[ViewVC] Diff of: cvs/EV/README

Comparing EV/README (file contents):
Revision 1.10 by root, Wed Nov 14 21:25:46 2007 UTC vs.
Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC

…		…
38		38
39	my $w = EV::child 666, sub {	39	my $w = EV::child 666, sub {
40	my ($w, $revents) = @_;	40	my ($w, $revents) = @_;
41	my $status = $w->rstatus;	41	my $status = $w->rstatus;
42	};	42	};
		43
		44	# STAT CHANGES
		45	my $w = EV::stat "/etc/passwd", 10, sub {
		46	my ($w, $revents) = @_;
		47	warn $w->path, " has changed somehow.\n";
		48	};
43		49
44	# MAINLOOP	50	# MAINLOOP
45	EV::loop; # loop until EV::unloop is called or all watchers stop	51	EV::loop; # loop until EV::unloop is called or all watchers stop
46	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled	52	EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
47	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block	53	EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
48		54
49	DESCRIPTION	55	DESCRIPTION
50	This module provides an interface to libev	56	This module provides an interface to libev
51	(<http://software.schmorp.de/pkg/libev.html>).	57	(<http://software.schmorp.de/pkg/libev.html>). While the documentation
		58	below is comprehensive, one might also consult the documentation of
		59	libev itself (<http://cvs.schmorp.de/libev/ev.html>) for more subtle
		60	details on watcher semantics or some discussion on the available
		61	backends, or how to force a specific backend with "LIBEV_FLAGS", or just
		62	about in any case because it has much more detailed information.
		63
		64	EVENT LOOPS
		65	EV supports multiple event loops: There is a single "default event loop"
		66	that can handle everything including signals and child watchers, and any
		67	number of "dynamic event loops" that can use different backends (with
		68	various limitations), but no child and signal watchers.
		69
		70	You do not have to do anything to create the default event loop: When
		71	the module is loaded a suitable backend is selected on the premise of
		72	selecting a working backend (which for example rules out kqueue on most
		73	BSDs). Modules should, unless they have "special needs" always use the
		74	default loop as this is fastest (perl-wise), best supported by other
		75	modules (e.g. AnyEvent or Coro) and most portable event loop.
		76
		77	For specific programs you cna create additional event loops dynamically.
		78
		79	$loop = new EV::loop [$flags]
		80	Create a new event loop as per the specified flags. Please refer to
		81	the "ev_loop_new ()" function description in the libev documentation
		82	(<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI
		83	ONS>) for more info.
		84
		85	The loop will automatically be destroyed when it is no longer
		86	referenced by any watcher and the loop object goes out of scope.
		87
		88	Using "EV::FLAG_FORKCHECK" is recommended, as only the default event
		89	loop is protected by this module.
		90
		91	$loop->loop_fork
		92	Must be called after a fork in the child, before entering or
		93	continuing the event loop. An alternative is to use
		94	"EV::FLAG_FORKCHECK" which calls this fucntion automatically, at
		95	some performance loss (refer to the libev documentation).
52		96
53	BASIC INTERFACE	97	BASIC INTERFACE
54	$EV::DIED	98	$EV::DIED
55	Must contain a reference to a function that is called when a	99	Must contain a reference to a function that is called when a
56	callback throws an exception (with $@ containing thr error). The	100	callback throws an exception (with $@ containing the error). The
57	default prints an informative message and continues.	101	default prints an informative message and continues.
58		102
59	If this callback throws an exception it will be silently ignored.	103	If this callback throws an exception it will be silently ignored.
60		104
61	$time = EV::time	105	$time = EV::time
62	Returns the current time in (fractional) seconds since the epoch.	106	Returns the current time in (fractional) seconds since the epoch.
63		107
64	$time = EV::now	108	$time = EV::now
		109	$time = $loop->now
65	Returns the time the last event loop iteration has been started.	110	Returns the time the last event loop iteration has been started.
66	This is the time that (relative) timers are based on, and refering	111	This is the time that (relative) timers are based on, and refering
67	to it is usually faster then calling EV::time.	112	to it is usually faster then calling EV::time.
68		113
69	$method = EV::ev_method	114	$backend = EV::backend
		115	$backend = $loop->backend
70	Returns an integer describing the backend used by libev	116	Returns an integer describing the backend used by libev
71	(EV::METHOD_SELECT or EV::METHOD_EPOLL).	117	(EV::METHOD_SELECT or EV::METHOD_EPOLL).
