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131 | .IX Title ""<STANDARD INPUT>" 1" |
134 | .IX Title "LIBEV 3" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH LIBEV 3 "2009-04-25" "libev-3.6" "libev - high performance full featured event loop" |
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137 | .\" way too many mistakes in technical documents. |
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138 | .if n .ad l |
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139 | .nh |
133 | .SH "NAME" |
140 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
141 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
142 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
144 | .Vb 1 |
138 | \& #include <ev.h> |
145 | \& #include <ev.h> |
139 | .Ve |
146 | .Ve |
140 | .SH "DESCRIPTION" |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
141 | .IX Header "DESCRIPTION" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
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149 | .Vb 2 |
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150 | \& // a single header file is required |
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151 | \& #include <ev.h> |
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152 | \& |
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153 | \& #include <stdio.h> // for puts |
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154 | \& |
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155 | \& // every watcher type has its own typedef\*(Aqd struct |
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156 | \& // with the name ev_TYPE |
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157 | \& ev_io stdin_watcher; |
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158 | \& ev_timer timeout_watcher; |
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159 | \& |
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160 | \& // all watcher callbacks have a similar signature |
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161 | \& // this callback is called when data is readable on stdin |
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162 | \& static void |
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163 | \& stdin_cb (EV_P_ ev_io *w, int revents) |
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164 | \& { |
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165 | \& puts ("stdin ready"); |
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166 | \& // for one\-shot events, one must manually stop the watcher |
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167 | \& // with its corresponding stop function. |
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168 | \& ev_io_stop (EV_A_ w); |
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169 | \& |
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170 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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171 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
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172 | \& } |
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173 | \& |
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174 | \& // another callback, this time for a time\-out |
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175 | \& static void |
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176 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
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177 | \& { |
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178 | \& puts ("timeout"); |
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179 | \& // this causes the innermost ev_loop to stop iterating |
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180 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
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181 | \& } |
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182 | \& |
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183 | \& int |
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184 | \& main (void) |
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185 | \& { |
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186 | \& // use the default event loop unless you have special needs |
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187 | \& struct ev_loop *loop = ev_default_loop (0); |
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188 | \& |
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189 | \& // initialise an io watcher, then start it |
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190 | \& // this one will watch for stdin to become readable |
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191 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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192 | \& ev_io_start (loop, &stdin_watcher); |
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193 | \& |
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194 | \& // initialise a timer watcher, then start it |
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195 | \& // simple non\-repeating 5.5 second timeout |
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196 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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197 | \& ev_timer_start (loop, &timeout_watcher); |
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198 | \& |
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199 | \& // now wait for events to arrive |
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200 | \& ev_loop (loop, 0); |
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201 | \& |
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202 | \& // unloop was called, so exit |
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203 | \& return 0; |
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204 | \& } |
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205 | .Ve |
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206 | .SH "ABOUT THIS DOCUMENT" |
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207 | .IX Header "ABOUT THIS DOCUMENT" |
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208 | This document documents the libev software package. |
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209 | .PP |
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210 | The newest version of this document is also available as an html-formatted |
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211 | web page you might find easier to navigate when reading it for the first |
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212 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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213 | .PP |
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214 | While this document tries to be as complete as possible in documenting |
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215 | libev, its usage and the rationale behind its design, it is not a tutorial |
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216 | on event-based programming, nor will it introduce event-based programming |
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217 | with libev. |
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218 | .PP |
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219 | Familarity with event based programming techniques in general is assumed |
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220 | throughout this document. |
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221 | .SH "ABOUT LIBEV" |
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222 | .IX Header "ABOUT LIBEV" |
142 | Libev is an event loop: you register interest in certain events (such as a |
223 | Libev is an event loop: you register interest in certain events (such as a |
143 | file descriptor being readable or a timeout occuring), and it will manage |
224 | file descriptor being readable or a timeout occurring), and it will manage |
144 | these event sources and provide your program with events. |
225 | these event sources and provide your program with events. |
145 | .PP |
226 | .PP |
146 | To do this, it must take more or less complete control over your process |
227 | To do this, it must take more or less complete control over your process |
147 | (or thread) by executing the \fIevent loop\fR handler, and will then |
228 | (or thread) by executing the \fIevent loop\fR handler, and will then |
148 | communicate events via a callback mechanism. |
229 | communicate events via a callback mechanism. |
149 | .PP |
230 | .PP |
150 | You register interest in certain events by registering so-called \fIevent |
231 | You register interest in certain events by registering so-called \fIevent |
151 | watchers\fR, which are relatively small C structures you initialise with the |
232 | watchers\fR, which are relatively small C structures you initialise with the |
152 | details of the event, and then hand it over to libev by \fIstarting\fR the |
233 | details of the event, and then hand it over to libev by \fIstarting\fR the |
153 | watcher. |
234 | watcher. |
154 | .SH "FEATURES" |
235 | .Sh "\s-1FEATURES\s0" |
155 | .IX Header "FEATURES" |
236 | .IX Subsection "FEATURES" |
156 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
237 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
157 | kqueue mechanisms for file descriptor events, relative timers, absolute |
238 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
158 | timers with customised rescheduling, signal events, process status change |
239 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
159 | events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event |
240 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
160 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
241 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
161 | fast (see this benchmark comparing |
242 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
162 | it to libevent for example). |
243 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
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244 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
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245 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
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246 | (\f(CW\*(C`ev_fork\*(C'\fR). |
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247 | .PP |
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248 | It also is quite fast (see this |
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249 | benchmark comparing it to libevent |
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250 | for example). |
163 | .SH "CONVENTIONS" |
251 | .Sh "\s-1CONVENTIONS\s0" |
164 | .IX Header "CONVENTIONS" |
252 | .IX Subsection "CONVENTIONS" |
165 | Libev is very configurable. In this manual the default configuration |
253 | Libev is very configurable. In this manual the default (and most common) |
166 | will be described, which supports multiple event loops. For more info |
254 | configuration will be described, which supports multiple event loops. For |
167 | about various configuration options please have a look at the file |
255 | more info about various configuration options please have a look at |
168 | \&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
169 | support for multiple event loops, then all functions taking an initial |
257 | for multiple event loops, then all functions taking an initial argument of |
170 | argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
171 | will not have this argument. |
259 | this argument. |
172 | .SH "TIME REPRESENTATION" |
260 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
173 | .IX Header "TIME REPRESENTATION" |
261 | .IX Subsection "TIME REPRESENTATION" |
174 | Libev represents time as a single floating point number, representing the |
262 | Libev represents time as a single floating point number, representing |
175 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
176 | the beginning of 1970, details are complicated, don't ask). This type is |
264 | near the beginning of 1970, details are complicated, don't ask). This |
177 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
265 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
178 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
266 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
179 | it, you should treat it as such. |
267 | on it, you should treat it as some floating point value. Unlike the name |
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268 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
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269 | throughout libev. |
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270 | .SH "ERROR HANDLING" |
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271 | .IX Header "ERROR HANDLING" |
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272 | Libev knows three classes of errors: operating system errors, usage errors |
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273 | and internal errors (bugs). |
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274 | .PP |
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275 | When libev catches an operating system error it cannot handle (for example |
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276 | a system call indicating a condition libev cannot fix), it calls the callback |
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277 | set via \f(CW\*(C`ev_set_syserr_cb\*(C'\fR, which is supposed to fix the problem or |
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278 | abort. The default is to print a diagnostic message and to call \f(CW\*(C`abort |
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279 | ()\*(C'\fR. |
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280 | .PP |
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281 | When libev detects a usage error such as a negative timer interval, then |
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282 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
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283 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
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284 | the libev caller and need to be fixed there. |
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285 | .PP |
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286 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
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287 | extensive consistency checking code. These do not trigger under normal |
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288 | circumstances, as they indicate either a bug in libev or worse. |
180 | .SH "GLOBAL FUNCTIONS" |
289 | .SH "GLOBAL FUNCTIONS" |
181 | .IX Header "GLOBAL FUNCTIONS" |
290 | .IX Header "GLOBAL FUNCTIONS" |
182 | These functions can be called anytime, even before initialising the |
291 | These functions can be called anytime, even before initialising the |
183 | library in any way. |
292 | library in any way. |
184 | .IP "ev_tstamp ev_time ()" 4 |
293 | .IP "ev_tstamp ev_time ()" 4 |
185 | .IX Item "ev_tstamp ev_time ()" |
294 | .IX Item "ev_tstamp ev_time ()" |
186 | Returns the current time as libev would use it. Please note that the |
295 | Returns the current time as libev would use it. Please note that the |
187 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
296 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
188 | you actually want to know. |
297 | you actually want to know. |
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298 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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299 | .IX Item "ev_sleep (ev_tstamp interval)" |
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300 | Sleep for the given interval: The current thread will be blocked until |
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301 | either it is interrupted or the given time interval has passed. Basically |
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302 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
189 | .IP "int ev_version_major ()" 4 |
303 | .IP "int ev_version_major ()" 4 |
190 | .IX Item "int ev_version_major ()" |
304 | .IX Item "int ev_version_major ()" |
191 | .PD 0 |
305 | .PD 0 |
192 | .IP "int ev_version_minor ()" 4 |
306 | .IP "int ev_version_minor ()" 4 |
193 | .IX Item "int ev_version_minor ()" |
307 | .IX Item "int ev_version_minor ()" |
194 | .PD |
308 | .PD |
195 | You can find out the major and minor version numbers of the library |
309 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
196 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
310 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
197 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
311 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
198 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
312 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
199 | version of the library your program was compiled against. |
313 | version of the library your program was compiled against. |
200 | .Sp |
314 | .Sp |
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315 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
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316 | release version. |
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317 | .Sp |
201 | Usually, it's a good idea to terminate if the major versions mismatch, |
318 | Usually, it's a good idea to terminate if the major versions mismatch, |
202 | as this indicates an incompatible change. Minor versions are usually |
319 | as this indicates an incompatible change. Minor versions are usually |
203 | compatible to older versions, so a larger minor version alone is usually |
320 | compatible to older versions, so a larger minor version alone is usually |
204 | not a problem. |
321 | not a problem. |
205 | .Sp |
322 | .Sp |
206 | Example: make sure we haven't accidentally been linked against the wrong |
323 | Example: Make sure we haven't accidentally been linked against the wrong |
207 | version: |
324 | version. |
208 | .Sp |
325 | .Sp |
209 | .Vb 3 |
326 | .Vb 3 |
210 | \& assert (("libev version mismatch", |
327 | \& assert (("libev version mismatch", |
211 | \& ev_version_major () == EV_VERSION_MAJOR |
328 | \& ev_version_major () == EV_VERSION_MAJOR |
212 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
329 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
213 | .Ve |
330 | .Ve |
214 | .IP "unsigned int ev_supported_backends ()" 4 |
331 | .IP "unsigned int ev_supported_backends ()" 4 |
215 | .IX Item "unsigned int ev_supported_backends ()" |
332 | .IX Item "unsigned int ev_supported_backends ()" |
216 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
333 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
217 | value) compiled into this binary of libev (independent of their |
334 | value) compiled into this binary of libev (independent of their |
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220 | .Sp |
337 | .Sp |
221 | Example: make sure we have the epoll method, because yeah this is cool and |
338 | Example: make sure we have the epoll method, because yeah this is cool and |
222 | a must have and can we have a torrent of it please!!!11 |
339 | a must have and can we have a torrent of it please!!!11 |
223 | .Sp |
340 | .Sp |
224 | .Vb 2 |
341 | .Vb 2 |
225 | \& assert (("sorry, no epoll, no sex", |
342 | \& assert (("sorry, no epoll, no sex", |
226 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
343 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
227 | .Ve |
344 | .Ve |
228 | .IP "unsigned int ev_recommended_backends ()" 4 |
345 | .IP "unsigned int ev_recommended_backends ()" 4 |
229 | .IX Item "unsigned int ev_recommended_backends ()" |
346 | .IX Item "unsigned int ev_recommended_backends ()" |
230 | Return the set of all backends compiled into this binary of libev and also |
347 | Return the set of all backends compiled into this binary of libev and also |
231 | recommended for this platform. This set is often smaller than the one |
348 | recommended for this platform. This set is often smaller than the one |
232 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
349 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
233 | most BSDs and will not be autodetected unless you explicitly request it |
350 | most BSDs and will not be auto-detected unless you explicitly request it |
234 | (assuming you know what you are doing). This is the set of backends that |
351 | (assuming you know what you are doing). This is the set of backends that |
235 | libev will probe for if you specify no backends explicitly. |
352 | libev will probe for if you specify no backends explicitly. |
236 | .IP "unsigned int ev_embeddable_backends ()" 4 |
353 | .IP "unsigned int ev_embeddable_backends ()" 4 |
237 | .IX Item "unsigned int ev_embeddable_backends ()" |
354 | .IX Item "unsigned int ev_embeddable_backends ()" |
238 | Returns the set of backends that are embeddable in other event loops. This |
355 | Returns the set of backends that are embeddable in other event loops. This |
239 | is the theoretical, all\-platform, value. To find which backends |
356 | is the theoretical, all-platform, value. To find which backends |
240 | might be supported on the current system, you would need to look at |
357 | might be supported on the current system, you would need to look at |
241 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
358 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
242 | recommended ones. |
359 | recommended ones. |
243 | .Sp |
360 | .Sp |
244 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
361 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
245 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
362 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
246 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
363 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
247 | Sets the allocation function to use (the prototype is similar to the |
364 | Sets the allocation function to use (the prototype is similar \- the |
248 | realloc C function, the semantics are identical). It is used to allocate |
365 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
249 | and free memory (no surprises here). If it returns zero when memory |
366 | used to allocate and free memory (no surprises here). If it returns zero |
250 | needs to be allocated, the library might abort or take some potentially |
367 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
251 | destructive action. The default is your system realloc function. |
368 | or take some potentially destructive action. |
|
|
369 | .Sp |
|
|
370 | Since some systems (at least OpenBSD and Darwin) fail to implement |
|
|
371 | correct \f(CW\*(C`realloc\*(C'\fR semantics, libev will use a wrapper around the system |
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|
372 | \&\f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions by default. |
252 | .Sp |
373 | .Sp |
253 | You could override this function in high-availability programs to, say, |
374 | You could override this function in high-availability programs to, say, |
254 | free some memory if it cannot allocate memory, to use a special allocator, |
375 | free some memory if it cannot allocate memory, to use a special allocator, |
255 | or even to sleep a while and retry until some memory is available. |
376 | or even to sleep a while and retry until some memory is available. |
256 | .Sp |
377 | .Sp |
257 | Example: replace the libev allocator with one that waits a bit and then |
378 | Example: Replace the libev allocator with one that waits a bit and then |
258 | retries: better than mine). |
379 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
259 | .Sp |
380 | .Sp |
260 | .Vb 6 |
381 | .Vb 6 |
261 | \& static void * |
382 | \& static void * |
262 | \& persistent_realloc (void *ptr, long size) |
383 | \& persistent_realloc (void *ptr, size_t size) |
263 | \& { |
384 | \& { |
264 | \& for (;;) |
385 | \& for (;;) |
265 | \& { |
386 | \& { |
266 | \& void *newptr = realloc (ptr, size); |
387 | \& void *newptr = realloc (ptr, size); |
267 | .Ve |
388 | \& |
268 | .Sp |
|
|
269 | .Vb 2 |
|
|
270 | \& if (newptr) |
389 | \& if (newptr) |
271 | \& return newptr; |
390 | \& return newptr; |
272 | .Ve |
391 | \& |
273 | .Sp |
|
|
274 | .Vb 3 |
|
|
275 | \& sleep (60); |
392 | \& sleep (60); |
276 | \& } |
393 | \& } |
277 | \& } |
394 | \& } |
278 | .Ve |
395 | \& |
279 | .Sp |
|
|
280 | .Vb 2 |
|
|
281 | \& ... |
396 | \& ... |
282 | \& ev_set_allocator (persistent_realloc); |
397 | \& ev_set_allocator (persistent_realloc); |
283 | .Ve |
398 | .Ve |
284 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
399 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
285 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
400 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
286 | Set the callback function to call on a retryable syscall error (such |
401 | Set the callback function to call on a retryable system call error (such |
287 | as failed select, poll, epoll_wait). The message is a printable string |
402 | as failed select, poll, epoll_wait). The message is a printable string |
288 | indicating the system call or subsystem causing the problem. If this |
403 | indicating the system call or subsystem causing the problem. If this |
289 | callback is set, then libev will expect it to remedy the sitution, no |
404 | callback is set, then libev will expect it to remedy the situation, no |
290 | matter what, when it returns. That is, libev will generally retry the |
405 | matter what, when it returns. That is, libev will generally retry the |
291 | requested operation, or, if the condition doesn't go away, do bad stuff |
406 | requested operation, or, if the condition doesn't go away, do bad stuff |
292 | (such as abort). |
407 | (such as abort). |
293 | .Sp |
408 | .Sp |
294 | Example: do the same thing as libev does internally: |
409 | Example: This is basically the same thing that libev does internally, too. |
295 | .Sp |
410 | .Sp |
296 | .Vb 6 |
411 | .Vb 6 |
297 | \& static void |
412 | \& static void |
298 | \& fatal_error (const char *msg) |
413 | \& fatal_error (const char *msg) |
299 | \& { |
414 | \& { |
300 | \& perror (msg); |
415 | \& perror (msg); |
301 | \& abort (); |
416 | \& abort (); |
302 | \& } |
417 | \& } |
303 | .Ve |
418 | \& |
304 | .Sp |
|
|
305 | .Vb 2 |
|
|
306 | \& ... |
419 | \& ... |
307 | \& ev_set_syserr_cb (fatal_error); |
420 | \& ev_set_syserr_cb (fatal_error); |
308 | .Ve |
421 | .Ve |
309 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
422 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
310 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
423 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
311 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
424 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
312 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
425 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
313 | events, and dynamically created loops which do not. |
426 | \&\fIfunction\fR). |
314 | .PP |
427 | .PP |
315 | If you use threads, a common model is to run the default event loop |
428 | The library knows two types of such loops, the \fIdefault\fR loop, which |
316 | in your main thread (or in a separate thread) and for each thread you |
429 | supports signals and child events, and dynamically created loops which do |
317 | create, you also create another event loop. Libev itself does no locking |
430 | not. |
318 | whatsoever, so if you mix calls to the same event loop in different |
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319 | threads, make sure you lock (this is usually a bad idea, though, even if |
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320 | done correctly, because it's hideous and inefficient). |
|
|
321 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
431 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
322 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
432 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
323 | This will initialise the default event loop if it hasn't been initialised |
433 | This will initialise the default event loop if it hasn't been initialised |
324 | yet and return it. If the default loop could not be initialised, returns |
434 | yet and return it. If the default loop could not be initialised, returns |
325 | false. If it already was initialised it simply returns it (and ignores the |
435 | false. If it already was initialised it simply returns it (and ignores the |
326 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
436 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
327 | .Sp |
437 | .Sp |
328 | If you don't know what event loop to use, use the one returned from this |
438 | If you don't know what event loop to use, use the one returned from this |
329 | function. |
439 | function. |
|
|
440 | .Sp |
|
|
441 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
|
|
442 | from multiple threads, you have to lock (note also that this is unlikely, |
|
|
443 | as loops cannot be shared easily between threads anyway). |
|
|
444 | .Sp |
|
|
445 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
|
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446 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
|
|
447 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
|
|
448 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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449 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
|
|
450 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
330 | .Sp |
451 | .Sp |
331 | The flags argument can be used to specify special behaviour or specific |
452 | The flags argument can be used to specify special behaviour or specific |
332 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
453 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
333 | .Sp |
454 | .Sp |
334 | The following flags are supported: |
455 | The following flags are supported: |
… | |
… | |
339 | The default flags value. Use this if you have no clue (it's the right |
460 | The default flags value. Use this if you have no clue (it's the right |
340 | thing, believe me). |
461 | thing, believe me). |
341 | .ie n .IP """EVFLAG_NOENV""" 4 |
462 | .ie n .IP """EVFLAG_NOENV""" 4 |
342 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
463 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
343 | .IX Item "EVFLAG_NOENV" |
464 | .IX Item "EVFLAG_NOENV" |
344 | If this flag bit is ored into the flag value (or the program runs setuid |
465 | If this flag bit is or'ed into the flag value (or the program runs setuid |
345 | or setgid) then libev will \fInot\fR look at the environment variable |
466 | or setgid) then libev will \fInot\fR look at the environment variable |
346 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
467 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
347 | override the flags completely if it is found in the environment. This is |
468 | override the flags completely if it is found in the environment. This is |
348 | useful to try out specific backends to test their performance, or to work |
469 | useful to try out specific backends to test their performance, or to work |
349 | around bugs. |
470 | around bugs. |
|
|
471 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
|
|
472 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
|
|
473 | .IX Item "EVFLAG_FORKCHECK" |
|
|
474 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
|
|
475 | a fork, you can also make libev check for a fork in each iteration by |
|
|
476 | enabling this flag. |
|
|
477 | .Sp |
|
|
478 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
|
|
479 | and thus this might slow down your event loop if you do a lot of loop |
|
|
480 | iterations and little real work, but is usually not noticeable (on my |
|
|
481 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
|
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482 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
|
|
483 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
|
|
484 | .Sp |
|
|
485 | The big advantage of this flag is that you can forget about fork (and |
|
|
486 | forget about forgetting to tell libev about forking) when you use this |
|
|
487 | flag. |
|
|
488 | .Sp |
|
|
489 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
|
|
490 | environment variable. |
350 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
491 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
351 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
492 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
352 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
493 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
353 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
494 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
354 | libev tries to roll its own fd_set with no limits on the number of fds, |
495 | libev tries to roll its own fd_set with no limits on the number of fds, |
355 | but if that fails, expect a fairly low limit on the number of fds when |
496 | but if that fails, expect a fairly low limit on the number of fds when |
356 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
497 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
357 | the fastest backend for a low number of fds. |
498 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
499 | .Sp |
|
|
500 | To get good performance out of this backend you need a high amount of |
|
|
501 | parallelism (most of the file descriptors should be busy). If you are |
|
|
502 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
|
|
503 | connections as possible during one iteration. You might also want to have |
|
|
504 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
|
|
505 | readiness notifications you get per iteration. |
|
|
506 | .Sp |
|
|
507 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
|
|
508 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
|
|
509 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
358 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
510 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
359 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
511 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
360 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
512 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
361 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
513 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
362 | select, but handles sparse fds better and has no artificial limit on the |
514 | than select, but handles sparse fds better and has no artificial |
363 | number of fds you can use (except it will slow down considerably with a |
515 | limit on the number of fds you can use (except it will slow down |
364 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
516 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
517 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
|
|
518 | performance tips. |
|
|
519 | .Sp |
|
|
520 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
|
|
521 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
365 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
522 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
366 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
523 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
367 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
524 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
368 | For few fds, this backend is a bit little slower than poll and select, |
525 | For few fds, this backend is a bit little slower than poll and select, |
369 | but it scales phenomenally better. While poll and select usually scale like |
526 | but it scales phenomenally better. While poll and select usually scale |
370 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
527 | like O(total_fds) where n is the total number of fds (or the highest fd), |
371 | either O(1) or O(active_fds). |
528 | epoll scales either O(1) or O(active_fds). |
372 | .Sp |
529 | .Sp |
|
|
530 | The epoll mechanism deserves honorable mention as the most misdesigned |
|
|
531 | of the more advanced event mechanisms: mere annoyances include silently |
|
|
532 | dropping file descriptors, requiring a system call per change per file |
|
|
533 | descriptor (and unnecessary guessing of parameters), problems with dup and |
|
|
534 | so on. The biggest issue is fork races, however \- if a program forks then |
|
|
535 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
|
|
536 | take considerable time (one syscall per file descriptor) and is of course |
|
|
537 | hard to detect. |
|
|
538 | .Sp |
|
|
539 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
|
|
540 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
|
|
