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131 | .IX Title ""<STANDARD INPUT>" 1" |
134 | .IX Title "LIBEV 3" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-24" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH LIBEV 3 "2008-05-09" "libev-1.1" "libev - high perfromance 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 |
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147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
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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 | \& // every watcher type has its own typedef\*(Aqd struct |
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154 | \& // with the name ev_<type> |
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155 | \& ev_io stdin_watcher; |
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156 | \& ev_timer timeout_watcher; |
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157 | \& |
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158 | \& // all watcher callbacks have a similar signature |
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159 | \& // this callback is called when data is readable on stdin |
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160 | \& static void |
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161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
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162 | \& { |
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163 | \& puts ("stdin ready"); |
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164 | \& // for one\-shot events, one must manually stop the watcher |
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165 | \& // with its corresponding stop function. |
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166 | \& ev_io_stop (EV_A_ w); |
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167 | \& |
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168 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
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170 | \& } |
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171 | \& |
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172 | \& // another callback, this time for a time\-out |
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173 | \& static void |
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174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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175 | \& { |
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176 | \& puts ("timeout"); |
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177 | \& // this causes the innermost ev_loop to stop iterating |
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178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
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179 | \& } |
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180 | \& |
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181 | \& int |
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182 | \& main (void) |
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183 | \& { |
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184 | \& // use the default event loop unless you have special needs |
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185 | \& struct ev_loop *loop = ev_default_loop (0); |
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186 | \& |
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187 | \& // initialise an io watcher, then start it |
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188 | \& // this one will watch for stdin to become readable |
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189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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190 | \& ev_io_start (loop, &stdin_watcher); |
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191 | \& |
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192 | \& // initialise a timer watcher, then start it |
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193 | \& // simple non\-repeating 5.5 second timeout |
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194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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195 | \& ev_timer_start (loop, &timeout_watcher); |
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196 | \& |
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197 | \& // now wait for events to arrive |
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198 | \& ev_loop (loop, 0); |
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199 | \& |
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200 | \& // unloop was called, so exit |
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201 | \& return 0; |
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202 | \& } |
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203 | .Ve |
140 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
141 | .IX Header "DESCRIPTION" |
205 | .IX Header "DESCRIPTION" |
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206 | The newest version of this document is also available as an html-formatted |
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207 | web page you might find easier to navigate when reading it for the first |
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208 | time: <http://cvs.schmorp.de/libev/ev.html>. |
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209 | .PP |
142 | Libev is an event loop: you register interest in certain events (such as a |
210 | 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 |
211 | file descriptor being readable or a timeout occurring), and it will manage |
144 | these event sources and provide your program with events. |
212 | these event sources and provide your program with events. |
145 | .PP |
213 | .PP |
146 | To do this, it must take more or less complete control over your process |
214 | 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 |
215 | (or thread) by executing the \fIevent loop\fR handler, and will then |
148 | communicate events via a callback mechanism. |
216 | communicate events via a callback mechanism. |
149 | .PP |
217 | .PP |
150 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
151 | watchers\fR, which are relatively small C structures you initialise with the |
219 | 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 |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
153 | watcher. |
221 | watcher. |
154 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
155 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
156 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
224 | 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 |
225 | 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 |
226 | 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 |
227 | (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 |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
161 | fast (see this benchmark comparing |
229 | (\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). |
230 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
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231 | \&\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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232 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
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233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
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234 | .PP |
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235 | It also is quite fast (see this |
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236 | benchmark comparing it to libevent |
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237 | for example). |
163 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
164 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
165 | Libev is very configurable. In this manual the default configuration |
240 | Libev is very configurable. In this manual the default (and most common) |
166 | will be described, which supports multiple event loops. For more info |
241 | configuration will be described, which supports multiple event loops. For |
167 | about various configuration options please have a look at the file |
242 | 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 |
243 | \&\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 |
244 | 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) |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
171 | will not have this argument. |
246 | this argument. |
172 | .SH "TIME REPRESENTATION" |
247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
173 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
174 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
175 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
250 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
176 | the beginning of 1970, details are complicated, don't ask). This type is |
251 | the beginning of 1970, details are complicated, don't ask). This type is |
177 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
252 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
178 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
253 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
179 | it, you should treat it as such. |
254 | it, you should treat it as some floatingpoint value. Unlike the name |
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255 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
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256 | throughout libev. |
180 | .SH "GLOBAL FUNCTIONS" |
257 | .SH "GLOBAL FUNCTIONS" |
181 | .IX Header "GLOBAL FUNCTIONS" |
258 | .IX Header "GLOBAL FUNCTIONS" |
182 | These functions can be called anytime, even before initialising the |
259 | These functions can be called anytime, even before initialising the |
183 | library in any way. |
260 | library in any way. |
184 | .IP "ev_tstamp ev_time ()" 4 |
261 | .IP "ev_tstamp ev_time ()" 4 |
185 | .IX Item "ev_tstamp ev_time ()" |
262 | .IX Item "ev_tstamp ev_time ()" |
186 | Returns the current time as libev would use it. Please note that the |
263 | 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 |
264 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
188 | you actually want to know. |
265 | you actually want to know. |
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266 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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267 | .IX Item "ev_sleep (ev_tstamp interval)" |
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268 | Sleep for the given interval: The current thread will be blocked until |
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269 | either it is interrupted or the given time interval has passed. Basically |
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270 | this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
189 | .IP "int ev_version_major ()" 4 |
271 | .IP "int ev_version_major ()" 4 |
190 | .IX Item "int ev_version_major ()" |
272 | .IX Item "int ev_version_major ()" |
191 | .PD 0 |
273 | .PD 0 |
192 | .IP "int ev_version_minor ()" 4 |
274 | .IP "int ev_version_minor ()" 4 |
193 | .IX Item "int ev_version_minor ()" |
275 | .IX Item "int ev_version_minor ()" |
194 | .PD |
276 | .PD |
195 | You can find out the major and minor version numbers of the library |
277 | 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 |
278 | 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 |
279 | \&\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 |
280 | 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. |
281 | version of the library your program was compiled against. |
200 | .Sp |
282 | .Sp |
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283 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
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284 | release version. |
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285 | .Sp |
201 | Usually, it's a good idea to terminate if the major versions mismatch, |
286 | Usually, it's a good idea to terminate if the major versions mismatch, |
202 | as this indicates an incompatible change. Minor versions are usually |
287 | as this indicates an incompatible change. Minor versions are usually |
203 | compatible to older versions, so a larger minor version alone is usually |
288 | compatible to older versions, so a larger minor version alone is usually |
204 | not a problem. |
289 | not a problem. |
205 | .Sp |
290 | .Sp |
206 | Example: make sure we haven't accidentally been linked against the wrong |
291 | Example: Make sure we haven't accidentally been linked against the wrong |
207 | version: |
292 | version. |
208 | .Sp |
293 | .Sp |
209 | .Vb 3 |
294 | .Vb 3 |
210 | \& assert (("libev version mismatch", |
295 | \& assert (("libev version mismatch", |
211 | \& ev_version_major () == EV_VERSION_MAJOR |
296 | \& ev_version_major () == EV_VERSION_MAJOR |
212 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
297 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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234 | (assuming you know what you are doing). This is the set of backends that |
319 | (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. |
320 | libev will probe for if you specify no backends explicitly. |
236 | .IP "unsigned int ev_embeddable_backends ()" 4 |
321 | .IP "unsigned int ev_embeddable_backends ()" 4 |
237 | .IX Item "unsigned int ev_embeddable_backends ()" |
322 | .IX Item "unsigned int ev_embeddable_backends ()" |
238 | Returns the set of backends that are embeddable in other event loops. This |
323 | Returns the set of backends that are embeddable in other event loops. This |
239 | is the theoretical, all\-platform, value. To find which backends |
324 | is the theoretical, all-platform, value. To find which backends |
240 | might be supported on the current system, you would need to look at |
325 | 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 |
326 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
242 | recommended ones. |
327 | recommended ones. |
243 | .Sp |
328 | .Sp |
244 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
329 | 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 |
330 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
246 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
331 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
247 | Sets the allocation function to use (the prototype is similar to the |
332 | Sets the allocation function to use (the prototype is similar \- the |
248 | realloc C function, the semantics are identical). It is used to allocate |
333 | 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 |
334 | 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 |
335 | 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. |
336 | or take some potentially destructive action. |
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337 | .Sp |
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338 | Since some systems (at least OpenBSD and Darwin) fail to implement |
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339 | correct \f(CW\*(C`realloc\*(C'\fR semantics, libev will use a wrapper around the system |
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340 | \&\f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions by default. |
252 | .Sp |
341 | .Sp |
253 | You could override this function in high-availability programs to, say, |
342 | 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, |
343 | 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. |
344 | or even to sleep a while and retry until some memory is available. |
256 | .Sp |
345 | .Sp |
257 | Example: replace the libev allocator with one that waits a bit and then |
346 | Example: Replace the libev allocator with one that waits a bit and then |
258 | retries: better than mine). |
347 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
259 | .Sp |
348 | .Sp |
260 | .Vb 6 |
349 | .Vb 6 |
261 | \& static void * |
350 | \& static void * |
262 | \& persistent_realloc (void *ptr, long size) |
351 | \& persistent_realloc (void *ptr, size_t size) |
263 | \& { |
352 | \& { |
264 | \& for (;;) |
353 | \& for (;;) |
265 | \& { |
354 | \& { |
266 | \& void *newptr = realloc (ptr, size); |
355 | \& void *newptr = realloc (ptr, size); |
267 | .Ve |
356 | \& |
268 | .Sp |
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269 | .Vb 2 |
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270 | \& if (newptr) |
357 | \& if (newptr) |
271 | \& return newptr; |
358 | \& return newptr; |
272 | .Ve |
359 | \& |
273 | .Sp |
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274 | .Vb 3 |
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275 | \& sleep (60); |
360 | \& sleep (60); |
276 | \& } |
361 | \& } |
277 | \& } |
362 | \& } |
278 | .Ve |
363 | \& |
279 | .Sp |
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280 | .Vb 2 |
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281 | \& ... |
364 | \& ... |
282 | \& ev_set_allocator (persistent_realloc); |
365 | \& ev_set_allocator (persistent_realloc); |
283 | .Ve |
366 | .Ve |
284 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
367 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
285 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
368 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
… | |
… | |
289 | callback is set, then libev will expect it to remedy the sitution, no |
372 | callback is set, then libev will expect it to remedy the sitution, no |
290 | matter what, when it returns. That is, libev will generally retry the |
373 | 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 |
374 | requested operation, or, if the condition doesn't go away, do bad stuff |
292 | (such as abort). |
375 | (such as abort). |
293 | .Sp |
376 | .Sp |
294 | Example: do the same thing as libev does internally: |
377 | Example: This is basically the same thing that libev does internally, too. |
295 | .Sp |
378 | .Sp |
296 | .Vb 6 |
379 | .Vb 6 |
297 | \& static void |
380 | \& static void |
298 | \& fatal_error (const char *msg) |
381 | \& fatal_error (const char *msg) |
299 | \& { |
382 | \& { |
300 | \& perror (msg); |
383 | \& perror (msg); |
301 | \& abort (); |
384 | \& abort (); |
302 | \& } |
385 | \& } |
303 | .Ve |
386 | \& |
304 | .Sp |
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305 | .Vb 2 |
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306 | \& ... |
387 | \& ... |
307 | \& ev_set_syserr_cb (fatal_error); |
388 | \& ev_set_syserr_cb (fatal_error); |
308 | .Ve |
389 | .Ve |
309 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
390 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
310 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
391 | .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 |
392 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
312 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
393 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
313 | events, and dynamically created loops which do not. |
394 | events, and dynamically created loops which do not. |
314 | .PP |
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315 | If you use threads, a common model is to run the default event loop |
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316 | in your main thread (or in a separate thread) and for each thread you |
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317 | create, you also create another event loop. Libev itself does no locking |
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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). |
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321 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
395 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
322 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
396 | .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 |
397 | 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 |
398 | 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 |
399 | 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). |
400 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
327 | .Sp |
401 | .Sp |
328 | If you don't know what event loop to use, use the one returned from this |
402 | If you don't know what event loop to use, use the one returned from this |
329 | function. |
403 | function. |
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404 | .Sp |
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405 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
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406 | from multiple threads, you have to lock (note also that this is unlikely, |
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407 | as loops cannot bes hared easily between threads anyway). |
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408 | .Sp |
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409 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
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410 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
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411 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
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412 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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413 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
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414 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
330 | .Sp |
415 | .Sp |
331 | The flags argument can be used to specify special behaviour or specific |
416 | 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). |
417 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
333 | .Sp |
418 | .Sp |
334 | The following flags are supported: |
419 | The following flags are supported: |
… | |
… | |
345 | or setgid) then libev will \fInot\fR look at the environment variable |
430 | 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 |
431 | \&\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 |
432 | 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 |
433 | useful to try out specific backends to test their performance, or to work |
349 | around bugs. |
434 | around bugs. |
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435 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
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436 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
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437 | .IX Item "EVFLAG_FORKCHECK" |
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438 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
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439 | a fork, you can also make libev check for a fork in each iteration by |
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440 | enabling this flag. |
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441 | .Sp |
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442 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
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443 | and thus this might slow down your event loop if you do a lot of loop |
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444 | iterations and little real work, but is usually not noticeable (on my |
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445 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
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446 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
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447 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
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448 | .Sp |
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449 | The big advantage of this flag is that you can forget about fork (and |
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450 | forget about forgetting to tell libev about forking) when you use this |
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451 | flag. |
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452 | .Sp |
