… | |
… | |
127 | .\} |
127 | .\} |
128 | .rm #[ #] #H #V #F C |
128 | .rm #[ #] #H #V #F C |
129 | .\" ======================================================================== |
129 | .\" ======================================================================== |
130 | .\" |
130 | .\" |
131 | .IX Title ""<STANDARD INPUT>" 1" |
131 | .IX Title ""<STANDARD INPUT>" 1" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-18" "perl v5.8.8" "User Contributed Perl Documentation" |
132 | .TH "<STANDARD INPUT>" 1 "2007-12-09" "perl v5.8.8" "User Contributed Perl Documentation" |
133 | .SH "NAME" |
133 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
134 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
135 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
137 | .Vb 1 |
138 | \& #include <ev.h> |
138 | \& #include <ev.h> |
139 | .Ve |
139 | .Ve |
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140 | .SH "EXAMPLE PROGRAM" |
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141 | .IX Header "EXAMPLE PROGRAM" |
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142 | .Vb 1 |
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143 | \& #include <ev.h> |
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144 | .Ve |
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145 | .PP |
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146 | .Vb 2 |
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147 | \& ev_io stdin_watcher; |
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148 | \& ev_timer timeout_watcher; |
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149 | .Ve |
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150 | .PP |
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151 | .Vb 8 |
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152 | \& /* called when data readable on stdin */ |
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153 | \& static void |
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154 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
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155 | \& { |
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156 | \& /* puts ("stdin ready"); */ |
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157 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
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158 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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159 | \& } |
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160 | .Ve |
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161 | .PP |
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162 | .Vb 6 |
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163 | \& static void |
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164 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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165 | \& { |
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166 | \& /* puts ("timeout"); */ |
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167 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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168 | \& } |
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169 | .Ve |
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170 | .PP |
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171 | .Vb 4 |
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172 | \& int |
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173 | \& main (void) |
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174 | \& { |
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175 | \& struct ev_loop *loop = ev_default_loop (0); |
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176 | .Ve |
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177 | .PP |
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178 | .Vb 3 |
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179 | \& /* initialise an io watcher, then start it */ |
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180 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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181 | \& ev_io_start (loop, &stdin_watcher); |
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182 | .Ve |
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183 | .PP |
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184 | .Vb 3 |
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185 | \& /* simple non-repeating 5.5 second timeout */ |
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186 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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187 | \& ev_timer_start (loop, &timeout_watcher); |
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188 | .Ve |
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189 | .PP |
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190 | .Vb 2 |
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191 | \& /* loop till timeout or data ready */ |
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192 | \& ev_loop (loop, 0); |
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193 | .Ve |
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194 | .PP |
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195 | .Vb 2 |
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196 | \& return 0; |
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197 | \& } |
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198 | .Ve |
140 | .SH "DESCRIPTION" |
199 | .SH "DESCRIPTION" |
141 | .IX Header "DESCRIPTION" |
200 | .IX Header "DESCRIPTION" |
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201 | The newest version of this document is also available as a html-formatted |
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202 | web page you might find easier to navigate when reading it for the first |
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203 | time: <http://cvs.schmorp.de/libev/ev.html>. |
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204 | .PP |
142 | Libev is an event loop: you register interest in certain events (such as a |
205 | 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 |
206 | file descriptor being readable or a timeout occuring), and it will manage |
144 | these event sources and provide your program with events. |
207 | these event sources and provide your program with events. |
145 | .PP |
208 | .PP |
146 | To do this, it must take more or less complete control over your process |
209 | To do this, it must take more or less complete control over your process |
… | |
… | |
151 | watchers\fR, which are relatively small C structures you initialise with the |
214 | 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 |
215 | details of the event, and then hand it over to libev by \fIstarting\fR the |
153 | watcher. |
216 | watcher. |
154 | .SH "FEATURES" |
217 | .SH "FEATURES" |
155 | .IX Header "FEATURES" |
218 | .IX Header "FEATURES" |
156 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
219 | 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 |
220 | 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 |
221 | 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 |
222 | (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 |
223 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
161 | fast (see this benchmark comparing |
224 | (\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). |
225 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
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226 | \&\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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227 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
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228 | (\f(CW\*(C`ev_fork\*(C'\fR). |
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229 | .PP |
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230 | It also is quite fast (see this |
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231 | benchmark comparing it to libevent |
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232 | for example). |
163 | .SH "CONVENTIONS" |
233 | .SH "CONVENTIONS" |
164 | .IX Header "CONVENTIONS" |
234 | .IX Header "CONVENTIONS" |
165 | Libev is very configurable. In this manual the default configuration |
235 | Libev is very configurable. In this manual the default configuration will |
166 | will be described, which supports multiple event loops. For more info |
236 | be described, which supports multiple event loops. For more info about |
167 | about various configuration options please have a look at the file |
237 | various configuration options please have a look at \fB\s-1EMBED\s0\fR section in |
168 | \&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without |
238 | this manual. If libev was configured without support for multiple event |
169 | support for multiple event loops, then all functions taking an initial |
239 | loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR |
170 | argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) |
240 | (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument. |
171 | will not have this argument. |
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172 | .SH "TIME REPRESENTATION" |
241 | .SH "TIME REPRESENTATION" |
173 | .IX Header "TIME REPRESENTATION" |
242 | .IX Header "TIME REPRESENTATION" |
174 | Libev represents time as a single floating point number, representing the |
243 | Libev represents time as a single floating point number, representing the |
175 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
244 | (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 |
245 | 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 |
246 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
178 | to the double type in C. |
247 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
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248 | it, you should treat it as such. |
179 | .SH "GLOBAL FUNCTIONS" |
249 | .SH "GLOBAL FUNCTIONS" |
180 | .IX Header "GLOBAL FUNCTIONS" |
250 | .IX Header "GLOBAL FUNCTIONS" |
181 | These functions can be called anytime, even before initialising the |
251 | These functions can be called anytime, even before initialising the |
182 | library in any way. |
252 | library in any way. |
183 | .IP "ev_tstamp ev_time ()" 4 |
253 | .IP "ev_tstamp ev_time ()" 4 |
… | |
… | |
199 | .Sp |
269 | .Sp |
200 | Usually, it's a good idea to terminate if the major versions mismatch, |
270 | Usually, it's a good idea to terminate if the major versions mismatch, |
201 | as this indicates an incompatible change. Minor versions are usually |
271 | as this indicates an incompatible change. Minor versions are usually |
202 | compatible to older versions, so a larger minor version alone is usually |
272 | compatible to older versions, so a larger minor version alone is usually |
203 | not a problem. |
273 | not a problem. |
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274 | .Sp |
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275 | Example: Make sure we haven't accidentally been linked against the wrong |
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276 | version. |
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277 | .Sp |
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278 | .Vb 3 |
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279 | \& assert (("libev version mismatch", |
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280 | \& ev_version_major () == EV_VERSION_MAJOR |
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281 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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282 | .Ve |
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283 | .IP "unsigned int ev_supported_backends ()" 4 |
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284 | .IX Item "unsigned int ev_supported_backends ()" |
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285 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
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286 | value) compiled into this binary of libev (independent of their |
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287 | availability on the system you are running on). See \f(CW\*(C`ev_default_loop\*(C'\fR for |
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288 | a description of the set values. |
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289 | .Sp |
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290 | Example: make sure we have the epoll method, because yeah this is cool and |
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291 | a must have and can we have a torrent of it please!!!11 |
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292 | .Sp |
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293 | .Vb 2 |
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294 | \& assert (("sorry, no epoll, no sex", |
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295 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
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296 | .Ve |
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297 | .IP "unsigned int ev_recommended_backends ()" 4 |
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298 | .IX Item "unsigned int ev_recommended_backends ()" |
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299 | Return the set of all backends compiled into this binary of libev and also |
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300 | recommended for this platform. This set is often smaller than the one |
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301 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
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302 | most BSDs and will not be autodetected unless you explicitly request it |
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303 | (assuming you know what you are doing). This is the set of backends that |
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304 | libev will probe for if you specify no backends explicitly. |
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305 | .IP "unsigned int ev_embeddable_backends ()" 4 |
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306 | .IX Item "unsigned int ev_embeddable_backends ()" |
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307 | Returns the set of backends that are embeddable in other event loops. This |
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308 | is the theoretical, all\-platform, value. To find which backends |
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309 | might be supported on the current system, you would need to look at |
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310 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
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311 | recommended ones. |
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312 | .Sp |
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313 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
204 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
314 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
205 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
315 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
206 | Sets the allocation function to use (the prototype is similar to the |
316 | Sets the allocation function to use (the prototype is similar \- the |
207 | realloc C function, the semantics are identical). It is used to allocate |
317 | semantics is identical \- to the realloc C function). It is used to |
208 | and free memory (no surprises here). If it returns zero when memory |
318 | allocate and free memory (no surprises here). If it returns zero when |
209 | needs to be allocated, the library might abort or take some potentially |
319 | memory needs to be allocated, the library might abort or take some |
210 | destructive action. The default is your system realloc function. |
320 | potentially destructive action. The default is your system realloc |
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321 | function. |
211 | .Sp |
322 | .Sp |
212 | You could override this function in high-availability programs to, say, |
323 | You could override this function in high-availability programs to, say, |
213 | free some memory if it cannot allocate memory, to use a special allocator, |
324 | free some memory if it cannot allocate memory, to use a special allocator, |
214 | or even to sleep a while and retry until some memory is available. |
325 | or even to sleep a while and retry until some memory is available. |
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326 | .Sp |
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327 | Example: Replace the libev allocator with one that waits a bit and then |
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328 | retries). |
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329 | .Sp |
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330 | .Vb 6 |
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331 | \& static void * |
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332 | \& persistent_realloc (void *ptr, size_t size) |
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333 | \& { |
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334 | \& for (;;) |
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335 | \& { |
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336 | \& void *newptr = realloc (ptr, size); |
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337 | .Ve |
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338 | .Sp |
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339 | .Vb 2 |
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340 | \& if (newptr) |
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341 | \& return newptr; |
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342 | .Ve |
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343 | .Sp |
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344 | .Vb 3 |
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345 | \& sleep (60); |
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346 | \& } |
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347 | \& } |
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348 | .Ve |
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349 | .Sp |
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350 | .Vb 2 |
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351 | \& ... |
