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Revision 1.354 by root, Thu Aug 11 21:26:39 2011 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - events independent of event loop implementation 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
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.
45 48
46=head1 SUPPORT 49=head1 SUPPORT
47 50
51An FAQ document is available as L<AnyEvent::FAQ>.
52
48There is a mailinglist for discussing all things AnyEvent, and an IRC 53There also is a mailinglist for discussing all things AnyEvent, and an IRC
49channel, too. 54channel, too.
50 55
51See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software 56See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
52Respository>, at L<http://anyevent.schmorp.de>, for more info. 57Repository>, at L<http://anyevent.schmorp.de>, for more info.
53 58
54=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 59=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
55 60
56Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 61Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
57nowadays. So what is different about AnyEvent? 62nowadays. So what is different about AnyEvent?
73module 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
74model you use. 79model you use.
75 80
76For 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
77actually 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
78like 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
79cannot use anything else, as they are simply incompatible to everything 84cannot use anything else, as they are simply incompatible to everything
80that 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
81module 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.
82 87
83AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 88AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
84fine. 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
85with 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
86your 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
87too. But if your module uses AnyEvent, it works transparently with all 92your module uses AnyEvent, it works transparently with all event models it
88event 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
89use 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,
90to AnyEvent, too, so it is future-proof). 95so it is future-proof).
91 96
92In 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
93model>, 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
94modules, 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
95follow. 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
96offering 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
97technically possible. 102technically possible.
98 103
99Of course, AnyEvent comes with a big (and fully optional!) toolbox 104Of course, AnyEvent comes with a big (and fully optional!) toolbox
100of useful functionality, such as an asynchronous DNS resolver, 100% 105of useful functionality, such as an asynchronous DNS resolver, 100%
106useful) 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
107model, you should I<not> use this module. 112model, you should I<not> use this module.
108 113
109=head1 DESCRIPTION 114=head1 DESCRIPTION
110 115
111L<AnyEvent> provides an identical interface to multiple event loops. This 116L<AnyEvent> provides a uniform interface to various event loops. This
112allows module authors to utilise an event loop without forcing module 117allows module authors to use event loop functionality without forcing
113users 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
114peacefully at any one time). 119than one event loop cannot coexist peacefully).
115 120
116The 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>
117module. 122module.
118 123
119During the first call of any watcher-creation method, the module tries 124During the first call of any watcher-creation method, the module tries
120to 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
121following modules is already loaded: L<EV>, 126following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
122L<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
123L<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
124to 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
125adaptor should always succeed) in the order given. The first one that can 130available, the pure-perl L<AnyEvent::Loop> should always work, so
126be successfully loaded will be used. If, after this, still none could be 131the other two are not normally tried.
127found, AnyEvent will fall back to a pure-perl event loop, which is not
128very efficient, but should work everywhere.
129 132
130Because AnyEvent first checks for modules that are already loaded, loading 133Because AnyEvent first checks for modules that are already loaded, loading
131an event model explicitly before first using AnyEvent will likely make 134an event model explicitly before first using AnyEvent will likely make
132that model the default. For example: 135that model the default. For example:
133 136
135 use AnyEvent; 138 use AnyEvent;
136 139
137 # .. AnyEvent will likely default to Tk 140 # .. AnyEvent will likely default to Tk
138 141
139The 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
140starts 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,
141use AnyEvent so their modules work together with others seamlessly... 144as very few modules hardcode event loops without announcing this very
145loudly.
142 146
143The pure-perl implementation of AnyEvent is called 147The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
144C<AnyEvent::Impl::Perl>. Like other event modules you can load it 148other event modules you can load it explicitly and enjoy the high
145explicitly and enjoy the high availability of that event loop :) 149availability of that event loop :)
146 150
147=head1 WATCHERS 151=head1 WATCHERS
148 152
149AnyEvent 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
150stores 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
155callback when the event occurs (of course, only when the event model 159callback when the event occurs (of course, only when the event model
156is in control). 160is in control).
157 161
158Note that B<callbacks must not permanently change global variables> 162Note that B<callbacks must not permanently change global variables>
159potentially 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<<
160callbacks must not C<die> >>. The former is good programming practise in 164callbacks must not C<die> >>. The former is good programming practice in
161Perl and the latter stems from the fact that exception handling differs 165Perl and the latter stems from the fact that exception handling differs
162widely between event loops. 166widely between event loops.
163 167
164To 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
165variable 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
166to it). 170to it).
167 171
168All 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.
169 173
170Many watchers either are used with "recursion" (repeating timers for 174Many watchers either are used with "recursion" (repeating timers for
171example), or need to refer to their watcher object in other ways. 175example), or need to refer to their watcher object in other ways.
172 176
173An any way to achieve that is this pattern: 177One way to achieve that is this pattern:
174 178
175 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 179 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
176 # you can use $w here, for example to undef it 180 # you can use $w here, for example to undef it
177 undef $w; 181 undef $w;
178 }); 182 });
180Note 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,
181my variables are only visible after the statement in which they are 185my variables are only visible after the statement in which they are
182declared. 186declared.
