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1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - the DBI of event loop programming
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported 5EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
6event loops. 6and POE are various supported event loops/environments.
7 7
8=head1 SYNOPSIS 8=head1 SYNOPSIS
9 9
10 use AnyEvent; 10 use AnyEvent;
11 11
12 # if you prefer function calls, look at the AE manpage for
13 # an alternative API.
14
12 # file descriptor readable 15 # file handle or descriptor readable
13 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); 16 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
14 17
15 # one-shot or repeating timers 18 # one-shot or repeating timers
16 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); 19 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
17 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... 20 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
18 21
19 print AnyEvent->now; # prints current event loop time 22 print AnyEvent->now; # prints current event loop time
20 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. 23 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
21 24
22 # POSIX signal 25 # POSIX signal
40=head1 INTRODUCTION/TUTORIAL 43=head1 INTRODUCTION/TUTORIAL
41 44
42This manpage is mainly a reference manual. If you are interested 45This manpage is mainly a reference manual. If you are interested
43in a tutorial or some gentle introduction, have a look at the 46in a tutorial or some gentle introduction, have a look at the
44L<AnyEvent::Intro> manpage. 47L<AnyEvent::Intro> manpage.
48
49=head1 SUPPORT
50
51An FAQ document is available as L<AnyEvent::FAQ>.
52
53There also is a mailinglist for discussing all things AnyEvent, and an IRC
54channel, too.
55
56See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
57Repository>, at L<http://anyevent.schmorp.de>, for more info.
45 58
46=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 59=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
47 60
48Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 61Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
49nowadays. So what is different about AnyEvent? 62nowadays. So what is different about AnyEvent?
65module users into the same thing by forcing them to use the same event 78module users into the same thing by forcing them to use the same event
66model you use. 79model you use.
67 80
68For modules like POE or IO::Async (which is a total misnomer as it is 81For modules like POE or IO::Async (which is a total misnomer as it is
69actually doing all I/O I<synchronously>...), using them in your module is 82actually doing all I/O I<synchronously>...), using them in your module is
70like joining a cult: After you joined, you are dependent on them and you 83like joining a cult: After you join, you are dependent on them and you
71cannot use anything else, as they are simply incompatible to everything 84cannot use anything else, as they are simply incompatible to everything
72that isn't them. What's worse, all the potential users of your 85that isn't them. What's worse, all the potential users of your
73module are I<also> forced to use the same event loop you use. 86module are I<also> forced to use the same event loop you use.
74 87
75AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 88AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
76fine. AnyEvent + Tk works fine etc. etc. but none of these work together 89fine. AnyEvent + Tk works fine etc. etc. but none of these work together
77with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if 90with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
78your module uses one of those, every user of your module has to use it, 91uses one of those, every user of your module has to use it, too. But if
79too. But if your module uses AnyEvent, it works transparently with all 92your module uses AnyEvent, it works transparently with all event models it
80event models it supports (including stuff like IO::Async, as long as those 93supports (including stuff like IO::Async, as long as those use one of the
81use one of the supported event loops. It is trivial to add new event loops 94supported event loops. It is easy to add new event loops to AnyEvent, too,
82to AnyEvent, too, so it is future-proof). 95so it is future-proof).
83 96
84In addition to being free of having to use I<the one and only true event 97In addition to being free of having to use I<the one and only true event
85model>, AnyEvent also is free of bloat and policy: with POE or similar 98model>, AnyEvent also is free of bloat and policy: with POE or similar
86modules, you get an enormous amount of code and strict rules you have to 99modules, you get an enormous amount of code and strict rules you have to
87follow. AnyEvent, on the other hand, is lean and up to the point, by only 100follow. AnyEvent, on the other hand, is lean and to the point, by only
88offering the functionality that is necessary, in as thin as a wrapper as 101offering the functionality that is necessary, in as thin as a wrapper as
89technically possible. 102technically possible.
90 103
91Of course, AnyEvent comes with a big (and fully optional!) toolbox 104Of course, AnyEvent comes with a big (and fully optional!) toolbox
92of useful functionality, such as an asynchronous DNS resolver, 100% 105of useful functionality, such as an asynchronous DNS resolver, 100%
98useful) and you want to force your users to use the one and only event 111useful) and you want to force your users to use the one and only event
99model, you should I<not> use this module. 112model, you should I<not> use this module.
100 113
101=head1 DESCRIPTION 114=head1 DESCRIPTION
102 115
103L<AnyEvent> provides an identical interface to multiple event loops. This 116L<AnyEvent> provides a uniform interface to various event loops. This
104allows module authors to utilise an event loop without forcing module 117allows module authors to use event loop functionality without forcing
105users to use the same event loop (as only a single event loop can coexist 118module users to use a specific event loop implementation (since more
106peacefully at any one time). 119than one event loop cannot coexist peacefully).
107 120
108The interface itself is vaguely similar, but not identical to the L<Event> 121The interface itself is vaguely similar, but not identical to the L<Event>
109module. 122module.
110 123
111During the first call of any watcher-creation method, the module tries 124During the first call of any watcher-creation method, the module tries
112to detect the currently loaded event loop by probing whether one of the 125to detect the currently loaded event loop by probing whether one of the
113following modules is already loaded: L<EV>, 126following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
114L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, 127L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
115L<POE>. The first one found is used. If none are found, the module tries 128found is used. If none are detected, the module tries to load the first
116to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl 129four modules in the order given; but note that if L<EV> is not
117adaptor should always succeed) in the order given. The first one that can 130available, the pure-perl L<AnyEvent::Loop> should always work, so
118be successfully loaded will be used. If, after this, still none could be 131the other two are not normally tried.
119found, AnyEvent will fall back to a pure-perl event loop, which is not
120very efficient, but should work everywhere.
121 132
122Because AnyEvent first checks for modules that are already loaded, loading 133Because AnyEvent first checks for modules that are already loaded, loading
123an event model explicitly before first using AnyEvent will likely make 134an event model explicitly before first using AnyEvent will likely make
124that model the default. For example: 135that model the default. For example:
125 136
127 use AnyEvent; 138 use AnyEvent;
128 139
129 # .. AnyEvent will likely default to Tk 140 # .. AnyEvent will likely default to Tk
130 141
131The I<likely> means that, if any module loads another event model and 142The I<likely> means that, if any module loads another event model and
132starts using it, all bets are off. Maybe you should tell their authors to 143starts using it, all bets are off - this case should be very rare though,
133use AnyEvent so their modules work together with others seamlessly... 144as very few modules hardcode event loops without announcing this very
145loudly.
134 146
135The pure-perl implementation of AnyEvent is called 147The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
136C<AnyEvent::Impl::Perl>. Like other event modules you can load it 148other event modules you can load it explicitly and enjoy the high
137explicitly and enjoy the high availability of that event loop :) 149availability of that event loop :)
138 150
139=head1 WATCHERS 151=head1 WATCHERS
140 152
141AnyEvent has the central concept of a I<watcher>, which is an object that 153AnyEvent has the central concept of a I<watcher>, which is an object that
142stores relevant data for each kind of event you are waiting for, such as 154stores relevant data for each kind of event you are waiting for, such as
147callback when the event occurs (of course, only when the event model 159callback when the event occurs (of course, only when the event model
148is in control). 160is in control).
149 161
150Note that B<callbacks must not permanently change global variables> 162Note that B<callbacks must not permanently change global variables>
151potentially in use by the event loop (such as C<$_> or C<$[>) and that B<< 163potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152callbacks must not C<die> >>. The former is good programming practise in 164callbacks must not C<die> >>. The former is good programming practice in
153Perl and the latter stems from the fact that exception handling differs 165Perl and the latter stems from the fact that exception handling differs
154widely between event loops. 166widely between event loops.
155 167
156To disable the watcher you have to destroy it (e.g. by setting the 168To disable a watcher you have to destroy it (e.g. by setting the
157variable you store it in to C<undef> or otherwise deleting all references 169variable you store it in to C<undef> or otherwise deleting all references
158to it). 170to it).
159 171
160All watchers are created by calling a method on the C<AnyEvent> class. 172All watchers are created by calling a method on the C<AnyEvent> class.
161 173
162Many watchers either are used with "recursion" (repeating timers for 174Many watchers either are used with "recursion" (repeating timers for
163example), or need to refer to their watcher object in other ways. 175example), or need to refer to their watcher object in other ways.
164 176
165An any way to achieve that is this pattern: 177One way to achieve that is this pattern:
166 178
167 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 179 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
168 # you can use $w here, for example to undef it 180 # you can use $w here, for example to undef it
169 undef $w; 181 undef $w;
170 }); 182 });
172Note that C<my $w; $w => combination. This is necessary because in Perl, 184Note that C<my $w; $w => combination. This is necessary because in Perl,
173my variables are only visible after the statement in which they are 185my variables are only visible after the statement in which they are
174declared. 186declared.
175 187
176=head2 I/O WATCHERS 188=head2 I/O WATCHERS
189
190 $w = AnyEvent->io (
191 fh => <filehandle_or_fileno>,
192 poll => <"r" or "w">,
193 cb => <callback>,
194 );
177 195
178You can create an I/O watcher by calling the C<< AnyEvent->io >> method 196You can create an I/O watcher by calling the C<< AnyEvent->io >> method
179with the following mandatory key-value pairs as arguments: 197with the following mandatory key-value pairs as arguments:
180 198
181C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch 199C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
196 214
197The I/O watcher might use the underlying file descriptor or a copy of it. 215The I/O watcher might use the underlying file descriptor or a copy of it.
198You must not close a file handle as long as any watcher is active on the 216You must not close a file handle as long as any watcher is active on the
199underlying file descriptor. 217underlying file descriptor.
200 218
201Some event loops issue spurious readyness notifications, so you should 219Some event loops issue spurious readiness notifications, so you should
202always use non-blocking calls when reading/writing from/to your file 220always use non-blocking calls when reading/writing from/to your file
203handles. 221handles.
204 222
205Example: wait for readability of STDIN, then read a line and disable the 223Example: wait for readability of STDIN, then read a line and disable the
206watcher. 224watcher.
211 undef $w; 229 undef $w;
212 }); 230 });
213 231
214=head2 TIME WATCHERS 232=head2 TIME WATCHERS
215 233
234 $w = AnyEvent->timer (after => <seconds>, cb => <callback>);
235
236 $w = AnyEvent->timer (
237 after => <fractional_seconds>,
238 interval => <fractional_seconds>,
239 cb => <callback>,
240 );
241
216You can create a time watcher by calling the C<< AnyEvent->timer >> 242You can create a time watcher by calling the C<< AnyEvent->timer >>
217method with the following mandatory arguments: 243method with the following mandatory arguments:
218 244
219C<after> specifies after how many seconds (fractional values are 245C<after> specifies after how many seconds (fractional values are
220supported) the callback should be invoked. C<cb> is the callback to invoke 246supported) the callback should be invoked. C<cb> is the callback to invoke
222 248
223Although the callback might get passed parameters, their value and 249Although the callback might get passed parameters, their value and
224presence is undefined and you cannot rely on them. Portable AnyEvent 250presence is undefined and you cannot rely on them. Portable AnyEvent
225callbacks cannot use arguments passed to time watcher callbacks. 251callbacks cannot use arguments passed to time watcher callbacks.
226 252
227The callback will normally be invoked once only. If you specify another 253The callback will normally be invoked only once. If you specify another
228parameter, C<interval>, as a strictly positive number (> 0), then the 254parameter, C<interval>, as a strictly positive number (> 0), then the
229callback will be invoked regularly at that interval (in fractional 255callback will be invoked regularly at that interval (in fractional
230seconds) after the first invocation. If C<interval> is specified with a 256seconds) after the first invocation. If C<interval> is specified with a
231false value, then it is treated as if it were missing. 257false value, then it is treated as if it were not specified at all.
232 258
233The callback will be rescheduled before invoking the callback, but no 259The callback will be rescheduled before invoking the callback, but no
234attempt is done to avoid timer drift in most backends, so the interval is 260attempt is made to avoid timer drift in most backends, so the interval is
235only approximate. 261only approximate.