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352 | \& ev_set_allocator (persistent_realloc); |
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353 | .Ve |
215 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
354 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
216 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
355 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
217 | Set the callback function to call on a retryable syscall error (such |
356 | Set the callback function to call on a retryable syscall error (such |
218 | as failed select, poll, epoll_wait). The message is a printable string |
357 | as failed select, poll, epoll_wait). The message is a printable string |
219 | indicating the system call or subsystem causing the problem. If this |
358 | indicating the system call or subsystem causing the problem. If this |
220 | callback is set, then libev will expect it to remedy the sitution, no |
359 | callback is set, then libev will expect it to remedy the sitution, no |
221 | matter what, when it returns. That is, libev will generally retry the |
360 | matter what, when it returns. That is, libev will generally retry the |
222 | requested operation, or, if the condition doesn't go away, do bad stuff |
361 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | (such as abort). |
362 | (such as abort). |
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363 | .Sp |
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364 | Example: This is basically the same thing that libev does internally, too. |
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365 | .Sp |
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366 | .Vb 6 |
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367 | \& static void |
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368 | \& fatal_error (const char *msg) |
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369 | \& { |
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370 | \& perror (msg); |
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371 | \& abort (); |
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372 | \& } |
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373 | .Ve |
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374 | .Sp |
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375 | .Vb 2 |
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376 | \& ... |
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377 | \& ev_set_syserr_cb (fatal_error); |
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378 | .Ve |
224 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
379 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
225 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
380 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
226 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
381 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
227 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
382 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
228 | events, and dynamically created loops which do not. |
383 | events, and dynamically created loops which do not. |
… | |
… | |
236 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
391 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
237 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
392 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
238 | This will initialise the default event loop if it hasn't been initialised |
393 | This will initialise the default event loop if it hasn't been initialised |
239 | yet and return it. If the default loop could not be initialised, returns |
394 | yet and return it. If the default loop could not be initialised, returns |
240 | false. If it already was initialised it simply returns it (and ignores the |
395 | false. If it already was initialised it simply returns it (and ignores the |
241 | flags). |
396 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
242 | .Sp |
397 | .Sp |
243 | If you don't know what event loop to use, use the one returned from this |
398 | If you don't know what event loop to use, use the one returned from this |
244 | function. |
399 | function. |
245 | .Sp |
400 | .Sp |
246 | The flags argument can be used to specify special behaviour or specific |
401 | The flags argument can be used to specify special behaviour or specific |
247 | backends to use, and is usually specified as 0 (or \s-1EVFLAG_AUTO\s0). |
402 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
248 | .Sp |
403 | .Sp |
249 | It supports the following flags: |
404 | The following flags are supported: |
250 | .RS 4 |
405 | .RS 4 |
251 | .ie n .IP """EVFLAG_AUTO""" 4 |
406 | .ie n .IP """EVFLAG_AUTO""" 4 |
252 | .el .IP "\f(CWEVFLAG_AUTO\fR" 4 |
407 | .el .IP "\f(CWEVFLAG_AUTO\fR" 4 |
253 | .IX Item "EVFLAG_AUTO" |
408 | .IX Item "EVFLAG_AUTO" |
254 | The default flags value. Use this if you have no clue (it's the right |
409 | The default flags value. Use this if you have no clue (it's the right |
… | |
… | |
260 | or setgid) then libev will \fInot\fR look at the environment variable |
415 | or setgid) then libev will \fInot\fR look at the environment variable |
261 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
416 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
262 | override the flags completely if it is found in the environment. This is |
417 | override the flags completely if it is found in the environment. This is |
263 | useful to try out specific backends to test their performance, or to work |
418 | useful to try out specific backends to test their performance, or to work |
264 | around bugs. |
419 | around bugs. |
|
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420 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
|
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421 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
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422 | .IX Item "EVFLAG_FORKCHECK" |
|
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423 | 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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424 | a fork, you can also make libev check for a fork in each iteration by |
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425 | enabling this flag. |
|
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426 | .Sp |
|
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427 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
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428 | and thus this might slow down your event loop if you do a lot of loop |
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429 | iterations and little real work, but is usually not noticeable (on my |
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430 | Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
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431 | without a syscall and thus \fIvery\fR fast, but my Linux system also has |
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432 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
|
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433 | .Sp |
|
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434 | The big advantage of this flag is that you can forget about fork (and |
|
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435 | forget about forgetting to tell libev about forking) when you use this |
|
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436 | flag. |
|
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437 | .Sp |
|
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438 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
|
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439 | environment variable. |
265 | .ie n .IP """EVMETHOD_SELECT"" (portable select backend)" 4 |
440 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
266 | .el .IP "\f(CWEVMETHOD_SELECT\fR (portable select backend)" 4 |
441 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
267 | .IX Item "EVMETHOD_SELECT (portable select backend)" |
442 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
268 | .PD 0 |
443 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
|
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444 | libev tries to roll its own fd_set with no limits on the number of fds, |
|
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445 | but if that fails, expect a fairly low limit on the number of fds when |
|
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446 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
|
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447 | the fastest backend for a low number of fds. |
269 | .ie n .IP """EVMETHOD_POLL"" (poll backend, available everywhere except on windows)" 4 |
448 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
270 | .el .IP "\f(CWEVMETHOD_POLL\fR (poll backend, available everywhere except on windows)" 4 |
449 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
271 | .IX Item "EVMETHOD_POLL (poll backend, available everywhere except on windows)" |
450 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
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451 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
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452 | select, but handles sparse fds better and has no artificial limit on the |
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453 | number of fds you can use (except it will slow down considerably with a |
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454 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
272 | .ie n .IP """EVMETHOD_EPOLL"" (linux only)" 4 |
455 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
273 | .el .IP "\f(CWEVMETHOD_EPOLL\fR (linux only)" 4 |
456 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
274 | .IX Item "EVMETHOD_EPOLL (linux only)" |
457 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
275 | .ie n .IP """EVMETHOD_KQUEUE"" (some bsds only)" 4 |
458 | For few fds, this backend is a bit little slower than poll and select, |
276 | .el .IP "\f(CWEVMETHOD_KQUEUE\fR (some bsds only)" 4 |
459 | but it scales phenomenally better. While poll and select usually scale like |
277 | .IX Item "EVMETHOD_KQUEUE (some bsds only)" |
460 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
|
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461 | either O(1) or O(active_fds). |
|
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462 | .Sp |
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463 | While stopping and starting an I/O watcher in the same iteration will |
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464 | result in some caching, there is still a syscall per such incident |
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465 | (because the fd could point to a different file description now), so its |
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466 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
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467 | well if you register events for both fds. |
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|
468 | .Sp |
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469 | Please note that epoll sometimes generates spurious notifications, so you |
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470 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
471 | (or space) is available. |
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|
472 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
|
|
473 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
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474 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
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475 | Kqueue deserves special mention, as at the time of this writing, it |
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476 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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477 | anything but sockets and pipes, except on Darwin, where of course its |
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478 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
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479 | unless you explicitly specify it explicitly in the flags (i.e. using |
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480 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
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481 | .Sp |
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482 | It scales in the same way as the epoll backend, but the interface to the |
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483 | kernel is more efficient (which says nothing about its actual speed, of |
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484 | course). While starting and stopping an I/O watcher does not cause an |
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485 | extra syscall as with epoll, it still adds up to four event changes per |
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486 | incident, so its best to avoid that. |
278 | .ie n .IP """EVMETHOD_DEVPOLL"" (solaris 8 only)" 4 |
487 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
279 | .el .IP "\f(CWEVMETHOD_DEVPOLL\fR (solaris 8 only)" 4 |
488 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
280 | .IX Item "EVMETHOD_DEVPOLL (solaris 8 only)" |
489 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
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490 | This is not implemented yet (and might never be). |
281 | .ie n .IP """EVMETHOD_PORT"" (solaris 10 only)" 4 |
491 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
282 | .el .IP "\f(CWEVMETHOD_PORT\fR (solaris 10 only)" 4 |
492 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
283 | .IX Item "EVMETHOD_PORT (solaris 10 only)" |
493 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
284 | .PD |
494 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
285 | If one or more of these are ored into the flags value, then only these |
495 | it's really slow, but it still scales very well (O(active_fds)). |
286 | backends will be tried (in the reverse order as given here). If one are |
496 | .Sp |
287 | specified, any backend will do. |
497 | Please note that solaris ports can result in a lot of spurious |
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498 | notifications, so you need to use non-blocking I/O or other means to avoid |
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499 | blocking when no data (or space) is available. |
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500 | .ie n .IP """EVBACKEND_ALL""" 4 |
|
|
501 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
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502 | .IX Item "EVBACKEND_ALL" |
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503 | Try all backends (even potentially broken ones that wouldn't be tried |
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504 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
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505 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
288 | .RE |
506 | .RE |
289 | .RS 4 |
507 | .RS 4 |
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|
508 | .Sp |
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509 | If one or more of these are ored into the flags value, then only these |
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510 | backends will be tried (in the reverse order as given here). If none are |
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511 | specified, most compiled-in backend will be tried, usually in reverse |
|
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512 | order of their flag values :) |
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|
513 | .Sp |
|
|
514 | The most typical usage is like this: |
|
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515 | .Sp |
|
|
516 | .Vb 2 |
|
|
517 | \& if (!ev_default_loop (0)) |
|
|
518 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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519 | .Ve |
|
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520 | .Sp |
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|
521 | Restrict libev to the select and poll backends, and do not allow |
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522 | environment settings to be taken into account: |
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523 | .Sp |
|
|
524 | .Vb 1 |
|
|
525 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
526 | .Ve |
|
|
527 | .Sp |
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528 | Use whatever libev has to offer, but make sure that kqueue is used if |
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529 | available (warning, breaks stuff, best use only with your own private |
|
|
530 | event loop and only if you know the \s-1OS\s0 supports your types of fds): |
|
|
531 | .Sp |
|
|
532 | .Vb 1 |
|
|
533 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
534 | .Ve |
290 | .RE |
535 | .RE |
291 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
536 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
292 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
537 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
293 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
538 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
294 | always distinct from the default loop. Unlike the default loop, it cannot |
539 | always distinct from the default loop. Unlike the default loop, it cannot |
295 | handle signal and child watchers, and attempts to do so will be greeted by |
540 | handle signal and child watchers, and attempts to do so will be greeted by |
296 | undefined behaviour (or a failed assertion if assertions are enabled). |
541 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
542 | .Sp |
|
|
543 | Example: Try to create a event loop that uses epoll and nothing else. |
|
|
544 | .Sp |
|
|
545 | .Vb 3 |
|
|
546 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
547 | \& if (!epoller) |
|
|
548 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
549 | .Ve |
297 | .IP "ev_default_destroy ()" 4 |
550 | .IP "ev_default_destroy ()" 4 |
298 | .IX Item "ev_default_destroy ()" |
551 | .IX Item "ev_default_destroy ()" |
299 | Destroys the default loop again (frees all memory and kernel state |
552 | Destroys the default loop again (frees all memory and kernel state |
300 | etc.). This stops all registered event watchers (by not touching them in |
