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113 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
117 | to the C<double> type in C, and when you need to do any calculations on |
117 | to the C<double> type in C, and when you need to do any calculations on |
118 | it, you should treat it as some floatingpoint value. Unlike the name |
118 | it, you should treat it as some floating point value. Unlike the name |
119 | component C<stamp> might indicate, it is also used for time differences |
119 | component C<stamp> might indicate, it is also used for time differences |
120 | throughout libev. |
120 | throughout libev. |
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121 | |
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122 | =head1 ERROR HANDLING |
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123 | |
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124 | Libev knows three classes of errors: operating system errors, usage errors |
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125 | and internal errors (bugs). |
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126 | |
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127 | When libev catches an operating system error it cannot handle (for example |
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128 | a system call indicating a condition libev cannot fix), it calls the callback |
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129 | set via C<ev_set_syserr_cb>, which is supposed to fix the problem or |
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130 | abort. The default is to print a diagnostic message and to call C<abort |
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131 | ()>. |
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132 | |
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133 | When libev detects a usage error such as a negative timer interval, then |
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134 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
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135 | so C<NDEBUG> will disable this checking): these are programming errors in |
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136 | the libev caller and need to be fixed there. |
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137 | |
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138 | Libev also has a few internal error-checking C<assert>ions, and also has |
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139 | extensive consistency checking code. These do not trigger under normal |
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140 | circumstances, as they indicate either a bug in libev or worse. |
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141 | |
121 | |
142 | |
122 | =head1 GLOBAL FUNCTIONS |
143 | =head1 GLOBAL FUNCTIONS |
123 | |
144 | |
124 | These functions can be called anytime, even before initialising the |
145 | These functions can be called anytime, even before initialising the |
125 | library in any way. |
146 | library in any way. |
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134 | |
155 | |
135 | =item ev_sleep (ev_tstamp interval) |
156 | =item ev_sleep (ev_tstamp interval) |
136 | |
157 | |
137 | Sleep for the given interval: The current thread will be blocked until |
158 | Sleep for the given interval: The current thread will be blocked until |
138 | either it is interrupted or the given time interval has passed. Basically |
159 | either it is interrupted or the given time interval has passed. Basically |
139 | this is a subsecond-resolution C<sleep ()>. |
160 | this is a sub-second-resolution C<sleep ()>. |
140 | |
161 | |
141 | =item int ev_version_major () |
162 | =item int ev_version_major () |
142 | |
163 | |
143 | =item int ev_version_minor () |
164 | =item int ev_version_minor () |
144 | |
165 | |
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179 | =item unsigned int ev_recommended_backends () |
200 | =item unsigned int ev_recommended_backends () |
180 | |
201 | |
181 | Return the set of all backends compiled into this binary of libev and also |
202 | Return the set of all backends compiled into this binary of libev and also |
182 | recommended for this platform. This set is often smaller than the one |
203 | recommended for this platform. This set is often smaller than the one |
183 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
204 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
184 | most BSDs and will not be autodetected unless you explicitly request it |
205 | most BSDs and will not be auto-detected unless you explicitly request it |
185 | (assuming you know what you are doing). This is the set of backends that |
206 | (assuming you know what you are doing). This is the set of backends that |
186 | libev will probe for if you specify no backends explicitly. |
207 | libev will probe for if you specify no backends explicitly. |
187 | |
208 | |
188 | =item unsigned int ev_embeddable_backends () |
209 | =item unsigned int ev_embeddable_backends () |
189 | |
210 | |
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231 | ... |
252 | ... |
232 | ev_set_allocator (persistent_realloc); |
253 | ev_set_allocator (persistent_realloc); |
233 | |
254 | |
234 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
255 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
235 | |
256 | |
236 | Set the callback function to call on a retryable syscall error (such |
257 | Set the callback function to call on a retryable system call error (such |
237 | as failed select, poll, epoll_wait). The message is a printable string |
258 | as failed select, poll, epoll_wait). The message is a printable string |
238 | indicating the system call or subsystem causing the problem. If this |
259 | indicating the system call or subsystem causing the problem. If this |
239 | callback is set, then libev will expect it to remedy the sitution, no |
260 | callback is set, then libev will expect it to remedy the situation, no |
240 | matter what, when it returns. That is, libev will generally retry the |
261 | matter what, when it returns. That is, libev will generally retry the |
241 | requested operation, or, if the condition doesn't go away, do bad stuff |
262 | requested operation, or, if the condition doesn't go away, do bad stuff |
242 | (such as abort). |
263 | (such as abort). |
243 | |
264 | |
244 | Example: This is basically the same thing that libev does internally, too. |
265 | Example: This is basically the same thing that libev does internally, too. |
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277 | from multiple threads, you have to lock (note also that this is unlikely, |
298 | from multiple threads, you have to lock (note also that this is unlikely, |
278 | as loops cannot bes hared easily between threads anyway). |
299 | as loops cannot bes hared easily between threads anyway). |
279 | |
300 | |
280 | The default loop is the only loop that can handle C<ev_signal> and |
301 | The default loop is the only loop that can handle C<ev_signal> and |
281 | C<ev_child> watchers, and to do this, it always registers a handler |
302 | C<ev_child> watchers, and to do this, it always registers a handler |
282 | for C<SIGCHLD>. If this is a problem for your app you can either |
303 | for C<SIGCHLD>. If this is a problem for your application you can either |
283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
304 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
305 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
285 | C<ev_default_init>. |
306 | C<ev_default_init>. |
286 | |
307 | |
287 | The flags argument can be used to specify special behaviour or specific |
308 | The flags argument can be used to specify special behaviour or specific |
… | |
… | |
296 | The default flags value. Use this if you have no clue (it's the right |
317 | The default flags value. Use this if you have no clue (it's the right |
297 | thing, believe me). |
318 | thing, believe me). |
298 | |
319 | |
299 | =item C<EVFLAG_NOENV> |
320 | =item C<EVFLAG_NOENV> |
300 | |
321 | |
301 | If this flag bit is ored into the flag value (or the program runs setuid |
322 | If this flag bit is or'ed into the flag value (or the program runs setuid |
302 | or setgid) then libev will I<not> look at the environment variable |
323 | or setgid) then libev will I<not> look at the environment variable |
303 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
324 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
304 | override the flags completely if it is found in the environment. This is |
325 | override the flags completely if it is found in the environment. This is |
305 | useful to try out specific backends to test their performance, or to work |
326 | useful to try out specific backends to test their performance, or to work |
306 | around bugs. |
327 | around bugs. |
… | |
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313 | |
334 | |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
335 | This works by calling C<getpid ()> on every iteration of the loop, |
315 | and thus this might slow down your event loop if you do a lot of loop |
336 | and thus this might slow down your event loop if you do a lot of loop |
316 | iterations and little real work, but is usually not noticeable (on my |
337 | iterations and little real work, but is usually not noticeable (on my |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
338 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
339 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
319 | C<pthread_atfork> which is even faster). |
340 | C<pthread_atfork> which is even faster). |
320 | |
341 | |
321 | The big advantage of this flag is that you can forget about fork (and |
342 | The big advantage of this flag is that you can forget about fork (and |
322 | forget about forgetting to tell libev about forking) when you use this |
343 | forget about forgetting to tell libev about forking) when you use this |
323 | flag. |
344 | flag. |
324 | |
345 | |
325 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
346 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
326 | environment variable. |
347 | environment variable. |
327 | |
348 | |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
349 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
329 | |
350 | |
330 | This is your standard select(2) backend. Not I<completely> standard, as |
351 | This is your standard select(2) backend. Not I<completely> standard, as |
… | |
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332 | but if that fails, expect a fairly low limit on the number of fds when |
353 | but if that fails, expect a fairly low limit on the number of fds when |
333 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
354 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
334 | usually the fastest backend for a low number of (low-numbered :) fds. |
355 | usually the fastest backend for a low number of (low-numbered :) fds. |
335 | |
356 | |
336 | To get good performance out of this backend you need a high amount of |
357 | To get good performance out of this backend you need a high amount of |
337 | parallelity (most of the file descriptors should be busy). If you are |
358 | parallelism (most of the file descriptors should be busy). If you are |
338 | writing a server, you should C<accept ()> in a loop to accept as many |
359 | writing a server, you should C<accept ()> in a loop to accept as many |
339 | connections as possible during one iteration. You might also want to have |
