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129 | .\" ======================================================================== |
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131 | .IX Title ""<STANDARD INPUT>" 1" |
134 | .IX Title "EV 1" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH EV 1 "2008-04-11" "perl v5.10.0" "User Contributed Perl Documentation" |
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137 | .\" way too many mistakes in technical documents. |
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138 | .if n .ad l |
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139 | .nh |
133 | .SH "NAME" |
140 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
141 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
142 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
144 | .Vb 1 |
138 | \& #include <ev.h> |
145 | \& #include <ev.h> |
139 | .Ve |
146 | .Ve |
140 | .SH "EXAMPLE PROGRAM" |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
141 | .IX Header "EXAMPLE PROGRAM" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
142 | .Vb 1 |
149 | .Vb 2 |
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150 | \& // a single header file is required |
143 | \& #include <ev.h> |
151 | \& #include <ev.h> |
144 | .Ve |
152 | \& |
145 | .PP |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
146 | .Vb 2 |
154 | \& // with the name ev_<type> |
147 | \& ev_io stdin_watcher; |
155 | \& ev_io stdin_watcher; |
148 | \& ev_timer timeout_watcher; |
156 | \& ev_timer timeout_watcher; |
149 | .Ve |
157 | \& |
150 | .PP |
158 | \& // all watcher callbacks have a similar signature |
151 | .Vb 8 |
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152 | \& /* called when data readable on stdin */ |
159 | \& // this callback is called when data is readable on stdin |
153 | \& static void |
160 | \& static void |
154 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
155 | \& { |
162 | \& { |
156 | \& /* puts ("stdin ready"); */ |
163 | \& puts ("stdin ready"); |
157 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
164 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
165 | \& // with its corresponding stop function. |
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166 | \& ev_io_stop (EV_A_ w); |
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167 | \& |
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168 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
159 | \& } |
170 | \& } |
160 | .Ve |
171 | \& |
161 | .PP |
172 | \& // another callback, this time for a time\-out |
162 | .Vb 6 |
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163 | \& static void |
173 | \& static void |
164 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
165 | \& { |
175 | \& { |
166 | \& /* puts ("timeout"); */ |
176 | \& puts ("timeout"); |
167 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
177 | \& // this causes the innermost ev_loop to stop iterating |
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178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
168 | \& } |
179 | \& } |
169 | .Ve |
180 | \& |
170 | .PP |
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171 | .Vb 4 |
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172 | \& int |
181 | \& int |
173 | \& main (void) |
182 | \& main (void) |
174 | \& { |
183 | \& { |
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184 | \& // use the default event loop unless you have special needs |
175 | \& struct ev_loop *loop = ev_default_loop (0); |
185 | \& struct ev_loop *loop = ev_default_loop (0); |
176 | .Ve |
186 | \& |
177 | .PP |
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178 | .Vb 3 |
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179 | \& /* initialise an io watcher, then start it */ |
187 | \& // initialise an io watcher, then start it |
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188 | \& // this one will watch for stdin to become readable |
180 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
181 | \& ev_io_start (loop, &stdin_watcher); |
190 | \& ev_io_start (loop, &stdin_watcher); |
182 | .Ve |
191 | \& |
183 | .PP |
192 | \& // initialise a timer watcher, then start it |
184 | .Vb 3 |
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185 | \& /* simple non-repeating 5.5 second timeout */ |
193 | \& // simple non\-repeating 5.5 second timeout |
186 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
187 | \& ev_timer_start (loop, &timeout_watcher); |
195 | \& ev_timer_start (loop, &timeout_watcher); |
188 | .Ve |
196 | \& |
189 | .PP |
197 | \& // now wait for events to arrive |
190 | .Vb 2 |
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191 | \& /* loop till timeout or data ready */ |
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192 | \& ev_loop (loop, 0); |
198 | \& ev_loop (loop, 0); |
193 | .Ve |
199 | \& |
194 | .PP |
200 | \& // unloop was called, so exit |
195 | .Vb 2 |
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196 | \& return 0; |
201 | \& return 0; |
197 | \& } |
202 | \& } |
198 | .Ve |
203 | .Ve |
199 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
200 | .IX Header "DESCRIPTION" |
205 | .IX Header "DESCRIPTION" |
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206 | The newest version of this document is also available as an html-formatted |
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207 | web page you might find easier to navigate when reading it for the first |
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208 | time: <http://cvs.schmorp.de/libev/ev.html>. |
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209 | .PP |
201 | Libev is an event loop: you register interest in certain events (such as a |
210 | Libev is an event loop: you register interest in certain events (such as a |
202 | file descriptor being readable or a timeout occuring), and it will manage |
211 | file descriptor being readable or a timeout occurring), and it will manage |
203 | these event sources and provide your program with events. |
212 | these event sources and provide your program with events. |
204 | .PP |
213 | .PP |
205 | To do this, it must take more or less complete control over your process |
214 | To do this, it must take more or less complete control over your process |
206 | (or thread) by executing the \fIevent loop\fR handler, and will then |
215 | (or thread) by executing the \fIevent loop\fR handler, and will then |
207 | communicate events via a callback mechanism. |
216 | communicate events via a callback mechanism. |
208 | .PP |
217 | .PP |
209 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
210 | watchers\fR, which are relatively small C structures you initialise with the |
219 | watchers\fR, which are relatively small C structures you initialise with the |
211 | details of the event, and then hand it over to libev by \fIstarting\fR the |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
212 | watcher. |
221 | watcher. |
213 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
214 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
215 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
224 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
216 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
217 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
218 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
219 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
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224 | (\f(CW\*(C`ev_fork\*(C'\fR). |
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
225 | .PP |
234 | .PP |
226 | It also is quite fast (see this |
235 | It also is quite fast (see this |
227 | benchmark comparing it to libevent |
236 | benchmark comparing it to libevent |
228 | for example). |
237 | for example). |
229 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
230 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
231 | Libev is very configurable. In this manual the default configuration will |
240 | Libev is very configurable. In this manual the default (and most common) |
232 | be described, which supports multiple event loops. For more info about |
241 | configuration will be described, which supports multiple event loops. For |
233 | various configuration options please have a look at \fB\s-1EMBED\s0\fR section in |
242 | more info about various configuration options please have a look at |
234 | this manual. If libev was configured without support for multiple event |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
235 | loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR |
244 | for multiple event loops, then all functions taking an initial argument of |
236 | (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument. |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
237 | .SH "TIME REPRESENTATION" |
246 | this argument. |
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247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
238 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
239 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
240 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
250 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
241 | the beginning of 1970, details are complicated, don't ask). This type is |
251 | the beginning of 1970, details are complicated, don't ask). This type is |
242 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
252 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
243 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
253 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
244 | it, you should treat it as such. |
254 | it, you should treat it as some floatingpoint value. Unlike the name |
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255 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
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256 | throughout libev. |
245 | .SH "GLOBAL FUNCTIONS" |
257 | .SH "GLOBAL FUNCTIONS" |
246 | .IX Header "GLOBAL FUNCTIONS" |
258 | .IX Header "GLOBAL FUNCTIONS" |
247 | These functions can be called anytime, even before initialising the |
259 | These functions can be called anytime, even before initialising the |
248 | library in any way. |
260 | library in any way. |
249 | .IP "ev_tstamp ev_time ()" 4 |
261 | .IP "ev_tstamp ev_time ()" 4 |
250 | .IX Item "ev_tstamp ev_time ()" |
262 | .IX Item "ev_tstamp ev_time ()" |
251 | Returns the current time as libev would use it. Please note that the |
263 | Returns the current time as libev would use it. Please note that the |
252 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
264 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
253 | you actually want to know. |
265 | you actually want to know. |
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266 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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267 | .IX Item "ev_sleep (ev_tstamp interval)" |
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268 | Sleep for the given interval: The current thread will be blocked until |
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269 | either it is interrupted or the given time interval has passed. Basically |
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270 | this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
254 | .IP "int ev_version_major ()" 4 |
271 | .IP "int ev_version_major ()" 4 |
255 | .IX Item "int ev_version_major ()" |
272 | .IX Item "int ev_version_major ()" |
256 | .PD 0 |
273 | .PD 0 |
257 | .IP "int ev_version_minor ()" 4 |
274 | .IP "int ev_version_minor ()" 4 |
258 | .IX Item "int ev_version_minor ()" |
275 | .IX Item "int ev_version_minor ()" |
259 | .PD |
276 | .PD |
260 | You can find out the major and minor version numbers of the library |
277 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
261 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
278 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
262 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
279 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
263 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
280 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
264 | version of the library your program was compiled against. |
281 | version of the library your program was compiled against. |
265 | .Sp |
282 | .Sp |
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283 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
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284 | release version. |
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285 | .Sp |
266 | Usually, it's a good idea to terminate if the major versions mismatch, |
286 | Usually, it's a good idea to terminate if the major versions mismatch, |
267 | as this indicates an incompatible change. Minor versions are usually |
287 | as this indicates an incompatible change. Minor versions are usually |
268 | compatible to older versions, so a larger minor version alone is usually |
288 | compatible to older versions, so a larger minor version alone is usually |
269 | not a problem. |
289 | not a problem. |
270 | .Sp |
290 | .Sp |
271 | Example: Make sure we haven't accidentally been linked against the wrong |
291 | Example: Make sure we haven't accidentally been linked against the wrong |
272 | version. |
292 | version. |
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299 | (assuming you know what you are doing). This is the set of backends that |
319 | (assuming you know what you are doing). This is the set of backends that |
300 | libev will probe for if you specify no backends explicitly. |
320 | libev will probe for if you specify no backends explicitly. |
301 | .IP "unsigned int ev_embeddable_backends ()" 4 |
321 | .IP "unsigned int ev_embeddable_backends ()" 4 |
302 | .IX Item "unsigned int ev_embeddable_backends ()" |
322 | .IX Item "unsigned int ev_embeddable_backends ()" |
303 | Returns the set of backends that are embeddable in other event loops. This |
323 | Returns the set of backends that are embeddable in other event loops. This |
304 | is the theoretical, all\-platform, value. To find which backends |
324 | is the theoretical, all-platform, value. To find which backends |
305 | might be supported on the current system, you would need to look at |
325 | might be supported on the current system, you would need to look at |
306 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
326 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
307 | recommended ones. |
327 | recommended ones. |
308 | .Sp |
328 | .Sp |
309 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
329 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
310 | .IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 |
330 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
311 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" |
331 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
312 | Sets the allocation function to use (the prototype and semantics are |
332 | Sets the allocation function to use (the prototype is similar \- the |
313 | identical to the realloc C function). It is used to allocate and free |
333 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
314 | memory (no surprises here). If it returns zero when memory needs to be |
334 | used to allocate and free memory (no surprises here). If it returns zero |
315 | allocated, the library might abort or take some potentially destructive |
335 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
316 | action. The default is your system realloc function. |
336 | or take some potentially destructive action. |
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337 | .Sp |
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338 | Since some systems (at least OpenBSD and Darwin) fail to implement |
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339 | correct \f(CW\*(C`realloc\*(C'\fR semantics, libev will use a wrapper around the system |
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340 | \&\f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions by default. |
317 | .Sp |
341 | .Sp |
318 | You could override this function in high-availability programs to, say, |
342 | You could override this function in high-availability programs to, say, |
319 | free some memory if it cannot allocate memory, to use a special allocator, |
343 | free some memory if it cannot allocate memory, to use a special allocator, |
320 | or even to sleep a while and retry until some memory is available. |
344 | or even to sleep a while and retry until some memory is available. |
321 | .Sp |
345 | .Sp |
322 | Example: Replace the libev allocator with one that waits a bit and then |
346 | Example: Replace the libev allocator with one that waits a bit and then |
323 | retries). |
347 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
324 | .Sp |
348 | .Sp |
325 | .Vb 6 |
349 | .Vb 6 |
326 | \& static void * |
350 | \& static void * |
327 | \& persistent_realloc (void *ptr, size_t size) |
351 | \& persistent_realloc (void *ptr, size_t size) |
328 | \& { |
352 | \& { |
329 | \& for (;;) |
353 | \& for (;;) |
330 | \& { |
354 | \& { |
331 | \& void *newptr = realloc (ptr, size); |
355 | \& void *newptr = realloc (ptr, size); |
332 | .Ve |
356 | \& |
333 | .Sp |
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334 | .Vb 2 |
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335 | \& if (newptr) |
357 | \& if (newptr) |
336 | \& return newptr; |
358 | \& return newptr; |
337 | .Ve |
359 | \& |
338 | .Sp |
|
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339 | .Vb 3 |
|
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340 | \& sleep (60); |
360 | \& sleep (60); |
341 | \& } |
361 | \& } |
342 | \& } |
362 | \& } |
343 | .Ve |
363 | \& |
344 | .Sp |
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345 | .Vb 2 |
|
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346 | \& ... |
364 | \& ... |
347 | \& ev_set_allocator (persistent_realloc); |
365 | \& ev_set_allocator (persistent_realloc); |
348 | .Ve |
366 | .Ve |
349 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
367 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
350 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
368 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
… | |
… | |
363 | \& fatal_error (const char *msg) |
381 | \& fatal_error (const char *msg) |
364 | \& { |
382 | \& { |
365 | \& perror (msg); |
383 | \& perror (msg); |
366 | \& abort (); |
384 | \& abort (); |
367 | \& } |
385 | \& } |
368 | .Ve |
386 | \& |
369 | .Sp |
|
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370 | .Vb 2 |
|
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371 | \& ... |
387 | \& ... |
372 | \& ev_set_syserr_cb (fatal_error); |
388 | \& ev_set_syserr_cb (fatal_error); |
373 | .Ve |
389 | .Ve |
374 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
390 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
375 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
391 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
376 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
392 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
377 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
393 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
378 | events, and dynamically created loops which do not. |
394 | events, and dynamically created loops which do not. |
379 | .PP |
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380 | If you use threads, a common model is to run the default event loop |
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381 | in your main thread (or in a separate thread) and for each thread you |
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382 | create, you also create another event loop. Libev itself does no locking |
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383 | whatsoever, so if you mix calls to the same event loop in different |
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384 | threads, make sure you lock (this is usually a bad idea, though, even if |
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385 | done correctly, because it's hideous and inefficient). |
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386 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
395 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
387 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
396 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
388 | This will initialise the default event loop if it hasn't been initialised |
397 | This will initialise the default event loop if it hasn't been initialised |
389 | yet and return it. If the default loop could not be initialised, returns |
398 | yet and return it. If the default loop could not be initialised, returns |
390 | false. If it already was initialised it simply returns it (and ignores the |
399 | false. If it already was initialised it simply returns it (and ignores the |
391 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
400 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
392 | .Sp |
401 | .Sp |
393 | If you don't know what event loop to use, use the one returned from this |
402 | If you don't know what event loop to use, use the one returned from this |
394 | function. |
403 | function. |
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404 | .Sp |
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405 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
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406 | from multiple threads, you have to lock (note also that this is unlikely, |
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407 | as loops cannot bes hared easily between threads anyway). |
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408 | .Sp |
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409 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
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410 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
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411 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
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412 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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413 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
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414 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
395 | .Sp |
415 | .Sp |
396 | The flags argument can be used to specify special behaviour or specific |
416 | The flags argument can be used to specify special behaviour or specific |
397 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
417 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
398 | .Sp |
418 | .Sp |
399 | The following flags are supported: |
419 | The following flags are supported: |
… | |
… | |
410 | or setgid) then libev will \fInot\fR look at the environment variable |
430 | or setgid) then libev will \fInot\fR look at the environment variable |
411 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
431 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
412 | override the flags completely if it is found in the environment. This is |
432 | override the flags completely if it is found in the environment. This is |
413 | useful to try out specific backends to test their performance, or to work |
433 | useful to try out specific backends to test their performance, or to work |
414 | around bugs. |
434 | around bugs. |
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435 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
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436 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
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437 | .IX Item "EVFLAG_FORKCHECK" |
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438 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
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439 | a fork, you can also make libev check for a fork in each iteration by |
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440 | enabling this flag. |
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441 | .Sp |