553 | etc.). None of the active event watchers will be stopped in the normal |
301 | any way whatsoever, although you cannot rely on this :). |
554 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
|
|
555 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
|
|
556 | calling this function, or cope with the fact afterwards (which is usually |
|
|
557 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
|
|
558 | for example). |
302 | .IP "ev_loop_destroy (loop)" 4 |
559 | .IP "ev_loop_destroy (loop)" 4 |
303 | .IX Item "ev_loop_destroy (loop)" |
560 | .IX Item "ev_loop_destroy (loop)" |
304 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
561 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
305 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
562 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
306 | .IP "ev_default_fork ()" 4 |
563 | .IP "ev_default_fork ()" 4 |
… | |
… | |
308 | This function reinitialises the kernel state for backends that have |
565 | This function reinitialises the kernel state for backends that have |
309 | one. Despite the name, you can call it anytime, but it makes most sense |
566 | one. Despite the name, you can call it anytime, but it makes most sense |
310 | after forking, in either the parent or child process (or both, but that |
567 | after forking, in either the parent or child process (or both, but that |
311 | again makes little sense). |
568 | again makes little sense). |
312 | .Sp |
569 | .Sp |
313 | You \fImust\fR call this function after forking if and only if you want to |
570 | You \fImust\fR call this function in the child process after forking if and |
314 | use the event library in both processes. If you just fork+exec, you don't |
571 | only if you want to use the event library in both processes. If you just |
315 | have to call it. |
572 | fork+exec, you don't have to call it. |
316 | .Sp |
573 | .Sp |
317 | The function itself is quite fast and it's usually not a problem to call |
574 | The function itself is quite fast and it's usually not a problem to call |
318 | it just in case after a fork. To make this easy, the function will fit in |
575 | it just in case after a fork. To make this easy, the function will fit in |
319 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
576 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
320 | .Sp |
577 | .Sp |
321 | .Vb 1 |
578 | .Vb 1 |
322 | \& pthread_atfork (0, 0, ev_default_fork); |
579 | \& pthread_atfork (0, 0, ev_default_fork); |
323 | .Ve |
580 | .Ve |
|
|
581 | .Sp |
|
|
582 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
583 | without calling this function, so if you force one of those backends you |
|
|
584 | do not need to care. |
324 | .IP "ev_loop_fork (loop)" 4 |
585 | .IP "ev_loop_fork (loop)" 4 |
325 | .IX Item "ev_loop_fork (loop)" |
586 | .IX Item "ev_loop_fork (loop)" |
326 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
587 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
327 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
588 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
328 | after fork, and how you do this is entirely your own problem. |
589 | after fork, and how you do this is entirely your own problem. |
|
|
590 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
591 | .IX Item "unsigned int ev_loop_count (loop)" |
|
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592 | Returns the count of loop iterations for the loop, which is identical to |
|
|
593 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
594 | happily wraps around with enough iterations. |
|
|
595 | .Sp |
|
|
596 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
597 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
598 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
329 | .IP "unsigned int ev_method (loop)" 4 |
599 | .IP "unsigned int ev_backend (loop)" 4 |
330 | .IX Item "unsigned int ev_method (loop)" |
600 | .IX Item "unsigned int ev_backend (loop)" |
331 | Returns one of the \f(CW\*(C`EVMETHOD_*\*(C'\fR flags indicating the event backend in |
601 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
332 | use. |
602 | use. |
333 | .IP "ev_tstamp ev_now (loop)" 4 |
603 | .IP "ev_tstamp ev_now (loop)" 4 |
334 | .IX Item "ev_tstamp ev_now (loop)" |
604 | .IX Item "ev_tstamp ev_now (loop)" |
335 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
605 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
336 | got events and started processing them. This timestamp does not change |
606 | received events and started processing them. This timestamp does not |
337 | as long as callbacks are being processed, and this is also the base time |
607 | change as long as callbacks are being processed, and this is also the base |
338 | used for relative timers. You can treat it as the timestamp of the event |
608 | time used for relative timers. You can treat it as the timestamp of the |
339 | occuring (or more correctly, the mainloop finding out about it). |
609 | event occuring (or more correctly, libev finding out about it). |
340 | .IP "ev_loop (loop, int flags)" 4 |
610 | .IP "ev_loop (loop, int flags)" 4 |
341 | .IX Item "ev_loop (loop, int flags)" |
611 | .IX Item "ev_loop (loop, int flags)" |
342 | Finally, this is it, the event handler. This function usually is called |
612 | Finally, this is it, the event handler. This function usually is called |
343 | after you initialised all your watchers and you want to start handling |
613 | after you initialised all your watchers and you want to start handling |
344 | events. |
614 | events. |
345 | .Sp |
615 | .Sp |
346 | If the flags argument is specified as 0, it will not return until either |
616 | If the flags argument is specified as \f(CW0\fR, it will not return until |
347 | no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
617 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
|
|
618 | .Sp |
|
|
619 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
|
|
620 | relying on all watchers to be stopped when deciding when a program has |
|
|
621 | finished (especially in interactive programs), but having a program that |
|
|
622 | automatically loops as long as it has to and no longer by virtue of |
|
|
623 | relying on its watchers stopping correctly is a thing of beauty. |
348 | .Sp |
624 | .Sp |
349 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
625 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
350 | those events and any outstanding ones, but will not block your process in |
626 | those events and any outstanding ones, but will not block your process in |
351 | case there are no events and will return after one iteration of the loop. |
627 | case there are no events and will return after one iteration of the loop. |
352 | .Sp |
628 | .Sp |
353 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
629 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
354 | neccessary) and will handle those and any outstanding ones. It will block |
630 | neccessary) and will handle those and any outstanding ones. It will block |
355 | your process until at least one new event arrives, and will return after |
631 | your process until at least one new event arrives, and will return after |
356 | one iteration of the loop. |
632 | one iteration of the loop. This is useful if you are waiting for some |
|
|
633 | external event in conjunction with something not expressible using other |
|
|
634 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
|
|
635 | usually a better approach for this kind of thing. |
357 | .Sp |
636 | .Sp |
358 | This flags value could be used to implement alternative looping |
|
|
359 | constructs, but the \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`check\*(C'\fR watchers provide a better and |
|
|
360 | more generic mechanism. |
|
|
361 | .Sp |
|
|
362 | Here are the gory details of what ev_loop does: |
637 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
363 | .Sp |
638 | .Sp |
364 | .Vb 15 |
639 | .Vb 19 |
|
|
640 | \& - Before the first iteration, call any pending watchers. |
365 | \& 1. If there are no active watchers (reference count is zero), return. |
641 | \& * If there are no active watchers (reference count is zero), return. |
366 | \& 2. Queue and immediately call all prepare watchers. |
642 | \& - Queue all prepare watchers and then call all outstanding watchers. |
367 | \& 3. If we have been forked, recreate the kernel state. |
643 | \& - If we have been forked, recreate the kernel state. |
368 | \& 4. Update the kernel state with all outstanding changes. |
644 | \& - Update the kernel state with all outstanding changes. |
369 | \& 5. Update the "event loop time". |
645 | \& - Update the "event loop time". |
370 | \& 6. Calculate for how long to block. |
646 | \& - Calculate for how long to block. |
371 | \& 7. Block the process, waiting for events. |
647 | \& - Block the process, waiting for any events. |
|
|
648 | \& - Queue all outstanding I/O (fd) events. |
372 | \& 8. Update the "event loop time" and do time jump handling. |
649 | \& - Update the "event loop time" and do time jump handling. |
373 | \& 9. Queue all outstanding timers. |
650 | \& - Queue all outstanding timers. |
374 | \& 10. Queue all outstanding periodics. |
651 | \& - Queue all outstanding periodics. |
375 | \& 11. If no events are pending now, queue all idle watchers. |
652 | \& - If no events are pending now, queue all idle watchers. |
376 | \& 12. Queue all check watchers. |
653 | \& - Queue all check watchers. |
377 | \& 13. Call all queued watchers in reverse order (i.e. check watchers first). |
654 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
655 | \& Signals and child watchers are implemented as I/O watchers, and will |
|
|
656 | \& be handled here by queueing them when their watcher gets executed. |
378 | \& 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
657 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
379 | \& was used, return, otherwise continue with step #1. |
658 | \& were used, return, otherwise continue with step *. |
|
|
659 | .Ve |
|
|
660 | .Sp |
|
|
661 | Example: Queue some jobs and then loop until no events are outsanding |
|
|
662 | anymore. |
|
|
663 | .Sp |
|
|
664 | .Vb 4 |
|
|
665 | \& ... queue jobs here, make sure they register event watchers as long |
|
|
666 | \& ... as they still have work to do (even an idle watcher will do..) |
|
|
667 | \& ev_loop (my_loop, 0); |
|
|
668 | \& ... jobs done. yeah! |
380 | .Ve |
669 | .Ve |
381 | .IP "ev_unloop (loop, how)" 4 |
670 | .IP "ev_unloop (loop, how)" 4 |
382 | .IX Item "ev_unloop (loop, how)" |
671 | .IX Item "ev_unloop (loop, how)" |
383 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
672 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
384 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
673 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
… | |
… | |
398 | example, libev itself uses this for its internal signal pipe: It is not |
687 | example, libev itself uses this for its internal signal pipe: It is not |
399 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
688 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
400 | no event watchers registered by it are active. It is also an excellent |
689 | no event watchers registered by it are active. It is also an excellent |
401 | way to do this for generic recurring timers or from within third-party |
690 | way to do this for generic recurring timers or from within third-party |
402 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
691 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
|
|
692 | .Sp |
|
|
693 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
|
|
694 | running when nothing else is active. |
|
|
695 | .Sp |
|
|
696 | .Vb 4 |
|
|
697 | \& struct ev_signal exitsig; |
|
|
698 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
699 | \& ev_signal_start (loop, &exitsig); |
|
|
700 | \& evf_unref (loop); |
|
|
701 | .Ve |
|
|
702 | .Sp |
|
|
703 | Example: For some weird reason, unregister the above signal handler again. |
|
|
704 | .Sp |
|
|
705 | .Vb 2 |
|
|
706 | \& ev_ref (loop); |
|
|
707 | \& ev_signal_stop (loop, &exitsig); |
|
|
708 | .Ve |
403 | .SH "ANATOMY OF A WATCHER" |
709 | .SH "ANATOMY OF A WATCHER" |
404 | .IX Header "ANATOMY OF A WATCHER" |
710 | .IX Header "ANATOMY OF A WATCHER" |
405 | A watcher is a structure that you create and register to record your |
711 | A watcher is a structure that you create and register to record your |
406 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
712 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
407 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
713 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
443 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
749 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
444 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
750 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
445 | .PP |
751 | .PP |
446 | As long as your watcher is active (has been started but not stopped) you |
752 | As long as your watcher is active (has been started but not stopped) you |
447 | must not touch the values stored in it. Most specifically you must never |
753 | must not touch the values stored in it. Most specifically you must never |
448 | reinitialise it or call its set method. |
754 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
449 | .PP |
|
|
450 | You can check whether an event is active by calling the \f(CW\*(C`ev_is_active |
|
|
451 | (watcher *)\*(C'\fR macro. To see whether an event is outstanding (but the |
|
|
452 | callback for it has not been called yet) you can use the \f(CW\*(C`ev_is_pending |
|
|
453 | (watcher *)\*(C'\fR macro. |
|
|
454 | .PP |
755 | .PP |
455 | Each and every callback receives the event loop pointer as first, the |
756 | Each and every callback receives the event loop pointer as first, the |
456 | registered watcher structure as second, and a bitset of received events as |
757 | registered watcher structure as second, and a bitset of received events as |
457 | third argument. |
758 | third argument. |
458 | .PP |
759 | .PP |
… | |
… | |
483 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
784 | The signal specified in the \f(CW\*(C`ev_signal\*(C'\fR watcher has been received by a thread. |
484 | .ie n .IP """EV_CHILD""" 4 |
785 | .ie n .IP """EV_CHILD""" 4 |
485 | .el .IP "\f(CWEV_CHILD\fR" 4 |
786 | .el .IP "\f(CWEV_CHILD\fR" 4 |
486 | .IX Item "EV_CHILD" |
787 | .IX Item "EV_CHILD" |
487 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
788 | The pid specified in the \f(CW\*(C`ev_child\*(C'\fR watcher has received a status change. |
|
|
789 | .ie n .IP """EV_STAT""" 4 |
|
|
790 | .el .IP "\f(CWEV_STAT\fR" 4 |
|
|
791 | .IX Item "EV_STAT" |
|
|
792 | The path specified in the \f(CW\*(C`ev_stat\*(C'\fR watcher changed its attributes somehow. |
488 | .ie n .IP """EV_IDLE""" 4 |
793 | .ie n .IP """EV_IDLE""" 4 |
489 | .el .IP "\f(CWEV_IDLE\fR" 4 |
794 | .el .IP "\f(CWEV_IDLE\fR" 4 |
490 | .IX Item "EV_IDLE" |
795 | .IX Item "EV_IDLE" |
491 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
796 | The \f(CW\*(C`ev_idle\*(C'\fR watcher has determined that you have nothing better to do. |
492 | .ie n .IP """EV_PREPARE""" 4 |
797 | .ie n .IP """EV_PREPARE""" 4 |
… | |
… | |
502 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
807 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
503 | received events. Callbacks of both watcher types can start and stop as |
808 | received events. Callbacks of both watcher types can start and stop as |
504 | many watchers as they want, and all of them will be taken into account |
809 | many watchers as they want, and all of them will be taken into account |
505 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
810 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
506 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
811 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
|
|
812 | .ie n .IP """EV_EMBED""" 4 |
|
|
813 | .el .IP "\f(CWEV_EMBED\fR" 4 |
|
|
814 | .IX Item "EV_EMBED" |
|
|
815 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
|
|
816 | .ie n .IP """EV_FORK""" 4 |
|
|
817 | .el .IP "\f(CWEV_FORK\fR" 4 |
|
|
818 | .IX Item "EV_FORK" |
|
|
819 | The event loop has been resumed in the child process after fork (see |
|
|
820 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
507 | .ie n .IP """EV_ERROR""" 4 |
821 | .ie n .IP """EV_ERROR""" 4 |
508 | .el .IP "\f(CWEV_ERROR\fR" 4 |
822 | .el .IP "\f(CWEV_ERROR\fR" 4 |
509 | .IX Item "EV_ERROR" |
823 | .IX Item "EV_ERROR" |
510 | An unspecified error has occured, the watcher has been stopped. This might |
824 | An unspecified error has occured, the watcher has been stopped. This might |
511 | happen because the watcher could not be properly started because libev |
825 | happen because the watcher could not be properly started because libev |
… | |
… | |
516 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
830 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
517 | for example it might indicate that a fd is readable or writable, and if |
831 | for example it might indicate that a fd is readable or writable, and if |
518 | your callbacks is well-written it can just attempt the operation and cope |
832 | your callbacks is well-written it can just attempt the operation and cope |
519 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
833 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
520 | programs, though, so beware. |
834 | programs, though, so beware. |
|
|
835 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
|
|
836 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
|
|
837 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
838 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
839 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
|
|
840 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
|
|
841 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
|
|
842 | This macro initialises the generic portion of a watcher. The contents |
|
|
843 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
|
|
844 | the generic parts of the watcher are initialised, you \fIneed\fR to call |
|
|
845 | the type-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR macro afterwards to initialise the |
|
|
846 | type-specific parts. For each type there is also a \f(CW\*(C`ev_TYPE_init\*(C'\fR macro |
|
|
847 | which rolls both calls into one. |
|
|
848 | .Sp |
|
|
849 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
850 | (or never started) and there are no pending events outstanding. |