360 | connections as possible during one iteration. You might also want to have |
340 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
361 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
341 | readiness notifications you get per iteration. |
362 | readiness notifications you get per iteration. |
342 | |
363 | |
… | |
… | |
354 | For few fds, this backend is a bit little slower than poll and select, |
375 | For few fds, this backend is a bit little slower than poll and select, |
355 | but it scales phenomenally better. While poll and select usually scale |
376 | but it scales phenomenally better. While poll and select usually scale |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
377 | like O(total_fds) where n is the total number of fds (or the highest fd), |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
378 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
358 | of shortcomings, such as silently dropping events in some hard-to-detect |
379 | of shortcomings, such as silently dropping events in some hard-to-detect |
359 | cases and requiring a syscall per fd change, no fork support and bad |
380 | cases and requiring a system call per fd change, no fork support and bad |
360 | support for dup. |
381 | support for dup. |
361 | |
382 | |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
383 | While stopping, setting and starting an I/O watcher in the same iteration |
363 | will result in some caching, there is still a syscall per such incident |
384 | will result in some caching, there is still a system call per such incident |
364 | (because the fd could point to a different file description now), so its |
385 | (because the fd could point to a different file description now), so its |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
386 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
366 | very well if you register events for both fds. |
387 | very well if you register events for both fds. |
367 | |
388 | |
368 | Please note that epoll sometimes generates spurious notifications, so you |
389 | Please note that epoll sometimes generates spurious notifications, so you |
… | |
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371 | |
392 | |
372 | Best performance from this backend is achieved by not unregistering all |
393 | Best performance from this backend is achieved by not unregistering all |
373 | watchers for a file descriptor until it has been closed, if possible, i.e. |
394 | watchers for a file descriptor until it has been closed, if possible, i.e. |
374 | keep at least one watcher active per fd at all times. |
395 | keep at least one watcher active per fd at all times. |
375 | |
396 | |
376 | While nominally embeddeble in other event loops, this feature is broken in |
397 | While nominally embeddable in other event loops, this feature is broken in |
377 | all kernel versions tested so far. |
398 | all kernel versions tested so far. |
378 | |
399 | |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
400 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
380 | |
401 | |
381 | Kqueue deserves special mention, as at the time of this writing, it |
402 | Kqueue deserves special mention, as at the time of this writing, it |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
403 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
383 | with anything but sockets and pipes, except on Darwin, where of course |
404 | with anything but sockets and pipes, except on Darwin, where of course |
384 | it's completely useless). For this reason it's not being "autodetected" |
405 | it's completely useless). For this reason it's not being "auto-detected" |
385 | unless you explicitly specify it explicitly in the flags (i.e. using |
406 | unless you explicitly specify it explicitly in the flags (i.e. using |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
407 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
387 | system like NetBSD. |
408 | system like NetBSD. |
388 | |
409 | |
389 | You still can embed kqueue into a normal poll or select backend and use it |
410 | You still can embed kqueue into a normal poll or select backend and use it |
… | |
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391 | the target platform). See C<ev_embed> watchers for more info. |
412 | the target platform). See C<ev_embed> watchers for more info. |
392 | |
413 | |
393 | It scales in the same way as the epoll backend, but the interface to the |
414 | It scales in the same way as the epoll backend, but the interface to the |
394 | kernel is more efficient (which says nothing about its actual speed, of |
415 | kernel is more efficient (which says nothing about its actual speed, of |
395 | course). While stopping, setting and starting an I/O watcher does never |
416 | course). While stopping, setting and starting an I/O watcher does never |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
417 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
418 | two event changes per incident, support for C<fork ()> is very bad and it |
398 | drops fds silently in similarly hard-to-detect cases. |
419 | drops fds silently in similarly hard-to-detect cases. |
399 | |
420 | |
400 | This backend usually performs well under most conditions. |
421 | This backend usually performs well under most conditions. |
401 | |
422 | |
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416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
437 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
417 | |
438 | |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
439 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
419 | it's really slow, but it still scales very well (O(active_fds)). |
440 | it's really slow, but it still scales very well (O(active_fds)). |
420 | |
441 | |
421 | Please note that solaris event ports can deliver a lot of spurious |
442 | Please note that Solaris event ports can deliver a lot of spurious |
422 | notifications, so you need to use non-blocking I/O or other means to avoid |
443 | notifications, so you need to use non-blocking I/O or other means to avoid |
423 | blocking when no data (or space) is available. |
444 | blocking when no data (or space) is available. |
424 | |
445 | |
425 | While this backend scales well, it requires one system call per active |
446 | While this backend scales well, it requires one system call per active |
426 | file descriptor per loop iteration. For small and medium numbers of file |
447 | file descriptor per loop iteration. For small and medium numbers of file |
… | |
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439 | |
460 | |
440 | It is definitely not recommended to use this flag. |
461 | It is definitely not recommended to use this flag. |
441 | |
462 | |
442 | =back |
463 | =back |
443 | |
464 | |
444 | If one or more of these are ored into the flags value, then only these |
465 | If one or more of these are or'ed into the flags value, then only these |
445 | backends will be tried (in the reverse order as listed here). If none are |
466 | backends will be tried (in the reverse order as listed here). If none are |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
467 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
447 | |
468 | |
448 | The most typical usage is like this: |
469 | The most typical usage is like this: |
449 | |
470 | |
… | |
… | |
481 | =item ev_default_destroy () |
502 | =item ev_default_destroy () |
482 | |
503 | |
483 | Destroys the default loop again (frees all memory and kernel state |
504 | Destroys the default loop again (frees all memory and kernel state |
484 | etc.). None of the active event watchers will be stopped in the normal |
505 | etc.). None of the active event watchers will be stopped in the normal |
485 | sense, so e.g. C<ev_is_active> might still return true. It is your |
506 | sense, so e.g. C<ev_is_active> might still return true. It is your |
486 | responsibility to either stop all watchers cleanly yoursef I<before> |
507 | responsibility to either stop all watchers cleanly yourself I<before> |
487 | calling this function, or cope with the fact afterwards (which is usually |
508 | calling this function, or cope with the fact afterwards (which is usually |
488 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
509 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
489 | for example). |
510 | for example). |
490 | |
511 | |
491 | Note that certain global state, such as signal state, will not be freed by |
512 | Note that certain global state, such as signal state, will not be freed by |
… | |
… | |
572 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
593 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
573 | those events and any outstanding ones, but will not block your process in |
594 | those events and any outstanding ones, but will not block your process in |
574 | case there are no events and will return after one iteration of the loop. |
595 | case there are no events and will return after one iteration of the loop. |
575 | |
596 | |
576 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
597 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
577 | neccessary) and will handle those and any outstanding ones. It will block |
598 | necessary) and will handle those and any outstanding ones. It will block |
578 | your process until at least one new event arrives, and will return after |
599 | your process until at least one new event arrives, and will return after |
579 | one iteration of the loop. This is useful if you are waiting for some |
600 | one iteration of the loop. This is useful if you are waiting for some |
580 | external event in conjunction with something not expressible using other |
601 | external event in conjunction with something not expressible using other |
581 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
602 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
582 | usually a better approach for this kind of thing. |
603 | usually a better approach for this kind of thing. |
… | |
… | |
683 | to spend more time collecting timeouts, at the expense of increased |
704 | to spend more time collecting timeouts, at the expense of increased |
684 | latency (the watcher callback will be called later). C<ev_io> watchers |
705 | latency (the watcher callback will be called later). C<ev_io> watchers |
685 | will not be affected. Setting this to a non-null value will not introduce |
706 | will not be affected. Setting this to a non-null value will not introduce |
686 | any overhead in libev. |
707 | any overhead in libev. |
687 | |
708 | |
688 | Many (busy) programs can usually benefit by setting the io collect |
709 | Many (busy) programs can usually benefit by setting the I/O collect |
689 | interval to a value near C<0.1> or so, which is often enough for |
710 | interval to a value near C<0.1> or so, which is often enough for |
690 | interactive servers (of course not for games), likewise for timeouts. It |
711 | interactive servers (of course not for games), likewise for timeouts. It |
691 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
712 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
692 | as this approsaches the timing granularity of most systems. |
713 | as this approaches the timing granularity of most systems. |
693 | |
714 | |
694 | =item ev_loop_verify (loop) |
715 | =item ev_loop_verify (loop) |
695 | |
716 | |
696 | This function only does something when C<EV_VERIFY> support has been |
717 | This function only does something when C<EV_VERIFY> support has been |