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442 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
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443 | and thus this might slow down your event loop if you do a lot of loop |
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444 | iterations and little real work, but is usually not noticeable (on my |
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445 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
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446 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
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447 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
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448 | .Sp |
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449 | The big advantage of this flag is that you can forget about fork (and |
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450 | forget about forgetting to tell libev about forking) when you use this |
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451 | flag. |
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452 | .Sp |
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453 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
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454 | environment variable. |
415 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
455 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
416 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
456 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
417 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
457 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
418 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
458 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
419 | libev tries to roll its own fd_set with no limits on the number of fds, |
459 | libev tries to roll its own fd_set with no limits on the number of fds, |
420 | but if that fails, expect a fairly low limit on the number of fds when |
460 | but if that fails, expect a fairly low limit on the number of fds when |
421 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
461 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
422 | the fastest backend for a low number of fds. |
462 | usually the fastest backend for a low number of (low-numbered :) fds. |
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463 | .Sp |
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464 | To get good performance out of this backend you need a high amount of |
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465 | parallelity (most of the file descriptors should be busy). If you are |
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466 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
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467 | connections as possible during one iteration. You might also want to have |
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468 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
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469 | readyness notifications you get per iteration. |
423 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
470 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
424 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
471 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
425 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
472 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
426 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
473 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
427 | select, but handles sparse fds better and has no artificial limit on the |
474 | than select, but handles sparse fds better and has no artificial |
428 | number of fds you can use (except it will slow down considerably with a |
475 | limit on the number of fds you can use (except it will slow down |
429 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
476 | considerably with a lot of inactive fds). It scales similarly to select, |
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477 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
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478 | performance tips. |
430 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
479 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
431 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
480 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
432 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
481 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
433 | For few fds, this backend is a bit little slower than poll and select, |
482 | For few fds, this backend is a bit little slower than poll and select, |
434 | but it scales phenomenally better. While poll and select usually scale like |
483 | but it scales phenomenally better. While poll and select usually scale |
435 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
484 | like O(total_fds) where n is the total number of fds (or the highest fd), |
436 | either O(1) or O(active_fds). |
485 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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486 | of shortcomings, such as silently dropping events in some hard-to-detect |
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487 | cases and requiring a syscall per fd change, no fork support and bad |
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488 | support for dup. |
437 | .Sp |
489 | .Sp |
438 | While stopping and starting an I/O watcher in the same iteration will |
490 | While stopping, setting and starting an I/O watcher in the same iteration |
439 | result in some caching, there is still a syscall per such incident |
491 | will result in some caching, there is still a syscall per such incident |
440 | (because the fd could point to a different file description now), so its |
492 | (because the fd could point to a different file description now), so its |
441 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
493 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
442 | well if you register events for both fds. |
494 | very well if you register events for both fds. |
443 | .Sp |
495 | .Sp |
444 | Please note that epoll sometimes generates spurious notifications, so you |
496 | Please note that epoll sometimes generates spurious notifications, so you |
445 | need to use non-blocking I/O or other means to avoid blocking when no data |
497 | need to use non-blocking I/O or other means to avoid blocking when no data |
446 | (or space) is available. |
498 | (or space) is available. |
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499 | .Sp |
|
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500 | Best performance from this backend is achieved by not unregistering all |
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501 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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502 | keep at least one watcher active per fd at all times. |
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503 | .Sp |
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504 | While nominally embeddeble in other event loops, this feature is broken in |
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505 | all kernel versions tested so far. |
447 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
506 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
448 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
507 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
449 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
508 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
450 | Kqueue deserves special mention, as at the time of this writing, it |
509 | Kqueue deserves special mention, as at the time of this writing, it |
451 | was broken on all BSDs except NetBSD (usually it doesn't work with |
510 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
452 | anything but sockets and pipes, except on Darwin, where of course its |
511 | with anything but sockets and pipes, except on Darwin, where of course |
453 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
512 | it's completely useless). For this reason it's not being \*(L"autodetected\*(R" |
454 | unless you explicitly specify it explicitly in the flags (i.e. using |
513 | unless you explicitly specify it explicitly in the flags (i.e. using |
455 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
514 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
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515 | system like NetBSD. |
|
|
516 | .Sp |
|
|
517 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
518 | only for sockets (after having made sure that sockets work with kqueue on |
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519 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
456 | .Sp |
520 | .Sp |
457 | It scales in the same way as the epoll backend, but the interface to the |
521 | It scales in the same way as the epoll backend, but the interface to the |
458 | kernel is more efficient (which says nothing about its actual speed, of |
522 | kernel is more efficient (which says nothing about its actual speed, of |
459 | course). While starting and stopping an I/O watcher does not cause an |
523 | course). While stopping, setting and starting an I/O watcher does never |
460 | extra syscall as with epoll, it still adds up to four event changes per |
524 | cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
461 | incident, so its best to avoid that. |
525 | two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
|
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526 | drops fds silently in similarly hard-to-detect cases. |
|
|
527 | .Sp |
|
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528 | This backend usually performs well under most conditions. |
|
|
529 | .Sp |
|
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530 | While nominally embeddable in other event loops, this doesn't work |
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531 | everywhere, so you might need to test for this. And since it is broken |
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532 | almost everywhere, you should only use it when you have a lot of sockets |
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533 | (for which it usually works), by embedding it into another event loop |
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|
534 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for |
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535 | sockets. |
462 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
536 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
463 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
537 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
464 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
538 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
465 | This is not implemented yet (and might never be). |
539 | This is not implemented yet (and might never be, unless you send me an |
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540 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
541 | and is not embeddable, which would limit the usefulness of this backend |
|
|
542 | immensely. |
466 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
543 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
467 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
544 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
468 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
545 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
469 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
546 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
470 | it's really slow, but it still scales very well (O(active_fds)). |
547 | it's really slow, but it still scales very well (O(active_fds)). |
471 | .Sp |
548 | .Sp |
472 | Please note that solaris ports can result in a lot of spurious |
549 | Please note that solaris event ports can deliver a lot of spurious |
473 | notifications, so you need to use non-blocking I/O or other means to avoid |
550 | notifications, so you need to use non-blocking I/O or other means to avoid |
474 | blocking when no data (or space) is available. |
551 | blocking when no data (or space) is available. |
|
|
552 | .Sp |
|
|
553 | While this backend scales well, it requires one system call per active |
|
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554 | file descriptor per loop iteration. For small and medium numbers of file |
|
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555 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
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556 | might perform better. |
|
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557 | .Sp |
|
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558 | On the positive side, ignoring the spurious readyness notifications, this |
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559 | backend actually performed to specification in all tests and is fully |
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560 | embeddable, which is a rare feat among the OS-specific backends. |
475 | .ie n .IP """EVBACKEND_ALL""" 4 |
561 | .ie n .IP """EVBACKEND_ALL""" 4 |
476 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
562 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
477 | .IX Item "EVBACKEND_ALL" |
563 | .IX Item "EVBACKEND_ALL" |
478 | Try all backends (even potentially broken ones that wouldn't be tried |
564 | Try all backends (even potentially broken ones that wouldn't be tried |
479 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
565 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
480 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
566 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
567 | .Sp |
|
|
568 | It is definitely not recommended to use this flag. |
481 | .RE |
569 | .RE |
482 | .RS 4 |
570 | .RS 4 |
483 | .Sp |
571 | .Sp |
484 | If one or more of these are ored into the flags value, then only these |
572 | If one or more of these are ored into the flags value, then only these |
485 | backends will be tried (in the reverse order as given here). If none are |
573 | backends will be tried (in the reverse order as listed here). If none are |
486 | specified, most compiled-in backend will be tried, usually in reverse |
574 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
487 | order of their flag values :) |
|
|
488 | .Sp |
575 | .Sp |
489 | The most typical usage is like this: |
576 | The most typical usage is like this: |
490 | .Sp |
577 | .Sp |
491 | .Vb 2 |
578 | .Vb 2 |
492 | \& if (!ev_default_loop (0)) |
579 | \& if (!ev_default_loop (0)) |
… | |
… | |
513 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
600 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
514 | always distinct from the default loop. Unlike the default loop, it cannot |
601 | always distinct from the default loop. Unlike the default loop, it cannot |
515 | handle signal and child watchers, and attempts to do so will be greeted by |
602 | handle signal and child watchers, and attempts to do so will be greeted by |
516 | undefined behaviour (or a failed assertion if assertions are enabled). |
603 | undefined behaviour (or a failed assertion if assertions are enabled). |
517 | .Sp |
604 | .Sp |
|
|
605 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
606 | libev with threads is indeed to create one loop per thread, and using the |
|
|
607 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
608 | .Sp |
518 | Example: Try to create a event loop that uses epoll and nothing else. |
609 | Example: Try to create a event loop that uses epoll and nothing else. |
519 | .Sp |
610 | .Sp |
520 | .Vb 3 |
611 | .Vb 3 |
521 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
612 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
522 | \& if (!epoller) |
613 | \& if (!epoller) |
… | |
… | |
527 | Destroys the default loop again (frees all memory and kernel state |
618 | Destroys the default loop again (frees all memory and kernel state |
528 | etc.). None of the active event watchers will be stopped in the normal |
619 | etc.). None of the active event watchers will be stopped in the normal |
529 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
620 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
530 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
621 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
531 | calling this function, or cope with the fact afterwards (which is usually |
622 | calling this function, or cope with the fact afterwards (which is usually |
532 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
623 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
533 | for example). |
624 | for example). |
|
|
625 | .Sp |
|
|
626 | Note that certain global state, such as signal state, will not be freed by |
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|
627 | this function, and related watchers (such as signal and child watchers) |
|
|
628 | would need to be stopped manually. |
|
|
629 | .Sp |
|
|
630 | In general it is not advisable to call this function except in the |
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|
631 | rare occasion where you really need to free e.g. the signal handling |
|
|
632 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
633 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
534 | .IP "ev_loop_destroy (loop)" 4 |
634 | .IP "ev_loop_destroy (loop)" 4 |
535 | .IX Item "ev_loop_destroy (loop)" |
635 | .IX Item "ev_loop_destroy (loop)" |
536 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
636 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
537 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
637 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
538 | .IP "ev_default_fork ()" 4 |
638 | .IP "ev_default_fork ()" 4 |
539 | .IX Item "ev_default_fork ()" |
639 | .IX Item "ev_default_fork ()" |
|
|
640 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
540 | This function reinitialises the kernel state for backends that have |
641 | to reinitialise the kernel state for backends that have one. Despite the |
541 | one. Despite the name, you can call it anytime, but it makes most sense |
642 | name, you can call it anytime, but it makes most sense after forking, in |
542 | after forking, in either the parent or child process (or both, but that |
643 | the child process (or both child and parent, but that again makes little |
543 | again makes little sense). |
644 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
645 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
544 | .Sp |
646 | .Sp |
545 | You \fImust\fR call this function in the child process after forking if and |
647 | On the other hand, you only need to call this function in the child |
546 | only if you want to use the event library in both processes. If you just |
648 | process if and only if you want to use the event library in the child. If |
547 | fork+exec, you don't have to call it. |
649 | you just fork+exec, you don't have to call it at all. |
548 | .Sp |
650 | .Sp |
549 | The function itself is quite fast and it's usually not a problem to call |
651 | The function itself is quite fast and it's usually not a problem to call |
550 | it just in case after a fork. To make this easy, the function will fit in |
652 | it just in case after a fork. To make this easy, the function will fit in |
551 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
653 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
552 | .Sp |
654 | .Sp |
553 | .Vb 1 |
655 | .Vb 1 |
554 | \& pthread_atfork (0, 0, ev_default_fork); |
656 | \& pthread_atfork (0, 0, ev_default_fork); |
555 | .Ve |
657 | .Ve |
556 | .Sp |
|
|
557 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
558 | without calling this function, so if you force one of those backends you |
|
|
559 | do not need to care. |
|
|
560 | .IP "ev_loop_fork (loop)" 4 |
658 | .IP "ev_loop_fork (loop)" 4 |
561 | .IX Item "ev_loop_fork (loop)" |
659 | .IX Item "ev_loop_fork (loop)" |
562 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
660 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
563 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
661 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
564 | after fork, and how you do this is entirely your own problem. |
662 | after fork, and how you do this is entirely your own problem. |
|
|
663 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
664 | .IX Item "int ev_is_default_loop (loop)" |
|
|
665 | Returns true when the given loop actually is the default loop, false otherwise. |
|
|
666 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
667 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
668 | Returns the count of loop iterations for the loop, which is identical to |
|
|
669 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
670 | happily wraps around with enough iterations. |
|
|
671 | .Sp |
|
|
672 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
673 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
674 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
565 | .IP "unsigned int ev_backend (loop)" 4 |
675 | .IP "unsigned int ev_backend (loop)" 4 |
566 | .IX Item "unsigned int ev_backend (loop)" |
676 | .IX Item "unsigned int ev_backend (loop)" |
567 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
677 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
568 | use. |
678 | use. |
569 | .IP "ev_tstamp ev_now (loop)" 4 |
679 | .IP "ev_tstamp ev_now (loop)" 4 |
570 | .IX Item "ev_tstamp ev_now (loop)" |
680 | .IX Item "ev_tstamp ev_now (loop)" |
571 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
681 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
572 | received events and started processing them. This timestamp does not |
682 | received events and started processing them. This timestamp does not |
573 | change as long as callbacks are being processed, and this is also the base |
683 | change as long as callbacks are being processed, and this is also the base |
574 | time used for relative timers. You can treat it as the timestamp of the |
684 | time used for relative timers. You can treat it as the timestamp of the |
575 | event occuring (or more correctly, libev finding out about it). |
685 | event occurring (or more correctly, libev finding out about it). |
576 | .IP "ev_loop (loop, int flags)" 4 |
686 | .IP "ev_loop (loop, int flags)" 4 |
577 | .IX Item "ev_loop (loop, int flags)" |
687 | .IX Item "ev_loop (loop, int flags)" |
578 | Finally, this is it, the event handler. This function usually is called |
688 | Finally, this is it, the event handler. This function usually is called |
579 | after you initialised all your watchers and you want to start handling |
689 | after you initialised all your watchers and you want to start handling |
580 | events. |
690 | events. |
… | |
… | |
600 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
710 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
601 | usually a better approach for this kind of thing. |
711 | usually a better approach for this kind of thing. |
602 | .Sp |
712 | .Sp |
603 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
713 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
604 | .Sp |
714 | .Sp |
605 | .Vb 18 |
715 | .Vb 10 |
606 | \& * If there are no active watchers (reference count is zero), return. |
716 | \& \- Before the first iteration, call any pending watchers. |
607 | \& - Queue prepare watchers and then call all outstanding watchers. |
717 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
718 | \& \- If a fork was detected, queue and call all fork watchers. |
|
|
719 | \& \- Queue and call all prepare watchers. |
608 | \& - If we have been forked, recreate the kernel state. |
720 | \& \- If we have been forked, recreate the kernel state. |
609 | \& - Update the kernel state with all outstanding changes. |
721 | \& \- Update the kernel state with all outstanding changes. |
610 | \& - Update the "event loop time". |
722 | \& \- Update the "event loop time". |