541 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
|
|
542 | even remove them from the set) than registered in the set (especially |
|
|
543 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
|
|
544 | employing an additional generation counter and comparing that against the |
|
|
545 | events to filter out spurious ones, recreating the set when required. |
|
|
546 | .Sp |
373 | While stopping and starting an I/O watcher in the same iteration will |
547 | While stopping, setting and starting an I/O watcher in the same iteration |
374 | result in some caching, there is still a syscall per such incident |
548 | will result in some caching, there is still a system call per such |
375 | (because the fd could point to a different file description now), so its |
549 | incident (because the same \fIfile descriptor\fR could point to a different |
376 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
550 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
377 | well if you register events for both fds. |
551 | file descriptors might not work very well if you register events for both |
|
|
552 | file descriptors. |
378 | .Sp |
553 | .Sp |
379 | Please note that epoll sometimes generates spurious notifications, so you |
554 | Best performance from this backend is achieved by not unregistering all |
380 | need to use non-blocking I/O or other means to avoid blocking when no data |
555 | watchers for a file descriptor until it has been closed, if possible, |
381 | (or space) is available. |
556 | i.e. keep at least one watcher active per fd at all times. Stopping and |
|
|
557 | starting a watcher (without re-setting it) also usually doesn't cause |
|
|
558 | extra overhead. A fork can both result in spurious notifications as well |
|
|
559 | as in libev having to destroy and recreate the epoll object, which can |
|
|
560 | take considerable time and thus should be avoided. |
|
|
561 | .Sp |
|
|
562 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
|
|
563 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
564 | the usage. So sad. |
|
|
565 | .Sp |
|
|
566 | While nominally embeddable in other event loops, this feature is broken in |
|
|
567 | all kernel versions tested so far. |
|
|
568 | .Sp |
|
|
569 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
570 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
382 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
571 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
383 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
572 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
384 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
573 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
385 | Kqueue deserves special mention, as at the time of this writing, it |
574 | Kqueue deserves special mention, as at the time of this writing, it |
386 | was broken on all BSDs except NetBSD (usually it doesn't work with |
575 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
387 | anything but sockets and pipes, except on Darwin, where of course its |
576 | with anything but sockets and pipes, except on Darwin, where of course |
388 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
577 | it's completely useless). Unlike epoll, however, whose brokenness |
|
|
578 | is by design, these kqueue bugs can (and eventually will) be fixed |
|
|
579 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
389 | unless you explicitly specify it explicitly in the flags (i.e. using |
580 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
390 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
581 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
582 | system like NetBSD. |
|
|
583 | .Sp |
|
|
584 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
585 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
586 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
391 | .Sp |
587 | .Sp |
392 | It scales in the same way as the epoll backend, but the interface to the |
588 | It scales in the same way as the epoll backend, but the interface to the |
393 | kernel is more efficient (which says nothing about its actual speed, of |
589 | kernel is more efficient (which says nothing about its actual speed, of |
394 | course). While starting and stopping an I/O watcher does not cause an |
590 | course). While stopping, setting and starting an I/O watcher does never |
395 | extra syscall as with epoll, it still adds up to four event changes per |
591 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
396 | incident, so its best to avoid that. |
592 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
|
|
593 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
594 | cases |
|
|
595 | .Sp |
|
|
596 | This backend usually performs well under most conditions. |
|
|
597 | .Sp |
|
|
598 | While nominally embeddable in other event loops, this doesn't work |
|
|
599 | everywhere, so you might need to test for this. And since it is broken |
|
|
600 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
601 | (for which it usually works), by embedding it into another event loop |
|
|
602 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
|
|
603 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
|
|
604 | .Sp |
|
|
605 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
|
|
606 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
|
|
607 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
397 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
608 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
398 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
609 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
399 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
610 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
400 | This is not implemented yet (and might never be). |
611 | This is not implemented yet (and might never be, unless you send me an |
|
|
612 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
613 | and is not embeddable, which would limit the usefulness of this backend |
|
|
614 | immensely. |
401 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
615 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
402 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
616 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
403 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
617 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
404 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
618 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
405 | it's really slow, but it still scales very well (O(active_fds)). |
619 | it's really slow, but it still scales very well (O(active_fds)). |
406 | .Sp |
620 | .Sp |
407 | Please note that solaris ports can result in a lot of spurious |
621 | Please note that Solaris event ports can deliver a lot of spurious |
408 | notifications, so you need to use non-blocking I/O or other means to avoid |
622 | notifications, so you need to use non-blocking I/O or other means to avoid |
409 | blocking when no data (or space) is available. |
623 | blocking when no data (or space) is available. |
|
|
624 | .Sp |
|
|
625 | While this backend scales well, it requires one system call per active |
|
|
626 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
627 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
628 | might perform better. |
|
|
629 | .Sp |
|
|
630 | On the positive side, with the exception of the spurious readiness |
|
|
631 | notifications, this backend actually performed fully to specification |
|
|
632 | in all tests and is fully embeddable, which is a rare feat among the |
|
|
633 | OS-specific backends (I vastly prefer correctness over speed hacks). |
|
|
634 | .Sp |
|
|
635 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
636 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
410 | .ie n .IP """EVBACKEND_ALL""" 4 |
637 | .ie n .IP """EVBACKEND_ALL""" 4 |
411 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
638 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
412 | .IX Item "EVBACKEND_ALL" |
639 | .IX Item "EVBACKEND_ALL" |
413 | Try all backends (even potentially broken ones that wouldn't be tried |
640 | Try all backends (even potentially broken ones that wouldn't be tried |
414 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
641 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
415 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
642 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
643 | .Sp |
|
|
644 | It is definitely not recommended to use this flag. |
416 | .RE |
645 | .RE |
417 | .RS 4 |
646 | .RS 4 |
418 | .Sp |
647 | .Sp |
419 | If one or more of these are ored into the flags value, then only these |
648 | If one or more of these are or'ed into the flags value, then only these |
420 | backends will be tried (in the reverse order as given here). If none are |
649 | backends will be tried (in the reverse order as listed here). If none are |
421 | specified, most compiled-in backend will be tried, usually in reverse |
650 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
422 | order of their flag values :) |
|
|
423 | .Sp |
651 | .Sp |
424 | The most typical usage is like this: |
652 | Example: This is the most typical usage. |
425 | .Sp |
653 | .Sp |
426 | .Vb 2 |
654 | .Vb 2 |
427 | \& if (!ev_default_loop (0)) |
655 | \& if (!ev_default_loop (0)) |
428 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
656 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
429 | .Ve |
657 | .Ve |
430 | .Sp |
658 | .Sp |
431 | Restrict libev to the select and poll backends, and do not allow |
659 | Example: Restrict libev to the select and poll backends, and do not allow |
432 | environment settings to be taken into account: |
660 | environment settings to be taken into account: |
433 | .Sp |
661 | .Sp |
434 | .Vb 1 |
662 | .Vb 1 |
435 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
663 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
436 | .Ve |
664 | .Ve |
437 | .Sp |
665 | .Sp |
438 | Use whatever libev has to offer, but make sure that kqueue is used if |
666 | Example: Use whatever libev has to offer, but make sure that kqueue is |
439 | available (warning, breaks stuff, best use only with your own private |
667 | used if available (warning, breaks stuff, best use only with your own |
440 | event loop and only if you know the \s-1OS\s0 supports your types of fds): |
668 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
669 | fds): |
441 | .Sp |
670 | .Sp |
442 | .Vb 1 |
671 | .Vb 1 |
443 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
672 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
444 | .Ve |
673 | .Ve |
445 | .RE |
674 | .RE |
446 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
675 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
447 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
676 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
448 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
677 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
449 | always distinct from the default loop. Unlike the default loop, it cannot |
678 | always distinct from the default loop. Unlike the default loop, it cannot |
450 | handle signal and child watchers, and attempts to do so will be greeted by |
679 | handle signal and child watchers, and attempts to do so will be greeted by |
451 | undefined behaviour (or a failed assertion if assertions are enabled). |
680 | undefined behaviour (or a failed assertion if assertions are enabled). |
452 | .Sp |
681 | .Sp |
|
|
682 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
683 | libev with threads is indeed to create one loop per thread, and using the |
|
|
684 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
685 | .Sp |
453 | Example: try to create a event loop that uses epoll and nothing else. |
686 | Example: Try to create a event loop that uses epoll and nothing else. |
454 | .Sp |
687 | .Sp |
455 | .Vb 3 |
688 | .Vb 3 |
456 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
689 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
457 | \& if (!epoller) |
690 | \& if (!epoller) |
458 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
691 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
459 | .Ve |
692 | .Ve |
460 | .IP "ev_default_destroy ()" 4 |
693 | .IP "ev_default_destroy ()" 4 |
461 | .IX Item "ev_default_destroy ()" |
694 | .IX Item "ev_default_destroy ()" |
462 | Destroys the default loop again (frees all memory and kernel state |
695 | Destroys the default loop again (frees all memory and kernel state |
463 | etc.). None of the active event watchers will be stopped in the normal |
696 | etc.). None of the active event watchers will be stopped in the normal |
464 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
697 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
465 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
698 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
466 | calling this function, or cope with the fact afterwards (which is usually |
699 | calling this function, or cope with the fact afterwards (which is usually |
467 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
700 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
468 | for example). |
701 | for example). |
|
|
702 | .Sp |
|
|
703 | Note that certain global state, such as signal state (and installed signal |
|
|
704 | handlers), will not be freed by this function, and related watchers (such |
|
|
705 | as signal and child watchers) would need to be stopped manually. |
|
|
706 | .Sp |
|
|
707 | In general it is not advisable to call this function except in the |
|
|
708 | rare occasion where you really need to free e.g. the signal handling |
|
|
709 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
710 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
469 | .IP "ev_loop_destroy (loop)" 4 |
711 | .IP "ev_loop_destroy (loop)" 4 |
470 | .IX Item "ev_loop_destroy (loop)" |
712 | .IX Item "ev_loop_destroy (loop)" |
471 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
713 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
472 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
714 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
473 | .IP "ev_default_fork ()" 4 |
715 | .IP "ev_default_fork ()" 4 |
474 | .IX Item "ev_default_fork ()" |
716 | .IX Item "ev_default_fork ()" |
|
|
717 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
475 | This function reinitialises the kernel state for backends that have |
718 | to reinitialise the kernel state for backends that have one. Despite the |
476 | one. Despite the name, you can call it anytime, but it makes most sense |
719 | name, you can call it anytime, but it makes most sense after forking, in |
477 | after forking, in either the parent or child process (or both, but that |
720 | the child process (or both child and parent, but that again makes little |
478 | again makes little sense). |
721 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
722 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
479 | .Sp |
723 | .Sp |
480 | You \fImust\fR call this function in the child process after forking if and |
724 | On the other hand, you only need to call this function in the child |
481 | only if you want to use the event library in both processes. If you just |
725 | process if and only if you want to use the event library in the child. If |
482 | fork+exec, you don't have to call it. |
726 | you just fork+exec, you don't have to call it at all. |
483 | .Sp |
727 | .Sp |
484 | The function itself is quite fast and it's usually not a problem to call |
728 | The function itself is quite fast and it's usually not a problem to call |
485 | it just in case after a fork. To make this easy, the function will fit in |
729 | it just in case after a fork. To make this easy, the function will fit in |
486 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
730 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
487 | .Sp |
731 | .Sp |
488 | .Vb 1 |
732 | .Vb 1 |
489 | \& pthread_atfork (0, 0, ev_default_fork); |
733 | \& pthread_atfork (0, 0, ev_default_fork); |
490 | .Ve |
734 | .Ve |
491 | .Sp |
|
|
492 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
493 | without calling this function, so if you force one of those backends you |
|
|
494 | do not need to care. |
|
|
495 | .IP "ev_loop_fork (loop)" 4 |
735 | .IP "ev_loop_fork (loop)" 4 |
496 | .IX Item "ev_loop_fork (loop)" |
736 | .IX Item "ev_loop_fork (loop)" |
497 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
737 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
498 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
738 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
499 | after fork, and how you do this is entirely your own problem. |
739 | after fork that you want to re-use in the child, and how you do this is |
|
|
740 | entirely your own problem. |
|
|
741 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
742 | .IX Item "int ev_is_default_loop (loop)" |
|
|
743 | Returns true when the given loop is, in fact, the default loop, and false |
|
|
744 | otherwise. |
|
|
745 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
746 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
747 | Returns the count of loop iterations for the loop, which is identical to |
|
|
748 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
749 | happily wraps around with enough iterations. |
|
|
750 | .Sp |
|
|
751 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
752 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
753 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
500 | .IP "unsigned int ev_backend (loop)" 4 |
754 | .IP "unsigned int ev_backend (loop)" 4 |
501 | .IX Item "unsigned int ev_backend (loop)" |
755 | .IX Item "unsigned int ev_backend (loop)" |
502 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
756 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
503 | use. |
757 | use. |
504 | .IP "ev_tstamp ev_now (loop)" 4 |
758 | .IP "ev_tstamp ev_now (loop)" 4 |
505 | .IX Item "ev_tstamp ev_now (loop)" |
759 | .IX Item "ev_tstamp ev_now (loop)" |
506 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
760 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
507 | received events and started processing them. This timestamp does not |
761 | received events and started processing them. This timestamp does not |
508 | change as long as callbacks are being processed, and this is also the base |
762 | change as long as callbacks are being processed, and this is also the base |
509 | time used for relative timers. You can treat it as the timestamp of the |
763 | time used for relative timers. You can treat it as the timestamp of the |
510 | event occuring (or more correctly, libev finding out about it). |
764 | event occurring (or more correctly, libev finding out about it). |
|
|
765 | .IP "ev_now_update (loop)" 4 |
|
|
766 | .IX Item "ev_now_update (loop)" |
|
|
767 | Establishes the current time by querying the kernel, updating the time |
|
|
768 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
|
|
769 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
|
|
770 | .Sp |
|
|
771 | This function is rarely useful, but when some event callback runs for a |
|
|
772 | very long time without entering the event loop, updating libev's idea of |
|
|
773 | the current time is a good idea. |
|
|
774 | .Sp |
|
|
775 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
|
|
776 | .IP "ev_suspend (loop)" 4 |
|
|
777 | .IX Item "ev_suspend (loop)" |
|
|
778 | .PD 0 |
|
|
779 | .IP "ev_resume (loop)" 4 |
|
|
780 | .IX Item "ev_resume (loop)" |
|
|
781 | .PD |
|
|
782 | These two functions suspend and resume a loop, for use when the loop is |
|
|
783 | not used for a while and timeouts should not be processed. |
|
|
784 | .Sp |
|
|
785 | A typical use case would be an interactive program such as a game: When |
|
|
786 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
|
|
787 | would be best to handle timeouts as if no time had actually passed while |
|
|
788 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
789 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
|
|
790 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
|
|
791 | .Sp |
|
|
792 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
|
|
793 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
|
|
794 | will be rescheduled (that is, they will lose any events that would have |
|
|
795 | occured while suspended). |
|
|
796 | .Sp |
|
|
797 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
|
|
798 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
|
|
799 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
|
|
800 | .Sp |
|
|
801 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
|
|
802 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
511 | .IP "ev_loop (loop, int flags)" 4 |
803 | .IP "ev_loop (loop, int flags)" 4 |
512 | .IX Item "ev_loop (loop, int flags)" |
804 | .IX Item "ev_loop (loop, int flags)" |
513 | Finally, this is it, the event handler. This function usually is called |
805 | Finally, this is it, the event handler. This function usually is called |
514 | after you initialised all your watchers and you want to start handling |
806 | after you initialised all your watchers and you want to start handling |
515 | events. |
807 | events. |
… | |
… | |
517 | If the flags argument is specified as \f(CW0\fR, it will not return until |
809 | If the flags argument is specified as \f(CW0\fR, it will not return until |
518 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
810 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
519 | .Sp |
811 | .Sp |
520 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
812 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
521 | relying on all watchers to be stopped when deciding when a program has |
813 | relying on all watchers to be stopped when deciding when a program has |
522 | finished (especially in interactive programs), but having a program that |
814 | finished (especially in interactive programs), but having a program |
523 | automatically loops as long as it has to and no longer by virtue of |
815 | that automatically loops as long as it has to and no longer by virtue |
524 | relying on its watchers stopping correctly is a thing of beauty. |
816 | of relying on its watchers stopping correctly, that is truly a thing of |
|
|
817 | beauty. |
525 | .Sp |
818 | .Sp |
526 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
819 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
527 | those events and any outstanding ones, but will not block your process in |
820 | those events and any already outstanding ones, but will not block your |
528 | case there are no events and will return after one iteration of the loop. |
821 | process in case there are no events and will return after one iteration of |
|
|
822 | the loop. |
529 | .Sp |
823 | .Sp |
530 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
824 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
531 | neccessary) and will handle those and any outstanding ones. It will block |
825 | necessary) and will handle those and any already outstanding ones. It |
532 | your process until at least one new event arrives, and will return after |
826 | will block your process until at least one new event arrives (which could |
533 | one iteration of the loop. This is useful if you are waiting for some |
827 | be an event internal to libev itself, so there is no guarantee that a |
534 | external event in conjunction with something not expressible using other |
828 | user-registered callback will be called), and will return after one |
|
|
829 | iteration of the loop. |
|
|
830 | .Sp |
|
|
831 | This is useful if you are waiting for some external event in conjunction |
|
|
832 | with something not expressible using other libev watchers (i.e. "roll your |
535 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
833 | own \f(CW\*(C`ev_loop\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
536 | usually a better approach for this kind of thing. |
834 | usually a better approach for this kind of thing. |
537 | .Sp |
835 | .Sp |
538 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
836 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
539 | .Sp |
837 | .Sp |
540 | .Vb 18 |
838 | .Vb 10 |
541 | \& * If there are no active watchers (reference count is zero), return. |
839 | \& \- Before the first iteration, call any pending watchers. |
542 | \& - Queue prepare watchers and then call all outstanding watchers. |
840 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
841 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
|
|
842 | \& \- Queue and call all prepare watchers. |
543 | \& - If we have been forked, recreate the kernel state. |
843 | \& \- If we have been forked, detach and recreate the kernel state |
|
|
844 | \& as to not disturb the other process. |
544 | \& - Update the kernel state with all outstanding changes. |
845 | \& \- Update the kernel state with all outstanding changes. |
545 | \& - Update the "event loop time". |
846 | \& \- Update the "event loop time" (ev_now ()). |
546 | \& - Calculate for how long to block. |
847 | \& \- Calculate for how long to sleep or block, if at all |
|
|
848 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
849 | \& any active watchers at all will result in not sleeping). |
|
|
850 | \& \- Sleep if the I/O and timer collect interval say so. |
547 | \& - Block the process, waiting for any events. |
851 | \& \- Block the process, waiting for any events. |
548 | \& - Queue all outstanding I/O (fd) events. |
852 | \& \- Queue all outstanding I/O (fd) events. |
549 | \& - Update the "event loop time" and do time jump handling. |
853 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
550 | \& - Queue all outstanding timers. |
854 | \& \- Queue all expired timers. |
551 | \& - Queue all outstanding periodics. |
855 | \& \- Queue all expired periodics. |
552 | \& - If no events are pending now, queue all idle watchers. |
856 | \& \- Unless any events are pending now, queue all idle watchers. |
553 | \& - Queue all check watchers. |
857 | \& \- Queue all check watchers. |
554 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
858 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
555 | \& Signals and child watchers are implemented as I/O watchers, and will |
859 | \& Signals and child watchers are implemented as I/O watchers, and will |
556 | \& be handled here by queueing them when their watcher gets executed. |
860 | \& be handled here by queueing them when their watcher gets executed. |
557 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
861 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
558 | \& were used, return, otherwise continue with step *. |
862 | \& were used, or there are no active watchers, return, otherwise |
|
|
863 | \& continue with step *. |
559 | .Ve |
864 | .Ve |
560 | .Sp |
865 | .Sp |
561 | Example: queue some jobs and then loop until no events are outsanding |
866 | Example: Queue some jobs and then loop until no events are outstanding |
562 | anymore. |
867 | anymore. |
563 | .Sp |
868 | .Sp |
564 | .Vb 4 |
869 | .Vb 4 |
565 | \& ... queue jobs here, make sure they register event watchers as long |
870 | \& ... queue jobs here, make sure they register event watchers as long |
566 | \& ... as they still have work to do (even an idle watcher will do..) |
871 | \& ... as they still have work to do (even an idle watcher will do..) |
567 | \& ev_loop (my_loop, 0); |
872 | \& ev_loop (my_loop, 0); |
568 | \& ... jobs done. yeah! |
873 | \& ... jobs done or somebody called unloop. yeah! |
569 | .Ve |
874 | .Ve |
570 | .IP "ev_unloop (loop, how)" 4 |
875 | .IP "ev_unloop (loop, how)" 4 |
571 | .IX Item "ev_unloop (loop, how)" |
876 | .IX Item "ev_unloop (loop, how)" |
572 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
877 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
573 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
878 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
574 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
879 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
575 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
880 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
881 | .Sp |
|
|
882 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
|
|
883 | .Sp |
|
|
884 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
576 | .IP "ev_ref (loop)" 4 |
885 | .IP "ev_ref (loop)" 4 |
577 | .IX Item "ev_ref (loop)" |
886 | .IX Item "ev_ref (loop)" |
578 | .PD 0 |
887 | .PD 0 |
579 | .IP "ev_unref (loop)" 4 |
888 | .IP "ev_unref (loop)" 4 |
580 | .IX Item "ev_unref (loop)" |
889 | .IX Item "ev_unref (loop)" |
581 | .PD |
890 | .PD |
582 | Ref/unref can be used to add or remove a reference count on the event |
891 | Ref/unref can be used to add or remove a reference count on the event |
583 | loop: Every watcher keeps one reference, and as long as the reference |
892 | loop: Every watcher keeps one reference, and as long as the reference |
584 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. If you have |
893 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
|
|
894 | .Sp |
585 | a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
895 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
586 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
896 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
|
|
897 | stopping it. |
|
|
898 | .Sp |
587 | example, libev itself uses this for its internal signal pipe: It is not |
899 | As an example, libev itself uses this for its internal signal pipe: It |
588 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
900 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
589 | no event watchers registered by it are active. It is also an excellent |
901 | exiting if no event watchers registered by it are active. It is also an |
590 | way to do this for generic recurring timers or from within third-party |
902 | excellent way to do this for generic recurring timers or from within |
591 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
903 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
|
|
904 | before stop\fR (but only if the watcher wasn't active before, or was active |
|
|
905 | before, respectively. Note also that libev might stop watchers itself |
|
|
906 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
|
|
907 | in the callback). |
592 | .Sp |
908 | .Sp |
593 | Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
909 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
594 | running when nothing else is active. |
910 | running when nothing else is active. |
595 | .Sp |
911 | .Sp |
596 | .Vb 4 |
912 | .Vb 4 |
597 | \& struct dv_signal exitsig; |
913 | \& ev_signal exitsig; |
598 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
914 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
599 | \& ev_signal_start (myloop, &exitsig); |
915 | \& ev_signal_start (loop, &exitsig); |
600 | \& evf_unref (myloop); |
916 | \& evf_unref (loop); |
601 | .Ve |
917 | .Ve |
602 | .Sp |
918 | .Sp |
603 | Example: for some weird reason, unregister the above signal handler again. |
919 | Example: For some weird reason, unregister the above signal handler again. |
604 | .Sp |
920 | .Sp |
605 | .Vb 2 |
921 | .Vb 2 |
606 | \& ev_ref (myloop); |
922 | \& ev_ref (loop); |
607 | \& ev_signal_stop (myloop, &exitsig); |
923 | \& ev_signal_stop (loop, &exitsig); |
608 | .Ve |
924 | .Ve |
|
|
925 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
926 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
927 | .PD 0 |
|
|
928 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
929 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
930 | .PD |
|
|
931 | These advanced functions influence the time that libev will spend waiting |
|
|
932 | for events. Both time intervals are by default \f(CW0\fR, meaning that libev |
|
|
933 | will try to invoke timer/periodic callbacks and I/O callbacks with minimum |
|
|
934 | latency. |
|
|
935 | .Sp |
|
|
936 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
937 | allows libev to delay invocation of I/O and timer/periodic callbacks |
|
|
938 | to increase efficiency of loop iterations (or to increase power-saving |
|
|
939 | opportunities). |
|
|
940 | .Sp |
|
|
941 | The idea is that sometimes your program runs just fast enough to handle |
|
|
942 | one (or very few) event(s) per loop iteration. While this makes the |
|
|
943 | program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
944 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
945 | overhead for the actual polling but can deliver many events at once. |
|
|
946 | .Sp |
|
|
947 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
948 | time collecting I/O events, so you can handle more events per iteration, |
|
|
949 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
950 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
951 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
952 | .Sp |
|
|
953 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
954 | to spend more time collecting timeouts, at the expense of increased |
|
|
955 | latency/jitter/inexactness (the watcher callback will be called |
|
|
956 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
|
|
957 | value will not introduce any overhead in libev. |
|
|
958 | .Sp |
|
|
959 | Many (busy) programs can usually benefit by setting the I/O collect |
|
|
960 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
961 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
962 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
963 | as this approaches the timing granularity of most systems. |
|
|
964 | .Sp |
|
|
965 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
|
|
966 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
|
|
967 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
|
|
968 | times the process sleeps and wakes up again. Another useful technique to |
|
|
969 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
|
|
970 | they fire on, say, one-second boundaries only. |
|
|
971 | .IP "ev_loop_verify (loop)" 4 |
|
|
972 | .IX Item "ev_loop_verify (loop)" |
|
|
973 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
|
|
974 | compiled in, which is the default for non-minimal builds. It tries to go |
|
|
975 | through all internal structures and checks them for validity. If anything |
|
|
976 | is found to be inconsistent, it will print an error message to standard |
|
|
977 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
|
|
978 | .Sp |
|
|
979 | This can be used to catch bugs inside libev itself: under normal |
|
|
980 | circumstances, this function will never abort as of course libev keeps its |
|
|
981 | data structures consistent. |
609 | .SH "ANATOMY OF A WATCHER" |
982 | .SH "ANATOMY OF A WATCHER" |
610 | .IX Header "ANATOMY OF A WATCHER" |
983 | .IX Header "ANATOMY OF A WATCHER" |
|
|
984 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
|
|
985 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
|
|
986 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
|
|
987 | .PP |
611 | A watcher is a structure that you create and register to record your |
988 | A watcher is a structure that you create and register to record your |
612 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
989 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
613 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
990 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
614 | .PP |
991 | .PP |
615 | .Vb 5 |
992 | .Vb 5 |
616 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
993 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
617 | \& { |
994 | \& { |
618 | \& ev_io_stop (w); |
995 | \& ev_io_stop (w); |
619 | \& ev_unloop (loop, EVUNLOOP_ALL); |
996 | \& ev_unloop (loop, EVUNLOOP_ALL); |
620 | \& } |
997 | \& } |
621 | .Ve |
998 | \& |
622 | .PP |
|
|
623 | .Vb 6 |
|
|
624 | \& struct ev_loop *loop = ev_default_loop (0); |
999 | \& struct ev_loop *loop = ev_default_loop (0); |
|
|
1000 | \& |
625 | \& struct ev_io stdin_watcher; |
1001 | \& ev_io stdin_watcher; |
|
|
1002 | \& |
626 | \& ev_init (&stdin_watcher, my_cb); |
1003 | \& ev_init (&stdin_watcher, my_cb); |
627 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1004 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
628 | \& ev_io_start (loop, &stdin_watcher); |
1005 | \& ev_io_start (loop, &stdin_watcher); |
|
|
1006 | \& |
629 | \& ev_loop (loop, 0); |
1007 | \& ev_loop (loop, 0); |
630 | .Ve |
1008 | .Ve |
631 | .PP |
1009 | .PP |
632 | As you can see, you are responsible for allocating the memory for your |
1010 | As you can see, you are responsible for allocating the memory for your |
633 | watcher structures (and it is usually a bad idea to do this on the stack, |
1011 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
634 | although this can sometimes be quite valid). |
1012 | stack). |
|
|
1013 | .PP |
|
|
