[ViewVC] Diff of: cvs/EV/EV.pm

Comparing EV/EV.pm (file contents):
Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs.
Revision 1.46 by root, Fri Nov 23 05:00:44 2007 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	EV - perl interface to libevent, monkey.org/~provos/libevent/	3	EV - perl interface to libev, a high performance full-featured event loop
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use EV;	7	use EV;
8		8
9	# TIMER	9	# TIMERS
10		10
11	my $w = EV::timer 2, 0, sub {	11	my $w = EV::timer 2, 0, sub {
12	warn "is called after 2s";	12	warn "is called after 2s";
13	};	13	};
14		14
15	my $w = EV::timer 2, 1, sub {	15	my $w = EV::timer 2, 2, sub {
16	warn "is called roughly every 2s (repeat = 1)";	16	warn "is called roughly every 2s (repeat = 2)";
17	};	17	};
18		18
19	undef $w; # destroy event watcher again	19	undef $w; # destroy event watcher again
20		20
21	# IO
22
23	my $w = EV::timer_abs 0, 60, sub {	21	my $w = EV::periodic 0, 60, 0, sub {
24	warn "is called every minute, on the minute, exactly";	22	warn "is called every minute, on the minute, exactly";
25	};	23	};
26		24
		25	# IO
		26
27	my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {	27	my $w = EV::io *STDIN, EV::READ, sub {
28	my ($w, $events) = @_; # all callbacks get the watcher object and event mask	28	my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29	if ($events & EV::TIMEOUT) {
30	warn "nothing received on stdin for 10 seconds, retrying";
31	} else {
32	warn "stdin is readable, you entered: ", <STDIN>;	29	warn "stdin is readable, you entered: ", <STDIN>;
33	}
34	};	30	};
35	$w->timeout (10);	31
		32	# SIGNALS
		33
		34	my $w = EV::signal 'QUIT', sub {
		35	warn "sigquit received\n";
		36	};
		37
		38	# CHILD/PID STATUS CHANGES
36		39
		40	my $w = EV::child 666, sub {
		41	my ($w, $revents) = @_;
		42	my $status = $w->rstatus;
		43	};
		44
37	# MAINLOOP	45	# MAINLOOP
38	EV::dispatch; # loop as long as watchers are active	46	EV::loop; # loop until EV::unloop is called or all watchers stop
39	EV::loop; # the same thing	47	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
40	EV::loop EV::LOOP_ONCE;	48	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
41	EV::loop EV::LOOP_ONSHOT;
42		49
43	=head1 DESCRIPTION	50	=head1 DESCRIPTION
44		51
45	This module provides an interface to libevent	52	This module provides an interface to libev
46	(L<http://monkey.org/~provos/libevent/>). You probably should acquaint	53	(L<http://software.schmorp.de/pkg/libev.html>).
47	yourself with its documentation and source code to be able to use this
48	module fully.
49
50	Please note thta this module disables the libevent EPOLL method by
51	default, see BUGS, below, if you need to enable it.
52		54
53	=cut	55	=cut
54		56
55	package EV;	57	package EV;
56		58
57	use strict;	59	use strict;
58		60
59	BEGIN {	61	BEGIN {
60	our $VERSION = '0.02';	62	our $VERSION = '1.2';
61	use XSLoader;	63	use XSLoader;
62	XSLoader::load "EV", $VERSION;	64	XSLoader::load "EV", $VERSION;
63	}	65	}
64		66
		67	@EV::Io::ISA =
		68	@EV::Timer::ISA =
		69	@EV::Periodic::ISA =
		70	@EV::Signal::ISA =
		71	@EV::Idle::ISA =
		72	@EV::Prepare::ISA =
		73	@EV::Check::ISA =
		74	@EV::Child::ISA = "EV::Watcher";
		75
65	=head1 BASIC INTERFACE	76	=head1 BASIC INTERFACE
66		77
67	=over 4	78	=over 4
68
69	=item $EV::NPRI
70
71	How many priority levels are available.
72		79
73	=item $EV::DIED	80	=item $EV::DIED
74		81
75	Must contain a reference to a function that is called when a callback	82	Must contain a reference to a function that is called when a callback
76	throws an exception (with $@ containing thr error). The default prints an	83	throws an exception (with $@ containing thr error). The default prints an
77	informative message and continues.	84	informative message and continues.
