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133 | .\" |
131 | .IX Title "EV 1" |
134 | .IX Title "LIBEV 3" |
132 | .TH EV 1 "2007-12-22" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH LIBEV 3 "2008-05-09" "libev-1.1" "libev - high perfromance full featured event loop" |
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136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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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" |
201 | The newest version of this document is also available as a html-formatted |
206 | The newest version of this document is also available as an html-formatted |
202 | web page you might find easier to navigate when reading it for the first |
207 | web page you might find easier to navigate when reading it for the first |
203 | time: <http://cvs.schmorp.de/libev/ev.html>. |
208 | time: <http://cvs.schmorp.de/libev/ev.html>. |
204 | .PP |
209 | .PP |
205 | 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 |
206 | file descriptor being readable or a timeout occurring), and it will manage |
211 | file descriptor being readable or a timeout occurring), and it will manage |
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212 | .PP |
217 | .PP |
213 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
214 | 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 |
215 | 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 |
216 | watcher. |
221 | watcher. |
217 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
218 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
219 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
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 |
220 | 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 |
221 | 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 |
222 | (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 |
223 | 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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228 | (\f(CW\*(C`ev_fork\*(C'\fR). |
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
229 | .PP |
234 | .PP |
230 | It also is quite fast (see this |
235 | It also is quite fast (see this |
231 | benchmark comparing it to libevent |
236 | benchmark comparing it to libevent |
232 | for example). |
237 | for example). |
233 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
234 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
235 | Libev is very configurable. In this manual the default configuration will |
240 | Libev is very configurable. In this manual the default (and most common) |
236 | be described, which supports multiple event loops. For more info about |
241 | configuration will be described, which supports multiple event loops. For |
237 | 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 |
238 | 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 |
239 | 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 |
240 | (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 |
241 | .SH "TIME REPRESENTATION" |
246 | this argument. |
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247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
242 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
243 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
244 | (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 |
245 | 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 |
246 | 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 |
247 | 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 |
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313 | (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 |
314 | libev will probe for if you specify no backends explicitly. |
320 | libev will probe for if you specify no backends explicitly. |
315 | .IP "unsigned int ev_embeddable_backends ()" 4 |
321 | .IP "unsigned int ev_embeddable_backends ()" 4 |
316 | .IX Item "unsigned int ev_embeddable_backends ()" |
322 | .IX Item "unsigned int ev_embeddable_backends ()" |
317 | 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 |
318 | is the theoretical, all\-platform, value. To find which backends |
324 | is the theoretical, all-platform, value. To find which backends |
319 | 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 |
320 | \&\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 |
321 | recommended ones. |
327 | recommended ones. |
322 | .Sp |
328 | .Sp |
323 | 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. |
324 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
330 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
325 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
331 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
326 | Sets the allocation function to use (the prototype is similar \- the |
332 | Sets the allocation function to use (the prototype is similar \- the |
327 | semantics is identical \- to the realloc C function). It is used to |
333 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
328 | allocate and free memory (no surprises here). If it returns zero when |
334 | used to allocate and free memory (no surprises here). If it returns zero |
329 | memory needs to be allocated, the library might abort or take some |
335 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
330 | potentially destructive action. The default is your system realloc |
336 | or take some potentially destructive action. |
331 | function. |
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. |
332 | .Sp |
341 | .Sp |
333 | You could override this function in high-availability programs to, say, |
342 | You could override this function in high-availability programs to, say, |
334 | 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, |
335 | 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. |
336 | .Sp |
345 | .Sp |
337 | 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 |
338 | retries). |
347 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
339 | .Sp |
348 | .Sp |
340 | .Vb 6 |
349 | .Vb 6 |
341 | \& static void * |
350 | \& static void * |
342 | \& persistent_realloc (void *ptr, size_t size) |
351 | \& persistent_realloc (void *ptr, size_t size) |
343 | \& { |
352 | \& { |
344 | \& for (;;) |
353 | \& for (;;) |
345 | \& { |
354 | \& { |
346 | \& void *newptr = realloc (ptr, size); |
355 | \& void *newptr = realloc (ptr, size); |
347 | .Ve |
356 | \& |
348 | .Sp |
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349 | .Vb 2 |
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350 | \& if (newptr) |
357 | \& if (newptr) |
351 | \& return newptr; |
358 | \& return newptr; |
352 | .Ve |
359 | \& |
353 | .Sp |
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354 | .Vb 3 |
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355 | \& sleep (60); |
360 | \& sleep (60); |
356 | \& } |
361 | \& } |
357 | \& } |
362 | \& } |
358 | .Ve |
363 | \& |
359 | .Sp |
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360 | .Vb 2 |
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361 | \& ... |
364 | \& ... |
362 | \& ev_set_allocator (persistent_realloc); |
365 | \& ev_set_allocator (persistent_realloc); |
363 | .Ve |
366 | .Ve |
364 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
367 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
365 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
368 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
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378 | \& fatal_error (const char *msg) |
381 | \& fatal_error (const char *msg) |
379 | \& { |
382 | \& { |
380 | \& perror (msg); |
383 | \& perror (msg); |
381 | \& abort (); |
384 | \& abort (); |
382 | \& } |
385 | \& } |
383 | .Ve |
386 | \& |
384 | .Sp |
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385 | .Vb 2 |
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386 | \& ... |
387 | \& ... |
387 | \& ev_set_syserr_cb (fatal_error); |
388 | \& ev_set_syserr_cb (fatal_error); |
388 | .Ve |
389 | .Ve |
389 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
390 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
390 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
391 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
391 | 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 |
392 | 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 |
393 | events, and dynamically created loops which do not. |
394 | events, and dynamically created loops which do not. |
394 | .PP |
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395 | If you use threads, a common model is to run the default event loop |
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396 | in your main thread (or in a separate thread) and for each thread you |
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397 | create, you also create another event loop. Libev itself does no locking |
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398 | whatsoever, so if you mix calls to the same event loop in different |
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399 | threads, make sure you lock (this is usually a bad idea, though, even if |
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400 | done correctly, because it's hideous and inefficient). |
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401 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
395 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
402 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
396 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
403 | 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 |
404 | 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 |
405 | 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 |
406 | 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). |
407 | .Sp |
401 | .Sp |
408 | 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 |
409 | function. |
403 | function. |
|
|
404 | .Sp |
|
|
405 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
|
|
406 | from multiple threads, you have to lock (note also that this is unlikely, |
|
|
407 | as loops cannot bes hared easily between threads anyway). |
|
|
408 | .Sp |
|
|
409 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
|
|
410 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
|
|
411 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
|
|
412 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
|
|
413 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
|
|
414 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
410 | .Sp |
415 | .Sp |
411 | 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 |
412 | 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). |
413 | .Sp |
418 | .Sp |
414 | The following flags are supported: |
419 | The following flags are supported: |
… | |
… | |
435 | enabling this flag. |
440 | enabling this flag. |
436 | .Sp |
441 | .Sp |
437 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
442 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
438 | and thus this might slow down your event loop if you do a lot of loop |
443 | and thus this might slow down your event loop if you do a lot of loop |
439 | iterations and little real work, but is usually not noticeable (on my |
444 | iterations and little real work, but is usually not noticeable (on my |
440 | Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
445 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
441 | without a syscall and thus \fIvery\fR fast, but my Linux system also has |
446 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
442 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
447 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
443 | .Sp |
448 | .Sp |
444 | The big advantage of this flag is that you can forget about fork (and |
449 | The big advantage of this flag is that you can forget about fork (and |
445 | forget about forgetting to tell libev about forking) when you use this |
450 | forget about forgetting to tell libev about forking) when you use this |
446 | flag. |
451 | flag. |
… | |
… | |
452 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
457 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
453 | 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 |
454 | 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, |
455 | 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 |
456 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
461 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
457 | usually the fastest backend for a low number of (low\-numbered :) fds. |
462 | usually the fastest backend for a low number of (low-numbered :) fds. |
458 | .Sp |
463 | .Sp |
459 | To get good performance out of this backend you need a high amount of |
464 | To get good performance out of this backend you need a high amount of |
460 | parallelity (most of the file descriptors should be busy). If you are |
465 | parallelity (most of the file descriptors should be busy). If you are |
461 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
466 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
462 | connections as possible during one iteration. You might also want to have |
467 | connections as possible during one iteration. You might also want to have |
… | |
… | |
477 | 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, |
478 | but it scales phenomenally better. While poll and select usually scale |
483 | but it scales phenomenally better. While poll and select usually scale |
479 | like O(total_fds) where n is the total number of fds (or the highest fd), |
484 | like O(total_fds) where n is the total number of fds (or the highest fd), |
480 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
485 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
481 | of shortcomings, such as silently dropping events in some hard-to-detect |
486 | of shortcomings, such as silently dropping events in some hard-to-detect |
482 | cases and rewiring a syscall per fd change, no fork support and bad |
487 | cases and requiring a syscall per fd change, no fork support and bad |
483 | support for dup. |
488 | support for dup. |
484 | .Sp |
489 | .Sp |
485 | While stopping, setting and starting an I/O watcher in the same iteration |
490 | While stopping, setting and starting an I/O watcher in the same iteration |
486 | will 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 |
487 | (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 |
… | |
… | |
547 | .Sp |
552 | .Sp |
548 | While this backend scales well, it requires one system call per active |
553 | While this backend scales well, it requires one system call per active |
549 | file descriptor per loop iteration. For small and medium numbers of file |
554 | file descriptor per loop iteration. For small and medium numbers of file |
550 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
555 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
551 | might perform better. |
556 | might perform better. |
|
|
557 | .Sp |
|
|
558 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
559 | backend actually performed to specification in all tests and is fully |
|
|
560 | embeddable, which is a rare feat among the OS-specific backends. |
552 | .ie n .IP """EVBACKEND_ALL""" 4 |
561 | .ie n .IP """EVBACKEND_ALL""" 4 |
553 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
562 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
554 | .IX Item "EVBACKEND_ALL" |
563 | .IX Item "EVBACKEND_ALL" |
555 | 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 |
556 | 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 |
… | |
… | |
559 | It is definitely not recommended to use this flag. |
568 | It is definitely not recommended to use this flag. |
560 | .RE |
569 | .RE |
561 | .RS 4 |
570 | .RS 4 |
562 | .Sp |
571 | .Sp |
563 | 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 |
564 | 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 |
565 | 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. |
566 | order of their flag values :) |
|
|
567 | .Sp |
575 | .Sp |
568 | The most typical usage is like this: |
576 | The most typical usage is like this: |
569 | .Sp |
577 | .Sp |
570 | .Vb 2 |
578 | .Vb 2 |
571 | \& if (!ev_default_loop (0)) |
579 | \& if (!ev_default_loop (0)) |
… | |
… | |
591 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
599 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
592 | 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 |
593 | 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 |
594 | 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 |
595 | undefined behaviour (or a failed assertion if assertions are enabled). |
603 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
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. |
596 | .Sp |
608 | .Sp |