236 262
237Example: fire an event after 7.7 seconds. 263Example: fire an event after 7.7 seconds.
238 264
239 my $w = AnyEvent->timer (after => 7.7, cb => sub { 265 my $w = AnyEvent->timer (after => 7.7, cb => sub {
257 283
258While most event loops expect timers to specified in a relative way, they 284While most event loops expect timers to specified in a relative way, they
259use absolute time internally. This makes a difference when your clock 285use absolute time internally. This makes a difference when your clock
260"jumps", for example, when ntp decides to set your clock backwards from 286"jumps", for example, when ntp decides to set your clock backwards from
261the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to 287the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
262fire "after" a second might actually take six years to finally fire. 288fire "after a second" might actually take six years to finally fire.
263 289
264AnyEvent cannot compensate for this. The only event loop that is conscious 290AnyEvent cannot compensate for this. The only event loop that is conscious
265about these issues is L<EV>, which offers both relative (ev_timer, based 291of these issues is L<EV>, which offers both relative (ev_timer, based
266on true relative time) and absolute (ev_periodic, based on wallclock time) 292on true relative time) and absolute (ev_periodic, based on wallclock time)
267timers. 293timers.
268 294
269AnyEvent always prefers relative timers, if available, matching the 295AnyEvent always prefers relative timers, if available, matching the
270AnyEvent API. 296AnyEvent API.
292I<In almost all cases (in all cases if you don't care), this is the 318I<In almost all cases (in all cases if you don't care), this is the
293function to call when you want to know the current time.> 319function to call when you want to know the current time.>
294 320
295This function is also often faster then C<< AnyEvent->time >>, and 321This function is also often faster then C<< AnyEvent->time >>, and
296thus the preferred method if you want some timestamp (for example, 322thus the preferred method if you want some timestamp (for example,
297L<AnyEvent::Handle> uses this to update it's activity timeouts). 323L<AnyEvent::Handle> uses this to update its activity timeouts).
298 324
299The rest of this section is only of relevance if you try to be very exact 325The rest of this section is only of relevance if you try to be very exact
300with your timing, you can skip it without bad conscience. 326with your timing; you can skip it without a bad conscience.
301 327
302For a practical example of when these times differ, consider L<Event::Lib> 328For a practical example of when these times differ, consider L<Event::Lib>
303and L<EV> and the following set-up: 329and L<EV> and the following set-up:
304 330
305The event loop is running and has just invoked one of your callback at 331The event loop is running and has just invoked one of your callbacks at
306time=500 (assume no other callbacks delay processing). In your callback, 332time=500 (assume no other callbacks delay processing). In your callback,
307you wait a second by executing C<sleep 1> (blocking the process for a 333you wait a second by executing C<sleep 1> (blocking the process for a
308second) and then (at time=501) you create a relative timer that fires 334second) and then (at time=501) you create a relative timer that fires
309after three seconds. 335after three seconds.
310 336
330difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into 356difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
331account. 357account.
332 358
333=item AnyEvent->now_update 359=item AnyEvent->now_update
334 360
335Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache 361Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
336the current time for each loop iteration (see the discussion of L<< 362time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
337AnyEvent->now >>, above). 363above).
338 364
339When a callback runs for a long time (or when the process sleeps), then 365When a callback runs for a long time (or when the process sleeps), then
340this "current" time will differ substantially from the real time, which 366this "current" time will differ substantially from the real time, which
341might affect timers and time-outs. 367might affect timers and time-outs.
342 368
343When this is the case, you can call this method, which will update the 369When this is the case, you can call this method, which will update the
344event loop's idea of "current time". 370event loop's idea of "current time".
345 371
372A typical example would be a script in a web server (e.g. C<mod_perl>) -
373when mod_perl executes the script, then the event loop will have the wrong
374idea about the "current time" (being potentially far in the past, when the
375script ran the last time). In that case you should arrange a call to C<<
376AnyEvent->now_update >> each time the web server process wakes up again
377(e.g. at the start of your script, or in a handler).
378
346Note that updating the time I<might> cause some events to be handled. 379Note that updating the time I<might> cause some events to be handled.
347 380
348=back 381=back
349 382
350=head2 SIGNAL WATCHERS 383=head2 SIGNAL WATCHERS
384
385 $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351 386
352You can watch for signals using a signal watcher, C<signal> is the signal 387You can watch for signals using a signal watcher, C<signal> is the signal
353I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl 388I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
354callback to be invoked whenever a signal occurs. 389callback to be invoked whenever a signal occurs.
355 390
361invocation, and callback invocation will be synchronous. Synchronous means 396invocation, and callback invocation will be synchronous. Synchronous means
362that it might take a while until the signal gets handled by the process, 397that it might take a while until the signal gets handled by the process,
363but it is guaranteed not to interrupt any other callbacks. 398but it is guaranteed not to interrupt any other callbacks.
364 399
365The main advantage of using these watchers is that you can share a signal 400The main advantage of using these watchers is that you can share a signal
366between multiple watchers. 401between multiple watchers, and AnyEvent will ensure that signals will not
402interrupt your program at bad times.
367 403
368This watcher might use C<%SIG>, so programs overwriting those signals 404This watcher might use C<%SIG> (depending on the event loop used),
369directly will likely not work correctly. 405so programs overwriting those signals directly will likely not work
406correctly.
370 407
371Example: exit on SIGINT 408Example: exit on SIGINT
372 409
373 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); 410 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
374 411
412=head3 Restart Behaviour
413
414While restart behaviour is up to the event loop implementation, most will
415not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
416pure perl implementation).
417
418=head3 Safe/Unsafe Signals
419
420Perl signals can be either "safe" (synchronous to opcode handling) or
421"unsafe" (asynchronous) - the former might get delayed indefinitely, the
422latter might corrupt your memory.
423
424AnyEvent signal handlers are, in addition, synchronous to the event loop,
425i.e. they will not interrupt your running perl program but will only be
426called as part of the normal event handling (just like timer, I/O etc.
427callbacks, too).
428
429=head3 Signal Races, Delays and Workarounds
430
431Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
432callbacks to signals in a generic way, which is a pity, as you cannot
433do race-free signal handling in perl, requiring C libraries for
434this. AnyEvent will try to do its best, which means in some cases,
435signals will be delayed. The maximum time a signal might be delayed is
436specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
437variable can be changed only before the first signal watcher is created,
438and should be left alone otherwise. This variable determines how often
439AnyEvent polls for signals (in case a wake-up was missed). Higher values
440will cause fewer spurious wake-ups, which is better for power and CPU
441saving.
442
443All these problems can be avoided by installing the optional
444L<Async::Interrupt> module, which works with most event loops. It will not
445work with inherently broken event loops such as L<Event> or L<Event::Lib>
446(and not with L<POE> currently, as POE does its own workaround with
447one-second latency). For those, you just have to suffer the delays.
448
375=head2 CHILD PROCESS WATCHERS 449=head2 CHILD PROCESS WATCHERS
376 450
451 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
452
377You can also watch on a child process exit and catch its exit status. 453You can also watch for a child process exit and catch its exit status.
378 454
379The child process is specified by the C<pid> argument (if set to C<0>, it 455The child process is specified by the C<pid> argument (on some backends,
380watches for any child process exit). The watcher will triggered only when 456using C<0> watches for any child process exit, on others this will
381the child process has finished and an exit status is available, not on 457croak). The watcher will be triggered only when the child process has
382any trace events (stopped/continued). 458finished and an exit status is available, not on any trace events
459(stopped/continued).
383 460
384The callback will be called with the pid and exit status (as returned by 461The callback will be called with the pid and exit status (as returned by
385waitpid), so unlike other watcher types, you I<can> rely on child watcher 462waitpid), so unlike other watcher types, you I<can> rely on child watcher
386callback arguments. 463callback arguments.
387 464
403 480
404This means you cannot create a child watcher as the very first 481This means you cannot create a child watcher as the very first
405thing in an AnyEvent program, you I<have> to create at least one 482thing in an AnyEvent program, you I<have> to create at least one
406watcher before you C<fork> the child (alternatively, you can call 483watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>). 484C<AnyEvent::detect>).
485
486As most event loops do not support waiting for child events, they will be
487emulated by AnyEvent in most cases, in which case the latency and race
488problems mentioned in the description of signal watchers apply.
408 489
409Example: fork a process and wait for it 490Example: fork a process and wait for it
410 491
411 my $done = AnyEvent->condvar; 492 my $done = AnyEvent->condvar;
412 493
424 # do something else, then wait for process exit 505 # do something else, then wait for process exit
425 $done->recv; 506 $done->recv;
426 507
427=head2 IDLE WATCHERS 508=head2 IDLE WATCHERS
428 509
429Sometimes there is a need to do something, but it is not so important 510 $w = AnyEvent->idle (cb => <callback>);
430to do it instantly, but only when there is nothing better to do. This
431"nothing better to do" is usually defined to be "no other events need
432attention by the event loop".
433 511
434Idle watchers ideally get invoked when the event loop has nothing 512This will repeatedly invoke the callback after the process becomes idle,
435better to do, just before it would block the process to wait for new 513until either the watcher is destroyed or new events have been detected.
436events. Instead of blocking, the idle watcher is invoked.
437 514
438Most event loops unfortunately do not really support idle watchers (only 515Idle watchers are useful when there is a need to do something, but it
516is not so important (or wise) to do it instantly. The callback will be
517invoked only when there is "nothing better to do", which is usually
518defined as "all outstanding events have been handled and no new events
519have been detected". That means that idle watchers ideally get invoked
520when the event loop has just polled for new events but none have been
521detected. Instead of blocking to wait for more events, the idle watchers
522will be invoked.
523
524Unfortunately, most event loops do not really support idle watchers (only
439EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent 525EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
440will simply call the callback "from time to time". 526will simply call the callback "from time to time".
441 527
442Example: read lines from STDIN, but only process them when the 528Example: read lines from STDIN, but only process them when the
443program is otherwise idle: 529program is otherwise idle:
459 }); 545 });
460 }); 546 });
461 547
462=head2 CONDITION VARIABLES 548=head2 CONDITION VARIABLES
463 549
550 $cv = AnyEvent->condvar;
551
552 $cv->send (<list>);
553 my @res = $cv->recv;
554
464If you are familiar with some event loops you will know that all of them 555If you are familiar with some event loops you will know that all of them
465require you to run some blocking "loop", "run" or similar function that 556require you to run some blocking "loop", "run" or similar function that
466will actively watch for new events and call your callbacks. 557will actively watch for new events and call your callbacks.
467 558
468AnyEvent is different, it expects somebody else to run the event loop and 559AnyEvent is slightly different: it expects somebody else to run the event
469will only block when necessary (usually when told by the user). 560loop and will only block when necessary (usually when told by the user).
470 561
471The instrument to do that is called a "condition variable", so called 562The tool to do that is called a "condition variable", so called because
472because they represent a condition that must become true. 563they represent a condition that must become true.
564
565Now is probably a good time to look at the examples further below.
473 566
474Condition variables can be created by calling the C<< AnyEvent->condvar 567Condition variables can be created by calling the C<< AnyEvent->condvar
475>> method, usually without arguments. The only argument pair allowed is 568>> method, usually without arguments. The only argument pair allowed is
476
477C<cb>, which specifies a callback to be called when the condition variable 569C<cb>, which specifies a callback to be called when the condition variable
478becomes true, with the condition variable as the first argument (but not 570becomes true, with the condition variable as the first argument (but not
479the results). 571the results).
480 572
481After creation, the condition variable is "false" until it becomes "true" 573After creation, the condition variable is "false" until it becomes "true"
482by calling the C<send> method (or calling the condition variable as if it 574by calling the C<send> method (or calling the condition variable as if it
483were a callback, read about the caveats in the description for the C<< 575were a callback, read about the caveats in the description for the C<<
484->send >> method). 576->send >> method).
485 577
486Condition variables are similar to callbacks, except that you can 578Since condition variables are the most complex part of the AnyEvent API, here are
487optionally wait for them. They can also be called merge points - points 579some different mental models of what they are - pick the ones you can connect to:
488in time where multiple outstanding events have been processed. And yet 580
489another way to call them is transactions - each condition variable can be 581=over 4
490used to represent a transaction, which finishes at some point and delivers 582
491a result. 583=item * Condition variables are like callbacks - you can call them (and pass them instead
584of callbacks). Unlike callbacks however, you can also wait for them to be called.
