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Revision 1.309 by root, Thu Oct 21 09:23:21 2010 UTC vs.
Revision 1.327 by root, Sun Oct 24 20:05:43 2010 UTC

26 puts ("stdin ready"); 26 puts ("stdin ready");
27 // for one-shot events, one must manually stop the watcher 27 // for one-shot events, one must manually stop the watcher
28 // with its corresponding stop function. 28 // with its corresponding stop function.
29 ev_io_stop (EV_A_ w); 29 ev_io_stop (EV_A_ w);
30 30
31 // this causes all nested ev_loop's to stop iterating 31 // this causes all nested ev_run's to stop iterating
32 ev_unloop (EV_A_ EVUNLOOP_ALL); 32 ev_break (EV_A_ EVBREAK_ALL);
33 } 33 }
34 34
35 // another callback, this time for a time-out 35 // another callback, this time for a time-out
36 static void 36 static void
37 timeout_cb (EV_P_ ev_timer *w, int revents) 37 timeout_cb (EV_P_ ev_timer *w, int revents)
38 { 38 {
39 puts ("timeout"); 39 puts ("timeout");
40 // this causes the innermost ev_loop to stop iterating 40 // this causes the innermost ev_run to stop iterating
41 ev_unloop (EV_A_ EVUNLOOP_ONE); 41 ev_break (EV_A_ EVBREAK_ONE);
42 } 42 }
43 43
44 int 44 int
45 main (void) 45 main (void)
46 { 46 {
47 // use the default event loop unless you have special needs 47 // use the default event loop unless you have special needs
48 struct ev_loop *loop = ev_default_loop (0); 48 struct ev_loop *loop = EV_DEFAULT;
49 49
50 // initialise an io watcher, then start it 50 // initialise an io watcher, then start it
51 // this one will watch for stdin to become readable 51 // this one will watch for stdin to become readable
52 ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); 52 ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53 ev_io_start (loop, &stdin_watcher); 53 ev_io_start (loop, &stdin_watcher);
56 // simple non-repeating 5.5 second timeout 56 // simple non-repeating 5.5 second timeout
57 ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); 57 ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58 ev_timer_start (loop, &timeout_watcher); 58 ev_timer_start (loop, &timeout_watcher);
59 59
60 // now wait for events to arrive 60 // now wait for events to arrive
61 ev_loop (loop, 0); 61 ev_run (loop, 0);
62 62
63 // unloop was called, so exit 63 // unloop was called, so exit
64 return 0; 64 return 0;
65 } 65 }
66 66
124this argument. 124this argument.
125 125
126=head2 TIME REPRESENTATION 126=head2 TIME REPRESENTATION
127 127
128Libev represents time as a single floating point number, representing 128Libev represents time as a single floating point number, representing
129the (fractional) number of seconds since the (POSIX) epoch (in practise 129the (fractional) number of seconds since the (POSIX) epoch (in practice
130somewhere near the beginning of 1970, details are complicated, don't 130somewhere near the beginning of 1970, details are complicated, don't
131ask). This type is called C<ev_tstamp>, which is what you should use 131ask). This type is called C<ev_tstamp>, which is what you should use
132too. It usually aliases to the C<double> type in C. When you need to do 132too. It usually aliases to the C<double> type in C. When you need to do
133any calculations on it, you should treat it as some floating point value. 133any calculations on it, you should treat it as some floating point value.
134 134
165 165
166=item ev_tstamp ev_time () 166=item ev_tstamp ev_time ()
167 167
168Returns the current time as libev would use it. Please note that the 168Returns the current time as libev would use it. Please note that the
169C<ev_now> function is usually faster and also often returns the timestamp 169C<ev_now> function is usually faster and also often returns the timestamp
170you actually want to know. 170you actually want to know. Also interesting is the combination of
171C<ev_update_now> and C<ev_now>.
171 172
172=item ev_sleep (ev_tstamp interval) 173=item ev_sleep (ev_tstamp interval)
173 174
174Sleep for the given interval: The current thread will be blocked until 175Sleep for the given interval: The current thread will be blocked until
175either it is interrupted or the given time interval has passed. Basically 176either it is interrupted or the given time interval has passed. Basically
192as this indicates an incompatible change. Minor versions are usually 193as this indicates an incompatible change. Minor versions are usually
193compatible to older versions, so a larger minor version alone is usually 194compatible to older versions, so a larger minor version alone is usually
194not a problem. 195not a problem.
195 196
196Example: Make sure we haven't accidentally been linked against the wrong 197Example: Make sure we haven't accidentally been linked against the wrong
197version (note, however, that this will not detect ABI mismatches :). 198version (note, however, that this will not detect other ABI mismatches,
199such as LFS or reentrancy).
198 200
199 assert (("libev version mismatch", 201 assert (("libev version mismatch",
200 ev_version_major () == EV_VERSION_MAJOR 202 ev_version_major () == EV_VERSION_MAJOR
201 && ev_version_minor () >= EV_VERSION_MINOR)); 203 && ev_version_minor () >= EV_VERSION_MINOR));
202 204
213 assert (("sorry, no epoll, no sex", 215 assert (("sorry, no epoll, no sex",
214 ev_supported_backends () & EVBACKEND_EPOLL)); 216 ev_supported_backends () & EVBACKEND_EPOLL));
215 217
216=item unsigned int ev_recommended_backends () 218=item unsigned int ev_recommended_backends ()
217 219
218Return the set of all backends compiled into this binary of libev and also 220Return the set of all backends compiled into this binary of libev and
219recommended for this platform. This set is often smaller than the one 221also recommended for this platform, meaning it will work for most file
222descriptor types. This set is often smaller than the one returned by
220returned by C<ev_supported_backends>, as for example kqueue is broken on 223C<ev_supported_backends>, as for example kqueue is broken on most BSDs
221most BSDs and will not be auto-detected unless you explicitly request it 224and will not be auto-detected unless you explicitly request it (assuming
222(assuming you know what you are doing). This is the set of backends that 225you know what you are doing). This is the set of backends that libev will
223libev will probe for if you specify no backends explicitly. 226probe for if you specify no backends explicitly.
224 227
225=item unsigned int ev_embeddable_backends () 228=item unsigned int ev_embeddable_backends ()
226 229
227Returns the set of backends that are embeddable in other event loops. This 230Returns the set of backends that are embeddable in other event loops. This
228is the theoretical, all-platform, value. To find which backends 231value is platform-specific but can include backends not available on the
229might be supported on the current system, you would need to look at 232current system. To find which embeddable backends might be supported on
230C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for 233the current system, you would need to look at C<ev_embeddable_backends ()
231recommended ones. 234& ev_supported_backends ()>, likewise for recommended ones.
232 235
233See the description of C<ev_embed> watchers for more info. 236See the description of C<ev_embed> watchers for more info.
234 237
235=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] 238=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
236 239
290 ... 293 ...
291 ev_set_syserr_cb (fatal_error); 294 ev_set_syserr_cb (fatal_error);
292 295
293=back 296=back
294 297
295=head1 FUNCTIONS CONTROLLING THE EVENT LOOP 298=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296 299
297An event loop is described by a C<struct ev_loop *> (the C<struct> 300An event loop is described by a C<struct ev_loop *> (the C<struct> is
298is I<not> optional in this case, as there is also an C<ev_loop> 301I<not> optional in this case unless libev 3 compatibility is disabled, as
299I<function>). 302libev 3 had an C<ev_loop> function colliding with the struct name).
300 303
301The library knows two types of such loops, the I<default> loop, which 304The library knows two types of such loops, the I<default> loop, which
302supports signals and child events, and dynamically created loops which do 305supports signals and child events, and dynamically created event loops
303not. 306which do not.
304 307
305=over 4 308=over 4
306 309
307=item struct ev_loop *ev_default_loop (unsigned int flags) 310=item struct ev_loop *ev_default_loop (unsigned int flags)
308 311
309This will initialise the default event loop if it hasn't been initialised 312This returns the "default" event loop object, which is what you should
310yet and return it. If the default loop could not be initialised, returns 313normally use when you just need "the event loop". Event loop objects and
311false. If it already was initialised it simply returns it (and ignores the 314the C<flags> parameter are described in more detail in the entry for
312flags. If that is troubling you, check C<ev_backend ()> afterwards). 315C<ev_loop_new>.