597 | 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. |
598 | .Sp |
610 | .Sp |
599 | .Vb 3 |
611 | .Vb 3 |
600 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
612 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
… | |
… | |
623 | .IX Item "ev_loop_destroy (loop)" |
635 | .IX Item "ev_loop_destroy (loop)" |
624 | 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 |
625 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
637 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
626 | .IP "ev_default_fork ()" 4 |
638 | .IP "ev_default_fork ()" 4 |
627 | .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 |
628 | This function reinitialises the kernel state for backends that have |
641 | to reinitialise the kernel state for backends that have one. Despite the |
629 | 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 |
630 | 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 |
631 | 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. |
632 | .Sp |
646 | .Sp |
633 | 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 |
634 | 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 |
635 | fork+exec, you don't have to call it. |
649 | you just fork+exec, you don't have to call it at all. |
636 | .Sp |
650 | .Sp |
637 | 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 |
638 | 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 |
639 | 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: |
640 | .Sp |
654 | .Sp |
641 | .Vb 1 |
655 | .Vb 1 |
642 | \& pthread_atfork (0, 0, ev_default_fork); |
656 | \& pthread_atfork (0, 0, ev_default_fork); |
643 | .Ve |
657 | .Ve |
644 | .Sp |
|
|
645 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
646 | without calling this function, so if you force one of those backends you |
|
|
647 | do not need to care. |
|
|
648 | .IP "ev_loop_fork (loop)" 4 |
658 | .IP "ev_loop_fork (loop)" 4 |
649 | .IX Item "ev_loop_fork (loop)" |
659 | .IX Item "ev_loop_fork (loop)" |
650 | 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 |
651 | \&\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 |
652 | 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. |
653 | .IP "unsigned int ev_loop_count (loop)" 4 |
666 | .IP "unsigned int ev_loop_count (loop)" 4 |
654 | .IX Item "unsigned int ev_loop_count (loop)" |
667 | .IX Item "unsigned int ev_loop_count (loop)" |
655 | Returns the count of loop iterations for the loop, which is identical to |
668 | Returns the count of loop iterations for the loop, which is identical to |
656 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
669 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
657 | happily wraps around with enough iterations. |
670 | happily wraps around with enough iterations. |
… | |
… | |
697 | 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 |
698 | usually a better approach for this kind of thing. |
711 | usually a better approach for this kind of thing. |
699 | .Sp |
712 | .Sp |
700 | 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: |
701 | .Sp |
714 | .Sp |
702 | .Vb 19 |
715 | .Vb 10 |
703 | \& - Before the first iteration, call any pending watchers. |
716 | \& \- Before the first iteration, call any pending watchers. |
704 | \& * If there are no active watchers (reference count is zero), return. |
717 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
705 | \& - Queue all prepare watchers and then call all outstanding watchers. |
718 | \& \- If a fork was detected, queue and call all fork watchers. |
|
|
719 | \& \- Queue and call all prepare watchers. |
706 | \& - If we have been forked, recreate the kernel state. |
720 | \& \- If we have been forked, recreate the kernel state. |
707 | \& - Update the kernel state with all outstanding changes. |
721 | \& \- Update the kernel state with all outstanding changes. |
708 | \& - Update the "event loop time". |
722 | \& \- Update the "event loop time". |
709 | \& - 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. |
710 | \& - Block the process, waiting for any events. |
727 | \& \- Block the process, waiting for any events. |
711 | \& - Queue all outstanding I/O (fd) events. |
728 | \& \- Queue all outstanding I/O (fd) events. |
712 | \& - Update the "event loop time" and do time jump handling. |
729 | \& \- Update the "event loop time" and do time jump handling. |
713 | \& - Queue all outstanding timers. |
730 | \& \- Queue all outstanding timers. |
714 | \& - Queue all outstanding periodics. |
731 | \& \- Queue all outstanding periodics. |
715 | \& - If no events are pending now, queue all idle watchers. |
732 | \& \- If no events are pending now, queue all idle watchers. |
716 | \& - Queue all check watchers. |
733 | \& \- Queue all check watchers. |
717 | \& - 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). |
718 | \& 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 |
719 | \& be handled here by queueing them when their watcher gets executed. |
736 | \& be handled here by queueing them when their watcher gets executed. |
720 | \& - 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 |
721 | \& were used, return, otherwise continue with step *. |
738 | \& were used, or there are no active watchers, return, otherwise |
|
|
739 | \& continue with step *. |
722 | .Ve |
740 | .Ve |
723 | .Sp |
741 | .Sp |
724 | 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 |
725 | anymore. |
743 | anymore. |
726 | .Sp |
744 | .Sp |
727 | .Vb 4 |
745 | .Vb 4 |
728 | \& ... queue jobs here, make sure they register event watchers as long |
746 | \& ... queue jobs here, make sure they register event watchers as long |
729 | \& ... 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..) |
… | |
… | |
734 | .IX Item "ev_unloop (loop, how)" |
752 | .IX Item "ev_unloop (loop, how)" |
735 | 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 |
736 | 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 |
737 | \&\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 |
738 | \&\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. |
739 | .IP "ev_ref (loop)" 4 |
759 | .IP "ev_ref (loop)" 4 |
740 | .IX Item "ev_ref (loop)" |
760 | .IX Item "ev_ref (loop)" |
741 | .PD 0 |
761 | .PD 0 |
742 | .IP "ev_unref (loop)" 4 |
762 | .IP "ev_unref (loop)" 4 |
743 | .IX Item "ev_unref (loop)" |
763 | .IX Item "ev_unref (loop)" |
… | |
… | |
749 | 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 |
750 | 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 |
751 | 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 |
752 | 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 |
753 | 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 |
754 | 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). |
755 | .Sp |
777 | .Sp |
756 | 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 |
757 | running when nothing else is active. |
779 | running when nothing else is active. |
758 | .Sp |
780 | .Sp |
759 | .Vb 4 |
781 | .Vb 4 |
… | |
… | |
816 | \& 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) |
817 | \& { |
839 | \& { |
818 | \& ev_io_stop (w); |
840 | \& ev_io_stop (w); |
819 | \& ev_unloop (loop, EVUNLOOP_ALL); |
841 | \& ev_unloop (loop, EVUNLOOP_ALL); |
820 | \& } |
842 | \& } |
821 | .Ve |
843 | \& |
822 | .PP |
|
|
823 | .Vb 6 |
|
|
824 | \& struct ev_loop *loop = ev_default_loop (0); |
844 | \& struct ev_loop *loop = ev_default_loop (0); |
825 | \& struct ev_io stdin_watcher; |
845 | \& struct ev_io stdin_watcher; |
826 | \& ev_init (&stdin_watcher, my_cb); |
846 | \& ev_init (&stdin_watcher, my_cb); |
827 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
847 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
828 | \& ev_io_start (loop, &stdin_watcher); |
848 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
916 | .ie n .IP """EV_FORK""" 4 |
936 | .ie n .IP """EV_FORK""" 4 |
917 | .el .IP "\f(CWEV_FORK\fR" 4 |
937 | .el .IP "\f(CWEV_FORK\fR" 4 |
918 | .IX Item "EV_FORK" |
938 | .IX Item "EV_FORK" |
919 | 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 |
920 | \&\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). |
921 | .ie n .IP """EV_ERROR""" 4 |
945 | .ie n .IP """EV_ERROR""" 4 |
922 | .el .IP "\f(CWEV_ERROR\fR" 4 |
946 | .el .IP "\f(CWEV_ERROR\fR" 4 |
923 | .IX Item "EV_ERROR" |
947 | .IX Item "EV_ERROR" |
924 | 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 |
925 | happen because the watcher could not be properly started because libev |
949 | happen because the watcher could not be properly started because libev |
… | |
… | |
1089 | 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, |
1090 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1114 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1091 | .PP |
1115 | .PP |
1092 | .Vb 1 |
1116 | .Vb 1 |
1093 | \& #include <stddef.h> |
1117 | \& #include <stddef.h> |
1094 | .Ve |
1118 | \& |
1095 | .PP |
|
|
1096 | .Vb 6 |
|
|
1097 | \& static void |
1119 | \& static void |
1098 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1120 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1099 | \& { |
1121 | \& { |
1100 | \& struct my_biggy big = (struct my_biggy * |
1122 | \& struct my_biggy big = (struct my_biggy * |
1101 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
1123 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1102 | \& } |
1124 | \& } |
1103 | .Ve |
1125 | \& |
1104 | .PP |
|
|
1105 | .Vb 6 |
|
|
1106 | \& static void |
1126 | \& static void |
1107 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1127 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1108 | \& { |
1128 | \& { |
1109 | \& struct my_biggy big = (struct my_biggy * |
1129 | \& struct my_biggy big = (struct my_biggy * |
1110 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
1130 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1111 | \& } |
1131 | \& } |
1112 | .Ve |
1132 | .Ve |
1113 | .SH "WATCHER TYPES" |
1133 | .SH "WATCHER TYPES" |
1114 | .IX Header "WATCHER TYPES" |
1134 | .IX Header "WATCHER TYPES" |
1115 | This section describes each watcher in detail, but will not repeat |
1135 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1138 | 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 |
1139 | 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 |
1140 | 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 |
1141 | required if you know what you are doing). |
1161 | required if you know what you are doing). |
1142 | .PP |
1162 | .PP |
1143 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
1144 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
1145 | descriptors correctly if you register interest in two or more fds pointing |
|
|
1146 | to the same underlying file/socket/etc. description (that is, they share |
|
|
1147 | the same underlying \*(L"file open\*(R"). |
|
|
1148 | .PP |
|
|
1149 | 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 |
1150 | (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 |
1151 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1165 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1152 | .PP |
1166 | .PP |
1153 | 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 |
… | |
… | |
1189 | .PP |
1203 | .PP |
1190 | \fIThe special problem of dup'ed file descriptors\fR |
1204 | \fIThe special problem of dup'ed file descriptors\fR |
1191 | .IX Subsection "The special problem of dup'ed file descriptors" |
1205 | .IX Subsection "The special problem of dup'ed file descriptors" |
1192 | .PP |
1206 | .PP |
1193 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1207 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1194 | but only events for the underlying file descriptions. That menas when you |
1208 | but only events for the underlying file descriptions. That means when you |
1195 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one |
1209 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
1196 | file descriptor might actually receive events. |
1210 | events for them, only one file descriptor might actually receive events. |
1197 | .PP |
1211 | .PP |
1198 | There is no workaorund possible except not registering events |
1212 | There is no workaround possible except not registering events |
1199 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to |
1213 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1200 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1214 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1201 | .PP |
1215 | .PP |
1202 | \fIThe special problem of fork\fR |
1216 | \fIThe special problem of fork\fR |
1203 | .IX Subsection "The special problem of fork" |
1217 | .IX Subsection "The special problem of fork" |
1204 | .PP |
1218 | .PP |
… | |
… | |
1208 | .PP |
1222 | .PP |
1209 | To support fork in your programs, you either have to call |
1223 | To support fork in your programs, you either have to call |
1210 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1224 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1211 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1225 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1212 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
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). |
1213 | .PP |
1240 | .PP |
1214 | \fIWatcher-Specific Functions\fR |
1241 | \fIWatcher-Specific Functions\fR |
1215 | .IX Subsection "Watcher-Specific Functions" |
1242 | .IX Subsection "Watcher-Specific Functions" |
1216 | .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 |
1217 | .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)" |
… | |
… | |
1227 | The file descriptor being watched. |
1254 | The file descriptor being watched. |
1228 | .IP "int events [read\-only]" 4 |
1255 | .IP "int events [read\-only]" 4 |
1229 | .IX Item "int events [read-only]" |
1256 | .IX Item "int events [read-only]" |
1230 | The events being watched. |
1257 | The events being watched. |
1231 | .PP |
1258 | .PP |
|
|
1259 | \fIExamples\fR |
|
|
1260 | .IX Subsection "Examples" |
|
|
1261 | .PP |
1232 | 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 |
1233 | 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 |
1234 | attempt to read a whole line in the callback. |
1264 | attempt to read a whole line in the callback. |
1235 | .PP |
1265 | .PP |
1236 | .Vb 6 |
1266 | .Vb 6 |
1237 | \& static void |
1267 | \& static void |
1238 | \& 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) |
1239 | \& { |
1269 | \& { |
1240 | \& ev_io_stop (loop, w); |
1270 | \& ev_io_stop (loop, w); |
1241 | \& .. 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 |
1242 | \& } |
1272 | \& } |
1243 | .Ve |
1273 | \& |
1244 | .PP |
|
|
1245 | .Vb 6 |
|
|
1246 | \& ... |
1274 | \& ... |
1247 | \& struct ev_loop *loop = ev_default_init (0); |
1275 | \& struct ev_loop *loop = ev_default_init (0); |
1248 | \& struct ev_io stdin_readable; |
1276 | \& struct ev_io stdin_readable; |
1249 | \& 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); |
1250 | \& ev_io_start (loop, &stdin_readable); |
1278 | \& ev_io_start (loop, &stdin_readable); |
… | |
… | |
1267 | of the event triggering whatever timeout you are modifying/starting. If |
1295 | of the event triggering whatever timeout you are modifying/starting. If |
1268 | 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 |
1269 | 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: |
1270 | .PP |
1298 | .PP |
1271 | .Vb 1 |
1299 | .Vb 1 |
1272 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1300 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1273 | .Ve |
1301 | .Ve |
1274 | .PP |
1302 | .PP |
1275 | 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, |
1276 | 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 |
1277 | order of execution is undefined. |
1305 | order of execution is undefined. |
… | |
… | |
1292 | 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 |
1293 | 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 |
1294 | 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 |
1295 | 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 |
1296 | timer will not fire more than once per event loop iteration. |
1324 | timer will not fire more than once per event loop iteration. |
1297 | .IP "ev_timer_again (loop)" 4 |
1325 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1298 | .IX Item "ev_timer_again (loop)" |
1326 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1299 | 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 |
1300 | repeating. The exact semantics are: |
1328 | repeating. The exact semantics are: |
1301 | .Sp |
1329 | .Sp |
1302 | If the timer is pending, its pending status is cleared. |
1330 | If the timer is pending, its pending status is cleared. |
1303 | .Sp |
1331 | .Sp |
… | |
… | |
1321 | .Sp |
1349 | .Sp |
1322 | .Vb 8 |
1350 | .Vb 8 |
1323 | \& ev_timer_init (timer, callback, 0., 5.); |
