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1 | .\" Automatically generated by Pod::Man 2.23 (Pod::Simple 3.14) |
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3 | .\" Standard preamble: |
4 | .\" ======================================================================== |
4 | .\" ======================================================================== |
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123 | .rm #[ #] #H #V #F C |
124 | .\" ======================================================================== |
124 | .\" ======================================================================== |
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125 | .\" |
126 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2009-07-27" "libev-3.8" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2012-04-19" "libev-4.11" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
129 | .\" way too many mistakes in technical documents. |
129 | .\" way too many mistakes in technical documents. |
130 | .if n .ad l |
130 | .if n .ad l |
131 | .nh |
131 | .nh |
132 | .SH "NAME" |
132 | .SH "NAME" |
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157 | \& puts ("stdin ready"); |
157 | \& puts ("stdin ready"); |
158 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& // for one\-shot events, one must manually stop the watcher |
159 | \& // with its corresponding stop function. |
159 | \& // with its corresponding stop function. |
160 | \& ev_io_stop (EV_A_ w); |
160 | \& ev_io_stop (EV_A_ w); |
161 | \& |
161 | \& |
162 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
162 | \& // this causes all nested ev_run\*(Aqs to stop iterating |
163 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
163 | \& ev_break (EV_A_ EVBREAK_ALL); |
164 | \& } |
164 | \& } |
165 | \& |
165 | \& |
166 | \& // another callback, this time for a time\-out |
166 | \& // another callback, this time for a time\-out |
167 | \& static void |
167 | \& static void |
168 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
168 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
169 | \& { |
169 | \& { |
170 | \& puts ("timeout"); |
170 | \& puts ("timeout"); |
171 | \& // this causes the innermost ev_loop to stop iterating |
171 | \& // this causes the innermost ev_run to stop iterating |
172 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
172 | \& ev_break (EV_A_ EVBREAK_ONE); |
173 | \& } |
173 | \& } |
174 | \& |
174 | \& |
175 | \& int |
175 | \& int |
176 | \& main (void) |
176 | \& main (void) |
177 | \& { |
177 | \& { |
178 | \& // use the default event loop unless you have special needs |
178 | \& // use the default event loop unless you have special needs |
179 | \& struct ev_loop *loop = ev_default_loop (0); |
179 | \& struct ev_loop *loop = EV_DEFAULT; |
180 | \& |
180 | \& |
181 | \& // initialise an io watcher, then start it |
181 | \& // initialise an io watcher, then start it |
182 | \& // this one will watch for stdin to become readable |
182 | \& // this one will watch for stdin to become readable |
183 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
183 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
184 | \& ev_io_start (loop, &stdin_watcher); |
184 | \& ev_io_start (loop, &stdin_watcher); |
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187 | \& // simple non\-repeating 5.5 second timeout |
187 | \& // simple non\-repeating 5.5 second timeout |
188 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
188 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
189 | \& ev_timer_start (loop, &timeout_watcher); |
189 | \& ev_timer_start (loop, &timeout_watcher); |
190 | \& |
190 | \& |
191 | \& // now wait for events to arrive |
191 | \& // now wait for events to arrive |
192 | \& ev_loop (loop, 0); |
192 | \& ev_run (loop, 0); |
193 | \& |
193 | \& |
194 | \& // unloop was called, so exit |
194 | \& // break was called, so exit |
195 | \& return 0; |
195 | \& return 0; |
196 | \& } |
196 | \& } |
197 | .Ve |
197 | .Ve |
198 | .SH "ABOUT THIS DOCUMENT" |
198 | .SH "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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206 | While this document tries to be as complete as possible in documenting |
206 | While this document tries to be as complete as possible in documenting |
207 | libev, its usage and the rationale behind its design, it is not a tutorial |
207 | libev, its usage and the rationale behind its design, it is not a tutorial |
208 | on event-based programming, nor will it introduce event-based programming |
208 | on event-based programming, nor will it introduce event-based programming |
209 | with libev. |
209 | with libev. |
210 | .PP |
210 | .PP |
211 | Familarity with event based programming techniques in general is assumed |
211 | Familiarity with event based programming techniques in general is assumed |
212 | throughout this document. |
212 | throughout this document. |
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213 | .SH "WHAT TO READ WHEN IN A HURRY" |
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214 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
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215 | This manual tries to be very detailed, but unfortunately, this also makes |
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216 | it very long. If you just want to know the basics of libev, I suggest |
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217 | reading \*(L"\s-1ANATOMY\s0 \s-1OF\s0 A \s-1WATCHER\s0\*(R", then the \*(L"\s-1EXAMPLE\s0 \s-1PROGRAM\s0\*(R" above and |
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218 | look up the missing functions in \*(L"\s-1GLOBAL\s0 \s-1FUNCTIONS\s0\*(R" and the \f(CW\*(C`ev_io\*(C'\fR and |
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219 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". |
213 | .SH "ABOUT LIBEV" |
220 | .SH "ABOUT LIBEV" |
214 | .IX Header "ABOUT LIBEV" |
221 | .IX Header "ABOUT LIBEV" |
215 | Libev is an event loop: you register interest in certain events (such as a |
222 | Libev is an event loop: you register interest in certain events (such as a |
216 | file descriptor being readable or a timeout occurring), and it will manage |
223 | file descriptor being readable or a timeout occurring), and it will manage |
217 | these event sources and provide your program with events. |
224 | these event sources and provide your program with events. |
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237 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
244 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
238 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
245 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
239 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
240 | .PP |
247 | .PP |
241 | It also is quite fast (see this |
248 | It also is quite fast (see this |
242 | <benchmark> comparing it to libevent |
249 | benchmark <http://libev.schmorp.de/bench.html> comparing it to libevent |
243 | for example). |
250 | for example). |
244 | .SS "\s-1CONVENTIONS\s0" |
251 | .SS "\s-1CONVENTIONS\s0" |
245 | .IX Subsection "CONVENTIONS" |
252 | .IX Subsection "CONVENTIONS" |
246 | Libev is very configurable. In this manual the default (and most common) |
253 | Libev is very configurable. In this manual the default (and most common) |
247 | configuration will be described, which supports multiple event loops. For |
254 | configuration will be described, which supports multiple event loops. For |
248 | more info about various configuration options please have a look at |
255 | more info about various configuration options please have a look at |
249 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
250 | for multiple event loops, then all functions taking an initial argument of |
257 | for multiple event loops, then all functions taking an initial argument of |
251 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
252 | this argument. |
259 | this argument. |
253 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
260 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
254 | .IX Subsection "TIME REPRESENTATION" |
261 | .IX Subsection "TIME REPRESENTATION" |
255 | Libev represents time as a single floating point number, representing |
262 | Libev represents time as a single floating point number, representing |
256 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
257 | near the beginning of 1970, details are complicated, don't ask). This |
264 | somewhere near the beginning of 1970, details are complicated, don't |
258 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
265 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
259 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
266 | too. It usually aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do |
260 | on it, you should treat it as some floating point value. Unlike the name |
267 | any calculations on it, you should treat it as some floating point value. |
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268 | .PP |
261 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
269 | Unlike the name component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for |
262 | throughout libev. |
270 | time differences (e.g. delays) throughout libev. |
263 | .SH "ERROR HANDLING" |
271 | .SH "ERROR HANDLING" |
264 | .IX Header "ERROR HANDLING" |
272 | .IX Header "ERROR HANDLING" |
265 | Libev knows three classes of errors: operating system errors, usage errors |
273 | Libev knows three classes of errors: operating system errors, usage errors |
266 | and internal errors (bugs). |
274 | and internal errors (bugs). |
267 | .PP |
275 | .PP |
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285 | library in any way. |
293 | library in any way. |
286 | .IP "ev_tstamp ev_time ()" 4 |
294 | .IP "ev_tstamp ev_time ()" 4 |
287 | .IX Item "ev_tstamp ev_time ()" |
295 | .IX Item "ev_tstamp ev_time ()" |
288 | Returns the current time as libev would use it. Please note that the |
296 | Returns the current time as libev would use it. Please note that the |
289 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
290 | you actually want to know. |
298 | you actually want to know. Also interesting is the combination of |
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299 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
291 | .IP "ev_sleep (ev_tstamp interval)" 4 |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
292 | .IX Item "ev_sleep (ev_tstamp interval)" |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
293 | Sleep for the given interval: The current thread will be blocked until |
302 | Sleep for the given interval: The current thread will be blocked |
294 | either it is interrupted or the given time interval has passed. Basically |
303 | until either it is interrupted or the given time interval has |
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304 | passed (approximately \- it might return a bit earlier even if not |
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305 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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306 | .Sp |
295 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
307 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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308 | .Sp |
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309 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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310 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
296 | .IP "int ev_version_major ()" 4 |
311 | .IP "int ev_version_major ()" 4 |
297 | .IX Item "int ev_version_major ()" |
312 | .IX Item "int ev_version_major ()" |
298 | .PD 0 |
313 | .PD 0 |
299 | .IP "int ev_version_minor ()" 4 |
314 | .IP "int ev_version_minor ()" 4 |
300 | .IX Item "int ev_version_minor ()" |
315 | .IX Item "int ev_version_minor ()" |
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312 | as this indicates an incompatible change. Minor versions are usually |
327 | as this indicates an incompatible change. Minor versions are usually |
313 | compatible to older versions, so a larger minor version alone is usually |
328 | compatible to older versions, so a larger minor version alone is usually |
314 | not a problem. |
329 | not a problem. |
315 | .Sp |
330 | .Sp |
316 | Example: Make sure we haven't accidentally been linked against the wrong |
331 | Example: Make sure we haven't accidentally been linked against the wrong |
317 | version. |
332 | version (note, however, that this will not detect other \s-1ABI\s0 mismatches, |
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333 | such as \s-1LFS\s0 or reentrancy). |
318 | .Sp |
334 | .Sp |
319 | .Vb 3 |
335 | .Vb 3 |
320 | \& assert (("libev version mismatch", |
336 | \& assert (("libev version mismatch", |
321 | \& ev_version_major () == EV_VERSION_MAJOR |
337 | \& ev_version_major () == EV_VERSION_MAJOR |
322 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
338 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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335 | \& assert (("sorry, no epoll, no sex", |
351 | \& assert (("sorry, no epoll, no sex", |
336 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
352 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
337 | .Ve |
353 | .Ve |
338 | .IP "unsigned int ev_recommended_backends ()" 4 |
354 | .IP "unsigned int ev_recommended_backends ()" 4 |
339 | .IX Item "unsigned int ev_recommended_backends ()" |
355 | .IX Item "unsigned int ev_recommended_backends ()" |
340 | Return the set of all backends compiled into this binary of libev and also |
356 | Return the set of all backends compiled into this binary of libev and |
341 | recommended for this platform. This set is often smaller than the one |
357 | also recommended for this platform, meaning it will work for most file |
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358 | descriptor types. This set is often smaller than the one returned by |
342 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
359 | \&\f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on most BSDs |
343 | most BSDs and will not be auto-detected unless you explicitly request it |
360 | and will not be auto-detected unless you explicitly request it (assuming |
344 | (assuming you know what you are doing). This is the set of backends that |
361 | you know what you are doing). This is the set of backends that libev will |
345 | libev will probe for if you specify no backends explicitly. |
362 | probe for if you specify no backends explicitly. |
346 | .IP "unsigned int ev_embeddable_backends ()" 4 |
363 | .IP "unsigned int ev_embeddable_backends ()" 4 |
347 | .IX Item "unsigned int ev_embeddable_backends ()" |
364 | .IX Item "unsigned int ev_embeddable_backends ()" |
348 | Returns the set of backends that are embeddable in other event loops. This |
365 | Returns the set of backends that are embeddable in other event loops. This |
349 | is the theoretical, all-platform, value. To find which backends |
366 | value is platform-specific but can include backends not available on the |
350 | might be supported on the current system, you would need to look at |
367 | current system. To find which embeddable backends might be supported on |
351 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
368 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
352 | recommended ones. |
369 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
353 | .Sp |
370 | .Sp |
354 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
371 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
355 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
372 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
356 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
373 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
357 | Sets the allocation function to use (the prototype is similar \- the |
374 | Sets the allocation function to use (the prototype is similar \- the |
358 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
375 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
359 | used to allocate and free memory (no surprises here). If it returns zero |
376 | used to allocate and free memory (no surprises here). If it returns zero |
360 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
377 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
361 | or take some potentially destructive action. |
378 | or take some potentially destructive action. |
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387 | \& } |
404 | \& } |
388 | \& |
405 | \& |
389 | \& ... |
406 | \& ... |
390 | \& ev_set_allocator (persistent_realloc); |
407 | \& ev_set_allocator (persistent_realloc); |
391 | .Ve |
408 | .Ve |
392 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
409 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
393 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
410 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" |
394 | Set the callback function to call on a retryable system call error (such |
411 | Set the callback function to call on a retryable system call error (such |
395 | as failed select, poll, epoll_wait). The message is a printable string |
412 | as failed select, poll, epoll_wait). The message is a printable string |
396 | indicating the system call or subsystem causing the problem. If this |
413 | indicating the system call or subsystem causing the problem. If this |
397 | callback is set, then libev will expect it to remedy the situation, no |
414 | callback is set, then libev will expect it to remedy the situation, no |
398 | matter what, when it returns. That is, libev will generally retry the |
415 | matter what, when it returns. That is, libev will generally retry the |
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410 | \& } |
427 | \& } |
411 | \& |
428 | \& |
412 | \& ... |
429 | \& ... |
413 | \& ev_set_syserr_cb (fatal_error); |
430 | \& ev_set_syserr_cb (fatal_error); |
414 | .Ve |
431 | .Ve |
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432 | .IP "ev_feed_signal (int signum)" 4 |
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433 | .IX Item "ev_feed_signal (int signum)" |
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434 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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435 | safe to call this function at any time, from any context, including signal |
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436 | handlers or random threads. |
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437 | .Sp |
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438 | Its main use is to customise signal handling in your process, especially |
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439 | in the presence of threads. For example, you could block signals |
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440 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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441 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
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442 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
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443 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
415 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
444 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
416 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
445 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
417 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
446 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
418 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
447 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
419 | \&\fIfunction\fR). |
448 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
420 | .PP |
449 | .PP |
421 | The library knows two types of such loops, the \fIdefault\fR loop, which |
450 | The library knows two types of such loops, the \fIdefault\fR loop, which |
422 | supports signals and child events, and dynamically created loops which do |
451 | supports child process events, and dynamically created event loops which |
423 | not. |
452 | do not. |
424 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
453 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
425 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
454 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
426 | This will initialise the default event loop if it hasn't been initialised |
455 | This returns the \*(L"default\*(R" event loop object, which is what you should |
427 | yet and return it. If the default loop could not be initialised, returns |
456 | normally use when you just need \*(L"the event loop\*(R". Event loop objects and |
428 | false. If it already was initialised it simply returns it (and ignores the |
457 | the \f(CW\*(C`flags\*(C'\fR parameter are described in more detail in the entry for |
429 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
458 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. |
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459 | .Sp |
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460 | If the default loop is already initialised then this function simply |
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461 | returns it (and ignores the flags. If that is troubling you, check |
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462 | \&\f(CW\*(C`ev_backend ()\*(C'\fR afterwards). Otherwise it will create it with the given |
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463 | flags, which should almost always be \f(CW0\fR, unless the caller is also the |
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464 | one calling \f(CW\*(C`ev_run\*(C'\fR or otherwise qualifies as \*(L"the main program\*(R". |
430 | .Sp |
465 | .Sp |
431 | If you don't know what event loop to use, use the one returned from this |
466 | If you don't know what event loop to use, use the one returned from this |
432 | function. |
467 | function (or via the \f(CW\*(C`EV_DEFAULT\*(C'\fR macro). |
433 | .Sp |
468 | .Sp |
434 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
469 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
435 | from multiple threads, you have to lock (note also that this is unlikely, |
470 | from multiple threads, you have to employ some kind of mutex (note also |
436 | as loops cannot be shared easily between threads anyway). |
471 | that this case is unlikely, as loops cannot be shared easily between |
|
|
472 | threads anyway). |
437 | .Sp |
473 | .Sp |
438 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
474 | The default loop is the only loop that can handle \f(CW\*(C`ev_child\*(C'\fR watchers, |
439 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
475 | and to do this, it always registers a handler for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is |
440 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
476 | a problem for your application you can either create a dynamic loop with |
441 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
477 | \&\f(CW\*(C`ev_loop_new\*(C'\fR which doesn't do that, or you can simply overwrite the |
442 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
478 | \&\f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling \f(CW\*(C`ev_default_init\*(C'\fR. |
443 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
479 | .Sp |
|
|
480 | Example: This is the most typical usage. |
|
|
481 | .Sp |
|
|
482 | .Vb 2 |
|
|
483 | \& if (!ev_default_loop (0)) |
|
|
484 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
485 | .Ve |
|
|
486 | .Sp |
|
|
487 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
488 | environment settings to be taken into account: |
|
|
489 | .Sp |
|
|
490 | .Vb 1 |
|
|
491 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
492 | .Ve |
|
|
493 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
|
|
494 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
|
|
495 | This will create and initialise a new event loop object. If the loop |
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|
496 | could not be initialised, returns false. |
|
|
497 | .Sp |
|
|
498 | This function is thread-safe, and one common way to use libev with |
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|
499 | threads is indeed to create one loop per thread, and using the default |
|
|
500 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
444 | .Sp |
501 | .Sp |
445 | The flags argument can be used to specify special behaviour or specific |
502 | The flags argument can be used to specify special behaviour or specific |
446 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
503 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
447 | .Sp |
504 | .Sp |
448 | The following flags are supported: |
505 | The following flags are supported: |
… | |
… | |
462 | useful to try out specific backends to test their performance, or to work |
519 | useful to try out specific backends to test their performance, or to work |
463 | around bugs. |
520 | around bugs. |
464 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
521 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
465 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
522 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
466 | .IX Item "EVFLAG_FORKCHECK" |
523 | .IX Item "EVFLAG_FORKCHECK" |
467 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
524 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
468 | a fork, you can also make libev check for a fork in each iteration by |
525 | make libev check for a fork in each iteration by enabling this flag. |
469 | enabling this flag. |
|
|
470 | .Sp |
526 | .Sp |
471 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
527 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
472 | and thus this might slow down your event loop if you do a lot of loop |
528 | and thus this might slow down your event loop if you do a lot of loop |
473 | iterations and little real work, but is usually not noticeable (on my |
529 | iterations and little real work, but is usually not noticeable (on my |
474 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
530 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
… | |
… | |
483 | environment variable. |
539 | environment variable. |
484 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
540 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
485 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
541 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
486 | .IX Item "EVFLAG_NOINOTIFY" |
542 | .IX Item "EVFLAG_NOINOTIFY" |
487 | When this flag is specified, then libev will not attempt to use the |
543 | When this flag is specified, then libev will not attempt to use the |
488 | \&\fIinotify\fR \s-1API\s0 for it's \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
544 | \&\fIinotify\fR \s-1API\s0 for its \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
489 | testing, this flag can be useful to conserve inotify file descriptors, as |
545 | testing, this flag can be useful to conserve inotify file descriptors, as |
490 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
546 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
491 | .ie n .IP """EVFLAG_NOSIGNALFD""" 4 |
547 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
492 | .el .IP "\f(CWEVFLAG_NOSIGNALFD\fR" 4 |
548 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
493 | .IX Item "EVFLAG_NOSIGNALFD" |
549 | .IX Item "EVFLAG_SIGNALFD" |
494 | When this flag is specified, then libev will not attempt to use the |
550 | When this flag is specified, then libev will attempt to use the |
495 | \&\fIsignalfd\fR \s-1API\s0 for it's \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This is |
551 | \&\fIsignalfd\fR \s-1API\s0 for its \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This \s-1API\s0 |
496 | probably only useful to work around any bugs in libev. Consequently, this |
552 | delivers signals synchronously, which makes it both faster and might make |
497 | flag might go away once the signalfd functionality is considered stable, |
553 | it possible to get the queued signal data. It can also simplify signal |
498 | so it's useful mostly in environment variables and not in program code. |
554 | handling with threads, as long as you properly block signals in your |
|
|
555 | threads that are not interested in handling them. |
|
|
556 | .Sp |
|
|
557 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
558 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
559 | example) that can't properly initialise their signal masks. |
|
|
560 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
|
561 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
|
|
562 | .IX Item "EVFLAG_NOSIGMASK" |
|
|
563 | When this flag is specified, then libev will avoid to modify the signal |
|
|
564 | mask. Specifically, this means you have to make sure signals are unblocked |
|
|
565 | when you want to receive them. |
|
|
566 | .Sp |
|
|
567 | This behaviour is useful when you want to do your own signal handling, or |
|
|
568 | want to handle signals only in specific threads and want to avoid libev |
|
|
569 | unblocking the signals. |
|
|
570 | .Sp |
|
|
571 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
|
|
572 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
573 | .Sp |
|
|
574 | This flag's behaviour will become the default in future versions of libev. |
499 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
575 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
500 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
576 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
501 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
577 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
502 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
578 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
503 | libev tries to roll its own fd_set with no limits on the number of fds, |
579 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
528 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
604 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
529 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
605 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
530 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
606 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
531 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
607 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
532 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
608 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
|
|
609 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
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|
610 | kernels). |
|
|
611 | .Sp |
533 | For few fds, this backend is a bit little slower than poll and select, |
612 | For few fds, this backend is a bit little slower than poll and select, but |
534 | but it scales phenomenally better. While poll and select usually scale |
613 | it scales phenomenally better. While poll and select usually scale like |
535 | like O(total_fds) where n is the total number of fds (or the highest fd), |
614 | O(total_fds) where total_fds is the total number of fds (or the highest |
536 | epoll scales either O(1) or O(active_fds). |
615 | fd), epoll scales either O(1) or O(active_fds). |
537 | .Sp |
616 | .Sp |
538 | The epoll mechanism deserves honorable mention as the most misdesigned |
617 | The epoll mechanism deserves honorable mention as the most misdesigned |
539 | of the more advanced event mechanisms: mere annoyances include silently |
618 | of the more advanced event mechanisms: mere annoyances include silently |
540 | dropping file descriptors, requiring a system call per change per file |
619 | dropping file descriptors, requiring a system call per change per file |
541 | descriptor (and unnecessary guessing of parameters), problems with dup and |
620 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
621 | returning before the timeout value, resulting in additional iterations |
|
|
622 | (and only giving 5ms accuracy while select on the same platform gives |