78		85
79	If this callback throws an exception it will be silently ignored.	86	If this callback throws an exception it will be silently ignored.
80		87
		88	=item $time = EV::time
		89
		90	Returns the current time in (fractional) seconds since the epoch.
		91
81	=item $time = EV::now	92	=item $time = EV::now
82		93
83	Returns the time in (fractional) seconds since the epoch.	94	Returns the time the last event loop iteration has been started. This
84		95	is the time that (relative) timers are based on, and refering to it is
85	=item $version = EV::version	96	usually faster then calling EV::time.
86		97
87	=item $method = EV::method	98	=item $method = EV::method
88		99
89	Return version string and event polling method used.	100	Returns an integer describing the backend used by libev (EV::METHOD_SELECT
		101	or EV::METHOD_EPOLL).
90		102
91	=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT	103	=item EV::loop [$flags]
92		104
93	=item EV::loopexit $after	105	Begin checking for events and calling callbacks. It returns when a
		106	callback calls EV::unloop.
94		107
95	Exit any active loop or dispatch after C<$after> seconds or immediately if	108	The $flags argument can be one of the following:
96	C<$after> is missing or zero.
97		109
98	=item EV::dispatch	110	0 as above
		111	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
		112	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
99		113
100	Same as C<EV::loop 0>.	114	=item EV::unloop [$how]
101		115
102	=item EV::event $callback	116	When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
		117	innermost call to EV::loop return.
103		118
104	Creates a new event watcher waiting for nothing, calling the given callback.	119	When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
		120	fast as possible.
105		121
		122	=back
		123
		124	=head2 WATCHER
		125
		126	A watcher is an object that gets created to record your interest in some
		127	event. For instance, if you want to wait for STDIN to become readable, you
		128	would create an EV::io watcher for that:
		129
		130	my $watcher = EV::io *STDIN, EV::READ, sub {
		131	my ($watcher, $revents) = @_;
		132	warn "yeah, STDIN should not be readable without blocking!\n"
		133	};
		134
		135	All watchers can be active (waiting for events) or inactive (paused). Only
		136	active watchers will have their callbacks invoked. All callbacks will be
		137	called with at least two arguments: the watcher and a bitmask of received
		138	events.
		139
		140	Each watcher type has its associated bit in revents, so you can use the
		141	same callback for multiple watchers. The event mask is named after the
		142	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
		143	EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
		144	(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
		145	uses EV::TIMEOUT).
		146
		147	In the rare case where one wants to create a watcher but not start it at
		148	the same time, each constructor has a variant with a trailing C<_ns> in
		149	its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
		150
		151	Please note that a watcher will automatically be stopped when the watcher
		152	object is destroyed, so you I<need> to keep the watcher objects returned by
		153	the constructors.
		154
		155	Also, all methods changing some aspect of a watcher (->set, ->priority,
		156	->fh and so on) automatically stop and start it again if it is active,
		157	which means pending events get lost.
		158
		159	=head2 WATCHER TYPES
		160
		161	Now lets move to the existing watcher types and asociated methods.
		162
		163	The following methods are available for all watchers. Then followes a
		164	description of each watcher constructor (EV::io, EV::timer, EV::periodic,
		165	EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
		166	any type-specific methods (if any).
		167
		168	=over 4
		169
		170	=item $w->start
		171
		172	Starts a watcher if it isn't active already. Does nothing to an already
		173	active watcher. By default, all watchers start out in the active state
		174	(see the description of the C<_ns> variants if you need stopped watchers).