183 187
184=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 );
185 195
186You 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
187with the following mandatory key-value pairs as arguments: 197with the following mandatory key-value pairs as arguments:
188 198
189C<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
204 214
205The 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.
206You 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
207underlying file descriptor. 217underlying file descriptor.
208 218
209Some event loops issue spurious readyness notifications, so you should 219Some event loops issue spurious readiness notifications, so you should
210always use non-blocking calls when reading/writing from/to your file 220always use non-blocking calls when reading/writing from/to your file
211handles. 221handles.
212 222
213Example: 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
214watcher. 224watcher.
219 undef $w; 229 undef $w;
220 }); 230 });
221 231
222=head2 TIME WATCHERS 232=head2 TIME WATCHERS
223 233
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
224You can create a time watcher by calling the C<< AnyEvent->timer >> 242You can create a time watcher by calling the C<< AnyEvent->timer >>
225method with the following mandatory arguments: 243method with the following mandatory arguments:
226 244
227C<after> specifies after how many seconds (fractional values are 245C<after> specifies after how many seconds (fractional values are
228supported) 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
230 248
231Although the callback might get passed parameters, their value and 249Although the callback might get passed parameters, their value and
232presence is undefined and you cannot rely on them. Portable AnyEvent 250presence is undefined and you cannot rely on them. Portable AnyEvent
233callbacks cannot use arguments passed to time watcher callbacks. 251callbacks cannot use arguments passed to time watcher callbacks.
234 252
235The callback will normally be invoked once only. If you specify another 253The callback will normally be invoked only once. If you specify another
236parameter, C<interval>, as a strictly positive number (> 0), then the 254parameter, C<interval>, as a strictly positive number (> 0), then the
237callback will be invoked regularly at that interval (in fractional 255callback will be invoked regularly at that interval (in fractional
238seconds) after the first invocation. If C<interval> is specified with a 256seconds) after the first invocation. If C<interval> is specified with a
239false value, then it is treated as if it were missing. 257false value, then it is treated as if it were not specified at all.
240 258
241The callback will be rescheduled before invoking the callback, but no 259The callback will be rescheduled before invoking the callback, but no
242attempt 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
243only approximate. 261only approximate.
244 262
245Example: fire an event after 7.7 seconds. 263Example: fire an event after 7.7 seconds.
246 264
247 my $w = AnyEvent->timer (after => 7.7, cb => sub { 265 my $w = AnyEvent->timer (after => 7.7, cb => sub {
265 283
266While 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
267use absolute time internally. This makes a difference when your clock 285use absolute time internally. This makes a difference when your clock
268"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
269the 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
270fire "after" a second might actually take six years to finally fire. 288fire "after a second" might actually take six years to finally fire.
271 289
272AnyEvent cannot compensate for this. The only event loop that is conscious 290AnyEvent cannot compensate for this. The only event loop that is conscious
273about 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
274on true relative time) and absolute (ev_periodic, based on wallclock time) 292on true relative time) and absolute (ev_periodic, based on wallclock time)
275timers. 293timers.
276 294
277AnyEvent always prefers relative timers, if available, matching the 295AnyEvent always prefers relative timers, if available, matching the
278AnyEvent API. 296AnyEvent API.
300I<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
301function to call when you want to know the current time.> 319function to call when you want to know the current time.>
302 320
303This function is also often faster then C<< AnyEvent->time >>, and 321This function is also often faster then C<< AnyEvent->time >>, and
304thus the preferred method if you want some timestamp (for example, 322thus the preferred method if you want some timestamp (for example,
305L<AnyEvent::Handle> uses this to update it's activity timeouts). 323L<AnyEvent::Handle> uses this to update its activity timeouts).
306 324
307The 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
308with your timing, you can skip it without bad conscience. 326with your timing; you can skip it without a bad conscience.
309 327
310For 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>
311and L<EV> and the following set-up: 329and L<EV> and the following set-up:
312 330
313The 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
314time=500 (assume no other callbacks delay processing). In your callback, 332time=500 (assume no other callbacks delay processing). In your callback,
315you 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
316second) 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
317after three seconds. 335after three seconds.
318 336
338difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into 356difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
339account. 357account.
340 358
341=item AnyEvent->now_update 359=item AnyEvent->now_update
342 360
343Some 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
344the current time for each loop iteration (see the discussion of L<< 362time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
345AnyEvent->now >>, above). 363above).
346 364
347When 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
348this "current" time will differ substantially from the real time, which 366this "current" time will differ substantially from the real time, which
349might affect timers and time-outs. 367might affect timers and time-outs.
350 368
351When 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
352event loop's idea of "current time". 370event loop's idea of "current time".
353 371
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
354Note 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.
355 380
356=back 381=back
357 382
358=head2 SIGNAL WATCHERS 383=head2 SIGNAL WATCHERS
384
385 $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
359 386
360You 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
361I<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
362callback to be invoked whenever a signal occurs. 389callback to be invoked whenever a signal occurs.
