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Revision 1.60 by root, Mon Dec 3 13:41:24 2007 UTC vs.
Revision 1.149 by root, Wed Apr 20 13:43:39 2016 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 {
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
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
44
45 # STAT CHANGES 45 # STAT CHANGES
46 my $w = EV::stat "/etc/passwd", 10, sub { 46 my $w = EV::stat "/etc/passwd", 10, sub {
47 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
48 warn $w->path, " has changed somehow.\n"; 48 warn $w->path, " has changed somehow.\n";
49 }; 49 };
50 50
51 # MAINLOOP 51 # MAINLOOP
52 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::run; # loop until EV::break is called or all watchers stop
53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::run EV::RUN_ONCE; # block until at least one event could be handled
54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::run EV::RUN_NOWAIT; # 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.
55 64
56=head1 DESCRIPTION 65=head1 DESCRIPTION
57 66
58This module provides an interface to libev 67This module provides an interface to libev
59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation 68(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of libev 69below is comprehensive, one might also consult the documentation of
61itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on 70libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62watcher semantics or some discussion on the available backends, or how to 71F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63force a specific backend with C<LIBEV_FLAGS>. 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 PORTING FROM EV 3.X to 4.X
83
84EV version 4 introduces a number of incompatible changes summarised
85here. According to the depreciation strategy used by libev, there is a
86compatibility layer in place so programs should continue to run unchanged
87(the XS interface lacks this layer, so programs using that one need to be
88updated).
89
90This compatibility layer will be switched off in some future release.
91
92All changes relevant to Perl are renames of symbols, functions and
93methods:
94
95 EV::loop => EV::run
96 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
97 EV::LOOP_ONESHOT => EV::RUN_ONCE
98
99 EV::unloop => EV::break
100 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
101 EV::UNLOOP_ONE => EV::BREAK_ONE
102 EV::UNLOOP_ALL => EV::BREAK_ALL
103
104 EV::TIMEOUT => EV::TIMER
105
106 EV::loop_count => EV::iteration
107 EV::loop_depth => EV::depth
108 EV::loop_verify => EV::verify
109
110The loop object methods corresponding to the functions above have been
111similarly renamed.
112
113=head2 MODULE EXPORTS
114
115This module does not export any symbols.
64 116
65=cut 117=cut
66 118
67package EV; 119package EV;
68 120
69use strict; 121use common::sense;
70 122
71BEGIN { 123BEGIN {
72 our $VERSION = '1.6'; 124 our $VERSION = 4.22;
73 use XSLoader; 125 use XSLoader;
126 local $^W = 0; # avoid spurious warning
74 XSLoader::load "EV", $VERSION; 127 XSLoader::load "EV", $VERSION;
75} 128}
76 129
77@EV::IO::ISA = 130@EV::IO::ISA =
78@EV::Timer::ISA = 131@EV::Timer::ISA =
83@EV::Idle::ISA = 136@EV::Idle::ISA =
84@EV::Prepare::ISA = 137@EV::Prepare::ISA =
85@EV::Check::ISA = 138@EV::Check::ISA =
86@EV::Embed::ISA = 139@EV::Embed::ISA =
87@EV::Fork::ISA = 140@EV::Fork::ISA =
141@EV::Async::ISA =
88 "EV::Watcher"; 142 "EV::Watcher";
89 143
144@EV::Loop::Default::ISA = "EV::Loop";
145
146=head1 EVENT LOOPS
147
148EV supports multiple event loops: There is a single "default event loop"
149that can handle everything including signals and child watchers, and any
150number of "dynamic event loops" that can use different backends (with
151various limitations), but no child and signal watchers.
152
153You do not have to do anything to create the default event loop: When
154the module is loaded a suitable backend is selected on the premise of
155selecting a working backend (which for example rules out kqueue on most
156BSDs). Modules should, unless they have "special needs" always use the
157default loop as this is fastest (perl-wise), best supported by other
158modules (e.g. AnyEvent or Coro) and most portable event loop.
159
160For specific programs you can create additional event loops dynamically.
161
162If you want to take advantage of kqueue (which often works properly for
163sockets only) even though the default loop doesn't enable it, you can
164I<embed> a kqueue loop into the default loop: running the default loop
165will then also service the kqueue loop to some extent. See the example in
166the section about embed watchers for an example on how to achieve that.
167
168=over 4
169
170=item $loop = new EV::Loop [$flags]
171
172Create a new event loop as per the specified flags. Please refer to
173the C<ev_loop_new ()> function description in the libev documentation
174(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
175or locally-installed as F<EV::libev> manpage) for more info.
176
177The loop will automatically be destroyed when it is no longer referenced
178by any watcher and the loop object goes out of scope.
179
180If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
181is recommended, as only the default event loop is protected by this
182module. If you I<are> embedding this loop in the default loop, this is not
183necessary, as C<EV::embed> automatically does the right thing on fork.
184
185=item $loop->loop_fork
186
187Must be called after a fork in the child, before entering or continuing
188the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
189this function automatically, at some performance loss (refer to the libev
190documentation).