542 | so on. The biggest issue is fork races, however \- if a program forks then |
623 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
543 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
624 | forks then \fIboth\fR parent and child process have to recreate the epoll |
544 | take considerable time (one syscall per file descriptor) and is of course |
625 | set, which can take considerable time (one syscall per file descriptor) |
545 | hard to detect. |
626 | and is of course hard to detect. |
546 | .Sp |
627 | .Sp |
547 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
628 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
548 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
629 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
549 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
630 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
550 | even remove them from the set) than registered in the set (especially |
631 | one cannot even remove them from the set) than registered in the set |
551 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
632 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
552 | employing an additional generation counter and comparing that against the |
633 | notifications by employing an additional generation counter and comparing |
553 | events to filter out spurious ones, recreating the set when required. |
634 | that against the events to filter out spurious ones, recreating the set |
|
|
635 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
636 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
637 | because epoll returns immediately despite a nonzero timeout. And last |
|
|
638 | not least, it also refuses to work with some file descriptors which work |
|
|
639 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
|
|
640 | .Sp |
|
|
641 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
642 | cobbled together in a hurry, no thought to design or interaction with |
|
|
643 | others. Oh, the pain, will it ever stop... |
554 | .Sp |
644 | .Sp |
555 | While stopping, setting and starting an I/O watcher in the same iteration |
645 | While stopping, setting and starting an I/O watcher in the same iteration |
556 | will result in some caching, there is still a system call per such |
646 | will result in some caching, there is still a system call per such |
557 | incident (because the same \fIfile descriptor\fR could point to a different |
647 | incident (because the same \fIfile descriptor\fR could point to a different |
558 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
648 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
595 | .Sp |
685 | .Sp |
596 | It scales in the same way as the epoll backend, but the interface to the |
686 | It scales in the same way as the epoll backend, but the interface to the |
597 | kernel is more efficient (which says nothing about its actual speed, of |
687 | kernel is more efficient (which says nothing about its actual speed, of |
598 | course). While stopping, setting and starting an I/O watcher does never |
688 | course). While stopping, setting and starting an I/O watcher does never |
599 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
689 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
600 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
690 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
601 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
691 | might have to leak fd's on fork, but it's more sane than epoll) and it |
602 | cases |
692 | drops fds silently in similarly hard-to-detect cases |
603 | .Sp |
693 | .Sp |
604 | This backend usually performs well under most conditions. |
694 | This backend usually performs well under most conditions. |
605 | .Sp |
695 | .Sp |
606 | While nominally embeddable in other event loops, this doesn't work |
696 | While nominally embeddable in other event loops, this doesn't work |
607 | everywhere, so you might need to test for this. And since it is broken |
697 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
624 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
714 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
625 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
715 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
626 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
716 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
627 | it's really slow, but it still scales very well (O(active_fds)). |
717 | it's really slow, but it still scales very well (O(active_fds)). |
628 | .Sp |
718 | .Sp |
629 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
630 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
631 | blocking when no data (or space) is available. |
|
|
632 | .Sp |
|
|
633 | While this backend scales well, it requires one system call per active |
719 | While this backend scales well, it requires one system call per active |
634 | file descriptor per loop iteration. For small and medium numbers of file |
720 | file descriptor per loop iteration. For small and medium numbers of file |
635 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
721 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
636 | might perform better. |
722 | might perform better. |
637 | .Sp |
723 | .Sp |
638 | On the positive side, with the exception of the spurious readiness |
724 | On the positive side, this backend actually performed fully to |
639 | notifications, this backend actually performed fully to specification |
|
|
640 | in all tests and is fully embeddable, which is a rare feat among the |
725 | specification in all tests and is fully embeddable, which is a rare feat |
641 | OS-specific backends (I vastly prefer correctness over speed hacks). |
726 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
727 | hacks). |
|
|
728 | .Sp |
|
|
729 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
730 | even sun itself gets it wrong in their code examples: The event polling |
|
|
731 | function sometimes returns events to the caller even though an error |
|
|
732 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
733 | even documented that way) \- deadly for edge-triggered interfaces where you |
|
|
734 | absolutely have to know whether an event occurred or not because you have |
|
|
735 | to re-arm the watcher. |
|
|
736 | .Sp |
|
|
737 | Fortunately libev seems to be able to work around these idiocies. |
642 | .Sp |
738 | .Sp |
643 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
739 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
644 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
740 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
645 | .ie n .IP """EVBACKEND_ALL""" 4 |
741 | .ie n .IP """EVBACKEND_ALL""" 4 |
646 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
742 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
647 | .IX Item "EVBACKEND_ALL" |
743 | .IX Item "EVBACKEND_ALL" |
648 | Try all backends (even potentially broken ones that wouldn't be tried |
744 | Try all backends (even potentially broken ones that wouldn't be tried |
649 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
745 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
650 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
746 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
651 | .Sp |
747 | .Sp |
652 | It is definitely not recommended to use this flag. |
748 | It is definitely not recommended to use this flag, use whatever |
|
|
749 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
750 | at all. |
|
|
751 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
752 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
753 | .IX Item "EVBACKEND_MASK" |
|
|
754 | Not a backend at all, but a mask to select all backend bits from a |
|
|
755 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
756 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
653 | .RE |
757 | .RE |
654 | .RS 4 |
758 | .RS 4 |
655 | .Sp |
759 | .Sp |
656 | If one or more of the backend flags are or'ed into the flags value, |
760 | If one or more of the backend flags are or'ed into the flags value, |
657 | then only these backends will be tried (in the reverse order as listed |
761 | then only these backends will be tried (in the reverse order as listed |
658 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
762 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
659 | ()\*(C'\fR will be tried. |
763 | ()\*(C'\fR will be tried. |
660 | .Sp |
764 | .Sp |
661 | Example: This is the most typical usage. |
|
|
662 | .Sp |
|
|
663 | .Vb 2 |
|
|
664 | \& if (!ev_default_loop (0)) |
|
|
665 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
666 | .Ve |
|
|
667 | .Sp |
|
|
668 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
669 | environment settings to be taken into account: |
|
|
670 | .Sp |
|
|
671 | .Vb 1 |
|
|
672 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
673 | .Ve |
|
|
674 | .Sp |
|
|
675 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
676 | used if available (warning, breaks stuff, best use only with your own |
|
|
677 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
678 | fds): |
|
|
679 | .Sp |
|
|
680 | .Vb 1 |
|
|
681 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
682 | .Ve |
|
|
683 | .RE |
|
|
684 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
|
|
685 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
|
|
686 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
|
|
687 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
688 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
689 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
690 | .Sp |
|
|
691 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
692 | libev with threads is indeed to create one loop per thread, and using the |
|
|
693 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
694 | .Sp |
|
|
695 | Example: Try to create a event loop that uses epoll and nothing else. |
765 | Example: Try to create a event loop that uses epoll and nothing else. |
696 | .Sp |
766 | .Sp |
697 | .Vb 3 |
767 | .Vb 3 |
698 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
768 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
699 | \& if (!epoller) |
769 | \& if (!epoller) |
700 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
770 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
701 | .Ve |
771 | .Ve |
|
|
772 | .Sp |
|
|
773 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
774 | used if available. |
|
|
775 | .Sp |
|
|
776 | .Vb 1 |
|
|
777 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
778 | .Ve |
|
|
779 | .RE |
702 | .IP "ev_default_destroy ()" 4 |
780 | .IP "ev_loop_destroy (loop)" 4 |
703 | .IX Item "ev_default_destroy ()" |
781 | .IX Item "ev_loop_destroy (loop)" |
704 | Destroys the default loop again (frees all memory and kernel state |
782 | Destroys an event loop object (frees all memory and kernel state |
705 | etc.). None of the active event watchers will be stopped in the normal |
783 | etc.). None of the active event watchers will be stopped in the normal |
706 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
784 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
707 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
785 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
708 | calling this function, or cope with the fact afterwards (which is usually |
786 | calling this function, or cope with the fact afterwards (which is usually |
709 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
787 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
… | |
… | |
711 | .Sp |
789 | .Sp |
712 | Note that certain global state, such as signal state (and installed signal |
790 | Note that certain global state, such as signal state (and installed signal |
713 | handlers), will not be freed by this function, and related watchers (such |
791 | handlers), will not be freed by this function, and related watchers (such |
714 | as signal and child watchers) would need to be stopped manually. |
792 | as signal and child watchers) would need to be stopped manually. |
715 | .Sp |
793 | .Sp |
716 | In general it is not advisable to call this function except in the |
794 | This function is normally used on loop objects allocated by |
717 | rare occasion where you really need to free e.g. the signal handling |
795 | \&\f(CW\*(C`ev_loop_new\*(C'\fR, but it can also be used on the default loop returned by |
718 | pipe fds. If you need dynamically allocated loops it is better to use |
796 | \&\f(CW\*(C`ev_default_loop\*(C'\fR, in which case it is not thread-safe. |
719 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
|
|
720 | .IP "ev_loop_destroy (loop)" 4 |
|
|
721 | .IX Item "ev_loop_destroy (loop)" |
|
|
722 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
|
|
723 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
|
|
724 | .IP "ev_default_fork ()" 4 |
|
|
725 | .IX Item "ev_default_fork ()" |
|
|
726 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
|
|
727 | to reinitialise the kernel state for backends that have one. Despite the |
|
|
728 | name, you can call it anytime, but it makes most sense after forking, in |
|
|
729 | the child process (or both child and parent, but that again makes little |
|
|
730 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
731 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
|
|
732 | .Sp |
797 | .Sp |
733 | On the other hand, you only need to call this function in the child |
798 | Note that it is not advisable to call this function on the default loop |
734 | process if and only if you want to use the event library in the child. If |
799 | except in the rare occasion where you really need to free its resources. |
735 | you just fork+exec, you don't have to call it at all. |
800 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
736 | .Sp |
801 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
737 | The function itself is quite fast and it's usually not a problem to call |
|
|
738 | it just in case after a fork. To make this easy, the function will fit in |
|
|
739 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
|
|
740 | .Sp |
|
|
741 | .Vb 1 |
|
|
742 | \& pthread_atfork (0, 0, ev_default_fork); |
|
|
743 | .Ve |
|
|
744 | .IP "ev_loop_fork (loop)" 4 |
802 | .IP "ev_loop_fork (loop)" 4 |
745 | .IX Item "ev_loop_fork (loop)" |
803 | .IX Item "ev_loop_fork (loop)" |
746 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
804 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
747 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
805 | reinitialise the kernel state for backends that have one. Despite the |
748 | after fork that you want to re-use in the child, and how you do this is |
806 | name, you can call it anytime, but it makes most sense after forking, in |
749 | entirely your own problem. |
807 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
|
|
808 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
|
|
809 | .Sp |
|
|
810 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
|
|
811 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
|
|
812 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
|
|
813 | during fork. |
|
|
814 | .Sp |
|
|
815 | On the other hand, you only need to call this function in the child |
|
|
816 | process if and only if you want to use the event loop in the child. If |
|
|
817 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
818 | call it at all (in fact, \f(CW\*(C`epoll\*(C'\fR is so badly broken that it makes a |
|
|
819 | difference, but libev will usually detect this case on its own and do a |
|
|
820 | costly reset of the backend). |
|
|
821 | .Sp |
|
|
822 | The function itself is quite fast and it's usually not a problem to call |
|
|
823 | it just in case after a fork. |
|
|
824 | .Sp |
|
|
825 | Example: Automate calling \f(CW\*(C`ev_loop_fork\*(C'\fR on the default loop when |
|
|
826 | using pthreads. |
|
|
827 | .Sp |
|
|
828 | .Vb 5 |
|
|
829 | \& static void |
|
|
830 | \& post_fork_child (void) |
|
|
831 | \& { |
|
|
832 | \& ev_loop_fork (EV_DEFAULT); |
|
|
833 | \& } |
|
|
834 | \& |
|
|
835 | \& ... |
|
|
836 | \& pthread_atfork (0, 0, post_fork_child); |
|
|
837 | .Ve |
750 | .IP "int ev_is_default_loop (loop)" 4 |
838 | .IP "int ev_is_default_loop (loop)" 4 |
751 | .IX Item "int ev_is_default_loop (loop)" |
839 | .IX Item "int ev_is_default_loop (loop)" |
752 | Returns true when the given loop is, in fact, the default loop, and false |
840 | Returns true when the given loop is, in fact, the default loop, and false |
753 | otherwise. |
841 | otherwise. |
754 | .IP "unsigned int ev_loop_count (loop)" 4 |
842 | .IP "unsigned int ev_iteration (loop)" 4 |
755 | .IX Item "unsigned int ev_loop_count (loop)" |
843 | .IX Item "unsigned int ev_iteration (loop)" |
756 | Returns the count of loop iterations for the loop, which is identical to |
844 | Returns the current iteration count for the event loop, which is identical |
757 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
845 | to the number of times libev did poll for new events. It starts at \f(CW0\fR |
758 | happily wraps around with enough iterations. |
846 | and happily wraps around with enough iterations. |
759 | .Sp |
847 | .Sp |
760 | This value can sometimes be useful as a generation counter of sorts (it |
848 | This value can sometimes be useful as a generation counter of sorts (it |
761 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
849 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
762 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
850 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
|
|
851 | prepare and check phases. |
763 | .IP "unsigned int ev_loop_depth (loop)" 4 |
852 | .IP "unsigned int ev_depth (loop)" 4 |
764 | .IX Item "unsigned int ev_loop_depth (loop)" |
853 | .IX Item "unsigned int ev_depth (loop)" |
765 | Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of |
854 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
766 | times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth. |
855 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
767 | .Sp |
856 | .Sp |
768 | Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is |
857 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
769 | \&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread), |
858 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
770 | in which case it is higher. |
859 | in which case it is higher. |
771 | .Sp |
860 | .Sp |
772 | Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
861 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
773 | etc.), doesn't count as exit. |
862 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
|
|
863 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
864 | convenient, in which case it is fully supported. |
774 | .IP "unsigned int ev_backend (loop)" 4 |
865 | .IP "unsigned int ev_backend (loop)" 4 |
775 | .IX Item "unsigned int ev_backend (loop)" |
866 | .IX Item "unsigned int ev_backend (loop)" |
776 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
867 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
777 | use. |
868 | use. |
778 | .IP "ev_tstamp ev_now (loop)" 4 |
869 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
784 | event occurring (or more correctly, libev finding out about it). |
875 | event occurring (or more correctly, libev finding out about it). |
785 | .IP "ev_now_update (loop)" 4 |
876 | .IP "ev_now_update (loop)" 4 |
786 | .IX Item "ev_now_update (loop)" |
877 | .IX Item "ev_now_update (loop)" |
787 | Establishes the current time by querying the kernel, updating the time |
878 | Establishes the current time by querying the kernel, updating the time |
788 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
879 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
789 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
880 | is usually done automatically within \f(CW\*(C`ev_run ()\*(C'\fR. |
790 | .Sp |
881 | .Sp |
791 | This function is rarely useful, but when some event callback runs for a |
882 | This function is rarely useful, but when some event callback runs for a |
792 | very long time without entering the event loop, updating libev's idea of |
883 | very long time without entering the event loop, updating libev's idea of |
793 | the current time is a good idea. |
884 | the current time is a good idea. |
794 | .Sp |
885 | .Sp |
… | |
… | |
797 | .IX Item "ev_suspend (loop)" |
888 | .IX Item "ev_suspend (loop)" |
798 | .PD 0 |
889 | .PD 0 |
799 | .IP "ev_resume (loop)" 4 |
890 | .IP "ev_resume (loop)" 4 |
800 | .IX Item "ev_resume (loop)" |
891 | .IX Item "ev_resume (loop)" |
801 | .PD |
892 | .PD |
802 | These two functions suspend and resume a loop, for use when the loop is |
893 | These two functions suspend and resume an event loop, for use when the |
803 | not used for a while and timeouts should not be processed. |
894 | loop is not used for a while and timeouts should not be processed. |
804 | .Sp |
895 | .Sp |
805 | A typical use case would be an interactive program such as a game: When |
896 | A typical use case would be an interactive program such as a game: When |
806 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
897 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
807 | would be best to handle timeouts as if no time had actually passed while |
898 | would be best to handle timeouts as if no time had actually passed while |
808 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
899 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
… | |
… | |
810 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
901 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
811 | .Sp |
902 | .Sp |
812 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
903 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
813 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
904 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
814 | will be rescheduled (that is, they will lose any events that would have |
905 | will be rescheduled (that is, they will lose any events that would have |
815 | occured while suspended). |
906 | occurred while suspended). |
816 | .Sp |
907 | .Sp |
817 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
908 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
818 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
909 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
819 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
910 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
820 | .Sp |
911 | .Sp |
821 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
912 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
822 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
913 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
823 | .IP "ev_loop (loop, int flags)" 4 |
914 | .IP "bool ev_run (loop, int flags)" 4 |
824 | .IX Item "ev_loop (loop, int flags)" |
915 | .IX Item "bool ev_run (loop, int flags)" |
825 | Finally, this is it, the event handler. This function usually is called |
916 | Finally, this is it, the event handler. This function usually is called |
826 | after you initialised all your watchers and you want to start handling |
917 | after you have initialised all your watchers and you want to start |
827 | events. |
918 | handling events. It will ask the operating system for any new events, call |
|
|
919 | the watcher callbacks, and then repeat the whole process indefinitely: This |
|
|
920 | is why event loops are called \fIloops\fR. |
828 | .Sp |
921 | .Sp |
829 | If the flags argument is specified as \f(CW0\fR, it will not return until |
922 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
830 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
923 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
|
|
924 | called. |
831 | .Sp |
925 | .Sp |
|
|
926 | The return value is false if there are no more active watchers (which |
|
|
927 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
928 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
|
|
929 | .Sp |
832 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
930 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
833 | relying on all watchers to be stopped when deciding when a program has |
931 | relying on all watchers to be stopped when deciding when a program has |
834 | finished (especially in interactive programs), but having a program |
932 | finished (especially in interactive programs), but having a program |
835 | that automatically loops as long as it has to and no longer by virtue |
933 | that automatically loops as long as it has to and no longer by virtue |
836 | of relying on its watchers stopping correctly, that is truly a thing of |
934 | of relying on its watchers stopping correctly, that is truly a thing of |
837 | beauty. |
935 | beauty. |
838 | .Sp |
936 | .Sp |
|
|
937 | This function is \fImostly\fR exception-safe \- you can break out of a |
|
|
938 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
939 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
940 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
941 | .Sp |
839 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
942 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
840 | those events and any already outstanding ones, but will not block your |
943 | those events and any already outstanding ones, but will not wait and |
841 | process in case there are no events and will return after one iteration of |
944 | block your process in case there are no events and will return after one |
842 | the loop. |
945 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
946 | events while doing lengthy calculations, to keep the program responsive. |
843 | .Sp |
947 | .Sp |
844 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
948 | A flags value of \f(CW\*(C`EVRUN_ONCE\*(C'\fR will look for new events (waiting if |
845 | necessary) and will handle those and any already outstanding ones. It |
949 | necessary) and will handle those and any already outstanding ones. It |
846 | will block your process until at least one new event arrives (which could |
950 | will block your process until at least one new event arrives (which could |
847 | be an event internal to libev itself, so there is no guarantee that a |
951 | be an event internal to libev itself, so there is no guarantee that a |
848 | user-registered callback will be called), and will return after one |
952 | user-registered callback will be called), and will return after one |
849 | iteration of the loop. |
953 | iteration of the loop. |
850 | .Sp |
954 | .Sp |
851 | This is useful if you are waiting for some external event in conjunction |
955 | This is useful if you are waiting for some external event in conjunction |
852 | with something not expressible using other libev watchers (i.e. "roll your |
956 | with something not expressible using other libev watchers (i.e. "roll your |
853 | own \f(CW\*(C`ev_loop\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
957 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
854 | usually a better approach for this kind of thing. |
958 | usually a better approach for this kind of thing. |
855 | .Sp |
959 | .Sp |
856 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
960 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
961 | understanding, not a guarantee that things will work exactly like this in |
|
|
962 | future versions): |
857 | .Sp |
963 | .Sp |
858 | .Vb 10 |
964 | .Vb 10 |
|
|
965 | \& \- Increment loop depth. |
|
|
966 | \& \- Reset the ev_break status. |
859 | \& \- Before the first iteration, call any pending watchers. |
967 | \& \- Before the first iteration, call any pending watchers. |
|
|
968 | \& LOOP: |
860 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
969 | \& \- If EVFLAG_FORKCHECK was used, check for a fork. |
861 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
970 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
862 | \& \- Queue and call all prepare watchers. |
971 | \& \- Queue and call all prepare watchers. |
|
|
972 | \& \- If ev_break was called, goto FINISH. |
863 | \& \- If we have been forked, detach and recreate the kernel state |
973 | \& \- If we have been forked, detach and recreate the kernel state |
864 | \& as to not disturb the other process. |
974 | \& as to not disturb the other process. |
865 | \& \- Update the kernel state with all outstanding changes. |
975 | \& \- Update the kernel state with all outstanding changes. |
866 | \& \- Update the "event loop time" (ev_now ()). |
976 | \& \- Update the "event loop time" (ev_now ()). |
867 | \& \- Calculate for how long to sleep or block, if at all |
977 | \& \- Calculate for how long to sleep or block, if at all |
868 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
978 | \& (active idle watchers, EVRUN_NOWAIT or not having |
869 | \& any active watchers at all will result in not sleeping). |
979 | \& any active watchers at all will result in not sleeping). |
870 | \& \- Sleep if the I/O and timer collect interval say so. |
980 | \& \- Sleep if the I/O and timer collect interval say so. |
|
|
981 | \& \- Increment loop iteration counter. |
871 | \& \- Block the process, waiting for any events. |
982 | \& \- Block the process, waiting for any events. |
872 | \& \- Queue all outstanding I/O (fd) events. |
983 | \& \- Queue all outstanding I/O (fd) events. |
873 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
984 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
874 | \& \- Queue all expired timers. |
985 | \& \- Queue all expired timers. |
875 | \& \- Queue all expired periodics. |
986 | \& \- Queue all expired periodics. |
876 | \& \- Unless any events are pending now, queue all idle watchers. |
987 | \& \- Queue all idle watchers with priority higher than that of pending events. |
877 | \& \- Queue all check watchers. |
988 | \& \- Queue all check watchers. |
878 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
989 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
879 | \& Signals and child watchers are implemented as I/O watchers, and will |
990 | \& Signals and child watchers are implemented as I/O watchers, and will |
880 | \& be handled here by queueing them when their watcher gets executed. |
991 | \& be handled here by queueing them when their watcher gets executed. |
881 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
992 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
882 | \& were used, or there are no active watchers, return, otherwise |
993 | \& were used, or there are no active watchers, goto FINISH, otherwise |
883 | \& continue with step *. |
994 | \& continue with step LOOP. |
|
|
995 | \& FINISH: |
|
|
996 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
997 | \& \- Decrement the loop depth. |
|
|
998 | \& \- Return. |
884 | .Ve |
999 | .Ve |
885 | .Sp |
1000 | .Sp |
886 | Example: Queue some jobs and then loop until no events are outstanding |
1001 | Example: Queue some jobs and then loop until no events are outstanding |
887 | anymore. |
1002 | anymore. |
888 | .Sp |
1003 | .Sp |
889 | .Vb 4 |
1004 | .Vb 4 |
890 | \& ... queue jobs here, make sure they register event watchers as long |
1005 | \& ... queue jobs here, make sure they register event watchers as long |
891 | \& ... as they still have work to do (even an idle watcher will do..) |
1006 | \& ... as they still have work to do (even an idle watcher will do..) |
892 | \& ev_loop (my_loop, 0); |
1007 | \& ev_run (my_loop, 0); |
893 | \& ... jobs done or somebody called unloop. yeah! |
1008 | \& ... jobs done or somebody called break. yeah! |
894 | .Ve |
1009 | .Ve |
895 | .IP "ev_unloop (loop, how)" 4 |
1010 | .IP "ev_break (loop, how)" 4 |
896 | .IX Item "ev_unloop (loop, how)" |
1011 | .IX Item "ev_break (loop, how)" |
897 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
1012 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
898 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1013 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
899 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
1014 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
900 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
1015 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