363 390
380 407
381Example: exit on SIGINT 408Example: exit on SIGINT
382 409
383 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); 410 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
384 411
412=head3 Restart Behaviour
413
414While restart behaviour is up to the event loop implementation, most will
415not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
416pure perl implementation).
417
418=head3 Safe/Unsafe Signals
419
420Perl signals can be either "safe" (synchronous to opcode handling) or
421"unsafe" (asynchronous) - the former might get delayed indefinitely, the
422latter might corrupt your memory.
423
424AnyEvent signal handlers are, in addition, synchronous to the event loop,
425i.e. they will not interrupt your running perl program but will only be
426called as part of the normal event handling (just like timer, I/O etc.
427callbacks, too).
428
385=head3 Signal Races, Delays and Workarounds 429=head3 Signal Races, Delays and Workarounds
386 430
387Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching 431Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
388callbacks to signals in a generic way, which is a pity, as you cannot do 432callbacks to signals in a generic way, which is a pity, as you cannot
389race-free signal handling in perl. AnyEvent will try to do it's best, but 433do race-free signal handling in perl, requiring C libraries for
434this. AnyEvent will try to do its best, which means in some cases,
390in some cases, signals will be delayed. The maximum time a signal might 435signals will be delayed. The maximum time a signal might be delayed is
391be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 436specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
392seconds). This variable can be changed only before the first signal 437variable can be changed only before the first signal watcher is created,
393watcher 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
394will 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
395saving. All these problems can be avoided by installing the optional 443All these problems can be avoided by installing the optional
396L<Async::Interrupt> module. This will not work with inherently broken 444L<Async::Interrupt> module, which works with most event loops. It will not
397event loops such as L<Event> or L<Event::Lib> (and not with L<POE> 445work with inherently broken event loops such as L<Event> or L<Event::Lib>
398currently, as POE does it's own workaround with one-second latency). With 446(and not with L<POE> currently, as POE does its own workaround with
399those, you just have to suffer the delays. 447one-second latency). For those, you just have to suffer the delays.
400 448
401=head2 CHILD PROCESS WATCHERS 449=head2 CHILD PROCESS WATCHERS
402 450
451 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
452
403You 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.
404 454
405The 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,
406watches for any child process exit). The watcher will triggered only when 456using C<0> watches for any child process exit, on others this will
407the child process has finished and an exit status is available, not on 457croak). The watcher will be triggered only when the child process has
408any trace events (stopped/continued). 458finished and an exit status is available, not on any trace events
459(stopped/continued).
409 460
410The 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
411waitpid), 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
412callback arguments. 463callback arguments.
413 464
431thing 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
432watcher before you C<fork> the child (alternatively, you can call 483watcher before you C<fork> the child (alternatively, you can call
433C<AnyEvent::detect>). 484C<AnyEvent::detect>).
434 485
435As 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
436emulated 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
437mentioned in the description of signal watchers apply. 488problems mentioned in the description of signal watchers apply.
438 489
439Example: fork a process and wait for it 490Example: fork a process and wait for it
440 491
441 my $done = AnyEvent->condvar; 492 my $done = AnyEvent->condvar;
442 493
454 # do something else, then wait for process exit 505 # do something else, then wait for process exit
455 $done->recv; 506 $done->recv;
456 507
457=head2 IDLE WATCHERS 508=head2 IDLE WATCHERS
458 509
459Sometimes there is a need to do something, but it is not so important 510 $w = AnyEvent->idle (cb => <callback>);
460to do it instantly, but only when there is nothing better to do. This
461"nothing better to do" is usually defined to be "no other events need
462attention by the event loop".
463 511
464Idle watchers ideally get invoked when the event loop has nothing 512This will repeatedly invoke the callback after the process becomes idle,
465better 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.
466events. Instead of blocking, the idle watcher is invoked.
467 514
468Most 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
469EV, 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
470will simply call the callback "from time to time". 526will simply call the callback "from time to time".
471 527
472Example: read lines from STDIN, but only process them when the 528Example: read lines from STDIN, but only process them when the
473program is otherwise idle: 529program is otherwise idle:
489 }); 545 });
490 }); 546 });
491 547
492=head2 CONDITION VARIABLES 548=head2 CONDITION VARIABLES
493 549
550 $cv = AnyEvent->condvar;
551
552 $cv->send (<list>);
553 my @res = $cv->recv;
554
494If 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
495require you to run some blocking "loop", "run" or similar function that 556require you to run some blocking "loop", "run" or similar function that
496will actively watch for new events and call your callbacks. 557will actively watch for new events and call your callbacks.
497 558
498AnyEvent is slightly different: it expects somebody else to run the event 559AnyEvent is slightly different: it expects somebody else to run the event
499loop 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).
500 561
501The instrument to do that is called a "condition variable", so called 562The tool to do that is called a "condition variable", so called because
502because they represent a condition that must become true. 563they represent a condition that must become true.
503 564
504Now 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.
