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Revision 1.17 by root, Wed Oct 31 21:34:45 2007 UTC vs.
Revision 1.22 by root, Fri Nov 2 11:02:22 2007 UTC

1=head1 NAME 1=head1 NAME
2 2
3EV - perl interface to libevent, monkey.org/~provos/libevent/ 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 8
9 # TIMER 9 # TIMERS
10 10
11 my $w = EV::timer 2, 0, sub { 11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s"; 12 warn "is called after 2s";
13 }; 13 };
14 14
… …
16 warn "is called roughly every 2s (repeat = 1)"; 16 warn "is called roughly every 2s (repeat = 1)";
17 }; 17 };
18 18
19 undef $w; # destroy event watcher again 19 undef $w; # destroy event watcher again
20 20
21 my $w = EV::timer_abs 0, 60, sub { 21 my $w = EV::periodic 0, 60, sub {
22 warn "is called every minute, on the minute, exactly"; 22 warn "is called every minute, on the minute, exactly";
23 }; 23 };
24 24
25 # IO 25 # IO
26 26
27 my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { 27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask 28 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
29 if ($revents & EV::TIMEOUT) {
30 warn "nothing received on stdin for 10 seconds, retrying";
31 } else {
32 warn "stdin is readable, you entered: ", <STDIN>; 29 warn "stdin is readable, you entered: ", <STDIN>;
33 }
34 };
35 $w->timeout (10);
36
37 my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
38 my ($w, $revents) = @_;
39 if ($revents & EV::TIMEOUT) {
40 warn "nothing entered within 30 seconds, bye bye.\n";
41 $w->stop;
42 } else {
43 my $line = <STDIN>;
44 warn "you entered something, you again have 30 seconds.\n";
45 }
46 }; 30 };
47 31
48 # SIGNALS 32 # SIGNALS
49 33
50 my $w = EV::signal 'QUIT', sub { 34 my $w = EV::signal 'QUIT', sub {
… …
60 my $w = EV::child 666, sub { 44 my $w = EV::child 666, sub {
61 my ($w, $revents, $status) = @_; 45 my ($w, $revents, $status) = @_;
62 }; 46 };
63 47
64 # MAINLOOP 48 # MAINLOOP
65 EV::dispatch; # loop as long as watchers are active 49 EV::loop; # loop until EV::loop_done is called
66 EV::loop; # the same thing
67 EV::loop EV::LOOP_ONESHOT; # block until some events could be handles 50 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
68 EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait 51 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
69 52
70=head1 DESCRIPTION 53=head1 DESCRIPTION
71 54
72This module provides an interface to libev 55This module provides an interface to libev
73(L<http://software.schmorp.de/pkg/libev.html>). You probably should 56(L<http://software.schmorp.de/pkg/libev.html>).
74acquaint yourself with its documentation and source code to be able to use
75this module fully.
76 57
77=cut 58=cut
78 59
79package EV; 60package EV;
80 61
81use strict; 62use strict;
82 63
83BEGIN { 64BEGIN {
84 our $VERSION = '0.03'; 65 our $VERSION = '0.1';
85 use XSLoader; 66 use XSLoader;
86 XSLoader::load "EV", $VERSION; 67 XSLoader::load "EV", $VERSION;
87} 68}
88 69
89@EV::Io::ISA = "EV::Watcher"; 70@EV::Io::ISA =
90@EV::Time::ISA = "EV::Watcher";
91@EV::Timer::ISA = "EV::Time"; 71@EV::Timer::ISA =
92@EV::Periodic::ISA = "EV::Time"; 72@EV::Periodic::ISA =
93@EV::Signal::ISA = "EV::Watcher"; 73@EV::Signal::ISA =
94@EV::Idle::ISA = "EV::Watcher"; 74@EV::Idle::ISA =
95@EV::Prepare::ISA = "EV::Watcher"; 75@EV::Prepare::ISA =
96@EV::Check::ISA = "EV::Watcher"; 76@EV::Check::ISA =
97@EV::Child::ISA = "EV::Watcher"; 77@EV::Child::ISA = "EV::Watcher";
98 78
99=head1 BASIC INTERFACE 79=head1 BASIC INTERFACE
100 80
101=over 4 81=over 4
102
103=item $EV::NPRI
104
105How many priority levels are available.
106 82
107=item $EV::DIED 83=item $EV::DIED
108 84
109Must contain a reference to a function that is called when a callback 85Must contain a reference to a function that is called when a callback
110throws an exception (with $@ containing thr error). The default prints an 86throws an exception (with $@ containing thr error). The default prints an
111informative message and continues. 87informative message and continues.