1351 | \& ev_timer_init (timer, callback, 0., 5.); |
1324 | \& ev_timer_again (loop, timer); |
1352 | \& ev_timer_again (loop, timer); |
1325 | \& ... |
1353 | \& ... |
1326 | \& timer->again = 17.; |
1354 | \& timer\->again = 17.; |
1327 | \& ev_timer_again (loop, timer); |
1355 | \& ev_timer_again (loop, timer); |
1328 | \& ... |
1356 | \& ... |
1329 | \& timer->again = 10.; |
1357 | \& timer\->again = 10.; |
1330 | \& ev_timer_again (loop, timer); |
1358 | \& ev_timer_again (loop, timer); |
1331 | .Ve |
1359 | .Ve |
1332 | .Sp |
1360 | .Sp |
1333 | This is more slightly efficient then stopping/starting the timer each time |
1361 | This is more slightly efficient then stopping/starting the timer each time |
1334 | you want to modify its timeout value. |
1362 | you want to modify its timeout value. |
… | |
… | |
1336 | .IX Item "ev_tstamp repeat [read-write]" |
1364 | .IX Item "ev_tstamp repeat [read-write]" |
1337 | 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 |
1338 | 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), |
1339 | which is also when any modifications are taken into account. |
1367 | which is also when any modifications are taken into account. |
1340 | .PP |
1368 | .PP |
|
|
1369 | \fIExamples\fR |
|
|
1370 | .IX Subsection "Examples" |
|
|
1371 | .PP |
1341 | Example: Create a timer that fires after 60 seconds. |
1372 | Example: Create a timer that fires after 60 seconds. |
1342 | .PP |
1373 | .PP |
1343 | .Vb 5 |
1374 | .Vb 5 |
1344 | \& static void |
1375 | \& static void |
1345 | \& 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) |
1346 | \& { |
1377 | \& { |
1347 | \& .. one minute over, w is actually stopped right here |
1378 | \& .. one minute over, w is actually stopped right here |
1348 | \& } |
1379 | \& } |
1349 | .Ve |
1380 | \& |
1350 | .PP |
|
|
1351 | .Vb 3 |
|
|
1352 | \& struct ev_timer mytimer; |
1381 | \& struct ev_timer mytimer; |
1353 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1382 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1354 | \& ev_timer_start (loop, &mytimer); |
1383 | \& ev_timer_start (loop, &mytimer); |
1355 | .Ve |
1384 | .Ve |
1356 | .PP |
1385 | .PP |
… | |
… | |
1361 | \& static void |
1390 | \& static void |
1362 | \& 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) |
1363 | \& { |
1392 | \& { |
1364 | \& .. ten seconds without any activity |
1393 | \& .. ten seconds without any activity |
1365 | \& } |
1394 | \& } |
1366 | .Ve |
1395 | \& |
1367 | .PP |
|
|
1368 | .Vb 4 |
|
|
1369 | \& struct ev_timer mytimer; |
1396 | \& struct ev_timer mytimer; |
1370 | \& 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 */ |
1371 | \& ev_timer_again (&mytimer); /* start timer */ |
1398 | \& ev_timer_again (&mytimer); /* start timer */ |
1372 | \& ev_loop (loop, 0); |
1399 | \& ev_loop (loop, 0); |
1373 | .Ve |
1400 | \& |
1374 | .PP |
|
|
1375 | .Vb 3 |
|
|
1376 | \& // 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": |
1377 | \& // reset the timeout to start ticking again at 10 seconds |
1402 | \& // reset the timeout to start ticking again at 10 seconds |
1378 | \& ev_timer_again (&mytimer); |
1403 | \& ev_timer_again (&mytimer); |
1379 | .Ve |
1404 | .Ve |
1380 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1405 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
… | |
… | |
1408 | .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)" |
1409 | .PD |
1434 | .PD |
1410 | 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 |
1411 | operation, and we will explain them from simplest to complex: |
1436 | operation, and we will explain them from simplest to complex: |
1412 | .RS 4 |
1437 | .RS 4 |
|
|
1438 | .IP "\(bu" 4 |
1413 | .IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4 |
1439 | absolute timer (at = time, interval = reschedule_cb = 0) |
1414 | .IX Item "absolute timer (at = time, interval = reschedule_cb = 0)" |
1440 | .Sp |
1415 | 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 |
1416 | \&\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, |
1417 | 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 |
1418 | system time reaches or surpasses this time. |
1444 | system time reaches or surpasses this time. |
|
|
1445 | .IP "\(bu" 4 |
1419 | .IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4 |
1446 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1420 | .IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" |
1447 | .Sp |
1421 | 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 |
1422 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1449 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1423 | and then repeat, regardless of any time jumps. |
1450 | and then repeat, regardless of any time jumps. |
1424 | .Sp |
1451 | .Sp |
1425 | 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 |
… | |
… | |
1439 | 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. |
1440 | .Sp |
1467 | .Sp |
1441 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
1468 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
1442 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1469 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1443 | this value. |
1470 | this value. |
|
|
1471 | .IP "\(bu" 4 |
1444 | .IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4 |
1472 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1445 | .IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)" |
1473 | .Sp |
1446 | 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 |
1447 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1475 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1448 | 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 |
1449 | current time as second argument. |
1477 | current time as second argument. |
1450 | .Sp |
1478 | .Sp |
… | |
… | |
1483 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1511 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1484 | 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 |
1485 | when you changed some parameters or the reschedule callback would return |
1513 | when you changed some parameters or the reschedule callback would return |
1486 | 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 |
1487 | program when the crontabs have changed). |
1515 | program when the crontabs have changed). |
|
|
1516 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
1517 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
1518 | When active, returns the absolute time that the watcher is supposed to |
|
|
1519 | trigger next. |
1488 | .IP "ev_tstamp offset [read\-write]" 4 |
1520 | .IP "ev_tstamp offset [read\-write]" 4 |
1489 | .IX Item "ev_tstamp offset [read-write]" |
1521 | .IX Item "ev_tstamp offset [read-write]" |
1490 | When repeating, this contains the offset value, otherwise this is the |
1522 | When repeating, this contains the offset value, otherwise this is the |
1491 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
1523 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
1492 | .Sp |
1524 | .Sp |
… | |
… | |
1500 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1532 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1501 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1533 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1502 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1534 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1503 | switched off. Can be changed any time, but changes only take effect when |
1535 | switched off. Can be changed any time, but changes only take effect when |
1504 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1536 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1505 | .IP "ev_tstamp at [read\-only]" 4 |
1537 | .PP |
1506 | .IX Item "ev_tstamp at [read-only]" |
1538 | \fIExamples\fR |
1507 | When active, contains the absolute time that the watcher is supposed to |
1539 | .IX Subsection "Examples" |
1508 | trigger next. |
|
|
1509 | .PP |
1540 | .PP |
1510 | Example: Call a callback every hour, or, more precisely, whenever the |
1541 | Example: Call a callback every hour, or, more precisely, whenever the |
1511 | system clock is divisible by 3600. The callback invocation times have |
1542 | system clock is divisible by 3600. The callback invocation times have |
1512 | potentially a lot of jittering, but good long-term stability. |
1543 | potentially a lot of jittering, but good long-term stability. |
1513 | .PP |
1544 | .PP |
… | |
… | |
1515 | \& static void |
1546 | \& static void |
1516 | \& 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) |
1517 | \& { |
1548 | \& { |
1518 | \& ... 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) |
1519 | \& } |
1550 | \& } |
1520 | .Ve |
1551 | \& |
1521 | .PP |
|
|
1522 | .Vb 3 |
|
|
1523 | \& struct ev_periodic hourly_tick; |
1552 | \& struct ev_periodic hourly_tick; |
1524 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1553 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1525 | \& ev_periodic_start (loop, &hourly_tick); |
1554 | \& ev_periodic_start (loop, &hourly_tick); |
1526 | .Ve |
1555 | .Ve |
1527 | .PP |
1556 | .PP |
1528 | 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: |
1529 | .PP |
1558 | .PP |
1530 | .Vb 1 |
1559 | .Vb 1 |
1531 | \& #include <math.h> |
1560 | \& #include <math.h> |
1532 | .Ve |
1561 | \& |
1533 | .PP |
|
|
1534 | .Vb 5 |
|
|
1535 | \& static ev_tstamp |
1562 | \& static ev_tstamp |
1536 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1563 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1537 | \& { |
1564 | \& { |
1538 | \& return fmod (now, 3600.) + 3600.; |
1565 | \& return fmod (now, 3600.) + 3600.; |
1539 | \& } |
1566 | \& } |
1540 | .Ve |
1567 | \& |
1541 | .PP |
|
|
1542 | .Vb 1 |
|
|
1543 | \& 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); |
1544 | .Ve |
1569 | .Ve |
1545 | .PP |
1570 | .PP |
1546 | Example: Call a callback every hour, starting now: |
1571 | Example: Call a callback every hour, starting now: |
1547 | .PP |
1572 | .PP |
… | |
… | |
1563 | first watcher gets started will libev actually register a signal watcher |
1588 | first watcher gets started will libev actually register a signal watcher |
1564 | 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 |
1565 | 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 |
1566 | 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 |
1567 | \&\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. |
1568 | .PP |
1599 | .PP |
1569 | \fIWatcher-Specific Functions and Data Members\fR |
1600 | \fIWatcher-Specific Functions and Data Members\fR |
1570 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1601 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1571 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1602 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1572 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1603 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1577 | 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 |
1578 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1609 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1579 | .IP "int signum [read\-only]" 4 |
1610 | .IP "int signum [read\-only]" 4 |
1580 | .IX Item "int signum [read-only]" |
1611 | .IX Item "int signum [read-only]" |
1581 | 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 |
1582 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1630 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1583 | .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" |
1584 | .IX Subsection "ev_child - watch out for process status changes" |
1632 | .IX Subsection "ev_child - watch out for process status changes" |
1585 | 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 |
1586 | 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. |
1587 | .PP |
1662 | .PP |
1588 | \fIWatcher-Specific Functions and Data Members\fR |
1663 | \fIWatcher-Specific Functions and Data Members\fR |
1589 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1664 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1590 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1665 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1591 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1666 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1592 | .PD 0 |
1667 | .PD 0 |
1593 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1668 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1594 | .IX Item "ev_child_set (ev_child *, int pid)" |
1669 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1595 | .PD |
1670 | .PD |
1596 | 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 |
1597 | \&\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 |
1598 | 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 |
1599 | 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 |
1600 | \&\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 |
1601 | 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). |
1602 | .IP "int pid [read\-only]" 4 |
1679 | .IP "int pid [read\-only]" 4 |
1603 | .IX Item "int pid [read-only]" |
1680 | .IX Item "int pid [read-only]" |
1604 | 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. |
1605 | .IP "int rpid [read\-write]" 4 |
1682 | .IP "int rpid [read\-write]" 4 |
1606 | .IX Item "int rpid [read-write]" |
1683 | .IX Item "int rpid [read-write]" |
… | |
… | |
1608 | .IP "int rstatus [read\-write]" 4 |
1685 | .IP "int rstatus [read\-write]" 4 |
1609 | .IX Item "int rstatus [read-write]" |
1686 | .IX Item "int rstatus [read-write]" |
1610 | 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 |
1611 | \&\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). |
1612 | .PP |
1689 | .PP |
1613 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
1690 | \fIExamples\fR |
|
|
1691 | .IX Subsection "Examples" |
1614 | .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 |
1615 | .Vb 5 |
1696 | .Vb 1 |
|
|
1697 | \& ev_child cw; |
|
|
1698 | \& |
1616 | \& static void |
1699 | \& static void |
1617 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1700 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
1618 | \& { |
1701 | \& { |
1619 | \& 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); |
1620 | \& } |
1704 | \& } |
1621 | .Ve |
1705 | \& |
1622 | .PP |
1706 | \& pid_t pid = fork (); |
1623 | .Vb 3 |
1707 | \& |
1624 | \& struct ev_signal signal_watcher; |
1708 | \& if (pid < 0) |
1625 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1709 | \& // error |
1626 | \& 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 | \& } |
1627 | .Ve |
1720 | .Ve |
1628 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1721 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1629 | .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?" |
1630 | .IX Subsection "ev_stat - did the file attributes just change?" |
1723 | .IX Subsection "ev_stat - did the file attributes just change?" |
1631 | 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 |
… | |
… | |
1650 | 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 |
1651 | usually overkill. |
1744 | usually overkill. |
1652 | .PP |
1745 | .PP |
1653 | 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, |
1654 | as even with OS-supported change notifications, this can be |
1747 | as even with OS-supported change notifications, this can be |
1655 | resource\-intensive. |
1748 | resource-intensive. |
1656 | .PP |
1749 | .PP |
1657 | 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 |
1658 | implemented (implementing kqueue support is left as an exercise for the |
1751 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1752 | reader, note, however, that the author sees no way of implementing ev_stat |
1659 | reader). Inotify will be used to give hints only and should not change the |
1753 | semantics with kqueue). Inotify will be used to give hints only and should |
1660 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
1754 | not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev |
1661 | to fall back to regular polling again even with inotify, but changes are |
1755 | sometimes needs to fall back to regular polling again even with inotify, |
1662 | usually detected immediately, and if the file exists there will be no |
1756 | but changes are usually detected immediately, and if the file exists there |
1663 | polling. |
1757 | will be no polling. |
|
|
1758 | .PP |
|
|
1759 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
1760 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
1761 | .PP |
|
|
1762 | Libev by default (unless the user overrides this) uses the default |
|
|
1763 | compilation environment, which means that on systems with optionally |
|
|
1764 | disabled large file support, you get the 32 bit version of the stat |
|
|
1765 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
