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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
368 403
369This watcher might use C<%SIG> (depending on the event loop used), 404This watcher might use C<%SIG> (depending on the event loop used),
370so programs overwriting those signals directly will likely not work 405so programs overwriting those signals directly will likely not work
371correctly. 406correctly.
372 407
408Example: exit on SIGINT
409
410 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
411
412=head3 Restart Behaviour
413
414While restart behaviour is up to the event loop implementation, most will
415not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
416pure perl implementation).
417
418=head3 Safe/Unsafe Signals
419
420Perl signals can be either "safe" (synchronous to opcode handling) or
421"unsafe" (asynchronous) - the former might get delayed indefinitely, the
422latter might corrupt your memory.
423
424AnyEvent signal handlers are, in addition, synchronous to the event loop,
425i.e. they will not interrupt your running perl program but will only be
426called as part of the normal event handling (just like timer, I/O etc.
427callbacks, too).
428
429=head3 Signal Races, Delays and Workarounds
430
373Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not 431Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
374support attaching callbacks to signals, which is a pity, as you cannot do 432callbacks to signals in a generic way, which is a pity, as you cannot
375race-free signal handling in perl. AnyEvent will try to do it's best, but 433do race-free signal handling in perl, requiring C libraries for
434this. AnyEvent will try to do its best, which means in some cases,
376in some cases, signals will be delayed. The maximum time a signal might 435signals will be delayed. The maximum time a signal might be delayed is
377be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 436specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
378seconds). This variable can be changed only before the first signal 437variable can be changed only before the first signal watcher is created,
379watcher is created, and should be left alone otherwise. Higher values 438and should be left alone otherwise. This variable determines how often
439AnyEvent polls for signals (in case a wake-up was missed). Higher values
380will cause fewer spurious wake-ups, which is better for power and CPU 440will cause fewer spurious wake-ups, which is better for power and CPU
441saving.
442
381saving. All these problems can be avoided by installing the optional 443All these problems can be avoided by installing the optional
382L<Async::Interrupt> module. 444L<Async::Interrupt> module, which works with most event loops. It will not
383 445work with inherently broken event loops such as L<Event> or L<Event::Lib>
384Example: exit on SIGINT 446(and not with L<POE> currently, as POE does its own workaround with
385 447one-second latency). For those, you just have to suffer the delays.
386 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
387 448
388=head2 CHILD PROCESS WATCHERS 449=head2 CHILD PROCESS WATCHERS
389 450
451 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
452
390You 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.
391 454
392The 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,
393watches for any child process exit). The watcher will triggered only when 456using C<0> watches for any child process exit, on others this will
394the child process has finished and an exit status is available, not on 457croak). The watcher will be triggered only when the child process has
395any trace events (stopped/continued). 458finished and an exit status is available, not on any trace events
459(stopped/continued).
396 460
397The 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
398waitpid), 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
399callback arguments. 463callback arguments.
400 464
418thing 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
419watcher before you C<fork> the child (alternatively, you can call 483watcher before you C<fork> the child (alternatively, you can call
420C<AnyEvent::detect>). 484C<AnyEvent::detect>).
421 485
422As most event loops do not support waiting for child events, they will be 486As most event loops do not support waiting for child events, they will be
423emulated by AnyEvent in most cases, in which the latency and race problems 487emulated by AnyEvent in most cases, in which case the latency and race
424mentioned in the description of signal watchers apply. 488problems mentioned in the description of signal watchers apply.
425 489
426Example: fork a process and wait for it 490Example: fork a process and wait for it
427 491
428 my $done = AnyEvent->condvar; 492 my $done = AnyEvent->condvar;
429 493
441 # do something else, then wait for process exit 505 # do something else, then wait for process exit
442 $done->recv; 506 $done->recv;
443 507
444=head2 IDLE WATCHERS 508=head2 IDLE WATCHERS
445 509
446Sometimes there is a need to do something, but it is not so important 510 $w = AnyEvent->idle (cb => <callback>);
447to do it instantly, but only when there is nothing better to do. This
448"nothing better to do" is usually defined to be "no other events need
449attention by the event loop".
450 511
451Idle watchers ideally get invoked when the event loop has nothing 512This will repeatedly invoke the callback after the process becomes idle,
452better 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.
453events. Instead of blocking, the idle watcher is invoked.
454 514
455Most 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
456EV, 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
457will simply call the callback "from time to time". 526will simply call the callback "from time to time".
458 527
459Example: read lines from STDIN, but only process them when the 528Example: read lines from STDIN, but only process them when the
460program is otherwise idle: 529program is otherwise idle:
476 }); 545 });
477 }); 546 });
478 547
479=head2 CONDITION VARIABLES 548=head2 CONDITION VARIABLES
480 549
550 $cv = AnyEvent->condvar;
551
552 $cv->send (<list>);
553 my @res = $cv->recv;
554
481If 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
482require you to run some blocking "loop", "run" or similar function that 556require you to run some blocking "loop", "run" or similar function that
483will actively watch for new events and call your callbacks. 557will actively watch for new events and call your callbacks.
484 558
485AnyEvent is slightly different: it expects somebody else to run the event 559AnyEvent is slightly different: it expects somebody else to run the event
486loop and will only block when necessary (usually when told by the user). 560loop and will only block when necessary (usually when told by the user).
487 561
488The instrument to do that is called a "condition variable", so called 562The tool to do that is called a "condition variable", so called because
489because they represent a condition that must become true. 563they represent a condition that must become true.
490 564
491Now is probably a good time to look at the examples further below. 565Now is probably a good time to look at the examples further below.
492 566
493Condition variables can be created by calling the C<< AnyEvent->condvar 567Condition variables can be created by calling the C<< AnyEvent->condvar
494>> method, usually without arguments. The only argument pair allowed is 568>> method, usually without arguments. The only argument pair allowed is
499After creation, the condition variable is "false" until it becomes "true" 573After creation, the condition variable is "false" until it becomes "true"
500by 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
501were 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<<
502->send >> method). 576->send >> method).
503 577
504Condition variables are similar to callbacks, except that you can 578Since condition variables are the most complex part of the AnyEvent API, here are
505optionally 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:
506in time where multiple outstanding events have been processed. And yet 580
507another way to call them is transactions - each condition variable can be 581=over 4
508used to represent a transaction, which finishes at some point and delivers 582
509a 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
510 601
511Condition variables are very useful to signal that something has finished, 602Condition variables are very useful to signal that something has finished,
512for example, if you write a module that does asynchronous http requests, 603for example, if you write a module that does asynchronous http requests,
513then a condition variable would be the ideal candidate to signal the 604then a condition variable would be the ideal candidate to signal the
514availability of results. The user can either act when the callback is 605availability of results. The user can either act when the callback is
527 618
528Condition variables are represented by hash refs in perl, and the keys 619Condition variables are represented by hash refs in perl, and the keys
529used 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
530easy (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
531AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call 622AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
532it's C<new> method in your own C<new> method. 623its C<new> method in your own C<new> method.
533 624
534There are two "sides" to a condition variable - the "producer side" which 625There are two "sides" to a condition variable - the "producer side" which
535eventually calls C<< -> send >>, and the "consumer side", which waits 626eventually calls C<< -> send >>, and the "consumer side", which waits
536for the send to occur. 627for the send to occur.
537 628
538Example: wait for a timer. 629Example: wait for a timer.
539 630
540 # wait till the result is ready 631 # condition: "wait till the timer is fired"
541 my $result_ready = AnyEvent->condvar; 632 my $timer_fired = AnyEvent->condvar;
542 633
543 # do something such as adding a timer 634 # create the timer - we could wait for, say
544 # or socket watcher the calls $result_ready->send 635 # a handle becomign ready, or even an
545 # when the "result" is ready. 636 # AnyEvent::HTTP request to finish, but
546 # in this case, we simply use a timer: 637 # in this case, we simply use a timer:
547 my $w = AnyEvent->timer ( 638 my $w = AnyEvent->timer (
548 after => 1, 639 after => 1,
549 cb => sub { $result_ready->send }, 640 cb => sub { $timer_fired->send },
550 ); 641 );
551 642
552 # this "blocks" (while handling events) till the callback 643 # this "blocks" (while handling events) till the callback
553 # calls -<send 644 # calls ->send
554 $result_ready->recv; 645 $timer_fired->recv;
555 646
556Example: wait for a timer, but take advantage of the fact that condition 647Example: wait for a timer, but take advantage of the fact that condition
557variables are also callable directly. 648variables are also callable directly.
558 649
559 my $done = AnyEvent->condvar; 650 my $done = AnyEvent->condvar;
602they were a code reference). Calling them directly is the same as calling 693they were a code reference). Calling them directly is the same as calling
603C<send>. 694C<send>.