191
192=item $loop->verify
193
194Calls C<ev_verify> to make internal consistency checks (for debugging
195libev) and abort the program if any data structures were found to be
196corrupted.
197
198=item $loop = EV::default_loop [$flags]
199
200Return the default loop (which is a singleton object). Since this module
201already creates the default loop with default flags, specifying flags here
202will not have any effect unless you destroy the default loop first, which
203isn't supported. So in short: don't do it, and if you break it, you get to
204keep the pieces.
205
206=back
207
208
90=head1 BASIC INTERFACE 209=head1 BASIC INTERFACE
91 210
92=over 4 211=over 4
93 212
94=item $EV::DIED 213=item $EV::DIED
95 214
96Must contain a reference to a function that is called when a callback 215Must contain a reference to a function that is called when a callback
97throws an exception (with $@ containing thr error). The default prints an 216throws an exception (with $@ containing the error). The default prints an
98informative message and continues. 217informative message and continues.
99 218
100If this callback throws an exception it will be silently ignored. 219If this callback throws an exception it will be silently ignored.
101 220
221=item $flags = EV::supported_backends
222
223=item $flags = EV::recommended_backends
224
225=item $flags = EV::embeddable_backends
226
227Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
228instance of EV, the set of recommended backends (supposed to be good) for
229this platform and the set of embeddable backends (see EMBED WATCHERS).
230
231=item EV::sleep $seconds
232
233Block the process for the given number of (fractional) seconds.
234
102=item $time = EV::time 235=item $time = EV::time
103 236
104Returns the current time in (fractional) seconds since the epoch. 237Returns the current time in (fractional) seconds since the epoch.
105 238
106=item $time = EV::now 239=item $time = EV::now
107 240
241=item $time = $loop->now
242
108Returns the time the last event loop iteration has been started. This 243Returns the time the last event loop iteration has been started. This
109is the time that (relative) timers are based on, and refering to it is 244is the time that (relative) timers are based on, and referring to it is
110usually faster then calling EV::time. 245usually faster then calling EV::time.
111 246
112=item $method = EV::method 247=item EV::now_update
113 248
249=item $loop->now_update
250
251Establishes the current time by querying the kernel, updating the time
252returned by C<EV::now> in the progress. This is a costly operation and
253is usually done automatically within C<EV::loop>.
254
255This function is rarely useful, but when some event callback runs for a
256very long time without entering the event loop, updating libev's idea of
257the current time is a good idea.
258
259=item EV::suspend
260
261=item $loop->suspend
262
263=item EV::resume
264
265=item $loop->resume
266
267These two functions suspend and resume a loop, for use when the loop is
268not used for a while and timeouts should not be processed.
269
270A typical use case would be an interactive program such as a game: When
271the user presses C<^Z> to suspend the game and resumes it an hour later it
272would be best to handle timeouts as if no time had actually passed while
273the program was suspended. This can be achieved by calling C<suspend>
274in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
275C<resume> directly afterwards to resume timer processing.
276
277Effectively, all C<timer> watchers will be delayed by the time spend
278between C<suspend> and C<resume>, and all C<periodic> watchers
279will be rescheduled (that is, they will lose any events that would have
280occured while suspended).
281
282After calling C<suspend> you B<must not> call I<any> function on the given
283loop other than C<resume>, and you B<must not> call C<resume>
284without a previous call to C<suspend>.
285
286Calling C<suspend>/C<resume> has the side effect of updating the event
287loop time (see C<now_update>).
288
289=item $backend = EV::backend
290
291=item $backend = $loop->backend
292
114Returns an integer describing the backend used by libev (EV::METHOD_SELECT 293Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
115or EV::METHOD_EPOLL). 294or EV::BACKEND_EPOLL).
116 295
117=item EV::loop [$flags] 296=item $active = EV::run [$flags]
297
298=item $active = $loop->run ([$flags])
118 299
119Begin checking for events and calling callbacks. It returns when a 300Begin checking for events and calling callbacks. It returns when a
120callback calls EV::unloop. 301callback calls EV::break or the flags are nonzero (in which case the
302return value is true) or when there are no active watchers which reference
303the loop (keepalive is true), in which case the return value will be
304false. The return value can generally be interpreted as "if true, there is
305more work left to do".
121 306
122The $flags argument can be one of the following: 307The $flags argument can be one of the following:
123 308
124 0 as above 309 0 as above
125 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 310 EV::RUN_ONCE block at most once (wait, but do not loop)
126 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 311 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
127 312
128=item EV::unloop [$how] 313=item EV::break [$how]
129 314
315=item $loop->break ([$how])
316
130When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 317When called with no arguments or an argument of EV::BREAK_ONE, makes the
131innermost call to EV::loop return. 318innermost call to EV::loop return.
132 319
133When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 320When called with an argument of EV::BREAK_ALL, all calls to EV::loop will
134fast as possible. 321return as fast as possible.
135 322
136=item $count = EV::loop_count 323When called with an argument of EV::BREAK_CANCEL, any pending break will
324be cancelled.