901 | .Sp |
1016 | .Sp |
902 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
1017 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
903 | .Sp |
1018 | .Sp |
904 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
1019 | It is safe to call \f(CW\*(C`ev_break\*(C'\fR from outside any \f(CW\*(C`ev_run\*(C'\fR calls, too, in |
|
|
1020 | which case it will have no effect. |
905 | .IP "ev_ref (loop)" 4 |
1021 | .IP "ev_ref (loop)" 4 |
906 | .IX Item "ev_ref (loop)" |
1022 | .IX Item "ev_ref (loop)" |
907 | .PD 0 |
1023 | .PD 0 |
908 | .IP "ev_unref (loop)" 4 |
1024 | .IP "ev_unref (loop)" 4 |
909 | .IX Item "ev_unref (loop)" |
1025 | .IX Item "ev_unref (loop)" |
910 | .PD |
1026 | .PD |
911 | Ref/unref can be used to add or remove a reference count on the event |
1027 | Ref/unref can be used to add or remove a reference count on the event |
912 | loop: Every watcher keeps one reference, and as long as the reference |
1028 | loop: Every watcher keeps one reference, and as long as the reference |
913 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
1029 | count is nonzero, \f(CW\*(C`ev_run\*(C'\fR will not return on its own. |
914 | .Sp |
1030 | .Sp |
915 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
1031 | This is useful when you have a watcher that you never intend to |
916 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
1032 | unregister, but that nevertheless should not keep \f(CW\*(C`ev_run\*(C'\fR from |
|
|
1033 | returning. In such a case, call \f(CW\*(C`ev_unref\*(C'\fR after starting, and \f(CW\*(C`ev_ref\*(C'\fR |
917 | stopping it. |
1034 | before stopping it. |
918 | .Sp |
1035 | .Sp |
919 | As an example, libev itself uses this for its internal signal pipe: It |
1036 | As an example, libev itself uses this for its internal signal pipe: It |
920 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
1037 | is not visible to the libev user and should not keep \f(CW\*(C`ev_run\*(C'\fR from |
921 | exiting if no event watchers registered by it are active. It is also an |
1038 | exiting if no event watchers registered by it are active. It is also an |
922 | excellent way to do this for generic recurring timers or from within |
1039 | excellent way to do this for generic recurring timers or from within |
923 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
1040 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
924 | before stop\fR (but only if the watcher wasn't active before, or was active |
1041 | before stop\fR (but only if the watcher wasn't active before, or was active |
925 | before, respectively. Note also that libev might stop watchers itself |
1042 | before, respectively. Note also that libev might stop watchers itself |
926 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
1043 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
927 | in the callback). |
1044 | in the callback). |
928 | .Sp |
1045 | .Sp |
929 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
1046 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_run\*(C'\fR |
930 | running when nothing else is active. |
1047 | running when nothing else is active. |
931 | .Sp |
1048 | .Sp |
932 | .Vb 4 |
1049 | .Vb 4 |
933 | \& ev_signal exitsig; |
1050 | \& ev_signal exitsig; |
934 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1051 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
935 | \& ev_signal_start (loop, &exitsig); |
1052 | \& ev_signal_start (loop, &exitsig); |
936 | \& evf_unref (loop); |
1053 | \& ev_unref (loop); |
937 | .Ve |
1054 | .Ve |
938 | .Sp |
1055 | .Sp |
939 | Example: For some weird reason, unregister the above signal handler again. |
1056 | Example: For some weird reason, unregister the above signal handler again. |
940 | .Sp |
1057 | .Sp |
941 | .Vb 2 |
1058 | .Vb 2 |
… | |
… | |
965 | overhead for the actual polling but can deliver many events at once. |
1082 | overhead for the actual polling but can deliver many events at once. |
966 | .Sp |
1083 | .Sp |
967 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1084 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
968 | time collecting I/O events, so you can handle more events per iteration, |
1085 | time collecting I/O events, so you can handle more events per iteration, |
969 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1086 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
970 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1087 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
971 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1088 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
972 | sleep time ensures that libev will not poll for I/O events more often then |
1089 | sleep time ensures that libev will not poll for I/O events more often then |
973 | once per this interval, on average. |
1090 | once per this interval, on average (as long as the host time resolution is |
|
|
1091 | good enough). |
974 | .Sp |
1092 | .Sp |
975 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1093 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
976 | to spend more time collecting timeouts, at the expense of increased |
1094 | to spend more time collecting timeouts, at the expense of increased |
977 | latency/jitter/inexactness (the watcher callback will be called |
1095 | latency/jitter/inexactness (the watcher callback will be called |
978 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1096 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
984 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
1102 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
985 | as this approaches the timing granularity of most systems. Note that if |
1103 | as this approaches the timing granularity of most systems. Note that if |
986 | you do transactions with the outside world and you can't increase the |
1104 | you do transactions with the outside world and you can't increase the |
987 | parallelity, then this setting will limit your transaction rate (if you |
1105 | parallelity, then this setting will limit your transaction rate (if you |
988 | need to poll once per transaction and the I/O collect interval is 0.01, |
1106 | need to poll once per transaction and the I/O collect interval is 0.01, |
989 | then you can't do more than 100 transations per second). |
1107 | then you can't do more than 100 transactions per second). |
990 | .Sp |
1108 | .Sp |
991 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
1109 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
992 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
1110 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
993 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
1111 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
994 | times the process sleeps and wakes up again. Another useful technique to |
1112 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
1003 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
1121 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
1004 | .Ve |
1122 | .Ve |
1005 | .IP "ev_invoke_pending (loop)" 4 |
1123 | .IP "ev_invoke_pending (loop)" 4 |
1006 | .IX Item "ev_invoke_pending (loop)" |
1124 | .IX Item "ev_invoke_pending (loop)" |
1007 | This call will simply invoke all pending watchers while resetting their |
1125 | This call will simply invoke all pending watchers while resetting their |
1008 | pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required, |
1126 | pending state. Normally, \f(CW\*(C`ev_run\*(C'\fR does this automatically when required, |
1009 | but when overriding the invoke callback this call comes handy. |
1127 | but when overriding the invoke callback this call comes handy. This |
|
|
1128 | function can be invoked from a watcher \- this can be useful for example |
|
|
1129 | when you want to do some lengthy calculation and want to pass further |
|
|
1130 | event handling to another thread (you still have to make sure only one |
|
|
1131 | thread executes within \f(CW\*(C`ev_invoke_pending\*(C'\fR or \f(CW\*(C`ev_run\*(C'\fR of course). |
1010 | .IP "int ev_pending_count (loop)" 4 |
1132 | .IP "int ev_pending_count (loop)" 4 |
1011 | .IX Item "int ev_pending_count (loop)" |
1133 | .IX Item "int ev_pending_count (loop)" |
1012 | Returns the number of pending watchers \- zero indicates that no watchers |
1134 | Returns the number of pending watchers \- zero indicates that no watchers |
1013 | are pending. |
1135 | are pending. |
1014 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
1136 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
1015 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
1137 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
1016 | This overrides the invoke pending functionality of the loop: Instead of |
1138 | This overrides the invoke pending functionality of the loop: Instead of |
1017 | invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call |
1139 | invoking all pending watchers when there are any, \f(CW\*(C`ev_run\*(C'\fR will call |
1018 | this callback instead. This is useful, for example, when you want to |
1140 | this callback instead. This is useful, for example, when you want to |
1019 | invoke the actual watchers inside another context (another thread etc.). |
1141 | invoke the actual watchers inside another context (another thread etc.). |
1020 | .Sp |
1142 | .Sp |
1021 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1143 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1022 | callback. |
1144 | callback. |
1023 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1145 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1024 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1146 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1025 | Sometimes you want to share the same loop between multiple threads. This |
1147 | Sometimes you want to share the same loop between multiple threads. This |
1026 | can be done relatively simply by putting mutex_lock/unlock calls around |
1148 | can be done relatively simply by putting mutex_lock/unlock calls around |
1027 | each call to a libev function. |
1149 | each call to a libev function. |
1028 | .Sp |
1150 | .Sp |
1029 | However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to |
1151 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1030 | wait for it to return. One way around this is to wake up the loop via |
1152 | to wait for it to return. One way around this is to wake up the event |
1031 | \&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR |
1153 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1032 | and \fIacquire\fR callbacks on the loop. |
1154 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1033 | .Sp |
1155 | .Sp |
1034 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1156 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1035 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1157 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1036 | afterwards. |
1158 | afterwards. |
1037 | .Sp |
1159 | .Sp |
… | |
… | |
1040 | .Sp |
1162 | .Sp |
1041 | While event loop modifications are allowed between invocations of |
1163 | While event loop modifications are allowed between invocations of |
1042 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
1164 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
1043 | modifications done will affect the event loop, i.e. adding watchers will |
1165 | modifications done will affect the event loop, i.e. adding watchers will |
1044 | have no effect on the set of file descriptors being watched, or the time |
1166 | have no effect on the set of file descriptors being watched, or the time |
1045 | waited. USe an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it |
1167 | waited. Use an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_run\*(C'\fR when you want it |
1046 | to take note of any changes you made. |
1168 | to take note of any changes you made. |
1047 | .Sp |
1169 | .Sp |
1048 | In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between |
1170 | In theory, threads executing \f(CW\*(C`ev_run\*(C'\fR will be async-cancel safe between |
1049 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
1171 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
1050 | .Sp |
1172 | .Sp |
1051 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1173 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1052 | document. |
1174 | document. |
1053 | .IP "ev_set_userdata (loop, void *data)" 4 |
1175 | .IP "ev_set_userdata (loop, void *data)" 4 |
1054 | .IX Item "ev_set_userdata (loop, void *data)" |
1176 | .IX Item "ev_set_userdata (loop, void *data)" |
1055 | .PD 0 |
1177 | .PD 0 |
1056 | .IP "ev_userdata (loop)" 4 |
1178 | .IP "void *ev_userdata (loop)" 4 |
1057 | .IX Item "ev_userdata (loop)" |
1179 | .IX Item "void *ev_userdata (loop)" |
1058 | .PD |
1180 | .PD |
1059 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1181 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1060 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1182 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1061 | \&\f(CW0.\fR |
1183 | \&\f(CW0\fR. |
1062 | .Sp |
1184 | .Sp |
1063 | These two functions can be used to associate arbitrary data with a loop, |
1185 | These two functions can be used to associate arbitrary data with a loop, |
1064 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1186 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1065 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1187 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1066 | any other purpose as well. |
1188 | any other purpose as well. |
1067 | .IP "ev_loop_verify (loop)" 4 |
1189 | .IP "ev_verify (loop)" 4 |
1068 | .IX Item "ev_loop_verify (loop)" |
1190 | .IX Item "ev_verify (loop)" |
1069 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1191 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1070 | compiled in, which is the default for non-minimal builds. It tries to go |
1192 | compiled in, which is the default for non-minimal builds. It tries to go |
1071 | through all internal structures and checks them for validity. If anything |
1193 | through all internal structures and checks them for validity. If anything |
1072 | is found to be inconsistent, it will print an error message to standard |
1194 | is found to be inconsistent, it will print an error message to standard |
1073 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
1195 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
… | |
… | |
1079 | .IX Header "ANATOMY OF A WATCHER" |
1201 | .IX Header "ANATOMY OF A WATCHER" |
1080 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
1202 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
1081 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
1203 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
1082 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
1204 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
1083 | .PP |
1205 | .PP |
1084 | A watcher is a structure that you create and register to record your |
1206 | A watcher is an opaque structure that you allocate and register to record |
1085 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
1207 | your interest in some event. To make a concrete example, imagine you want |
1086 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
1208 | to wait for \s-1STDIN\s0 to become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher |
|
|
1209 | for that: |
1087 | .PP |
1210 | .PP |
1088 | .Vb 5 |
1211 | .Vb 5 |
1089 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1212 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1090 | \& { |
1213 | \& { |
1091 | \& ev_io_stop (w); |
1214 | \& ev_io_stop (w); |
1092 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1215 | \& ev_break (loop, EVBREAK_ALL); |
1093 | \& } |
1216 | \& } |
1094 | \& |
1217 | \& |
1095 | \& struct ev_loop *loop = ev_default_loop (0); |
1218 | \& struct ev_loop *loop = ev_default_loop (0); |
1096 | \& |
1219 | \& |
1097 | \& ev_io stdin_watcher; |
1220 | \& ev_io stdin_watcher; |
1098 | \& |
1221 | \& |
1099 | \& ev_init (&stdin_watcher, my_cb); |
1222 | \& ev_init (&stdin_watcher, my_cb); |
1100 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1223 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1101 | \& ev_io_start (loop, &stdin_watcher); |
1224 | \& ev_io_start (loop, &stdin_watcher); |
1102 | \& |
1225 | \& |
1103 | \& ev_loop (loop, 0); |
1226 | \& ev_run (loop, 0); |
1104 | .Ve |
1227 | .Ve |
1105 | .PP |
1228 | .PP |
1106 | As you can see, you are responsible for allocating the memory for your |
1229 | As you can see, you are responsible for allocating the memory for your |
1107 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
1230 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
1108 | stack). |
1231 | stack). |
1109 | .PP |
1232 | .PP |
1110 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1233 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1111 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
1234 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
1112 | .PP |
1235 | .PP |
1113 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1236 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init (watcher |
1114 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1237 | *, callback)\*(C'\fR, which expects a callback to be provided. This callback is |
1115 | callback gets invoked each time the event occurs (or, in the case of I/O |
1238 | invoked each time the event occurs (or, in the case of I/O watchers, each |
1116 | watchers, each time the event loop detects that the file descriptor given |
1239 | time the event loop detects that the file descriptor given is readable |
1117 | is readable and/or writable). |
1240 | and/or writable). |
1118 | .PP |
1241 | .PP |
1119 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1242 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1120 | macro to configure it, with arguments specific to the watcher type. There |
1243 | macro to configure it, with arguments specific to the watcher type. There |
1121 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
1244 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
1122 | .PP |
1245 | .PP |
… | |
… | |
1144 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1267 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1145 | .IX Item "EV_WRITE" |
1268 | .IX Item "EV_WRITE" |
1146 | .PD |
1269 | .PD |
1147 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1270 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1148 | writable. |
1271 | writable. |
1149 | .ie n .IP """EV_TIMEOUT""" 4 |
1272 | .ie n .IP """EV_TIMER""" 4 |
1150 | .el .IP "\f(CWEV_TIMEOUT\fR" 4 |
1273 | .el .IP "\f(CWEV_TIMER\fR" 4 |
1151 | .IX Item "EV_TIMEOUT" |
1274 | .IX Item "EV_TIMER" |
1152 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1275 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1153 | .ie n .IP """EV_PERIODIC""" 4 |
1276 | .ie n .IP """EV_PERIODIC""" 4 |
1154 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1277 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1155 | .IX Item "EV_PERIODIC" |
1278 | .IX Item "EV_PERIODIC" |
1156 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
1279 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
… | |
… | |
1176 | .PD 0 |
1299 | .PD 0 |
1177 | .ie n .IP """EV_CHECK""" 4 |
1300 | .ie n .IP """EV_CHECK""" 4 |
1178 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1301 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1179 | .IX Item "EV_CHECK" |
1302 | .IX Item "EV_CHECK" |
1180 | .PD |
1303 | .PD |
1181 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_loop\*(C'\fR starts |
1304 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1182 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1305 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1183 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1306 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1184 | received events. Callbacks of both watcher types can start and stop as |
1307 | received events. Callbacks of both watcher types can start and stop as |
1185 | many watchers as they want, and all of them will be taken into account |
1308 | many watchers as they want, and all of them will be taken into account |
1186 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1309 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1187 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
1310 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1188 | .ie n .IP """EV_EMBED""" 4 |
1311 | .ie n .IP """EV_EMBED""" 4 |
1189 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1312 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1190 | .IX Item "EV_EMBED" |
1313 | .IX Item "EV_EMBED" |
1191 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1314 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1192 | .ie n .IP """EV_FORK""" 4 |
1315 | .ie n .IP """EV_FORK""" 4 |
1193 | .el .IP "\f(CWEV_FORK\fR" 4 |
1316 | .el .IP "\f(CWEV_FORK\fR" 4 |
1194 | .IX Item "EV_FORK" |
1317 | .IX Item "EV_FORK" |
1195 | The event loop has been resumed in the child process after fork (see |
1318 | The event loop has been resumed in the child process after fork (see |
1196 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1319 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1320 | .ie n .IP """EV_CLEANUP""" 4 |
|
|
1321 | .el .IP "\f(CWEV_CLEANUP\fR" 4 |
|
|
1322 | .IX Item "EV_CLEANUP" |
|
|
1323 | The event loop is about to be destroyed (see \f(CW\*(C`ev_cleanup\*(C'\fR). |
1197 | .ie n .IP """EV_ASYNC""" 4 |
1324 | .ie n .IP """EV_ASYNC""" 4 |
1198 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1325 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1199 | .IX Item "EV_ASYNC" |
1326 | .IX Item "EV_ASYNC" |
1200 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1327 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1201 | .ie n .IP """EV_CUSTOM""" 4 |
1328 | .ie n .IP """EV_CUSTOM""" 4 |
… | |
… | |
1245 | .Vb 3 |
1372 | .Vb 3 |
1246 | \& ev_io w; |
1373 | \& ev_io w; |
1247 | \& ev_init (&w, my_cb); |
1374 | \& ev_init (&w, my_cb); |
1248 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1375 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1249 | .Ve |
1376 | .Ve |
1250 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1377 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4 |
1251 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1378 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4 |
1252 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1379 | .IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])" |
1253 | This macro initialises the type-specific parts of a watcher. You need to |
1380 | This macro initialises the type-specific parts of a watcher. You need to |
1254 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1381 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1255 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1382 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1256 | macro on a watcher that is active (it can be pending, however, which is a |
1383 | macro on a watcher that is active (it can be pending, however, which is a |
1257 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1384 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
… | |
… | |
1270 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1397 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1271 | .Sp |
1398 | .Sp |
1272 | .Vb 1 |
1399 | .Vb 1 |
1273 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1400 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1274 | .Ve |
1401 | .Ve |
1275 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1402 | .ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4 |
1276 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1403 | .el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4 |
1277 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1404 | .IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)" |
1278 | Starts (activates) the given watcher. Only active watchers will receive |
1405 | Starts (activates) the given watcher. Only active watchers will receive |
1279 | events. If the watcher is already active nothing will happen. |
1406 | events. If the watcher is already active nothing will happen. |
1280 | .Sp |
1407 | .Sp |
1281 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1408 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1282 | whole section. |
1409 | whole section. |
1283 | .Sp |
1410 | .Sp |
1284 | .Vb 1 |
1411 | .Vb 1 |
1285 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1412 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1286 | .Ve |
1413 | .Ve |
1287 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1414 | .ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4 |
1288 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1415 | .el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4 |
1289 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1416 | .IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)" |
1290 | Stops the given watcher if active, and clears the pending status (whether |
1417 | Stops the given watcher if active, and clears the pending status (whether |
1291 | the watcher was active or not). |
1418 | the watcher was active or not). |
1292 | .Sp |
1419 | .Sp |
1293 | It is possible that stopped watchers are pending \- for example, |
1420 | It is possible that stopped watchers are pending \- for example, |
1294 | non-repeating timers are being stopped when they become pending \- but |
1421 | non-repeating timers are being stopped when they become pending \- but |
… | |
… | |
1313 | Returns the callback currently set on the watcher. |
1440 | Returns the callback currently set on the watcher. |
1314 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1441 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1315 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1442 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1316 | Change the callback. You can change the callback at virtually any time |
1443 | Change the callback. You can change the callback at virtually any time |
1317 | (modulo threads). |
1444 | (modulo threads). |
1318 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
1445 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1319 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
1446 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1320 | .PD 0 |
1447 | .PD 0 |
1321 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1448 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1322 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1449 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1323 | .PD |
1450 | .PD |
1324 | Set and query the priority of the watcher. The priority is a small |
1451 | Set and query the priority of the watcher. The priority is a small |
… | |
… | |
1354 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1481 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1355 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1482 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1356 | .Sp |
1483 | .Sp |
1357 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1484 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1358 | callback to be invoked, which can be accomplished with this function. |
1485 | callback to be invoked, which can be accomplished with this function. |
1359 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1486 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1360 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1487 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1361 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1488 | Feeds the given event set into the event loop, as if the specified event |
1362 | and read at any time: libev will completely ignore it. This can be used |
1489 | had happened for the specified watcher (which must be a pointer to an |
1363 | to associate arbitrary data with your watcher. If you need more data and |
1490 | initialised but not necessarily started event watcher). Obviously you must |
1364 | don't want to allocate memory and store a pointer to it in that data |
1491 | not free the watcher as long as it has pending events. |
1365 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1492 | .Sp |
1366 | data: |
1493 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1494 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
|
|
1495 | not started in the first place. |
|
|
1496 | .Sp |
|
|
1497 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
|
|
1498 | functions that do not need a watcher. |
1367 | .PP |
1499 | .PP |
1368 | .Vb 7 |
1500 | See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 |
1369 | \& struct my_io |
1501 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
1370 | \& { |
1502 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1371 | \& ev_io io; |
1503 | .IX Subsection "WATCHER STATES" |
1372 | \& int otherfd; |
1504 | There are various watcher states mentioned throughout this manual \- |
1373 | \& void *somedata; |
1505 | active, pending and so on. In this section these states and the rules to |
1374 | \& struct whatever *mostinteresting; |
1506 | transition between them will be described in more detail \- and while these |
1375 | \& }; |
1507 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1376 | \& |
1508 | .IP "initialiased" 4 |
1377 | \& ... |
1509 | .IX Item "initialiased" |
1378 | \& struct my_io w; |
1510 | Before a watcher can be registered with the event loop it has to be |
1379 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
1511 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1380 | .Ve |
1512 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1381 | .PP |
1513 | .Sp |
1382 | And since your callback will be called with a pointer to the watcher, you |
1514 | In this state it is simply some block of memory that is suitable for |
1383 | can cast it back to your own type: |
1515 | use in an event loop. It can be moved around, freed, reused etc. at |
1384 | .PP |
1516 | will \- as long as you either keep the memory contents intact, or call |
1385 | .Vb 5 |
1517 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1386 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1518 | .IP "started/running/active" 4 |
1387 | \& { |
1519 | .IX Item "started/running/active" |
1388 | \& struct my_io *w = (struct my_io *)w_; |
1520 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1389 | \& ... |
1521 | property of the event loop, and is actively waiting for events. While in |
1390 | \& } |
1522 | this state it cannot be accessed (except in a few documented ways), moved, |
1391 | .Ve |
1523 | freed or anything else \- the only legal thing is to keep a pointer to it, |
1392 | .PP |
1524 | and call libev functions on it that are documented to work on active watchers. |
1393 | More interesting and less C\-conformant ways of casting your callback type |
1525 | .IP "pending" 4 |
1394 | instead have been omitted. |
1526 | .IX Item "pending" |
1395 | .PP |
1527 | If a watcher is active and libev determines that an event it is interested |
1396 | Another common scenario is to use some data structure with multiple |
1528 | in has occurred (such as a timer expiring), it will become pending. It will |
1397 | embedded watchers: |
1529 | stay in this pending state until either it is stopped or its callback is |
1398 | .PP |
1530 | about to be invoked, so it is not normally pending inside the watcher |
1399 | .Vb 6 |
1531 | callback. |
1400 | \& struct my_biggy |
1532 | .Sp |
1401 | \& { |
1533 | The watcher might or might not be active while it is pending (for example, |
1402 | \& int some_data; |
1534 | an expired non-repeating timer can be pending but no longer active). If it |
1403 | \& ev_timer t1; |
1535 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
1404 | \& ev_timer t2; |
1536 | but it is still property of the event loop at this time, so cannot be |
1405 | \& } |
1537 | moved, freed or reused. And if it is active the rules described in the |
1406 | .Ve |
1538 | previous item still apply. |
1407 | .PP |
1539 | .Sp |
1408 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
1540 | It is also possible to feed an event on a watcher that is not active (e.g. |