604 695
605=item $cv->croak ($error) 696=item $cv->croak ($error)
606 697
607Similar to send, but causes all call's to C<< ->recv >> to invoke 698Similar to send, but causes all calls to C<< ->recv >> to invoke
608C<Carp::croak> with the given error message/object/scalar. 699C<Carp::croak> with the given error message/object/scalar.
609 700
610This can be used to signal any errors to the condition variable 701This can be used to signal any errors to the condition variable
611user/consumer. Doing it this way instead of calling C<croak> directly 702user/consumer. Doing it this way instead of calling C<croak> directly
612delays the error detetcion, but has the overwhelmign advantage that it 703delays the error detection, but has the overwhelming advantage that it
613diagnoses the error at the place where the result is expected, and not 704diagnoses the error at the place where the result is expected, and not
614deep in some event clalback without connection to the actual code causing 705deep in some event callback with no connection to the actual code causing
615the problem. 706the problem.
616 707
617=item $cv->begin ([group callback]) 708=item $cv->begin ([group callback])
618 709
619=item $cv->end 710=item $cv->end
622one. 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
623to use a condition variable for the whole process. 714to use a condition variable for the whole process.
624 715
625Every 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
626C<< ->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
627>>, 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
628is 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
629callback 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.
630 722
631You 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
632sends), 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
633condition (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).
634 726
656one 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
657sending. 749sending.
658 750
659The ping example mentioned above is slightly more complicated, as the 751The ping example mentioned above is slightly more complicated, as the
660there 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
661begung can potentially be zero: 753begun can potentially be zero:
662 754
663 my $cv = AnyEvent->condvar; 755 my $cv = AnyEvent->condvar;
664 756
665 my %result; 757 my %result;
666 $cv->begin (sub { $cv->send (\%result) }); 758 $cv->begin (sub { shift->send (\%result) });
667 759
668 for my $host (@list_of_hosts) { 760 for my $host (@list_of_hosts) {
669 $cv->begin; 761 $cv->begin;
670 ping_host_then_call_callback $host, sub { 762 ping_host_then_call_callback $host, sub {
671 $result{$host} = ...; 763 $result{$host} = ...;
687to 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
688C<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
689doesn't execute once). 781doesn't execute once).
690 782
691This is the general pattern when you "fan out" into multiple (but 783This is the general pattern when you "fan out" into multiple (but
692potentially 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
693the 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
694subrequest you start, call C<begin> and for each subrequest you finish, 786subrequest you start, call C<begin> and for each subrequest you finish,
695call C<end>. 787call C<end>.
696 788
697=back 789=back
704=over 4 796=over 4
705 797
706=item $cv->recv 798=item $cv->recv
707 799
708Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 800Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
709>> methods have been called on c<$cv>, while servicing other watchers 801>> methods have been called on C<$cv>, while servicing other watchers
710normally. 802normally.
711 803
712You 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
713will return immediately. 805will return immediately.
714 806
731caller 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
732condition variables with some kind of request results and supporting 824condition variables with some kind of request results and supporting
733callbacks so the caller knows that getting the result will not block, 825callbacks so the caller knows that getting the result will not block,
734while still supporting blocking waits if the caller so desires). 826while still supporting blocking waits if the caller so desires).
735 827
736You 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
737only calling C<< ->recv >> from within that callback (or at a later 829only calling C<< ->recv >> from within that callback (or at a later
738time). 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
739waits otherwise. 831waits otherwise.
740 832
741=item $bool = $cv->ready 833=item $bool = $cv->ready
747 839
748This is a mutator function that returns the callback set and optionally 840This is a mutator function that returns the callback set and optionally
749replaces it before doing so. 841replaces it before doing so.
750 842
751The 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
752C<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
753variable itself. Calling C<recv> inside the callback or at any later time 845condition variable itself. If the condition is already true, the
754is 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.
755 848
756=back 849=back
757 850
758=head1 SUPPORTED EVENT LOOPS/BACKENDS 851=head1 SUPPORTED EVENT LOOPS/BACKENDS
759 852
762=over 4 855=over 4
763 856
764=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.
765 858
766EV 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
767use. 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
768that, will fall back to its own pure-perl implementation, which is 861pure-perl implementation, which is available everywhere as it comes with
769available everywhere as it comes with AnyEvent itself. 862AnyEvent itself.
770 863
771 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 864 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
772 AnyEvent::Impl::Event based on Event, very stable, few glitches.
773 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 865 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
774 866
775=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.
776 868
777These 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
778is 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
779them. This means that AnyEvent will automatically pick the right backend 871them. This means that AnyEvent will automatically pick the right backend
780when the main program loads an event module before anything starts to 872when the main program loads an event module before anything starts to
781create watchers. Nothing special needs to be done by the main program. 873create watchers. Nothing special needs to be done by the main program.
782 874
875 AnyEvent::Impl::Event based on Event, very stable, few glitches.
783 AnyEvent::Impl::Glib based on Glib, slow but very stable. 876 AnyEvent::Impl::Glib based on Glib, slow but very stable.
784 AnyEvent::Impl::Tk based on Tk, very broken. 877 AnyEvent::Impl::Tk based on Tk, very broken.
785 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 878 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
786 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::FLTK2 based on FLTK (fltk 2 binding).
787 884
788=item Backends with special needs. 885=item Backends with special needs.
789 886
790Qt requires the Qt::Application to be instantiated first, but will 887Qt requires the Qt::Application to be instantiated first, but will
791otherwise be picked up automatically. As long as the main program 888otherwise be picked up automatically. As long as the main program
792instantiates the application before any AnyEvent watchers are created, 889instantiates the application before any AnyEvent watchers are created,
793everything should just work. 890everything should just work.
794 891
795 AnyEvent::Impl::Qt based on Qt. 892 AnyEvent::Impl::Qt based on Qt.
796 893
797Support for IO::Async can only be partial, as it is too broken and
798architecturally limited to even support the AnyEvent API. It also
799is the only event loop that needs the loop to be set explicitly, so
800it can only be used by a main program knowing about AnyEvent. See
801L<AnyEvent::Impl::Async> for the gory details.
802
803 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
804
805=item Event loops that are indirectly supported via other backends. 894=item Event loops that are indirectly supported via other backends.
806 895
807Some event loops can be supported via other modules: 896Some event loops can be supported via other modules:
808 897
809There is no direct support for WxWidgets (L<Wx>) or L<Prima>. 898There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
834Contains C<undef> until the first watcher is being created, before the 923Contains C<undef> until the first watcher is being created, before the
835backend has been autodetected. 924backend has been autodetected.
836 925
837Afterwards it contains the event model that is being used, which is the 926Afterwards it contains the event model that is being used, which is the
838name of the Perl class implementing the model. This class is usually one 927name of the Perl class implementing the model. This class is usually one
839of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the 928of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
840case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it 929case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
841will be C<urxvt::anyevent>). 930will be C<urxvt::anyevent>).
842 931
843=item AnyEvent::detect 932=item AnyEvent::detect
844 933
845Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 934Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
846if necessary. You should only call this function right before you would 935if necessary. You should only call this function right before you would
847have 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
848runtime, and not e.g. while initialising of your module. 937runtime, and not e.g. during initialisation of your module.
849 938
850If you need to do some initialisation before AnyEvent watchers are 939If you need to do some initialisation before AnyEvent watchers are
851created, use C<post_detect>. 940created, use C<post_detect>.
852 941
853=item $guard = AnyEvent::post_detect { BLOCK } 942=item $guard = AnyEvent::post_detect { BLOCK }
854 943
855Arranges for the code block to be executed as soon as the event model is 944Arranges for the code block to be executed as soon as the event model is
856autodetected (or immediately if this has already happened). 945autodetected (or immediately if that has already happened).
857 946
858The block will be executed I<after> the actual backend has been detected 947The block will be executed I<after> the actual backend has been detected
859(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been 948(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
860created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do 949created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
861other initialisations - see the sources of L<AnyEvent::Strict> or 950other initialisations - see the sources of L<AnyEvent::Strict> or
865event module detection too early, for example, L<AnyEvent::AIO> creates 954event module detection too early, for example, L<AnyEvent::AIO> creates
866and installs the global L<IO::AIO> watcher in a C<post_detect> block to 955and installs the global L<IO::AIO> watcher in a C<post_detect> block to
867avoid autodetecting the event module at load time. 956avoid autodetecting the event module at load time.
868 957
869If called in scalar or list context, then it creates and returns an object 958If called in scalar or list context, then it creates and returns an object
870that automatically removes the callback again when it is destroyed. See 959that automatically removes the callback again when it is destroyed (or
960C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
871L<Coro::BDB> for a case where this is useful. 961a case where this is useful.
962
963Example: Create a watcher for the IO::AIO module and store it in
964C<$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 ||= $guard;
872 978
873=item @AnyEvent::post_detect 979=item @AnyEvent::post_detect
874 980
875If there are any code references in this array (you can C<push> to it 981If there are any code references in this array (you can C<push> to it
876before or after loading AnyEvent), then they will called directly after 982before or after loading AnyEvent), then they will be called directly
877the event loop has been chosen. 983after the event loop has been chosen.