316
317If the default loop is already initialised then this function simply
318returns it (and ignores the flags. If that is troubling you, check
319C<ev_backend ()> afterwards). Otherwise it will create it with the given
320flags, which should almost always be C<0>, unless the caller is also the
321one calling C<ev_run> or otherwise qualifies as "the main program".
313 322
314If you don't know what event loop to use, use the one returned from this 323If you don't know what event loop to use, use the one returned from this
315function. 324function (or via the C<EV_DEFAULT> macro).
316 325
317Note that this function is I<not> thread-safe, so if you want to use it 326Note that this function is I<not> thread-safe, so if you want to use it
318from multiple threads, you have to lock (note also that this is unlikely, 327from multiple threads, you have to employ some kind of mutex (note also
319as loops cannot be shared easily between threads anyway). 328that this case is unlikely, as loops cannot be shared easily between
329threads anyway).
320 330
321The default loop is the only loop that can handle C<ev_signal> and 331The default loop is the only loop that can handle C<ev_child> watchers,
322C<ev_child> watchers, and to do this, it always registers a handler 332and to do this, it always registers a handler for C<SIGCHLD>. If this is
323for C<SIGCHLD>. If this is a problem for your application you can either 333a problem for your application you can either create a dynamic loop with
324create a dynamic loop with C<ev_loop_new> that doesn't do that, or you 334C<ev_loop_new> which doesn't do that, or you can simply overwrite the
325can simply overwrite the C<SIGCHLD> signal handler I<after> calling 335C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326C<ev_default_init>. 336
337Example: This is the most typical usage.
338
339 if (!ev_default_loop (0))
340 fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
341
342Example: Restrict libev to the select and poll backends, and do not allow
343environment settings to be taken into account:
344
345 ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
346
347=item struct ev_loop *ev_loop_new (unsigned int flags)
348
349This will create and initialise a new event loop object. If the loop
350could not be initialised, returns false.
351
352Note that this function I<is> thread-safe, and one common way to use
353libev with threads is indeed to create one loop per thread, and using the
354default loop in the "main" or "initial" thread.
327 355
328The flags argument can be used to specify special behaviour or specific 356The flags argument can be used to specify special behaviour or specific
329backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). 357backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
330 358
331The following flags are supported: 359The following flags are supported:
549If one or more of the backend flags are or'ed into the flags value, 577If one or more of the backend flags are or'ed into the flags value,
550then only these backends will be tried (in the reverse order as listed 578then only these backends will be tried (in the reverse order as listed
551here). If none are specified, all backends in C<ev_recommended_backends 579here). If none are specified, all backends in C<ev_recommended_backends
552()> will be tried. 580()> will be tried.
553 581
554Example: This is the most typical usage.
555
556 if (!ev_default_loop (0))
557 fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
558
559Example: Restrict libev to the select and poll backends, and do not allow
560environment settings to be taken into account:
561
562 ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
563
564Example: Use whatever libev has to offer, but make sure that kqueue is
565used if available (warning, breaks stuff, best use only with your own
566private event loop and only if you know the OS supports your types of
567fds):
568
569 ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
570
571=item struct ev_loop *ev_loop_new (unsigned int flags)
572
573Similar to C<ev_default_loop>, but always creates a new event loop that is
574always distinct from the default loop.
575
576Note that this function I<is> thread-safe, and one common way to use
577libev with threads is indeed to create one loop per thread, and using the
578default loop in the "main" or "initial" thread.
579
580Example: Try to create a event loop that uses epoll and nothing else. 582Example: Try to create a event loop that uses epoll and nothing else.
581 583
582 struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 584 struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583 if (!epoller) 585 if (!epoller)
584 fatal ("no epoll found here, maybe it hides under your chair"); 586 fatal ("no epoll found here, maybe it hides under your chair");
585 587
588Example: Use whatever libev has to offer, but make sure that kqueue is
589used if available.
590
591 struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
592
586=item ev_default_destroy () 593=item ev_loop_destroy (loop)
587 594
588Destroys the default loop (frees all memory and kernel state etc.). None 595Destroys an event loop object (frees all memory and kernel state
589of the active event watchers will be stopped in the normal sense, so 596etc.). None of the active event watchers will be stopped in the normal
590e.g. C<ev_is_active> might still return true. It is your responsibility to 597sense, so e.g. C<ev_is_active> might still return true. It is your
591either stop all watchers cleanly yourself I<before> calling this function, 598responsibility to either stop all watchers cleanly yourself I<before>
592or cope with the fact afterwards (which is usually the easiest thing, you 599calling this function, or cope with the fact afterwards (which is usually
593can just ignore the watchers and/or C<free ()> them for example). 600the easiest thing, you can just ignore the watchers and/or C<free ()> them
601for example).
594 602
595Note that certain global state, such as signal state (and installed signal 603Note that certain global state, such as signal state (and installed signal
596handlers), will not be freed by this function, and related watchers (such 604handlers), will not be freed by this function, and related watchers (such
597as signal and child watchers) would need to be stopped manually. 605as signal and child watchers) would need to be stopped manually.
598 606
599In general it is not advisable to call this function except in the 607This function is normally used on loop objects allocated by
600rare occasion where you really need to free e.g. the signal handling 608C<ev_loop_new>, but it can also be used on the default loop returned by
609C<ev_default_loop>, in which case it is not thread-safe.
610
611Note that it is not advisable to call this function on the default loop
612except in the rare occasion where you really need to free it's resources.
601pipe fds. If you need dynamically allocated loops it is better to use 613If you need dynamically allocated loops it is better to use C<ev_loop_new>
602C<ev_loop_new> and C<ev_loop_destroy>. 614and C<ev_loop_destroy>.
603 615
604=item ev_loop_destroy (loop) 616=item ev_loop_fork (loop)
605 617
606Like C<ev_default_destroy>, but destroys an event loop created by an
607earlier call to C<ev_loop_new>.
608
609=item ev_default_fork ()
610
611This function sets a flag that causes subsequent C<ev_loop> iterations 618This function sets a flag that causes subsequent C<ev_run> iterations to
612to reinitialise the kernel state for backends that have one. Despite the 619reinitialise the kernel state for backends that have one. Despite the
613name, you can call it anytime, but it makes most sense after forking, in 620name, you can call it anytime, but it makes most sense after forking, in
614the child process (or both child and parent, but that again makes little 621the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
615sense). You I<must> call it in the child before using any of the libev 622child before resuming or calling C<ev_run>.
616functions, and it will only take effect at the next C<ev_loop> iteration.
617 623
618Again, you I<have> to call it on I<any> loop that you want to re-use after 624Again, you I<have> to call it on I<any> loop that you want to re-use after
619a fork, I<even if you do not plan to use the loop in the parent>. This is 625a fork, I<even if you do not plan to use the loop in the parent>. This is
620because some kernel interfaces *cough* I<kqueue> *cough* do funny things 626because some kernel interfaces *cough* I<kqueue> *cough* do funny things
621during fork. 627during fork.
622 628
623On the other hand, you only need to call this function in the child 629On the other hand, you only need to call this function in the child
624process if and only if you want to use the event loop in the child. If you 630process if and only if you want to use the event loop in the child. If
625just fork+exec or create a new loop in the child, you don't have to call 631you just fork+exec or create a new loop in the child, you don't have to
626it at all. 632call it at all (in fact, C<epoll> is so badly broken that it makes a
633difference, but libev will usually detect this case on its own and do a
634costly reset of the backend).
627 635
628The function itself is quite fast and it's usually not a problem to call 636The function itself is quite fast and it's usually not a problem to call
629it just in case after a fork. To make this easy, the function will fit in 637it just in case after a fork.
630quite nicely into a call to C<pthread_atfork>:
631 638
639Example: Automate calling C<ev_loop_fork> on the default loop when
640using pthreads.
641
642 static void
643 post_fork_child (void)
644 {
645 ev_loop_fork (EV_DEFAULT);
646 }
647
648 ...