325
326=item $count = EV::iteration
327
328=item $count = $loop->iteration
137 329
138Return the number of times the event loop has polled for new 330Return the number of times the event loop has polled for new
139events. Sometiems useful as a generation counter. 331events. Sometimes useful as a generation counter.
140 332
141=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 333=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
334
335=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
142 336
143This function rolls together an I/O and a timer watcher for a single 337This function rolls together an I/O and a timer watcher for a single
144one-shot event without the need for managing a watcher object. 338one-shot event without the need for managing a watcher object.
145 339
146If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> 340If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
152If timeout is C<undef> or negative, then there will be no 346If timeout is C<undef> or negative, then there will be no
153timeout. Otherwise a EV::timer with this value will be started. 347timeout. Otherwise a EV::timer with this value will be started.
154 348
155When an error occurs or either the timeout or I/O watcher triggers, then 349When an error occurs or either the timeout or I/O watcher triggers, then
156the callback will be called with the received event set (in general 350the callback will be called with the received event set (in general
157you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, 351you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
158C<EV::WRITE> and C<EV::TIMEOUT>). 352C<EV::WRITE> and C<EV::TIMER>).
159 353
160EV::once doesn't return anything: the watchers stay active till either 354EV::once doesn't return anything: the watchers stay active till either
161of them triggers, then they will be stopped and freed, and the callback 355of them triggers, then they will be stopped and freed, and the callback
162invoked. 356invoked.
163 357
164=back 358=item EV::feed_fd_event $fd, $revents
165 359
360=item $loop->feed_fd_event ($fd, $revents)
361
362Feed an event on a file descriptor into EV. EV will react to this call as
363if the readyness notifications specified by C<$revents> (a combination of
364C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
365
366=item EV::feed_signal_event $signal
367
368Feed a signal event into the default loop. EV will react to this call as
369if the signal specified by C<$signal> had occured.
370
371=item EV::feed_signal $signal
372
373Feed a signal event into EV - unlike C<EV::feed_signal_event>, this works
374regardless of which loop has registered the signal, and is mainly useful
375fro custom signal implementations.
376
377=item EV::set_io_collect_interval $time
378
379=item $loop->set_io_collect_interval ($time)
380
381=item EV::set_timeout_collect_interval $time
382
383=item $loop->set_timeout_collect_interval ($time)
384
385These advanced functions set the minimum block interval when polling for I/O events and the minimum
386wait interval for timer events. See the libev documentation at
387L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
388(locally installed as F<EV::libev>) for a more detailed discussion.
389
390=item $count = EV::pending_count
391
392=item $count = $loop->pending_count
393
394Returns the number of currently pending watchers.
395
396=item EV::invoke_pending
397
398=item $loop->invoke_pending
399
400Invoke all currently pending watchers.
401
402=back
403
404
166=head2 WATCHER OBJECTS 405=head1 WATCHER OBJECTS
167 406
168A watcher is an object that gets created to record your interest in some 407A watcher is an object that gets created to record your interest in some
169event. For instance, if you want to wait for STDIN to become readable, you 408event. For instance, if you want to wait for STDIN to become readable, you
170would create an EV::io watcher for that: 409would create an EV::io watcher for that:
171 410
172 my $watcher = EV::io *STDIN, EV::READ, sub { 411 my $watcher = EV::io *STDIN, EV::READ, sub {
173 my ($watcher, $revents) = @_; 412 my ($watcher, $revents) = @_;
174 warn "yeah, STDIN should not be readable without blocking!\n" 413 warn "yeah, STDIN should now be readable without blocking!\n"
175 }; 414 };
176 415
177All watchers can be active (waiting for events) or inactive (paused). Only 416All watchers can be active (waiting for events) or inactive (paused). Only
178active watchers will have their callbacks invoked. All callbacks will be 417active watchers will have their callbacks invoked. All callbacks will be
179called with at least two arguments: the watcher and a bitmask of received 418called with at least two arguments: the watcher and a bitmask of received
180events. 419events.
181 420
182Each watcher type has its associated bit in revents, so you can use the 421Each watcher type has its associated bit in revents, so you can use the
183same callback for multiple watchers. The event mask is named after the 422same callback for multiple watchers. The event mask is named after the
184type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 423type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
185EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 424EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
186(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 425(which can set both EV::READ and EV::WRITE bits).
187uses EV::TIMEOUT).
188 426
189In the rare case where one wants to create a watcher but not start it at 427In the rare case where one wants to create a watcher but not start it at
190the same time, each constructor has a variant with a trailing C<_ns> in 428the same time, each constructor has a variant with a trailing C<_ns> in
191its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 429its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
192 430
212 450
213=item $w->stop 451=item $w->stop
214 452
215Stop a watcher if it is active. Also clear any pending events (events that 453Stop a watcher if it is active. Also clear any pending events (events that
216have been received but that didn't yet result in a callback invocation), 454have been received but that didn't yet result in a callback invocation),
217regardless of wether the watcher was active or not. 455regardless of whether the watcher was active or not.
218 456
219=item $bool = $w->is_active 457=item $bool = $w->is_active
220 458
221Returns true if the watcher is active, false otherwise. 459Returns true if the watcher is active, false otherwise.