611 | \& - Calculate for how long to block. |
723 | \& \- Calculate for how long to sleep or block, if at all |
|
|
724 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
725 | \& any active watchers at all will result in not sleeping). |
|
|
726 | \& \- Sleep if the I/O and timer collect interval say so. |
612 | \& - Block the process, waiting for any events. |
727 | \& \- Block the process, waiting for any events. |
613 | \& - Queue all outstanding I/O (fd) events. |
728 | \& \- Queue all outstanding I/O (fd) events. |
614 | \& - Update the "event loop time" and do time jump handling. |
729 | \& \- Update the "event loop time" and do time jump handling. |
615 | \& - Queue all outstanding timers. |
730 | \& \- Queue all outstanding timers. |
616 | \& - Queue all outstanding periodics. |
731 | \& \- Queue all outstanding periodics. |
617 | \& - If no events are pending now, queue all idle watchers. |
732 | \& \- If no events are pending now, queue all idle watchers. |
618 | \& - Queue all check watchers. |
733 | \& \- Queue all check watchers. |
619 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
734 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
620 | \& Signals and child watchers are implemented as I/O watchers, and will |
735 | \& Signals and child watchers are implemented as I/O watchers, and will |
621 | \& be handled here by queueing them when their watcher gets executed. |
736 | \& be handled here by queueing them when their watcher gets executed. |
622 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
737 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
623 | \& were used, return, otherwise continue with step *. |
738 | \& were used, or there are no active watchers, return, otherwise |
|
|
739 | \& continue with step *. |
624 | .Ve |
740 | .Ve |
625 | .Sp |
741 | .Sp |
626 | Example: Queue some jobs and then loop until no events are outsanding |
742 | Example: Queue some jobs and then loop until no events are outstanding |
627 | anymore. |
743 | anymore. |
628 | .Sp |
744 | .Sp |
629 | .Vb 4 |
745 | .Vb 4 |
630 | \& ... queue jobs here, make sure they register event watchers as long |
746 | \& ... queue jobs here, make sure they register event watchers as long |
631 | \& ... as they still have work to do (even an idle watcher will do..) |
747 | \& ... as they still have work to do (even an idle watcher will do..) |
… | |
… | |
636 | .IX Item "ev_unloop (loop, how)" |
752 | .IX Item "ev_unloop (loop, how)" |
637 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
753 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
638 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
754 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
639 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
755 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
640 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
756 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
757 | .Sp |
|
|
758 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
641 | .IP "ev_ref (loop)" 4 |
759 | .IP "ev_ref (loop)" 4 |
642 | .IX Item "ev_ref (loop)" |
760 | .IX Item "ev_ref (loop)" |
643 | .PD 0 |
761 | .PD 0 |
644 | .IP "ev_unref (loop)" 4 |
762 | .IP "ev_unref (loop)" 4 |
645 | .IX Item "ev_unref (loop)" |
763 | .IX Item "ev_unref (loop)" |
… | |
… | |
651 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
769 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
652 | example, libev itself uses this for its internal signal pipe: It is not |
770 | example, libev itself uses this for its internal signal pipe: It is not |
653 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
771 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
654 | no event watchers registered by it are active. It is also an excellent |
772 | no event watchers registered by it are active. It is also an excellent |
655 | way to do this for generic recurring timers or from within third-party |
773 | way to do this for generic recurring timers or from within third-party |
656 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
774 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
775 | (but only if the watcher wasn't active before, or was active before, |
|
|
776 | respectively). |
657 | .Sp |
777 | .Sp |
658 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
778 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
659 | running when nothing else is active. |
779 | running when nothing else is active. |
660 | .Sp |
780 | .Sp |
661 | .Vb 4 |
781 | .Vb 4 |
… | |
… | |
669 | .Sp |
789 | .Sp |
670 | .Vb 2 |
790 | .Vb 2 |
671 | \& ev_ref (loop); |
791 | \& ev_ref (loop); |
672 | \& ev_signal_stop (loop, &exitsig); |
792 | \& ev_signal_stop (loop, &exitsig); |
673 | .Ve |
793 | .Ve |
|
|
794 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
795 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
796 | .PD 0 |
|
|
797 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
798 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
799 | .PD |
|
|
800 | These advanced functions influence the time that libev will spend waiting |
|
|
801 | for events. Both are by default \f(CW0\fR, meaning that libev will try to |
|
|
802 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
803 | .Sp |
|
|
804 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
805 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
806 | increase efficiency of loop iterations. |
|
|
807 | .Sp |
|
|
808 | The background is that sometimes your program runs just fast enough to |
|
|
809 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
810 | the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
811 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
812 | overhead for the actual polling but can deliver many events at once. |
|
|
813 | .Sp |
|
|
814 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
815 | time collecting I/O events, so you can handle more events per iteration, |
|
|
816 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
817 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
818 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
819 | .Sp |
|
|
820 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
821 | to spend more time collecting timeouts, at the expense of increased |
|
|
822 | latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
|
|
823 | will not be affected. Setting this to a non-null value will not introduce |
|
|
824 | any overhead in libev. |
|
|
825 | .Sp |
|
|
826 | Many (busy) programs can usually benefit by setting the io collect |
|
|
827 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
828 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
829 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
830 | as this approsaches the timing granularity of most systems. |
674 | .SH "ANATOMY OF A WATCHER" |
831 | .SH "ANATOMY OF A WATCHER" |
675 | .IX Header "ANATOMY OF A WATCHER" |
832 | .IX Header "ANATOMY OF A WATCHER" |
676 | A watcher is a structure that you create and register to record your |
833 | A watcher is a structure that you create and register to record your |
677 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
834 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
678 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
835 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
681 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
838 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
682 | \& { |
839 | \& { |
683 | \& ev_io_stop (w); |
840 | \& ev_io_stop (w); |
684 | \& ev_unloop (loop, EVUNLOOP_ALL); |
841 | \& ev_unloop (loop, EVUNLOOP_ALL); |
685 | \& } |
842 | \& } |
686 | .Ve |
843 | \& |
687 | .PP |
|
|
688 | .Vb 6 |
|
|
689 | \& struct ev_loop *loop = ev_default_loop (0); |
844 | \& struct ev_loop *loop = ev_default_loop (0); |
690 | \& struct ev_io stdin_watcher; |
845 | \& struct ev_io stdin_watcher; |
691 | \& ev_init (&stdin_watcher, my_cb); |
846 | \& ev_init (&stdin_watcher, my_cb); |
692 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
847 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
693 | \& ev_io_start (loop, &stdin_watcher); |
848 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
781 | .ie n .IP """EV_FORK""" 4 |
936 | .ie n .IP """EV_FORK""" 4 |
782 | .el .IP "\f(CWEV_FORK\fR" 4 |
937 | .el .IP "\f(CWEV_FORK\fR" 4 |
783 | .IX Item "EV_FORK" |
938 | .IX Item "EV_FORK" |
784 | The event loop has been resumed in the child process after fork (see |
939 | The event loop has been resumed in the child process after fork (see |
785 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
940 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
941 | .ie n .IP """EV_ASYNC""" 4 |
|
|
942 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
943 | .IX Item "EV_ASYNC" |
|
|
944 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
786 | .ie n .IP """EV_ERROR""" 4 |
945 | .ie n .IP """EV_ERROR""" 4 |
787 | .el .IP "\f(CWEV_ERROR\fR" 4 |
946 | .el .IP "\f(CWEV_ERROR\fR" 4 |
788 | .IX Item "EV_ERROR" |
947 | .IX Item "EV_ERROR" |
789 | An unspecified error has occured, the watcher has been stopped. This might |
948 | An unspecified error has occured, the watcher has been stopped. This might |
790 | happen because the watcher could not be properly started because libev |
949 | happen because the watcher could not be properly started because libev |
… | |
… | |
855 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1014 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
856 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1015 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
857 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1016 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
858 | events but its callback has not yet been invoked). As long as a watcher |
1017 | events but its callback has not yet been invoked). As long as a watcher |
859 | is pending (but not active) you must not call an init function on it (but |
1018 | is pending (but not active) you must not call an init function on it (but |
860 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1019 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
861 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1020 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1021 | it). |
862 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1022 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
863 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1023 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
864 | Returns the callback currently set on the watcher. |
1024 | Returns the callback currently set on the watcher. |
865 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1025 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
866 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1026 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
867 | Change the callback. You can change the callback at virtually any time |
1027 | Change the callback. You can change the callback at virtually any time |
868 | (modulo threads). |
1028 | (modulo threads). |
|
|
1029 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1030 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1031 | .PD 0 |
|
|
1032 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1033 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1034 | .PD |
|
|
1035 | Set and query the priority of the watcher. The priority is a small |
|
|
1036 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1037 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1038 | before watchers with lower priority, but priority will not keep watchers |
|
|
1039 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1040 | .Sp |
|
|
1041 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1042 | invocation after new events have been received. This is useful, for |
|
|
1043 | example, to reduce latency after idling, or more often, to bind two |
|
|
1044 | watchers on the same event and make sure one is called first. |
|
|
1045 | .Sp |
|
|
1046 | If you need to suppress invocation when higher priority events are pending |
|
|
1047 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1048 | .Sp |
|
|
1049 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1050 | pending. |
|
|
1051 | .Sp |
|
|
1052 | The default priority used by watchers when no priority has been set is |
|
|
1053 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1054 | .Sp |
|
|
1055 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1056 | fine, as long as you do not mind that the priority value you query might |
|
|
1057 | or might not have been adjusted to be within valid range. |
|
|
1058 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1059 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1060 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
|
|
1061 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1062 | can deal with that fact. |
|
|
1063 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1064 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1065 | If the watcher is pending, this function returns clears its pending status |
|
|
1066 | and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1067 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
869 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1068 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
870 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1069 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
871 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1070 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
872 | and read at any time, libev will completely ignore it. This can be used |
1071 | and read at any time, libev will completely ignore it. This can be used |
873 | to associate arbitrary data with your watcher. If you need more data and |
1072 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
914 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
1113 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
915 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1114 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
916 | .PP |
1115 | .PP |
917 | .Vb 1 |
1116 | .Vb 1 |
918 | \& #include <stddef.h> |
1117 | \& #include <stddef.h> |
919 | .Ve |
1118 | \& |
920 | .PP |
|
|
921 | .Vb 6 |
|
|
922 | \& static void |
1119 | \& static void |
923 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1120 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
924 | \& { |
1121 | \& { |
925 | \& struct my_biggy big = (struct my_biggy * |
1122 | \& struct my_biggy big = (struct my_biggy * |
926 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
1123 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
927 | \& } |
1124 | \& } |
928 | .Ve |
1125 | \& |
929 | .PP |
|
|
930 | .Vb 6 |
|
|
931 | \& static void |
1126 | \& static void |
932 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1127 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
933 | \& { |
1128 | \& { |
934 | \& struct my_biggy big = (struct my_biggy * |
1129 | \& struct my_biggy big = (struct my_biggy * |
935 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
1130 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
936 | \& } |
1131 | \& } |
937 | .Ve |
1132 | .Ve |
938 | .SH "WATCHER TYPES" |
1133 | .SH "WATCHER TYPES" |
939 | .IX Header "WATCHER TYPES" |
1134 | .IX Header "WATCHER TYPES" |
940 | This section describes each watcher in detail, but will not repeat |
1135 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
963 | In general you can register as many read and/or write event watchers per |
1158 | In general you can register as many read and/or write event watchers per |
964 | fd as you want (as long as you don't confuse yourself). Setting all file |
1159 | fd as you want (as long as you don't confuse yourself). Setting all file |
965 | descriptors to non-blocking mode is also usually a good idea (but not |
1160 | descriptors to non-blocking mode is also usually a good idea (but not |
966 | required if you know what you are doing). |
1161 | required if you know what you are doing). |
967 | .PP |
1162 | .PP |
968 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
969 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
970 | descriptors correctly if you register interest in two or more fds pointing |
|
|
971 | to the same underlying file/socket/etc. description (that is, they share |
|
|
972 | the same underlying \*(L"file open\*(R"). |
|
|
973 | .PP |
|
|
974 | If you must do this, then force the use of a known-to-be-good backend |
1163 | If you must do this, then force the use of a known-to-be-good backend |
975 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1164 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
976 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1165 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
977 | .PP |
1166 | .PP |
978 | Another thing you have to watch out for is that it is quite easy to |
1167 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
984 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1173 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
985 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1174 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
986 | .PP |
1175 | .PP |
987 | If you cannot run the fd in non-blocking mode (for example you should not |
1176 | If you cannot run the fd in non-blocking mode (for example you should not |
988 | play around with an Xlib connection), then you have to seperately re-test |
1177 | play around with an Xlib connection), then you have to seperately re-test |
989 | wether a file descriptor is really ready with a known-to-be good interface |
1178 | whether a file descriptor is really ready with a known-to-be good interface |
990 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1179 | such as poll (fortunately in our Xlib example, Xlib already does this on |
991 | its own, so its quite safe to use). |
1180 | its own, so its quite safe to use). |
|
|
1181 | .PP |
|
|
1182 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1183 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1184 | .PP |
|
|
1185 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1186 | descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means, |
|
|
1187 | such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file |
|
|
1188 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1189 | this interest. If another file descriptor with the same number then is |
|
|
1190 | registered with libev, there is no efficient way to see that this is, in |
|
|
1191 | fact, a different file descriptor. |
|
|
1192 | .PP |
|
|
1193 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1194 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1195 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1196 | it is assumed that the file descriptor stays the same. That means that |
|
|
1197 | you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the |
|
|
1198 | descriptor even if the file descriptor number itself did not change. |
|
|
1199 | .PP |
|
|
1200 | This is how one would do it normally anyway, the important point is that |
|
|
1201 | the libev application should not optimise around libev but should leave |
|
|
1202 | optimisations to libev. |
|
|
1203 | .PP |
|
|
1204 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1205 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1206 | .PP |
|
|
1207 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1208 | but only events for the underlying file descriptions. That means when you |
|
|
1209 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1210 | events for them, only one file descriptor might actually receive events. |
|
|
1211 | .PP |
|
|
1212 | There is no workaround possible except not registering events |
|
|
1213 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1214 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1215 | .PP |
|
|
1216 | \fIThe special problem of fork\fR |
|
|
1217 | .IX Subsection "The special problem of fork" |
|
|
1218 | .PP |
|
|
1219 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1220 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1221 | it in the child. |
|
|
1222 | .PP |
|
|
1223 | To support fork in your programs, you either have to call |
|
|
1224 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1225 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1226 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1227 | .PP |
|
|
1228 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1229 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1230 | .PP |
|
|
1231 | While not really specific to libev, it is easy to forget about \s-1SIGPIPE:\s0 |
|
|
1232 | when reading from a pipe whose other end has been closed, your program |
|
|
1233 | gets send a \s-1SIGPIPE\s0, which, by default, aborts your program. For most |
|
|
1234 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1235 | undesirable. |
|
|
1236 | .PP |
|
|
1237 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1238 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1239 | somewhere, as that would have given you a big clue). |
|
|
1240 | .PP |
|
|
1241 | \fIWatcher-Specific Functions\fR |
|
|
1242 | .IX Subsection "Watcher-Specific Functions" |
992 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1243 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
993 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1244 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
994 | .PD 0 |
1245 | .PD 0 |
995 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1246 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
996 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1247 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
… | |
… | |
1003 | The file descriptor being watched. |
1254 | The file descriptor being watched. |
1004 | .IP "int events [read\-only]" 4 |
1255 | .IP "int events [read\-only]" 4 |
1005 | .IX Item "int events [read-only]" |
1256 | .IX Item "int events [read-only]" |
1006 | The events being watched. |
1257 | The events being watched. |
1007 | .PP |
1258 | .PP |
|
|
1259 | \fIExamples\fR |
|
|
1260 | .IX Subsection "Examples" |
|
|
1261 | .PP |
1008 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1262 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1009 | readable, but only once. Since it is likely line\-buffered, you could |
1263 | readable, but only once. Since it is likely line-buffered, you could |
1010 | attempt to read a whole line in the callback. |
1264 | attempt to read a whole line in the callback. |
1011 | .PP |
1265 | .PP |
1012 | .Vb 6 |
1266 | .Vb 6 |
1013 | \& static void |
1267 | \& static void |
1014 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1268 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1015 | \& { |
1269 | \& { |
1016 | \& ev_io_stop (loop, w); |
1270 | \& ev_io_stop (loop, w); |
1017 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1271 | \& .. read from stdin here (or from w\->fd) and haqndle any I/O errors |
1018 | \& } |
1272 | \& } |
1019 | .Ve |
1273 | \& |
1020 | .PP |
|
|
1021 | .Vb 6 |
|
|
1022 | \& ... |
1274 | \& ... |
1023 | \& struct ev_loop *loop = ev_default_init (0); |
1275 | \& struct ev_loop *loop = ev_default_init (0); |
1024 | \& struct ev_io stdin_readable; |
1276 | \& struct ev_io stdin_readable; |
1025 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1277 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1026 | \& ev_io_start (loop, &stdin_readable); |
1278 | \& ev_io_start (loop, &stdin_readable); |
… | |
… | |
1043 | of the event triggering whatever timeout you are modifying/starting. If |
1295 | of the event triggering whatever timeout you are modifying/starting. If |
1044 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1296 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1045 | on the current time, use something like this to adjust for this: |
1297 | on the current time, use something like this to adjust for this: |
1046 | .PP |
1298 | .PP |
1047 | .Vb 1 |
1299 | .Vb 1 |
1048 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1300 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1049 | .Ve |