632 pthread_atfork (0, 0, ev_default_fork); 649 pthread_atfork (0, 0, post_fork_child);
633
634=item ev_loop_fork (loop)
635
636Like C<ev_default_fork>, but acts on an event loop created by
637C<ev_loop_new>. Yes, you have to call this on every allocated event loop
638after fork that you want to re-use in the child, and how you keep track of
639them is entirely your own problem.
640 650
641=item int ev_is_default_loop (loop) 651=item int ev_is_default_loop (loop)
642 652
643Returns true when the given loop is, in fact, the default loop, and false 653Returns true when the given loop is, in fact, the default loop, and false
644otherwise. 654otherwise.
645 655
646=item unsigned int ev_iteration (loop) 656=item unsigned int ev_iteration (loop)
647 657
648Returns the current iteration count for the loop, which is identical to 658Returns the current iteration count for the event loop, which is identical
649the number of times libev did poll for new events. It starts at C<0> and 659to the number of times libev did poll for new events. It starts at C<0>
650happily wraps around with enough iterations. 660and happily wraps around with enough iterations.
651 661
652This value can sometimes be useful as a generation counter of sorts (it 662This value can sometimes be useful as a generation counter of sorts (it
653"ticks" the number of loop iterations), as it roughly corresponds with 663"ticks" the number of loop iterations), as it roughly corresponds with
654C<ev_prepare> and C<ev_check> calls - and is incremented between the 664C<ev_prepare> and C<ev_check> calls - and is incremented between the
655prepare and check phases. 665prepare and check phases.
656 666
657=item unsigned int ev_depth (loop) 667=item unsigned int ev_depth (loop)
658 668
659Returns the number of times C<ev_loop> was entered minus the number of 669Returns the number of times C<ev_run> was entered minus the number of
660times C<ev_loop> was exited, in other words, the recursion depth. 670times C<ev_run> was exited, in other words, the recursion depth.
661 671
662Outside C<ev_loop>, this number is zero. In a callback, this number is 672Outside C<ev_run>, this number is zero. In a callback, this number is
663C<1>, unless C<ev_loop> was invoked recursively (or from another thread), 673C<1>, unless C<ev_run> was invoked recursively (or from another thread),
664in which case it is higher. 674in which case it is higher.
665 675
666Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread 676Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
667etc.), doesn't count as "exit" - consider this as a hint to avoid such 677etc.), doesn't count as "exit" - consider this as a hint to avoid such
668ungentleman behaviour unless it's really convenient. 678ungentleman-like behaviour unless it's really convenient.
669 679
670=item unsigned int ev_backend (loop) 680=item unsigned int ev_backend (loop)
671 681
672Returns one of the C<EVBACKEND_*> flags indicating the event backend in 682Returns one of the C<EVBACKEND_*> flags indicating the event backend in
673use. 683use.
682 692
683=item ev_now_update (loop) 693=item ev_now_update (loop)
684 694
685Establishes the current time by querying the kernel, updating the time 695Establishes the current time by querying the kernel, updating the time
686returned by C<ev_now ()> in the progress. This is a costly operation and 696returned by C<ev_now ()> in the progress. This is a costly operation and
687is usually done automatically within C<ev_loop ()>. 697is usually done automatically within C<ev_run ()>.
688 698
689This function is rarely useful, but when some event callback runs for a 699This function is rarely useful, but when some event callback runs for a
690very long time without entering the event loop, updating libev's idea of 700very long time without entering the event loop, updating libev's idea of
691the current time is a good idea. 701the current time is a good idea.
692 702
694 704
695=item ev_suspend (loop) 705=item ev_suspend (loop)
696 706
697=item ev_resume (loop) 707=item ev_resume (loop)
698 708
699These two functions suspend and resume a loop, for use when the loop is 709These two functions suspend and resume an event loop, for use when the
700not used for a while and timeouts should not be processed. 710loop is not used for a while and timeouts should not be processed.
701 711
702A typical use case would be an interactive program such as a game: When 712A typical use case would be an interactive program such as a game: When
703the user presses C<^Z> to suspend the game and resumes it an hour later it 713the user presses C<^Z> to suspend the game and resumes it an hour later it
704would be best to handle timeouts as if no time had actually passed while 714would be best to handle timeouts as if no time had actually passed while
705the program was suspended. This can be achieved by calling C<ev_suspend> 715the program was suspended. This can be achieved by calling C<ev_suspend>
716without a previous call to C<ev_suspend>. 726without a previous call to C<ev_suspend>.
717 727
718Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the 728Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
719event loop time (see C<ev_now_update>). 729event loop time (see C<ev_now_update>).
720 730
721=item ev_loop (loop, int flags) 731=item ev_run (loop, int flags)
722 732
723Finally, this is it, the event handler. This function usually is called 733Finally, this is it, the event handler. This function usually is called
724after you have initialised all your watchers and you want to start 734after you have initialised all your watchers and you want to start
725handling events. 735handling events. It will ask the operating system for any new events, call
736the watcher callbacks, an then repeat the whole process indefinitely: This
737is why event loops are called I<loops>.
726 738
727If the flags argument is specified as C<0>, it will not return until 739If the flags argument is specified as C<0>, it will keep handling events
728either no event watchers are active anymore or C<ev_unloop> was called. 740until either no event watchers are active anymore or C<ev_break> was
741called.
729 742
730Please note that an explicit C<ev_unloop> is usually better than 743Please note that an explicit C<ev_break> is usually better than
731relying on all watchers to be stopped when deciding when a program has 744relying on all watchers to be stopped when deciding when a program has
732finished (especially in interactive programs), but having a program 745finished (especially in interactive programs), but having a program
733that automatically loops as long as it has to and no longer by virtue 746that automatically loops as long as it has to and no longer by virtue
734of relying on its watchers stopping correctly, that is truly a thing of 747of relying on its watchers stopping correctly, that is truly a thing of
735beauty. 748beauty.
736 749
737A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle 750A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
738those events and any already outstanding ones, but will not block your 751those events and any already outstanding ones, but will not wait and
739process in case there are no events and will return after one iteration of 752block your process in case there are no events and will return after one
740the loop. 753iteration of the loop. This is sometimes useful to poll and handle new
754events while doing lengthy calculations, to keep the program responsive.
741 755
742A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if 756A flags value of C<EVRUN_ONCE> will look for new events (waiting if
743necessary) and will handle those and any already outstanding ones. It 757necessary) and will handle those and any already outstanding ones. It
744will block your process until at least one new event arrives (which could 758will block your process until at least one new event arrives (which could
745be an event internal to libev itself, so there is no guarantee that a 759be an event internal to libev itself, so there is no guarantee that a
746user-registered callback will be called), and will return after one 760user-registered callback will be called), and will return after one
747iteration of the loop. 761iteration of the loop.
748 762
749This is useful if you are waiting for some external event in conjunction 763This is useful if you are waiting for some external event in conjunction
750with something not expressible using other libev watchers (i.e. "roll your 764with something not expressible using other libev watchers (i.e. "roll your
751own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is 765own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
752usually a better approach for this kind of thing. 766usually a better approach for this kind of thing.
753 767
754Here are the gory details of what C<ev_loop> does: 768Here are the gory details of what C<ev_run> does:
755 769
770 - Increment loop depth.
771 - Reset the ev_break status.
756 - Before the first iteration, call any pending watchers. 772 - Before the first iteration, call any pending watchers.
773 LOOP:
757 * If EVFLAG_FORKCHECK was used, check for a fork. 774 - If EVFLAG_FORKCHECK was used, check for a fork.
758 - If a fork was detected (by any means), queue and call all fork watchers. 775 - If a fork was detected (by any means), queue and call all fork watchers.
759 - Queue and call all prepare watchers. 776 - Queue and call all prepare watchers.
777 - If ev_break was called, goto FINISH.
760 - If we have been forked, detach and recreate the kernel state 778 - If we have been forked, detach and recreate the kernel state
761 as to not disturb the other process. 779 as to not disturb the other process.
762 - Update the kernel state with all outstanding changes. 780 - Update the kernel state with all outstanding changes.