		175
		176	=item $w->stop
		177
		178	Stop a watcher if it is active. Also clear any pending events (events that
		179	have been received but that didn't yet result in a callback invocation),
		180	regardless of wether the watcher was active or not.
		181
		182	=item $bool = $w->is_active
		183
		184	Returns true if the watcher is active, false otherwise.
		185
		186	=item $current_data = $w->data
		187
		188	=item $old_data = $w->data ($new_data)
		189
		190	Queries a freely usable data scalar on the watcher and optionally changes
		191	it. This is a way to associate custom data with a watcher:
		192
		193	my $w = EV::timer 60, 0, sub {
		194	warn $_[0]->data;
		195	};
		196	$w->data ("print me!");
		197
		198	=item $current_cb = $w->cb
		199
		200	=item $old_cb = $w->cb ($new_cb)
		201
		202	Queries the callback on the watcher and optionally changes it. You can do
		203	this at any time without the watcher restarting.
		204
		205	=item $current_priority = $w->priority
		206
		207	=item $old_priority = $w->priority ($new_priority)
		208
		209	Queries the priority on the watcher and optionally changes it. Pending
		210	watchers with higher priority will be invoked first. The valid range of
		211	priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
		212	-2). If the priority is outside this range it will automatically be
		213	normalised to the nearest valid priority.
		214
		215	The default priority of any newly-created weatcher is 0.
		216
		217	=item $w->trigger ($revents)
		218
		219	Call the callback now with the given event mask.
		220
		221
106	=item my $w = EV::io $fileno_or_fh, $eventmask, $callback	222	=item $w = EV::io $fileno_or_fh, $eventmask, $callback
107		223
108	=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback	224	=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
109		225
110	As long as the returned watcher object is alive, call the C<$callback>	226	As long as the returned watcher object is alive, call the C<$callback>
111	when the events specified in C<$eventmask> happen. Initially, the timeout	227	when the events specified in C<$eventmask>.
112	is disabled.
113		228
114	You can additionall set a timeout to occur on the watcher, but note that
115	this timeout will not be reset when you get an I/O event in the EV::PERSIST
116	case, and reaching a timeout will always stop the watcher even in the
117	EV::PERSIST case.
118
119	If you want a timeout to occur only after a specific time of inactivity, set
120	a repeating timeout and do NOT use EV::PERSIST.
121
122	Eventmask can be one or more of these constants ORed together:	229	The $eventmask can be one or more of these constants ORed together:
123		230
124	EV::READ wait until read() wouldn't block anymore	231	EV::READ wait until read() wouldn't block anymore
125	EV::WRITE wait until write() wouldn't block anymore	232	EV::WRITE wait until write() wouldn't block anymore
126	EV::PERSIST stay active after a (non-timeout) event occured
127		233
128	The C<io_ns> variant doesn't add/start the newly created watcher.	234	The C<io_ns> variant doesn't start (activate) the newly created watcher.
129		235
130	=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback	236	=item $w->set ($fileno_or_fh, $eventmask)
131		237
132	=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback	238	Reconfigures the watcher, see the constructor above for details. Can be
		239	called at any time.
133		240
134	Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was	241	=item $current_fh = $w->fh
135	a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
136	and will automatically be cleared. The watcher will be restarted after each event.
137		242
138	If the timeout is zero or undef, no timeout will be set, and a normal	243	=item $old_fh = $w->fh ($new_fh)
139	watcher (with the persist flag set!) will be created.
140		244
141	This has the effect of timing out after the specified period of inactivity	245	Returns the previously set filehandle and optionally set a new one.
142	has happened.
143		246
144	Due to the design of libevent, this is also relatively inefficient, having	247	=item $current_eventmask = $w->events
145	one or two io watchers and a separate timeout watcher that you reset on
146	activity (by calling its C<start> method) is usually more efficient.