222 460
252The default priority of any newly-created watcher is 0. 490The default priority of any newly-created watcher is 0.
253 491
254Note that the priority semantics have not yet been fleshed out and are 492Note that the priority semantics have not yet been fleshed out and are
255subject to almost certain change. 493subject to almost certain change.
256 494
257=item $w->trigger ($revents) 495=item $w->invoke ($revents)
258 496
259Call the callback *now* with the given event mask. 497Call the callback *now* with the given event mask.
498
499=item $w->feed_event ($revents)
500
501Feed some events on this watcher into EV. EV will react to this call as if
502the watcher had received the given C<$revents> mask.
503
504=item $revents = $w->clear_pending
505
506If the watcher is pending, this function clears its pending status and
507returns its C<$revents> bitset (as if its callback was invoked). If the
508watcher isn't pending it does nothing and returns C<0>.
260 509
261=item $previous_state = $w->keepalive ($bool) 510=item $previous_state = $w->keepalive ($bool)
262 511
263Normally, C<EV::loop> will return when there are no active watchers 512Normally, C<EV::loop> will return when there are no active watchers
264(which is a "deadlock" because no progress can be made anymore). This is 513(which is a "deadlock" because no progress can be made anymore). This is
265convinient because it allows you to start your watchers (and your jobs), 514convenient because it allows you to start your watchers (and your jobs),
266call C<EV::loop> once and when it returns you know that all your jobs are 515call C<EV::loop> once and when it returns you know that all your jobs are
267finished (or they forgot to register some watchers for their task :). 516finished (or they forgot to register some watchers for their task :).
268 517
269Sometimes, however, this gets in your way, for example when you the module 518Sometimes, however, this gets in your way, for example when the module
270that calls C<EV::loop> (usually the main program) is not the same module 519that calls C<EV::loop> (usually the main program) is not the same module
271as a long-living watcher (for example a DNS client module written by 520as a long-living watcher (for example a DNS client module written by
272somebody else even). Then you might want any outstanding requests to be 521somebody else even). Then you might want any outstanding requests to be
273handled, but you would not want to keep C<EV::loop> from returning just 522handled, but you would not want to keep C<EV::loop> from returning just
274because you happen to have this long-running UDP port watcher. 523because you happen to have this long-running UDP port watcher.
275 524
276In this case you can clear the keepalive status, which means that even 525In this case you can clear the keepalive status, which means that even
277though your watcher is active, it won't keep C<EV::loop> from returning. 526though your watcher is active, it won't keep C<EV::loop> from returning.
278 527
279The initial value for keepalive is true (enabled), and you cna change it 528The initial value for keepalive is true (enabled), and you can change it
280any time. 529any time.
281 530
282Example: Register an IO watcher for some UDP socket but do not keep the 531Example: Register an I/O watcher for some UDP socket but do not keep the
283event loop from running just because of that watcher. 532event loop from running just because of that watcher.
284 533
285 my $udp_socket = ... 534 my $udp_socket = ...
286 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 535 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
287 $udp_watcher->keepalive (0); 536 $udp_watcher->keepalive (0);
288 537
289=back 538=item $loop = $w->loop
290 539
540Return the loop that this watcher is attached to.
291 541
542=back
543
544
292=head2 WATCHER TYPES 545=head1 WATCHER TYPES
293 546
294Each of the following subsections describes a single watcher type. 547Each of the following subsections describes a single watcher type.
295 548
296=head3 IO WATCHERS - is this file descriptor readable or writable? 549=head3 I/O WATCHERS - is this file descriptor readable or writable?
297 550
298=over 4 551=over 4
299 552
300=item $w = EV::io $fileno_or_fh, $eventmask, $callback 553=item $w = EV::io $fileno_or_fh, $eventmask, $callback
301 554
302=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 555=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
556
557=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
558
559=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
303 560
304As long as the returned watcher object is alive, call the C<$callback> 561As long as the returned watcher object is alive, call the C<$callback>
305when at least one of events specified in C<$eventmask> occurs. 562when at least one of events specified in C<$eventmask> occurs.
306 563
307The $eventmask can be one or more of these constants ORed together: 564The $eventmask can be one or more of these constants ORed together:
336=over 4 593=over 4
337 594
338=item $w = EV::timer $after, $repeat, $callback 595=item $w = EV::timer $after, $repeat, $callback
339 596
340=item $w = EV::timer_ns $after, $repeat, $callback 597=item $w = EV::timer_ns $after, $repeat, $callback
598
599=item $w = $loop->timer ($after, $repeat, $callback)
600
601=item $w = $loop->timer_ns ($after, $repeat, $callback)
341 602
342Calls the callback after C<$after> seconds (which may be fractional). If 603Calls the callback after C<$after> seconds (which may be fractional). If
343C<$repeat> is non-zero, the timer will be restarted (with the $repeat 604C<$repeat> is non-zero, the timer will be restarted (with the $repeat
344value as $after) after the callback returns. 605value as $after) after the callback returns.
345 606
353in front of the machine while the timer is running and changes the system 614in front of the machine while the timer is running and changes the system
354clock, the timer will nevertheless run (roughly) the same time. 615clock, the timer will nevertheless run (roughly) the same time.