585
586=item * Condition variables are signals - one side can emit or send them,
587the other side can wait for them, or install a handler that is called when
588the signal fires.
589
590=item * Condition variables are like "Merge Points" - points in your program
591where you merge multiple independent results/control flows into one.
592
593=item * Condition variables represent a transaction - functions that start
594some kind of transaction can return them, leaving the caller the choice
595between waiting in a blocking fashion, or setting a callback.
596
597=item * Condition variables represent future values, or promises to deliver
598some result, long before the result is available.
599
600=back
492 601
493Condition variables are very useful to signal that something has finished, 602Condition variables are very useful to signal that something has finished,
494for example, if you write a module that does asynchronous http requests, 603for example, if you write a module that does asynchronous http requests,
495then a condition variable would be the ideal candidate to signal the 604then a condition variable would be the ideal candidate to signal the
496availability of results. The user can either act when the callback is 605availability of results. The user can either act when the callback is
509 618
510Condition variables are represented by hash refs in perl, and the keys 619Condition variables are represented by hash refs in perl, and the keys
511used by AnyEvent itself are all named C<_ae_XXX> to make subclassing 620used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
512easy (it is often useful to build your own transaction class on top of 621easy (it is often useful to build your own transaction class on top of
513AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call 622AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
514it's C<new> method in your own C<new> method. 623its C<new> method in your own C<new> method.
515 624
516There are two "sides" to a condition variable - the "producer side" which 625There are two "sides" to a condition variable - the "producer side" which
517eventually calls C<< -> send >>, and the "consumer side", which waits 626eventually calls C<< -> send >>, and the "consumer side", which waits
518for the send to occur. 627for the send to occur.
519 628
520Example: wait for a timer. 629Example: wait for a timer.
521 630
522 # wait till the result is ready 631 # condition: "wait till the timer is fired"
523 my $result_ready = AnyEvent->condvar; 632 my $timer_fired = AnyEvent->condvar;
524 633
525 # do something such as adding a timer 634 # create the timer - we could wait for, say
526 # or socket watcher the calls $result_ready->send 635 # a handle becomign ready, or even an
527 # when the "result" is ready. 636 # AnyEvent::HTTP request to finish, but
528 # in this case, we simply use a timer: 637 # in this case, we simply use a timer:
529 my $w = AnyEvent->timer ( 638 my $w = AnyEvent->timer (
530 after => 1, 639 after => 1,
531 cb => sub { $result_ready->send }, 640 cb => sub { $timer_fired->send },
532 ); 641 );
533 642
534 # this "blocks" (while handling events) till the callback 643 # this "blocks" (while handling events) till the callback
535 # calls send 644 # calls ->send
536 $result_ready->recv; 645 $timer_fired->recv;
537 646
538Example: wait for a timer, but take advantage of the fact that 647Example: wait for a timer, but take advantage of the fact that condition
539condition variables are also code references. 648variables are also callable directly.
540 649
541 my $done = AnyEvent->condvar; 650 my $done = AnyEvent->condvar;
542 my $delay = AnyEvent->timer (after => 5, cb => $done); 651 my $delay = AnyEvent->timer (after => 5, cb => $done);
543 $done->recv; 652 $done->recv;
544 653
550 659
551 ... 660 ...
552 661
553 my @info = $couchdb->info->recv; 662 my @info = $couchdb->info->recv;
554 663
555And this is how you would just ste a callback to be called whenever the 664And this is how you would just set a callback to be called whenever the
556results are available: 665results are available:
557 666
558 $couchdb->info->cb (sub { 667 $couchdb->info->cb (sub {
559 my @info = $_[0]->recv; 668 my @info = $_[0]->recv;
560 }); 669 });
578immediately from within send. 687immediately from within send.
579 688
580Any arguments passed to the C<send> call will be returned by all 689Any arguments passed to the C<send> call will be returned by all
581future C<< ->recv >> calls. 690future C<< ->recv >> calls.
582 691
583Condition variables are overloaded so one can call them directly 692Condition variables are overloaded so one can call them directly (as if
584(as a code reference). Calling them directly is the same as calling 693they were a code reference). Calling them directly is the same as calling
585C<send>. Note, however, that many C-based event loops do not handle 694C<send>.
586overloading, so as tempting as it may be, passing a condition variable
587instead of a callback does not work. Both the pure perl and EV loops
588support overloading, however, as well as all functions that use perl to
589invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
590example).
591 695
592=item $cv->croak ($error) 696=item $cv->croak ($error)
593 697
594Similar to send, but causes all call's to C<< ->recv >> to invoke 698Similar to send, but causes all calls to C<< ->recv >> to invoke
595C<Carp::croak> with the given error message/object/scalar. 699C<Carp::croak> with the given error message/object/scalar.
596 700
597This can be used to signal any errors to the condition variable 701This can be used to signal any errors to the condition variable
598user/consumer. 702user/consumer. Doing it this way instead of calling C<croak> directly
703delays the error detection, but has the overwhelming advantage that it
704diagnoses the error at the place where the result is expected, and not
705deep in some event callback with no connection to the actual code causing
706the problem.
599 707
600=item $cv->begin ([group callback]) 708=item $cv->begin ([group callback])
601 709
602=item $cv->end 710=item $cv->end
603 711
605one. For example, a function that pings many hosts in parallel might want 713one. For example, a function that pings many hosts in parallel might want
606to use a condition variable for the whole process. 714to use a condition variable for the whole process.
607 715
608Every call to C<< ->begin >> will increment a counter, and every call to 716Every call to C<< ->begin >> will increment a counter, and every call to
609C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 717C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
610>>, the (last) callback passed to C<begin> will be executed. That callback 718>>, the (last) callback passed to C<begin> will be executed, passing the
611is I<supposed> to call C<< ->send >>, but that is not required. If no 719condvar as first argument. That callback is I<supposed> to call C<< ->send
612callback was set, C<send> will be called without any arguments. 720>>, but that is not required. If no group callback was set, C<send> will
721be called without any arguments.
613 722
614You can think of C<< $cv->send >> giving you an OR condition (one call 723You can think of C<< $cv->send >> giving you an OR condition (one call
615sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND 724sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
616condition (all C<begin> calls must be C<end>'ed before the condvar sends). 725condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617 726
639one call to C<begin>, so the condvar waits for all calls to C<end> before 748one call to C<begin>, so the condvar waits for all calls to C<end> before
640sending. 749sending.
641 750
642The ping example mentioned above is slightly more complicated, as the 751The ping example mentioned above is slightly more complicated, as the
643there are results to be passwd back, and the number of tasks that are 752there are results to be passwd back, and the number of tasks that are
644begung can potentially be zero: 753begun can potentially be zero:
645 754
646 my $cv = AnyEvent->condvar; 755 my $cv = AnyEvent->condvar;
647 756
648 my %result; 757 my %result;
649 $cv->begin (sub { $cv->send (\%result) }); 758 $cv->begin (sub { shift->send (\%result) });
650 759
651 for my $host (@list_of_hosts) { 760 for my $host (@list_of_hosts) {
652 $cv->begin; 761 $cv->begin;
653 ping_host_then_call_callback $host, sub { 762 ping_host_then_call_callback $host, sub {
654 $result{$host} = ...; 763 $result{$host} = ...;
670to be called once the counter reaches C<0>, and second, it ensures that 779to be called once the counter reaches C<0>, and second, it ensures that
671C<send> is called even when C<no> hosts are being pinged (the loop 780C<send> is called even when C<no> hosts are being pinged (the loop
672doesn't execute once). 781doesn't execute once).
673 782
674This is the general pattern when you "fan out" into multiple (but 783This is the general pattern when you "fan out" into multiple (but
675potentially none) subrequests: use an outer C<begin>/C<end> pair to set 784potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
676the callback and ensure C<end> is called at least once, and then, for each 785the callback and ensure C<end> is called at least once, and then, for each
677subrequest you start, call C<begin> and for each subrequest you finish, 786subrequest you start, call C<begin> and for each subrequest you finish,
678call C<end>. 787call C<end>.
679 788
680=back 789=back
687=over 4 796=over 4
688 797
689=item $cv->recv 798=item $cv->recv
690 799
691Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 800Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
692>> methods have been called on c<$cv>, while servicing other watchers 801>> methods have been called on C<$cv>, while servicing other watchers
693normally. 802normally.
694 803
695You can only wait once on a condition - additional calls are valid but 804You can only wait once on a condition - additional calls are valid but
696will return immediately. 805will return immediately.
697 806
699function will call C<croak>. 808function will call C<croak>.
700 809
701In list context, all parameters passed to C<send> will be returned, 810In list context, all parameters passed to C<send> will be returned,
702in scalar context only the first one will be returned. 811in scalar context only the first one will be returned.
703 812
813Note that doing a blocking wait in a callback is not supported by any
814event loop, that is, recursive invocation of a blocking C<< ->recv
815>> is not allowed, and the C<recv> call will C<croak> if such a
816condition is detected. This condition can be slightly loosened by using
817L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
818any thread that doesn't run the event loop itself.
819
704Not all event models support a blocking wait - some die in that case 820Not all event models support a blocking wait - some die in that case
705(programs might want to do that to stay interactive), so I<if you are 821(programs might want to do that to stay interactive), so I<if you are
706using this from a module, never require a blocking wait>, but let the 822using this from a module, never require a blocking wait>. Instead, let the
707caller decide whether the call will block or not (for example, by coupling 823caller decide whether the call will block or not (for example, by coupling
708condition variables with some kind of request results and supporting 824condition variables with some kind of request results and supporting
709callbacks so the caller knows that getting the result will not block, 825callbacks so the caller knows that getting the result will not block,
710while still supporting blocking waits if the caller so desires). 826while still supporting blocking waits if the caller so desires).
711 827
712Another reason I<never> to C<< ->recv >> in a module is that you cannot
713sensibly have two C<< ->recv >>'s in parallel, as that would require
714multiple interpreters or coroutines/threads, none of which C<AnyEvent>
715can supply.
716
717The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
718fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
719versions and also integrates coroutines into AnyEvent, making blocking
720C<< ->recv >> calls perfectly safe as long as they are done from another
721coroutine (one that doesn't run the event loop).
722
723You can ensure that C<< -recv >> never blocks by setting a callback and 828You can ensure that C<< ->recv >> never blocks by setting a callback and
724only calling C<< ->recv >> from within that callback (or at a later 829only calling C<< ->recv >> from within that callback (or at a later
725time). This will work even when the event loop does not support blocking 830time). This will work even when the event loop does not support blocking
726waits otherwise. 831waits otherwise.
727 832
728=item $bool = $cv->ready 833=item $bool = $cv->ready
734 839
735This is a mutator function that returns the callback set and optionally 840This is a mutator function that returns the callback set and optionally
736replaces it before doing so. 841replaces it before doing so.
737 842
738The callback will be called when the condition becomes "true", i.e. when 843The callback will be called when the condition becomes "true", i.e. when
739C<send> or C<croak> are called, with the only argument being the condition 844C<send> or C<croak> are called, with the only argument being the
740variable itself. Calling C<recv> inside the callback or at any later time 845condition variable itself. If the condition is already true, the
741is guaranteed not to block. 846callback is called immediately when it is set. Calling C<recv> inside
847the callback or at any later time is guaranteed not to block.
742 848
743=back 849=back
744 850
745=head1 SUPPORTED EVENT LOOPS/BACKENDS 851=head1 SUPPORTED EVENT LOOPS/BACKENDS
746 852
749=over 4 855=over 4
750 856
751=item Backends that are autoprobed when no other event loop can be found. 857=item Backends that are autoprobed when no other event loop can be found.
752 858
753EV is the preferred backend when no other event loop seems to be in 859EV is the preferred backend when no other event loop seems to be in
754use. If EV is not installed, then AnyEvent will try Event, and, failing 860use. If EV is not installed, then AnyEvent will fall back to its own
755that, will fall back to its own pure-perl implementation, which is 861pure-perl implementation, which is available everywhere as it comes with
756available everywhere as it comes with AnyEvent itself. 862AnyEvent itself.