505 566
506Condition variables can be created by calling the C<< AnyEvent->condvar 567Condition variables can be created by calling the C<< AnyEvent->condvar
507>> method, usually without arguments. The only argument pair allowed is 568>> method, usually without arguments. The only argument pair allowed is
512After creation, the condition variable is "false" until it becomes "true" 573After creation, the condition variable is "false" until it becomes "true"
513by 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
514were 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<<
515->send >> method). 576->send >> method).
516 577
517Condition variables are similar to callbacks, except that you can 578Since condition variables are the most complex part of the AnyEvent API, here are
518optionally 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:
519in time where multiple outstanding events have been processed. And yet 580
520another way to call them is transactions - each condition variable can be 581=over 4
521used to represent a transaction, which finishes at some point and delivers 582
522a result. And yet some people know them as "futures" - a promise to 583=item * Condition variables are like callbacks - you can call them (and pass them instead
523compute/deliver something that you can wait for. 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
524 601
525Condition variables are very useful to signal that something has finished, 602Condition variables are very useful to signal that something has finished,
526for example, if you write a module that does asynchronous http requests, 603for example, if you write a module that does asynchronous http requests,
527then a condition variable would be the ideal candidate to signal the 604then a condition variable would be the ideal candidate to signal the
528availability of results. The user can either act when the callback is 605availability of results. The user can either act when the callback is
541 618
542Condition variables are represented by hash refs in perl, and the keys 619Condition variables are represented by hash refs in perl, and the keys
543used 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
544easy (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
545AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call 622AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
546it's C<new> method in your own C<new> method. 623its C<new> method in your own C<new> method.
547 624
548There are two "sides" to a condition variable - the "producer side" which 625There are two "sides" to a condition variable - the "producer side" which
549eventually calls C<< -> send >>, and the "consumer side", which waits 626eventually calls C<< -> send >>, and the "consumer side", which waits
550for the send to occur. 627for the send to occur.
551 628
552Example: wait for a timer. 629Example: wait for a timer.
553 630
554 # wait till the result is ready 631 # condition: "wait till the timer is fired"
555 my $result_ready = AnyEvent->condvar; 632 my $timer_fired = AnyEvent->condvar;
556 633
557 # do something such as adding a timer 634 # create the timer - we could wait for, say
558 # or socket watcher the calls $result_ready->send 635 # a handle becomign ready, or even an
559 # when the "result" is ready. 636 # AnyEvent::HTTP request to finish, but
560 # in this case, we simply use a timer: 637 # in this case, we simply use a timer:
561 my $w = AnyEvent->timer ( 638 my $w = AnyEvent->timer (
562 after => 1, 639 after => 1,
563 cb => sub { $result_ready->send }, 640 cb => sub { $timer_fired->send },
564 ); 641 );
565 642
566 # this "blocks" (while handling events) till the callback 643 # this "blocks" (while handling events) till the callback
567 # calls -<send 644 # calls ->send
568 $result_ready->recv; 645 $timer_fired->recv;
569 646
570Example: 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
571variables are also callable directly. 648variables are also callable directly.
572 649
573 my $done = AnyEvent->condvar; 650 my $done = AnyEvent->condvar;
616they 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
617C<send>. 694C<send>.
618 695
619=item $cv->croak ($error) 696=item $cv->croak ($error)
620 697
621Similar to send, but causes all call's to C<< ->recv >> to invoke 698Similar to send, but causes all calls to C<< ->recv >> to invoke
622C<Carp::croak> with the given error message/object/scalar. 699C<Carp::croak> with the given error message/object/scalar.
623 700
624This can be used to signal any errors to the condition variable 701This can be used to signal any errors to the condition variable
625user/consumer. Doing it this way instead of calling C<croak> directly 702user/consumer. Doing it this way instead of calling C<croak> directly
626delays the error detetcion, but has the overwhelmign advantage that it 703delays the error detection, but has the overwhelming advantage that it
627diagnoses 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
628deep in some event clalback without connection to the actual code causing 705deep in some event callback with no connection to the actual code causing
629the problem. 706the problem.
630 707
631=item $cv->begin ([group callback]) 708=item $cv->begin ([group callback])
632 709
633=item $cv->end 710=item $cv->end
636one. 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
637to use a condition variable for the whole process. 714to use a condition variable for the whole process.
638 715
639Every 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
640C<< ->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
641>>, 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
642is 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
643callback 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.
644 722
645You 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
646sends), 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
647condition (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).
648 726
670one 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
671sending. 749sending.
672 750
673The ping example mentioned above is slightly more complicated, as the 751The ping example mentioned above is slightly more complicated, as the
674there 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
675begung can potentially be zero: 753begun can potentially be zero:
676 754
677 my $cv = AnyEvent->condvar; 755 my $cv = AnyEvent->condvar;
678 756
679 my %result; 757 my %result;
680 $cv->begin (sub { $cv->send (\%result) }); 758 $cv->begin (sub { shift->send (\%result) });
681 759
682 for my $host (@list_of_hosts) { 760 for my $host (@list_of_hosts) {
683 $cv->begin; 761 $cv->begin;
684 ping_host_then_call_callback $host, sub { 762 ping_host_then_call_callback $host, sub {
685 $result{$host} = ...; 763 $result{$host} = ...;
701to 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
702C<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
703doesn't execute once). 781doesn't execute once).