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453 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
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454 | environment variable. |
350 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
455 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
351 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
456 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
352 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
457 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
353 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
458 | 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, |
459 | 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 |
460 | 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 |
461 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
357 | the fastest backend for a low number of fds. |
462 | usually the fastest backend for a low number of (low-numbered :) fds. |
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463 | .Sp |
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464 | To get good performance out of this backend you need a high amount of |
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465 | parallelity (most of the file descriptors should be busy). If you are |
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466 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
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467 | connections as possible during one iteration. You might also want to have |
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468 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
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469 | readyness notifications you get per iteration. |
358 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
470 | .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 |
471 | .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)" |
472 | .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 |
473 | 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 |
474 | 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 |
475 | 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). |
476 | considerably with a lot of inactive fds). It scales similarly to select, |
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477 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
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478 | performance tips. |
365 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
479 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
366 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
480 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
367 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
481 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
368 | For few fds, this backend is a bit little slower than poll and select, |
482 | 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 |
483 | 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 |
484 | like O(total_fds) where n is the total number of fds (or the highest fd), |
371 | either O(1) or O(active_fds). |
485 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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486 | of shortcomings, such as silently dropping events in some hard-to-detect |
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487 | cases and requiring a syscall per fd change, no fork support and bad |
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488 | support for dup. |
372 | .Sp |
489 | .Sp |
373 | While stopping and starting an I/O watcher in the same iteration will |
490 | 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 |
491 | will result in some caching, there is still a syscall per such incident |
375 | (because the fd could point to a different file description now), so its |
492 | (because the fd could point to a different file description now), so its |
376 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
493 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
377 | well if you register events for both fds. |
494 | very well if you register events for both fds. |
378 | .Sp |
495 | .Sp |
379 | Please note that epoll sometimes generates spurious notifications, so you |
496 | Please note that epoll sometimes generates spurious notifications, so you |
380 | need to use non-blocking I/O or other means to avoid blocking when no data |
497 | need to use non-blocking I/O or other means to avoid blocking when no data |
381 | (or space) is available. |
498 | (or space) is available. |
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499 | .Sp |
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500 | Best performance from this backend is achieved by not unregistering all |
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501 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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502 | keep at least one watcher active per fd at all times. |
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503 | .Sp |
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504 | While nominally embeddeble in other event loops, this feature is broken in |
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505 | all kernel versions tested so far. |
382 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
506 | .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 |
507 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
384 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
508 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
385 | Kqueue deserves special mention, as at the time of this writing, it |
509 | 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 |
510 | 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 |
511 | with anything but sockets and pipes, except on Darwin, where of course |
388 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
512 | it's completely useless). For this reason it's not being \*(L"autodetected\*(R" |
389 | unless you explicitly specify it explicitly in the flags (i.e. using |
513 | unless you explicitly specify it explicitly in the flags (i.e. using |
390 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
514 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
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515 | system like NetBSD. |
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516 | .Sp |
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517 | You still can embed kqueue into a normal poll or select backend and use it |
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518 | only for sockets (after having made sure that sockets work with kqueue on |
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519 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
391 | .Sp |
520 | .Sp |
392 | It scales in the same way as the epoll backend, but the interface to the |
521 | 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 |
522 | 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 |
523 | 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 |
524 | cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
396 | incident, so its best to avoid that. |
525 | two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
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526 | drops fds silently in similarly hard-to-detect cases. |
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|
527 | .Sp |
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528 | This backend usually performs well under most conditions. |
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529 | .Sp |
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530 | While nominally embeddable in other event loops, this doesn't work |
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531 | everywhere, so you might need to test for this. And since it is broken |
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532 | almost everywhere, you should only use it when you have a lot of sockets |
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533 | (for which it usually works), by embedding it into another event loop |
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534 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for |
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535 | sockets. |
397 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
536 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
398 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
537 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
399 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
538 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
400 | This is not implemented yet (and might never be). |
539 | This is not implemented yet (and might never be, unless you send me an |
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540 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
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541 | and is not embeddable, which would limit the usefulness of this backend |
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542 | immensely. |
401 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
543 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
402 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
544 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
403 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
545 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
404 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
546 | 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)). |
547 | it's really slow, but it still scales very well (O(active_fds)). |
406 | .Sp |
548 | .Sp |
407 | Please note that solaris ports can result in a lot of spurious |
549 | 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 |
550 | notifications, so you need to use non-blocking I/O or other means to avoid |
409 | blocking when no data (or space) is available. |
551 | blocking when no data (or space) is available. |
|
|
552 | .Sp |
|
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553 | While this backend scales well, it requires one system call per active |
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554 | file descriptor per loop iteration. For small and medium numbers of file |
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555 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
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556 | might perform better. |
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557 | .Sp |
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558 | On the positive side, ignoring the spurious readyness notifications, this |
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559 | backend actually performed to specification in all tests and is fully |
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560 | embeddable, which is a rare feat among the OS-specific backends. |
410 | .ie n .IP """EVBACKEND_ALL""" 4 |
561 | .ie n .IP """EVBACKEND_ALL""" 4 |
411 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
562 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
412 | .IX Item "EVBACKEND_ALL" |
563 | .IX Item "EVBACKEND_ALL" |
413 | Try all backends (even potentially broken ones that wouldn't be tried |
564 | 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 |
565 | 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. |
566 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
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567 | .Sp |
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568 | It is definitely not recommended to use this flag. |
416 | .RE |
569 | .RE |
417 | .RS 4 |
570 | .RS 4 |
418 | .Sp |
571 | .Sp |
419 | If one or more of these are ored into the flags value, then only these |
572 | If one or more of these are ored into the flags value, then only these |
420 | backends will be tried (in the reverse order as given here). If none are |
573 | 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 |
574 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
422 | order of their flag values :) |
|
|
423 | .Sp |
575 | .Sp |
424 | The most typical usage is like this: |
576 | The most typical usage is like this: |
425 | .Sp |
577 | .Sp |
426 | .Vb 2 |
578 | .Vb 2 |
427 | \& if (!ev_default_loop (0)) |
579 | \& if (!ev_default_loop (0)) |
… | |
… | |
448 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
600 | 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 |
601 | 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 |
602 | 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). |
603 | undefined behaviour (or a failed assertion if assertions are enabled). |
452 | .Sp |
604 | .Sp |
|
|
605 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
606 | libev with threads is indeed to create one loop per thread, and using the |
|
|
607 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
608 | .Sp |
453 | Example: try to create a event loop that uses epoll and nothing else. |
609 | Example: Try to create a event loop that uses epoll and nothing else. |
454 | .Sp |
610 | .Sp |
455 | .Vb 3 |
611 | .Vb 3 |
456 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
612 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
457 | \& if (!epoller) |
613 | \& if (!epoller) |
458 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
614 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
… | |
… | |
462 | Destroys the default loop again (frees all memory and kernel state |
618 | 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 |
619 | 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 |
620 | 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 |
621 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
466 | calling this function, or cope with the fact afterwards (which is usually |
622 | 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 |
623 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
468 | for example). |
624 | for example). |
|
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625 | .Sp |
|
|
626 | Note that certain global state, such as signal state, will not be freed by |
|
|
627 | this function, and related watchers (such as signal and child watchers) |
|
|
628 | would need to be stopped manually. |
|
|
629 | .Sp |
|
|
630 | In general it is not advisable to call this function except in the |
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631 | rare occasion where you really need to free e.g. the signal handling |
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632 | pipe fds. If you need dynamically allocated loops it is better to use |
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633 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
469 | .IP "ev_loop_destroy (loop)" 4 |
634 | .IP "ev_loop_destroy (loop)" 4 |
470 | .IX Item "ev_loop_destroy (loop)" |
635 | .IX Item "ev_loop_destroy (loop)" |
471 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
636 | 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. |
637 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
473 | .IP "ev_default_fork ()" 4 |
638 | .IP "ev_default_fork ()" 4 |
474 | .IX Item "ev_default_fork ()" |
639 | .IX Item "ev_default_fork ()" |
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|
640 | 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 |
641 | 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 |
642 | 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 |
643 | the child process (or both child and parent, but that again makes little |
478 | again makes little sense). |
644 | sense). You \fImust\fR call it in the child before using any of the libev |
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|
645 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
479 | .Sp |
646 | .Sp |
480 | You \fImust\fR call this function in the child process after forking if and |
647 | 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 |
648 | 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. |
649 | you just fork+exec, you don't have to call it at all. |
483 | .Sp |
650 | .Sp |
484 | The function itself is quite fast and it's usually not a problem to call |
651 | 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 |
652 | 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: |
653 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
487 | .Sp |
654 | .Sp |
488 | .Vb 1 |
655 | .Vb 1 |
489 | \& pthread_atfork (0, 0, ev_default_fork); |
656 | \& pthread_atfork (0, 0, ev_default_fork); |
490 | .Ve |
657 | .Ve |
491 | .Sp |
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|
492 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
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|
493 | without calling this function, so if you force one of those backends you |
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|
494 | do not need to care. |
|
|
495 | .IP "ev_loop_fork (loop)" 4 |
658 | .IP "ev_loop_fork (loop)" 4 |
496 | .IX Item "ev_loop_fork (loop)" |
659 | .IX Item "ev_loop_fork (loop)" |
497 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
660 | 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 |
661 | \&\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. |
662 | after fork, and how you do this is entirely your own problem. |
|
|
663 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
664 | .IX Item "int ev_is_default_loop (loop)" |
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|
665 | Returns true when the given loop actually is the default loop, false otherwise. |
|
|
666 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
667 | .IX Item "unsigned int ev_loop_count (loop)" |
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|
668 | Returns the count of loop iterations for the loop, which is identical to |
|
|
669 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
670 | happily wraps around with enough iterations. |
|
|
671 | .Sp |
|
|
672 | This value can sometimes be useful as a generation counter of sorts (it |
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|
673 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
674 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
500 | .IP "unsigned int ev_backend (loop)" 4 |
675 | .IP "unsigned int ev_backend (loop)" 4 |
501 | .IX Item "unsigned int ev_backend (loop)" |
676 | .IX Item "unsigned int ev_backend (loop)" |
502 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
677 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
503 | use. |
678 | use. |
504 | .IP "ev_tstamp ev_now (loop)" 4 |
679 | .IP "ev_tstamp ev_now (loop)" 4 |
505 | .IX Item "ev_tstamp ev_now (loop)" |
680 | .IX Item "ev_tstamp ev_now (loop)" |
506 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
681 | 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 |
682 | 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 |
683 | 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 |
684 | 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). |
685 | event occurring (or more correctly, libev finding out about it). |
511 | .IP "ev_loop (loop, int flags)" 4 |
686 | .IP "ev_loop (loop, int flags)" 4 |
512 | .IX Item "ev_loop (loop, int flags)" |
687 | .IX Item "ev_loop (loop, int flags)" |
513 | Finally, this is it, the event handler. This function usually is called |
688 | 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 |
689 | after you initialised all your watchers and you want to start handling |
515 | events. |
690 | events. |
… | |
… | |
535 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
710 | libev watchers. 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. |
711 | usually a better approach for this kind of thing. |
537 | .Sp |
712 | .Sp |
538 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
713 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
539 | .Sp |
714 | .Sp |
540 | .Vb 18 |
715 | .Vb 10 |
541 | \& * If there are no active watchers (reference count is zero), return. |
716 | \& \- Before the first iteration, call any pending watchers. |
542 | \& - Queue prepare watchers and then call all outstanding watchers. |
717 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
718 | \& \- If a fork was detected, queue and call all fork watchers. |
|
|
719 | \& \- Queue and call all prepare watchers. |
543 | \& - If we have been forked, recreate the kernel state. |
720 | \& \- If we have been forked, recreate the kernel state. |
544 | \& - Update the kernel state with all outstanding changes. |
721 | \& \- Update the kernel state with all outstanding changes. |
545 | \& - Update the "event loop time". |
722 | \& \- Update the "event loop time". |
546 | \& - Calculate for how long to block. |
723 | \& \- Calculate for how long to sleep or block, if at all |
|
|
724 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
725 | \& any active watchers at all will result in not sleeping). |
|
|
726 | \& \- Sleep if the I/O and timer collect interval say so. |
547 | \& - Block the process, waiting for any events. |
727 | \& \- Block the process, waiting for any events. |
548 | \& - Queue all outstanding I/O (fd) events. |
728 | \& \- Queue all outstanding I/O (fd) events. |
549 | \& - Update the "event loop time" and do time jump handling. |
729 | \& \- Update the "event loop time" and do time jump handling. |
550 | \& - Queue all outstanding timers. |
730 | \& \- Queue all outstanding timers. |
551 | \& - Queue all outstanding periodics. |
731 | \& \- Queue all outstanding periodics. |
552 | \& - If no events are pending now, queue all idle watchers. |
732 | \& \- If no events are pending now, queue all idle watchers. |
553 | \& - Queue all check watchers. |
733 | \& \- Queue all check watchers. |
554 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
734 | \& \- 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 |
735 | \& Signals and child watchers are implemented as I/O watchers, and will |
556 | \& be handled here by queueing them when their watcher gets executed. |
736 | \& be handled here by queueing them when their watcher gets executed. |
557 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
737 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
558 | \& were used, return, otherwise continue with step *. |
738 | \& were used, or there are no active watchers, return, otherwise |
|
|
739 | \& continue with step *. |
559 | .Ve |
740 | .Ve |
560 | .Sp |
741 | .Sp |
561 | Example: queue some jobs and then loop until no events are outsanding |
742 | Example: Queue some jobs and then loop until no events are outstanding |
562 | anymore. |
743 | anymore. |
563 | .Sp |
744 | .Sp |
564 | .Vb 4 |
745 | .Vb 4 |
565 | \& ... queue jobs here, make sure they register event watchers as long |
746 | \& ... 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..) |
747 | \& ... as they still have work to do (even an idle watcher will do..) |
… | |
… | |
571 | .IX Item "ev_unloop (loop, how)" |
752 | .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 |
753 | 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 |
754 | 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 |
755 | \&\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. |
756 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
757 | .Sp |
|
|
758 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
576 | .IP "ev_ref (loop)" 4 |
759 | .IP "ev_ref (loop)" 4 |
577 | .IX Item "ev_ref (loop)" |
760 | .IX Item "ev_ref (loop)" |
578 | .PD 0 |
761 | .PD 0 |
579 | .IP "ev_unref (loop)" 4 |
762 | .IP "ev_unref (loop)" 4 |
580 | .IX Item "ev_unref (loop)" |
763 | .IX Item "ev_unref (loop)" |
… | |
… | |
586 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
769 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
587 | example, libev itself uses this for its internal signal pipe: It is not |
770 | example, libev itself uses this for its internal signal pipe: It is not |
588 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
771 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
589 | no event watchers registered by it are active. It is also an excellent |
772 | no event watchers registered by it are active. It is also an excellent |
590 | way to do this for generic recurring timers or from within third-party |
773 | way to do this for generic recurring timers or from within third-party |
591 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