757 863
758 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 864 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
759 AnyEvent::Impl::Event based on Event, very stable, few glitches.
760 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 865 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
761 866
762=item Backends that are transparently being picked up when they are used. 867=item Backends that are transparently being picked up when they are used.
763 868
764These will be used when they are currently loaded when the first watcher 869These will be used if they are already loaded when the first watcher
765is created, in which case it is assumed that the application is using 870is created, in which case it is assumed that the application is using
766them. This means that AnyEvent will automatically pick the right backend 871them. This means that AnyEvent will automatically pick the right backend
767when the main program loads an event module before anything starts to 872when the main program loads an event module before anything starts to
768create watchers. Nothing special needs to be done by the main program. 873create watchers. Nothing special needs to be done by the main program.
769 874
875 AnyEvent::Impl::Event based on Event, very stable, few glitches.
770 AnyEvent::Impl::Glib based on Glib, slow but very stable. 876 AnyEvent::Impl::Glib based on Glib, slow but very stable.
771 AnyEvent::Impl::Tk based on Tk, very broken. 877 AnyEvent::Impl::Tk based on Tk, very broken.
772 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 878 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
773 AnyEvent::Impl::POE based on POE, very slow, some limitations. 879 AnyEvent::Impl::POE based on POE, very slow, some limitations.
880 AnyEvent::Impl::Irssi used when running within irssi.
881 AnyEvent::Impl::IOAsync based on IO::Async.
882 AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
883 AnyEvent::Impl::FLTK based on FLTK.
774 884
775=item Backends with special needs. 885=item Backends with special needs.
776 886
777Qt requires the Qt::Application to be instantiated first, but will 887Qt requires the Qt::Application to be instantiated first, but will
778otherwise be picked up automatically. As long as the main program 888otherwise be picked up automatically. As long as the main program
779instantiates the application before any AnyEvent watchers are created, 889instantiates the application before any AnyEvent watchers are created,
780everything should just work. 890everything should just work.
781 891
782 AnyEvent::Impl::Qt based on Qt. 892 AnyEvent::Impl::Qt based on Qt.
783 893
784Support for IO::Async can only be partial, as it is too broken and
785architecturally limited to even support the AnyEvent API. It also
786is the only event loop that needs the loop to be set explicitly, so
787it can only be used by a main program knowing about AnyEvent. See
788L<AnyEvent::Impl::Async> for the gory details.
789
790 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
791
792=item Event loops that are indirectly supported via other backends. 894=item Event loops that are indirectly supported via other backends.
793 895
794Some event loops can be supported via other modules: 896Some event loops can be supported via other modules:
795 897
796There is no direct support for WxWidgets (L<Wx>) or L<Prima>. 898There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
809 911
810=back 912=back
811 913
812=head1 GLOBAL VARIABLES AND FUNCTIONS 914=head1 GLOBAL VARIABLES AND FUNCTIONS
813 915
916These are not normally required to use AnyEvent, but can be useful to
917write AnyEvent extension modules.
918
814=over 4 919=over 4
815 920
816=item $AnyEvent::MODEL 921=item $AnyEvent::MODEL
817 922
818Contains C<undef> until the first watcher is being created. Then it 923Contains C<undef> until the first watcher is being created, before the
924backend has been autodetected.
925
819contains the event model that is being used, which is the name of the 926Afterwards it contains the event model that is being used, which is the
820Perl class implementing the model. This class is usually one of the 927name of the Perl class implementing the model. This class is usually one
821C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 928of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
822AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 929case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
930will be C<urxvt::anyevent>).
823 931
824=item AnyEvent::detect 932=item AnyEvent::detect
825 933
826Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 934Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
827if necessary. You should only call this function right before you would 935if necessary. You should only call this function right before you would
828have created an AnyEvent watcher anyway, that is, as late as possible at 936have created an AnyEvent watcher anyway, that is, as late as possible at
829runtime. 937runtime, and not e.g. during initialisation of your module.
938
939If you need to do some initialisation before AnyEvent watchers are
940created, use C<post_detect>.
830 941
831=item $guard = AnyEvent::post_detect { BLOCK } 942=item $guard = AnyEvent::post_detect { BLOCK }
832 943
833Arranges for the code block to be executed as soon as the event model is 944Arranges for the code block to be executed as soon as the event model is
834autodetected (or immediately if this has already happened). 945autodetected (or immediately if that has already happened).
946
947The block will be executed I<after> the actual backend has been detected
948(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
949created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
950other initialisations - see the sources of L<AnyEvent::Strict> or
951L<AnyEvent::AIO> to see how this is used.
952
953The most common usage is to create some global watchers, without forcing
954event module detection too early, for example, L<AnyEvent::AIO> creates
955and installs the global L<IO::AIO> watcher in a C<post_detect> block to
956avoid autodetecting the event module at load time.
835 957
836If called in scalar or list context, then it creates and returns an object 958If called in scalar or list context, then it creates and returns an object
837that automatically removes the callback again when it is destroyed. See 959that automatically removes the callback again when it is destroyed (or
960C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
838L<Coro::BDB> for a case where this is useful. 961a case where this is useful.
962
963Example: Create a watcher for the IO::AIO module and store it in
964C<$WATCHER>, but do so only do so after the event loop is initialised.
965
966 our WATCHER;
967
968 my $guard = AnyEvent::post_detect {
969 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
970 };
971
972 # the ||= is important in case post_detect immediately runs the block,
973 # as to not clobber the newly-created watcher. assigning both watcher and
974 # post_detect guard to the same variable has the advantage of users being
975 # able to just C<undef $WATCHER> if the watcher causes them grief.
976
977 $WATCHER ||= $guard;
839 978
840=item @AnyEvent::post_detect 979=item @AnyEvent::post_detect
841 980
842If there are any code references in this array (you can C<push> to it 981If there are any code references in this array (you can C<push> to it
843before or after loading AnyEvent), then they will called directly after 982before or after loading AnyEvent), then they will be called directly
844the event loop has been chosen. 983after the event loop has been chosen.
845 984
846You should check C<$AnyEvent::MODEL> before adding to this array, though: 985You should check C<$AnyEvent::MODEL> before adding to this array, though:
847if it contains a true value then the event loop has already been detected, 986if it is defined then the event loop has already been detected, and the
848and the array will be ignored. 987array will be ignored.
849 988
850Best use C<AnyEvent::post_detect { BLOCK }> instead. 989Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
990it, as it takes care of these details.
991
992This variable is mainly useful for modules that can do something useful
993when AnyEvent is used and thus want to know when it is initialised, but do
994not need to even load it by default. This array provides the means to hook
995into AnyEvent passively, without loading it.
996
997Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
998together, you could put this into Coro (this is the actual code used by
999Coro to accomplish this):
1000
1001 if (defined $AnyEvent::MODEL) {
1002 # AnyEvent already initialised, so load Coro::AnyEvent
1003 require Coro::AnyEvent;
1004 } else {
1005 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
1006 # as soon as it is
1007 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
1008 }
1009
1010=item AnyEvent::postpone BLOCK
1011
1012Arranges for the block to be executed as soon as possible, but not before
1013the call itself returns. In practise, the block will be executed just
1014before the event loop polls for new events, or shortly afterwards.
1015
1016This function never returns anything (to make the C<return postpone { ...
1017}> idiom more useful.
1018
1019To understand the usefulness of this function, consider a function that
1020asynchronously does something for you and returns some transaction
1021object or guard to let you cancel the operation. For example,
1022C<AnyEvent::Socket::tcp_connect>:
1023
1024 # start a conenction attempt unless one is active
1025 $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
1026 delete $self->{connect_guard};
1027 ...
1028 };
1029
1030Imagine that this function could instantly call the callback, for
1031example, because it detects an obvious error such as a negative port
1032number. Invoking the callback before the function returns causes problems
1033however: the callback will be called and will try to delete the guard
1034object. But since the function hasn't returned yet, there is nothing to
1035delete. When the function eventually returns it will assign the guard
1036object to C<< $self->{connect_guard} >>, where it will likely never be
1037deleted, so the program thinks it is still trying to connect.
1038
1039This is where C<AnyEvent::postpone> should be used. Instead of calling the
1040callback directly on error:
1041
1042 $cb->(undef), return # signal error to callback, BAD!
1043 if $some_error_condition;
1044
1045It should use C<postpone>:
1046
1047 AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
1048 if $some_error_condition;
851 1049
852=back 1050=back
853 1051
854=head1 WHAT TO DO IN A MODULE 1052=head1 WHAT TO DO IN A MODULE
855 1053
866because it will stall the whole program, and the whole point of using 1064because it will stall the whole program, and the whole point of using
867events is to stay interactive. 1065events is to stay interactive.
868 1066
869It is fine, however, to call C<< ->recv >> when the user of your module 1067It is fine, however, to call C<< ->recv >> when the user of your module
870requests it (i.e. if you create a http request object ad have a method 1068requests it (i.e. if you create a http request object ad have a method
871called C<results> that returns the results, it should call C<< ->recv >> 1069called C<results> that returns the results, it may call C<< ->recv >>
872freely, as the user of your module knows what she is doing. always). 1070freely, as the user of your module knows what she is doing. Always).
873 1071
874=head1 WHAT TO DO IN THE MAIN PROGRAM 1072=head1 WHAT TO DO IN THE MAIN PROGRAM
875 1073
876There will always be a single main program - the only place that should 1074There will always be a single main program - the only place that should
877dictate which event model to use. 1075dictate which event model to use.
878 1076
879If it doesn't care, it can just "use AnyEvent" and use it itself, or not 1077If the program is not event-based, it need not do anything special, even
880do anything special (it does not need to be event-based) and let AnyEvent 1078when it depends on a module that uses an AnyEvent. If the program itself
881decide which implementation to chose if some module relies on it. 1079uses AnyEvent, but does not care which event loop is used, all it needs
1080to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
1081available loop implementation.
882 1082
883If the main program relies on a specific event model - for example, in 1083If the main program relies on a specific event model - for example, in
884Gtk2 programs you have to rely on the Glib module - you should load the 1084Gtk2 programs you have to rely on the Glib module - you should load the
885event module before loading AnyEvent or any module that uses it: generally 1085event module before loading AnyEvent or any module that uses it: generally
886speaking, you should load it as early as possible. The reason is that 1086speaking, you should load it as early as possible. The reason is that
887modules might create watchers when they are loaded, and AnyEvent will 1087modules might create watchers when they are loaded, and AnyEvent will
888decide on the event model to use as soon as it creates watchers, and it 1088decide on the event model to use as soon as it creates watchers, and it
889might chose the wrong one unless you load the correct one yourself. 1089might choose the wrong one unless you load the correct one yourself.
890 1090
891You can chose to use a pure-perl implementation by loading the 1091You can chose to use a pure-perl implementation by loading the
892C<AnyEvent::Impl::Perl> module, which gives you similar behaviour 1092C<AnyEvent::Loop> module, which gives you similar behaviour
893everywhere, but letting AnyEvent chose the model is generally better. 1093everywhere, but letting AnyEvent chose the model is generally better.
894 1094
895=head2 MAINLOOP EMULATION 1095=head2 MAINLOOP EMULATION
896 1096
897Sometimes (often for short test scripts, or even standalone programs who 1097Sometimes (often for short test scripts, or even standalone programs who
912=head1 OTHER MODULES 1112=head1 OTHER MODULES
913 1113
914The following is a non-exhaustive list of additional modules that use 1114The following is a non-exhaustive list of additional modules that use
915AnyEvent as a client and can therefore be mixed easily with other AnyEvent 1115AnyEvent as a client and can therefore be mixed easily with other AnyEvent
916modules and other event loops in the same program. Some of the modules 1116modules and other event loops in the same program. Some of the modules
917come with AnyEvent, most are available via CPAN. 1117come as part of AnyEvent, the others are available via CPAN.