|
|
851 | .Sp |
|
|
852 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
853 | int revents)\*(C'\fR. |
|
|
854 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
|
|
855 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
|
|
856 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
|
|
857 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
858 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
|
|
859 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
|
|
860 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
861 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
|
|
862 | .Sp |
|
|
863 | Although some watcher types do not have type-specific arguments |
|
|
864 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
|
|
865 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
|
|
866 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
|
|
867 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
|
|
868 | This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
|
|
869 | calls into a single call. This is the most convinient method to initialise |
|
|
870 | a watcher. The same limitations apply, of course. |
|
|
871 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
|
|
872 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
|
|
873 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
|
|
874 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
875 | events. If the watcher is already active nothing will happen. |
|
|
876 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
|
|
877 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
|
|
878 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
|
|
879 | Stops the given watcher again (if active) and clears the pending |
|
|
880 | status. It is possible that stopped watchers are pending (for example, |
|
|
881 | non-repeating timers are being stopped when they become pending), but |
|
|
882 | \&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If |
|
|
883 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
884 | good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
|
|
885 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
|
|
886 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
|
|
887 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
888 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
889 | it. |
|
|
890 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
|
|
891 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
|
|
892 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
893 | events but its callback has not yet been invoked). As long as a watcher |
|
|
894 | is pending (but not active) you must not call an init function on it (but |
|
|
895 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
|
|
896 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
897 | it). |
|
|
898 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
|
|
899 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
|
|
900 | Returns the callback currently set on the watcher. |
|
|
901 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
|
|
902 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
|
|
903 | Change the callback. You can change the callback at virtually any time |
|
|
904 | (modulo threads). |
|
|
905 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
906 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
907 | .PD 0 |
|
|
908 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
909 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
910 | .PD |
|
|
911 | Set and query the priority of the watcher. The priority is a small |
|
|
912 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
913 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
914 | before watchers with lower priority, but priority will not keep watchers |
|
|
915 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
916 | .Sp |
|
|
917 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
918 | invocation after new events have been received. This is useful, for |
|
|
919 | example, to reduce latency after idling, or more often, to bind two |
|
|
920 | watchers on the same event and make sure one is called first. |
|
|
921 | .Sp |
|
|
922 | If you need to suppress invocation when higher priority events are pending |
|
|
923 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
924 | .Sp |
|
|
925 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
926 | pending. |
|
|
927 | .Sp |
|
|
928 | The default priority used by watchers when no priority has been set is |
|
|
929 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
930 | .Sp |
|
|
931 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
932 | fine, as long as you do not mind that the priority value you query might |
|
|
933 | or might not have been adjusted to be within valid range. |
|
|
934 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
935 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
936 | 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 |
|
|
937 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
938 | can deal with that fact. |
|
|
939 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
940 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
941 | If the watcher is pending, this function returns clears its pending status |
|
|
942 | and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
943 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
521 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
944 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
522 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
945 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
523 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
946 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
524 | and read at any time, libev will completely ignore it. This can be used |
947 | and read at any time, libev will completely ignore it. This can be used |
525 | to associate arbitrary data with your watcher. If you need more data and |
948 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
546 | \& struct my_io *w = (struct my_io *)w_; |
969 | \& struct my_io *w = (struct my_io *)w_; |
547 | \& ... |
970 | \& ... |
548 | \& } |
971 | \& } |
549 | .Ve |
972 | .Ve |
550 | .PP |
973 | .PP |
551 | More interesting and less C\-conformant ways of catsing your callback type |
974 | More interesting and less C\-conformant ways of casting your callback type |
552 | have been omitted.... |
975 | instead have been omitted. |
|
|
976 | .PP |
|
|
977 | Another common scenario is having some data structure with multiple |
|
|
978 | watchers: |
|
|
979 | .PP |
|
|
980 | .Vb 6 |
|
|
981 | \& struct my_biggy |
|
|
982 | \& { |
|
|
983 | \& int some_data; |
|
|
984 | \& ev_timer t1; |
|
|
985 | \& ev_timer t2; |
|
|
986 | \& } |
|
|
987 | .Ve |
|
|
988 | .PP |
|
|
989 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
|
|
990 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
|
|
991 | .PP |
|
|
992 | .Vb 1 |
|
|
993 | \& #include <stddef.h> |
|
|
994 | .Ve |
|
|
995 | .PP |
|
|
996 | .Vb 6 |
|
|
997 | \& static void |
|
|
998 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
999 | \& { |
|
|
1000 | \& struct my_biggy big = (struct my_biggy * |
|
|
1001 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
1002 | \& } |
|
|
1003 | .Ve |
|
|
1004 | .PP |
|
|
1005 | .Vb 6 |
|
|
1006 | \& static void |
|
|
1007 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
1008 | \& { |
|
|
1009 | \& struct my_biggy big = (struct my_biggy * |
|
|
1010 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
1011 | \& } |
|
|
1012 | .Ve |
553 | .SH "WATCHER TYPES" |
1013 | .SH "WATCHER TYPES" |
554 | .IX Header "WATCHER TYPES" |
1014 | .IX Header "WATCHER TYPES" |
555 | This section describes each watcher in detail, but will not repeat |
1015 | This section describes each watcher in detail, but will not repeat |
556 | information given in the last section. |
1016 | information given in the last section. Any initialisation/set macros, |
|
|
1017 | functions and members specific to the watcher type are explained. |
|
|
1018 | .PP |
|
|
1019 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
|
|
1020 | while the watcher is active, you can look at the member and expect some |
|
|
1021 | sensible content, but you must not modify it (you can modify it while the |
|
|
1022 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
|
|
1023 | means you can expect it to have some sensible content while the watcher |
|
|
1024 | is active, but you can also modify it. Modifying it may not do something |
|
|
1025 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
1026 | not crash or malfunction in any way. |
557 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable" |
1027 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
558 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable" |
1028 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
559 | .IX Subsection "ev_io - is this file descriptor readable or writable" |
1029 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
560 | I/O watchers check whether a file descriptor is readable or writable |
1030 | I/O watchers check whether a file descriptor is readable or writable |
561 | in each iteration of the event loop (This behaviour is called |
1031 | in each iteration of the event loop, or, more precisely, when reading |
562 | level-triggering because you keep receiving events as long as the |
1032 | would not block the process and writing would at least be able to write |
563 | condition persists. Remember you can stop the watcher if you don't want to |
1033 | some data. This behaviour is called level-triggering because you keep |
564 | act on the event and neither want to receive future events). |
1034 | receiving events as long as the condition persists. Remember you can stop |
|
|
1035 | the watcher if you don't want to act on the event and neither want to |
|
|
1036 | receive future events. |
565 | .PP |
1037 | .PP |
566 | In general you can register as many read and/or write event watchers per |
1038 | In general you can register as many read and/or write event watchers per |
567 | fd as you want (as long as you don't confuse yourself). Setting all file |
1039 | fd as you want (as long as you don't confuse yourself). Setting all file |
568 | descriptors to non-blocking mode is also usually a good idea (but not |
1040 | descriptors to non-blocking mode is also usually a good idea (but not |
569 | required if you know what you are doing). |
1041 | required if you know what you are doing). |
570 | .PP |
1042 | .PP |
571 | You have to be careful with dup'ed file descriptors, though. Some backends |
1043 | You have to be careful with dup'ed file descriptors, though. Some backends |
572 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
1044 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
573 | descriptors correctly if you register interest in two or more fds pointing |
1045 | descriptors correctly if you register interest in two or more fds pointing |
574 | to the same underlying file/socket etc. description (that is, they share |
1046 | to the same underlying file/socket/etc. description (that is, they share |
575 | the same underlying \*(L"file open\*(R"). |
1047 | the same underlying \*(L"file open\*(R"). |
576 | .PP |
1048 | .PP |
577 | If you must do this, then force the use of a known-to-be-good backend |
1049 | If you must do this, then force the use of a known-to-be-good backend |
578 | (at the time of this writing, this includes only \s-1EVMETHOD_SELECT\s0 and |
1050 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
579 | \&\s-1EVMETHOD_POLL\s0). |
1051 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
1052 | .PP |
|
|
1053 | Another thing you have to watch out for is that it is quite easy to |
|
|
1054 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
|
|
1055 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
|
|
1056 | because there is no data. Not only are some backends known to create a |
|
|
1057 | lot of those (for example solaris ports), it is very easy to get into |
|
|
1058 | this situation even with a relatively standard program structure. Thus |
|
|
1059 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1060 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
|
|
1061 | .PP |
|
|
1062 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
1063 | play around with an Xlib connection), then you have to seperately re-test |
|
|
1064 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
1065 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
1066 | its own, so its quite safe to use). |
580 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1067 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
581 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1068 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
582 | .PD 0 |
1069 | .PD 0 |
583 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1070 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
584 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1071 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
585 | .PD |
1072 | .PD |
586 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive |
1073 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
587 | events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | |
1074 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
588 | EV_WRITE\*(C'\fR to receive the given events. |
1075 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
|
|
1076 | .IP "int fd [read\-only]" 4 |
|
|
1077 | .IX Item "int fd [read-only]" |
|
|
1078 | The file descriptor being watched. |
|
|
1079 | .IP "int events [read\-only]" 4 |
|
|
1080 | .IX Item "int events [read-only]" |
|
|
1081 | The events being watched. |
|
|
1082 | .PP |
|
|
1083 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
|
|
1084 | readable, but only once. Since it is likely line\-buffered, you could |
|
|
1085 | attempt to read a whole line in the callback. |
|
|
1086 | .PP |
|
|
1087 | .Vb 6 |
|
|
1088 | \& static void |
|
|
1089 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1090 | \& { |
|
|
1091 | \& ev_io_stop (loop, w); |
|
|
1092 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
1093 | \& } |
|
|
1094 | .Ve |
|
|
1095 | .PP |
|
|
1096 | .Vb 6 |
|
|
1097 | \& ... |
|
|
1098 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
1099 | \& struct ev_io stdin_readable; |
|
|
1100 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
1101 | \& ev_io_start (loop, &stdin_readable); |
|
|
1102 | \& ev_loop (loop, 0); |
|
|
1103 | .Ve |
589 | .ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" |
1104 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
590 | .el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" |
1105 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
591 | .IX Subsection "ev_timer - relative and optionally recurring timeouts" |
1106 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
592 | Timer watchers are simple relative timers that generate an event after a |
1107 | Timer watchers are simple relative timers that generate an event after a |
593 | given time, and optionally repeating in regular intervals after that. |
1108 | given time, and optionally repeating in regular intervals after that. |
594 | .PP |
1109 | .PP |
595 | The timers are based on real time, that is, if you register an event that |
1110 | The timers are based on real time, that is, if you register an event that |
596 | times out after an hour and you reset your system clock to last years |
1111 | times out after an hour and you reset your system clock to last years |
… | |
… | |
630 | .IP "ev_timer_again (loop)" 4 |
1145 | .IP "ev_timer_again (loop)" 4 |
631 | .IX Item "ev_timer_again (loop)" |
1146 | .IX Item "ev_timer_again (loop)" |
632 | This will act as if the timer timed out and restart it again if it is |
1147 | This will act as if the timer timed out and restart it again if it is |
633 | repeating. The exact semantics are: |
1148 | repeating. The exact semantics are: |
634 | .Sp |
1149 | .Sp |
|
|
1150 | If the timer is pending, its pending status is cleared. |
|
|
1151 | .Sp |
635 | If the timer is started but nonrepeating, stop it. |
1152 | If the timer is started but nonrepeating, stop it (as if it timed out). |
636 | .Sp |
1153 | .Sp |
637 | If the timer is repeating, either start it if necessary (with the repeat |
1154 | If the timer is repeating, either start it if necessary (with the |
638 | value), or reset the running timer to the repeat value. |
1155 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
639 | .Sp |
1156 | .Sp |
640 | This sounds a bit complicated, but here is a useful and typical |
1157 | This sounds a bit complicated, but here is a useful and typical |
641 | example: Imagine you have a tcp connection and you want a so-called idle |
1158 | example: Imagine you have a tcp connection and you want a so-called idle |
642 | timeout, that is, you want to be called when there have been, say, 60 |
1159 | timeout, that is, you want to be called when there have been, say, 60 |
643 | seconds of inactivity on the socket. The easiest way to do this is to |
1160 | seconds of inactivity on the socket. The easiest way to do this is to |
644 | configure an \f(CW\*(C`ev_timer\*(C'\fR with after=repeat=60 and calling ev_timer_again each |
1161 | 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 |
645 | time you successfully read or write some data. If you go into an idle |
1162 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
646 | state where you do not expect data to travel on the socket, you can stop |
1163 | you go into an idle state where you do not expect data to travel on the |
647 | the timer, and again will automatically restart it if need be. |
1164 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
|
|
1165 | automatically restart it if need be. |
|
|
1166 | .Sp |
|
|
1167 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
|
|
1168 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
|
|
1169 | .Sp |
|
|
1170 | .Vb 8 |
|
|
1171 | \& ev_timer_init (timer, callback, 0., 5.); |
|
|
1172 | \& ev_timer_again (loop, timer); |
|
|
1173 | \& ... |
|
|
1174 | \& timer->again = 17.; |
|
|
1175 | \& ev_timer_again (loop, timer); |
|
|
1176 | \& ... |
|
|
1177 | \& timer->again = 10.; |
|
|
1178 | \& ev_timer_again (loop, timer); |
|
|
1179 | .Ve |
|
|
1180 | .Sp |
|
|
1181 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1182 | you want to modify its timeout value. |
|
|
1183 | .IP "ev_tstamp repeat [read\-write]" 4 |
|
|
1184 | .IX Item "ev_tstamp repeat [read-write]" |