1301 | .Ve |
1050 | .PP |
1302 | .PP |
1051 | The callback is guarenteed to be invoked only when its timeout has passed, |
1303 | The callback is guarenteed to be invoked only when its timeout has passed, |
1052 | but if multiple timers become ready during the same loop iteration then |
1304 | but if multiple timers become ready during the same loop iteration then |
1053 | order of execution is undefined. |
1305 | order of execution is undefined. |
|
|
1306 | .PP |
|
|
1307 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1308 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1054 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1309 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1055 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1310 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1056 | .PD 0 |
1311 | .PD 0 |
1057 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1312 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1058 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1313 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1065 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1320 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1066 | configure a timer to trigger every 10 seconds, then it will trigger at |
1321 | configure a timer to trigger every 10 seconds, then it will trigger at |
1067 | exactly 10 second intervals. If, however, your program cannot keep up with |
1322 | exactly 10 second intervals. If, however, your program cannot keep up with |
1068 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1323 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1069 | timer will not fire more than once per event loop iteration. |
1324 | timer will not fire more than once per event loop iteration. |
1070 | .IP "ev_timer_again (loop)" 4 |
1325 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1071 | .IX Item "ev_timer_again (loop)" |
1326 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1072 | This will act as if the timer timed out and restart it again if it is |
1327 | This will act as if the timer timed out and restart it again if it is |
1073 | repeating. The exact semantics are: |
1328 | repeating. The exact semantics are: |
1074 | .Sp |
1329 | .Sp |
|
|
1330 | If the timer is pending, its pending status is cleared. |
|
|
1331 | .Sp |
1075 | If the timer is started but nonrepeating, stop it. |
1332 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1076 | .Sp |
1333 | .Sp |
1077 | If the timer is repeating, either start it if necessary (with the repeat |
1334 | If the timer is repeating, either start it if necessary (with the |
1078 | value), or reset the running timer to the repeat value. |
1335 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1079 | .Sp |
1336 | .Sp |
1080 | This sounds a bit complicated, but here is a useful and typical |
1337 | This sounds a bit complicated, but here is a useful and typical |
1081 | example: Imagine you have a tcp connection and you want a so-called |
1338 | example: Imagine you have a tcp connection and you want a so-called idle |
1082 | idle timeout, that is, you want to be called when there have been, |
1339 | timeout, that is, you want to be called when there have been, say, 60 |
1083 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1340 | seconds of inactivity on the socket. The easiest way to do this is to |
1084 | this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling |
1341 | configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call |
1085 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
1342 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
1086 | you go into an idle state where you do not expect data to travel on the |
1343 | you go into an idle state where you do not expect data to travel on the |
1087 | socket, you can stop the timer, and again will automatically restart it if |
1344 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
1088 | need be. |
1345 | automatically restart it if need be. |
1089 | .Sp |
1346 | .Sp |
1090 | You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether |
1347 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
1091 | and only ever use the \f(CW\*(C`repeat\*(C'\fR value: |
1348 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
1092 | .Sp |
1349 | .Sp |
1093 | .Vb 8 |
1350 | .Vb 8 |
1094 | \& ev_timer_init (timer, callback, 0., 5.); |
1351 | \& ev_timer_init (timer, callback, 0., 5.); |
1095 | \& ev_timer_again (loop, timer); |
1352 | \& ev_timer_again (loop, timer); |
1096 | \& ... |
1353 | \& ... |
1097 | \& timer->again = 17.; |
1354 | \& timer\->again = 17.; |
1098 | \& ev_timer_again (loop, timer); |
1355 | \& ev_timer_again (loop, timer); |
1099 | \& ... |
1356 | \& ... |
1100 | \& timer->again = 10.; |
1357 | \& timer\->again = 10.; |
1101 | \& ev_timer_again (loop, timer); |
1358 | \& ev_timer_again (loop, timer); |
1102 | .Ve |
1359 | .Ve |
1103 | .Sp |
1360 | .Sp |
1104 | This is more efficient then stopping/starting the timer eahc time you want |
1361 | This is more slightly efficient then stopping/starting the timer each time |
1105 | to modify its timeout value. |
1362 | you want to modify its timeout value. |
1106 | .IP "ev_tstamp repeat [read\-write]" 4 |
1363 | .IP "ev_tstamp repeat [read\-write]" 4 |
1107 | .IX Item "ev_tstamp repeat [read-write]" |
1364 | .IX Item "ev_tstamp repeat [read-write]" |
1108 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1365 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1109 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1366 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1110 | which is also when any modifications are taken into account. |
1367 | which is also when any modifications are taken into account. |
|
|
1368 | .PP |
|
|
1369 | \fIExamples\fR |
|
|
1370 | .IX Subsection "Examples" |
1111 | .PP |
1371 | .PP |
1112 | Example: Create a timer that fires after 60 seconds. |
1372 | Example: Create a timer that fires after 60 seconds. |
1113 | .PP |
1373 | .PP |
1114 | .Vb 5 |
1374 | .Vb 5 |
1115 | \& static void |
1375 | \& static void |
1116 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1376 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1117 | \& { |
1377 | \& { |
1118 | \& .. one minute over, w is actually stopped right here |
1378 | \& .. one minute over, w is actually stopped right here |
1119 | \& } |
1379 | \& } |
1120 | .Ve |
1380 | \& |
1121 | .PP |
|
|
1122 | .Vb 3 |
|
|
1123 | \& struct ev_timer mytimer; |
1381 | \& struct ev_timer mytimer; |
1124 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1382 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1125 | \& ev_timer_start (loop, &mytimer); |
1383 | \& ev_timer_start (loop, &mytimer); |
1126 | .Ve |
1384 | .Ve |
1127 | .PP |
1385 | .PP |
… | |
… | |
1132 | \& static void |
1390 | \& static void |
1133 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1391 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1134 | \& { |
1392 | \& { |
1135 | \& .. ten seconds without any activity |
1393 | \& .. ten seconds without any activity |
1136 | \& } |
1394 | \& } |
1137 | .Ve |
1395 | \& |
1138 | .PP |
|
|
1139 | .Vb 4 |
|
|
1140 | \& struct ev_timer mytimer; |
1396 | \& struct ev_timer mytimer; |
1141 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1397 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1142 | \& ev_timer_again (&mytimer); /* start timer */ |
1398 | \& ev_timer_again (&mytimer); /* start timer */ |
1143 | \& ev_loop (loop, 0); |
1399 | \& ev_loop (loop, 0); |
1144 | .Ve |
1400 | \& |
1145 | .PP |
|
|
1146 | .Vb 3 |
|
|
1147 | \& // and in some piece of code that gets executed on any "activity": |
1401 | \& // and in some piece of code that gets executed on any "activity": |
1148 | \& // reset the timeout to start ticking again at 10 seconds |
1402 | \& // reset the timeout to start ticking again at 10 seconds |
1149 | \& ev_timer_again (&mytimer); |
1403 | \& ev_timer_again (&mytimer); |
1150 | .Ve |
1404 | .Ve |
1151 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1405 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
… | |
… | |
1158 | but on wallclock time (absolute time). You can tell a periodic watcher |
1412 | but on wallclock time (absolute time). You can tell a periodic watcher |
1159 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1413 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1160 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1414 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1161 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1415 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1162 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1416 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1163 | roughly 10 seconds later and of course not if you reset your system time |
1417 | roughly 10 seconds later). |
1164 | again). |
|
|
1165 | .PP |
1418 | .PP |
1166 | They can also be used to implement vastly more complex timers, such as |
1419 | They can also be used to implement vastly more complex timers, such as |
1167 | triggering an event on eahc midnight, local time. |
1420 | triggering an event on each midnight, local time or other, complicated, |
|
|
1421 | rules. |
1168 | .PP |
1422 | .PP |
1169 | As with timers, the callback is guarenteed to be invoked only when the |
1423 | As with timers, the callback is guarenteed to be invoked only when the |
1170 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1424 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1171 | during the same loop iteration then order of execution is undefined. |
1425 | during the same loop iteration then order of execution is undefined. |
|
|
1426 | .PP |
|
|
1427 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1428 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1172 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1429 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1173 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1430 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1174 | .PD 0 |
1431 | .PD 0 |
1175 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1432 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1176 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1433 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1177 | .PD |
1434 | .PD |
1178 | Lots of arguments, lets sort it out... There are basically three modes of |
1435 | Lots of arguments, lets sort it out... There are basically three modes of |
1179 | operation, and we will explain them from simplest to complex: |
1436 | operation, and we will explain them from simplest to complex: |
1180 | .RS 4 |
1437 | .RS 4 |
|
|
1438 | .IP "\(bu" 4 |
1181 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1439 | absolute timer (at = time, interval = reschedule_cb = 0) |
1182 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1440 | .Sp |
1183 | In this configuration the watcher triggers an event at the wallclock time |
1441 | In this configuration the watcher triggers an event at the wallclock time |
1184 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1442 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1185 | that is, if it is to be run at January 1st 2011 then it will run when the |
1443 | that is, if it is to be run at January 1st 2011 then it will run when the |
1186 | system time reaches or surpasses this time. |
1444 | system time reaches or surpasses this time. |
|
|
1445 | .IP "\(bu" 4 |
1187 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1446 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1188 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1447 | .Sp |
1189 | In this mode the watcher will always be scheduled to time out at the next |
1448 | In this mode the watcher will always be scheduled to time out at the next |
1190 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1449 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1191 | of any time jumps. |
1450 | and then repeat, regardless of any time jumps. |
1192 | .Sp |
1451 | .Sp |
1193 | This can be used to create timers that do not drift with respect to system |
1452 | This can be used to create timers that do not drift with respect to system |
1194 | time: |
1453 | time: |
1195 | .Sp |
1454 | .Sp |
1196 | .Vb 1 |
1455 | .Vb 1 |
… | |
… | |
1203 | by 3600. |
1462 | by 3600. |
1204 | .Sp |
1463 | .Sp |
1205 | Another way to think about it (for the mathematically inclined) is that |
1464 | Another way to think about it (for the mathematically inclined) is that |
1206 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1465 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1207 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1466 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1208 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1467 | .Sp |
1209 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1468 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1469 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1470 | this value. |
|
|
1471 | .IP "\(bu" 4 |
|
|
1472 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
|
|
1473 | .Sp |
1210 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1474 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1211 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1475 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1212 | reschedule callback will be called with the watcher as first, and the |
1476 | reschedule callback will be called with the watcher as first, and the |
1213 | current time as second argument. |
1477 | current time as second argument. |
1214 | .Sp |
1478 | .Sp |
1215 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1479 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1216 | ever, or make any event loop modifications\fR. If you need to stop it, |
1480 | ever, or make any event loop modifications\fR. If you need to stop it, |
1217 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1481 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
1218 | starting a prepare watcher). |
1482 | starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal). |
1219 | .Sp |
1483 | .Sp |
1220 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1484 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1221 | ev_tstamp now)\*(C'\fR, e.g.: |
1485 | ev_tstamp now)\*(C'\fR, e.g.: |
1222 | .Sp |
1486 | .Sp |
1223 | .Vb 4 |
1487 | .Vb 4 |
… | |
… | |
1247 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1511 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1248 | Simply stops and restarts the periodic watcher again. This is only useful |
1512 | Simply stops and restarts the periodic watcher again. This is only useful |
1249 | when you changed some parameters or the reschedule callback would return |
1513 | when you changed some parameters or the reschedule callback would return |
1250 | a different time than the last time it was called (e.g. in a crond like |
1514 | a different time than the last time it was called (e.g. in a crond like |
1251 | program when the crontabs have changed). |
1515 | program when the crontabs have changed). |
|
|
1516 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1517 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1518 | When repeating, this contains the offset value, otherwise this is the |
|
|
1519 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1520 | .Sp |
|
|
1521 | Can be modified any time, but changes only take effect when the periodic |
|
|
1522 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1252 | .IP "ev_tstamp interval [read\-write]" 4 |
1523 | .IP "ev_tstamp interval [read\-write]" 4 |
1253 | .IX Item "ev_tstamp interval [read-write]" |
1524 | .IX Item "ev_tstamp interval [read-write]" |
1254 | The current interval value. Can be modified any time, but changes only |
1525 | The current interval value. Can be modified any time, but changes only |
1255 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1526 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1256 | called. |
1527 | called. |
1257 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1528 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1258 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1529 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1259 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1530 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1260 | switched off. Can be changed any time, but changes only take effect when |
1531 | switched off. Can be changed any time, but changes only take effect when |
1261 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1532 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
|
|
1533 | .IP "ev_tstamp at [read\-only]" 4 |
|
|
1534 | .IX Item "ev_tstamp at [read-only]" |
|
|
1535 | When active, contains the absolute time that the watcher is supposed to |
|
|
1536 | trigger next. |
|
|
1537 | .PP |
|
|
1538 | \fIExamples\fR |
|
|
1539 | .IX Subsection "Examples" |
1262 | .PP |
1540 | .PP |
1263 | Example: Call a callback every hour, or, more precisely, whenever the |
1541 | Example: Call a callback every hour, or, more precisely, whenever the |
1264 | system clock is divisible by 3600. The callback invocation times have |
1542 | system clock is divisible by 3600. The callback invocation times have |
1265 | potentially a lot of jittering, but good long-term stability. |
1543 | potentially a lot of jittering, but good long-term stability. |
1266 | .PP |
1544 | .PP |
… | |
… | |
1268 | \& static void |
1546 | \& static void |
1269 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1547 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1270 | \& { |
1548 | \& { |
1271 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1549 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1272 | \& } |
1550 | \& } |
1273 | .Ve |
1551 | \& |
1274 | .PP |
|
|
1275 | .Vb 3 |
|
|
1276 | \& struct ev_periodic hourly_tick; |
1552 | \& struct ev_periodic hourly_tick; |
1277 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1553 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1278 | \& ev_periodic_start (loop, &hourly_tick); |
1554 | \& ev_periodic_start (loop, &hourly_tick); |
1279 | .Ve |
1555 | .Ve |
1280 | .PP |
1556 | .PP |
1281 | Example: The same as above, but use a reschedule callback to do it: |
1557 | Example: The same as above, but use a reschedule callback to do it: |
1282 | .PP |
1558 | .PP |
1283 | .Vb 1 |
1559 | .Vb 1 |
1284 | \& #include <math.h> |
1560 | \& #include <math.h> |
1285 | .Ve |
1561 | \& |
1286 | .PP |
|
|
1287 | .Vb 5 |
|
|
1288 | \& static ev_tstamp |
1562 | \& static ev_tstamp |
1289 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1563 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1290 | \& { |
1564 | \& { |
1291 | \& return fmod (now, 3600.) + 3600.; |
1565 | \& return fmod (now, 3600.) + 3600.; |
1292 | \& } |
1566 | \& } |
1293 | .Ve |
1567 | \& |
1294 | .PP |
|
|
1295 | .Vb 1 |
|
|
1296 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1568 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1297 | .Ve |
1569 | .Ve |
1298 | .PP |
1570 | .PP |
1299 | Example: Call a callback every hour, starting now: |
1571 | Example: Call a callback every hour, starting now: |
1300 | .PP |
1572 | .PP |
… | |
… | |
1316 | first watcher gets started will libev actually register a signal watcher |
1588 | first watcher gets started will libev actually register a signal watcher |
1317 | with the kernel (thus it coexists with your own signal handlers as long |
1589 | with the kernel (thus it coexists with your own signal handlers as long |
1318 | as you don't register any with libev). Similarly, when the last signal |
1590 | as you don't register any with libev). Similarly, when the last signal |
1319 | watcher for a signal is stopped libev will reset the signal handler to |
1591 | watcher for a signal is stopped libev will reset the signal handler to |
1320 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1592 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1593 | .PP |
|
|
1594 | If possible and supported, libev will install its handlers with |
|
|
1595 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly |
|
|
1596 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1597 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1598 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
1599 | .PP |
|
|
1600 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1601 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1321 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1602 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1322 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1603 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1323 | .PD 0 |
1604 | .PD 0 |
1324 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1605 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1325 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1606 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
… | |
… | |
1327 | Configures the watcher to trigger on the given signal number (usually one |
1608 | Configures the watcher to trigger on the given signal number (usually one |
1328 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1609 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1329 | .IP "int signum [read\-only]" 4 |
1610 | .IP "int signum [read\-only]" 4 |
1330 | .IX Item "int signum [read-only]" |
1611 | .IX Item "int signum [read-only]" |
1331 | The signal the watcher watches out for. |
1612 | The signal the watcher watches out for. |
|
|
1613 | .PP |
|
|
1614 | \fIExamples\fR |
|
|
1615 | .IX Subsection "Examples" |
|
|
1616 | .PP |
|
|
1617 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1618 | .PP |
|
|
1619 | .Vb 5 |
|
|
1620 | \& static void |
|
|
1621 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1622 | \& { |
|
|
1623 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1624 | \& } |
|
|
1625 | \& |
|
|
1626 | \& struct ev_signal signal_watcher; |
|
|
1627 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1628 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1629 | .Ve |
1332 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1630 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1333 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1631 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1334 | .IX Subsection "ev_child - watch out for process status changes" |
1632 | .IX Subsection "ev_child - watch out for process status changes" |
1335 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1633 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1336 | some child status changes (most typically when a child of yours dies). |
1634 | some child status changes (most typically when a child of yours dies). It |
|
|
1635 | is permissible to install a child watcher \fIafter\fR the child has been |
|
|
1636 | forked (which implies it might have already exited), as long as the event |
|
|
1637 | loop isn't entered (or is continued from a watcher). |
|
|
1638 | .PP |
|
|
1639 | Only the default event loop is capable of handling signals, and therefore |
|
|
1640 | you can only rgeister child watchers in the default event loop. |
|
|
1641 | .PP |
|
|
1642 | \fIProcess Interaction\fR |
|
|
1643 | .IX Subsection "Process Interaction" |
|
|
1644 | .PP |
|
|
1645 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1646 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1647 | the first child watcher is started after the child exits. The occurance |
|
|
1648 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1649 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1650 | children, even ones not watched. |
|
|
1651 | .PP |
|
|
1652 | \fIOverriding the Built-In Processing\fR |
|
|
1653 | .IX Subsection "Overriding the Built-In Processing" |
|
|
1654 | .PP |
|
|
1655 | Libev offers no special support for overriding the built-in child |
|
|
1656 | processing, but if your application collides with libev's default child |
|
|
1657 | handler, you can override it easily by installing your own handler for |
|
|
1658 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