918 1118
919=over 4 1119=over 4
920 1120
921=item L<AnyEvent::Util> 1121=item L<AnyEvent::Util>
922 1122
923Contains various utility functions that replace often-used but blocking 1123Contains various utility functions that replace often-used blocking
924functions such as C<inet_aton> by event-/callback-based versions. 1124functions such as C<inet_aton> with event/callback-based versions.
925 1125
926=item L<AnyEvent::Socket> 1126=item L<AnyEvent::Socket>
927 1127
928Provides various utility functions for (internet protocol) sockets, 1128Provides various utility functions for (internet protocol) sockets,
929addresses and name resolution. Also functions to create non-blocking tcp 1129addresses and name resolution. Also functions to create non-blocking tcp
931 1131
932=item L<AnyEvent::Handle> 1132=item L<AnyEvent::Handle>
933 1133
934Provide read and write buffers, manages watchers for reads and writes, 1134Provide read and write buffers, manages watchers for reads and writes,
935supports raw and formatted I/O, I/O queued and fully transparent and 1135supports raw and formatted I/O, I/O queued and fully transparent and
936non-blocking SSL/TLS (via L<AnyEvent::TLS>. 1136non-blocking SSL/TLS (via L<AnyEvent::TLS>).
937 1137
938=item L<AnyEvent::DNS> 1138=item L<AnyEvent::DNS>
939 1139
940Provides rich asynchronous DNS resolver capabilities. 1140Provides rich asynchronous DNS resolver capabilities.
941 1141
1142=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
1143
1144Implement event-based interfaces to the protocols of the same name (for
1145the curious, IGS is the International Go Server and FCP is the Freenet
1146Client Protocol).
1147
1148=item L<AnyEvent::Handle::UDP>
1149
1150Here be danger!
1151
1152As Pauli would put it, "Not only is it not right, it's not even wrong!" -
1153there are so many things wrong with AnyEvent::Handle::UDP, most notably
1154its use of a stream-based API with a protocol that isn't streamable, that
1155the only way to improve it is to delete it.
1156
1157It features data corruption (but typically only under load) and general
1158confusion. On top, the author is not only clueless about UDP but also
1159fact-resistant - some gems of his understanding: "connect doesn't work
1160with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
1161packets", "I don't need to implement proper error checking as UDP doesn't
1162support error checking" and so on - he doesn't even understand what's
1163wrong with his module when it is explained to him.
1164
942=item L<AnyEvent::HTTP> 1165=item L<AnyEvent::DBI>
943 1166
944A simple-to-use HTTP library that is capable of making a lot of concurrent 1167Executes L<DBI> requests asynchronously in a proxy process for you,
945HTTP requests. 1168notifying you in an event-based way when the operation is finished.
1169
1170=item L<AnyEvent::AIO>
1171
1172Truly asynchronous (as opposed to non-blocking) I/O, should be in the
1173toolbox of every event programmer. AnyEvent::AIO transparently fuses
1174L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
1175file I/O, and much more.
946 1176
947=item L<AnyEvent::HTTPD> 1177=item L<AnyEvent::HTTPD>
948 1178
949Provides a simple web application server framework. 1179A simple embedded webserver.
950 1180
951=item L<AnyEvent::FastPing> 1181=item L<AnyEvent::FastPing>
952 1182
953The fastest ping in the west. 1183The fastest ping in the west.
954 1184
955=item L<AnyEvent::DBI>
956
957Executes L<DBI> requests asynchronously in a proxy process.
958
959=item L<AnyEvent::AIO>
960
961Truly asynchronous I/O, should be in the toolbox of every event
962programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
963together.
964
965=item L<AnyEvent::BDB>
966
967Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
968L<BDB> and AnyEvent together.
969
970=item L<AnyEvent::GPSD>
971
972A non-blocking interface to gpsd, a daemon delivering GPS information.
973
974=item L<AnyEvent::IRC>
975
976AnyEvent based IRC client module family (replacing the older Net::IRC3).
977
978=item L<AnyEvent::XMPP>
979
980AnyEvent based XMPP (Jabber protocol) module family (replacing the older
981Net::XMPP2>.
982
983=item L<AnyEvent::IGS>
984
985A non-blocking interface to the Internet Go Server protocol (used by
986L<App::IGS>).
987
988=item L<Net::FCP>
989
990AnyEvent-based implementation of the Freenet Client Protocol, birthplace
991of AnyEvent.
992
993=item L<Event::ExecFlow>
994
995High level API for event-based execution flow control.
996
997=item L<Coro> 1185=item L<Coro>
998 1186
999Has special support for AnyEvent via L<Coro::AnyEvent>. 1187Has special support for AnyEvent via L<Coro::AnyEvent>.
1000 1188
1001=back 1189=back
1002 1190
1003=cut 1191=cut
1004 1192
1005package AnyEvent; 1193package AnyEvent;
1006 1194
1007no warnings; 1195# basically a tuned-down version of common::sense
1008use strict qw(vars subs); 1196sub common_sense {
1197 # from common:.sense 3.4
1198 ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
1199 # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
1200 $^H |= 0x00000600;
1201}
1009 1202
1203BEGIN { AnyEvent::common_sense }
1204
1010use Carp; 1205use Carp ();
1011 1206
1012our $VERSION = 4.801; 1207our $VERSION = '5.34';
1013our $MODEL; 1208our $MODEL;
1014 1209
1015our $AUTOLOAD; 1210our $AUTOLOAD;
1016our @ISA; 1211our @ISA;
1017 1212
1018our @REGISTRY; 1213our @REGISTRY;
1019 1214
1020our $WIN32; 1215our $VERBOSE;
1021 1216
1022BEGIN { 1217BEGIN {
1023 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1218 require "AnyEvent/constants.pl";
1219
1024 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1220 eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1025 1221
1026 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1222 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1027 if ${^TAINT}; 1223 if ${^TAINT};
1028}
1029 1224
1030our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1225 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1226
1227}
1228
1229our $MAX_SIGNAL_LATENCY = 10;
1031 1230
1032our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 1231our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1033 1232
1034{ 1233{
1035 my $idx; 1234 my $idx;
1037 for reverse split /\s*,\s*/, 1236 for reverse split /\s*,\s*/,
1038 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 1237 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1039} 1238}
1040 1239
1041my @models = ( 1240my @models = (
1042 [EV:: => AnyEvent::Impl::EV::], 1241 [EV:: => AnyEvent::Impl::EV:: , 1],
1043 [Event:: => AnyEvent::Impl::Event::], 1242 [AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1044 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1045 # everything below here will not be autoprobed 1243 # everything below here will not (normally) be autoprobed
1046 # as the pureperl backend should work everywhere 1244 # as the pure perl backend should work everywhere
1047 # and is usually faster 1245 # and is usually faster
1246 [Event:: => AnyEvent::Impl::Event::, 1],
1048 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers 1247 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1049 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1248 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1249 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1050 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles 1250 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1251 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1051 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1252 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1052 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1053 [Wx:: => AnyEvent::Impl::POE::], 1253 [Wx:: => AnyEvent::Impl::POE::],
1054 [Prima:: => AnyEvent::Impl::POE::], 1254 [Prima:: => AnyEvent::Impl::POE::],
1055 # IO::Async is just too broken - we would need workarounds for its
1056 # byzantine signal and broken child handling, among others.
1057 # IO::Async is rather hard to detect, as it doesn't have any
1058 # obvious default class.
1059# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1060# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program 1255 [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::],
1061# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program 1256 [Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1257 [FLTK:: => AnyEvent::Impl::FLTK::],
1062); 1258);
1063 1259
1064our %method = map +($_ => 1), 1260our %method = map +($_ => 1),
1065 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1261 qw(io timer time now now_update signal child idle condvar DESTROY);
1066 1262
1067our @post_detect; 1263our @post_detect;
1068 1264
1069sub post_detect(&) { 1265sub post_detect(&) {
1070 my ($cb) = @_; 1266 my ($cb) = @_;
1071 1267
1072 if ($MODEL) {
1073 $cb->();
1074
1075 1
1076 } else {
1077 push @post_detect, $cb; 1268 push @post_detect, $cb;
1078 1269
1079 defined wantarray 1270 defined wantarray
1080 ? bless \$cb, "AnyEvent::Util::postdetect" 1271 ? bless \$cb, "AnyEvent::Util::postdetect"
1081 : () 1272 : ()
1082 }
1083} 1273}
1084 1274
1085sub AnyEvent::Util::postdetect::DESTROY { 1275sub AnyEvent::Util::postdetect::DESTROY {
1086 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1276 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1087} 1277}
1088 1278
1089sub detect() { 1279sub detect() {
1280 # free some memory
1281 *detect = sub () { $MODEL };
1282
1283 local $!; # for good measure
1284 local $SIG{__DIE__};
1285
1286 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1287 my $model = "AnyEvent::Impl::$1";
1288 if (eval "require $model") {
1289 $MODEL = $model;
1290 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1291 } else {
1292 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1293 }
1294 }
1295
1296 # check for already loaded models
1090 unless ($MODEL) { 1297 unless ($MODEL) {
1091 no strict 'refs'; 1298 for (@REGISTRY, @models) {
1092 local $SIG{__DIE__}; 1299 my ($package, $model) = @$_;
1093 1300 if (${"$package\::VERSION"} > 0) {
1094 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1095 my $model = "AnyEvent::Impl::$1";
1096 if (eval "require $model") { 1301 if (eval "require $model") {
1097 $MODEL = $model; 1302 $MODEL = $model;
1098 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; 1303 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1099 } else { 1304 last;
1100 warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; 1305 }
1101 } 1306 }
1102 } 1307 }
1103 1308
1104 # check for already loaded models
1105 unless ($MODEL) { 1309 unless ($MODEL) {
1310 # try to autoload a model
1106 for (@REGISTRY, @models) { 1311 for (@REGISTRY, @models) {
1107 my ($package, $model) = @$_; 1312 my ($package, $model, $autoload) = @$_;
1313 if (
1314 $autoload
1315 and eval "require $package"
1108 if (${"$package\::VERSION"} > 0) { 1316 and ${"$package\::VERSION"} > 0
1109 if (eval "require $model") { 1317 and eval "require $model"
1318 ) {
1110 $MODEL = $model; 1319 $MODEL = $model;
1111 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; 1320 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1112 last; 1321 last;
1113 }
1114 } 1322 }
1115 } 1323 }
1116 1324
1117 unless ($MODEL) {
1118 # try to load a model
1119
1120 for (@REGISTRY, @models) {
1121 my ($package, $model) = @$_;
1122 if (eval "require $package"
1123 and ${"$package\::VERSION"} > 0
1124 and eval "require $model") {
1125 $MODEL = $model;
1126 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1127 last;
1128 }
1129 }
1130
1131 $MODEL 1325 $MODEL
1132 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; 1326 or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1133 }
1134 } 1327 }
1135
1136 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1137
1138 unshift @ISA, $MODEL;
1139
1140 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1141
1142 (shift @post_detect)->() while @post_detect;
1143 } 1328 }
1329
1330 @models = (); # free probe data
1331
1332 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1333 unshift @ISA, $MODEL;
1334
1335 # now nuke some methods that are overridden by the backend.
1336 # SUPER is not allowed.