774 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
775 | (but only if the watcher wasn't active before, or was active before, |
|
|
776 | respectively). |
592 | .Sp |
777 | .Sp |
593 | Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
778 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
594 | running when nothing else is active. |
779 | running when nothing else is active. |
595 | .Sp |
780 | .Sp |
596 | .Vb 4 |
781 | .Vb 4 |
597 | \& struct dv_signal exitsig; |
782 | \& struct ev_signal exitsig; |
598 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
783 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
599 | \& ev_signal_start (myloop, &exitsig); |
784 | \& ev_signal_start (loop, &exitsig); |
600 | \& evf_unref (myloop); |
785 | \& evf_unref (loop); |
601 | .Ve |
786 | .Ve |
602 | .Sp |
787 | .Sp |
603 | Example: for some weird reason, unregister the above signal handler again. |
788 | Example: For some weird reason, unregister the above signal handler again. |
604 | .Sp |
789 | .Sp |
605 | .Vb 2 |
790 | .Vb 2 |
606 | \& ev_ref (myloop); |
791 | \& ev_ref (loop); |
607 | \& ev_signal_stop (myloop, &exitsig); |
792 | \& ev_signal_stop (loop, &exitsig); |
608 | .Ve |
793 | .Ve |
|
|
794 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
795 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
796 | .PD 0 |
|
|
797 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
798 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
799 | .PD |
|
|
800 | These advanced functions influence the time that libev will spend waiting |
|
|
801 | for events. Both are by default \f(CW0\fR, meaning that libev will try to |
|
|
802 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
803 | .Sp |
|
|
804 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
805 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
806 | increase efficiency of loop iterations. |
|
|
807 | .Sp |
|
|
808 | The background is that sometimes your program runs just fast enough to |
|
|
809 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
810 | the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
811 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
812 | overhead for the actual polling but can deliver many events at once. |
|
|
813 | .Sp |
|
|
814 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
815 | time collecting I/O events, so you can handle more events per iteration, |
|
|
816 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
817 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
818 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
819 | .Sp |
|
|
820 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
821 | to spend more time collecting timeouts, at the expense of increased |
|
|
822 | latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
|
|
823 | will not be affected. Setting this to a non-null value will not introduce |
|
|
824 | any overhead in libev. |
|
|
825 | .Sp |
|
|
826 | Many (busy) programs can usually benefit by setting the io collect |
|
|
827 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
828 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
829 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
830 | as this approsaches the timing granularity of most systems. |
609 | .SH "ANATOMY OF A WATCHER" |
831 | .SH "ANATOMY OF A WATCHER" |
610 | .IX Header "ANATOMY OF A WATCHER" |
832 | .IX Header "ANATOMY OF A WATCHER" |
611 | A watcher is a structure that you create and register to record your |
833 | 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 |
834 | 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: |
835 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
616 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
838 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
617 | \& { |
839 | \& { |
618 | \& ev_io_stop (w); |
840 | \& ev_io_stop (w); |
619 | \& ev_unloop (loop, EVUNLOOP_ALL); |
841 | \& ev_unloop (loop, EVUNLOOP_ALL); |
620 | \& } |
842 | \& } |
621 | .Ve |
843 | \& |
622 | .PP |
|
|
623 | .Vb 6 |
|
|
624 | \& struct ev_loop *loop = ev_default_loop (0); |
844 | \& struct ev_loop *loop = ev_default_loop (0); |
625 | \& struct ev_io stdin_watcher; |
845 | \& struct ev_io stdin_watcher; |
626 | \& ev_init (&stdin_watcher, my_cb); |
846 | \& ev_init (&stdin_watcher, my_cb); |
627 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
847 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
628 | \& ev_io_start (loop, &stdin_watcher); |
848 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
684 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
904 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
685 | .ie n .IP """EV_CHILD""" 4 |
905 | .ie n .IP """EV_CHILD""" 4 |
686 | .el .IP "\f(CWEV_CHILD\fR" 4 |
906 | .el .IP "\f(CWEV_CHILD\fR" 4 |
687 | .IX Item "EV_CHILD" |
907 | .IX Item "EV_CHILD" |
688 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
908 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
|
|
909 | .ie n .IP """EV_STAT""" 4 |
|
|
910 | .el .IP "\f(CWEV_STAT\fR" 4 |
|
|
911 | .IX Item "EV_STAT" |
|
|
912 | The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow. |
689 | .ie n .IP """EV_IDLE""" 4 |
913 | .ie n .IP """EV_IDLE""" 4 |
690 | .el .IP "\f(CWEV_IDLE\fR" 4 |
914 | .el .IP "\f(CWEV_IDLE\fR" 4 |
691 | .IX Item "EV_IDLE" |
915 | .IX Item "EV_IDLE" |
692 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
916 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
693 | .ie n .IP """EV_PREPARE""" 4 |
917 | .ie n .IP """EV_PREPARE""" 4 |
… | |
… | |
703 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
927 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
704 | received events. Callbacks of both watcher types can start and stop as |
928 | received events. Callbacks of both watcher types can start and stop as |
705 | many watchers as they want, and all of them will be taken into account |
929 | many watchers as they want, and all of them will be taken into account |
706 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
930 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
707 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
931 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
|
|
932 | .ie n .IP """EV_EMBED""" 4 |
|
|
933 | .el .IP "\f(CWEV_EMBED\fR" 4 |
|
|
934 | .IX Item "EV_EMBED" |
|
|
935 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
|
|
936 | .ie n .IP """EV_FORK""" 4 |
|
|
937 | .el .IP "\f(CWEV_FORK\fR" 4 |
|
|
938 | .IX Item "EV_FORK" |
|
|
939 | The event loop has been resumed in the child process after fork (see |
|
|
940 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
941 | .ie n .IP """EV_ASYNC""" 4 |
|
|
942 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
943 | .IX Item "EV_ASYNC" |
|
|
944 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
708 | .ie n .IP """EV_ERROR""" 4 |
945 | .ie n .IP """EV_ERROR""" 4 |
709 | .el .IP "\f(CWEV_ERROR\fR" 4 |
946 | .el .IP "\f(CWEV_ERROR\fR" 4 |
710 | .IX Item "EV_ERROR" |
947 | .IX Item "EV_ERROR" |
711 | An unspecified error has occured, the watcher has been stopped. This might |
948 | An unspecified error has occured, the watcher has been stopped. This might |
712 | happen because the watcher could not be properly started because libev |
949 | happen because the watcher could not be properly started because libev |
… | |
… | |
777 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1014 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
778 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1015 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
779 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1016 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
780 | events but its callback has not yet been invoked). As long as a watcher |
1017 | events but its callback has not yet been invoked). As long as a watcher |
781 | is pending (but not active) you must not call an init function on it (but |
1018 | is pending (but not active) you must not call an init function on it (but |
782 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1019 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
783 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1020 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1021 | it). |
784 | .IP "callback = ev_cb (ev_TYPE *watcher)" 4 |
1022 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
785 | .IX Item "callback = ev_cb (ev_TYPE *watcher)" |
1023 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
786 | Returns the callback currently set on the watcher. |
1024 | Returns the callback currently set on the watcher. |
787 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1025 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
788 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1026 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
789 | Change the callback. You can change the callback at virtually any time |
1027 | Change the callback. You can change the callback at virtually any time |
790 | (modulo threads). |
1028 | (modulo threads). |
|
|
1029 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1030 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1031 | .PD 0 |
|
|
1032 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1033 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1034 | .PD |
|
|
1035 | Set and query the priority of the watcher. The priority is a small |
|
|
1036 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1037 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1038 | before watchers with lower priority, but priority will not keep watchers |
|
|
1039 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1040 | .Sp |
|
|
1041 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1042 | invocation after new events have been received. This is useful, for |
|
|
1043 | example, to reduce latency after idling, or more often, to bind two |
|
|
1044 | watchers on the same event and make sure one is called first. |
|
|
1045 | .Sp |
|
|
1046 | If you need to suppress invocation when higher priority events are pending |
|
|
1047 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1048 | .Sp |
|
|
1049 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1050 | pending. |
|
|
1051 | .Sp |
|
|
1052 | The default priority used by watchers when no priority has been set is |
|
|
1053 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1054 | .Sp |
|
|
1055 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1056 | fine, as long as you do not mind that the priority value you query might |
|
|
1057 | or might not have been adjusted to be within valid range. |
|
|
1058 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1059 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1060 | 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 |
|
|
1061 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1062 | can deal with that fact. |
|
|
1063 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1064 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1065 | If the watcher is pending, this function returns clears its pending status |
|
|
1066 | and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1067 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
791 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1068 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
792 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1069 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
793 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1070 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
794 | and read at any time, libev will completely ignore it. This can be used |
1071 | and read at any time, libev will completely ignore it. This can be used |
795 | to associate arbitrary data with your watcher. If you need more data and |
1072 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
816 | \& struct my_io *w = (struct my_io *)w_; |
1093 | \& struct my_io *w = (struct my_io *)w_; |
817 | \& ... |
1094 | \& ... |
818 | \& } |
1095 | \& } |
819 | .Ve |
1096 | .Ve |
820 | .PP |
1097 | .PP |
821 | More interesting and less C\-conformant ways of catsing your callback type |
1098 | More interesting and less C\-conformant ways of casting your callback type |
822 | have been omitted.... |
1099 | instead have been omitted. |
|
|
1100 | .PP |
|
|
1101 | Another common scenario is having some data structure with multiple |
|
|
1102 | watchers: |
|
|
1103 | .PP |
|
|
1104 | .Vb 6 |
|
|
1105 | \& struct my_biggy |
|
|
1106 | \& { |
|
|
1107 | \& int some_data; |
|
|
1108 | \& ev_timer t1; |
|
|
1109 | \& ev_timer t2; |
|
|
1110 | \& } |
|
|
1111 | .Ve |
|
|
1112 | .PP |
|
|
1113 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
|
|
1114 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
|
|
1115 | .PP |
|
|
1116 | .Vb 1 |
|
|
1117 | \& #include <stddef.h> |
|
|
1118 | \& |
|
|
1119 | \& static void |
|
|
1120 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
1121 | \& { |
|
|
1122 | \& struct my_biggy big = (struct my_biggy * |
|
|
1123 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1124 | \& } |
|
|
1125 | \& |
|
|
1126 | \& static void |
|
|
1127 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
1128 | \& { |
|
|
1129 | \& struct my_biggy big = (struct my_biggy * |
|
|
1130 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1131 | \& } |
|
|
1132 | .Ve |
823 | .SH "WATCHER TYPES" |
1133 | .SH "WATCHER TYPES" |
824 | .IX Header "WATCHER TYPES" |
1134 | .IX Header "WATCHER TYPES" |
825 | This section describes each watcher in detail, but will not repeat |
1135 | This section describes each watcher in detail, but will not repeat |
826 | information given in the last section. |
1136 | information given in the last section. Any initialisation/set macros, |
|
|
1137 | functions and members specific to the watcher type are explained. |
|
|
1138 | .PP |
|
|
1139 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
|
|
1140 | while the watcher is active, you can look at the member and expect some |
|
|
1141 | sensible content, but you must not modify it (you can modify it while the |
|
|
1142 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
|
|
1143 | means you can expect it to have some sensible content while the watcher |
|
|
1144 | is active, but you can also modify it. Modifying it may not do something |
|
|
1145 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
1146 | not crash or malfunction in any way. |
827 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1147 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
828 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1148 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
829 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1149 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
830 | I/O watchers check whether a file descriptor is readable or writable |
1150 | I/O watchers check whether a file descriptor is readable or writable |
831 | in each iteration of the event loop, or, more precisely, when reading |
1151 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
838 | In general you can register as many read and/or write event watchers per |
1158 | In general you can register as many read and/or write event watchers per |
839 | fd as you want (as long as you don't confuse yourself). Setting all file |
1159 | fd as you want (as long as you don't confuse yourself). Setting all file |
840 | descriptors to non-blocking mode is also usually a good idea (but not |
1160 | descriptors to non-blocking mode is also usually a good idea (but not |
841 | required if you know what you are doing). |
1161 | required if you know what you are doing). |
842 | .PP |
1162 | .PP |
843 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
844 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
845 | descriptors correctly if you register interest in two or more fds pointing |
|
|
846 | to the same underlying file/socket/etc. description (that is, they share |
|
|
847 | the same underlying \*(L"file open\*(R"). |
|
|
848 | .PP |
|
|
849 | If you must do this, then force the use of a known-to-be-good backend |
1163 | If you must do this, then force the use of a known-to-be-good backend |
850 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1164 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
851 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1165 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
852 | .PP |
1166 | .PP |
853 | Another thing you have to watch out for is that it is quite easy to |
1167 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
859 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1173 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
860 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1174 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
861 | .PP |
1175 | .PP |
862 | If you cannot run the fd in non-blocking mode (for example you should not |
1176 | If you cannot run the fd in non-blocking mode (for example you should not |
863 | play around with an Xlib connection), then you have to seperately re-test |
1177 | play around with an Xlib connection), then you have to seperately re-test |
864 | wether a file descriptor is really ready with a known-to-be good interface |
1178 | whether a file descriptor is really ready with a known-to-be good interface |
865 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1179 | such as poll (fortunately in our Xlib example, Xlib already does this on |
866 | its own, so its quite safe to use). |
1180 | its own, so its quite safe to use). |
|
|
1181 | .PP |
|
|
1182 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1183 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1184 | .PP |
|
|
1185 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1186 | descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means, |
|
|
1187 | such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file |
|
|
1188 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1189 | this interest. If another file descriptor with the same number then is |
|
|
1190 | registered with libev, there is no efficient way to see that this is, in |
|
|
1191 | fact, a different file descriptor. |
|
|
1192 | .PP |
|
|
1193 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1194 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1195 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1196 | it is assumed that the file descriptor stays the same. That means that |
|
|
1197 | 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 |
|
|
1198 | descriptor even if the file descriptor number itself did not change. |
|
|
1199 | .PP |
|
|
1200 | This is how one would do it normally anyway, the important point is that |
|
|
1201 | the libev application should not optimise around libev but should leave |
|
|
1202 | optimisations to libev. |
|
|
1203 | .PP |
|
|
1204 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1205 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1206 | .PP |
|
|
1207 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1208 | but only events for the underlying file descriptions. That means when you |
|
|
1209 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1210 | events for them, only one file descriptor might actually receive events. |
|
|
1211 | .PP |
|
|
1212 | There is no workaround possible except not registering events |
|
|
1213 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1214 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1215 | .PP |
|
|
1216 | \fIThe special problem of fork\fR |
|
|
1217 | .IX Subsection "The special problem of fork" |
|
|
1218 | .PP |
|
|
1219 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1220 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1221 | it in the child. |
|
|
1222 | .PP |
|
|
1223 | To support fork in your programs, you either have to call |
|
|
1224 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1225 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1226 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1227 | .PP |
|
|
1228 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1229 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1230 | .PP |
|
|
1231 | While not really specific to libev, it is easy to forget about \s-1SIGPIPE:\s0 |
|
|
1232 | when reading from a pipe whose other end has been closed, your program |
|
|
1233 | gets send a \s-1SIGPIPE\s0, which, by default, aborts your program. For most |
|
|
1234 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1235 | undesirable. |
|
|
1236 | .PP |
|
|
1237 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1238 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1239 | somewhere, as that would have given you a big clue). |
|
|
1240 | .PP |
|
|
1241 | \fIWatcher-Specific Functions\fR |
|
|
1242 | .IX Subsection "Watcher-Specific Functions" |
867 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1243 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
868 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1244 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
869 | .PD 0 |
1245 | .PD 0 |
870 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1246 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
871 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1247 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
872 | .PD |
1248 | .PD |
873 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1249 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
874 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1250 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
875 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
1251 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
|
|
1252 | .IP "int fd [read\-only]" 4 |
|
|
1253 | .IX Item "int fd [read-only]" |
|
|
1254 | The file descriptor being watched. |
|
|
1255 | .IP "int events [read\-only]" 4 |
|
|
1256 | .IX Item "int events [read-only]" |
|
|
1257 | The events being watched. |
876 | .PP |
1258 | .PP |
|
|
1259 | \fIExamples\fR |
|
|
1260 | .IX Subsection "Examples" |
|
|
1261 | .PP |
877 | Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1262 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
878 | readable, but only once. Since it is likely line\-buffered, you could |
1263 | readable, but only once. Since it is likely line-buffered, you could |
879 | attempt to read a whole line in the callback: |
1264 | attempt to read a whole line in the callback. |
880 | .PP |
1265 | .PP |
881 | .Vb 6 |
1266 | .Vb 6 |
882 | \& static void |
1267 | \& static void |
883 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1268 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
884 | \& { |
1269 | \& { |
885 | \& ev_io_stop (loop, w); |
1270 | \& ev_io_stop (loop, w); |
886 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1271 | \& .. read from stdin here (or from w\->fd) and haqndle any I/O errors |
887 | \& } |
1272 | \& } |
888 | .Ve |
1273 | \& |
889 | .PP |
|
|
890 | .Vb 6 |
|
|
891 | \& ... |
1274 | \& ... |
892 | \& struct ev_loop *loop = ev_default_init (0); |
1275 | \& struct ev_loop *loop = ev_default_init (0); |
893 | \& struct ev_io stdin_readable; |
1276 | \& struct ev_io stdin_readable; |
894 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1277 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
895 | \& ev_io_start (loop, &stdin_readable); |
1278 | \& ev_io_start (loop, &stdin_readable); |
… | |
… | |
912 | of the event triggering whatever timeout you are modifying/starting. If |
1295 | of the event triggering whatever timeout you are modifying/starting. If |
913 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1296 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
914 | on the current time, use something like this to adjust for this: |
1297 | on the current time, use something like this to adjust for this: |
915 | .PP |
1298 | .PP |
916 | .Vb 1 |
1299 | .Vb 1 |
917 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1300 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
918 | .Ve |
1301 | .Ve |
919 | .PP |
1302 | .PP |
920 | The callback is guarenteed to be invoked only when its timeout has passed, |
1303 | The callback is guarenteed to be invoked only when its timeout has passed, |
921 | but if multiple timers become ready during the same loop iteration then |