1659 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1660 | event-based approach to child reaping and thus use libev's support for |
|
|
1661 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
1662 | .PP |
|
|
1663 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1664 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1337 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1665 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1338 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1666 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1339 | .PD 0 |
1667 | .PD 0 |
1340 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1668 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1341 | .IX Item "ev_child_set (ev_child *, int pid)" |
1669 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1342 | .PD |
1670 | .PD |
1343 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1671 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1344 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1672 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1345 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1673 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1346 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1674 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1347 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1675 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1348 | process causing the status change. |
1676 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
1677 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
1678 | activate the watcher when the process is stopped or continued). |
1349 | .IP "int pid [read\-only]" 4 |
1679 | .IP "int pid [read\-only]" 4 |
1350 | .IX Item "int pid [read-only]" |
1680 | .IX Item "int pid [read-only]" |
1351 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1681 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1352 | .IP "int rpid [read\-write]" 4 |
1682 | .IP "int rpid [read\-write]" 4 |
1353 | .IX Item "int rpid [read-write]" |
1683 | .IX Item "int rpid [read-write]" |
… | |
… | |
1355 | .IP "int rstatus [read\-write]" 4 |
1685 | .IP "int rstatus [read\-write]" 4 |
1356 | .IX Item "int rstatus [read-write]" |
1686 | .IX Item "int rstatus [read-write]" |
1357 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1687 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1358 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1688 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1359 | .PP |
1689 | .PP |
1360 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
1690 | \fIExamples\fR |
|
|
1691 | .IX Subsection "Examples" |
1361 | .PP |
1692 | .PP |
|
|
1693 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
1694 | its completion. |
|
|
1695 | .PP |
1362 | .Vb 5 |
1696 | .Vb 1 |
|
|
1697 | \& ev_child cw; |
|
|
1698 | \& |
1363 | \& static void |
1699 | \& static void |
1364 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1700 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
1365 | \& { |
1701 | \& { |
1366 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1702 | \& ev_child_stop (EV_A_ w); |
|
|
1703 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1367 | \& } |
1704 | \& } |
1368 | .Ve |
1705 | \& |
1369 | .PP |
1706 | \& pid_t pid = fork (); |
1370 | .Vb 3 |
1707 | \& |
1371 | \& struct ev_signal signal_watcher; |
1708 | \& if (pid < 0) |
1372 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1709 | \& // error |
1373 | \& ev_signal_start (loop, &sigint_cb); |
1710 | \& else if (pid == 0) |
|
|
1711 | \& { |
|
|
1712 | \& // the forked child executes here |
|
|
1713 | \& exit (1); |
|
|
1714 | \& } |
|
|
1715 | \& else |
|
|
1716 | \& { |
|
|
1717 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
1718 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
1719 | \& } |
1374 | .Ve |
1720 | .Ve |
1375 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1721 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1376 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1722 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1377 | .IX Subsection "ev_stat - did the file attributes just change?" |
1723 | .IX Subsection "ev_stat - did the file attributes just change?" |
1378 | This watches a filesystem path for attribute changes. That is, it calls |
1724 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1382 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1728 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1383 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
1729 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
1384 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
1730 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
1385 | otherwise always forced to be at least one) and all the other fields of |
1731 | otherwise always forced to be at least one) and all the other fields of |
1386 | the stat buffer having unspecified contents. |
1732 | the stat buffer having unspecified contents. |
|
|
1733 | .PP |
|
|
1734 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
|
|
1735 | relative and your working directory changes, the behaviour is undefined. |
1387 | .PP |
1736 | .PP |
1388 | Since there is no standard to do this, the portable implementation simply |
1737 | Since there is no standard to do this, the portable implementation simply |
1389 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
1738 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
1390 | can specify a recommended polling interval for this case. If you specify |
1739 | can specify a recommended polling interval for this case. If you specify |
1391 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
1740 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
… | |
… | |
1394 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1743 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1395 | usually overkill. |
1744 | usually overkill. |
1396 | .PP |
1745 | .PP |
1397 | This watcher type is not meant for massive numbers of stat watchers, |
1746 | This watcher type is not meant for massive numbers of stat watchers, |
1398 | as even with OS-supported change notifications, this can be |
1747 | as even with OS-supported change notifications, this can be |
1399 | resource\-intensive. |
1748 | resource-intensive. |
1400 | .PP |
1749 | .PP |
1401 | At the time of this writing, only the Linux inotify interface is |
1750 | At the time of this writing, only the Linux inotify interface is |
1402 | implemented (implementing kqueue support is left as an exercise for the |
1751 | implemented (implementing kqueue support is left as an exercise for the |
1403 | reader). Inotify will be used to give hints only and should not change the |
1752 | reader). Inotify will be used to give hints only and should not change the |
1404 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
1753 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
1405 | to fall back to regular polling again even with inotify, but changes are |
1754 | to fall back to regular polling again even with inotify, but changes are |
1406 | usually detected immediately, and if the file exists there will be no |
1755 | usually detected immediately, and if the file exists there will be no |
1407 | polling. |
1756 | polling. |
|
|
1757 | .PP |
|
|
1758 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
1759 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
1760 | .PP |
|
|
1761 | Libev by default (unless the user overrides this) uses the default |
|
|
1762 | compilation environment, which means that on systems with optionally |
|
|
1763 | disabled large file support, you get the 32 bit version of the stat |
|
|
1764 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
1765 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1766 | compile libev with the same flags to get binary compatibility. This is |
|
|
1767 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
1768 | most noticably with ev_stat and largefile support. |
|
|
1769 | .PP |
|
|
1770 | \fIInotify\fR |
|
|
1771 | .IX Subsection "Inotify" |
|
|
1772 | .PP |
|
|
1773 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1774 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1775 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1776 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1777 | .PP |
|
|
1778 | Inotify presense does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1779 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1780 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presense of inotify support |
|
|
1781 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1782 | .PP |
|
|
1783 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1784 | implement this functionality, due to the requirement of having a file |
|
|
1785 | descriptor open on the object at all times). |
|
|
1786 | .PP |
|
|
1787 | \fIThe special problem of stat time resolution\fR |
|
|
1788 | .IX Subsection "The special problem of stat time resolution" |
|
|
1789 | .PP |
|
|
1790 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1791 | even on systems where the resolution is higher, many filesystems still |
|
|
1792 | only support whole seconds. |
|
|
1793 | .PP |
|
|
1794 | That means that, if the time is the only thing that changes, you might |
|
|
1795 | miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and calls |
|
|
1796 | your callback, which does something. When there is another update within |
|
|
1797 | the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it. |
|
|
1798 | .PP |
|
|
1799 | The solution to this is to delay acting on a change for a second (or till |
|
|
1800 | the next second boundary), using a roughly one-second delay \f(CW\*(C`ev_timer\*(C'\fR |
|
|
1801 | (\f(CW\*(C`ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)\*(C'\fR). The \f(CW.01\fR |
|
|
1802 | is added to work around small timing inconsistencies of some operating |
|
|
1803 | systems. |
|
|
1804 | .PP |
|
|
1805 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1806 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1408 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1807 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1409 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1808 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1410 | .PD 0 |
1809 | .PD 0 |
1411 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1810 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1412 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
1811 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
… | |
… | |
1418 | path for as long as the watcher is active. |
1817 | path for as long as the watcher is active. |
1419 | .Sp |
1818 | .Sp |
1420 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1819 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1421 | relative to the attributes at the time the watcher was started (or the |
1820 | relative to the attributes at the time the watcher was started (or the |
1422 | last change was detected). |
1821 | last change was detected). |
1423 | .IP "ev_stat_stat (ev_stat *)" 4 |
1822 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1424 | .IX Item "ev_stat_stat (ev_stat *)" |
1823 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1425 | Updates the stat buffer immediately with new values. If you change the |
1824 | Updates the stat buffer immediately with new values. If you change the |
1426 | watched path in your callback, you could call this fucntion to avoid |
1825 | watched path in your callback, you could call this fucntion to avoid |
1427 | detecting this change (while introducing a race condition). Can also be |
1826 | detecting this change (while introducing a race condition). Can also be |
1428 | useful simply to find out the new values. |
1827 | useful simply to find out the new values. |
1429 | .IP "ev_statdata attr [read\-only]" 4 |
1828 | .IP "ev_statdata attr [read\-only]" 4 |
… | |
… | |
1441 | The specified interval. |
1840 | The specified interval. |
1442 | .IP "const char *path [read\-only]" 4 |
1841 | .IP "const char *path [read\-only]" 4 |
1443 | .IX Item "const char *path [read-only]" |
1842 | .IX Item "const char *path [read-only]" |
1444 | The filesystem path that is being watched. |
1843 | The filesystem path that is being watched. |
1445 | .PP |
1844 | .PP |
|
|
1845 | \fIExamples\fR |
|
|
1846 | .IX Subsection "Examples" |
|
|
1847 | .PP |
1446 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1848 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1447 | .PP |
1849 | .PP |
1448 | .Vb 15 |
1850 | .Vb 10 |
1449 | \& static void |
1851 | \& static void |
1450 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1852 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1451 | \& { |
1853 | \& { |
1452 | \& /* /etc/passwd changed in some way */ |
1854 | \& /* /etc/passwd changed in some way */ |
1453 | \& if (w->attr.st_nlink) |
1855 | \& if (w\->attr.st_nlink) |
1454 | \& { |
1856 | \& { |
1455 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
1857 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1456 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
1858 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1457 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
1859 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1458 | \& } |
1860 | \& } |
1459 | \& else |
1861 | \& else |
1460 | \& /* you shalt not abuse printf for puts */ |
1862 | \& /* you shalt not abuse printf for puts */ |
1461 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1863 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1462 | \& "if this is windows, they already arrived\en"); |
1864 | \& "if this is windows, they already arrived\en"); |
1463 | \& } |
1865 | \& } |
1464 | .Ve |
1866 | \& |
1465 | .PP |
|
|
1466 | .Vb 2 |
|
|
1467 | \& ... |
1867 | \& ... |
1468 | \& ev_stat passwd; |
1868 | \& ev_stat passwd; |
|
|
1869 | \& |
|
|
1870 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1871 | \& ev_stat_start (loop, &passwd); |
1469 | .Ve |
1872 | .Ve |
|
|
1873 | .PP |
|
|
1874 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1875 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1876 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1877 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1470 | .PP |
1878 | .PP |
1471 | .Vb 2 |
1879 | .Vb 2 |
|
|
1880 | \& static ev_stat passwd; |
|
|
1881 | \& static ev_timer timer; |
|
|
1882 | \& |
|
|
1883 | \& static void |
|
|
1884 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1885 | \& { |
|
|
1886 | \& ev_timer_stop (EV_A_ w); |
|
|
1887 | \& |
|
|
1888 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1889 | \& } |
|
|
1890 | \& |
|
|
1891 | \& static void |
|
|
1892 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1893 | \& { |
|
|
1894 | \& /* reset the one\-second timer */ |
|
|
1895 | \& ev_timer_again (EV_A_ &timer); |
|
|
1896 | \& } |
|
|
1897 | \& |
|
|
1898 | \& ... |
1472 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1899 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1473 | \& ev_stat_start (loop, &passwd); |
1900 | \& ev_stat_start (loop, &passwd); |
|
|
1901 | \& ev_timer_init (&timer, timer_cb, 0., 1.01); |
1474 | .Ve |
1902 | .Ve |
1475 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1903 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1476 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1904 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1477 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1905 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1478 | Idle watchers trigger events when there are no other events are pending |
1906 | Idle watchers trigger events when no other events of the same or higher |
1479 | (prepare, check and other idle watchers do not count). That is, as long |
1907 | priority are pending (prepare, check and other idle watchers do not |
1480 | as your process is busy handling sockets or timeouts (or even signals, |
1908 | count). |
1481 | imagine) it will not be triggered. But when your process is idle all idle |
1909 | .PP |
1482 | watchers are being called again and again, once per event loop iteration \- |
1910 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1911 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1912 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1913 | are pending), the idle watchers are being called once per event loop |
1483 | until stopped, that is, or your process receives more events and becomes |
1914 | iteration \- until stopped, that is, or your process receives more events |
1484 | busy. |
1915 | and becomes busy again with higher priority stuff. |
1485 | .PP |
1916 | .PP |
1486 | The most noteworthy effect is that as long as any idle watchers are |
1917 | The most noteworthy effect is that as long as any idle watchers are |
1487 | active, the process will not block when waiting for new events. |
1918 | active, the process will not block when waiting for new events. |
1488 | .PP |
1919 | .PP |
1489 | Apart from keeping your process non-blocking (which is a useful |
1920 | Apart from keeping your process non-blocking (which is a useful |
1490 | effect on its own sometimes), idle watchers are a good place to do |
1921 | effect on its own sometimes), idle watchers are a good place to do |
1491 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1922 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1492 | event loop has handled all outstanding events. |
1923 | event loop has handled all outstanding events. |
|
|
1924 | .PP |
|
|
1925 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1926 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1493 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1927 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1494 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1928 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1495 | Initialises and configures the idle watcher \- it has no parameters of any |
1929 | Initialises and configures the idle watcher \- it has no parameters of any |
1496 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1930 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1497 | believe me. |
1931 | believe me. |
|
|
1932 | .PP |
|
|
1933 | \fIExamples\fR |
|
|
1934 | .IX Subsection "Examples" |
1498 | .PP |
1935 | .PP |
1499 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1936 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1500 | callback, free it. Also, use no error checking, as usual. |
1937 | callback, free it. Also, use no error checking, as usual. |
1501 | .PP |
1938 | .PP |
1502 | .Vb 7 |
1939 | .Vb 7 |
1503 | \& static void |
1940 | \& static void |
1504 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1941 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1505 | \& { |
1942 | \& { |
1506 | \& free (w); |
1943 | \& free (w); |
1507 | \& // now do something you wanted to do when the program has |
1944 | \& // now do something you wanted to do when the program has |
1508 | \& // no longer asnything immediate to do. |
1945 | \& // no longer anything immediate to do. |
1509 | \& } |
1946 | \& } |
1510 | .Ve |
1947 | \& |
1511 | .PP |
|
|
1512 | .Vb 3 |
|
|
1513 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1948 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1514 | \& ev_idle_init (idle_watcher, idle_cb); |
1949 | \& ev_idle_init (idle_watcher, idle_cb); |
1515 | \& ev_idle_start (loop, idle_cb); |
1950 | \& ev_idle_start (loop, idle_cb); |
1516 | .Ve |
1951 | .Ve |
1517 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1952 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
… | |
… | |
1552 | are ready to run (it's actually more complicated: it only runs coroutines |
1987 | are ready to run (it's actually more complicated: it only runs coroutines |
1553 | with priority higher than or equal to the event loop and one coroutine |
1988 | with priority higher than or equal to the event loop and one coroutine |
1554 | of lower priority, but only once, using idle watchers to keep the event |
1989 | of lower priority, but only once, using idle watchers to keep the event |
1555 | loop from blocking if lower-priority coroutines are active, thus mapping |
1990 | loop from blocking if lower-priority coroutines are active, thus mapping |
1556 | low-priority coroutines to idle/background tasks). |
1991 | low-priority coroutines to idle/background tasks). |
|
|
1992 | .PP |
|
|
1993 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
1994 | priority, to ensure that they are being run before any other watchers |
|
|
1995 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
|
|
1996 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
|
|
1997 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers |
|
|
1998 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
|
|
1999 | (non-libev) event loops those other event loops might be in an unusable |
|
|
2000 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
|
|
2001 | coexist peacefully with others). |
|
|
2002 | .PP |
|
|
2003 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2004 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1557 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2005 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1558 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2006 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1559 | .PD 0 |
2007 | .PD 0 |
1560 | .IP "ev_check_init (ev_check *, callback)" 4 |
2008 | .IP "ev_check_init (ev_check *, callback)" 4 |
1561 | .IX Item "ev_check_init (ev_check *, callback)" |
2009 | .IX Item "ev_check_init (ev_check *, callback)" |
1562 | .PD |
2010 | .PD |
1563 | Initialises and configures the prepare or check watcher \- they have no |
2011 | Initialises and configures the prepare or check watcher \- they have no |
1564 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2012 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1565 | macros, but using them is utterly, utterly and completely pointless. |
2013 | macros, but using them is utterly, utterly and completely pointless. |
1566 | .PP |
2014 | .PP |
1567 | Example: To include a library such as adns, you would add \s-1IO\s0 watchers |
2015 | \fIExamples\fR |
1568 | and a timeout watcher in a prepare handler, as required by libadns, and |
2016 | .IX Subsection "Examples" |
|
|
2017 | .PP |
|
|
2018 | There are a number of principal ways to embed other event loops or modules |
|
|
2019 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2020 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2021 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
|
|
2022 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
|
|
2023 | into the Glib event loop). |
|
|
2024 | .PP |
|
|
2025 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1569 | in a check watcher, destroy them and call into libadns. What follows is |
2026 | and in a check watcher, destroy them and call into libadns. What follows |
1570 | pseudo-code only of course: |
2027 | is pseudo-code only of course. This requires you to either use a low |
|
|
2028 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2029 | the callbacks for the IO/timeout watchers might not have been called yet. |
1571 | .PP |
2030 | .PP |
1572 | .Vb 2 |
2031 | .Vb 2 |
1573 | \& static ev_io iow [nfd]; |
2032 | \& static ev_io iow [nfd]; |
1574 | \& static ev_timer tw; |
2033 | \& static ev_timer tw; |
1575 | .Ve |
2034 | \& |
1576 | .PP |
|
|
1577 | .Vb 9 |
|
|
1578 | \& static void |
2035 | \& static void |
1579 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2036 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
1580 | \& { |
2037 | \& { |
1581 | \& // set the relevant poll flags |
|
|
1582 | \& // could also call adns_processreadable etc. here |
|
|
1583 | \& struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1584 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1585 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1586 | \& } |
2038 | \& } |
1587 | .Ve |
2039 | \& |
1588 | .PP |
|
|
1589 | .Vb 7 |
|
|
1590 | \& // create io watchers for each fd and a timer before blocking |
2040 | \& // create io watchers for each fd and a timer before blocking |