72		118
73	EV::loop [$flags]	119	EV::loop [$flags]
		120	$loop->loop ([$flags])
74	Begin checking for events and calling callbacks. It returns when a	121	Begin checking for events and calling callbacks. It returns when a
75	callback calls EV::unloop.	122	callback calls EV::unloop.
76		123
77	The $flags argument can be one of the following:	124	The $flags argument can be one of the following:
78		125
79	0 as above	126	0 as above
80	EV::LOOP_ONESHOT block at most once (wait, but do not loop)	127	EV::LOOP_ONESHOT block at most once (wait, but do not loop)
81	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)	128	EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
82		129
83	EV::unloop [$how]	130	EV::unloop [$how]
		131	$loop->unloop ([$how])
84	When called with no arguments or an argument of EV::UNLOOP_ONE,	132	When called with no arguments or an argument of EV::UNLOOP_ONE,
85	makes the innermost call to EV::loop return.	133	makes the innermost call to EV::loop return.
86		134
87	When called with an argument of EV::UNLOOP_ALL, all calls to	135	When called with an argument of EV::UNLOOP_ALL, all calls to
88	EV::loop will return as fast as possible.	136	EV::loop will return as fast as possible.
89		137
90	WATCHER	138	$count = EV::loop_count
		139	$count = $loop->loop_count
		140	Return the number of times the event loop has polled for new events.
		141	Sometiems useful as a generation counter.
		142
		143	EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
		144	$loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
		145	This function rolls together an I/O and a timer watcher for a single
		146	one-shot event without the need for managing a watcher object.
		147
		148	If $fh_or_undef is a filehandle or file descriptor, then $events
		149	must be a bitset containing either "EV::READ", "EV::WRITE" or
		150	"EV::READ \| EV::WRITE", indicating the type of I/O event you want to
		151	wait for. If you do not want to wait for some I/O event, specify
		152	"undef" for $fh_or_undef and 0 for $events).
		153
		154	If timeout is "undef" or negative, then there will be no timeout.
		155	Otherwise a EV::timer with this value will be started.
		156
		157	When an error occurs or either the timeout or I/O watcher triggers,
		158	then the callback will be called with the received event set (in
		159	general you can expect it to be a combination of "EV::ERROR",
		160	"EV::READ", "EV::WRITE" and "EV::TIMEOUT").
		161
		162	EV::once doesn't return anything: the watchers stay active till
		163	either of them triggers, then they will be stopped and freed, and
		164	the callback invoked.
		165
		166	EV::feed_fd_event ($fd, $revents)
		167	$loop->feed_fd_event ($fd, $revents)
		168	Feed an event on a file descriptor into EV. EV will react to this
		169	call as if the readyness notifications specified by $revents (a
		170	combination of "EV::READ" and "EV::WRITE") happened on the file
		171	descriptor $fd.
		172
		173	EV::feed_signal_event ($signal)
		174	Feed a signal event into EV. EV will react to this call as if the
		175	signal specified by $signal had occured.
		176
		177	WATCHER OBJECTS
91	A watcher is an object that gets created to record your interest in some	178	A watcher is an object that gets created to record your interest in some
92	event. For instance, if you want to wait for STDIN to become readable,	179	event. For instance, if you want to wait for STDIN to become readable,
93	you would create an EV::io watcher for that:	180	you would create an EV::io watcher for that:
94		181
95	my $watcher = EV::io *STDIN, EV::READ, sub {	182	my $watcher = EV::io *STDIN, EV::READ, sub {
96	my ($watcher, $revents) = @_;	183	my ($watcher, $revents) = @_;
97	warn "yeah, STDIN should not be readable without blocking!\n"	184	warn "yeah, STDIN should now be readable without blocking!\n"
98	};	185	};
99		186
100	All watchers can be active (waiting for events) or inactive (paused).	187	All watchers can be active (waiting for events) or inactive (paused).
101	Only active watchers will have their callbacks invoked. All callbacks	188	Only active watchers will have their callbacks invoked. All callbacks
102	will be called with at least two arguments: the watcher and a bitmask of	189	will be called with at least two arguments: the watcher and a bitmask of
103	received events.	190	received events.