878 984
879You should check C<$AnyEvent::MODEL> before adding to this array, though: 985You should check C<$AnyEvent::MODEL> before adding to this array, though:
880if it is defined then the event loop has already been detected, and the 986if it is defined then the event loop has already been detected, and the
881array will be ignored. 987array will be ignored.
882 988
883Best use C<AnyEvent::post_detect { BLOCK }> when your application allows 989Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
884it,as it takes care of these details. 990it, as it takes care of these details.
885 991
886This variable is mainly useful for modules that can do something useful 992This variable is mainly useful for modules that can do something useful
887when AnyEvent is used and thus want to know when it is initialised, but do 993when AnyEvent is used and thus want to know when it is initialised, but do
888not need to even load it by default. This array provides the means to hook 994not need to even load it by default. This array provides the means to hook
889into AnyEvent passively, without loading it. 995into AnyEvent passively, without loading it.
890 996
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;
1049
891=back 1050=back
892 1051
893=head1 WHAT TO DO IN A MODULE 1052=head1 WHAT TO DO IN A MODULE
894 1053
895As a module author, you should C<use AnyEvent> and call AnyEvent methods 1054As a module author, you should C<use AnyEvent> and call AnyEvent methods
905because 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
906events is to stay interactive. 1065events is to stay interactive.
907 1066
908It 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
909requests 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
910called C<results> that returns the results, it should call C<< ->recv >> 1069called C<results> that returns the results, it may call C<< ->recv >>
911freely, 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).
912 1071
913=head1 WHAT TO DO IN THE MAIN PROGRAM 1072=head1 WHAT TO DO IN THE MAIN PROGRAM
914 1073
915There 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
916dictate which event model to use. 1075dictate which event model to use.
917 1076
918If 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
919do 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
920decide 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.
921 1082
922If 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
923Gtk2 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
924event module before loading AnyEvent or any module that uses it: generally 1085event module before loading AnyEvent or any module that uses it: generally
925speaking, 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
926modules might create watchers when they are loaded, and AnyEvent will 1087modules might create watchers when they are loaded, and AnyEvent will
927decide 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
928might chose the wrong one unless you load the correct one yourself. 1089might choose the wrong one unless you load the correct one yourself.
929 1090
930You can chose to use a pure-perl implementation by loading the 1091You can chose to use a pure-perl implementation by loading the
931C<AnyEvent::Impl::Perl> module, which gives you similar behaviour 1092C<AnyEvent::Loop> module, which gives you similar behaviour
932everywhere, but letting AnyEvent chose the model is generally better. 1093everywhere, but letting AnyEvent chose the model is generally better.
933 1094
934=head2 MAINLOOP EMULATION 1095=head2 MAINLOOP EMULATION
935 1096
936Sometimes (often for short test scripts, or even standalone programs who 1097Sometimes (often for short test scripts, or even standalone programs who
951=head1 OTHER MODULES 1112=head1 OTHER MODULES
952 1113
953The following is a non-exhaustive list of additional modules that use 1114The following is a non-exhaustive list of additional modules that use
954AnyEvent 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
955modules 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
956come with AnyEvent, most are available via CPAN. 1117come as part of AnyEvent, the others are available via CPAN.
957 1118
958=over 4 1119=over 4
959 1120
960=item L<AnyEvent::Util> 1121=item L<AnyEvent::Util>
961 1122
962Contains various utility functions that replace often-used but blocking 1123Contains various utility functions that replace often-used blocking
963functions such as C<inet_aton> by event-/callback-based versions. 1124functions such as C<inet_aton> with event/callback-based versions.
964 1125
965=item L<AnyEvent::Socket> 1126=item L<AnyEvent::Socket>
966 1127
967Provides various utility functions for (internet protocol) sockets, 1128Provides various utility functions for (internet protocol) sockets,
968addresses and name resolution. Also functions to create non-blocking tcp 1129addresses and name resolution. Also functions to create non-blocking tcp
970 1131
971=item L<AnyEvent::Handle> 1132=item L<AnyEvent::Handle>
972 1133
973Provide read and write buffers, manages watchers for reads and writes, 1134Provide read and write buffers, manages watchers for reads and writes,
974supports 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
975non-blocking SSL/TLS (via L<AnyEvent::TLS>. 1136non-blocking SSL/TLS (via L<AnyEvent::TLS>).
976 1137
977=item L<AnyEvent::DNS> 1138=item L<AnyEvent::DNS>
978 1139
979Provides rich asynchronous DNS resolver capabilities. 1140Provides rich asynchronous DNS resolver capabilities.
980 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
981=item L<AnyEvent::HTTP> 1165=item L<AnyEvent::DBI>
982 1166
983A 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,
984HTTP 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.
985 1176
986=item L<AnyEvent::HTTPD> 1177=item L<AnyEvent::HTTPD>
987 1178
988Provides a simple web application server framework. 1179A simple embedded webserver.
989 1180
990=item L<AnyEvent::FastPing> 1181=item L<AnyEvent::FastPing>
991 1182
992The fastest ping in the west. 1183The fastest ping in the west.
993
994=item L<AnyEvent::DBI>
995
996Executes L<DBI> requests asynchronously in a proxy process.
997
998=item L<AnyEvent::AIO>
999
1000Truly asynchronous I/O, should be in the toolbox of every event
1001programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
1002together.
1003
1004=item L<AnyEvent::BDB>
1005
1006Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
1007L<BDB> and AnyEvent together.
1008
1009=item L<AnyEvent::GPSD>
1010
1011A non-blocking interface to gpsd, a daemon delivering GPS information.
1012
1013=item L<AnyEvent::IRC>
1014
1015AnyEvent based IRC client module family (replacing the older Net::IRC3).
1016
1017=item L<AnyEvent::XMPP>
1018
1019AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1020Net::XMPP2>.
1021
1022=item L<AnyEvent::IGS>
1023
1024A non-blocking interface to the Internet Go Server protocol (used by
1025L<App::IGS>).
1026
1027=item L<Net::FCP>
1028
1029AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1030of AnyEvent.
1031
1032=item L<Event::ExecFlow>
1033
1034High level API for event-based execution flow control.
1035 1184
1036=item L<Coro> 1185=item L<Coro>
1037 1186
1038Has special support for AnyEvent via L<Coro::AnyEvent>. 1187Has special support for AnyEvent via L<Coro::AnyEvent>.
1039 1188
1043 1192
1044package AnyEvent; 1193package AnyEvent;
1045 1194
1046# basically a tuned-down version of common::sense 1195# basically a tuned-down version of common::sense
1047sub common_sense { 1196sub common_sense {
1048 # no warnings 1197 # from common:.sense 3.4
1049 ${^WARNING_BITS} ^= ${^WARNING_BITS}; 1198 ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
1050 # use strict vars subs 1199 # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
1051 $^H |= 0x00000600; 1200 $^H |= 0x00000600;
1052} 1201}
1053 1202
1054BEGIN { AnyEvent::common_sense } 1203BEGIN { AnyEvent::common_sense }
1055 1204
1056use Carp (); 1205use Carp ();
1057 1206
1058our $VERSION = 4.85; 1207our $VERSION = '5.34';
1059our $MODEL; 1208our $MODEL;
1060 1209
1061our $AUTOLOAD;
1062our @ISA; 1210our @ISA;
1063 1211
1064our @REGISTRY; 1212our @REGISTRY;
1065 1213
1066our $WIN32;
1067
1068our $VERBOSE; 1214our $VERBOSE;
1069 1215
1070BEGIN { 1216BEGIN {
1071 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1217 require "AnyEvent/constants.pl";
1218
1072 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1219 eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1073 1220
1074 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1221 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1075 if ${^TAINT}; 1222 if ${^TAINT};
1076 1223
1077 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1224 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1087 $PROTOCOL{$_} = ++$idx 1234 $PROTOCOL{$_} = ++$idx
1088 for reverse split /\s*,\s*/, 1235 for reverse split /\s*,\s*/,
1089 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 1236 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1090} 1237}
1091 1238
1239our @post_detect;
1240
1241sub post_detect(&) {
1242 my ($cb) = @_;
1243
1244 push @post_detect, $cb;
1245
1246 defined wantarray
1247 ? bless \$cb, "AnyEvent::Util::postdetect"
1248 : ()
1249}
1250
1251sub AnyEvent::Util::postdetect::DESTROY {
1252 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1253}
1254
1255our $POSTPONE_W;
1256our @POSTPONE;
1257
1258sub _postpone_exec {
1259 undef $POSTPONE_W;
1260
1261 &{ shift @POSTPONE }
1262 while @POSTPONE;
1263}
1264
1265sub postpone(&) {
1266 push @POSTPONE, shift;
1267
1268 $POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
1269
1270 ()
1271}
1272
1092my @models = ( 1273our @models = (
1093 [EV:: => AnyEvent::Impl::EV::], 1274 [EV:: => AnyEvent::Impl::EV:: , 1],
1094 [Event:: => AnyEvent::Impl::Event::], 1275 [AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1095 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1096 # everything below here will not be autoprobed 1276 # everything below here will not (normally) be autoprobed
1097 # as the pureperl backend should work everywhere 1277 # as the pure perl backend should work everywhere
1098 # and is usually faster 1278 # and is usually faster
1279 [Event:: => AnyEvent::Impl::Event::, 1],
1099 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers 1280 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1100 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1281 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1282 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1101 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles 1283 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1102 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 1284 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1103 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1285 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1104 [Wx:: => AnyEvent::Impl::POE::], 1286 [Wx:: => AnyEvent::Impl::POE::],
1105 [Prima:: => AnyEvent::Impl::POE::], 1287 [Prima:: => AnyEvent::Impl::POE::],
1106 # IO::Async is just too broken - we would need workarounds for its 1288 [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
1107 # byzantine signal and broken child handling, among others. 1289 [Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1108 # IO::Async is rather hard to detect, as it doesn't have any 1290 [FLTK:: => AnyEvent::Impl::FLTK2::],
1109 # obvious default class.