1591 | \& static void |
2041 | \& static void |
1592 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2042 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1593 | \& { |
2043 | \& { |
1594 | \& int timeout = 3600000;truct pollfd fds [nfd]; |
2044 | \& int timeout = 3600000; |
|
|
2045 | \& struct pollfd fds [nfd]; |
1595 | \& // actual code will need to loop here and realloc etc. |
2046 | \& // actual code will need to loop here and realloc etc. |
1596 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2047 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1597 | .Ve |
2048 | \& |
1598 | .PP |
|
|
1599 | .Vb 3 |
|
|
1600 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2049 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1601 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2050 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1602 | \& ev_timer_start (loop, &tw); |
2051 | \& ev_timer_start (loop, &tw); |
1603 | .Ve |
2052 | \& |
1604 | .PP |
|
|
1605 | .Vb 6 |
|
|
1606 | \& // create on ev_io per pollfd |
2053 | \& // create one ev_io per pollfd |
1607 | \& for (int i = 0; i < nfd; ++i) |
2054 | \& for (int i = 0; i < nfd; ++i) |
1608 | \& { |
2055 | \& { |
1609 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2056 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1610 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2057 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1611 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2058 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1612 | .Ve |
2059 | \& |
1613 | .PP |
|
|
1614 | .Vb 5 |
|
|
1615 | \& fds [i].revents = 0; |
2060 | \& fds [i].revents = 0; |
1616 | \& iow [i].data = fds + i; |
|
|
1617 | \& ev_io_start (loop, iow + i); |
2061 | \& ev_io_start (loop, iow + i); |
1618 | \& } |
2062 | \& } |
1619 | \& } |
2063 | \& } |
1620 | .Ve |
2064 | \& |
1621 | .PP |
|
|
1622 | .Vb 5 |
|
|
1623 | \& // stop all watchers after blocking |
2065 | \& // stop all watchers after blocking |
1624 | \& static void |
2066 | \& static void |
1625 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2067 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1626 | \& { |
2068 | \& { |
1627 | \& ev_timer_stop (loop, &tw); |
2069 | \& ev_timer_stop (loop, &tw); |
1628 | .Ve |
2070 | \& |
1629 | .PP |
|
|
1630 | .Vb 2 |
|
|
1631 | \& for (int i = 0; i < nfd; ++i) |
2071 | \& for (int i = 0; i < nfd; ++i) |
|
|
2072 | \& { |
|
|
2073 | \& // set the relevant poll flags |
|
|
2074 | \& // could also call adns_processreadable etc. here |
|
|
2075 | \& struct pollfd *fd = fds + i; |
|
|
2076 | \& int revents = ev_clear_pending (iow + i); |
|
|
2077 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2078 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2079 | \& |
|
|
2080 | \& // now stop the watcher |
1632 | \& ev_io_stop (loop, iow + i); |
2081 | \& ev_io_stop (loop, iow + i); |
1633 | .Ve |
2082 | \& } |
1634 | .PP |
2083 | \& |
1635 | .Vb 2 |
|
|
1636 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2084 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2085 | \& } |
|
|
2086 | .Ve |
|
|
2087 | .PP |
|
|
2088 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2089 | in the prepare watcher and would dispose of the check watcher. |
|
|
2090 | .PP |
|
|
2091 | Method 3: If the module to be embedded supports explicit event |
|
|
2092 | notification (adns does), you can also make use of the actual watcher |
|
|
2093 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
2094 | .PP |
|
|
2095 | .Vb 5 |
|
|
2096 | \& static void |
|
|
2097 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2098 | \& { |
|
|
2099 | \& adns_state ads = (adns_state)w\->data; |
|
|
2100 | \& update_now (EV_A); |
|
|
2101 | \& |
|
|
2102 | \& adns_processtimeouts (ads, &tv_now); |
|
|
2103 | \& } |
|
|
2104 | \& |
|
|
2105 | \& static void |
|
|
2106 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2107 | \& { |
|
|
2108 | \& adns_state ads = (adns_state)w\->data; |
|
|
2109 | \& update_now (EV_A); |
|
|
2110 | \& |
|
|
2111 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2112 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2113 | \& } |
|
|
2114 | \& |
|
|
2115 | \& // do not ever call adns_afterpoll |
|
|
2116 | .Ve |
|
|
2117 | .PP |
|
|
2118 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2119 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
2120 | their poll function. The drawback with this solution is that the main |
|
|
2121 | loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does |
|
|
2122 | this. |
|
|
2123 | .PP |
|
|
2124 | .Vb 4 |
|
|
2125 | \& static gint |
|
|
2126 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2127 | \& { |
|
|
2128 | \& int got_events = 0; |
|
|
2129 | \& |
|
|
2130 | \& for (n = 0; n < nfds; ++n) |
|
|
2131 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2132 | \& |
|
|
2133 | \& if (timeout >= 0) |
|
|
2134 | \& // create/start timer |
|
|
2135 | \& |
|
|
2136 | \& // poll |
|
|
2137 | \& ev_loop (EV_A_ 0); |
|
|
2138 | \& |
|
|
2139 | \& // stop timer again |
|
|
2140 | \& if (timeout >= 0) |
|
|
2141 | \& ev_timer_stop (EV_A_ &to); |
|
|
2142 | \& |
|
|
2143 | \& // stop io watchers again \- their callbacks should have set |
|
|
2144 | \& for (n = 0; n < nfds; ++n) |
|
|
2145 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2146 | \& |
|
|
2147 | \& return got_events; |
1637 | \& } |
2148 | \& } |
1638 | .Ve |
2149 | .Ve |
1639 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2150 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1640 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2151 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1641 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2152 | .IX Subsection "ev_embed - when one backend isn't enough..." |
… | |
… | |
1684 | portable one. |
2195 | portable one. |
1685 | .PP |
2196 | .PP |
1686 | So when you want to use this feature you will always have to be prepared |
2197 | So when you want to use this feature you will always have to be prepared |
1687 | that you cannot get an embeddable loop. The recommended way to get around |
2198 | that you cannot get an embeddable loop. The recommended way to get around |
1688 | this is to have a separate variables for your embeddable loop, try to |
2199 | this is to have a separate variables for your embeddable loop, try to |
1689 | create it, and if that fails, use the normal loop for everything: |
2200 | create it, and if that fails, use the normal loop for everything. |
1690 | .PP |
2201 | .PP |
1691 | .Vb 3 |
2202 | \fIWatcher-Specific Functions and Data Members\fR |
1692 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2203 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1693 | \& struct ev_loop *loop_lo = 0; |
|
|
1694 | \& struct ev_embed embed; |
|
|
1695 | .Ve |
|
|
1696 | .PP |
|
|
1697 | .Vb 5 |
|
|
1698 | \& // see if there is a chance of getting one that works |
|
|
1699 | \& // (remember that a flags value of 0 means autodetection) |
|
|
1700 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1701 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1702 | \& : 0; |
|
|
1703 | .Ve |
|
|
1704 | .PP |
|
|
1705 | .Vb 8 |
|
|
1706 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
1707 | \& if (loop_lo) |
|
|
1708 | \& { |
|
|
1709 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1710 | \& ev_embed_start (loop_hi, &embed); |
|
|
1711 | \& } |
|
|
1712 | \& else |
|
|
1713 | \& loop_lo = loop_hi; |
|
|
1714 | .Ve |
|
|
1715 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2204 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1716 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2205 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1717 | .PD 0 |
2206 | .PD 0 |
1718 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2207 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1719 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2208 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
… | |
… | |
1726 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2215 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1727 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2216 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1728 | Make a single, non-blocking sweep over the embedded loop. This works |
2217 | Make a single, non-blocking sweep over the embedded loop. This works |
1729 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2218 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1730 | apropriate way for embedded loops. |
2219 | apropriate way for embedded loops. |
1731 | .IP "struct ev_loop *loop [read\-only]" 4 |
2220 | .IP "struct ev_loop *other [read\-only]" 4 |
1732 | .IX Item "struct ev_loop *loop [read-only]" |
2221 | .IX Item "struct ev_loop *other [read-only]" |
1733 | The embedded event loop. |
2222 | The embedded event loop. |
|
|
2223 | .PP |
|
|
2224 | \fIExamples\fR |
|
|
2225 | .IX Subsection "Examples" |
|
|
2226 | .PP |
|
|
2227 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2228 | event loop. If that is not possible, use the default loop. The default |
|
|
2229 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2230 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2231 | used). |
|
|
2232 | .PP |
|
|
2233 | .Vb 3 |
|
|
2234 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2235 | \& struct ev_loop *loop_lo = 0; |
|
|
2236 | \& struct ev_embed embed; |
|
|
2237 | \& |
|
|
2238 | \& // see if there is a chance of getting one that works |
|
|
2239 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2240 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2241 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2242 | \& : 0; |
|
|
2243 | \& |
|
|
2244 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2245 | \& if (loop_lo) |
|
|
2246 | \& { |
|
|
2247 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2248 | \& ev_embed_start (loop_hi, &embed); |
|
|
2249 | \& } |
|
|
2250 | \& else |
|
|
2251 | \& loop_lo = loop_hi; |
|
|
2252 | .Ve |
|
|
2253 | .PP |
|
|
2254 | Example: Check if kqueue is available but not recommended and create |
|
|
2255 | a kqueue backend for use with sockets (which usually work with any |
|
|
2256 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2257 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2258 | .PP |
|
|
2259 | .Vb 3 |
|
|
2260 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2261 | \& struct ev_loop *loop_socket = 0; |
|
|
2262 | \& struct ev_embed embed; |
|
|
2263 | \& |
|
|
2264 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2265 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2266 | \& { |
|
|
2267 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2268 | \& ev_embed_start (loop, &embed); |
|
|
2269 | \& } |
|
|
2270 | \& |
|
|
2271 | \& if (!loop_socket) |
|
|
2272 | \& loop_socket = loop; |
|
|
2273 | \& |
|
|
2274 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2275 | .Ve |
1734 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2276 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
1735 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2277 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
1736 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2278 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
1737 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2279 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
1738 | whoever is a good citizen cared to tell libev about it by calling |
2280 | whoever is a good citizen cared to tell libev about it by calling |
1739 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2281 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
1740 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2282 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
1741 | and only in the child after the fork. If whoever good citizen calling |
2283 | and only in the child after the fork. If whoever good citizen calling |
1742 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2284 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
1743 | handlers will be invoked, too, of course. |
2285 | handlers will be invoked, too, of course. |
|
|
2286 | .PP |
|
|
2287 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2288 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1744 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2289 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
1745 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2290 | .IX Item "ev_fork_init (ev_signal *, callback)" |
1746 | Initialises and configures the fork watcher \- it has no parameters of any |
2291 | Initialises and configures the fork watcher \- it has no parameters of any |
1747 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2292 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
1748 | believe me. |
2293 | believe me. |
|
|
2294 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2295 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2296 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2297 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2298 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2299 | loops \- those are of course safe to use in different threads). |
|
|
2300 | .PP |
|
|
2301 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2302 | control, for example because it belongs to another thread. This is what |
|
|
2303 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2304 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2305 | safe. |
|
|
2306 | .PP |
|
|
2307 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2308 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2309 | (i.e. the number of callback invocations may be less than the number of |
|
|
2310 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2311 | .PP |
|
|
2312 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2313 | just the default loop. |
|
|
2314 | .PP |
|
|
2315 | \fIQueueing\fR |
|
|
2316 | .IX Subsection "Queueing" |
|
|
2317 | .PP |
|
|
2318 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2319 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2320 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2321 | need elaborate support such as pthreads. |
|
|
2322 | .PP |
|
|
2323 | That means that if you want to queue data, you have to provide your own |
|
|
2324 | queue. But at least I can tell you would implement locking around your |
|
|
2325 | queue: |
|
|
2326 | .IP "queueing from a signal handler context" 4 |
|
|
2327 | .IX Item "queueing from a signal handler context" |
|
|
2328 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2329 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2330 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2331 | .Sp |
|
|
2332 | .Vb 1 |
|
|
2333 | \& static ev_async mysig; |
|
|
2334 | \& |
|
|
2335 | \& static void |
|
|
2336 | \& sigusr1_handler (void) |
|
|
2337 | \& { |
|
|
2338 | \& sometype data; |
|
|
2339 | \& |
|
|
2340 | \& // no locking etc. |
|
|
2341 | \& queue_put (data); |
|
|
2342 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2343 | \& } |
|
|
2344 | \& |
|
|
2345 | \& static void |
|
|
2346 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2347 | \& { |
|
|
2348 | \& sometype data; |
|
|
2349 | \& sigset_t block, prev; |
|
|
2350 | \& |
|
|
2351 | \& sigemptyset (&block); |
|
|
2352 | \& sigaddset (&block, SIGUSR1); |
|
|
2353 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2354 | \& |
|
|
2355 | \& while (queue_get (&data)) |
|
|
2356 | \& process (data); |
|
|
2357 | \& |
|
|
2358 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2359 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2360 | \& } |
|
|
2361 | .Ve |
|
|
2362 | .Sp |
|
|
2363 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2364 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2365 | either...). |
|
|
2366 | .IP "queueing from a thread context" 4 |
|
|
2367 | .IX Item "queueing from a thread context" |
|
|
2368 | The strategy for threads is different, as you cannot (easily) block |
|
|
2369 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2370 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2371 | .Sp |
|
|
2372 | .Vb 2 |
|
|
2373 | \& static ev_async mysig; |
|
|
2374 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2375 | \& |
|
|
2376 | \& static void |
|
|
2377 | \& otherthread (void) |
|
|
2378 | \& { |
|
|
2379 | \& // only need to lock the actual queueing operation |
|
|
2380 | \& pthread_mutex_lock (&mymutex); |
|
|
2381 | \& queue_put (data); |
|
|
2382 | \& pthread_mutex_unlock (&mymutex); |
|
|
2383 | \& |
|
|
2384 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2385 | \& } |
|
|
2386 | \& |
|
|
2387 | \& static void |
|
|
2388 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2389 | \& { |
|
|
2390 | \& pthread_mutex_lock (&mymutex); |
|
|
2391 | \& |
|
|
2392 | \& while (queue_get (&data)) |
|
|
2393 | \& process (data); |
|
|
2394 | \& |
|
|
2395 | \& pthread_mutex_unlock (&mymutex); |
|
|
2396 | \& } |
|
|
2397 | .Ve |
|
|
2398 | .PP |
|
|
2399 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2400 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2401 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2402 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2403 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2404 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2405 | believe me. |
|
|
2406 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2407 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2408 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2409 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2410 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2411 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2412 | section below on what exactly this means). |
|
|
2413 | .Sp |
|
|
2414 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2415 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2416 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2417 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2418 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2419 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2420 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2421 | event loop. |
|
|
2422 | .Sp |
|
|
2423 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2424 | the loop iterates next and checks for the watcher to have become active, |
|
|
2425 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2426 | quickly check wether invoking the loop might be a good idea. |
|
|
2427 | .Sp |
|
|
2428 | Not that this does \fInot\fR check wether the watcher itself is pending, only |
|
|
2429 | wether it has been requested to make this watcher pending. |
1749 | .SH "OTHER FUNCTIONS" |
2430 | .SH "OTHER FUNCTIONS" |
1750 | .IX Header "OTHER FUNCTIONS" |
2431 | .IX Header "OTHER FUNCTIONS" |
1751 | There are some other functions of possible interest. Described. Here. Now. |
2432 | There are some other functions of possible interest. Described. Here. Now. |
1752 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2433 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1753 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2434 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
1777 | \& if (revents & EV_TIMEOUT) |
2458 | \& if (revents & EV_TIMEOUT) |
1778 | \& /* doh, nothing entered */; |
2459 | \& /* doh, nothing entered */; |
1779 | \& else if (revents & EV_READ) |
2460 | \& else if (revents & EV_READ) |
1780 | \& /* stdin might have data for us, joy! */; |
2461 | \& /* stdin might have data for us, joy! */; |
1781 | \& } |
2462 | \& } |
1782 | .Ve |
2463 | \& |
1783 | .Sp |
|
|
1784 | .Vb 1 |
|
|
1785 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2464 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1786 | .Ve |
2465 | .Ve |
1787 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2466 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
1788 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2467 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
1789 | Feeds the given event set into the event loop, as if the specified event |
2468 | Feeds the given event set into the event loop, as if the specified event |
… | |
… | |
1799 | loop!). |
2478 | loop!). |
1800 | .SH "LIBEVENT EMULATION" |
2479 | .SH "LIBEVENT EMULATION" |
1801 | .IX Header "LIBEVENT EMULATION" |
2480 | .IX Header "LIBEVENT EMULATION" |
1802 | Libev offers a compatibility emulation layer for libevent. It cannot |
2481 | Libev offers a compatibility emulation layer for libevent. It cannot |
1803 | emulate the internals of libevent, so here are some usage hints: |
2482 | emulate the internals of libevent, so here are some usage hints: |
|
|
2483 | .IP "\(bu" 4 |
1804 | .IP "* Use it by including <event.h>, as usual." 4 |
2484 | Use it by including <event.h>, as usual. |
1805 | .IX Item "Use it by including <event.h>, as usual." |
2485 | .IP "\(bu" 4 |
1806 | .PD 0 |
2486 | The following members are fully supported: ev_base, ev_callback, |
1807 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2487 | ev_arg, ev_fd, ev_res, ev_events. |
1808 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2488 | .IP "\(bu" 4 |
1809 | .IP "* Avoid using ev_flags and the EVLIST_*\-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private \s-1API\s0)." 4 |
2489 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1810 | .IX Item "Avoid using ev_flags and the EVLIST_*-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private API)." |
2490 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1811 | .IP "* Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." 4 |
2491 | it a private \s-1API\s0). |
1812 | .IX Item "Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." |
2492 | .IP "\(bu" 4 |
|
|
2493 | Priorities are not currently supported. Initialising priorities |
|
|
2494 | will fail and all watchers will have the same priority, even though there |
|
|
2495 | is an ev_pri field. |
|
|
2496 | .IP "\(bu" 4 |
|
|
2497 | In libevent, the last base created gets the signals, in libev, the |
|
|
2498 | first base created (== the default loop) gets the signals. |
|
|
2499 | .IP "\(bu" 4 |
1813 | .IP "* Other members are not supported." 4 |
2500 | Other members are not supported. |
1814 | .IX Item "Other members are not supported." |
2501 | .IP "\(bu" 4 |
1815 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2502 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1816 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2503 | to use the libev header file and library. |
1817 | .PD |
|
|
1818 | .SH "\*(C+ SUPPORT" |
2504 | .SH "\*(C+ SUPPORT" |
1819 | .IX Header " SUPPORT" |
2505 | .IX Header " SUPPORT" |
1820 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2506 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1821 | you to use some convinience methods to start/stop watchers and also change |
2507 | you to use some convinience methods to start/stop watchers and also change |
1822 | the callback model to a model using method callbacks on objects. |
2508 | the callback model to a model using method callbacks on objects. |
… | |
… | |
1825 | .PP |
2511 | .PP |
1826 | .Vb 1 |
2512 | .Vb 1 |
1827 | \& #include <ev++.h> |
2513 | \& #include <ev++.h> |
1828 | .Ve |
2514 | .Ve |
1829 | .PP |
2515 | .PP |
1830 | (it is not installed by default). This automatically includes \fIev.h\fR |
2516 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1831 | and puts all of its definitions (many of them macros) into the global |
2517 | of them macros) into the global namespace. All \*(C+ specific things are |
1832 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
2518 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2519 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1833 | .PP |
2520 | .PP |
1834 | It should support all the same embedding options as \fIev.h\fR, most notably |
2521 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1835 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
2522 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2523 | that the watcher is associated with (or no additional members at all if |
|
|