1766 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1767 | compile libev with the same flags to get binary compatibility. This is |
|
|
1768 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
1769 | most noticably with ev_stat and largefile support. |
|
|
1770 | .PP |
|
|
1771 | \fIInotify\fR |
|
|
1772 | .IX Subsection "Inotify" |
|
|
1773 | .PP |
|
|
1774 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1775 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1776 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1777 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1778 | .PP |
|
|
1779 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1780 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1781 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
1782 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1783 | .PP |
|
|
1784 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1785 | implement this functionality, due to the requirement of having a file |
|
|
1786 | descriptor open on the object at all times). |
|
|
1787 | .PP |
|
|
1788 | \fIThe special problem of stat time resolution\fR |
|
|
1789 | .IX Subsection "The special problem of stat time resolution" |
|
|
1790 | .PP |
|
|
1791 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1792 | even on systems where the resolution is higher, many filesystems still |
|
|
1793 | only support whole seconds. |
|
|
1794 | .PP |
|
|
1795 | That means that, if the time is the only thing that changes, you can |
|
|
1796 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
1797 | calls your callback, which does something. When there is another update |
|
|
1798 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it as the stat |
|
|
1799 | data does not change. |
|
|
1800 | .PP |
|
|
1801 | The solution to this is to delay acting on a change for slightly more |
|
|
1802 | than second (or till slightly after the next full second boundary), using |
|
|
1803 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
1804 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
1805 | .PP |
|
|
1806 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
1807 | of some operating systems (where the second counter of the current time |
|
|
1808 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1809 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
1810 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
1811 | update file times then there will be a small window where the kernel uses |
|
|
1812 | the previous second to update file times but libev might already execute |
|
|
1813 | the timer callback). |
1664 | .PP |
1814 | .PP |
1665 | \fIWatcher-Specific Functions and Data Members\fR |
1815 | \fIWatcher-Specific Functions and Data Members\fR |
1666 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1816 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1667 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1817 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1668 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1818 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
… | |
… | |
1674 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1824 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1675 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1825 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1676 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1826 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1677 | path for as long as the watcher is active. |
1827 | path for as long as the watcher is active. |
1678 | .Sp |
1828 | .Sp |
1679 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1829 | The callback will receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, relative |
1680 | relative to the attributes at the time the watcher was started (or the |
1830 | to the attributes at the time the watcher was started (or the last change |
1681 | last change was detected). |
1831 | was detected). |
1682 | .IP "ev_stat_stat (ev_stat *)" 4 |
1832 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1683 | .IX Item "ev_stat_stat (ev_stat *)" |
1833 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1684 | Updates the stat buffer immediately with new values. If you change the |
1834 | Updates the stat buffer immediately with new values. If you change the |
1685 | watched path in your callback, you could call this fucntion to avoid |
1835 | watched path in your callback, you could call this function to avoid |
1686 | detecting this change (while introducing a race condition). Can also be |
1836 | detecting this change (while introducing a race condition if you are not |
1687 | useful simply to find out the new values. |
1837 | the only one changing the path). Can also be useful simply to find out the |
|
|
1838 | new values. |
1688 | .IP "ev_statdata attr [read\-only]" 4 |
1839 | .IP "ev_statdata attr [read\-only]" 4 |
1689 | .IX Item "ev_statdata attr [read-only]" |
1840 | .IX Item "ev_statdata attr [read-only]" |
1690 | The most-recently detected attributes of the file. Although the type is of |
1841 | The most-recently detected attributes of the file. Although the type is |
1691 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
1842 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
1843 | suitable for your system, but you can only rely on the POSIX-standardised |
1692 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
1844 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
1693 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1845 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1694 | .IP "ev_statdata prev [read\-only]" 4 |
1846 | .IP "ev_statdata prev [read\-only]" 4 |
1695 | .IX Item "ev_statdata prev [read-only]" |
1847 | .IX Item "ev_statdata prev [read-only]" |
1696 | The previous attributes of the file. The callback gets invoked whenever |
1848 | The previous attributes of the file. The callback gets invoked whenever |
1697 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
1849 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
1850 | differ: \f(CW\*(C`st_dev\*(C'\fR, \f(CW\*(C`st_ino\*(C'\fR, \f(CW\*(C`st_mode\*(C'\fR, \f(CW\*(C`st_nlink\*(C'\fR, \f(CW\*(C`st_uid\*(C'\fR, |
|
|
1851 | \&\f(CW\*(C`st_gid\*(C'\fR, \f(CW\*(C`st_rdev\*(C'\fR, \f(CW\*(C`st_size\*(C'\fR, \f(CW\*(C`st_atime\*(C'\fR, \f(CW\*(C`st_mtime\*(C'\fR, \f(CW\*(C`st_ctime\*(C'\fR. |
1698 | .IP "ev_tstamp interval [read\-only]" 4 |
1852 | .IP "ev_tstamp interval [read\-only]" 4 |
1699 | .IX Item "ev_tstamp interval [read-only]" |
1853 | .IX Item "ev_tstamp interval [read-only]" |
1700 | The specified interval. |
1854 | The specified interval. |
1701 | .IP "const char *path [read\-only]" 4 |
1855 | .IP "const char *path [read\-only]" 4 |
1702 | .IX Item "const char *path [read-only]" |
1856 | .IX Item "const char *path [read-only]" |
1703 | The filesystem path that is being watched. |
1857 | The filesystem path that is being watched. |
1704 | .PP |
1858 | .PP |
|
|
1859 | \fIExamples\fR |
|
|
1860 | .IX Subsection "Examples" |
|
|
1861 | .PP |
1705 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1862 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1706 | .PP |
1863 | .PP |
1707 | .Vb 15 |
1864 | .Vb 10 |
1708 | \& static void |
1865 | \& static void |
1709 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1866 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1710 | \& { |
1867 | \& { |
1711 | \& /* /etc/passwd changed in some way */ |
1868 | \& /* /etc/passwd changed in some way */ |
1712 | \& if (w->attr.st_nlink) |
1869 | \& if (w\->attr.st_nlink) |
1713 | \& { |
1870 | \& { |
1714 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
1871 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1715 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
1872 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1716 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
1873 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1717 | \& } |
1874 | \& } |
1718 | \& else |
1875 | \& else |
1719 | \& /* you shalt not abuse printf for puts */ |
1876 | \& /* you shalt not abuse printf for puts */ |
1720 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1877 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1721 | \& "if this is windows, they already arrived\en"); |
1878 | \& "if this is windows, they already arrived\en"); |
1722 | \& } |
1879 | \& } |
1723 | .Ve |
1880 | \& |
1724 | .PP |
|
|
1725 | .Vb 2 |
|
|
1726 | \& ... |
1881 | \& ... |
1727 | \& ev_stat passwd; |
1882 | \& ev_stat passwd; |
|
|
1883 | \& |
|
|
1884 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1885 | \& ev_stat_start (loop, &passwd); |
1728 | .Ve |
1886 | .Ve |
|
|
1887 | .PP |
|
|
1888 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1889 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1890 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1891 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1729 | .PP |
1892 | .PP |
1730 | .Vb 2 |
1893 | .Vb 2 |
|
|
1894 | \& static ev_stat passwd; |
|
|
1895 | \& static ev_timer timer; |
|
|
1896 | \& |
|
|
1897 | \& static void |
|
|
1898 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1899 | \& { |
|
|
1900 | \& ev_timer_stop (EV_A_ w); |
|
|
1901 | \& |
|
|
1902 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1903 | \& } |
|
|
1904 | \& |
|
|
1905 | \& static void |
|
|
1906 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1907 | \& { |
|
|
1908 | \& /* reset the one\-second timer */ |
|
|
1909 | \& ev_timer_again (EV_A_ &timer); |
|
|
1910 | \& } |
|
|
1911 | \& |
|
|
1912 | \& ... |
1731 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1913 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1732 | \& ev_stat_start (loop, &passwd); |
1914 | \& ev_stat_start (loop, &passwd); |
|
|
1915 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1733 | .Ve |
1916 | .Ve |
1734 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1917 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1735 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1918 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1736 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1919 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1737 | Idle watchers trigger events when no other events of the same or higher |
1920 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1748 | The most noteworthy effect is that as long as any idle watchers are |
1931 | The most noteworthy effect is that as long as any idle watchers are |
1749 | active, the process will not block when waiting for new events. |
1932 | active, the process will not block when waiting for new events. |
1750 | .PP |
1933 | .PP |
1751 | Apart from keeping your process non-blocking (which is a useful |
1934 | Apart from keeping your process non-blocking (which is a useful |
1752 | effect on its own sometimes), idle watchers are a good place to do |
1935 | effect on its own sometimes), idle watchers are a good place to do |
1753 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1936 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1754 | event loop has handled all outstanding events. |
1937 | event loop has handled all outstanding events. |
1755 | .PP |
1938 | .PP |
1756 | \fIWatcher-Specific Functions and Data Members\fR |
1939 | \fIWatcher-Specific Functions and Data Members\fR |
1757 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1940 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1758 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1941 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1759 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1942 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1760 | Initialises and configures the idle watcher \- it has no parameters of any |
1943 | Initialises and configures the idle watcher \- it has no parameters of any |
1761 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1944 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1762 | believe me. |
1945 | believe me. |
1763 | .PP |
1946 | .PP |
|
|
1947 | \fIExamples\fR |
|
|
1948 | .IX Subsection "Examples" |
|
|
1949 | .PP |
1764 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1950 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1765 | callback, free it. Also, use no error checking, as usual. |
1951 | callback, free it. Also, use no error checking, as usual. |
1766 | .PP |
1952 | .PP |
1767 | .Vb 7 |
1953 | .Vb 7 |
1768 | \& static void |
1954 | \& static void |
1769 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1955 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1770 | \& { |
1956 | \& { |
1771 | \& free (w); |
1957 | \& free (w); |
1772 | \& // now do something you wanted to do when the program has |
1958 | \& // now do something you wanted to do when the program has |
1773 | \& // no longer asnything immediate to do. |
1959 | \& // no longer anything immediate to do. |
1774 | \& } |
1960 | \& } |
1775 | .Ve |
1961 | \& |
1776 | .PP |
|
|
1777 | .Vb 3 |
|
|
1778 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1962 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1779 | \& ev_idle_init (idle_watcher, idle_cb); |
1963 | \& ev_idle_init (idle_watcher, idle_cb); |
1780 | \& ev_idle_start (loop, idle_cb); |
1964 | \& ev_idle_start (loop, idle_cb); |
1781 | .Ve |
1965 | .Ve |
1782 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1966 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
… | |
… | |
1822 | .PP |
2006 | .PP |
1823 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
2007 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
1824 | priority, to ensure that they are being run before any other watchers |
2008 | priority, to ensure that they are being run before any other watchers |
1825 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
2009 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
1826 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
2010 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
1827 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers |
2011 | supports this, they might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers |
1828 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
2012 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
1829 | (non\-libev) event loops those other event loops might be in an unusable |
2013 | (non-libev) event loops those other event loops might be in an unusable |
1830 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
2014 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
1831 | coexist peacefully with others). |
2015 | coexist peacefully with others). |
1832 | .PP |
2016 | .PP |
1833 | \fIWatcher-Specific Functions and Data Members\fR |
2017 | \fIWatcher-Specific Functions and Data Members\fR |
1834 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2018 | .IX Subsection "Watcher-Specific Functions and Data Members" |
… | |
… | |
1840 | .PD |
2024 | .PD |
1841 | Initialises and configures the prepare or check watcher \- they have no |
2025 | Initialises and configures the prepare or check watcher \- they have no |
1842 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2026 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1843 | macros, but using them is utterly, utterly and completely pointless. |
2027 | macros, but using them is utterly, utterly and completely pointless. |
1844 | .PP |
2028 | .PP |
|
|
2029 | \fIExamples\fR |
|
|
2030 | .IX Subsection "Examples" |
|
|
2031 | .PP |
1845 | There are a number of principal ways to embed other event loops or modules |
2032 | There are a number of principal ways to embed other event loops or modules |
1846 | into libev. Here are some ideas on how to include libadns into libev |
2033 | into libev. Here are some ideas on how to include libadns into libev |
1847 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
2034 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
1848 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
2035 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
1849 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
2036 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
1850 | into the Glib event loop). |
2037 | Glib event loop). |
1851 | .PP |
2038 | .PP |
1852 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
2039 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1853 | and in a check watcher, destroy them and call into libadns. What follows |
2040 | and in a check watcher, destroy them and call into libadns. What follows |
1854 | is pseudo-code only of course. This requires you to either use a low |
2041 | is pseudo-code only of course. This requires you to either use a low |
1855 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
2042 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