147		248
		249	=item $old_eventmask = $w->events ($new_eventmask)
		250
		251	Returns the previously set event mask and optionally set a new one.
		252
		253
148	=item my $w = EV::timer $after, $repeat, $callback	254	=item $w = EV::timer $after, $repeat, $callback
149		255
150	=item my $w = EV::timer_ns $after, $repeat, $callback	256	=item $w = EV::timer_ns $after, $repeat, $callback
151		257
152	Calls the callback after C<$after> seconds. If C<$repeat> is true, the	258	Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,
153	timer will be restarted after the callback returns. This means that the	259	the timer will be restarted (with the $repeat value as $after) after the
154	callback would be called roughly every C<$after> seconds, prolonged by the	260	callback returns.
155	time the callback takes.
156		261
		262	This means that the callback would be called roughly after C<$after>
		263	seconds, and then every C<$repeat> seconds. The timer does his best not
		264	to drift, but it will not invoke the timer more often then once per event
		265	loop iteration, and might drift in other cases. If that isn't acceptable,
		266	look at EV::periodic, which can provide long-term stable timers.
		267
		268	The timer is based on a monotonic clock, that is, if somebody is sitting
		269	in front of the machine while the timer is running and changes the system
		270	clock, the timer will nevertheless run (roughly) the same time.
		271
157	The C<timer_ns> variant doesn't add/start the newly created watcher.	272	The C<timer_ns> variant doesn't start (activate) the newly created watcher.
158		273
159	=item my $w = EV::timer_abs $at, $interval, $callback	274	=item $w->set ($after, $repeat)
160		275
161	=item my $w = EV::timer_abs_ns $at, $interval, $callback	276	Reconfigures the watcher, see the constructor above for details. Can be at
		277	any time.
162		278
163	Similar to EV::timer, but the time is given as an absolute point in time	279	=item $w->again
164	(C<$at>), plus an optional C<$interval>.
165		280
166	If the C<$interval> is zero, then the callback will be called at the time	281	Similar to the C<start> method, but has special semantics for repeating timers:
167	C<$at> if that is in the future, or as soon as possible if its in the
168	past. It will not automatically repeat.
169		282
170	If the C<$interval> is nonzero, then the watcher will always be scheduled	283	If the timer is active and non-repeating, it will be stopped.
171	to time out at the next C<$at + integer * $interval> time.
172		284
173	This can be used to schedule a callback to run at very regular intervals,	285	If the timer is active and repeating, reset the timeout to occur
174	as long as the processing time is less then the interval (otherwise	286	C<$repeat> seconds after now.
175	obviously events will be skipped).	287
		288	If the timer is inactive and repeating, start it using the repeat value.
		289
		290	Otherwise do nothing.
		291
		292	This behaviour is useful when you have a timeout for some IO
		293	operation. You create a timer object with the same value for C<$after> and
		294	C<$repeat>, and then, in the read/write watcher, run the C<again> method
		295	on the timeout.
		296
		297
		298	=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
		299
		300	=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		301
		302	Similar to EV::timer, but is not based on relative timeouts but on
		303	absolute times. Apart from creating "simple" timers that trigger "at" the
		304	specified time, it can also be used for non-drifting absolute timers and
		305	more complex, cron-like, setups that are not adversely affected by time
		306	jumps (i.e. when the system clock is changed by explicit date -s or other
		307	means such as ntpd). It is also the most complex watcher type in EV.
		308
		309	It has three distinct "modes":
		310
		311	=over 4
		312
		313	=item * absolute timer ($interval = $reschedule_cb = 0)
		314
		315	This time simply fires at the wallclock time C<$at> and doesn't repeat. It
		316	will not adjust when a time jump occurs, that is, if it is to be run
		317	at January 1st 2011 then it will run when the system time reaches or
		318	surpasses this time.