1409 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
1541 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1410 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
1542 | active. |
1411 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
1543 | .IP "stopped" 4 |
1412 | programmers): |
1544 | .IX Item "stopped" |
1413 | .PP |
1545 | A watcher can be stopped implicitly by libev (in which case it might still |
1414 | .Vb 1 |
1546 | be pending), or explicitly by calling its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. The |
1415 | \& #include <stddef.h> |
1547 | latter will clear any pending state the watcher might be in, regardless |
1416 | \& |
1548 | of whether it was active or not, so stopping a watcher explicitly before |
1417 | \& static void |
1549 | freeing it is often a good idea. |
1418 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1550 | .Sp |
1419 | \& { |
1551 | While stopped (and not pending) the watcher is essentially in the |
1420 | \& struct my_biggy big = (struct my_biggy *) |
1552 | initialised state, that is, it can be reused, moved, modified in any way |
1421 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1553 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1422 | \& } |
1554 | it again). |
1423 | \& |
|
|
1424 | \& static void |
|
|
1425 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1426 | \& { |
|
|
1427 | \& struct my_biggy big = (struct my_biggy *) |
|
|
1428 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1429 | \& } |
|
|
1430 | .Ve |
|
|
1431 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1555 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1432 | .IX Subsection "WATCHER PRIORITY MODELS" |
1556 | .IX Subsection "WATCHER PRIORITY MODELS" |
1433 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1557 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1434 | integers that influence the ordering of event callback invocation |
1558 | integers that influence the ordering of event callback invocation |
1435 | between watchers in some way, all else being equal. |
1559 | between watchers in some way, all else being equal. |
… | |
… | |
1477 | .PP |
1601 | .PP |
1478 | For example, to emulate how many other event libraries handle priorities, |
1602 | For example, to emulate how many other event libraries handle priorities, |
1479 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
1603 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
1480 | the normal watcher callback, you just start the idle watcher. The real |
1604 | the normal watcher callback, you just start the idle watcher. The real |
1481 | processing is done in the idle watcher callback. This causes libev to |
1605 | processing is done in the idle watcher callback. This causes libev to |
1482 | continously poll and process kernel event data for the watcher, but when |
1606 | continuously poll and process kernel event data for the watcher, but when |
1483 | the lock-out case is known to be rare (which in turn is rare :), this is |
1607 | the lock-out case is known to be rare (which in turn is rare :), this is |
1484 | workable. |
1608 | workable. |
1485 | .PP |
1609 | .PP |
1486 | Usually, however, the lock-out model implemented that way will perform |
1610 | Usually, however, the lock-out model implemented that way will perform |
1487 | miserably under the type of load it was designed to handle. In that case, |
1611 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1502 | \& { |
1626 | \& { |
1503 | \& // stop the I/O watcher, we received the event, but |
1627 | \& // stop the I/O watcher, we received the event, but |
1504 | \& // are not yet ready to handle it. |
1628 | \& // are not yet ready to handle it. |
1505 | \& ev_io_stop (EV_A_ w); |
1629 | \& ev_io_stop (EV_A_ w); |
1506 | \& |
1630 | \& |
1507 | \& // start the idle watcher to ahndle the actual event. |
1631 | \& // start the idle watcher to handle the actual event. |
1508 | \& // it will not be executed as long as other watchers |
1632 | \& // it will not be executed as long as other watchers |
1509 | \& // with the default priority are receiving events. |
1633 | \& // with the default priority are receiving events. |
1510 | \& ev_idle_start (EV_A_ &idle); |
1634 | \& ev_idle_start (EV_A_ &idle); |
1511 | \& } |
1635 | \& } |
1512 | \& |
1636 | \& |
… | |
… | |
1560 | In general you can register as many read and/or write event watchers per |
1684 | In general you can register as many read and/or write event watchers per |
1561 | fd as you want (as long as you don't confuse yourself). Setting all file |
1685 | fd as you want (as long as you don't confuse yourself). Setting all file |
1562 | descriptors to non-blocking mode is also usually a good idea (but not |
1686 | descriptors to non-blocking mode is also usually a good idea (but not |
1563 | required if you know what you are doing). |
1687 | required if you know what you are doing). |
1564 | .PP |
1688 | .PP |
1565 | If you cannot use non-blocking mode, then force the use of a |
|
|
1566 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1567 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1568 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1569 | files) \- libev doesn't guarentee any specific behaviour in that case. |
|
|
1570 | .PP |
|
|
1571 | Another thing you have to watch out for is that it is quite easy to |
1689 | Another thing you have to watch out for is that it is quite easy to |
1572 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1690 | receive \*(L"spurious\*(R" readiness notifications, that is, your callback might |
1573 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1691 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1574 | because there is no data. Not only are some backends known to create a |
1692 | because there is no data. It is very easy to get into this situation even |
1575 | lot of those (for example Solaris ports), it is very easy to get into |
1693 | with a relatively standard program structure. Thus it is best to always |
1576 | this situation even with a relatively standard program structure. Thus |
1694 | use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning \f(CW\*(C`EAGAIN\*(C'\fR is far |
1577 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1578 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1695 | preferable to a program hanging until some data arrives. |
1579 | .PP |
1696 | .PP |
1580 | If you cannot run the fd in non-blocking mode (for example you should |
1697 | If you cannot run the fd in non-blocking mode (for example you should |
1581 | not play around with an Xlib connection), then you have to separately |
1698 | not play around with an Xlib connection), then you have to separately |
1582 | re-test whether a file descriptor is really ready with a known-to-be good |
1699 | re-test whether a file descriptor is really ready with a known-to-be good |
1583 | interface such as poll (fortunately in our Xlib example, Xlib already |
1700 | interface such as poll (fortunately in the case of Xlib, it already does |
1584 | does this on its own, so its quite safe to use). Some people additionally |
1701 | this on its own, so its quite safe to use). Some people additionally |
1585 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1702 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1586 | indefinitely. |
1703 | indefinitely. |
1587 | .PP |
1704 | .PP |
1588 | But really, best use non-blocking mode. |
1705 | But really, best use non-blocking mode. |
1589 | .PP |
1706 | .PP |
… | |
… | |
1619 | .PP |
1736 | .PP |
1620 | There is no workaround possible except not registering events |
1737 | There is no workaround possible except not registering events |
1621 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1738 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1622 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1739 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1623 | .PP |
1740 | .PP |
|
|
1741 | \fIThe special problem of files\fR |
|
|
1742 | .IX Subsection "The special problem of files" |
|
|
1743 | .PP |
|
|
1744 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
|
|
1745 | representing files, and expect it to become ready when their program |
|
|
1746 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1747 | .PP |
|
|
1748 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
|
|
1749 | notification as soon as the kernel knows whether and how much data is |
|
|
1750 | there, and in the case of open files, that's always the case, so you |
|
|
1751 | always get a readiness notification instantly, and your read (or possibly |
|
|
1752 | write) will still block on the disk I/O. |
|
|
1753 | .PP |
|
|
1754 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1755 | devices and so on, there is another party (the sender) that delivers data |
|
|
1756 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1757 | will not send data on its own, simply because it doesn't know what you |
|
|
1758 | wish to read \- you would first have to request some data. |
|
|
1759 | .PP |
|
|
1760 | Since files are typically not-so-well supported by advanced notification |
|
|
1761 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
|
|
1762 | to files, even though you should not use it. The reason for this is |
|
|
1763 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
|
|
1764 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1765 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
|
|
1766 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
|
|
1767 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1768 | it \*(L"just works\*(R" instead of freezing. |
|
|
1769 | .PP |
|
|
1770 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1771 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
|
|
1772 | when you rarely read from a file instead of from a socket, and want to |
|
|
1773 | reuse the same code path. |
|
|
1774 | .PP |
1624 | \fIThe special problem of fork\fR |
1775 | \fIThe special problem of fork\fR |
1625 | .IX Subsection "The special problem of fork" |
1776 | .IX Subsection "The special problem of fork" |
1626 | .PP |
1777 | .PP |
1627 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1778 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1628 | useless behaviour. Libev fully supports fork, but needs to be told about |
1779 | useless behaviour. Libev fully supports fork, but needs to be told about |
1629 | it in the child. |
1780 | it in the child if you want to continue to use it in the child. |
1630 | .PP |
1781 | .PP |
1631 | To support fork in your programs, you either have to call |
1782 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1632 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1783 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1633 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1784 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1634 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1635 | .PP |
1785 | .PP |
1636 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1786 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1637 | .IX Subsection "The special problem of SIGPIPE" |
1787 | .IX Subsection "The special problem of SIGPIPE" |
1638 | .PP |
1788 | .PP |
1639 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1789 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
… | |
… | |
1642 | this is sensible behaviour, for daemons, this is usually undesirable. |
1792 | this is sensible behaviour, for daemons, this is usually undesirable. |
1643 | .PP |
1793 | .PP |
1644 | So when you encounter spurious, unexplained daemon exits, make sure you |
1794 | So when you encounter spurious, unexplained daemon exits, make sure you |
1645 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1795 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1646 | somewhere, as that would have given you a big clue). |
1796 | somewhere, as that would have given you a big clue). |
|
|
1797 | .PP |
|
|
1798 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
|
|
1799 | .IX Subsection "The special problem of accept()ing when you can't" |
|
|
1800 | .PP |
|
|
1801 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
|
|
1802 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1803 | connection from the pending queue in all error cases. |
|
|
1804 | .PP |
|
|
1805 | For example, larger servers often run out of file descriptors (because |
|
|
1806 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
|
|
1807 | rejecting the connection, leading to libev signalling readiness on |
|
|
1808 | the next iteration again (the connection still exists after all), and |
|
|
1809 | typically causing the program to loop at 100% \s-1CPU\s0 usage. |
|
|
1810 | .PP |
|
|
1811 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1812 | operating systems, there is usually little the app can do to remedy the |
|
|
1813 | situation, and no known thread-safe method of removing the connection to |
|
|
1814 | cope with overload is known (to me). |
|
|
1815 | .PP |
|
|
1816 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1817 | \&\- when the program encounters an overload, it will just loop until the |
|
|
1818 | situation is over. While this is a form of busy waiting, no \s-1OS\s0 offers an |
|
|
1819 | event-based way to handle this situation, so it's the best one can do. |
|
|
1820 | .PP |
|
|
1821 | A better way to handle the situation is to log any errors other than |
|
|
1822 | \&\f(CW\*(C`EAGAIN\*(C'\fR and \f(CW\*(C`EWOULDBLOCK\*(C'\fR, making sure not to flood the log with such |
|
|
1823 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1824 | what could be wrong (\*(L"raise the ulimit!\*(R"). For extra points one could stop |
|
|
1825 | the \f(CW\*(C`ev_io\*(C'\fR watcher on the listening fd \*(L"for a while\*(R", which reduces \s-1CPU\s0 |
|
|
1826 | usage. |
|
|
1827 | .PP |
|
|
1828 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1829 | descriptor for overload situations (e.g. by opening \fI/dev/null\fR), and |
|
|
1830 | when you run into \f(CW\*(C`ENFILE\*(C'\fR or \f(CW\*(C`EMFILE\*(C'\fR, close it, run \f(CW\*(C`accept\*(C'\fR, |
|
|
1831 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1832 | clients under typical overload conditions. |
|
|
1833 | .PP |
|
|
1834 | The last way to handle it is to simply log the error and \f(CW\*(C`exit\*(C'\fR, as |
|
|
1835 | is often done with \f(CW\*(C`malloc\*(C'\fR failures, but this results in an easy |
|
|
1836 | opportunity for a DoS attack. |
1647 | .PP |
1837 | .PP |
1648 | \fIWatcher-Specific Functions\fR |
1838 | \fIWatcher-Specific Functions\fR |
1649 | .IX Subsection "Watcher-Specific Functions" |
1839 | .IX Subsection "Watcher-Specific Functions" |
1650 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1840 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1651 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1841 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
… | |
… | |
1681 | \& ... |
1871 | \& ... |
1682 | \& struct ev_loop *loop = ev_default_init (0); |
1872 | \& struct ev_loop *loop = ev_default_init (0); |
1683 | \& ev_io stdin_readable; |
1873 | \& ev_io stdin_readable; |
1684 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1874 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1685 | \& ev_io_start (loop, &stdin_readable); |
1875 | \& ev_io_start (loop, &stdin_readable); |
1686 | \& ev_loop (loop, 0); |
1876 | \& ev_run (loop, 0); |
1687 | .Ve |
1877 | .Ve |
1688 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1878 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1689 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1879 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1690 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1880 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1691 | Timer watchers are simple relative timers that generate an event after a |
1881 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1697 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1887 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1698 | monotonic clock option helps a lot here). |
1888 | monotonic clock option helps a lot here). |
1699 | .PP |
1889 | .PP |
1700 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1890 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1701 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1891 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1702 | might introduce a small delay). If multiple timers become ready during the |
1892 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1893 | early\*(R", below). If multiple timers become ready during the same loop |
1703 | same loop iteration then the ones with earlier time-out values are invoked |
1894 | iteration then the ones with earlier time-out values are invoked before |
1704 | before ones of the same priority with later time-out values (but this is |
1895 | ones of the same priority with later time-out values (but this is no |
1705 | no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1896 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1706 | .PP |
1897 | .PP |
1707 | \fIBe smart about timeouts\fR |
1898 | \fIBe smart about timeouts\fR |
1708 | .IX Subsection "Be smart about timeouts" |
1899 | .IX Subsection "Be smart about timeouts" |
1709 | .PP |
1900 | .PP |
1710 | Many real-world problems involve some kind of timeout, usually for error |
1901 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1792 | .Sp |
1983 | .Sp |
1793 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1984 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1794 | but remember the time of last activity, and check for a real timeout only |
1985 | but remember the time of last activity, and check for a real timeout only |
1795 | within the callback: |
1986 | within the callback: |
1796 | .Sp |
1987 | .Sp |
1797 | .Vb 1 |
1988 | .Vb 3 |
|
|
1989 | \& ev_tstamp timeout = 60.; |
1798 | \& ev_tstamp last_activity; // time of last activity |
1990 | \& ev_tstamp last_activity; // time of last activity |
|
|
1991 | \& ev_timer timer; |
1799 | \& |
1992 | \& |
1800 | \& static void |
1993 | \& static void |
1801 | \& callback (EV_P_ ev_timer *w, int revents) |
1994 | \& callback (EV_P_ ev_timer *w, int revents) |
1802 | \& { |
1995 | \& { |
1803 | \& ev_tstamp now = ev_now (EV_A); |
1996 | \& // calculate when the timeout would happen |
1804 | \& ev_tstamp timeout = last_activity + 60.; |
1997 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1805 | \& |
1998 | \& |
1806 | \& // if last_activity + 60. is older than now, we did time out |
1999 | \& // if negative, it means we the timeout already occured |
1807 | \& if (timeout < now) |
2000 | \& if (after < 0.) |
1808 | \& { |
2001 | \& { |
1809 | \& // timeout occured, take action |
2002 | \& // timeout occurred, take action |
1810 | \& } |
2003 | \& } |
1811 | \& else |
2004 | \& else |
1812 | \& { |
2005 | \& { |
1813 | \& // callback was invoked, but there was some activity, re\-arm |
2006 | \& // callback was invoked, but there was some recent |
1814 | \& // the watcher to fire in last_activity + 60, which is |
2007 | \& // activity. simply restart the timer to time out |
1815 | \& // guaranteed to be in the future, so "again" is positive: |
2008 | \& // after "after" seconds, which is the earliest time |
1816 | \& w\->repeat = timeout \- now; |
2009 | \& // the timeout can occur. |
|
|
2010 | \& ev_timer_set (w, after, 0.); |
1817 | \& ev_timer_again (EV_A_ w); |
2011 | \& ev_timer_start (EV_A_ w); |
1818 | \& } |
2012 | \& } |
1819 | \& } |
2013 | \& } |
1820 | .Ve |
2014 | .Ve |
1821 | .Sp |
2015 | .Sp |
1822 | To summarise the callback: first calculate the real timeout (defined |
2016 | To summarise the callback: first calculate in how many seconds the |
1823 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2017 | timeout will occur (by calculating the absolute time when it would occur, |
1824 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2018 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1825 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2019 | (EV_A)\*(C'\fR from that). |
1826 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1827 | a timeout then. |
|
|
1828 | .Sp |
2020 | .Sp |
1829 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2021 | If this value is negative, then we are already past the timeout, i.e. we |
1830 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2022 | timed out, and need to do whatever is needed in this case. |
|
|
2023 | .Sp |
|
|
2024 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2025 | and simply start the timer with this timeout value. |
|
|
2026 | .Sp |
|
|
2027 | In other words, each time the callback is invoked it will check whether |
|
|
2028 | the timeout cocured. If not, it will simply reschedule itself to check |
|
|
2029 | again at the earliest time it could time out. Rinse. Repeat. |
1831 | .Sp |
2030 | .Sp |
1832 | This scheme causes more callback invocations (about one every 60 seconds |
2031 | This scheme causes more callback invocations (about one every 60 seconds |
1833 | minus half the average time between activity), but virtually no calls to |
2032 | minus half the average time between activity), but virtually no calls to |
1834 | libev to change the timeout. |
2033 | libev to change the timeout. |
1835 | .Sp |
2034 | .Sp |
1836 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2035 | To start the machinery, simply initialise the watcher and set |
1837 | to the current time (meaning we just have some activity :), then call the |
2036 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
1838 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2037 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2038 | the timer: |
1839 | .Sp |
2039 | .Sp |
1840 | .Vb 3 |
2040 | .Vb 3 |
|
|
2041 | \& last_activity = ev_now (EV_A); |
1841 | \& ev_init (timer, callback); |
2042 | \& ev_init (&timer, callback); |
1842 | \& last_activity = ev_now (loop); |
2043 | \& callback (EV_A_ &timer, 0); |
1843 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1844 | .Ve |
2044 | .Ve |
1845 | .Sp |
2045 | .Sp |
1846 | And when there is some activity, simply store the current time in |
2046 | When there is some activity, simply store the current time in |
1847 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2047 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
1848 | .Sp |
2048 | .Sp |
1849 | .Vb 1 |
2049 | .Vb 2 |
|
|
2050 | \& if (activity detected) |
1850 | \& last_actiivty = ev_now (loop); |
2051 | \& last_activity = ev_now (EV_A); |
|
|
2052 | .Ve |
|
|
2053 | .Sp |
|
|
2054 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2055 | providing a new value, stopping the timer and calling the callback, which |
|
|
2056 | will agaion do the right thing (for example, time out immediately :). |
|
|
2057 | .Sp |
|
|
2058 | .Vb 3 |
|
|
2059 | \& timeout = new_value; |
|
|
2060 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2061 | \& callback (EV_A_ &timer, 0); |
1851 | .Ve |
2062 | .Ve |
1852 | .Sp |
2063 | .Sp |
1853 | This technique is slightly more complex, but in most cases where the |
2064 | This technique is slightly more complex, but in most cases where the |
1854 | time-out is unlikely to be triggered, much more efficient. |
2065 | time-out is unlikely to be triggered, much more efficient. |
1855 | .Sp |
|
|
1856 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1857 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1858 | fix things for you. |
|
|
1859 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2066 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
1860 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2067 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
1861 | If there is not one request, but many thousands (millions...), all |
2068 | If there is not one request, but many thousands (millions...), all |
1862 | employing some kind of timeout with the same timeout value, then one can |
2069 | employing some kind of timeout with the same timeout value, then one can |
1863 | do even better: |
2070 | do even better: |
… | |
… | |
1887 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2094 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1888 | rather complicated, but extremely efficient, something that really pays |
2095 | rather complicated, but extremely efficient, something that really pays |
1889 | off after the first million or so of active timers, i.e. it's usually |
2096 | off after the first million or so of active timers, i.e. it's usually |
1890 | overkill :) |
2097 | overkill :) |
1891 | .PP |
2098 | .PP |
|
|
2099 | \fIThe special problem of being too early\fR |
|
|
2100 | .IX Subsection "The special problem of being too early" |
|
|
2101 | .PP |
|
|
2102 | If you ask a timer to call your callback after three seconds, then |
|
|
2103 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2104 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2105 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2106 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2107 | .PP |
|
|
2108 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2109 | delay has occurred, but cannot guarantee this. |
|
|
2110 | .PP |
|
|
2111 | A less obvious failure mode is calling your callback too early: many event |
|
|
2112 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2113 | this can cause your callback to be invoked much earlier than you would |
|
|
2114 | expect. |
|
|
2115 | .PP |
|
|
2116 | To see why, imagine a system with a clock that only offers full second |
|
|
2117 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2118 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2119 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2120 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2121 | .PP |
|
|
2122 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2123 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2124 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2125 | intentions. |
|
|
2126 | .PP |
|
|
2127 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2128 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2129 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2130 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2131 | .PP |
|
|
2132 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2133 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2134 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2135 | late\*(R" side of things. |
|
|
2136 | .PP |
1892 | \fIThe special problem of time updates\fR |
2137 | \fIThe special problem of time updates\fR |
1893 | .IX Subsection "The special problem of time updates" |
2138 | .IX Subsection "The special problem of time updates" |
1894 | .PP |
2139 | .PP |
1895 | Establishing the current time is a costly operation (it usually takes at |
2140 | Establishing the current time is a costly operation (it usually takes |
1896 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2141 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
1897 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
2142 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
1898 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2143 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
1899 | lots of events in one iteration. |
2144 | lots of events in one iteration. |
1900 | .PP |
2145 | .PP |
1901 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2146 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1902 | time. This is usually the right thing as this timestamp refers to the time |
2147 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1909 | .Ve |
2154 | .Ve |
1910 | .PP |
2155 | .PP |
1911 | If the event loop is suspended for a long time, you can also force an |
2156 | If the event loop is suspended for a long time, you can also force an |
1912 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2157 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1913 | ()\*(C'\fR. |
2158 | ()\*(C'\fR. |
|
|
2159 | .PP |
|
|
2160 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2161 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2162 | .PP |
|
|
2163 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2164 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2165 | jumps). |
|
|
2166 | .PP |
|
|
2167 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2168 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2169 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2170 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2171 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2172 | .PP |
|
|
2173 | The moral of this is to only compare libev-related timestamps with |
|
|
2174 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2175 | a second or so. |
|
|
2176 | .PP |
|
|
2177 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2178 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2179 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2180 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2181 | .PP |
|
|
2182 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2183 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2184 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2185 | .PP |
|
|
2186 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2187 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2188 | exactly the right behaviour. |
|
|
2189 | .PP |
|
|
2190 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2191 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2192 | time, where your comparisons will always generate correct results. |
1914 | .PP |
2193 | .PP |
1915 | \fIThe special problems of suspended animation\fR |
2194 | \fIThe special problems of suspended animation\fR |
1916 | .IX Subsection "The special problems of suspended animation" |
2195 | .IX Subsection "The special problems of suspended animation" |
1917 | .PP |
2196 | .PP |
1918 | When you leave the server world it is quite customary to hit machines that |
2197 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
1962 | trigger at exactly 10 second intervals. If, however, your program cannot |
2241 | trigger at exactly 10 second intervals. If, however, your program cannot |
1963 | keep up with the timer (because it takes longer than those 10 seconds to |
2242 | keep up with the timer (because it takes longer than those 10 seconds to |
1964 | do stuff) the timer will not fire more than once per event loop iteration. |
2243 | do stuff) the timer will not fire more than once per event loop iteration. |
1965 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2244 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1966 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2245 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1967 | This will act as if the timer timed out and restart it again if it is |
2246 | This will act as if the timer timed out, and restarts it again if it is |
1968 | repeating. The exact semantics are: |
2247 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2248 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
1969 | .Sp |
2249 | .Sp |
|
|
2250 | The exact semantics are as in the following rules, all of which will be |
|
|
2251 | applied to the watcher: |
|
|
2252 | .RS 4 |
1970 | If the timer is pending, its pending status is cleared. |
2253 | .IP "If the timer is pending, the pending status is always cleared." 4 |
1971 | .Sp |
2254 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2255 | .PD 0 |
1972 | If the timer is started but non-repeating, stop it (as if it timed out). |
2256 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
1973 | .Sp |
2257 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
1974 | If the timer is repeating, either start it if necessary (with the |
2258 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
1975 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2259 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2260 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2261 | .RE |
|
|
2262 | .RS 4 |
|
|
2263 | .PD |
1976 | .Sp |
2264 | .Sp |
1977 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2265 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1978 | usage example. |