1014 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
|
|
1015 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
635 | .PP |
1016 | .PP |
636 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1017 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
637 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1018 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
638 | callback gets invoked each time the event occurs (or, in the case of io |
1019 | callback gets invoked each time the event occurs (or, in the case of I/O |
639 | watchers, each time the event loop detects that the file descriptor given |
1020 | watchers, each time the event loop detects that the file descriptor given |
640 | is readable and/or writable). |
1021 | is readable and/or writable). |
641 | .PP |
1022 | .PP |
642 | Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro |
1023 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
643 | with arguments specific to this watcher type. There is also a macro |
1024 | macro to configure it, with arguments specific to the watcher type. There |
644 | to combine initialisation and setting in one call: \f(CW\*(C`ev_<type>_init |
1025 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
645 | (watcher *, callback, ...)\*(C'\fR. |
|
|
646 | .PP |
1026 | .PP |
647 | To make the watcher actually watch out for events, you have to start it |
1027 | To make the watcher actually watch out for events, you have to start it |
648 | with a watcher-specific start function (\f(CW\*(C`ev_<type>_start (loop, watcher |
1028 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
649 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1029 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
650 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
1030 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
651 | .PP |
1031 | .PP |
652 | As long as your watcher is active (has been started but not stopped) you |
1032 | As long as your watcher is active (has been started but not stopped) you |
653 | must not touch the values stored in it. Most specifically you must never |
1033 | must not touch the values stored in it. Most specifically you must never |
654 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
1034 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
655 | .PP |
1035 | .PP |
656 | Each and every callback receives the event loop pointer as first, the |
1036 | Each and every callback receives the event loop pointer as first, the |
657 | registered watcher structure as second, and a bitset of received events as |
1037 | registered watcher structure as second, and a bitset of received events as |
658 | third argument. |
1038 | third argument. |
659 | .PP |
1039 | .PP |
… | |
… | |
707 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1087 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
708 | received events. Callbacks of both watcher types can start and stop as |
1088 | received events. Callbacks of both watcher types can start and stop as |
709 | many watchers as they want, and all of them will be taken into account |
1089 | many watchers as they want, and all of them will be taken into account |
710 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1090 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
711 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
1091 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
|
|
1092 | .ie n .IP """EV_EMBED""" 4 |
|
|
1093 | .el .IP "\f(CWEV_EMBED\fR" 4 |
|
|
1094 | .IX Item "EV_EMBED" |
|
|
1095 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
|
|
1096 | .ie n .IP """EV_FORK""" 4 |
|
|
1097 | .el .IP "\f(CWEV_FORK\fR" 4 |
|
|
1098 | .IX Item "EV_FORK" |
|
|
1099 | The event loop has been resumed in the child process after fork (see |
|
|
1100 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1101 | .ie n .IP """EV_ASYNC""" 4 |
|
|
1102 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
1103 | .IX Item "EV_ASYNC" |
|
|
1104 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1105 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1106 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1107 | .IX Item "EV_CUSTOM" |
|
|
1108 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1109 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
712 | .ie n .IP """EV_ERROR""" 4 |
1110 | .ie n .IP """EV_ERROR""" 4 |
713 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1111 | .el .IP "\f(CWEV_ERROR\fR" 4 |
714 | .IX Item "EV_ERROR" |
1112 | .IX Item "EV_ERROR" |
715 | An unspecified error has occured, the watcher has been stopped. This might |
1113 | An unspecified error has occurred, the watcher has been stopped. This might |
716 | happen because the watcher could not be properly started because libev |
1114 | happen because the watcher could not be properly started because libev |
717 | ran out of memory, a file descriptor was found to be closed or any other |
1115 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
1116 | problem. Libev considers these application bugs. |
|
|
1117 | .Sp |
718 | problem. You best act on it by reporting the problem and somehow coping |
1118 | You best act on it by reporting the problem and somehow coping with the |
719 | with the watcher being stopped. |
1119 | watcher being stopped. Note that well-written programs should not receive |
|
|
1120 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
1121 | bug in your program. |
720 | .Sp |
1122 | .Sp |
721 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
1123 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
722 | for example it might indicate that a fd is readable or writable, and if |
1124 | example it might indicate that a fd is readable or writable, and if your |
723 | your callbacks is well-written it can just attempt the operation and cope |
1125 | callbacks is well-written it can just attempt the operation and cope with |
724 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
1126 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
725 | programs, though, so beware. |
1127 | programs, though, as the fd could already be closed and reused for another |
|
|
1128 | thing, so beware. |
726 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1129 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
727 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1130 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
728 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
729 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
730 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1131 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
731 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1132 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
732 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1133 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
733 | This macro initialises the generic portion of a watcher. The contents |
1134 | This macro initialises the generic portion of a watcher. The contents |
734 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
1135 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
… | |
… | |
738 | which rolls both calls into one. |
1139 | which rolls both calls into one. |
739 | .Sp |
1140 | .Sp |
740 | You can reinitialise a watcher at any time as long as it has been stopped |
1141 | You can reinitialise a watcher at any time as long as it has been stopped |
741 | (or never started) and there are no pending events outstanding. |
1142 | (or never started) and there are no pending events outstanding. |
742 | .Sp |
1143 | .Sp |
743 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
1144 | The callback is always of type \f(CW\*(C`void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
744 | int revents)\*(C'\fR. |
1145 | int revents)\*(C'\fR. |
|
|
1146 | .Sp |
|
|
1147 | Example: Initialise an \f(CW\*(C`ev_io\*(C'\fR watcher in two steps. |
|
|
1148 | .Sp |
|
|
1149 | .Vb 3 |
|
|
1150 | \& ev_io w; |
|
|
1151 | \& ev_init (&w, my_cb); |
|
|
1152 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
|
|
1153 | .Ve |
745 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1154 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
746 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1155 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
747 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1156 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
748 | This macro initialises the type-specific parts of a watcher. You need to |
1157 | This macro initialises the type-specific parts of a watcher. You need to |
749 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1158 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
… | |
… | |
751 | macro on a watcher that is active (it can be pending, however, which is a |
1160 | macro on a watcher that is active (it can be pending, however, which is a |
752 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1161 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
753 | .Sp |
1162 | .Sp |
754 | Although some watcher types do not have type-specific arguments |
1163 | Although some watcher types do not have type-specific arguments |
755 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
1164 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
|
|
1165 | .Sp |
|
|
1166 | See \f(CW\*(C`ev_init\*(C'\fR, above, for an example. |
756 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
1167 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
757 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
1168 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
758 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
1169 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
759 | This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
1170 | This convenience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
760 | calls into a single call. This is the most convinient method to initialise |
1171 | calls into a single call. This is the most convenient method to initialise |
761 | a watcher. The same limitations apply, of course. |
1172 | a watcher. The same limitations apply, of course. |
|
|
1173 | .Sp |
|
|
1174 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
|
|
1175 | .Sp |
|
|
1176 | .Vb 1 |
|
|
1177 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
|
|
1178 | .Ve |
762 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1179 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
763 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1180 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
764 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1181 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
765 | Starts (activates) the given watcher. Only active watchers will receive |
1182 | Starts (activates) the given watcher. Only active watchers will receive |
766 | events. If the watcher is already active nothing will happen. |
1183 | events. If the watcher is already active nothing will happen. |
|
|
1184 | .Sp |
|
|
1185 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
|
|
1186 | whole section. |
|
|
1187 | .Sp |
|
|
1188 | .Vb 1 |
|
|
1189 | \& ev_io_start (EV_DEFAULT_UC, &w); |
|
|
1190 | .Ve |
767 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1191 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
768 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1192 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
769 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1193 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
770 | Stops the given watcher again (if active) and clears the pending |
1194 | Stops the given watcher if active, and clears the pending status (whether |
|
|
1195 | the watcher was active or not). |
|
|
1196 | .Sp |
771 | status. It is possible that stopped watchers are pending (for example, |
1197 | It is possible that stopped watchers are pending \- for example, |
772 | non-repeating timers are being stopped when they become pending), but |
1198 | non-repeating timers are being stopped when they become pending \- but |
773 | \&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If |
1199 | calling \f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor |
774 | you want to free or reuse the memory used by the watcher it is therefore a |
1200 | pending. If you want to free or reuse the memory used by the watcher it is |
775 | good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1201 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
776 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1202 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
777 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1203 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
778 | Returns a true value iff the watcher is active (i.e. it has been started |
1204 | Returns a true value iff the watcher is active (i.e. it has been started |
779 | and not yet been stopped). As long as a watcher is active you must not modify |
1205 | and not yet been stopped). As long as a watcher is active you must not modify |
780 | it. |
1206 | it. |
781 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1207 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
782 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1208 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
783 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1209 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
784 | events but its callback has not yet been invoked). As long as a watcher |
1210 | events but its callback has not yet been invoked). As long as a watcher |
785 | is pending (but not active) you must not call an init function on it (but |
1211 | is pending (but not active) you must not call an init function on it (but |
786 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1212 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
787 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1213 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1214 | it). |
788 | .IP "callback = ev_cb (ev_TYPE *watcher)" 4 |
1215 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
789 | .IX Item "callback = ev_cb (ev_TYPE *watcher)" |
1216 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
790 | Returns the callback currently set on the watcher. |
1217 | Returns the callback currently set on the watcher. |
791 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1218 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
792 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1219 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
793 | Change the callback. You can change the callback at virtually any time |
1220 | Change the callback. You can change the callback at virtually any time |
794 | (modulo threads). |
1221 | (modulo threads). |
|
|
1222 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1223 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1224 | .PD 0 |
|
|
1225 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1226 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1227 | .PD |
|
|
1228 | Set and query the priority of the watcher. The priority is a small |
|
|
1229 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1230 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1231 | before watchers with lower priority, but priority will not keep watchers |
|
|
1232 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1233 | .Sp |
|
|
1234 | If you need to suppress invocation when higher priority events are pending |
|
|
1235 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1236 | .Sp |
|
|
1237 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1238 | pending. |
|
|
1239 | .Sp |
|
|
1240 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1241 | fine, as long as you do not mind that the priority value you query might |
|
|
1242 | or might not have been clamped to the valid range. |
|
|
1243 | .Sp |
|
|
1244 | The default priority used by watchers when no priority has been set is |
|
|
1245 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1246 | .Sp |
|
|
1247 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1248 | priorities. |
|
|
1249 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1250 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1251 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
|
|
1252 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1253 | can deal with that fact, as both are simply passed through to the |
|
|
1254 | callback. |
|
|
1255 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1256 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1257 | If the watcher is pending, this function clears its pending status and |
|
|
1258 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1259 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
|
|
1260 | .Sp |
|
|
1261 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
|
|
1262 | callback to be invoked, which can be accomplished with this function. |
795 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1263 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
796 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1264 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
797 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1265 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
798 | and read at any time, libev will completely ignore it. This can be used |
1266 | and read at any time: libev will completely ignore it. This can be used |
799 | to associate arbitrary data with your watcher. If you need more data and |
1267 | to associate arbitrary data with your watcher. If you need more data and |
800 | don't want to allocate memory and store a pointer to it in that data |
1268 | don't want to allocate memory and store a pointer to it in that data |
801 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1269 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
802 | data: |
1270 | data: |
803 | .PP |
1271 | .PP |
804 | .Vb 7 |
1272 | .Vb 7 |
805 | \& struct my_io |
1273 | \& struct my_io |
806 | \& { |
1274 | \& { |
807 | \& struct ev_io io; |
1275 | \& ev_io io; |
808 | \& int otherfd; |
1276 | \& int otherfd; |
809 | \& void *somedata; |
1277 | \& void *somedata; |
810 | \& struct whatever *mostinteresting; |
1278 | \& struct whatever *mostinteresting; |
811 | \& } |
1279 | \& }; |
|
|
1280 | \& |
|
|
1281 | \& ... |
|
|
1282 | \& struct my_io w; |
|
|
1283 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
812 | .Ve |
1284 | .Ve |
813 | .PP |
1285 | .PP |
814 | And since your callback will be called with a pointer to the watcher, you |
1286 | And since your callback will be called with a pointer to the watcher, you |
815 | can cast it back to your own type: |
1287 | can cast it back to your own type: |
816 | .PP |
1288 | .PP |
817 | .Vb 5 |
1289 | .Vb 5 |
818 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1290 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
819 | \& { |
1291 | \& { |
820 | \& struct my_io *w = (struct my_io *)w_; |
1292 | \& struct my_io *w = (struct my_io *)w_; |
821 | \& ... |
1293 | \& ... |
822 | \& } |
1294 | \& } |
823 | .Ve |
1295 | .Ve |
824 | .PP |
1296 | .PP |
825 | More interesting and less C\-conformant ways of catsing your callback type |
1297 | More interesting and less C\-conformant ways of casting your callback type |
826 | have been omitted.... |
1298 | instead have been omitted. |
|
|
1299 | .PP |
|
|
1300 | Another common scenario is to use some data structure with multiple |
|
|
1301 | embedded watchers: |
|
|
1302 | .PP |
|
|
1303 | .Vb 6 |
|
|
1304 | \& struct my_biggy |
|
|
1305 | \& { |
|
|
1306 | \& int some_data; |
|
|
1307 | \& ev_timer t1; |
|
|
1308 | \& ev_timer t2; |
|
|
1309 | \& } |
|
|
1310 | .Ve |
|
|
1311 | .PP |
|
|
1312 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
1313 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1314 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1315 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1316 | programmers): |
|
|
1317 | .PP |
|
|
1318 | .Vb 1 |
|
|
1319 | \& #include <stddef.h> |
|
|
1320 | \& |
|
|
1321 | \& static void |
|
|
1322 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
1323 | \& { |
|
|
1324 | \& struct my_biggy big = (struct my_biggy * |
|
|
1325 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1326 | \& } |
|
|
1327 | \& |
|
|
1328 | \& static void |
|
|
1329 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1330 | \& { |
|
|
1331 | \& struct my_biggy big = (struct my_biggy * |
|
|
1332 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1333 | \& } |
|
|
1334 | .Ve |
|
|
1335 | .Sh "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1336 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1337 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1338 | integers that influence the ordering of event callback invocation |
|
|
1339 | between watchers in some way, all else being equal. |
|
|
1340 | .PP |
|
|
1341 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1342 | description for the more technical details such as the actual priority |
|
|
1343 | range. |
|
|
1344 | .PP |
|
|
1345 | There are two common ways how these these priorities are being interpreted |
|
|
1346 | by event loops: |
|
|
1347 | .PP |
|
|
1348 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1349 | of lower priority watchers, which means as long as higher priority |
|
|
1350 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1351 | .PP |
|
|
1352 | The less common only-for-ordering model uses priorities solely to order |
|
|
1353 | callback invocation within a single event loop iteration: Higher priority |
|
|
1354 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1355 | before polling for new events. |
|
|
1356 | .PP |
|
|
1357 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1358 | except for idle watchers (which use the lock-out model). |
|
|
1359 | .PP |
|
|
1360 | The rationale behind this is that implementing the lock-out model for |
|
|
1361 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1362 | libraries will just poll for the same events again and again as long as |
|
|
1363 | their callbacks have not been executed, which is very inefficient in the |
|
|
1364 | common case of one high-priority watcher locking out a mass of lower |
|
|
1365 | priority ones. |
|
|
1366 | .PP |
|
|
1367 | Static (ordering) priorities are most useful when you have two or more |
|
|
1368 | watchers handling the same resource: a typical usage example is having an |
|
|
1369 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1370 | timeouts. Under load, data might be received while the program handles |
|
|
1371 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1372 | handler will be executed before checking for data. In that case, giving |
|
|
1373 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1374 | handled first even under adverse conditions (which is usually, but not |
|
|
1375 | always, what you want). |
|
|
1376 | .PP |
|
|
1377 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1378 | will only be executed when no same or higher priority watchers have |
|
|
1379 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1380 | required. |
|
|
1381 | .PP |
|
|
1382 | For example, to emulate how many other event libraries handle priorities, |
|
|
1383 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1384 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1385 | processing is done in the idle watcher callback. This causes libev to |
|
|
1386 | continously poll and process kernel event data for the watcher, but when |
|
|
1387 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1388 | workable. |
|
|
1389 | .PP |
|
|
1390 | Usually, however, the lock-out model implemented that way will perform |
|
|
1391 | miserably under the type of load it was designed to handle. In that case, |
|
|
1392 | it might be preferable to stop the real watcher before starting the |
|
|
1393 | idle watcher, so the kernel will not have to process the event in case |
|
|
1394 | the actual processing will be delayed for considerable time. |
|
|
1395 | .PP |
|
|
1396 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1397 | priority than the default, and which should only process data when no |
|
|
1398 | other events are pending: |
|
|
1399 | .PP |
|
|
1400 | .Vb 2 |
|
|
1401 | \& ev_idle idle; // actual processing watcher |
|
|
1402 | \& ev_io io; // actual event watcher |
|
|
1403 | \& |
|
|
1404 | \& static void |
|
|
1405 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1406 | \& { |
|
|
1407 | \& // stop the I/O watcher, we received the event, but |
|
|
1408 | \& // are not yet ready to handle it. |
|
|
1409 | \& ev_io_stop (EV_A_ w); |
|
|
1410 | \& |
|
|
1411 | \& // start the idle watcher to ahndle the actual event. |
|
|
1412 | \& // it will not be executed as long as other watchers |
|
|
1413 | \& // with the default priority are receiving events. |
|
|
1414 | \& ev_idle_start (EV_A_ &idle); |
|
|
1415 | \& } |
|
|
1416 | \& |
|
|
1417 | \& static void |
|
|
1418 | \& idle\-cb (EV_P_ ev_idle *w, int revents) |
|
|
1419 | \& { |
|
|
1420 | \& // actual processing |
|
|
1421 | \& read (STDIN_FILENO, ...); |
|
|
1422 | \& |
|
|
1423 | \& // have to start the I/O watcher again, as |
|
|
1424 | \& // we have handled the event |
|
|
1425 | \& ev_io_start (EV_P_ &io); |
|
|
1426 | \& } |
|
|
1427 | \& |
|
|
1428 | \& // initialisation |
|
|
1429 | \& ev_idle_init (&idle, idle_cb); |
|
|
1430 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1431 | \& ev_io_start (EV_DEFAULT_ &io); |
|
|
1432 | .Ve |
|
|
1433 | .PP |
|
|
1434 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1435 | low-priority connections can not be locked out forever under load. This |
|
|
1436 | enables your program to keep a lower latency for important connections |
|
|
1437 | during short periods of high load, while not completely locking out less |
|
|
1438 | important ones. |
827 | .SH "WATCHER TYPES" |
1439 | .SH "WATCHER TYPES" |
828 | .IX Header "WATCHER TYPES" |
1440 | .IX Header "WATCHER TYPES" |
829 | This section describes each watcher in detail, but will not repeat |
1441 | This section describes each watcher in detail, but will not repeat |
830 | information given in the last section. Any initialisation/set macros, |
1442 | information given in the last section. Any initialisation/set macros, |
831 | functions and members specific to the watcher type are explained. |
1443 | functions and members specific to the watcher type are explained. |
… | |
… | |
852 | In general you can register as many read and/or write event watchers per |
1464 | In general you can register as many read and/or write event watchers per |
853 | fd as you want (as long as you don't confuse yourself). Setting all file |
1465 | fd as you want (as long as you don't confuse yourself). Setting all file |
854 | descriptors to non-blocking mode is also usually a good idea (but not |
1466 | descriptors to non-blocking mode is also usually a good idea (but not |
855 | required if you know what you are doing). |
1467 | required if you know what you are doing). |
856 | .PP |
1468 | .PP |
857 | You have to be careful with dup'ed file descriptors, though. Some backends |
1469 | If you cannot use non-blocking mode, then force the use of a |
858 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
1470 | known-to-be-good backend (at the time of this writing, this includes only |
859 | descriptors correctly if you register interest in two or more fds pointing |
1471 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
860 | to the same underlying file/socket/etc. description (that is, they share |
1472 | descriptors for which non-blocking operation makes no sense (such as |
861 | the same underlying \*(L"file open\*(R"). |
1473 | files) \- libev doesn't guarentee any specific behaviour in that case. |
862 | .PP |
|
|
863 | If you must do this, then force the use of a known-to-be-good backend |
|
|
864 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
|
|
865 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
866 | .PP |
1474 | .PP |
867 | Another thing you have to watch out for is that it is quite easy to |
1475 | Another thing you have to watch out for is that it is quite easy to |
868 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
1476 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
869 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1477 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
870 | because there is no data. Not only are some backends known to create a |
1478 | because there is no data. Not only are some backends known to create a |
871 | lot of those (for example solaris ports), it is very easy to get into |
1479 | lot of those (for example Solaris ports), it is very easy to get into |
872 | this situation even with a relatively standard program structure. Thus |
1480 | this situation even with a relatively standard program structure. Thus |
873 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1481 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
874 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1482 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
875 | .PP |
1483 | .PP |
876 | If you cannot run the fd in non-blocking mode (for example you should not |
1484 | If you cannot run the fd in non-blocking mode (for example you should |
877 | play around with an Xlib connection), then you have to seperately re-test |
1485 | not play around with an Xlib connection), then you have to separately |
878 | wether a file descriptor is really ready with a known-to-be good interface |
1486 | re-test whether a file descriptor is really ready with a known-to-be good |
879 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1487 | interface such as poll (fortunately in our Xlib example, Xlib already |
880 | its own, so its quite safe to use). |
1488 | does this on its own, so its quite safe to use). Some people additionally |
|
|
1489 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
|
|
1490 | indefinitely. |
|
|
1491 | .PP |
|
|
1492 | But really, best use non-blocking mode. |
|
|
1493 | .PP |
|
|
1494 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1495 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1496 | .PP |
|
|
1497 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1498 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
|
|
1499 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
|
|
1500 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1501 | this interest. If another file descriptor with the same number then is |
|
|
1502 | registered with libev, there is no efficient way to see that this is, in |
|
|
1503 | fact, a different file descriptor. |
|
|
1504 | .PP |
|
|
1505 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1506 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1507 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1508 | it is assumed that the file descriptor stays the same. That means that |
|
|
1509 | you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the |
|
|
1510 | descriptor even if the file descriptor number itself did not change. |
|
|
1511 | .PP |
|
|
1512 | This is how one would do it normally anyway, the important point is that |
|
|
1513 | the libev application should not optimise around libev but should leave |
|
|
1514 | optimisations to libev. |
|
|
1515 | .PP |
|
|
1516 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1517 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1518 | .PP |
|
|
1519 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1520 | but only events for the underlying file descriptions. That means when you |
|
|
1521 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1522 | events for them, only one file descriptor might actually receive events. |
|
|
1523 | .PP |
|
|
1524 | There is no workaround possible except not registering events |
|
|
1525 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1526 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1527 | .PP |
|
|
1528 | \fIThe special problem of fork\fR |
|
|
1529 | .IX Subsection "The special problem of fork" |
|
|
1530 | .PP |
|
|
1531 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1532 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1533 | it in the child. |
|
|
1534 | .PP |
|
|
1535 | To support fork in your programs, you either have to call |
|
|
1536 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1537 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1538 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1539 | .PP |
|
|
1540 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1541 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1542 | .PP |
|
|
1543 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
|
|
1544 | when writing to a pipe whose other end has been closed, your program gets |
|
|
1545 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
|
|
1546 | this is sensible behaviour, for daemons, this is usually undesirable. |
|
|
1547 | .PP |
|
|
1548 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1549 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1550 | somewhere, as that would have given you a big clue). |
|
|
1551 | .PP |
|
|
1552 | \fIWatcher-Specific Functions\fR |
|
|
1553 | .IX Subsection "Watcher-Specific Functions" |
881 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1554 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
882 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1555 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
883 | .PD 0 |
1556 | .PD 0 |
884 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1557 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
885 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1558 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
886 | .PD |
1559 | .PD |
887 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1560 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
888 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1561 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
889 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
1562 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
890 | .IP "int fd [read\-only]" 4 |
1563 | .IP "int fd [read\-only]" 4 |
891 | .IX Item "int fd [read-only]" |
1564 | .IX Item "int fd [read-only]" |
892 | The file descriptor being watched. |
1565 | The file descriptor being watched. |
893 | .IP "int events [read\-only]" 4 |
1566 | .IP "int events [read\-only]" 4 |
894 | .IX Item "int events [read-only]" |
1567 | .IX Item "int events [read-only]" |
895 | The events being watched. |
1568 | The events being watched. |
896 | .PP |
1569 | .PP |
|
|
1570 | \fIExamples\fR |
|
|
1571 | .IX Subsection "Examples" |
|
|
1572 | .PP |
897 | Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1573 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
898 | readable, but only once. Since it is likely line\-buffered, you could |
1574 | readable, but only once. Since it is likely line-buffered, you could |
899 | attempt to read a whole line in the callback: |
1575 | attempt to read a whole line in the callback. |
900 | .PP |
1576 | .PP |
901 | .Vb 6 |
1577 | .Vb 6 |
902 | \& static void |
1578 | \& static void |
903 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1579 | \& stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
904 | \& { |
1580 | \& { |
905 | \& ev_io_stop (loop, w); |
1581 | \& ev_io_stop (loop, w); |
906 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1582 | \& .. read from stdin here (or from w\->fd) and handle any I/O errors |
907 | \& } |
1583 | \& } |
908 | .Ve |
1584 | \& |
909 | .PP |
|
|
910 | .Vb 6 |
|
|
911 | \& ... |
1585 | \& ... |
912 | \& struct ev_loop *loop = ev_default_init (0); |
1586 | \& struct ev_loop *loop = ev_default_init (0); |
913 | \& struct ev_io stdin_readable; |
1587 | \& ev_io stdin_readable; |
914 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1588 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
915 | \& ev_io_start (loop, &stdin_readable); |
1589 | \& ev_io_start (loop, &stdin_readable); |
916 | \& ev_loop (loop, 0); |
1590 | \& ev_loop (loop, 0); |
917 | .Ve |
1591 | .Ve |
918 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1592 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
919 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1593 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
920 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1594 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
921 | Timer watchers are simple relative timers that generate an event after a |
1595 | Timer watchers are simple relative timers that generate an event after a |
922 | given time, and optionally repeating in regular intervals after that. |
1596 | given time, and optionally repeating in regular intervals after that. |
923 | .PP |
1597 | .PP |
924 | The timers are based on real time, that is, if you register an event that |
1598 | The timers are based on real time, that is, if you register an event that |
925 | times out after an hour and you reset your system clock to last years |