697 | compiled in. It tries to go through all internal structures and checks |
718 | compiled in. It tries to go through all internal structures and checks |
… | |
… | |
728 | watcher structures (and it is usually a bad idea to do this on the stack, |
749 | watcher structures (and it is usually a bad idea to do this on the stack, |
729 | although this can sometimes be quite valid). |
750 | although this can sometimes be quite valid). |
730 | |
751 | |
731 | Each watcher structure must be initialised by a call to C<ev_init |
752 | Each watcher structure must be initialised by a call to C<ev_init |
732 | (watcher *, callback)>, which expects a callback to be provided. This |
753 | (watcher *, callback)>, which expects a callback to be provided. This |
733 | callback gets invoked each time the event occurs (or, in the case of io |
754 | callback gets invoked each time the event occurs (or, in the case of I/O |
734 | watchers, each time the event loop detects that the file descriptor given |
755 | watchers, each time the event loop detects that the file descriptor given |
735 | is readable and/or writable). |
756 | is readable and/or writable). |
736 | |
757 | |
737 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
758 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
738 | with arguments specific to this watcher type. There is also a macro |
759 | with arguments specific to this watcher type. There is also a macro |
… | |
… | |
814 | |
835 | |
815 | The given async watcher has been asynchronously notified (see C<ev_async>). |
836 | The given async watcher has been asynchronously notified (see C<ev_async>). |
816 | |
837 | |
817 | =item C<EV_ERROR> |
838 | =item C<EV_ERROR> |
818 | |
839 | |
819 | An unspecified error has occured, the watcher has been stopped. This might |
840 | An unspecified error has occurred, the watcher has been stopped. This might |
820 | happen because the watcher could not be properly started because libev |
841 | happen because the watcher could not be properly started because libev |
821 | ran out of memory, a file descriptor was found to be closed or any other |
842 | ran out of memory, a file descriptor was found to be closed or any other |
822 | problem. You best act on it by reporting the problem and somehow coping |
843 | problem. You best act on it by reporting the problem and somehow coping |
823 | with the watcher being stopped. |
844 | with the watcher being stopped. |
824 | |
845 | |
825 | Libev will usually signal a few "dummy" events together with an error, |
846 | Libev will usually signal a few "dummy" events together with an error, |
826 | for example it might indicate that a fd is readable or writable, and if |
847 | for example it might indicate that a fd is readable or writable, and if |
827 | your callbacks is well-written it can just attempt the operation and cope |
848 | your callbacks is well-written it can just attempt the operation and cope |
828 | with the error from read() or write(). This will not work in multithreaded |
849 | with the error from read() or write(). This will not work in multi-threaded |
829 | programs, though, so beware. |
850 | programs, though, so beware. |
830 | |
851 | |
831 | =back |
852 | =back |
832 | |
853 | |
833 | =head2 GENERIC WATCHER FUNCTIONS |
854 | =head2 GENERIC WATCHER FUNCTIONS |
… | |
… | |
863 | Although some watcher types do not have type-specific arguments |
884 | Although some watcher types do not have type-specific arguments |
864 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
885 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
865 | |
886 | |
866 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
887 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
867 | |
888 | |
868 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
889 | This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
869 | calls into a single call. This is the most convinient method to initialise |
890 | calls into a single call. This is the most convenient method to initialise |
870 | a watcher. The same limitations apply, of course. |
891 | a watcher. The same limitations apply, of course. |
871 | |
892 | |
872 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
893 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
873 | |
894 | |
874 | Starts (activates) the given watcher. Only active watchers will receive |
895 | Starts (activates) the given watcher. Only active watchers will receive |
… | |
… | |
1046 | |
1067 | |
1047 | Another thing you have to watch out for is that it is quite easy to |
1068 | Another thing you have to watch out for is that it is quite easy to |
1048 | receive "spurious" readiness notifications, that is your callback might |
1069 | receive "spurious" readiness notifications, that is your callback might |
1049 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1070 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1050 | because there is no data. Not only are some backends known to create a |
1071 | because there is no data. Not only are some backends known to create a |
1051 | lot of those (for example solaris ports), it is very easy to get into |
1072 | lot of those (for example Solaris ports), it is very easy to get into |
1052 | this situation even with a relatively standard program structure. Thus |
1073 | this situation even with a relatively standard program structure. Thus |
1053 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1074 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1054 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1075 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1055 | |
1076 | |
1056 | If you cannot run the fd in non-blocking mode (for example you should not |
1077 | If you cannot run the fd in non-blocking mode (for example you should not |
1057 | play around with an Xlib connection), then you have to seperately re-test |
1078 | play around with an Xlib connection), then you have to separately re-test |
1058 | whether a file descriptor is really ready with a known-to-be good interface |
1079 | whether a file descriptor is really ready with a known-to-be good interface |
1059 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1080 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1060 | its own, so its quite safe to use). |
1081 | its own, so its quite safe to use). |
1061 | |
1082 | |
1062 | =head3 The special problem of disappearing file descriptors |
1083 | =head3 The special problem of disappearing file descriptors |
… | |
… | |
1122 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1143 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1123 | |
1144 | |
1124 | =item ev_io_set (ev_io *, int fd, int events) |
1145 | =item ev_io_set (ev_io *, int fd, int events) |
1125 | |
1146 | |
1126 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1147 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1127 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1148 | receive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1128 | C<EV_READ | EV_WRITE> to receive the given events. |
1149 | C<EV_READ | EV_WRITE> to receive the given events. |
1129 | |
1150 | |
1130 | =item int fd [read-only] |
1151 | =item int fd [read-only] |
1131 | |
1152 | |
1132 | The file descriptor being watched. |
1153 | The file descriptor being watched. |
… | |
… | |
1162 | |
1183 | |
1163 | Timer watchers are simple relative timers that generate an event after a |
1184 | Timer watchers are simple relative timers that generate an event after a |
1164 | given time, and optionally repeating in regular intervals after that. |
1185 | given time, and optionally repeating in regular intervals after that. |
1165 | |
1186 | |
1166 | The timers are based on real time, that is, if you register an event that |
1187 | The timers are based on real time, that is, if you register an event that |
1167 | times out after an hour and you reset your system clock to january last |
1188 | times out after an hour and you reset your system clock to January last |
1168 | year, it will still time out after (roughly) and hour. "Roughly" because |
1189 | year, it will still time out after (roughly) and hour. "Roughly" because |
1169 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1190 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1170 | monotonic clock option helps a lot here). |
1191 | monotonic clock option helps a lot here). |
1171 | |
1192 | |
1172 | The relative timeouts are calculated relative to the C<ev_now ()> |
1193 | The relative timeouts are calculated relative to the C<ev_now ()> |
… | |
… | |
1175 | you suspect event processing to be delayed and you I<need> to base the timeout |
1196 | you suspect event processing to be delayed and you I<need> to base the timeout |
1176 | on the current time, use something like this to adjust for this: |
1197 | on the current time, use something like this to adjust for this: |
1177 | |
1198 | |
1178 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1199 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1179 | |
1200 | |
1180 | The callback is guarenteed to be invoked only after its timeout has passed, |
1201 | The callback is guaranteed to be invoked only after its timeout has passed, |
1181 | but if multiple timers become ready during the same loop iteration then |
1202 | but if multiple timers become ready during the same loop iteration then |
1182 | order of execution is undefined. |
1203 | order of execution is undefined. |
1183 | |
1204 | |
1184 | =head3 Watcher-Specific Functions and Data Members |
1205 | =head3 Watcher-Specific Functions and Data Members |
1185 | |
1206 | |
… | |
… | |
1206 | This will act as if the timer timed out and restart it again if it is |
1227 | This will act as if the timer timed out and restart it again if it is |
1207 | repeating. The exact semantics are: |
1228 | repeating. The exact semantics are: |
1208 | |
1229 | |
1209 | If the timer is pending, its pending status is cleared. |
1230 | If the timer is pending, its pending status is cleared. |
1210 | |
1231 | |
1211 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1232 | If the timer is started but non-repeating, stop it (as if it timed out). |
1212 | |
1233 | |
1213 | If the timer is repeating, either start it if necessary (with the |
1234 | If the timer is repeating, either start it if necessary (with the |
1214 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1235 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1215 | |
1236 | |
1216 | This sounds a bit complicated, but here is a useful and typical |
1237 | This sounds a bit complicated, but here is a useful and typical |
1217 | example: Imagine you have a tcp connection and you want a so-called idle |
1238 | example: Imagine you have a TCP connection and you want a so-called idle |
1218 | timeout, that is, you want to be called when there have been, say, 60 |
1239 | timeout, that is, you want to be called when there have been, say, 60 |
1219 | seconds of inactivity on the socket. The easiest way to do this is to |
1240 | seconds of inactivity on the socket. The easiest way to do this is to |
1220 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1241 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1221 | C<ev_timer_again> each time you successfully read or write some data. If |
1242 | C<ev_timer_again> each time you successfully read or write some data. If |
1222 | you go into an idle state where you do not expect data to travel on the |
1243 | you go into an idle state where you do not expect data to travel on the |
… | |
… | |