|
|
1185 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
|
|
1186 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
|
|
1187 | which is also when any modifications are taken into account. |
|
|
1188 | .PP |
|
|
1189 | Example: Create a timer that fires after 60 seconds. |
|
|
1190 | .PP |
|
|
1191 | .Vb 5 |
|
|
1192 | \& static void |
|
|
1193 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1194 | \& { |
|
|
1195 | \& .. one minute over, w is actually stopped right here |
|
|
1196 | \& } |
|
|
1197 | .Ve |
|
|
1198 | .PP |
|
|
1199 | .Vb 3 |
|
|
1200 | \& struct ev_timer mytimer; |
|
|
1201 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
1202 | \& ev_timer_start (loop, &mytimer); |
|
|
1203 | .Ve |
|
|
1204 | .PP |
|
|
1205 | Example: Create a timeout timer that times out after 10 seconds of |
|
|
1206 | inactivity. |
|
|
1207 | .PP |
|
|
1208 | .Vb 5 |
|
|
1209 | \& static void |
|
|
1210 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1211 | \& { |
|
|
1212 | \& .. ten seconds without any activity |
|
|
1213 | \& } |
|
|
1214 | .Ve |
|
|
1215 | .PP |
|
|
1216 | .Vb 4 |
|
|
1217 | \& struct ev_timer mytimer; |
|
|
1218 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
1219 | \& ev_timer_again (&mytimer); /* start timer */ |
|
|
1220 | \& ev_loop (loop, 0); |
|
|
1221 | .Ve |
|
|
1222 | .PP |
|
|
1223 | .Vb 3 |
|
|
1224 | \& // and in some piece of code that gets executed on any "activity": |
|
|
1225 | \& // reset the timeout to start ticking again at 10 seconds |
|
|
1226 | \& ev_timer_again (&mytimer); |
|
|
1227 | .Ve |
648 | .ie n .Sh """ev_periodic"" \- to cron or not to cron" |
1228 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
649 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron" |
1229 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
650 | .IX Subsection "ev_periodic - to cron or not to cron" |
1230 | .IX Subsection "ev_periodic - to cron or not to cron?" |
651 | Periodic watchers are also timers of a kind, but they are very versatile |
1231 | Periodic watchers are also timers of a kind, but they are very versatile |
652 | (and unfortunately a bit complex). |
1232 | (and unfortunately a bit complex). |
653 | .PP |
1233 | .PP |
654 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1234 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
655 | but on wallclock time (absolute time). You can tell a periodic watcher |
1235 | but on wallclock time (absolute time). You can tell a periodic watcher |
656 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1236 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
657 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1237 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
658 | + 10.>) and then reset your system clock to the last year, then it will |
1238 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
659 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1239 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
660 | roughly 10 seconds later and of course not if you reset your system time |
1240 | roughly 10 seconds later). |
661 | again). |
|
|
662 | .PP |
1241 | .PP |
663 | They can also be used to implement vastly more complex timers, such as |
1242 | They can also be used to implement vastly more complex timers, such as |
664 | triggering an event on eahc midnight, local time. |
1243 | triggering an event on each midnight, local time or other, complicated, |
|
|
1244 | rules. |
665 | .PP |
1245 | .PP |
666 | As with timers, the callback is guarenteed to be invoked only when the |
1246 | As with timers, the callback is guarenteed to be invoked only when the |
667 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1247 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
668 | during the same loop iteration then order of execution is undefined. |
1248 | during the same loop iteration then order of execution is undefined. |
669 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1249 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
… | |
… | |
673 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1253 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
674 | .PD |
1254 | .PD |
675 | Lots of arguments, lets sort it out... There are basically three modes of |
1255 | Lots of arguments, lets sort it out... There are basically three modes of |
676 | operation, and we will explain them from simplest to complex: |
1256 | operation, and we will explain them from simplest to complex: |
677 | .RS 4 |
1257 | .RS 4 |
678 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1258 | .IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4 |
679 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1259 | .IX Item "absolute timer (at = time, interval = reschedule_cb = 0)" |
680 | In this configuration the watcher triggers an event at the wallclock time |
1260 | In this configuration the watcher triggers an event at the wallclock time |
681 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1261 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
682 | that is, if it is to be run at January 1st 2011 then it will run when the |
1262 | that is, if it is to be run at January 1st 2011 then it will run when the |
683 | system time reaches or surpasses this time. |
1263 | system time reaches or surpasses this time. |
684 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1264 | .IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4 |
685 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1265 | .IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" |
686 | In this mode the watcher will always be scheduled to time out at the next |
1266 | In this mode the watcher will always be scheduled to time out at the next |
687 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1267 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
688 | of any time jumps. |
1268 | and then repeat, regardless of any time jumps. |
689 | .Sp |
1269 | .Sp |
690 | This can be used to create timers that do not drift with respect to system |
1270 | This can be used to create timers that do not drift with respect to system |
691 | time: |
1271 | time: |
692 | .Sp |
1272 | .Sp |
693 | .Vb 1 |
1273 | .Vb 1 |
… | |
… | |
700 | by 3600. |
1280 | by 3600. |
701 | .Sp |
1281 | .Sp |
702 | Another way to think about it (for the mathematically inclined) is that |
1282 | Another way to think about it (for the mathematically inclined) is that |
703 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1283 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
704 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1284 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
|
|
1285 | .Sp |
|
|
1286 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1287 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1288 | this value. |
705 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1289 | .IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4 |
706 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1290 | .IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)" |
707 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1291 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
708 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1292 | ignored. Instead, each time the periodic watcher gets scheduled, the |
709 | reschedule callback will be called with the watcher as first, and the |
1293 | reschedule callback will be called with the watcher as first, and the |
710 | current time as second argument. |
1294 | current time as second argument. |
711 | .Sp |
1295 | .Sp |
712 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1296 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
713 | ever, or make any event loop modifications\fR. If you need to stop it, |
1297 | ever, or make any event loop modifications\fR. If you need to stop it, |
714 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1298 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
715 | starting a prepare watcher). |
1299 | starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). |
716 | .Sp |
1300 | .Sp |
717 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1301 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
718 | ev_tstamp now)\*(C'\fR, e.g.: |
1302 | ev_tstamp now)\*(C'\fR, e.g.: |
719 | .Sp |
1303 | .Sp |
720 | .Vb 4 |
1304 | .Vb 4 |
… | |
… | |
744 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1328 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
745 | Simply stops and restarts the periodic watcher again. This is only useful |
1329 | Simply stops and restarts the periodic watcher again. This is only useful |
746 | when you changed some parameters or the reschedule callback would return |
1330 | when you changed some parameters or the reschedule callback would return |
747 | a different time than the last time it was called (e.g. in a crond like |
1331 | a different time than the last time it was called (e.g. in a crond like |
748 | program when the crontabs have changed). |
1332 | program when the crontabs have changed). |
|
|
1333 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1334 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1335 | When repeating, this contains the offset value, otherwise this is the |
|
|
1336 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1337 | .Sp |
|
|
1338 | Can be modified any time, but changes only take effect when the periodic |
|
|
1339 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1340 | .IP "ev_tstamp interval [read\-write]" 4 |
|
|
1341 | .IX Item "ev_tstamp interval [read-write]" |
|
|
1342 | The current interval value. Can be modified any time, but changes only |
|
|
1343 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
|
|
1344 | called. |
|
|
1345 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
|
|
1346 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
|
|
1347 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
|
|
1348 | switched off. Can be changed any time, but changes only take effect when |
|
|
1349 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1350 | .PP |
|
|
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1352 | system clock is divisible by 3600. The callback invocation times have |
|
|
1353 | potentially a lot of jittering, but good long-term stability. |
|
|
1354 | .PP |
|
|
1355 | .Vb 5 |
|
|
1356 | \& static void |
|
|
1357 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1358 | \& { |
|
|
1359 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1360 | \& } |
|
|
1361 | .Ve |
|
|
1362 | .PP |
|
|
1363 | .Vb 3 |
|
|
1364 | \& struct ev_periodic hourly_tick; |
|
|
1365 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1366 | \& ev_periodic_start (loop, &hourly_tick); |
|
|
1367 | .Ve |
|
|
1368 | .PP |
|
|
1369 | Example: The same as above, but use a reschedule callback to do it: |
|
|
1370 | .PP |
|
|
1371 | .Vb 1 |
|
|
1372 | \& #include <math.h> |
|
|
1373 | .Ve |
|
|
1374 | .PP |
|
|
1375 | .Vb 5 |
|
|
1376 | \& static ev_tstamp |
|
|
1377 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1378 | \& { |
|
|
1379 | \& return fmod (now, 3600.) + 3600.; |
|
|
1380 | \& } |
|
|
1381 | .Ve |
|
|
1382 | .PP |
|
|
1383 | .Vb 1 |
|
|
1384 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1385 | .Ve |
|
|
1386 | .PP |
|
|
1387 | Example: Call a callback every hour, starting now: |
|
|
1388 | .PP |
|
|
1389 | .Vb 4 |
|
|
1390 | \& struct ev_periodic hourly_tick; |
|
|
1391 | \& ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1392 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1393 | \& ev_periodic_start (loop, &hourly_tick); |
|
|
1394 | .Ve |
749 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled" |
1395 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
750 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled" |
1396 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
751 | .IX Subsection "ev_signal - signal me when a signal gets signalled" |
1397 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
752 | Signal watchers will trigger an event when the process receives a specific |
1398 | Signal watchers will trigger an event when the process receives a specific |
753 | signal one or more times. Even though signals are very asynchronous, libev |
1399 | signal one or more times. Even though signals are very asynchronous, libev |
754 | will try it's best to deliver signals synchronously, i.e. as part of the |
1400 | will try it's best to deliver signals synchronously, i.e. as part of the |
755 | normal event processing, like any other event. |
1401 | normal event processing, like any other event. |
756 | .PP |
1402 | .PP |
… | |
… | |
766 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1412 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
767 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1413 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
768 | .PD |
1414 | .PD |
769 | Configures the watcher to trigger on the given signal number (usually one |
1415 | Configures the watcher to trigger on the given signal number (usually one |
770 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1416 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
|
|
1417 | .IP "int signum [read\-only]" 4 |
|
|
1418 | .IX Item "int signum [read-only]" |
|
|
1419 | The signal the watcher watches out for. |
771 | .ie n .Sh """ev_child"" \- wait for pid status changes" |
1420 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
772 | .el .Sh "\f(CWev_child\fP \- wait for pid status changes" |
1421 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
773 | .IX Subsection "ev_child - wait for pid status changes" |
1422 | .IX Subsection "ev_child - watch out for process status changes" |
774 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1423 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
775 | some child status changes (most typically when a child of yours dies). |
1424 | some child status changes (most typically when a child of yours dies). |
776 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1425 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
777 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1426 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
778 | .PD 0 |
1427 | .PD 0 |
… | |
… | |
783 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1432 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
784 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1433 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
785 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1434 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
786 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1435 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
787 | process causing the status change. |
1436 | process causing the status change. |
|
|
1437 | .IP "int pid [read\-only]" 4 |
|
|
1438 | .IX Item "int pid [read-only]" |
|
|
1439 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
|
|
1440 | .IP "int rpid [read\-write]" 4 |
|
|
1441 | .IX Item "int rpid [read-write]" |
|
|
1442 | The process id that detected a status change. |
|
|
1443 | .IP "int rstatus [read\-write]" 4 |
|
|
1444 | .IX Item "int rstatus [read-write]" |
|
|
1445 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
|
|
1446 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
|
|
1447 | .PP |
|
|
1448 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1449 | .PP |
|
|
1450 | .Vb 5 |
|
|
1451 | \& static void |
|
|
1452 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1453 | \& { |
|
|
1454 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1455 | \& } |
|
|
1456 | .Ve |
|
|
1457 | .PP |
|
|
1458 | .Vb 3 |
|
|
1459 | \& struct ev_signal signal_watcher; |
|
|
1460 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1461 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1462 | .Ve |
|
|
1463 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
|
|
1464 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
|
|
1465 | .IX Subsection "ev_stat - did the file attributes just change?" |
|
|
1466 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1467 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
|
|
1468 | compared to the last time, invoking the callback if it did. |
|
|
1469 | .PP |
|
|
1470 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
|
|
1471 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
|
|
1472 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
|
|
1473 | otherwise always forced to be at least one) and all the other fields of |
|
|
1474 | the stat buffer having unspecified contents. |
|
|
1475 | .PP |
|
|
1476 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
|
|
1477 | relative and your working directory changes, the behaviour is undefined. |
|
|
1478 | .PP |
|
|
1479 | Since there is no standard to do this, the portable implementation simply |
|
|
1480 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
|
|
1481 | can specify a recommended polling interval for this case. If you specify |
|
|
1482 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
|
|
1483 | unspecified default\fR value will be used (which you can expect to be around |
|
|
1484 | five seconds, although this might change dynamically). Libev will also |
|
|
1485 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
|
|
1486 | usually overkill. |
|
|
1487 | .PP |
|
|
1488 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1489 | as even with OS-supported change notifications, this can be |
|
|
1490 | resource\-intensive. |
|
|
1491 | .PP |
|
|
1492 | At the time of this writing, only the Linux inotify interface is |
|
|
1493 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1494 | reader). Inotify will be used to give hints only and should not change the |
|
|
1495 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
|
|
1496 | to fall back to regular polling again even with inotify, but changes are |
|
|
1497 | usually detected immediately, and if the file exists there will be no |
|
|
1498 | polling. |
|
|
1499 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
|
|
1500 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
|
|
1501 | .PD 0 |
|
|
1502 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
|
|
1503 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
|
|
1504 | .PD |
|
|
1505 | Configures the watcher to wait for status changes of the given |
|
|
1506 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
|
|
1507 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
|
|
1508 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
|
|