763 - Update the "event loop time" (ev_now ()). 781 - Update the "event loop time" (ev_now ()).
764 - Calculate for how long to sleep or block, if at all 782 - Calculate for how long to sleep or block, if at all
765 (active idle watchers, EVLOOP_NONBLOCK or not having 783 (active idle watchers, EVRUN_NOWAIT or not having
766 any active watchers at all will result in not sleeping). 784 any active watchers at all will result in not sleeping).
767 - Sleep if the I/O and timer collect interval say so. 785 - Sleep if the I/O and timer collect interval say so.
786 - Increment loop iteration counter.
768 - Block the process, waiting for any events. 787 - Block the process, waiting for any events.
769 - Queue all outstanding I/O (fd) events. 788 - Queue all outstanding I/O (fd) events.
770 - Update the "event loop time" (ev_now ()), and do time jump adjustments. 789 - Update the "event loop time" (ev_now ()), and do time jump adjustments.
771 - Queue all expired timers. 790 - Queue all expired timers.
772 - Queue all expired periodics. 791 - Queue all expired periodics.
773 - Unless any events are pending now, queue all idle watchers. 792 - Queue all idle watchers with priority higher than that of pending events.
774 - Queue all check watchers. 793 - Queue all check watchers.
775 - Call all queued watchers in reverse order (i.e. check watchers first). 794 - Call all queued watchers in reverse order (i.e. check watchers first).
776 Signals and child watchers are implemented as I/O watchers, and will 795 Signals and child watchers are implemented as I/O watchers, and will
777 be handled here by queueing them when their watcher gets executed. 796 be handled here by queueing them when their watcher gets executed.
778 - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 797 - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
779 were used, or there are no active watchers, return, otherwise 798 were used, or there are no active watchers, goto FINISH, otherwise
780 continue with step *. 799 continue with step LOOP.
800 FINISH:
801 - Reset the ev_break status iff it was EVBREAK_ONE.
802 - Decrement the loop depth.
803 - Return.
781 804
782Example: Queue some jobs and then loop until no events are outstanding 805Example: Queue some jobs and then loop until no events are outstanding
783anymore. 806anymore.
784 807
785 ... queue jobs here, make sure they register event watchers as long 808 ... queue jobs here, make sure they register event watchers as long
786 ... as they still have work to do (even an idle watcher will do..) 809 ... as they still have work to do (even an idle watcher will do..)
787 ev_loop (my_loop, 0); 810 ev_run (my_loop, 0);
788 ... jobs done or somebody called unloop. yeah! 811 ... jobs done or somebody called unloop. yeah!
789 812
790=item ev_unloop (loop, how) 813=item ev_break (loop, how)
791 814
792Can be used to make a call to C<ev_loop> return early (but only after it 815Can be used to make a call to C<ev_run> return early (but only after it
793has processed all outstanding events). The C<how> argument must be either 816has processed all outstanding events). The C<how> argument must be either
794C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or 817C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
795C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. 818C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
796 819
797This "unloop state" will be cleared when entering C<ev_loop> again. 820This "unloop state" will be cleared when entering C<ev_run> again.
798 821
799It is safe to call C<ev_unloop> from outside any C<ev_loop> calls. 822It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
800 823
801=item ev_ref (loop) 824=item ev_ref (loop)
802 825
803=item ev_unref (loop) 826=item ev_unref (loop)
804 827
805Ref/unref can be used to add or remove a reference count on the event 828Ref/unref can be used to add or remove a reference count on the event
806loop: Every watcher keeps one reference, and as long as the reference 829loop: Every watcher keeps one reference, and as long as the reference
807count is nonzero, C<ev_loop> will not return on its own. 830count is nonzero, C<ev_run> will not return on its own.
808 831
809This is useful when you have a watcher that you never intend to 832This is useful when you have a watcher that you never intend to
810unregister, but that nevertheless should not keep C<ev_loop> from 833unregister, but that nevertheless should not keep C<ev_run> from
811returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> 834returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
812before stopping it. 835before stopping it.
813 836
814As an example, libev itself uses this for its internal signal pipe: It 837As an example, libev itself uses this for its internal signal pipe: It
815is not visible to the libev user and should not keep C<ev_loop> from 838is not visible to the libev user and should not keep C<ev_run> from
816exiting if no event watchers registered by it are active. It is also an 839exiting if no event watchers registered by it are active. It is also an
817excellent way to do this for generic recurring timers or from within 840excellent way to do this for generic recurring timers or from within
818third-party libraries. Just remember to I<unref after start> and I<ref 841third-party libraries. Just remember to I<unref after start> and I<ref
819before stop> (but only if the watcher wasn't active before, or was active 842before stop> (but only if the watcher wasn't active before, or was active
820before, respectively. Note also that libev might stop watchers itself 843before, respectively. Note also that libev might stop watchers itself
821(e.g. non-repeating timers) in which case you have to C<ev_ref> 844(e.g. non-repeating timers) in which case you have to C<ev_ref>
822in the callback). 845in the callback).
823 846
824Example: Create a signal watcher, but keep it from keeping C<ev_loop> 847Example: Create a signal watcher, but keep it from keeping C<ev_run>
825running when nothing else is active. 848running when nothing else is active.
826 849
827 ev_signal exitsig; 850 ev_signal exitsig;
828 ev_signal_init (&exitsig, sig_cb, SIGINT); 851 ev_signal_init (&exitsig, sig_cb, SIGINT);
829 ev_signal_start (loop, &exitsig); 852 ev_signal_start (loop, &exitsig);
892 ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); 915 ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
893 916
894=item ev_invoke_pending (loop) 917=item ev_invoke_pending (loop)
895 918
896This call will simply invoke all pending watchers while resetting their 919This call will simply invoke all pending watchers while resetting their
897pending state. Normally, C<ev_loop> does this automatically when required, 920pending state. Normally, C<ev_run> does this automatically when required,
898but when overriding the invoke callback this call comes handy. 921but when overriding the invoke callback this call comes handy. This
922function can be invoked from a watcher - this can be useful for example
923when you want to do some lengthy calculation and want to pass further
924event handling to another thread (you still have to make sure only one
925thread executes within C<ev_invoke_pending> or C<ev_run> of course).
899 926
900=item int ev_pending_count (loop) 927=item int ev_pending_count (loop)
901 928
902Returns the number of pending watchers - zero indicates that no watchers 929Returns the number of pending watchers - zero indicates that no watchers
903are pending. 930are pending.
904 931
905=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) 932=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
906 933
907This overrides the invoke pending functionality of the loop: Instead of 934This overrides the invoke pending functionality of the loop: Instead of
908invoking all pending watchers when there are any, C<ev_loop> will call 935invoking all pending watchers when there are any, C<ev_run> will call
909this callback instead. This is useful, for example, when you want to 936this callback instead. This is useful, for example, when you want to
910invoke the actual watchers inside another context (another thread etc.). 937invoke the actual watchers inside another context (another thread etc.).
911 938
912If you want to reset the callback, use C<ev_invoke_pending> as new 939If you want to reset the callback, use C<ev_invoke_pending> as new
913callback. 940callback.
916 943
917Sometimes you want to share the same loop between multiple threads. This 944Sometimes you want to share the same loop between multiple threads. This
918can be done relatively simply by putting mutex_lock/unlock calls around 945can be done relatively simply by putting mutex_lock/unlock calls around
919each call to a libev function. 946each call to a libev function.
920 947
921However, C<ev_loop> can run an indefinite time, so it is not feasible to 948However, C<ev_run> can run an indefinite time, so it is not feasible
922wait for it to return. One way around this is to wake up the loop via 949to wait for it to return. One way around this is to wake up the event
923C<ev_unloop> and C<av_async_send>, another way is to set these I<release> 950loop via C<ev_break> and C<av_async_send>, another way is to set these
924and I<acquire> callbacks on the loop. 951I<release> and I<acquire> callbacks on the loop.
925 952
926When set, then C<release> will be called just before the thread is 953When set, then C<release> will be called just before the thread is
927suspended waiting for new events, and C<acquire> is called just 954suspended waiting for new events, and C<acquire> is called just
928afterwards. 955afterwards.
929 956
932 959
933While event loop modifications are allowed between invocations of 960While event loop modifications are allowed between invocations of
934C<release> and C<acquire> (that's their only purpose after all), no 961C<release> and C<acquire> (that's their only purpose after all), no
935modifications done will affect the event loop, i.e. adding watchers will 962modifications done will affect the event loop, i.e. adding watchers will
936have no effect on the set of file descriptors being watched, or the time 963have no effect on the set of file descriptors being watched, or the time
937waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it 964waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
938to take note of any changes you made. 965to take note of any changes you made.
939 966
940In theory, threads executing C<ev_loop> will be async-cancel safe between 967In theory, threads executing C<ev_run> will be async-cancel safe between
941invocations of C<release> and C<acquire>. 968invocations of C<release> and C<acquire>.
942 969
943See also the locking example in the C<THREADS> section later in this 970See also the locking example in the C<THREADS> section later in this
944document. 971document.
945 972
975 1002
976In the following description, uppercase C<TYPE> in names stands for the 1003In the following description, uppercase C<TYPE> in names stands for the
977watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer 1004watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
978watchers and C<ev_io_start> for I/O watchers. 1005watchers and C<ev_io_start> for I/O watchers.
979 1006
980A watcher is a structure that you create and register to record your 1007A watcher is an opaque structure that you allocate and register to record
981interest in some event. For instance, if you want to wait for STDIN to 1008your interest in some event. To make a concrete example, imagine you want
982become readable, you would create an C<ev_io> watcher for that: 1009to wait for STDIN to become readable, you would create an C<ev_io> watcher
1010for that:
983 1011
984 static void my_cb (struct ev_loop *loop, ev_io *w, int revents) 1012 static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
985 { 1013 {
986 ev_io_stop (w); 1014 ev_io_stop (w);
987 ev_unloop (loop, EVUNLOOP_ALL); 1015 ev_break (loop, EVBREAK_ALL);
988 } 1016 }
989 1017
990 struct ev_loop *loop = ev_default_loop (0); 1018 struct ev_loop *loop = ev_default_loop (0);
991 1019
992 ev_io stdin_watcher; 1020 ev_io stdin_watcher;
993 1021
994 ev_init (&stdin_watcher, my_cb); 1022 ev_init (&stdin_watcher, my_cb);
995 ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); 1023 ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
996 ev_io_start (loop, &stdin_watcher); 1024 ev_io_start (loop, &stdin_watcher);
997 1025
998 ev_loop (loop, 0); 1026 ev_run (loop, 0);
999 1027
1000As you can see, you are responsible for allocating the memory for your 1028As you can see, you are responsible for allocating the memory for your
1001watcher structures (and it is I<usually> a bad idea to do this on the 1029watcher structures (and it is I<usually> a bad idea to do this on the
1002stack). 1030stack).
1003 1031
1004Each watcher has an associated watcher structure (called C<struct ev_TYPE> 1032Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1005or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). 1033or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1006 1034
1007Each watcher structure must be initialised by a call to C<ev_init 1035Each watcher structure must be initialised by a call to C<ev_init (watcher
1008(watcher *, callback)>, which expects a callback to be provided. This 1036*, callback)>, which expects a callback to be provided. This callback is
1009callback gets invoked each time the event occurs (or, in the case of I/O 1037invoked each time the event occurs (or, in the case of I/O watchers, each
1010watchers, each time the event loop detects that the file descriptor given 1038time the event loop detects that the file descriptor given is readable
1011is readable and/or writable). 1039and/or writable).
1012 1040
1013Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> 1041Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1014macro to configure it, with arguments specific to the watcher type. There 1042macro to configure it, with arguments specific to the watcher type. There
1015is also a macro to combine initialisation and setting in one call: C<< 1043is also a macro to combine initialisation and setting in one call: C<<
1016ev_TYPE_init (watcher *, callback, ...) >>. 1044ev_TYPE_init (watcher *, callback, ...) >>.
1067 1095
1068=item C<EV_PREPARE> 1096=item C<EV_PREPARE>
1069 1097
1070=item C<EV_CHECK> 1098=item C<EV_CHECK>
1071 1099
1072All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts 1100All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1073to gather new events, and all C<ev_check> watchers are invoked just after 1101to gather new events, and all C<ev_check> watchers are invoked just after
1074C<ev_loop> has gathered them, but before it invokes any callbacks for any 1102C<ev_run> has gathered them, but before it invokes any callbacks for any
1075received events. Callbacks of both watcher types can start and stop as 1103received events. Callbacks of both watcher types can start and stop as
1076many watchers as they want, and all of them will be taken into account 1104many watchers as they want, and all of them will be taken into account
1077(for example, a C<ev_prepare> watcher might start an idle watcher to keep 1105(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1078C<ev_loop> from blocking). 1106C<ev_run> from blocking).
1079 1107
1080=item C<EV_EMBED> 1108=item C<EV_EMBED>
1081 1109
1082The embedded event loop specified in the C<ev_embed> watcher needs attention. 1110The embedded event loop specified in the C<ev_embed> watcher needs attention.
1083 1111
1084=item C<EV_FORK> 1112=item C<EV_FORK>
1085 1113
1086The event loop has been resumed in the child process after fork (see 1114The event loop has been resumed in the child process after fork (see
1087C<ev_fork>). 1115C<ev_fork>).
1116
1117=item C<EV_CLEANUP>
1118
1119The event loop is abotu to be destroyed (see C<ev_cleanup>).
1088 1120
1089=item C<EV_ASYNC> 1121=item C<EV_ASYNC>
1090 1122
1091The given async watcher has been asynchronously notified (see C<ev_async>). 1123The given async watcher has been asynchronously notified (see C<ev_async>).
1092 1124
1111example it might indicate that a fd is readable or writable, and if your 1143example it might indicate that a fd is readable or writable, and if your
1112callbacks is well-written it can just attempt the operation and cope with 1144callbacks is well-written it can just attempt the operation and cope with
1113the error from read() or write(). This will not work in multi-threaded 1145the error from read() or write(). This will not work in multi-threaded
1114programs, though, as the fd could already be closed and reused for another 1146programs, though, as the fd could already be closed and reused for another
1115thing, so beware. 1147thing, so beware.
1148
1149=back
1150
1151=head2 WATCHER STATES
1152
1153There are various watcher states mentioned throughout this manual -
1154active, pending and so on. In this section these states and the rules to
1155transition between them will be described in more detail - and while these
1156rules might look complicated, they usually do "the right thing".
1157
1158=over 4
1159
1160=item initialiased
1161
1162Before a watcher can be registered with the event looop it has to be
1163initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
1164C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1165
1166In this state it is simply some block of memory that is suitable for use
1167in an event loop. It can be moved around, freed, reused etc. at will.
1168
1169=item started/running/active
1170
1171Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1172property of the event loop, and is actively waiting for events. While in
1173this state it cannot be accessed (except in a few documented ways), moved,
1174freed or anything else - the only legal thing is to keep a pointer to it,
1175and call libev functions on it that are documented to work on active watchers.
1176
1177=item pending
1178
1179If a watcher is active and libev determines that an event it is interested
1180in has occurred (such as a timer expiring), it will become pending. It will
1181stay in this pending state until either it is stopped or its callback is
1182about to be invoked, so it is not normally pending inside the watcher
1183callback.
1184
1185The watcher might or might not be active while it is pending (for example,
1186an expired non-repeating timer can be pending but no longer active). If it
1187is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
1188but it is still property of the event loop at this time, so cannot be
1189moved, freed or reused. And if it is active the rules described in the
1190previous item still apply.
1191
1192It is also possible to feed an event on a watcher that is not active (e.g.
1193via C<ev_feed_event>), in which case it becomes pending without being
1194active.
1195
1196=item stopped
1197
1198A watcher can be stopped implicitly by libev (in which case it might still
1199be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1200latter will clear any pending state the watcher might be in, regardless
1201of whether it was active or not, so stopping a watcher explicitly before
1202freeing it is often a good idea.
1203
1204While stopped (and not pending) the watcher is essentially in the
1205initialised state, that is it can be reused, moved, modified in any way
1206you wish.
1116 1207
1117=back 1208=back
1118 1209
1119=head2 GENERIC WATCHER FUNCTIONS 1210=head2 GENERIC WATCHER FUNCTIONS
1120 1211
1624 ... 1715 ...
1625 struct ev_loop *loop = ev_default_init (0); 1716 struct ev_loop *loop = ev_default_init (0);
1626 ev_io stdin_readable; 1717 ev_io stdin_readable;
1627 ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1718 ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1628 ev_io_start (loop, &stdin_readable); 1719 ev_io_start (loop, &stdin_readable);
1629 ev_loop (loop, 0); 1720 ev_run (loop, 0);
1630 1721
1631 1722
1632=head2 C<ev_timer> - relative and optionally repeating timeouts 1723=head2 C<ev_timer> - relative and optionally repeating timeouts
1633 1724
1634Timer watchers are simple relative timers that generate an event after a 1725Timer watchers are simple relative timers that generate an event after a
1643The callback is guaranteed to be invoked only I<after> its timeout has 1734The callback is guaranteed to be invoked only I<after> its timeout has
1644passed (not I<at>, so on systems with very low-resolution clocks this 1735passed (not I<at>, so on systems with very low-resolution clocks this
1645might introduce a small delay). If multiple timers become ready during the 1736might introduce a small delay). If multiple timers become ready during the
1646same loop iteration then the ones with earlier time-out values are invoked 1737same loop iteration then the ones with earlier time-out values are invoked
1647before ones of the same priority with later time-out values (but this is 1738before ones of the same priority with later time-out values (but this is
1648no longer true when a callback calls C<ev_loop> recursively). 1739no longer true when a callback calls C<ev_run> recursively).
1649 1740
1650=head3 Be smart about timeouts 1741=head3 Be smart about timeouts
1651 1742
1652Many real-world problems involve some kind of timeout, usually for error 1743Many real-world problems involve some kind of timeout, usually for error
1653recovery. A typical example is an HTTP request - if the other side hangs, 1744recovery. A typical example is an HTTP request - if the other side hangs,
1824 1915
1825=head3 The special problem of time updates 1916=head3 The special problem of time updates
1826 1917
1827Establishing the current time is a costly operation (it usually takes at 1918Establishing the current time is a costly operation (it usually takes at
1828least two system calls): EV therefore updates its idea of the current 1919least two system calls): EV therefore updates its idea of the current
1829time only before and after C<ev_loop> collects new events, which causes a 1920time only before and after C<ev_run> collects new events, which causes a
1830growing difference between C<ev_now ()> and C<ev_time ()> when handling 1921growing difference between C<ev_now ()> and C<ev_time ()> when handling
1831lots of events in one iteration. 1922lots of events in one iteration.
1832 1923
1833The relative timeouts are calculated relative to the C<ev_now ()> 1924The relative timeouts are calculated relative to the C<ev_now ()>
1834time. This is usually the right thing as this timestamp refers to the time 1925time. This is usually the right thing as this timestamp refers to the time
1951 } 2042 }
1952 2043
1953 ev_timer mytimer; 2044 ev_timer mytimer;
1954 ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ 2045 ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1955 ev_timer_again (&mytimer); /* start timer */ 2046 ev_timer_again (&mytimer); /* start timer */
1956 ev_loop (loop, 0); 2047 ev_run (loop, 0);
1957 2048
1958 // and in some piece of code that gets executed on any "activity": 2049 // and in some piece of code that gets executed on any "activity":
1959 // reset the timeout to start ticking again at 10 seconds 2050 // reset the timeout to start ticking again at 10 seconds
1960 ev_timer_again (&mytimer); 2051 ev_timer_again (&mytimer);
1961 2052
1987 2078
1988As with timers, the callback is guaranteed to be invoked only when the 2079As with timers, the callback is guaranteed to be invoked only when the
1989point in time where it is supposed to trigger has passed. If multiple 2080point in time where it is supposed to trigger has passed. If multiple
1990timers become ready during the same loop iteration then the ones with 2081timers become ready during the same loop iteration then the ones with
1991earlier time-out values are invoked before ones with later time-out values 2082earlier time-out values are invoked before ones with later time-out values
1992(but this is no longer true when a callback calls C<ev_loop> recursively). 2083(but this is no longer true when a callback calls C<ev_run> recursively).
1993 2084
1994=head3 Watcher-Specific Functions and Data Members 2085=head3 Watcher-Specific Functions and Data Members
1995 2086
1996=over 4 2087=over 4
1997 2088
2235Example: Try to exit cleanly on SIGINT. 2326Example: Try to exit cleanly on SIGINT.
2236 2327
2237 static void 2328 static void
2238 sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) 2329 sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2239 { 2330 {
2240 ev_unloop (loop, EVUNLOOP_ALL); 2331 ev_break (loop, EVBREAK_ALL);
2241 } 2332 }
2242 2333
2243 ev_signal signal_watcher; 2334 ev_signal signal_watcher;
2244 ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 2335 ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2245 ev_signal_start (loop, &signal_watcher); 2336 ev_signal_start (loop, &signal_watcher);
2631 2722
2632Prepare and check watchers are usually (but not always) used in pairs: 2723Prepare and check watchers are usually (but not always) used in pairs:
2633prepare watchers get invoked before the process blocks and check watchers 2724prepare watchers get invoked before the process blocks and check watchers
2634afterwards. 2725afterwards.
2635 2726
2636You I<must not> call C<ev_loop> or similar functions that enter 2727You I<must not> call C<ev_run> or similar functions that enter
2637the current event loop from either C<ev_prepare> or C<ev_check> 2728the current event loop from either C<ev_prepare> or C<ev_check>
2638watchers. Other loops than the current one are fine, however. The 2729watchers. Other loops than the current one are fine, however. The
2639rationale behind this is that you do not need to check for recursion in 2730rationale behind this is that you do not need to check for recursion in
2640those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, 2731those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2641C<ev_check> so if you have one watcher of each kind they will always be 2732C<ev_check> so if you have one watcher of each kind they will always be
2809 2900
2810 if (timeout >= 0) 2901 if (timeout >= 0)
2811 // create/start timer 2902 // create/start timer
2812 2903
2813 // poll 2904 // poll
2814 ev_loop (EV_A_ 0); 2905 ev_run (EV_A_ 0);
2815 2906
2816 // stop timer again 2907 // stop timer again
2817 if (timeout >= 0) 2908 if (timeout >= 0)
2818 ev_timer_stop (EV_A_ &to); 2909 ev_timer_stop (EV_A_ &to);
2819 2910
2897if you do not want that, you need to temporarily stop the embed watcher). 2988if you do not want that, you need to temporarily stop the embed watcher).
2898 2989
2899=item ev_embed_sweep (loop, ev_embed *) 2990=item ev_embed_sweep (loop, ev_embed *)
2900 2991
2901Make a single, non-blocking sweep over the embedded loop. This works 2992Make a single, non-blocking sweep over the embedded loop. This works
2902similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most 2993similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2903appropriate way for embedded loops. 2994appropriate way for embedded loops.
2904 2995
2905=item struct ev_loop *other [read-only] 2996=item struct ev_loop *other [read-only]
2906 2997
2907The embedded event loop. 2998The embedded event loop.
2993disadvantage of having to use multiple event loops (which do not support 3084disadvantage of having to use multiple event loops (which do not support
2994signal watchers). 3085signal watchers).
2995 3086
2996When this is not possible, or you want to use the default loop for 3087When this is not possible, or you want to use the default loop for
2997other reasons, then in the process that wants to start "fresh", call 3088other reasons, then in the process that wants to start "fresh", call
2998C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying 3089C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2999the default loop will "orphan" (not stop) all registered watchers, so you 3090Destroying the default loop will "orphan" (not stop) all registered
3000have to be careful not to execute code that modifies those watchers. Note 3091watchers, so you have to be careful not to execute code that modifies
3001also that in that case, you have to re-register any signal watchers. 3092those watchers. Note also that in that case, you have to re-register any
3093signal watchers.
3002 3094
3003=head3 Watcher-Specific Functions and Data Members 3095=head3 Watcher-Specific Functions and Data Members
3004 3096
3005=over 4 3097=over 4
3006 3098
3007=item ev_fork_init (ev_signal *, callback) 3099=item ev_fork_init (ev_fork *, callback)
3008 3100
3009Initialises and configures the fork watcher - it has no parameters of any 3101Initialises and configures the fork watcher - it has no parameters of any
3010kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, 3102kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3011believe me. 3103believe me.
3012 3104
3013=back 3105=back
3014 3106
3015 3107
3108=head2 C<ev_cleanup> - even the best things end
3109
3110Cleanup watchers are called just before the event loop they are registered
3111with is being destroyed.
3112
3113While there is no guarantee that the event loop gets destroyed, cleanup
3114watchers provide a convenient method to install cleanup hooks for your
3115program, worker threads and so on - you just to make sure to destroy the
3116loop when you want them to be invoked.
3117
3118Cleanup watchers are invoked in the same way as any other watcher. Unlike
3119all other watchers, they do not keep a reference to the event loop (which
3120makes a lot of sense if you think about it). Like all other watchers, you
3121can call libev functions in the callback, except C<ev_cleanup_start>.
3122
3123=head3 Watcher-Specific Functions and Data Members
3124
3125=over 4
3126
3127=item ev_cleanup_init (ev_cleanup *, callback)
3128
3129Initialises and configures the cleanup watcher - it has no parameters of
3130any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
3131pointless, believe me.
3132
3133=back
3134
3135Example: Register an atexit handler to destroy the default loop, so any
3136cleanup functions are called.
3137
3138 static void
3139 program_exits (void)
3140 {
3141 ev_loop_destroy (EV_DEFAULT_UC);
3142 }
3143
3144 ...
3145 atexit (program_exits);
3146
3147
3016=head2 C<ev_async> - how to wake up an event loop 3148=head2 C<ev_async> - how to wake up an event loop
3017 3149
3018In general, you cannot use an C<ev_loop> from multiple threads or other 3150In general, you cannot use an C<ev_run> from multiple threads or other
3019asynchronous sources such as signal handlers (as opposed to multiple event 3151asynchronous sources such as signal handlers (as opposed to multiple event
3020loops - those are of course safe to use in different threads). 3152loops - those are of course safe to use in different threads).
3021 3153
3022Sometimes, however, you need to wake up an event loop you do not control, 3154Sometimes, however, you need to wake up an event loop you do not control,
3023for example because it belongs to another thread. This is what C<ev_async> 3155for example because it belongs to another thread. This is what C<ev_async>
3530loop argument"). The C<EV_A> form is used when this is the sole argument, 3662loop argument"). The C<EV_A> form is used when this is the sole argument,
3531C<EV_A_> is used when other arguments are following. Example: 3663C<EV_A_> is used when other arguments are following. Example:
3532 3664
3533 ev_unref (EV_A); 3665 ev_unref (EV_A);
3534 ev_timer_add (EV_A_ watcher); 3666 ev_timer_add (EV_A_ watcher);
3535 ev_loop (EV_A_ 0); 3667 ev_run (EV_A_ 0);
3536 3668
3537It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, 3669It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3538which is often provided by the following macro. 3670which is often provided by the following macro.
3539 3671
3540=item C<EV_P>, C<EV_P_> 3672=item C<EV_P>, C<EV_P_>
3580 } 3712 }
3581 3713
3582 ev_check check; 3714 ev_check check;
3583 ev_check_init (&check, check_cb); 3715 ev_check_init (&check, check_cb);
3584 ev_check_start (EV_DEFAULT_ &check); 3716 ev_check_start (EV_DEFAULT_ &check);
3585 ev_loop (EV_DEFAULT_ 0); 3717 ev_run (EV_DEFAULT_ 0);
3586 3718
3587=head1 EMBEDDING 3719=head1 EMBEDDING
3588 3720
3589Libev can (and often is) directly embedded into host 3721Libev can (and often is) directly embedded into host
3590applications. Examples of applications that embed it include the Deliantra 3722applications. Examples of applications that embed it include the Deliantra
3681to a compiled library. All other symbols change the ABI, which means all 3813to a compiled library. All other symbols change the ABI, which means all
3682users of libev and the libev code itself must be compiled with compatible 3814users of libev and the libev code itself must be compiled with compatible
3683settings. 3815settings.
3684 3816
3685=over 4 3817=over 4
3818
3819=item EV_COMPAT3 (h)
3820
3821Backwards compatibility is a major concern for libev. This is why this
3822release of libev comes with wrappers for the functions and symbols that
3823have been renamed between libev version 3 and 4.
3824
3825You can disable these wrappers (to test compatibility with future
3826versions) by defining C<EV_COMPAT3> to C<0> when compiling your
3827sources. This has the additional advantage that you can drop the C<struct>
3828from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
3829typedef in that case.
3830
3831In some future version, the default for C<EV_COMPAT3> will become C<0>,
3832and in some even more future version the compatibility code will be
3833removed completely.
3686 3834
3687=item EV_STANDALONE (h) 3835=item EV_STANDALONE (h)
3688 3836
3689Must always be C<1> if you do not use autoconf configuration, which 3837Must always be C<1> if you do not use autoconf configuration, which
3690keeps libev from including F<config.h>, and it also defines dummy 3838keeps libev from including F<config.h>, and it also defines dummy
4265 userdata *u = ev_userdata (EV_A); 4413 userdata *u = ev_userdata (EV_A);
4266 pthread_mutex_lock (&u->lock); 4414 pthread_mutex_lock (&u->lock);
4267 } 4415 }
4268 4416
4269The event loop thread first acquires the mutex, and then jumps straight 4417The event loop thread first acquires the mutex, and then jumps straight
4270into C<ev_loop>: 4418into C<ev_run>:
4271 4419
4272 void * 4420 void *
4273 l_run (void *thr_arg) 4421 l_run (void *thr_arg)
4274 { 4422 {
4275 struct ev_loop *loop = (struct ev_loop *)thr_arg; 4423 struct ev_loop *loop = (struct ev_loop *)thr_arg;
4276 4424
4277 l_acquire (EV_A); 4425 l_acquire (EV_A);
4278 pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); 4426 pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4279 ev_loop (EV_A_ 0); 4427 ev_run (EV_A_ 0);
4280 l_release (EV_A); 4428 l_release (EV_A);
4281 4429
4282 return 0; 4430 return 0;
4283 } 4431 }
4284 4432
4336 4484
4337=head3 COROUTINES 4485=head3 COROUTINES
4338 4486
4339Libev is very accommodating to coroutines ("cooperative threads"): 4487Libev is very accommodating to coroutines ("cooperative threads"):
4340libev fully supports nesting calls to its functions from different 4488libev fully supports nesting calls to its functions from different
4341coroutines (e.g. you can call C<ev_loop> on the same loop from two 4489coroutines (e.g. you can call C<ev_run> on the same loop from two
4342different coroutines, and switch freely between both coroutines running 4490different coroutines, and switch freely between both coroutines running
4343the loop, as long as you don't confuse yourself). The only exception is 4491the loop, as long as you don't confuse yourself). The only exception is
4344that you must not do this from C<ev_periodic> reschedule callbacks. 4492that you must not do this from C<ev_periodic> reschedule callbacks.
4345 4493
4346Care has been taken to ensure that libev does not keep local state inside 4494Care has been taken to ensure that libev does not keep local state inside
4347C<ev_loop>, and other calls do not usually allow for coroutine switches as 4495C<ev_run>, and other calls do not usually allow for coroutine switches as
4348they do not call any callbacks. 4496they do not call any callbacks.
4349 4497
4350=head2 COMPILER WARNINGS 4498=head2 COMPILER WARNINGS
4351 4499
4352Depending on your compiler and compiler settings, you might get no or a 4500Depending on your compiler and compiler settings, you might get no or a
4436=head3 C<kqueue> is buggy 4584=head3 C<kqueue> is buggy
4437 4585
4438The kqueue syscall is broken in all known versions - most versions support 4586The kqueue syscall is broken in all known versions - most versions support
4439only sockets, many support pipes. 4587only sockets, many support pipes.
4440 4588
4441Libev tries to work around this by not using C<kqueue> by default on 4589Libev tries to work around this by not using C<kqueue> by default on this
4442this rotten platform, but of course you can still ask for it when creating 4590rotten platform, but of course you can still ask for it when creating a
4443a loop. 4591loop - embedding a socket-only kqueue loop into a select-based one is
4592probably going to work well.
4444 4593
4445=head3 C<poll> is buggy 4594=head3 C<poll> is buggy
4446 4595
4447Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> 4596Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4448implementation by something calling C<kqueue> internally around the 10.5.6 4597implementation by something calling C<kqueue> internally around the 10.5.6
4467 4616
4468=head3 C<errno> reentrancy 4617=head3 C<errno> reentrancy
4469 4618
4470The default compile environment on Solaris is unfortunately so 4619The default compile environment on Solaris is unfortunately so
4471thread-unsafe that you can't even use components/libraries compiled 4620thread-unsafe that you can't even use components/libraries compiled
4472without C<-D_REENTRANT> (as long as they use C<errno>), which, of course, 4621without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4473isn't defined by default. 4622defined by default. A valid, if stupid, implementation choice.
4474 4623
4475If you want to use libev in threaded environments you have to make sure 4624If you want to use libev in threaded environments you have to make sure
4476it's compiled with C<_REENTRANT> defined. 4625it's compiled with C<_REENTRANT> defined.
4477 4626
4478=head3 Event port backend 4627=head3 Event port backend
4479 4628
4480The scalable event interface for Solaris is called "event ports". Unfortunately, 4629The scalable event interface for Solaris is called "event
4481this mechanism is very buggy. If you run into high CPU usage, your program 4630ports". Unfortunately, this mechanism is very buggy in all major
4631releases. If you run into high CPU usage, your program freezes or you get
4482freezes or you get a large number of spurious wakeups, make sure you have 4632a large number of spurious wakeups, make sure you have all the relevant
4483all the relevant and latest kernel patches applied. No, I don't know which 4633and latest kernel patches applied. No, I don't know which ones, but there
4484ones, but there are multiple ones. 4634are multiple ones to apply, and afterwards, event ports actually work
4635great.
4485 4636
4486If you can't get it to work, you can try running the program by setting 4637If you can't get it to work, you can try running the program by setting
4487the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and 4638the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4488C<select> backends. 4639C<select> backends.
4489 4640
4490=head2 AIX POLL BUG 4641=head2 AIX POLL BUG
4491 4642
4492AIX unfortunately has a broken C<poll.h> header. Libev works around 4643AIX unfortunately has a broken C<poll.h> header. Libev works around
4493this by trying to avoid the poll backend altogether (i.e. it's not even 4644this by trying to avoid the poll backend altogether (i.e. it's not even
4494compiled in), which normally isn't a big problem as C<select> works fine 4645compiled in), which normally isn't a big problem as C<select> works fine
4495with large bitsets, and AIX is dead anyway. 4646with large bitsets on AIX, and AIX is dead anyway.
4496 4647
4497=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS 4648=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4498 4649
4499=head3 General issues 4650=head3 General issues
4500 4651
4729compatibility, so most programs should still compile. Those might be 4880compatibility, so most programs should still compile. Those might be
4730removed in later versions of libev, so better update early than late. 4881removed in later versions of libev, so better update early than late.
4731 4882
4732=over 4 4883=over 4
4733 4884
4734=item C<ev_loop_count> renamed to C<ev_iteration> 4885=item C<ev_default_destroy> and C<ev_default_fork> have been removed
4735 4886
4736=item C<ev_loop_depth> renamed to C<ev_depth> 4887These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
4737 4888
4738=item C<ev_loop_verify> renamed to C<ev_verify> 4889 ev_loop_destroy (EV_DEFAULT_UC);
4890 ev_loop_fork (EV_DEFAULT);
4891
4892=item function/symbol renames
4893
4894A number of functions and symbols have been renamed:
4895
4896 ev_loop => ev_run
4897 EVLOOP_NONBLOCK => EVRUN_NOWAIT
4898 EVLOOP_ONESHOT => EVRUN_ONCE
4899
4900 ev_unloop => ev_break
4901 EVUNLOOP_CANCEL => EVBREAK_CANCEL
4902 EVUNLOOP_ONE => EVBREAK_ONE
4903 EVUNLOOP_ALL => EVBREAK_ALL
4904
4905 EV_TIMEOUT => EV_TIMER
4906
4907 ev_loop_count => ev_iteration
4908 ev_loop_depth => ev_depth
4909 ev_loop_verify => ev_verify
4739 4910
4740Most functions working on C<struct ev_loop> objects don't have an 4911Most functions working on C<struct ev_loop> objects don't have an
4741C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is 4912C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
4913associated constants have been renamed to not collide with the C<struct
4914ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
4915as all other watcher types. Note that C<ev_loop_fork> is still called
4742still called C<ev_loop_fork> because it would otherwise clash with the 4916C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4743C<ev_fork> typedef. 4917typedef.
4744 4918
4745=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> 4919=item C<EV_COMPAT3> backwards compatibility mechanism
4746 4920
4747This is a simple rename - all other watcher types use their name 4921The backward compatibility mechanism can be controlled by
4748as revents flag, and now C<ev_timer> does, too. 4922C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4749 4923section.
4750Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4751and continue to be present for the foreseeable future, so this is mostly a
4752documentation change.
4753 4924
4754=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> 4925=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4755 4926
4756The preprocessor symbol C<EV_MINIMAL> has been replaced by a different 4927The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4757mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile 4928mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
4764 4935
4765=over 4 4936=over 4
4766 4937
4767=item active 4938=item active
4768 4939
4769A watcher is active as long as it has been started (has been attached to 4940A watcher is active as long as it has been started and not yet stopped.
4770an event loop) but not yet stopped (disassociated from the event loop). 4941See L<WATCHER STATES> for details.
4771 4942
4772=item application 4943=item application
4773 4944
4774In this document, an application is whatever is using libev. 4945In this document, an application is whatever is using libev.
4946
4947=item backend
4948
4949The part of the code dealing with the operating system interfaces.
4775 4950
4776=item callback 4951=item callback
4777 4952
4778The address of a function that is called when some event has been 4953The address of a function that is called when some event has been
4779detected. Callbacks are being passed the event loop, the watcher that 4954detected. Callbacks are being passed the event loop, the watcher that
4780received the event, and the actual event bitset. 4955received the event, and the actual event bitset.
4781 4956
4782=item callback invocation 4957=item callback/watcher invocation
4783 4958
4784The act of calling the callback associated with a watcher. 4959The act of calling the callback associated with a watcher.
4785 4960
4786=item event 4961=item event
4787 4962
4806The model used to describe how an event loop handles and processes 4981The model used to describe how an event loop handles and processes
4807watchers and events. 4982watchers and events.
4808 4983
4809=item pending 4984=item pending
4810 4985
4811A watcher is pending as soon as the corresponding event has been detected, 4986A watcher is pending as soon as the corresponding event has been
4812and stops being pending as soon as the watcher will be invoked or its 4987detected. See L<WATCHER STATES> for details.
4813pending status is explicitly cleared by the application.
4814
4815A watcher can be pending, but not active. Stopping a watcher also clears
4816its pending status.
4817 4988
4818=item real time 4989=item real time
4819 4990
4820The physical time that is observed. It is apparently strictly monotonic :) 4991The physical time that is observed. It is apparently strictly monotonic :)
4821 4992
4828=item watcher 4999=item watcher
4829 5000
4830A data structure that describes interest in certain events. Watchers need 5001A data structure that describes interest in certain events. Watchers need
4831to be started (attached to an event loop) before they can receive events. 5002to be started (attached to an event loop) before they can receive events.
4832 5003
4833=item watcher invocation
4834
4835The act of calling the callback associated with a watcher.
4836
4837=back 5004=back
4838 5005
4839=head1 AUTHOR 5006=head1 AUTHOR
4840 5007
4841Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. 5008Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.

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