104		191
105	Each watcher type has its associated bit in revents, so you can use the	192	Each watcher type has its associated bit in revents, so you can use the
106	same callback for multiple watchers. The event mask is named after the	193	same callback for multiple watchers. The event mask is named after the
107	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,	194	type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
108	EV::periodic sets EV::PERIODIC and so on, with the exception of IO	195	EV::periodic sets EV::PERIODIC and so on, with the exception of I/O
109	events (which can set both EV::READ and EV::WRITE bits), and EV::timer	196	events (which can set both EV::READ and EV::WRITE bits), and EV::timer
110	(which uses EV::TIMEOUT).	197	(which uses EV::TIMEOUT).
111		198
112	In the rare case where one wants to create a watcher but not start it at	199	In the rare case where one wants to create a watcher but not start it at
113	the same time, each constructor has a variant with a trailing "_ns" in	200	the same time, each constructor has a variant with a trailing "_ns" in
…		…
119		206
120	Also, all methods changing some aspect of a watcher (->set, ->priority,	207	Also, all methods changing some aspect of a watcher (->set, ->priority,
121	->fh and so on) automatically stop and start it again if it is active,	208	->fh and so on) automatically stop and start it again if it is active,
122	which means pending events get lost.	209	which means pending events get lost.
123		210
124	WATCHER TYPES	211	COMMON WATCHER METHODS
125	Now lets move to the existing watcher types and asociated methods.	212	This section lists methods common to all watchers.
126
127	The following methods are available for all watchers. Then followes a
128	description of each watcher constructor (EV::io, EV::timer,
129	EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and
130	EV::check), followed by any type-specific methods (if any).
131		213
132	$w->start	214	$w->start
133	Starts a watcher if it isn't active already. Does nothing to an	215	Starts a watcher if it isn't active already. Does nothing to an
134	already active watcher. By default, all watchers start out in the	216	already active watcher. By default, all watchers start out in the
135	active state (see the description of the "_ns" variants if you need	217	active state (see the description of the "_ns" variants if you need
136	stopped watchers).	218	stopped watchers).
137		219
138	$w->stop	220	$w->stop
139	Stop a watcher if it is active. Also clear any pending events	221	Stop a watcher if it is active. Also clear any pending events
140	(events that have been received but that didn't yet result in a	222	(events that have been received but that didn't yet result in a
141	callback invocation), regardless of wether the watcher was active or	223	callback invocation), regardless of whether the watcher was active
142	not.	224	or not.
143		225
144	$bool = $w->is_active	226	$bool = $w->is_active
145	Returns true if the watcher is active, false otherwise.	227	Returns true if the watcher is active, false otherwise.
146		228
147	$current_data = $w->data	229	$current_data = $w->data
…		…
165	Pending watchers with higher priority will be invoked first. The	247	Pending watchers with higher priority will be invoked first. The
166	valid range of priorities lies between EV::MAXPRI (default 2) and	248	valid range of priorities lies between EV::MAXPRI (default 2) and
167	EV::MINPRI (default -2). If the priority is outside this range it	249	EV::MINPRI (default -2). If the priority is outside this range it
168	will automatically be normalised to the nearest valid priority.	250	will automatically be normalised to the nearest valid priority.
169		251
170	The default priority of any newly-created weatcher is 0.	252	The default priority of any newly-created watcher is 0.
171		253
		254	Note that the priority semantics have not yet been fleshed out and
		255	are subject to almost certain change.
		256
172	$w->trigger ($revents)	257	$w->invoke ($revents)
173	Call the callback now with the given event mask.	258	Call the callback now with the given event mask.
174		259
		260	$w->feed_event ($revents)
		261	Feed some events on this watcher into EV. EV will react to this call
		262	as if the watcher had received the given $revents mask.
		263
		264	$revents = $w->clear_pending
		265	If the watcher is pending, this function clears its pending status
		266	and returns its $revents bitset (as if its callback was invoked). If
		267	the watcher isn't pending it does nothing and returns 0.
		268
		269	$previous_state = $w->keepalive ($bool)
		270	Normally, "EV::loop" will return when there are no active watchers
		271	(which is a "deadlock" because no progress can be made anymore).
		272	This is convinient because it allows you to start your watchers (and
		273	your jobs), call "EV::loop" once and when it returns you know that
		274	all your jobs are finished (or they forgot to register some watchers
		275	for their task :).