1509 | path for as long as the watcher is active. |
|
|
1510 | .Sp |
|
|
1511 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
|
|
1512 | relative to the attributes at the time the watcher was started (or the |
|
|
1513 | last change was detected). |
|
|
1514 | .IP "ev_stat_stat (ev_stat *)" 4 |
|
|
1515 | .IX Item "ev_stat_stat (ev_stat *)" |
|
|
1516 | Updates the stat buffer immediately with new values. If you change the |
|
|
1517 | watched path in your callback, you could call this fucntion to avoid |
|
|
1518 | detecting this change (while introducing a race condition). Can also be |
|
|
1519 | useful simply to find out the new values. |
|
|
1520 | .IP "ev_statdata attr [read\-only]" 4 |
|
|
1521 | .IX Item "ev_statdata attr [read-only]" |
|
|
1522 | The most-recently detected attributes of the file. Although the type is of |
|
|
1523 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
1524 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
|
|
1525 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
|
|
1526 | .IP "ev_statdata prev [read\-only]" 4 |
|
|
1527 | .IX Item "ev_statdata prev [read-only]" |
|
|
1528 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1529 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
|
|
1530 | .IP "ev_tstamp interval [read\-only]" 4 |
|
|
1531 | .IX Item "ev_tstamp interval [read-only]" |
|
|
1532 | The specified interval. |
|
|
1533 | .IP "const char *path [read\-only]" 4 |
|
|
1534 | .IX Item "const char *path [read-only]" |
|
|
1535 | The filesystem path that is being watched. |
|
|
1536 | .PP |
|
|
1537 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
|
|
1538 | .PP |
|
|
1539 | .Vb 15 |
|
|
1540 | \& static void |
|
|
1541 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1542 | \& { |
|
|
1543 | \& /* /etc/passwd changed in some way */ |
|
|
1544 | \& if (w->attr.st_nlink) |
|
|
1545 | \& { |
|
|
1546 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
|
|
1547 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
|
|
1548 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
|
|
1549 | \& } |
|
|
1550 | \& else |
|
|
1551 | \& /* you shalt not abuse printf for puts */ |
|
|
1552 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1553 | \& "if this is windows, they already arrived\en"); |
|
|
1554 | \& } |
|
|
1555 | .Ve |
|
|
1556 | .PP |
|
|
1557 | .Vb 2 |
|
|
1558 | \& ... |
|
|
1559 | \& ev_stat passwd; |
|
|
1560 | .Ve |
|
|
1561 | .PP |
|
|
1562 | .Vb 2 |
|
|
1563 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1564 | \& ev_stat_start (loop, &passwd); |
|
|
1565 | .Ve |
788 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do" |
1566 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
789 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do" |
1567 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
790 | .IX Subsection "ev_idle - when you've got nothing better to do" |
1568 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
791 | Idle watchers trigger events when there are no other events are pending |
1569 | Idle watchers trigger events when no other events of the same or higher |
792 | (prepare, check and other idle watchers do not count). That is, as long |
1570 | priority are pending (prepare, check and other idle watchers do not |
793 | as your process is busy handling sockets or timeouts (or even signals, |
1571 | count). |
794 | imagine) it will not be triggered. But when your process is idle all idle |
1572 | .PP |
795 | watchers are being called again and again, once per event loop iteration \- |
1573 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1574 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1575 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1576 | are pending), the idle watchers are being called once per event loop |
796 | until stopped, that is, or your process receives more events and becomes |
1577 | iteration \- until stopped, that is, or your process receives more events |
797 | busy. |
1578 | and becomes busy again with higher priority stuff. |
798 | .PP |
1579 | .PP |
799 | The most noteworthy effect is that as long as any idle watchers are |
1580 | The most noteworthy effect is that as long as any idle watchers are |
800 | active, the process will not block when waiting for new events. |
1581 | active, the process will not block when waiting for new events. |
801 | .PP |
1582 | .PP |
802 | Apart from keeping your process non-blocking (which is a useful |
1583 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
806 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1587 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
807 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1588 | .IX Item "ev_idle_init (ev_signal *, callback)" |
808 | Initialises and configures the idle watcher \- it has no parameters of any |
1589 | Initialises and configures the idle watcher \- it has no parameters of any |
809 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1590 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
810 | believe me. |
1591 | believe me. |
|
|
1592 | .PP |
|
|
1593 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
|
|
1594 | callback, free it. Also, use no error checking, as usual. |
|
|
1595 | .PP |
|
|
1596 | .Vb 7 |
|
|
1597 | \& static void |
|
|
1598 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1599 | \& { |
|
|
1600 | \& free (w); |
|
|
1601 | \& // now do something you wanted to do when the program has |
|
|
1602 | \& // no longer asnything immediate to do. |
|
|
1603 | \& } |
|
|
1604 | .Ve |
|
|
1605 | .PP |
|
|
1606 | .Vb 3 |
|
|
1607 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1608 | \& ev_idle_init (idle_watcher, idle_cb); |
|
|
1609 | \& ev_idle_start (loop, idle_cb); |
|
|
1610 | .Ve |
811 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop" |
1611 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
812 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop" |
1612 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
813 | .IX Subsection "ev_prepare and ev_check - customise your event loop" |
1613 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
814 | Prepare and check watchers are usually (but not always) used in tandem: |
1614 | Prepare and check watchers are usually (but not always) used in tandem: |
815 | prepare watchers get invoked before the process blocks and check watchers |
1615 | prepare watchers get invoked before the process blocks and check watchers |
816 | afterwards. |
1616 | afterwards. |
817 | .PP |
1617 | .PP |
|
|
1618 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
|
|
1619 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
|
|
1620 | watchers. Other loops than the current one are fine, however. The |
|
|
1621 | rationale behind this is that you do not need to check for recursion in |
|
|
1622 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
|
|
1623 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
|
|
1624 | called in pairs bracketing the blocking call. |
|
|
1625 | .PP |
818 | Their main purpose is to integrate other event mechanisms into libev. This |
1626 | Their main purpose is to integrate other event mechanisms into libev and |
819 | could be used, for example, to track variable changes, implement your own |
1627 | their use is somewhat advanced. This could be used, for example, to track |
820 | watchers, integrate net-snmp or a coroutine library and lots more. |
1628 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1629 | coroutine library and lots more. They are also occasionally useful if |
|
|
1630 | you cache some data and want to flush it before blocking (for example, |
|
|
1631 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
1632 | watcher). |
821 | .PP |
1633 | .PP |
822 | This is done by examining in each prepare call which file descriptors need |
1634 | This is done by examining in each prepare call which file descriptors need |
823 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
1635 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
824 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
1636 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
825 | provide just this functionality). Then, in the check watcher you check for |
1637 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
834 | are ready to run (it's actually more complicated: it only runs coroutines |
1646 | are ready to run (it's actually more complicated: it only runs coroutines |
835 | with priority higher than or equal to the event loop and one coroutine |
1647 | with priority higher than or equal to the event loop and one coroutine |
836 | of lower priority, but only once, using idle watchers to keep the event |
1648 | of lower priority, but only once, using idle watchers to keep the event |
837 | loop from blocking if lower-priority coroutines are active, thus mapping |
1649 | loop from blocking if lower-priority coroutines are active, thus mapping |
838 | low-priority coroutines to idle/background tasks). |
1650 | low-priority coroutines to idle/background tasks). |
|
|
1651 | .PP |
|
|
1652 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
1653 | priority, to ensure that they are being run before any other watchers |
|
|
1654 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
|
|
1655 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
|
|
1656 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did |
|
|
1657 | their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event |
|
|
1658 | loops those other event loops might be in an unusable state until their |
|
|
1659 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
|
|
1660 | others). |
839 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1661 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
840 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1662 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
841 | .PD 0 |
1663 | .PD 0 |
842 | .IP "ev_check_init (ev_check *, callback)" 4 |
1664 | .IP "ev_check_init (ev_check *, callback)" 4 |
843 | .IX Item "ev_check_init (ev_check *, callback)" |
1665 | .IX Item "ev_check_init (ev_check *, callback)" |
844 | .PD |
1666 | .PD |
845 | Initialises and configures the prepare or check watcher \- they have no |
1667 | Initialises and configures the prepare or check watcher \- they have no |
846 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1668 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
847 | macros, but using them is utterly, utterly and completely pointless. |
1669 | macros, but using them is utterly, utterly and completely pointless. |
|
|
1670 | .PP |
|
|
1671 | There are a number of principal ways to embed other event loops or modules |
|
|
1672 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1673 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
1674 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
|
|
1675 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
|
|
1676 | into the Glib event loop). |
|
|
1677 | .PP |
|
|
1678 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
|
|
1679 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1680 | is pseudo-code only of course. This requires you to either use a low |
|
|
1681 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
1682 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
1683 | .PP |
|
|
1684 | .Vb 2 |
|
|
1685 | \& static ev_io iow [nfd]; |
|
|
1686 | \& static ev_timer tw; |
|
|
1687 | .Ve |
|
|
1688 | .PP |
|
|
1689 | .Vb 4 |
|
|
1690 | \& static void |
|
|
1691 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1692 | \& { |
|
|
1693 | \& } |
|
|
1694 | .Ve |
|
|
1695 | .PP |
|
|
1696 | .Vb 8 |
|
|
1697 | \& // create io watchers for each fd and a timer before blocking |
|
|
1698 | \& static void |
|
|
1699 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1700 | \& { |
|
|
1701 | \& int timeout = 3600000; |
|
|
1702 | \& struct pollfd fds [nfd]; |
|
|
1703 | \& // actual code will need to loop here and realloc etc. |
|
|
1704 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1705 | .Ve |
|
|
1706 | .PP |
|
|
1707 | .Vb 3 |
|
|
1708 | \& /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1709 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1710 | \& ev_timer_start (loop, &tw); |
|
|
1711 | .Ve |
|
|
1712 | .PP |
|
|
1713 | .Vb 6 |
|
|
1714 | \& // create one ev_io per pollfd |
|
|
1715 | \& for (int i = 0; i < nfd; ++i) |
|
|
1716 | \& { |
|
|
1717 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1718 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1719 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1720 | .Ve |
|
|
1721 | .PP |
|
|
1722 | .Vb 4 |
|
|
1723 | \& fds [i].revents = 0; |
|
|
1724 | \& ev_io_start (loop, iow + i); |
|
|
1725 | \& } |
|
|
1726 | \& } |
|
|
1727 | .Ve |
|
|
1728 | .PP |
|
|
1729 | .Vb 5 |
|
|
1730 | \& // stop all watchers after blocking |
|
|
1731 | \& static void |
|
|
1732 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1733 | \& { |
|
|
1734 | \& ev_timer_stop (loop, &tw); |
|
|
1735 | .Ve |
|
|
1736 | .PP |
|
|
1737 | .Vb 8 |
|
|
1738 | \& for (int i = 0; i < nfd; ++i) |
|
|
1739 | \& { |
|
|
1740 | \& // set the relevant poll flags |
|
|
1741 | \& // could also call adns_processreadable etc. here |
|
|
1742 | \& struct pollfd *fd = fds + i; |
|
|
1743 | \& int revents = ev_clear_pending (iow + i); |
|
|
1744 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1745 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1746 | .Ve |
|
|
1747 | .PP |
|
|
1748 | .Vb 3 |
|
|
1749 | \& // now stop the watcher |
|
|
1750 | \& ev_io_stop (loop, iow + i); |
|
|
1751 | \& } |
|
|
1752 | .Ve |
|
|
1753 | .PP |
|
|
1754 | .Vb 2 |
|
|
1755 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1756 | \& } |
|
|
1757 | .Ve |
|
|
1758 | .PP |
|
|
1759 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
1760 | in the prepare watcher and would dispose of the check watcher. |
|
|
1761 | .PP |
|
|
1762 | Method 3: If the module to be embedded supports explicit event |
|
|
1763 | notification (adns does), you can also make use of the actual watcher |
|
|
1764 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1765 | .PP |
|
|
1766 | .Vb 5 |
|
|
1767 | \& static void |
|
|
1768 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1769 | \& { |
|
|
1770 | \& adns_state ads = (adns_state)w->data; |
|
|
1771 | \& update_now (EV_A); |
|
|
1772 | .Ve |
|
|
1773 | .PP |
|
|
1774 | .Vb 2 |
|
|
1775 | \& adns_processtimeouts (ads, &tv_now); |
|
|
1776 | \& } |
|
|
1777 | .Ve |
|
|
1778 | .PP |
|
|
1779 | .Vb 5 |
|
|
1780 | \& static void |
|
|
1781 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1782 | \& { |
|
|
1783 | \& adns_state ads = (adns_state)w->data; |
|
|
1784 | \& update_now (EV_A); |
|
|
1785 | .Ve |
|
|
1786 | .PP |
|
|
1787 | .Vb 3 |
|
|
1788 | \& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1789 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1790 | \& } |
|
|
1791 | .Ve |
|
|
1792 | .PP |
|
|
1793 | .Vb 1 |
|
|
1794 | \& // do not ever call adns_afterpoll |
|
|
1795 | .Ve |
|
|
1796 | .PP |
|
|
1797 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1798 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1799 | their poll function. The drawback with this solution is that the main |
|
|
1800 | loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does |
|
|
1801 | this. |
|
|
1802 | .PP |
|
|
1803 | .Vb 4 |
|
|
1804 | \& static gint |
|
|
1805 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1806 | \& { |
|
|
1807 | \& int got_events = 0; |
|
|
1808 | .Ve |
|
|
1809 | .PP |
|
|
1810 | .Vb 2 |
|
|
1811 | \& for (n = 0; n < nfds; ++n) |
|
|
1812 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1813 | .Ve |
|
|
1814 | .PP |
|
|
1815 | .Vb 2 |
|
|
1816 | \& if (timeout >= 0) |
|
|
1817 | \& // create/start timer |
|
|
1818 | .Ve |
|
|
1819 | .PP |
|
|
1820 | .Vb 2 |
|
|
1821 | \& // poll |
|
|
1822 | \& ev_loop (EV_A_ 0); |
|
|
1823 | .Ve |
|
|
1824 | .PP |
|
|
1825 | .Vb 3 |
|
|
1826 | \& // stop timer again |
|
|
1827 | \& if (timeout >= 0) |
|
|
1828 | \& ev_timer_stop (EV_A_ &to); |
|
|
1829 | .Ve |
|
|
1830 | .PP |
|
|
1831 | .Vb 3 |
|
|
1832 | \& // stop io watchers again - their callbacks should have set |
|
|
1833 | \& for (n = 0; n < nfds; ++n) |
|
|
1834 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
1835 | .Ve |
|
|
1836 | .PP |
|
|
1837 | .Vb 2 |
|
|
1838 | \& return got_events; |
|
|
1839 | \& } |
|
|
1840 | .Ve |
|
|
1841 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
|
|
1842 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
|
|
1843 | .IX Subsection "ev_embed - when one backend isn't enough..." |
|
|
1844 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1845 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
|
|
1846 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1847 | fashion and must not be used). |
|
|
1848 | .PP |
|
|
1849 | There are primarily two reasons you would want that: work around bugs and |
|
|
1850 | prioritise I/O. |
|
|
1851 | .PP |
|
|
1852 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1853 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1854 | still want to make use of it because you have many sockets and it scales |
|
|
1855 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1856 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1857 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1858 | at least you can use both at what they are best. |
|
|
1859 | .PP |
|
|
1860 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1861 | to be watched and handled very quickly (with low latency), and even |
|
|
1862 | priorities and idle watchers might have too much overhead. In this case |
|
|
1863 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1864 | a second one, and embed the second one in the first. |
|
|
1865 | .PP |
|
|
1866 | As long as the watcher is active, the callback will be invoked every time |
|
|
1867 | there might be events pending in the embedded loop. The callback must then |
|
|
1868 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
|
|
1869 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1870 | loop strictly lower priority for example). You can also set the callback |
|
|
1871 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
|
|
1872 | embedded loop sweep. |
|
|
1873 | .PP |
|
|
1874 | As long as the watcher is started it will automatically handle events. The |
|
|
1875 | callback will be invoked whenever some events have been handled. You can |
|
|
1876 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
1877 | interested in that. |
|
|
1878 | .PP |
|
|