1110# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1111# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1112# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
1113); 1291);
1114 1292
1115our %method = map +($_ => 1), 1293# all autoloaded methods reserve the complete glob, not just the method slot.
1294# due to bugs in perls method cache implementation.
1116 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1295our @methods = qw(io timer time now now_update signal child idle condvar);
1117 1296
1118our @post_detect;
1119
1120sub post_detect(&) { 1297sub detect() {
1121 my ($cb) = @_; 1298 local $!; # for good measure
1299 local $SIG{__DIE__}; # we use eval
1122 1300
1123 if ($MODEL) { 1301 # free some memory
1124 $cb->(); 1302 *detect = sub () { $MODEL };
1303 # undef &func doesn't correctly update the method cache. grmbl.
1304 # so we delete the whole glob. grmbl.
1305 # otoh, perl doesn't let me undef an active usb, but it lets me free
1306 # a glob with an active sub. hrm. i hope it works, but perl is
1307 # usually buggy in this department. sigh.
1308 delete @{"AnyEvent::"}{@methods};
1309 undef @methods;
1125 1310
1126 1 1311 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
1312 my $model = $1;
1313 $model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
1314 if (eval "require $model") {
1315 $MODEL = $model;
1316 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1127 } else { 1317 } else {
1128 push @post_detect, $cb; 1318 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1129 1319 }
1130 defined wantarray
1131 ? bless \$cb, "AnyEvent::Util::postdetect"
1132 : ()
1133 } 1320 }
1134}
1135 1321
1136sub AnyEvent::Util::postdetect::DESTROY { 1322 # check for already loaded models
1137 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1138}
1139
1140sub detect() {
1141 unless ($MODEL) { 1323 unless ($MODEL) {
1142 local $SIG{__DIE__}; 1324 for (@REGISTRY, @models) {
1143 1325 my ($package, $model) = @$_;
1144 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1326 if (${"$package\::VERSION"} > 0) {
1145 my $model = "AnyEvent::Impl::$1";
1146 if (eval "require $model") { 1327 if (eval "require $model") {
1147 $MODEL = $model; 1328 $MODEL = $model;
1148 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2; 1329 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1149 } else { 1330 last;
1150 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE; 1331 }
1151 } 1332 }
1152 } 1333 }
1153 1334
1154 # check for already loaded models
1155 unless ($MODEL) { 1335 unless ($MODEL) {
1336 # try to autoload a model
1156 for (@REGISTRY, @models) { 1337 for (@REGISTRY, @models) {
1157 my ($package, $model) = @$_; 1338 my ($package, $model, $autoload) = @$_;
1339 if (
1340 $autoload
1341 and eval "require $package"
1158 if (${"$package\::VERSION"} > 0) { 1342 and ${"$package\::VERSION"} > 0
1159 if (eval "require $model") { 1343 and eval "require $model"
1344 ) {
1160 $MODEL = $model; 1345 $MODEL = $model;
1161 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2; 1346 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1162 last; 1347 last;
1163 }
1164 } 1348 }
1165 } 1349 }
1166 1350
1167 unless ($MODEL) {
1168 # try to load a model
1169
1170 for (@REGISTRY, @models) {
1171 my ($package, $model) = @$_;
1172 if (eval "require $package"
1173 and ${"$package\::VERSION"} > 0
1174 and eval "require $model") {
1175 $MODEL = $model;
1176 warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
1177 last;
1178 }
1179 }
1180
1181 $MODEL 1351 $MODEL
1182 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; 1352 or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1183 }
1184 } 1353 }
1185
1186 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1187
1188 unshift @ISA, $MODEL;
1189
1190 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1191
1192 (shift @post_detect)->() while @post_detect;
1193 } 1354 }
1194 1355
1356 # free memory only needed for probing
1357 undef @models;
1358 undef @REGISTRY;
1359
1360 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1361 unshift @ISA, $MODEL;
1362
1363 # now nuke some methods that are overridden by the backend.
1364 # SUPER usage is not allowed in these.
1365 for (qw(time signal child idle)) {
1366 undef &{"AnyEvent::Base::$_"}
1367 if defined &{"$MODEL\::$_"};
1368 }
1369
1370 if ($ENV{PERL_ANYEVENT_STRICT}) {
1371 require AnyEvent::Strict;
1372 }
1373
1374 if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
1375 require AnyEvent::Debug;
1376 AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
1377 }
1378
1379 if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
1380 require AnyEvent::Debug;
1381 #d#
1382 }
1383
1384 (shift @post_detect)->() while @post_detect;
1385 undef @post_detect;
1386
1387 *post_detect = sub(&) {
1388 shift->();
1389
1390 undef
1391 };
1392
1195 $MODEL 1393 $MODEL
1196} 1394}
1197 1395
1198sub AUTOLOAD { 1396for my $name (@methods) {
1199 (my $func = $AUTOLOAD) =~ s/.*://; 1397 *$name = sub {
1200 1398 detect;
1201 $method{$func} 1399 # we use goto because
1202 or Carp::croak "$func: not a valid method for AnyEvent objects"; 1400 # a) it makes the thunk more transparent
1203 1401 # b) it allows us to delete the thunk later
1204 detect unless $MODEL; 1402 goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1205 1403 };
1206 my $class = shift;
1207 $class->$func (@_);
1208} 1404}
1209 1405
1210# utility function to dup a filehandle. this is used by many backends 1406# utility function to dup a filehandle. this is used by many backends
1211# to support binding more than one watcher per filehandle (they usually 1407# to support binding more than one watcher per filehandle (they usually
1212# allow only one watcher per fd, so we dup it to get a different one). 1408# allow only one watcher per fd, so we dup it to get a different one).
1222 # we assume CLOEXEC is already set by perl in all important cases 1418 # we assume CLOEXEC is already set by perl in all important cases
1223 1419
1224 ($fh2, $rw) 1420 ($fh2, $rw)
1225} 1421}
1226 1422
1423=head1 SIMPLIFIED AE API
1424
1425Starting with version 5.0, AnyEvent officially supports a second, much
1426simpler, API that is designed to reduce the calling, typing and memory
1427overhead by using function call syntax and a fixed number of parameters.
1428
1429See the L<AE> manpage for details.
1430
1431=cut
1432
1433package AE;
1434
1435our $VERSION = $AnyEvent::VERSION;
1436
1437sub _reset() {
1438 eval q{
1439 # fall back to the main API by default - backends and AnyEvent::Base
1440 # implementations can overwrite these.
1441
1442 sub io($$$) {
1443 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
1444 }
1445
1446 sub timer($$$) {
1447 AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
1448 }
1449
1450 sub signal($$) {
1451 AnyEvent->signal (signal => $_[0], cb => $_[1])
1452 }
1453
1454 sub child($$) {
1455 AnyEvent->child (pid => $_[0], cb => $_[1])
1456 }
1457
1458 sub idle($) {
1459 AnyEvent->idle (cb => $_[0]);
1460 }
1461
1462 sub cv(;&) {
1463 AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
1464 }
1465
1466 sub now() {
1467 AnyEvent->now
1468 }
1469
1470 sub now_update() {
1471 AnyEvent->now_update
1472 }
1473
1474 sub time() {
1475 AnyEvent->time
1476 }
1477
1478 *postpone = \&AnyEvent::postpone;
1479 };
1480 die if $@;
1481}
1482
1483BEGIN { _reset }
1484
1227package AnyEvent::Base; 1485package AnyEvent::Base;
1228 1486
1229# default implementations for many methods 1487# default implementations for many methods
1230 1488
1231sub _time { 1489sub time {
1490 eval q{ # poor man's autoloading {}
1232 # probe for availability of Time::HiRes 1491 # probe for availability of Time::HiRes
1233 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1492 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1234 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8; 1493 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1235 *_time = \&Time::HiRes::time; 1494 *AE::time = \&Time::HiRes::time;
1236 # if (eval "use POSIX (); (POSIX::times())... 1495 # if (eval "use POSIX (); (POSIX::times())...