1283 | |
1304 | |
1284 | Periodic watchers are also timers of a kind, but they are very versatile |
1305 | Periodic watchers are also timers of a kind, but they are very versatile |
1285 | (and unfortunately a bit complex). |
1306 | (and unfortunately a bit complex). |
1286 | |
1307 | |
1287 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1308 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1288 | but on wallclock time (absolute time). You can tell a periodic watcher |
1309 | but on wall clock time (absolute time). You can tell a periodic watcher |
1289 | to trigger after some specific point in time. For example, if you tell a |
1310 | to trigger after some specific point in time. For example, if you tell a |
1290 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1311 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1291 | + 10.>, that is, an absolute time not a delay) and then reset your system |
1312 | + 10.>, that is, an absolute time not a delay) and then reset your system |
1292 | clock to january of the previous year, then it will take more than year |
1313 | clock to January of the previous year, then it will take more than year |
1293 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
1314 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
1294 | roughly 10 seconds later as it uses a relative timeout). |
1315 | roughly 10 seconds later as it uses a relative timeout). |
1295 | |
1316 | |
1296 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1317 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1297 | such as triggering an event on each "midnight, local time", or other |
1318 | such as triggering an event on each "midnight, local time", or other |
1298 | complicated, rules. |
1319 | complicated, rules. |
1299 | |
1320 | |
1300 | As with timers, the callback is guarenteed to be invoked only when the |
1321 | As with timers, the callback is guaranteed to be invoked only when the |
1301 | time (C<at>) has passed, but if multiple periodic timers become ready |
1322 | time (C<at>) has passed, but if multiple periodic timers become ready |
1302 | during the same loop iteration then order of execution is undefined. |
1323 | during the same loop iteration then order of execution is undefined. |
1303 | |
1324 | |
1304 | =head3 Watcher-Specific Functions and Data Members |
1325 | =head3 Watcher-Specific Functions and Data Members |
1305 | |
1326 | |
… | |
… | |
1314 | |
1335 | |
1315 | =over 4 |
1336 | =over 4 |
1316 | |
1337 | |
1317 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1338 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1318 | |
1339 | |
1319 | In this configuration the watcher triggers an event after the wallclock |
1340 | In this configuration the watcher triggers an event after the wall clock |
1320 | time C<at> has passed and doesn't repeat. It will not adjust when a time |
1341 | time C<at> has passed and doesn't repeat. It will not adjust when a time |
1321 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1342 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1322 | run when the system time reaches or surpasses this time. |
1343 | run when the system time reaches or surpasses this time. |
1323 | |
1344 | |
1324 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1345 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
… | |
… | |
1332 | the hour: |
1353 | the hour: |
1333 | |
1354 | |
1334 | ev_periodic_set (&periodic, 0., 3600., 0); |
1355 | ev_periodic_set (&periodic, 0., 3600., 0); |
1335 | |
1356 | |
1336 | This doesn't mean there will always be 3600 seconds in between triggers, |
1357 | This doesn't mean there will always be 3600 seconds in between triggers, |
1337 | but only that the the callback will be called when the system time shows a |
1358 | but only that the callback will be called when the system time shows a |
1338 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1359 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1339 | by 3600. |
1360 | by 3600. |
1340 | |
1361 | |
1341 | Another way to think about it (for the mathematically inclined) is that |
1362 | Another way to think about it (for the mathematically inclined) is that |
1342 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1363 | C<ev_periodic> will try to run the callback in this mode at the next possible |
… | |
… | |
1344 | |
1365 | |
1345 | For numerical stability it is preferable that the C<at> value is near |
1366 | For numerical stability it is preferable that the C<at> value is near |
1346 | C<ev_now ()> (the current time), but there is no range requirement for |
1367 | C<ev_now ()> (the current time), but there is no range requirement for |
1347 | this value, and in fact is often specified as zero. |
1368 | this value, and in fact is often specified as zero. |
1348 | |
1369 | |
1349 | Note also that there is an upper limit to how often a timer can fire (cpu |
1370 | Note also that there is an upper limit to how often a timer can fire (CPU |
1350 | speed for example), so if C<interval> is very small then timing stability |
1371 | speed for example), so if C<interval> is very small then timing stability |
1351 | will of course detoriate. Libev itself tries to be exact to be about one |
1372 | will of course deteriorate. Libev itself tries to be exact to be about one |
1352 | millisecond (if the OS supports it and the machine is fast enough). |
1373 | millisecond (if the OS supports it and the machine is fast enough). |
1353 | |
1374 | |
1354 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1375 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1355 | |
1376 | |
1356 | In this mode the values for C<interval> and C<at> are both being |
1377 | In this mode the values for C<interval> and C<at> are both being |
… | |
… | |
1425 | |
1446 | |
1426 | =head3 Examples |
1447 | =head3 Examples |
1427 | |
1448 | |
1428 | Example: Call a callback every hour, or, more precisely, whenever the |
1449 | Example: Call a callback every hour, or, more precisely, whenever the |
1429 | system clock is divisible by 3600. The callback invocation times have |
1450 | system clock is divisible by 3600. The callback invocation times have |
1430 | potentially a lot of jittering, but good long-term stability. |
1451 | potentially a lot of jitter, but good long-term stability. |
1431 | |
1452 | |
1432 | static void |
1453 | static void |
1433 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1454 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1434 | { |
1455 | { |
1435 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1456 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
… | |
… | |
1472 | as you don't register any with libev). Similarly, when the last signal |
1493 | as you don't register any with libev). Similarly, when the last signal |
1473 | watcher for a signal is stopped libev will reset the signal handler to |
1494 | watcher for a signal is stopped libev will reset the signal handler to |
1474 | SIG_DFL (regardless of what it was set to before). |
1495 | SIG_DFL (regardless of what it was set to before). |
1475 | |
1496 | |
1476 | If possible and supported, libev will install its handlers with |
1497 | If possible and supported, libev will install its handlers with |
1477 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
1498 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
1478 | interrupted. If you have a problem with syscalls getting interrupted by |
1499 | interrupted. If you have a problem with system calls getting interrupted by |
1479 | signals you can block all signals in an C<ev_check> watcher and unblock |
1500 | signals you can block all signals in an C<ev_check> watcher and unblock |
1480 | them in an C<ev_prepare> watcher. |
1501 | them in an C<ev_prepare> watcher. |
1481 | |
1502 | |
1482 | =head3 Watcher-Specific Functions and Data Members |
1503 | =head3 Watcher-Specific Functions and Data Members |
1483 | |
1504 | |
… | |
… | |
1518 | is permissible to install a child watcher I<after> the child has been |
1539 | is permissible to install a child watcher I<after> the child has been |
1519 | forked (which implies it might have already exited), as long as the event |
1540 | forked (which implies it might have already exited), as long as the event |
1520 | loop isn't entered (or is continued from a watcher). |
1541 | loop isn't entered (or is continued from a watcher). |
1521 | |
1542 | |
1522 | Only the default event loop is capable of handling signals, and therefore |
1543 | Only the default event loop is capable of handling signals, and therefore |
1523 | you can only rgeister child watchers in the default event loop. |
1544 | you can only register child watchers in the default event loop. |
1524 | |
1545 | |
1525 | =head3 Process Interaction |
1546 | =head3 Process Interaction |
1526 | |
1547 | |
1527 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1548 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1528 | initialised. This is necessary to guarantee proper behaviour even if |
1549 | initialised. This is necessary to guarantee proper behaviour even if |
1529 | the first child watcher is started after the child exits. The occurance |
1550 | the first child watcher is started after the child exits. The occurrence |
1530 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1551 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1531 | synchronously as part of the event loop processing. Libev always reaps all |
1552 | synchronously as part of the event loop processing. Libev always reaps all |
1532 | children, even ones not watched. |
1553 | children, even ones not watched. |
1533 | |
1554 | |
1534 | =head3 Overriding the Built-In Processing |
1555 | =head3 Overriding the Built-In Processing |
… | |
… | |
1603 | } |
1624 | } |
1604 | |
1625 | |
1605 | |
1626 | |
1606 | =head2 C<ev_stat> - did the file attributes just change? |
1627 | =head2 C<ev_stat> - did the file attributes just change? |
1607 | |
1628 | |
1608 | This watches a filesystem path for attribute changes. That is, it calls |
1629 | This watches a file system path for attribute changes. That is, it calls |
1609 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1630 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1610 | compared to the last time, invoking the callback if it did. |
1631 | compared to the last time, invoking the callback if it did. |
1611 | |
1632 | |
1612 | The path does not need to exist: changing from "path exists" to "path does |
1633 | The path does not need to exist: changing from "path exists" to "path does |
1613 | not exist" is a status change like any other. The condition "path does |
1634 | not exist" is a status change like any other. The condition "path does |
… | |
… | |
1647 | disabled large file support, you get the 32 bit version of the stat |
1668 | disabled large file support, you get the 32 bit version of the stat |
1648 | structure. When using the library from programs that change the ABI to |
1669 | structure. When using the library from programs that change the ABI to |
1649 | use 64 bit file offsets the programs will fail. In that case you have to |
1670 | use 64 bit file offsets the programs will fail. In that case you have to |
1650 | compile libev with the same flags to get binary compatibility. This is |
1671 | compile libev with the same flags to get binary compatibility. This is |
1651 | obviously the case with any flags that change the ABI, but the problem is |
1672 | obviously the case with any flags that change the ABI, but the problem is |
1652 | most noticably with ev_stat and largefile support. |