1304 | but if multiple timers become ready during the same loop iteration then |
922 | order of execution is undefined. |
1305 | order of execution is undefined. |
|
|
1306 | .PP |
|
|
1307 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1308 | .IX Subsection "Watcher-Specific Functions and Data Members" |
923 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1309 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
924 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1310 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
925 | .PD 0 |
1311 | .PD 0 |
926 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1312 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
927 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1313 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
934 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1320 | The timer itself will do a best-effort at avoiding drift, that is, if you |
935 | configure a timer to trigger every 10 seconds, then it will trigger at |
1321 | configure a timer to trigger every 10 seconds, then it will trigger at |
936 | exactly 10 second intervals. If, however, your program cannot keep up with |
1322 | exactly 10 second intervals. If, however, your program cannot keep up with |
937 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1323 | the timer (because it takes longer than those 10 seconds to do stuff) the |
938 | timer will not fire more than once per event loop iteration. |
1324 | timer will not fire more than once per event loop iteration. |
939 | .IP "ev_timer_again (loop)" 4 |
1325 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
940 | .IX Item "ev_timer_again (loop)" |
1326 | .IX Item "ev_timer_again (loop, ev_timer *)" |
941 | This will act as if the timer timed out and restart it again if it is |
1327 | This will act as if the timer timed out and restart it again if it is |
942 | repeating. The exact semantics are: |
1328 | repeating. The exact semantics are: |
943 | .Sp |
1329 | .Sp |
|
|
1330 | If the timer is pending, its pending status is cleared. |
|
|
1331 | .Sp |
944 | If the timer is started but nonrepeating, stop it. |
1332 | If the timer is started but nonrepeating, stop it (as if it timed out). |
945 | .Sp |
1333 | .Sp |
946 | If the timer is repeating, either start it if necessary (with the repeat |
1334 | If the timer is repeating, either start it if necessary (with the |
947 | value), or reset the running timer to the repeat value. |
1335 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
948 | .Sp |
1336 | .Sp |
949 | This sounds a bit complicated, but here is a useful and typical |
1337 | This sounds a bit complicated, but here is a useful and typical |
950 | example: Imagine you have a tcp connection and you want a so-called idle |
1338 | example: Imagine you have a tcp connection and you want a so-called idle |
951 | timeout, that is, you want to be called when there have been, say, 60 |
1339 | timeout, that is, you want to be called when there have been, say, 60 |
952 | seconds of inactivity on the socket. The easiest way to do this is to |
1340 | seconds of inactivity on the socket. The easiest way to do this is to |
953 | configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each |
1341 | configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call |
954 | time you successfully read or write some data. If you go into an idle |
1342 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
955 | state where you do not expect data to travel on the socket, you can stop |
1343 | you go into an idle state where you do not expect data to travel on the |
956 | the timer, and again will automatically restart it if need be. |
1344 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
|
|
1345 | automatically restart it if need be. |
|
|
1346 | .Sp |
|
|
1347 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
|
|
1348 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
|
|
1349 | .Sp |
|
|
1350 | .Vb 8 |
|
|
1351 | \& ev_timer_init (timer, callback, 0., 5.); |
|
|
1352 | \& ev_timer_again (loop, timer); |
|
|
1353 | \& ... |
|
|
1354 | \& timer\->again = 17.; |
|
|
1355 | \& ev_timer_again (loop, timer); |
|
|
1356 | \& ... |
|
|
1357 | \& timer\->again = 10.; |
|
|
1358 | \& ev_timer_again (loop, timer); |
|
|
1359 | .Ve |
|
|
1360 | .Sp |
|
|
1361 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1362 | you want to modify its timeout value. |
|
|
1363 | .IP "ev_tstamp repeat [read\-write]" 4 |
|
|
1364 | .IX Item "ev_tstamp repeat [read-write]" |
|
|
1365 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
|
|
1366 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
|
|
1367 | which is also when any modifications are taken into account. |
957 | .PP |
1368 | .PP |
|
|
1369 | \fIExamples\fR |
|
|
1370 | .IX Subsection "Examples" |
|
|
1371 | .PP |
958 | Example: create a timer that fires after 60 seconds. |
1372 | Example: Create a timer that fires after 60 seconds. |
959 | .PP |
1373 | .PP |
960 | .Vb 5 |
1374 | .Vb 5 |
961 | \& static void |
1375 | \& static void |
962 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1376 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
963 | \& { |
1377 | \& { |
964 | \& .. one minute over, w is actually stopped right here |
1378 | \& .. one minute over, w is actually stopped right here |
965 | \& } |
1379 | \& } |
966 | .Ve |
1380 | \& |
967 | .PP |
|
|
968 | .Vb 3 |
|
|
969 | \& struct ev_timer mytimer; |
1381 | \& struct ev_timer mytimer; |
970 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1382 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
971 | \& ev_timer_start (loop, &mytimer); |
1383 | \& ev_timer_start (loop, &mytimer); |
972 | .Ve |
1384 | .Ve |
973 | .PP |
1385 | .PP |
974 | Example: create a timeout timer that times out after 10 seconds of |
1386 | Example: Create a timeout timer that times out after 10 seconds of |
975 | inactivity. |
1387 | inactivity. |
976 | .PP |
1388 | .PP |
977 | .Vb 5 |
1389 | .Vb 5 |
978 | \& static void |
1390 | \& static void |
979 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1391 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
980 | \& { |
1392 | \& { |
981 | \& .. ten seconds without any activity |
1393 | \& .. ten seconds without any activity |
982 | \& } |
1394 | \& } |
983 | .Ve |
1395 | \& |
984 | .PP |
|
|
985 | .Vb 4 |
|
|
986 | \& struct ev_timer mytimer; |
1396 | \& struct ev_timer mytimer; |
987 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1397 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
988 | \& ev_timer_again (&mytimer); /* start timer */ |
1398 | \& ev_timer_again (&mytimer); /* start timer */ |
989 | \& ev_loop (loop, 0); |
1399 | \& ev_loop (loop, 0); |
990 | .Ve |
1400 | \& |
991 | .PP |
|
|
992 | .Vb 3 |
|
|
993 | \& // and in some piece of code that gets executed on any "activity": |
1401 | \& // and in some piece of code that gets executed on any "activity": |
994 | \& // reset the timeout to start ticking again at 10 seconds |
1402 | \& // reset the timeout to start ticking again at 10 seconds |
995 | \& ev_timer_again (&mytimer); |
1403 | \& ev_timer_again (&mytimer); |
996 | .Ve |
1404 | .Ve |
997 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1405 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
… | |
… | |
1004 | but on wallclock time (absolute time). You can tell a periodic watcher |
1412 | but on wallclock time (absolute time). You can tell a periodic watcher |
1005 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1413 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1006 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1414 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1007 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1415 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1008 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1416 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1009 | roughly 10 seconds later and of course not if you reset your system time |
1417 | roughly 10 seconds later). |
1010 | again). |
|
|
1011 | .PP |
1418 | .PP |
1012 | They can also be used to implement vastly more complex timers, such as |
1419 | They can also be used to implement vastly more complex timers, such as |
1013 | triggering an event on eahc midnight, local time. |
1420 | triggering an event on each midnight, local time or other, complicated, |
|
|
1421 | rules. |
1014 | .PP |
1422 | .PP |
1015 | As with timers, the callback is guarenteed to be invoked only when the |
1423 | As with timers, the callback is guarenteed to be invoked only when the |
1016 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1424 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1017 | during the same loop iteration then order of execution is undefined. |
1425 | during the same loop iteration then order of execution is undefined. |
|
|
1426 | .PP |
|
|
1427 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1428 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1018 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1429 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1019 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1430 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1020 | .PD 0 |
1431 | .PD 0 |
1021 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1432 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1022 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1433 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1023 | .PD |
1434 | .PD |
1024 | Lots of arguments, lets sort it out... There are basically three modes of |
1435 | Lots of arguments, lets sort it out... There are basically three modes of |
1025 | operation, and we will explain them from simplest to complex: |
1436 | operation, and we will explain them from simplest to complex: |
1026 | .RS 4 |
1437 | .RS 4 |
|
|
1438 | .IP "\(bu" 4 |
1027 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1439 | absolute timer (at = time, interval = reschedule_cb = 0) |
1028 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1440 | .Sp |
1029 | In this configuration the watcher triggers an event at the wallclock time |
1441 | In this configuration the watcher triggers an event at the wallclock time |
1030 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1442 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1031 | that is, if it is to be run at January 1st 2011 then it will run when the |
1443 | that is, if it is to be run at January 1st 2011 then it will run when the |
1032 | system time reaches or surpasses this time. |
1444 | system time reaches or surpasses this time. |
|
|
1445 | .IP "\(bu" 4 |
1033 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1446 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1034 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1447 | .Sp |
1035 | In this mode the watcher will always be scheduled to time out at the next |
1448 | In this mode the watcher will always be scheduled to time out at the next |
1036 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1449 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1037 | of any time jumps. |
1450 | and then repeat, regardless of any time jumps. |
1038 | .Sp |
1451 | .Sp |
1039 | This can be used to create timers that do not drift with respect to system |
1452 | This can be used to create timers that do not drift with respect to system |
1040 | time: |
1453 | time: |
1041 | .Sp |
1454 | .Sp |
1042 | .Vb 1 |
1455 | .Vb 1 |
… | |
… | |
1049 | by 3600. |
1462 | by 3600. |
1050 | .Sp |
1463 | .Sp |
1051 | Another way to think about it (for the mathematically inclined) is that |
1464 | Another way to think about it (for the mathematically inclined) is that |
1052 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1465 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1053 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1466 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1054 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1467 | .Sp |
1055 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1468 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1469 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1470 | this value. |
|
|
1471 | .IP "\(bu" 4 |
|
|
1472 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
|
|
1473 | .Sp |
1056 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1474 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1057 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1475 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1058 | reschedule callback will be called with the watcher as first, and the |
1476 | reschedule callback will be called with the watcher as first, and the |
1059 | current time as second argument. |
1477 | current time as second argument. |
1060 | .Sp |
1478 | .Sp |
1061 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1479 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1062 | ever, or make any event loop modifications\fR. If you need to stop it, |
1480 | ever, or make any event loop modifications\fR. If you need to stop it, |
1063 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1481 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1064 | starting a prepare watcher). |
1482 | starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). |
1065 | .Sp |
1483 | .Sp |
1066 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1484 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1067 | ev_tstamp now)\*(C'\fR, e.g.: |
1485 | ev_tstamp now)\*(C'\fR, e.g.: |
1068 | .Sp |
1486 | .Sp |
1069 | .Vb 4 |
1487 | .Vb 4 |
… | |
… | |
1093 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1511 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1094 | Simply stops and restarts the periodic watcher again. This is only useful |
1512 | Simply stops and restarts the periodic watcher again. This is only useful |
1095 | when you changed some parameters or the reschedule callback would return |
1513 | when you changed some parameters or the reschedule callback would return |
1096 | a different time than the last time it was called (e.g. in a crond like |
1514 | a different time than the last time it was called (e.g. in a crond like |
1097 | program when the crontabs have changed). |
1515 | program when the crontabs have changed). |
|
|
1516 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
1517 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
1518 | When active, returns the absolute time that the watcher is supposed to |
|
|
1519 | trigger next. |
|
|
1520 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1521 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1522 | When repeating, this contains the offset value, otherwise this is the |
|
|
1523 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1524 | .Sp |
|
|
1525 | Can be modified any time, but changes only take effect when the periodic |
|
|
1526 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1527 | .IP "ev_tstamp interval [read\-write]" 4 |
|
|
1528 | .IX Item "ev_tstamp interval [read-write]" |
|
|
1529 | The current interval value. Can be modified any time, but changes only |
|
|
1530 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
|
|
1531 | called. |
|
|
1532 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
|
|
1533 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
|
|
1534 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
|
|
1535 | switched off. Can be changed any time, but changes only take effect when |
|
|
1536 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1098 | .PP |
1537 | .PP |
|
|
1538 | \fIExamples\fR |
|
|
1539 | .IX Subsection "Examples" |
|
|
1540 | .PP |
1099 | Example: call a callback every hour, or, more precisely, whenever the |
1541 | Example: Call a callback every hour, or, more precisely, whenever the |
1100 | system clock is divisible by 3600. The callback invocation times have |
1542 | system clock is divisible by 3600. The callback invocation times have |
1101 | potentially a lot of jittering, but good long-term stability. |
1543 | potentially a lot of jittering, but good long-term stability. |
1102 | .PP |
1544 | .PP |
1103 | .Vb 5 |
1545 | .Vb 5 |
1104 | \& static void |
1546 | \& static void |
1105 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1547 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1106 | \& { |
1548 | \& { |
1107 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1549 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1108 | \& } |
1550 | \& } |
1109 | .Ve |
1551 | \& |
1110 | .PP |
|
|
1111 | .Vb 3 |
|
|
1112 | \& struct ev_periodic hourly_tick; |
1552 | \& struct ev_periodic hourly_tick; |
1113 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1553 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1114 | \& ev_periodic_start (loop, &hourly_tick); |
1554 | \& ev_periodic_start (loop, &hourly_tick); |
1115 | .Ve |
1555 | .Ve |
1116 | .PP |
1556 | .PP |
1117 | Example: the same as above, but use a reschedule callback to do it: |
1557 | Example: The same as above, but use a reschedule callback to do it: |
1118 | .PP |
1558 | .PP |
1119 | .Vb 1 |
1559 | .Vb 1 |
1120 | \& #include <math.h> |
1560 | \& #include <math.h> |
1121 | .Ve |
1561 | \& |
1122 | .PP |
|
|
1123 | .Vb 5 |
|
|
1124 | \& static ev_tstamp |
1562 | \& static ev_tstamp |
1125 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1563 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1126 | \& { |
1564 | \& { |
1127 | \& return fmod (now, 3600.) + 3600.; |
1565 | \& return fmod (now, 3600.) + 3600.; |
1128 | \& } |
1566 | \& } |
1129 | .Ve |
1567 | \& |
1130 | .PP |
|
|
1131 | .Vb 1 |
|
|
1132 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1568 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1133 | .Ve |
1569 | .Ve |
1134 | .PP |
1570 | .PP |
1135 | Example: call a callback every hour, starting now: |
1571 | Example: Call a callback every hour, starting now: |
1136 | .PP |
1572 | .PP |
1137 | .Vb 4 |
1573 | .Vb 4 |
1138 | \& struct ev_periodic hourly_tick; |
1574 | \& struct ev_periodic hourly_tick; |
1139 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1575 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1140 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1576 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
… | |
… | |
1152 | first watcher gets started will libev actually register a signal watcher |
1588 | first watcher gets started will libev actually register a signal watcher |
1153 | with the kernel (thus it coexists with your own signal handlers as long |
1589 | with the kernel (thus it coexists with your own signal handlers as long |
1154 | as you don't register any with libev). Similarly, when the last signal |
1590 | as you don't register any with libev). Similarly, when the last signal |
1155 | watcher for a signal is stopped libev will reset the signal handler to |
1591 | watcher for a signal is stopped libev will reset the signal handler to |
1156 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1592 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1593 | .PP |
|
|
1594 | If possible and supported, libev will install its handlers with |
|
|
1595 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly |
|
|
1596 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1597 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1598 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
1599 | .PP |
|
|
1600 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1601 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1157 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1602 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1158 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1603 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1159 | .PD 0 |
1604 | .PD 0 |
1160 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1605 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1161 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1606 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1162 | .PD |
1607 | .PD |
1163 | Configures the watcher to trigger on the given signal number (usually one |
1608 | Configures the watcher to trigger on the given signal number (usually one |
1164 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1609 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
|
|
1610 | .IP "int signum [read\-only]" 4 |
|
|
1611 | .IX Item "int signum [read-only]" |
|
|
1612 | The signal the watcher watches out for. |
|
|
1613 | .PP |
|
|
1614 | \fIExamples\fR |
|
|
1615 | .IX Subsection "Examples" |
|
|
1616 | .PP |
|
|
1617 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1618 | .PP |
|
|
1619 | .Vb 5 |
|
|
1620 | \& static void |
|
|
1621 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1622 | \& { |
|
|
1623 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1624 | \& } |
|
|
1625 | \& |
|
|
1626 | \& struct ev_signal signal_watcher; |
|
|
1627 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1628 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1629 | .Ve |
1165 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1630 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1166 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1631 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1167 | .IX Subsection "ev_child - watch out for process status changes" |
1632 | .IX Subsection "ev_child - watch out for process status changes" |
1168 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1633 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1169 | some child status changes (most typically when a child of yours dies). |
1634 | some child status changes (most typically when a child of yours dies). It |
|
|
1635 | is permissible to install a child watcher \fIafter\fR the child has been |
|
|
1636 | forked (which implies it might have already exited), as long as the event |
|
|
1637 | loop isn't entered (or is continued from a watcher). |
|
|
1638 | .PP |
|
|
1639 | Only the default event loop is capable of handling signals, and therefore |
|
|
1640 | you can only rgeister child watchers in the default event loop. |
|
|
1641 | .PP |
|
|
1642 | \fIProcess Interaction\fR |
|
|
1643 | .IX Subsection "Process Interaction" |
|
|
1644 | .PP |
|
|
1645 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1646 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1647 | the first child watcher is started after the child exits. The occurance |
|
|
1648 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1649 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1650 | children, even ones not watched. |
|
|
1651 | .PP |
|
|
1652 | \fIOverriding the Built-In Processing\fR |
|
|
1653 | .IX Subsection "Overriding the Built-In Processing" |
|
|
1654 | .PP |
|
|
1655 | Libev offers no special support for overriding the built-in child |
|
|
1656 | processing, but if your application collides with libev's default child |
|
|
1657 | handler, you can override it easily by installing your own handler for |
|
|
1658 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
1659 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1660 | event-based approach to child reaping and thus use libev's support for |
|
|
1661 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
1662 | .PP |
|
|
1663 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1664 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1170 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1665 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1171 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1666 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1172 | .PD 0 |
1667 | .PD 0 |
1173 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1668 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1174 | .IX Item "ev_child_set (ev_child *, int pid)" |
1669 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1175 | .PD |
1670 | .PD |
1176 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1671 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1177 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1672 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1178 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1673 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1179 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1674 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1180 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1675 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1181 | process causing the status change. |