112 88
113If this callback throws an exception it will be silently ignored. 89If this callback throws an exception it will be silently ignored.
114 90
91=item $time = EV::time
92
93Returns the current time in (fractional) seconds since the epoch.
94
115=item $time = EV::now 95=item $time = EV::now
116 96
117Returns the time in (fractional) seconds since the epoch. 97Returns the time the last event loop iteration has been started. This
98is the time that (relative) timers are based on, and refering to it is
99usually faster then calling EV::time.
118 100
119=item $version = EV::version
120
121=item $method = EV::method 101=item $method = EV::ev_method
122 102
123Return version string and event polling method used. 103Returns an integer describing the backend used by libev (EV::METHOD_SELECT
104or EV::METHOD_EPOLL).
124 105
125=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT 106=item EV::loop [$flags]
126 107
127=item EV::loopexit $after 108Begin checking for events and calling callbacks. It returns when a
109callback calls EV::loop_done.
128 110
129Exit any active loop or dispatch after C<$after> seconds or immediately if 111The $flags argument can be one of the following:
130C<$after> is missing or zero.
131 112
132=item EV::dispatch 113 0 as above
114 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
115 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
133 116
134Same as C<EV::loop 0>. 117=item EV::loop_done [$how]
135 118
136=item EV::event $callback 119When called with no arguments or an argument of 1, makes the innermost
120call to EV::loop return.
137 121
138Creates a new event watcher waiting for nothing, calling the given callback. 122When called with an agrument of 2, all calls to EV::loop will return as
123fast as possible.
139 124
125=back
126
127=head2 WATCHER
128
129A watcher is an object that gets created to record your interest in some
130event. For instance, if you want to wait for STDIN to become readable, you
131would create an EV::io watcher for that:
132
133 my $watcher = EV::io *STDIN, EV::READ, sub {
134 my ($watcher, $revents) = @_;
135 warn "yeah, STDIN should not be readable without blocking!\n"
136 };
137
138All watchers can be active (waiting for events) or inactive (paused). Only
139active watchers will have their callbacks invoked. All callbacks will be
140called with at least two arguments: the watcher and a bitmask of received
141events.
142
143Each watcher type has its associated bit in revents, so you can use the
144same callback for multiple watchers. The event mask is named after the
145type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
146EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
147(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
148uses EV::TIMEOUT).
149
150In the rare case where one wants to create a watcher but not start it at
151the same time, each constructor has a variant with a trailing C<_ns> in
152its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
153
154Please note that a watcher will automatically be stopped when the watcher
155object is returned, so you I<need> to keep the watcher objects returned by
156the constructors.
157
158=head2 WATCHER TYPES
159
160Now lets move to the existing watcher types and asociated methods.
161
162The following methods are available for all watchers. Then followes a
163description of each watcher constructor (EV::io, EV::timer, EV::periodic,
164EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
165any type-specific methods (if any).
166
167=over 4
168
169=item $w->start
170
171Starts a watcher if it isn't active already. Does nothing to an already
172active watcher. By default, all watchers start out in the active state
173(see the description of the C<_ns> variants if you need stopped watchers).
174
175=item $w->stop
176
177Stop a watcher if it is active. Also clear any pending events (events that
178have been received but that didn't yet result in a callback invocation),
179regardless of wether the watcher was active or not.
180
181=item $bool = $w->is_active
182
183Returns true if the watcher is active, false otherwise.
184
185=item $current_cb = $w->cb
186
187=item $old_cb = $w->cb ($new_cb)
188
189Queries the callback on the watcher and optionally changes it. You cna do
190this at any time.
191
192=item $w->trigger ($revents)
193
194Call the callback *now* with the given event mask.
195
196
140=item my $w = EV::io $fileno_or_fh, $eventmask, $callback 197=item $w = EV::io $fileno_or_fh, $eventmask, $callback
141 198
142=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 199=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
143 200
144As long as the returned watcher object is alive, call the C<$callback> 201As long as the returned watcher object is alive, call the C<$callback>
145when the events specified in C<$eventmask> happen. Initially, the timeout 202when the events specified in C<$eventmask>.
146is disabled.
147 203
148You can additionall set a timeout to occur on the watcher, but note that
149this timeout will not be reset when you get an I/O event in the EV::PERSIST
150case, and reaching a timeout will always stop the watcher even in the
151EV::PERSIST case.