1673 | most noticeably with ev_stat and large file support. |
1653 | |
1674 | |
1654 | =head3 Inotify |
1675 | =head3 Inotify |
1655 | |
1676 | |
1656 | When C<inotify (7)> support has been compiled into libev (generally only |
1677 | When C<inotify (7)> support has been compiled into libev (generally only |
1657 | available on Linux) and present at runtime, it will be used to speed up |
1678 | available on Linux) and present at runtime, it will be used to speed up |
… | |
… | |
1667 | implement this functionality, due to the requirement of having a file |
1688 | implement this functionality, due to the requirement of having a file |
1668 | descriptor open on the object at all times). |
1689 | descriptor open on the object at all times). |
1669 | |
1690 | |
1670 | =head3 The special problem of stat time resolution |
1691 | =head3 The special problem of stat time resolution |
1671 | |
1692 | |
1672 | The C<stat ()> syscall only supports full-second resolution portably, and |
1693 | The C<stat ()> system call only supports full-second resolution portably, and |
1673 | even on systems where the resolution is higher, many filesystems still |
1694 | even on systems where the resolution is higher, many file systems still |
1674 | only support whole seconds. |
1695 | only support whole seconds. |
1675 | |
1696 | |
1676 | That means that, if the time is the only thing that changes, you can |
1697 | That means that, if the time is the only thing that changes, you can |
1677 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1698 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1678 | calls your callback, which does something. When there is another update |
1699 | calls your callback, which does something. When there is another update |
… | |
… | |
1738 | |
1759 | |
1739 | The specified interval. |
1760 | The specified interval. |
1740 | |
1761 | |
1741 | =item const char *path [read-only] |
1762 | =item const char *path [read-only] |
1742 | |
1763 | |
1743 | The filesystem path that is being watched. |
1764 | The file system path that is being watched. |
1744 | |
1765 | |
1745 | =back |
1766 | =back |
1746 | |
1767 | |
1747 | =head3 Examples |
1768 | =head3 Examples |
1748 | |
1769 | |
… | |
… | |
1874 | |
1895 | |
1875 | This is done by examining in each prepare call which file descriptors need |
1896 | This is done by examining in each prepare call which file descriptors need |
1876 | to be watched by the other library, registering C<ev_io> watchers for |
1897 | to be watched by the other library, registering C<ev_io> watchers for |
1877 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1898 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1878 | provide just this functionality). Then, in the check watcher you check for |
1899 | provide just this functionality). Then, in the check watcher you check for |
1879 | any events that occured (by checking the pending status of all watchers |
1900 | any events that occurred (by checking the pending status of all watchers |
1880 | and stopping them) and call back into the library. The I/O and timer |
1901 | and stopping them) and call back into the library. The I/O and timer |
1881 | callbacks will never actually be called (but must be valid nevertheless, |
1902 | callbacks will never actually be called (but must be valid nevertheless, |
1882 | because you never know, you know?). |
1903 | because you never know, you know?). |
1883 | |
1904 | |
1884 | As another example, the Perl Coro module uses these hooks to integrate |
1905 | As another example, the Perl Coro module uses these hooks to integrate |
… | |
… | |
1986 | |
2007 | |
1987 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
2008 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
1988 | in the prepare watcher and would dispose of the check watcher. |
2009 | in the prepare watcher and would dispose of the check watcher. |
1989 | |
2010 | |
1990 | Method 3: If the module to be embedded supports explicit event |
2011 | Method 3: If the module to be embedded supports explicit event |
1991 | notification (adns does), you can also make use of the actual watcher |
2012 | notification (libadns does), you can also make use of the actual watcher |
1992 | callbacks, and only destroy/create the watchers in the prepare watcher. |
2013 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1993 | |
2014 | |
1994 | static void |
2015 | static void |
1995 | timer_cb (EV_P_ ev_timer *w, int revents) |
2016 | timer_cb (EV_P_ ev_timer *w, int revents) |
1996 | { |
2017 | { |
… | |
… | |
2011 | } |
2032 | } |
2012 | |
2033 | |
2013 | // do not ever call adns_afterpoll |
2034 | // do not ever call adns_afterpoll |
2014 | |
2035 | |
2015 | Method 4: Do not use a prepare or check watcher because the module you |
2036 | Method 4: Do not use a prepare or check watcher because the module you |
2016 | want to embed is too inflexible to support it. Instead, youc na override |
2037 | want to embed is too inflexible to support it. Instead, you can override |
2017 | their poll function. The drawback with this solution is that the main |
2038 | their poll function. The drawback with this solution is that the main |
2018 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
2039 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
2019 | this. |
2040 | this. |
2020 | |
2041 | |
2021 | static gint |
2042 | static gint |
… | |
… | |
2105 | |
2126 | |
2106 | Configures the watcher to embed the given loop, which must be |
2127 | Configures the watcher to embed the given loop, which must be |
2107 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2128 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2108 | invoked automatically, otherwise it is the responsibility of the callback |
2129 | invoked automatically, otherwise it is the responsibility of the callback |
2109 | to invoke it (it will continue to be called until the sweep has been done, |
2130 | to invoke it (it will continue to be called until the sweep has been done, |
2110 | if you do not want thta, you need to temporarily stop the embed watcher). |
2131 | if you do not want that, you need to temporarily stop the embed watcher). |
2111 | |
2132 | |
2112 | =item ev_embed_sweep (loop, ev_embed *) |
2133 | =item ev_embed_sweep (loop, ev_embed *) |
2113 | |
2134 | |
2114 | Make a single, non-blocking sweep over the embedded loop. This works |
2135 | Make a single, non-blocking sweep over the embedded loop. This works |
2115 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2136 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2116 | apropriate way for embedded loops. |
2137 | appropriate way for embedded loops. |
2117 | |
2138 | |
2118 | =item struct ev_loop *other [read-only] |
2139 | =item struct ev_loop *other [read-only] |
2119 | |
2140 | |
2120 | The embedded event loop. |
2141 | The embedded event loop. |
2121 | |
2142 | |
… | |
… | |
2123 | |
2144 | |
2124 | =head3 Examples |
2145 | =head3 Examples |
2125 | |
2146 | |
2126 | Example: Try to get an embeddable event loop and embed it into the default |
2147 | Example: Try to get an embeddable event loop and embed it into the default |
2127 | event loop. If that is not possible, use the default loop. The default |
2148 | event loop. If that is not possible, use the default loop. The default |
2128 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
2149 | loop is stored in C<loop_hi>, while the embeddable loop is stored in |
2129 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
2150 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2130 | used). |
2151 | used). |
2131 | |
2152 | |
2132 | struct ev_loop *loop_hi = ev_default_init (0); |
2153 | struct ev_loop *loop_hi = ev_default_init (0); |
2133 | struct ev_loop *loop_lo = 0; |
2154 | struct ev_loop *loop_lo = 0; |
2134 | struct ev_embed embed; |
2155 | struct ev_embed embed; |
… | |
… | |
2228 | |
2249 | |
2229 | =item queueing from a signal handler context |
2250 | =item queueing from a signal handler context |
2230 | |
2251 | |
2231 | To implement race-free queueing, you simply add to the queue in the signal |
2252 | To implement race-free queueing, you simply add to the queue in the signal |
2232 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
2253 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
2233 | some fictitiuous SIGUSR1 handler: |
2254 | some fictitious SIGUSR1 handler: |
2234 | |
2255 | |
2235 | static ev_async mysig; |
2256 | static ev_async mysig; |
2236 | |
2257 | |
2237 | static void |
2258 | static void |
2238 | sigusr1_handler (void) |
2259 | sigusr1_handler (void) |
… | |
… | |
2312 | =item ev_async_send (loop, ev_async *) |
2333 | =item ev_async_send (loop, ev_async *) |
2313 | |
2334 | |
2314 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2335 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2315 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2336 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2316 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
2337 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
2317 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
2338 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2318 | section below on what exactly this means). |
2339 | section below on what exactly this means). |
2319 | |
2340 | |
2320 | This call incurs the overhead of a syscall only once per loop iteration, |
2341 | This call incurs the overhead of a system call only once per loop iteration, |
2321 | so while the overhead might be noticable, it doesn't apply to repeated |
2342 | so while the overhead might be noticeable, it doesn't apply to repeated |
2322 | calls to C<ev_async_send>. |
2343 | calls to C<ev_async_send>. |
2323 | |
2344 | |
2324 | =item bool = ev_async_pending (ev_async *) |
2345 | =item bool = ev_async_pending (ev_async *) |
2325 | |
2346 | |
2326 | Returns a non-zero value when C<ev_async_send> has been called on the |
2347 | Returns a non-zero value when C<ev_async_send> has been called on the |
… | |
… | |
2328 | event loop. |
2349 | event loop. |
2329 | |
2350 | |
2330 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2351 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2331 | the loop iterates next and checks for the watcher to have become active, |
2352 | the loop iterates next and checks for the watcher to have become active, |
2332 | it will reset the flag again. C<ev_async_pending> can be used to very |
2353 | it will reset the flag again. C<ev_async_pending> can be used to very |
2333 | quickly check wether invoking the loop might be a good idea. |
2354 | quickly check whether invoking the loop might be a good idea. |
2334 | |
2355 | |
2335 | Not that this does I<not> check wether the watcher itself is pending, only |
2356 | Not that this does I<not> check whether the watcher itself is pending, only |
2336 | wether it has been requested to make this watcher pending. |
2357 | whether it has been requested to make this watcher pending. |
2337 | |
2358 | |
2338 | =back |
2359 | =back |
2339 | |
2360 | |
2340 | |
2361 | |
2341 | =head1 OTHER FUNCTIONS |
2362 | =head1 OTHER FUNCTIONS |
… | |
… | |
2352 | or timeout without having to allocate/configure/start/stop/free one or |
2373 | or timeout without having to allocate/configure/start/stop/free one or |
2353 | more watchers yourself. |
2374 | more watchers yourself. |
2354 | |
2375 | |
2355 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2376 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2356 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2377 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2357 | C<events> set will be craeted and started. |