1676 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
1677 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
1678 | activate the watcher when the process is stopped or continued). |
|
|
1679 | .IP "int pid [read\-only]" 4 |
|
|
1680 | .IX Item "int pid [read-only]" |
|
|
1681 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
|
|
1682 | .IP "int rpid [read\-write]" 4 |
|
|
1683 | .IX Item "int rpid [read-write]" |
|
|
1684 | The process id that detected a status change. |
|
|
1685 | .IP "int rstatus [read\-write]" 4 |
|
|
1686 | .IX Item "int rstatus [read-write]" |
|
|
1687 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
|
|
1688 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1182 | .PP |
1689 | .PP |
1183 | Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
1690 | \fIExamples\fR |
|
|
1691 | .IX Subsection "Examples" |
1184 | .PP |
1692 | .PP |
|
|
1693 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
1694 | its completion. |
|
|
1695 | .PP |
1185 | .Vb 5 |
1696 | .Vb 1 |
|
|
1697 | \& ev_child cw; |
|
|
1698 | \& |
1186 | \& static void |
1699 | \& static void |
1187 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1700 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
1188 | \& { |
1701 | \& { |
1189 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1702 | \& ev_child_stop (EV_A_ w); |
|
|
1703 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1190 | \& } |
1704 | \& } |
|
|
1705 | \& |
|
|
1706 | \& pid_t pid = fork (); |
|
|
1707 | \& |
|
|
1708 | \& if (pid < 0) |
|
|
1709 | \& // error |
|
|
1710 | \& else if (pid == 0) |
|
|
1711 | \& { |
|
|
1712 | \& // the forked child executes here |
|
|
1713 | \& exit (1); |
|
|
1714 | \& } |
|
|
1715 | \& else |
|
|
1716 | \& { |
|
|
1717 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
1718 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
1719 | \& } |
1191 | .Ve |
1720 | .Ve |
|
|
1721 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
|
|
1722 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
|
|
1723 | .IX Subsection "ev_stat - did the file attributes just change?" |
|
|
1724 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1725 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
|
|
1726 | compared to the last time, invoking the callback if it did. |
1192 | .PP |
1727 | .PP |
|
|
1728 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
|
|
1729 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
|
|
1730 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
|
|
1731 | otherwise always forced to be at least one) and all the other fields of |
|
|
1732 | the stat buffer having unspecified contents. |
|
|
1733 | .PP |
|
|
1734 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
|
|
1735 | relative and your working directory changes, the behaviour is undefined. |
|
|
1736 | .PP |
|
|
1737 | Since there is no standard to do this, the portable implementation simply |
|
|
1738 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
|
|
1739 | can specify a recommended polling interval for this case. If you specify |
|
|
1740 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
|
|
1741 | unspecified default\fR value will be used (which you can expect to be around |
|
|
1742 | five seconds, although this might change dynamically). Libev will also |
|
|
1743 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
|
|
1744 | usually overkill. |
|
|
1745 | .PP |
|
|
1746 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1747 | as even with OS-supported change notifications, this can be |
|
|
1748 | resource-intensive. |
|
|
1749 | .PP |
|
|
1750 | At the time of this writing, only the Linux inotify interface is |
|
|
1751 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1752 | reader, note, however, that the author sees no way of implementing ev_stat |
|
|
1753 | semantics with kqueue). Inotify will be used to give hints only and should |
|
|
1754 | not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev |
|
|
1755 | sometimes needs to fall back to regular polling again even with inotify, |
|
|
1756 | but changes are usually detected immediately, and if the file exists there |
|
|
1757 | will be no polling. |
|
|
1758 | .PP |
|
|
1759 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
1760 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
1761 | .PP |
|
|
1762 | Libev by default (unless the user overrides this) uses the default |
|
|
1763 | compilation environment, which means that on systems with optionally |
|
|
1764 | disabled large file support, you get the 32 bit version of the stat |
|
|
1765 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
1766 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1767 | compile libev with the same flags to get binary compatibility. This is |
|
|
1768 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
1769 | most noticably with ev_stat and largefile support. |
|
|
1770 | .PP |
|
|
1771 | \fIInotify\fR |
|
|
1772 | .IX Subsection "Inotify" |
|
|
1773 | .PP |
|
|
1774 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1775 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1776 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1777 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1778 | .PP |
|
|
1779 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1780 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1781 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
1782 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1783 | .PP |
|
|
1784 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1785 | implement this functionality, due to the requirement of having a file |
|
|
1786 | descriptor open on the object at all times). |
|
|
1787 | .PP |
|
|
1788 | \fIThe special problem of stat time resolution\fR |
|
|
1789 | .IX Subsection "The special problem of stat time resolution" |
|
|
1790 | .PP |
|
|
1791 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1792 | even on systems where the resolution is higher, many filesystems still |
|
|
1793 | only support whole seconds. |
|
|
1794 | .PP |
|
|
1795 | That means that, if the time is the only thing that changes, you can |
|
|
1796 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
1797 | calls your callback, which does something. When there is another update |
|
|
1798 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it as the stat |
|
|
1799 | data does not change. |
|
|
1800 | .PP |
|
|
1801 | The solution to this is to delay acting on a change for slightly more |
|
|
1802 | than second (or till slightly after the next full second boundary), using |
|
|
1803 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
1804 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
1805 | .PP |
|
|
1806 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
1807 | of some operating systems (where the second counter of the current time |
|
|
1808 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1809 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
1810 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
1811 | update file times then there will be a small window where the kernel uses |
|
|
1812 | the previous second to update file times but libev might already execute |
|
|
1813 | the timer callback). |
|
|
1814 | .PP |
|
|
1815 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1816 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
1817 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
|
|
1818 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
|
|
1819 | .PD 0 |
|
|
1820 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
|
|
1821 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
|
|
1822 | .PD |
|
|
1823 | Configures the watcher to wait for status changes of the given |
|
|
1824 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
|
|
1825 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
|
|
1826 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
|
|
1827 | path for as long as the watcher is active. |
|
|
1828 | .Sp |
|
|
1829 | The callback will receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, relative |
|
|
1830 | to the attributes at the time the watcher was started (or the last change |
|
|
1831 | was detected). |
|
|
1832 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
|
|
1833 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
|
|
1834 | Updates the stat buffer immediately with new values. If you change the |
|
|
1835 | watched path in your callback, you could call this function to avoid |
|
|
1836 | detecting this change (while introducing a race condition if you are not |
|
|
1837 | the only one changing the path). Can also be useful simply to find out the |
|
|
1838 | new values. |
|
|
1839 | .IP "ev_statdata attr [read\-only]" 4 |
|
|
1840 | .IX Item "ev_statdata attr [read-only]" |
|
|
1841 | The most-recently detected attributes of the file. Although the type is |
|
|
1842 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
1843 | suitable for your system, but you can only rely on the POSIX-standardised |
|
|
1844 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
|
|
1845 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
|
|
1846 | .IP "ev_statdata prev [read\-only]" 4 |
|
|
1847 | .IX Item "ev_statdata prev [read-only]" |
|
|
1848 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1849 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
1850 | 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, |
|
|
1851 | \&\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. |
|
|
1852 | .IP "ev_tstamp interval [read\-only]" 4 |
|
|
1853 | .IX Item "ev_tstamp interval [read-only]" |
|
|
1854 | The specified interval. |
|
|
1855 | .IP "const char *path [read\-only]" 4 |
|
|
1856 | .IX Item "const char *path [read-only]" |
|
|
1857 | The filesystem path that is being watched. |
|
|
1858 | .PP |
|
|
1859 | \fIExamples\fR |
|
|
1860 | .IX Subsection "Examples" |
|
|
1861 | .PP |
|
|
1862 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
|
|
1863 | .PP |
|
|
1864 | .Vb 10 |
|
|
1865 | \& static void |
|
|
1866 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1867 | \& { |
|
|
1868 | \& /* /etc/passwd changed in some way */ |
|
|
1869 | \& if (w\->attr.st_nlink) |
|
|
1870 | \& { |
|
|
1871 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
|
|
1872 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
|
|
1873 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
|
|
1874 | \& } |
|
|
1875 | \& else |
|
|
1876 | \& /* you shalt not abuse printf for puts */ |
|
|
1877 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1878 | \& "if this is windows, they already arrived\en"); |
|
|
1879 | \& } |
|
|
1880 | \& |
|
|
1881 | \& ... |
|
|
1882 | \& ev_stat passwd; |
|
|
1883 | \& |
|
|
1884 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1885 | \& ev_stat_start (loop, &passwd); |
|
|
1886 | .Ve |
|
|
1887 | .PP |
|
|
1888 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1889 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1890 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1891 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
|
|
1892 | .PP |
1193 | .Vb 3 |
1893 | .Vb 2 |
1194 | \& struct ev_signal signal_watcher; |
1894 | \& static ev_stat passwd; |
1195 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1895 | \& static ev_timer timer; |
1196 | \& ev_signal_start (loop, &sigint_cb); |
1896 | \& |
|
|
1897 | \& static void |
|
|
1898 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1899 | \& { |
|
|
1900 | \& ev_timer_stop (EV_A_ w); |
|
|
1901 | \& |
|
|
1902 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1903 | \& } |
|
|
1904 | \& |
|
|
1905 | \& static void |
|
|
1906 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1907 | \& { |
|
|
1908 | \& /* reset the one\-second timer */ |
|
|
1909 | \& ev_timer_again (EV_A_ &timer); |
|
|
1910 | \& } |
|
|
1911 | \& |
|
|
1912 | \& ... |
|
|
1913 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1914 | \& ev_stat_start (loop, &passwd); |
|
|
1915 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1197 | .Ve |
1916 | .Ve |
1198 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1917 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1199 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1918 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1200 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1919 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1201 | Idle watchers trigger events when there are no other events are pending |
1920 | Idle watchers trigger events when no other events of the same or higher |
1202 | (prepare, check and other idle watchers do not count). That is, as long |
1921 | priority are pending (prepare, check and other idle watchers do not |
1203 | as your process is busy handling sockets or timeouts (or even signals, |
1922 | count). |
1204 | imagine) it will not be triggered. But when your process is idle all idle |
1923 | .PP |
1205 | watchers are being called again and again, once per event loop iteration \- |
1924 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1925 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1926 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1927 | are pending), the idle watchers are being called once per event loop |
1206 | until stopped, that is, or your process receives more events and becomes |
1928 | iteration \- until stopped, that is, or your process receives more events |
1207 | busy. |
1929 | and becomes busy again with higher priority stuff. |
1208 | .PP |
1930 | .PP |
1209 | The most noteworthy effect is that as long as any idle watchers are |
1931 | The most noteworthy effect is that as long as any idle watchers are |
1210 | active, the process will not block when waiting for new events. |
1932 | active, the process will not block when waiting for new events. |
1211 | .PP |
1933 | .PP |
1212 | Apart from keeping your process non-blocking (which is a useful |
1934 | Apart from keeping your process non-blocking (which is a useful |
1213 | effect on its own sometimes), idle watchers are a good place to do |
1935 | effect on its own sometimes), idle watchers are a good place to do |
1214 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1936 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1215 | event loop has handled all outstanding events. |
1937 | event loop has handled all outstanding events. |
|
|
1938 | .PP |
|
|
1939 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1940 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1216 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1941 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1217 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1942 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1218 | Initialises and configures the idle watcher \- it has no parameters of any |
1943 | Initialises and configures the idle watcher \- it has no parameters of any |
1219 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1944 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1220 | believe me. |
1945 | believe me. |
1221 | .PP |
1946 | .PP |
|
|
1947 | \fIExamples\fR |
|
|
1948 | .IX Subsection "Examples" |
|
|
1949 | .PP |
1222 | Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the |
1950 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1223 | callback, free it. Alos, use no error checking, as usual. |
1951 | callback, free it. Also, use no error checking, as usual. |
1224 | .PP |
1952 | .PP |
1225 | .Vb 7 |
1953 | .Vb 7 |
1226 | \& static void |
1954 | \& static void |
1227 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1955 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1228 | \& { |
1956 | \& { |
1229 | \& free (w); |
1957 | \& free (w); |
1230 | \& // now do something you wanted to do when the program has |
1958 | \& // now do something you wanted to do when the program has |
1231 | \& // no longer asnything immediate to do. |
1959 | \& // no longer anything immediate to do. |
1232 | \& } |
1960 | \& } |
1233 | .Ve |
1961 | \& |
1234 | .PP |
|
|
1235 | .Vb 3 |
|
|
1236 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1962 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1237 | \& ev_idle_init (idle_watcher, idle_cb); |
1963 | \& ev_idle_init (idle_watcher, idle_cb); |
1238 | \& ev_idle_start (loop, idle_cb); |
1964 | \& ev_idle_start (loop, idle_cb); |
1239 | .Ve |
1965 | .Ve |
1240 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1966 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
… | |
… | |
1242 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
1968 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
1243 | Prepare and check watchers are usually (but not always) used in tandem: |
1969 | Prepare and check watchers are usually (but not always) used in tandem: |
1244 | prepare watchers get invoked before the process blocks and check watchers |
1970 | prepare watchers get invoked before the process blocks and check watchers |
1245 | afterwards. |
1971 | afterwards. |
1246 | .PP |
1972 | .PP |
|
|
1973 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
|
|
1974 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
|
|
1975 | watchers. Other loops than the current one are fine, however. The |
|
|
1976 | rationale behind this is that you do not need to check for recursion in |
|
|
1977 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
|
|
1978 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
|
|
1979 | called in pairs bracketing the blocking call. |
|
|
1980 | .PP |
1247 | Their main purpose is to integrate other event mechanisms into libev and |
1981 | Their main purpose is to integrate other event mechanisms into libev and |
1248 | their use is somewhat advanced. This could be used, for example, to track |
1982 | their use is somewhat advanced. This could be used, for example, to track |
1249 | variable changes, implement your own watchers, integrate net-snmp or a |
1983 | variable changes, implement your own watchers, integrate net-snmp or a |
1250 | coroutine library and lots more. |
1984 | coroutine library and lots more. They are also occasionally useful if |
|
|
1985 | you cache some data and want to flush it before blocking (for example, |
|
|
1986 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
1987 | watcher). |
1251 | .PP |
1988 | .PP |
1252 | This is done by examining in each prepare call which file descriptors need |
1989 | This is done by examining in each prepare call which file descriptors need |
1253 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
1990 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
1254 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
1991 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
1255 | provide just this functionality). Then, in the check watcher you check for |
1992 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1264 | are ready to run (it's actually more complicated: it only runs coroutines |
2001 | are ready to run (it's actually more complicated: it only runs coroutines |
1265 | with priority higher than or equal to the event loop and one coroutine |
2002 | with priority higher than or equal to the event loop and one coroutine |
1266 | of lower priority, but only once, using idle watchers to keep the event |
2003 | of lower priority, but only once, using idle watchers to keep the event |
1267 | loop from blocking if lower-priority coroutines are active, thus mapping |
2004 | loop from blocking if lower-priority coroutines are active, thus mapping |
1268 | low-priority coroutines to idle/background tasks). |
2005 | low-priority coroutines to idle/background tasks). |
|
|
2006 | .PP |
|
|
2007 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
2008 | priority, to ensure that they are being run before any other watchers |
|
|
2009 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
|
|
2010 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
|
|
2011 | supports this, they might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers |
|
|
2012 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
|
|
2013 | (non-libev) event loops those other event loops might be in an unusable |
|
|
2014 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
|
|
2015 | coexist peacefully with others). |
|
|
2016 | .PP |
|
|
2017 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2018 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1269 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2019 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1270 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2020 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1271 | .PD 0 |
2021 | .PD 0 |
1272 | .IP "ev_check_init (ev_check *, callback)" 4 |
2022 | .IP "ev_check_init (ev_check *, callback)" 4 |
1273 | .IX Item "ev_check_init (ev_check *, callback)" |
2023 | .IX Item "ev_check_init (ev_check *, callback)" |
1274 | .PD |
2024 | .PD |
1275 | Initialises and configures the prepare or check watcher \- they have no |
2025 | Initialises and configures the prepare or check watcher \- they have no |
1276 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2026 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1277 | macros, but using them is utterly, utterly and completely pointless. |
2027 | macros, but using them is utterly, utterly and completely pointless. |
1278 | .PP |
2028 | .PP |
1279 | Example: *TODO*. |
2029 | \fIExamples\fR |
|
|
2030 | .IX Subsection "Examples" |
|
|
2031 | .PP |
|
|
2032 | There are a number of principal ways to embed other event loops or modules |
|
|
2033 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2034 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2035 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
|
|
2036 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
|
|
2037 | Glib event loop). |
|
|
2038 | .PP |
|
|
2039 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
|
|
2040 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
2041 | is pseudo-code only of course. This requires you to either use a low |
|
|
2042 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2043 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
2044 | .PP |
|
|
2045 | .Vb 2 |
|
|
2046 | \& static ev_io iow [nfd]; |
|
|
2047 | \& static ev_timer tw; |
|
|
2048 | \& |
|
|
2049 | \& static void |
|
|
2050 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
2051 | \& { |
|
|
2052 | \& } |
|
|
2053 | \& |
|
|
2054 | \& // create io watchers for each fd and a timer before blocking |
|
|
2055 | \& static void |
|
|
2056 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
2057 | \& { |
|
|
2058 | \& int timeout = 3600000; |
|
|
2059 | \& struct pollfd fds [nfd]; |
|
|
2060 | \& // actual code will need to loop here and realloc etc. |
|
|
2061 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
2062 | \& |
|
|
2063 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
|
|
2064 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
|
|
2065 | \& ev_timer_start (loop, &tw); |
|
|
2066 | \& |
|
|
2067 | \& // create one ev_io per pollfd |
|
|
2068 | \& for (int i = 0; i < nfd; ++i) |
|
|
2069 | \& { |
|
|
2070 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
2071 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
2072 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
2073 | \& |
|
|
2074 | \& fds [i].revents = 0; |
|
|
2075 | \& ev_io_start (loop, iow + i); |
|
|
2076 | \& } |
|
|
2077 | \& } |
|
|
2078 | \& |
|
|
2079 | \& // stop all watchers after blocking |
|
|
2080 | \& static void |
|
|
2081 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
2082 | \& { |
|
|
2083 | \& ev_timer_stop (loop, &tw); |
|
|
2084 | \& |
|
|
2085 | \& for (int i = 0; i < nfd; ++i) |
|
|
2086 | \& { |
|
|
2087 | \& // set the relevant poll flags |
|
|
2088 | \& // could also call adns_processreadable etc. here |
|
|
2089 | \& struct pollfd *fd = fds + i; |
|
|
2090 | \& int revents = ev_clear_pending (iow + i); |
|
|