1237 } else { 1496 } else {
1238 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE; 1497 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1239 *_time = sub { time }; # epic fail 1498 *AE::time = sub (){ time }; # epic fail
1499 }
1500
1501 *time = sub { AE::time }; # different prototypes
1240 } 1502 };
1503 die if $@;
1241 1504
1242 &_time 1505 &time
1243} 1506}
1244 1507
1245sub time { _time } 1508*now = \&time;
1246sub now { _time } 1509
1247sub now_update { } 1510sub now_update { }
1248 1511
1512sub _poll {
1513 Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
1514}
1515
1249# default implementation for ->condvar 1516# default implementation for ->condvar
1517# in fact, the default should not be overwritten
1250 1518
1251sub condvar { 1519sub condvar {
1520 eval q{ # poor man's autoloading {}
1521 *condvar = sub {
1252 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1522 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1523 };
1524
1525 *AE::cv = sub (;&) {
1526 bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
1527 };
1528 };
1529 die if $@;
1530
1531 &condvar
1253} 1532}
1254 1533
1255# default implementation for ->signal 1534# default implementation for ->signal
1256 1535
1257our $HAVE_ASYNC_INTERRUPT; 1536our $HAVE_ASYNC_INTERRUPT;
1537
1538sub _have_async_interrupt() {
1539 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
1540 && eval "use Async::Interrupt 1.02 (); 1")
1541 unless defined $HAVE_ASYNC_INTERRUPT;
1542
1543 $HAVE_ASYNC_INTERRUPT
1544}
1545
1258our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1546our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1259our (%SIG_ASY, %SIG_ASY_W); 1547our (%SIG_ASY, %SIG_ASY_W);
1260our ($SIG_COUNT, $SIG_TW); 1548our ($SIG_COUNT, $SIG_TW);
1261 1549
1262sub _signal_exec { 1550# install a dummy wakeup watcher to reduce signal catching latency
1263 $HAVE_ASYNC_INTERRUPT 1551# used by Impls
1264 ? $SIGPIPE_R->drain 1552sub _sig_add() {
1265 : sysread $SIGPIPE_R, my $dummy, 9; 1553 unless ($SIG_COUNT++) {
1554 # try to align timer on a full-second boundary, if possible
1555 my $NOW = AE::now;
1266 1556
1267 while (%SIG_EV) { 1557 $SIG_TW = AE::timer
1268 for (keys %SIG_EV) { 1558 $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1269 delete $SIG_EV{$_}; 1559 $MAX_SIGNAL_LATENCY,
1270 $_->() for values %{ $SIG_CB{$_} || {} }; 1560 sub { } # just for the PERL_ASYNC_CHECK
1271 } 1561 ;
1272 } 1562 }
1273} 1563}
1274 1564
1275sub _signal { 1565sub _sig_del {
1276 my (undef, %arg) = @_;
1277
1278 my $signal = uc $arg{signal}
1279 or Carp::croak "required option 'signal' is missing";
1280
1281 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1282
1283 if ($HAVE_ASYNC_INTERRUPT) {
1284 # async::interrupt
1285
1286 $SIG_ASY{$signal} ||= do {
1287 my $asy = new Async::Interrupt
1288 cb => sub { undef $SIG_EV{$signal} },
1289 signal => $signal,
1290 pipe => [$SIGPIPE_R->filenos],
1291 ;
1292 $asy->pipe_autodrain (0);
1293
1294 $asy
1295 };
1296
1297 } else {
1298 # pure perl
1299
1300 $SIG{$signal} ||= sub {
1301 local $!;
1302 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1303 undef $SIG_EV{$signal};
1304 };
1305
1306 # can't do signal processing without introducing races in pure perl,
1307 # so limit the signal latency.
1308 ++$SIG_COUNT;
1309 $SIG_TW ||= AnyEvent->timer (
1310 after => $MAX_SIGNAL_LATENCY,
1311 interval => $MAX_SIGNAL_LATENCY,
1312 cb => sub { }, # just for the PERL_ASYNC_CHECK
1313 );
1314 }
1315
1316 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1317}
1318
1319sub signal {
1320 # probe for availability of Async::Interrupt
1321 if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
1322 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1323
1324 $HAVE_ASYNC_INTERRUPT = 1;
1325 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1326 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
1327
1328 } else {
1329 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1330
1331 require Fcntl;
1332
1333 if (AnyEvent::WIN32) {
1334 require AnyEvent::Util;
1335
1336 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1337 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1338 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1339 } else {
1340 pipe $SIGPIPE_R, $SIGPIPE_W;
1341 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1342 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1343
1344 # not strictly required, as $^F is normally 2, but let's make sure...
1345 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1346 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1347 }
1348
1349 $SIGPIPE_R
1350 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1351
1352 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1353 }
1354
1355 *signal = \&_signal;
1356 &signal
1357}
1358
1359sub AnyEvent::Base::signal::DESTROY {
1360 my ($signal, $cb) = @{$_[0]};
1361
1362 undef $SIG_TW 1566 undef $SIG_TW
1363 unless --$SIG_COUNT; 1567 unless --$SIG_COUNT;
1568}
1364 1569
1570our $_sig_name_init; $_sig_name_init = sub {
1571 eval q{ # poor man's autoloading {}
1572 undef $_sig_name_init;
1573
1574 if (_have_async_interrupt) {
1575 *sig2num = \&Async::Interrupt::sig2num;
1576 *sig2name = \&Async::Interrupt::sig2name;
1577 } else {
1578 require Config;
1579
1580 my %signame2num;
1581 @signame2num{ split ' ', $Config::Config{sig_name} }
1582 = split ' ', $Config::Config{sig_num};
1583
1584 my @signum2name;
1585 @signum2name[values %signame2num] = keys %signame2num;
1586
1587 *sig2num = sub($) {
1588 $_[0] > 0 ? shift : $signame2num{+shift}
1589 };
1590 *sig2name = sub ($) {
1591 $_[0] > 0 ? $signum2name[+shift] : shift
1592 };
1593 }
1594 };
1595 die if $@;
1596};
1597
1598sub sig2num ($) { &$_sig_name_init; &sig2num }
1599sub sig2name($) { &$_sig_name_init; &sig2name }
1600
1601sub signal {
1602 eval q{ # poor man's autoloading {}
1603 # probe for availability of Async::Interrupt
1604 if (_have_async_interrupt) {
1605 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1606
1607 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1608 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1609
1610 } else {
1611 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1612
1613 if (AnyEvent::WIN32) {
1614 require AnyEvent::Util;
1615
1616 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1617 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
1618 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
1619 } else {
1620 pipe $SIGPIPE_R, $SIGPIPE_W;
1621 fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1622 fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1623
1624 # not strictly required, as $^F is normally 2, but let's make sure...
1625 fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1626 fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1627 }
1628
1629 $SIGPIPE_R
1630 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1631
1632 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1633 }
1634
1635 *signal = $HAVE_ASYNC_INTERRUPT
1636 ? sub {
1637 my (undef, %arg) = @_;
1638
1639 # async::interrupt
1640 my $signal = sig2num $arg{signal};
1641 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1642
1643 $SIG_ASY{$signal} ||= new Async::Interrupt
1644 cb => sub { undef $SIG_EV{$signal} },
1645 signal => $signal,
1646 pipe => [$SIGPIPE_R->filenos],
1647 pipe_autodrain => 0,
1648 ;
1649
1650 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1651 }
1652 : sub {
1653 my (undef, %arg) = @_;
1654
1655 # pure perl
1656 my $signal = sig2name $arg{signal};
1657 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1658
1659 $SIG{$signal} ||= sub {
1660 local $!;
1661 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1662 undef $SIG_EV{$signal};
1663 };
1664
1665 # can't do signal processing without introducing races in pure perl,
1666 # so limit the signal latency.
1667 _sig_add;
1668
1669 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1670 }
1671 ;
1672
1673 *AnyEvent::Base::signal::DESTROY = sub {
1674 my ($signal, $cb) = @{$_[0]};
1675
1676 _sig_del;
1677
1365 delete $SIG_CB{$signal}{$cb}; 1678 delete $SIG_CB{$signal}{$cb};
1366 1679
1367 $HAVE_ASYNC_INTERRUPT 1680 $HAVE_ASYNC_INTERRUPT
1368 ? delete $SIG_ASY{$signal} 1681 ? delete $SIG_ASY{$signal}
1369 : # delete doesn't work with older perls - they then 1682 : # delete doesn't work with older perls - they then
1370 # print weird messages, or just unconditionally exit 1683 # print weird messages, or just unconditionally exit
1371 # instead of getting the default action. 1684 # instead of getting the default action.