2378 | C<events> set will be created and started. |
2358 | |
2379 | |
2359 | If C<timeout> is less than 0, then no timeout watcher will be |
2380 | If C<timeout> is less than 0, then no timeout watcher will be |
2360 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2381 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2361 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2382 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2362 | dubious value. |
2383 | dubious value. |
… | |
… | |
2387 | Feed an event on the given fd, as if a file descriptor backend detected |
2408 | Feed an event on the given fd, as if a file descriptor backend detected |
2388 | the given events it. |
2409 | the given events it. |
2389 | |
2410 | |
2390 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2411 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2391 | |
2412 | |
2392 | Feed an event as if the given signal occured (C<loop> must be the default |
2413 | Feed an event as if the given signal occurred (C<loop> must be the default |
2393 | loop!). |
2414 | loop!). |
2394 | |
2415 | |
2395 | =back |
2416 | =back |
2396 | |
2417 | |
2397 | |
2418 | |
… | |
… | |
2426 | =back |
2447 | =back |
2427 | |
2448 | |
2428 | =head1 C++ SUPPORT |
2449 | =head1 C++ SUPPORT |
2429 | |
2450 | |
2430 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2451 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2431 | you to use some convinience methods to start/stop watchers and also change |
2452 | you to use some convenience methods to start/stop watchers and also change |
2432 | the callback model to a model using method callbacks on objects. |
2453 | the callback model to a model using method callbacks on objects. |
2433 | |
2454 | |
2434 | To use it, |
2455 | To use it, |
2435 | |
2456 | |
2436 | #include <ev++.h> |
2457 | #include <ev++.h> |
… | |
… | |
2537 | =item w->set (struct ev_loop *) |
2558 | =item w->set (struct ev_loop *) |
2538 | |
2559 | |
2539 | Associates a different C<struct ev_loop> with this watcher. You can only |
2560 | Associates a different C<struct ev_loop> with this watcher. You can only |
2540 | do this when the watcher is inactive (and not pending either). |
2561 | do this when the watcher is inactive (and not pending either). |
2541 | |
2562 | |
2542 | =item w->set ([args]) |
2563 | =item w->set ([arguments]) |
2543 | |
2564 | |
2544 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2565 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
2545 | called at least once. Unlike the C counterpart, an active watcher gets |
2566 | called at least once. Unlike the C counterpart, an active watcher gets |
2546 | automatically stopped and restarted when reconfiguring it with this |
2567 | automatically stopped and restarted when reconfiguring it with this |
2547 | method. |
2568 | method. |
2548 | |
2569 | |
2549 | =item w->start () |
2570 | =item w->start () |
… | |
… | |
2591 | |
2612 | |
2592 | |
2613 | |
2593 | =head1 OTHER LANGUAGE BINDINGS |
2614 | =head1 OTHER LANGUAGE BINDINGS |
2594 | |
2615 | |
2595 | Libev does not offer other language bindings itself, but bindings for a |
2616 | Libev does not offer other language bindings itself, but bindings for a |
2596 | numbe rof languages exist in the form of third-party packages. If you know |
2617 | number of languages exist in the form of third-party packages. If you know |
2597 | any interesting language binding in addition to the ones listed here, drop |
2618 | any interesting language binding in addition to the ones listed here, drop |
2598 | me a note. |
2619 | me a note. |
2599 | |
2620 | |
2600 | =over 4 |
2621 | =over 4 |
2601 | |
2622 | |
… | |
… | |
2611 | L<http://software.schmorp.de/pkg/EV>. |
2632 | L<http://software.schmorp.de/pkg/EV>. |
2612 | |
2633 | |
2613 | =item Ruby |
2634 | =item Ruby |
2614 | |
2635 | |
2615 | Tony Arcieri has written a ruby extension that offers access to a subset |
2636 | Tony Arcieri has written a ruby extension that offers access to a subset |
2616 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
2637 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2617 | more on top of it. It can be found via gem servers. Its homepage is at |
2638 | more on top of it. It can be found via gem servers. Its homepage is at |
2618 | L<http://rev.rubyforge.org/>. |
2639 | L<http://rev.rubyforge.org/>. |
2619 | |
2640 | |
2620 | =item D |
2641 | =item D |
2621 | |
2642 | |
… | |
… | |
2625 | =back |
2646 | =back |
2626 | |
2647 | |
2627 | |
2648 | |
2628 | =head1 MACRO MAGIC |
2649 | =head1 MACRO MAGIC |
2629 | |
2650 | |
2630 | Libev can be compiled with a variety of options, the most fundamantal |
2651 | Libev can be compiled with a variety of options, the most fundamental |
2631 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2652 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2632 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2653 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2633 | |
2654 | |
2634 | To make it easier to write programs that cope with either variant, the |
2655 | To make it easier to write programs that cope with either variant, the |
2635 | following macros are defined: |
2656 | following macros are defined: |
… | |
… | |
2709 | libev somewhere in your source tree). |
2730 | libev somewhere in your source tree). |
2710 | |
2731 | |
2711 | =head2 FILESETS |
2732 | =head2 FILESETS |
2712 | |
2733 | |
2713 | Depending on what features you need you need to include one or more sets of files |
2734 | Depending on what features you need you need to include one or more sets of files |
2714 | in your app. |
2735 | in your application. |
2715 | |
2736 | |
2716 | =head3 CORE EVENT LOOP |
2737 | =head3 CORE EVENT LOOP |
2717 | |
2738 | |
2718 | To include only the libev core (all the C<ev_*> functions), with manual |
2739 | To include only the libev core (all the C<ev_*> functions), with manual |
2719 | configuration (no autoconf): |
2740 | configuration (no autoconf): |
… | |
… | |
2770 | event.h |
2791 | event.h |
2771 | event.c |
2792 | event.c |
2772 | |
2793 | |
2773 | =head3 AUTOCONF SUPPORT |
2794 | =head3 AUTOCONF SUPPORT |
2774 | |
2795 | |
2775 | Instead of using C<EV_STANDALONE=1> and providing your config in |
2796 | Instead of using C<EV_STANDALONE=1> and providing your configuration in |
2776 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2797 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2777 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2798 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2778 | include F<config.h> and configure itself accordingly. |
2799 | include F<config.h> and configure itself accordingly. |
2779 | |
2800 | |
2780 | For this of course you need the m4 file: |
2801 | For this of course you need the m4 file: |
… | |
… | |
2782 | libev.m4 |
2803 | libev.m4 |
2783 | |
2804 | |
2784 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2805 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2785 | |
2806 | |
2786 | Libev can be configured via a variety of preprocessor symbols you have to |
2807 | Libev can be configured via a variety of preprocessor symbols you have to |
2787 | define before including any of its files. The default in the absense of |
2808 | define before including any of its files. The default in the absence of |
2788 | autoconf is noted for every option. |
2809 | autoconf is noted for every option. |
2789 | |
2810 | |
2790 | =over 4 |
2811 | =over 4 |
2791 | |
2812 | |
2792 | =item EV_STANDALONE |
2813 | =item EV_STANDALONE |
… | |
… | |
2798 | F<event.h> that are not directly supported by the libev core alone. |
2819 | F<event.h> that are not directly supported by the libev core alone. |
2799 | |
2820 | |
2800 | =item EV_USE_MONOTONIC |
2821 | =item EV_USE_MONOTONIC |
2801 | |
2822 | |
2802 | If defined to be C<1>, libev will try to detect the availability of the |
2823 | If defined to be C<1>, libev will try to detect the availability of the |
2803 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2824 | monotonic clock option at both compile time and runtime. Otherwise no use |
2804 | of the monotonic clock option will be attempted. If you enable this, you |
2825 | of the monotonic clock option will be attempted. If you enable this, you |
2805 | usually have to link against librt or something similar. Enabling it when |
2826 | usually have to link against librt or something similar. Enabling it when |
2806 | the functionality isn't available is safe, though, although you have |
2827 | the functionality isn't available is safe, though, although you have |
2807 | to make sure you link against any libraries where the C<clock_gettime> |
2828 | to make sure you link against any libraries where the C<clock_gettime> |
2808 | function is hiding in (often F<-lrt>). |
2829 | function is hiding in (often F<-lrt>). |
2809 | |
2830 | |
2810 | =item EV_USE_REALTIME |
2831 | =item EV_USE_REALTIME |
2811 | |
2832 | |
2812 | If defined to be C<1>, libev will try to detect the availability of the |
2833 | If defined to be C<1>, libev will try to detect the availability of the |
2813 | realtime clock option at compiletime (and assume its availability at |
2834 | real-time clock option at compile time (and assume its availability at |
2814 | runtime if successful). Otherwise no use of the realtime clock option will |
2835 | runtime if successful). Otherwise no use of the real-time clock option will |
2815 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2836 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2816 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2837 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2817 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2838 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2818 | |
2839 | |
2819 | =item EV_USE_NANOSLEEP |
2840 | =item EV_USE_NANOSLEEP |
… | |
… | |
2830 | 2.7 or newer, otherwise disabled. |
2851 | 2.7 or newer, otherwise disabled. |
2831 | |
2852 | |
2832 | =item EV_USE_SELECT |
2853 | =item EV_USE_SELECT |
2833 | |
2854 | |
2834 | If undefined or defined to be C<1>, libev will compile in support for the |
2855 | If undefined or defined to be C<1>, libev will compile in support for the |
2835 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2856 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
2836 | other method takes over, select will be it. Otherwise the select backend |
2857 | other method takes over, select will be it. Otherwise the select backend |
2837 | will not be compiled in. |
2858 | will not be compiled in. |
2838 | |
2859 | |
2839 | =item EV_SELECT_USE_FD_SET |
2860 | =item EV_SELECT_USE_FD_SET |
2840 | |
2861 | |
2841 | If defined to C<1>, then the select backend will use the system C<fd_set> |
2862 | If defined to C<1>, then the select backend will use the system C<fd_set> |
2842 | structure. This is useful if libev doesn't compile due to a missing |
2863 | structure. This is useful if libev doesn't compile due to a missing |
2843 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
2864 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
2844 | exotic systems. This usually limits the range of file descriptors to some |
2865 | exotic systems. This usually limits the range of file descriptors to some |
2845 | low limit such as 1024 or might have other limitations (winsocket only |
2866 | low limit such as 1024 or might have other limitations (winsocket only |