2524 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2525 | .PP |
|
|
2526 | Currently, functions, and static and non-static member functions can be |
|
|
2527 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2528 | need one additional pointer for context. If you need support for other |
|
|
2529 | types of functors please contact the author (preferably after implementing |
|
|
2530 | it). |
1836 | .PP |
2531 | .PP |
1837 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2532 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1838 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
2533 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
1839 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2534 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1840 | .IX Item "ev::READ, ev::WRITE etc." |
2535 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
1852 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
2547 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1853 | defines by many implementations. |
2548 | defines by many implementations. |
1854 | .Sp |
2549 | .Sp |
1855 | All of those classes have these methods: |
2550 | All of those classes have these methods: |
1856 | .RS 4 |
2551 | .RS 4 |
1857 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
2552 | .IP "ev::TYPE::TYPE ()" 4 |
1858 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
2553 | .IX Item "ev::TYPE::TYPE ()" |
1859 | .PD 0 |
2554 | .PD 0 |
1860 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
2555 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1861 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
2556 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1862 | .IP "ev::TYPE::~TYPE" 4 |
2557 | .IP "ev::TYPE::~TYPE" 4 |
1863 | .IX Item "ev::TYPE::~TYPE" |
2558 | .IX Item "ev::TYPE::~TYPE" |
1864 | .PD |
2559 | .PD |
1865 | The constructor takes a pointer to an object and a method pointer to |
2560 | The constructor (optionally) takes an event loop to associate the watcher |
1866 | the event handler callback to call in this class. The constructor calls |
2561 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1867 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
2562 | .Sp |
1868 | before starting it. If you do not specify a loop then the constructor |
2563 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1869 | automatically associates the default loop with this watcher. |
2564 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2565 | .Sp |
|
|
2566 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2567 | method to set a callback before you can start the watcher. |
|
|
2568 | .Sp |
|
|
2569 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2570 | not allow explicit template arguments for constructors). |
1870 | .Sp |
2571 | .Sp |
1871 | The destructor automatically stops the watcher if it is active. |
2572 | The destructor automatically stops the watcher if it is active. |
|
|
2573 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2574 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2575 | This method sets the callback method to call. The method has to have a |
|
|
2576 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2577 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2578 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2579 | .Sp |
|
|
2580 | This method synthesizes efficient thunking code to call your method from |
|
|
2581 | the C callback that libev requires. If your compiler can inline your |
|
|
2582 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2583 | your compiler is good :), then the method will be fully inlined into the |
|
|
2584 | thunking function, making it as fast as a direct C callback. |
|
|
2585 | .Sp |
|
|
2586 | Example: simple class declaration and watcher initialisation |
|
|
2587 | .Sp |
|
|
2588 | .Vb 4 |
|
|
2589 | \& struct myclass |
|
|
2590 | \& { |
|
|
2591 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2592 | \& } |
|
|
2593 | \& |
|
|
2594 | \& myclass obj; |
|
|
2595 | \& ev::io iow; |
|
|
2596 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2597 | .Ve |
|
|
2598 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2599 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2600 | Also sets a callback, but uses a static method or plain function as |
|
|
2601 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2602 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2603 | .Sp |
|
|
2604 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
2605 | .Sp |
|
|
2606 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
2607 | .Sp |
|
|
2608 | Example: |
|
|
2609 | .Sp |
|
|
2610 | .Vb 2 |
|
|
2611 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
2612 | \& iow.set <io_cb> (); |
|
|
2613 | .Ve |
1872 | .IP "w\->set (struct ev_loop *)" 4 |
2614 | .IP "w\->set (struct ev_loop *)" 4 |
1873 | .IX Item "w->set (struct ev_loop *)" |
2615 | .IX Item "w->set (struct ev_loop *)" |
1874 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
2616 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1875 | do this when the watcher is inactive (and not pending either). |
2617 | do this when the watcher is inactive (and not pending either). |
1876 | .IP "w\->set ([args])" 4 |
2618 | .IP "w\->set ([args])" 4 |
1877 | .IX Item "w->set ([args])" |
2619 | .IX Item "w->set ([args])" |
1878 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
2620 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
1879 | called at least once. Unlike the C counterpart, an active watcher gets |
2621 | called at least once. Unlike the C counterpart, an active watcher gets |
1880 | automatically stopped and restarted. |
2622 | automatically stopped and restarted when reconfiguring it with this |
|
|
2623 | method. |
1881 | .IP "w\->start ()" 4 |
2624 | .IP "w\->start ()" 4 |
1882 | .IX Item "w->start ()" |
2625 | .IX Item "w->start ()" |
1883 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
2626 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1884 | constructor already takes the loop. |
2627 | constructor already stores the event loop. |
1885 | .IP "w\->stop ()" 4 |
2628 | .IP "w\->stop ()" 4 |
1886 | .IX Item "w->stop ()" |
2629 | .IX Item "w->stop ()" |
1887 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
2630 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1888 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
2631 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
1889 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
2632 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1890 | .IX Item "w->again () ev::timer, ev::periodic only" |
2633 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1891 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
2634 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1892 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
2635 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1893 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
2636 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1894 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
2637 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1895 | .IX Item "w->sweep () ev::embed only" |
2638 | .IX Item "w->sweep () (ev::embed only)" |
1896 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
2639 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
1897 | .ie n .IP "w\->update () ""ev::stat"" only" 4 |
2640 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
1898 | .el .IP "w\->update () \f(CWev::stat\fR only" 4 |
2641 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
1899 | .IX Item "w->update () ev::stat only" |
2642 | .IX Item "w->update () (ev::stat only)" |
1900 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
2643 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1901 | .RE |
2644 | .RE |
1902 | .RS 4 |
2645 | .RS 4 |
1903 | .RE |
2646 | .RE |
1904 | .PP |
2647 | .PP |
… | |
… | |
1906 | the constructor. |
2649 | the constructor. |
1907 | .PP |
2650 | .PP |
1908 | .Vb 4 |
2651 | .Vb 4 |
1909 | \& class myclass |
2652 | \& class myclass |
1910 | \& { |
2653 | \& { |
1911 | \& ev_io io; void io_cb (ev::io &w, int revents); |
2654 | \& ev::io io; void io_cb (ev::io &w, int revents); |
1912 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
2655 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
1913 | .Ve |
2656 | \& |
1914 | .PP |
|
|
1915 | .Vb 2 |
|
|
1916 | \& myclass (); |
2657 | \& myclass (int fd) |
1917 | \& } |
|
|
1918 | .Ve |
|
|
1919 | .PP |
|
|
1920 | .Vb 6 |
|
|
1921 | \& myclass::myclass (int fd) |
|
|
1922 | \& : io (this, &myclass::io_cb), |
|
|
1923 | \& idle (this, &myclass::idle_cb) |
|
|
1924 | \& { |
2658 | \& { |
|
|
2659 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
2660 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2661 | \& |
1925 | \& io.start (fd, ev::READ); |
2662 | \& io.start (fd, ev::READ); |
|
|
2663 | \& } |
1926 | \& } |
2664 | \& }; |
1927 | .Ve |
2665 | .Ve |
|
|
2666 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2667 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2668 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2669 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2670 | any interesting language binding in addition to the ones listed here, drop |
|
|
2671 | me a note. |
|
|
2672 | .IP "Perl" 4 |
|
|
2673 | .IX Item "Perl" |
|
|
2674 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2675 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2676 | there are additional modules that implement libev-compatible interfaces |
|
|
2677 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2678 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2679 | .Sp |
|
|
2680 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2681 | <http://software.schmorp.de/pkg/EV>. |
|
|
2682 | .IP "Ruby" 4 |
|
|
2683 | .IX Item "Ruby" |
|
|
2684 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2685 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2686 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2687 | <http://rev.rubyforge.org/>. |
|
|
2688 | .IP "D" 4 |
|
|
2689 | .IX Item "D" |
|
|
2690 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2691 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
1928 | .SH "MACRO MAGIC" |
2692 | .SH "MACRO MAGIC" |
1929 | .IX Header "MACRO MAGIC" |
2693 | .IX Header "MACRO MAGIC" |
1930 | Libev can be compiled with a variety of options, the most fundemantal is |
2694 | Libev can be compiled with a variety of options, the most fundamantal |
1931 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and |
2695 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
1932 | callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
2696 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1933 | .PP |
2697 | .PP |
1934 | To make it easier to write programs that cope with either variant, the |
2698 | To make it easier to write programs that cope with either variant, the |
1935 | following macros are defined: |
2699 | following macros are defined: |
1936 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
2700 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
1937 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
2701 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
… | |
… | |
1956 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2720 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
1957 | .Sp |
2721 | .Sp |
1958 | .Vb 2 |
2722 | .Vb 2 |
1959 | \& // this is how ev_unref is being declared |
2723 | \& // this is how ev_unref is being declared |
1960 | \& static void ev_unref (EV_P); |
2724 | \& static void ev_unref (EV_P); |
1961 | .Ve |
2725 | \& |
1962 | .Sp |
|
|
1963 | .Vb 2 |
|
|
1964 | \& // this is how you can declare your typical callback |
2726 | \& // this is how you can declare your typical callback |
1965 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2727 | \& static void cb (EV_P_ ev_timer *w, int revents) |
1966 | .Ve |
2728 | .Ve |
1967 | .Sp |
2729 | .Sp |
1968 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
2730 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
… | |
… | |
1970 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
2732 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
1971 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
2733 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
1972 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
2734 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
1973 | Similar to the other two macros, this gives you the value of the default |
2735 | Similar to the other two macros, this gives you the value of the default |
1974 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
2736 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2737 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
2738 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
2739 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
2740 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
2741 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
2742 | is undefined when the default loop has not been initialised by a previous |
|
|
2743 | execution of \f(CW\*(C`EV_DEFAULT\*(C'\fR, \f(CW\*(C`EV_DEFAULT_\*(C'\fR or \f(CW\*(C`ev_default_init (...)\*(C'\fR. |
|
|
2744 | .Sp |
|
|
2745 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
2746 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
1975 | .PP |
2747 | .PP |
1976 | Example: Declare and initialise a check watcher, working regardless of |
2748 | Example: Declare and initialise a check watcher, utilising the above |
1977 | wether multiple loops are supported or not. |
2749 | macros so it will work regardless of whether multiple loops are supported |
|
|
2750 | or not. |
1978 | .PP |
2751 | .PP |
1979 | .Vb 5 |
2752 | .Vb 5 |
1980 | \& static void |
2753 | \& static void |
1981 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2754 | \& check_cb (EV_P_ ev_timer *w, int revents) |
1982 | \& { |
2755 | \& { |
1983 | \& ev_check_stop (EV_A_ w); |
2756 | \& ev_check_stop (EV_A_ w); |
1984 | \& } |
2757 | \& } |
1985 | .Ve |
2758 | \& |
1986 | .PP |
|
|
1987 | .Vb 4 |
|
|
1988 | \& ev_check check; |
2759 | \& ev_check check; |
1989 | \& ev_check_init (&check, check_cb); |
2760 | \& ev_check_init (&check, check_cb); |
1990 | \& ev_check_start (EV_DEFAULT_ &check); |
2761 | \& ev_check_start (EV_DEFAULT_ &check); |
1991 | \& ev_loop (EV_DEFAULT_ 0); |
2762 | \& ev_loop (EV_DEFAULT_ 0); |
1992 | .Ve |
2763 | .Ve |
1993 | .SH "EMBEDDING" |
2764 | .SH "EMBEDDING" |
1994 | .IX Header "EMBEDDING" |
2765 | .IX Header "EMBEDDING" |
1995 | Libev can (and often is) directly embedded into host |
2766 | Libev can (and often is) directly embedded into host |
1996 | applications. Examples of applications that embed it include the Deliantra |
2767 | applications. Examples of applications that embed it include the Deliantra |
1997 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2768 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
1998 | and rxvt\-unicode. |
2769 | and rxvt-unicode. |
1999 | .PP |
2770 | .PP |
2000 | The goal is to enable you to just copy the neecssary files into your |
2771 | The goal is to enable you to just copy the necessary files into your |
2001 | source directory without having to change even a single line in them, so |
2772 | source directory without having to change even a single line in them, so |
2002 | you can easily upgrade by simply copying (or having a checked-out copy of |
2773 | you can easily upgrade by simply copying (or having a checked-out copy of |
2003 | libev somewhere in your source tree). |
2774 | libev somewhere in your source tree). |
2004 | .Sh "\s-1FILESETS\s0" |
2775 | .Sh "\s-1FILESETS\s0" |
2005 | .IX Subsection "FILESETS" |
2776 | .IX Subsection "FILESETS" |
… | |
… | |
2038 | .Vb 4 |
2809 | .Vb 4 |
2039 | \& ev.h |
2810 | \& ev.h |
2040 | \& ev.c |
2811 | \& ev.c |
2041 | \& ev_vars.h |
2812 | \& ev_vars.h |
2042 | \& ev_wrap.h |
2813 | \& ev_wrap.h |
2043 | .Ve |
2814 | \& |
2044 | .PP |
|
|
2045 | .Vb 1 |
|
|
2046 | \& ev_win32.c required on win32 platforms only |
2815 | \& ev_win32.c required on win32 platforms only |
2047 | .Ve |
2816 | \& |
2048 | .PP |
|
|
2049 | .Vb 5 |
|
|
2050 | \& ev_select.c only when select backend is enabled (which is by default) |
2817 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2051 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2818 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2052 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2819 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2053 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2820 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2054 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2821 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2055 | .Ve |
2822 | .Ve |
… | |
… | |
2094 | .Vb 1 |
2861 | .Vb 1 |
2095 | \& libev.m4 |
2862 | \& libev.m4 |
2096 | .Ve |
2863 | .Ve |
2097 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2864 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2098 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2865 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2099 | Libev can be configured via a variety of preprocessor symbols you have to define |
2866 | Libev can be configured via a variety of preprocessor symbols you have to |
2100 | before including any of its files. The default is not to build for multiplicity |
2867 | define before including any of its files. The default in the absense of |
2101 | and only include the select backend. |
2868 | autoconf is noted for every option. |
2102 | .IP "\s-1EV_STANDALONE\s0" 4 |
2869 | .IP "\s-1EV_STANDALONE\s0" 4 |
2103 | .IX Item "EV_STANDALONE" |
2870 | .IX Item "EV_STANDALONE" |
2104 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2871 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2105 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2872 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2106 | implementations for some libevent functions (such as logging, which is not |
2873 | implementations for some libevent functions (such as logging, which is not |
… | |
… | |
2110 | .IX Item "EV_USE_MONOTONIC" |
2877 | .IX Item "EV_USE_MONOTONIC" |
2111 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2878 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2112 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2879 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2113 | of the monotonic clock option will be attempted. If you enable this, you |
2880 | of the monotonic clock option will be attempted. If you enable this, you |
2114 | usually have to link against librt or something similar. Enabling it when |
2881 | usually have to link against librt or something similar. Enabling it when |
2115 | the functionality isn't available is safe, though, althoguh you have |
2882 | the functionality isn't available is safe, though, although you have |
2116 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2883 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2117 | function is hiding in (often \fI\-lrt\fR). |
2884 | function is hiding in (often \fI\-lrt\fR). |
2118 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2885 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2119 | .IX Item "EV_USE_REALTIME" |
2886 | .IX Item "EV_USE_REALTIME" |
2120 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2887 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2121 | realtime clock option at compiletime (and assume its availability at |
2888 | realtime clock option at compiletime (and assume its availability at |
2122 | runtime if successful). Otherwise no use of the realtime clock option will |
2889 | runtime if successful). Otherwise no use of the realtime clock option will |
2123 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2890 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2124 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
2891 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
2125 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2892 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2893 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
2894 | .IX Item "EV_USE_NANOSLEEP" |
|
|
2895 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
2896 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
2897 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
2898 | .IX Item "EV_USE_EVENTFD" |
|
|
2899 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
2900 | available and will probe for kernel support at runtime. This will improve |
|
|
2901 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
2902 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2903 | 2.7 or newer, otherwise disabled. |
2126 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2904 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2127 | .IX Item "EV_USE_SELECT" |
2905 | .IX Item "EV_USE_SELECT" |
2128 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2906 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2129 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2907 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2130 | other method takes over, select will be it. Otherwise the select backend |
2908 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2145 | wants osf handles on win32 (this is the case when the select to |
2923 | wants osf handles on win32 (this is the case when the select to |
2146 | be used is the winsock select). This means that it will call |
2924 | be used is the winsock select). This means that it will call |
2147 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2925 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2148 | it is assumed that all these functions actually work on fds, even |
2926 | it is assumed that all these functions actually work on fds, even |
2149 | on win32. Should not be defined on non\-win32 platforms. |
2927 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2928 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2929 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2930 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2931 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2932 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2933 | correct. In some cases, programs use their own file descriptor management, |
|
|
2934 | in which case they can provide this function to map fds to socket handles. |
2150 | .IP "\s-1EV_USE_POLL\s0" 4 |
2935 | .IP "\s-1EV_USE_POLL\s0" 4 |
2151 | .IX Item "EV_USE_POLL" |
2936 | .IX Item "EV_USE_POLL" |
2152 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2937 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2153 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2938 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2154 | takes precedence over select. |
2939 | takes precedence over select. |
2155 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2940 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2156 | .IX Item "EV_USE_EPOLL" |
2941 | .IX Item "EV_USE_EPOLL" |
2157 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2942 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2158 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2943 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2159 | otherwise another method will be used as fallback. This is the |
2944 | otherwise another method will be used as fallback. This is the preferred |
2160 | preferred backend for GNU/Linux systems. |
2945 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2946 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2161 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2947 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2162 | .IX Item "EV_USE_KQUEUE" |
2948 | .IX Item "EV_USE_KQUEUE" |
2163 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2949 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2164 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2950 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2165 | otherwise another method will be used as fallback. This is the preferred |
2951 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
