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82 82
83=head1 WHAT TO READ WHEN IN A HURRY 83=head1 WHAT TO READ WHEN IN A HURRY
84 84
85This manual tries to be very detailed, but unfortunately, this also makes 85This manual tries to be very detailed, but unfortunately, this also makes
86it very long. If you just want to know the basics of libev, I suggest 86it very long. If you just want to know the basics of libev, I suggest
87reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and 87reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and
88look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and 88look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and
89C<ev_timer> sections in L<WATCHER TYPES>. 89C<ev_timer> sections in L</WATCHER TYPES>.
90 90
91=head1 ABOUT LIBEV 91=head1 ABOUT LIBEV
92 92
93Libev is an event loop: you register interest in certain events (such as a 93Libev is an event loop: you register interest in certain events (such as a
94file descriptor being readable or a timeout occurring), and it will manage 94file descriptor being readable or a timeout occurring), and it will manage
764 764
765This function is rarely useful, but when some event callback runs for a 765This function is rarely useful, but when some event callback runs for a
766very long time without entering the event loop, updating libev's idea of 766very long time without entering the event loop, updating libev's idea of
767the current time is a good idea. 767the current time is a good idea.
768 768
769See also L<The special problem of time updates> in the C<ev_timer> section. 769See also L</The special problem of time updates> in the C<ev_timer> section.
770 770
771=item ev_suspend (loop) 771=item ev_suspend (loop)
772 772
773=item ev_resume (loop) 773=item ev_resume (loop)
774 774
1318 1318
1319=item callback ev_cb (ev_TYPE *watcher) 1319=item callback ev_cb (ev_TYPE *watcher)
1320 1320
1321Returns the callback currently set on the watcher. 1321Returns the callback currently set on the watcher.
1322 1322
1323=item ev_cb_set (ev_TYPE *watcher, callback) 1323=item ev_set_cb (ev_TYPE *watcher, callback)
1324 1324
1325Change the callback. You can change the callback at virtually any time 1325Change the callback. You can change the callback at virtually any time
1326(modulo threads). 1326(modulo threads).
1327 1327
1328=item ev_set_priority (ev_TYPE *watcher, int priority) 1328=item ev_set_priority (ev_TYPE *watcher, int priority)
1346or might not have been clamped to the valid range. 1346or might not have been clamped to the valid range.
1347 1347
1348The default priority used by watchers when no priority has been set is 1348The default priority used by watchers when no priority has been set is
1349always C<0>, which is supposed to not be too high and not be too low :). 1349always C<0>, which is supposed to not be too high and not be too low :).
1350 1350
1351See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of 1351See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
1352priorities. 1352priorities.
1353 1353
1354=item ev_invoke (loop, ev_TYPE *watcher, int revents) 1354=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1355 1355
1356Invoke the C<watcher> with the given C<loop> and C<revents>. Neither 1356Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
1381See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related 1381See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1382functions that do not need a watcher. 1382functions that do not need a watcher.
1383 1383
1384=back 1384=back
1385 1385
1386See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR 1386See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR
1387OWN COMPOSITE WATCHERS> idioms. 1387OWN COMPOSITE WATCHERS> idioms.
1388 1388
1389=head2 WATCHER STATES 1389=head2 WATCHER STATES
1390 1390
1391There are various watcher states mentioned throughout this manual - 1391There are various watcher states mentioned throughout this manual -
2136=item If the timer is repeating, make the C<repeat> value the new timeout 2136=item If the timer is repeating, make the C<repeat> value the new timeout
2137and start the timer, if necessary. 2137and start the timer, if necessary.
2138 2138
2139=back 2139=back
2140 2140
2141This sounds a bit complicated, see L<Be smart about timeouts>, above, for a 2141This sounds a bit complicated, see L</Be smart about timeouts>, above, for a
2142usage example. 2142usage example.
2143 2143
2144=item ev_tstamp ev_timer_remaining (loop, ev_timer *) 2144=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
2145 2145
2146Returns the remaining time until a timer fires. If the timer is active, 2146Returns the remaining time until a timer fires. If the timer is active,
2858 2858
2859This mode of operation can be useful together with an C<ev_check> watcher, 2859This mode of operation can be useful together with an C<ev_check> watcher,
2860to do something on each event loop iteration - for example to balance load 2860to do something on each event loop iteration - for example to balance load
2861between different connections. 2861between different connections.
2862 2862
2863See L<Abusing an C<ev_check> watcher for its side-effect> for a longer 2863See L</Abusing an ev_check watcher for its side-effect> for a longer
2864example. 2864example.