2266 | usage example. |
|
|
2267 | .RE |
1979 | .IP "ev_timer_remaining (loop, ev_timer *)" 4 |
2268 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
1980 | .IX Item "ev_timer_remaining (loop, ev_timer *)" |
2269 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
1981 | Returns the remaining time until a timer fires. If the timer is active, |
2270 | Returns the remaining time until a timer fires. If the timer is active, |
1982 | then this time is relative to the current event loop time, otherwise it's |
2271 | then this time is relative to the current event loop time, otherwise it's |
1983 | the timeout value currently configured. |
2272 | the timeout value currently configured. |
1984 | .Sp |
2273 | .Sp |
1985 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
2274 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
1986 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR |
2275 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remaining\*(C'\fR |
1987 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
2276 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
1988 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
2277 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
1989 | too), and so on. |
2278 | too), and so on. |
1990 | .IP "ev_tstamp repeat [read\-write]" 4 |
2279 | .IP "ev_tstamp repeat [read\-write]" 4 |
1991 | .IX Item "ev_tstamp repeat [read-write]" |
2280 | .IX Item "ev_tstamp repeat [read-write]" |
… | |
… | |
2021 | \& } |
2310 | \& } |
2022 | \& |
2311 | \& |
2023 | \& ev_timer mytimer; |
2312 | \& ev_timer mytimer; |
2024 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2313 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2025 | \& ev_timer_again (&mytimer); /* start timer */ |
2314 | \& ev_timer_again (&mytimer); /* start timer */ |
2026 | \& ev_loop (loop, 0); |
2315 | \& ev_run (loop, 0); |
2027 | \& |
2316 | \& |
2028 | \& // and in some piece of code that gets executed on any "activity": |
2317 | \& // and in some piece of code that gets executed on any "activity": |
2029 | \& // reset the timeout to start ticking again at 10 seconds |
2318 | \& // reset the timeout to start ticking again at 10 seconds |
2030 | \& ev_timer_again (&mytimer); |
2319 | \& ev_timer_again (&mytimer); |
2031 | .Ve |
2320 | .Ve |
… | |
… | |
2057 | .PP |
2346 | .PP |
2058 | As with timers, the callback is guaranteed to be invoked only when the |
2347 | As with timers, the callback is guaranteed to be invoked only when the |
2059 | point in time where it is supposed to trigger has passed. If multiple |
2348 | point in time where it is supposed to trigger has passed. If multiple |
2060 | timers become ready during the same loop iteration then the ones with |
2349 | timers become ready during the same loop iteration then the ones with |
2061 | earlier time-out values are invoked before ones with later time-out values |
2350 | earlier time-out values are invoked before ones with later time-out values |
2062 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
2351 | (but this is no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
2063 | .PP |
2352 | .PP |
2064 | \fIWatcher-Specific Functions and Data Members\fR |
2353 | \fIWatcher-Specific Functions and Data Members\fR |
2065 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2354 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2066 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
2355 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
2067 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
2356 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
… | |
… | |
2103 | .Sp |
2392 | .Sp |
2104 | Another way to think about it (for the mathematically inclined) is that |
2393 | Another way to think about it (for the mathematically inclined) is that |
2105 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2394 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2106 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2395 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2107 | .Sp |
2396 | .Sp |
2108 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2397 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2109 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2398 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2110 | this value, and in fact is often specified as zero. |
2399 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2400 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2401 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2402 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2111 | .Sp |
2403 | .Sp |
2112 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2404 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2113 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2405 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2114 | will of course deteriorate. Libev itself tries to be exact to be about one |
2406 | will of course deteriorate. Libev itself tries to be exact to be about one |
2115 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2407 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2194 | system time is divisible by 3600. The callback invocation times have |
2486 | system time is divisible by 3600. The callback invocation times have |
2195 | potentially a lot of jitter, but good long-term stability. |
2487 | potentially a lot of jitter, but good long-term stability. |
2196 | .PP |
2488 | .PP |
2197 | .Vb 5 |
2489 | .Vb 5 |
2198 | \& static void |
2490 | \& static void |
2199 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2491 | \& clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2200 | \& { |
2492 | \& { |
2201 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2493 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2202 | \& } |
2494 | \& } |
2203 | \& |
2495 | \& |
2204 | \& ev_periodic hourly_tick; |
2496 | \& ev_periodic hourly_tick; |
… | |
… | |
2231 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
2523 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
2232 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2524 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2233 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2525 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2234 | Signal watchers will trigger an event when the process receives a specific |
2526 | Signal watchers will trigger an event when the process receives a specific |
2235 | signal one or more times. Even though signals are very asynchronous, libev |
2527 | signal one or more times. Even though signals are very asynchronous, libev |
2236 | will try it's best to deliver signals synchronously, i.e. as part of the |
2528 | will try its best to deliver signals synchronously, i.e. as part of the |
2237 | normal event processing, like any other event. |
2529 | normal event processing, like any other event. |
2238 | .PP |
2530 | .PP |
2239 | If you want signals to be delivered truly asynchronously, just use |
2531 | If you want signals to be delivered truly asynchronously, just use |
2240 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
2532 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
2241 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
2533 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
… | |
… | |
2249 | .PP |
2541 | .PP |
2250 | When the first watcher gets started will libev actually register something |
2542 | When the first watcher gets started will libev actually register something |
2251 | with the kernel (thus it coexists with your own signal handlers as long as |
2543 | with the kernel (thus it coexists with your own signal handlers as long as |
2252 | you don't register any with libev for the same signal). |
2544 | you don't register any with libev for the same signal). |
2253 | .PP |
2545 | .PP |
2254 | Both the signal mask state (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal handler state |
|
|
2255 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2256 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2257 | and might or might not set or restore the installed signal handler. |
|
|
2258 | .PP |
|
|
2259 | If possible and supported, libev will install its handlers with |
2546 | If possible and supported, libev will install its handlers with |
2260 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2547 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2261 | not be unduly interrupted. If you have a problem with system calls getting |
2548 | not be unduly interrupted. If you have a problem with system calls getting |
2262 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2549 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2263 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
2550 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2551 | .PP |
|
|
2552 | \fIThe special problem of inheritance over fork/execve/pthread_create\fR |
|
|
2553 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
|
|
2554 | .PP |
|
|
2555 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
|
|
2556 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2557 | stopping it again), that is, libev might or might not block the signal, |
|
|
2558 | and might or might not set or restore the installed signal handler (but |
|
|
2559 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
|
|
2560 | .PP |
|
|
2561 | While this does not matter for the signal disposition (libev never |
|
|
2562 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
|
|
2563 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
|
|
2564 | certain signals to be blocked. |
|
|
2565 | .PP |
|
|
2566 | This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset |
|
|
2567 | the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good |
|
|
2568 | choice usually). |
|
|
2569 | .PP |
|
|
2570 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2571 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
|
|
2572 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2573 | .PP |
|
|
2574 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2575 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
|
|
2576 | the window of opportunity for problems, it will not go away, as libev |
|
|
2577 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
|
|
2578 | .PP |
|
|
2579 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
|
|
2580 | you expect it to be empty, you have a race condition in your code\fR. This |
|
|
2581 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2582 | .PP |
|
|
2583 | \fIThe special problem of threads signal handling\fR |
|
|
2584 | .IX Subsection "The special problem of threads signal handling" |
|
|
2585 | .PP |
|
|
2586 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2587 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2588 | threads in a process block signals, which is hard to achieve. |
|
|
2589 | .PP |
|
|
2590 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2591 | for the same signals), you can tackle this problem by globally blocking |
|
|
2592 | all signals before creating any threads (or creating them with a fully set |
|
|
2593 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2594 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2595 | these signals. You can pass on any signals that libev might be interested |
|
|
2596 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
2264 | .PP |
2597 | .PP |
2265 | \fIWatcher-Specific Functions and Data Members\fR |
2598 | \fIWatcher-Specific Functions and Data Members\fR |
2266 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2599 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2267 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2600 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2268 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2601 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
2283 | .PP |
2616 | .PP |
2284 | .Vb 5 |
2617 | .Vb 5 |
2285 | \& static void |
2618 | \& static void |
2286 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2619 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2287 | \& { |
2620 | \& { |
2288 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2621 | \& ev_break (loop, EVBREAK_ALL); |
2289 | \& } |
2622 | \& } |
2290 | \& |
2623 | \& |
2291 | \& ev_signal signal_watcher; |
2624 | \& ev_signal signal_watcher; |
2292 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2625 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2293 | \& ev_signal_start (loop, &signal_watcher); |
2626 | \& ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2678 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3011 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2679 | Prepare and check watchers are usually (but not always) used in pairs: |
3012 | Prepare and check watchers are usually (but not always) used in pairs: |
2680 | prepare watchers get invoked before the process blocks and check watchers |
3013 | prepare watchers get invoked before the process blocks and check watchers |
2681 | afterwards. |
3014 | afterwards. |
2682 | .PP |
3015 | .PP |
2683 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
3016 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
2684 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3017 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2685 | watchers. Other loops than the current one are fine, however. The |
3018 | watchers. Other loops than the current one are fine, however. The |
2686 | rationale behind this is that you do not need to check for recursion in |
3019 | rationale behind this is that you do not need to check for recursion in |
2687 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3020 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2688 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3021 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
… | |
… | |
2860 | \& |
3193 | \& |
2861 | \& if (timeout >= 0) |
3194 | \& if (timeout >= 0) |
2862 | \& // create/start timer |
3195 | \& // create/start timer |
2863 | \& |
3196 | \& |
2864 | \& // poll |
3197 | \& // poll |
2865 | \& ev_loop (EV_A_ 0); |
3198 | \& ev_run (EV_A_ 0); |
2866 | \& |
3199 | \& |
2867 | \& // stop timer again |
3200 | \& // stop timer again |
2868 | \& if (timeout >= 0) |
3201 | \& if (timeout >= 0) |
2869 | \& ev_timer_stop (EV_A_ &to); |
3202 | \& ev_timer_stop (EV_A_ &to); |
2870 | \& |
3203 | \& |
… | |
… | |
2948 | to invoke it (it will continue to be called until the sweep has been done, |
3281 | to invoke it (it will continue to be called until the sweep has been done, |
2949 | if you do not want that, you need to temporarily stop the embed watcher). |
3282 | if you do not want that, you need to temporarily stop the embed watcher). |
2950 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
3283 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2951 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
3284 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2952 | Make a single, non-blocking sweep over the embedded loop. This works |
3285 | Make a single, non-blocking sweep over the embedded loop. This works |
2953 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
3286 | similarly to \f(CW\*(C`ev_run (embedded_loop, EVRUN_NOWAIT)\*(C'\fR, but in the most |
2954 | appropriate way for embedded loops. |
3287 | appropriate way for embedded loops. |
2955 | .IP "struct ev_loop *other [read\-only]" 4 |
3288 | .IP "struct ev_loop *other [read\-only]" 4 |
2956 | .IX Item "struct ev_loop *other [read-only]" |
3289 | .IX Item "struct ev_loop *other [read-only]" |
2957 | The embedded event loop. |
3290 | The embedded event loop. |
2958 | .PP |
3291 | .PP |
… | |
… | |
3020 | handlers will be invoked, too, of course. |
3353 | handlers will be invoked, too, of course. |
3021 | .PP |
3354 | .PP |
3022 | \fIThe special problem of life after fork \- how is it possible?\fR |
3355 | \fIThe special problem of life after fork \- how is it possible?\fR |
3023 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3356 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3024 | .PP |
3357 | .PP |
3025 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
3358 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3026 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3359 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3027 | sequence should be handled by libev without any problems. |
3360 | sequence should be handled by libev without any problems. |
3028 | .PP |
3361 | .PP |
3029 | This changes when the application actually wants to do event handling |
3362 | This changes when the application actually wants to do event handling |
3030 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3363 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3046 | disadvantage of having to use multiple event loops (which do not support |
3379 | disadvantage of having to use multiple event loops (which do not support |
3047 | signal watchers). |
3380 | signal watchers). |
3048 | .PP |
3381 | .PP |
3049 | When this is not possible, or you want to use the default loop for |
3382 | When this is not possible, or you want to use the default loop for |
3050 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
3383 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
3051 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
3384 | \&\f(CW\*(C`ev_loop_destroy (EV_DEFAULT)\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. |
3052 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
3385 | Destroying the default loop will \*(L"orphan\*(R" (not stop) all registered |
3053 | have to be careful not to execute code that modifies those watchers. Note |
3386 | watchers, so you have to be careful not to execute code that modifies |
3054 | also that in that case, you have to re-register any signal watchers. |
3387 | those watchers. Note also that in that case, you have to re-register any |
|
|
3388 | signal watchers. |
3055 | .PP |
3389 | .PP |
3056 | \fIWatcher-Specific Functions and Data Members\fR |
3390 | \fIWatcher-Specific Functions and Data Members\fR |
3057 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3391 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3058 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3392 | .IP "ev_fork_init (ev_fork *, callback)" 4 |
3059 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3393 | .IX Item "ev_fork_init (ev_fork *, callback)" |
3060 | Initialises and configures the fork watcher \- it has no parameters of any |
3394 | Initialises and configures the fork watcher \- it has no parameters of any |
3061 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3395 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3062 | believe me. |
3396 | really. |
|
|
3397 | .ie n .SS """ev_cleanup"" \- even the best things end" |
|
|
3398 | .el .SS "\f(CWev_cleanup\fP \- even the best things end" |
|
|
3399 | .IX Subsection "ev_cleanup - even the best things end" |
|
|
3400 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3401 | by a call to \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
|
|
3402 | .PP |
|
|
3403 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3404 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3405 | program, worker threads and so on \- you just to make sure to destroy the |
|
|
3406 | loop when you want them to be invoked. |
|
|
3407 | .PP |
|
|
3408 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3409 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3410 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3411 | can call libev functions in the callback, except \f(CW\*(C`ev_cleanup_start\*(C'\fR. |
|
|
3412 | .PP |
|
|
3413 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3414 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3415 | .IP "ev_cleanup_init (ev_cleanup *, callback)" 4 |
|
|
3416 | .IX Item "ev_cleanup_init (ev_cleanup *, callback)" |
|
|
3417 | Initialises and configures the cleanup watcher \- it has no parameters of |
|
|
3418 | any kind. There is a \f(CW\*(C`ev_cleanup_set\*(C'\fR macro, but using it is utterly |
|
|
3419 | pointless, I assure you. |
|
|
3420 | .PP |
|
|
3421 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3422 | cleanup functions are called. |
|
|
3423 | .PP |
|
|
3424 | .Vb 5 |
|
|
3425 | \& static void |
|
|
3426 | \& program_exits (void) |
|
|
3427 | \& { |
|
|
3428 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3429 | \& } |
|
|
3430 | \& |
|
|
3431 | \& ... |
|
|
3432 | \& atexit (program_exits); |
|
|
3433 | .Ve |
3063 | .ie n .SS """ev_async"" \- how to wake up another event loop" |
3434 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3064 | .el .SS "\f(CWev_async\fP \- how to wake up another event loop" |
3435 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3065 | .IX Subsection "ev_async - how to wake up another event loop" |
3436 | .IX Subsection "ev_async - how to wake up an event loop" |
3066 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3437 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3067 | asynchronous sources such as signal handlers (as opposed to multiple event |
3438 | asynchronous sources such as signal handlers (as opposed to multiple event |
3068 | loops \- those are of course safe to use in different threads). |
3439 | loops \- those are of course safe to use in different threads). |
3069 | .PP |
3440 | .PP |
3070 | Sometimes, however, you need to wake up another event loop you do not |
3441 | Sometimes, however, you need to wake up an event loop you do not control, |
3071 | control, for example because it belongs to another thread. This is what |
3442 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
3072 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
3443 | watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you can signal |
3073 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
3444 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3074 | safe. |
|
|
3075 | .PP |
3445 | .PP |
3076 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3446 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3077 | too, are asynchronous in nature, and signals, too, will be compressed |
3447 | too, are asynchronous in nature, and signals, too, will be compressed |
3078 | (i.e. the number of callback invocations may be less than the number of |
3448 | (i.e. the number of callback invocations may be less than the number of |
3079 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3449 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3080 | .PP |
3450 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3081 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3451 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3082 | just the default loop. |
3452 | even without knowing which loop owns the signal. |
3083 | .PP |
3453 | .PP |
3084 | \fIQueueing\fR |
3454 | \fIQueueing\fR |
3085 | .IX Subsection "Queueing" |
3455 | .IX Subsection "Queueing" |
3086 | .PP |
3456 | .PP |
3087 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3457 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3088 | is that the author does not know of a simple (or any) algorithm for a |
3458 | is that the author does not know of a simple (or any) algorithm for a |
3089 | multiple-writer-single-reader queue that works in all cases and doesn't |
3459 | multiple-writer-single-reader queue that works in all cases and doesn't |
3090 | need elaborate support such as pthreads. |
3460 | need elaborate support such as pthreads or unportable memory access |
|
|
3461 | semantics. |
3091 | .PP |
3462 | .PP |
3092 | That means that if you want to queue data, you have to provide your own |
3463 | That means that if you want to queue data, you have to provide your own |
3093 | queue. But at least I can tell you how to implement locking around your |
3464 | queue. But at least I can tell you how to implement locking around your |
3094 | queue: |
3465 | queue: |
3095 | .IP "queueing from a signal handler context" 4 |
3466 | .IP "queueing from a signal handler context" 4 |
… | |
… | |
3173 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3544 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3174 | trust me. |
3545 | trust me. |
3175 | .IP "ev_async_send (loop, ev_async *)" 4 |
3546 | .IP "ev_async_send (loop, ev_async *)" 4 |
3176 | .IX Item "ev_async_send (loop, ev_async *)" |
3547 | .IX Item "ev_async_send (loop, ev_async *)" |
3177 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3548 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3178 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3549 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3550 | returns. |
|
|
3551 | .Sp |
3179 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3552 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3180 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3553 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3181 | section below on what exactly this means). |
3554 | embedding section below on what exactly this means). |
3182 | .Sp |
3555 | .Sp |
3183 | Note that, as with other watchers in libev, multiple events might get |
3556 | Note that, as with other watchers in libev, multiple events might get |
3184 | compressed into a single callback invocation (another way to look at this |
3557 | compressed into a single callback invocation (another way to look at |
3185 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3558 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3186 | reset when the event loop detects that). |
3559 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3187 | .Sp |
3560 | .Sp |
3188 | This call incurs the overhead of a system call only once per event loop |
3561 | This call incurs the overhead of at most one extra system call per event |
3189 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3562 | loop iteration, if the event loop is blocked, and no syscall at all if |
3190 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3563 | the event loop (or your program) is processing events. That means that |
|
|
3564 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3565 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3566 | zero) under load. |
3191 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3567 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3192 | .IX Item "bool = ev_async_pending (ev_async *)" |
3568 | .IX Item "bool = ev_async_pending (ev_async *)" |
3193 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3569 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3194 | watcher but the event has not yet been processed (or even noted) by the |
3570 | watcher but the event has not yet been processed (or even noted) by the |
3195 | event loop. |
3571 | event loop. |
… | |
… | |
3220 | .Sp |
3596 | .Sp |
3221 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3597 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3222 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3598 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3223 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3599 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3224 | .Sp |
3600 | .Sp |
3225 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3601 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and is |
3226 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3602 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3227 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3603 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3228 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3604 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3229 | a timeout and an io event at the same time \- you probably should give io |
3605 | a timeout and an io event at the same time \- you probably should give io |
3230 | events precedence. |
3606 | events precedence. |
3231 | .Sp |
3607 | .Sp |
3232 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3608 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
… | |
… | |
3234 | .Vb 7 |
3610 | .Vb 7 |
3235 | \& static void stdin_ready (int revents, void *arg) |
3611 | \& static void stdin_ready (int revents, void *arg) |
3236 | \& { |
3612 | \& { |
3237 | \& if (revents & EV_READ) |
3613 | \& if (revents & EV_READ) |
3238 | \& /* stdin might have data for us, joy! */; |
3614 | \& /* stdin might have data for us, joy! */; |
3239 | \& else if (revents & EV_TIMEOUT) |
3615 | \& else if (revents & EV_TIMER) |
3240 | \& /* doh, nothing entered */; |
3616 | \& /* doh, nothing entered */; |
3241 | \& } |
3617 | \& } |
3242 | \& |
3618 | \& |
3243 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3619 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3244 | .Ve |
3620 | .Ve |
3245 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
|
|
3246 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
|
|
3247 | Feeds the given event set into the event loop, as if the specified event |
|
|
3248 | had happened for the specified watcher (which must be a pointer to an |
|
|
3249 | initialised but not necessarily started event watcher). |
|
|
3250 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
3621 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3251 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
3622 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3252 | Feed an event on the given fd, as if a file descriptor backend detected |
3623 | Feed an event on the given fd, as if a file descriptor backend detected |
3253 | the given events it. |
3624 | the given events. |
3254 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
3625 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3255 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
3626 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3256 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3627 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3257 | loop!). |
3628 | which is async-safe. |
|
|
3629 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3630 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3631 | This section explains some common idioms that are not immediately |
|
|
3632 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3633 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3634 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
|
|
3635 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3636 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3637 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3638 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3639 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3640 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3641 | data: |
|
|
3642 | .PP |
|
|
3643 | .Vb 7 |
|
|
3644 | \& struct my_io |
|
|
3645 | \& { |
|
|
3646 | \& ev_io io; |
|
|
3647 | \& int otherfd; |
|
|
3648 | \& void *somedata; |
|
|
3649 | \& struct whatever *mostinteresting; |
|
|
3650 | \& }; |
|
|
3651 | \& |
|
|
3652 | \& ... |
|
|
3653 | \& struct my_io w; |
|
|
3654 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3655 | .Ve |
|
|
3656 | .PP |
|
|
3657 | And since your callback will be called with a pointer to the watcher, you |
|
|
3658 | can cast it back to your own type: |
|
|
3659 | .PP |
|
|
3660 | .Vb 5 |
|
|
3661 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3662 | \& { |
|
|
3663 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3664 | \& ... |
|
|
3665 | \& } |
|
|
3666 | .Ve |
|
|
3667 | .PP |
|
|
3668 | More interesting and less C\-conformant ways of casting your callback |
|
|
3669 | function type instead have been omitted. |
|
|
3670 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
|
|
3671 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3672 | Another common scenario is to use some data structure with multiple |
|
|
3673 | embedded watchers, in effect creating your own watcher that combines |
|
|
3674 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3675 | .PP |
|
|
3676 | .Vb 6 |
|
|
3677 | \& struct my_biggy |
|
|
3678 | \& { |
|
|
3679 | \& int some_data; |
|
|
3680 | \& ev_timer t1; |
|
|
3681 | \& ev_timer t2; |
|
|
3682 | \& } |
|
|
3683 | .Ve |
|
|
3684 | .PP |
|
|