2846 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
2867 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
2847 | influence the size of the C<fd_set> used. |
2868 | influence the size of the C<fd_set> used. |
2848 | |
2869 | |
… | |
… | |
2897 | otherwise another method will be used as fallback. This is the preferred |
2918 | otherwise another method will be used as fallback. This is the preferred |
2898 | backend for Solaris 10 systems. |
2919 | backend for Solaris 10 systems. |
2899 | |
2920 | |
2900 | =item EV_USE_DEVPOLL |
2921 | =item EV_USE_DEVPOLL |
2901 | |
2922 | |
2902 | reserved for future expansion, works like the USE symbols above. |
2923 | Reserved for future expansion, works like the USE symbols above. |
2903 | |
2924 | |
2904 | =item EV_USE_INOTIFY |
2925 | =item EV_USE_INOTIFY |
2905 | |
2926 | |
2906 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2927 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2907 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2928 | interface to speed up C<ev_stat> watchers. Its actual availability will |
… | |
… | |
2914 | access is atomic with respect to other threads or signal contexts. No such |
2935 | access is atomic with respect to other threads or signal contexts. No such |
2915 | type is easily found in the C language, so you can provide your own type |
2936 | type is easily found in the C language, so you can provide your own type |
2916 | that you know is safe for your purposes. It is used both for signal handler "locking" |
2937 | that you know is safe for your purposes. It is used both for signal handler "locking" |
2917 | as well as for signal and thread safety in C<ev_async> watchers. |
2938 | as well as for signal and thread safety in C<ev_async> watchers. |
2918 | |
2939 | |
2919 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
2940 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
2920 | (from F<signal.h>), which is usually good enough on most platforms. |
2941 | (from F<signal.h>), which is usually good enough on most platforms. |
2921 | |
2942 | |
2922 | =item EV_H |
2943 | =item EV_H |
2923 | |
2944 | |
2924 | The name of the F<ev.h> header file used to include it. The default if |
2945 | The name of the F<ev.h> header file used to include it. The default if |
… | |
… | |
2963 | When doing priority-based operations, libev usually has to linearly search |
2984 | When doing priority-based operations, libev usually has to linearly search |
2964 | all the priorities, so having many of them (hundreds) uses a lot of space |
2985 | all the priorities, so having many of them (hundreds) uses a lot of space |
2965 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
2986 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
2966 | fine. |
2987 | fine. |
2967 | |
2988 | |
2968 | If your embedding app does not need any priorities, defining these both to |
2989 | If your embedding application does not need any priorities, defining these both to |
2969 | C<0> will save some memory and cpu. |
2990 | C<0> will save some memory and CPU. |
2970 | |
2991 | |
2971 | =item EV_PERIODIC_ENABLE |
2992 | =item EV_PERIODIC_ENABLE |
2972 | |
2993 | |
2973 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2994 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2974 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2995 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
… | |
… | |
3002 | |
3023 | |
3003 | =item EV_MINIMAL |
3024 | =item EV_MINIMAL |
3004 | |
3025 | |
3005 | If you need to shave off some kilobytes of code at the expense of some |
3026 | If you need to shave off some kilobytes of code at the expense of some |
3006 | speed, define this symbol to C<1>. Currently this is used to override some |
3027 | speed, define this symbol to C<1>. Currently this is used to override some |
3007 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
3028 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3008 | much smaller 2-heap for timer management over the default 4-heap. |
3029 | much smaller 2-heap for timer management over the default 4-heap. |
3009 | |
3030 | |
3010 | =item EV_PID_HASHSIZE |
3031 | =item EV_PID_HASHSIZE |
3011 | |
3032 | |
3012 | C<ev_child> watchers use a small hash table to distribute workload by |
3033 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
3025 | =item EV_USE_4HEAP |
3046 | =item EV_USE_4HEAP |
3026 | |
3047 | |
3027 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3048 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3028 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
3049 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
3029 | to C<1>. The 4-heap uses more complicated (longer) code but has |
3050 | to C<1>. The 4-heap uses more complicated (longer) code but has |
3030 | noticably faster performance with many (thousands) of watchers. |
3051 | noticeably faster performance with many (thousands) of watchers. |
3031 | |
3052 | |
3032 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3053 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3033 | (disabled). |
3054 | (disabled). |
3034 | |
3055 | |
3035 | =item EV_HEAP_CACHE_AT |
3056 | =item EV_HEAP_CACHE_AT |
… | |
… | |
3037 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3058 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3038 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
3059 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
3039 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3060 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3040 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3061 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3041 | but avoids random read accesses on heap changes. This improves performance |
3062 | but avoids random read accesses on heap changes. This improves performance |
3042 | noticably with with many (hundreds) of watchers. |
3063 | noticeably with with many (hundreds) of watchers. |
3043 | |
3064 | |
3044 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3065 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3045 | (disabled). |
3066 | (disabled). |
3046 | |
3067 | |
3047 | =item EV_VERIFY |
3068 | =item EV_VERIFY |
… | |
… | |
3083 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3104 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3084 | method calls instead of plain function calls in C++. |
3105 | method calls instead of plain function calls in C++. |
3085 | |
3106 | |
3086 | =head2 EXPORTED API SYMBOLS |
3107 | =head2 EXPORTED API SYMBOLS |
3087 | |
3108 | |
3088 | If you need to re-export the API (e.g. via a dll) and you need a list of |
3109 | If you need to re-export the API (e.g. via a DLL) and you need a list of |
3089 | exported symbols, you can use the provided F<Symbol.*> files which list |
3110 | exported symbols, you can use the provided F<Symbol.*> files which list |
3090 | all public symbols, one per line: |
3111 | all public symbols, one per line: |
3091 | |
3112 | |
3092 | Symbols.ev for libev proper |
3113 | Symbols.ev for libev proper |
3093 | Symbols.event for the libevent emulation |
3114 | Symbols.event for the libevent emulation |
3094 | |
3115 | |
3095 | This can also be used to rename all public symbols to avoid clashes with |
3116 | This can also be used to rename all public symbols to avoid clashes with |
3096 | multiple versions of libev linked together (which is obviously bad in |
3117 | multiple versions of libev linked together (which is obviously bad in |
3097 | itself, but sometimes it is inconvinient to avoid this). |
3118 | itself, but sometimes it is inconvenient to avoid this). |
3098 | |
3119 | |
3099 | A sed command like this will create wrapper C<#define>'s that you need to |
3120 | A sed command like this will create wrapper C<#define>'s that you need to |
3100 | include before including F<ev.h>: |
3121 | include before including F<ev.h>: |
3101 | |
3122 | |
3102 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
3123 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
… | |
… | |
3141 | |
3162 | |
3142 | =head1 THREADS AND COROUTINES |
3163 | =head1 THREADS AND COROUTINES |
3143 | |
3164 | |
3144 | =head2 THREADS |
3165 | =head2 THREADS |
3145 | |
3166 | |
3146 | Libev itself is completely threadsafe, but it uses no locking. This |
3167 | Libev itself is completely thread-safe, but it uses no locking. This |
3147 | means that you can use as many loops as you want in parallel, as long as |
3168 | means that you can use as many loops as you want in parallel, as long as |
3148 | only one thread ever calls into one libev function with the same loop |
3169 | only one thread ever calls into one libev function with the same loop |
3149 | parameter. |
3170 | parameter. |
3150 | |
3171 | |
3151 | Or put differently: calls with different loop parameters can be done in |
3172 | Or put differently: calls with different loop parameters can be done in |
… | |
… | |
3158 | help you but by giving some generic advice: |
3179 | help you but by giving some generic advice: |
3159 | |
3180 | |
3160 | =over 4 |
3181 | =over 4 |
3161 | |
3182 | |
3162 | =item * most applications have a main thread: use the default libev loop |
3183 | =item * most applications have a main thread: use the default libev loop |
3163 | in that thread, or create a seperate thread running only the default loop. |
3184 | in that thread, or create a separate thread running only the default loop. |
3164 | |
3185 | |
3165 | This helps integrating other libraries or software modules that use libev |
3186 | This helps integrating other libraries or software modules that use libev |
3166 | themselves and don't care/know about threading. |
3187 | themselves and don't care/know about threading. |
3167 | |
3188 | |
3168 | =item * one loop per thread is usually a good model. |
3189 | =item * one loop per thread is usually a good model. |
3169 | |
3190 | |
3170 | Doing this is almost never wrong, sometimes a better-performance model |
3191 | Doing this is almost never wrong, sometimes a better-performance model |
3171 | exists, but it is always a good start. |
3192 | exists, but it is always a good start. |
3172 | |
3193 | |
3173 | =item * other models exist, such as the leader/follower pattern, where one |
3194 | =item * other models exist, such as the leader/follower pattern, where one |
3174 | loop is handed through multiple threads in a kind of round-robbin fashion. |
3195 | loop is handed through multiple threads in a kind of round-robin fashion. |
3175 | |
3196 | |
3176 | Chosing a model is hard - look around, learn, know that usually you cna do |
3197 | Choosing a model is hard - look around, learn, know that usually you can do |
3177 | better than you currently do :-) |
3198 | better than you currently do :-) |
3178 | |
3199 | |
3179 | =item * often you need to talk to some other thread which blocks in the |
3200 | =item * often you need to talk to some other thread which blocks in the |
3180 | event loop - C<ev_async> watchers can be used to wake them up from other |
3201 | event loop - C<ev_async> watchers can be used to wake them up from other |
3181 | threads safely (or from signal contexts...). |
3202 | threads safely (or from signal contexts...). |
3182 | |
3203 | |
3183 | =back |
3204 | =back |
3184 | |
3205 | |
3185 | =head2 COROUTINES |
3206 | =head2 COROUTINES |
3186 | |
3207 | |
3187 | Libev is much more accomodating to coroutines ("cooperative threads"): |
3208 | Libev is much more accommodating to coroutines ("cooperative threads"): |
3188 | libev fully supports nesting calls to it's functions from different |