1599 | times out after an hour and you reset your system clock to January last |
926 | time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because |
1600 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
927 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1601 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
928 | monotonic clock option helps a lot here). |
1602 | monotonic clock option helps a lot here). |
|
|
1603 | .PP |
|
|
1604 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
|
|
1605 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
|
|
1606 | might introduce a small delay). If multiple timers become ready during the |
|
|
1607 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1608 | before ones with later time-out values (but this is no longer true when a |
|
|
1609 | callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
|
|
1610 | .PP |
|
|
1611 | \fIBe smart about timeouts\fR |
|
|
1612 | .IX Subsection "Be smart about timeouts" |
|
|
1613 | .PP |
|
|
1614 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1615 | recovery. A typical example is an \s-1HTTP\s0 request \- if the other side hangs, |
|
|
1616 | you want to raise some error after a while. |
|
|
1617 | .PP |
|
|
1618 | What follows are some ways to handle this problem, from obvious and |
|
|
1619 | inefficient to smart and efficient. |
|
|
1620 | .PP |
|
|
1621 | In the following, a 60 second activity timeout is assumed \- a timeout that |
|
|
1622 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1623 | data or other life sign was received). |
|
|
1624 | .IP "1. Use a timer and stop, reinitialise and start it on activity." 4 |
|
|
1625 | .IX Item "1. Use a timer and stop, reinitialise and start it on activity." |
|
|
1626 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1627 | start the watcher: |
|
|
1628 | .Sp |
|
|
1629 | .Vb 2 |
|
|
1630 | \& ev_timer_init (timer, callback, 60., 0.); |
|
|
1631 | \& ev_timer_start (loop, timer); |
|
|
1632 | .Ve |
|
|
1633 | .Sp |
|
|
1634 | Then, each time there is some activity, \f(CW\*(C`ev_timer_stop\*(C'\fR it, initialise it |
|
|
1635 | and start it again: |
|
|
1636 | .Sp |
|
|
1637 | .Vb 3 |
|
|
1638 | \& ev_timer_stop (loop, timer); |
|
|
1639 | \& ev_timer_set (timer, 60., 0.); |
|
|
1640 | \& ev_timer_start (loop, timer); |
|
|
1641 | .Ve |
|
|
1642 | .Sp |
|
|
1643 | This is relatively simple to implement, but means that each time there is |
|
|
1644 | some activity, libev will first have to remove the timer from its internal |
|
|
1645 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1646 | still not a constant-time operation. |
|
|
1647 | .ie n .IP "2. Use a timer and re-start it with ""ev_timer_again"" inactivity." 4 |
|
|
1648 | .el .IP "2. Use a timer and re-start it with \f(CWev_timer_again\fR inactivity." 4 |
|
|
1649 | .IX Item "2. Use a timer and re-start it with ev_timer_again inactivity." |
|
|
1650 | This is the easiest way, and involves using \f(CW\*(C`ev_timer_again\*(C'\fR instead of |
|
|
1651 | \&\f(CW\*(C`ev_timer_start\*(C'\fR. |
|
|
1652 | .Sp |
|
|
1653 | To implement this, configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value |
|
|
1654 | of \f(CW60\fR and then call \f(CW\*(C`ev_timer_again\*(C'\fR at start and each time you |
|
|
1655 | successfully read or write some data. If you go into an idle state where |
|
|
1656 | you do not expect data to travel on the socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR |
|
|
1657 | the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will automatically restart it if need be. |
|
|
1658 | .Sp |
|
|
1659 | That means you can ignore both the \f(CW\*(C`ev_timer_start\*(C'\fR function and the |
|
|
1660 | \&\f(CW\*(C`after\*(C'\fR argument to \f(CW\*(C`ev_timer_set\*(C'\fR, and only ever use the \f(CW\*(C`repeat\*(C'\fR |
|
|
1661 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
|
|
1662 | .Sp |
|
|
1663 | At start: |
|
|
1664 | .Sp |
|
|
1665 | .Vb 3 |
|
|
1666 | \& ev_timer_init (timer, callback); |
|
|
1667 | \& timer\->repeat = 60.; |
|
|
1668 | \& ev_timer_again (loop, timer); |
|
|
1669 | .Ve |
|
|
1670 | .Sp |
|
|
1671 | Each time there is some activity: |
|
|
1672 | .Sp |
|
|
1673 | .Vb 1 |
|
|
1674 | \& ev_timer_again (loop, timer); |
|
|
1675 | .Ve |
|
|
1676 | .Sp |
|
|
1677 | It is even possible to change the time-out on the fly, regardless of |
|
|
1678 | whether the watcher is active or not: |
|
|
1679 | .Sp |
|
|
1680 | .Vb 2 |
|
|
1681 | \& timer\->repeat = 30.; |
|
|
1682 | \& ev_timer_again (loop, timer); |
|
|
1683 | .Ve |
|
|
1684 | .Sp |
|
|
1685 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1686 | you want to modify its timeout value, as libev does not have to completely |
|
|
1687 | remove and re-insert the timer from/into its internal data structure. |
|
|
1688 | .Sp |
|
|
1689 | It is, however, even simpler than the \*(L"obvious\*(R" way to do it. |
|
|
1690 | .IP "3. Let the timer time out, but then re-arm it as required." 4 |
|
|
1691 | .IX Item "3. Let the timer time out, but then re-arm it as required." |
|
|
1692 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1693 | relatively long compared to the intervals between other activity \- in |
|
|
1694 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1695 | associated activity resets. |
|
|
1696 | .Sp |
|
|
1697 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
|
|
1698 | but remember the time of last activity, and check for a real timeout only |
|
|
1699 | within the callback: |
|
|
1700 | .Sp |
|
|
1701 | .Vb 1 |
|
|
1702 | \& ev_tstamp last_activity; // time of last activity |
|
|
1703 | \& |
|
|
1704 | \& static void |
|
|
1705 | \& callback (EV_P_ ev_timer *w, int revents) |
|
|
1706 | \& { |
|
|
1707 | \& ev_tstamp now = ev_now (EV_A); |
|
|
1708 | \& ev_tstamp timeout = last_activity + 60.; |
|
|
1709 | \& |
|
|
1710 | \& // if last_activity + 60. is older than now, we did time out |
|
|
1711 | \& if (timeout < now) |
|
|
1712 | \& { |
|
|
1713 | \& // timeout occured, take action |
|
|
1714 | \& } |
|
|
1715 | \& else |
|
|
1716 | \& { |
|
|
1717 | \& // callback was invoked, but there was some activity, re\-arm |
|
|
1718 | \& // the watcher to fire in last_activity + 60, which is |
|
|
1719 | \& // guaranteed to be in the future, so "again" is positive: |
|
|
1720 | \& w\->repeat = timeout \- now; |
|
|
1721 | \& ev_timer_again (EV_A_ w); |
|
|
1722 | \& } |
|
|
1723 | \& } |
|
|
1724 | .Ve |
|
|
1725 | .Sp |
|
|
1726 | To summarise the callback: first calculate the real timeout (defined |
|
|
1727 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
|
|
1728 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
|
|
1729 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
|
|
1730 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1731 | a timeout then. |
|
|
1732 | .Sp |
|
|
1733 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
|
|
1734 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
|
|
1735 | .Sp |
|
|
1736 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1737 | minus half the average time between activity), but virtually no calls to |
|
|
1738 | libev to change the timeout. |
|
|
1739 | .Sp |
|
|
1740 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
|
|
1741 | to the current time (meaning we just have some activity :), then call the |
|
|
1742 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
|
|
1743 | .Sp |
|
|
1744 | .Vb 3 |
|
|
1745 | \& ev_timer_init (timer, callback); |
|
|
1746 | \& last_activity = ev_now (loop); |
|
|
1747 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1748 | .Ve |
|
|
1749 | .Sp |
|
|
1750 | And when there is some activity, simply store the current time in |
|
|
1751 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
|
|
1752 | .Sp |
|
|
1753 | .Vb 1 |
|
|
1754 | \& last_actiivty = ev_now (loop); |
|
|
1755 | .Ve |
|
|
1756 | .Sp |
|
|
1757 | This technique is slightly more complex, but in most cases where the |
|
|
1758 | time-out is unlikely to be triggered, much more efficient. |
|
|
1759 | .Sp |
|
|
1760 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1761 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1762 | fix things for you. |
|
|
1763 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
|
|
1764 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
|
|
1765 | If there is not one request, but many thousands (millions...), all |
|
|
1766 | employing some kind of timeout with the same timeout value, then one can |
|
|
1767 | do even better: |
|
|
1768 | .Sp |
|
|
1769 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1770 | at the \fIend\fR of the list. |
|
|
1771 | .Sp |
|
|
1772 | Then use an \f(CW\*(C`ev_timer\*(C'\fR to fire when the timeout at the \fIbeginning\fR of |
|
|
1773 | the list is expected to fire (for example, using the technique #3). |
|
|
1774 | .Sp |
|
|
1775 | When there is some activity, remove the timer from the list, recalculate |
|
|
1776 | the timeout, append it to the end of the list again, and make sure to |
|
|
1777 | update the \f(CW\*(C`ev_timer\*(C'\fR if it was taken from the beginning of the list. |
|
|
1778 | .Sp |
|
|
1779 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1780 | starting, stopping and updating the timers, at the expense of a major |
|
|
1781 | complication, and having to use a constant timeout. The constant timeout |
|
|
1782 | ensures that the list stays sorted. |
|
|
1783 | .PP |
|
|
1784 | So which method the best? |
|
|
1785 | .PP |
|
|
1786 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1787 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1788 | better, and isn't very complicated either. In most case, choosing either |
|
|
1789 | one is fine, with #3 being better in typical situations. |
|
|
1790 | .PP |
|
|
1791 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1792 | rather complicated, but extremely efficient, something that really pays |
|
|
1793 | off after the first million or so of active timers, i.e. it's usually |
|
|
1794 | overkill :) |
|
|
1795 | .PP |
|
|
1796 | \fIThe special problem of time updates\fR |
|
|
1797 | .IX Subsection "The special problem of time updates" |
|
|
1798 | .PP |
|
|
1799 | Establishing the current time is a costly operation (it usually takes at |
|
|
1800 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
|
|
1801 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
|
|
1802 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
|
|
1803 | lots of events in one iteration. |
929 | .PP |
1804 | .PP |
930 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1805 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
931 | time. This is usually the right thing as this timestamp refers to the time |
1806 | time. This is usually the right thing as this timestamp refers to the time |
932 | of the event triggering whatever timeout you are modifying/starting. If |
1807 | of the event triggering whatever timeout you are modifying/starting. If |
933 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1808 | you suspect event processing to be delayed and you \fIneed\fR to base the |
934 | on the current time, use something like this to adjust for this: |
1809 | timeout on the current time, use something like this to adjust for this: |
935 | .PP |
1810 | .PP |
936 | .Vb 1 |
1811 | .Vb 1 |
937 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1812 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
938 | .Ve |
1813 | .Ve |
939 | .PP |
1814 | .PP |
940 | The callback is guarenteed to be invoked only when its timeout has passed, |
1815 | If the event loop is suspended for a long time, you can also force an |
941 | but if multiple timers become ready during the same loop iteration then |
1816 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
942 | order of execution is undefined. |
1817 | ()\*(C'\fR. |
|
|
1818 | .PP |
|
|
1819 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1820 | .IX Subsection "Watcher-Specific Functions and Data Members" |
943 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1821 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
944 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1822 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
945 | .PD 0 |
1823 | .PD 0 |
946 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1824 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
947 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1825 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
948 | .PD |
1826 | .PD |
949 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR is |
1827 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
950 | \&\f(CW0.\fR, then it will automatically be stopped. If it is positive, then the |
1828 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
951 | timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds |
1829 | reached. If it is positive, then the timer will automatically be |
952 | later, again, and again, until stopped manually. |
1830 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
|
|
1831 | until stopped manually. |
953 | .Sp |
1832 | .Sp |
954 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1833 | The timer itself will do a best-effort at avoiding drift, that is, if |
955 | configure a timer to trigger every 10 seconds, then it will trigger at |
1834 | you configure a timer to trigger every 10 seconds, then it will normally |
956 | exactly 10 second intervals. If, however, your program cannot keep up with |
1835 | trigger at exactly 10 second intervals. If, however, your program cannot |
957 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1836 | keep up with the timer (because it takes longer than those 10 seconds to |
958 | timer will not fire more than once per event loop iteration. |
1837 | do stuff) the timer will not fire more than once per event loop iteration. |
959 | .IP "ev_timer_again (loop)" 4 |
1838 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
960 | .IX Item "ev_timer_again (loop)" |
1839 | .IX Item "ev_timer_again (loop, ev_timer *)" |
961 | This will act as if the timer timed out and restart it again if it is |
1840 | This will act as if the timer timed out and restart it again if it is |
962 | repeating. The exact semantics are: |
1841 | repeating. The exact semantics are: |
963 | .Sp |
1842 | .Sp |
|
|
1843 | If the timer is pending, its pending status is cleared. |
|
|
1844 | .Sp |
964 | If the timer is started but nonrepeating, stop it. |
1845 | If the timer is started but non-repeating, stop it (as if it timed out). |
965 | .Sp |
1846 | .Sp |
966 | If the timer is repeating, either start it if necessary (with the repeat |
1847 | If the timer is repeating, either start it if necessary (with the |
967 | value), or reset the running timer to the repeat value. |
1848 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
968 | .Sp |
1849 | .Sp |
969 | This sounds a bit complicated, but here is a useful and typical |
1850 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
970 | example: Imagine you have a tcp connection and you want a so-called |
1851 | usage example. |
971 | idle timeout, that is, you want to be called when there have been, |
|
|
972 | say, 60 seconds of inactivity on the socket. The easiest way to do |
|
|
973 | this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling |
|
|
974 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
|
|
975 | you go into an idle state where you do not expect data to travel on the |
|
|
976 | socket, you can stop the timer, and again will automatically restart it if |
|
|
977 | need be. |
|
|
978 | .Sp |
|
|
979 | You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether |
|
|
980 | and only ever use the \f(CW\*(C`repeat\*(C'\fR value: |
|
|
981 | .Sp |
|
|
982 | .Vb 8 |
|
|
983 | \& ev_timer_init (timer, callback, 0., 5.); |
|
|
984 | \& ev_timer_again (loop, timer); |
|
|
985 | \& ... |
|
|
986 | \& timer->again = 17.; |
|
|
987 | \& ev_timer_again (loop, timer); |
|
|
988 | \& ... |
|
|
989 | \& timer->again = 10.; |
|
|
990 | \& ev_timer_again (loop, timer); |
|
|
991 | .Ve |
|
|
992 | .Sp |
|
|
993 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
994 | to modify its timeout value. |
|
|
995 | .IP "ev_tstamp repeat [read\-write]" 4 |
1852 | .IP "ev_tstamp repeat [read\-write]" 4 |
996 | .IX Item "ev_tstamp repeat [read-write]" |
1853 | .IX Item "ev_tstamp repeat [read-write]" |
997 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1854 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
998 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1855 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
999 | which is also when any modifications are taken into account. |
1856 | which is also when any modifications are taken into account. |
1000 | .PP |
1857 | .PP |
|
|
1858 | \fIExamples\fR |
|
|
1859 | .IX Subsection "Examples" |
|
|
1860 | .PP |
1001 | Example: create a timer that fires after 60 seconds. |
1861 | Example: Create a timer that fires after 60 seconds. |
1002 | .PP |
1862 | .PP |
1003 | .Vb 5 |
1863 | .Vb 5 |
1004 | \& static void |
1864 | \& static void |
1005 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1865 | \& one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1006 | \& { |
1866 | \& { |
1007 | \& .. one minute over, w is actually stopped right here |
1867 | \& .. one minute over, w is actually stopped right here |
1008 | \& } |
1868 | \& } |
1009 | .Ve |
1869 | \& |
1010 | .PP |
|
|
1011 | .Vb 3 |
|
|
1012 | \& struct ev_timer mytimer; |
1870 | \& ev_timer mytimer; |
1013 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1871 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1014 | \& ev_timer_start (loop, &mytimer); |
1872 | \& ev_timer_start (loop, &mytimer); |
1015 | .Ve |
1873 | .Ve |
1016 | .PP |
1874 | .PP |
1017 | Example: create a timeout timer that times out after 10 seconds of |
1875 | Example: Create a timeout timer that times out after 10 seconds of |
1018 | inactivity. |
1876 | inactivity. |
1019 | .PP |
1877 | .PP |
1020 | .Vb 5 |
1878 | .Vb 5 |
1021 | \& static void |
1879 | \& static void |
1022 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1880 | \& timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1023 | \& { |
1881 | \& { |
1024 | \& .. ten seconds without any activity |
1882 | \& .. ten seconds without any activity |
1025 | \& } |
1883 | \& } |
1026 | .Ve |
1884 | \& |
1027 | .PP |
|
|
1028 | .Vb 4 |
|
|
1029 | \& struct ev_timer mytimer; |
1885 | \& ev_timer mytimer; |
1030 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1886 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1031 | \& ev_timer_again (&mytimer); /* start timer */ |
1887 | \& ev_timer_again (&mytimer); /* start timer */ |
1032 | \& ev_loop (loop, 0); |
1888 | \& ev_loop (loop, 0); |
1033 | .Ve |
1889 | \& |
1034 | .PP |
|
|
1035 | .Vb 3 |
|
|
1036 | \& // and in some piece of code that gets executed on any "activity": |
1890 | \& // and in some piece of code that gets executed on any "activity": |
1037 | \& // reset the timeout to start ticking again at 10 seconds |
1891 | \& // reset the timeout to start ticking again at 10 seconds |
1038 | \& ev_timer_again (&mytimer); |
1892 | \& ev_timer_again (&mytimer); |
1039 | .Ve |
1893 | .Ve |
1040 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1894 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1041 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
1895 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
1042 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1896 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1043 | Periodic watchers are also timers of a kind, but they are very versatile |
1897 | Periodic watchers are also timers of a kind, but they are very versatile |
1044 | (and unfortunately a bit complex). |
1898 | (and unfortunately a bit complex). |
1045 | .PP |
1899 | .PP |
1046 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1900 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1047 | but on wallclock time (absolute time). You can tell a periodic watcher |
1901 | relative time, the physical time that passes) but on wall clock time |
1048 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1902 | (absolute time, the thing you can read on your calender or clock). The |
1049 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1903 | difference is that wall clock time can run faster or slower than real |
1050 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1904 | time, and time jumps are not uncommon (e.g. when you adjust your |
1051 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1905 | wrist-watch). |
1052 | roughly 10 seconds later and of course not if you reset your system time |
|
|
1053 | again). |
|
|
1054 | .PP |
1906 | .PP |
1055 | They can also be used to implement vastly more complex timers, such as |
1907 | You can tell a periodic watcher to trigger after some specific point |
1056 | triggering an event on eahc midnight, local time. |
1908 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
1909 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
1910 | not a delay) and then reset your system clock to January of the previous |
|
|
1911 | year, then it will take a year or more to trigger the event (unlike an |
|
|
1912 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
1913 | it, as it uses a relative timeout). |
1057 | .PP |
1914 | .PP |
|
|
1915 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
|
|
1916 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
|
|
1917 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
1918 | those cannot react to time jumps. |
|
|
1919 | .PP |
1058 | As with timers, the callback is guarenteed to be invoked only when the |
1920 | As with timers, the callback is guaranteed to be invoked only when the |
1059 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1921 | point in time where it is supposed to trigger has passed. If multiple |
1060 | during the same loop iteration then order of execution is undefined. |
1922 | timers become ready during the same loop iteration then the ones with |
|
|
1923 | earlier time-out values are invoked before ones with later time-out values |
|
|
1924 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
|
|
1925 | .PP |
|
|
1926 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1927 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1061 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1928 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1062 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1929 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1063 | .PD 0 |
1930 | .PD 0 |
1064 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1931 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1065 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1932 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1066 | .PD |
1933 | .PD |
1067 | Lots of arguments, lets sort it out... There are basically three modes of |
1934 | Lots of arguments, let's sort it out... There are basically three modes of |
1068 | operation, and we will explain them from simplest to complex: |
1935 | operation, and we will explain them from simplest to most complex: |
1069 | .RS 4 |
1936 | .RS 4 |
1070 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1937 | .IP "\(bu" 4 |
1071 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1938 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
|
|
1939 | .Sp |
1072 | In this configuration the watcher triggers an event at the wallclock time |
1940 | In this configuration the watcher triggers an event after the wall clock |
1073 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1941 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1074 | that is, if it is to be run at January 1st 2011 then it will run when the |
1942 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1075 | system time reaches or surpasses this time. |
1943 | will be stopped and invoked when the system clock reaches or surpasses |
1076 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1944 | this point in time. |
1077 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1945 | .IP "\(bu" 4 |
|
|
1946 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
|
|
1947 | .Sp |
1078 | In this mode the watcher will always be scheduled to time out at the next |
1948 | In this mode the watcher will always be scheduled to time out at the next |
1079 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1949 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1080 | of any time jumps. |
1950 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
1951 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1081 | .Sp |
1952 | .Sp |
1082 | This can be used to create timers that do not drift with respect to system |
1953 | This can be used to create timers that do not drift with respect to the |
1083 | time: |
1954 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
|
|
1955 | hour, on the hour (with respect to \s-1UTC\s0): |
1084 | .Sp |
1956 | .Sp |
1085 | .Vb 1 |
1957 | .Vb 1 |
1086 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1958 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1087 | .Ve |
1959 | .Ve |
1088 | .Sp |
1960 | .Sp |
1089 | This doesn't mean there will always be 3600 seconds in between triggers, |
1961 | This doesn't mean there will always be 3600 seconds in between triggers, |
1090 | but only that the the callback will be called when the system time shows a |
1962 | but only that the callback will be called when the system time shows a |
1091 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1963 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1092 | by 3600. |
1964 | by 3600. |
1093 | .Sp |
1965 | .Sp |
1094 | Another way to think about it (for the mathematically inclined) is that |
1966 | Another way to think about it (for the mathematically inclined) is that |
1095 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1967 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1096 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1968 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1097 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1969 | .Sp |
1098 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1970 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
|
|
1971 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1972 | this value, and in fact is often specified as zero. |
|
|
1973 | .Sp |
|
|
1974 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
|
|
1975 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
|
|
1976 | will of course deteriorate. Libev itself tries to be exact to be about one |
|
|
1977 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
|
|
1978 | .IP "\(bu" 4 |
|
|
1979 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
|
|
1980 | .Sp |
1099 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1981 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1100 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1982 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1101 | reschedule callback will be called with the watcher as first, and the |
1983 | reschedule callback will be called with the watcher as first, and the |
1102 | current time as second argument. |
1984 | current time as second argument. |
1103 | .Sp |
1985 | .Sp |
1104 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1986 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1105 | ever, or make any event loop modifications\fR. If you need to stop it, |
1987 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
1106 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1988 | allowed by documentation here\fR. |
1107 | starting a prepare watcher). |
|
|
1108 | .Sp |
1989 | .Sp |
|
|
1990 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
|
|
1991 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
|
|
1992 | only event loop modification you are allowed to do). |
|
|
1993 | .Sp |
1109 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1994 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(ev_periodic |
1110 | ev_tstamp now)\*(C'\fR, e.g.: |
1995 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
1111 | .Sp |
1996 | .Sp |
1112 | .Vb 4 |
1997 | .Vb 5 |
|
|
1998 | \& static ev_tstamp |
1113 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1999 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
1114 | \& { |
2000 | \& { |
1115 | \& return now + 60.; |
2001 | \& return now + 60.; |
1116 | \& } |
2002 | \& } |
1117 | .Ve |
2003 | .Ve |
1118 | .Sp |
2004 | .Sp |
1119 | It must return the next time to trigger, based on the passed time value |
2005 | It must return the next time to trigger, based on the passed time value |
1120 | (that is, the lowest time value larger than to the second argument). It |
2006 | (that is, the lowest time value larger than to the second argument). It |
1121 | will usually be called just before the callback will be triggered, but |
2007 | will usually be called just before the callback will be triggered, but |
1122 | might be called at other times, too. |
2008 | might be called at other times, too. |
1123 | .Sp |
2009 | .Sp |
1124 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is later than the |
2010 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
1125 | passed \f(CI\*(C`now\*(C'\fI value\fR. Not even \f(CW\*(C`now\*(C'\fR itself will do, it \fImust\fR be larger. |
2011 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
1126 | .Sp |
2012 | .Sp |
1127 | This can be used to create very complex timers, such as a timer that |
2013 | This can be used to create very complex timers, such as a timer that |
1128 | triggers on each midnight, local time. To do this, you would calculate the |
2014 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
1129 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2015 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1130 | you do this is, again, up to you (but it is not trivial, which is the main |
2016 | you do this is, again, up to you (but it is not trivial, which is the main |
1131 | reason I omitted it as an example). |
2017 | reason I omitted it as an example). |
1132 | .RE |
2018 | .RE |
1133 | .RS 4 |
2019 | .RS 4 |
… | |
… | |
1136 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2022 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1137 | Simply stops and restarts the periodic watcher again. This is only useful |
2023 | Simply stops and restarts the periodic watcher again. This is only useful |
1138 | when you changed some parameters or the reschedule callback would return |
2024 | when you changed some parameters or the reschedule callback would return |
1139 | a different time than the last time it was called (e.g. in a crond like |
2025 | a different time than the last time it was called (e.g. in a crond like |
1140 | program when the crontabs have changed). |
2026 | program when the crontabs have changed). |
|
|
2027 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
2028 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
2029 | When active, returns the absolute time that the watcher is supposed |
|
|
2030 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2031 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2032 | rescheduling modes. |
|
|
2033 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
2034 | .IX Item "ev_tstamp offset [read-write]" |
|
|
2035 | When repeating, this contains the offset value, otherwise this is the |
|
|
2036 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2037 | although libev might modify this value for better numerical stability). |
|
|
2038 | .Sp |
|
|
2039 | Can be modified any time, but changes only take effect when the periodic |
|
|
2040 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1141 | .IP "ev_tstamp interval [read\-write]" 4 |
2041 | .IP "ev_tstamp interval [read\-write]" 4 |
1142 | .IX Item "ev_tstamp interval [read-write]" |
2042 | .IX Item "ev_tstamp interval [read-write]" |
1143 | The current interval value. Can be modified any time, but changes only |
2043 | The current interval value. Can be modified any time, but changes only |
1144 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
2044 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1145 | called. |
2045 | called. |
1146 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
2046 | .IP "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1147 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
2047 | .IX Item "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write]" |
1148 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
2048 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1149 | switched off. Can be changed any time, but changes only take effect when |
2049 | switched off. Can be changed any time, but changes only take effect when |
1150 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2050 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1151 | .PP |
2051 | .PP |
|
|
2052 | \fIExamples\fR |
|
|
2053 | .IX Subsection "Examples" |
|
|
2054 | .PP |
1152 | Example: call a callback every hour, or, more precisely, whenever the |
2055 | Example: Call a callback every hour, or, more precisely, whenever the |
1153 | system clock is divisible by 3600. The callback invocation times have |
2056 | system time is divisible by 3600. The callback invocation times have |
1154 | potentially a lot of jittering, but good long-term stability. |
2057 | potentially a lot of jitter, but good long-term stability. |
1155 | .PP |
2058 | .PP |
1156 | .Vb 5 |
2059 | .Vb 5 |
1157 | \& static void |
2060 | \& static void |
1158 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
2061 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1159 | \& { |
2062 | \& { |
1160 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2063 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1161 | \& } |
2064 | \& } |
1162 | .Ve |
2065 | \& |
1163 | .PP |
|
|
1164 | .Vb 3 |
|
|
1165 | \& struct ev_periodic hourly_tick; |
2066 | \& ev_periodic hourly_tick; |
1166 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
2067 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1167 | \& ev_periodic_start (loop, &hourly_tick); |
2068 | \& ev_periodic_start (loop, &hourly_tick); |
1168 | .Ve |
2069 | .Ve |
1169 | .PP |
2070 | .PP |
1170 | Example: the same as above, but use a reschedule callback to do it: |
2071 | Example: The same as above, but use a reschedule callback to do it: |
1171 | .PP |
2072 | .PP |
1172 | .Vb 1 |
2073 | .Vb 1 |
1173 | \& #include <math.h> |
2074 | \& #include <math.h> |
1174 | .Ve |
2075 | \& |
1175 | .PP |
|
|
1176 | .Vb 5 |
|
|
1177 | \& static ev_tstamp |
2076 | \& static ev_tstamp |
1178 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
2077 | \& my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1179 | \& { |
2078 | \& { |
1180 | \& return fmod (now, 3600.) + 3600.; |
2079 | \& return now + (3600. \- fmod (now, 3600.)); |
1181 | \& } |
2080 | \& } |
1182 | .Ve |
2081 | \& |
1183 | .PP |
|
|
1184 | .Vb 1 |
|
|
1185 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
2082 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1186 | .Ve |
2083 | .Ve |
1187 | .PP |
2084 | .PP |
1188 | Example: call a callback every hour, starting now: |
2085 | Example: Call a callback every hour, starting now: |
1189 | .PP |
2086 | .PP |
1190 | .Vb 4 |
2087 | .Vb 4 |
1191 | \& struct ev_periodic hourly_tick; |
2088 | \& ev_periodic hourly_tick; |
1192 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2089 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1193 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2090 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1194 | \& ev_periodic_start (loop, &hourly_tick); |
2091 | \& ev_periodic_start (loop, &hourly_tick); |
1195 | .Ve |
2092 | .Ve |
1196 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2093 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
1197 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2094 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1198 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2095 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1199 | Signal watchers will trigger an event when the process receives a specific |
2096 | Signal watchers will trigger an event when the process receives a specific |
1200 | signal one or more times. Even though signals are very asynchronous, libev |
2097 | signal one or more times. Even though signals are very asynchronous, libev |
1201 | will try it's best to deliver signals synchronously, i.e. as part of the |
2098 | will try it's best to deliver signals synchronously, i.e. as part of the |
1202 | normal event processing, like any other event. |
2099 | normal event processing, like any other event. |
1203 | .PP |
2100 | .PP |
|
|
2101 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
|
|
2102 | do without libev and forget about sharing the signal. You can even use |
|
|
2103 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
|
|
2104 | .PP |
1204 | You can configure as many watchers as you like per signal. Only when the |