2865 2865
2866=head3 Watcher-Specific Functions and Data Members 2866=head3 Watcher-Specific Functions and Data Members
2867 2867
2868=over 4 2868=over 4
2881callback, free it. Also, use no error checking, as usual. 2881callback, free it. Also, use no error checking, as usual.
2882 2882
2883 static void 2883 static void
2884 idle_cb (struct ev_loop *loop, ev_idle *w, int revents) 2884 idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
2885 { 2885 {
2886 // stop the watcher
2887 ev_idle_stop (loop, w);
2888
2889 // now we can free it
2886 free (w); 2890 free (w);
2891
2887 // now do something you wanted to do when the program has 2892 // now do something you wanted to do when the program has
2888 // no longer anything immediate to do. 2893 // no longer anything immediate to do.
2889 } 2894 }
2890 2895
2891 ev_idle *idle_watcher = malloc (sizeof (ev_idle)); 2896 ev_idle *idle_watcher = malloc (sizeof (ev_idle));
3870called): 3875called):
3871 3876
3872 void 3877 void
3873 wait_for_event (ev_watcher *w) 3878 wait_for_event (ev_watcher *w)
3874 { 3879 {
3875 ev_cb_set (w) = current_coro; 3880 ev_set_cb (w, current_coro);
3876 switch_to (libev_coro); 3881 switch_to (libev_coro);
3877 } 3882 }
3878 3883
3879That basically suspends the coroutine inside C<wait_for_event> and 3884That basically suspends the coroutine inside C<wait_for_event> and
3880continues the libev coroutine, which, when appropriate, switches back to 3885continues the libev coroutine, which, when appropriate, switches back to
3883You can do similar tricks if you have, say, threads with an event queue - 3888You can do similar tricks if you have, say, threads with an event queue -
3884instead of storing a coroutine, you store the queue object and instead of 3889instead of storing a coroutine, you store the queue object and instead of
3885switching to a coroutine, you push the watcher onto the queue and notify 3890switching to a coroutine, you push the watcher onto the queue and notify
3886any waiters. 3891any waiters.
3887 3892
3888To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two 3893To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two
3889files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: 3894files, F<my_ev.h> and F<my_ev.c> that include the respective libev files:
3890 3895
3891 // my_ev.h 3896 // my_ev.h
3892 #define EV_CB_DECLARE(type) struct my_coro *cb; 3897 #define EV_CB_DECLARE(type) struct my_coro *cb;
3893 #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); 3898 #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb);
3945libev sources can be compiled as C++. Therefore, code that uses the C API 3950libev sources can be compiled as C++. Therefore, code that uses the C API
3946will work fine. 3951will work fine.
3947 3952
3948Proper exception specifications might have to be added to callbacks passed 3953Proper exception specifications might have to be added to callbacks passed
3949to libev: exceptions may be thrown only from watcher callbacks, all 3954to libev: exceptions may be thrown only from watcher callbacks, all
3950other callbacks (allocator, syserr, loop acquire/release and periodioc 3955other callbacks (allocator, syserr, loop acquire/release and periodic
3951reschedule callbacks) must not throw exceptions, and might need a C<throw 3956reschedule callbacks) must not throw exceptions, and might need a C<throw
3952()> specification. If you have code that needs to be compiled as both C 3957()> specification. If you have code that needs to be compiled as both C
3953and C++ you can use the C<EV_THROW> macro for this: 3958and C++ you can use the C<EV_THROW> macro for this:
3954 3959
3955 static void 3960 static void
4116Associates a different C<struct ev_loop> with this watcher. You can only 4121Associates a different C<struct ev_loop> with this watcher. You can only
4117do this when the watcher is inactive (and not pending either). 4122do this when the watcher is inactive (and not pending either).
4118 4123
4119=item w->set ([arguments]) 4124=item w->set ([arguments])
4120 4125
4121Basically the same as C<ev_TYPE_set>, with the same arguments. Either this 4126Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>),
4122method or a suitable start method must be called at least once. Unlike the 4127with the same arguments. Either this method or a suitable start method
4123C counterpart, an active watcher gets automatically stopped and restarted 4128must be called at least once. Unlike the C counterpart, an active watcher
4124when reconfiguring it with this method. 4129gets automatically stopped and restarted when reconfiguring it with this
4130method.
4131
4132For C<ev::embed> watchers this method is called C<set_embed>, to avoid
4133clashing with the C<set (loop)> method.