704 782
705This is the general pattern when you "fan out" into multiple (but 783This is the general pattern when you "fan out" into multiple (but
706potentially 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
707the 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
708subrequest you start, call C<begin> and for each subrequest you finish, 786subrequest you start, call C<begin> and for each subrequest you finish,
709call C<end>. 787call C<end>.
710 788
711=back 789=back
718=over 4 796=over 4
719 797
720=item $cv->recv 798=item $cv->recv
721 799
722Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 800Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
723>> methods have been called on c<$cv>, while servicing other watchers 801>> methods have been called on C<$cv>, while servicing other watchers
724normally. 802normally.
725 803
726You 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
727will return immediately. 805will return immediately.
728 806
745caller 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
746condition variables with some kind of request results and supporting 824condition variables with some kind of request results and supporting
747callbacks so the caller knows that getting the result will not block, 825callbacks so the caller knows that getting the result will not block,
748while still supporting blocking waits if the caller so desires). 826while still supporting blocking waits if the caller so desires).
749 827
750You 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
751only calling C<< ->recv >> from within that callback (or at a later 829only calling C<< ->recv >> from within that callback (or at a later
752time). 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
753waits otherwise. 831waits otherwise.
754 832
755=item $bool = $cv->ready 833=item $bool = $cv->ready
761 839
762This is a mutator function that returns the callback set and optionally 840This is a mutator function that returns the callback set and optionally
763replaces it before doing so. 841replaces it before doing so.
764 842
765The 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
766C<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
767variable itself. Calling C<recv> inside the callback or at any later time 845condition variable itself. If the condition is already true, the
768is 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.
769 848
770=back 849=back
771 850
772=head1 SUPPORTED EVENT LOOPS/BACKENDS 851=head1 SUPPORTED EVENT LOOPS/BACKENDS
773 852
776=over 4 855=over 4
777 856
778=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.
779 858
780EV 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
781use. 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
782that, will fall back to its own pure-perl implementation, which is 861pure-perl implementation, which is available everywhere as it comes with
783available everywhere as it comes with AnyEvent itself. 862AnyEvent itself.
784 863
785 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 864 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
786 AnyEvent::Impl::Event based on Event, very stable, few glitches.
787 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 865 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
788 866
789=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.
790 868
791These 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
792is 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
793them. This means that AnyEvent will automatically pick the right backend 871them. This means that AnyEvent will automatically pick the right backend
794when the main program loads an event module before anything starts to 872when the main program loads an event module before anything starts to
795create watchers. Nothing special needs to be done by the main program. 873create watchers. Nothing special needs to be done by the main program.
796 874
875 AnyEvent::Impl::Event based on Event, very stable, few glitches.
797 AnyEvent::Impl::Glib based on Glib, slow but very stable. 876 AnyEvent::Impl::Glib based on Glib, slow but very stable.
798 AnyEvent::Impl::Tk based on Tk, very broken. 877 AnyEvent::Impl::Tk based on Tk, very broken.
799 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 878 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
800 AnyEvent::Impl::POE based on POE, very slow, some limitations. 879 AnyEvent::Impl::POE based on POE, very slow, some limitations.
880 AnyEvent::Impl::Irssi used when running within irssi.
881 AnyEvent::Impl::IOAsync based on IO::Async.
882 AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
883 AnyEvent::Impl::FLTK based on FLTK.
801 884
802=item Backends with special needs. 885=item Backends with special needs.
803 886
804Qt requires the Qt::Application to be instantiated first, but will 887Qt requires the Qt::Application to be instantiated first, but will
805otherwise be picked up automatically. As long as the main program 888otherwise be picked up automatically. As long as the main program
806instantiates the application before any AnyEvent watchers are created, 889instantiates the application before any AnyEvent watchers are created,
807everything should just work. 890everything should just work.
808 891
809 AnyEvent::Impl::Qt based on Qt. 892 AnyEvent::Impl::Qt based on Qt.
810 893
811Support for IO::Async can only be partial, as it is too broken and
812architecturally limited to even support the AnyEvent API. It also
813is the only event loop that needs the loop to be set explicitly, so
814it can only be used by a main program knowing about AnyEvent. See
815L<AnyEvent::Impl::Async> for the gory details.
816
817 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
818
819=item Event loops that are indirectly supported via other backends. 894=item Event loops that are indirectly supported via other backends.
820 895
821Some event loops can be supported via other modules: 896Some event loops can be supported via other modules:
822 897
823There is no direct support for WxWidgets (L<Wx>) or L<Prima>. 898There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
848Contains C<undef> until the first watcher is being created, before the 923Contains C<undef> until the first watcher is being created, before the
849backend has been autodetected. 924backend has been autodetected.