1372 undef $SIG{$signal} 1685 undef $SIG{$signal}
1373 unless keys %{ $SIG_CB{$signal} }; 1686 unless keys %{ $SIG_CB{$signal} };
1687 };
1688
1689 *_signal_exec = sub {
1690 $HAVE_ASYNC_INTERRUPT
1691 ? $SIGPIPE_R->drain
1692 : sysread $SIGPIPE_R, (my $dummy), 9;
1693
1694 while (%SIG_EV) {
1695 for (keys %SIG_EV) {
1696 delete $SIG_EV{$_};
1697 &$_ for values %{ $SIG_CB{$_} || {} };
1698 }
1699 }
1700 };
1701 };
1702 die if $@;
1703
1704 &signal
1374} 1705}
1375 1706
1376# default implementation for ->child 1707# default implementation for ->child
1377 1708
1378our %PID_CB; 1709our %PID_CB;
1379our $CHLD_W; 1710our $CHLD_W;
1380our $CHLD_DELAY_W; 1711our $CHLD_DELAY_W;
1381our $WNOHANG;
1382 1712
1383sub _sigchld { 1713# used by many Impl's
1384 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1714sub _emit_childstatus($$) {
1385 $_->($pid, $?) 1715 my (undef, $rpid, $rstatus) = @_;
1716
1717 $_->($rpid, $rstatus)
1386 for values %{ $PID_CB{$pid} || {} }, 1718 for values %{ $PID_CB{$rpid} || {} },
1387 values %{ $PID_CB{0} || {} }; 1719 values %{ $PID_CB{0} || {} };
1388 }
1389} 1720}
1390 1721
1391sub child { 1722sub child {
1723 eval q{ # poor man's autoloading {}
1724 *_sigchld = sub {
1725 my $pid;
1726
1727 AnyEvent->_emit_childstatus ($pid, $?)
1728 while ($pid = waitpid -1, WNOHANG) > 0;
1729 };
1730
1731 *child = sub {
1392 my (undef, %arg) = @_; 1732 my (undef, %arg) = @_;
1393 1733
1394 defined (my $pid = $arg{pid} + 0) 1734 my $pid = $arg{pid};
1395 or Carp::croak "required option 'pid' is missing"; 1735 my $cb = $arg{cb};
1396 1736
1397 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1737 $PID_CB{$pid}{$cb+0} = $cb;
1398 1738
1399 # WNOHANG is almost cetrainly 1 everywhere
1400 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1401 ? 1
1402 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1403
1404 unless ($CHLD_W) { 1739 unless ($CHLD_W) {
1405 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1740 $CHLD_W = AE::signal CHLD => \&_sigchld;
1406 # child could be a zombie already, so make at least one round 1741 # child could be a zombie already, so make at least one round
1407 &_sigchld; 1742 &_sigchld;
1408 } 1743 }
1409 1744
1410 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1745 bless [$pid, $cb+0], "AnyEvent::Base::child"
1411} 1746 };
1412 1747
1413sub AnyEvent::Base::child::DESTROY { 1748 *AnyEvent::Base::child::DESTROY = sub {
1414 my ($pid, $cb) = @{$_[0]}; 1749 my ($pid, $icb) = @{$_[0]};
1415 1750
1416 delete $PID_CB{$pid}{$cb}; 1751 delete $PID_CB{$pid}{$icb};
1417 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1752 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1418 1753
1419 undef $CHLD_W unless keys %PID_CB; 1754 undef $CHLD_W unless keys %PID_CB;
1755 };
1756 };
1757 die if $@;
1758
1759 &child
1420} 1760}
1421 1761
1422# idle emulation is done by simply using a timer, regardless 1762# idle emulation is done by simply using a timer, regardless
1423# of whether the process is idle or not, and not letting 1763# of whether the process is idle or not, and not letting
1424# the callback use more than 50% of the time. 1764# the callback use more than 50% of the time.
1425sub idle { 1765sub idle {
1766 eval q{ # poor man's autoloading {}
1767 *idle = sub {
1426 my (undef, %arg) = @_; 1768 my (undef, %arg) = @_;
1427 1769
1428 my ($cb, $w, $rcb) = $arg{cb}; 1770 my ($cb, $w, $rcb) = $arg{cb};
1429 1771
1430 $rcb = sub { 1772 $rcb = sub {
1431 if ($cb) { 1773 if ($cb) {
1432 $w = _time; 1774 $w = AE::time;
1433 &$cb; 1775 &$cb;
1434 $w = _time - $w; 1776 $w = AE::time - $w;
1435 1777
1436 # never use more then 50% of the time for the idle watcher, 1778 # never use more then 50% of the time for the idle watcher,
1437 # within some limits 1779 # within some limits
1438 $w = 0.0001 if $w < 0.0001; 1780 $w = 0.0001 if $w < 0.0001;
1439 $w = 5 if $w > 5; 1781 $w = 5 if $w > 5;
1440 1782
1441 $w = AnyEvent->timer (after => $w, cb => $rcb); 1783 $w = AE::timer $w, 0, $rcb;
1442 } else { 1784 } else {
1443 # clean up... 1785 # clean up...
1444 undef $w; 1786 undef $w;
1445 undef $rcb; 1787 undef $rcb;
1788 }
1789 };
1790
1791 $w = AE::timer 0.05, 0, $rcb;
1792
1793 bless \\$cb, "AnyEvent::Base::idle"
1446 } 1794 };
1795
1796 *AnyEvent::Base::idle::DESTROY = sub {
1797 undef $${$_[0]};
1798 };
1447 }; 1799 };
1800 die if $@;
1448 1801
1449 $w = AnyEvent->timer (after => 0.05, cb => $rcb); 1802 &idle
1450
1451 bless \\$cb, "AnyEvent::Base::idle"
1452}
1453
1454sub AnyEvent::Base::idle::DESTROY {
1455 undef $${$_[0]};
1456} 1803}
1457 1804
1458package AnyEvent::CondVar; 1805package AnyEvent::CondVar;
1459 1806
1460our @ISA = AnyEvent::CondVar::Base::; 1807our @ISA = AnyEvent::CondVar::Base::;
1808
1809# only to be used for subclassing
1810sub new {
1811 my $class = shift;
1812 bless AnyEvent->condvar (@_), $class
1813}
1461 1814
1462package AnyEvent::CondVar::Base; 1815package AnyEvent::CondVar::Base;
1463 1816
1464#use overload 1817#use overload
1465# '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1818# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1475 1828
1476sub _send { 1829sub _send {
1477 # nop 1830 # nop
1478} 1831}
1479 1832
1833sub _wait {
1834 AnyEvent->_poll until $_[0]{_ae_sent};
1835}
1836
1480sub send { 1837sub send {
1481 my $cv = shift; 1838 my $cv = shift;
1482 $cv->{_ae_sent} = [@_]; 1839 $cv->{_ae_sent} = [@_];
1483 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; 1840 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
1484 $cv->_send; 1841 $cv->_send;
1491 1848
1492sub ready { 1849sub ready {
1493 $_[0]{_ae_sent} 1850 $_[0]{_ae_sent}
1494} 1851}
1495 1852
1496sub _wait {
1497 $WAITING
1498 and !$_[0]{_ae_sent}
1499 and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
1500
1501 local $WAITING = 1;
1502 AnyEvent->one_event while !$_[0]{_ae_sent};
1503}
1504
1505sub recv { 1853sub recv {
1854 unless ($_[0]{_ae_sent}) {
1855 $WAITING
1856 and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
1857
1858 local $WAITING = 1;
1506 $_[0]->_wait; 1859 $_[0]->_wait;
1860 }
1507 1861
1508 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; 1862 $_[0]{_ae_croak}
1509 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] 1863 and Carp::croak $_[0]{_ae_croak};
1864
1865 wantarray
1866 ? @{ $_[0]{_ae_sent} }
1867 : $_[0]{_ae_sent}[0]
1510} 1868}
1511 1869
1512sub cb { 1870sub cb {
1513 $_[0]{_ae_cb} = $_[1] if @_ > 1; 1871 my $cv = shift;
1872
1873 @_
1874 and $cv->{_ae_cb} = shift
1875 and $cv->{_ae_sent}
1876 and (delete $cv->{_ae_cb})->($cv);
1877
1514 $_[0]{_ae_cb} 1878 $cv->{_ae_cb}
1515} 1879}
1516 1880
1517sub begin { 1881sub begin {
1518 ++$_[0]{_ae_counter}; 1882 ++$_[0]{_ae_counter};
1519 $_[0]{_ae_end_cb} = $_[1] if @_ > 1; 1883 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1524 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; 1888 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1525} 1889}
1526 1890
1527# undocumented/compatibility with pre-3.4 1891# undocumented/compatibility with pre-3.4
1528*broadcast = \&send; 1892*broadcast = \&send;
1529*wait = \&_wait; 1893*wait = \&recv;
1530 1894
1531=head1 ERROR AND EXCEPTION HANDLING 1895=head1 ERROR AND EXCEPTION HANDLING
1532 1896
1533In general, AnyEvent does not do any error handling - it relies on the 1897In general, AnyEvent does not do any error handling - it relies on the
1534caller to do that if required. The L<AnyEvent::Strict> module (see also 1898caller to do that if required. The L<AnyEvent::Strict> module (see also
1581check the arguments passed to most method calls. If it finds any problems, 1945check the arguments passed to most method calls. If it finds any problems,
1582it will croak. 1946it will croak.