4125 4134
4126=item w->start () 4135=item w->start ()
4127 4136
4128Starts the watcher. Note that there is no C<loop> argument, as the 4137Starts the watcher. Note that there is no C<loop> argument, as the
4129constructor already stores the event loop. 4138constructor already stores the event loop.
4232=item Lua 4241=item Lua
4233 4242
4234Brian Maher has written a partial interface to libev for lua (at the 4243Brian Maher has written a partial interface to libev for lua (at the
4235time of this writing, only C<ev_io> and C<ev_timer>), to be found at 4244time of this writing, only C<ev_io> and C<ev_timer>), to be found at
4236L<http://github.com/brimworks/lua-ev>. 4245L<http://github.com/brimworks/lua-ev>.
4246
4247=item Javascript
4248
4249Node.js (L<http://nodejs.org>) uses libev as the underlying event library.
4250
4251=item Others
4252
4253There are others, and I stopped counting.
4237 4254
4238=back 4255=back
4239 4256
4240 4257
4241=head1 MACRO MAGIC 4258=head1 MACRO MAGIC
4540 4557
4541If programs implement their own fd to handle mapping on win32, then this 4558If programs implement their own fd to handle mapping on win32, then this
4542macro can be used to override the C<close> function, useful to unregister 4559macro can be used to override the C<close> function, useful to unregister
4543file descriptors again. Note that the replacement function has to close 4560file descriptors again. Note that the replacement function has to close
4544the underlying OS handle. 4561the underlying OS handle.
4562
4563=item EV_USE_WSASOCKET
4564
4565If defined to be C<1>, libev will use C<WSASocket> to create its internal
4566communication socket, which works better in some environments. Otherwise,
4567the normal C<socket> function will be used, which works better in other
4568environments.
4545 4569
4546=item EV_USE_POLL 4570=item EV_USE_POLL
4547 4571
4548If defined to be C<1>, libev will compile in support for the C<poll>(2) 4572If defined to be C<1>, libev will compile in support for the C<poll>(2)
4549backend. Otherwise it will be enabled on non-win32 platforms. It 4573backend. Otherwise it will be enabled on non-win32 platforms. It
4988default loop and triggering an C<ev_async> watcher from the default loop 5012default loop and triggering an C<ev_async> watcher from the default loop
4989watcher callback into the event loop interested in the signal. 5013watcher callback into the event loop interested in the signal.
4990 5014
4991=back 5015=back
4992 5016
4993See also L<THREAD LOCKING EXAMPLE>. 5017See also L</THREAD LOCKING EXAMPLE>.
4994 5018
4995=head3 COROUTINES 5019=head3 COROUTINES
4996 5020
4997Libev is very accommodating to coroutines ("cooperative threads"): 5021Libev is very accommodating to coroutines ("cooperative threads"):
4998libev fully supports nesting calls to its functions from different 5022libev fully supports nesting calls to its functions from different
5404=over 4 5428=over 4
5405 5429
5406=item C<EV_COMPAT3> backwards compatibility mechanism 5430=item C<EV_COMPAT3> backwards compatibility mechanism
5407 5431
5408The backward compatibility mechanism can be controlled by 5432The backward compatibility mechanism can be controlled by
5409C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> 5433C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING>
5410section. 5434section.
5411 5435
5412=item C<ev_default_destroy> and C<ev_default_fork> have been removed 5436=item C<ev_default_destroy> and C<ev_default_fork> have been removed
5413 5437
5414These calls can be replaced easily by their C<ev_loop_xxx> counterparts: 5438These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
5457=over 4 5481=over 4
5458 5482
5459=item active 5483=item active
5460 5484
5461A watcher is active as long as it has been started and not yet stopped. 5485A watcher is active as long as it has been started and not yet stopped.
5462See L<WATCHER STATES> for details. 5486See L</WATCHER STATES> for details.
5463 5487
5464=item application 5488=item application
5465 5489
5466In this document, an application is whatever is using libev. 5490In this document, an application is whatever is using libev.
5467 5491
5503watchers and events. 5527watchers and events.
5504 5528
5505=item pending 5529=item pending
5506 5530
5507A watcher is pending as soon as the corresponding event has been 5531A watcher is pending as soon as the corresponding event has been
5508detected. See L<WATCHER STATES> for details. 5532detected. See L</WATCHER STATES> for details.
5509 5533
5510=item real time 5534=item real time
5511 5535
5512The physical time that is observed. It is apparently strictly monotonic :) 5536The physical time that is observed. It is apparently strictly monotonic :)
5513 5537

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