2105 | You can configure as many watchers as you like per signal. Only when the |
1205 | first watcher gets started will libev actually register a signal watcher |
2106 | first watcher gets started will libev actually register a signal handler |
1206 | with the kernel (thus it coexists with your own signal handlers as long |
2107 | with the kernel (thus it coexists with your own signal handlers as long as |
1207 | as you don't register any with libev). Similarly, when the last signal |
2108 | you don't register any with libev for the same signal). Similarly, when |
1208 | watcher for a signal is stopped libev will reset the signal handler to |
2109 | the last signal watcher for a signal is stopped, libev will reset the |
1209 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
2110 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
2111 | .PP |
|
|
2112 | If possible and supported, libev will install its handlers with |
|
|
2113 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
|
|
2114 | interrupted. If you have a problem with system calls getting interrupted by |
|
|
2115 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
2116 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2117 | .PP |
|
|
2118 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2119 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1210 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2120 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1211 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2121 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1212 | .PD 0 |
2122 | .PD 0 |
1213 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
2123 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1214 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
2124 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
… | |
… | |
1216 | Configures the watcher to trigger on the given signal number (usually one |
2126 | Configures the watcher to trigger on the given signal number (usually one |
1217 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
2127 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1218 | .IP "int signum [read\-only]" 4 |
2128 | .IP "int signum [read\-only]" 4 |
1219 | .IX Item "int signum [read-only]" |
2129 | .IX Item "int signum [read-only]" |
1220 | The signal the watcher watches out for. |
2130 | The signal the watcher watches out for. |
|
|
2131 | .PP |
|
|
2132 | \fIExamples\fR |
|
|
2133 | .IX Subsection "Examples" |
|
|
2134 | .PP |
|
|
2135 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
|
|
2136 | .PP |
|
|
2137 | .Vb 5 |
|
|
2138 | \& static void |
|
|
2139 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
|
|
2140 | \& { |
|
|
2141 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
2142 | \& } |
|
|
2143 | \& |
|
|
2144 | \& ev_signal signal_watcher; |
|
|
2145 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
2146 | \& ev_signal_start (loop, &signal_watcher); |
|
|
2147 | .Ve |
1221 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2148 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1222 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2149 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1223 | .IX Subsection "ev_child - watch out for process status changes" |
2150 | .IX Subsection "ev_child - watch out for process status changes" |
1224 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2151 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1225 | some child status changes (most typically when a child of yours dies). |
2152 | some child status changes (most typically when a child of yours dies or |
|
|
2153 | exits). It is permissible to install a child watcher \fIafter\fR the child |
|
|
2154 | has been forked (which implies it might have already exited), as long |
|
|
2155 | as the event loop isn't entered (or is continued from a watcher), i.e., |
|
|
2156 | forking and then immediately registering a watcher for the child is fine, |
|
|
2157 | but forking and registering a watcher a few event loop iterations later is |
|
|
2158 | not. |
|
|
2159 | .PP |
|
|
2160 | Only the default event loop is capable of handling signals, and therefore |
|
|
2161 | you can only register child watchers in the default event loop. |
|
|
2162 | .PP |
|
|
2163 | \fIProcess Interaction\fR |
|
|
2164 | .IX Subsection "Process Interaction" |
|
|
2165 | .PP |
|
|
2166 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
2167 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
2168 | the first child watcher is started after the child exits. The occurrence |
|
|
2169 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
2170 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
2171 | children, even ones not watched. |
|
|
2172 | .PP |
|
|
2173 | \fIOverriding the Built-In Processing\fR |
|
|
2174 | .IX Subsection "Overriding the Built-In Processing" |
|
|
2175 | .PP |
|
|
2176 | Libev offers no special support for overriding the built-in child |
|
|
2177 | processing, but if your application collides with libev's default child |
|
|
2178 | handler, you can override it easily by installing your own handler for |
|
|
2179 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
2180 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
2181 | event-based approach to child reaping and thus use libev's support for |
|
|
2182 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
2183 | .PP |
|
|
2184 | \fIStopping the Child Watcher\fR |
|
|
2185 | .IX Subsection "Stopping the Child Watcher" |
|
|
2186 | .PP |
|
|
2187 | Currently, the child watcher never gets stopped, even when the |
|
|
2188 | child terminates, so normally one needs to stop the watcher in the |
|
|
2189 | callback. Future versions of libev might stop the watcher automatically |
|
|
2190 | when a child exit is detected. |
|
|
2191 | .PP |
|
|
2192 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2193 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1226 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
2194 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1227 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
2195 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1228 | .PD 0 |
2196 | .PD 0 |
1229 | .IP "ev_child_set (ev_child *, int pid)" 4 |
2197 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1230 | .IX Item "ev_child_set (ev_child *, int pid)" |
2198 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1231 | .PD |
2199 | .PD |
1232 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
2200 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1233 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
2201 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1234 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
2202 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1235 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
2203 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1236 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
2204 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1237 | process causing the status change. |
2205 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
2206 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
2207 | activate the watcher when the process is stopped or continued). |
1238 | .IP "int pid [read\-only]" 4 |
2208 | .IP "int pid [read\-only]" 4 |
1239 | .IX Item "int pid [read-only]" |
2209 | .IX Item "int pid [read-only]" |
1240 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
2210 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1241 | .IP "int rpid [read\-write]" 4 |
2211 | .IP "int rpid [read\-write]" 4 |
1242 | .IX Item "int rpid [read-write]" |
2212 | .IX Item "int rpid [read-write]" |
… | |
… | |
1244 | .IP "int rstatus [read\-write]" 4 |
2214 | .IP "int rstatus [read\-write]" 4 |
1245 | .IX Item "int rstatus [read-write]" |
2215 | .IX Item "int rstatus [read-write]" |
1246 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
2216 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1247 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
2217 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1248 | .PP |
2218 | .PP |
1249 | Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
2219 | \fIExamples\fR |
|
|
2220 | .IX Subsection "Examples" |
1250 | .PP |
2221 | .PP |
|
|
2222 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
2223 | its completion. |
|
|
2224 | .PP |
1251 | .Vb 5 |
2225 | .Vb 1 |
|
|
2226 | \& ev_child cw; |
|
|
2227 | \& |
1252 | \& static void |
2228 | \& static void |
1253 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
2229 | \& child_cb (EV_P_ ev_child *w, int revents) |
1254 | \& { |
2230 | \& { |
1255 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2231 | \& ev_child_stop (EV_A_ w); |
|
|
2232 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1256 | \& } |
2233 | \& } |
1257 | .Ve |
2234 | \& |
1258 | .PP |
2235 | \& pid_t pid = fork (); |
1259 | .Vb 3 |
2236 | \& |
1260 | \& struct ev_signal signal_watcher; |
2237 | \& if (pid < 0) |
1261 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2238 | \& // error |
1262 | \& ev_signal_start (loop, &sigint_cb); |
2239 | \& else if (pid == 0) |
|
|
2240 | \& { |
|
|
2241 | \& // the forked child executes here |
|
|
2242 | \& exit (1); |
|
|
2243 | \& } |
|
|
2244 | \& else |
|
|
2245 | \& { |
|
|
2246 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
2247 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
2248 | \& } |
1263 | .Ve |
2249 | .Ve |
1264 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2250 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1265 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2251 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1266 | .IX Subsection "ev_stat - did the file attributes just change?" |
2252 | .IX Subsection "ev_stat - did the file attributes just change?" |
1267 | This watches a filesystem path for attribute changes. That is, it calls |
2253 | This watches a file system path for attribute changes. That is, it calls |
1268 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
2254 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
1269 | compared to the last time, invoking the callback if it did. |
2255 | and sees if it changed compared to the last time, invoking the callback if |
|
|
2256 | it did. |
1270 | .PP |
2257 | .PP |
1271 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2258 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1272 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
2259 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
1273 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
2260 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
1274 | otherwise always forced to be at least one) and all the other fields of |
2261 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
1275 | the stat buffer having unspecified contents. |
2262 | least one) and all the other fields of the stat buffer having unspecified |
|
|
2263 | contents. |
1276 | .PP |
2264 | .PP |
1277 | Since there is no standard to do this, the portable implementation simply |
2265 | The path \fImust not\fR end in a slash or contain special components such as |
1278 | calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You |
2266 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
1279 | can specify a recommended polling interval for this case. If you specify |
2267 | your working directory changes, then the behaviour is undefined. |
1280 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
2268 | .PP |
1281 | unspecified default\fR value will be used (which you can expect to be around |
2269 | Since there is no portable change notification interface available, the |
1282 | five seconds, although this might change dynamically). Libev will also |
2270 | portable implementation simply calls \f(CWstat(2)\fR regularly on the path |
1283 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
2271 | to see if it changed somehow. You can specify a recommended polling |
1284 | usually overkill. |
2272 | interval for this case. If you specify a polling interval of \f(CW0\fR (highly |
|
|
2273 | recommended!) then a \fIsuitable, unspecified default\fR value will be used |
|
|
2274 | (which you can expect to be around five seconds, although this might |
|
|
2275 | change dynamically). Libev will also impose a minimum interval which is |
|
|
2276 | currently around \f(CW0.1\fR, but that's usually overkill. |
1285 | .PP |
2277 | .PP |
1286 | This watcher type is not meant for massive numbers of stat watchers, |
2278 | This watcher type is not meant for massive numbers of stat watchers, |
1287 | as even with OS-supported change notifications, this can be |
2279 | as even with OS-supported change notifications, this can be |
1288 | resource\-intensive. |
2280 | resource-intensive. |
1289 | .PP |
2281 | .PP |
1290 | At the time of this writing, no specific \s-1OS\s0 backends are implemented, but |
2282 | At the time of this writing, the only OS-specific interface implemented |
1291 | if demand increases, at least a kqueue and inotify backend will be added. |
2283 | is the Linux inotify interface (implementing kqueue support is left as an |
|
|
2284 | exercise for the reader. Note, however, that the author sees no way of |
|
|
2285 | implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue, except as a hint). |
|
|
2286 | .PP |
|
|
2287 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
2288 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
2289 | .PP |
|
|
2290 | Libev by default (unless the user overrides this) uses the default |
|
|
2291 | compilation environment, which means that on systems with large file |
|
|
2292 | support disabled by default, you get the 32 bit version of the stat |
|
|
2293 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
2294 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
2295 | compile libev with the same flags to get binary compatibility. This is |
|
|
2296 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
2297 | most noticeably displayed with ev_stat and large file support. |
|
|
2298 | .PP |
|
|
2299 | The solution for this is to lobby your distribution maker to make large |
|
|
2300 | file interfaces available by default (as e.g. FreeBSD does) and not |
|
|
2301 | optional. Libev cannot simply switch on large file support because it has |
|
|
2302 | to exchange stat structures with application programs compiled using the |
|
|
2303 | default compilation environment. |
|
|
2304 | .PP |
|
|
2305 | \fIInotify and Kqueue\fR |
|
|
2306 | .IX Subsection "Inotify and Kqueue" |
|
|
2307 | .PP |
|
|
2308 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev and present at |
|
|
2309 | runtime, it will be used to speed up change detection where possible. The |
|
|
2310 | inotify descriptor will be created lazily when the first \f(CW\*(C`ev_stat\*(C'\fR |
|
|
2311 | watcher is being started. |
|
|
2312 | .PP |
|
|
2313 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
2314 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
2315 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
2316 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
|
|
2317 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2318 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2319 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2320 | xfs are fully working) libev usually gets away without polling. |
|
|
2321 | .PP |
|
|
2322 | There is no support for kqueue, as apparently it cannot be used to |
|
|
2323 | implement this functionality, due to the requirement of having a file |
|
|
2324 | descriptor open on the object at all times, and detecting renames, unlinks |
|
|
2325 | etc. is difficult. |
|
|
2326 | .PP |
|
|
2327 | \fI\f(CI\*(C`stat ()\*(C'\fI is a synchronous operation\fR |
|
|
2328 | .IX Subsection "stat () is a synchronous operation" |
|
|
2329 | .PP |
|
|
2330 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2331 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
|
|
2332 | ()\*(C'\fR, which is a synchronous operation. |
|
|
2333 | .PP |
|
|
2334 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2335 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2336 | as the path data is usually in memory already (except when starting the |
|
|
2337 | watcher). |
|
|
2338 | .PP |
|
|
2339 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
|
|
2340 | time due to network issues, and even under good conditions, a stat call |
|
|
2341 | often takes multiple milliseconds. |
|
|
2342 | .PP |
|
|
2343 | Therefore, it is best to avoid using \f(CW\*(C`ev_stat\*(C'\fR watchers on networked |
|
|
2344 | paths, although this is fully supported by libev. |
|
|
2345 | .PP |
|
|
2346 | \fIThe special problem of stat time resolution\fR |
|
|
2347 | .IX Subsection "The special problem of stat time resolution" |
|
|
2348 | .PP |
|
|
2349 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
|
|
2350 | and even on systems where the resolution is higher, most file systems |
|
|
2351 | still only support whole seconds. |
|
|
2352 | .PP |
|
|
2353 | That means that, if the time is the only thing that changes, you can |
|
|
2354 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
2355 | calls your callback, which does something. When there is another update |
|
|
2356 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect unless the |
|
|
2357 | stat data does change in other ways (e.g. file size). |
|
|
2358 | .PP |
|
|
2359 | The solution to this is to delay acting on a change for slightly more |
|
|
2360 | than a second (or till slightly after the next full second boundary), using |
|
|
2361 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
2362 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
2363 | .PP |
|
|
2364 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
2365 | of some operating systems (where the second counter of the current time |
|
|
2366 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
2367 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
2368 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
2369 | update file times then there will be a small window where the kernel uses |
|
|
2370 | the previous second to update file times but libev might already execute |
|
|
2371 | the timer callback). |
|
|
2372 | .PP |
|
|
2373 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2374 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1292 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
2375 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1293 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
2376 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1294 | .PD 0 |
2377 | .PD 0 |
1295 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
2378 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1296 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
2379 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
… | |
… | |
1299 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
2382 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1300 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
2383 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1301 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
2384 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1302 | path for as long as the watcher is active. |
2385 | path for as long as the watcher is active. |
1303 | .Sp |
2386 | .Sp |
1304 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
2387 | The callback will receive an \f(CW\*(C`EV_STAT\*(C'\fR event when a change was detected, |
1305 | relative to the attributes at the time the watcher was started (or the |
2388 | relative to the attributes at the time the watcher was started (or the |
1306 | last change was detected). |
2389 | last change was detected). |
1307 | .IP "ev_stat_stat (ev_stat *)" 4 |
2390 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1308 | .IX Item "ev_stat_stat (ev_stat *)" |
2391 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1309 | Updates the stat buffer immediately with new values. If you change the |
2392 | Updates the stat buffer immediately with new values. If you change the |
1310 | watched path in your callback, you could call this fucntion to avoid |
2393 | watched path in your callback, you could call this function to avoid |
1311 | detecting this change (while introducing a race condition). Can also be |
2394 | detecting this change (while introducing a race condition if you are not |
1312 | useful simply to find out the new values. |
2395 | the only one changing the path). Can also be useful simply to find out the |
|
|
2396 | new values. |
1313 | .IP "ev_statdata attr [read\-only]" 4 |
2397 | .IP "ev_statdata attr [read\-only]" 4 |
1314 | .IX Item "ev_statdata attr [read-only]" |
2398 | .IX Item "ev_statdata attr [read-only]" |
1315 | The most-recently detected attributes of the file. Although the type is of |
2399 | The most-recently detected attributes of the file. Although the type is |
1316 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
2400 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
2401 | suitable for your system, but you can only rely on the POSIX-standardised |
1317 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
2402 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
1318 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
2403 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1319 | .IP "ev_statdata prev [read\-only]" 4 |
2404 | .IP "ev_statdata prev [read\-only]" 4 |
1320 | .IX Item "ev_statdata prev [read-only]" |
2405 | .IX Item "ev_statdata prev [read-only]" |
1321 | The previous attributes of the file. The callback gets invoked whenever |
2406 | The previous attributes of the file. The callback gets invoked whenever |
1322 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
2407 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
2408 | differ: \f(CW\*(C`st_dev\*(C'\fR, \f(CW\*(C`st_ino\*(C'\fR, \f(CW\*(C`st_mode\*(C'\fR, \f(CW\*(C`st_nlink\*(C'\fR, \f(CW\*(C`st_uid\*(C'\fR, |
|
|
2409 | \&\f(CW\*(C`st_gid\*(C'\fR, \f(CW\*(C`st_rdev\*(C'\fR, \f(CW\*(C`st_size\*(C'\fR, \f(CW\*(C`st_atime\*(C'\fR, \f(CW\*(C`st_mtime\*(C'\fR, \f(CW\*(C`st_ctime\*(C'\fR. |
1323 | .IP "ev_tstamp interval [read\-only]" 4 |
2410 | .IP "ev_tstamp interval [read\-only]" 4 |
1324 | .IX Item "ev_tstamp interval [read-only]" |
2411 | .IX Item "ev_tstamp interval [read-only]" |
1325 | The specified interval. |
2412 | The specified interval. |
1326 | .IP "const char *path [read\-only]" 4 |
2413 | .IP "const char *path [read\-only]" 4 |
1327 | .IX Item "const char *path [read-only]" |
2414 | .IX Item "const char *path [read-only]" |
1328 | The filesystem path that is being watched. |
2415 | The file system path that is being watched. |
|
|
2416 | .PP |
|
|
2417 | \fIExamples\fR |
|
|
2418 | .IX Subsection "Examples" |
1329 | .PP |
2419 | .PP |
1330 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
2420 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1331 | .PP |
2421 | .PP |
1332 | .Vb 15 |
2422 | .Vb 10 |
1333 | \& static void |
2423 | \& static void |
1334 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
2424 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1335 | \& { |
2425 | \& { |
1336 | \& /* /etc/passwd changed in some way */ |
2426 | \& /* /etc/passwd changed in some way */ |
1337 | \& if (w->attr.st_nlink) |
2427 | \& if (w\->attr.st_nlink) |
1338 | \& { |
2428 | \& { |
1339 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
2429 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1340 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
2430 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1341 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
2431 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1342 | \& } |
2432 | \& } |
1343 | \& else |
2433 | \& else |
1344 | \& /* you shalt not abuse printf for puts */ |
2434 | \& /* you shalt not abuse printf for puts */ |
1345 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
2435 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1346 | \& "if this is windows, they already arrived\en"); |
2436 | \& "if this is windows, they already arrived\en"); |
1347 | \& } |
2437 | \& } |
|
|
2438 | \& |
|
|
2439 | \& ... |
|
|
2440 | \& ev_stat passwd; |
|
|
2441 | \& |
|
|
2442 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
2443 | \& ev_stat_start (loop, &passwd); |
1348 | .Ve |
2444 | .Ve |
|
|
2445 | .PP |
|
|
2446 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
2447 | miss updates (however, frequent updates will delay processing, too, so |
|
|
2448 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
2449 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1349 | .PP |
2450 | .PP |
1350 | .Vb 2 |
2451 | .Vb 2 |
|
|
2452 | \& static ev_stat passwd; |
|
|
2453 | \& static ev_timer timer; |
|
|
2454 | \& |
|
|
2455 | \& static void |
|
|
2456 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2457 | \& { |
|
|
2458 | \& ev_timer_stop (EV_A_ w); |
|
|
2459 | \& |
|
|
2460 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
2461 | \& } |
|
|
2462 | \& |
|
|
2463 | \& static void |
|
|
2464 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
2465 | \& { |
|
|
2466 | \& /* reset the one\-second timer */ |
|
|
2467 | \& ev_timer_again (EV_A_ &timer); |
|
|
2468 | \& } |
|
|
2469 | \& |
1351 | \& ... |
2470 | \& ... |
1352 | \& ev_stat passwd; |
|
|
1353 | .Ve |
|
|
1354 | .PP |
|
|
1355 | .Vb 2 |
|
|
1356 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
2471 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1357 | \& ev_stat_start (loop, &passwd); |
2472 | \& ev_stat_start (loop, &passwd); |
|
|
2473 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1358 | .Ve |
2474 | .Ve |
1359 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2475 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1360 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2476 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1361 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2477 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1362 | Idle watchers trigger events when there are no other events are pending |
2478 | Idle watchers trigger events when no other events of the same or higher |
1363 | (prepare, check and other idle watchers do not count). That is, as long |
2479 | priority are pending (prepare, check and other idle watchers do not count |
1364 | as your process is busy handling sockets or timeouts (or even signals, |
2480 | as receiving \*(L"events\*(R"). |
1365 | imagine) it will not be triggered. But when your process is idle all idle |
2481 | .PP |
1366 | watchers are being called again and again, once per event loop iteration \- |
2482 | That is, as long as your process is busy handling sockets or timeouts |
|
|
2483 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
2484 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
2485 | are pending), the idle watchers are being called once per event loop |
1367 | until stopped, that is, or your process receives more events and becomes |
2486 | iteration \- until stopped, that is, or your process receives more events |
1368 | busy. |
2487 | and becomes busy again with higher priority stuff. |
1369 | .PP |
2488 | .PP |
1370 | The most noteworthy effect is that as long as any idle watchers are |
2489 | The most noteworthy effect is that as long as any idle watchers are |
1371 | active, the process will not block when waiting for new events. |
2490 | active, the process will not block when waiting for new events. |
1372 | .PP |
2491 | .PP |
1373 | Apart from keeping your process non-blocking (which is a useful |
2492 | Apart from keeping your process non-blocking (which is a useful |
1374 | effect on its own sometimes), idle watchers are a good place to do |
2493 | effect on its own sometimes), idle watchers are a good place to do |
1375 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
2494 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1376 | event loop has handled all outstanding events. |
2495 | event loop has handled all outstanding events. |
|
|
2496 | .PP |
|
|
2497 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2498 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1377 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2499 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
1378 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2500 | .IX Item "ev_idle_init (ev_idle *, callback)" |
1379 | Initialises and configures the idle watcher \- it has no parameters of any |
2501 | Initialises and configures the idle watcher \- it has no parameters of any |
1380 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2502 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1381 | believe me. |
2503 | believe me. |
1382 | .PP |
2504 | .PP |
|
|
2505 | \fIExamples\fR |
|
|
2506 | .IX Subsection "Examples" |
|
|
2507 | .PP |
1383 | Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the |
2508 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1384 | callback, free it. Alos, use no error checking, as usual. |
2509 | callback, free it. Also, use no error checking, as usual. |
1385 | .PP |
2510 | .PP |
1386 | .Vb 7 |
2511 | .Vb 7 |
1387 | \& static void |
2512 | \& static void |
1388 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2513 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1389 | \& { |
2514 | \& { |
1390 | \& free (w); |
2515 | \& free (w); |
1391 | \& // now do something you wanted to do when the program has |
2516 | \& // now do something you wanted to do when the program has |
1392 | \& // no longer asnything immediate to do. |
2517 | \& // no longer anything immediate to do. |
1393 | \& } |
2518 | \& } |
1394 | .Ve |
2519 | \& |
1395 | .PP |
|
|
1396 | .Vb 3 |
|
|
1397 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2520 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1398 | \& ev_idle_init (idle_watcher, idle_cb); |
2521 | \& ev_idle_init (idle_watcher, idle_cb); |
1399 | \& ev_idle_start (loop, idle_cb); |
2522 | \& ev_idle_start (loop, idle_cb); |
1400 | .Ve |
2523 | .Ve |
1401 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2524 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1402 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2525 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
1403 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2526 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
1404 | Prepare and check watchers are usually (but not always) used in tandem: |
2527 | Prepare and check watchers are usually (but not always) used in pairs: |
1405 | prepare watchers get invoked before the process blocks and check watchers |
2528 | prepare watchers get invoked before the process blocks and check watchers |
1406 | afterwards. |
2529 | afterwards. |
1407 | .PP |
2530 | .PP |
1408 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
2531 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
1409 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2532 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
… | |
… | |
1412 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2535 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
1413 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
2536 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
1414 | called in pairs bracketing the blocking call. |
2537 | called in pairs bracketing the blocking call. |
1415 | .PP |
2538 | .PP |
1416 | Their main purpose is to integrate other event mechanisms into libev and |
2539 | Their main purpose is to integrate other event mechanisms into libev and |
1417 | their use is somewhat advanced. This could be used, for example, to track |
2540 | their use is somewhat advanced. They could be used, for example, to track |
1418 | variable changes, implement your own watchers, integrate net-snmp or a |
2541 | variable changes, implement your own watchers, integrate net-snmp or a |
1419 | coroutine library and lots more. They are also occasionally useful if |
2542 | coroutine library and lots more. They are also occasionally useful if |
1420 | you cache some data and want to flush it before blocking (for example, |
2543 | you cache some data and want to flush it before blocking (for example, |
1421 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
2544 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
1422 | watcher). |
2545 | watcher). |
1423 | .PP |
2546 | .PP |
1424 | This is done by examining in each prepare call which file descriptors need |
2547 | This is done by examining in each prepare call which file descriptors |
1425 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
2548 | need to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers |
1426 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
2549 | for them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many |
1427 | provide just this functionality). Then, in the check watcher you check for |
2550 | libraries provide exactly this functionality). Then, in the check watcher, |
1428 | any events that occured (by checking the pending status of all watchers |
2551 | you check for any events that occurred (by checking the pending status |
1429 | and stopping them) and call back into the library. The I/O and timer |
2552 | of all watchers and stopping them) and call back into the library. The |
1430 | callbacks will never actually be called (but must be valid nevertheless, |
2553 | I/O and timer callbacks will never actually be called (but must be valid |
1431 | because you never know, you know?). |
2554 | nevertheless, because you never know, you know?). |
1432 | .PP |
2555 | .PP |
1433 | As another example, the Perl Coro module uses these hooks to integrate |
2556 | As another example, the Perl Coro module uses these hooks to integrate |
1434 | coroutines into libev programs, by yielding to other active coroutines |
2557 | coroutines into libev programs, by yielding to other active coroutines |
1435 | during each prepare and only letting the process block if no coroutines |
2558 | during each prepare and only letting the process block if no coroutines |
1436 | are ready to run (it's actually more complicated: it only runs coroutines |
2559 | are ready to run (it's actually more complicated: it only runs coroutines |
1437 | with priority higher than or equal to the event loop and one coroutine |
2560 | with priority higher than or equal to the event loop and one coroutine |
1438 | of lower priority, but only once, using idle watchers to keep the event |
2561 | of lower priority, but only once, using idle watchers to keep the event |
1439 | loop from blocking if lower-priority coroutines are active, thus mapping |
2562 | loop from blocking if lower-priority coroutines are active, thus mapping |
1440 | low-priority coroutines to idle/background tasks). |
2563 | low-priority coroutines to idle/background tasks). |
|
|
2564 | .PP |
|
|
2565 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
2566 | priority, to ensure that they are being run before any other watchers |
|
|
2567 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
|
|
2568 | .PP |
|
|
2569 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
|
|
2570 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
|
|
2571 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
|
|
2572 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
|
|
2573 | loops those other event loops might be in an unusable state until their |
|
|
2574 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
|
|
2575 | others). |
|
|
2576 | .PP |
|
|
2577 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2578 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1441 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2579 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1442 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2580 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1443 | .PD 0 |
2581 | .PD 0 |
1444 | .IP "ev_check_init (ev_check *, callback)" 4 |
2582 | .IP "ev_check_init (ev_check *, callback)" 4 |
1445 | .IX Item "ev_check_init (ev_check *, callback)" |
2583 | .IX Item "ev_check_init (ev_check *, callback)" |
1446 | .PD |
2584 | .PD |
1447 | Initialises and configures the prepare or check watcher \- they have no |
2585 | Initialises and configures the prepare or check watcher \- they have no |
1448 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2586 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1449 | macros, but using them is utterly, utterly and completely pointless. |
2587 | macros, but using them is utterly, utterly, utterly and completely |
|
|
2588 | pointless. |
1450 | .PP |
2589 | .PP |
1451 | Example: To include a library such as adns, you would add \s-1IO\s0 watchers |
2590 | \fIExamples\fR |
1452 | and a timeout watcher in a prepare handler, as required by libadns, and |
2591 | .IX Subsection "Examples" |
|
|
2592 | .PP |
|
|
2593 | There are a number of principal ways to embed other event loops or modules |
|
|