1583 1947
1584In other words, enables "strict" mode. 1948In other words, enables "strict" mode.
1585 1949
1586Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense> 1950Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1587>>, it is definitely recommended to keep it off in production. Keeping 1951>>, it is definitely recommended to keep it off in production. Keeping
1588C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs 1952C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1589can be very useful, however. 1953can be very useful, however.
1590 1954
1591=item C<PERL_ANYEVENT_MODEL> 1955=item C<PERL_ANYEVENT_MODEL>
1592 1956
1593This can be used to specify the event model to be used by AnyEvent, before 1957This can be used to specify the event model to be used by AnyEvent, before
1594auto detection and -probing kicks in. It must be a string consisting 1958auto detection and -probing kicks in.
1595entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1959
1960It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
1961or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1596and the resulting module name is loaded and if the load was successful, 1962resulting module name is loaded and - if the load was successful - used as
1597used as event model. If it fails to load AnyEvent will proceed with 1963event model backend. If it fails to load then AnyEvent will proceed with
1598auto detection and -probing. 1964auto detection and -probing.
1599 1965
1600This functionality might change in future versions. 1966If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
1967nothing gets prepended and the module name is used as-is (hint: C<::> at
1968the end of a string designates a module name and quotes it appropriately).
1601 1969
1602For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1970For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1603could start your program like this: 1971could start your program like this:
1604 1972
1605 PERL_ANYEVENT_MODEL=Perl perl ... 1973 PERL_ANYEVENT_MODEL=Perl perl ...
1606 1974
1607=item C<PERL_ANYEVENT_PROTOCOLS> 1975=item C<PERL_ANYEVENT_PROTOCOLS>
1728 warn "read: $input\n"; # output what has been read 2096 warn "read: $input\n"; # output what has been read
1729 $cv->send if $input =~ /^q/i; # quit program if /^q/i 2097 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1730 }, 2098 },
1731 ); 2099 );
1732 2100
1733 my $time_watcher; # can only be used once
1734
1735 sub new_timer {
1736 $timer = AnyEvent->timer (after => 1, cb => sub { 2101 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1737 warn "timeout\n"; # print 'timeout' about every second 2102 warn "timeout\n"; # print 'timeout' at most every second
1738 &new_timer; # and restart the time
1739 }); 2103 });
1740 }
1741
1742 new_timer; # create first timer
1743 2104
1744 $cv->recv; # wait until user enters /^q/i 2105 $cv->recv; # wait until user enters /^q/i
1745 2106
1746=head1 REAL-WORLD EXAMPLE 2107=head1 REAL-WORLD EXAMPLE
1747 2108
1820 2181
1821The actual code goes further and collects all errors (C<die>s, exceptions) 2182The actual code goes further and collects all errors (C<die>s, exceptions)
1822that occurred during request processing. The C<result> method detects 2183that occurred during request processing. The C<result> method detects
1823whether an exception as thrown (it is stored inside the $txn object) 2184whether an exception as thrown (it is stored inside the $txn object)
1824and just throws the exception, which means connection errors and other 2185and just throws the exception, which means connection errors and other
1825problems get reported tot he code that tries to use the result, not in a 2186problems get reported to the code that tries to use the result, not in a
1826random callback. 2187random callback.
1827 2188
1828All of this enables the following usage styles: 2189All of this enables the following usage styles:
1829 2190
18301. Blocking: 21911. Blocking:
1878through AnyEvent. The benchmark creates a lot of timers (with a zero 2239through AnyEvent. The benchmark creates a lot of timers (with a zero
1879timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 2240timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1880which it is), lets them fire exactly once and destroys them again. 2241which it is), lets them fire exactly once and destroys them again.
1881 2242
1882Source code for this benchmark is found as F<eg/bench> in the AnyEvent 2243Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1883distribution. 2244distribution. It uses the L<AE> interface, which makes a real difference
2245for the EV and Perl backends only.
1884 2246
1885=head3 Explanation of the columns 2247=head3 Explanation of the columns
1886 2248
1887I<watcher> is the number of event watchers created/destroyed. Since 2249I<watcher> is the number of event watchers created/destroyed. Since
1888different event models feature vastly different performances, each event 2250different event models feature vastly different performances, each event
1909watcher. 2271watcher.
1910 2272
1911=head3 Results 2273=head3 Results
1912 2274
1913 name watchers bytes create invoke destroy comment 2275 name watchers bytes create invoke destroy comment
1914 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 2276 EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1915 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 2277 EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1916 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 2278 Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1917 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 2279 Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1918 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 2280 Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1919 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 2281 Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1920 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll 2282 IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1921 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll 2283 IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1922 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 2284 Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1923 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 2285 Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1924 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 2286 POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1925 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 2287 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1926 2288
1927=head3 Discussion 2289=head3 Discussion
1928 2290
1929The benchmark does I<not> measure scalability of the event loop very 2291The benchmark does I<not> measure scalability of the event loop very
1930well. For example, a select-based event loop (such as the pure perl one) 2292well. For example, a select-based event loop (such as the pure perl one)
1942benchmark machine, handling an event takes roughly 1600 CPU cycles with 2304benchmark machine, handling an event takes roughly 1600 CPU cycles with
1943EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU 2305EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1944cycles with POE. 2306cycles with POE.
1945 2307
1946C<EV> is the sole leader regarding speed and memory use, which are both 2308C<EV> is the sole leader regarding speed and memory use, which are both
1947maximal/minimal, respectively. Even when going through AnyEvent, it uses 2309maximal/minimal, respectively. When using the L<AE> API there is zero
2310overhead (when going through the AnyEvent API create is about 5-6 times
2311slower, with other times being equal, so still uses far less memory than
1948far less memory than any other event loop and is still faster than Event 2312any other event loop and is still faster than Event natively).
1949natively.
1950 2313
1951The pure perl implementation is hit in a few sweet spots (both the 2314The pure perl implementation is hit in a few sweet spots (both the
1952constant timeout and the use of a single fd hit optimisations in the perl 2315constant timeout and the use of a single fd hit optimisations in the perl
1953interpreter and the backend itself). Nevertheless this shows that it 2316interpreter and the backend itself). Nevertheless this shows that it
1954adds very little overhead in itself. Like any select-based backend its 2317adds very little overhead in itself. Like any select-based backend its
2028In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 2391In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
2029(1%) are active. This mirrors the activity of large servers with many 2392(1%) are active. This mirrors the activity of large servers with many
2030connections, most of which are idle at any one point in time. 2393connections, most of which are idle at any one point in time.
2031 2394
2032Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 2395Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
2033distribution. 2396distribution. It uses the L<AE> interface, which makes a real difference
2397for the EV and Perl backends only.
2034 2398
2035=head3 Explanation of the columns 2399=head3 Explanation of the columns
2036 2400
2037I<sockets> is the number of sockets, and twice the number of "servers" (as 2401I<sockets> is the number of sockets, and twice the number of "servers" (as
2038each server has a read and write socket end). 2402each server has a read and write socket end).
2046a new one that moves the timeout into the future. 2410a new one that moves the timeout into the future.
2047 2411
2048=head3 Results 2412=head3 Results
2049 2413
2050 name sockets create request 2414 name sockets create request
2051 EV 20000 69.01 11.16 2415 EV 20000 62.66 7.99
2052 Perl 20000 73.32 35.87 2416 Perl 20000 68.32 32.64
2053 IOAsync 20000 157.00 98.14 epoll 2417 IOAsync 20000 174.06 101.15 epoll
2054 IOAsync 20000 159.31 616.06 poll 2418 IOAsync 20000 174.67 610.84 poll
2055 Event 20000 212.62 257.32 2419 Event 20000 202.69 242.91
2056 Glib 20000 651.16 1896.30 2420 Glib 20000 557.01 1689.52
2057 POE 20000 349.67 12317.24 uses POE::Loop::Event 2421 POE 20000 341.54 12086.32 uses POE::Loop::Event
2058 2422
2059=head3 Discussion 2423=head3 Discussion
2060 2424
2061This benchmark I<does> measure scalability and overall performance of the 2425This benchmark I<does> measure scalability and overall performance of the
2062particular event loop. 2426particular event loop.