3209 | libev fully supports nesting calls to it's functions from different |
3189 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3210 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3190 | different coroutines and switch freely between both coroutines running the |
3211 | different coroutines and switch freely between both coroutines running the |
3191 | loop, as long as you don't confuse yourself). The only exception is that |
3212 | loop, as long as you don't confuse yourself). The only exception is that |
3192 | you must not do this from C<ev_periodic> reschedule callbacks. |
3213 | you must not do this from C<ev_periodic> reschedule callbacks. |
… | |
… | |
3240 | |
3261 | |
3241 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3262 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3242 | |
3263 | |
3243 | A change means an I/O watcher gets started or stopped, which requires |
3264 | A change means an I/O watcher gets started or stopped, which requires |
3244 | libev to recalculate its status (and possibly tell the kernel, depending |
3265 | libev to recalculate its status (and possibly tell the kernel, depending |
3245 | on backend and wether C<ev_io_set> was used). |
3266 | on backend and whether C<ev_io_set> was used). |
3246 | |
3267 | |
3247 | =item Activating one watcher (putting it into the pending state): O(1) |
3268 | =item Activating one watcher (putting it into the pending state): O(1) |
3248 | |
3269 | |
3249 | =item Priority handling: O(number_of_priorities) |
3270 | =item Priority handling: O(number_of_priorities) |
3250 | |
3271 | |
… | |
… | |
3257 | |
3278 | |
3258 | =item Processing ev_async_send: O(number_of_async_watchers) |
3279 | =item Processing ev_async_send: O(number_of_async_watchers) |
3259 | |
3280 | |
3260 | =item Processing signals: O(max_signal_number) |
3281 | =item Processing signals: O(max_signal_number) |
3261 | |
3282 | |
3262 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
3283 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
3263 | calls in the current loop iteration. Checking for async and signal events |
3284 | calls in the current loop iteration. Checking for async and signal events |
3264 | involves iterating over all running async watchers or all signal numbers. |
3285 | involves iterating over all running async watchers or all signal numbers. |
3265 | |
3286 | |
3266 | =back |
3287 | =back |
3267 | |
3288 | |
… | |
… | |
3281 | way (note also that glib is the slowest event library known to man). |
3302 | way (note also that glib is the slowest event library known to man). |
3282 | |
3303 | |
3283 | There is no supported compilation method available on windows except |
3304 | There is no supported compilation method available on windows except |
3284 | embedding it into other applications. |
3305 | embedding it into other applications. |
3285 | |
3306 | |
|
|
3307 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
3308 | accept large writes: instead of resulting in a partial write, windows will |
|
|
3309 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
|
|
3310 | so make sure you only write small amounts into your sockets (less than a |
|
|
3311 | megabyte seems safe, but thsi apparently depends on the amount of memory |
|
|
3312 | available). |
|
|
3313 | |
3286 | Due to the many, low, and arbitrary limits on the win32 platform and |
3314 | Due to the many, low, and arbitrary limits on the win32 platform and |
3287 | the abysmal performance of winsockets, using a large number of sockets |
3315 | the abysmal performance of winsockets, using a large number of sockets |
3288 | is not recommended (and not reasonable). If your program needs to use |
3316 | is not recommended (and not reasonable). If your program needs to use |
3289 | more than a hundred or so sockets, then likely it needs to use a totally |
3317 | more than a hundred or so sockets, then likely it needs to use a totally |
3290 | different implementation for windows, as libev offers the POSIX readiness |
3318 | different implementation for windows, as libev offers the POSIX readiness |
3291 | notification model, which cannot be implemented efficiently on windows |
3319 | notification model, which cannot be implemented efficiently on windows |
3292 | (microsoft monopoly games). |
3320 | (Microsoft monopoly games). |
3293 | |
3321 | |
3294 | =over 4 |
3322 | =over 4 |
3295 | |
3323 | |
3296 | =item The winsocket select function |
3324 | =item The winsocket select function |
3297 | |
3325 | |
3298 | The winsocket C<select> function doesn't follow POSIX in that it requires |
3326 | The winsocket C<select> function doesn't follow POSIX in that it |
3299 | socket I<handles> and not socket I<file descriptors>. This makes select |
3327 | requires socket I<handles> and not socket I<file descriptors> (it is |
3300 | very inefficient, and also requires a mapping from file descriptors |
3328 | also extremely buggy). This makes select very inefficient, and also |
3301 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
3329 | requires a mapping from file descriptors to socket handles. See the |
3302 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
3330 | discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and |
3303 | symbols for more info. |
3331 | C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info. |
3304 | |
3332 | |
3305 | The configuration for a "naked" win32 using the microsoft runtime |
3333 | The configuration for a "naked" win32 using the Microsoft runtime |
3306 | libraries and raw winsocket select is: |
3334 | libraries and raw winsocket select is: |
3307 | |
3335 | |
3308 | #define EV_USE_SELECT 1 |
3336 | #define EV_USE_SELECT 1 |
3309 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3337 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3310 | |
3338 | |
… | |
… | |
3315 | |
3343 | |
3316 | Windows has numerous arbitrary (and low) limits on things. |
3344 | Windows has numerous arbitrary (and low) limits on things. |
3317 | |
3345 | |
3318 | Early versions of winsocket's select only supported waiting for a maximum |
3346 | Early versions of winsocket's select only supported waiting for a maximum |
3319 | of C<64> handles (probably owning to the fact that all windows kernels |
3347 | of C<64> handles (probably owning to the fact that all windows kernels |
3320 | can only wait for C<64> things at the same time internally; microsoft |
3348 | can only wait for C<64> things at the same time internally; Microsoft |
3321 | recommends spawning a chain of threads and wait for 63 handles and the |
3349 | recommends spawning a chain of threads and wait for 63 handles and the |
3322 | previous thread in each. Great). |
3350 | previous thread in each. Great). |
3323 | |
3351 | |
3324 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3352 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3325 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3353 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3326 | call (which might be in libev or elsewhere, for example, perl does its own |
3354 | call (which might be in libev or elsewhere, for example, perl does its own |
3327 | select emulation on windows). |
3355 | select emulation on windows). |
3328 | |
3356 | |
3329 | Another limit is the number of file descriptors in the microsoft runtime |
3357 | Another limit is the number of file descriptors in the Microsoft runtime |
3330 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
3358 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
3331 | or something like this inside microsoft). You can increase this by calling |
3359 | or something like this inside Microsoft). You can increase this by calling |
3332 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
3360 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
3333 | arbitrary limit), but is broken in many versions of the microsoft runtime |
3361 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
3334 | libraries. |
3362 | libraries. |
3335 | |
3363 | |
3336 | This might get you to about C<512> or C<2048> sockets (depending on |
3364 | This might get you to about C<512> or C<2048> sockets (depending on |
3337 | windows version and/or the phase of the moon). To get more, you need to |
3365 | windows version and/or the phase of the moon). To get more, you need to |
3338 | wrap all I/O functions and provide your own fd management, but the cost of |
3366 | wrap all I/O functions and provide your own fd management, but the cost of |
… | |
… | |
3386 | =back |
3414 | =back |
3387 | |
3415 | |
3388 | If you know of other additional requirements drop me a note. |
3416 | If you know of other additional requirements drop me a note. |
3389 | |
3417 | |
3390 | |
3418 | |
|
|
3419 | =head1 COMPILER WARNINGS |
|
|
3420 | |
|
|
3421 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3422 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3423 | scared by this. |
|
|
3424 | |
|
|
3425 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
3426 | has different warnings, and each user has different tastes regarding |
|
|
3427 | warning options. "Warn-free" code therefore cannot be a goal except when |
|
|
3428 | targeting a specific compiler and compiler-version. |
|
|
3429 | |
|
|
3430 | Another reason is that some compiler warnings require elaborate |
|
|
3431 | workarounds, or other changes to the code that make it less clear and less |
|
|
3432 | maintainable. |
|
|
3433 | |
|
|
3434 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3435 | wrong (because they don't actually warn about the condition their message |
|
|
3436 | seems to warn about). |
|
|
3437 | |
|
|
3438 | While libev is written to generate as few warnings as possible, |
|
|
3439 | "warn-free" code is not a goal, and it is recommended not to build libev |
|
|
3440 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3441 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3442 | warnings, not errors, or proof of bugs. |
|
|
3443 | |
|
|
3444 | |
3391 | =head1 VALGRIND |
3445 | =head1 VALGRIND |
3392 | |
3446 | |
3393 | Valgrind has a special section here because it is a popular tool that is |
3447 | Valgrind has a special section here because it is a popular tool that is |
3394 | highly useful, but valgrind reports are very hard to interpret. |
3448 | highly useful, but valgrind reports are very hard to interpret. |
3395 | |
3449 | |
… | |
… | |
3398 | |
3452 | |
3399 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3453 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3400 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3454 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3401 | ==2274== still reachable: 256 bytes in 1 blocks. |
3455 | ==2274== still reachable: 256 bytes in 1 blocks. |
3402 | |
3456 | |
3403 | then there is no memory leak. Similarly, under some circumstances, |
3457 | Then there is no memory leak. Similarly, under some circumstances, |
3404 | valgrind might report kernel bugs as if it were a bug in libev, or it |
3458 | valgrind might report kernel bugs as if it were a bug in libev, or it |
3405 | might be confused (it is a very good tool, but only a tool). |
3459 | might be confused (it is a very good tool, but only a tool). |
3406 | |
3460 | |
3407 | If you are unsure about something, feel free to contact the mailing list |
3461 | If you are unsure about something, feel free to contact the mailing list |
3408 | with the full valgrind report and an explanation on why you think this is |
3462 | with the full valgrind report and an explanation on why you think this is |