3685 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3686 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3687 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3688 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3689 | real programmers): |
|
|
3690 | .PP |
|
|
3691 | .Vb 1 |
|
|
3692 | \& #include <stddef.h> |
|
|
3693 | \& |
|
|
3694 | \& static void |
|
|
3695 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3696 | \& { |
|
|
3697 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3698 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3699 | \& } |
|
|
3700 | \& |
|
|
3701 | \& static void |
|
|
3702 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3703 | \& { |
|
|
3704 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3705 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3706 | \& } |
|
|
3707 | .Ve |
|
|
3708 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
|
|
3709 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3710 | Often you have structures like this in event-based programs: |
|
|
3711 | .PP |
|
|
3712 | .Vb 4 |
|
|
3713 | \& callback () |
|
|
3714 | \& { |
|
|
3715 | \& free (request); |
|
|
3716 | \& } |
|
|
3717 | \& |
|
|
3718 | \& request = start_new_request (..., callback); |
|
|
3719 | .Ve |
|
|
3720 | .PP |
|
|
3721 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3722 | used to cancel the operation, or do other things with it. |
|
|
3723 | .PP |
|
|
3724 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3725 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3726 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3727 | operation and simply invoke the callback with the result. |
|
|
3728 | .PP |
|
|
3729 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3730 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3731 | .PP |
|
|
3732 | Even if you pass the request by some safer means to the callback, you |
|
|
3733 | might want to do something to the request after starting it, such as |
|
|
3734 | canceling it, which probably isn't working so well when the callback has |
|
|
3735 | already been invoked. |
|
|
3736 | .PP |
|
|
3737 | A common way around all these issues is to make sure that |
|
|
3738 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3739 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3740 | delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher |
|
|
3741 | for example, or more sneakily, by reusing an existing (stopped) watcher |
|
|
3742 | and pushing it into the pending queue: |
|
|
3743 | .PP |
|
|
3744 | .Vb 2 |
|
|
3745 | \& ev_set_cb (watcher, callback); |
|
|
3746 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3747 | .Ve |
|
|
3748 | .PP |
|
|
3749 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3750 | invoked, while not delaying callback invocation too much. |
|
|
3751 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
|
|
3752 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3753 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3754 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3755 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3756 | .PP |
|
|
3757 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3758 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3759 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3760 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3761 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
|
|
3762 | .PP |
|
|
3763 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3764 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3765 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3766 | .PP |
|
|
3767 | .Vb 2 |
|
|
3768 | \& // main loop |
|
|
3769 | \& int exit_main_loop = 0; |
|
|
3770 | \& |
|
|
3771 | \& while (!exit_main_loop) |
|
|
3772 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3773 | \& |
|
|
3774 | \& // in a modal watcher |
|
|
3775 | \& int exit_nested_loop = 0; |
|
|
3776 | \& |
|
|
3777 | \& while (!exit_nested_loop) |
|
|
3778 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3779 | .Ve |
|
|
3780 | .PP |
|
|
3781 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3782 | .PP |
|
|
3783 | .Vb 2 |
|
|
3784 | \& // exit modal loop |
|
|
3785 | \& exit_nested_loop = 1; |
|
|
3786 | \& |
|
|
3787 | \& // exit main program, after modal loop is finished |
|
|
3788 | \& exit_main_loop = 1; |
|
|
3789 | \& |
|
|
3790 | \& // exit both |
|
|
3791 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
3792 | .Ve |
|
|
3793 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
|
|
3794 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
3795 | Here is a fictitious example of how to run an event loop in a different |
|
|
3796 | thread from where callbacks are being invoked and watchers are |
|
|
3797 | created/added/removed. |
|
|
3798 | .PP |
|
|
3799 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
3800 | which uses exactly this technique (which is suited for many high-level |
|
|
3801 | languages). |
|
|
3802 | .PP |
|
|
3803 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3804 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3805 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3806 | .PP |
|
|
3807 | First, you need to associate some data with the event loop: |
|
|
3808 | .PP |
|
|
3809 | .Vb 6 |
|
|
3810 | \& typedef struct { |
|
|
3811 | \& mutex_t lock; /* global loop lock */ |
|
|
3812 | \& ev_async async_w; |
|
|
3813 | \& thread_t tid; |
|
|
3814 | \& cond_t invoke_cv; |
|
|
3815 | \& } userdata; |
|
|
3816 | \& |
|
|
3817 | \& void prepare_loop (EV_P) |
|
|
3818 | \& { |
|
|
3819 | \& // for simplicity, we use a static userdata struct. |
|
|
3820 | \& static userdata u; |
|
|
3821 | \& |
|
|
3822 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
3823 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
3824 | \& |
|
|
3825 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
3826 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
3827 | \& |
|
|
3828 | \& // now associate this with the loop |
|
|
3829 | \& ev_set_userdata (EV_A_ u); |
|
|
3830 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3831 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3832 | \& |
|
|
3833 | \& // then create the thread running ev_run |
|
|
3834 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
3835 | \& } |
|
|
3836 | .Ve |
|
|
3837 | .PP |
|
|
3838 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
3839 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3840 | that might have been added: |
|
|
3841 | .PP |
|
|
3842 | .Vb 5 |
|
|
3843 | \& static void |
|
|
3844 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
3845 | \& { |
|
|
3846 | \& // just used for the side effects |
|
|
3847 | \& } |
|
|
3848 | .Ve |
|
|
3849 | .PP |
|
|
3850 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
3851 | protecting the loop data, respectively. |
|
|
3852 | .PP |
|
|
3853 | .Vb 6 |
|
|
3854 | \& static void |
|
|
3855 | \& l_release (EV_P) |
|
|
3856 | \& { |
|
|
3857 | \& userdata *u = ev_userdata (EV_A); |
|
|
3858 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3859 | \& } |
|
|
3860 | \& |
|
|
3861 | \& static void |
|
|
3862 | \& l_acquire (EV_P) |
|
|
3863 | \& { |
|
|
3864 | \& userdata *u = ev_userdata (EV_A); |
|
|
3865 | \& pthread_mutex_lock (&u\->lock); |
|
|
3866 | \& } |
|
|
3867 | .Ve |
|
|
3868 | .PP |
|
|
3869 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3870 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
3871 | .PP |
|
|
3872 | .Vb 4 |
|
|
3873 | \& void * |
|
|
3874 | \& l_run (void *thr_arg) |
|
|
3875 | \& { |
|
|
3876 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3877 | \& |
|
|
3878 | \& l_acquire (EV_A); |
|
|
3879 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3880 | \& ev_run (EV_A_ 0); |
|
|
3881 | \& l_release (EV_A); |
|
|
3882 | \& |
|
|
3883 | \& return 0; |
|
|
3884 | \& } |
|
|
3885 | .Ve |
|
|
3886 | .PP |
|
|
3887 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
3888 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3889 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
3890 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3891 | and b) skipping inter-thread-communication when there are no pending |
|
|
3892 | watchers is very beneficial): |
|
|
3893 | .PP |
|
|
3894 | .Vb 4 |
|
|
3895 | \& static void |
|
|
3896 | \& l_invoke (EV_P) |
|
|
3897 | \& { |
|
|
3898 | \& userdata *u = ev_userdata (EV_A); |
|
|
3899 | \& |
|
|
3900 | \& while (ev_pending_count (EV_A)) |
|
|
3901 | \& { |
|
|
3902 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3903 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
3904 | \& } |
|
|
3905 | \& } |
|
|
3906 | .Ve |
|
|
3907 | .PP |
|
|
3908 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3909 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
3910 | thread to continue: |
|
|
3911 | .PP |
|
|
3912 | .Vb 4 |
|
|
3913 | \& static void |
|
|
3914 | \& real_invoke_pending (EV_P) |
|
|
3915 | \& { |
|
|
3916 | \& userdata *u = ev_userdata (EV_A); |
|
|
3917 | \& |
|
|
3918 | \& pthread_mutex_lock (&u\->lock); |
|
|
3919 | \& ev_invoke_pending (EV_A); |
|
|
3920 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
3921 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3922 | \& } |
|
|
3923 | .Ve |
|
|
3924 | .PP |
|
|
3925 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3926 | event loop, you will now have to lock: |
|
|
3927 | .PP |
|
|
3928 | .Vb 2 |
|
|
3929 | \& ev_timer timeout_watcher; |
|
|
3930 | \& userdata *u = ev_userdata (EV_A); |
|
|
3931 | \& |
|
|
3932 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3933 | \& |
|
|
3934 | \& pthread_mutex_lock (&u\->lock); |
|
|
3935 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3936 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
3937 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3938 | .Ve |
|
|
3939 | .PP |
|
|
3940 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
3941 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3942 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3943 | watchers in the next event loop iteration. |
|
|
3944 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
|
|
3945 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
3946 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
3947 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
3948 | kind of threads or coroutines, you might want to customise libev so that |
|
|
3949 | doesn't need callbacks anymore. |
|
|
3950 | .PP |
|
|
3951 | Imagine you have coroutines that you can switch to using a function |
|
|
3952 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
3953 | and that due to some magic, the currently active coroutine is stored in a |
|
|
3954 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
3955 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
3956 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
3957 | .PP |
|
|
3958 | .Vb 2 |
|
|
3959 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3960 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
3961 | .Ve |
|
|
3962 | .PP |
|
|
3963 | That means instead of having a C callback function, you store the |
|
|
3964 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
3965 | your callback, you instead have it switch to that coroutine. |
|
|
3966 | .PP |
|
|
3967 | A coroutine might now wait for an event with a function called |
|
|
3968 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
3969 | matter when, or whether the watcher is active or not when this function is |
|
|
3970 | called): |
|
|
3971 | .PP |
|
|
3972 | .Vb 6 |
|
|
3973 | \& void |
|
|
3974 | \& wait_for_event (ev_watcher *w) |
|
|
3975 | \& { |
|
|
3976 | \& ev_cb_set (w) = current_coro; |
|
|
3977 | \& switch_to (libev_coro); |
|
|
3978 | \& } |
|
|
3979 | .Ve |
|
|
3980 | .PP |
|
|
3981 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
3982 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
3983 | this or any other coroutine. |
|
|
3984 | .PP |
|
|
3985 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
3986 | instead of storing a coroutine, you store the queue object and instead of |
|
|
3987 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
3988 | any waiters. |
|
|
3989 | .PP |
|
|
3990 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
|
|
3991 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
3992 | .PP |
|
|
3993 | .Vb 4 |
|
|
3994 | \& // my_ev.h |
|
|
3995 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3996 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
|
|
3997 | \& #include "../libev/ev.h" |
|
|
3998 | \& |
|
|
3999 | \& // my_ev.c |
|
|
4000 | \& #define EV_H "my_ev.h" |
|
|
4001 | \& #include "../libev/ev.c" |
|
|
4002 | .Ve |
|
|
4003 | .PP |
|
|
4004 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
4005 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
4006 | can even use \fIev.h\fR as header file name directly. |
3258 | .SH "LIBEVENT EMULATION" |
4007 | .SH "LIBEVENT EMULATION" |
3259 | .IX Header "LIBEVENT EMULATION" |
4008 | .IX Header "LIBEVENT EMULATION" |
3260 | Libev offers a compatibility emulation layer for libevent. It cannot |
4009 | Libev offers a compatibility emulation layer for libevent. It cannot |
3261 | emulate the internals of libevent, so here are some usage hints: |
4010 | emulate the internals of libevent, so here are some usage hints: |
|
|
4011 | .IP "\(bu" 4 |
|
|
4012 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
4013 | .Sp |
|
|
4014 | This was the newest libevent version available when libev was implemented, |
|
|
4015 | and is still mostly unchanged in 2010. |
3262 | .IP "\(bu" 4 |
4016 | .IP "\(bu" 4 |
3263 | Use it by including <event.h>, as usual. |
4017 | Use it by including <event.h>, as usual. |
3264 | .IP "\(bu" 4 |
4018 | .IP "\(bu" 4 |
3265 | The following members are fully supported: ev_base, ev_callback, |
4019 | The following members are fully supported: ev_base, ev_callback, |
3266 | ev_arg, ev_fd, ev_res, ev_events. |
4020 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3272 | Priorities are not currently supported. Initialising priorities |
4026 | Priorities are not currently supported. Initialising priorities |
3273 | will fail and all watchers will have the same priority, even though there |
4027 | will fail and all watchers will have the same priority, even though there |
3274 | is an ev_pri field. |
4028 | is an ev_pri field. |
3275 | .IP "\(bu" 4 |
4029 | .IP "\(bu" 4 |
3276 | In libevent, the last base created gets the signals, in libev, the |
4030 | In libevent, the last base created gets the signals, in libev, the |
3277 | first base created (== the default loop) gets the signals. |
4031 | base that registered the signal gets the signals. |
3278 | .IP "\(bu" 4 |
4032 | .IP "\(bu" 4 |
3279 | Other members are not supported. |
4033 | Other members are not supported. |
3280 | .IP "\(bu" 4 |
4034 | .IP "\(bu" 4 |
3281 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4035 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3282 | to use the libev header file and library. |
4036 | to use the libev header file and library. |
3283 | .SH "\*(C+ SUPPORT" |
4037 | .SH "\*(C+ SUPPORT" |
3284 | .IX Header " SUPPORT" |
4038 | .IX Header " SUPPORT" |
|
|
4039 | .SS "C \s-1API\s0" |
|
|
4040 | .IX Subsection "C API" |
|
|
4041 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4042 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4043 | will work fine. |
|
|
4044 | .PP |
|
|
4045 | Proper exception specifications might have to be added to callbacks passed |
|
|
4046 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
4047 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
|
|
4048 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
|
|
4049 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
|
|
4050 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
|
|
4051 | .PP |
|
|
4052 | .Vb 6 |
|
|
4053 | \& static void |
|
|
4054 | \& fatal_error (const char *msg) EV_THROW |
|
|
4055 | \& { |
|
|
4056 | \& perror (msg); |
|
|
4057 | \& abort (); |
|
|
4058 | \& } |
|
|
4059 | \& |
|
|
4060 | \& ... |
|
|
4061 | \& ev_set_syserr_cb (fatal_error); |
|
|
4062 | .Ve |
|
|
4063 | .PP |
|
|
4064 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4065 | \&\f(CW\*(C`ev_inoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter |
|
|
4066 | because it runs cleanup watchers). |
|
|
4067 | .PP |
|
|
4068 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4069 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4070 | throwing exceptions through C libraries (most do). |
|
|
4071 | .SS "\*(C+ \s-1API\s0" |
|
|
4072 | .IX Subsection " API" |
3285 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4073 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3286 | you to use some convenience methods to start/stop watchers and also change |
4074 | you to use some convenience methods to start/stop watchers and also change |
3287 | the callback model to a model using method callbacks on objects. |
4075 | the callback model to a model using method callbacks on objects. |
3288 | .PP |
4076 | .PP |
3289 | To use it, |
4077 | To use it, |
… | |
… | |
3300 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
4088 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
3301 | classes add (compared to plain C\-style watchers) is the event loop pointer |
4089 | classes add (compared to plain C\-style watchers) is the event loop pointer |
3302 | that the watcher is associated with (or no additional members at all if |
4090 | that the watcher is associated with (or no additional members at all if |
3303 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
4091 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
3304 | .PP |
4092 | .PP |
3305 | Currently, functions, and static and non-static member functions can be |
4093 | Currently, functions, static and non-static member functions and classes |
3306 | used as callbacks. Other types should be easy to add as long as they only |
4094 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3307 | need one additional pointer for context. If you need support for other |
4095 | to add as long as they only need one additional pointer for context. If |
3308 | types of functors please contact the author (preferably after implementing |
4096 | you need support for other types of functors please contact the author |
3309 | it). |
4097 | (preferably after implementing it). |
|
|
4098 | .PP |
|
|
4099 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4100 | conventions as your C compiler (for static member functions), or you have |
|
|
4101 | to embed libev and compile libev itself as \*(C+. |
3310 | .PP |
4102 | .PP |
3311 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4103 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3312 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4104 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3313 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4105 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3314 | .IX Item "ev::READ, ev::WRITE etc." |
4106 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3322 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4114 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3323 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4115 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3324 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4116 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3325 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4117 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3326 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4118 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3327 | defines by many implementations. |
4119 | defined by many implementations. |
3328 | .Sp |
4120 | .Sp |
3329 | All of those classes have these methods: |
4121 | All of those classes have these methods: |
3330 | .RS 4 |
4122 | .RS 4 |
3331 | .IP "ev::TYPE::TYPE ()" 4 |
4123 | .IP "ev::TYPE::TYPE ()" 4 |
3332 | .IX Item "ev::TYPE::TYPE ()" |
4124 | .IX Item "ev::TYPE::TYPE ()" |
3333 | .PD 0 |
4125 | .PD 0 |
3334 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
4126 | .IP "ev::TYPE::TYPE (loop)" 4 |
3335 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
4127 | .IX Item "ev::TYPE::TYPE (loop)" |
3336 | .IP "ev::TYPE::~TYPE" 4 |
4128 | .IP "ev::TYPE::~TYPE" 4 |
3337 | .IX Item "ev::TYPE::~TYPE" |
4129 | .IX Item "ev::TYPE::~TYPE" |
3338 | .PD |
4130 | .PD |
3339 | The constructor (optionally) takes an event loop to associate the watcher |
4131 | The constructor (optionally) takes an event loop to associate the watcher |
3340 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
4132 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
… | |
… | |
3374 | \& ev::io iow; |
4166 | \& ev::io iow; |
3375 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
4167 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3376 | .Ve |
4168 | .Ve |
3377 | .IP "w\->set (object *)" 4 |
4169 | .IP "w\->set (object *)" 4 |
3378 | .IX Item "w->set (object *)" |
4170 | .IX Item "w->set (object *)" |
3379 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3380 | .Sp |
|
|
3381 | This is a variation of a method callback \- leaving out the method to call |
4171 | This is a variation of a method callback \- leaving out the method to call |
3382 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
4172 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
3383 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
4173 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
3384 | the time. Incidentally, you can then also leave out the template argument |
4174 | the time. Incidentally, you can then also leave out the template argument |
3385 | list. |
4175 | list. |
… | |
… | |
3419 | .Sp |
4209 | .Sp |
3420 | .Vb 2 |
4210 | .Vb 2 |
3421 | \& static void io_cb (ev::io &w, int revents) { } |
4211 | \& static void io_cb (ev::io &w, int revents) { } |
3422 | \& iow.set <io_cb> (); |
4212 | \& iow.set <io_cb> (); |
3423 | .Ve |
4213 | .Ve |
3424 | .IP "w\->set (struct ev_loop *)" 4 |
4214 | .IP "w\->set (loop)" 4 |
3425 | .IX Item "w->set (struct ev_loop *)" |
4215 | .IX Item "w->set (loop)" |
3426 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4216 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3427 | do this when the watcher is inactive (and not pending either). |
4217 | do this when the watcher is inactive (and not pending either). |
3428 | .IP "w\->set ([arguments])" 4 |
4218 | .IP "w\->set ([arguments])" 4 |
3429 | .IX Item "w->set ([arguments])" |
4219 | .IX Item "w->set ([arguments])" |
3430 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
4220 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
3431 | called at least once. Unlike the C counterpart, an active watcher gets |
4221 | method or a suitable start method must be called at least once. Unlike the |
3432 | automatically stopped and restarted when reconfiguring it with this |
4222 | C counterpart, an active watcher gets automatically stopped and restarted |
3433 | method. |
4223 | when reconfiguring it with this method. |
3434 | .IP "w\->start ()" 4 |
4224 | .IP "w\->start ()" 4 |
3435 | .IX Item "w->start ()" |
4225 | .IX Item "w->start ()" |
3436 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4226 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3437 | constructor already stores the event loop. |
4227 | constructor already stores the event loop. |
|
|
4228 | .IP "w\->start ([arguments])" 4 |
|
|
4229 | .IX Item "w->start ([arguments])" |
|
|
4230 | Instead of calling \f(CW\*(C`set\*(C'\fR and \f(CW\*(C`start\*(C'\fR methods separately, it is often |
|
|
4231 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
4232 | the configure \f(CW\*(C`set\*(C'\fR method of the watcher. |
3438 | .IP "w\->stop ()" 4 |
4233 | .IP "w\->stop ()" 4 |
3439 | .IX Item "w->stop ()" |
4234 | .IX Item "w->stop ()" |
3440 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
4235 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3441 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
4236 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3442 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
4237 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
… | |
… | |
3453 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
4248 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3454 | .RE |
4249 | .RE |
3455 | .RS 4 |
4250 | .RS 4 |
3456 | .RE |
4251 | .RE |
3457 | .PP |
4252 | .PP |
3458 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
4253 | Example: Define a class with two I/O and idle watchers, start the I/O |
3459 | the constructor. |
4254 | watchers in the constructor. |
3460 | .PP |
4255 | .PP |
3461 | .Vb 4 |
4256 | .Vb 5 |
3462 | \& class myclass |
4257 | \& class myclass |
3463 | \& { |
4258 | \& { |
3464 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4259 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
4260 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3465 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4261 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3466 | \& |
4262 | \& |
3467 | \& myclass (int fd) |
4263 | \& myclass (int fd) |
3468 | \& { |
4264 | \& { |
3469 | \& io .set <myclass, &myclass::io_cb > (this); |
4265 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
4266 | \& io2 .set <myclass, &myclass::io2_cb > (this); |
3470 | \& idle.set <myclass, &myclass::idle_cb> (this); |
4267 | \& idle.set <myclass, &myclass::idle_cb> (this); |
3471 | \& |
4268 | \& |
3472 | \& io.start (fd, ev::READ); |
4269 | \& io.set (fd, ev::WRITE); // configure the watcher |
|
|
4270 | \& io.start (); // start it whenever convenient |
|
|
4271 | \& |
|
|
4272 | \& io2.start (fd, ev::READ); // set + start in one call |
3473 | \& } |
4273 | \& } |
3474 | \& }; |
4274 | \& }; |
3475 | .Ve |
4275 | .Ve |
3476 | .SH "OTHER LANGUAGE BINDINGS" |
4276 | .SH "OTHER LANGUAGE BINDINGS" |
3477 | .IX Header "OTHER LANGUAGE BINDINGS" |
4277 | .IX Header "OTHER LANGUAGE BINDINGS" |
… | |
… | |
3504 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4304 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
3505 | makes rev work even on mingw. |
4305 | makes rev work even on mingw. |
3506 | .IP "Haskell" 4 |
4306 | .IP "Haskell" 4 |
3507 | .IX Item "Haskell" |
4307 | .IX Item "Haskell" |
3508 | A haskell binding to libev is available at |
4308 | A haskell binding to libev is available at |
3509 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4309 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
3510 | .IP "D" 4 |
4310 | .IP "D" 4 |
3511 | .IX Item "D" |
4311 | .IX Item "D" |
3512 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4312 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3513 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4313 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
3514 | .IP "Ocaml" 4 |
4314 | .IP "Ocaml" 4 |
3515 | .IX Item "Ocaml" |
4315 | .IX Item "Ocaml" |
3516 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4316 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3517 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4317 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3518 | .IP "Lua" 4 |
4318 | .IP "Lua" 4 |
3519 | .IX Item "Lua" |
4319 | .IX Item "Lua" |
3520 | Brian Maher has written a partial interface to libev |
4320 | Brian Maher has written a partial interface to libev for lua (at the |
3521 | for lua (only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4321 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
3522 | <http://github.com/brimworks/lua\-ev>. |
4322 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
3523 | .SH "MACRO MAGIC" |
4323 | .SH "MACRO MAGIC" |
3524 | .IX Header "MACRO MAGIC" |
4324 | .IX Header "MACRO MAGIC" |
3525 | Libev can be compiled with a variety of options, the most fundamental |
4325 | Libev can be compiled with a variety of options, the most fundamental |
3526 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4326 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3527 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4327 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
3536 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
4336 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3537 | .Sp |
4337 | .Sp |
3538 | .Vb 3 |
4338 | .Vb 3 |
3539 | \& ev_unref (EV_A); |
4339 | \& ev_unref (EV_A); |
3540 | \& ev_timer_add (EV_A_ watcher); |
4340 | \& ev_timer_add (EV_A_ watcher); |
3541 | \& ev_loop (EV_A_ 0); |
4341 | \& ev_run (EV_A_ 0); |
3542 | .Ve |
4342 | .Ve |
3543 | .Sp |
4343 | .Sp |
3544 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
4344 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3545 | which is often provided by the following macro. |
4345 | which is often provided by the following macro. |
3546 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
4346 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
… | |
… | |
3562 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4362 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3563 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4363 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3564 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4364 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3565 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4365 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3566 | Similar to the other two macros, this gives you the value of the default |
4366 | Similar to the other two macros, this gives you the value of the default |
3567 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4367 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4368 | will be initialised if it isn't already initialised. |
|
|
4369 | .Sp |
|
|
4370 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4371 | to initialise the loop somewhere. |
3568 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4372 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3569 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4373 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3570 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4374 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3571 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4375 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3572 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4376 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
3588 | \& } |
4392 | \& } |
3589 | \& |
4393 | \& |
3590 | \& ev_check check; |
4394 | \& ev_check check; |
3591 | \& ev_check_init (&check, check_cb); |
4395 | \& ev_check_init (&check, check_cb); |
3592 | \& ev_check_start (EV_DEFAULT_ &check); |
4396 | \& ev_check_start (EV_DEFAULT_ &check); |
3593 | \& ev_loop (EV_DEFAULT_ 0); |
4397 | \& ev_run (EV_DEFAULT_ 0); |
3594 | .Ve |
4398 | .Ve |
3595 | .SH "EMBEDDING" |
4399 | .SH "EMBEDDING" |
3596 | .IX Header "EMBEDDING" |
4400 | .IX Header "EMBEDDING" |
3597 | Libev can (and often is) directly embedded into host |
4401 | Libev can (and often is) directly embedded into host |
3598 | applications. Examples of applications that embed it include the Deliantra |
4402 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3693 | \& libev.m4 |
4497 | \& libev.m4 |
3694 | .Ve |
4498 | .Ve |
3695 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4499 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3696 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4500 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3697 | Libev can be configured via a variety of preprocessor symbols you have to |
4501 | Libev can be configured via a variety of preprocessor symbols you have to |
3698 | define before including any of its files. The default in the absence of |
4502 | define before including (or compiling) any of its files. The default in |
3699 | autoconf is documented for every option. |
4503 | the absence of autoconf is documented for every option. |
|
|
4504 | .PP |
|
|
4505 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
|
|
4506 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
|
|
4507 | to redefine them before including \fIev.h\fR without breaking compatibility |
|
|
4508 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
|
|