		319
		320	=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0)
		321
		322	In this mode the watcher will always be scheduled to time out at the
		323	next C<$at + N * $interval> time (for some integer N) and then repeat,
		324	regardless of any time jumps.
		325
		326	This can be used to create timers that do not drift with respect to system
		327	time:
		328
		329	my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
		330
		331	That doesn't mean there will always be 3600 seconds in between triggers,
		332	but only that the the clalback will be called when the system time shows a
		333	full hour (UTC).
176		334
177	Another way to think about it (for the mathematically inclined) is that	335	Another way to think about it (for the mathematically inclined) is that
178	C<timer_abs> will try to tun the callback at the next possible time where	336	EV::periodic will try to run the callback in this mode at the next
179	C<$time = $at (mod $interval)>, regardless of any time jumps.	337	possible time where C<$time = $at (mod $interval)>, regardless of any time
		338	jumps.
180		339
181	The C<timer_abs_ns> variant doesn't add/start the newly created watcher.	340	=item * manual reschedule mode ($reschedule_cb = coderef)
182		341
183	=item my $w = EV::signal $signum, $callback	342	In this mode $interval and $at are both being ignored. Instead, each
		343	time the periodic watcher gets scheduled, the reschedule callback
		344	($reschedule_cb) will be called with the watcher as first, and the current
		345	time as second argument.
184		346
185	=item my $w = EV::signal_ns $signum, $callback	347	I<This callback MUST NOT stop or destroy this or any other periodic
		348	watcher, ever>. If you need to stop it, return 1e30 and stop it
		349	afterwards.
186		350
187	Call the callback when signal $signum is received.	351	It must return the next time to trigger, based on the passed time value
		352	(that is, the lowest time value larger than to the second argument). It
		353	will usually be called just before the callback will be triggered, but
		354	might be called at other times, too.
188		355
189	The C<signal_ns> variant doesn't add/start the newly created watcher.	356	This can be used to create very complex timers, such as a timer that
		357	triggers on each midnight, local time (actually 24 hours after the last
		358	midnight, to keep the example simple. If you know a way to do it correctly
		359	in about the same space (without requiring elaborate modules), drop me a
		360	note :):
		361
		362	my $daily = EV::periodic 0, 0, sub {
		363	my ($w, $now) = @_;
		364
		365	use Time::Local ();
		366	my (undef, undef, undef, $d, $m, $y) = localtime $now;
		367	86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
		368	}, sub {
		369	print "it's midnight or likely shortly after, now\n";
		370	};
190		371
191	=back	372	=back
192		373
193	=head1 THE EV::Event CLASS	374	The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
194		375
195	All EV functions creating an event watcher (designated by C<my $w =>	376	=item $w->set ($at, $interval, $reschedule_cb)
196	above) support the following methods on the returned watcher object:
197		377
198	=over 4	378	Reconfigures the watcher, see the constructor above for details. Can be at
		379	any time.
199		380
200	=item $w->add ($timeout)	381	=item $w->again
201		382
202	Stops and (re-)starts the event watcher, setting the optional timeout to	383	Simply stops and starts the watcher again.
203	the given value, or clearing the timeout if none is given.
204		384
205	=item $w->start
206		385
207	Stops and (re-)starts the event watcher without touching the timeout.	386	=item $w = EV::signal $signal, $callback
208		387
209	=item $w->del	388	=item $w = EV::signal_ns $signal, $callback
210		389
211	=item $w->stop	390	Call the callback when $signal is received (the signal can be specified
		391	by number or by name, just as with kill or %SIG).
212		392
213	Stop the event watcher if it was started.	393	EV will grab the signal for the process (the kernel only allows one
		394	component to receive a signal at a time) when you start a signal watcher,
		395	and removes it again when you stop it. Perl does the same when you
		396	add/remove callbacks to %SIG, so watch out.
214		397
215	=item $current_callback = $w->cb	398	You can have as many signal watchers per signal as you want.
216		399
217	=item $old_callback = $w->cb ($new_callback)	400	The C<signal_ns> variant doesn't start (activate) the newly created watcher.
218		401
219	Return the previously set callback and optionally set a new one.	402	=item $w->set ($signal)
220		403
221	=item $current_fh = $w->fh	404	Reconfigures the watcher, see the constructor above for details. Can be at
		405	any time.
222		406
223	=item $old_fh = $w->fh ($new_fh)
224
225	Returns the previously set filehandle and optionally set a new one (also
226	clears the EV::SIGNAL flag when setting a filehandle).
227
228	=item $current_signal = $w->signal	407	=item $current_signum = $w->signal
229		408
230	=item $old_signal = $w->signal ($new_signal)	409	=item $old_signum = $w->signal ($new_signal)
231		410
232	Returns the previously set signal number and optionally set a new one (also sets	411	Returns the previously set signal (always as a number not name) and
233	the EV::SIGNAL flag when setting a signal).	412	optionally set a new one.
234		413
235	=item $current_eventmask = $w->events
236		414
237	=item $old_eventmask = $w->events ($new_eventmask)	415	=item $w = EV::child $pid, $callback
238		416
		417	=item $w = EV::child_ns $pid, $callback
		418
		419	Call the callback when a status change for pid C<$pid> (or any pid
		420	if C<$pid> is 0) has been received. More precisely: when the process
		421	receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
		422	changed/zombie children and call the callback.
		423
		424	You can access both status and pid by using the C<rstatus> and C<rpid>
		425	methods on the watcher object.
		426
		427	You can have as many pid watchers per pid as you want.
		428
		429	The C<child_ns> variant doesn't start (activate) the newly created watcher.
		430
		431	=item $w->set ($pid)
		432
		433	Reconfigures the watcher, see the constructor above for details. Can be at
		434	any time.
		435
		436	=item $current_pid = $w->pid
		437
		438	=item $old_pid = $w->pid ($new_pid)
		439
239	Returns the previously set event mask and optionally set a new one.	440	Returns the previously set process id and optionally set a new one.
240		441
241	=item $w->timeout ($after, $repeat)	442	=item $exit_status = $w->rstatus
242		443
243	Resets the timeout (see C<EV::timer> for details).	444	Return the exit/wait status (as returned by waitpid, see the waitpid entry
		445	in perlfunc).
244		446
245	=item $w->timeout_abs ($at, $interval)	447	=item $pid = $w->rpid
246		448
247	Resets the timeout (see C<EV::timer_abs> for details).	449	Return the pid of the awaited child (useful when you have installed a
		450	watcher for all pids).
248		451
249	=item $w->priority_set ($priority)
250		452
251	Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).	453	=item $w = EV::idle $callback
		454
		455	=item $w = EV::idle_ns $callback
		456
		457	Call the callback when there are no pending io, timer/periodic, signal or
		458	child events, i.e. when the process is idle.
		459
		460	The process will not block as long as any idle watchers are active, and
		461	they will be called repeatedly until stopped.
		462
		463	The C<idle_ns> variant doesn't start (activate) the newly created watcher.
		464
		465
		466	=item $w = EV::prepare $callback
		467
		468	=item $w = EV::prepare_ns $callback
		469
		470	Call the callback just before the process would block. You can still
		471	create/modify any watchers at this point.
		472
		473	See the EV::check watcher, below, for explanations and an example.
		474
		475	The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
		476
		477
		478	=item $w = EV::check $callback
		479
		480	=item $w = EV::check_ns $callback
		481
		482	Call the callback just after the process wakes up again (after it has
		483	gathered events), but before any other callbacks have been invoked.
		484
		485	This is used to integrate other event-based software into the EV
		486	mainloop: You register a prepare callback and in there, you create io and
		487	timer watchers as required by the other software. Here is a real-world
		488	example of integrating Net::SNMP (with some details left out):
		489
		490	our @snmp_watcher;
		491
		492	our $snmp_prepare = EV::prepare sub {
		493	# do nothing unless active
		494	$dispatcher->{_event_queue_h}
		495	or return;
		496
		497	# make the dispatcher handle any outstanding stuff
		498	... not shown
		499
		500	# create an IO watcher for each and every socket
		501	@snmp_watcher = (
		502	(map { EV::io $_, EV::READ, sub { } }
		503	keys %{ $dispatcher->{_descriptors} }),
		504
		505	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		506	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		507	0, sub { },
		508	);
		509	};
		510
		511	The callbacks are irrelevant (and are not even being called), the
		512	only purpose of those watchers is to wake up the process as soon as
		513	one of those events occurs (socket readable, or timer timed out). The
		514	corresponding EV::check watcher will then clean up:
		515
		516	our $snmp_check = EV::check sub {
		517	# destroy all watchers
		518	@snmp_watcher = ();
		519
		520	# make the dispatcher handle any new stuff
		521	... not shown
		522	};
		523
		524	The callbacks of the created watchers will not be called as the watchers
		525	are destroyed before this cna happen (remember EV::check gets called
		526	first).
		527
		528	The C<check_ns> variant doesn't start (activate) the newly created watcher.
252		529
253	=back	530	=back
254		531
255	=head1 BUGS	532	=head1 THREADS
256		533
257	Lots. Libevent itself isn't well tested and rather buggy, and this module	534	Threads are not supported by this module in any way. Perl pseudo-threads
258	is quite new at the moment.	535	is evil stuff and must die. As soon as Perl gains real threads I will work
		536	on thread support for it.
259		537
260	Please note that the epoll method is not, in general, reliable in programs	538	=head1 FORK
261	that use fork (even if no libveent calls are being made in the forked
262	process). If your program behaves erratically, try setting the environment
263	variable C<EVENT_NOEPOLL> first when running the program.
264		539
265	In general, if you fork, then you can only use the EV module in one of the	540	Most of the "improved" event delivering mechanisms of modern operating
266	children.	541	systems have quite a few problems with fork(2) (to put it bluntly: it is
		542	not supported and usually destructive). Libev makes it possible to work
		543	around this by having a function that recreates the kernel state after
		544	fork in the child.
		545
		546	On non-win32 platforms, this module requires the pthread_atfork
		547	functionality to do this automatically for you. This function is quite
		548	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		549	negligible, because everything the function currently does is set a flag
		550	that is checked only when the event loop gets used the next time, so when
		551	you do fork but not use EV, the overhead is minimal.
		552
		553	On win32, there is no notion of fork so all this doesn't apply, of course.
267		554
268	=cut	555	=cut
269		556
270	our $DIED = sub {	557	our $DIED = sub {
271	warn "EV: error in callback (ignoring): $@";	558	warn "EV: error in callback (ignoring): $@";
272	};	559	};
273		560
274	our $NPRI = 4;	561	default_loop
275	our $BASE = init;	562	or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
276	priority_init $NPRI;
277
278	push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
279		563
280	1;	564	1;
281		565
282	=head1 SEE ALSO	566	=head1 SEE ALSO
283		567
284	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.	568	L<EV::DNS>.
285	L<EV::AnyEvent>.
286		569
287	=head1 AUTHOR	570	=head1 AUTHOR
288		571
289	Marc Lehmann <schmorp@schmorp.de>	572	Marc Lehmann <schmorp@schmorp.de>
290	http://home.schmorp.de/	573	http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing EV/EV.pm (file contents): Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs. Revision 1.46 by root, Fri Nov 23 05:00:44 2007 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.10 by root, Mon Oct 29 07:24:37 2007 UTC vs.
Revision 1.46 by root, Fri Nov 23 05:00:44 2007 UTC