2594 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2595 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2596 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
|
|
2597 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
|
|
2598 | Glib event loop). |
|
|
2599 | .PP |
|
|
2600 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1453 | in a check watcher, destroy them and call into libadns. What follows is |
2601 | and in a check watcher, destroy them and call into libadns. What follows |
1454 | pseudo-code only of course: |
2602 | is pseudo-code only of course. This requires you to either use a low |
|
|
2603 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2604 | the callbacks for the IO/timeout watchers might not have been called yet. |
1455 | .PP |
2605 | .PP |
1456 | .Vb 2 |
2606 | .Vb 2 |
1457 | \& static ev_io iow [nfd]; |
2607 | \& static ev_io iow [nfd]; |
1458 | \& static ev_timer tw; |
2608 | \& static ev_timer tw; |
1459 | .Ve |
2609 | \& |
1460 | .PP |
|
|
1461 | .Vb 9 |
|
|
1462 | \& static void |
2610 | \& static void |
1463 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2611 | \& io_cb (struct ev_loop *loop, ev_io *w, int revents) |
1464 | \& { |
2612 | \& { |
1465 | \& // set the relevant poll flags |
|
|
1466 | \& // could also call adns_processreadable etc. here |
|
|
1467 | \& struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1468 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1469 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1470 | \& } |
2613 | \& } |
1471 | .Ve |
2614 | \& |
1472 | .PP |
|
|
1473 | .Vb 7 |
|
|
1474 | \& // create io watchers for each fd and a timer before blocking |
2615 | \& // create io watchers for each fd and a timer before blocking |
1475 | \& static void |
2616 | \& static void |
1476 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2617 | \& adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
1477 | \& { |
2618 | \& { |
1478 | \& int timeout = 3600000;truct pollfd fds [nfd]; |
2619 | \& int timeout = 3600000; |
|
|
2620 | \& struct pollfd fds [nfd]; |
1479 | \& // actual code will need to loop here and realloc etc. |
2621 | \& // actual code will need to loop here and realloc etc. |
1480 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2622 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1481 | .Ve |
2623 | \& |
1482 | .PP |
|
|
1483 | .Vb 3 |
|
|
1484 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2624 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1485 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2625 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1486 | \& ev_timer_start (loop, &tw); |
2626 | \& ev_timer_start (loop, &tw); |
1487 | .Ve |
2627 | \& |
1488 | .PP |
|
|
1489 | .Vb 6 |
|
|
1490 | \& // create on ev_io per pollfd |
2628 | \& // create one ev_io per pollfd |
1491 | \& for (int i = 0; i < nfd; ++i) |
2629 | \& for (int i = 0; i < nfd; ++i) |
1492 | \& { |
2630 | \& { |
1493 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2631 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1494 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2632 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1495 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2633 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
2634 | \& |
|
|
2635 | \& fds [i].revents = 0; |
|
|
2636 | \& ev_io_start (loop, iow + i); |
|
|
2637 | \& } |
|
|
2638 | \& } |
|
|
2639 | \& |
|
|
2640 | \& // stop all watchers after blocking |
|
|
2641 | \& static void |
|
|
2642 | \& adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
|
|
2643 | \& { |
|
|
2644 | \& ev_timer_stop (loop, &tw); |
|
|
2645 | \& |
|
|
2646 | \& for (int i = 0; i < nfd; ++i) |
|
|
2647 | \& { |
|
|
2648 | \& // set the relevant poll flags |
|
|
2649 | \& // could also call adns_processreadable etc. here |
|
|
2650 | \& struct pollfd *fd = fds + i; |
|
|
2651 | \& int revents = ev_clear_pending (iow + i); |
|
|
2652 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2653 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2654 | \& |
|
|
2655 | \& // now stop the watcher |
|
|
2656 | \& ev_io_stop (loop, iow + i); |
|
|
2657 | \& } |
|
|
2658 | \& |
|
|
2659 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2660 | \& } |
1496 | .Ve |
2661 | .Ve |
|
|
2662 | .PP |
|
|
2663 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2664 | in the prepare watcher and would dispose of the check watcher. |
|
|
2665 | .PP |
|
|
2666 | Method 3: If the module to be embedded supports explicit event |
|
|
2667 | notification (libadns does), you can also make use of the actual watcher |
|
|
2668 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1497 | .PP |
2669 | .PP |
1498 | .Vb 5 |
2670 | .Vb 5 |
1499 | \& fds [i].revents = 0; |
|
|
1500 | \& iow [i].data = fds + i; |
|
|
1501 | \& ev_io_start (loop, iow + i); |
|
|
1502 | \& } |
|
|
1503 | \& } |
|
|
1504 | .Ve |
|
|
1505 | .PP |
|
|
1506 | .Vb 5 |
|
|
1507 | \& // stop all watchers after blocking |
|
|
1508 | \& static void |
2671 | \& static void |
1509 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2672 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
1510 | \& { |
2673 | \& { |
1511 | \& ev_timer_stop (loop, &tw); |
2674 | \& adns_state ads = (adns_state)w\->data; |
1512 | .Ve |
2675 | \& update_now (EV_A); |
1513 | .PP |
2676 | \& |
1514 | .Vb 2 |
2677 | \& adns_processtimeouts (ads, &tv_now); |
1515 | \& for (int i = 0; i < nfd; ++i) |
|
|
1516 | \& ev_io_stop (loop, iow + i); |
|
|
1517 | .Ve |
|
|
1518 | .PP |
|
|
1519 | .Vb 2 |
|
|
1520 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1521 | \& } |
2678 | \& } |
|
|
2679 | \& |
|
|
2680 | \& static void |
|
|
2681 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2682 | \& { |
|
|
2683 | \& adns_state ads = (adns_state)w\->data; |
|
|
2684 | \& update_now (EV_A); |
|
|
2685 | \& |
|
|
2686 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2687 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2688 | \& } |
|
|
2689 | \& |
|
|
2690 | \& // do not ever call adns_afterpoll |
|
|
2691 | .Ve |
|
|
2692 | .PP |
|
|
2693 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2694 | want to embed is not flexible enough to support it. Instead, you can |
|
|
2695 | override their poll function. The drawback with this solution is that the |
|
|
2696 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
|
|
2697 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
|
|
2698 | libglib event loop. |
|
|
2699 | .PP |
|
|
2700 | .Vb 4 |
|
|
2701 | \& static gint |
|
|
2702 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2703 | \& { |
|
|
2704 | \& int got_events = 0; |
|
|
2705 | \& |
|
|
2706 | \& for (n = 0; n < nfds; ++n) |
|
|
2707 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2708 | \& |
|
|
2709 | \& if (timeout >= 0) |
|
|
2710 | \& // create/start timer |
|
|
2711 | \& |
|
|
2712 | \& // poll |
|
|
2713 | \& ev_loop (EV_A_ 0); |
|
|
2714 | \& |
|
|
2715 | \& // stop timer again |
|
|
2716 | \& if (timeout >= 0) |
|
|
2717 | \& ev_timer_stop (EV_A_ &to); |
|
|
2718 | \& |
|
|
2719 | \& // stop io watchers again \- their callbacks should have set |
|
|
2720 | \& for (n = 0; n < nfds; ++n) |
|
|
2721 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2722 | \& |
|
|
2723 | \& return got_events; |
|
|
2724 | \& } |
1522 | .Ve |
2725 | .Ve |
1523 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2726 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1524 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2727 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1525 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2728 | .IX Subsection "ev_embed - when one backend isn't enough..." |
1526 | This is a rather advanced watcher type that lets you embed one event loop |
2729 | This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
1532 | prioritise I/O. |
2735 | prioritise I/O. |
1533 | .PP |
2736 | .PP |
1534 | As an example for a bug workaround, the kqueue backend might only support |
2737 | As an example for a bug workaround, the kqueue backend might only support |
1535 | sockets on some platform, so it is unusable as generic backend, but you |
2738 | sockets on some platform, so it is unusable as generic backend, but you |
1536 | still want to make use of it because you have many sockets and it scales |
2739 | still want to make use of it because you have many sockets and it scales |
1537 | so nicely. In this case, you would create a kqueue-based loop and embed it |
2740 | so nicely. In this case, you would create a kqueue-based loop and embed |
1538 | into your default loop (which might use e.g. poll). Overall operation will |
2741 | it into your default loop (which might use e.g. poll). Overall operation |
1539 | be a bit slower because first libev has to poll and then call kevent, but |
2742 | will be a bit slower because first libev has to call \f(CW\*(C`poll\*(C'\fR and then |
1540 | at least you can use both at what they are best. |
2743 | \&\f(CW\*(C`kevent\*(C'\fR, but at least you can use both mechanisms for what they are |
|
|
2744 | best: \f(CW\*(C`kqueue\*(C'\fR for scalable sockets and \f(CW\*(C`poll\*(C'\fR if you want it to work :) |
1541 | .PP |
2745 | .PP |
1542 | As for prioritising I/O: rarely you have the case where some fds have |
2746 | As for prioritising I/O: under rare circumstances you have the case where |
1543 | to be watched and handled very quickly (with low latency), and even |
2747 | some fds have to be watched and handled very quickly (with low latency), |
1544 | priorities and idle watchers might have too much overhead. In this case |
2748 | and even priorities and idle watchers might have too much overhead. In |
1545 | you would put all the high priority stuff in one loop and all the rest in |
2749 | this case you would put all the high priority stuff in one loop and all |
1546 | a second one, and embed the second one in the first. |
2750 | the rest in a second one, and embed the second one in the first. |
1547 | .PP |
2751 | .PP |
1548 | As long as the watcher is active, the callback will be invoked every time |
2752 | As long as the watcher is active, the callback will be invoked every |
1549 | there might be events pending in the embedded loop. The callback must then |
2753 | time there might be events pending in the embedded loop. The callback |
1550 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
2754 | must then call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single |
1551 | their callbacks (you could also start an idle watcher to give the embedded |
2755 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
1552 | loop strictly lower priority for example). You can also set the callback |
2756 | \&\f(CW\*(C`ev_embed_sweep\*(C'\fR function directly, it could also start an idle watcher |
1553 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
2757 | to give the embedded loop strictly lower priority for example). |
1554 | embedded loop sweep. |
|
|
1555 | .PP |
2758 | .PP |
1556 | As long as the watcher is started it will automatically handle events. The |
2759 | You can also set the callback to \f(CW0\fR, in which case the embed watcher |
1557 | callback will be invoked whenever some events have been handled. You can |
2760 | will automatically execute the embedded loop sweep whenever necessary. |
1558 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
1559 | interested in that. |
|
|
1560 | .PP |
2761 | .PP |
1561 | Also, there have not currently been made special provisions for forking: |
2762 | Fork detection will be handled transparently while the \f(CW\*(C`ev_embed\*(C'\fR watcher |
1562 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
2763 | is active, i.e., the embedded loop will automatically be forked when the |
1563 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
2764 | embedding loop forks. In other cases, the user is responsible for calling |
1564 | yourself. |
2765 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR on the embedded loop. |
1565 | .PP |
2766 | .PP |
1566 | Unfortunately, not all backends are embeddable, only the ones returned by |
2767 | Unfortunately, not all backends are embeddable: only the ones returned by |
1567 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2768 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
1568 | portable one. |
2769 | portable one. |
1569 | .PP |
2770 | .PP |
1570 | So when you want to use this feature you will always have to be prepared |
2771 | So when you want to use this feature you will always have to be prepared |
1571 | that you cannot get an embeddable loop. The recommended way to get around |
2772 | that you cannot get an embeddable loop. The recommended way to get around |
1572 | this is to have a separate variables for your embeddable loop, try to |
2773 | this is to have a separate variables for your embeddable loop, try to |
1573 | create it, and if that fails, use the normal loop for everything: |
2774 | create it, and if that fails, use the normal loop for everything. |
1574 | .PP |
2775 | .PP |
1575 | .Vb 3 |
2776 | \fI\f(CI\*(C`ev_embed\*(C'\fI and fork\fR |
1576 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2777 | .IX Subsection "ev_embed and fork" |
1577 | \& struct ev_loop *loop_lo = 0; |
|
|
1578 | \& struct ev_embed embed; |
|
|
1579 | .Ve |
|
|
1580 | .PP |
2778 | .PP |
1581 | .Vb 5 |
2779 | While the \f(CW\*(C`ev_embed\*(C'\fR watcher is running, forks in the embedding loop will |
1582 | \& // see if there is a chance of getting one that works |
2780 | automatically be applied to the embedded loop as well, so no special |
1583 | \& // (remember that a flags value of 0 means autodetection) |
2781 | fork handling is required in that case. When the watcher is not running, |
1584 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2782 | however, it is still the task of the libev user to call \f(CW\*(C`ev_loop_fork ()\*(C'\fR |
1585 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2783 | as applicable. |
1586 | \& : 0; |
|
|
1587 | .Ve |
|
|
1588 | .PP |
2784 | .PP |
1589 | .Vb 8 |
2785 | \fIWatcher-Specific Functions and Data Members\fR |
1590 | \& // if we got one, then embed it, otherwise default to loop_hi |
2786 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1591 | \& if (loop_lo) |
|
|
1592 | \& { |
|
|
1593 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1594 | \& ev_embed_start (loop_hi, &embed); |
|
|
1595 | \& } |
|
|
1596 | \& else |
|
|
1597 | \& loop_lo = loop_hi; |
|
|
1598 | .Ve |
|
|
1599 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2787 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1600 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2788 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1601 | .PD 0 |
2789 | .PD 0 |
1602 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2790 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1603 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2791 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1604 | .PD |
2792 | .PD |
1605 | Configures the watcher to embed the given loop, which must be |
2793 | Configures the watcher to embed the given loop, which must be |
1606 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
2794 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
1607 | invoked automatically, otherwise it is the responsibility of the callback |
2795 | invoked automatically, otherwise it is the responsibility of the callback |
1608 | to invoke it (it will continue to be called until the sweep has been done, |
2796 | to invoke it (it will continue to be called until the sweep has been done, |
1609 | if you do not want thta, you need to temporarily stop the embed watcher). |
2797 | if you do not want that, you need to temporarily stop the embed watcher). |
1610 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2798 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1611 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2799 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1612 | Make a single, non-blocking sweep over the embedded loop. This works |
2800 | Make a single, non-blocking sweep over the embedded loop. This works |
1613 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2801 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1614 | apropriate way for embedded loops. |
2802 | appropriate way for embedded loops. |
1615 | .IP "struct ev_loop *loop [read\-only]" 4 |
2803 | .IP "struct ev_loop *other [read\-only]" 4 |
1616 | .IX Item "struct ev_loop *loop [read-only]" |
2804 | .IX Item "struct ev_loop *other [read-only]" |
1617 | The embedded event loop. |
2805 | The embedded event loop. |
|
|
2806 | .PP |
|
|
2807 | \fIExamples\fR |
|
|
2808 | .IX Subsection "Examples" |
|
|
2809 | .PP |
|
|
2810 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2811 | event loop. If that is not possible, use the default loop. The default |
|
|
2812 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the embeddable loop is stored in |
|
|
2813 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the case no embeddable loop can be |
|
|
2814 | used). |
|
|
2815 | .PP |
|
|
2816 | .Vb 3 |
|
|
2817 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2818 | \& struct ev_loop *loop_lo = 0; |
|
|
2819 | \& ev_embed embed; |
|
|
2820 | \& |
|
|
2821 | \& // see if there is a chance of getting one that works |
|
|
2822 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2823 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2824 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2825 | \& : 0; |
|
|
2826 | \& |
|
|
2827 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2828 | \& if (loop_lo) |
|
|
2829 | \& { |
|
|
2830 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2831 | \& ev_embed_start (loop_hi, &embed); |
|
|
2832 | \& } |
|
|
2833 | \& else |
|
|
2834 | \& loop_lo = loop_hi; |
|
|
2835 | .Ve |
|
|
2836 | .PP |
|
|
2837 | Example: Check if kqueue is available but not recommended and create |
|
|
2838 | a kqueue backend for use with sockets (which usually work with any |
|
|
2839 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2840 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2841 | .PP |
|
|
2842 | .Vb 3 |
|
|
2843 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2844 | \& struct ev_loop *loop_socket = 0; |
|
|
2845 | \& ev_embed embed; |
|
|
2846 | \& |
|
|
2847 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2848 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2849 | \& { |
|
|
2850 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2851 | \& ev_embed_start (loop, &embed); |
|
|
2852 | \& } |
|
|
2853 | \& |
|
|
2854 | \& if (!loop_socket) |
|
|
2855 | \& loop_socket = loop; |
|
|
2856 | \& |
|
|
2857 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2858 | .Ve |
|
|
2859 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
|
|
2860 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
|
|
2861 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
|
|
2862 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
|
|
2863 | whoever is a good citizen cared to tell libev about it by calling |
|
|
2864 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
|
|
2865 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
|
|
2866 | and only in the child after the fork. If whoever good citizen calling |
|
|
2867 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
|
|
2868 | handlers will be invoked, too, of course. |
|
|
2869 | .PP |
|
|
2870 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
2871 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
2872 | .PP |
|
|
2873 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
|
|
2874 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
2875 | sequence should be handled by libev without any problems. |
|
|
2876 | .PP |
|
|
2877 | This changes when the application actually wants to do event handling |
|
|
2878 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
2879 | fork. |
|
|
2880 | .PP |
|
|
2881 | The default mode of operation (for libev, with application help to detect |
|
|
2882 | forks) is to duplicate all the state in the child, as would be expected |
|
|
2883 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
2884 | .PP |
|
|
2885 | When both processes want to continue using libev, then this is usually the |
|
|
2886 | wrong result. In that case, usually one process (typically the parent) is |
|
|
2887 | supposed to continue with all watchers in place as before, while the other |
|
|
2888 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
2889 | .PP |
|
|
2890 | The cleanest and most efficient way to achieve that with libev is to |
|
|
2891 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
2892 | use that for new watchers. This has the advantage of not touching more |
|
|
2893 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
2894 | disadvantage of having to use multiple event loops (which do not support |
|
|
2895 | signal watchers). |
|
|
2896 | .PP |
|
|
2897 | When this is not possible, or you want to use the default loop for |
|
|
2898 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
2899 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
|
|
2900 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
|
|
2901 | have to be careful not to execute code that modifies those watchers. Note |
|
|
2902 | also that in that case, you have to re-register any signal watchers. |
|
|
2903 | .PP |
|
|
2904 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2905 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2906 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
|
|
2907 | .IX Item "ev_fork_init (ev_signal *, callback)" |
|
|
2908 | Initialises and configures the fork watcher \- it has no parameters of any |
|
|
2909 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2910 | believe me. |
|
|
2911 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2912 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2913 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2914 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2915 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2916 | loops \- those are of course safe to use in different threads). |
|
|
2917 | .PP |
|
|
2918 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2919 | control, for example because it belongs to another thread. This is what |
|
|
2920 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2921 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2922 | safe. |
|
|
2923 | .PP |
|
|
2924 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2925 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2926 | (i.e. the number of callback invocations may be less than the number of |
|
|
2927 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2928 | .PP |
|
|
2929 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2930 | just the default loop. |
|
|
2931 | .PP |
|
|
2932 | \fIQueueing\fR |
|
|
2933 | .IX Subsection "Queueing" |
|
|
2934 | .PP |
|
|
2935 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2936 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2937 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2938 | need elaborate support such as pthreads. |
|
|
2939 | .PP |
|
|
2940 | That means that if you want to queue data, you have to provide your own |
|
|
2941 | queue. But at least I can tell you how to implement locking around your |
|
|
2942 | queue: |
|
|
2943 | .IP "queueing from a signal handler context" 4 |
|
|
2944 | .IX Item "queueing from a signal handler context" |
|
|
2945 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2946 | handler but you block the signal handler in the watcher callback. Here is |
|
|
2947 | an example that does that for some fictitious \s-1SIGUSR1\s0 handler: |
|
|
2948 | .Sp |
|
|
2949 | .Vb 1 |
|
|
2950 | \& static ev_async mysig; |
|
|
2951 | \& |
|
|
2952 | \& static void |
|
|
2953 | \& sigusr1_handler (void) |
|
|
2954 | \& { |
|
|
2955 | \& sometype data; |
|
|
2956 | \& |
|
|
2957 | \& // no locking etc. |
|
|
2958 | \& queue_put (data); |
|
|
2959 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2960 | \& } |
|
|
2961 | \& |
|
|
2962 | \& static void |
|
|
2963 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2964 | \& { |
|
|
2965 | \& sometype data; |
|
|
2966 | \& sigset_t block, prev; |
|
|
2967 | \& |
|
|
2968 | \& sigemptyset (&block); |
|
|
2969 | \& sigaddset (&block, SIGUSR1); |
|
|
2970 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2971 | \& |
|
|
2972 | \& while (queue_get (&data)) |
|
|
2973 | \& process (data); |
|
|
2974 | \& |
|
|
2975 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2976 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2977 | \& } |
|
|
2978 | .Ve |
|
|
2979 | .Sp |
|
|
2980 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2981 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2982 | either...). |
|
|
2983 | .IP "queueing from a thread context" 4 |
|
|
2984 | .IX Item "queueing from a thread context" |
|
|
2985 | The strategy for threads is different, as you cannot (easily) block |
|
|
2986 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2987 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2988 | .Sp |
|
|
2989 | .Vb 2 |
|
|
2990 | \& static ev_async mysig; |
|
|
2991 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2992 | \& |
|
|
2993 | \& static void |
|
|
2994 | \& otherthread (void) |
|
|
2995 | \& { |
|
|
2996 | \& // only need to lock the actual queueing operation |
|
|
2997 | \& pthread_mutex_lock (&mymutex); |
|
|
2998 | \& queue_put (data); |
|
|
2999 | \& pthread_mutex_unlock (&mymutex); |
|
|
3000 | \& |
|
|
3001 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
3002 | \& } |
|
|
3003 | \& |
|
|
3004 | \& static void |
|
|
3005 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
3006 | \& { |
|
|
3007 | \& pthread_mutex_lock (&mymutex); |
|
|
3008 | \& |
|
|
3009 | \& while (queue_get (&data)) |
|
|
3010 | \& process (data); |
|
|
3011 | \& |
|
|
3012 | \& pthread_mutex_unlock (&mymutex); |
|
|
3013 | \& } |
|
|
3014 | .Ve |
|
|
3015 | .PP |
|
|
3016 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3017 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3018 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
3019 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
3020 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
3021 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
3022 | trust me. |
|
|
3023 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
3024 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
3025 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
3026 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
3027 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
|
|
3028 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
3029 | section below on what exactly this means). |
|
|
3030 | .Sp |
|
|
3031 | Note that, as with other watchers in libev, multiple events might get |
|
|
3032 | compressed into a single callback invocation (another way to look at this |
|
|
3033 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3034 | reset when the event loop detects that). |
|
|
3035 | .Sp |
|
|
3036 | This call incurs the overhead of a system call only once per event loop |
|
|
3037 | iteration, so while the overhead might be noticeable, it doesn't apply to |
|
|
3038 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
|
|
3039 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
3040 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
3041 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
3042 | watcher but the event has not yet been processed (or even noted) by the |
|
|
3043 | event loop. |
|
|
3044 | .Sp |
|
|
3045 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
3046 | the loop iterates next and checks for the watcher to have become active, |
|
|
3047 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
3048 | quickly check whether invoking the loop might be a good idea. |
|
|
3049 | .Sp |
|
|
3050 | Not that this does \fInot\fR check whether the watcher itself is pending, |
|
|
3051 | only whether it has been requested to make this watcher pending: there |
|
|
3052 | is a time window between the event loop checking and resetting the async |
|
|
3053 | notification, and the callback being invoked. |
1618 | .SH "OTHER FUNCTIONS" |
3054 | .SH "OTHER FUNCTIONS" |
1619 | .IX Header "OTHER FUNCTIONS" |
3055 | .IX Header "OTHER FUNCTIONS" |
1620 | There are some other functions of possible interest. Described. Here. Now. |
3056 | There are some other functions of possible interest. Described. Here. Now. |
1621 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3057 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1622 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3058 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
1623 | This function combines a simple timer and an I/O watcher, calls your |
3059 | This function combines a simple timer and an I/O watcher, calls your |
1624 | callback on whichever event happens first and automatically stop both |
3060 | callback on whichever event happens first and automatically stops both |
1625 | watchers. This is useful if you want to wait for a single event on an fd |
3061 | watchers. This is useful if you want to wait for a single event on an fd |
1626 | or timeout without having to allocate/configure/start/stop/free one or |
3062 | or timeout without having to allocate/configure/start/stop/free one or |
1627 | more watchers yourself. |
3063 | more watchers yourself. |
1628 | .Sp |
3064 | .Sp |
1629 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and events |
3065 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and the |
1630 | is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for the given \f(CW\*(C`fd\*(C'\fR and |
3066 | \&\f(CW\*(C`events\*(C'\fR argument is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for |
1631 | \&\f(CW\*(C`events\*(C'\fR set will be craeted and started. |
3067 | the given \f(CW\*(C`fd\*(C'\fR and \f(CW\*(C`events\*(C'\fR set will be created and started. |
1632 | .Sp |
3068 | .Sp |
1633 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3069 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
1634 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3070 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
1635 | repeat = 0) will be started. While \f(CW0\fR is a valid timeout, it is of |
3071 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
1636 | dubious value. |
|
|
1637 | .Sp |
3072 | .Sp |
1638 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3073 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
1639 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3074 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
1640 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3075 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
1641 | value passed to \f(CW\*(C`ev_once\*(C'\fR: |
3076 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
|
|
3077 | a timeout and an io event at the same time \- you probably should give io |
|
|
3078 | events precedence. |
|
|
3079 | .Sp |
|
|
3080 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
1642 | .Sp |
3081 | .Sp |
1643 | .Vb 7 |
3082 | .Vb 7 |
1644 | \& static void stdin_ready (int revents, void *arg) |
3083 | \& static void stdin_ready (int revents, void *arg) |
1645 | \& { |
3084 | \& { |
1646 | \& if (revents & EV_TIMEOUT) |
|
|
1647 | \& /* doh, nothing entered */; |
|
|
1648 | \& else if (revents & EV_READ) |
3085 | \& if (revents & EV_READ) |
1649 | \& /* stdin might have data for us, joy! */; |
3086 | \& /* stdin might have data for us, joy! */; |
|
|
3087 | \& else if (revents & EV_TIMEOUT) |
|
|
3088 | \& /* doh, nothing entered */; |
1650 | \& } |
3089 | \& } |
1651 | .Ve |
3090 | \& |
1652 | .Sp |
|
|
1653 | .Vb 1 |
|
|
1654 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3091 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1655 | .Ve |
3092 | .Ve |
1656 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
3093 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
1657 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
3094 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
1658 | Feeds the given event set into the event loop, as if the specified event |
3095 | Feeds the given event set into the event loop, as if the specified event |
1659 | had happened for the specified watcher (which must be a pointer to an |
3096 | had happened for the specified watcher (which must be a pointer to an |
1660 | initialised but not necessarily started event watcher). |
3097 | initialised but not necessarily started event watcher). |
1661 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
3098 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
1662 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
3099 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
1663 | Feed an event on the given fd, as if a file descriptor backend detected |
3100 | Feed an event on the given fd, as if a file descriptor backend detected |
1664 | the given events it. |
3101 | the given events it. |
1665 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
3102 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
1666 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
3103 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
1667 | Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default |
3104 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
1668 | loop!). |
3105 | loop!). |
1669 | .SH "LIBEVENT EMULATION" |
3106 | .SH "LIBEVENT EMULATION" |
1670 | .IX Header "LIBEVENT EMULATION" |
3107 | .IX Header "LIBEVENT EMULATION" |
1671 | Libev offers a compatibility emulation layer for libevent. It cannot |
3108 | Libev offers a compatibility emulation layer for libevent. It cannot |
1672 | emulate the internals of libevent, so here are some usage hints: |
3109 | emulate the internals of libevent, so here are some usage hints: |
|
|
3110 | .IP "\(bu" 4 |
1673 | .IP "* Use it by including <event.h>, as usual." 4 |
3111 | Use it by including <event.h>, as usual. |
1674 | .IX Item "Use it by including <event.h>, as usual." |
3112 | .IP "\(bu" 4 |
1675 | .PD 0 |
3113 | The following members are fully supported: ev_base, ev_callback, |
1676 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
3114 | ev_arg, ev_fd, ev_res, ev_events. |
1677 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
3115 | .IP "\(bu" 4 |
1678 | .IP "* Avoid using ev_flags and the EVLIST_*\-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private \s-1API\s0)." 4 |
3116 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1679 | .IX Item "Avoid using ev_flags and the EVLIST_*-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private API)." |
3117 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1680 | .IP "* Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." 4 |
3118 | it a private \s-1API\s0). |
1681 | .IX Item "Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." |
3119 | .IP "\(bu" 4 |
|
|
3120 | Priorities are not currently supported. Initialising priorities |
|
|
3121 | will fail and all watchers will have the same priority, even though there |
|
|
3122 | is an ev_pri field. |
|
|
3123 | .IP "\(bu" 4 |
|
|
3124 | In libevent, the last base created gets the signals, in libev, the |
|
|
3125 | first base created (== the default loop) gets the signals. |
|
|
3126 | .IP "\(bu" 4 |
1682 | .IP "* Other members are not supported." 4 |
3127 | Other members are not supported. |
1683 | .IX Item "Other members are not supported." |
3128 | .IP "\(bu" 4 |
1684 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
3129 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1685 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
3130 | to use the libev header file and library. |
1686 | .PD |
|
|
1687 | .SH "\*(C+ SUPPORT" |
3131 | .SH "\*(C+ SUPPORT" |
1688 | .IX Header " SUPPORT" |
3132 | .IX Header " SUPPORT" |
1689 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3133 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1690 | you to use some convinience methods to start/stop watchers and also change |
3134 | you to use some convenience methods to start/stop watchers and also change |
1691 | the callback model to a model using method callbacks on objects. |
3135 | the callback model to a model using method callbacks on objects. |
1692 | .PP |
3136 | .PP |
1693 | To use it, |
3137 | To use it, |
1694 | .PP |
3138 | .PP |
1695 | .Vb 1 |
3139 | .Vb 1 |
1696 | \& #include <ev++.h> |
3140 | \& #include <ev++.h> |
1697 | .Ve |
3141 | .Ve |
1698 | .PP |
3142 | .PP |
1699 | (it is not installed by default). This automatically includes \fIev.h\fR |
3143 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1700 | and puts all of its definitions (many of them macros) into the global |
3144 | of them macros) into the global namespace. All \*(C+ specific things are |
1701 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
3145 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