850 925
851Afterwards 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
852name 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
853of 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
854case 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
855will be C<urxvt::anyevent>). 930will be C<urxvt::anyevent>).
856 931
857=item AnyEvent::detect 932=item AnyEvent::detect
858 933
859Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 934Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
860if necessary. You should only call this function right before you would 935if necessary. You should only call this function right before you would
861have 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
862runtime, and not e.g. while initialising of your module. 937runtime, and not e.g. during initialisation of your module.
863 938
864If you need to do some initialisation before AnyEvent watchers are 939If you need to do some initialisation before AnyEvent watchers are
865created, use C<post_detect>. 940created, use C<post_detect>.
866 941
867=item $guard = AnyEvent::post_detect { BLOCK } 942=item $guard = AnyEvent::post_detect { BLOCK }
868 943
869Arranges for the code block to be executed as soon as the event model is 944Arranges for the code block to be executed as soon as the event model is
870autodetected (or immediately if this has already happened). 945autodetected (or immediately if that has already happened).
871 946
872The block will be executed I<after> the actual backend has been detected 947The block will be executed I<after> the actual backend has been detected
873(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been 948(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
874created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do 949created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
875other initialisations - see the sources of L<AnyEvent::Strict> or 950other initialisations - see the sources of L<AnyEvent::Strict> or
884that automatically removes the callback again when it is destroyed (or 959that automatically removes the callback again when it is destroyed (or
885C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for 960C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
886a case where this is useful. 961a case where this is useful.
887 962
888Example: Create a watcher for the IO::AIO module and store it in 963Example: Create a watcher for the IO::AIO module and store it in
889C<$WATCHER>. Only do so after the event loop is initialised, though. 964C<$WATCHER>, but do so only do so after the event loop is initialised.
890 965
891 our WATCHER; 966 our WATCHER;
892 967
893 my $guard = AnyEvent::post_detect { 968 my $guard = AnyEvent::post_detect {
894 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); 969 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
902 $WATCHER ||= $guard; 977 $WATCHER ||= $guard;
903 978
904=item @AnyEvent::post_detect 979=item @AnyEvent::post_detect
905 980
906If there are any code references in this array (you can C<push> to it 981If there are any code references in this array (you can C<push> to it
907before or after loading AnyEvent), then they will called directly after 982before or after loading AnyEvent), then they will be called directly
908the event loop has been chosen. 983after the event loop has been chosen.
909 984
910You should check C<$AnyEvent::MODEL> before adding to this array, though: 985You should check C<$AnyEvent::MODEL> before adding to this array, though:
911if 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
912array will be ignored. 987array will be ignored.
913 988
914Best use C<AnyEvent::post_detect { BLOCK }> when your application allows 989Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
915it,as it takes care of these details. 990it, as it takes care of these details.
916 991
917This variable is mainly useful for modules that can do something useful 992This variable is mainly useful for modules that can do something useful
918when 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
919not 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
920into AnyEvent passively, without loading it. 995into AnyEvent passively, without loading it.
921 996
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
922=back 1050=back
923 1051
924=head1 WHAT TO DO IN A MODULE 1052=head1 WHAT TO DO IN A MODULE
925 1053
926As 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
936because 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
937events is to stay interactive. 1065events is to stay interactive.
938 1066
939It 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
940requests 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
941called C<results> that returns the results, it should call C<< ->recv >> 1069called C<results> that returns the results, it may call C<< ->recv >>
942freely, 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).
943 1071
944=head1 WHAT TO DO IN THE MAIN PROGRAM 1072=head1 WHAT TO DO IN THE MAIN PROGRAM
945 1073
946There 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
947dictate which event model to use. 1075dictate which event model to use.
948 1076
949If 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
950do 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
951decide 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.
952 1082
953If 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
954Gtk2 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
955event module before loading AnyEvent or any module that uses it: generally 1085event module before loading AnyEvent or any module that uses it: generally
956speaking, 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
957modules might create watchers when they are loaded, and AnyEvent will 1087modules might create watchers when they are loaded, and AnyEvent will
958decide 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
959might chose the wrong one unless you load the correct one yourself. 1089might choose the wrong one unless you load the correct one yourself.
960 1090
961You can chose to use a pure-perl implementation by loading the 1091You can chose to use a pure-perl implementation by loading the
962C<AnyEvent::Impl::Perl> module, which gives you similar behaviour 1092C<AnyEvent::Loop> module, which gives you similar behaviour
963everywhere, but letting AnyEvent chose the model is generally better. 1093everywhere, but letting AnyEvent chose the model is generally better.
964 1094
965=head2 MAINLOOP EMULATION 1095=head2 MAINLOOP EMULATION
966 1096
967Sometimes (often for short test scripts, or even standalone programs who 1097Sometimes (often for short test scripts, or even standalone programs who
982=head1 OTHER MODULES 1112=head1 OTHER MODULES
983 1113
984The following is a non-exhaustive list of additional modules that use 1114The following is a non-exhaustive list of additional modules that use
985AnyEvent 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
986modules 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
987come with AnyEvent, most are available via CPAN. 1117come as part of AnyEvent, the others are available via CPAN.
988 1118
989=over 4 1119=over 4
990 1120
991=item L<AnyEvent::Util> 1121=item L<AnyEvent::Util>
992 1122
993Contains various utility functions that replace often-used but blocking 1123Contains various utility functions that replace often-used blocking
994functions such as C<inet_aton> by event-/callback-based versions. 1124functions such as C<inet_aton> with event/callback-based versions.
995 1125
996=item L<AnyEvent::Socket> 1126=item L<AnyEvent::Socket>
997 1127
998Provides various utility functions for (internet protocol) sockets, 1128Provides various utility functions for (internet protocol) sockets,
999addresses and name resolution. Also functions to create non-blocking tcp 1129addresses and name resolution. Also functions to create non-blocking tcp
1001 1131
1002=item L<AnyEvent::Handle> 1132=item L<AnyEvent::Handle>
1003 1133
1004Provide read and write buffers, manages watchers for reads and writes, 1134Provide read and write buffers, manages watchers for reads and writes,
1005supports 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
1006non-blocking SSL/TLS (via L<AnyEvent::TLS>. 1136non-blocking SSL/TLS (via L<AnyEvent::TLS>).
1007 1137
1008=item L<AnyEvent::DNS> 1138=item L<AnyEvent::DNS>
1009 1139
1010Provides rich asynchronous DNS resolver capabilities. 1140Provides rich asynchronous DNS resolver capabilities.
1011 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
1012=item L<AnyEvent::HTTP> 1165=item L<AnyEvent::DBI>
1013 1166
1014A 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,
1015HTTP 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.
1016 1176
1017=item L<AnyEvent::HTTPD> 1177=item L<AnyEvent::HTTPD>
1018 1178
1019Provides a simple web application server framework. 1179A simple embedded webserver.
1020 1180
1021=item L<AnyEvent::FastPing> 1181=item L<AnyEvent::FastPing>
1022 1182
1023The fastest ping in the west. 1183The fastest ping in the west.
1024
1025=item L<AnyEvent::DBI>
1026
1027Executes L<DBI> requests asynchronously in a proxy process.
1028
1029=item L<AnyEvent::AIO>
1030
1031Truly asynchronous I/O, should be in the toolbox of every event
1032programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
1033together.
1034
1035=item L<AnyEvent::BDB>
1036
1037Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
1038L<BDB> and AnyEvent together.
1039
1040=item L<AnyEvent::GPSD>
1041
1042A non-blocking interface to gpsd, a daemon delivering GPS information.
1043
1044=item L<AnyEvent::IRC>
1045
1046AnyEvent based IRC client module family (replacing the older Net::IRC3).
1047
1048=item L<AnyEvent::XMPP>
1049
1050AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1051Net::XMPP2>.
1052
1053=item L<AnyEvent::IGS>
1054
1055A non-blocking interface to the Internet Go Server protocol (used by
1056L<App::IGS>).
1057
1058=item L<Net::FCP>
1059
1060AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1061of AnyEvent.
1062
1063=item L<Event::ExecFlow>
1064
1065High level API for event-based execution flow control.
1066 1184
1067=item L<Coro> 1185=item L<Coro>
1068 1186
1069Has special support for AnyEvent via L<Coro::AnyEvent>. 1187Has special support for AnyEvent via L<Coro::AnyEvent>.
1070 1188
1074 1192
1075package AnyEvent; 1193package AnyEvent;
1076 1194
1077# basically a tuned-down version of common::sense 1195# basically a tuned-down version of common::sense
1078sub common_sense { 1196sub common_sense {
1079 # no warnings 1197 # from common:.sense 3.4
1080 ${^WARNING_BITS} ^= ${^WARNING_BITS}; 1198 ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
1081 # use strict vars subs 1199 # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
1082 $^H |= 0x00000600; 1200 $^H |= 0x00000600;
1083} 1201}
1084 1202
1085BEGIN { AnyEvent::common_sense } 1203BEGIN { AnyEvent::common_sense }
1086 1204
1087use Carp (); 1205use Carp ();
1088 1206
1089our $VERSION = 4.86; 1207our $VERSION = '5.34';
1090our $MODEL; 1208our $MODEL;
1091 1209
1092our $AUTOLOAD; 1210our $AUTOLOAD;
1093our @ISA; 1211our @ISA;
1094 1212
1095our @REGISTRY; 1213our @REGISTRY;
1096 1214
1097our $WIN32;
1098
1099our $VERBOSE; 1215our $VERBOSE;
1100 1216
1101BEGIN { 1217BEGIN {
1102 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1218 require "AnyEvent/constants.pl";
1219
1103 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1220 eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1104 1221
1105 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1222 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1106 if ${^TAINT}; 1223 if ${^TAINT};
1107 1224
1108 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1225 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1119 for reverse split /\s*,\s*/, 1236 for reverse split /\s*,\s*/,
1120 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 1237 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1121} 1238}
1122 1239
1123my @models = ( 1240my @models = (
1124 [EV:: => AnyEvent::Impl::EV::], 1241 [EV:: => AnyEvent::Impl::EV:: , 1],
1125 [Event:: => AnyEvent::Impl::Event::], 1242 [AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1126 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1127 # everything below here will not be autoprobed 1243 # everything below here will not (normally) be autoprobed
1128 # as the pureperl backend should work everywhere 1244 # as the pure perl backend should work everywhere
1129 # and is usually faster 1245 # and is usually faster
1246 [Event:: => AnyEvent::Impl::Event::, 1],
1130 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers 1247 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1131 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1248 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1249 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1132 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles 1250 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1133 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 1251 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1134 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1252 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1135 [Wx:: => AnyEvent::Impl::POE::], 1253 [Wx:: => AnyEvent::Impl::POE::],
1136 [Prima:: => AnyEvent::Impl::POE::], 1254 [Prima:: => AnyEvent::Impl::POE::],
1137 # IO::Async is just too broken - we would need workarounds for its
1138 # byzantine signal and broken child handling, among others.