1879 | Also, there have not currently been made special provisions for forking: |
|
|
1880 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
|
|
1881 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
|
|
1882 | yourself. |
|
|
1883 | .PP |
|
|
1884 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1885 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
|
|
1886 | portable one. |
|
|
1887 | .PP |
|
|
1888 | So when you want to use this feature you will always have to be prepared |
|
|
1889 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1890 | this is to have a separate variables for your embeddable loop, try to |
|
|
1891 | create it, and if that fails, use the normal loop for everything: |
|
|
1892 | .PP |
|
|
1893 | .Vb 3 |
|
|
1894 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1895 | \& struct ev_loop *loop_lo = 0; |
|
|
1896 | \& struct ev_embed embed; |
|
|
1897 | .Ve |
|
|
1898 | .PP |
|
|
1899 | .Vb 5 |
|
|
1900 | \& // see if there is a chance of getting one that works |
|
|
1901 | \& // (remember that a flags value of 0 means autodetection) |
|
|
1902 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1903 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1904 | \& : 0; |
|
|
1905 | .Ve |
|
|
1906 | .PP |
|
|
1907 | .Vb 8 |
|
|
1908 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
1909 | \& if (loop_lo) |
|
|
1910 | \& { |
|
|
1911 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1912 | \& ev_embed_start (loop_hi, &embed); |
|
|
1913 | \& } |
|
|
1914 | \& else |
|
|
1915 | \& loop_lo = loop_hi; |
|
|
1916 | .Ve |
|
|
1917 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
|
|
1918 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
|
|
1919 | .PD 0 |
|
|
1920 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
|
|
1921 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
|
|
1922 | .PD |
|
|
1923 | Configures the watcher to embed the given loop, which must be |
|
|
1924 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
|
|
1925 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1926 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1927 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1928 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
|
|
1929 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
|
|
1930 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1931 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
|
|
1932 | apropriate way for embedded loops. |
|
|
1933 | .IP "struct ev_loop *loop [read\-only]" 4 |
|
|
1934 | .IX Item "struct ev_loop *loop [read-only]" |
|
|
1935 | The embedded event loop. |
|
|
1936 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
|
|
1937 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
|
|
1938 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
|
|
1939 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
|
|
1940 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1941 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
|
|
1942 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
|
|
1943 | and only in the child after the fork. If whoever good citizen calling |
|
|
1944 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
|
|
1945 | handlers will be invoked, too, of course. |
|
|
1946 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
|
|
1947 | .IX Item "ev_fork_init (ev_signal *, callback)" |
|
|
1948 | Initialises and configures the fork watcher \- it has no parameters of any |
|
|
1949 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
1950 | believe me. |
848 | .SH "OTHER FUNCTIONS" |
1951 | .SH "OTHER FUNCTIONS" |
849 | .IX Header "OTHER FUNCTIONS" |
1952 | .IX Header "OTHER FUNCTIONS" |
850 | There are some other functions of possible interest. Described. Here. Now. |
1953 | There are some other functions of possible interest. Described. Here. Now. |
851 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1954 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
852 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
1955 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
881 | .Ve |
1984 | .Ve |
882 | .Sp |
1985 | .Sp |
883 | .Vb 1 |
1986 | .Vb 1 |
884 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1987 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
885 | .Ve |
1988 | .Ve |
886 | .IP "ev_feed_event (loop, watcher, int events)" 4 |
1989 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
887 | .IX Item "ev_feed_event (loop, watcher, int events)" |
1990 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
888 | Feeds the given event set into the event loop, as if the specified event |
1991 | Feeds the given event set into the event loop, as if the specified event |
889 | had happened for the specified watcher (which must be a pointer to an |
1992 | had happened for the specified watcher (which must be a pointer to an |
890 | initialised but not necessarily started event watcher). |
1993 | initialised but not necessarily started event watcher). |
891 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
1994 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
892 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
1995 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
893 | Feed an event on the given fd, as if a file descriptor backend detected |
1996 | Feed an event on the given fd, as if a file descriptor backend detected |
894 | the given events it. |
1997 | the given events it. |
895 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
1998 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
896 | .IX Item "ev_feed_signal_event (loop, int signum)" |
1999 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
897 | Feed an event as if the given signal occured (loop must be the default loop!). |
2000 | Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default |
|
|
2001 | loop!). |
898 | .SH "LIBEVENT EMULATION" |
2002 | .SH "LIBEVENT EMULATION" |
899 | .IX Header "LIBEVENT EMULATION" |
2003 | .IX Header "LIBEVENT EMULATION" |
900 | Libev offers a compatibility emulation layer for libevent. It cannot |
2004 | Libev offers a compatibility emulation layer for libevent. It cannot |
901 | emulate the internals of libevent, so here are some usage hints: |
2005 | emulate the internals of libevent, so here are some usage hints: |
902 | .IP "* Use it by including <event.h>, as usual." 4 |
2006 | .IP "* Use it by including <event.h>, as usual." 4 |
… | |
… | |
913 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2017 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
914 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2018 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
915 | .PD |
2019 | .PD |
916 | .SH "\*(C+ SUPPORT" |
2020 | .SH "\*(C+ SUPPORT" |
917 | .IX Header " SUPPORT" |
2021 | .IX Header " SUPPORT" |
918 | \&\s-1TBD\s0. |
2022 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
|
|
2023 | you to use some convinience methods to start/stop watchers and also change |
|
|
2024 | the callback model to a model using method callbacks on objects. |
|
|
2025 | .PP |
|
|
2026 | To use it, |
|
|
2027 | .PP |
|
|
2028 | .Vb 1 |
|
|
2029 | \& #include <ev++.h> |
|
|
2030 | .Ve |
|
|
2031 | .PP |
|
|
2032 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
|
|
2033 | of them macros) into the global namespace. All \*(C+ specific things are |
|
|
2034 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2035 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
|
|
2036 | .PP |
|
|
2037 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
|
|
2038 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2039 | that the watcher is associated with (or no additional members at all if |
|
|
2040 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2041 | .PP |
|
|
2042 | Currently, functions, and static and non-static member functions can be |
|
|
2043 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2044 | need one additional pointer for context. If you need support for other |
|
|
2045 | types of functors please contact the author (preferably after implementing |
|
|
2046 | it). |
|
|
2047 | .PP |
|
|
2048 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
|
|
2049 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
|
|
2050 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
|
|
2051 | .IX Item "ev::READ, ev::WRITE etc." |
|
|
2052 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
|
|
2053 | macros from \fIev.h\fR. |
|
|
2054 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
|
|
2055 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
|
|
2056 | .IX Item "ev::tstamp, ev::now" |
|
|
2057 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
|
|
2058 | .ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 |
|
|
2059 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
|
|
2060 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
|
|
2061 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
|
|
2062 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
|
|
2063 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
|
|
2064 | defines by many implementations. |
|
|
2065 | .Sp |
|
|
2066 | All of those classes have these methods: |
|
|
2067 | .RS 4 |
|
|
2068 | .IP "ev::TYPE::TYPE ()" 4 |
|
|
2069 | .IX Item "ev::TYPE::TYPE ()" |
|
|
2070 | .PD 0 |
|
|
2071 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
|
|
2072 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
|
|
2073 | .IP "ev::TYPE::~TYPE" 4 |
|
|
2074 | .IX Item "ev::TYPE::~TYPE" |
|
|
2075 | .PD |
|
|
2076 | The constructor (optionally) takes an event loop to associate the watcher |
|
|
2077 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
|
|
2078 | .Sp |
|
|
2079 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
|
|
2080 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2081 | .Sp |
|
|
2082 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2083 | method to set a callback before you can start the watcher. |
|
|
2084 | .Sp |
|
|
2085 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2086 | not allow explicit template arguments for constructors). |
|
|
2087 | .Sp |
|
|
2088 | The destructor automatically stops the watcher if it is active. |
|
|
2089 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2090 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2091 | This method sets the callback method to call. The method has to have a |
|
|
2092 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2093 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2094 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2095 | .Sp |
|
|
2096 | This method synthesizes efficient thunking code to call your method from |
|
|
2097 | the C callback that libev requires. If your compiler can inline your |
|
|
2098 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2099 | your compiler is good :), then the method will be fully inlined into the |
|
|
2100 | thunking function, making it as fast as a direct C callback. |
|
|
2101 | .Sp |
|
|
2102 | Example: simple class declaration and watcher initialisation |
|
|
2103 | .Sp |
|
|
2104 | .Vb 4 |
|
|
2105 | \& struct myclass |
|
|
2106 | \& { |
|
|
2107 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2108 | \& } |
|
|
2109 | .Ve |
|
|
2110 | .Sp |
|
|
2111 | .Vb 3 |
|
|
2112 | \& myclass obj; |
|
|
2113 | \& ev::io iow; |
|
|
2114 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2115 | .Ve |
|
|
2116 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2117 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2118 | Also sets a callback, but uses a static method or plain function as |
|
|
2119 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2120 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2121 | .Sp |
|
|
2122 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
2123 | .Sp |
|
|
2124 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
2125 | .Sp |
|
|
2126 | Example: |
|
|
2127 | .Sp |
|
|
2128 | .Vb 2 |
|
|
2129 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
2130 | \& iow.set <io_cb> (); |
|
|
2131 | .Ve |
|
|
2132 | .IP "w\->set (struct ev_loop *)" 4 |
|
|
2133 | .IX Item "w->set (struct ev_loop *)" |
|
|
2134 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
|
|
2135 | do this when the watcher is inactive (and not pending either). |
|
|
2136 | .IP "w\->set ([args])" 4 |
|
|
2137 | .IX Item "w->set ([args])" |
|
|
2138 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
|
|
2139 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
2140 | automatically stopped and restarted when reconfiguring it with this |
|
|
2141 | method. |
|
|
2142 | .IP "w\->start ()" 4 |
|
|
2143 | .IX Item "w->start ()" |
|
|
2144 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
|
|
2145 | constructor already stores the event loop. |
|
|
2146 | .IP "w\->stop ()" 4 |
|
|
2147 | .IX Item "w->stop ()" |
|
|
2148 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
|
|
2149 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
|
|
2150 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
|
|
2151 | .IX Item "w->again () ev::timer, ev::periodic only" |
|
|
2152 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
|
|
2153 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
|
|
2154 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
|
|
2155 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
|
|
2156 | .IX Item "w->sweep () ev::embed only" |
|
|
2157 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
|
|
2158 | .ie n .IP "w\->update () ""ev::stat"" only" 4 |
|
|
2159 | .el .IP "w\->update () \f(CWev::stat\fR only" 4 |
|
|
2160 | .IX Item "w->update () ev::stat only" |
|
|
2161 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
|
|
2162 | .RE |
|
|
2163 | .RS 4 |
|
|
2164 | .RE |
|
|
2165 | .PP |
|
|
2166 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
|
|
2167 | the constructor. |
|
|
2168 | .PP |
|
|
2169 | .Vb 4 |
|
|
2170 | \& class myclass |
|
|
2171 | \& { |
|
|
2172 | \& ev_io io; void io_cb (ev::io &w, int revents); |
|
|
2173 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2174 | .Ve |
|
|
2175 | .PP |
|
|
2176 | .Vb 2 |
|
|
2177 | \& myclass (); |
|
|
2178 | \& } |
|
|
2179 | .Ve |
|
|
2180 | .PP |
|
|
2181 | .Vb 4 |
|
|
2182 | \& myclass::myclass (int fd) |
|
|
2183 | \& { |
|
|
2184 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
2185 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2186 | .Ve |
|
|
2187 | .PP |
|
|
2188 | .Vb 2 |
|
|
2189 | \& io.start (fd, ev::READ); |
|
|
2190 | \& } |
|
|
2191 | .Ve |
|
|
2192 | .SH "MACRO MAGIC" |
|
|
2193 | .IX Header "MACRO MAGIC" |
|
|
2194 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
2195 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and |
|
|
2196 | callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
|
|
2197 | .PP |
|
|
2198 | To make it easier to write programs that cope with either variant, the |
|
|
2199 | following macros are defined: |
|
|
2200 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
|
|
2201 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
|
|
2202 | .IX Item "EV_A, EV_A_" |
|
|
2203 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
|
|
2204 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
|
|
2205 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
|
|
2206 | .Sp |
|
|
2207 | .Vb 3 |
|
|
2208 | \& ev_unref (EV_A); |
|
|
2209 | \& ev_timer_add (EV_A_ watcher); |
|
|
2210 | \& ev_loop (EV_A_ 0); |
|
|
2211 | .Ve |
|
|
2212 | .Sp |
|
|
2213 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
|
|
2214 | which is often provided by the following macro. |
|
|
2215 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
|
|
2216 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
|
|
2217 | .IX Item "EV_P, EV_P_" |
|
|
2218 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
|
|
2219 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
|
|
2220 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
|
|
2221 | .Sp |
|
|
2222 | .Vb 2 |
|
|
2223 | \& // this is how ev_unref is being declared |
|
|
2224 | \& static void ev_unref (EV_P); |
|
|
2225 | .Ve |
|
|
2226 | .Sp |
|
|
2227 | .Vb 2 |
|
|
2228 | \& // this is how you can declare your typical callback |
|
|
2229 | \& static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2230 | .Ve |
|
|
2231 | .Sp |
|
|
2232 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
|
|
2233 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
|
|
2234 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
|
|
2235 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
|
|
2236 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
|
|
2237 | Similar to the other two macros, this gives you the value of the default |
|
|
2238 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2239 | .PP |
|
|
2240 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2241 | macros so it will work regardless of whether multiple loops are supported |
|
|
2242 | or not. |
|
|
2243 | .PP |
|
|
2244 | .Vb 5 |
|
|
2245 | \& static void |
|
|
2246 | \& check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2247 | \& { |
|
|
2248 | \& ev_check_stop (EV_A_ w); |
|
|
2249 | \& } |
|
|
2250 | .Ve |
|
|
2251 | .PP |
|
|
2252 | .Vb 4 |
|
|
2253 | \& ev_check check; |
|
|
2254 | \& ev_check_init (&check, check_cb); |
|
|
2255 | \& ev_check_start (EV_DEFAULT_ &check); |
|
|
2256 | \& ev_loop (EV_DEFAULT_ 0); |
|
|
2257 | .Ve |
|
|
2258 | .SH "EMBEDDING" |
|
|
2259 | .IX Header "EMBEDDING" |
|
|
2260 | Libev can (and often is) directly embedded into host |
|
|
2261 | applications. Examples of applications that embed it include the Deliantra |
|
|
2262 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
|
|
2263 | and rxvt\-unicode. |
|
|
2264 | .PP |
|
|
2265 | The goal is to enable you to just copy the neecssary files into your |
|
|
2266 | source directory without having to change even a single line in them, so |
|
|
2267 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
2268 | libev somewhere in your source tree). |
|
|
2269 | .Sh "\s-1FILESETS\s0" |
|
|
2270 | .IX Subsection "FILESETS" |
|
|
2271 | Depending on what features you need you need to include one or more sets of files |
|
|
2272 | in your app. |
|
|
2273 | .PP |
|
|
2274 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
|
|
2275 | .IX Subsection "CORE EVENT LOOP" |
|
|
2276 | .PP |
|
|
2277 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
|
|
2278 | configuration (no autoconf): |
|
|
2279 | .PP |
|
|
2280 | .Vb 2 |
|
|
2281 | \& #define EV_STANDALONE 1 |
|
|
2282 | \& #include "ev.c" |
|
|
2283 | .Ve |
|
|
2284 | .PP |
|
|
2285 | This will automatically include \fIev.h\fR, too, and should be done in a |