1337 for (qw(time signal child idle)) {
1338 undef &{"AnyEvent::Base::$_"}
1339 if defined &{"$MODEL\::$_"};
1340 }
1341
1342 if ($ENV{PERL_ANYEVENT_STRICT}) {
1343 eval { require AnyEvent::Strict };
1344 warn "AnyEvent: cannot load AnyEvent::Strict: $@"
1345 if $@ && $VERBOSE;
1346 }
1347
1348 (shift @post_detect)->() while @post_detect;
1349
1350 *post_detect = sub(&) {
1351 shift->();
1352
1353 undef
1354 };
1144 1355
1145 $MODEL 1356 $MODEL
1146} 1357}
1147 1358
1148sub AUTOLOAD { 1359sub AUTOLOAD {
1149 (my $func = $AUTOLOAD) =~ s/.*://; 1360 (my $func = $AUTOLOAD) =~ s/.*://;
1150 1361
1151 $method{$func} 1362 $method{$func}
1152 or croak "$func: not a valid method for AnyEvent objects"; 1363 or Carp::croak "$func: not a valid AnyEvent class method";
1153 1364
1154 detect unless $MODEL; 1365 detect;
1155 1366
1156 my $class = shift; 1367 my $class = shift;
1157 $class->$func (@_); 1368 $class->$func (@_);
1369}
1370
1371our $POSTPONE_W;
1372our @POSTPONE;
1373
1374sub _postpone_exec {
1375 undef $POSTPONE_W;
1376 (pop @POSTPONE)->()
1377 while @POSTPONE;
1378}
1379
1380sub postpone(&) {
1381 push @POSTPONE, shift;
1382
1383 $POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
1384
1385 ()
1158} 1386}
1159 1387
1160# utility function to dup a filehandle. this is used by many backends 1388# utility function to dup a filehandle. this is used by many backends
1161# to support binding more than one watcher per filehandle (they usually 1389# to support binding more than one watcher per filehandle (they usually
1162# allow only one watcher per fd, so we dup it to get a different one). 1390# allow only one watcher per fd, so we dup it to get a different one).
1163sub _dupfh($$;$$) { 1391sub _dupfh($$;$$) {
1164 my ($poll, $fh, $r, $w) = @_; 1392 my ($poll, $fh, $r, $w) = @_;
1165 1393
1166 # cygwin requires the fh mode to be matching, unix doesn't 1394 # cygwin requires the fh mode to be matching, unix doesn't
1167 my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">"); 1395 my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1168 1396
1169 open my $fh2, "$mode&", $fh 1397 open my $fh2, $mode, $fh
1170 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,"; 1398 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1171 1399
1172 # we assume CLOEXEC is already set by perl in all important cases 1400 # we assume CLOEXEC is already set by perl in all important cases
1173 1401
1174 ($fh2, $rw) 1402 ($fh2, $rw)
1175} 1403}
1176 1404
1405=head1 SIMPLIFIED AE API
1406
1407Starting with version 5.0, AnyEvent officially supports a second, much
1408simpler, API that is designed to reduce the calling, typing and memory
1409overhead by using function call syntax and a fixed number of parameters.
1410
1411See the L<AE> manpage for details.
1412
1413=cut
1414
1415package AE;
1416
1417our $VERSION = $AnyEvent::VERSION;
1418
1419# fall back to the main API by default - backends and AnyEvent::Base
1420# implementations can overwrite these.
1421
1422sub io($$$) {
1423 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
1424}
1425
1426sub timer($$$) {
1427 AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
1428}
1429
1430sub signal($$) {
1431 AnyEvent->signal (signal => $_[0], cb => $_[1])
1432}
1433
1434sub child($$) {
1435 AnyEvent->child (pid => $_[0], cb => $_[1])
1436}
1437
1438sub idle($) {
1439 AnyEvent->idle (cb => $_[0])
1440}
1441
1442sub cv(;&) {
1443 AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
1444}
1445
1446sub now() {
1447 AnyEvent->now
1448}
1449
1450sub now_update() {
1451 AnyEvent->now_update
1452}
1453
1454sub time() {
1455 AnyEvent->time
1456}
1457
1177package AnyEvent::Base; 1458package AnyEvent::Base;
1178 1459
1179# default implementations for many methods 1460# default implementations for many methods
1180 1461
1181BEGIN { 1462sub time {
1463 eval q{ # poor man's autoloading {}
1464 # probe for availability of Time::HiRes
1182 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1465 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1466 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1183 *_time = \&Time::HiRes::time; 1467 *AE::time = \&Time::HiRes::time;
1184 # if (eval "use POSIX (); (POSIX::times())... 1468 # if (eval "use POSIX (); (POSIX::times())...
1185 } else { 1469 } else {
1470 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1186 *_time = sub { time }; # epic fail 1471 *AE::time = sub (){ time }; # epic fail
1472 }
1473
1474 *time = sub { AE::time }; # different prototypes
1475 };
1476 die if $@;
1477
1478 &time
1479}
1480
1481*now = \&time;
1482
1483sub now_update { }
1484
1485sub _poll {
1486 Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
1487}
1488
1489# default implementation for ->condvar
1490# in fact, the default should not be overwritten
1491
1492sub condvar {
1493 eval q{ # poor man's autoloading {}
1494 *condvar = sub {
1495 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1496 };
1497
1498 *AE::cv = sub (;&) {
1499 bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
1500 };
1501 };
1502 die if $@;
1503
1504 &condvar
1505}
1506
1507# default implementation for ->signal
1508
1509our $HAVE_ASYNC_INTERRUPT;
1510
1511sub _have_async_interrupt() {
1512 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
1513 && eval "use Async::Interrupt 1.02 (); 1")
1514 unless defined $HAVE_ASYNC_INTERRUPT;
1515
1516 $HAVE_ASYNC_INTERRUPT
1517}
1518
1519our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1520our (%SIG_ASY, %SIG_ASY_W);
1521our ($SIG_COUNT, $SIG_TW);
1522
1523# install a dummy wakeup watcher to reduce signal catching latency
1524# used by Impls
1525sub _sig_add() {
1526 unless ($SIG_COUNT++) {
1527 # try to align timer on a full-second boundary, if possible
1528 my $NOW = AE::now;
1529
1530 $SIG_TW = AE::timer
1531 $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1532 $MAX_SIGNAL_LATENCY,
1533 sub { } # just for the PERL_ASYNC_CHECK
1534 ;
1187 } 1535 }
1188} 1536}
1189 1537
1190sub time { _time } 1538sub _sig_del {
1191sub now { _time } 1539 undef $SIG_TW
1192sub now_update { } 1540 unless --$SIG_COUNT;
1193
1194# default implementation for ->condvar
1195
1196sub condvar {
1197 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1198} 1541}
1199 1542
1200# default implementation for ->signal 1543our $_sig_name_init; $_sig_name_init = sub {
1544 eval q{ # poor man's autoloading {}
1545 undef $_sig_name_init;
1201 1546
1202our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1547 if (_have_async_interrupt) {
1548 *sig2num = \&Async::Interrupt::sig2num;
1549 *sig2name = \&Async::Interrupt::sig2name;
1550 } else {
1551 require Config;
1203 1552
1204sub _signal_exec { 1553 my %signame2num;
1205 sysread $SIGPIPE_R, my $dummy, 4; 1554 @signame2num{ split ' ', $Config::Config{sig_name} }
1555 = split ' ', $Config::Config{sig_num};
1206 1556
1207 while (%SIG_EV) { 1557 my @signum2name;
1208 for (keys %SIG_EV) { 1558 @signum2name[values %signame2num] = keys %signame2num;
1209 delete $SIG_EV{$_}; 1559
1210 $_->() for values %{ $SIG_CB{$_} || {} }; 1560 *sig2num = sub($) {
1561 $_[0] > 0 ? shift : $signame2num{+shift}
1562 };
1563 *sig2name = sub ($) {
1564 $_[0] > 0 ? $signum2name[+shift] : shift
1565 };
1211 } 1566 }
1212 } 1567 };
1213} 1568 die if $@;
1569};
1570
1571sub sig2num ($) { &$_sig_name_init; &sig2num }
1572sub sig2name($) { &$_sig_name_init; &sig2name }
1214 1573
1215sub signal { 1574sub signal {
1216 my (undef, %arg) = @_; 1575 eval q{ # poor man's autoloading {}
1576 # probe for availability of Async::Interrupt
1577 if (_have_async_interrupt) {
1578 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1217 1579
1218 unless ($SIGPIPE_R) { 1580 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1219 require Fcntl; 1581 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1220 1582
1221 if (AnyEvent::WIN32) {
1222 require AnyEvent::Util;
1223
1224 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1225 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1226 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1227 } else { 1583 } else {
1584 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1585
1586 if (AnyEvent::WIN32) {
1587 require AnyEvent::Util;
1588
1589 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1590 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
1591 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
1592 } else {
1228 pipe $SIGPIPE_R, $SIGPIPE_W; 1593 pipe $SIGPIPE_R, $SIGPIPE_W;
1229 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; 1594 fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1230 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case 1595 fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1231 1596
1232 # not strictly required, as $^F is normally 2, but let's make sure... 1597 # not strictly required, as $^F is normally 2, but let's make sure...
1233 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1598 fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1234 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1599 fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1600 }
1601
1602 $SIGPIPE_R
1603 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1604
1605 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1235 } 1606 }
1236 1607
1237 $SIGPIPE_R 1608 *signal = $HAVE_ASYNC_INTERRUPT
1238 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; 1609 ? sub {
1610 my (undef, %arg) = @_;
1239 1611
1240 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); 1612 # async::interrupt
1241 }
1242
1243 my $signal = uc $arg{signal} 1613 my $signal = sig2num $arg{signal};
1244 or Carp::croak "required option 'signal' is missing";
1245
1246 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1614 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1615
1616 $SIG_ASY{$signal} ||= new Async::Interrupt
1617 cb => sub { undef $SIG_EV{$signal} },
1618 signal => $signal,
1619 pipe => [$SIGPIPE_R->filenos],
1620 pipe_autodrain => 0,
1621 ;
1622
1623 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1624 }
1625 : sub {
1626 my (undef, %arg) = @_;
1627
1628 # pure perl
1629 my $signal = sig2name $arg{signal};
1630 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1631
1247 $SIG{$signal} ||= sub { 1632 $SIG{$signal} ||= sub {
1248 local $!; 1633 local $!;
1249 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; 1634 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1250 undef $SIG_EV{$signal}; 1635 undef $SIG_EV{$signal};
1636 };
1637
1638 # can't do signal processing without introducing races in pure perl,
1639 # so limit the signal latency.
1640 _sig_add;
1641
1642 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1643 }
1644 ;
1645
1646 *AnyEvent::Base::signal::DESTROY = sub {
1647 my ($signal, $cb) = @{$_[0]};
1648
1649 _sig_del;
1650
1651 delete $SIG_CB{$signal}{$cb};
1652
1653 $HAVE_ASYNC_INTERRUPT
1654 ? delete $SIG_ASY{$signal}
1655 : # delete doesn't work with older perls - they then
1656 # print weird messages, or just unconditionally exit
1657 # instead of getting the default action.
1658 undef $SIG{$signal}
1659 unless keys %{ $SIG_CB{$signal} };
1660 };
1661
1662 *_signal_exec = sub {
1663 $HAVE_ASYNC_INTERRUPT
1664 ? $SIGPIPE_R->drain
1665 : sysread $SIGPIPE_R, (my $dummy), 9;
1666
1667 while (%SIG_EV) {
1668 for (keys %SIG_EV) {
1669 delete $SIG_EV{$_};
1670 $_->() for values %{ $SIG_CB{$_} || {} };
1671 }
1672 }
1673 };
1251 }; 1674 };
1675 die if $@;
1252 1676
1253 bless [$signal, $arg{cb}], "AnyEvent::Base::signal" 1677 &signal
1254}
1255
1256sub AnyEvent::Base::signal::DESTROY {
1257 my ($signal, $cb) = @{$_[0]};
1258
1259 delete $SIG_CB{$signal}{$cb};
1260
1261 # delete doesn't work with older perls - they then
1262 # print weird messages, or just unconditionally exit
1263 # instead of getting the default action.