152
153If you want a timeout to occur only after a specific time of inactivity, set
154a repeating timeout and do NOT use EV::PERSIST.
155
156Eventmask can be one or more of these constants ORed together: 204The $eventmask can be one or more of these constants ORed together:
157 205
158 EV::READ wait until read() wouldn't block anymore 206 EV::READ wait until read() wouldn't block anymore
159 EV::WRITE wait until write() wouldn't block anymore 207 EV::WRITE wait until write() wouldn't block anymore
160 EV::PERSIST stay active after a (non-timeout) event occured
161 208
162The C<io_ns> variant doesn't add/start the newly created watcher. 209The C<io_ns> variant doesn't start (activate) the newly created watcher.
163 210
164=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback 211=item $w->set ($fileno_or_fh, $eventmask)
165 212
166=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback 213Reconfigures the watcher, see the constructor above for details. Can be
214called at any time.
167 215
168Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was 216=item $current_fh = $w->fh
169a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
170and will automatically be cleared. The watcher will be restarted after each event.
171 217
172If the timeout is zero or undef, no timeout will be set, and a normal 218=item $old_fh = $w->fh ($new_fh)
173watcher (with the persist flag set!) will be created.
174 219
175This has the effect of timing out after the specified period of inactivity 220Returns the previously set filehandle and optionally set a new one.
176has happened.
177 221
178Due to the design of libevent, this is also relatively inefficient, having 222=item $current_eventmask = $w->events
179one or two io watchers and a separate timeout watcher that you reset on
180activity (by calling its C<start> method) is usually more efficient.
181 223
224=item $old_eventmask = $w->events ($new_eventmask)
225
226Returns the previously set event mask and optionally set a new one.
227
228
182=item my $w = EV::timer $after, $repeat, $callback 229=item $w = EV::timer $after, $repeat, $callback
183 230
184=item my $w = EV::timer_ns $after, $repeat, $callback 231=item $w = EV::timer_ns $after, $repeat, $callback
185 232
186Calls the callback after C<$after> seconds. If C<$repeat> is true, the 233Calls the callback after C<$after> seconds. If C<$repeat> is non-zero,
187timer will be restarted after the callback returns. This means that the 234the timer will be restarted (with the $repeat value as $after) after the
188callback would be called roughly every C<$after> seconds, prolonged by the 235callback returns.
189time the callback takes.
190 236
237This means that the callback would be called roughly after C<$after>
238seconds, and then every C<$repeat> seconds. "Roughly" because the time of
239callback processing is not taken into account, so the timer will slowly
240drift. If that isn't acceptable, look at EV::periodic.
241
242The timer is based on a monotonic clock, that is if somebody is sitting
243in front of the machine while the timer is running and changes the system
244clock, the timer will nevertheless run (roughly) the same time.
245
191The C<timer_ns> variant doesn't add/start the newly created watcher. 246The C<timer_ns> variant doesn't start (activate) the newly created watcher.
192 247
248=item $w->set ($after, $repeat)
249
250Reconfigures the watcher, see the constructor above for details. Can be at
251any time.
252
253=item $w->again
254
255Similar to the C<start> method, but has special semantics for repeating timers:
256
257If the timer is active and repeating, reset the timeout to occur
258C<$repeat> seconds after now.
259
260If the timer is active and non-repeating, it will be stopped.
261
262If the timer is in active and repeating, start it.
263
264Otherwise do nothing.
265
266This behaviour is useful when you have a timeout for some IO
267operation. You create a timer object with the same value for C<$after> and
268C<$repeat>, and then, in the read/write watcher, run the C<again> method
269on the timeout.
270
271
272=item $w = EV::periodic $at, $interval, $callback
273
193=item my $w = EV::timer_abs $at, $interval, $callback 274=item $w = EV::periodic_ns $at, $interval, $callback
194
195=item my $w = EV::timer_abs_ns $at, $interval, $callback
196 275
197Similar to EV::timer, but the time is given as an absolute point in time 276Similar to EV::timer, but the time is given as an absolute point in time
198(C<$at>), plus an optional C<$interval>. 277(C<$at>), plus an optional C<$interval>.
199 278
200If the C<$interval> is zero, then the callback will be called at the time 279If the C<$interval> is zero, then the callback will be called at the time
201C<$at> if that is in the future, or as soon as possible if its in the 280C<$at> if that is in the future, or as soon as possible if it is in the
202past. It will not automatically repeat. 281past. It will not automatically repeat.