4509 | users of libev and the libev code itself must be compiled with compatible |
|
|
4510 | settings. |
|
|
4511 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
|
|
4512 | .IX Item "EV_COMPAT3 (h)" |
|
|
4513 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4514 | release of libev comes with wrappers for the functions and symbols that |
|
|
4515 | have been renamed between libev version 3 and 4. |
|
|
4516 | .Sp |
|
|
4517 | You can disable these wrappers (to test compatibility with future |
|
|
4518 | versions) by defining \f(CW\*(C`EV_COMPAT3\*(C'\fR to \f(CW0\fR when compiling your |
|
|
4519 | sources. This has the additional advantage that you can drop the \f(CW\*(C`struct\*(C'\fR |
|
|
4520 | from \f(CW\*(C`struct ev_loop\*(C'\fR declarations, as libev will provide an \f(CW\*(C`ev_loop\*(C'\fR |
|
|
4521 | typedef in that case. |
|
|
4522 | .Sp |
|
|
4523 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
|
|
4524 | and in some even more future version the compatibility code will be |
|
|
4525 | removed completely. |
3700 | .IP "\s-1EV_STANDALONE\s0" 4 |
4526 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
3701 | .IX Item "EV_STANDALONE" |
4527 | .IX Item "EV_STANDALONE (h)" |
3702 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4528 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3703 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4529 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3704 | implementations for some libevent functions (such as logging, which is not |
4530 | implementations for some libevent functions (such as logging, which is not |
3705 | supported). It will also not define any of the structs usually found in |
4531 | supported). It will also not define any of the structs usually found in |
3706 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4532 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3707 | .Sp |
4533 | .Sp |
3708 | In standalone mode, libev will still try to automatically deduce the |
4534 | In standalone mode, libev will still try to automatically deduce the |
3709 | configuration, but has to be more conservative. |
4535 | configuration, but has to be more conservative. |
|
|
4536 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4537 | .IX Item "EV_USE_FLOOR" |
|
|
4538 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4539 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4540 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4541 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4542 | function is not available will fail, so the safe default is to not enable |
|
|
4543 | this. |
3710 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4544 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3711 | .IX Item "EV_USE_MONOTONIC" |
4545 | .IX Item "EV_USE_MONOTONIC" |
3712 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4546 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3713 | monotonic clock option at both compile time and runtime. Otherwise no |
4547 | monotonic clock option at both compile time and runtime. Otherwise no |
3714 | use of the monotonic clock option will be attempted. If you enable this, |
4548 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
3769 | wants osf handles on win32 (this is the case when the select to |
4603 | wants osf handles on win32 (this is the case when the select to |
3770 | be used is the winsock select). This means that it will call |
4604 | be used is the winsock select). This means that it will call |
3771 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
4605 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3772 | it is assumed that all these functions actually work on fds, even |
4606 | it is assumed that all these functions actually work on fds, even |
3773 | on win32. Should not be defined on non\-win32 platforms. |
4607 | on win32. Should not be defined on non\-win32 platforms. |
3774 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
4608 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4 |
3775 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
4609 | .IX Item "EV_FD_TO_WIN32_HANDLE(fd)" |
3776 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
4610 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3777 | file descriptors to socket handles. When not defining this symbol (the |
4611 | file descriptors to socket handles. When not defining this symbol (the |
3778 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
4612 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3779 | correct. In some cases, programs use their own file descriptor management, |
4613 | correct. In some cases, programs use their own file descriptor management, |
3780 | in which case they can provide this function to map fds to socket handles. |
4614 | in which case they can provide this function to map fds to socket handles. |
|
|
4615 | .IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4 |
|
|
4616 | .IX Item "EV_WIN32_HANDLE_TO_FD(handle)" |
|
|
4617 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors |
|
|
4618 | using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing |
|
|
4619 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4620 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4621 | .IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4 |
|
|
4622 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
|
|
4623 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4624 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
|
|
4625 | file descriptors again. Note that the replacement function has to close |
|
|
4626 | the underlying \s-1OS\s0 handle. |
3781 | .IP "\s-1EV_USE_POLL\s0" 4 |
4627 | .IP "\s-1EV_USE_POLL\s0" 4 |
3782 | .IX Item "EV_USE_POLL" |
4628 | .IX Item "EV_USE_POLL" |
3783 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4629 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3784 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4630 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3785 | takes precedence over select. |
4631 | takes precedence over select. |
… | |
… | |
3814 | .IX Item "EV_USE_INOTIFY" |
4660 | .IX Item "EV_USE_INOTIFY" |
3815 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4661 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
3816 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4662 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
3817 | be detected at runtime. If undefined, it will be enabled if the headers |
4663 | be detected at runtime. If undefined, it will be enabled if the headers |
3818 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4664 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4665 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4666 | .IX Item "EV_NO_SMP" |
|
|
4667 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4668 | between threads, that is, threads can be used, but threads never run on |
|
|
4669 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4670 | and makes libev faster. |
|
|
4671 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4672 | .IX Item "EV_NO_THREADS" |
|
|
4673 | If defined to be \f(CW1\fR, libev will assume that it will never be called |
|
|
4674 | from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, |
|
|
4675 | above. This reduces dependencies and makes libev faster. |
3819 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4676 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
3820 | .IX Item "EV_ATOMIC_T" |
4677 | .IX Item "EV_ATOMIC_T" |
3821 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4678 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
3822 | access is atomic with respect to other threads or signal contexts. No such |
4679 | access is atomic and serialised with respect to other threads or signal |
3823 | type is easily found in the C language, so you can provide your own type |
4680 | contexts. No such type is easily found in the C language, so you can |
3824 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4681 | provide your own type that you know is safe for your purposes. It is used |
3825 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4682 | both for signal handler \*(L"locking\*(R" as well as for signal and thread safety |
|
|
4683 | in \f(CW\*(C`ev_async\*(C'\fR watchers. |
3826 | .Sp |
4684 | .Sp |
3827 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4685 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
3828 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4686 | (from \fIsignal.h\fR), which is usually good enough on most platforms, |
|
|
4687 | although strictly speaking using a type that also implies a memory fence |
|
|
4688 | is required. |
3829 | .IP "\s-1EV_H\s0" 4 |
4689 | .IP "\s-1EV_H\s0 (h)" 4 |
3830 | .IX Item "EV_H" |
4690 | .IX Item "EV_H (h)" |
3831 | The name of the \fIev.h\fR header file used to include it. The default if |
4691 | The name of the \fIev.h\fR header file used to include it. The default if |
3832 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4692 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
3833 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4693 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3834 | .IP "\s-1EV_CONFIG_H\s0" 4 |
4694 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
3835 | .IX Item "EV_CONFIG_H" |
4695 | .IX Item "EV_CONFIG_H (h)" |
3836 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4696 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3837 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4697 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3838 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4698 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3839 | .IP "\s-1EV_EVENT_H\s0" 4 |
4699 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
3840 | .IX Item "EV_EVENT_H" |
4700 | .IX Item "EV_EVENT_H (h)" |
3841 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4701 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3842 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4702 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
3843 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
4703 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
3844 | .IX Item "EV_PROTOTYPES" |
4704 | .IX Item "EV_PROTOTYPES (h)" |
3845 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4705 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3846 | prototypes, but still define all the structs and other symbols. This is |
4706 | prototypes, but still define all the structs and other symbols. This is |
3847 | occasionally useful if you want to provide your own wrapper functions |
4707 | occasionally useful if you want to provide your own wrapper functions |
3848 | around libev functions. |
4708 | around libev functions. |
3849 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
4709 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
… | |
… | |
3851 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4711 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3852 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4712 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3853 | additional independent event loops. Otherwise there will be no support |
4713 | additional independent event loops. Otherwise there will be no support |
3854 | for multiple event loops and there is no first event loop pointer |
4714 | for multiple event loops and there is no first event loop pointer |
3855 | argument. Instead, all functions act on the single default loop. |
4715 | argument. Instead, all functions act on the single default loop. |
|
|
4716 | .Sp |
|
|
4717 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4718 | default loop when multiplicity is switched off \- you always have to |
|
|
4719 | initialise the loop manually in this case. |
3856 | .IP "\s-1EV_MINPRI\s0" 4 |
4720 | .IP "\s-1EV_MINPRI\s0" 4 |
3857 | .IX Item "EV_MINPRI" |
4721 | .IX Item "EV_MINPRI" |
3858 | .PD 0 |
4722 | .PD 0 |
3859 | .IP "\s-1EV_MAXPRI\s0" 4 |
4723 | .IP "\s-1EV_MAXPRI\s0" 4 |
3860 | .IX Item "EV_MAXPRI" |
4724 | .IX Item "EV_MAXPRI" |
… | |
… | |
3869 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4733 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
3870 | fine. |
4734 | fine. |
3871 | .Sp |
4735 | .Sp |
3872 | If your embedding application does not need any priorities, defining these |
4736 | If your embedding application does not need any priorities, defining these |
3873 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4737 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
3874 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
4738 | .IP "\s-1EV_PERIODIC_ENABLE\s0, \s-1EV_IDLE_ENABLE\s0, \s-1EV_EMBED_ENABLE\s0, \s-1EV_STAT_ENABLE\s0, \s-1EV_PREPARE_ENABLE\s0, \s-1EV_CHECK_ENABLE\s0, \s-1EV_FORK_ENABLE\s0, \s-1EV_SIGNAL_ENABLE\s0, \s-1EV_ASYNC_ENABLE\s0, \s-1EV_CHILD_ENABLE\s0." 4 |
3875 | .IX Item "EV_PERIODIC_ENABLE" |
4739 | .IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." |
3876 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
4740 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
3877 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
4741 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
3878 | code. |
4742 | is not. Disabling watcher types mainly saves code size. |
3879 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3880 | .IX Item "EV_IDLE_ENABLE" |
|
|
3881 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3882 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3883 | code. |
|
|
3884 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
3885 | .IX Item "EV_EMBED_ENABLE" |
|
|
3886 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
3887 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3888 | watcher types, which therefore must not be disabled. |
|
|
3889 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
4743 | .IP "\s-1EV_FEATURES\s0" 4 |
3890 | .IX Item "EV_STAT_ENABLE" |
4744 | .IX Item "EV_FEATURES" |
3891 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
3892 | defined to be \f(CW0\fR, then they are not. |
|
|
3893 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3894 | .IX Item "EV_FORK_ENABLE" |
|
|
3895 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3896 | defined to be \f(CW0\fR, then they are not. |
|
|
3897 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3898 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3899 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3900 | defined to be \f(CW0\fR, then they are not. |
|
|
3901 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
3902 | .IX Item "EV_MINIMAL" |
|
|
3903 | If you need to shave off some kilobytes of code at the expense of some |
4745 | If you need to shave off some kilobytes of code at the expense of some |
3904 | speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this |
4746 | speed (but with the full \s-1API\s0), you can define this symbol to request |
3905 | is used to override some inlining decisions, saves roughly 30% code size |
4747 | certain subsets of functionality. The default is to enable all features |
3906 | on amd64. It also selects a much smaller 2\-heap for timer management over |
4748 | that can be enabled on the platform. |
3907 | the default 4\-heap. |
|
|
3908 | .Sp |
4749 | .Sp |
3909 | You can save even more by disabling watcher types you do not need |
4750 | A typical way to use this symbol is to define it to \f(CW0\fR (or to a bitset |
3910 | and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR |
4751 | with some broad features you want) and then selectively re-enable |
3911 | (\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot. |
4752 | additional parts you want, for example if you want everything minimal, |
|
|
4753 | but multiple event loop support, async and child watchers and the poll |
|
|
4754 | backend, use this: |
3912 | .Sp |
4755 | .Sp |
3913 | Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to |
4756 | .Vb 5 |
3914 | provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts |
4757 | \& #define EV_FEATURES 0 |
3915 | of the \s-1API\s0 are still available, and do not complain if this subset changes |
4758 | \& #define EV_MULTIPLICITY 1 |
3916 | over time. |
4759 | \& #define EV_USE_POLL 1 |
|
|
4760 | \& #define EV_CHILD_ENABLE 1 |
|
|
4761 | \& #define EV_ASYNC_ENABLE 1 |
|
|
4762 | .Ve |
|
|
4763 | .Sp |
|
|
4764 | The actual value is a bitset, it can be a combination of the following |
|
|
4765 | values (by default, all of these are enabled): |
|
|
4766 | .RS 4 |
|
|
4767 | .ie n .IP "1 \- faster/larger code" 4 |
|
|
4768 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
|
|
4769 | .IX Item "1 - faster/larger code" |
|
|
4770 | Use larger code to speed up some operations. |
|
|
4771 | .Sp |
|
|
4772 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4773 | code size by roughly 30% on amd64). |
|
|
4774 | .Sp |
|
|
4775 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
|
|
4776 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
|
|
4777 | assertions. |
|
|
4778 | .Sp |
|
|
4779 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4780 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
|
|
4781 | .ie n .IP "2 \- faster/larger data structures" 4 |
|
|
4782 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
|
|
4783 | .IX Item "2 - faster/larger data structures" |
|
|
4784 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
|
|
4785 | hash table sizes and so on. This will usually further increase code size |
|
|
4786 | and can additionally have an effect on the size of data structures at |
|
|
4787 | runtime. |
|
|
4788 | .Sp |
|
|
4789 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4790 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
|
|
4791 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
|
|
4792 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
|
|
4793 | .IX Item "4 - full API configuration" |
|
|
4794 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
|
|
4795 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
|
|
4796 | .ie n .IP "8 \- full \s-1API\s0" 4 |
|
|
4797 | .el .IP "\f(CW8\fR \- full \s-1API\s0" 4 |
|
|
4798 | .IX Item "8 - full API" |
|
|
4799 | This enables a lot of the \*(L"lesser used\*(R" \s-1API\s0 functions. See \f(CW\*(C`ev.h\*(C'\fR for |
|
|
4800 | details on which parts of the \s-1API\s0 are still available without this |
|
|
4801 | feature, and do not complain if this subset changes over time. |
|
|
4802 | .ie n .IP "16 \- enable all optional watcher types" 4 |
|
|
4803 | .el .IP "\f(CW16\fR \- enable all optional watcher types" 4 |
|
|
4804 | .IX Item "16 - enable all optional watcher types" |
|
|
4805 | Enables all optional watcher types. If you want to selectively enable |
|
|
4806 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4807 | embed, async, child...) you can enable them manually by defining |
|
|
4808 | \&\f(CW\*(C`EV_watchertype_ENABLE\*(C'\fR to \f(CW1\fR instead. |
|
|
4809 | .ie n .IP "32 \- enable all backends" 4 |
|
|
4810 | .el .IP "\f(CW32\fR \- enable all backends" 4 |
|
|
4811 | .IX Item "32 - enable all backends" |
|
|
4812 | This enables all backends \- without this feature, you need to enable at |
|
|
4813 | least one backend manually (\f(CW\*(C`EV_USE_SELECT\*(C'\fR is a good choice). |
|
|
4814 | .ie n .IP "64 \- enable OS-specific ""helper"" APIs" 4 |
|
|
4815 | .el .IP "\f(CW64\fR \- enable OS-specific ``helper'' APIs" 4 |
|
|
4816 | .IX Item "64 - enable OS-specific helper APIs" |
|
|
4817 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4818 | default. |
|
|
4819 | .RE |
|
|
4820 | .RS 4 |
|
|
4821 | .Sp |
|
|
4822 | Compiling with \f(CW\*(C`gcc \-Os \-DEV_STANDALONE \-DEV_USE_EPOLL=1 \-DEV_FEATURES=0\*(C'\fR |
|
|
4823 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4824 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4825 | watchers, timers and monotonic clock support. |
|
|
4826 | .Sp |
|
|
4827 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4828 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
|
|
4829 | your program might be left out as well \- a binary starting a timer and an |
|
|
4830 | I/O watcher then might come out at only 5Kb. |
|
|
4831 | .RE |
|
|
4832 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4833 | .IX Item "EV_API_STATIC" |
|
|
4834 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4835 | will have static linkage. This means that libev will not export any |
|
|
4836 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4837 | when you embed libev, only want to use libev functions in a single file, |
|
|
4838 | and do not want its identifiers to be visible. |
|
|
4839 | .Sp |
|
|
4840 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4841 | wants to use libev. |
|
|
4842 | .Sp |
|
|
4843 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4844 | doesn't support the required declaration syntax. |
|
|
4845 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
|
|
4846 | .IX Item "EV_AVOID_STDIO" |
|
|
4847 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
|
|
4848 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4849 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4850 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4851 | big. |
|
|
4852 | .Sp |
|
|
4853 | Note that error messages might become less precise when this option is |
|
|
4854 | enabled. |
3917 | .IP "\s-1EV_NSIG\s0" 4 |
4855 | .IP "\s-1EV_NSIG\s0" 4 |
3918 | .IX Item "EV_NSIG" |
4856 | .IX Item "EV_NSIG" |
3919 | The highest supported signal number, +1 (or, the number of |
4857 | The highest supported signal number, +1 (or, the number of |
3920 | signals): Normally, libev tries to deduce the maximum number of signals |
4858 | signals): Normally, libev tries to deduce the maximum number of signals |
3921 | automatically, but sometimes this fails, in which case it can be |
4859 | automatically, but sometimes this fails, in which case it can be |
3922 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
4860 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
3923 | good for about any system in existance) can save some memory, as libev |
4861 | good for about any system in existence) can save some memory, as libev |
3924 | statically allocates some 12\-24 bytes per signal number. |
4862 | statically allocates some 12\-24 bytes per signal number. |
3925 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
4863 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3926 | .IX Item "EV_PID_HASHSIZE" |
4864 | .IX Item "EV_PID_HASHSIZE" |
3927 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
4865 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3928 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
4866 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR disabled), |
3929 | than enough. If you need to manage thousands of children you might want to |
4867 | usually more than enough. If you need to manage thousands of children you |
3930 | increase this value (\fImust\fR be a power of two). |
4868 | might want to increase this value (\fImust\fR be a power of two). |
3931 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
4869 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3932 | .IX Item "EV_INOTIFY_HASHSIZE" |
4870 | .IX Item "EV_INOTIFY_HASHSIZE" |
3933 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
4871 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
3934 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
4872 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR |
3935 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
4873 | disabled), usually more than enough. If you need to manage thousands of |
3936 | watchers you might want to increase this value (\fImust\fR be a power of |
4874 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers you might want to increase this value (\fImust\fR be a |
3937 | two). |
4875 | power of two). |
3938 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
4876 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
3939 | .IX Item "EV_USE_4HEAP" |
4877 | .IX Item "EV_USE_4HEAP" |
3940 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4878 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3941 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
4879 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
3942 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
4880 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
3943 | faster performance with many (thousands) of watchers. |
4881 | faster performance with many (thousands) of watchers. |
3944 | .Sp |
4882 | .Sp |
3945 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4883 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3946 | (disabled). |
4884 | will be \f(CW0\fR. |
3947 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
4885 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
3948 | .IX Item "EV_HEAP_CACHE_AT" |
4886 | .IX Item "EV_HEAP_CACHE_AT" |
3949 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4887 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3950 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
4888 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
3951 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
4889 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
3952 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
4890 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
3953 | but avoids random read accesses on heap changes. This improves performance |
4891 | but avoids random read accesses on heap changes. This improves performance |
3954 | noticeably with many (hundreds) of watchers. |
4892 | noticeably with many (hundreds) of watchers. |
3955 | .Sp |
4893 | .Sp |
3956 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4894 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3957 | (disabled). |
4895 | will be \f(CW0\fR. |
3958 | .IP "\s-1EV_VERIFY\s0" 4 |
4896 | .IP "\s-1EV_VERIFY\s0" 4 |
3959 | .IX Item "EV_VERIFY" |
4897 | .IX Item "EV_VERIFY" |
3960 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
4898 | Controls how much internal verification (see \f(CW\*(C`ev_verify ()\*(C'\fR) will |
3961 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
4899 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
3962 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
4900 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
3963 | called. If set to \f(CW2\fR, then the internal verification code will be |
4901 | called. If set to \f(CW2\fR, then the internal verification code will be |
3964 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4902 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
3965 | verification code will be called very frequently, which will slow down |
4903 | verification code will be called very frequently, which will slow down |
3966 | libev considerably. |
4904 | libev considerably. |
3967 | .Sp |
4905 | .Sp |
3968 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
4906 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3969 | \&\f(CW0\fR. |
4907 | will be \f(CW0\fR. |
3970 | .IP "\s-1EV_COMMON\s0" 4 |
4908 | .IP "\s-1EV_COMMON\s0" 4 |
3971 | .IX Item "EV_COMMON" |
4909 | .IX Item "EV_COMMON" |
3972 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
4910 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3973 | this macro to a something else you can include more and other types of |
4911 | this macro to something else you can include more and other types of |
3974 | members. You have to define it each time you include one of the files, |
4912 | members. You have to define it each time you include one of the files, |
3975 | though, and it must be identical each time. |
4913 | though, and it must be identical each time. |
3976 | .Sp |
4914 | .Sp |
3977 | For example, the perl \s-1EV\s0 module uses something like this: |
4915 | For example, the perl \s-1EV\s0 module uses something like this: |
3978 | .Sp |
4916 | .Sp |
… | |
… | |
4036 | file. |
4974 | file. |
4037 | .PP |
4975 | .PP |
4038 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
4976 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
4039 | that everybody includes and which overrides some configure choices: |
4977 | that everybody includes and which overrides some configure choices: |
4040 | .PP |
4978 | .PP |
4041 | .Vb 9 |
4979 | .Vb 8 |
4042 | \& #define EV_MINIMAL 1 |
4980 | \& #define EV_FEATURES 8 |
4043 | \& #define EV_USE_POLL 0 |
4981 | \& #define EV_USE_SELECT 1 |
4044 | \& #define EV_MULTIPLICITY 0 |
|
|
4045 | \& #define EV_PERIODIC_ENABLE 0 |
4982 | \& #define EV_PREPARE_ENABLE 1 |
|
|
4983 | \& #define EV_IDLE_ENABLE 1 |
4046 | \& #define EV_STAT_ENABLE 0 |
4984 | \& #define EV_SIGNAL_ENABLE 1 |
4047 | \& #define EV_FORK_ENABLE 0 |
4985 | \& #define EV_CHILD_ENABLE 1 |
|
|
4986 | \& #define EV_USE_STDEXCEPT 0 |
4048 | \& #define EV_CONFIG_H <config.h> |
4987 | \& #define EV_CONFIG_H <config.h> |
4049 | \& #define EV_MINPRI 0 |
|
|
4050 | \& #define EV_MAXPRI 0 |
|
|
4051 | \& |
4988 | \& |
4052 | \& #include "ev++.h" |
4989 | \& #include "ev++.h" |
4053 | .Ve |
4990 | .Ve |
4054 | .PP |
4991 | .PP |
4055 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
4992 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
4056 | .PP |
4993 | .PP |
4057 | .Vb 2 |
4994 | .Vb 2 |
4058 | \& #include "ev_cpp.h" |
4995 | \& #include "ev_cpp.h" |
4059 | \& #include "ev.c" |
4996 | \& #include "ev.c" |
4060 | .Ve |
4997 | .Ve |
4061 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4998 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4062 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4999 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4063 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5000 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4064 | .IX Subsection "THREADS AND COROUTINES" |
5001 | .IX Subsection "THREADS AND COROUTINES" |
4065 | \fI\s-1THREADS\s0\fR |
5002 | \fI\s-1THREADS\s0\fR |
4066 | .IX Subsection "THREADS" |
5003 | .IX Subsection "THREADS" |
4067 | .PP |
5004 | .PP |
… | |
… | |
4114 | An example use would be to communicate signals or other events that only |
5051 | An example use would be to communicate signals or other events that only |
4115 | work in the default loop by registering the signal watcher with the |
5052 | work in the default loop by registering the signal watcher with the |
4116 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5053 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4117 | watcher callback into the event loop interested in the signal. |
5054 | watcher callback into the event loop interested in the signal. |
4118 | .PP |
5055 | .PP |
4119 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
5056 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
4120 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4121 | .PP |
|
|
4122 | Here is a fictitious example of how to run an event loop in a different |
|
|
4123 | thread than where callbacks are being invoked and watchers are |
|
|
4124 | created/added/removed. |
|
|
4125 | .PP |
|
|
4126 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4127 | which uses exactly this technique (which is suited for many high-level |
|
|
4128 | languages). |
|
|
4129 | .PP |
|
|
4130 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4131 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4132 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4133 | .PP |
|
|
4134 | First, you need to associate some data with the event loop: |
|
|
4135 | .PP |
|
|
4136 | .Vb 6 |
|
|
4137 | \& typedef struct { |
|
|
4138 | \& mutex_t lock; /* global loop lock */ |
|
|
4139 | \& ev_async async_w; |
|
|
4140 | \& thread_t tid; |
|
|
4141 | \& cond_t invoke_cv; |
|
|
4142 | \& } userdata; |
|
|
4143 | \& |
|
|
4144 | \& void prepare_loop (EV_P) |
|
|
4145 | \& { |
|
|
4146 | \& // for simplicity, we use a static userdata struct. |
|
|
4147 | \& static userdata u; |
|
|
4148 | \& |
|
|
4149 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4150 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4151 | \& |
|
|
4152 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4153 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4154 | \& |
|
|
4155 | \& // now associate this with the loop |
|
|
4156 | \& ev_set_userdata (EV_A_ u); |
|
|