1856 | the callbacks for the IO/timeout watchers might not have been called yet. |
2043 | the callbacks for the IO/timeout watchers might not have been called yet. |
1857 | .PP |
2044 | .PP |
1858 | .Vb 2 |
2045 | .Vb 2 |
1859 | \& static ev_io iow [nfd]; |
2046 | \& static ev_io iow [nfd]; |
1860 | \& static ev_timer tw; |
2047 | \& static ev_timer tw; |
1861 | .Ve |
2048 | \& |
1862 | .PP |
|
|
1863 | .Vb 4 |
|
|
1864 | \& static void |
2049 | \& static void |
1865 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2050 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
1866 | \& { |
2051 | \& { |
1867 | \& } |
2052 | \& } |
1868 | .Ve |
2053 | \& |
1869 | .PP |
|
|
1870 | .Vb 8 |
|
|
1871 | \& // create io watchers for each fd and a timer before blocking |
2054 | \& // create io watchers for each fd and a timer before blocking |
1872 | \& static void |
2055 | \& static void |
1873 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2056 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1874 | \& { |
2057 | \& { |
1875 | \& int timeout = 3600000; |
2058 | \& int timeout = 3600000; |
1876 | \& struct pollfd fds [nfd]; |
2059 | \& struct pollfd fds [nfd]; |
1877 | \& // actual code will need to loop here and realloc etc. |
2060 | \& // actual code will need to loop here and realloc etc. |
1878 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2061 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1879 | .Ve |
2062 | \& |
1880 | .PP |
|
|
1881 | .Vb 3 |
|
|
1882 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2063 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1883 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2064 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1884 | \& ev_timer_start (loop, &tw); |
2065 | \& ev_timer_start (loop, &tw); |
1885 | .Ve |
2066 | \& |
1886 | .PP |
|
|
1887 | .Vb 6 |
|
|
1888 | \& // create one ev_io per pollfd |
2067 | \& // create one ev_io per pollfd |
1889 | \& for (int i = 0; i < nfd; ++i) |
2068 | \& for (int i = 0; i < nfd; ++i) |
1890 | \& { |
2069 | \& { |
1891 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2070 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1892 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2071 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1893 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2072 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1894 | .Ve |
2073 | \& |
1895 | .PP |
|
|
1896 | .Vb 4 |
|
|
1897 | \& fds [i].revents = 0; |
2074 | \& fds [i].revents = 0; |
1898 | \& ev_io_start (loop, iow + i); |
2075 | \& ev_io_start (loop, iow + i); |
1899 | \& } |
2076 | \& } |
1900 | \& } |
2077 | \& } |
1901 | .Ve |
2078 | \& |
1902 | .PP |
|
|
1903 | .Vb 5 |
|
|
1904 | \& // stop all watchers after blocking |
2079 | \& // stop all watchers after blocking |
1905 | \& static void |
2080 | \& static void |
1906 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2081 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1907 | \& { |
2082 | \& { |
1908 | \& ev_timer_stop (loop, &tw); |
2083 | \& ev_timer_stop (loop, &tw); |
1909 | .Ve |
2084 | \& |
1910 | .PP |
|
|
1911 | .Vb 8 |
|
|
1912 | \& for (int i = 0; i < nfd; ++i) |
2085 | \& for (int i = 0; i < nfd; ++i) |
1913 | \& { |
2086 | \& { |
1914 | \& // set the relevant poll flags |
2087 | \& // set the relevant poll flags |
1915 | \& // could also call adns_processreadable etc. here |
2088 | \& // could also call adns_processreadable etc. here |
1916 | \& struct pollfd *fd = fds + i; |
2089 | \& struct pollfd *fd = fds + i; |
1917 | \& int revents = ev_clear_pending (iow + i); |
2090 | \& int revents = ev_clear_pending (iow + i); |
1918 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
2091 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
1919 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
2092 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
1920 | .Ve |
2093 | \& |
1921 | .PP |
|
|
1922 | .Vb 3 |
|
|
1923 | \& // now stop the watcher |
2094 | \& // now stop the watcher |
1924 | \& ev_io_stop (loop, iow + i); |
2095 | \& ev_io_stop (loop, iow + i); |
1925 | \& } |
2096 | \& } |
1926 | .Ve |
2097 | \& |
1927 | .PP |
|
|
1928 | .Vb 2 |
|
|
1929 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2098 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1930 | \& } |
2099 | \& } |
1931 | .Ve |
2100 | .Ve |
1932 | .PP |
2101 | .PP |
1933 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
2102 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
… | |
… | |
1939 | .PP |
2108 | .PP |
1940 | .Vb 5 |
2109 | .Vb 5 |
1941 | \& static void |
2110 | \& static void |
1942 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
2111 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
1943 | \& { |
2112 | \& { |
1944 | \& adns_state ads = (adns_state)w->data; |
2113 | \& adns_state ads = (adns_state)w\->data; |
1945 | \& update_now (EV_A); |
2114 | \& update_now (EV_A); |
1946 | .Ve |
2115 | \& |
1947 | .PP |
|
|
1948 | .Vb 2 |
|
|
1949 | \& adns_processtimeouts (ads, &tv_now); |
2116 | \& adns_processtimeouts (ads, &tv_now); |
1950 | \& } |
2117 | \& } |
1951 | .Ve |
2118 | \& |
1952 | .PP |
|
|
1953 | .Vb 5 |
|
|
1954 | \& static void |
2119 | \& static void |
1955 | \& io_cb (EV_P_ ev_io *w, int revents) |
2120 | \& io_cb (EV_P_ ev_io *w, int revents) |
1956 | \& { |
2121 | \& { |
1957 | \& adns_state ads = (adns_state)w->data; |
2122 | \& adns_state ads = (adns_state)w\->data; |
1958 | \& update_now (EV_A); |
2123 | \& update_now (EV_A); |
1959 | .Ve |
2124 | \& |
1960 | .PP |
|
|
1961 | .Vb 3 |
|
|
1962 | \& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
2125 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
1963 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
2126 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
1964 | \& } |
2127 | \& } |
1965 | .Ve |
2128 | \& |
1966 | .PP |
|
|
1967 | .Vb 1 |
|
|
1968 | \& // do not ever call adns_afterpoll |
2129 | \& // do not ever call adns_afterpoll |
1969 | .Ve |
2130 | .Ve |
1970 | .PP |
2131 | .PP |
1971 | Method 4: Do not use a prepare or check watcher because the module you |
2132 | Method 4: Do not use a prepare or check watcher because the module you |
1972 | want to embed is too inflexible to support it. Instead, youc na override |
2133 | want to embed is too inflexible to support it. Instead, youc na override |
… | |
… | |
1977 | .Vb 4 |
2138 | .Vb 4 |
1978 | \& static gint |
2139 | \& static gint |
1979 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
2140 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
1980 | \& { |
2141 | \& { |
1981 | \& int got_events = 0; |
2142 | \& int got_events = 0; |
1982 | .Ve |
2143 | \& |
1983 | .PP |
|
|
1984 | .Vb 2 |
|
|
1985 | \& for (n = 0; n < nfds; ++n) |
2144 | \& for (n = 0; n < nfds; ++n) |
1986 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
2145 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
1987 | .Ve |
2146 | \& |
1988 | .PP |
|
|
1989 | .Vb 2 |
|
|
1990 | \& if (timeout >= 0) |
2147 | \& if (timeout >= 0) |
1991 | \& // create/start timer |
2148 | \& // create/start timer |
1992 | .Ve |
2149 | \& |
1993 | .PP |
|
|
1994 | .Vb 2 |
|
|
1995 | \& // poll |
2150 | \& // poll |
1996 | \& ev_loop (EV_A_ 0); |
2151 | \& ev_loop (EV_A_ 0); |
1997 | .Ve |
2152 | \& |
1998 | .PP |
|
|
1999 | .Vb 3 |
|
|
2000 | \& // stop timer again |
2153 | \& // stop timer again |
2001 | \& if (timeout >= 0) |
2154 | \& if (timeout >= 0) |
2002 | \& ev_timer_stop (EV_A_ &to); |
2155 | \& ev_timer_stop (EV_A_ &to); |
2003 | .Ve |
2156 | \& |
2004 | .PP |
|
|
2005 | .Vb 3 |
|
|
2006 | \& // stop io watchers again - their callbacks should have set |
2157 | \& // stop io watchers again \- their callbacks should have set |
2007 | \& for (n = 0; n < nfds; ++n) |
2158 | \& for (n = 0; n < nfds; ++n) |
2008 | \& ev_io_stop (EV_A_ iow [n]); |
2159 | \& ev_io_stop (EV_A_ iow [n]); |
2009 | .Ve |
2160 | \& |
2010 | .PP |
|
|
2011 | .Vb 2 |
|
|
2012 | \& return got_events; |
2161 | \& return got_events; |
2013 | \& } |
2162 | \& } |
2014 | .Ve |
2163 | .Ve |
2015 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2164 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2016 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2165 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
… | |
… | |
2060 | portable one. |
2209 | portable one. |
2061 | .PP |
2210 | .PP |
2062 | So when you want to use this feature you will always have to be prepared |
2211 | So when you want to use this feature you will always have to be prepared |
2063 | that you cannot get an embeddable loop. The recommended way to get around |
2212 | that you cannot get an embeddable loop. The recommended way to get around |
2064 | this is to have a separate variables for your embeddable loop, try to |
2213 | this is to have a separate variables for your embeddable loop, try to |
2065 | create it, and if that fails, use the normal loop for everything: |
2214 | create it, and if that fails, use the normal loop for everything. |
2066 | .PP |
|
|
2067 | .Vb 3 |
|
|
2068 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2069 | \& struct ev_loop *loop_lo = 0; |
|
|
2070 | \& struct ev_embed embed; |
|
|
2071 | .Ve |
|
|
2072 | .PP |
|
|
2073 | .Vb 5 |
|
|
2074 | \& // see if there is a chance of getting one that works |
|
|
2075 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2076 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2077 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2078 | \& : 0; |
|
|
2079 | .Ve |
|
|
2080 | .PP |
|
|
2081 | .Vb 8 |
|
|
2082 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2083 | \& if (loop_lo) |
|
|
2084 | \& { |
|
|
2085 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2086 | \& ev_embed_start (loop_hi, &embed); |
|
|
2087 | \& } |
|
|
2088 | \& else |
|
|
2089 | \& loop_lo = loop_hi; |
|
|
2090 | .Ve |
|
|
2091 | .PP |
2215 | .PP |
2092 | \fIWatcher-Specific Functions and Data Members\fR |
2216 | \fIWatcher-Specific Functions and Data Members\fR |
2093 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2217 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2094 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2218 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2095 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2219 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
… | |
… | |
2108 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2232 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2109 | apropriate way for embedded loops. |
2233 | apropriate way for embedded loops. |
2110 | .IP "struct ev_loop *other [read\-only]" 4 |
2234 | .IP "struct ev_loop *other [read\-only]" 4 |
2111 | .IX Item "struct ev_loop *other [read-only]" |
2235 | .IX Item "struct ev_loop *other [read-only]" |
2112 | The embedded event loop. |
2236 | The embedded event loop. |
|
|
2237 | .PP |
|
|
2238 | \fIExamples\fR |
|
|
2239 | .IX Subsection "Examples" |
|
|
2240 | .PP |
|
|
2241 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2242 | event loop. If that is not possible, use the default loop. The default |
|
|
2243 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2244 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2245 | used). |
|
|
2246 | .PP |
|
|
2247 | .Vb 3 |
|
|
2248 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2249 | \& struct ev_loop *loop_lo = 0; |
|
|
2250 | \& struct ev_embed embed; |
|
|
2251 | \& |
|
|
2252 | \& // see if there is a chance of getting one that works |
|
|
2253 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2254 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2255 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2256 | \& : 0; |
|
|
2257 | \& |
|
|
2258 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2259 | \& if (loop_lo) |
|
|
2260 | \& { |
|
|
2261 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2262 | \& ev_embed_start (loop_hi, &embed); |
|
|
2263 | \& } |
|
|
2264 | \& else |
|
|
2265 | \& loop_lo = loop_hi; |
|
|
2266 | .Ve |
|
|
2267 | .PP |
|
|
2268 | Example: Check if kqueue is available but not recommended and create |
|
|
2269 | a kqueue backend for use with sockets (which usually work with any |
|
|
2270 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2271 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2272 | .PP |
|
|
2273 | .Vb 3 |
|
|
2274 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2275 | \& struct ev_loop *loop_socket = 0; |
|
|
2276 | \& struct ev_embed embed; |
|
|
2277 | \& |
|
|
2278 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2279 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2280 | \& { |
|
|
2281 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2282 | \& ev_embed_start (loop, &embed); |
|
|
2283 | \& } |
|
|
2284 | \& |
|
|
2285 | \& if (!loop_socket) |
|
|
2286 | \& loop_socket = loop; |
|
|
2287 | \& |
|
|
2288 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2289 | .Ve |
2113 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2290 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2114 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2291 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2115 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2292 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2116 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2293 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2117 | whoever is a good citizen cared to tell libev about it by calling |
2294 | whoever is a good citizen cared to tell libev about it by calling |
… | |
… | |
2126 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2303 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2127 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2304 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2128 | Initialises and configures the fork watcher \- it has no parameters of any |
2305 | Initialises and configures the fork watcher \- it has no parameters of any |
2129 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2306 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2130 | believe me. |
2307 | believe me. |
|
|
2308 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2309 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2310 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2311 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2312 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2313 | loops \- those are of course safe to use in different threads). |
|
|
2314 | .PP |
|
|
2315 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2316 | control, for example because it belongs to another thread. This is what |
|
|
2317 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2318 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2319 | safe. |
|
|
2320 | .PP |
|
|
2321 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2322 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2323 | (i.e. the number of callback invocations may be less than the number of |
|
|
2324 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2325 | .PP |
|
|
2326 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2327 | just the default loop. |
|
|
2328 | .PP |
|
|
2329 | \fIQueueing\fR |
|
|
2330 | .IX Subsection "Queueing" |
|
|
2331 | .PP |
|
|
2332 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2333 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2334 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2335 | need elaborate support such as pthreads. |
|
|
2336 | .PP |
|
|
2337 | That means that if you want to queue data, you have to provide your own |
|
|
2338 | queue. But at least I can tell you would implement locking around your |
|
|
2339 | queue: |
|
|
2340 | .IP "queueing from a signal handler context" 4 |
|
|
2341 | .IX Item "queueing from a signal handler context" |
|
|
2342 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2343 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2344 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2345 | .Sp |
|
|
2346 | .Vb 1 |
|
|
2347 | \& static ev_async mysig; |
|
|
2348 | \& |
|
|
2349 | \& static void |
|
|
2350 | \& sigusr1_handler (void) |
|
|
2351 | \& { |
|
|
2352 | \& sometype data; |
|
|
2353 | \& |
|
|
2354 | \& // no locking etc. |
|
|
2355 | \& queue_put (data); |
|
|
2356 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2357 | \& } |
|
|
2358 | \& |
|
|
2359 | \& static void |
|
|
2360 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2361 | \& { |
|
|
2362 | \& sometype data; |
|
|
2363 | \& sigset_t block, prev; |
|
|
2364 | \& |
|
|
2365 | \& sigemptyset (&block); |
|
|
2366 | \& sigaddset (&block, SIGUSR1); |
|
|
2367 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2368 | \& |
|
|
2369 | \& while (queue_get (&data)) |