2091 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2092 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2093 | \& |
|
|
2094 | \& // now stop the watcher |
|
|
2095 | \& ev_io_stop (loop, iow + i); |
|
|
2096 | \& } |
|
|
2097 | \& |
|
|
2098 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2099 | \& } |
|
|
2100 | .Ve |
|
|
2101 | .PP |
|
|
2102 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2103 | in the prepare watcher and would dispose of the check watcher. |
|
|
2104 | .PP |
|
|
2105 | Method 3: If the module to be embedded supports explicit event |
|
|
2106 | notification (adns does), you can also make use of the actual watcher |
|
|
2107 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
2108 | .PP |
|
|
2109 | .Vb 5 |
|
|
2110 | \& static void |
|
|
2111 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2112 | \& { |
|
|
2113 | \& adns_state ads = (adns_state)w\->data; |
|
|
2114 | \& update_now (EV_A); |
|
|
2115 | \& |
|
|
2116 | \& adns_processtimeouts (ads, &tv_now); |
|
|
2117 | \& } |
|
|
2118 | \& |
|
|
2119 | \& static void |
|
|
2120 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2121 | \& { |
|
|
2122 | \& adns_state ads = (adns_state)w\->data; |
|
|
2123 | \& update_now (EV_A); |
|
|
2124 | \& |
|
|
2125 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2126 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2127 | \& } |
|
|
2128 | \& |
|
|
2129 | \& // do not ever call adns_afterpoll |
|
|
2130 | .Ve |
|
|
2131 | .PP |
|
|
2132 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2133 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
2134 | their poll function. The drawback with this solution is that the main |
|
|
2135 | loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does |
|
|
2136 | this. |
|
|
2137 | .PP |
|
|
2138 | .Vb 4 |
|
|
2139 | \& static gint |
|
|
2140 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2141 | \& { |
|
|
2142 | \& int got_events = 0; |
|
|
2143 | \& |
|
|
2144 | \& for (n = 0; n < nfds; ++n) |
|
|
2145 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2146 | \& |
|
|
2147 | \& if (timeout >= 0) |
|
|
2148 | \& // create/start timer |
|
|
2149 | \& |
|
|
2150 | \& // poll |
|
|
2151 | \& ev_loop (EV_A_ 0); |
|
|
2152 | \& |
|
|
2153 | \& // stop timer again |
|
|
2154 | \& if (timeout >= 0) |
|
|
2155 | \& ev_timer_stop (EV_A_ &to); |
|
|
2156 | \& |
|
|
2157 | \& // stop io watchers again \- their callbacks should have set |
|
|
2158 | \& for (n = 0; n < nfds; ++n) |
|
|
2159 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2160 | \& |
|
|
2161 | \& return got_events; |
|
|
2162 | \& } |
|
|
2163 | .Ve |
1280 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2164 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1281 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2165 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1282 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2166 | .IX Subsection "ev_embed - when one backend isn't enough..." |
1283 | This is a rather advanced watcher type that lets you embed one event loop |
2167 | This is a rather advanced watcher type that lets you embed one event loop |
1284 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2168 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
… | |
… | |
1325 | portable one. |
2209 | portable one. |
1326 | .PP |
2210 | .PP |
1327 | So when you want to use this feature you will always have to be prepared |
2211 | So when you want to use this feature you will always have to be prepared |
1328 | that you cannot get an embeddable loop. The recommended way to get around |
2212 | that you cannot get an embeddable loop. The recommended way to get around |
1329 | this is to have a separate variables for your embeddable loop, try to |
2213 | this is to have a separate variables for your embeddable loop, try to |
1330 | create it, and if that fails, use the normal loop for everything: |
2214 | create it, and if that fails, use the normal loop for everything. |
1331 | .PP |
2215 | .PP |
1332 | .Vb 3 |
2216 | \fIWatcher-Specific Functions and Data Members\fR |
1333 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2217 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1334 | \& struct ev_loop *loop_lo = 0; |
|
|
1335 | \& struct ev_embed embed; |
|
|
1336 | .Ve |
|
|
1337 | .PP |
|
|
1338 | .Vb 5 |
|
|
1339 | \& // see if there is a chance of getting one that works |
|
|
1340 | \& // (remember that a flags value of 0 means autodetection) |
|
|
1341 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1342 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1343 | \& : 0; |
|
|
1344 | .Ve |
|
|
1345 | .PP |
|
|
1346 | .Vb 8 |
|
|
1347 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
1348 | \& if (loop_lo) |
|
|
1349 | \& { |
|
|
1350 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1351 | \& ev_embed_start (loop_hi, &embed); |
|
|
1352 | \& } |
|
|
1353 | \& else |
|
|
1354 | \& loop_lo = loop_hi; |
|
|
1355 | .Ve |
|
|
1356 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2218 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1357 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2219 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1358 | .PD 0 |
2220 | .PD 0 |
1359 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2221 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1360 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2222 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
… | |
… | |
1367 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2229 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1368 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2230 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1369 | Make a single, non-blocking sweep over the embedded loop. This works |
2231 | Make a single, non-blocking sweep over the embedded loop. This works |
1370 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2232 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1371 | apropriate way for embedded loops. |
2233 | apropriate way for embedded loops. |
|
|
2234 | .IP "struct ev_loop *other [read\-only]" 4 |
|
|
2235 | .IX Item "struct ev_loop *other [read-only]" |
|
|
2236 | The embedded event loop. |
|
|
2237 | .PP |
|
|
2238 | \fIExamples\fR |
|
|
2239 | .IX Subsection "Examples" |
|
|
2240 | .PP |
|
|
2241 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2242 | event loop. If that is not possible, use the default loop. The default |
|
|
2243 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2244 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2245 | used). |
|
|
2246 | .PP |
|
|
2247 | .Vb 3 |
|
|
2248 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2249 | \& struct ev_loop *loop_lo = 0; |
|
|
2250 | \& struct ev_embed embed; |
|
|
2251 | \& |
|
|
2252 | \& // see if there is a chance of getting one that works |
|
|
2253 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2254 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2255 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2256 | \& : 0; |
|
|
2257 | \& |
|
|
2258 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2259 | \& if (loop_lo) |
|
|
2260 | \& { |
|
|
2261 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2262 | \& ev_embed_start (loop_hi, &embed); |
|
|
2263 | \& } |
|
|
2264 | \& else |
|
|
2265 | \& loop_lo = loop_hi; |
|
|
2266 | .Ve |
|
|
2267 | .PP |
|
|
2268 | Example: Check if kqueue is available but not recommended and create |
|
|
2269 | a kqueue backend for use with sockets (which usually work with any |
|
|
2270 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2271 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2272 | .PP |
|
|
2273 | .Vb 3 |
|
|
2274 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2275 | \& struct ev_loop *loop_socket = 0; |
|
|
2276 | \& struct ev_embed embed; |
|
|
2277 | \& |
|
|
2278 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2279 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2280 | \& { |
|
|
2281 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2282 | \& ev_embed_start (loop, &embed); |
|
|
2283 | \& } |
|
|
2284 | \& |
|
|
2285 | \& if (!loop_socket) |
|
|
2286 | \& loop_socket = loop; |
|
|
2287 | \& |
|
|
2288 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2289 | .Ve |
|
|
2290 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
|
|
2291 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
|
|
2292 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
|
|
2293 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
|
|
2294 | whoever is a good citizen cared to tell libev about it by calling |
|
|
2295 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
|
|
2296 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
|
|
2297 | and only in the child after the fork. If whoever good citizen calling |
|
|
2298 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
|
|
2299 | handlers will be invoked, too, of course. |
|
|
2300 | .PP |
|
|
2301 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2302 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2303 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
|
|
2304 | .IX Item "ev_fork_init (ev_signal *, callback)" |
|
|
2305 | Initialises and configures the fork watcher \- it has no parameters of any |
|
|
2306 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2307 | believe me. |
|
|
2308 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2309 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2310 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2311 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2312 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2313 | loops \- those are of course safe to use in different threads). |
|
|
2314 | .PP |
|
|
2315 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2316 | control, for example because it belongs to another thread. This is what |
|
|
2317 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2318 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2319 | safe. |
|
|
2320 | .PP |
|
|
2321 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2322 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2323 | (i.e. the number of callback invocations may be less than the number of |
|
|
2324 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2325 | .PP |
|
|
2326 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2327 | just the default loop. |
|
|
2328 | .PP |
|
|
2329 | \fIQueueing\fR |
|
|
2330 | .IX Subsection "Queueing" |
|
|
2331 | .PP |
|
|
2332 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2333 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2334 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2335 | need elaborate support such as pthreads. |
|
|
2336 | .PP |
|
|
2337 | That means that if you want to queue data, you have to provide your own |
|
|
2338 | queue. But at least I can tell you would implement locking around your |
|
|
2339 | queue: |
|
|
2340 | .IP "queueing from a signal handler context" 4 |
|
|
2341 | .IX Item "queueing from a signal handler context" |
|
|
2342 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2343 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2344 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2345 | .Sp |
|
|
2346 | .Vb 1 |
|
|
2347 | \& static ev_async mysig; |
|
|
2348 | \& |
|
|
2349 | \& static void |
|
|
2350 | \& sigusr1_handler (void) |
|
|
2351 | \& { |
|
|
2352 | \& sometype data; |
|
|
2353 | \& |
|
|
2354 | \& // no locking etc. |
|
|
2355 | \& queue_put (data); |
|
|
2356 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2357 | \& } |
|
|
2358 | \& |
|
|
2359 | \& static void |
|
|
2360 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2361 | \& { |
|
|
2362 | \& sometype data; |
|
|
2363 | \& sigset_t block, prev; |
|
|
2364 | \& |
|
|
2365 | \& sigemptyset (&block); |
|
|
2366 | \& sigaddset (&block, SIGUSR1); |
|
|
2367 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2368 | \& |
|
|
2369 | \& while (queue_get (&data)) |
|
|
2370 | \& process (data); |
|
|
2371 | \& |
|
|
2372 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2373 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2374 | \& } |
|
|
2375 | .Ve |
|
|
2376 | .Sp |
|
|
2377 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2378 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2379 | either...). |
|
|
2380 | .IP "queueing from a thread context" 4 |
|
|
2381 | .IX Item "queueing from a thread context" |
|
|
2382 | The strategy for threads is different, as you cannot (easily) block |
|
|
2383 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2384 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2385 | .Sp |
|
|
2386 | .Vb 2 |
|
|
2387 | \& static ev_async mysig; |
|
|
2388 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2389 | \& |
|
|
2390 | \& static void |
|
|
2391 | \& otherthread (void) |
|
|
2392 | \& { |
|
|
2393 | \& // only need to lock the actual queueing operation |
|
|
2394 | \& pthread_mutex_lock (&mymutex); |
|
|
2395 | \& queue_put (data); |
|
|
2396 | \& pthread_mutex_unlock (&mymutex); |
|
|
2397 | \& |
|
|
2398 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2399 | \& } |
|
|
2400 | \& |
|
|
2401 | \& static void |
|
|
2402 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2403 | \& { |
|
|
2404 | \& pthread_mutex_lock (&mymutex); |
|
|
2405 | \& |
|
|
2406 | \& while (queue_get (&data)) |
|
|
2407 | \& process (data); |
|
|
2408 | \& |
|
|
2409 | \& pthread_mutex_unlock (&mymutex); |
|
|
2410 | \& } |
|
|
2411 | .Ve |
|
|
2412 | .PP |
|
|
2413 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2414 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2415 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2416 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2417 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2418 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2419 | believe me. |
|
|
2420 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2421 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2422 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2423 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2424 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2425 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2426 | section below on what exactly this means). |
|
|
2427 | .Sp |
|
|
2428 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2429 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2430 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2431 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2432 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2433 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2434 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2435 | event loop. |
|
|
2436 | .Sp |
|
|
2437 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2438 | the loop iterates next and checks for the watcher to have become active, |
|
|
2439 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2440 | quickly check wether invoking the loop might be a good idea. |
|
|
2441 | .Sp |
|
|
2442 | Not that this does \fInot\fR check wether the watcher itself is pending, only |
|
|
2443 | wether it has been requested to make this watcher pending. |
1372 | .SH "OTHER FUNCTIONS" |
2444 | .SH "OTHER FUNCTIONS" |
1373 | .IX Header "OTHER FUNCTIONS" |
2445 | .IX Header "OTHER FUNCTIONS" |
1374 | There are some other functions of possible interest. Described. Here. Now. |
2446 | There are some other functions of possible interest. Described. Here. Now. |
1375 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2447 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1376 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2448 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
1400 | \& if (revents & EV_TIMEOUT) |
2472 | \& if (revents & EV_TIMEOUT) |
1401 | \& /* doh, nothing entered */; |
2473 | \& /* doh, nothing entered */; |
1402 | \& else if (revents & EV_READ) |
2474 | \& else if (revents & EV_READ) |
1403 | \& /* stdin might have data for us, joy! */; |
2475 | \& /* stdin might have data for us, joy! */; |
1404 | \& } |
2476 | \& } |
1405 | .Ve |
2477 | \& |
1406 | .Sp |
|
|
1407 | .Vb 1 |
|
|
1408 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2478 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1409 | .Ve |
2479 | .Ve |
1410 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2480 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
1411 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2481 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
1412 | Feeds the given event set into the event loop, as if the specified event |
2482 | Feeds the given event set into the event loop, as if the specified event |
… | |
… | |
1422 | loop!). |
2492 | loop!). |
1423 | .SH "LIBEVENT EMULATION" |
2493 | .SH "LIBEVENT EMULATION" |
1424 | .IX Header "LIBEVENT EMULATION" |
2494 | .IX Header "LIBEVENT EMULATION" |
1425 | Libev offers a compatibility emulation layer for libevent. It cannot |
2495 | Libev offers a compatibility emulation layer for libevent. It cannot |
1426 | emulate the internals of libevent, so here are some usage hints: |
2496 | emulate the internals of libevent, so here are some usage hints: |
|
|
2497 | .IP "\(bu" 4 |
1427 | .IP "* Use it by including <event.h>, as usual." 4 |
2498 | Use it by including <event.h>, as usual. |
1428 | .IX Item "Use it by including <event.h>, as usual." |
2499 | .IP "\(bu" 4 |
1429 | .PD 0 |
2500 | The following members are fully supported: ev_base, ev_callback, |
1430 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2501 | ev_arg, ev_fd, ev_res, ev_events. |
1431 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2502 | .IP "\(bu" 4 |
1432 | .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 |
2503 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1433 | .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)." |
2504 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1434 | .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 |
2505 | it a private \s-1API\s0). |
1435 | .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." |
2506 | .IP "\(bu" 4 |
|
|
2507 | Priorities are not currently supported. Initialising priorities |
|
|
2508 | will fail and all watchers will have the same priority, even though there |
|
|
2509 | is an ev_pri field. |
|
|
2510 | .IP "\(bu" 4 |
|
|
2511 | In libevent, the last base created gets the signals, in libev, the |
|
|
2512 | first base created (== the default loop) gets the signals. |
|
|
2513 | .IP "\(bu" 4 |
1436 | .IP "* Other members are not supported." 4 |
2514 | Other members are not supported. |
1437 | .IX Item "Other members are not supported." |
2515 | .IP "\(bu" 4 |
1438 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2516 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1439 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2517 | to use the libev header file and library. |
1440 | .PD |
|
|
1441 | .SH "\*(C+ SUPPORT" |
2518 | .SH "\*(C+ SUPPORT" |
1442 | .IX Header " SUPPORT" |
2519 | .IX Header " SUPPORT" |
1443 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2520 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1444 | you to use some convinience methods to start/stop watchers and also change |
2521 | you to use some convinience methods to start/stop watchers and also change |
1445 | the callback model to a model using method callbacks on objects. |
2522 | the callback model to a model using method callbacks on objects. |
… | |
… | |
1448 | .PP |
2525 | .PP |
1449 | .Vb 1 |
2526 | .Vb 1 |
1450 | \& #include <ev++.h> |
2527 | \& #include <ev++.h> |
1451 | .Ve |
2528 | .Ve |
1452 | .PP |
2529 | .PP |
1453 | (it is not installed by default). This automatically includes \fIev.h\fR |
2530 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1454 | and puts all of its definitions (many of them macros) into the global |
2531 | of them macros) into the global namespace. All \*(C+ specific things are |
1455 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
2532 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2533 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1456 | .PP |
2534 | .PP |
1457 | It should support all the same embedding options as \fIev.h\fR, most notably |
2535 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1458 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
2536 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2537 | that the watcher is associated with (or no additional members at all if |
|
|
2538 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2539 | .PP |
|
|
2540 | Currently, functions, and static and non-static member functions can be |
|
|
2541 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2542 | need one additional pointer for context. If you need support for other |
|
|
2543 | types of functors please contact the author (preferably after implementing |
|
|
2544 | it). |
1459 | .PP |
2545 | .PP |
1460 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2546 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1461 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
2547 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
1462 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2548 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1463 | .IX Item "ev::READ, ev::WRITE etc." |
2549 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
1475 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
2561 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1476 | defines by many implementations. |
2562 | defines by many implementations. |
1477 | .Sp |
2563 | .Sp |
1478 | All of those classes have these methods: |
2564 | All of those classes have these methods: |
1479 | .RS 4 |
2565 | .RS 4 |
1480 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
2566 | .IP "ev::TYPE::TYPE ()" 4 |
1481 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
2567 | .IX Item "ev::TYPE::TYPE ()" |
1482 | .PD 0 |
2568 | .PD 0 |
1483 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
2569 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1484 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
2570 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1485 | .IP "ev::TYPE::~TYPE" 4 |
2571 | .IP "ev::TYPE::~TYPE" 4 |
1486 | .IX Item "ev::TYPE::~TYPE" |
2572 | .IX Item "ev::TYPE::~TYPE" |
1487 | .PD |
2573 | .PD |
1488 | The constructor takes a pointer to an object and a method pointer to |
2574 | The constructor (optionally) takes an event loop to associate the watcher |
1489 | the event handler callback to call in this class. The constructor calls |
2575 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1490 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
2576 | .Sp |
1491 | before starting it. If you do not specify a loop then the constructor |
2577 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1492 | automatically associates the default loop with this watcher. |
2578 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2579 | .Sp |
|
|
2580 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2581 | method to set a callback before you can start the watcher. |
|
|
2582 | .Sp |
|
|
2583 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2584 | not allow explicit template arguments for constructors). |
1493 | .Sp |
2585 | .Sp |
1494 | The destructor automatically stops the watcher if it is active. |
2586 | The destructor automatically stops the watcher if it is active. |
|
|
2587 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2588 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2589 | This method sets the callback method to call. The method has to have a |
|
|
2590 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2591 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2592 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2593 | .Sp |
|
|
2594 | This method synthesizes efficient thunking code to call your method from |
|
|
2595 | the C callback that libev requires. If your compiler can inline your |
|
|
2596 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2597 | your compiler is good :), then the method will be fully inlined into the |
|
|
2598 | thunking function, making it as fast as a direct C callback. |
|
|
2599 | .Sp |
|
|
2600 | Example: simple class declaration and watcher initialisation |