		276
		277	Sometimes, however, this gets in your way, for example when the
		278	module that calls "EV::loop" (usually the main program) is not the
		279	same module as a long-living watcher (for example a DNS client
		280	module written by somebody else even). Then you might want any
		281	outstanding requests to be handled, but you would not want to keep
		282	"EV::loop" from returning just because you happen to have this
		283	long-running UDP port watcher.
		284
		285	In this case you can clear the keepalive status, which means that
		286	even though your watcher is active, it won't keep "EV::loop" from
		287	returning.
		288
		289	The initial value for keepalive is true (enabled), and you cna
		290	change it any time.
		291
		292	Example: Register an I/O watcher for some UDP socket but do not keep
		293	the event loop from running just because of that watcher.
		294
		295	my $udp_socket = ...
		296	my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
		297	$1000udp_watcher->keepalive (0);
		298
		299	$loop = $w->loop
		300	Return the loop that this watcher is attached to.
		301
		302	WATCHER TYPES
		303	Each of the following subsections describes a single watcher type.
		304
		305	I/O WATCHERS - is this file descriptor readable or writable?
175	$w = EV::io $fileno_or_fh, $eventmask, $callback	306	$w = EV::io $fileno_or_fh, $eventmask, $callback
176	$w = EV::io_ns $fileno_or_fh, $eventmask, $callback	307	$w = EV::io_ns $fileno_or_fh, $eventmask, $callback
		308	$w = $loop->io ($fileno_or_fh, $eventmask, $callback)
		309	$w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
177	As long as the returned watcher object is alive, call the $callback	310	As long as the returned watcher object is alive, call the $callback
178	when the events specified in $eventmask.	311	when at least one of events specified in $eventmask occurs.
179		312
180	The $eventmask can be one or more of these constants ORed together:	313	The $eventmask can be one or more of these constants ORed together:
181		314
182	EV::READ wait until read() wouldn't block anymore	315	EV::READ wait until read() wouldn't block anymore
183	EV::WRITE wait until write() wouldn't block anymore	316	EV::WRITE wait until write() wouldn't block anymore
…		…
195		328
196	$current_eventmask = $w->events	329	$current_eventmask = $w->events
197	$old_eventmask = $w->events ($new_eventmask)	330	$old_eventmask = $w->events ($new_eventmask)
198	Returns the previously set event mask and optionally set a new one.	331	Returns the previously set event mask and optionally set a new one.
199		332
		333	TIMER WATCHERS - relative and optionally repeating timeouts
200	$w = EV::timer $after, $repeat, $callback	334	$w = EV::timer $after, $repeat, $callback
201	$w = EV::timer_ns $after, $repeat, $callback	335	$w = EV::timer_ns $after, $repeat, $callback
202	Calls the callback after $after seconds. If $repeat is non-zero, the	336	$w = $loop->timer ($after, $repeat, $callback)
203	timer will be restarted (with the $repeat value as $after) after the	337	$w = $loop->timer_ns ($after, $repeat, $callback)
204	callback returns.	338	Calls the callback after $after seconds (which may be fractional).
		339	If $repeat is non-zero, the timer will be restarted (with the
		340	$repeat value as $after) after the callback returns.
205		341
206	This means that the callback would be called roughly after $after	342	This means that the callback would be called roughly after $after
207	seconds, and then every $repeat seconds. The timer does his best not	343	seconds, and then every $repeat seconds. The timer does his best not
208	to drift, but it will not invoke the timer more often then once per	344	to drift, but it will not invoke the timer more often then once per
209	event loop iteration, and might drift in other cases. If that isn't	345	event loop iteration, and might drift in other cases. If that isn't
…		…
218	The "timer_ns" variant doesn't start (activate) the newly created	354	The "timer_ns" variant doesn't start (activate) the newly created
219	watcher.	355	watcher.
220		356
221	$w->set ($after, $repeat)	357	$w->set ($after, $repeat)
222	Reconfigures the watcher, see the constructor above for details. Can	358	Reconfigures the watcher, see the constructor above for details. Can
223	be at any time.	359	be called at any time.
224		360
225	$w->again	361	$w->again
226	Similar to the "start" method, but has special semantics for	362	Similar to the "start" method, but has special semantics for
227	repeating timers:	363	repeating timers:
228		364
…		…
239	This behaviour is useful when you have a timeout for some IO	375	This behaviour is useful when you have a timeout for some IO
240	operation. You create a timer object with the same value for $after	376	operation. You create a timer object with the same value for $after
241	and $repeat, and then, in the read/write watcher, run the "again"	377	and $repeat, and then, in the read/write watcher, run the "again"
242	method on the timeout.	378	method on the timeout.
243		379
		380	PERIODIC WATCHERS - to cron or not to cron?
244	$w = EV::periodic $at, $interval, $reschedule_cb, $callback	381	$w = EV::periodic $at, $interval, $reschedule_cb, $callback
245	$w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback	382	$w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
		383	$w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
		384	$w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
246	Similar to EV::timer, but is not based on relative timeouts but on	385	Similar to EV::timer, but is not based on relative timeouts but on
247	absolute times. Apart from creating "simple" timers that trigger	386	absolute times. Apart from creating "simple" timers that trigger
248	"at" the specified time, it can also be used for non-drifting	387	"at" the specified time, it can also be used for non-drifting
249	absolute timers and more complex, cron-like, setups that are not	388	absolute timers and more complex, cron-like, setups that are not
250	adversely affected by time jumps (i.e. when the system clock is	389	adversely affected by time jumps (i.e. when the system clock is
…		…
313	The "periodic_ns" variant doesn't start (activate) the newly created	452	The "periodic_ns" variant doesn't start (activate) the newly created
314	watcher.	453	watcher.
315		454
316	$w->set ($at, $interval, $reschedule_cb)	455	$w->set ($at, $interval, $reschedule_cb)
317	Reconfigures the watcher, see the constructor above for details. Can	456	Reconfigures the watcher, see the constructor above for details. Can
318	be at any time.	457	be called at any time.
319		458
320	$w->again	459	$w->again
321	Simply stops and starts the watcher again.	460	Simply stops and starts the watcher again.
322		461
		462	$time = $w->at
		463	Return the time that the watcher is expected to trigger next.
		464
		465	SIGNAL WATCHERS - signal me when a signal gets signalled!
323	$w = EV::signal $signal, $callback	466	$w = EV::signal $signal, $callback
324	$w = EV::signal_ns $signal, $callback	467	$w = EV::signal_ns $signal, $callback
325	Call the callback when $signal is received (the signal can be	468	Call the callback when $signal is received (the signal can be
326	specified by number or by name, just as with kill or %SIG).	469	specified by number or by name, just as with "kill" or %SIG).
327		470
328	EV will grab the signal for the process (the kernel only allows one	471	EV will grab the signal for the process (the kernel only allows one
329	component to receive a signal at a time) when you start a signal	472	component to receive a signal at a time) when you start a signal
330	watcher, and removes it again when you stop it. Perl does the same	473	watcher, and removes it again when you stop it. Perl does the same
331	when you add/remove callbacks to %SIG, so watch out.	474	when you add/remove callbacks to %SIG, so watch out.
…		…
335	The "signal_ns" variant doesn't start (activate) the newly created	478	The "signal_ns" variant doesn't start (activate) the newly created
336	watcher.	479	watcher.
337		480
338	$w->set ($signal)	481	$w->set ($signal)
339	Reconfigures the watcher, see the constructor above for details. Can	482	Reconfigures the watcher, see the constructor above for details. Can
340	be at any time.	483	be called at any time.
341		484
342	$current_signum = $w->signal	485	$current_signum = $w->signal
343	$old_signum = $w->signal ($new_signal)	486	$old_signum = $w->signal ($new_signal)
344	Returns the previously set signal (always as a number not name) and	487	Returns the previously set signal (always as a number not name) and
345	optionally set a new one.	488	optionally set a new one.
346		489
		490	CHILD WATCHERS - watch out for process status changes
347	$w = EV::child $pid, $callback	491	$w = EV::child $pid, $callback
348	$w = EV::child_ns $pid, $callback	492	$w = EV::child_ns $pid, $callback
		493	$w = $loop->child ($pid, $callback)
		494	$w = $loop->child_ns ($pid, $callback)
349	Call the callback when a status change for pid $pid (or any pid if	495	Call the callback when a status change for pid $pid (or any pid if
350	$pid is 0) has been received. More precisely: when the process	496	$pid is 0) has been received. More precisely: when the process
351	receives a SIGCHLD, EV will fetch the outstanding exit/wait status	497	receives a "SIGCHLD", EV will fetch the outstanding exit/wait status
352	for all changed/zombie children and call the callback.	498	for all changed/zombie children and call the callback.
353		499
354	You can access both status and pid by using the "rstatus" and "rpid"	500	It is valid (and fully supported) to install a child watcher after a
		501	child has exited but before the event loop has started its next
		502	iteration (for example, first you "fork", then the new child process
		503	might exit, and only then do you install a child watcher in the
		504	parent for the new pid).
		505
		506	You can access both exit (or tracing) status and pid by using the
355	methods on the watcher object.	507	"rstatus" and "rpid" methods on the watcher object.
356		508
357	You can have as many pid watchers per pid as you want.	509	You can have as many pid watchers per pid as you want, they will all
		510	be called.
358		511
359	The "child_ns" variant doesn't start (activate) the newly created	512	The "child_ns" variant doesn't start (activate) the newly created
360	watcher.	513	watcher.
361		514
362	$w->set ($pid)	515	$w->set ($pid)
363	Reconfigures the watcher, see the constructor above for details. Can	516	Reconfigures the watcher, see the constructor above for details. Can
364	be at any time.	517	be called at any time.
365		518
366	$current_pid = $w->pid	519	$current_pid = $w->pid
367	$old_pid = $w->pid ($new_pid)	520	$old_pid = $w->pid ($new_pid)
368	Returns the previously set process id and optionally set a new one.	521	Returns the previously set process id and optionally set a new one.
369		522
…		…
373		526
374	$pid = $w->rpid	527	$pid = $w->rpid
375	Return the pid of the awaited child (useful when you have installed	528	Return the pid of the awaited child (useful when you have installed
376	a watcher for all pids).	529	a watcher for all pids).
377		530
		531	STAT WATCHERS - did the file attributes just change?
		532	$w = EV::stat $path, $interval, $callback
		533	$w = EV::stat_ns $path, $interval, $callback
		534	$w = $loop->stat ($path, $interval, $callback)
		535	$w = $loop->stat_ns ($path, $interval, $callback)
		536	Call the callback when a file status change has been detected on
		537	$path. The $path does not need to exist, changing from "path exists"
		538	to "path does not exist" is a status change like any other.
		539
		540	The $interval is a recommended polling interval for systems where
		541	OS-supported change notifications don't exist or are not supported.
		542	If you use 0 then an unspecified default is used (which is highly
		543	recommended!), which is to be expected to be around five seconds
		544	usually.
		545
		546	This watcher type is not meant for massive numbers of stat watchers,
		547	as even with OS-supported change notifications, this can be
		548	resource-intensive.
		549
		550	The "stat_ns" variant doesn't start (activate) the newly created
		551	watcher.
		552
		553	... = $w->stat
		554	This call is very similar to the perl "stat" built-in: It stats
		555	(using "lstat") the path specified in the watcher and sets perls
		556	stat cache (as well as EV's idea of the current stat values) to the
		557	values found.
		558
		559	In scalar context, a boolean is return indicating success or failure
		560	of the stat. In list context, the same 13-value list as with stat is
		561	returned (except that the blksize and blocks fields are not
		562	reliable).
		563
		564	In the case of an error, errno is set to "ENOENT" (regardless of the
		565	actual error value) and the "nlink" value is forced to zero (if the
		566	stat was successful then nlink is guaranteed to be non-zero).
		567
		568	See also the next two entries for more info.
		569
		570	... = $w->attr
		571	Just like "$w->stat", but without the initial stat'ing: this returns
		572	the values most recently detected by EV. See the next entry for more
		573	info.
		574
		575	... = $w->prev
		576	Just like "$w->stat", but without the initial stat'ing: this returns
		577	the previous set of values, before the change.
		578
		579	That is, when the watcher callback is invoked, "$w->prev" will be
		580	set to the values found before a change was detected, while
		581	"$w->attr" returns the values found leading to the change detection.
		582	The difference (if any) between "prev" and "attr" is what triggered
		583	the callback.
		584
		585	If you did something to the filesystem object and do not want to
		586	trigger yet another change, you can call "stat" to update EV's idea
		587	of what the current attributes are.
		588
		589	$w->set ($path, $interval)
		590	Reconfigures the watcher, see the constructor above for details. Can
		591	be called at any time.
		592
		593	$current_path = $w->path
		594	$old_path = $w->path ($new_path)
		595	Returns the previously set path and optionally set a new one.
		596
		597	$current_interval = $w->interval
		598	$old_interval = $w->interval ($new_interval)
		599	Returns the previously set interval and optionally set a new one.
		600	Can be used to query the actual interval used.
		601
		602	IDLE WATCHERS - when you've got nothing better to do...
378	$w = EV::idle $callback	603	$w = EV::idle $callback
379	$w = EV::idle_ns $callback	604	$w = EV::idle_ns $callback
		605	$w = $loop->idle ($callback)
		606	$w = $loop->idle_ns ($callback)
380	Call the callback when there are no pending io, timer/periodic,	607	Call the callback when there are no other pending watchers of the
381	signal or child events, i.e. when the process is idle.	608	same or higher priority (excluding check, prepare and other idle
		609	watchers of the same or lower priority, of course). They are called
		610	idle watchers because when the watcher is the highest priority
		611	pending event in the process, the process is considered to be idle
		612	at that priority.
		613
		614	If you want a watcher that is only ever called when no other
		615	events are outstanding you have to set the priority to "EV::MINPRI".
382		616
383	The process will not block as long as any idle watchers are active,	617	The process will not block as long as any idle watchers are active,
384	and they will be called repeatedly until stopped.	618	and they will be called repeatedly until stopped.
385		619
		620	For example, if you have idle watchers at priority 0 and 1, and an
		621	I/O watcher at priority 0, then the idle watcher at priority 1 and
		622	the I/O watcher will always run when ready. Only when the idle
		623	watcher at priority 1 is stopped and the I/O watcher at priority 0
		624	is not pending with the 0-priority idle watcher be invoked.
		625
386	The "idle_ns" variant doesn't start (activate) the newly created	626	The "idle_ns" variant doesn't start (activate) the newly created
387	watcher.	627	watcher.
388		628
		629	PREPARE WATCHERS - customise your event loop!
389	$w = EV::prepare $callback	630	$w = EV::prepare $callback
390	$w = EV::prepare_ns $callback	631	$w = EV::prepare_ns $callback
		632	$w = $loop->prepare ($callback)
		633	$w = $loop->prepare_ns ($callback)
391	Call the callback just before the process would block. You can still	634	Call the callback just before the process would block. You can still
392	create/modify any watchers at this point.	635	create/modify any watchers at this point.
393		636
394	See the EV::check watcher, below, for explanations and an example.	637	See the EV::check watcher, below, for explanations and an example.
395		638
396	The "prepare_ns" variant doesn't start (activate) the newly created	639	The "prepare_ns" variant doesn't start (activate) the newly created
397	watcher.	640	watcher.
398		641
		642	CHECK WATCHERS - customise your event loop even more!
399	$w = EV::check $callback	643	$w = EV::check $callback
400	$w = EV::check_ns $callback	644	$w = EV::check_ns $callback
		645	$w = $loop->check ($callback)
		646	$w = $loop->check_ns ($callback)
401	Call the callback just after the process wakes up again (after it	647	Call the callback just after the process wakes up again (after it
402	has gathered events), but before any other callbacks have been	648	has gathered events), but before any other callbacks have been
403	invoked.	649	invoked.
404		650
405	This is used to integrate other event-based software into the EV	651	This is used to integrate other event-based software into the EV
…		…
414	# do nothing unless active	660	# do nothing unless active
415	$dispatcher->{_event_queue_h}	661	$dispatcher->{_event_queue_h}
416	or return;	662	or return;
417		663
418	# make the dispatcher handle any outstanding stuff	664	# make the dispatcher handle any outstanding stuff
		665	... not shown
419		666
420	# create an IO watcher for each and every socket	667	# create an I/O watcher for each and every socket
421	@snmp_watcher = (	668	@snmp_watcher = (
422	(map { EV::io $_, EV::READ, sub { } }	669	(map { EV::io $_, EV::READ, sub { } }
423	keys %{ $dispatcher->{_descriptors} }),	670	keys %{ $dispatcher->{_descriptors} }),
		671
		672	EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
		673	? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
		674	0, sub { },
424	);	675	);
425
426	# if there are any timeouts, also create a timer
427	push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
428	if $event->[Net::SNMP::Dispatcher::_ACTIVE];
429	};	676	};
430		677
431	The callbacks are irrelevant, the only purpose of those watchers is	678	The callbacks are irrelevant (and are not even being called), the
432	to wake up the process as soon as one of those events occurs (socket	679	only purpose of those watchers is to wake up the process as soon as
433	readable, or timer timed out). The corresponding EV::check watcher	680	one of those events occurs (socket readable, or timer timed out).
434	will then clean up:	681	The corresponding EV::check watcher will then clean up:
435		682
436	our $snmp_check = EV::check sub {	683	our $snmp_check = EV::check sub {
437	# destroy all watchers	684	# destroy all watchers
438	@snmp_watcher = ();	685	@snmp_watcher = ();
439		686
440	# make the dispatcher handle any new stuff	687	# make the dispatcher handle any new stuff
		688	... not shown
441	};	689	};
442		690
443	The callbacks of the created watchers will not be called as the	691	The callbacks of the created watchers will not be called as the
444	watchers are destroyed before this cna happen (remember EV::check	692	watchers are destroyed before this cna happen (remember EV::check
445	gets called first).	693	gets called first).
446		694
447	The "check_ns" variant doesn't start (activate) the newly created	695	The "check_ns" variant doesn't start (activate) the newly created
448	watcher.	696	watcher.
449		697
		698	FORK WATCHERS - the audacity to resume the event loop after a fork
		699	Fork watchers are called when a "fork ()" was detected. The invocation
		700	is done before the event loop blocks next and before "check" watchers
		701	are being called, and only in the child after the fork.
		702
		703	$w = EV::fork $callback
		704	$w = EV::fork_ns $callback
		705	$w = $loop->fork ($callback)
		706	$w = $loop->fork_ns ($callback)
		707	Call the callback before the event loop is resumed in the child
		708	process after a fork.
		709
		710	The "fork_ns" variant doesn't start (activate) the newly created
		711	watcher.
		712
		713	PERL SIGNALS
		714	While Perl signal handling (%SIG) is not affected by EV, the behaviour
		715	with EV is as the same as any other C library: Perl-signals will only be
		716	handled when Perl runs, which means your signal handler might be invoked
		717	only the next time an event callback is invoked.
		718
		719	The solution is to use EV signal watchers (see "EV::signal"), which will
		720	ensure proper operations with regards to other event watchers.
		721
		722	If you cannot do this for whatever reason, you can also force a watcher
		723	to be called on every event loop iteration by installing a "EV::check"
		724	watcher:
		725
		726	my $async_check = EV::check sub { };
		727
		728	This ensures that perl gets into control for a short time to handle any
		729	pending signals, and also ensures (slightly) slower overall operation.
		730
450	THREADS	731	THREADS
451	Threads are not supported by this in any way. Perl pseudo-threads is	732	Threads are not supported by this module in any way. Perl pseudo-threads
452	evil stuff and must die.	733	is evil stuff and must die. As soon as Perl gains real threads I will
		734	work on thread support for it.
		735
		736	FORK
		737	Most of the "improved" event delivering mechanisms of modern operating
		738	systems have quite a few problems with fork(2) (to put it bluntly: it is
		739	not supported and usually destructive). Libev makes it possible to work
		740	around this by having a function that recreates the kernel state after
		741	fork in the child.
		742
		743	On non-win32 platforms, this module requires the pthread_atfork
		744	functionality to do this automatically for you. This function is quite
		745	buggy on most BSDs, though, so YMMV. The overhead for this is quite
		746	negligible, because everything the function currently does is set a flag
		747	that is checked only when the event loop gets used the next time, so
		748	when you do fork but not use EV, the overhead is minimal.
		749
		750	On win32, there is no notion of fork so all this doesn't apply, of
		751	course.
453		752
454	SEE ALSO	753	SEE ALSO
455	L<EV::DNS>, L<EV::AnyEvent>.	754	EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event
		755	loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines
		756	with EV), Net::SNMP::EV (asynchronous SNMP).
456		757
457	AUTHOR	758	AUTHOR
458	Marc Lehmann <schmorp@schmorp.de>	759	Marc Lehmann <schmorp@schmorp.de>
459	http://home.schmorp.de/	760	http://home.schmorp.de/
460		761

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Revision 1.10 by root, Wed Nov 14 21:25:46 2007 UTC vs.
Revision 1.20 by root, Sat Dec 22 12:05:42 2007 UTC