1264 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1265} 1678}
1266 1679
1267# default implementation for ->child 1680# default implementation for ->child
1268 1681
1269our %PID_CB; 1682our %PID_CB;
1270our $CHLD_W; 1683our $CHLD_W;
1271our $CHLD_DELAY_W; 1684our $CHLD_DELAY_W;
1272our $WNOHANG;
1273 1685
1274sub _sigchld { 1686# used by many Impl's
1275 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1687sub _emit_childstatus($$) {
1688 my (undef, $rpid, $rstatus) = @_;
1689
1690 $_->($rpid, $rstatus)
1276 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1691 for values %{ $PID_CB{$rpid} || {} },
1277 (values %{ $PID_CB{0} || {} }); 1692 values %{ $PID_CB{0} || {} };
1278 }
1279} 1693}
1280 1694
1281sub child { 1695sub child {
1696 eval q{ # poor man's autoloading {}
1697 *_sigchld = sub {
1698 my $pid;
1699
1700 AnyEvent->_emit_childstatus ($pid, $?)
1701 while ($pid = waitpid -1, WNOHANG) > 0;
1702 };
1703
1704 *child = sub {
1282 my (undef, %arg) = @_; 1705 my (undef, %arg) = @_;
1283 1706
1284 defined (my $pid = $arg{pid} + 0) 1707 my $pid = $arg{pid};
1285 or Carp::croak "required option 'pid' is missing"; 1708 my $cb = $arg{cb};
1286 1709
1287 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1710 $PID_CB{$pid}{$cb+0} = $cb;
1288 1711
1289 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1290
1291 unless ($CHLD_W) { 1712 unless ($CHLD_W) {
1292 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1713 $CHLD_W = AE::signal CHLD => \&_sigchld;
1293 # child could be a zombie already, so make at least one round 1714 # child could be a zombie already, so make at least one round
1294 &_sigchld; 1715 &_sigchld;
1295 } 1716 }
1296 1717
1297 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1718 bless [$pid, $cb+0], "AnyEvent::Base::child"
1298} 1719 };
1299 1720
1300sub AnyEvent::Base::child::DESTROY { 1721 *AnyEvent::Base::child::DESTROY = sub {
1301 my ($pid, $cb) = @{$_[0]}; 1722 my ($pid, $icb) = @{$_[0]};
1302 1723
1303 delete $PID_CB{$pid}{$cb}; 1724 delete $PID_CB{$pid}{$icb};
1304 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1725 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1305 1726
1306 undef $CHLD_W unless keys %PID_CB; 1727 undef $CHLD_W unless keys %PID_CB;
1728 };
1729 };
1730 die if $@;
1731
1732 &child
1307} 1733}
1308 1734
1309# idle emulation is done by simply using a timer, regardless 1735# idle emulation is done by simply using a timer, regardless
1310# of whether the process is idle or not, and not letting 1736# of whether the process is idle or not, and not letting
1311# the callback use more than 50% of the time. 1737# the callback use more than 50% of the time.
1312sub idle { 1738sub idle {
1739 eval q{ # poor man's autoloading {}
1740 *idle = sub {
1313 my (undef, %arg) = @_; 1741 my (undef, %arg) = @_;
1314 1742
1315 my ($cb, $w, $rcb) = $arg{cb}; 1743 my ($cb, $w, $rcb) = $arg{cb};
1316 1744
1317 $rcb = sub { 1745 $rcb = sub {
1318 if ($cb) { 1746 if ($cb) {
1319 $w = _time; 1747 $w = _time;
1320 &$cb; 1748 &$cb;
1321 $w = _time - $w; 1749 $w = _time - $w;
1322 1750
1323 # never use more then 50% of the time for the idle watcher, 1751 # never use more then 50% of the time for the idle watcher,
1324 # within some limits 1752 # within some limits
1325 $w = 0.0001 if $w < 0.0001; 1753 $w = 0.0001 if $w < 0.0001;
1326 $w = 5 if $w > 5; 1754 $w = 5 if $w > 5;
1327 1755
1328 $w = AnyEvent->timer (after => $w, cb => $rcb); 1756 $w = AE::timer $w, 0, $rcb;
1329 } else { 1757 } else {
1330 # clean up... 1758 # clean up...
1331 undef $w; 1759 undef $w;
1332 undef $rcb; 1760 undef $rcb;
1761 }
1762 };
1763
1764 $w = AE::timer 0.05, 0, $rcb;
1765
1766 bless \\$cb, "AnyEvent::Base::idle"
1333 } 1767 };
1768
1769 *AnyEvent::Base::idle::DESTROY = sub {
1770 undef $${$_[0]};
1771 };
1334 }; 1772 };
1773 die if $@;
1335 1774
1336 $w = AnyEvent->timer (after => 0.05, cb => $rcb); 1775 &idle
1337
1338 bless \\$cb, "AnyEvent::Base::idle"
1339}
1340
1341sub AnyEvent::Base::idle::DESTROY {
1342 undef $${$_[0]};
1343} 1776}
1344 1777
1345package AnyEvent::CondVar; 1778package AnyEvent::CondVar;
1346 1779
1347our @ISA = AnyEvent::CondVar::Base::; 1780our @ISA = AnyEvent::CondVar::Base::;
1348 1781
1782# only to be used for subclassing
1783sub new {
1784 my $class = shift;
1785 bless AnyEvent->condvar (@_), $class
1786}
1787
1349package AnyEvent::CondVar::Base; 1788package AnyEvent::CondVar::Base;
1350 1789
1351use overload 1790#use overload
1352 '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1791# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1353 fallback => 1; 1792# fallback => 1;
1793
1794# save 300+ kilobytes by dirtily hardcoding overloading
1795${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
1796*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
1797*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
1798${'AnyEvent::CondVar::Base::()'} = 1; # fallback
1799
1800our $WAITING;
1354 1801
1355sub _send { 1802sub _send {
1356 # nop 1803 # nop
1804}
1805
1806sub _wait {
1807 AnyEvent->_poll until $_[0]{_ae_sent};
1357} 1808}
1358 1809
1359sub send { 1810sub send {
1360 my $cv = shift; 1811 my $cv = shift;
1361 $cv->{_ae_sent} = [@_]; 1812 $cv->{_ae_sent} = [@_];
1370 1821
1371sub ready { 1822sub ready {
1372 $_[0]{_ae_sent} 1823 $_[0]{_ae_sent}
1373} 1824}
1374 1825
1375sub _wait {
1376 AnyEvent->one_event while !$_[0]{_ae_sent};
1377}
1378
1379sub recv { 1826sub recv {
1827 unless ($_[0]{_ae_sent}) {
1828 $WAITING
1829 and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
1830
1831 local $WAITING = 1;
1380 $_[0]->_wait; 1832 $_[0]->_wait;
1833 }
1381 1834
1382 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; 1835 $_[0]{_ae_croak}
1383 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] 1836 and Carp::croak $_[0]{_ae_croak};
1837
1838 wantarray
1839 ? @{ $_[0]{_ae_sent} }
1840 : $_[0]{_ae_sent}[0]
1384} 1841}
1385 1842
1386sub cb { 1843sub cb {
1387 $_[0]{_ae_cb} = $_[1] if @_ > 1; 1844 my $cv = shift;
1845
1846 @_
1847 and $cv->{_ae_cb} = shift
1848 and $cv->{_ae_sent}
1849 and (delete $cv->{_ae_cb})->($cv);
1850
1388 $_[0]{_ae_cb} 1851 $cv->{_ae_cb}
1389} 1852}
1390 1853
1391sub begin { 1854sub begin {
1392 ++$_[0]{_ae_counter}; 1855 ++$_[0]{_ae_counter};
1393 $_[0]{_ae_end_cb} = $_[1] if @_ > 1; 1856 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1398 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; 1861 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1399} 1862}
1400 1863
1401# undocumented/compatibility with pre-3.4 1864# undocumented/compatibility with pre-3.4
1402*broadcast = \&send; 1865*broadcast = \&send;
1403*wait = \&_wait; 1866*wait = \&recv;
1404 1867
1405=head1 ERROR AND EXCEPTION HANDLING 1868=head1 ERROR AND EXCEPTION HANDLING
1406 1869
1407In general, AnyEvent does not do any error handling - it relies on the 1870In general, AnyEvent does not do any error handling - it relies on the
1408caller to do that if required. The L<AnyEvent::Strict> module (see also 1871caller to do that if required. The L<AnyEvent::Strict> module (see also
1442C<PERL_ANYEVENT_MODEL>. 1905C<PERL_ANYEVENT_MODEL>.
1443 1906
1444When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1907When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1445model it chooses. 1908model it chooses.
1446 1909
1910When set to C<8> or higher, then AnyEvent will report extra information on
1911which optional modules it loads and how it implements certain features.
1912
1447=item C<PERL_ANYEVENT_STRICT> 1913=item C<PERL_ANYEVENT_STRICT>
1448 1914
1449AnyEvent does not do much argument checking by default, as thorough 1915AnyEvent does not do much argument checking by default, as thorough
1450argument checking is very costly. Setting this variable to a true value 1916argument checking is very costly. Setting this variable to a true value
1451will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1917will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1452check the arguments passed to most method calls. If it finds any problems, 1918check the arguments passed to most method calls. If it finds any problems,
1453it will croak. 1919it will croak.
1454 1920
1455In other words, enables "strict" mode. 1921In other words, enables "strict" mode.
1456 1922
1457Unlike C<use strict>, it is definitely recommended to keep it off in 1923Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1458production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1924>>, it is definitely recommended to keep it off in production. Keeping
1459developing programs can be very useful, however. 1925C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1926can be very useful, however.
1460 1927
1461=item C<PERL_ANYEVENT_MODEL> 1928=item C<PERL_ANYEVENT_MODEL>
1462 1929
1463This can be used to specify the event model to be used by AnyEvent, before 1930This can be used to specify the event model to be used by AnyEvent, before
1464auto detection and -probing kicks in. It must be a string consisting 1931auto detection and -probing kicks in. It must be a string consisting
1467used as event model. If it fails to load AnyEvent will proceed with 1934used as event model. If it fails to load AnyEvent will proceed with
1468auto detection and -probing. 1935auto detection and -probing.
1469 1936
1470This functionality might change in future versions. 1937This functionality might change in future versions.
1471 1938
1472For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1939For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1473could start your program like this: 1940could start your program like this:
1474 1941
1475 PERL_ANYEVENT_MODEL=Perl perl ... 1942 PERL_ANYEVENT_MODEL=Perl perl ...
1476 1943
1477=item C<PERL_ANYEVENT_PROTOCOLS> 1944=item C<PERL_ANYEVENT_PROTOCOLS>
1526 1993
1527When neither C<ca_file> nor C<ca_path> was specified during 1994When neither C<ca_file> nor C<ca_path> was specified during
1528L<AnyEvent::TLS> context creation, and either of these environment 1995L<AnyEvent::TLS> context creation, and either of these environment
1529variables exist, they will be used to specify CA certificate locations 1996variables exist, they will be used to specify CA certificate locations
1530instead of a system-dependent default. 1997instead of a system-dependent default.
1998
1999=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
2000
2001When these are set to C<1>, then the respective modules are not
2002loaded. Mostly good for testing AnyEvent itself.
1531 2003
1532=back 2004=back
1533 2005
1534=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 2006=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1535 2007
1593 warn "read: $input\n"; # output what has been read 2065 warn "read: $input\n"; # output what has been read
1594 $cv->send if $input =~ /^q/i; # quit program if /^q/i 2066 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1595 }, 2067 },
1596 ); 2068 );
1597 2069
1598 my $time_watcher; # can only be used once
1599
1600 sub new_timer {
1601 $timer = AnyEvent->timer (after => 1, cb => sub { 2070 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1602 warn "timeout\n"; # print 'timeout' about every second 2071 warn "timeout\n"; # print 'timeout' at most every second
1603 &new_timer; # and restart the time
1604 }); 2072 });
1605 }
1606
1607 new_timer; # create first timer
1608 2073
1609 $cv->recv; # wait until user enters /^q/i 2074 $cv->recv; # wait until user enters /^q/i
1610 2075
1611=head1 REAL-WORLD EXAMPLE 2076=head1 REAL-WORLD EXAMPLE
1612 2077
1685 2150
1686The actual code goes further and collects all errors (C<die>s, exceptions) 2151The actual code goes further and collects all errors (C<die>s, exceptions)
1687that occurred during request processing. The C<result> method detects 2152that occurred during request processing. The C<result> method detects
1688whether an exception as thrown (it is stored inside the $txn object) 2153whether an exception as thrown (it is stored inside the $txn object)
1689and just throws the exception, which means connection errors and other 2154and just throws the exception, which means connection errors and other
1690problems get reported tot he code that tries to use the result, not in a 2155problems get reported to the code that tries to use the result, not in a
1691random callback. 2156random callback.