355 616
356The C<timer_ns> variant doesn't start (activate) the newly created watcher. 617The C<timer_ns> variant doesn't start (activate) the newly created watcher.
357 618
358=item $w->set ($after, $repeat) 619=item $w->set ($after, $repeat = 0)
359 620
360Reconfigures the watcher, see the constructor above for details. Can be called at 621Reconfigures the watcher, see the constructor above for details. Can be called at
361any time. 622any time.
362 623
363=item $w->again 624=item $w->again
625
626=item $w->again ($repeat)
364 627
365Similar to the C<start> method, but has special semantics for repeating timers: 628Similar to the C<start> method, but has special semantics for repeating timers:
366 629
367If the timer is active and non-repeating, it will be stopped. 630If the timer is active and non-repeating, it will be stopped.
368 631
376This behaviour is useful when you have a timeout for some IO 639This behaviour is useful when you have a timeout for some IO
377operation. You create a timer object with the same value for C<$after> and 640operation. You create a timer object with the same value for C<$after> and
378C<$repeat>, and then, in the read/write watcher, run the C<again> method 641C<$repeat>, and then, in the read/write watcher, run the C<again> method
379on the timeout. 642on the timeout.
380 643
644If called with a C<$repeat> argument, then it uses this a timer repeat
645value.
646
647=item $after = $w->remaining
648
649Calculates and returns the remaining time till the timer will fire.
650
381=back 651=back
382 652
383 653
384=head3 PERIODIC WATCHERS - to cron or not to cron? 654=head3 PERIODIC WATCHERS - to cron or not to cron?
385 655
386=over 4 656=over 4
387 657
388=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 658=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
389 659
390=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 660=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
661
662=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
663
664=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
391 665
392Similar to EV::timer, but is not based on relative timeouts but on 666Similar to EV::timer, but is not based on relative timeouts but on
393absolute times. Apart from creating "simple" timers that trigger "at" the 667absolute times. Apart from creating "simple" timers that trigger "at" the
394specified time, it can also be used for non-drifting absolute timers and 668specified time, it can also be used for non-drifting absolute timers and
395more complex, cron-like, setups that are not adversely affected by time 669more complex, cron-like, setups that are not adversely affected by time
405This time simply fires at the wallclock time C<$at> and doesn't repeat. It 679This time simply fires at the wallclock time C<$at> and doesn't repeat. It
406will not adjust when a time jump occurs, that is, if it is to be run 680will not adjust when a time jump occurs, that is, if it is to be run
407at January 1st 2011 then it will run when the system time reaches or 681at January 1st 2011 then it will run when the system time reaches or
408surpasses this time. 682surpasses this time.
409 683
410=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 684=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
411 685
412In this mode the watcher will always be scheduled to time out at the 686In this mode the watcher will always be scheduled to time out at the
413next C<$at + N * $interval> time (for some integer N) and then repeat, 687next C<$at + N * $interval> time (for some integer N) and then repeat,
414regardless of any time jumps. 688regardless of any time jumps.
415 689
417time: 691time:
418 692
419 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; 693 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
420 694
421That doesn't mean there will always be 3600 seconds in between triggers, 695That doesn't mean there will always be 3600 seconds in between triggers,
422but only that the the clalback will be called when the system time shows a 696but only that the the callback will be called when the system time shows a
423full hour (UTC). 697full hour (UTC).
424 698
425Another way to think about it (for the mathematically inclined) is that 699Another way to think about it (for the mathematically inclined) is that
426EV::periodic will try to run the callback in this mode at the next 700EV::periodic will try to run the callback in this mode at the next
427possible time where C<$time = $at (mod $interval)>, regardless of any time 701possible time where C<$time = $at (mod $interval)>, regardless of any time
433time the periodic watcher gets scheduled, the reschedule callback 707time the periodic watcher gets scheduled, the reschedule callback
434($reschedule_cb) will be called with the watcher as first, and the current 708($reschedule_cb) will be called with the watcher as first, and the current
435time as second argument. 709time as second argument.
436 710
437I<This callback MUST NOT stop or destroy this or any other periodic 711I<This callback MUST NOT stop or destroy this or any other periodic
438watcher, ever>. If you need to stop it, return 1e30 and stop it 712watcher, ever, and MUST NOT call any event loop functions or methods>. If
439afterwards. 713you need to stop it, return 1e30 and stop it afterwards. You may create
714and start a C<EV::prepare> watcher for this task.
440 715
441It must return the next time to trigger, based on the passed time value 716It must return the next time to trigger, based on the passed time value
442(that is, the lowest time value larger than to the second argument). It 717(that is, the lowest time value larger than or equal to to the second
443will usually be called just before the callback will be triggered, but 718argument). It will usually be called just before the callback will be
444might be called at other times, too. 719triggered, but might be called at other times, too.
445 720
446This can be used to create very complex timers, such as a timer that 721This can be used to create very complex timers, such as a timer that
447triggers on each midnight, local time (actually 24 hours after the last 722triggers on each midnight, local time (actually 24 hours after the last
448midnight, to keep the example simple. If you know a way to do it correctly 723midnight, to keep the example simple. If you know a way to do it correctly
449in about the same space (without requiring elaborate modules), drop me a 724in about the same space (without requiring elaborate modules), drop me a
470 745
471=item $w->again 746=item $w->again
472 747
473Simply stops and starts the watcher again. 748Simply stops and starts the watcher again.
474 749
750=item $time = $w->at
751
752Return the time that the watcher is expected to trigger next.
753
475=back 754=back
476 755
477 756
478=head3 SIGNAL WATCHERS - signal me when a signal gets signalled! 757=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
479 758
480=over 4 759=over 4
481 760
482=item $w = EV::signal $signal, $callback 761=item $w = EV::signal $signal, $callback
483 762
484=item $w = EV::signal_ns $signal, $callback 763=item $w = EV::signal_ns $signal, $callback
764
765=item $w = $loop->signal ($signal, $callback)
766
767=item $w = $loop->signal_ns ($signal, $callback)
485 768
486Call the callback when $signal is received (the signal can be specified by 769Call the callback when $signal is received (the signal can be specified by
487number or by name, just as with C<kill> or C<%SIG>). 770number or by name, just as with C<kill> or C<%SIG>).
771
772Only one event loop can grab a given signal - attempting to grab the same
773signal from two EV loops will crash the program immediately or cause data
774corruption.
488 775
489EV will grab the signal for the process (the kernel only allows one 776EV will grab the signal for the process (the kernel only allows one
490component to receive a signal at a time) when you start a signal watcher, 777component to receive a signal at a time) when you start a signal watcher,
491and removes it again when you stop it. Perl does the same when you 778and removes it again when you stop it. Perl does the same when you
492add/remove callbacks to C<%SIG>, so watch out. 779add/remove callbacks to C<%SIG>, so watch out.
512 799
513=head3 CHILD WATCHERS - watch out for process status changes 800=head3 CHILD WATCHERS - watch out for process status changes
514 801
515=over 4 802=over 4
516 803
517=item $w = EV::child $pid, $callback 804=item $w = EV::child $pid, $trace, $callback
518 805
519=item $w = EV::child_ns $pid, $callback 806=item $w = EV::child_ns $pid, $trace, $callback
520 807
808=item $w = $loop->child ($pid, $trace, $callback)
809
810=item $w = $loop->child_ns ($pid, $trace, $callback)
811
521Call the callback when a status change for pid C<$pid> (or any pid if 812Call the callback when a status change for pid C<$pid> (or any pid
522C<$pid> is 0) has been received. More precisely: when the process receives 813if C<$pid> is 0) has been received (a status change happens when the
814process terminates or is killed, or, when trace is true, additionally when
815it is stopped or continued). More precisely: when the process receives
523a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all 816a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
524changed/zombie children and call the callback. 817changed/zombie children and call the callback.
525 818
526It is valid (and fully supported) to install a child watcher after a child 819It is valid (and fully supported) to install a child watcher after a child
527has exited but before the event loop has started its next iteration (for 820has exited but before the event loop has started its next iteration (for
534You can have as many pid watchers per pid as you want, they will all be 827You can have as many pid watchers per pid as you want, they will all be
535called. 828called.
536 829
537The C<child_ns> variant doesn't start (activate) the newly created watcher. 830The C<child_ns> variant doesn't start (activate) the newly created watcher.
538 831
539=item $w->set ($pid) 832=item $w->set ($pid, $trace)
540 833
541Reconfigures the watcher, see the constructor above for details. Can be called at 834Reconfigures the watcher, see the constructor above for details. Can be called at
542any time. 835any time.
543 836
544=item $current_pid = $w->pid 837=item $current_pid = $w->pid
545 838
546=item $old_pid = $w->pid ($new_pid)
547
548Returns the previously set process id and optionally set a new one. 839Returns the previously set process id and optionally set a new one.
549 840
550=item $exit_status = $w->rstatus 841=item $exit_status = $w->rstatus
551 842
552Return the exit/wait status (as returned by waitpid, see the waitpid entry 843Return the exit/wait status (as returned by waitpid, see the waitpid entry
565=over 4 856=over 4
566 857
567=item $w = EV::stat $path, $interval, $callback 858=item $w = EV::stat $path, $interval, $callback
568 859
569=item $w = EV::stat_ns $path, $interval, $callback 860=item $w = EV::stat_ns $path, $interval, $callback
861
862=item $w = $loop->stat ($path, $interval, $callback)
863
864=item $w = $loop->stat_ns ($path, $interval, $callback)
570 865
571Call the callback when a file status change has been detected on 866Call the callback when a file status change has been detected on
572C<$path>. The C<$path> does not need to exist, changing from "path exists" 867C<$path>. The C<$path> does not need to exist, changing from "path exists"
573to "path does not exist" is a status change like any other. 868to "path does not exist" is a status change like any other.
574 869
645 940
646=item $w = EV::idle $callback 941=item $w = EV::idle $callback
647 942
648=item $w = EV::idle_ns $callback 943=item $w = EV::idle_ns $callback
649 944
650Call the callback when there are no pending io, timer/periodic, signal or 945=item $w = $loop->idle ($callback)
651child events, i.e. when the process is idle. 946
947=item $w = $loop->idle_ns ($callback)
948
949Call the callback when there are no other pending watchers of the same or
950higher priority (excluding check, prepare and other idle watchers of the
951same or lower priority, of course). They are called idle watchers because
952when the watcher is the highest priority pending event in the process, the
953process is considered to be idle at that priority.
954
955If you want a watcher that is only ever called when I<no> other events are
956outstanding you have to set the priority to C<EV::MINPRI>.
652 957
653The process will not block as long as any idle watchers are active, and 958The process will not block as long as any idle watchers are active, and
654they will be called repeatedly until stopped. 959they will be called repeatedly until stopped.
655 960
961For example, if you have idle watchers at priority C<0> and C<1>, and
962an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
963and the I/O watcher will always run when ready. Only when the idle watcher
964at priority C<1> is stopped and the I/O watcher at priority C<0> is not
965pending with the C<0>-priority idle watcher be invoked.
966
656The C<idle_ns> variant doesn't start (activate) the newly created watcher. 967The C<idle_ns> variant doesn't start (activate) the newly created watcher.
657 968
658=back 969=back
659 970
660 971
663=over 4 974=over 4
664 975
665=item $w = EV::prepare $callback 976=item $w = EV::prepare $callback
666 977
667=item $w = EV::prepare_ns $callback 978=item $w = EV::prepare_ns $callback
979
980=item $w = $loop->prepare ($callback)
981
982=item $w = $loop->prepare_ns ($callback)
668 983
669Call the callback just before the process would block. You can still 984Call the callback just before the process would block. You can still
670create/modify any watchers at this point. 985create/modify any watchers at this point.
671 986
672See the EV::check watcher, below, for explanations and an example. 987See the EV::check watcher, below, for explanations and an example.
682 997
683=item $w = EV::check $callback 998=item $w = EV::check $callback
684 999
685=item $w = EV::check_ns $callback 1000=item $w = EV::check_ns $callback
686 1001
1002=item $w = $loop->check ($callback)
1003
1004=item $w = $loop->check_ns ($callback)
1005
687Call the callback just after the process wakes up again (after it has 1006Call the callback just after the process wakes up again (after it has
688gathered events), but before any other callbacks have been invoked. 1007gathered events), but before any other callbacks have been invoked.
689 1008
690This is used to integrate other event-based software into the EV 1009This can be used to integrate other event-based software into the EV
691mainloop: You register a prepare callback and in there, you create io and 1010mainloop: You register a prepare callback and in there, you create io and
692timer watchers as required by the other software. Here is a real-world 1011timer watchers as required by the other software. Here is a real-world
693example of integrating Net::SNMP (with some details left out): 1012example of integrating Net::SNMP (with some details left out):
694 1013
695 our @snmp_watcher; 1014 our @snmp_watcher;
700 or return; 1019 or return;
701 1020
702 # make the dispatcher handle any outstanding stuff 1021 # make the dispatcher handle any outstanding stuff
703 ... not shown 1022 ... not shown
704 1023
705 # create an IO watcher for each and every socket 1024 # create an I/O watcher for each and every socket
706 @snmp_watcher = ( 1025 @snmp_watcher = (
707 (map { EV::io $_, EV::READ, sub { } } 1026 (map { EV::io $_, EV::READ, sub { } }
708 keys %{ $dispatcher->{_descriptors} }), 1027 keys %{ $dispatcher->{_descriptors} }),
709 1028
710 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 1029 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
725 # make the dispatcher handle any new stuff 1044 # make the dispatcher handle any new stuff
726 ... not shown 1045 ... not shown
727 }; 1046 };
728 1047
729The callbacks of the created watchers will not be called as the watchers 1048The callbacks of the created watchers will not be called as the watchers
730are destroyed before this cna happen (remember EV::check gets called 1049are destroyed before this can happen (remember EV::check gets called
731first). 1050first).
732 1051
733The C<check_ns> variant doesn't start (activate) the newly created watcher. 1052The C<check_ns> variant doesn't start (activate) the newly created watcher.
1053
1054=item EV::CHECK constant issues
1055
1056Like all other watcher types, there is a bitmask constant for use in
1057C<$revents> and other places. The C<EV::CHECK> is special as it has
1058the same name as the C<CHECK> sub called by Perl. This doesn't cause
1059big issues on newer perls (beginning with 5.8.9), but it means thatthe
1060constant must be I<inlined>, i.e. runtime calls will not work. That means
1061that as long as you always C<use EV> and then C<EV::CHECK> you are on the
1062safe side.
734 1063
735=back 1064=back
736 1065
737 1066
738=head3 FORK WATCHERS - the audacity to resume the event loop after a fork 1067=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
745 1074
746=item $w = EV::fork $callback 1075=item $w = EV::fork $callback
747 1076
748=item $w = EV::fork_ns $callback 1077=item $w = EV::fork_ns $callback
749 1078
1079=item $w = $loop->fork ($callback)
1080
1081=item $w = $loop->fork_ns ($callback)
1082
750Call the callback before the event loop is resumed in the child process 1083Call the callback before the event loop is resumed in the child process
751after a fork. 1084after a fork.