|
|
2370 | \& process (data); |
|
|
2371 | \& |
|
|
2372 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2373 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2374 | \& } |
|
|
2375 | .Ve |
|
|
2376 | .Sp |
|
|
2377 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2378 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2379 | either...). |
|
|
2380 | .IP "queueing from a thread context" 4 |
|
|
2381 | .IX Item "queueing from a thread context" |
|
|
2382 | The strategy for threads is different, as you cannot (easily) block |
|
|
2383 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2384 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2385 | .Sp |
|
|
2386 | .Vb 2 |
|
|
2387 | \& static ev_async mysig; |
|
|
2388 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2389 | \& |
|
|
2390 | \& static void |
|
|
2391 | \& otherthread (void) |
|
|
2392 | \& { |
|
|
2393 | \& // only need to lock the actual queueing operation |
|
|
2394 | \& pthread_mutex_lock (&mymutex); |
|
|
2395 | \& queue_put (data); |
|
|
2396 | \& pthread_mutex_unlock (&mymutex); |
|
|
2397 | \& |
|
|
2398 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2399 | \& } |
|
|
2400 | \& |
|
|
2401 | \& static void |
|
|
2402 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2403 | \& { |
|
|
2404 | \& pthread_mutex_lock (&mymutex); |
|
|
2405 | \& |
|
|
2406 | \& while (queue_get (&data)) |
|
|
2407 | \& process (data); |
|
|
2408 | \& |
|
|
2409 | \& pthread_mutex_unlock (&mymutex); |
|
|
2410 | \& } |
|
|
2411 | .Ve |
|
|
2412 | .PP |
|
|
2413 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2414 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2415 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2416 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2417 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2418 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2419 | believe me. |
|
|
2420 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2421 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2422 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2423 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2424 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2425 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2426 | section below on what exactly this means). |
|
|
2427 | .Sp |
|
|
2428 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2429 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2430 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2431 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2432 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2433 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2434 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2435 | event loop. |
|
|
2436 | .Sp |
|
|
2437 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2438 | the loop iterates next and checks for the watcher to have become active, |
|
|
2439 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2440 | quickly check wether invoking the loop might be a good idea. |
|
|
2441 | .Sp |
|
|
2442 | Not that this does \fInot\fR check wether the watcher itself is pending, only |
|
|
2443 | wether it has been requested to make this watcher pending. |
2131 | .SH "OTHER FUNCTIONS" |
2444 | .SH "OTHER FUNCTIONS" |
2132 | .IX Header "OTHER FUNCTIONS" |
2445 | .IX Header "OTHER FUNCTIONS" |
2133 | There are some other functions of possible interest. Described. Here. Now. |
2446 | There are some other functions of possible interest. Described. Here. Now. |
2134 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2447 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2135 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2448 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2159 | \& if (revents & EV_TIMEOUT) |
2472 | \& if (revents & EV_TIMEOUT) |
2160 | \& /* doh, nothing entered */; |
2473 | \& /* doh, nothing entered */; |
2161 | \& else if (revents & EV_READ) |
2474 | \& else if (revents & EV_READ) |
2162 | \& /* stdin might have data for us, joy! */; |
2475 | \& /* stdin might have data for us, joy! */; |
2163 | \& } |
2476 | \& } |
2164 | .Ve |
2477 | \& |
2165 | .Sp |
|
|
2166 | .Vb 1 |
|
|
2167 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2478 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2168 | .Ve |
2479 | .Ve |
2169 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2480 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2170 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2481 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2171 | Feeds the given event set into the event loop, as if the specified event |
2482 | Feeds the given event set into the event loop, as if the specified event |
… | |
… | |
2181 | loop!). |
2492 | loop!). |
2182 | .SH "LIBEVENT EMULATION" |
2493 | .SH "LIBEVENT EMULATION" |
2183 | .IX Header "LIBEVENT EMULATION" |
2494 | .IX Header "LIBEVENT EMULATION" |
2184 | Libev offers a compatibility emulation layer for libevent. It cannot |
2495 | Libev offers a compatibility emulation layer for libevent. It cannot |
2185 | emulate the internals of libevent, so here are some usage hints: |
2496 | emulate the internals of libevent, so here are some usage hints: |
|
|
2497 | .IP "\(bu" 4 |
2186 | .IP "* Use it by including <event.h>, as usual." 4 |
2498 | Use it by including <event.h>, as usual. |
2187 | .IX Item "Use it by including <event.h>, as usual." |
2499 | .IP "\(bu" 4 |
2188 | .PD 0 |
2500 | The following members are fully supported: ev_base, ev_callback, |
2189 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2501 | ev_arg, ev_fd, ev_res, ev_events. |
2190 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2502 | .IP "\(bu" 4 |
2191 | .IP "* Avoid using ev_flags and the EVLIST_*\-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private \s-1API\s0)." 4 |
2503 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
2192 | .IX Item "Avoid using ev_flags and the EVLIST_*-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private API)." |
2504 | maintained by libev, it does not work exactly the same way as in libevent (consider |
2193 | .IP "* Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." 4 |
2505 | it a private \s-1API\s0). |
2194 | .IX Item "Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." |
2506 | .IP "\(bu" 4 |
|
|
2507 | Priorities are not currently supported. Initialising priorities |
|
|
2508 | will fail and all watchers will have the same priority, even though there |
|
|
2509 | is an ev_pri field. |
|
|
2510 | .IP "\(bu" 4 |
|
|
2511 | In libevent, the last base created gets the signals, in libev, the |
|
|
2512 | first base created (== the default loop) gets the signals. |
|
|
2513 | .IP "\(bu" 4 |
2195 | .IP "* Other members are not supported." 4 |
2514 | Other members are not supported. |
2196 | .IX Item "Other members are not supported." |
2515 | .IP "\(bu" 4 |
2197 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2516 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
2198 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2517 | to use the libev header file and library. |
2199 | .PD |
|
|
2200 | .SH "\*(C+ SUPPORT" |
2518 | .SH "\*(C+ SUPPORT" |
2201 | .IX Header " SUPPORT" |
2519 | .IX Header " SUPPORT" |
2202 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2520 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2203 | you to use some convinience methods to start/stop watchers and also change |
2521 | you to use some convinience methods to start/stop watchers and also change |
2204 | the callback model to a model using method callbacks on objects. |
2522 | the callback model to a model using method callbacks on objects. |
… | |
… | |
2284 | .Vb 4 |
2602 | .Vb 4 |
2285 | \& struct myclass |
2603 | \& struct myclass |
2286 | \& { |
2604 | \& { |
2287 | \& void io_cb (ev::io &w, int revents) { } |
2605 | \& void io_cb (ev::io &w, int revents) { } |
2288 | \& } |
2606 | \& } |
2289 | .Ve |
2607 | \& |
2290 | .Sp |
|
|
2291 | .Vb 3 |
|
|
2292 | \& myclass obj; |
2608 | \& myclass obj; |
2293 | \& ev::io iow; |
2609 | \& ev::io iow; |
2294 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
2610 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
2295 | .Ve |
2611 | .Ve |
2296 | .IP "w\->set<function> (void *data = 0)" 4 |
2612 | .IP "w\->set<function> (void *data = 0)" 4 |
… | |
… | |
2347 | the constructor. |
2663 | the constructor. |
2348 | .PP |
2664 | .PP |
2349 | .Vb 4 |
2665 | .Vb 4 |
2350 | \& class myclass |
2666 | \& class myclass |
2351 | \& { |
2667 | \& { |
2352 | \& ev_io io; void io_cb (ev::io &w, int revents); |
2668 | \& ev::io io; void io_cb (ev::io &w, int revents); |
2353 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
2669 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
2354 | .Ve |
2670 | \& |
2355 | .PP |
|
|
2356 | .Vb 2 |
|
|
2357 | \& myclass (); |
2671 | \& myclass (int fd) |
2358 | \& } |
|
|
2359 | .Ve |
|
|
2360 | .PP |
|
|
2361 | .Vb 4 |
|
|
2362 | \& myclass::myclass (int fd) |
|
|
2363 | \& { |
2672 | \& { |
2364 | \& io .set <myclass, &myclass::io_cb > (this); |
2673 | \& io .set <myclass, &myclass::io_cb > (this); |
2365 | \& idle.set <myclass, &myclass::idle_cb> (this); |
2674 | \& idle.set <myclass, &myclass::idle_cb> (this); |
2366 | .Ve |
2675 | \& |
2367 | .PP |
|
|
2368 | .Vb 2 |
|
|
2369 | \& io.start (fd, ev::READ); |
2676 | \& io.start (fd, ev::READ); |
|
|
2677 | \& } |
2370 | \& } |
2678 | \& }; |
2371 | .Ve |
2679 | .Ve |
|
|
2680 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2681 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2682 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2683 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2684 | any interesting language binding in addition to the ones listed here, drop |
|
|
2685 | me a note. |
|
|
2686 | .IP "Perl" 4 |
|
|
2687 | .IX Item "Perl" |
|
|
2688 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2689 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2690 | there are additional modules that implement libev-compatible interfaces |
|
|
2691 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2692 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2693 | .Sp |
|
|
2694 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2695 | <http://software.schmorp.de/pkg/EV>. |
|
|
2696 | .IP "Ruby" 4 |
|
|
2697 | .IX Item "Ruby" |
|
|
2698 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2699 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2700 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2701 | <http://rev.rubyforge.org/>. |
|
|
2702 | .IP "D" 4 |
|
|
2703 | .IX Item "D" |
|
|
2704 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2705 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
2372 | .SH "MACRO MAGIC" |
2706 | .SH "MACRO MAGIC" |
2373 | .IX Header "MACRO MAGIC" |
2707 | .IX Header "MACRO MAGIC" |
2374 | Libev can be compiled with a variety of options, the most fundamantal |
2708 | Libev can be compiled with a variety of options, the most fundamantal |
2375 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
2709 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
2376 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
2710 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
2400 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2734 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2401 | .Sp |
2735 | .Sp |
2402 | .Vb 2 |
2736 | .Vb 2 |
2403 | \& // this is how ev_unref is being declared |
2737 | \& // this is how ev_unref is being declared |
2404 | \& static void ev_unref (EV_P); |
2738 | \& static void ev_unref (EV_P); |
2405 | .Ve |
2739 | \& |
2406 | .Sp |
|
|
2407 | .Vb 2 |
|
|
2408 | \& // this is how you can declare your typical callback |
2740 | \& // this is how you can declare your typical callback |
2409 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2741 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2410 | .Ve |
2742 | .Ve |
2411 | .Sp |
2743 | .Sp |
2412 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
2744 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
… | |
… | |
2414 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
2746 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
2415 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
2747 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
2416 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
2748 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
2417 | Similar to the other two macros, this gives you the value of the default |
2749 | Similar to the other two macros, this gives you the value of the default |
2418 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
2750 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2751 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
2752 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
2753 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
2754 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
2755 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
2756 | is undefined when the default loop has not been initialised by a previous |
|
|
2757 | execution of \f(CW\*(C`EV_DEFAULT\*(C'\fR, \f(CW\*(C`EV_DEFAULT_\*(C'\fR or \f(CW\*(C`ev_default_init (...)\*(C'\fR. |
|
|
2758 | .Sp |
|
|
2759 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
2760 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
2419 | .PP |
2761 | .PP |
2420 | Example: Declare and initialise a check watcher, utilising the above |
2762 | Example: Declare and initialise a check watcher, utilising the above |
2421 | macros so it will work regardless of whether multiple loops are supported |
2763 | macros so it will work regardless of whether multiple loops are supported |
2422 | or not. |
2764 | or not. |
2423 | .PP |
2765 | .PP |
… | |
… | |
2425 | \& static void |
2767 | \& static void |
2426 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2768 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2427 | \& { |
2769 | \& { |
2428 | \& ev_check_stop (EV_A_ w); |
2770 | \& ev_check_stop (EV_A_ w); |
2429 | \& } |
2771 | \& } |
2430 | .Ve |
2772 | \& |
2431 | .PP |
|
|
2432 | .Vb 4 |
|
|
2433 | \& ev_check check; |
2773 | \& ev_check check; |
2434 | \& ev_check_init (&check, check_cb); |
2774 | \& ev_check_init (&check, check_cb); |
2435 | \& ev_check_start (EV_DEFAULT_ &check); |
2775 | \& ev_check_start (EV_DEFAULT_ &check); |
2436 | \& ev_loop (EV_DEFAULT_ 0); |
2776 | \& ev_loop (EV_DEFAULT_ 0); |
2437 | .Ve |
2777 | .Ve |
2438 | .SH "EMBEDDING" |
2778 | .SH "EMBEDDING" |
2439 | .IX Header "EMBEDDING" |
2779 | .IX Header "EMBEDDING" |
2440 | Libev can (and often is) directly embedded into host |
2780 | Libev can (and often is) directly embedded into host |
2441 | applications. Examples of applications that embed it include the Deliantra |
2781 | applications. Examples of applications that embed it include the Deliantra |
2442 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2782 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2443 | and rxvt\-unicode. |
2783 | and rxvt-unicode. |
2444 | .PP |
2784 | .PP |
2445 | The goal is to enable you to just copy the necessary files into your |
2785 | The goal is to enable you to just copy the necessary files into your |
2446 | source directory without having to change even a single line in them, so |
2786 | source directory without having to change even a single line in them, so |
2447 | you can easily upgrade by simply copying (or having a checked-out copy of |
2787 | you can easily upgrade by simply copying (or having a checked-out copy of |
2448 | libev somewhere in your source tree). |
2788 | libev somewhere in your source tree). |
… | |
… | |
2483 | .Vb 4 |
2823 | .Vb 4 |
2484 | \& ev.h |
2824 | \& ev.h |
2485 | \& ev.c |
2825 | \& ev.c |
2486 | \& ev_vars.h |
2826 | \& ev_vars.h |
2487 | \& ev_wrap.h |
2827 | \& ev_wrap.h |
2488 | .Ve |
2828 | \& |
2489 | .PP |
|
|
2490 | .Vb 1 |
|
|
2491 | \& ev_win32.c required on win32 platforms only |
2829 | \& ev_win32.c required on win32 platforms only |
2492 | .Ve |
2830 | \& |
2493 | .PP |
|
|
2494 | .Vb 5 |
|
|
2495 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2831 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2496 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2832 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2497 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2833 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2498 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2834 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2499 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2835 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
… | |
… | |
2539 | .Vb 1 |
2875 | .Vb 1 |
2540 | \& libev.m4 |