203 282
204If the C<$interval> is nonzero, then the watcher will always be scheduled 283If the C<$interval> is nonzero, then the watcher will always be scheduled
205to time out at the next C<$at + integer * $interval> time. 284to time out at the next C<$at + N * $interval> time.
206 285
207This can be used to schedule a callback to run at very regular intervals, 286This can be used to schedule a callback to run at very regular intervals,
208as long as the processing time is less then the interval (otherwise 287as long as the processing time is less then the interval (otherwise
209obviously events will be skipped). 288obviously events will be skipped).
210 289
211Another way to think about it (for the mathematically inclined) is that 290Another way to think about it (for the mathematically inclined) is that
212C<timer_abs> will try to tun the callback at the next possible time where 291EV::periodic will try to run the callback at the next possible time where
213C<$time = $at (mod $interval)>, regardless of any time jumps. 292C<$time = $at (mod $interval)>, regardless of any time jumps.
214 293
294This periodic timer is based on "wallclock time", that is, if the clock
295changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at
296the specified time. This means it will never drift (it might jitter, but
297it will not drift).
298
215The C<timer_abs_ns> variant doesn't add/start the newly created watcher. 299The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
216 300
301=item $w->set ($at, $interval)
302
303Reconfigures the watcher, see the constructor above for details. Can be at
304any time.
305
306
217=item my $w = EV::signal $signal, $callback 307=item $w = EV::signal $signal, $callback
218 308
219=item my $w = EV::signal_ns $signal, $callback 309=item $w = EV::signal_ns $signal, $callback
220 310
221Call the callback when $signal is received (the signal can be specified 311Call the callback when $signal is received (the signal can be specified
222by number or by name, just as with kill or %SIG). Signal watchers are 312by number or by name, just as with kill or %SIG).
223persistent no natter what.
224 313
225EV will grab the signal for the process (the kernel only allows one 314EV will grab the signal for the process (the kernel only allows one
226component to receive signals) when you start a signal watcher, and 315component to receive a signal at a time) when you start a signal watcher,
227removes it again when you stop it. Pelr does the same when you add/remove 316and removes it again when you stop it. Perl does the same when you
228callbacks to %SIG, so watch out. 317add/remove callbacks to %SIG, so watch out.
229 318
230Unfortunately, only one handler can be registered per signal. Screw 319You can have as many signal watchers per signal as you want.
231libevent.
232 320
233The C<signal_ns> variant doesn't add/start the newly created watcher. 321The C<signal_ns> variant doesn't start (activate) the newly created watcher.
322
323=item $w->set ($signal)
324
325Reconfigures the watcher, see the constructor above for details. Can be at
326any time.
327
328=item $current_signum = $w->signal
329
330=item $old_signum = $w->signal ($new_signal)
331
332Returns the previously set signal (always as a number not name) and
333optionally set a new one.
334
335
336=item $w = EV::child $pid, $callback
337
338=item $w = EV::child_ns $pid, $callback
339
340Call the callback when a status change for pid C<$pid> (or any pid
341if C<$pid> is 0) has been received. More precisely: when the process
342receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
343changed/zombie children and call the callback.
344
345Unlike all other callbacks, this callback will be called with an
346additional third argument which is the exit status. See the C<waitpid>
347function for details.
348
349You can have as many pid watchers per pid as you want.
350
351The C<child_ns> variant doesn't start (activate) the newly created watcher.
352
353=item $w->set ($pid)
354
355Reconfigures the watcher, see the constructor above for details. Can be at
356any time.
357
358=item $current_pid = $w->pid
359
360=item $old_pid = $w->pid ($new_pid)
361
362Returns the previously set process id and optionally set a new one.
363
364
365=item $w = EV::idle $callback
366
367=item $w = EV::idle_ns $callback
368
369Call the callback when there are no pending io, timer/periodic, signal or
370child events, i.e. when the process is idle.
371
372The process will not block as long as any idle watchers are active, and
373they will be called repeatedly until stopped.
374
375The C<idle_ns> variant doesn't start (activate) the newly created watcher.
376
377
378=item $w = EV::prepare $callback
379
380=item $w = EV::prepare_ns $callback
381
382Call the callback just before the process would block. You can still
383create/modify any watchers at this point.
384
385See the EV::check watcher, below, for explanations and an example.
386
387The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
388
389
390=item $w = EV::check $callback
391
392=item $w = EV::check_ns $callback
393
394Call the callback just after the process wakes up again (after it has
395gathered events), but before any other callbacks have been invoked.