3146 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1702 | .PP |
3147 | .PP |
1703 | It should support all the same embedding options as \fIev.h\fR, most notably |
3148 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1704 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
3149 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
3150 | that the watcher is associated with (or no additional members at all if |
|
|
3151 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
3152 | .PP |
|
|
3153 | Currently, functions, and static and non-static member functions can be |
|
|
3154 | used as callbacks. Other types should be easy to add as long as they only |
|
|
3155 | need one additional pointer for context. If you need support for other |
|
|
3156 | types of functors please contact the author (preferably after implementing |
|
|
3157 | it). |
1705 | .PP |
3158 | .PP |
1706 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3159 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1707 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3160 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
1708 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3161 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1709 | .IX Item "ev::READ, ev::WRITE etc." |
3162 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
1721 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3174 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1722 | defines by many implementations. |
3175 | defines by many implementations. |
1723 | .Sp |
3176 | .Sp |
1724 | All of those classes have these methods: |
3177 | All of those classes have these methods: |
1725 | .RS 4 |
3178 | .RS 4 |
1726 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
3179 | .IP "ev::TYPE::TYPE ()" 4 |
1727 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
3180 | .IX Item "ev::TYPE::TYPE ()" |
1728 | .PD 0 |
3181 | .PD 0 |
1729 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
3182 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1730 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
3183 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1731 | .IP "ev::TYPE::~TYPE" 4 |
3184 | .IP "ev::TYPE::~TYPE" 4 |
1732 | .IX Item "ev::TYPE::~TYPE" |
3185 | .IX Item "ev::TYPE::~TYPE" |
1733 | .PD |
3186 | .PD |
1734 | The constructor takes a pointer to an object and a method pointer to |
3187 | The constructor (optionally) takes an event loop to associate the watcher |
1735 | the event handler callback to call in this class. The constructor calls |
3188 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1736 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
3189 | .Sp |
1737 | before starting it. If you do not specify a loop then the constructor |
3190 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1738 | automatically associates the default loop with this watcher. |
3191 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
3192 | .Sp |
|
|
3193 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
3194 | method to set a callback before you can start the watcher. |
|
|
3195 | .Sp |
|
|
3196 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
3197 | not allow explicit template arguments for constructors). |
1739 | .Sp |
3198 | .Sp |
1740 | The destructor automatically stops the watcher if it is active. |
3199 | The destructor automatically stops the watcher if it is active. |
|
|
3200 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
3201 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
3202 | This method sets the callback method to call. The method has to have a |
|
|
3203 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
3204 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
3205 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
3206 | .Sp |
|
|
3207 | This method synthesizes efficient thunking code to call your method from |
|
|
3208 | the C callback that libev requires. If your compiler can inline your |
|
|
3209 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
3210 | your compiler is good :), then the method will be fully inlined into the |
|
|
3211 | thunking function, making it as fast as a direct C callback. |
|
|
3212 | .Sp |
|
|
3213 | Example: simple class declaration and watcher initialisation |
|
|
3214 | .Sp |
|
|
3215 | .Vb 4 |
|
|
3216 | \& struct myclass |
|
|
3217 | \& { |
|
|
3218 | \& void io_cb (ev::io &w, int revents) { } |
|
|
3219 | \& } |
|
|
3220 | \& |
|
|
3221 | \& myclass obj; |
|
|
3222 | \& ev::io iow; |
|
|
3223 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
3224 | .Ve |
|
|
3225 | .IP "w\->set (object *)" 4 |
|
|
3226 | .IX Item "w->set (object *)" |
|
|
3227 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3228 | .Sp |
|
|
3229 | This is a variation of a method callback \- leaving out the method to call |
|
|
3230 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
|
|
3231 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
|
|
3232 | the time. Incidentally, you can then also leave out the template argument |
|
|
3233 | list. |
|
|
3234 | .Sp |
|
|
3235 | The \f(CW\*(C`operator ()\*(C'\fR method prototype must be \f(CW\*(C`void operator ()(watcher &w, |
|
|
3236 | int revents)\*(C'\fR. |
|
|
3237 | .Sp |
|
|
3238 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3239 | .Sp |
|
|
3240 | Example: use a functor object as callback. |
|
|
3241 | .Sp |
|
|
3242 | .Vb 7 |
|
|
3243 | \& struct myfunctor |
|
|
3244 | \& { |
|
|
3245 | \& void operator() (ev::io &w, int revents) |
|
|
3246 | \& { |
|
|
3247 | \& ... |
|
|
3248 | \& } |
|
|
3249 | \& } |
|
|
3250 | \& |
|
|
3251 | \& myfunctor f; |
|
|
3252 | \& |
|
|
3253 | \& ev::io w; |
|
|
3254 | \& w.set (&f); |
|
|
3255 | .Ve |
|
|
3256 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
3257 | .IX Item "w->set<function> (void *data = 0)" |
|
|
3258 | Also sets a callback, but uses a static method or plain function as |
|
|
3259 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
3260 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
3261 | .Sp |
|
|
3262 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
3263 | .Sp |
|
|
3264 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3265 | .Sp |
|
|
3266 | Example: Use a plain function as callback. |
|
|
3267 | .Sp |
|
|
3268 | .Vb 2 |
|
|
3269 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
3270 | \& iow.set <io_cb> (); |
|
|
3271 | .Ve |
1741 | .IP "w\->set (struct ev_loop *)" 4 |
3272 | .IP "w\->set (struct ev_loop *)" 4 |
1742 | .IX Item "w->set (struct ev_loop *)" |
3273 | .IX Item "w->set (struct ev_loop *)" |
1743 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3274 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1744 | do this when the watcher is inactive (and not pending either). |
3275 | do this when the watcher is inactive (and not pending either). |
1745 | .IP "w\->set ([args])" 4 |
3276 | .IP "w\->set ([arguments])" 4 |
1746 | .IX Item "w->set ([args])" |
3277 | .IX Item "w->set ([arguments])" |
1747 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
3278 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
1748 | called at least once. Unlike the C counterpart, an active watcher gets |
3279 | called at least once. Unlike the C counterpart, an active watcher gets |
1749 | automatically stopped and restarted. |
3280 | automatically stopped and restarted when reconfiguring it with this |
|
|
3281 | method. |
1750 | .IP "w\->start ()" 4 |
3282 | .IP "w\->start ()" 4 |
1751 | .IX Item "w->start ()" |
3283 | .IX Item "w->start ()" |
1752 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
3284 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1753 | constructor already takes the loop. |
3285 | constructor already stores the event loop. |
1754 | .IP "w\->stop ()" 4 |
3286 | .IP "w\->stop ()" 4 |
1755 | .IX Item "w->stop ()" |
3287 | .IX Item "w->stop ()" |
1756 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3288 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1757 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
3289 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
1758 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
3290 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1759 | .IX Item "w->again () ev::timer, ev::periodic only" |
3291 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1760 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3292 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1761 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3293 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1762 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
3294 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1763 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
3295 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1764 | .IX Item "w->sweep () ev::embed only" |
3296 | .IX Item "w->sweep () (ev::embed only)" |
1765 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
3297 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
|
|
3298 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
|
|
3299 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
|
|
3300 | .IX Item "w->update () (ev::stat only)" |
|
|
3301 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1766 | .RE |
3302 | .RE |
1767 | .RS 4 |
3303 | .RS 4 |
1768 | .RE |
3304 | .RE |
1769 | .PP |
3305 | .PP |
1770 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
3306 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
1771 | the constructor. |
3307 | the constructor. |
1772 | .PP |
3308 | .PP |
1773 | .Vb 4 |
3309 | .Vb 4 |
1774 | \& class myclass |
3310 | \& class myclass |
1775 | \& { |
3311 | \& { |
1776 | \& ev_io io; void io_cb (ev::io &w, int revents); |
3312 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
1777 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
3313 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
|
|
3314 | \& |
|
|
3315 | \& myclass (int fd) |
|
|
3316 | \& { |
|
|
3317 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
3318 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
3319 | \& |
|
|
3320 | \& io.start (fd, ev::READ); |
|
|
3321 | \& } |
|
|
3322 | \& }; |
1778 | .Ve |
3323 | .Ve |
|
|
3324 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
3325 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
3326 | Libev does not offer other language bindings itself, but bindings for a |
|
|
3327 | number of languages exist in the form of third-party packages. If you know |
|
|
3328 | any interesting language binding in addition to the ones listed here, drop |
|
|
3329 | me a note. |
|
|
3330 | .IP "Perl" 4 |
|
|
3331 | .IX Item "Perl" |
|
|
3332 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
3333 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
3334 | there are additional modules that implement libev-compatible interfaces |
|
|
3335 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
|
|
3336 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
|
|
3337 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
3338 | .Sp |
|
|
3339 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
|
|
3340 | <http://software.schmorp.de/pkg/EV>. |
|
|
3341 | .IP "Python" 4 |
|
|
3342 | .IX Item "Python" |
|
|
3343 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
|
|
3344 | seems to be quite complete and well-documented. |
|
|
3345 | .IP "Ruby" 4 |
|
|
3346 | .IX Item "Ruby" |
|
|
3347 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
3348 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
|
|
3349 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
3350 | <http://rev.rubyforge.org/>. |
|
|
3351 | .Sp |
|
|
3352 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
|
|
3353 | makes rev work even on mingw. |
|
|
3354 | .IP "Haskell" 4 |
|
|
3355 | .IX Item "Haskell" |
|
|
3356 | A haskell binding to libev is available at |
|
|
3357 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
|
|
3358 | .IP "D" 4 |
|
|
3359 | .IX Item "D" |
|
|
3360 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
3361 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
|
|
3362 | .IP "Ocaml" 4 |
|
|
3363 | .IX Item "Ocaml" |
|
|
3364 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3365 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
|
|
3366 | .SH "MACRO MAGIC" |
|
|
3367 | .IX Header "MACRO MAGIC" |
|
|
3368 | Libev can be compiled with a variety of options, the most fundamental |
|
|
3369 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
|
|
3370 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1779 | .PP |
3371 | .PP |
|
|
3372 | To make it easier to write programs that cope with either variant, the |
|
|
3373 | following macros are defined: |
|
|
3374 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
|
|
3375 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
|
|
3376 | .IX Item "EV_A, EV_A_" |
|
|
3377 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
|
|
3378 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
|
|
3379 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
|
|
3380 | .Sp |
|
|
3381 | .Vb 3 |
|
|
3382 | \& ev_unref (EV_A); |
|
|
3383 | \& ev_timer_add (EV_A_ watcher); |
|
|
3384 | \& ev_loop (EV_A_ 0); |
|
|
3385 | .Ve |
|
|
3386 | .Sp |
|
|
3387 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
|
|
3388 | which is often provided by the following macro. |
|
|
3389 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
|
|
3390 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
|
|
3391 | .IX Item "EV_P, EV_P_" |
|
|
3392 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
|
|
3393 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
|
|
3394 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
|
|
3395 | .Sp |
1780 | .Vb 2 |
3396 | .Vb 2 |
1781 | \& myclass (); |
3397 | \& // this is how ev_unref is being declared |
1782 | \& } |
3398 | \& static void ev_unref (EV_P); |
|
|
3399 | \& |
|
|
3400 | \& // this is how you can declare your typical callback |
|
|
3401 | \& static void cb (EV_P_ ev_timer *w, int revents) |
1783 | .Ve |
3402 | .Ve |
|
|
3403 | .Sp |
|
|
3404 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
|
|
3405 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
|
|
3406 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
|
|
3407 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
|
|
3408 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
|
|
3409 | Similar to the other two macros, this gives you the value of the default |
|
|
3410 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
3411 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
3412 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
3413 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
3414 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
3415 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
3416 | is undefined when the default loop has not been initialised by a previous |
|
|
3417 | execution of \f(CW\*(C`EV_DEFAULT\*(C'\fR, \f(CW\*(C`EV_DEFAULT_\*(C'\fR or \f(CW\*(C`ev_default_init (...)\*(C'\fR. |
|
|
3418 | .Sp |
|
|
3419 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
3420 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
1784 | .PP |
3421 | .PP |
|
|
3422 | Example: Declare and initialise a check watcher, utilising the above |
|
|
3423 | macros so it will work regardless of whether multiple loops are supported |
|
|
3424 | or not. |
|
|
3425 | .PP |
1785 | .Vb 6 |
3426 | .Vb 5 |
1786 | \& myclass::myclass (int fd) |
3427 | \& static void |
1787 | \& : io (this, &myclass::io_cb), |
3428 | \& check_cb (EV_P_ ev_timer *w, int revents) |
1788 | \& idle (this, &myclass::idle_cb) |
|
|
1789 | \& { |
3429 | \& { |
1790 | \& io.start (fd, ev::READ); |
3430 | \& ev_check_stop (EV_A_ w); |
1791 | \& } |
3431 | \& } |
|
|
3432 | \& |
|
|
3433 | \& ev_check check; |
|
|
3434 | \& ev_check_init (&check, check_cb); |
|
|
3435 | \& ev_check_start (EV_DEFAULT_ &check); |
|
|
3436 | \& ev_loop (EV_DEFAULT_ 0); |
1792 | .Ve |
3437 | .Ve |
1793 | .SH "EMBEDDING" |
3438 | .SH "EMBEDDING" |
1794 | .IX Header "EMBEDDING" |
3439 | .IX Header "EMBEDDING" |
1795 | Libev can (and often is) directly embedded into host |
3440 | Libev can (and often is) directly embedded into host |
1796 | applications. Examples of applications that embed it include the Deliantra |
3441 | applications. Examples of applications that embed it include the Deliantra |
1797 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
3442 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
1798 | and rxvt\-unicode. |
3443 | and rxvt-unicode. |
1799 | .PP |
3444 | .PP |
1800 | The goal is to enable you to just copy the neecssary files into your |
3445 | The goal is to enable you to just copy the necessary files into your |
1801 | source directory without having to change even a single line in them, so |
3446 | source directory without having to change even a single line in them, so |
1802 | you can easily upgrade by simply copying (or having a checked-out copy of |
3447 | you can easily upgrade by simply copying (or having a checked-out copy of |
1803 | libev somewhere in your source tree). |
3448 | libev somewhere in your source tree). |
1804 | .Sh "\s-1FILESETS\s0" |
3449 | .Sh "\s-1FILESETS\s0" |
1805 | .IX Subsection "FILESETS" |
3450 | .IX Subsection "FILESETS" |
1806 | Depending on what features you need you need to include one or more sets of files |
3451 | Depending on what features you need you need to include one or more sets of files |
1807 | in your app. |
3452 | in your application. |
1808 | .PP |
3453 | .PP |
1809 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3454 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
1810 | .IX Subsection "CORE EVENT LOOP" |
3455 | .IX Subsection "CORE EVENT LOOP" |
1811 | .PP |
3456 | .PP |
1812 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3457 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
1813 | configuration (no autoconf): |
3458 | configuration (no autoconf): |
1814 | .PP |
3459 | .PP |
1815 | .Vb 2 |
3460 | .Vb 2 |
1816 | \& #define EV_STANDALONE 1 |
3461 | \& #define EV_STANDALONE 1 |
1817 | \& #include "ev.c" |
3462 | \& #include "ev.c" |
1818 | .Ve |
3463 | .Ve |
1819 | .PP |
3464 | .PP |
1820 | This will automatically include \fIev.h\fR, too, and should be done in a |
3465 | This will automatically include \fIev.h\fR, too, and should be done in a |
1821 | single C source file only to provide the function implementations. To use |
3466 | single C source file only to provide the function implementations. To use |
1822 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
3467 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
1823 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
3468 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
1824 | where you can put other configuration options): |
3469 | where you can put other configuration options): |
1825 | .PP |
3470 | .PP |
1826 | .Vb 2 |
3471 | .Vb 2 |
1827 | \& #define EV_STANDALONE 1 |
3472 | \& #define EV_STANDALONE 1 |
1828 | \& #include "ev.h" |
3473 | \& #include "ev.h" |
1829 | .Ve |
3474 | .Ve |
1830 | .PP |
3475 | .PP |
1831 | Both header files and implementation files can be compiled with a \*(C+ |
3476 | Both header files and implementation files can be compiled with a \*(C+ |
1832 | compiler (at least, thats a stated goal, and breakage will be treated |
3477 | compiler (at least, that's a stated goal, and breakage will be treated |
1833 | as a bug). |
3478 | as a bug). |
1834 | .PP |
3479 | .PP |
1835 | You need the following files in your source tree, or in a directory |
3480 | You need the following files in your source tree, or in a directory |
1836 | in your include path (e.g. in libev/ when using \-Ilibev): |
3481 | in your include path (e.g. in libev/ when using \-Ilibev): |
1837 | .PP |
3482 | .PP |
1838 | .Vb 4 |
3483 | .Vb 4 |
1839 | \& ev.h |
3484 | \& ev.h |
1840 | \& ev.c |
3485 | \& ev.c |
1841 | \& ev_vars.h |
3486 | \& ev_vars.h |
1842 | \& ev_wrap.h |
3487 | \& ev_wrap.h |
1843 | .Ve |
3488 | \& |
1844 | .PP |
|
|
1845 | .Vb 1 |
|
|
1846 | \& ev_win32.c required on win32 platforms only |
3489 | \& ev_win32.c required on win32 platforms only |
1847 | .Ve |
3490 | \& |
1848 | .PP |
|
|
1849 | .Vb 5 |
|
|
1850 | \& ev_select.c only when select backend is enabled (which is by default) |
3491 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
1851 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
3492 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
1852 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
3493 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1853 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
3494 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1854 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
3495 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
1855 | .Ve |
3496 | .Ve |
1856 | .PP |
3497 | .PP |
1857 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3498 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
1858 | to compile this single file. |
3499 | to compile this single file. |
1859 | .PP |
3500 | .PP |
… | |
… | |
1861 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3502 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
1862 | .PP |
3503 | .PP |
1863 | To include the libevent compatibility \s-1API\s0, also include: |
3504 | To include the libevent compatibility \s-1API\s0, also include: |
1864 | .PP |
3505 | .PP |
1865 | .Vb 1 |
3506 | .Vb 1 |
1866 | \& #include "event.c" |
3507 | \& #include "event.c" |
1867 | .Ve |
3508 | .Ve |
1868 | .PP |
3509 | .PP |
1869 | in the file including \fIev.c\fR, and: |
3510 | in the file including \fIev.c\fR, and: |
1870 | .PP |
3511 | .PP |
1871 | .Vb 1 |
3512 | .Vb 1 |
1872 | \& #include "event.h" |
3513 | \& #include "event.h" |
1873 | .Ve |
3514 | .Ve |
1874 | .PP |
3515 | .PP |
1875 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
3516 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
1876 | .PP |
3517 | .PP |
1877 | You need the following additional files for this: |
3518 | You need the following additional files for this: |
1878 | .PP |
3519 | .PP |
1879 | .Vb 2 |
3520 | .Vb 2 |
1880 | \& event.h |
3521 | \& event.h |
1881 | \& event.c |
3522 | \& event.c |
1882 | .Ve |
3523 | .Ve |
1883 | .PP |
3524 | .PP |
1884 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
3525 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
1885 | .IX Subsection "AUTOCONF SUPPORT" |
3526 | .IX Subsection "AUTOCONF SUPPORT" |
1886 | .PP |
3527 | .PP |
1887 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
3528 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
1888 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3529 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
1889 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
3530 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
1890 | include \fIconfig.h\fR and configure itself accordingly. |
3531 | include \fIconfig.h\fR and configure itself accordingly. |
1891 | .PP |
3532 | .PP |
1892 | For this of course you need the m4 file: |
3533 | For this of course you need the m4 file: |
1893 | .PP |
3534 | .PP |
1894 | .Vb 1 |
3535 | .Vb 1 |
1895 | \& libev.m4 |
3536 | \& libev.m4 |
1896 | .Ve |
3537 | .Ve |
1897 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3538 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
1898 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3539 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
1899 | Libev can be configured via a variety of preprocessor symbols you have to define |
3540 | Libev can be configured via a variety of preprocessor symbols you have to |
1900 | before including any of its files. The default is not to build for multiplicity |
3541 | define before including any of its files. The default in the absence of |
1901 | and only include the select backend. |
3542 | autoconf is documented for every option. |
1902 | .IP "\s-1EV_STANDALONE\s0" 4 |
3543 | .IP "\s-1EV_STANDALONE\s0" 4 |
1903 | .IX Item "EV_STANDALONE" |
3544 | .IX Item "EV_STANDALONE" |
1904 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3545 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
1905 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3546 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
1906 | implementations for some libevent functions (such as logging, which is not |
3547 | implementations for some libevent functions (such as logging, which is not |
1907 | supported). It will also not define any of the structs usually found in |
3548 | supported). It will also not define any of the structs usually found in |
1908 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3549 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
3550 | .Sp |
|
|
3551 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3552 | configuration, but has to be more conservative. |
1909 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3553 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
1910 | .IX Item "EV_USE_MONOTONIC" |
3554 | .IX Item "EV_USE_MONOTONIC" |
1911 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3555 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
1912 | monotonic clock option at both compiletime and runtime. Otherwise no use |
3556 | monotonic clock option at both compile time and runtime. Otherwise no |
1913 | of the monotonic clock option will be attempted. If you enable this, you |
3557 | use of the monotonic clock option will be attempted. If you enable this, |
1914 | usually have to link against librt or something similar. Enabling it when |
3558 | you usually have to link against librt or something similar. Enabling it |
1915 | the functionality isn't available is safe, though, althoguh you have |
3559 | when the functionality isn't available is safe, though, although you have |
1916 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3560 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
1917 | function is hiding in (often \fI\-lrt\fR). |
3561 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
1918 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3562 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
1919 | .IX Item "EV_USE_REALTIME" |
3563 | .IX Item "EV_USE_REALTIME" |
1920 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3564 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
1921 | realtime clock option at compiletime (and assume its availability at |
3565 | real-time clock option at compile time (and assume its availability |
1922 | runtime if successful). Otherwise no use of the realtime clock option will |
3566 | at runtime if successful). Otherwise no use of the real-time clock |
1923 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
3567 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
1924 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
3568 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
1925 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
3569 | correctness. See the note about libraries in the description of |
|
|
3570 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
3571 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
|
|
3572 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
|
|
3573 | .IX Item "EV_USE_CLOCK_SYSCALL" |
|
|
3574 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
|
|
3575 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
|
|
3576 | exists because on GNU/Linux, \f(CW\*(C`clock_gettime\*(C'\fR is in \f(CW\*(C`librt\*(C'\fR, but \f(CW\*(C`librt\*(C'\fR |
|
|
3577 | unconditionally pulls in \f(CW\*(C`libpthread\*(C'\fR, slowing down single-threaded |
|
|
3578 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3579 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3580 | the pthread dependency. Defaults to \f(CW1\fR on GNU/Linux with glibc 2.x or |
|
|
3581 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
|
|
3582 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
3583 | .IX Item "EV_USE_NANOSLEEP" |
|
|
3584 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
3585 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
3586 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
3587 | .IX Item "EV_USE_EVENTFD" |
|
|
3588 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
3589 | available and will probe for kernel support at runtime. This will improve |
|
|
3590 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
3591 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
3592 | 2.7 or newer, otherwise disabled. |
1926 | .IP "\s-1EV_USE_SELECT\s0" 4 |
3593 | .IP "\s-1EV_USE_SELECT\s0" 4 |
1927 | .IX Item "EV_USE_SELECT" |
3594 | .IX Item "EV_USE_SELECT" |
1928 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
3595 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
1929 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
3596 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no |
1930 | other method takes over, select will be it. Otherwise the select backend |
3597 | other method takes over, select will be it. Otherwise the select backend |
1931 | will not be compiled in. |
3598 | will not be compiled in. |
1932 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3599 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
1933 | .IX Item "EV_SELECT_USE_FD_SET" |
3600 | .IX Item "EV_SELECT_USE_FD_SET" |
1934 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3601 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
1935 | structure. This is useful if libev doesn't compile due to a missing |
3602 | structure. This is useful if libev doesn't compile due to a missing |
1936 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on |
3603 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout |
1937 | exotic systems. This usually limits the range of file descriptors to some |
3604 | on exotic systems. This usually limits the range of file descriptors to |
1938 | low limit such as 1024 or might have other limitations (winsocket only |
3605 | some low limit such as 1024 or might have other limitations (winsocket |
1939 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
3606 | only allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, |
1940 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
3607 | configures the maximum size of the \f(CW\*(C`fd_set\*(C'\fR. |
1941 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3608 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
1942 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3609 | .IX Item "EV_SELECT_IS_WINSOCKET" |
1943 | When defined to \f(CW1\fR, the select backend will assume that |
3610 | When defined to \f(CW1\fR, the select backend will assume that |
1944 | select/socket/connect etc. don't understand file descriptors but |
3611 | select/socket/connect etc. don't understand file descriptors but |
1945 | wants osf handles on win32 (this is the case when the select to |
3612 | wants osf handles on win32 (this is the case when the select to |
1946 | be used is the winsock select). This means that it will call |
3613 | be used is the winsock select). This means that it will call |
1947 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3614 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
1948 | it is assumed that all these functions actually work on fds, even |
3615 | it is assumed that all these functions actually work on fds, even |
1949 | on win32. Should not be defined on non\-win32 platforms. |
3616 | on win32. Should not be defined on non\-win32 platforms. |
|
|
3617 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
3618 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
3619 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
3620 | file descriptors to socket handles. When not defining this symbol (the |
|
|
3621 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
3622 | correct. In some cases, programs use their own file descriptor management, |
|
|
3623 | in which case they can provide this function to map fds to socket handles. |
1950 | .IP "\s-1EV_USE_POLL\s0" 4 |
3624 | .IP "\s-1EV_USE_POLL\s0" 4 |
1951 | .IX Item "EV_USE_POLL" |
3625 | .IX Item "EV_USE_POLL" |
1952 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3626 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
1953 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3627 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
1954 | takes precedence over select. |
3628 | takes precedence over select. |
1955 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
3629 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
1956 | .IX Item "EV_USE_EPOLL" |
3630 | .IX Item "EV_USE_EPOLL" |
1957 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
3631 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
1958 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
3632 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
1959 | otherwise another method will be used as fallback. This is the |
3633 | otherwise another method will be used as fallback. This is the preferred |
1960 | preferred backend for GNU/Linux systems. |
3634 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
3635 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
1961 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
3636 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
1962 | .IX Item "EV_USE_KQUEUE" |
3637 | .IX Item "EV_USE_KQUEUE" |
1963 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
3638 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
1964 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
3639 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
1965 | otherwise another method will be used as fallback. This is the preferred |
3640 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
1975 | 10 port style backend. Its availability will be detected at runtime, |
3650 | 10 port style backend. Its availability will be detected at runtime, |
1976 | otherwise another method will be used as fallback. This is the preferred |
3651 | otherwise another method will be used as fallback. This is the preferred |
1977 | backend for Solaris 10 systems. |
3652 | backend for Solaris 10 systems. |
1978 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
3653 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
1979 | .IX Item "EV_USE_DEVPOLL" |
3654 | .IX Item "EV_USE_DEVPOLL" |
1980 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
3655 | Reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
3656 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
3657 | .IX Item "EV_USE_INOTIFY" |
|
|
3658 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
3659 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
3660 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
3661 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
3662 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
3663 | .IX Item "EV_ATOMIC_T" |
|
|
3664 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
3665 | access is atomic with respect to other threads or signal contexts. No such |
|
|
3666 | type is easily found in the C language, so you can provide your own type |
|
|
3667 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
3668 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
3669 | .Sp |
|
|
3670 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
3671 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
1981 | .IP "\s-1EV_H\s0" 4 |
3672 | .IP "\s-1EV_H\s0" 4 |
1982 | .IX Item "EV_H" |
3673 | .IX Item "EV_H" |
1983 | The name of the \fIev.h\fR header file used to include it. The default if |
3674 | The name of the \fIev.h\fR header file used to include it. The default if |
1984 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3675 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
1985 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3676 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
1986 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3677 | .IP "\s-1EV_CONFIG_H\s0" 4 |
1987 | .IX Item "EV_CONFIG_H" |
3678 | .IX Item "EV_CONFIG_H" |
1988 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3679 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
1989 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3680 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
1990 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3681 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
1991 | .IP "\s-1EV_EVENT_H\s0" 4 |
3682 | .IP "\s-1EV_EVENT_H\s0" 4 |
1992 | .IX Item "EV_EVENT_H" |
3683 | .IX Item "EV_EVENT_H" |
1993 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3684 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
1994 | of how the \fIevent.h\fR header can be found. |
3685 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
1995 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3686 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
1996 | .IX Item "EV_PROTOTYPES" |
3687 | .IX Item "EV_PROTOTYPES" |
1997 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3688 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
1998 | prototypes, but still define all the structs and other symbols. This is |
3689 | prototypes, but still define all the structs and other symbols. This is |
1999 | occasionally useful if you want to provide your own wrapper functions |
3690 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2003 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3694 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
2004 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3695 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
2005 | additional independent event loops. Otherwise there will be no support |
3696 | additional independent event loops. Otherwise there will be no support |
2006 | for multiple event loops and there is no first event loop pointer |
3697 | for multiple event loops and there is no first event loop pointer |
2007 | argument. Instead, all functions act on the single default loop. |
3698 | argument. Instead, all functions act on the single default loop. |
|
|
3699 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3700 | .IX Item "EV_MINPRI" |
|
|
3701 | .PD 0 |
|
|
3702 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3703 | .IX Item "EV_MAXPRI" |
|
|
3704 | .PD |
|
|
3705 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3706 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3707 | provide for more priorities by overriding those symbols (usually defined |
|
|
3708 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3709 | .Sp |
|
|
3710 | When doing priority-based operations, libev usually has to linearly search |
|
|
3711 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3712 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3713 | fine. |
|
|
3714 | .Sp |
|
|
3715 | If your embedding application does not need any priorities, defining these |
|
|
3716 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
2008 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
3717 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
2009 | .IX Item "EV_PERIODIC_ENABLE" |
3718 | .IX Item "EV_PERIODIC_ENABLE" |
2010 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
3719 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
2011 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
3720 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
2012 | code. |
3721 | code. |
|
|
3722 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3723 | .IX Item "EV_IDLE_ENABLE" |
|
|
3724 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3725 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3726 | code. |
2013 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
3727 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
2014 | .IX Item "EV_EMBED_ENABLE" |
3728 | .IX Item "EV_EMBED_ENABLE" |
2015 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
3729 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
2016 | defined to be \f(CW0\fR, then they are not. |
3730 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3731 | watcher types, which therefore must not be disabled. |
2017 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
3732 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
2018 | .IX Item "EV_STAT_ENABLE" |
3733 | .IX Item "EV_STAT_ENABLE" |
2019 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
3734 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
2020 | defined to be \f(CW0\fR, then they are not. |
3735 | defined to be \f(CW0\fR, then they are not. |
|
|
3736 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3737 | .IX Item "EV_FORK_ENABLE" |
|
|
3738 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3739 | defined to be \f(CW0\fR, then they are not. |
|
|
3740 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3741 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3742 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3743 | defined to be \f(CW0\fR, then they are not. |
2021 | .IP "\s-1EV_MINIMAL\s0" 4 |
3744 | .IP "\s-1EV_MINIMAL\s0" 4 |
2022 | .IX Item "EV_MINIMAL" |
3745 | .IX Item "EV_MINIMAL" |
2023 | If you need to shave off some kilobytes of code at the expense of some |
3746 | If you need to shave off some kilobytes of code at the expense of some |
2024 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3747 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
2025 | some inlining decisions, saves roughly 30% codesize of amd64. |
3748 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
|
|
3749 | much smaller 2\-heap for timer management over the default 4\-heap. |
|
|
3750 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
|
|
3751 | .IX Item "EV_PID_HASHSIZE" |
|
|
3752 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3753 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
|
|
3754 | than enough. If you need to manage thousands of children you might want to |
|
|
3755 | increase this value (\fImust\fR be a power of two). |
|
|
3756 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
3757 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
3758 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3759 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
3760 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
3761 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
3762 | two). |
|
|
3763 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3764 | .IX Item "EV_USE_4HEAP" |
|
|
3765 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3766 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
|
|
3767 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
|
|
3768 | faster performance with many (thousands) of watchers. |
|
|
3769 | .Sp |
|
|
3770 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3771 | (disabled). |
|
|
3772 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3773 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3774 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3775 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
|
|
3776 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3777 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3778 | but avoids random read accesses on heap changes. This improves performance |
|
|
3779 | noticeably with many (hundreds) of watchers. |
|
|
3780 | .Sp |
|
|
3781 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3782 | (disabled). |
|
|
3783 | .IP "\s-1EV_VERIFY\s0" 4 |
|
|
3784 | .IX Item "EV_VERIFY" |
|
|
3785 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
|
|
3786 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
|
|
3787 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
|
|
3788 | called. If set to \f(CW2\fR, then the internal verification code will be |
|
|
3789 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
|
|
3790 | verification code will be called very frequently, which will slow down |
|
|
3791 | libev considerably. |
|
|
3792 | .Sp |
|
|
3793 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
|
|
3794 | \&\f(CW0\fR. |
2026 | .IP "\s-1EV_COMMON\s0" 4 |
3795 | .IP "\s-1EV_COMMON\s0" 4 |
2027 | .IX Item "EV_COMMON" |
3796 | .IX Item "EV_COMMON" |
2028 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3797 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
2029 | this macro to a something else you can include more and other types of |
3798 | this macro to a something else you can include more and other types of |
2030 | members. You have to define it each time you include one of the files, |
3799 | members. You have to define it each time you include one of the files, |
2031 | though, and it must be identical each time. |
3800 | though, and it must be identical each time. |
2032 | .Sp |
3801 | .Sp |
2033 | For example, the perl \s-1EV\s0 module uses something like this: |
3802 | For example, the perl \s-1EV\s0 module uses something like this: |
2034 | .Sp |
3803 | .Sp |
2035 | .Vb 3 |
3804 | .Vb 3 |
2036 | \& #define EV_COMMON \e |
3805 | \& #define EV_COMMON \e |
2037 | \& SV *self; /* contains this struct */ \e |
3806 | \& SV *self; /* contains this struct */ \e |
2038 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
3807 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
2039 | .Ve |
3808 | .Ve |
2040 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
3809 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
2041 | .IX Item "EV_CB_DECLARE (type)" |
3810 | .IX Item "EV_CB_DECLARE (type)" |
2042 | .PD 0 |
3811 | .PD 0 |
2043 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
3812 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
… | |
… | |
2045 | .IP "ev_set_cb (ev, cb)" 4 |
3814 | .IP "ev_set_cb (ev, cb)" 4 |
2046 | .IX Item "ev_set_cb (ev, cb)" |
3815 | .IX Item "ev_set_cb (ev, cb)" |
2047 | .PD |
3816 | .PD |
2048 | Can be used to change the callback member declaration in each watcher, |
3817 | Can be used to change the callback member declaration in each watcher, |
2049 | and the way callbacks are invoked and set. Must expand to a struct member |
3818 | and the way callbacks are invoked and set. Must expand to a struct member |
2050 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3819 | definition and a statement, respectively. See the \fIev.h\fR header file for |
2051 | their default definitions. One possible use for overriding these is to |
3820 | their default definitions. One possible use for overriding these is to |
2052 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3821 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
2053 | method calls instead of plain function calls in \*(C+. |
3822 | method calls instead of plain function calls in \*(C+. |
|
|
3823 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3824 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3825 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
|
|
3826 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3827 | all public symbols, one per line: |
|
|
3828 | .PP |
|
|
3829 | .Vb 2 |
|
|
3830 | \& Symbols.ev for libev proper |
|
|
3831 | \& Symbols.event for the libevent emulation |
|
|
3832 | .Ve |
|
|
3833 | .PP |
|
|
3834 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3835 | multiple versions of libev linked together (which is obviously bad in |
|
|
3836 | itself, but sometimes it is inconvenient to avoid this). |
|
|
3837 | .PP |
|
|
3838 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3839 | include before including \fIev.h\fR: |
|
|
3840 | .PP |
|
|
3841 | .Vb 1 |
|
|
3842 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3843 | .Ve |
|
|
3844 | .PP |
|
|
3845 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3846 | .PP |
|
|
3847 | .Vb 4 |
|
|
3848 | \& #define ev_backend myprefix_ev_backend |
|
|
3849 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3850 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3851 | \& ... |
|
|
3852 | .Ve |
2054 | .Sh "\s-1EXAMPLES\s0" |
3853 | .Sh "\s-1EXAMPLES\s0" |
2055 | .IX Subsection "EXAMPLES" |
3854 | .IX Subsection "EXAMPLES" |
2056 | For a real-world example of a program the includes libev |
3855 | For a real-world example of a program the includes libev |
2057 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3856 | verbatim, you can have a look at the \s-1EV\s0 perl module |
2058 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3857 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2059 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3858 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2060 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3859 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2061 | will be compiled. It is pretty complex because it provides its own header |
3860 | will be compiled. It is pretty complex because it provides its own header |
2062 | file. |
3861 | file. |
2063 | .Sp |
3862 | .PP |
2064 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3863 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2065 | that everybody includes and which overrides some autoconf choices: |
3864 | that everybody includes and which overrides some configure choices: |
2066 | .Sp |
3865 | .PP |
2067 | .Vb 4 |
3866 | .Vb 9 |
|
|
3867 | \& #define EV_MINIMAL 1 |
2068 | \& #define EV_USE_POLL 0 |
3868 | \& #define EV_USE_POLL 0 |
2069 | \& #define EV_MULTIPLICITY 0 |
3869 | \& #define EV_MULTIPLICITY 0 |
2070 | \& #define EV_PERIODICS 0 |
3870 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3871 | \& #define EV_STAT_ENABLE 0 |
|
|
3872 | \& #define EV_FORK_ENABLE 0 |
2071 | \& #define EV_CONFIG_H <config.h> |
3873 | \& #define EV_CONFIG_H <config.h> |
2072 | .Ve |
3874 | \& #define EV_MINPRI 0 |
2073 | .Sp |
3875 | \& #define EV_MAXPRI 0 |
2074 | .Vb 1 |
3876 | \& |
2075 | \& #include "ev++.h" |
3877 | \& #include "ev++.h" |
2076 | .Ve |
3878 | .Ve |
2077 | .Sp |
3879 | .PP |
2078 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3880 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2079 | .Sp |
3881 | .PP |
2080 | .Vb 2 |
3882 | .Vb 2 |
2081 | \& #include "ev_cpp.h" |
3883 | \& #include "ev_cpp.h" |
2082 | \& #include "ev.c" |
3884 | \& #include "ev.c" |
2083 | .Ve |
3885 | .Ve |
|
|
3886 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
3887 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
3888 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
|
|
3889 | .IX Subsection "THREADS AND COROUTINES" |
|
|
3890 | \fI\s-1THREADS\s0\fR |
|
|
3891 | .IX Subsection "THREADS" |
|
|
3892 | .PP |
|
|
3893 | All libev functions are reentrant and thread-safe unless explicitly |
|
|
3894 | documented otherwise, but libev implements no locking itself. This means |
|
|
3895 | that you can use as many loops as you want in parallel, as long as there |
|
|
3896 | are no concurrent calls into any libev function with the same loop |
|
|
3897 | parameter (\f(CW\*(C`ev_default_*\*(C'\fR calls have an implicit default loop parameter, |
|
|
3898 | of course): libev guarantees that different event loops share no data |
|
|
3899 | structures that need any locking. |
|
|
3900 | .PP |
|
|
3901 | Or to put it differently: calls with different loop parameters can be done |
|
|
3902 | concurrently from multiple threads, calls with the same loop parameter |
|
|
3903 | must be done serially (but can be done from different threads, as long as |
|
|
3904 | only one thread ever is inside a call at any point in time, e.g. by using |
|
|
3905 | a mutex per loop). |
|
|
3906 | .PP |
|
|
3907 | Specifically to support threads (and signal handlers), libev implements |
|
|
3908 | so-called \f(CW\*(C`ev_async\*(C'\fR watchers, which allow some limited form of |
|
|
3909 | concurrency on the same event loop, namely waking it up \*(L"from the |
|
|
3910 | outside\*(R". |
|
|
3911 | .PP |
|
|
3912 | If you want to know which design (one loop, locking, or multiple loops |
|
|
3913 | without or something else still) is best for your problem, then I cannot |
|
|
3914 | help you, but here is some generic advice: |
|
|
3915 | .IP "\(bu" 4 |
|
|
3916 | most applications have a main thread: use the default libev loop |
|
|
3917 | in that thread, or create a separate thread running only the default loop. |
|
|
3918 | .Sp |
|
|
3919 | This helps integrating other libraries or software modules that use libev |
|
|
3920 | themselves and don't care/know about threading. |
|
|
3921 | .IP "\(bu" 4 |
|
|
3922 | one loop per thread is usually a good model. |
|
|
3923 | .Sp |
|
|
3924 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3925 | exists, but it is always a good start. |
|
|
3926 | .IP "\(bu" 4 |
|
|
3927 | other models exist, such as the leader/follower pattern, where one |
|
|
3928 | loop is handed through multiple threads in a kind of round-robin fashion. |
|
|
3929 | .Sp |
|
|
3930 | Choosing a model is hard \- look around, learn, know that usually you can do |
|
|
3931 | better than you currently do :\-) |
|
|
3932 | .IP "\(bu" 4 |
|
|
3933 | often you need to talk to some other thread which blocks in the |
|
|
3934 | event loop. |
|
|
3935 | .Sp |
|
|
3936 | \&\f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other threads safely |
|
|
3937 | (or from signal contexts...). |
|
|
3938 | .Sp |
|
|
3939 | An example use would be to communicate signals or other events that only |
|
|
3940 | work in the default loop by registering the signal watcher with the |
|
|
3941 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
|
|
3942 | watcher callback into the event loop interested in the signal. |
|
|
3943 | .PP |
|
|
3944 | \fI\s-1COROUTINES\s0\fR |
|
|
3945 | .IX Subsection "COROUTINES" |
|
|
3946 | .PP |
|
|
3947 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3948 | libev fully supports nesting calls to its functions from different |
|
|
3949 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3950 | different coroutines, and switch freely between both coroutines running the |
|
|
3951 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3952 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3953 | .PP |
|
|
3954 | Care has been taken to ensure that libev does not keep local state inside |
|
|
3955 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
|
|
3956 | they do not call any callbacks. |
|
|
3957 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
|
|
3958 | .IX Subsection "COMPILER WARNINGS" |
|
|
3959 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3960 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3961 | scared by this. |
|
|
3962 | .PP |
|
|
3963 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
3964 | has different warnings, and each user has different tastes regarding |
|
|
3965 | warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when |
|
|
3966 | targeting a specific compiler and compiler-version. |
|
|
3967 | .PP |
|
|
3968 | Another reason is that some compiler warnings require elaborate |
|
|
3969 | workarounds, or other changes to the code that make it less clear and less |
|
|
3970 | maintainable. |
|
|
3971 | .PP |
|
|
3972 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3973 | wrong (because they don't actually warn about the condition their message |
|
|
3974 | seems to warn about). For example, certain older gcc versions had some |
|
|
3975 | warnings that resulted an extreme number of false positives. These have |
|
|
3976 | been fixed, but some people still insist on making code warn-free with |
|
|
3977 | such buggy versions. |
|
|
3978 | .PP |
|
|
3979 | While libev is written to generate as few warnings as possible, |
|
|
3980 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
|
|
3981 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3982 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3983 | warnings, not errors, or proof of bugs. |
|
|
3984 | .Sh "\s-1VALGRIND\s0" |
|
|
3985 | .IX Subsection "VALGRIND" |
|
|
3986 | Valgrind has a special section here because it is a popular tool that is |
|
|
3987 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
|
|
3988 | .PP |
|
|
3989 | If you think you found a bug (memory leak, uninitialised data access etc.) |
|
|
3990 | in libev, then check twice: If valgrind reports something like: |
|
|
3991 | .PP |
|
|
3992 | .Vb 3 |
|
|
3993 | \& ==2274== definitely lost: 0 bytes in 0 blocks. |
|
|
3994 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
|
|
3995 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
|
|
3996 | .Ve |
|
|
3997 | .PP |
|
|
3998 | Then there is no memory leak, just as memory accounted to global variables |
|
|
3999 | is not a memleak \- the memory is still being referenced, and didn't leak. |
|
|
4000 | .PP |
|
|
4001 | Similarly, under some circumstances, valgrind might report kernel bugs |
|
|
4002 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
|
|
4003 | although an acceptable workaround has been found here), or it might be |
|
|
4004 | confused. |
|
|
4005 | .PP |
|
|
4006 | Keep in mind that valgrind is a very good tool, but only a tool. Don't |
|
|
4007 | make it into some kind of religion. |
|
|
4008 | .PP |
|
|
4009 | If you are unsure about something, feel free to contact the mailing list |
|
|
4010 | with the full valgrind report and an explanation on why you think this |
|
|
4011 | is a bug in libev (best check the archives, too :). However, don't be |
|
|
4012 | annoyed when you get a brisk \*(L"this is no bug\*(R" answer and take the chance |
|
|
4013 | of learning how to interpret valgrind properly. |
|
|
4014 | .PP |
|
|
4015 | If you need, for some reason, empty reports from valgrind for your project |
|
|
4016 | I suggest using suppression lists. |
|
|
4017 | .SH "PORTABILITY NOTES" |
|
|
4018 | .IX Header "PORTABILITY NOTES" |
|
|
4019 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
4020 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
4021 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
4022 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
4023 | model. Libev still offers limited functionality on this platform in |
|
|
4024 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
4025 | descriptors. This only applies when using Win32 natively, not when using |
|
|
4026 | e.g. cygwin. |
|
|
4027 | .PP |
|
|
4028 | Lifting these limitations would basically require the full |
|
|
4029 | re-implementation of the I/O system. If you are into these kinds of |
|
|
4030 | things, then note that glib does exactly that for you in a very portable |
|
|
4031 | way (note also that glib is the slowest event library known to man). |
|
|
4032 | .PP |
|
|
4033 | There is no supported compilation method available on windows except |
|
|
4034 | embedding it into other applications. |
|
|
4035 | .PP |
|
|
4036 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4037 | tries its best, but under most conditions, signals will simply not work. |
|
|
4038 | .PP |
|
|
4039 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
4040 | accept large writes: instead of resulting in a partial write, windows will |
|
|
4041 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
|
|
4042 | so make sure you only write small amounts into your sockets (less than a |
|
|
4043 | megabyte seems safe, but this apparently depends on the amount of memory |
|
|
4044 | available). |
|
|
4045 | .PP |
|
|
4046 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
4047 | the abysmal performance of winsockets, using a large number of sockets |
|
|
4048 | is not recommended (and not reasonable). If your program needs to use |
|
|
4049 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
4050 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
|
|
4051 | notification model, which cannot be implemented efficiently on windows |
|
|
4052 | (due to Microsoft monopoly games). |
|
|
4053 | .PP |
|
|
4054 | A typical way to use libev under windows is to embed it (see the embedding |
|
|
4055 | section for details) and use the following \fIevwrap.h\fR header file instead |
|
|
4056 | of \fIev.h\fR: |
|
|
4057 | .PP |
|
|
4058 | .Vb 2 |
|
|
4059 | \& #define EV_STANDALONE /* keeps ev from requiring config.h */ |
|
|
4060 | \& #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */ |
|
|
4061 | \& |
|
|
4062 | \& #include "ev.h" |
|
|
4063 | .Ve |
|
|
4064 | .PP |
|
|
4065 | And compile the following \fIevwrap.c\fR file into your project (make sure |
|
|
4066 | you do \fInot\fR compile the \fIev.c\fR or any other embedded source files!): |
|
|
4067 | .PP |
|
|
4068 | .Vb 2 |
|
|
4069 | \& #include "evwrap.h" |
|
|
4070 | \& #include "ev.c" |
|
|
4071 | .Ve |
|
|
4072 | .IP "The winsocket select function" 4 |
|
|
4073 | .IX Item "The winsocket select function" |
|
|
4074 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
|
|
4075 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
|
|
4076 | also extremely buggy). This makes select very inefficient, and also |
|
|
4077 | requires a mapping from file descriptors to socket handles (the Microsoft |
|
|
4078 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
|
|
4079 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
|
|
4080 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
|
|
4081 | .Sp |
|
|
4082 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
|
|
4083 | libraries and raw winsocket select is: |
|
|
4084 | .Sp |
|
|
4085 | .Vb 2 |
|
|
4086 | \& #define EV_USE_SELECT 1 |
|
|
4087 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
4088 | .Ve |
|
|
4089 | .Sp |
|
|
4090 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
4091 | complexity in the O(nA\*^X) range when using win32. |
|
|
4092 | .IP "Limited number of file descriptors" 4 |
|
|
4093 | .IX Item "Limited number of file descriptors" |
|
|
4094 | Windows has numerous arbitrary (and low) limits on things. |
|
|
4095 | .Sp |
|
|
4096 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
4097 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
4098 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
|
|
4099 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
4100 | previous thread in each. Sounds great!). |
|
|
4101 | .Sp |
|
|
4102 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
4103 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
4104 | call (which might be in libev or elsewhere, for example, perl and many |
|
|
4105 | other interpreters do their own select emulation on windows). |
|
|
4106 | .Sp |
|
|
4107 | Another limit is the number of file descriptors in the Microsoft runtime |
|
|
4108 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
|
|
4109 | fetish or something like this inside Microsoft). You can increase this |
|
|
4110 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
|
|
4111 | (another arbitrary limit), but is broken in many versions of the Microsoft |
|
|
4112 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
|
|
4113 | (depending on windows version and/or the phase of the moon). To get more, |
|
|
4114 | you need to wrap all I/O functions and provide your own fd management, but |
|
|
4115 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
4116 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
|
|
4117 | .IX Subsection "PORTABILITY REQUIREMENTS" |
|
|
4118 | In addition to a working ISO-C implementation and of course the |
|
|
4119 | backend-specific APIs, libev relies on a few additional extensions: |
|
|
4120 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
|
|
4121 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
|
|
4122 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
|
|
4123 | Libev assumes not only that all watcher pointers have the same internal |
|
|
4124 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
|
|
4125 | assumes that the same (machine) code can be used to call any watcher |
|
|
4126 | callback: The watcher callbacks have different type signatures, but libev |
|
|
4127 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
4128 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
4129 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
4130 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
4131 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
4132 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
|
|
4133 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
4134 | believed to be sufficiently portable. |
|
|
4135 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
4136 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
4137 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
4138 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
|
|
4139 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
|
|
4140 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
|
|
4141 | thread\*(R" or will block signals process-wide, both behaviours would |
|
|
4142 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
|
|
4143 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
|
|
4144 | .Sp |
|
|
4145 | The most portable way to handle signals is to block signals in all threads |
|
|
4146 | except the initial one, and run the default loop in the initial thread as |
|
|
4147 | well. |
|
|
4148 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
|
|
4149 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
|
|
4150 | .IX Item "long must be large enough for common memory allocation sizes" |
|
|
4151 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
|
|
4152 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
|
|
4153 | systems (Microsoft...) this might be unexpectedly low, but is still at |
|
|
4154 | least 31 bits everywhere, which is enough for hundreds of millions of |
|
|
4155 | watchers. |
|
|
4156 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
|
|
4157 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
|
|
4158 | .IX Item "double must hold a time value in seconds with enough accuracy" |
|
|
4159 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
|
|
4160 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
4161 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
4162 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
|
|
4163 | .PP |
|
|
4164 | If you know of other additional requirements drop me a note. |
2084 | .SH "COMPLEXITIES" |
4165 | .SH "ALGORITHMIC COMPLEXITIES" |
2085 | .IX Header "COMPLEXITIES" |
4166 | .IX Header "ALGORITHMIC COMPLEXITIES" |
2086 | In this section the complexities of (many of) the algorithms used inside |
4167 | In this section the complexities of (many of) the algorithms used inside |
2087 | libev will be explained. For complexity discussions about backends see the |
4168 | libev will be documented. For complexity discussions about backends see |
2088 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
4169 | the documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2089 | .RS 4 |
4170 | .PP |
|
|
4171 | All of the following are about amortised time: If an array needs to be |
|
|
4172 | extended, libev needs to realloc and move the whole array, but this |
|
|
4173 | happens asymptotically rarer with higher number of elements, so O(1) might |
|
|
4174 | mean that libev does a lengthy realloc operation in rare cases, but on |
|
|
4175 | average it is much faster and asymptotically approaches constant time. |
2090 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
4176 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2091 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
4177 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
4178 | This means that, when you have a watcher that triggers in one hour and |
|
|
4179 | there are 100 watchers that would trigger before that, then inserting will |
|
|
4180 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
4181 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
4182 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
4183 | That means that changing a timer costs less than removing/adding them, |
|
|
4184 | as only the relative motion in the event queue has to be paid for. |
|
|
4185 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
4186 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
4187 | These just add the watcher into an array or at the head of a list. |
|
|
4188 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
4189 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
2092 | .PD 0 |
4190 | .PD 0 |
2093 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2094 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
|
|
2095 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
|
|
2096 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
|
|
2097 | .IP "Stopping check/prepare/idle watchers: O(1)" 4 |
|
|
2098 | .IX Item "Stopping check/prepare/idle watchers: O(1)" |
|
|
2099 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 |
4191 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2100 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" |
4192 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
4193 | .PD |
|
|
4194 | These watchers are stored in lists, so they need to be walked to find the |
|
|
4195 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
4196 | have many watchers waiting for the same fd or signal: one is typical, two |
|
|
4197 | is rare). |
2101 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
4198 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2102 | .IX Item "Finding the next timer per loop iteration: O(1)" |
4199 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
4200 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
4201 | fixed position in the storage array. |
2103 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
4202 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2104 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
4203 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2105 | .IP "Activating one watcher: O(1)" 4 |
4204 | A change means an I/O watcher gets started or stopped, which requires |
2106 | .IX Item "Activating one watcher: O(1)" |
4205 | libev to recalculate its status (and possibly tell the kernel, depending |
2107 | .RE |
4206 | on backend and whether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2108 | .RS 4 |
4207 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
4208 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
4209 | .PD 0 |
|
|
4210 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
4211 | .IX Item "Priority handling: O(number_of_priorities)" |
2109 | .PD |
4212 | .PD |
|
|
4213 | Priorities are implemented by allocating some space for each |
|
|
4214 | priority. When doing priority-based operations, libev usually has to |
|
|
4215 | linearly search all the priorities, but starting/stopping and activating |
|
|
4216 | watchers becomes O(1) with respect to priority handling. |
|
|
4217 | .IP "Sending an ev_async: O(1)" 4 |
|
|
4218 | .IX Item "Sending an ev_async: O(1)" |
|
|
4219 | .PD 0 |
|
|
4220 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
4221 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
4222 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
4223 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
4224 | .PD |
|
|
4225 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
4226 | calls in the current loop iteration. Checking for async and signal events |
|
|
4227 | involves iterating over all running async watchers or all signal numbers. |
|
|
4228 | .SH "GLOSSARY" |
|
|
4229 | .IX Header "GLOSSARY" |
|
|
4230 | .IP "active" 4 |
|
|
4231 | .IX Item "active" |
|
|
4232 | A watcher is active as long as it has been started (has been attached to |
|
|
4233 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4234 | .IP "application" 4 |
|
|
4235 | .IX Item "application" |
|
|
4236 | In this document, an application is whatever is using libev. |
|
|
4237 | .IP "callback" 4 |
|
|
4238 | .IX Item "callback" |
|
|
4239 | The address of a function that is called when some event has been |
|
|
4240 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4241 | received the event, and the actual event bitset. |
|
|
4242 | .IP "callback invocation" 4 |
|
|
4243 | .IX Item "callback invocation" |
|
|
4244 | The act of calling the callback associated with a watcher. |
|
|
4245 | .IP "event" 4 |
|
|
4246 | .IX Item "event" |
|
|
4247 | A change of state of some external event, such as data now being available |
|
|
4248 | for reading on a file descriptor, time having passed or simply not having |
|
|
4249 | any other events happening anymore. |
|
|
4250 | .Sp |
|
|
4251 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
4252 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
|
|
4253 | .IP "event library" 4 |
|
|
4254 | .IX Item "event library" |
|
|
4255 | A software package implementing an event model and loop. |
|
|
4256 | .IP "event loop" 4 |
|
|
4257 | .IX Item "event loop" |
|
|
4258 | An entity that handles and processes external events and converts them |
|
|
4259 | into callback invocations. |
|
|
4260 | .IP "event model" 4 |
|
|
4261 | .IX Item "event model" |
|
|
4262 | The model used to describe how an event loop handles and processes |
|
|
4263 | watchers and events. |
|
|
4264 | .IP "pending" 4 |
|
|
4265 | .IX Item "pending" |
|
|
4266 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4267 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4268 | pending status is explicitly cleared by the application. |
|
|
4269 | .Sp |
|
|
4270 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4271 | its pending status. |
|
|
4272 | .IP "real time" 4 |
|
|
4273 | .IX Item "real time" |
|
|
4274 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4275 | .IP "wall-clock time" 4 |
|
|
4276 | .IX Item "wall-clock time" |
|
|
4277 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4278 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4279 | clock. |
|
|
4280 | .IP "watcher" 4 |
|
|
4281 | .IX Item "watcher" |
|
|
4282 | A data structure that describes interest in certain events. Watchers need |
|
|
4283 | to be started (attached to an event loop) before they can receive events. |
|
|
4284 | .IP "watcher invocation" 4 |
|
|
4285 | .IX Item "watcher invocation" |
|
|
4286 | The act of calling the callback associated with a watcher. |
2110 | .SH "AUTHOR" |
4287 | .SH "AUTHOR" |
2111 | .IX Header "AUTHOR" |
4288 | .IX Header "AUTHOR" |
2112 | Marc Lehmann <libev@schmorp.de>. |
4289 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |