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Revision 1.47 by root, Fri Nov 23 13:08:55 2007 UTC vs.
Revision 1.127 by root, Sun Mar 28 15:48:21 2010 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 3EV - 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
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMERS 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
42 my $status = $w->rstatus; 48 warn $w->path, " has changed somehow.\n";
43 }; 49 };
44 50
45 # MAINLOOP 51 # MAINLOOP
46 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::loop; # loop until EV::unloop is called or all watchers stop
47 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
48 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
55
56=head1 BEFORE YOU START USING THIS MODULE
57
58If you only need timer, I/O, signal, child and idle watchers and not the
59advanced functionality of this module, consider using L<AnyEvent> instead,
60specifically the simplified API described in L<AE>.
61
62When used with EV as backend, the L<AE> API is as fast as the native L<EV>
63API, but your programs/modules will still run with many other event loops.
49 64
50=head1 DESCRIPTION 65=head1 DESCRIPTION
51 66
52This module provides an interface to libev 67This module provides an interface to libev
53(L<http://software.schmorp.de/pkg/libev.html>). 68(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
69below is comprehensive, one might also consult the documentation of
70libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
71F<perldoc EV::libev>) for more subtle details on watcher semantics or some
72discussion on the available backends, or how to force a specific backend
73with C<LIBEV_FLAGS>, or just about in any case because it has much more
74detailed information.
75
76This module is very fast and scalable. It is actually so fast that you
77can use it through the L<AnyEvent> module, stay portable to other event
78loops (if you don't rely on any watcher types not available through it)
79and still be faster than with any other event loop currently supported in
80Perl.
81
82=head2 MODULE EXPORTS
83
84This module does not export any symbols.
54 85
55=cut 86=cut
56 87
57package EV; 88package EV;
58 89
59use strict; 90use common::sense;
60 91
61BEGIN { 92BEGIN {
62 our $VERSION = '1.2'; 93 our $VERSION = '4.00';
63 use XSLoader; 94 use XSLoader;
64 XSLoader::load "EV", $VERSION; 95 XSLoader::load "EV", $VERSION;
65} 96}
66 97
67@EV::Io::ISA = 98@EV::IO::ISA =
68@EV::Timer::ISA = 99@EV::Timer::ISA =
69@EV::Periodic::ISA = 100@EV::Periodic::ISA =
70@EV::Signal::ISA = 101@EV::Signal::ISA =
102@EV::Child::ISA =
103@EV::Stat::ISA =
71@EV::Idle::ISA = 104@EV::Idle::ISA =
72@EV::Prepare::ISA = 105@EV::Prepare::ISA =
73@EV::Check::ISA = 106@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 107@EV::Embed::ISA =
108@EV::Fork::ISA =
109@EV::Async::ISA =
110 "EV::Watcher";
111
112@EV::Loop::Default::ISA = "EV::Loop";
113
114=head1 EVENT LOOPS
115
116EV supports multiple event loops: There is a single "default event loop"
117that can handle everything including signals and child watchers, and any
118number of "dynamic event loops" that can use different backends (with
119various limitations), but no child and signal watchers.
120
121You do not have to do anything to create the default event loop: When
122the module is loaded a suitable backend is selected on the premise of
123selecting a working backend (which for example rules out kqueue on most
124BSDs). Modules should, unless they have "special needs" always use the
125default loop as this is fastest (perl-wise), best supported by other
126modules (e.g. AnyEvent or Coro) and most portable event loop.
127
128For specific programs you can create additional event loops dynamically.
129
130If you want to take advantage of kqueue (which often works properly for
131sockets only) even though the default loop doesn't enable it, you can
132I<embed> a kqueue loop into the default loop: running the default loop
133will then also service the kqueue loop to some extent. See the example in
134the section about embed watchers for an example on how to achieve that.
135
136=over 4
137
138=item $loop = new EV::Loop [$flags]
139
140Create a new event loop as per the specified flags. Please refer to
141the C<ev_loop_new ()> function description in the libev documentation
142(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
143or locally-installed as F<EV::libev> manpage) for more info.
144
145The loop will automatically be destroyed when it is no longer referenced
146by any watcher and the loop object goes out of scope.
147
148If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
149is recommended, as only the default event loop is protected by this
150module. If you I<are> embedding this loop in the default loop, this is not
151necessary, as C<EV::embed> automatically does the right thing on fork.
152
153=item $loop->loop_fork
154
155Must be called after a fork in the child, before entering or continuing
156the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
157this function automatically, at some performance loss (refer to the libev
158documentation).
159
160=item $loop->loop_verify
161
162Calls C<ev_verify> to make internal consistency checks (for debugging
163libev) and abort the program if any data structures were found to be
164corrupted.
165
166=item $loop = EV::default_loop [$flags]
167
168Return the default loop (which is a singleton object). Since this module
169already creates the default loop with default flags, specifying flags here
170will not have any effect unless you destroy the default loop first, which
171isn't supported. So in short: don't do it, and if you break it, you get to
172keep the pieces.
173
174=back
175
75 176
76=head1 BASIC INTERFACE 177=head1 BASIC INTERFACE
77 178
78=over 4 179=over 4
79 180
80=item $EV::DIED 181=item $EV::DIED
81 182
82Must contain a reference to a function that is called when a callback 183Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 184throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 185informative message and continues.
85 186
86If this callback throws an exception it will be silently ignored. 187If this callback throws an exception it will be silently ignored.
87 188
189=item $flags = EV::supported_backends
190
191=item $flags = EV::recommended_backends
192
193=item $flags = EV::embeddable_backends
194
195Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
196instance of EV, the set of recommended backends (supposed to be good) for
197this platform and the set of embeddable backends (see EMBED WATCHERS).
198
199=item EV::sleep $seconds
200
201Block the process for the given number of (fractional) seconds.
202
88=item $time = EV::time 203=item $time = EV::time
89 204
90Returns the current time in (fractional) seconds since the epoch. 205Returns the current time in (fractional) seconds since the epoch.
91 206
92=item $time = EV::now 207=item $time = EV::now
93 208
209=item $time = $loop->now
210
94Returns the time the last event loop iteration has been started. This 211Returns the time the last event loop iteration has been started. This
95is the time that (relative) timers are based on, and refering to it is 212is the time that (relative) timers are based on, and referring to it is
96usually faster then calling EV::time. 213usually faster then calling EV::time.
97 214
98=item $method = EV::method 215=item EV::now_update
99 216
217=item $loop->now_update
218
219Establishes the current time by querying the kernel, updating the time
220returned by C<EV::now> in the progress. This is a costly operation and
221is usually done automatically within C<EV::loop>.
222
223This function is rarely useful, but when some event callback runs for a
224very long time without entering the event loop, updating libev's idea of
225the current time is a good idea.
226
227=item EV::suspend
228
229=item $loop->suspend
230
231=item EV::resume
232
233=item $loop->resume
234
235These two functions suspend and resume a loop, for use when the loop is
236not used for a while and timeouts should not be processed.
237
238A typical use case would be an interactive program such as a game: When
239the user presses C<^Z> to suspend the game and resumes it an hour later it
240would be best to handle timeouts as if no time had actually passed while
241the program was suspended. This can be achieved by calling C<suspend>
242in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
243C<resume> directly afterwards to resume timer processing.
244
245Effectively, all C<timer> watchers will be delayed by the time spend
246between C<suspend> and C<resume>, and all C<periodic> watchers
247will be rescheduled (that is, they will lose any events that would have
248occured while suspended).
249
250After calling C<suspend> you B<must not> call I<any> function on the given
251loop other than C<resume>, and you B<must not> call C<resume>
252without a previous call to C<suspend>.
253
254Calling C<suspend>/C<resume> has the side effect of updating the event
255loop time (see C<now_update>).
256
257=item $backend = EV::backend
258
259=item $backend = $loop->backend
260
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 261Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
101or EV::METHOD_EPOLL). 262or EV::BACKEND_EPOLL).
102 263
103=item EV::loop [$flags] 264=item EV::loop [$flags]
265
266=item $loop->loop ([$flags])
104 267
105Begin checking for events and calling callbacks. It returns when a 268Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 269callback calls EV::unloop.
107 270
108The $flags argument can be one of the following: 271The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 274 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 275 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 276
114=item EV::unloop [$how] 277=item EV::unloop [$how]
115 278
279=item $loop->unloop ([$how])
280
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 281When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 282innermost call to EV::loop return.
118 283
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 284When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 285fast as possible.
121 286
287=item $count = EV::loop_count
288
289=item $count = $loop->loop_count
290
291Return the number of times the event loop has polled for new
292events. Sometimes useful as a generation counter.
293
122=item EV::once $fh_or_undef, $events, $timeout, $cb->($events) 294=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
295
296=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
123 297
124This function rolls together an I/O and a timer watcher for a single 298This function rolls together an I/O and a timer watcher for a single
125one-shot event without the need for managing a watcher object. 299one-shot event without the need for managing a watcher object.
126 300
127If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> 301If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
133If timeout is C<undef> or negative, then there will be no 307If timeout is C<undef> or negative, then there will be no
134timeout. Otherwise a EV::timer with this value will be started. 308timeout. Otherwise a EV::timer with this value will be started.
135 309
136When an error occurs or either the timeout or I/O watcher triggers, then 310When an error occurs or either the timeout or I/O watcher triggers, then
137the callback will be called with the received event set (in general 311the callback will be called with the received event set (in general
138you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, 312you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
139C<EV::WRITE> and C<EV::TIMEOUT>). 313C<EV::WRITE> and C<EV::TIMER>).
140 314
141EV::once doesn't return anything: the watchers stay active till either 315EV::once doesn't return anything: the watchers stay active till either
142of them triggers, then they will be stopped and freed, and the callback 316of them triggers, then they will be stopped and freed, and the callback
143invoked. 317invoked.
144 318
145=back 319=item EV::feed_fd_event ($fd, $revents)
146 320
147=head2 WATCHER 321=item $loop->feed_fd_event ($fd, $revents)
322
323Feed an event on a file descriptor into EV. EV will react to this call as
324if the readyness notifications specified by C<$revents> (a combination of
325C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
326
327=item EV::feed_signal_event ($signal)
328
329Feed a signal event into EV. EV will react to this call as if the signal
330specified by C<$signal> had occured.
331
332=item EV::set_io_collect_interval $time
333
334=item $loop->set_io_collect_interval ($time)
335
336=item EV::set_timeout_collect_interval $time
337
338=item $loop->set_timeout_collect_interval ($time)
339
340These advanced functions set the minimum block interval when polling for I/O events and the minimum
341wait interval for timer events. See the libev documentation at
342L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
343(locally installed as F<EV::libev>) for a more detailed discussion.
344
345=item $count = EV::pending_count
346
347=item $count = $loop->pending_count
348
349Returns the number of currently pending watchers.
350
351=item EV::invoke_pending
352
353=item $loop->invoke_pending
354
355Invoke all currently pending watchers.
356
357=back
358
359
360=head1 WATCHER OBJECTS
148 361
149A watcher is an object that gets created to record your interest in some 362A watcher is an object that gets created to record your interest in some
150event. For instance, if you want to wait for STDIN to become readable, you 363event. For instance, if you want to wait for STDIN to become readable, you
151would create an EV::io watcher for that: 364would create an EV::io watcher for that:
152 365
153 my $watcher = EV::io *STDIN, EV::READ, sub { 366 my $watcher = EV::io *STDIN, EV::READ, sub {
154 my ($watcher, $revents) = @_; 367 my ($watcher, $revents) = @_;
155 warn "yeah, STDIN should not be readable without blocking!\n" 368 warn "yeah, STDIN should now be readable without blocking!\n"
156 }; 369 };
157 370
158All watchers can be active (waiting for events) or inactive (paused). Only 371All watchers can be active (waiting for events) or inactive (paused). Only
159active watchers will have their callbacks invoked. All callbacks will be 372active watchers will have their callbacks invoked. All callbacks will be
160called with at least two arguments: the watcher and a bitmask of received 373called with at least two arguments: the watcher and a bitmask of received
161events. 374events.
162 375
163Each watcher type has its associated bit in revents, so you can use the 376Each watcher type has its associated bit in revents, so you can use the
164same callback for multiple watchers. The event mask is named after the 377same callback for multiple watchers. The event mask is named after the
165type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 378type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
166EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 379EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
167(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 380(which can set both EV::READ and EV::WRITE bits).
168uses EV::TIMEOUT).
169 381
170In the rare case where one wants to create a watcher but not start it at 382In the rare case where one wants to create a watcher but not start it at
171the same time, each constructor has a variant with a trailing C<_ns> in 383the same time, each constructor has a variant with a trailing C<_ns> in
172its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 384its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
173 385
177 389
178Also, all methods changing some aspect of a watcher (->set, ->priority, 390Also, all methods changing some aspect of a watcher (->set, ->priority,
179->fh and so on) automatically stop and start it again if it is active, 391->fh and so on) automatically stop and start it again if it is active,
180which means pending events get lost. 392which means pending events get lost.
181 393
182=head2 WATCHER TYPES 394=head2 COMMON WATCHER METHODS
183 395
184Now lets move to the existing watcher types and asociated methods. 396This section lists methods common to all watchers.
185
186The following methods are available for all watchers. Then followes a
187description of each watcher constructor (EV::io, EV::timer, EV::periodic,
188EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
189any type-specific methods (if any).
190 397
191=over 4 398=over 4
192 399
193=item $w->start 400=item $w->start
194 401
198 405
199=item $w->stop 406=item $w->stop
200 407
201Stop a watcher if it is active. Also clear any pending events (events that 408Stop a watcher if it is active. Also clear any pending events (events that
202have been received but that didn't yet result in a callback invocation), 409have been received but that didn't yet result in a callback invocation),
203regardless of wether the watcher was active or not. 410regardless of whether the watcher was active or not.
204 411
205=item $bool = $w->is_active 412=item $bool = $w->is_active
206 413
207Returns true if the watcher is active, false otherwise. 414Returns true if the watcher is active, false otherwise.
208 415
233watchers with higher priority will be invoked first. The valid range of 440watchers with higher priority will be invoked first. The valid range of
234priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 441priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
235-2). If the priority is outside this range it will automatically be 442-2). If the priority is outside this range it will automatically be
236normalised to the nearest valid priority. 443normalised to the nearest valid priority.
237 444
238The default priority of any newly-created weatcher is 0. 445The default priority of any newly-created watcher is 0.
239 446
447Note that the priority semantics have not yet been fleshed out and are
448subject to almost certain change.
449
240=item $w->trigger ($revents) 450=item $w->invoke ($revents)
241 451
242Call the callback *now* with the given event mask. 452Call the callback *now* with the given event mask.
243 453
454=item $w->feed_event ($revents)
455
456Feed some events on this watcher into EV. EV will react to this call as if
457the watcher had received the given C<$revents> mask.
458
459=item $revents = $w->clear_pending
460
461If the watcher is pending, this function clears its pending status and
462returns its C<$revents> bitset (as if its callback was invoked). If the
463watcher isn't pending it does nothing and returns C<0>.
464
465=item $previous_state = $w->keepalive ($bool)
466
467Normally, C<EV::loop> will return when there are no active watchers
468(which is a "deadlock" because no progress can be made anymore). This is
469convenient because it allows you to start your watchers (and your jobs),
470call C<EV::loop> once and when it returns you know that all your jobs are
471finished (or they forgot to register some watchers for their task :).
472
473Sometimes, however, this gets in your way, for example when the module
474that calls C<EV::loop> (usually the main program) is not the same module
475as a long-living watcher (for example a DNS client module written by
476somebody else even). Then you might want any outstanding requests to be
477handled, but you would not want to keep C<EV::loop> from returning just
478because you happen to have this long-running UDP port watcher.
479
480In this case you can clear the keepalive status, which means that even
481though your watcher is active, it won't keep C<EV::loop> from returning.
482
483The initial value for keepalive is true (enabled), and you can change it
484any time.
485
486Example: Register an I/O watcher for some UDP socket but do not keep the
487event loop from running just because of that watcher.
488
489 my $udp_socket = ...
490 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
491 $udp_watcher->keepalive (0);
492
493=item $loop = $w->loop
494
495Return the loop that this watcher is attached to.
496
497=back
498
499
500=head1 WATCHER TYPES
501
502Each of the following subsections describes a single watcher type.
503
504=head3 I/O WATCHERS - is this file descriptor readable or writable?
505
506=over 4
244 507
245=item $w = EV::io $fileno_or_fh, $eventmask, $callback 508=item $w = EV::io $fileno_or_fh, $eventmask, $callback
246 509
247=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 510=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
248 511
512=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
513
514=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
515
249As long as the returned watcher object is alive, call the C<$callback> 516As long as the returned watcher object is alive, call the C<$callback>
250when the events specified in C<$eventmask>. 517when at least one of events specified in C<$eventmask> occurs.
251 518
252The $eventmask can be one or more of these constants ORed together: 519The $eventmask can be one or more of these constants ORed together:
253 520
254 EV::READ wait until read() wouldn't block anymore 521 EV::READ wait until read() wouldn't block anymore
255 EV::WRITE wait until write() wouldn't block anymore 522 EV::WRITE wait until write() wouldn't block anymore
271 538
272=item $old_eventmask = $w->events ($new_eventmask) 539=item $old_eventmask = $w->events ($new_eventmask)
273 540
274Returns the previously set event mask and optionally set a new one. 541Returns the previously set event mask and optionally set a new one.
275 542
543=back
544
545
546=head3 TIMER WATCHERS - relative and optionally repeating timeouts
547
548=over 4
276 549
277=item $w = EV::timer $after, $repeat, $callback 550=item $w = EV::timer $after, $repeat, $callback
278 551
279=item $w = EV::timer_ns $after, $repeat, $callback 552=item $w = EV::timer_ns $after, $repeat, $callback
280 553
281Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 554=item $w = $loop->timer ($after, $repeat, $callback)
282the timer will be restarted (with the $repeat value as $after) after the 555
283callback returns. 556=item $w = $loop->timer_ns ($after, $repeat, $callback)
557
558Calls the callback after C<$after> seconds (which may be fractional). If
559C<$repeat> is non-zero, the timer will be restarted (with the $repeat
560value as $after) after the callback returns.
284 561
285This means that the callback would be called roughly after C<$after> 562This means that the callback would be called roughly after C<$after>
286seconds, and then every C<$repeat> seconds. The timer does his best not 563seconds, and then every C<$repeat> seconds. The timer does his best not
287to drift, but it will not invoke the timer more often then once per event 564to drift, but it will not invoke the timer more often then once per event
288loop iteration, and might drift in other cases. If that isn't acceptable, 565loop iteration, and might drift in other cases. If that isn't acceptable,
294 571
295The C<timer_ns> variant doesn't start (activate) the newly created watcher. 572The C<timer_ns> variant doesn't start (activate) the newly created watcher.
296 573
297=item $w->set ($after, $repeat) 574=item $w->set ($after, $repeat)
298 575
299Reconfigures the watcher, see the constructor above for details. Can be at 576Reconfigures the watcher, see the constructor above for details. Can be called at
300any time. 577any time.
301 578
302=item $w->again 579=item $w->again
303 580
304Similar to the C<start> method, but has special semantics for repeating timers: 581Similar to the C<start> method, but has special semantics for repeating timers:
315This behaviour is useful when you have a timeout for some IO 592This behaviour is useful when you have a timeout for some IO
316operation. You create a timer object with the same value for C<$after> and 593operation. You create a timer object with the same value for C<$after> and
317C<$repeat>, and then, in the read/write watcher, run the C<again> method 594C<$repeat>, and then, in the read/write watcher, run the C<again> method
318on the timeout. 595on the timeout.
319 596
597=back
598
599
600=head3 PERIODIC WATCHERS - to cron or not to cron?
601
602=over 4
320 603
321=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 604=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
322 605
323=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 606=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
607
608=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
609
610=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
324 611
325Similar to EV::timer, but is not based on relative timeouts but on 612Similar to EV::timer, but is not based on relative timeouts but on
326absolute times. Apart from creating "simple" timers that trigger "at" the 613absolute times. Apart from creating "simple" timers that trigger "at" the
327specified time, it can also be used for non-drifting absolute timers and 614specified time, it can also be used for non-drifting absolute timers and
328more complex, cron-like, setups that are not adversely affected by time 615more complex, cron-like, setups that are not adversely affected by time
338This time simply fires at the wallclock time C<$at> and doesn't repeat. It 625This time simply fires at the wallclock time C<$at> and doesn't repeat. It
339will not adjust when a time jump occurs, that is, if it is to be run 626will not adjust when a time jump occurs, that is, if it is to be run
340at January 1st 2011 then it will run when the system time reaches or 627at January 1st 2011 then it will run when the system time reaches or
341surpasses this time. 628surpasses this time.
342 629
343=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 630=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
344 631
345In this mode the watcher will always be scheduled to time out at the 632In this mode the watcher will always be scheduled to time out at the
346next C<$at + N * $interval> time (for some integer N) and then repeat, 633next C<$at + N * $interval> time (for some integer N) and then repeat,
347regardless of any time jumps. 634regardless of any time jumps.
348 635
366time the periodic watcher gets scheduled, the reschedule callback 653time the periodic watcher gets scheduled, the reschedule callback
367($reschedule_cb) will be called with the watcher as first, and the current 654($reschedule_cb) will be called with the watcher as first, and the current
368time as second argument. 655time as second argument.
369 656
370I<This callback MUST NOT stop or destroy this or any other periodic 657I<This callback MUST NOT stop or destroy this or any other periodic
371watcher, ever>. If you need to stop it, return 1e30 and stop it 658watcher, ever, and MUST NOT call any event loop functions or methods>. If
372afterwards. 659you need to stop it, return 1e30 and stop it afterwards. You may create
660and start a C<EV::prepare> watcher for this task.
373 661
374It must return the next time to trigger, based on the passed time value 662It must return the next time to trigger, based on the passed time value
375(that is, the lowest time value larger than to the second argument). It 663(that is, the lowest time value larger than or equal to to the second
376will usually be called just before the callback will be triggered, but 664argument). It will usually be called just before the callback will be
377might be called at other times, too. 665triggered, but might be called at other times, too.
378 666
379This can be used to create very complex timers, such as a timer that 667This can be used to create very complex timers, such as a timer that
380triggers on each midnight, local time (actually 24 hours after the last 668triggers on each midnight, local time (actually 24 hours after the last
381midnight, to keep the example simple. If you know a way to do it correctly 669midnight, to keep the example simple. If you know a way to do it correctly
382in about the same space (without requiring elaborate modules), drop me a 670in about the same space (without requiring elaborate modules), drop me a
396 684
397The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 685The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
398 686
399=item $w->set ($at, $interval, $reschedule_cb) 687=item $w->set ($at, $interval, $reschedule_cb)
400 688
401Reconfigures the watcher, see the constructor above for details. Can be at 689Reconfigures the watcher, see the constructor above for details. Can be called at
402any time. 690any time.
403 691
404=item $w->again 692=item $w->again
405 693
406Simply stops and starts the watcher again. 694Simply stops and starts the watcher again.
407 695
696=item $time = $w->at
697
698Return the time that the watcher is expected to trigger next.
699
700=back
701
702
703=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
704
705=over 4
408 706
409=item $w = EV::signal $signal, $callback 707=item $w = EV::signal $signal, $callback
410 708
411=item $w = EV::signal_ns $signal, $callback 709=item $w = EV::signal_ns $signal, $callback
412 710
711=item $w = $loop->signal ($signal, $callback)
712
713=item $w = $loop->signal_ns ($signal, $callback)
714
413Call the callback when $signal is received (the signal can be specified 715Call the callback when $signal is received (the signal can be specified by
414by number or by name, just as with kill or %SIG). 716number or by name, just as with C<kill> or C<%SIG>).
717
718Only one event loop can grab a given signal - attempting to grab the same
719signal from two EV loops will crash the program immediately or cause data
720corruption.
415 721
416EV will grab the signal for the process (the kernel only allows one 722EV will grab the signal for the process (the kernel only allows one
417component to receive a signal at a time) when you start a signal watcher, 723component to receive a signal at a time) when you start a signal watcher,
418and removes it again when you stop it. Perl does the same when you 724and removes it again when you stop it. Perl does the same when you
419add/remove callbacks to %SIG, so watch out. 725add/remove callbacks to C<%SIG>, so watch out.
420 726
421You can have as many signal watchers per signal as you want. 727You can have as many signal watchers per signal as you want.
422 728
423The C<signal_ns> variant doesn't start (activate) the newly created watcher. 729The C<signal_ns> variant doesn't start (activate) the newly created watcher.
424 730
425=item $w->set ($signal) 731=item $w->set ($signal)
426 732
427Reconfigures the watcher, see the constructor above for details. Can be at 733Reconfigures the watcher, see the constructor above for details. Can be
428any time. 734called at any time.
429 735
430=item $current_signum = $w->signal 736=item $current_signum = $w->signal
431 737
432=item $old_signum = $w->signal ($new_signal) 738=item $old_signum = $w->signal ($new_signal)
433 739
434Returns the previously set signal (always as a number not name) and 740Returns the previously set signal (always as a number not name) and
435optionally set a new one. 741optionally set a new one.
436 742
743=back
437 744
745
746=head3 CHILD WATCHERS - watch out for process status changes
747
748=over 4
749
438=item $w = EV::child $pid, $callback 750=item $w = EV::child $pid, $trace, $callback
439 751
440=item $w = EV::child_ns $pid, $callback 752=item $w = EV::child_ns $pid, $trace, $callback
753
754=item $w = $loop->child ($pid, $trace, $callback)
755
756=item $w = $loop->child_ns ($pid, $trace, $callback)
441 757
442Call the callback when a status change for pid C<$pid> (or any pid 758Call the callback when a status change for pid C<$pid> (or any pid
443if C<$pid> is 0) has been received. More precisely: when the process 759if C<$pid> is 0) has been received (a status change happens when the
760process terminates or is killed, or, when trace is true, additionally when
761it is stopped or continued). More precisely: when the process receives
444receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 762a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
445changed/zombie children and call the callback. 763changed/zombie children and call the callback.
446 764
447You can access both status and pid by using the C<rstatus> and C<rpid> 765It is valid (and fully supported) to install a child watcher after a child
448methods on the watcher object. 766has exited but before the event loop has started its next iteration (for
767example, first you C<fork>, then the new child process might exit, and
768only then do you install a child watcher in the parent for the new pid).
449 769
770You can access both exit (or tracing) status and pid by using the
771C<rstatus> and C<rpid> methods on the watcher object.
772
450You can have as many pid watchers per pid as you want. 773You can have as many pid watchers per pid as you want, they will all be
774called.
451 775
452The C<child_ns> variant doesn't start (activate) the newly created watcher. 776The C<child_ns> variant doesn't start (activate) the newly created watcher.
453 777
454=item $w->set ($pid) 778=item $w->set ($pid, $trace)
455 779
456Reconfigures the watcher, see the constructor above for details. Can be at 780Reconfigures the watcher, see the constructor above for details. Can be called at
457any time. 781any time.
458 782
459=item $current_pid = $w->pid 783=item $current_pid = $w->pid
460
461=item $old_pid = $w->pid ($new_pid)
462 784
463Returns the previously set process id and optionally set a new one. 785Returns the previously set process id and optionally set a new one.
464 786
465=item $exit_status = $w->rstatus 787=item $exit_status = $w->rstatus
466 788
470=item $pid = $w->rpid 792=item $pid = $w->rpid
471 793
472Return the pid of the awaited child (useful when you have installed a 794Return the pid of the awaited child (useful when you have installed a
473watcher for all pids). 795watcher for all pids).
474 796
797=back
798
799
800=head3 STAT WATCHERS - did the file attributes just change?
801
802=over 4
803
804=item $w = EV::stat $path, $interval, $callback
805
806=item $w = EV::stat_ns $path, $interval, $callback
807
808=item $w = $loop->stat ($path, $interval, $callback)
809
810=item $w = $loop->stat_ns ($path, $interval, $callback)
811
812Call the callback when a file status change has been detected on
813C<$path>. The C<$path> does not need to exist, changing from "path exists"
814to "path does not exist" is a status change like any other.
815
816The C<$interval> is a recommended polling interval for systems where
817OS-supported change notifications don't exist or are not supported. If
818you use C<0> then an unspecified default is used (which is highly
819recommended!), which is to be expected to be around five seconds usually.
820
821This watcher type is not meant for massive numbers of stat watchers,
822as even with OS-supported change notifications, this can be
823resource-intensive.
824
825The C<stat_ns> variant doesn't start (activate) the newly created watcher.
826
827=item ... = $w->stat
828
829This call is very similar to the perl C<stat> built-in: It stats (using
830C<lstat>) the path specified in the watcher and sets perls stat cache (as
831well as EV's idea of the current stat values) to the values found.
832
833In scalar context, a boolean is return indicating success or failure of
834the stat. In list context, the same 13-value list as with stat is returned
835(except that the blksize and blocks fields are not reliable).
836
837In the case of an error, errno is set to C<ENOENT> (regardless of the
838actual error value) and the C<nlink> value is forced to zero (if the stat
839was successful then nlink is guaranteed to be non-zero).
840
841See also the next two entries for more info.
842
843=item ... = $w->attr
844
845Just like C<< $w->stat >>, but without the initial stat'ing: this returns
846the values most recently detected by EV. See the next entry for more info.
847
848=item ... = $w->prev
849
850Just like C<< $w->stat >>, but without the initial stat'ing: this returns
851the previous set of values, before the change.
852
853That is, when the watcher callback is invoked, C<< $w->prev >> will be set
854to the values found I<before> a change was detected, while C<< $w->attr >>
855returns the values found leading to the change detection. The difference (if any)
856between C<prev> and C<attr> is what triggered the callback.
857
858If you did something to the filesystem object and do not want to trigger
859yet another change, you can call C<stat> to update EV's idea of what the
860current attributes are.
861
862=item $w->set ($path, $interval)
863
864Reconfigures the watcher, see the constructor above for details. Can be
865called at any time.
866
867=item $current_path = $w->path
868
869=item $old_path = $w->path ($new_path)
870
871Returns the previously set path and optionally set a new one.
872
873=item $current_interval = $w->interval
874
875=item $old_interval = $w->interval ($new_interval)
876
877Returns the previously set interval and optionally set a new one. Can be
878used to query the actual interval used.
879
880=back
881
882
883=head3 IDLE WATCHERS - when you've got nothing better to do...
884
885=over 4
475 886
476=item $w = EV::idle $callback 887=item $w = EV::idle $callback
477 888
478=item $w = EV::idle_ns $callback 889=item $w = EV::idle_ns $callback
479 890
480Call the callback when there are no pending io, timer/periodic, signal or 891=item $w = $loop->idle ($callback)
481child events, i.e. when the process is idle. 892
893=item $w = $loop->idle_ns ($callback)
894
895Call the callback when there are no other pending watchers of the same or
896higher priority (excluding check, prepare and other idle watchers of the
897same or lower priority, of course). They are called idle watchers because
898when the watcher is the highest priority pending event in the process, the
899process is considered to be idle at that priority.
900
901If you want a watcher that is only ever called when I<no> other events are
902outstanding you have to set the priority to C<EV::MINPRI>.
482 903
483The process will not block as long as any idle watchers are active, and 904The process will not block as long as any idle watchers are active, and
484they will be called repeatedly until stopped. 905they will be called repeatedly until stopped.
485 906
907For example, if you have idle watchers at priority C<0> and C<1>, and
908an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
909and the I/O watcher will always run when ready. Only when the idle watcher
910at priority C<1> is stopped and the I/O watcher at priority C<0> is not
911pending with the C<0>-priority idle watcher be invoked.
912
486The C<idle_ns> variant doesn't start (activate) the newly created watcher. 913The C<idle_ns> variant doesn't start (activate) the newly created watcher.
487 914
915=back
916
917
918=head3 PREPARE WATCHERS - customise your event loop!
919
920=over 4
488 921
489=item $w = EV::prepare $callback 922=item $w = EV::prepare $callback
490 923
491=item $w = EV::prepare_ns $callback 924=item $w = EV::prepare_ns $callback
925
926=item $w = $loop->prepare ($callback)
927
928=item $w = $loop->prepare_ns ($callback)
492 929
493Call the callback just before the process would block. You can still 930Call the callback just before the process would block. You can still
494create/modify any watchers at this point. 931create/modify any watchers at this point.
495 932
496See the EV::check watcher, below, for explanations and an example. 933See the EV::check watcher, below, for explanations and an example.
497 934
498The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 935The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
499 936
937=back
938
939
940=head3 CHECK WATCHERS - customise your event loop even more!
941
942=over 4
500 943
501=item $w = EV::check $callback 944=item $w = EV::check $callback
502 945
503=item $w = EV::check_ns $callback 946=item $w = EV::check_ns $callback
947
948=item $w = $loop->check ($callback)
949
950=item $w = $loop->check_ns ($callback)
504 951
505Call the callback just after the process wakes up again (after it has 952Call the callback just after the process wakes up again (after it has
506gathered events), but before any other callbacks have been invoked. 953gathered events), but before any other callbacks have been invoked.
507 954
508This is used to integrate other event-based software into the EV 955This is used to integrate other event-based software into the EV
518 or return; 965 or return;
519 966
520 # make the dispatcher handle any outstanding stuff 967 # make the dispatcher handle any outstanding stuff
521 ... not shown 968 ... not shown
522 969
523 # create an IO watcher for each and every socket 970 # create an I/O watcher for each and every socket
524 @snmp_watcher = ( 971 @snmp_watcher = (
525 (map { EV::io $_, EV::READ, sub { } } 972 (map { EV::io $_, EV::READ, sub { } }
526 keys %{ $dispatcher->{_descriptors} }), 973 keys %{ $dispatcher->{_descriptors} }),
527 974
528 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 975 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
543 # make the dispatcher handle any new stuff 990 # make the dispatcher handle any new stuff
544 ... not shown 991 ... not shown
545 }; 992 };
546 993
547The callbacks of the created watchers will not be called as the watchers 994The callbacks of the created watchers will not be called as the watchers
548are destroyed before this cna happen (remember EV::check gets called 995are destroyed before this can happen (remember EV::check gets called
549first). 996first).
550 997
551The C<check_ns> variant doesn't start (activate) the newly created watcher. 998The C<check_ns> variant doesn't start (activate) the newly created watcher.
552 999
553=back 1000=back
554 1001
1002
1003=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
1004
1005Fork watchers are called when a C<fork ()> was detected. The invocation
1006is done before the event loop blocks next and before C<check> watchers
1007are being called, and only in the child after the fork.
1008
1009=over 4
1010
1011=item $w = EV::fork $callback
1012
1013=item $w = EV::fork_ns $callback
1014
1015=item $w = $loop->fork ($callback)
1016
1017=item $w = $loop->fork_ns ($callback)
1018
1019Call the callback before the event loop is resumed in the child process
1020after a fork.
1021
1022The C<fork_ns> variant doesn't start (activate) the newly created watcher.
1023
1024=back
1025
1026
1027=head3 EMBED WATCHERS - when one backend isn't enough...
1028
1029This is a rather advanced watcher type that lets you embed one event loop
1030into another (currently only IO events are supported in the embedded
1031loop, other types of watchers might be handled in a delayed or incorrect
1032fashion and must not be used).
1033
1034See the libev documentation at
1035L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1036(locally installed as F<EV::libev>) for more details.
1037
1038In short, this watcher is most useful on BSD systems without working
1039kqueue to still be able to handle a large number of sockets:
1040
1041 my $socket_loop;
1042
1043 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1044 if (
1045 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1046 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1047 ) {
1048 # use kqueue for sockets
1049 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1050 }
1051
1052 # use the default loop otherwise
1053 $socket_loop ||= EV::default_loop;
1054
1055=over 4
1056
1057=item $w = EV::embed $otherloop[, $callback]
1058
1059=item $w = EV::embed_ns $otherloop[, $callback]
1060
1061=item $w = $loop->embed ($otherloop[, $callback])
1062
1063=item $w = $loop->embed_ns ($otherloop[, $callback])
1064
1065Call the callback when the embedded event loop (C<$otherloop>) has any
1066I/O activity. The C<$callback> is optional: if it is missing, then the
1067embedded event loop will be managed automatically (which is recommended),
1068otherwise you have to invoke C<sweep> yourself.
1069
1070The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1071
1072=back
1073
1074=head3 ASYNC WATCHERS - how to wake up another event loop
1075
1076Async watchers are provided by EV, but have little use in perl directly,
1077as perl neither supports threads running in parallel nor direct access to
1078signal handlers or other contexts where they could be of value.
1079
1080It is, however, possible to use them from the XS level.
1081
1082Please see the libev documentation for further details.
1083
1084=over 4
1085
1086=item $w = EV::async $callback
1087
1088=item $w = EV::async_ns $callback
1089
1090=item $w->send
1091
1092=item $bool = $w->async_pending
1093
1094=back
1095
1096
1097=head1 PERL SIGNALS
1098
1099While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1100with EV is as the same as any other C library: Perl-signals will only be
1101handled when Perl runs, which means your signal handler might be invoked
1102only the next time an event callback is invoked.
1103
1104The solution is to use EV signal watchers (see C<EV::signal>), which will
1105ensure proper operations with regards to other event watchers.
1106
1107If you cannot do this for whatever reason, you can also force a watcher
1108to be called on every event loop iteration by installing a C<EV::check>
1109watcher:
1110
1111 my $async_check = EV::check sub { };
1112
1113This ensures that perl gets into control for a short time to handle any
1114pending signals, and also ensures (slightly) slower overall operation.
1115
555=head1 THREADS 1116=head1 ITHREADS
556 1117
557Threads are not supported by this module in any way. Perl pseudo-threads 1118Ithreads are not supported by this module in any way. Perl pseudo-threads
558is evil stuff and must die. As soon as Perl gains real threads I will work 1119is evil stuff and must die. Real threads as provided by Coro are fully
559on thread support for it. 1120supported (and enhanced support is available via L<Coro::EV>).
560 1121
561=head1 FORK 1122=head1 FORK
562 1123
563Most of the "improved" event delivering mechanisms of modern operating 1124Most of the "improved" event delivering mechanisms of modern operating
564systems have quite a few problems with fork(2) (to put it bluntly: it is 1125systems have quite a few problems with fork(2) (to put it bluntly: it is
580our $DIED = sub { 1141our $DIED = sub {
581 warn "EV: error in callback (ignoring): $@"; 1142 warn "EV: error in callback (ignoring): $@";
582}; 1143};
583 1144
584default_loop 1145default_loop
585 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1146 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
586 1147
5871; 11481;
588 1149
589=head1 SEE ALSO 1150=head1 SEE ALSO
590 1151
591 L<EV::DNS>. 1152L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1153event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1154coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1155event-loop agnostic and portable event driven programming.
592 1156
593=head1 AUTHOR 1157=head1 AUTHOR
594 1158
595 Marc Lehmann <schmorp@schmorp.de> 1159 Marc Lehmann <schmorp@schmorp.de>
596 http://home.schmorp.de/ 1160 http://home.schmorp.de/
597 1161
598=cut 1162=cut
599 1163

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