|
|
2286 | single C source file only to provide the function implementations. To use |
|
|
2287 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
|
|
2288 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
|
|
2289 | where you can put other configuration options): |
|
|
2290 | .PP |
|
|
2291 | .Vb 2 |
|
|
2292 | \& #define EV_STANDALONE 1 |
|
|
2293 | \& #include "ev.h" |
|
|
2294 | .Ve |
|
|
2295 | .PP |
|
|
2296 | Both header files and implementation files can be compiled with a \*(C+ |
|
|
2297 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
2298 | as a bug). |
|
|
2299 | .PP |
|
|
2300 | You need the following files in your source tree, or in a directory |
|
|
2301 | in your include path (e.g. in libev/ when using \-Ilibev): |
|
|
2302 | .PP |
|
|
2303 | .Vb 4 |
|
|
2304 | \& ev.h |
|
|
2305 | \& ev.c |
|
|
2306 | \& ev_vars.h |
|
|
2307 | \& ev_wrap.h |
|
|
2308 | .Ve |
|
|
2309 | .PP |
|
|
2310 | .Vb 1 |
|
|
2311 | \& ev_win32.c required on win32 platforms only |
|
|
2312 | .Ve |
|
|
2313 | .PP |
|
|
2314 | .Vb 5 |
|
|
2315 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
2316 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
2317 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
2318 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
2319 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
2320 | .Ve |
|
|
2321 | .PP |
|
|
2322 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
|
|
2323 | to compile this single file. |
|
|
2324 | .PP |
|
|
2325 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
|
|
2326 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
|
|
2327 | .PP |
|
|
2328 | To include the libevent compatibility \s-1API\s0, also include: |
|
|
2329 | .PP |
|
|
2330 | .Vb 1 |
|
|
2331 | \& #include "event.c" |
|
|
2332 | .Ve |
|
|
2333 | .PP |
|
|
2334 | in the file including \fIev.c\fR, and: |
|
|
2335 | .PP |
|
|
2336 | .Vb 1 |
|
|
2337 | \& #include "event.h" |
|
|
2338 | .Ve |
|
|
2339 | .PP |
|
|
2340 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
|
|
2341 | .PP |
|
|
2342 | You need the following additional files for this: |
|
|
2343 | .PP |
|
|
2344 | .Vb 2 |
|
|
2345 | \& event.h |
|
|
2346 | \& event.c |
|
|
2347 | .Ve |
|
|
2348 | .PP |
|
|
2349 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
|
|
2350 | .IX Subsection "AUTOCONF SUPPORT" |
|
|
2351 | .PP |
|
|
2352 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
|
|
2353 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
|
|
2354 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
|
|
2355 | include \fIconfig.h\fR and configure itself accordingly. |
|
|
2356 | .PP |
|
|
2357 | For this of course you need the m4 file: |
|
|
2358 | .PP |
|
|
2359 | .Vb 1 |
|
|
2360 | \& libev.m4 |
|
|
2361 | .Ve |
|
|
2362 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
|
|
2363 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
|
|
2364 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
2365 | before including any of its files. The default is not to build for multiplicity |
|
|
2366 | and only include the select backend. |
|
|
2367 | .IP "\s-1EV_STANDALONE\s0" 4 |
|
|
2368 | .IX Item "EV_STANDALONE" |
|
|
2369 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
|
|
2370 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
|
|
2371 | implementations for some libevent functions (such as logging, which is not |
|
|
2372 | supported). It will also not define any of the structs usually found in |
|
|
2373 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
2374 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
|
|
2375 | .IX Item "EV_USE_MONOTONIC" |
|
|
2376 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
|
|
2377 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
2378 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
2379 | usually have to link against librt or something similar. Enabling it when |
|
|
2380 | the functionality isn't available is safe, though, althoguh you have |
|
|
2381 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
|
|
2382 | function is hiding in (often \fI\-lrt\fR). |
|
|
2383 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
|
|
2384 | .IX Item "EV_USE_REALTIME" |
|
|
2385 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
|
|
2386 | realtime clock option at compiletime (and assume its availability at |
|
|
2387 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
2388 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
|
|
2389 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
|
|
2390 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2391 | .IP "\s-1EV_USE_SELECT\s0" 4 |
|
|
2392 | .IX Item "EV_USE_SELECT" |
|
|
2393 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
|
|
2394 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
|
|
2395 | other method takes over, select will be it. Otherwise the select backend |
|
|
2396 | will not be compiled in. |
|
|
2397 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
|
|
2398 | .IX Item "EV_SELECT_USE_FD_SET" |
|
|
2399 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
|
|
2400 | structure. This is useful if libev doesn't compile due to a missing |
|
|
2401 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on |
|
|
2402 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2403 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2404 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
|
|
2405 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
|
|
2406 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
|
|
2407 | .IX Item "EV_SELECT_IS_WINSOCKET" |
|
|
2408 | When defined to \f(CW1\fR, the select backend will assume that |
|
|
2409 | select/socket/connect etc. don't understand file descriptors but |
|
|
2410 | wants osf handles on win32 (this is the case when the select to |
|
|
2411 | be used is the winsock select). This means that it will call |
|
|
2412 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
|
|
2413 | it is assumed that all these functions actually work on fds, even |
|
|
2414 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2415 | .IP "\s-1EV_USE_POLL\s0" 4 |
|
|
2416 | .IX Item "EV_USE_POLL" |
|
|
2417 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
|
|
2418 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
|
|
2419 | takes precedence over select. |
|
|
2420 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
|
|
2421 | .IX Item "EV_USE_EPOLL" |
|
|
2422 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
2423 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
|
|
2424 | otherwise another method will be used as fallback. This is the |
|
|
2425 | preferred backend for GNU/Linux systems. |
|
|
2426 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
|
|
2427 | .IX Item "EV_USE_KQUEUE" |
|
|
2428 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
|
|
2429 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
|
|
2430 | otherwise another method will be used as fallback. This is the preferred |
|
|
2431 | backend for \s-1BSD\s0 and BSD-like systems, although on most BSDs kqueue only |
|
|
2432 | supports some types of fds correctly (the only platform we found that |
|
|
2433 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2434 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2435 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2436 | kqueue loop. |
|
|
2437 | .IP "\s-1EV_USE_PORT\s0" 4 |
|
|
2438 | .IX Item "EV_USE_PORT" |
|
|
2439 | If defined to be \f(CW1\fR, libev will compile in support for the Solaris |
|
|
2440 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2441 | otherwise another method will be used as fallback. This is the preferred |
|
|
2442 | backend for Solaris 10 systems. |
|
|
2443 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
|
|
2444 | .IX Item "EV_USE_DEVPOLL" |
|
|
2445 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
2446 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
2447 | .IX Item "EV_USE_INOTIFY" |
|
|
2448 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
2449 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
2450 | be detected at runtime. |
|
|
2451 | .IP "\s-1EV_H\s0" 4 |
|
|
2452 | .IX Item "EV_H" |
|
|
2453 | The name of the \fIev.h\fR header file used to include it. The default if |
|
|
2454 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
|
|
2455 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
|
|
2456 | .IP "\s-1EV_CONFIG_H\s0" 4 |
|
|
2457 | .IX Item "EV_CONFIG_H" |
|
|
2458 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
|
|
2459 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
|
|
2460 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
|
|
2461 | .IP "\s-1EV_EVENT_H\s0" 4 |
|
|
2462 | .IX Item "EV_EVENT_H" |
|
|
2463 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
|
|
2464 | of how the \fIevent.h\fR header can be found. |
|
|
2465 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
|
|
2466 | .IX Item "EV_PROTOTYPES" |
|
|
2467 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
|
|
2468 | prototypes, but still define all the structs and other symbols. This is |
|
|
2469 | occasionally useful if you want to provide your own wrapper functions |
|
|
2470 | around libev functions. |
|
|
2471 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
|
|
2472 | .IX Item "EV_MULTIPLICITY" |
|
|
2473 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
|
|
2474 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
|
|
2475 | additional independent event loops. Otherwise there will be no support |
|
|
2476 | for multiple event loops and there is no first event loop pointer |
|
|
2477 | argument. Instead, all functions act on the single default loop. |
|
|
2478 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
2479 | .IX Item "EV_MINPRI" |
|
|
2480 | .PD 0 |
|
|
2481 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
2482 | .IX Item "EV_MAXPRI" |
|
|
2483 | .PD |
|
|
2484 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
2485 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
2486 | provide for more priorities by overriding those symbols (usually defined |
|
|
2487 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
2488 | .Sp |
|
|
2489 | When doing priority-based operations, libev usually has to linearly search |
|
|
2490 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2491 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
2492 | fine. |
|
|
2493 | .Sp |
|
|
2494 | If your embedding app does not need any priorities, defining these both to |
|
|
2495 | \&\f(CW0\fR will save some memory and cpu. |
|
|
2496 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
|
|
2497 | .IX Item "EV_PERIODIC_ENABLE" |
|
|
2498 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
|
|
2499 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
2500 | code. |
|
|
2501 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
2502 | .IX Item "EV_IDLE_ENABLE" |
|
|
2503 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
2504 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
2505 | code. |
|
|
2506 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
2507 | .IX Item "EV_EMBED_ENABLE" |
|
|
2508 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
2509 | defined to be \f(CW0\fR, then they are not. |
|
|
2510 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
|
|
2511 | .IX Item "EV_STAT_ENABLE" |
|
|
2512 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
2513 | defined to be \f(CW0\fR, then they are not. |
|
|
2514 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
2515 | .IX Item "EV_FORK_ENABLE" |
|
|
2516 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
2517 | defined to be \f(CW0\fR, then they are not. |
|
|
2518 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
2519 | .IX Item "EV_MINIMAL" |
|
|
2520 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2521 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
|
|
2522 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2523 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
|
|
2524 | .IX Item "EV_PID_HASHSIZE" |
|
|
2525 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
2526 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
|
|
2527 | than enough. If you need to manage thousands of children you might want to |
|
|
2528 | increase this value (\fImust\fR be a power of two). |
|
|
2529 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
2530 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
2531 | \&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
2532 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
2533 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
2534 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
2535 | two). |
|
|
2536 | .IP "\s-1EV_COMMON\s0" 4 |
|
|
2537 | .IX Item "EV_COMMON" |
|
|
2538 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
|
|
2539 | this macro to a something else you can include more and other types of |
|
|
2540 | members. You have to define it each time you include one of the files, |
|
|
2541 | though, and it must be identical each time. |
|
|
2542 | .Sp |
|
|
2543 | For example, the perl \s-1EV\s0 module uses something like this: |
|
|
2544 | .Sp |
|
|
2545 | .Vb 3 |
|
|
2546 | \& #define EV_COMMON \e |
|
|
2547 | \& SV *self; /* contains this struct */ \e |
|
|
2548 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2549 | .Ve |
|
|
2550 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
|
|
2551 | .IX Item "EV_CB_DECLARE (type)" |
|
|
2552 | .PD 0 |
|
|
2553 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
|
|
2554 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
|
|
2555 | .IP "ev_set_cb (ev, cb)" 4 |
|
|
2556 | .IX Item "ev_set_cb (ev, cb)" |
|
|
2557 | .PD |
|
|
2558 | Can be used to change the callback member declaration in each watcher, |
|
|
2559 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2560 | definition and a statement, respectively. See the \fIev.v\fR header file for |
|
|
2561 | their default definitions. One possible use for overriding these is to |
|
|
2562 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
|
|
2563 | method calls instead of plain function calls in \*(C+. |
|
|
2564 | .Sh "\s-1EXAMPLES\s0" |
|
|
2565 | .IX Subsection "EXAMPLES" |
|
|
2566 | For a real-world example of a program the includes libev |
|
|
2567 | verbatim, you can have a look at the \s-1EV\s0 perl module |
|
|
2568 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2569 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
|
|
2570 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
|
|
2571 | will be compiled. It is pretty complex because it provides its own header |
|
|
2572 | file. |
|
|
2573 | .Sp |
|
|
2574 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
|
|
2575 | that everybody includes and which overrides some configure choices: |
|
|
2576 | .Sp |
|
|
2577 | .Vb 9 |
|
|
2578 | \& #define EV_MINIMAL 1 |
|
|
2579 | \& #define EV_USE_POLL 0 |
|
|
2580 | \& #define EV_MULTIPLICITY 0 |
|
|
2581 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
2582 | \& #define EV_STAT_ENABLE 0 |
|
|
2583 | \& #define EV_FORK_ENABLE 0 |
|
|
2584 | \& #define EV_CONFIG_H <config.h> |
|
|
2585 | \& #define EV_MINPRI 0 |
|
|
2586 | \& #define EV_MAXPRI 0 |
|
|
2587 | .Ve |
|
|
2588 | .Sp |
|
|
2589 | .Vb 1 |
|
|
2590 | \& #include "ev++.h" |
|
|
2591 | .Ve |
|
|
2592 | .Sp |
|
|
2593 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
|
|
2594 | .Sp |
|
|
2595 | .Vb 2 |
|
|
2596 | \& #include "ev_cpp.h" |
|
|
2597 | \& #include "ev.c" |
|
|
2598 | .Ve |
|
|
2599 | .SH "COMPLEXITIES" |
|
|
2600 | .IX Header "COMPLEXITIES" |
|
|
2601 | In this section the complexities of (many of) the algorithms used inside |
|
|
2602 | libev will be explained. For complexity discussions about backends see the |
|
|
2603 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
|
|
2604 | .Sp |
|
|
2605 | All of the following are about amortised time: If an array needs to be |
|
|
2606 | extended, libev needs to realloc and move the whole array, but this |
|
|
2607 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2608 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2609 | it is much faster and asymptotically approaches constant time. |
|
|
2610 | .RS 4 |
|
|
2611 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
|
|
2612 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
2613 | This means that, when you have a watcher that triggers in one hour and |
|
|
2614 | there are 100 watchers that would trigger before that then inserting will |
|
|
2615 | have to skip those 100 watchers. |
|
|
2616 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2617 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
|
|
2618 | That means that for changing a timer costs less than removing/adding them |
|
|
2619 | as only the relative motion in the event queue has to be paid for. |
|
|
2620 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
|
|
2621 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
|
|
2622 | These just add the watcher into an array or at the head of a list. |
|
|
2623 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2624 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
|
|
2625 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
2626 | These watchers are stored in lists then need to be walked to find the |
|
|
2627 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2628 | have many watchers waiting for the same fd or signal). |
|
|
2629 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
|
|
2630 | .IX Item "Finding the next timer per loop iteration: O(1)" |
|
|
2631 | .PD 0 |
|
|
2632 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
|
|
2633 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
|
|
2634 | .PD |
|
|
2635 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2636 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2637 | .IP "Activating one watcher: O(1)" 4 |
|
|
2638 | .IX Item "Activating one watcher: O(1)" |
|
|
2639 | .PD 0 |
|
|
2640 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
2641 | .IX Item "Priority handling: O(number_of_priorities)" |
|
|
2642 | .PD |
|
|
2643 | Priorities are implemented by allocating some space for each |
|
|
2644 | priority. When doing priority-based operations, libev usually has to |
|
|
2645 | linearly search all the priorities. |
|
|
2646 | .RE |
|
|
2647 | .RS 4 |
919 | .SH "AUTHOR" |
2648 | .SH "AUTHOR" |
920 | .IX Header "AUTHOR" |
2649 | .IX Header "AUTHOR" |
921 | Marc Lehmann <libev@schmorp.de>. |
2650 | Marc Lehmann <libev@schmorp.de>. |