2188As you can see, the AnyEvent + EV combination even beats the 2552As you can see, the AnyEvent + EV combination even beats the
2189hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 2553hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2190backend easily beats IO::Lambda and POE. 2554backend easily beats IO::Lambda and POE.
2191 2555
2192And even the 100% non-blocking version written using the high-level (and 2556And even the 100% non-blocking version written using the high-level (and
2193slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a 2557slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2194large margin, even though it does all of DNS, tcp-connect and socket I/O 2558higher level ("unoptimised") abstractions by a large margin, even though
2195in a non-blocking way. 2559it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2196 2560
2197The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and 2561The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2198F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are 2562F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2199part of the IO::lambda distribution and were used without any changes. 2563part of the IO::Lambda distribution and were used without any changes.
2200 2564
2201 2565
2202=head1 SIGNALS 2566=head1 SIGNALS
2203 2567
2204AnyEvent currently installs handlers for these signals: 2568AnyEvent currently installs handlers for these signals:
2241 unless defined $SIG{PIPE}; 2605 unless defined $SIG{PIPE};
2242 2606
2243=head1 RECOMMENDED/OPTIONAL MODULES 2607=head1 RECOMMENDED/OPTIONAL MODULES
2244 2608
2245One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and 2609One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2246it's built-in modules) are required to use it. 2610its built-in modules) are required to use it.
2247 2611
2248That does not mean that AnyEvent won't take advantage of some additional 2612That does not mean that AnyEvent won't take advantage of some additional
2249modules if they are installed. 2613modules if they are installed.
2250 2614
2251This section epxlains which additional modules will be used, and how they 2615This section explains which additional modules will be used, and how they
2252affect AnyEvent's operetion. 2616affect AnyEvent's operation.
2253 2617
2254=over 4 2618=over 4
2255 2619
2256=item L<Async::Interrupt> 2620=item L<Async::Interrupt>
2257 2621
2258This slightly arcane module is used to implement fast signal handling: To 2622This slightly arcane module is used to implement fast signal handling: To
2259my knowledge, there is no way to do completely race-free and quick 2623my knowledge, there is no way to do completely race-free and quick
2260signal handling in pure perl. To ensure that signals still get 2624signal handling in pure perl. To ensure that signals still get
2261delivered, AnyEvent will start an interval timer to wake up perl (and 2625delivered, AnyEvent will start an interval timer to wake up perl (and
2262catch the signals) with soemd elay (default is 10 seconds, look for 2626catch the signals) with some delay (default is 10 seconds, look for
2263C<$AnyEvent::MAX_SIGNAL_LATENCY>). 2627C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2264 2628
2265If this module is available, then it will be used to implement signal 2629If this module is available, then it will be used to implement signal
2266catching, which means that signals will not be delayed, and the event loop 2630catching, which means that signals will not be delayed, and the event loop
2267will not be interrupted regularly, which is more efficient (And good for 2631will not be interrupted regularly, which is more efficient (and good for
2268battery life on laptops). 2632battery life on laptops).
2269 2633
2270This affects not just the pure-perl event loop, but also other event loops 2634This affects not just the pure-perl event loop, but also other event loops
2271that have no signal handling on their own (e.g. Glib, Tk, Qt). 2635that have no signal handling on their own (e.g. Glib, Tk, Qt).
2636
2637Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
2638and either employ their own workarounds (POE) or use AnyEvent's workaround
2639(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
2640does nothing for those backends.
2272 2641
2273=item L<EV> 2642=item L<EV>
2274 2643
2275This module isn't really "optional", as it is simply one of the backend 2644This module isn't really "optional", as it is simply one of the backend
2276event loops that AnyEvent can use. However, it is simply the best event 2645event loops that AnyEvent can use. However, it is simply the best event
2279automatic timer adjustments even when no monotonic clock is available, 2648automatic timer adjustments even when no monotonic clock is available,
2280can take avdantage of advanced kernel interfaces such as C<epoll> and 2649can take avdantage of advanced kernel interfaces such as C<epoll> and
2281C<kqueue>, and is the fastest backend I<by far>. You can even embed 2650C<kqueue>, and is the fastest backend I<by far>. You can even embed
2282L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>). 2651L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2283 2652
2653If you only use backends that rely on another event loop (e.g. C<Tk>),
2654then this module will do nothing for you.
2655
2284=item L<Guard> 2656=item L<Guard>
2285 2657
2286The guard module, when used, will be used to implement 2658The guard module, when used, will be used to implement
2287C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a 2659C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2288lot less memory), but otherwise doesn't affect guard operation much. It is 2660lot less memory), but otherwise doesn't affect guard operation much. It is
2289purely used for performance. 2661purely used for performance.
2290 2662
2291=item L<JSON> and L<JSON::XS> 2663=item L<JSON> and L<JSON::XS>
2292 2664
2293This module is required when you want to read or write JSON data via 2665One of these modules is required when you want to read or write JSON data
2294L<AnyEvent::Handle>. It is also written in pure-perl, but can take 2666via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
2295advantage of the ulta-high-speed L<JSON::XS> module when it is installed. 2667advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2296
2297In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2298installed.
2299 2668
2300=item L<Net::SSLeay> 2669=item L<Net::SSLeay>
2301 2670
2302Implementing TLS/SSL in Perl is certainly interesting, but not very 2671Implementing TLS/SSL in Perl is certainly interesting, but not very
2303worthwhile: If this module is installed, then L<AnyEvent::Handle> (with 2672worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2304the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL. 2673the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2305 2674
2306=item L<Time::HiRes> 2675=item L<Time::HiRes>
2307 2676
2308This module is part of perl since release 5.008. It will be used when the 2677This module is part of perl since release 5.008. It will be used when the
2309chosen event library does not come with a timing source on it's own. The 2678chosen event library does not come with a timing source of its own. The
2310pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to 2679pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
2311try to use a monotonic clock for timing stability. 2680try to use a monotonic clock for timing stability.
2312 2681
2313=back 2682=back
2314 2683
2315 2684
2316=head1 FORK 2685=head1 FORK
2317 2686
2318Most event libraries are not fork-safe. The ones who are usually are 2687Most event libraries are not fork-safe. The ones who are usually are
2319because they rely on inefficient but fork-safe C<select> or C<poll> 2688because they rely on inefficient but fork-safe C<select> or C<poll> calls
2320calls. Only L<EV> is fully fork-aware. 2689- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
2690are usually badly thought-out hacks that are incompatible with fork in
2691one way or another. Only L<EV> is fully fork-aware and ensures that you
2692continue event-processing in both parent and child (or both, if you know
2693what you are doing).
2694
2695This means that, in general, you cannot fork and do event processing in
2696the child if the event library was initialised before the fork (which
2697usually happens when the first AnyEvent watcher is created, or the library
2698is loaded).
2321 2699
2322If you have to fork, you must either do so I<before> creating your first 2700If you have to fork, you must either do so I<before> creating your first
2323watcher OR you must not use AnyEvent at all in the child OR you must do 2701watcher OR you must not use AnyEvent at all in the child OR you must do
2324something completely out of the scope of AnyEvent. 2702something completely out of the scope of AnyEvent.
2703
2704The problem of doing event processing in the parent I<and> the child
2705is much more complicated: even for backends that I<are> fork-aware or
2706fork-safe, their behaviour is not usually what you want: fork clones all
2707watchers, that means all timers, I/O watchers etc. are active in both
2708parent and child, which is almost never what you want. USing C<exec>
2709to start worker children from some kind of manage rprocess is usually
2710preferred, because it is much easier and cleaner, at the expense of having
2711to have another binary.
2325 2712
2326 2713
2327=head1 SECURITY CONSIDERATIONS 2714=head1 SECURITY CONSIDERATIONS
2328 2715
2329AnyEvent can be forced to load any event model via 2716AnyEvent can be forced to load any event model via
2359pronounced). 2746pronounced).
2360 2747
2361 2748
2362=head1 SEE ALSO 2749=head1 SEE ALSO
2363 2750
2751Tutorial/Introduction: L<AnyEvent::Intro>.
2752
2753FAQ: L<AnyEvent::FAQ>.
2754
2364Utility functions: L<AnyEvent::Util>. 2755Utility functions: L<AnyEvent::Util>.
2365 2756
2366Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 2757Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2367L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2758L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2368 2759
2369Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2760Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2370L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2761L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2371L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2762L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2372L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>. 2763L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2373 2764
2374Non-blocking file handles, sockets, TCP clients and 2765Non-blocking file handles, sockets, TCP clients and
2375servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>. 2766servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2376 2767
2377Asynchronous DNS: L<AnyEvent::DNS>. 2768Asynchronous DNS: L<AnyEvent::DNS>.
2378 2769
2379Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, 2770Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2380L<Coro::Event>,
2381 2771
2382Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>, 2772Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2383L<AnyEvent::HTTP>. 2773L<AnyEvent::HTTP>.
2384 2774
2385 2775
2386=head1 AUTHOR 2776=head1 AUTHOR
2387 2777

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