752 1085
753The C<fork_ns> variant doesn't start (activate) the newly created watcher. 1086The C<fork_ns> variant doesn't start (activate) the newly created watcher.
754 1087
755=back 1088=back
756 1089
757 1090
1091=head3 EMBED WATCHERS - when one backend isn't enough...
1092
1093This is a rather advanced watcher type that lets you embed one event loop
1094into another (currently only IO events are supported in the embedded
1095loop, other types of watchers might be handled in a delayed or incorrect
1096fashion and must not be used).
1097
1098See the libev documentation at
1099L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1100(locally installed as F<EV::libev>) for more details.
1101
1102In short, this watcher is most useful on BSD systems without working
1103kqueue to still be able to handle a large number of sockets:
1104
1105 my $socket_loop;
1106
1107 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1108 if (
1109 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1110 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1111 ) {
1112 # use kqueue for sockets
1113 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1114 }
1115
1116 # use the default loop otherwise
1117 $socket_loop ||= EV::default_loop;
1118
1119=over 4
1120
1121=item $w = EV::embed $otherloop[, $callback]
1122
1123=item $w = EV::embed_ns $otherloop[, $callback]
1124
1125=item $w = $loop->embed ($otherloop[, $callback])
1126
1127=item $w = $loop->embed_ns ($otherloop[, $callback])
1128
1129Call the callback when the embedded event loop (C<$otherloop>) has any
1130I/O activity. The C<$callback> is optional: if it is missing, then the
1131embedded event loop will be managed automatically (which is recommended),
1132otherwise you have to invoke C<sweep> yourself.
1133
1134The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1135
1136=back
1137
1138=head3 ASYNC WATCHERS - how to wake up another event loop
1139
1140Async watchers are provided by EV, but have little use in perl directly,
1141as perl neither supports threads running in parallel nor direct access to
1142signal handlers or other contexts where they could be of value.
1143
1144It is, however, possible to use them from the XS level.
1145
1146Please see the libev documentation for further details.
1147
1148=over 4
1149
1150=item $w = EV::async $callback
1151
1152=item $w = EV::async_ns $callback
1153
1154=item $w = $loop->async ($callback)
1155
1156=item $w = $loop->async_ns ($callback)
1157
1158=item $w->send
1159
1160=item $bool = $w->async_pending
1161
1162=back
1163
1164=head3 CLEANUP WATCHERS - how to clean up when the event loop goes away
1165
1166Cleanup watchers are not supported on the Perl level, they can only be
1167used via XS currently.
1168
1169
1170=head1 PERL SIGNALS
1171
1172While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1173with EV is as the same as any other C library: Perl-signals will only be
1174handled when Perl runs, which means your signal handler might be invoked
1175only the next time an event callback is invoked.
1176
1177The solution is to use EV signal watchers (see C<EV::signal>), which will
1178ensure proper operations with regards to other event watchers.
1179
1180If you cannot do this for whatever reason, you can also force a watcher
1181to be called on every event loop iteration by installing a C<EV::check>
1182watcher:
1183
1184 my $async_check = EV::check sub { };
1185
1186This ensures that perl gets into control for a short time to handle any
1187pending signals, and also ensures (slightly) slower overall operation.
1188
758=head1 THREADS 1189=head1 ITHREADS
759 1190
760Threads are not supported by this module in any way. Perl pseudo-threads 1191Ithreads are not supported by this module in any way. Perl pseudo-threads
761is evil stuff and must die. As soon as Perl gains real threads I will work 1192is evil stuff and must die. Real threads as provided by Coro are fully
762on thread support for it. 1193supported (and enhanced support is available via L<Coro::EV>).
763 1194
764=head1 FORK 1195=head1 FORK
765 1196
766Most of the "improved" event delivering mechanisms of modern operating 1197Most of the "improved" event delivering mechanisms of modern operating
767systems have quite a few problems with fork(2) (to put it bluntly: it is 1198systems have quite a few problems with fork(2) (to put it bluntly: it is
783our $DIED = sub { 1214our $DIED = sub {
784 warn "EV: error in callback (ignoring): $@"; 1215 warn "EV: error in callback (ignoring): $@";
785}; 1216};
786 1217
787default_loop 1218default_loop
788 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1219 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
789 1220
7901; 12211;
791 1222
792=head1 SEE ALSO 1223=head1 SEE ALSO
793 1224
1225L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
794L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as 1226(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
795event loop), L<Coro::EV> (efficient coroutines with EV). 1227loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
1228integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1229event-loop agnostic and portable event driven programming.
796 1230
797=head1 AUTHOR 1231=head1 AUTHOR
798 1232
799 Marc Lehmann <schmorp@schmorp.de> 1233 Marc Lehmann <schmorp@schmorp.de>
800 http://home.schmorp.de/ 1234 http://home.schmorp.de/
801 1235
802=cut 1236=cut
803 1237

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