396
397This is used to integrate other event-based software into the EV
398mainloop: You register a prepare callback and in there, you create io and
399timer watchers as required by the other software. Here is a real-world
400example of integrating Net::SNMP (with some details left out):
401
402 our @snmp_watcher;
403
404 our $snmp_prepare = EV::prepare sub {
405 # do nothing unless active
406 $dispatcher->{_event_queue_h}
407 or return;
408
409 # make the dispatcher handle any outstanding stuff
410
411 # create an IO watcher for each and every socket
412 @snmp_watcher = (
413 (map { EV::io $_, EV::READ, sub { } }
414 keys %{ $dispatcher->{_descriptors} }),
415 );
416
417 # if there are any timeouts, also create a timer
418 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
419 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
420 };
421
422The callbacks are irrelevant, the only purpose of those watchers is
423to wake up the process as soon as one of those events occurs (socket
424readable, or timer timed out). The corresponding EV::check watcher will then
425clean up:
426
427 our $snmp_check = EV::check sub {
428 # destroy all watchers
429 @snmp_watcher = ();
430
431 # make the dispatcher handle any new stuff
432 };
433
434The callbacks of the created watchers will not be called as the watchers
435are destroyed before this cna happen (remember EV::check gets called
436first).
437
438The C<check_ns> variant doesn't start (activate) the newly created watcher.
234 439
235=back 440=back
236 441
237=head1 THE EV::Event CLASS
238
239All EV functions creating an event watcher (designated by C<my $w =>
240above) support the following methods on the returned watcher object:
241
242=over 4
243
244=item $w->add ($timeout)
245
246Stops and (re-)starts the event watcher, setting the optional timeout to
247the given value, or clearing the timeout if none is given.
248
249=item $w->start
250
251Stops and (re-)starts the event watcher without touching the timeout.
252
253=item $w->del
254
255=item $w->stop
256
257Stop the event watcher if it was started.
258
259=item $current_callback = $w->cb
260
261=item $old_callback = $w->cb ($new_callback)
262
263Return the previously set callback and optionally set a new one.
264
265=item $current_fh = $w->fh
266
267=item $old_fh = $w->fh ($new_fh)
268
269Returns the previously set filehandle and optionally set a new one (also
270clears the EV::SIGNAL flag when setting a filehandle).
271
272=item $current_signal = $w->signal
273
274=item $old_signal = $w->signal ($new_signal)
275
276Returns the previously set signal number and optionally set a new one (also sets
277the EV::SIGNAL flag when setting a signal).
278
279=item $current_eventmask = $w->events
280
281=item $old_eventmask = $w->events ($new_eventmask)
282
283Returns the previously set event mask and optionally set a new one.
284
285=item $w->timeout ($after, $repeat)
286
287Resets the timeout (see C<EV::timer> for details).
288
289=item $w->timeout_abs ($at, $interval)
290
291Resets the timeout (see C<EV::timer_abs> for details).
292
293=item $w->priority_set ($priority)
294
295Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
296
297=back
298
299=head1 THREADS 442=head1 THREADS
300 443
301Threads are not supported by this in any way. Perl pseudo-threads is evil 444Threads are not supported by this in any way. Perl pseudo-threads is evil
302and must die. 445stuff and must die.
303
304=head1 BUGS
305
306Lots. Libevent itself isn't well tested and rather buggy, and this module
307is quite new at the moment.
308
309Please note that the epoll method is not, in general, reliable in programs
310that use fork (even if no libveent calls are being made in the forked
311process). If your program behaves erratically, try setting the environment
312variable C<EVENT_NOEPOLL> first when running the program.
313
314In general, if you fork, then you can only use the EV module in one of the
315children.
316 446
317=cut 447=cut
318 448
319our $DIED = sub { 449our $DIED = sub {
320 warn "EV: error in callback (ignoring): $@"; 450 warn "EV: error in callback (ignoring): $@";
… …
326 456
3271; 4571;
328 458
329=head1 SEE ALSO 459=head1 SEE ALSO
330 460
331 L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.
332 L<EV::AnyEvent>. 461 L<EV::DNS>, L<EV::AnyEvent>.
333 462
334=head1 AUTHOR 463=head1 AUTHOR
335 464
336 Marc Lehmann <schmorp@schmorp.de> 465 Marc Lehmann <schmorp@schmorp.de>
337 http://home.schmorp.de/ 466 http://home.schmorp.de/

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