|
|
2601 | .Sp |
|
|
2602 | .Vb 4 |
|
|
2603 | \& struct myclass |
|
|
2604 | \& { |
|
|
2605 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2606 | \& } |
|
|
2607 | \& |
|
|
2608 | \& myclass obj; |
|
|
2609 | \& ev::io iow; |
|
|
2610 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2611 | .Ve |
|
|
2612 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2613 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2614 | Also sets a callback, but uses a static method or plain function as |
|
|
2615 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2616 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2617 | .Sp |
|
|
2618 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
2619 | .Sp |
|
|
2620 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
2621 | .Sp |
|
|
2622 | Example: |
|
|
2623 | .Sp |
|
|
2624 | .Vb 2 |
|
|
2625 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
2626 | \& iow.set <io_cb> (); |
|
|
2627 | .Ve |
1495 | .IP "w\->set (struct ev_loop *)" 4 |
2628 | .IP "w\->set (struct ev_loop *)" 4 |
1496 | .IX Item "w->set (struct ev_loop *)" |
2629 | .IX Item "w->set (struct ev_loop *)" |
1497 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
2630 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1498 | do this when the watcher is inactive (and not pending either). |
2631 | do this when the watcher is inactive (and not pending either). |
1499 | .IP "w\->set ([args])" 4 |
2632 | .IP "w\->set ([args])" 4 |
1500 | .IX Item "w->set ([args])" |
2633 | .IX Item "w->set ([args])" |
1501 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
2634 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
1502 | called at least once. Unlike the C counterpart, an active watcher gets |
2635 | called at least once. Unlike the C counterpart, an active watcher gets |
1503 | automatically stopped and restarted. |
2636 | automatically stopped and restarted when reconfiguring it with this |
|
|
2637 | method. |
1504 | .IP "w\->start ()" 4 |
2638 | .IP "w\->start ()" 4 |
1505 | .IX Item "w->start ()" |
2639 | .IX Item "w->start ()" |
1506 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
2640 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1507 | constructor already takes the loop. |
2641 | constructor already stores the event loop. |
1508 | .IP "w\->stop ()" 4 |
2642 | .IP "w\->stop ()" 4 |
1509 | .IX Item "w->stop ()" |
2643 | .IX Item "w->stop ()" |
1510 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
2644 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1511 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
2645 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
1512 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
2646 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1513 | .IX Item "w->again () ev::timer, ev::periodic only" |
2647 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1514 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
2648 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1515 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
2649 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1516 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
2650 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1517 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
2651 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1518 | .IX Item "w->sweep () ev::embed only" |
2652 | .IX Item "w->sweep () (ev::embed only)" |
1519 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
2653 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
|
|
2654 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
|
|
2655 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
|
|
2656 | .IX Item "w->update () (ev::stat only)" |
|
|
2657 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1520 | .RE |
2658 | .RE |
1521 | .RS 4 |
2659 | .RS 4 |
1522 | .RE |
2660 | .RE |
1523 | .PP |
2661 | .PP |
1524 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
2662 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
1525 | the constructor. |
2663 | the constructor. |
1526 | .PP |
2664 | .PP |
1527 | .Vb 4 |
2665 | .Vb 4 |
1528 | \& class myclass |
2666 | \& class myclass |
1529 | \& { |
2667 | \& { |
1530 | \& ev_io io; void io_cb (ev::io &w, int revents); |
2668 | \& ev::io io; void io_cb (ev::io &w, int revents); |
1531 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
2669 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2670 | \& |
|
|
2671 | \& myclass (int fd) |
|
|
2672 | \& { |
|
|
2673 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
2674 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2675 | \& |
|
|
2676 | \& io.start (fd, ev::READ); |
|
|
2677 | \& } |
|
|
2678 | \& }; |
1532 | .Ve |
2679 | .Ve |
|
|
2680 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2681 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2682 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2683 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2684 | any interesting language binding in addition to the ones listed here, drop |
|
|
2685 | me a note. |
|
|
2686 | .IP "Perl" 4 |
|
|
2687 | .IX Item "Perl" |
|
|
2688 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2689 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2690 | there are additional modules that implement libev-compatible interfaces |
|
|
2691 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2692 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2693 | .Sp |
|
|
2694 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2695 | <http://software.schmorp.de/pkg/EV>. |
|
|
2696 | .IP "Ruby" 4 |
|
|
2697 | .IX Item "Ruby" |
|
|
2698 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2699 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2700 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2701 | <http://rev.rubyforge.org/>. |
|
|
2702 | .IP "D" 4 |
|
|
2703 | .IX Item "D" |
|
|
2704 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2705 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2706 | .SH "MACRO MAGIC" |
|
|
2707 | .IX Header "MACRO MAGIC" |
|
|
2708 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2709 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
|
|
2710 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1533 | .PP |
2711 | .PP |
|
|
2712 | To make it easier to write programs that cope with either variant, the |
|
|
2713 | following macros are defined: |
|
|
2714 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
|
|
2715 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
|
|
2716 | .IX Item "EV_A, EV_A_" |
|
|
2717 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
|
|
2718 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
|
|
2719 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
|
|
2720 | .Sp |
|
|
2721 | .Vb 3 |
|
|
2722 | \& ev_unref (EV_A); |
|
|
2723 | \& ev_timer_add (EV_A_ watcher); |
|
|
2724 | \& ev_loop (EV_A_ 0); |
|
|
2725 | .Ve |
|
|
2726 | .Sp |
|
|
2727 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
|
|
2728 | which is often provided by the following macro. |
|
|
2729 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
|
|
2730 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
|
|
2731 | .IX Item "EV_P, EV_P_" |
|
|
2732 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
|
|
2733 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
|
|
2734 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
|
|
2735 | .Sp |
1534 | .Vb 2 |
2736 | .Vb 2 |
1535 | \& myclass (); |
2737 | \& // this is how ev_unref is being declared |
|
|
2738 | \& static void ev_unref (EV_P); |
|
|
2739 | \& |
|
|
2740 | \& // this is how you can declare your typical callback |
|
|
2741 | \& static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2742 | .Ve |
|
|
2743 | .Sp |
|
|
2744 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
|
|
2745 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
|
|
2746 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
|
|
2747 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
|
|
2748 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
|
|
2749 | Similar to the other two macros, this gives you the value of the default |
|
|
2750 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2751 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
2752 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
2753 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
2754 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
2755 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
2756 | is undefined when the default loop has not been initialised by a previous |
|
|
2757 | 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. |
|
|
2758 | .Sp |
|
|
2759 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
2760 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
|
|
2761 | .PP |
|
|
2762 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2763 | macros so it will work regardless of whether multiple loops are supported |
|
|
2764 | or not. |
|
|
2765 | .PP |
|
|
2766 | .Vb 5 |
|
|
2767 | \& static void |
|
|
2768 | \& check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2769 | \& { |
|
|
2770 | \& ev_check_stop (EV_A_ w); |
1536 | \& } |
2771 | \& } |
1537 | .Ve |
2772 | \& |
1538 | .PP |
2773 | \& ev_check check; |
1539 | .Vb 6 |
2774 | \& ev_check_init (&check, check_cb); |
1540 | \& myclass::myclass (int fd) |
2775 | \& ev_check_start (EV_DEFAULT_ &check); |
1541 | \& : io (this, &myclass::io_cb), |
2776 | \& ev_loop (EV_DEFAULT_ 0); |
1542 | \& idle (this, &myclass::idle_cb) |
|
|
1543 | \& { |
|
|
1544 | \& io.start (fd, ev::READ); |
|
|
1545 | \& } |
|
|
1546 | .Ve |
2777 | .Ve |
1547 | .SH "EMBEDDING" |
2778 | .SH "EMBEDDING" |
1548 | .IX Header "EMBEDDING" |
2779 | .IX Header "EMBEDDING" |
1549 | Libev can (and often is) directly embedded into host |
2780 | Libev can (and often is) directly embedded into host |
1550 | applications. Examples of applications that embed it include the Deliantra |
2781 | applications. Examples of applications that embed it include the Deliantra |
1551 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2782 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
1552 | and rxvt\-unicode. |
2783 | and rxvt-unicode. |
1553 | .PP |
2784 | .PP |
1554 | The goal is to enable you to just copy the neecssary files into your |
2785 | The goal is to enable you to just copy the necessary files into your |
1555 | source directory without having to change even a single line in them, so |
2786 | source directory without having to change even a single line in them, so |
1556 | you can easily upgrade by simply copying (or having a checked-out copy of |
2787 | you can easily upgrade by simply copying (or having a checked-out copy of |
1557 | libev somewhere in your source tree). |
2788 | libev somewhere in your source tree). |
1558 | .Sh "\s-1FILESETS\s0" |
2789 | .Sh "\s-1FILESETS\s0" |
1559 | .IX Subsection "FILESETS" |
2790 | .IX Subsection "FILESETS" |
… | |
… | |
1592 | .Vb 4 |
2823 | .Vb 4 |
1593 | \& ev.h |
2824 | \& ev.h |
1594 | \& ev.c |
2825 | \& ev.c |
1595 | \& ev_vars.h |
2826 | \& ev_vars.h |
1596 | \& ev_wrap.h |
2827 | \& ev_wrap.h |
1597 | .Ve |
2828 | \& |
1598 | .PP |
|
|
1599 | .Vb 1 |
|
|
1600 | \& ev_win32.c required on win32 platforms only |
2829 | \& ev_win32.c required on win32 platforms only |
1601 | .Ve |
2830 | \& |
1602 | .PP |
|
|
1603 | .Vb 5 |
|
|
1604 | \& ev_select.c only when select backend is enabled (which is is by default) |
2831 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
1605 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2832 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
1606 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2833 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1607 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2834 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1608 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2835 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
1609 | .Ve |
2836 | .Ve |
1610 | .PP |
2837 | .PP |
1611 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
2838 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
1612 | to compile a single file. |
2839 | to compile this single file. |
1613 | .PP |
2840 | .PP |
1614 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
2841 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
1615 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
2842 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
1616 | .PP |
2843 | .PP |
1617 | To include the libevent compatibility \s-1API\s0, also include: |
2844 | To include the libevent compatibility \s-1API\s0, also include: |
… | |
… | |
1638 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
2865 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
1639 | .IX Subsection "AUTOCONF SUPPORT" |
2866 | .IX Subsection "AUTOCONF SUPPORT" |
1640 | .PP |
2867 | .PP |
1641 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
2868 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
1642 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
2869 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
1643 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR off. \fIev.c\fR will then include |
2870 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
1644 | \&\fIconfig.h\fR and configure itself accordingly. |
2871 | include \fIconfig.h\fR and configure itself accordingly. |
1645 | .PP |
2872 | .PP |
1646 | For this of course you need the m4 file: |
2873 | For this of course you need the m4 file: |
1647 | .PP |
2874 | .PP |
1648 | .Vb 1 |
2875 | .Vb 1 |
1649 | \& libev.m4 |
2876 | \& libev.m4 |
1650 | .Ve |
2877 | .Ve |
1651 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2878 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
1652 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2879 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
1653 | Libev can be configured via a variety of preprocessor symbols you have to define |
2880 | Libev can be configured via a variety of preprocessor symbols you have to |
1654 | before including any of its files. The default is not to build for multiplicity |
2881 | define before including any of its files. The default in the absense of |
1655 | and only include the select backend. |
2882 | autoconf is noted for every option. |
1656 | .IP "\s-1EV_STANDALONE\s0" 4 |
2883 | .IP "\s-1EV_STANDALONE\s0" 4 |
1657 | .IX Item "EV_STANDALONE" |
2884 | .IX Item "EV_STANDALONE" |
1658 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2885 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
1659 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2886 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
1660 | implementations for some libevent functions (such as logging, which is not |
2887 | implementations for some libevent functions (such as logging, which is not |
… | |
… | |
1664 | .IX Item "EV_USE_MONOTONIC" |
2891 | .IX Item "EV_USE_MONOTONIC" |
1665 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2892 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
1666 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2893 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1667 | of the monotonic clock option will be attempted. If you enable this, you |
2894 | of the monotonic clock option will be attempted. If you enable this, you |
1668 | usually have to link against librt or something similar. Enabling it when |
2895 | usually have to link against librt or something similar. Enabling it when |
1669 | the functionality isn't available is safe, though, althoguh you have |
2896 | the functionality isn't available is safe, though, although you have |
1670 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2897 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
1671 | function is hiding in (often \fI\-lrt\fR). |
2898 | function is hiding in (often \fI\-lrt\fR). |
1672 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2899 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
1673 | .IX Item "EV_USE_REALTIME" |
2900 | .IX Item "EV_USE_REALTIME" |
1674 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2901 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
1675 | realtime clock option at compiletime (and assume its availability at |
2902 | realtime clock option at compiletime (and assume its availability at |
1676 | runtime if successful). Otherwise no use of the realtime clock option will |
2903 | runtime if successful). Otherwise no use of the realtime clock option will |
1677 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2904 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
1678 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
2905 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
1679 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2906 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2907 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
2908 | .IX Item "EV_USE_NANOSLEEP" |
|
|
2909 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
2910 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
2911 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
2912 | .IX Item "EV_USE_EVENTFD" |
|
|
2913 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
2914 | available and will probe for kernel support at runtime. This will improve |
|
|
2915 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
2916 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2917 | 2.7 or newer, otherwise disabled. |
1680 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2918 | .IP "\s-1EV_USE_SELECT\s0" 4 |
1681 | .IX Item "EV_USE_SELECT" |
2919 | .IX Item "EV_USE_SELECT" |
1682 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2920 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
1683 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2921 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
1684 | other method takes over, select will be it. Otherwise the select backend |
2922 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
1699 | wants osf handles on win32 (this is the case when the select to |
2937 | wants osf handles on win32 (this is the case when the select to |
1700 | be used is the winsock select). This means that it will call |
2938 | be used is the winsock select). This means that it will call |
1701 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2939 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
1702 | it is assumed that all these functions actually work on fds, even |
2940 | it is assumed that all these functions actually work on fds, even |
1703 | on win32. Should not be defined on non\-win32 platforms. |
2941 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2942 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2943 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2944 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2945 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2946 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2947 | correct. In some cases, programs use their own file descriptor management, |
|
|
2948 | in which case they can provide this function to map fds to socket handles. |
1704 | .IP "\s-1EV_USE_POLL\s0" 4 |
2949 | .IP "\s-1EV_USE_POLL\s0" 4 |
1705 | .IX Item "EV_USE_POLL" |
2950 | .IX Item "EV_USE_POLL" |
1706 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2951 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
1707 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2952 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
1708 | takes precedence over select. |
2953 | takes precedence over select. |
1709 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2954 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
1710 | .IX Item "EV_USE_EPOLL" |
2955 | .IX Item "EV_USE_EPOLL" |
1711 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2956 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
1712 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2957 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
1713 | otherwise another method will be used as fallback. This is the |
2958 | otherwise another method will be used as fallback. This is the preferred |
1714 | preferred backend for GNU/Linux systems. |
2959 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2960 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
1715 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2961 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
1716 | .IX Item "EV_USE_KQUEUE" |
2962 | .IX Item "EV_USE_KQUEUE" |
1717 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2963 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
1718 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2964 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
1719 | otherwise another method will be used as fallback. This is the preferred |
2965 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
1730 | otherwise another method will be used as fallback. This is the preferred |
2976 | otherwise another method will be used as fallback. This is the preferred |
1731 | backend for Solaris 10 systems. |
2977 | backend for Solaris 10 systems. |
1732 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
2978 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
1733 | .IX Item "EV_USE_DEVPOLL" |
2979 | .IX Item "EV_USE_DEVPOLL" |
1734 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2980 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
2981 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
2982 | .IX Item "EV_USE_INOTIFY" |
|
|
2983 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
2984 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
2985 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2986 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2987 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
2988 | .IX Item "EV_ATOMIC_T" |
|
|
2989 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
2990 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2991 | type is easily found in the C language, so you can provide your own type |
|
|
2992 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
2993 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
2994 | .Sp |
|
|
2995 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
2996 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
1735 | .IP "\s-1EV_H\s0" 4 |
2997 | .IP "\s-1EV_H\s0" 4 |
1736 | .IX Item "EV_H" |
2998 | .IX Item "EV_H" |
1737 | The name of the \fIev.h\fR header file used to include it. The default if |
2999 | The name of the \fIev.h\fR header file used to include it. The default if |
1738 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3000 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
1739 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3001 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
1740 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3002 | .IP "\s-1EV_CONFIG_H\s0" 4 |
1741 | .IX Item "EV_CONFIG_H" |
3003 | .IX Item "EV_CONFIG_H" |
1742 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3004 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
1743 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3005 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
1744 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3006 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
1745 | .IP "\s-1EV_EVENT_H\s0" 4 |
3007 | .IP "\s-1EV_EVENT_H\s0" 4 |
1746 | .IX Item "EV_EVENT_H" |
3008 | .IX Item "EV_EVENT_H" |
1747 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3009 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
1748 | of how the \fIevent.h\fR header can be found. |
3010 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
1749 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3011 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
1750 | .IX Item "EV_PROTOTYPES" |
3012 | .IX Item "EV_PROTOTYPES" |
1751 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3013 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
1752 | prototypes, but still define all the structs and other symbols. This is |
3014 | prototypes, but still define all the structs and other symbols. This is |
1753 | occasionally useful if you want to provide your own wrapper functions |