1692 2157
1693All of this enables the following usage styles: 2158All of this enables the following usage styles:
1694 2159
16951. Blocking: 21601. Blocking:
1743through AnyEvent. The benchmark creates a lot of timers (with a zero 2208through AnyEvent. The benchmark creates a lot of timers (with a zero
1744timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 2209timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1745which it is), lets them fire exactly once and destroys them again. 2210which it is), lets them fire exactly once and destroys them again.
1746 2211
1747Source code for this benchmark is found as F<eg/bench> in the AnyEvent 2212Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1748distribution. 2213distribution. It uses the L<AE> interface, which makes a real difference
2214for the EV and Perl backends only.
1749 2215
1750=head3 Explanation of the columns 2216=head3 Explanation of the columns
1751 2217
1752I<watcher> is the number of event watchers created/destroyed. Since 2218I<watcher> is the number of event watchers created/destroyed. Since
1753different event models feature vastly different performances, each event 2219different event models feature vastly different performances, each event
1774watcher. 2240watcher.
1775 2241
1776=head3 Results 2242=head3 Results
1777 2243
1778 name watchers bytes create invoke destroy comment 2244 name watchers bytes create invoke destroy comment
1779 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 2245 EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1780 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 2246 EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1781 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 2247 Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1782 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 2248 Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1783 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 2249 Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1784 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 2250 Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1785 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll 2251 IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1786 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll 2252 IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1787 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 2253 Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1788 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 2254 Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1789 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 2255 POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1790 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 2256 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1791 2257
1792=head3 Discussion 2258=head3 Discussion
1793 2259
1794The benchmark does I<not> measure scalability of the event loop very 2260The benchmark does I<not> measure scalability of the event loop very
1795well. For example, a select-based event loop (such as the pure perl one) 2261well. For example, a select-based event loop (such as the pure perl one)
1807benchmark machine, handling an event takes roughly 1600 CPU cycles with 2273benchmark machine, handling an event takes roughly 1600 CPU cycles with
1808EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU 2274EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1809cycles with POE. 2275cycles with POE.
1810 2276
1811C<EV> is the sole leader regarding speed and memory use, which are both 2277C<EV> is the sole leader regarding speed and memory use, which are both
1812maximal/minimal, respectively. Even when going through AnyEvent, it uses 2278maximal/minimal, respectively. When using the L<AE> API there is zero
2279overhead (when going through the AnyEvent API create is about 5-6 times
2280slower, with other times being equal, so still uses far less memory than
1813far less memory than any other event loop and is still faster than Event 2281any other event loop and is still faster than Event natively).
1814natively.
1815 2282
1816The pure perl implementation is hit in a few sweet spots (both the 2283The pure perl implementation is hit in a few sweet spots (both the
1817constant timeout and the use of a single fd hit optimisations in the perl 2284constant timeout and the use of a single fd hit optimisations in the perl
1818interpreter and the backend itself). Nevertheless this shows that it 2285interpreter and the backend itself). Nevertheless this shows that it
1819adds very little overhead in itself. Like any select-based backend its 2286adds very little overhead in itself. Like any select-based backend its
1893In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 2360In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1894(1%) are active. This mirrors the activity of large servers with many 2361(1%) are active. This mirrors the activity of large servers with many
1895connections, most of which are idle at any one point in time. 2362connections, most of which are idle at any one point in time.
1896 2363
1897Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 2364Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1898distribution. 2365distribution. It uses the L<AE> interface, which makes a real difference
2366for the EV and Perl backends only.
1899 2367
1900=head3 Explanation of the columns 2368=head3 Explanation of the columns
1901 2369
1902I<sockets> is the number of sockets, and twice the number of "servers" (as 2370I<sockets> is the number of sockets, and twice the number of "servers" (as
1903each server has a read and write socket end). 2371each server has a read and write socket end).
1911a new one that moves the timeout into the future. 2379a new one that moves the timeout into the future.
1912 2380
1913=head3 Results 2381=head3 Results
1914 2382
1915 name sockets create request 2383 name sockets create request
1916 EV 20000 69.01 11.16 2384 EV 20000 62.66 7.99
1917 Perl 20000 73.32 35.87 2385 Perl 20000 68.32 32.64
1918 IOAsync 20000 157.00 98.14 epoll 2386 IOAsync 20000 174.06 101.15 epoll
1919 IOAsync 20000 159.31 616.06 poll 2387 IOAsync 20000 174.67 610.84 poll
1920 Event 20000 212.62 257.32 2388 Event 20000 202.69 242.91
1921 Glib 20000 651.16 1896.30 2389 Glib 20000 557.01 1689.52
1922 POE 20000 349.67 12317.24 uses POE::Loop::Event 2390 POE 20000 341.54 12086.32 uses POE::Loop::Event
1923 2391
1924=head3 Discussion 2392=head3 Discussion
1925 2393
1926This benchmark I<does> measure scalability and overall performance of the 2394This benchmark I<does> measure scalability and overall performance of the
1927particular event loop. 2395particular event loop.
2053As you can see, the AnyEvent + EV combination even beats the 2521As you can see, the AnyEvent + EV combination even beats the
2054hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 2522hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2055backend easily beats IO::Lambda and POE. 2523backend easily beats IO::Lambda and POE.
2056 2524
2057And even the 100% non-blocking version written using the high-level (and 2525And even the 100% non-blocking version written using the high-level (and
2058slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a 2526slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2059large margin, even though it does all of DNS, tcp-connect and socket I/O 2527higher level ("unoptimised") abstractions by a large margin, even though
2060in a non-blocking way. 2528it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2061 2529
2062The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and 2530The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2063F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are 2531F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2064part of the IO::lambda distribution and were used without any changes. 2532part of the IO::Lambda distribution and were used without any changes.
2065 2533
2066 2534
2067=head1 SIGNALS 2535=head1 SIGNALS
2068 2536
2069AnyEvent currently installs handlers for these signals: 2537AnyEvent currently installs handlers for these signals:
2074 2542
2075A handler for C<SIGCHLD> is installed by AnyEvent's child watcher 2543A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
2076emulation for event loops that do not support them natively. Also, some 2544emulation for event loops that do not support them natively. Also, some
2077event loops install a similar handler. 2545event loops install a similar handler.
2078 2546
2079If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will 2547Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2080reset it to default, to avoid losing child exit statuses. 2548AnyEvent will reset it to default, to avoid losing child exit statuses.
2081 2549
2082=item SIGPIPE 2550=item SIGPIPE
2083 2551
2084A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> 2552A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2085when AnyEvent gets loaded. 2553when AnyEvent gets loaded.
2103 if $SIG{CHLD} eq 'IGNORE'; 2571 if $SIG{CHLD} eq 'IGNORE';
2104 2572
2105$SIG{PIPE} = sub { } 2573$SIG{PIPE} = sub { }
2106 unless defined $SIG{PIPE}; 2574 unless defined $SIG{PIPE};
2107 2575
2576=head1 RECOMMENDED/OPTIONAL MODULES
2577
2578One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2579its built-in modules) are required to use it.
2580
2581That does not mean that AnyEvent won't take advantage of some additional
2582modules if they are installed.
2583
2584This section explains which additional modules will be used, and how they
2585affect AnyEvent's operation.
2586
2587=over 4
2588
2589=item L<Async::Interrupt>
2590
2591This slightly arcane module is used to implement fast signal handling: To
2592my knowledge, there is no way to do completely race-free and quick
2593signal handling in pure perl. To ensure that signals still get
2594delivered, AnyEvent will start an interval timer to wake up perl (and
2595catch the signals) with some delay (default is 10 seconds, look for
2596C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2597
2598If this module is available, then it will be used to implement signal
2599catching, which means that signals will not be delayed, and the event loop
2600will not be interrupted regularly, which is more efficient (and good for
2601battery life on laptops).
2602
2603This affects not just the pure-perl event loop, but also other event loops
2604that have no signal handling on their own (e.g. Glib, Tk, Qt).
2605
2606Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
2607and either employ their own workarounds (POE) or use AnyEvent's workaround
2608(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
2609does nothing for those backends.
2610
2611=item L<EV>
2612
2613This module isn't really "optional", as it is simply one of the backend
2614event loops that AnyEvent can use. However, it is simply the best event
2615loop available in terms of features, speed and stability: It supports
2616the AnyEvent API optimally, implements all the watcher types in XS, does
2617automatic timer adjustments even when no monotonic clock is available,
2618can take avdantage of advanced kernel interfaces such as C<epoll> and
2619C<kqueue>, and is the fastest backend I<by far>. You can even embed
2620L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2621
2622If you only use backends that rely on another event loop (e.g. C<Tk>),
2623then this module will do nothing for you.
2624
2625=item L<Guard>
2626
2627The guard module, when used, will be used to implement
2628C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2629lot less memory), but otherwise doesn't affect guard operation much. It is
2630purely used for performance.
2631
2632=item L<JSON> and L<JSON::XS>
2633
2634One of these modules is required when you want to read or write JSON data
2635via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
2636advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2637
2638=item L<Net::SSLeay>
2639
2640Implementing TLS/SSL in Perl is certainly interesting, but not very
2641worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2642the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2643
2644=item L<Time::HiRes>
2645
2646This module is part of perl since release 5.008. It will be used when the
2647chosen event library does not come with a timing source of its own. The
2648pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
2649try to use a monotonic clock for timing stability.
2650
2651=back
2652
2653
2108=head1 FORK 2654=head1 FORK
2109 2655
2110Most event libraries are not fork-safe. The ones who are usually are 2656Most event libraries are not fork-safe. The ones who are usually are
2111because they rely on inefficient but fork-safe C<select> or C<poll> 2657because they rely on inefficient but fork-safe C<select> or C<poll> calls
2112calls. Only L<EV> is fully fork-aware. 2658- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
2659are usually badly thought-out hacks that are incompatible with fork in
2660one way or another. Only L<EV> is fully fork-aware and ensures that you
2661continue event-processing in both parent and child (or both, if you know
2662what you are doing).
2663
2664This means that, in general, you cannot fork and do event processing in
2665the child if the event library was initialised before the fork (which
2666usually happens when the first AnyEvent watcher is created, or the library
2667is loaded).
2113 2668
2114If you have to fork, you must either do so I<before> creating your first 2669If you have to fork, you must either do so I<before> creating your first
2115watcher OR you must not use AnyEvent at all in the child. 2670watcher OR you must not use AnyEvent at all in the child OR you must do
2671something completely out of the scope of AnyEvent.
2672
2673The problem of doing event processing in the parent I<and> the child
2674is much more complicated: even for backends that I<are> fork-aware or
2675fork-safe, their behaviour is not usually what you want: fork clones all
2676watchers, that means all timers, I/O watchers etc. are active in both
2677parent and child, which is almost never what you want. USing C<exec>
2678to start worker children from some kind of manage rprocess is usually
2679preferred, because it is much easier and cleaner, at the expense of having
2680to have another binary.
2116 2681
2117 2682
2118=head1 SECURITY CONSIDERATIONS 2683=head1 SECURITY CONSIDERATIONS
2119 2684
2120AnyEvent can be forced to load any event model via 2685AnyEvent can be forced to load any event model via
2150pronounced). 2715pronounced).
2151 2716
2152 2717
2153=head1 SEE ALSO 2718=head1 SEE ALSO
2154 2719
2720Tutorial/Introduction: L<AnyEvent::Intro>.
2721
2722FAQ: L<AnyEvent::FAQ>.
2723
2155Utility functions: L<AnyEvent::Util>. 2724Utility functions: L<AnyEvent::Util>.
2156 2725
2157Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 2726Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2158L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2727L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2159 2728
2160Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2729Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2161L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2730L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2162L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2731L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2163L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>. 2732L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2164 2733
2165Non-blocking file handles, sockets, TCP clients and 2734Non-blocking file handles, sockets, TCP clients and
2166servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>. 2735servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2167 2736
2168Asynchronous DNS: L<AnyEvent::DNS>. 2737Asynchronous DNS: L<AnyEvent::DNS>.
2169 2738
2170Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, 2739Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2171L<Coro::Event>,
2172 2740
2173Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>, 2741Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2174L<AnyEvent::HTTP>. 2742L<AnyEvent::HTTP>.
2175 2743
2176 2744
2177=head1 AUTHOR 2745=head1 AUTHOR
2178 2746

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