2876 | \& libev.m4 |
2541 | .Ve |
2877 | .Ve |
2542 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2878 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2543 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2879 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2544 | Libev can be configured via a variety of preprocessor symbols you have to define |
2880 | Libev can be configured via a variety of preprocessor symbols you have to |
2545 | before including any of its files. The default is not to build for multiplicity |
2881 | define before including any of its files. The default in the absense of |
2546 | and only include the select backend. |
2882 | autoconf is noted for every option. |
2547 | .IP "\s-1EV_STANDALONE\s0" 4 |
2883 | .IP "\s-1EV_STANDALONE\s0" 4 |
2548 | .IX Item "EV_STANDALONE" |
2884 | .IX Item "EV_STANDALONE" |
2549 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2885 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2550 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2886 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2551 | implementations for some libevent functions (such as logging, which is not |
2887 | implementations for some libevent functions (such as logging, which is not |
… | |
… | |
2570 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2906 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2571 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
2907 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
2572 | .IX Item "EV_USE_NANOSLEEP" |
2908 | .IX Item "EV_USE_NANOSLEEP" |
2573 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
2909 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
2574 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
2910 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
2911 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
2912 | .IX Item "EV_USE_EVENTFD" |
|
|
2913 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
2914 | available and will probe for kernel support at runtime. This will improve |
|
|
2915 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
2916 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2917 | 2.7 or newer, otherwise disabled. |
2575 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2918 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2576 | .IX Item "EV_USE_SELECT" |
2919 | .IX Item "EV_USE_SELECT" |
2577 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2920 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2578 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2921 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2579 | other method takes over, select will be it. Otherwise the select backend |
2922 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2594 | wants osf handles on win32 (this is the case when the select to |
2937 | wants osf handles on win32 (this is the case when the select to |
2595 | be used is the winsock select). This means that it will call |
2938 | be used is the winsock select). This means that it will call |
2596 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2939 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2597 | it is assumed that all these functions actually work on fds, even |
2940 | it is assumed that all these functions actually work on fds, even |
2598 | on win32. Should not be defined on non\-win32 platforms. |
2941 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2942 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2943 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2944 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2945 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2946 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2947 | correct. In some cases, programs use their own file descriptor management, |
|
|
2948 | in which case they can provide this function to map fds to socket handles. |
2599 | .IP "\s-1EV_USE_POLL\s0" 4 |
2949 | .IP "\s-1EV_USE_POLL\s0" 4 |
2600 | .IX Item "EV_USE_POLL" |
2950 | .IX Item "EV_USE_POLL" |
2601 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2951 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2602 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2952 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2603 | takes precedence over select. |
2953 | takes precedence over select. |
2604 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2954 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2605 | .IX Item "EV_USE_EPOLL" |
2955 | .IX Item "EV_USE_EPOLL" |
2606 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2956 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2607 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2957 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2608 | otherwise another method will be used as fallback. This is the |
2958 | otherwise another method will be used as fallback. This is the preferred |
2609 | preferred backend for GNU/Linux systems. |
2959 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2960 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2610 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2961 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2611 | .IX Item "EV_USE_KQUEUE" |
2962 | .IX Item "EV_USE_KQUEUE" |
2612 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2963 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2613 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2964 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2614 | otherwise another method will be used as fallback. This is the preferred |
2965 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
2629 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2980 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2630 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2981 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2631 | .IX Item "EV_USE_INOTIFY" |
2982 | .IX Item "EV_USE_INOTIFY" |
2632 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2983 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2633 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2984 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2634 | be detected at runtime. |
2985 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2986 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2987 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
2988 | .IX Item "EV_ATOMIC_T" |
|
|
2989 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
2990 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2991 | type is easily found in the C language, so you can provide your own type |
|
|
2992 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
2993 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
2994 | .Sp |
|
|
2995 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
2996 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2635 | .IP "\s-1EV_H\s0" 4 |
2997 | .IP "\s-1EV_H\s0" 4 |
2636 | .IX Item "EV_H" |
2998 | .IX Item "EV_H" |
2637 | The name of the \fIev.h\fR header file used to include it. The default if |
2999 | The name of the \fIev.h\fR header file used to include it. The default if |
2638 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3000 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2639 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3001 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2640 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3002 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2641 | .IX Item "EV_CONFIG_H" |
3003 | .IX Item "EV_CONFIG_H" |
2642 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3004 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2643 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3005 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2644 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3006 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2645 | .IP "\s-1EV_EVENT_H\s0" 4 |
3007 | .IP "\s-1EV_EVENT_H\s0" 4 |
2646 | .IX Item "EV_EVENT_H" |
3008 | .IX Item "EV_EVENT_H" |
2647 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3009 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2648 | of how the \fIevent.h\fR header can be found. |
3010 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2649 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3011 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2650 | .IX Item "EV_PROTOTYPES" |
3012 | .IX Item "EV_PROTOTYPES" |
2651 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3013 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2652 | prototypes, but still define all the structs and other symbols. This is |
3014 | prototypes, but still define all the structs and other symbols. This is |
2653 | occasionally useful if you want to provide your own wrapper functions |
3015 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2697 | defined to be \f(CW0\fR, then they are not. |
3059 | defined to be \f(CW0\fR, then they are not. |
2698 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3060 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2699 | .IX Item "EV_FORK_ENABLE" |
3061 | .IX Item "EV_FORK_ENABLE" |
2700 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3062 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2701 | defined to be \f(CW0\fR, then they are not. |
3063 | defined to be \f(CW0\fR, then they are not. |
|
|
3064 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3065 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3066 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3067 | defined to be \f(CW0\fR, then they are not. |
2702 | .IP "\s-1EV_MINIMAL\s0" 4 |
3068 | .IP "\s-1EV_MINIMAL\s0" 4 |
2703 | .IX Item "EV_MINIMAL" |
3069 | .IX Item "EV_MINIMAL" |
2704 | If you need to shave off some kilobytes of code at the expense of some |
3070 | If you need to shave off some kilobytes of code at the expense of some |
2705 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3071 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
2706 | some inlining decisions, saves roughly 30% codesize of amd64. |
3072 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
|
|
3073 | much smaller 2\-heap for timer management over the default 4\-heap. |
2707 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3074 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
2708 | .IX Item "EV_PID_HASHSIZE" |
3075 | .IX Item "EV_PID_HASHSIZE" |
2709 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3076 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
2710 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3077 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2711 | than enough. If you need to manage thousands of children you might want to |
3078 | than enough. If you need to manage thousands of children you might want to |
2712 | increase this value (\fImust\fR be a power of two). |
3079 | increase this value (\fImust\fR be a power of two). |
2713 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3080 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
2714 | .IX Item "EV_INOTIFY_HASHSIZE" |
3081 | .IX Item "EV_INOTIFY_HASHSIZE" |
2715 | \&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by |
3082 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
2716 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
3083 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
2717 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
3084 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
2718 | watchers you might want to increase this value (\fImust\fR be a power of |
3085 | watchers you might want to increase this value (\fImust\fR be a power of |
2719 | two). |
3086 | two). |
|
|
3087 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3088 | .IX Item "EV_USE_4HEAP" |
|
|
3089 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3090 | timer and periodics heap, libev uses a 4\-heap when this symbol is defined |
|
|
3091 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has a |
|
|
3092 | noticable after performance with many (thousands) of watchers. |
|
|
3093 | .Sp |
|
|
3094 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3095 | (disabled). |
|
|
3096 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3097 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3098 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3099 | timer and periodics heap, libev can cache the timestamp (\fIat\fR) within |
|
|
3100 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3101 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3102 | but avoids random read accesses on heap changes. This noticably improves |
|
|
3103 | performance noticably with with many (hundreds) of watchers. |
|
|
3104 | .Sp |
|
|
3105 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3106 | (disabled). |
2720 | .IP "\s-1EV_COMMON\s0" 4 |
3107 | .IP "\s-1EV_COMMON\s0" 4 |
2721 | .IX Item "EV_COMMON" |
3108 | .IX Item "EV_COMMON" |
2722 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3109 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
2723 | this macro to a something else you can include more and other types of |
3110 | this macro to a something else you can include more and other types of |
2724 | members. You have to define it each time you include one of the files, |
3111 | members. You have to define it each time you include one of the files, |
… | |
… | |
2748 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3135 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
2749 | .IX Subsection "EXPORTED API SYMBOLS" |
3136 | .IX Subsection "EXPORTED API SYMBOLS" |
2750 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
3137 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
2751 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3138 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
2752 | all public symbols, one per line: |
3139 | all public symbols, one per line: |
2753 | .Sp |
3140 | .PP |
2754 | .Vb 2 |
3141 | .Vb 2 |
2755 | \& Symbols.ev for libev proper |
3142 | \& Symbols.ev for libev proper |
2756 | \& Symbols.event for the libevent emulation |
3143 | \& Symbols.event for the libevent emulation |
2757 | .Ve |
3144 | .Ve |
2758 | .Sp |
3145 | .PP |
2759 | This can also be used to rename all public symbols to avoid clashes with |
3146 | This can also be used to rename all public symbols to avoid clashes with |
2760 | multiple versions of libev linked together (which is obviously bad in |
3147 | multiple versions of libev linked together (which is obviously bad in |
2761 | itself, but sometimes it is inconvinient to avoid this). |
3148 | itself, but sometimes it is inconvinient to avoid this). |
2762 | .Sp |
3149 | .PP |
2763 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
3150 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
2764 | include before including \fIev.h\fR: |
3151 | include before including \fIev.h\fR: |
2765 | .Sp |
3152 | .PP |
2766 | .Vb 1 |
3153 | .Vb 1 |
2767 | \& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
3154 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
2768 | .Ve |
3155 | .Ve |
2769 | .Sp |
3156 | .PP |
2770 | This would create a file \fIwrap.h\fR which essentially looks like this: |
3157 | This would create a file \fIwrap.h\fR which essentially looks like this: |
2771 | .Sp |
3158 | .PP |
2772 | .Vb 4 |
3159 | .Vb 4 |
2773 | \& #define ev_backend myprefix_ev_backend |
3160 | \& #define ev_backend myprefix_ev_backend |
2774 | \& #define ev_check_start myprefix_ev_check_start |
3161 | \& #define ev_check_start myprefix_ev_check_start |
2775 | \& #define ev_check_stop myprefix_ev_check_stop |
3162 | \& #define ev_check_stop myprefix_ev_check_stop |
2776 | \& ... |
3163 | \& ... |
… | |
… | |
2782 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3169 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2783 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3170 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2784 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3171 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2785 | will be compiled. It is pretty complex because it provides its own header |
3172 | will be compiled. It is pretty complex because it provides its own header |
2786 | file. |
3173 | file. |
2787 | .Sp |
3174 | .PP |
2788 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3175 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2789 | that everybody includes and which overrides some configure choices: |
3176 | that everybody includes and which overrides some configure choices: |
2790 | .Sp |
3177 | .PP |
2791 | .Vb 9 |
3178 | .Vb 9 |
2792 | \& #define EV_MINIMAL 1 |
3179 | \& #define EV_MINIMAL 1 |
2793 | \& #define EV_USE_POLL 0 |
3180 | \& #define EV_USE_POLL 0 |
2794 | \& #define EV_MULTIPLICITY 0 |
3181 | \& #define EV_MULTIPLICITY 0 |