2180 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2966 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2181 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2967 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2182 | .IX Item "EV_USE_INOTIFY" |
2968 | .IX Item "EV_USE_INOTIFY" |
2183 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2969 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2184 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2970 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2185 | be detected at runtime. |
2971 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2972 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2973 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
2974 | .IX Item "EV_ATOMIC_T" |
|
|
2975 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
2976 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2977 | type is easily found in the C language, so you can provide your own type |
|
|
2978 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
2979 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
2980 | .Sp |
|
|
2981 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
2982 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2186 | .IP "\s-1EV_H\s0" 4 |
2983 | .IP "\s-1EV_H\s0" 4 |
2187 | .IX Item "EV_H" |
2984 | .IX Item "EV_H" |
2188 | The name of the \fIev.h\fR header file used to include it. The default if |
2985 | The name of the \fIev.h\fR header file used to include it. The default if |
2189 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
2986 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2190 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2987 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2191 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2988 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2192 | .IX Item "EV_CONFIG_H" |
2989 | .IX Item "EV_CONFIG_H" |
2193 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2990 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2194 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2991 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2195 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2992 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2196 | .IP "\s-1EV_EVENT_H\s0" 4 |
2993 | .IP "\s-1EV_EVENT_H\s0" 4 |
2197 | .IX Item "EV_EVENT_H" |
2994 | .IX Item "EV_EVENT_H" |
2198 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2995 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2199 | of how the \fIevent.h\fR header can be found. |
2996 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2200 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2997 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2201 | .IX Item "EV_PROTOTYPES" |
2998 | .IX Item "EV_PROTOTYPES" |
2202 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2999 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2203 | prototypes, but still define all the structs and other symbols. This is |
3000 | prototypes, but still define all the structs and other symbols. This is |
2204 | occasionally useful if you want to provide your own wrapper functions |
3001 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2208 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3005 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
2209 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3006 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
2210 | additional independent event loops. Otherwise there will be no support |
3007 | additional independent event loops. Otherwise there will be no support |
2211 | for multiple event loops and there is no first event loop pointer |
3008 | for multiple event loops and there is no first event loop pointer |
2212 | argument. Instead, all functions act on the single default loop. |
3009 | argument. Instead, all functions act on the single default loop. |
|
|
3010 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3011 | .IX Item "EV_MINPRI" |
|
|
3012 | .PD 0 |
|
|
3013 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3014 | .IX Item "EV_MAXPRI" |
|
|
3015 | .PD |
|
|
3016 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3017 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3018 | provide for more priorities by overriding those symbols (usually defined |
|
|
3019 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3020 | .Sp |
|
|
3021 | When doing priority-based operations, libev usually has to linearly search |
|
|
3022 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3023 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3024 | fine. |
|
|
3025 | .Sp |
|
|
3026 | If your embedding app does not need any priorities, defining these both to |
|
|
3027 | \&\f(CW0\fR will save some memory and cpu. |
2213 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
3028 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
2214 | .IX Item "EV_PERIODIC_ENABLE" |
3029 | .IX Item "EV_PERIODIC_ENABLE" |
2215 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
3030 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
|
|
3031 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3032 | code. |
|
|
3033 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3034 | .IX Item "EV_IDLE_ENABLE" |
|
|
3035 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
2216 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
3036 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
2217 | code. |
3037 | code. |
2218 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
3038 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
2219 | .IX Item "EV_EMBED_ENABLE" |
3039 | .IX Item "EV_EMBED_ENABLE" |
2220 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
3040 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
… | |
… | |
2225 | defined to be \f(CW0\fR, then they are not. |
3045 | defined to be \f(CW0\fR, then they are not. |
2226 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3046 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2227 | .IX Item "EV_FORK_ENABLE" |
3047 | .IX Item "EV_FORK_ENABLE" |
2228 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3048 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2229 | defined to be \f(CW0\fR, then they are not. |
3049 | defined to be \f(CW0\fR, then they are not. |
|
|
3050 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3051 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3052 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3053 | defined to be \f(CW0\fR, then they are not. |
2230 | .IP "\s-1EV_MINIMAL\s0" 4 |
3054 | .IP "\s-1EV_MINIMAL\s0" 4 |
2231 | .IX Item "EV_MINIMAL" |
3055 | .IX Item "EV_MINIMAL" |
2232 | If you need to shave off some kilobytes of code at the expense of some |
3056 | If you need to shave off some kilobytes of code at the expense of some |
2233 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3057 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
2234 | some inlining decisions, saves roughly 30% codesize of amd64. |
3058 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2238 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3062 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2239 | than enough. If you need to manage thousands of children you might want to |
3063 | than enough. If you need to manage thousands of children you might want to |
2240 | increase this value (\fImust\fR be a power of two). |
3064 | increase this value (\fImust\fR be a power of two). |
2241 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3065 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
2242 | .IX Item "EV_INOTIFY_HASHSIZE" |
3066 | .IX Item "EV_INOTIFY_HASHSIZE" |
2243 | \&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by |
3067 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
2244 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
3068 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
2245 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
3069 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
2246 | watchers you might want to increase this value (\fImust\fR be a power of |
3070 | watchers you might want to increase this value (\fImust\fR be a power of |
2247 | two). |
3071 | two). |
2248 | .IP "\s-1EV_COMMON\s0" 4 |
3072 | .IP "\s-1EV_COMMON\s0" 4 |
… | |
… | |
2267 | .IP "ev_set_cb (ev, cb)" 4 |
3091 | .IP "ev_set_cb (ev, cb)" 4 |
2268 | .IX Item "ev_set_cb (ev, cb)" |
3092 | .IX Item "ev_set_cb (ev, cb)" |
2269 | .PD |
3093 | .PD |
2270 | Can be used to change the callback member declaration in each watcher, |
3094 | Can be used to change the callback member declaration in each watcher, |
2271 | and the way callbacks are invoked and set. Must expand to a struct member |
3095 | and the way callbacks are invoked and set. Must expand to a struct member |
2272 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3096 | definition and a statement, respectively. See the \fIev.h\fR header file for |
2273 | their default definitions. One possible use for overriding these is to |
3097 | their default definitions. One possible use for overriding these is to |
2274 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3098 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
2275 | method calls instead of plain function calls in \*(C+. |
3099 | method calls instead of plain function calls in \*(C+. |
|
|
3100 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3101 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3102 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
|
|
3103 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3104 | all public symbols, one per line: |
|
|
3105 | .PP |
|
|
3106 | .Vb 2 |
|
|
3107 | \& Symbols.ev for libev proper |
|
|
3108 | \& Symbols.event for the libevent emulation |
|
|
3109 | .Ve |
|
|
3110 | .PP |
|
|
3111 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3112 | multiple versions of libev linked together (which is obviously bad in |
|
|
3113 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3114 | .PP |
|
|
3115 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3116 | include before including \fIev.h\fR: |
|
|
3117 | .PP |
|
|
3118 | .Vb 1 |
|
|
3119 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3120 | .Ve |
|
|
3121 | .PP |
|
|
3122 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3123 | .PP |
|
|
3124 | .Vb 4 |
|
|
3125 | \& #define ev_backend myprefix_ev_backend |
|
|
3126 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3127 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3128 | \& ... |
|
|
3129 | .Ve |
2276 | .Sh "\s-1EXAMPLES\s0" |
3130 | .Sh "\s-1EXAMPLES\s0" |
2277 | .IX Subsection "EXAMPLES" |
3131 | .IX Subsection "EXAMPLES" |
2278 | For a real-world example of a program the includes libev |
3132 | For a real-world example of a program the includes libev |
2279 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3133 | verbatim, you can have a look at the \s-1EV\s0 perl module |
2280 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3134 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2281 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3135 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2282 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3136 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2283 | will be compiled. It is pretty complex because it provides its own header |
3137 | will be compiled. It is pretty complex because it provides its own header |
2284 | file. |
3138 | file. |
2285 | .Sp |
3139 | .PP |
2286 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3140 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2287 | that everybody includes and which overrides some autoconf choices: |
3141 | that everybody includes and which overrides some configure choices: |
2288 | .Sp |
3142 | .PP |
2289 | .Vb 4 |
3143 | .Vb 9 |
|
|
3144 | \& #define EV_MINIMAL 1 |
2290 | \& #define EV_USE_POLL 0 |
3145 | \& #define EV_USE_POLL 0 |
2291 | \& #define EV_MULTIPLICITY 0 |
3146 | \& #define EV_MULTIPLICITY 0 |
2292 | \& #define EV_PERIODICS 0 |
3147 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3148 | \& #define EV_STAT_ENABLE 0 |
|
|
3149 | \& #define EV_FORK_ENABLE 0 |
2293 | \& #define EV_CONFIG_H <config.h> |
3150 | \& #define EV_CONFIG_H <config.h> |
2294 | .Ve |
3151 | \& #define EV_MINPRI 0 |
2295 | .Sp |
3152 | \& #define EV_MAXPRI 0 |
2296 | .Vb 1 |
3153 | \& |
2297 | \& #include "ev++.h" |
3154 | \& #include "ev++.h" |
2298 | .Ve |
3155 | .Ve |
2299 | .Sp |
3156 | .PP |
2300 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3157 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2301 | .Sp |
3158 | .PP |
2302 | .Vb 2 |
3159 | .Vb 2 |
2303 | \& #include "ev_cpp.h" |
3160 | \& #include "ev_cpp.h" |
2304 | \& #include "ev.c" |
3161 | \& #include "ev.c" |
2305 | .Ve |
3162 | .Ve |
|
|
3163 | .SH "THREADS AND COROUTINES" |
|
|
3164 | .IX Header "THREADS AND COROUTINES" |
|
|
3165 | .Sh "\s-1THREADS\s0" |
|
|
3166 | .IX Subsection "THREADS" |
|
|
3167 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3168 | means that you can use as many loops as you want in parallel, as long as |
|
|
3169 | only one thread ever calls into one libev function with the same loop |
|
|
3170 | parameter. |
|
|
3171 | .PP |
|
|
3172 | Or put differently: calls with different loop parameters can be done in |
|
|
3173 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3174 | done serially (but can be done from different threads, as long as only one |
|
|
3175 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3176 | per loop). |
|
|
3177 | .PP |
|
|
3178 | If you want to know which design is best for your problem, then I cannot |
|
|
3179 | help you but by giving some generic advice: |
|
|
3180 | .IP "\(bu" 4 |
|
|
3181 | most applications have a main thread: use the default libev loop |
|
|
3182 | in that thread, or create a seperate thread running only the default loop. |
|
|
3183 | .Sp |
|
|
3184 | This helps integrating other libraries or software modules that use libev |
|
|
3185 | themselves and don't care/know about threading. |
|
|
3186 | .IP "\(bu" 4 |
|
|
3187 | one loop per thread is usually a good model. |
|
|
3188 | .Sp |
|
|
3189 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3190 | exists, but it is always a good start. |
|
|
3191 | .IP "\(bu" 4 |
|
|
3192 | other models exist, such as the leader/follower pattern, where one |
|
|
3193 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3194 | .Sp |
|
|
3195 | Chosing a model is hard \- look around, learn, know that usually you cna do |
|
|
3196 | better than you currently do :\-) |
|
|
3197 | .IP "\(bu" 4 |
|
|
3198 | often you need to talk to some other thread which blocks in the |
|
|
3199 | event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other |
|
|
3200 | threads safely (or from signal contexts...). |
|
|
3201 | .Sh "\s-1COROUTINES\s0" |
|
|
3202 | .IX Subsection "COROUTINES" |
|
|
3203 | Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3204 | libev fully supports nesting calls to it's functions from different |
|
|
3205 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3206 | different coroutines and switch freely between both coroutines running the |
|
|
3207 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3208 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3209 | .PP |
|
|
3210 | Care has been invested into making sure that libev does not keep local |
|
|
3211 | state inside \f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow coroutine |
|
|
3212 | switches. |
2306 | .SH "COMPLEXITIES" |
3213 | .SH "COMPLEXITIES" |
2307 | .IX Header "COMPLEXITIES" |
3214 | .IX Header "COMPLEXITIES" |
2308 | In this section the complexities of (many of) the algorithms used inside |
3215 | In this section the complexities of (many of) the algorithms used inside |
2309 | libev will be explained. For complexity discussions about backends see the |
3216 | libev will be explained. For complexity discussions about backends see the |
2310 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
3217 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2311 | .RS 4 |
3218 | .PP |
|
|
3219 | All of the following are about amortised time: If an array needs to be |
|
|
3220 | extended, libev needs to realloc and move the whole array, but this |
|
|
3221 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
3222 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3223 | it is much faster and asymptotically approaches constant time. |
2312 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
3224 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2313 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
3225 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
3226 | This means that, when you have a watcher that triggers in one hour and |
|
|
3227 | there are 100 watchers that would trigger before that then inserting will |
|
|
3228 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
3229 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
3230 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
3231 | That means that changing a timer costs less than removing/adding them |
|
|
3232 | as only the relative motion in the event queue has to be paid for. |
|
|
3233 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
3234 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
3235 | These just add the watcher into an array or at the head of a list. |
|
|
3236 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
3237 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
2314 | .PD 0 |
3238 | .PD 0 |
2315 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2316 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
|
|
2317 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
|
|
2318 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
|
|
2319 | .IP "Stopping check/prepare/idle watchers: O(1)" 4 |
|
|
2320 | .IX Item "Stopping check/prepare/idle watchers: O(1)" |
|
|
2321 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
3239 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2322 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
3240 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3241 | .PD |
|
|
3242 | These watchers are stored in lists then need to be walked to find the |
|
|
3243 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3244 | have many watchers waiting for the same fd or signal). |
2323 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
3245 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2324 | .IX Item "Finding the next timer per loop iteration: O(1)" |
3246 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
3247 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3248 | beginning of the storage array. |
2325 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
3249 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2326 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
3250 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2327 | .IP "Activating one watcher: O(1)" 4 |
3251 | A change means an I/O watcher gets started or stopped, which requires |
2328 | .IX Item "Activating one watcher: O(1)" |
3252 | libev to recalculate its status (and possibly tell the kernel, depending |
2329 | .RE |
3253 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2330 | .RS 4 |
3254 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3255 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
3256 | .PD 0 |
|
|
3257 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
3258 | .IX Item "Priority handling: O(number_of_priorities)" |
2331 | .PD |
3259 | .PD |
|
|
3260 | Priorities are implemented by allocating some space for each |
|
|
3261 | priority. When doing priority-based operations, libev usually has to |
|
|
3262 | linearly search all the priorities, but starting/stopping and activating |
|
|
3263 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3264 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3265 | .IX Item "Sending an ev_async: O(1)" |
|
|
3266 | .PD 0 |
|
|
3267 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3268 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3269 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3270 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3271 | .PD |
|
|
3272 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3273 | calls in the current loop iteration. Checking for async and signal events |
|
|
3274 | involves iterating over all running async watchers or all signal numbers. |
|
|
3275 | .SH "Win32 platform limitations and workarounds" |
|
|
3276 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3277 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3278 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3279 | model. Libev still offers limited functionality on this platform in |
|
|
3280 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3281 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3282 | e.g. cygwin. |
|
|
3283 | .PP |
|
|
3284 | There is no supported compilation method available on windows except |
|
|
3285 | embedding it into other applications. |
|
|
3286 | .PP |
|
|
3287 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3288 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3289 | recommended (and not reasonable). If your program needs to use more than |
|
|
3290 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3291 | implementation for windows, as libev offers the \s-1POSIX\s0 model, which cannot |
|
|
3292 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3293 | .IP "The winsocket select function" 4 |
|
|
3294 | .IX Item "The winsocket select function" |
|
|
3295 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires |
|
|
3296 | socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select |
|
|
3297 | very inefficient, and also requires a mapping from file descriptors |
|
|
3298 | to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, |
|
|
3299 | \&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor |
|
|
3300 | symbols for more info. |
|
|
3301 | .Sp |
|
|
3302 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3303 | libraries and raw winsocket select is: |
|
|
3304 | .Sp |
|
|
3305 | .Vb 2 |
|
|
3306 | \& #define EV_USE_SELECT 1 |
|
|
3307 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3308 | .Ve |
|
|
3309 | .Sp |
|
|
3310 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3311 | complexity in the O(nA\*^X) range when using win32. |
|
|
3312 | .IP "Limited number of file descriptors" 4 |
|
|
3313 | .IX Item "Limited number of file descriptors" |
|
|
3314 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3315 | of winsocket's select only supported waiting for a max. of \f(CW64\fR handles |
|
|
3316 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3317 | \&\f(CW64\fR things at the same time internally; microsoft recommends spawning a |
|
|
3318 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3319 | .Sp |
|
|
3320 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3321 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3322 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3323 | select emulation on windows). |
|
|
3324 | .Sp |
|
|
3325 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3326 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3327 | or something like this inside microsoft). You can increase this by calling |
|
|
3328 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3329 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3330 | libraries. |
|
|
3331 | .Sp |
|
|
3332 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3333 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3334 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3335 | calling select (O(nA\*^X)) will likely make this unworkable. |
2332 | .SH "AUTHOR" |
3336 | .SH "AUTHOR" |
2333 | .IX Header "AUTHOR" |
3337 | .IX Header "AUTHOR" |
2334 | Marc Lehmann <libev@schmorp.de>. |
3338 | Marc Lehmann <libev@schmorp.de>. |
|
|
3339 | .SH "POD ERRORS" |
|
|
3340 | .IX Header "POD ERRORS" |
|
|
3341 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3342 | .IP "Around line 3015:" 4 |
|
|
3343 | .IX Item "Around line 3015:" |
|
|
3344 | You forgot a '=back' before '=head2' |