3015 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
1757 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3019 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
1758 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3020 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
1759 | additional independent event loops. Otherwise there will be no support |
3021 | additional independent event loops. Otherwise there will be no support |
1760 | for multiple event loops and there is no first event loop pointer |
3022 | for multiple event loops and there is no first event loop pointer |
1761 | argument. Instead, all functions act on the single default loop. |
3023 | argument. Instead, all functions act on the single default loop. |
|
|
3024 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3025 | .IX Item "EV_MINPRI" |
|
|
3026 | .PD 0 |
|
|
3027 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3028 | .IX Item "EV_MAXPRI" |
|
|
3029 | .PD |
|
|
3030 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3031 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3032 | provide for more priorities by overriding those symbols (usually defined |
|
|
3033 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3034 | .Sp |
|
|
3035 | When doing priority-based operations, libev usually has to linearly search |
|
|
3036 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3037 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3038 | fine. |
|
|
3039 | .Sp |
|
|
3040 | If your embedding app does not need any priorities, defining these both to |
|
|
3041 | \&\f(CW0\fR will save some memory and cpu. |
1762 | .IP "\s-1EV_PERIODICS\s0" 4 |
3042 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
1763 | .IX Item "EV_PERIODICS" |
3043 | .IX Item "EV_PERIODIC_ENABLE" |
1764 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported, |
3044 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
1765 | otherwise not. This saves a few kb of code. |
3045 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3046 | code. |
|
|
3047 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3048 | .IX Item "EV_IDLE_ENABLE" |
|
|
3049 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3050 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3051 | code. |
|
|
3052 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
3053 | .IX Item "EV_EMBED_ENABLE" |
|
|
3054 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
3055 | defined to be \f(CW0\fR, then they are not. |
|
|
3056 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
|
|
3057 | .IX Item "EV_STAT_ENABLE" |
|
|
3058 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
3059 | defined to be \f(CW0\fR, then they are not. |
|
|
3060 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3061 | .IX Item "EV_FORK_ENABLE" |
|
|
3062 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3063 | defined to be \f(CW0\fR, then they are not. |
|
|
3064 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3065 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3066 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3067 | defined to be \f(CW0\fR, then they are not. |
|
|
3068 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
3069 | .IX Item "EV_MINIMAL" |
|
|
3070 | If you need to shave off some kilobytes of code at the expense of some |
|
|
3071 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
|
|
3072 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
|
|
3073 | much smaller 2\-heap for timer management over the default 4\-heap. |
|
|
3074 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
|
|
3075 | .IX Item "EV_PID_HASHSIZE" |
|
|
3076 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3077 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
|
|
3078 | than enough. If you need to manage thousands of children you might want to |
|
|
3079 | increase this value (\fImust\fR be a power of two). |
|
|
3080 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
3081 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
3082 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3083 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
3084 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
3085 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
3086 | two). |
|
|
3087 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3088 | .IX Item "EV_USE_4HEAP" |
|
|
3089 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3090 | timer and periodics heap, libev uses a 4\-heap when this symbol is defined |
|
|
3091 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has a |
|
|
3092 | noticable after performance with many (thousands) of watchers. |
|
|
3093 | .Sp |
|
|
3094 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3095 | (disabled). |
|
|
3096 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3097 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3098 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3099 | timer and periodics heap, libev can cache the timestamp (\fIat\fR) within |
|
|
3100 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3101 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3102 | but avoids random read accesses on heap changes. This noticably improves |
|
|
3103 | performance noticably with with many (hundreds) of watchers. |
|
|
3104 | .Sp |
|
|
3105 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3106 | (disabled). |
1766 | .IP "\s-1EV_COMMON\s0" 4 |
3107 | .IP "\s-1EV_COMMON\s0" 4 |
1767 | .IX Item "EV_COMMON" |
3108 | .IX Item "EV_COMMON" |
1768 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3109 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
1769 | this macro to a something else you can include more and other types of |
3110 | this macro to a something else you can include more and other types of |
1770 | members. You have to define it each time you include one of the files, |
3111 | members. You have to define it each time you include one of the files, |
… | |
… | |
1775 | .Vb 3 |
3116 | .Vb 3 |
1776 | \& #define EV_COMMON \e |
3117 | \& #define EV_COMMON \e |
1777 | \& SV *self; /* contains this struct */ \e |
3118 | \& SV *self; /* contains this struct */ \e |
1778 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
3119 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
1779 | .Ve |
3120 | .Ve |
1780 | .IP "\s-1EV_CB_DECLARE\s0(type)" 4 |
3121 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
1781 | .IX Item "EV_CB_DECLARE(type)" |
3122 | .IX Item "EV_CB_DECLARE (type)" |
1782 | .PD 0 |
3123 | .PD 0 |
1783 | .IP "\s-1EV_CB_INVOKE\s0(watcher,revents)" 4 |
3124 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
1784 | .IX Item "EV_CB_INVOKE(watcher,revents)" |
3125 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
1785 | .IP "ev_set_cb(ev,cb)" 4 |
3126 | .IP "ev_set_cb (ev, cb)" 4 |
1786 | .IX Item "ev_set_cb(ev,cb)" |
3127 | .IX Item "ev_set_cb (ev, cb)" |
1787 | .PD |
3128 | .PD |
1788 | Can be used to change the callback member declaration in each watcher, |
3129 | Can be used to change the callback member declaration in each watcher, |
1789 | and the way callbacks are invoked and set. Must expand to a struct member |
3130 | and the way callbacks are invoked and set. Must expand to a struct member |
1790 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3131 | definition and a statement, respectively. See the \fIev.h\fR header file for |
1791 | their default definitions. One possible use for overriding these is to |
3132 | their default definitions. One possible use for overriding these is to |
1792 | avoid the ev_loop pointer as first argument in all cases, or to use method |
3133 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
1793 | calls instead of plain function calls in \*(C+. |
3134 | method calls instead of plain function calls in \*(C+. |
|
|
3135 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3136 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3137 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
|
|
3138 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3139 | all public symbols, one per line: |
|
|
3140 | .PP |
|
|
3141 | .Vb 2 |
|
|
3142 | \& Symbols.ev for libev proper |
|
|
3143 | \& Symbols.event for the libevent emulation |
|
|
3144 | .Ve |
|
|
3145 | .PP |
|
|
3146 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3147 | multiple versions of libev linked together (which is obviously bad in |
|
|
3148 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3149 | .PP |
|
|
3150 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3151 | include before including \fIev.h\fR: |
|
|
3152 | .PP |
|
|
3153 | .Vb 1 |
|
|
3154 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3155 | .Ve |
|
|
3156 | .PP |
|
|
3157 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3158 | .PP |
|
|
3159 | .Vb 4 |
|
|
3160 | \& #define ev_backend myprefix_ev_backend |
|
|
3161 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3162 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3163 | \& ... |
|
|
3164 | .Ve |
1794 | .Sh "\s-1EXAMPLES\s0" |
3165 | .Sh "\s-1EXAMPLES\s0" |
1795 | .IX Subsection "EXAMPLES" |
3166 | .IX Subsection "EXAMPLES" |
1796 | For a real-world example of a program the includes libev |
3167 | For a real-world example of a program the includes libev |
1797 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3168 | verbatim, you can have a look at the \s-1EV\s0 perl module |
1798 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3169 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
1799 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3170 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
1800 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3171 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
1801 | will be compiled. It is pretty complex because it provides its own header |
3172 | will be compiled. It is pretty complex because it provides its own header |
1802 | file. |
3173 | file. |
1803 | .Sp |
3174 | .PP |
1804 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3175 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
1805 | that everybody includes and which overrides some autoconf choices: |
3176 | that everybody includes and which overrides some configure choices: |
1806 | .Sp |
3177 | .PP |
1807 | .Vb 4 |
3178 | .Vb 9 |
|
|
3179 | \& #define EV_MINIMAL 1 |
1808 | \& #define EV_USE_POLL 0 |
3180 | \& #define EV_USE_POLL 0 |
1809 | \& #define EV_MULTIPLICITY 0 |
3181 | \& #define EV_MULTIPLICITY 0 |
1810 | \& #define EV_PERIODICS 0 |
3182 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3183 | \& #define EV_STAT_ENABLE 0 |
|
|
3184 | \& #define EV_FORK_ENABLE 0 |
1811 | \& #define EV_CONFIG_H <config.h> |
3185 | \& #define EV_CONFIG_H <config.h> |
1812 | .Ve |
3186 | \& #define EV_MINPRI 0 |
1813 | .Sp |
3187 | \& #define EV_MAXPRI 0 |
1814 | .Vb 1 |
3188 | \& |
1815 | \& #include "ev++.h" |
3189 | \& #include "ev++.h" |
1816 | .Ve |
3190 | .Ve |
1817 | .Sp |
3191 | .PP |
1818 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3192 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
1819 | .Sp |
3193 | .PP |
1820 | .Vb 2 |
3194 | .Vb 2 |
1821 | \& #include "ev_cpp.h" |
3195 | \& #include "ev_cpp.h" |
1822 | \& #include "ev.c" |
3196 | \& #include "ev.c" |
1823 | .Ve |
3197 | .Ve |
|
|
3198 | .SH "THREADS AND COROUTINES" |
|
|
3199 | .IX Header "THREADS AND COROUTINES" |
|
|
3200 | .Sh "\s-1THREADS\s0" |
|
|
3201 | .IX Subsection "THREADS" |
|
|
3202 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3203 | means that you can use as many loops as you want in parallel, as long as |
|
|
3204 | only one thread ever calls into one libev function with the same loop |
|
|
3205 | parameter. |
|
|
3206 | .PP |
|
|
3207 | Or put differently: calls with different loop parameters can be done in |
|
|
3208 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3209 | done serially (but can be done from different threads, as long as only one |
|
|
3210 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3211 | per loop). |
|
|
3212 | .PP |
|
|
3213 | If you want to know which design is best for your problem, then I cannot |
|
|
3214 | help you but by giving some generic advice: |
|
|
3215 | .IP "\(bu" 4 |
|
|
3216 | most applications have a main thread: use the default libev loop |
|
|
3217 | in that thread, or create a seperate thread running only the default loop. |
|
|
3218 | .Sp |
|
|
3219 | This helps integrating other libraries or software modules that use libev |
|
|
3220 | themselves and don't care/know about threading. |
|
|
3221 | .IP "\(bu" 4 |
|
|
3222 | one loop per thread is usually a good model. |
|
|
3223 | .Sp |
|
|
3224 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3225 | exists, but it is always a good start. |
|
|
3226 | .IP "\(bu" 4 |
|
|
3227 | other models exist, such as the leader/follower pattern, where one |
|
|
3228 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3229 | .Sp |
|
|
3230 | Chosing a model is hard \- look around, learn, know that usually you cna do |
|
|
3231 | better than you currently do :\-) |
|
|
3232 | .IP "\(bu" 4 |
|
|
3233 | often you need to talk to some other thread which blocks in the |
|
|
3234 | event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other |
|
|
3235 | threads safely (or from signal contexts...). |
|
|
3236 | .Sh "\s-1COROUTINES\s0" |
|
|
3237 | .IX Subsection "COROUTINES" |
|
|
3238 | Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3239 | libev fully supports nesting calls to it's functions from different |
|
|
3240 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3241 | different coroutines and switch freely between both coroutines running the |
|
|
3242 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3243 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3244 | .PP |
|
|
3245 | Care has been invested into making sure that libev does not keep local |
|
|
3246 | state inside \f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow coroutine |
|
|
3247 | switches. |
|
|
3248 | .SH "COMPLEXITIES" |
|
|
3249 | .IX Header "COMPLEXITIES" |
|
|
3250 | In this section the complexities of (many of) the algorithms used inside |
|
|
3251 | libev will be explained. For complexity discussions about backends see the |
|
|
3252 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
|
|
3253 | .PP |
|
|
3254 | All of the following are about amortised time: If an array needs to be |
|
|
3255 | extended, libev needs to realloc and move the whole array, but this |
|
|
3256 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
3257 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3258 | it is much faster and asymptotically approaches constant time. |
|
|
3259 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
|
|
3260 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
3261 | This means that, when you have a watcher that triggers in one hour and |
|
|
3262 | there are 100 watchers that would trigger before that then inserting will |
|
|
3263 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
3264 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
3265 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
3266 | That means that changing a timer costs less than removing/adding them |
|
|
3267 | as only the relative motion in the event queue has to be paid for. |
|
|
3268 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
3269 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
3270 | These just add the watcher into an array or at the head of a list. |
|
|
3271 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
3272 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
|
|
3273 | .PD 0 |
|
|
3274 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
|
|
3275 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3276 | .PD |
|
|
3277 | These watchers are stored in lists then need to be walked to find the |
|
|
3278 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3279 | have many watchers waiting for the same fd or signal). |
|
|
3280 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
|
|
3281 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
3282 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
3283 | fixed position in the storage array. |
|
|
3284 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
|
|
3285 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
|
|
3286 | A change means an I/O watcher gets started or stopped, which requires |
|
|
3287 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3288 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
|
|
3289 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3290 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
3291 | .PD 0 |
|
|
3292 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
3293 | .IX Item "Priority handling: O(number_of_priorities)" |
|
|
3294 | .PD |
|
|
3295 | Priorities are implemented by allocating some space for each |
|
|
3296 | priority. When doing priority-based operations, libev usually has to |
|
|
3297 | linearly search all the priorities, but starting/stopping and activating |
|
|
3298 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3299 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3300 | .IX Item "Sending an ev_async: O(1)" |
|
|
3301 | .PD 0 |
|
|
3302 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3303 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3304 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3305 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3306 | .PD |
|
|
3307 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3308 | calls in the current loop iteration. Checking for async and signal events |
|
|
3309 | involves iterating over all running async watchers or all signal numbers. |
|
|
3310 | .SH "Win32 platform limitations and workarounds" |
|
|
3311 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3312 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3313 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3314 | model. Libev still offers limited functionality on this platform in |
|
|
3315 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3316 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3317 | e.g. cygwin. |
|
|
3318 | .PP |
|
|
3319 | Lifting these limitations would basically require the full |
|
|
3320 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3321 | things, then note that glib does exactly that for you in a very portable |
|
|
3322 | way (note also that glib is the slowest event library known to man). |
|
|
3323 | .PP |
|
|
3324 | There is no supported compilation method available on windows except |
|
|
3325 | embedding it into other applications. |
|
|
3326 | .PP |
|
|
3327 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3328 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3329 | is not recommended (and not reasonable). If your program needs to use |
|
|
3330 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3331 | different implementation for windows, as libev offers the \s-1POSIX\s0 readyness |
|
|
3332 | notification model, which cannot be implemented efficiently on windows |
|
|
3333 | (microsoft monopoly games). |
|
|
3334 | .IP "The winsocket select function" 4 |
|
|
3335 | .IX Item "The winsocket select function" |
|
|
3336 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires |
|
|
3337 | socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select |
|
|
3338 | very inefficient, and also requires a mapping from file descriptors |
|
|
3339 | to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, |
|
|
3340 | \&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor |
|
|
3341 | symbols for more info. |
|
|
3342 | .Sp |
|
|
3343 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3344 | libraries and raw winsocket select is: |
|
|
3345 | .Sp |
|
|
3346 | .Vb 2 |
|
|
3347 | \& #define EV_USE_SELECT 1 |
|
|
3348 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3349 | .Ve |
|
|
3350 | .Sp |
|
|
3351 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3352 | complexity in the O(nA\*^X) range when using win32. |
|
|
3353 | .IP "Limited number of file descriptors" 4 |
|
|
3354 | .IX Item "Limited number of file descriptors" |
|
|
3355 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3356 | .Sp |
|
|
3357 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3358 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
3359 | can only wait for \f(CW64\fR things at the same time internally; microsoft |
|
|
3360 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3361 | previous thread in each. Great). |
|
|
3362 | .Sp |
|
|
3363 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3364 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3365 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3366 | select emulation on windows). |
|
|
3367 | .Sp |
|
|
3368 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3369 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3370 | or something like this inside microsoft). You can increase this by calling |
|
|
3371 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3372 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3373 | libraries. |
|
|
3374 | .Sp |
|
|
3375 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3376 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3377 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3378 | calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
3379 | .SH "PORTABILITY REQUIREMENTS" |
|
|
3380 | .IX Header "PORTABILITY REQUIREMENTS" |
|
|
3381 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3382 | additional extensions: |
|
|
3383 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
3384 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
3385 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
3386 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
3387 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic w.r.t. accesses from different |
|
|
3388 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
3389 | believed to be sufficiently portable. |
|
|
3390 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
3391 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
3392 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
3393 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
|
|
3394 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
|
|
3395 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
|
|
3396 | thread\*(R" or will block signals process-wide, both behaviours would |
|
|
3397 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
|
|
3398 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
|
|
3399 | .Sp |
|
|
3400 | The most portable way to handle signals is to block signals in all threads |
|
|
3401 | except the initial one, and run the default loop in the initial thread as |
|
|
3402 | well. |
|
|
3403 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
|
|
3404 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
|
|
3405 | .IX Item "long must be large enough for common memory allocation sizes" |
|
|
3406 | To improve portability and simplify using libev, libev uses \f(CW\*(C`long\*(C'\fR |
|
|
3407 | internally instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On |
|
|
3408 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3409 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3410 | millions of watchers. |
|
|
3411 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
|
|
3412 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
|
|
3413 | .IX Item "double must hold a time value in seconds with enough accuracy" |
|
|
3414 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
|
|
3415 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3416 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3417 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
|
|
3418 | .PP |
|
|
3419 | If you know of other additional requirements drop me a note. |
1824 | .SH "AUTHOR" |
3420 | .SH "AUTHOR" |
1825 | .IX Header "AUTHOR" |
3421 | .IX Header "AUTHOR" |
1826 | Marc Lehmann <libev@schmorp.de>. |
3422 | Marc Lehmann <libev@schmorp.de>. |
|
|
3423 | .SH "POD ERRORS" |
|
|
3424 | .IX Header "POD ERRORS" |
|
|
3425 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3426 | .IP "Around line 3052:" 4 |
|
|
3427 | .IX Item "Around line 3052:" |
|
|
3428 | You forgot a '=back' before '=head2' |