2795 | \& #define EV_PERIODIC_ENABLE 0 |
3182 | \& #define EV_PERIODIC_ENABLE 0 |
2796 | \& #define EV_STAT_ENABLE 0 |
3183 | \& #define EV_STAT_ENABLE 0 |
2797 | \& #define EV_FORK_ENABLE 0 |
3184 | \& #define EV_FORK_ENABLE 0 |
2798 | \& #define EV_CONFIG_H <config.h> |
3185 | \& #define EV_CONFIG_H <config.h> |
2799 | \& #define EV_MINPRI 0 |
3186 | \& #define EV_MINPRI 0 |
2800 | \& #define EV_MAXPRI 0 |
3187 | \& #define EV_MAXPRI 0 |
2801 | .Ve |
3188 | \& |
2802 | .Sp |
|
|
2803 | .Vb 1 |
|
|
2804 | \& #include "ev++.h" |
3189 | \& #include "ev++.h" |
2805 | .Ve |
3190 | .Ve |
2806 | .Sp |
3191 | .PP |
2807 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3192 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2808 | .Sp |
3193 | .PP |
2809 | .Vb 2 |
3194 | .Vb 2 |
2810 | \& #include "ev_cpp.h" |
3195 | \& #include "ev_cpp.h" |
2811 | \& #include "ev.c" |
3196 | \& #include "ev.c" |
2812 | .Ve |
3197 | .Ve |
|
|
3198 | .SH "THREADS AND COROUTINES" |
|
|
3199 | .IX Header "THREADS AND COROUTINES" |
|
|
3200 | .Sh "\s-1THREADS\s0" |
|
|
3201 | .IX Subsection "THREADS" |
|
|
3202 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3203 | means that you can use as many loops as you want in parallel, as long as |
|
|
3204 | only one thread ever calls into one libev function with the same loop |
|
|
3205 | parameter. |
|
|
3206 | .PP |
|
|
3207 | Or put differently: calls with different loop parameters can be done in |
|
|
3208 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3209 | done serially (but can be done from different threads, as long as only one |
|
|
3210 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3211 | per loop). |
|
|
3212 | .PP |
|
|
3213 | If you want to know which design is best for your problem, then I cannot |
|
|
3214 | help you but by giving some generic advice: |
|
|
3215 | .IP "\(bu" 4 |
|
|
3216 | most applications have a main thread: use the default libev loop |
|
|
3217 | in that thread, or create a seperate thread running only the default loop. |
|
|
3218 | .Sp |
|
|
3219 | This helps integrating other libraries or software modules that use libev |
|
|
3220 | themselves and don't care/know about threading. |
|
|
3221 | .IP "\(bu" 4 |
|
|
3222 | one loop per thread is usually a good model. |
|
|
3223 | .Sp |
|
|
3224 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3225 | exists, but it is always a good start. |
|
|
3226 | .IP "\(bu" 4 |
|
|
3227 | other models exist, such as the leader/follower pattern, where one |
|
|
3228 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3229 | .Sp |
|
|
3230 | Chosing a model is hard \- look around, learn, know that usually you cna do |
|
|
3231 | better than you currently do :\-) |
|
|
3232 | .IP "\(bu" 4 |
|
|
3233 | often you need to talk to some other thread which blocks in the |
|
|
3234 | event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other |
|
|
3235 | threads safely (or from signal contexts...). |
|
|
3236 | .Sh "\s-1COROUTINES\s0" |
|
|
3237 | .IX Subsection "COROUTINES" |
|
|
3238 | Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3239 | libev fully supports nesting calls to it's functions from different |
|
|
3240 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3241 | different coroutines and switch freely between both coroutines running the |
|
|
3242 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3243 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3244 | .PP |
|
|
3245 | Care has been invested into making sure that libev does not keep local |
|
|
3246 | state inside \f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow coroutine |
|
|
3247 | switches. |
2813 | .SH "COMPLEXITIES" |
3248 | .SH "COMPLEXITIES" |
2814 | .IX Header "COMPLEXITIES" |
3249 | .IX Header "COMPLEXITIES" |
2815 | In this section the complexities of (many of) the algorithms used inside |
3250 | In this section the complexities of (many of) the algorithms used inside |
2816 | libev will be explained. For complexity discussions about backends see the |
3251 | libev will be explained. For complexity discussions about backends see the |
2817 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
3252 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2818 | .Sp |
3253 | .PP |
2819 | All of the following are about amortised time: If an array needs to be |
3254 | All of the following are about amortised time: If an array needs to be |
2820 | extended, libev needs to realloc and move the whole array, but this |
3255 | extended, libev needs to realloc and move the whole array, but this |
2821 | happens asymptotically never with higher number of elements, so O(1) might |
3256 | happens asymptotically never with higher number of elements, so O(1) might |
2822 | mean it might do a lengthy realloc operation in rare cases, but on average |
3257 | mean it might do a lengthy realloc operation in rare cases, but on average |
2823 | it is much faster and asymptotically approaches constant time. |
3258 | it is much faster and asymptotically approaches constant time. |
2824 | .RS 4 |
|
|
2825 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
3259 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2826 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
3260 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
2827 | This means that, when you have a watcher that triggers in one hour and |
3261 | This means that, when you have a watcher that triggers in one hour and |
2828 | there are 100 watchers that would trigger before that then inserting will |
3262 | there are 100 watchers that would trigger before that then inserting will |
2829 | have to skip those 100 watchers. |
3263 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
2830 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
3264 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
2831 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
3265 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
2832 | That means that for changing a timer costs less than removing/adding them |
3266 | That means that changing a timer costs less than removing/adding them |
2833 | as only the relative motion in the event queue has to be paid for. |
3267 | as only the relative motion in the event queue has to be paid for. |
2834 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
3268 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
2835 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
3269 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
2836 | These just add the watcher into an array or at the head of a list. |
3270 | These just add the watcher into an array or at the head of a list. |
|
|
3271 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
2837 | =item Stopping check/prepare/idle watchers: O(1) |
3272 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
|
|
3273 | .PD 0 |
2838 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
3274 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2839 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
3275 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3276 | .PD |
2840 | These watchers are stored in lists then need to be walked to find the |
3277 | These watchers are stored in lists then need to be walked to find the |
2841 | correct watcher to remove. The lists are usually short (you don't usually |
3278 | correct watcher to remove. The lists are usually short (you don't usually |
2842 | have many watchers waiting for the same fd or signal). |
3279 | have many watchers waiting for the same fd or signal). |
2843 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
3280 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2844 | .IX Item "Finding the next timer per loop iteration: O(1)" |
3281 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
2845 | .PD 0 |
3282 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
3283 | fixed position in the storage array. |
2846 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
3284 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2847 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
3285 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2848 | .PD |
|
|
2849 | A change means an I/O watcher gets started or stopped, which requires |
3286 | A change means an I/O watcher gets started or stopped, which requires |
2850 | libev to recalculate its status (and possibly tell the kernel). |
3287 | libev to recalculate its status (and possibly tell the kernel, depending |
2851 | .IP "Activating one watcher: O(1)" 4 |
3288 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2852 | .IX Item "Activating one watcher: O(1)" |
3289 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3290 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
2853 | .PD 0 |
3291 | .PD 0 |
2854 | .IP "Priority handling: O(number_of_priorities)" 4 |
3292 | .IP "Priority handling: O(number_of_priorities)" 4 |
2855 | .IX Item "Priority handling: O(number_of_priorities)" |
3293 | .IX Item "Priority handling: O(number_of_priorities)" |
2856 | .PD |
3294 | .PD |
2857 | Priorities are implemented by allocating some space for each |
3295 | Priorities are implemented by allocating some space for each |
2858 | priority. When doing priority-based operations, libev usually has to |
3296 | priority. When doing priority-based operations, libev usually has to |
2859 | linearly search all the priorities. |
3297 | linearly search all the priorities, but starting/stopping and activating |
2860 | .RE |
3298 | watchers becomes O(1) w.r.t. priority handling. |
2861 | .RS 4 |
3299 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3300 | .IX Item "Sending an ev_async: O(1)" |
|
|
3301 | .PD 0 |
|
|
3302 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3303 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3304 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3305 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3306 | .PD |
|
|
3307 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3308 | calls in the current loop iteration. Checking for async and signal events |
|
|
3309 | involves iterating over all running async watchers or all signal numbers. |
|
|
3310 | .SH "Win32 platform limitations and workarounds" |
|
|
3311 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3312 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3313 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3314 | model. Libev still offers limited functionality on this platform in |
|
|
3315 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3316 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3317 | e.g. cygwin. |
|
|
3318 | .PP |
|
|
3319 | Lifting these limitations would basically require the full |
|
|
3320 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3321 | things, then note that glib does exactly that for you in a very portable |
|
|
3322 | way (note also that glib is the slowest event library known to man). |
|
|
3323 | .PP |
|
|
3324 | There is no supported compilation method available on windows except |
|
|
3325 | embedding it into other applications. |
|
|
3326 | .PP |
|
|
3327 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3328 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3329 | is not recommended (and not reasonable). If your program needs to use |
|
|
3330 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3331 | different implementation for windows, as libev offers the \s-1POSIX\s0 readyness |
|
|
3332 | notification model, which cannot be implemented efficiently on windows |
|
|
3333 | (microsoft monopoly games). |
|
|
3334 | .IP "The winsocket select function" 4 |
|
|
3335 | .IX Item "The winsocket select function" |
|
|
3336 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires |
|
|
3337 | socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select |
|
|
3338 | very inefficient, and also requires a mapping from file descriptors |
|
|
3339 | to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, |
|
|
3340 | \&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor |
|
|
3341 | symbols for more info. |
|
|
3342 | .Sp |
|
|
3343 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3344 | libraries and raw winsocket select is: |
|
|
3345 | .Sp |
|
|
3346 | .Vb 2 |
|
|
3347 | \& #define EV_USE_SELECT 1 |
|
|
3348 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3349 | .Ve |
|
|
3350 | .Sp |
|
|
3351 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3352 | complexity in the O(nA\*^X) range when using win32. |
|
|
3353 | .IP "Limited number of file descriptors" 4 |
|
|
3354 | .IX Item "Limited number of file descriptors" |
|
|
3355 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3356 | .Sp |
|
|
3357 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3358 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
3359 | can only wait for \f(CW64\fR things at the same time internally; microsoft |
|
|
3360 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3361 | previous thread in each. Great). |
|
|
3362 | .Sp |
|
|
3363 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3364 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3365 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3366 | select emulation on windows). |
|
|
3367 | .Sp |
|
|
3368 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3369 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3370 | or something like this inside microsoft). You can increase this by calling |
|
|
3371 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3372 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3373 | libraries. |
|
|
3374 | .Sp |
|
|
3375 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3376 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3377 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3378 | calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
3379 | .SH "PORTABILITY REQUIREMENTS" |
|
|
3380 | .IX Header "PORTABILITY REQUIREMENTS" |
|
|
3381 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3382 | additional extensions: |
|
|
3383 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
3384 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
3385 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
3386 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
3387 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic w.r.t. accesses from different |
|
|
3388 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
3389 | believed to be sufficiently portable. |
|
|
3390 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
3391 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
3392 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
3393 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
|
|
3394 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
|
|
3395 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
|
|
3396 | thread\*(R" or will block signals process-wide, both behaviours would |
|
|
3397 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
|
|
3398 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
|
|
3399 | .Sp |
|
|
3400 | The most portable way to handle signals is to block signals in all threads |
|
|
3401 | except the initial one, and run the default loop in the initial thread as |
|
|
3402 | well. |
|
|
3403 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
|
|
3404 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
|
|
3405 | .IX Item "long must be large enough for common memory allocation sizes" |
|
|
3406 | To improve portability and simplify using libev, libev uses \f(CW\*(C`long\*(C'\fR |
|
|
3407 | internally instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On |
|
|
3408 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3409 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3410 | millions of watchers. |
|
|
3411 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
|
|
3412 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
|
|
3413 | .IX Item "double must hold a time value in seconds with enough accuracy" |
|
|
3414 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
|
|
3415 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3416 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3417 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
|
|
3418 | .PP |
|
|
3419 | If you know of other additional requirements drop me a note. |
2862 | .SH "AUTHOR" |
3420 | .SH "AUTHOR" |
2863 | .IX Header "AUTHOR" |
3421 | .IX Header "AUTHOR" |
2864 | Marc Lehmann <libev@schmorp.de>. |
3422 | Marc Lehmann <libev@schmorp.de>. |
|
|
3423 | .SH "POD ERRORS" |
|
|
3424 | .IX Header "POD ERRORS" |
|
|
3425 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3426 | .IP "Around line 3052:" 4 |
|
|
3427 | .IX Item "Around line 3052:" |
|
|
3428 | You forgot a '=back' before '=head2' |