4157 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4158 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4159 | \& |
|
|
4160 | \& // then create the thread running ev_loop |
|
|
4161 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4162 | \& } |
|
|
4163 | .Ve |
|
|
4164 | .PP |
|
|
4165 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4166 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4167 | that might have been added: |
|
|
4168 | .PP |
|
|
4169 | .Vb 5 |
|
|
4170 | \& static void |
|
|
4171 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4172 | \& { |
|
|
4173 | \& // just used for the side effects |
|
|
4174 | \& } |
|
|
4175 | .Ve |
|
|
4176 | .PP |
|
|
4177 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4178 | protecting the loop data, respectively. |
|
|
4179 | .PP |
|
|
4180 | .Vb 6 |
|
|
4181 | \& static void |
|
|
4182 | \& l_release (EV_P) |
|
|
4183 | \& { |
|
|
4184 | \& userdata *u = ev_userdata (EV_A); |
|
|
4185 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4186 | \& } |
|
|
4187 | \& |
|
|
4188 | \& static void |
|
|
4189 | \& l_acquire (EV_P) |
|
|
4190 | \& { |
|
|
4191 | \& userdata *u = ev_userdata (EV_A); |
|
|
4192 | \& pthread_mutex_lock (&u\->lock); |
|
|
4193 | \& } |
|
|
4194 | .Ve |
|
|
4195 | .PP |
|
|
4196 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4197 | into \f(CW\*(C`ev_loop\*(C'\fR: |
|
|
4198 | .PP |
|
|
4199 | .Vb 4 |
|
|
4200 | \& void * |
|
|
4201 | \& l_run (void *thr_arg) |
|
|
4202 | \& { |
|
|
4203 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4204 | \& |
|
|
4205 | \& l_acquire (EV_A); |
|
|
4206 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4207 | \& ev_loop (EV_A_ 0); |
|
|
4208 | \& l_release (EV_A); |
|
|
4209 | \& |
|
|
4210 | \& return 0; |
|
|
4211 | \& } |
|
|
4212 | .Ve |
|
|
4213 | .PP |
|
|
4214 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4215 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4216 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4217 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4218 | and b) skipping inter-thread-communication when there are no pending |
|
|
4219 | watchers is very beneficial): |
|
|
4220 | .PP |
|
|
4221 | .Vb 4 |
|
|
4222 | \& static void |
|
|
4223 | \& l_invoke (EV_P) |
|
|
4224 | \& { |
|
|
4225 | \& userdata *u = ev_userdata (EV_A); |
|
|
4226 | \& |
|
|
4227 | \& while (ev_pending_count (EV_A)) |
|
|
4228 | \& { |
|
|
4229 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4230 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4231 | \& } |
|
|
4232 | \& } |
|
|
4233 | .Ve |
|
|
4234 | .PP |
|
|
4235 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4236 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4237 | thread to continue: |
|
|
4238 | .PP |
|
|
4239 | .Vb 4 |
|
|
4240 | \& static void |
|
|
4241 | \& real_invoke_pending (EV_P) |
|
|
4242 | \& { |
|
|
4243 | \& userdata *u = ev_userdata (EV_A); |
|
|
4244 | \& |
|
|
4245 | \& pthread_mutex_lock (&u\->lock); |
|
|
4246 | \& ev_invoke_pending (EV_A); |
|
|
4247 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4248 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4249 | \& } |
|
|
4250 | .Ve |
|
|
4251 | .PP |
|
|
4252 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4253 | event loop, you will now have to lock: |
|
|
4254 | .PP |
|
|
4255 | .Vb 2 |
|
|
4256 | \& ev_timer timeout_watcher; |
|
|
4257 | \& userdata *u = ev_userdata (EV_A); |
|
|
4258 | \& |
|
|
4259 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4260 | \& |
|
|
4261 | \& pthread_mutex_lock (&u\->lock); |
|
|
4262 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4263 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4264 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4265 | .Ve |
|
|
4266 | .PP |
|
|
4267 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4268 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4269 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4270 | watchers in the next event loop iteration. |
|
|
4271 | .PP |
5057 | .PP |
4272 | \fI\s-1COROUTINES\s0\fR |
5058 | \fI\s-1COROUTINES\s0\fR |
4273 | .IX Subsection "COROUTINES" |
5059 | .IX Subsection "COROUTINES" |
4274 | .PP |
5060 | .PP |
4275 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5061 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
4276 | libev fully supports nesting calls to its functions from different |
5062 | libev fully supports nesting calls to its functions from different |
4277 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
5063 | coroutines (e.g. you can call \f(CW\*(C`ev_run\*(C'\fR on the same loop from two |
4278 | different coroutines, and switch freely between both coroutines running |
5064 | different coroutines, and switch freely between both coroutines running |
4279 | the loop, as long as you don't confuse yourself). The only exception is |
5065 | the loop, as long as you don't confuse yourself). The only exception is |
4280 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5066 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4281 | .PP |
5067 | .PP |
4282 | Care has been taken to ensure that libev does not keep local state inside |
5068 | Care has been taken to ensure that libev does not keep local state inside |
4283 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5069 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4284 | they do not call any callbacks. |
5070 | they do not call any callbacks. |
4285 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5071 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
4286 | .IX Subsection "COMPILER WARNINGS" |
5072 | .IX Subsection "COMPILER WARNINGS" |
4287 | Depending on your compiler and compiler settings, you might get no or a |
5073 | Depending on your compiler and compiler settings, you might get no or a |
4288 | lot of warnings when compiling libev code. Some people are apparently |
5074 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
4298 | maintainable. |
5084 | maintainable. |
4299 | .PP |
5085 | .PP |
4300 | And of course, some compiler warnings are just plain stupid, or simply |
5086 | And of course, some compiler warnings are just plain stupid, or simply |
4301 | wrong (because they don't actually warn about the condition their message |
5087 | wrong (because they don't actually warn about the condition their message |
4302 | seems to warn about). For example, certain older gcc versions had some |
5088 | seems to warn about). For example, certain older gcc versions had some |
4303 | warnings that resulted an extreme number of false positives. These have |
5089 | warnings that resulted in an extreme number of false positives. These have |
4304 | been fixed, but some people still insist on making code warn-free with |
5090 | been fixed, but some people still insist on making code warn-free with |
4305 | such buggy versions. |
5091 | such buggy versions. |
4306 | .PP |
5092 | .PP |
4307 | While libev is written to generate as few warnings as possible, |
5093 | While libev is written to generate as few warnings as possible, |
4308 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
5094 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4342 | .PP |
5128 | .PP |
4343 | If you need, for some reason, empty reports from valgrind for your project |
5129 | If you need, for some reason, empty reports from valgrind for your project |
4344 | I suggest using suppression lists. |
5130 | I suggest using suppression lists. |
4345 | .SH "PORTABILITY NOTES" |
5131 | .SH "PORTABILITY NOTES" |
4346 | .IX Header "PORTABILITY NOTES" |
5132 | .IX Header "PORTABILITY NOTES" |
|
|
5133 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
|
|
5134 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
|
|
5135 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
5136 | interfaces but \fIdisables\fR them by default. |
|
|
5137 | .PP |
|
|
5138 | That means that libev compiled in the default environment doesn't support |
|
|
5139 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
|
|
5140 | .PP |
|
|
5141 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
5142 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
|
|
5143 | standard libev compiled for their system. |
|
|
5144 | .PP |
|
|
5145 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
|
|
5146 | suddenly make it incompatible to the default compile time environment, |
|
|
5147 | i.e. all programs not using special compile switches. |
|
|
5148 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
|
|
5149 | .IX Subsection "OS/X AND DARWIN BUGS" |
|
|
5150 | The whole thing is a bug if you ask me \- basically any system interface |
|
|
5151 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
5152 | OpenGL drivers. |
|
|
5153 | .PP |
|
|
5154 | \fI\f(CI\*(C`kqueue\*(C'\fI is buggy\fR |
|
|
5155 | .IX Subsection "kqueue is buggy" |
|
|
5156 | .PP |
|
|
5157 | The kqueue syscall is broken in all known versions \- most versions support |
|
|
5158 | only sockets, many support pipes. |
|
|
5159 | .PP |
|
|
5160 | Libev tries to work around this by not using \f(CW\*(C`kqueue\*(C'\fR by default on this |
|
|
5161 | rotten platform, but of course you can still ask for it when creating a |
|
|
5162 | loop \- embedding a socket-only kqueue loop into a select-based one is |
|
|
5163 | probably going to work well. |
|
|
5164 | .PP |
|
|
5165 | \fI\f(CI\*(C`poll\*(C'\fI is buggy\fR |
|
|
5166 | .IX Subsection "poll is buggy" |
|
|
5167 | .PP |
|
|
5168 | Instead of fixing \f(CW\*(C`kqueue\*(C'\fR, Apple replaced their (working) \f(CW\*(C`poll\*(C'\fR |
|
|
5169 | implementation by something calling \f(CW\*(C`kqueue\*(C'\fR internally around the 10.5.6 |
|
|
5170 | release, so now \f(CW\*(C`kqueue\*(C'\fR \fIand\fR \f(CW\*(C`poll\*(C'\fR are broken. |
|
|
5171 | .PP |
|
|
5172 | Libev tries to work around this by not using \f(CW\*(C`poll\*(C'\fR by default on |
|
|
5173 | this rotten platform, but of course you can still ask for it when creating |
|
|
5174 | a loop. |
|
|
5175 | .PP |
|
|
5176 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
|
|
5177 | .IX Subsection "select is buggy" |
|
|
5178 | .PP |
|
|
5179 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
|
|
5180 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
|
|
5181 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
|
|
5182 | you use more. |
|
|
5183 | .PP |
|
|
5184 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
|
|
5185 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
|
|
5186 | work on \s-1OS/X\s0. |
|
|
5187 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
5188 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
|
|
5189 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
|
|
5190 | .IX Subsection "errno reentrancy" |
|
|
5191 | .PP |
|
|
5192 | The default compile environment on Solaris is unfortunately so |
|
|
5193 | thread-unsafe that you can't even use components/libraries compiled |
|
|
5194 | without \f(CW\*(C`\-D_REENTRANT\*(C'\fR in a threaded program, which, of course, isn't |
|
|
5195 | defined by default. A valid, if stupid, implementation choice. |
|
|
5196 | .PP |
|
|
5197 | If you want to use libev in threaded environments you have to make sure |
|
|
5198 | it's compiled with \f(CW\*(C`_REENTRANT\*(C'\fR defined. |
|
|
5199 | .PP |
|
|
5200 | \fIEvent port backend\fR |
|
|
5201 | .IX Subsection "Event port backend" |
|
|
5202 | .PP |
|
|
5203 | The scalable event interface for Solaris is called \*(L"event |
|
|
5204 | ports\*(R". Unfortunately, this mechanism is very buggy in all major |
|
|
5205 | releases. If you run into high \s-1CPU\s0 usage, your program freezes or you get |
|
|
5206 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
5207 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
5208 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
5209 | great. |
|
|
5210 | .PP |
|
|
5211 | If you can't get it to work, you can try running the program by setting |
|
|
5212 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
|
|
5213 | \&\f(CW\*(C`select\*(C'\fR backends. |
|
|
5214 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
|
|
5215 | .IX Subsection "AIX POLL BUG" |
|
|
5216 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
|
|
5217 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
5218 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
|
|
5219 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
4347 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5220 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
4348 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5221 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
5222 | \fIGeneral issues\fR |
|
|
5223 | .IX Subsection "General issues" |
|
|
5224 | .PP |
4349 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5225 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4350 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5226 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4351 | model. Libev still offers limited functionality on this platform in |
5227 | model. Libev still offers limited functionality on this platform in |
4352 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5228 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4353 | descriptors. This only applies when using Win32 natively, not when using |
5229 | descriptors. This only applies when using Win32 natively, not when using |
4354 | e.g. cygwin. |
5230 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
5231 | as every compiler comes with a slightly differently broken/incompatible |
|
|
5232 | environment. |
4355 | .PP |
5233 | .PP |
4356 | Lifting these limitations would basically require the full |
5234 | Lifting these limitations would basically require the full |
4357 | re-implementation of the I/O system. If you are into these kinds of |
5235 | re-implementation of the I/O system. If you are into this kind of thing, |
4358 | things, then note that glib does exactly that for you in a very portable |
5236 | then note that glib does exactly that for you in a very portable way (note |
4359 | way (note also that glib is the slowest event library known to man). |
5237 | also that glib is the slowest event library known to man). |
4360 | .PP |
5238 | .PP |
4361 | There is no supported compilation method available on windows except |
5239 | There is no supported compilation method available on windows except |
4362 | embedding it into other applications. |
5240 | embedding it into other applications. |
4363 | .PP |
5241 | .PP |
4364 | Sensible signal handling is officially unsupported by Microsoft \- libev |
5242 | Sensible signal handling is officially unsupported by Microsoft \- libev |
… | |
… | |
4395 | .PP |
5273 | .PP |
4396 | .Vb 2 |
5274 | .Vb 2 |
4397 | \& #include "evwrap.h" |
5275 | \& #include "evwrap.h" |
4398 | \& #include "ev.c" |
5276 | \& #include "ev.c" |
4399 | .Ve |
5277 | .Ve |
4400 | .IP "The winsocket select function" 4 |
5278 | .PP |
|
|
5279 | \fIThe winsocket \f(CI\*(C`select\*(C'\fI function\fR |
4401 | .IX Item "The winsocket select function" |
5280 | .IX Subsection "The winsocket select function" |
|
|
5281 | .PP |
4402 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
5282 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
4403 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
5283 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
4404 | also extremely buggy). This makes select very inefficient, and also |
5284 | also extremely buggy). This makes select very inefficient, and also |
4405 | requires a mapping from file descriptors to socket handles (the Microsoft |
5285 | requires a mapping from file descriptors to socket handles (the Microsoft |
4406 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
5286 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
4407 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
5287 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
4408 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
5288 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
4409 | .Sp |
5289 | .PP |
4410 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
5290 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
4411 | libraries and raw winsocket select is: |
5291 | libraries and raw winsocket select is: |
4412 | .Sp |
5292 | .PP |
4413 | .Vb 2 |
5293 | .Vb 2 |
4414 | \& #define EV_USE_SELECT 1 |
5294 | \& #define EV_USE_SELECT 1 |
4415 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5295 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4416 | .Ve |
5296 | .Ve |
4417 | .Sp |
5297 | .PP |
4418 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5298 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4419 | complexity in the O(nA\*^X) range when using win32. |
5299 | complexity in the O(nA\*^X) range when using win32. |
|
|
5300 | .PP |
4420 | .IP "Limited number of file descriptors" 4 |
5301 | \fILimited number of file descriptors\fR |
4421 | .IX Item "Limited number of file descriptors" |
5302 | .IX Subsection "Limited number of file descriptors" |
|
|
5303 | .PP |
4422 | Windows has numerous arbitrary (and low) limits on things. |
5304 | Windows has numerous arbitrary (and low) limits on things. |
4423 | .Sp |
5305 | .PP |
4424 | Early versions of winsocket's select only supported waiting for a maximum |
5306 | Early versions of winsocket's select only supported waiting for a maximum |
4425 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
5307 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
4426 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
5308 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
4427 | recommends spawning a chain of threads and wait for 63 handles and the |
5309 | recommends spawning a chain of threads and wait for 63 handles and the |
4428 | previous thread in each. Sounds great!). |
5310 | previous thread in each. Sounds great!). |
4429 | .Sp |
5311 | .PP |
4430 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
5312 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
4431 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
5313 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
4432 | call (which might be in libev or elsewhere, for example, perl and many |
5314 | call (which might be in libev or elsewhere, for example, perl and many |
4433 | other interpreters do their own select emulation on windows). |
5315 | other interpreters do their own select emulation on windows). |
4434 | .Sp |
5316 | .PP |
4435 | Another limit is the number of file descriptors in the Microsoft runtime |
5317 | Another limit is the number of file descriptors in the Microsoft runtime |
4436 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
5318 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
4437 | fetish or something like this inside Microsoft). You can increase this |
5319 | fetish or something like this inside Microsoft). You can increase this |
4438 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5320 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
4439 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5321 | (another arbitrary limit), but is broken in many versions of the Microsoft |
… | |
… | |
4451 | Libev assumes not only that all watcher pointers have the same internal |
5333 | Libev assumes not only that all watcher pointers have the same internal |
4452 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5334 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
4453 | assumes that the same (machine) code can be used to call any watcher |
5335 | assumes that the same (machine) code can be used to call any watcher |
4454 | callback: The watcher callbacks have different type signatures, but libev |
5336 | callback: The watcher callbacks have different type signatures, but libev |
4455 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5337 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5338 | .IP "pointer accesses must be thread-atomic" 4 |
|
|
5339 | .IX Item "pointer accesses must be thread-atomic" |
|
|
5340 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
5341 | writable in one piece \- this is the case on all current architectures. |
4456 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5342 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
4457 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
5343 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
4458 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
5344 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
4459 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
5345 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
4460 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
5346 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
… | |
… | |
4483 | watchers. |
5369 | watchers. |
4484 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5370 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
4485 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
5371 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
4486 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5372 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4487 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5373 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4488 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
5374 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4489 | enough for at least into the year 4000. This requirement is fulfilled by |
5375 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
5376 | (the design goal for libev). This requirement is overfulfilled by |
4490 | implementations implementing \s-1IEEE\s0 754, which is basically all existing |
5377 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
|
|
5378 | .Sp |
4491 | ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least |
5379 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
4492 | 2200. |
5380 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5381 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5382 | something like that, just kidding). |
4493 | .PP |
5383 | .PP |
4494 | If you know of other additional requirements drop me a note. |
5384 | If you know of other additional requirements drop me a note. |
4495 | .SH "ALGORITHMIC COMPLEXITIES" |
5385 | .SH "ALGORITHMIC COMPLEXITIES" |
4496 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5386 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4497 | In this section the complexities of (many of) the algorithms used inside |
5387 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4551 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5441 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
4552 | .IP "Processing signals: O(max_signal_number)" 4 |
5442 | .IP "Processing signals: O(max_signal_number)" 4 |
4553 | .IX Item "Processing signals: O(max_signal_number)" |
5443 | .IX Item "Processing signals: O(max_signal_number)" |
4554 | .PD |
5444 | .PD |
4555 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5445 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4556 | calls in the current loop iteration. Checking for async and signal events |
5446 | calls in the current loop iteration and the loop is currently |
|
|
5447 | blocked. Checking for async and signal events involves iterating over all |
4557 | involves iterating over all running async watchers or all signal numbers. |
5448 | running async watchers or all signal numbers. |
|
|
5449 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5450 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5451 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
|
|
5452 | .PP |
|
|
5453 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
|
|
5454 | for all changes, so most programs should still compile. The compatibility |
|
|
5455 | layer might be removed in later versions of libev, so better update to the |
|
|
5456 | new \s-1API\s0 early than late. |
|
|
5457 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
|
|
5458 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
|
|
5459 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
|
|
5460 | The backward compatibility mechanism can be controlled by |
|
|
5461 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1MACROS\s0\*(R" in \s-1PREPROCESSOR\s0 \s-1SYMBOLS\s0 in the \s-1EMBEDDING\s0 |
|
|
5462 | section. |
|
|
5463 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
|
|
5464 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
|
|
5465 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
|
|
5466 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
|
|
5467 | .Sp |
|
|
5468 | .Vb 2 |
|
|
5469 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5470 | \& ev_loop_fork (EV_DEFAULT); |
|
|
5471 | .Ve |
|
|
5472 | .IP "function/symbol renames" 4 |
|
|
5473 | .IX Item "function/symbol renames" |
|
|
5474 | A number of functions and symbols have been renamed: |
|
|
5475 | .Sp |
|
|
5476 | .Vb 3 |
|
|
5477 | \& ev_loop => ev_run |
|
|
5478 | \& EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5479 | \& EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5480 | \& |
|
|
5481 | \& ev_unloop => ev_break |
|
|
5482 | \& EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5483 | \& EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5484 | \& EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5485 | \& |
|
|
5486 | \& EV_TIMEOUT => EV_TIMER |
|
|
5487 | \& |
|
|
5488 | \& ev_loop_count => ev_iteration |
|
|
5489 | \& ev_loop_depth => ev_depth |
|
|
5490 | \& ev_loop_verify => ev_verify |
|
|
5491 | .Ve |
|
|
5492 | .Sp |
|
|
5493 | Most functions working on \f(CW\*(C`struct ev_loop\*(C'\fR objects don't have an |
|
|
5494 | \&\f(CW\*(C`ev_loop_\*(C'\fR prefix, so it was removed; \f(CW\*(C`ev_loop\*(C'\fR, \f(CW\*(C`ev_unloop\*(C'\fR and |
|
|
5495 | associated constants have been renamed to not collide with the \f(CW\*(C`struct |
|
|
5496 | ev_loop\*(C'\fR anymore and \f(CW\*(C`EV_TIMER\*(C'\fR now follows the same naming scheme |
|
|
5497 | as all other watcher types. Note that \f(CW\*(C`ev_loop_fork\*(C'\fR is still called |
|
|
5498 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR because it would otherwise clash with the \f(CW\*(C`ev_fork\*(C'\fR |
|
|
5499 | typedef. |
|
|
5500 | .ie n .IP """EV_MINIMAL"" mechanism replaced by ""EV_FEATURES""" 4 |
|
|
5501 | .el .IP "\f(CWEV_MINIMAL\fR mechanism replaced by \f(CWEV_FEATURES\fR" 4 |
|
|
5502 | .IX Item "EV_MINIMAL mechanism replaced by EV_FEATURES" |
|
|
5503 | The preprocessor symbol \f(CW\*(C`EV_MINIMAL\*(C'\fR has been replaced by a different |
|
|
5504 | mechanism, \f(CW\*(C`EV_FEATURES\*(C'\fR. Programs using \f(CW\*(C`EV_MINIMAL\*(C'\fR usually compile |
|
|
5505 | and work, but the library code will of course be larger. |
4558 | .SH "GLOSSARY" |
5506 | .SH "GLOSSARY" |
4559 | .IX Header "GLOSSARY" |
5507 | .IX Header "GLOSSARY" |
4560 | .IP "active" 4 |
5508 | .IP "active" 4 |
4561 | .IX Item "active" |
5509 | .IX Item "active" |
4562 | A watcher is active as long as it has been started (has been attached to |
5510 | A watcher is active as long as it has been started and not yet stopped. |
4563 | an event loop) but not yet stopped (disassociated from the event loop). |
5511 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
4564 | .IP "application" 4 |
5512 | .IP "application" 4 |
4565 | .IX Item "application" |
5513 | .IX Item "application" |
4566 | In this document, an application is whatever is using libev. |
5514 | In this document, an application is whatever is using libev. |
|
|
5515 | .IP "backend" 4 |
|
|
5516 | .IX Item "backend" |
|
|
5517 | The part of the code dealing with the operating system interfaces. |
4567 | .IP "callback" 4 |
5518 | .IP "callback" 4 |
4568 | .IX Item "callback" |
5519 | .IX Item "callback" |
4569 | The address of a function that is called when some event has been |
5520 | The address of a function that is called when some event has been |
4570 | detected. Callbacks are being passed the event loop, the watcher that |
5521 | detected. Callbacks are being passed the event loop, the watcher that |
4571 | received the event, and the actual event bitset. |
5522 | received the event, and the actual event bitset. |
4572 | .IP "callback invocation" 4 |
5523 | .IP "callback/watcher invocation" 4 |
4573 | .IX Item "callback invocation" |
5524 | .IX Item "callback/watcher invocation" |
4574 | The act of calling the callback associated with a watcher. |
5525 | The act of calling the callback associated with a watcher. |
4575 | .IP "event" 4 |
5526 | .IP "event" 4 |
4576 | .IX Item "event" |
5527 | .IX Item "event" |
4577 | A change of state of some external event, such as data now being available |
5528 | A change of state of some external event, such as data now being available |
4578 | for reading on a file descriptor, time having passed or simply not having |
5529 | for reading on a file descriptor, time having passed or simply not having |
4579 | any other events happening anymore. |
5530 | any other events happening anymore. |
4580 | .Sp |
5531 | .Sp |
4581 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
5532 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
4582 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
5533 | \&\f(CW\*(C`EV_TIMER\*(C'\fR). |
4583 | .IP "event library" 4 |
5534 | .IP "event library" 4 |
4584 | .IX Item "event library" |
5535 | .IX Item "event library" |
4585 | A software package implementing an event model and loop. |
5536 | A software package implementing an event model and loop. |
4586 | .IP "event loop" 4 |
5537 | .IP "event loop" 4 |
4587 | .IX Item "event loop" |
5538 | .IX Item "event loop" |
… | |
… | |
4591 | .IX Item "event model" |
5542 | .IX Item "event model" |
4592 | The model used to describe how an event loop handles and processes |
5543 | The model used to describe how an event loop handles and processes |
4593 | watchers and events. |
5544 | watchers and events. |
4594 | .IP "pending" 4 |
5545 | .IP "pending" 4 |
4595 | .IX Item "pending" |
5546 | .IX Item "pending" |
4596 | A watcher is pending as soon as the corresponding event has been detected, |
5547 | A watcher is pending as soon as the corresponding event has been |
4597 | and stops being pending as soon as the watcher will be invoked or its |
5548 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
4598 | pending status is explicitly cleared by the application. |
|
|
4599 | .Sp |
|
|
4600 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4601 | its pending status. |
|
|
4602 | .IP "real time" 4 |
5549 | .IP "real time" 4 |
4603 | .IX Item "real time" |
5550 | .IX Item "real time" |
4604 | The physical time that is observed. It is apparently strictly monotonic :) |
5551 | The physical time that is observed. It is apparently strictly monotonic :) |
4605 | .IP "wall-clock time" 4 |
5552 | .IP "wall-clock time" 4 |
4606 | .IX Item "wall-clock time" |
5553 | .IX Item "wall-clock time" |
4607 | The time and date as shown on clocks. Unlike real time, it can actually |
5554 | The time and date as shown on clocks. Unlike real time, it can actually |
4608 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5555 | be wrong and jump forwards and backwards, e.g. when you adjust your |
4609 | clock. |
5556 | clock. |
4610 | .IP "watcher" 4 |
5557 | .IP "watcher" 4 |
4611 | .IX Item "watcher" |
5558 | .IX Item "watcher" |
4612 | A data structure that describes interest in certain events. Watchers need |
5559 | A data structure that describes interest in certain events. Watchers need |
4613 | to be started (attached to an event loop) before they can receive events. |
5560 | to be started (attached to an event loop) before they can receive events. |
4614 | .IP "watcher invocation" 4 |
|
|
4615 | .IX Item "watcher invocation" |
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4616 | The act of calling the callback associated with a watcher. |
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4617 | .SH "AUTHOR" |
5561 | .SH "AUTHOR" |
4618 | .IX Header "AUTHOR" |
5562 | .IX Header "AUTHOR" |
4619 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5563 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
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5564 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |