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Comparing libev/ev.pod (file contents):
Revision 1.358 by sf-exg, Tue Jan 11 08:43:48 2011 UTC vs.
Revision 1.363 by root, Sun Jan 30 22:38:59 2011 UTC

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_run (loop, 0); 61 ev_run (loop, 0);
62 62
63 // unloop was called, so exit 63 // break was called, so exit
64 return 0; 64 return 0;
65 } 65 }
66 66
67=head1 ABOUT THIS DOCUMENT 67=head1 ABOUT THIS DOCUMENT
68 68
441when you want to receive them. 441when you want to receive them.
442 442
443This behaviour is useful when you want to do your own signal handling, or 443This behaviour is useful when you want to do your own signal handling, or
444want to handle signals only in specific threads and want to avoid libev 444want to handle signals only in specific threads and want to avoid libev
445unblocking the signals. 445unblocking the signals.
446
447It's also required by POSIX in a threaded program, as libev calls
448C<sigprocmask>, whose behaviour is officially unspecified.
446 449
447This flag's behaviour will become the default in future versions of libev. 450This flag's behaviour will become the default in future versions of libev.
448 451
449=item C<EVBACKEND_SELECT> (value 1, portable select backend) 452=item C<EVBACKEND_SELECT> (value 1, portable select backend)
450 453
865anymore. 868anymore.
866 869
867 ... queue jobs here, make sure they register event watchers as long 870 ... queue jobs here, make sure they register event watchers as long
868 ... as they still have work to do (even an idle watcher will do..) 871 ... as they still have work to do (even an idle watcher will do..)
869 ev_run (my_loop, 0); 872 ev_run (my_loop, 0);
870 ... jobs done or somebody called unloop. yeah! 873 ... jobs done or somebody called break. yeah!
871 874
872=item ev_break (loop, how) 875=item ev_break (loop, how)
873 876
874Can be used to make a call to C<ev_run> return early (but only after it 877Can be used to make a call to C<ev_run> return early (but only after it
875has processed all outstanding events). The C<how> argument must be either 878has processed all outstanding events). The C<how> argument must be either
1375 1378
1376Before a watcher can be registered with the event looop it has to be 1379Before a watcher can be registered with the event looop it has to be
1377initialised. This can be done with a call to C<ev_TYPE_init>, or calls to 1380initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
1378C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. 1381C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1379 1382
1380In this state it is simply some block of memory that is suitable for use 1383In this state it is simply some block of memory that is suitable for
1381in an event loop. It can be moved around, freed, reused etc. at will. 1384use in an event loop. It can be moved around, freed, reused etc. at
1385will - as long as you either keep the memory contents intact, or call
1386C<ev_TYPE_init> again.
1382 1387
1383=item started/running/active 1388=item started/running/active
1384 1389
1385Once a watcher has been started with a call to C<ev_TYPE_start> it becomes 1390Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1386property of the event loop, and is actively waiting for events. While in 1391property of the event loop, and is actively waiting for events. While in
1414latter will clear any pending state the watcher might be in, regardless 1419latter will clear any pending state the watcher might be in, regardless
1415of whether it was active or not, so stopping a watcher explicitly before 1420of whether it was active or not, so stopping a watcher explicitly before
1416freeing it is often a good idea. 1421freeing it is often a good idea.
1417 1422
1418While stopped (and not pending) the watcher is essentially in the 1423While stopped (and not pending) the watcher is essentially in the
1419initialised state, that is it can be reused, moved, modified in any way 1424initialised state, that is, it can be reused, moved, modified in any way
1420you wish. 1425you wish (but when you trash the memory block, you need to C<ev_TYPE_init>
1426it again).
1421 1427
1422=back 1428=back
1423 1429
1424=head2 WATCHER PRIORITY MODELS 1430=head2 WATCHER PRIORITY MODELS
1425 1431
2300=head3 The special problem of inheritance over fork/execve/pthread_create 2306=head3 The special problem of inheritance over fork/execve/pthread_create
2301 2307
2302Both the signal mask (C<sigprocmask>) and the signal disposition 2308Both the signal mask (C<sigprocmask>) and the signal disposition
2303(C<sigaction>) are unspecified after starting a signal watcher (and after 2309(C<sigaction>) are unspecified after starting a signal watcher (and after
2304stopping it again), that is, libev might or might not block the signal, 2310stopping it again), that is, libev might or might not block the signal,
2305and might or might not set or restore the installed signal handler. 2311and might or might not set or restore the installed signal handler (but
2312see C<EVFLAG_NOSIGMASK>).
2306 2313
2307While this does not matter for the signal disposition (libev never 2314While this does not matter for the signal disposition (libev never
2308sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on 2315sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
2309C<execve>), this matters for the signal mask: many programs do not expect 2316C<execve>), this matters for the signal mask: many programs do not expect
2310certain signals to be blocked. 2317certain signals to be blocked.
3181 atexit (program_exits); 3188 atexit (program_exits);
3182 3189
3183 3190
3184=head2 C<ev_async> - how to wake up an event loop 3191=head2 C<ev_async> - how to wake up an event loop
3185 3192
3186In general, you cannot use an C<ev_run> from multiple threads or other 3193In general, you cannot use an C<ev_loop> from multiple threads or other
3187asynchronous sources such as signal handlers (as opposed to multiple event 3194asynchronous sources such as signal handlers (as opposed to multiple event
3188loops - those are of course safe to use in different threads). 3195loops - those are of course safe to use in different threads).
3189 3196
3190Sometimes, however, you need to wake up an event loop you do not control, 3197Sometimes, however, you need to wake up an event loop you do not control,
3191for example because it belongs to another thread. This is what C<ev_async> 3198for example because it belongs to another thread. This is what C<ev_async>
3301trust me. 3308trust me.
3302 3309
3303=item ev_async_send (loop, ev_async *) 3310=item ev_async_send (loop, ev_async *)
3304 3311
3305Sends/signals/activates the given C<ev_async> watcher, that is, feeds 3312Sends/signals/activates the given C<ev_async> watcher, that is, feeds
3306an C<EV_ASYNC> event on the watcher into the event loop. Unlike 3313an C<EV_ASYNC> event on the watcher into the event loop, and instanlty
3314returns.
3315
3307C<ev_feed_event>, this call is safe to do from other threads, signal or 3316Unlike C<ev_feed_event>, this call is safe to do from other threads,
3308similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding 3317signal or similar contexts (see the discussion of C<EV_ATOMIC_T> in the
3309section below on what exactly this means). 3318embedding section below on what exactly this means).
3310 3319
3311Note that, as with other watchers in libev, multiple events might get 3320Note that, as with other watchers in libev, multiple events might get
3312compressed into a single callback invocation (another way to look at this 3321compressed into a single callback invocation (another way to look at this
3313is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, 3322is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,
3314reset when the event loop detects that). 3323reset when the event loop detects that).
3504 exit_main_loop = exit_nested_loop = 1; 3513 exit_main_loop = exit_nested_loop = 1;
3505 3514
3506=head2 THREAD LOCKING EXAMPLE 3515=head2 THREAD LOCKING EXAMPLE
3507 3516
3508Here is a fictitious example of how to run an event loop in a different 3517Here is a fictitious example of how to run an event loop in a different
3509thread than where callbacks are being invoked and watchers are 3518thread from where callbacks are being invoked and watchers are
3510created/added/removed. 3519created/added/removed.
3511 3520
3512For a real-world example, see the C<EV::Loop::Async> perl module, 3521For a real-world example, see the C<EV::Loop::Async> perl module,
3513which uses exactly this technique (which is suited for many high-level 3522which uses exactly this technique (which is suited for many high-level
3514languages). 3523languages).
3540 // now associate this with the loop 3549 // now associate this with the loop
3541 ev_set_userdata (EV_A_ u); 3550 ev_set_userdata (EV_A_ u);
3542 ev_set_invoke_pending_cb (EV_A_ l_invoke); 3551 ev_set_invoke_pending_cb (EV_A_ l_invoke);
3543 ev_set_loop_release_cb (EV_A_ l_release, l_acquire); 3552 ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
3544 3553
3545 // then create the thread running ev_loop 3554 // then create the thread running ev_run
3546 pthread_create (&u->tid, 0, l_run, EV_A); 3555 pthread_create (&u->tid, 0, l_run, EV_A);
3547 } 3556 }
3548 3557
3549The callback for the C<ev_async> watcher does nothing: the watcher is used 3558The callback for the C<ev_async> watcher does nothing: the watcher is used
3550solely to wake up the event loop so it takes notice of any new watchers 3559solely to wake up the event loop so it takes notice of any new watchers

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