1139 # IO::Async is rather hard to detect, as it doesn't have any
1140 # obvious default class.
1141# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1142# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program 1255 [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::],
1143# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program 1256 [Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1257 [FLTK:: => AnyEvent::Impl::FLTK::],
1144); 1258);
1145 1259
1146our %method = map +($_ => 1), 1260our %method = map +($_ => 1),
1147 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1261 qw(io timer time now now_update signal child idle condvar DESTROY);
1148 1262
1149our @post_detect; 1263our @post_detect;
1150 1264
1151sub post_detect(&) { 1265sub post_detect(&) {
1152 my ($cb) = @_; 1266 my ($cb) = @_;
1153 1267
1154 if ($MODEL) {
1155 $cb->();
1156
1157 1
1158 } else {
1159 push @post_detect, $cb; 1268 push @post_detect, $cb;
1160 1269
1161 defined wantarray 1270 defined wantarray
1162 ? bless \$cb, "AnyEvent::Util::postdetect" 1271 ? bless \$cb, "AnyEvent::Util::postdetect"
1163 : () 1272 : ()
1164 }
1165} 1273}
1166 1274
1167sub AnyEvent::Util::postdetect::DESTROY { 1275sub AnyEvent::Util::postdetect::DESTROY {
1168 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1276 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1169} 1277}
1170 1278
1171sub detect() { 1279sub detect() {
1280 # free some memory
1281 *detect = sub () { $MODEL };
1282
1283 local $!; # for good measure
1284 local $SIG{__DIE__};
1285
1286 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1287 my $model = "AnyEvent::Impl::$1";
1288 if (eval "require $model") {
1289 $MODEL = $model;
1290 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1291 } else {
1292 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1293 }
1294 }
1295
1296 # check for already loaded models
1172 unless ($MODEL) { 1297 unless ($MODEL) {
1173 local $SIG{__DIE__}; 1298 for (@REGISTRY, @models) {
1174 1299 my ($package, $model) = @$_;
1175 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1300 if (${"$package\::VERSION"} > 0) {
1176 my $model = "AnyEvent::Impl::$1";
1177 if (eval "require $model") { 1301 if (eval "require $model") {
1178 $MODEL = $model; 1302 $MODEL = $model;
1179 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2; 1303 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1180 } else { 1304 last;
1181 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE; 1305 }
1182 } 1306 }
1183 } 1307 }
1184 1308
1185 # check for already loaded models
1186 unless ($MODEL) { 1309 unless ($MODEL) {
1310 # try to autoload a model
1187 for (@REGISTRY, @models) { 1311 for (@REGISTRY, @models) {
1188 my ($package, $model) = @$_; 1312 my ($package, $model, $autoload) = @$_;
1313 if (
1314 $autoload
1315 and eval "require $package"
1189 if (${"$package\::VERSION"} > 0) { 1316 and ${"$package\::VERSION"} > 0
1190 if (eval "require $model") { 1317 and eval "require $model"
1318 ) {
1191 $MODEL = $model; 1319 $MODEL = $model;
1192 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2; 1320 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1193 last; 1321 last;
1194 }
1195 } 1322 }
1196 } 1323 }
1197 1324
1198 unless ($MODEL) {
1199 # try to load a model
1200
1201 for (@REGISTRY, @models) {
1202 my ($package, $model) = @$_;
1203 if (eval "require $package"
1204 and ${"$package\::VERSION"} > 0
1205 and eval "require $model") {
1206 $MODEL = $model;
1207 warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
1208 last;
1209 }
1210 }
1211
1212 $MODEL 1325 $MODEL
1213 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n"; 1326 or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1214 }
1215 } 1327 }
1216
1217 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1218
1219 unshift @ISA, $MODEL;
1220
1221 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1222
1223 (shift @post_detect)->() while @post_detect;
1224 } 1328 }
1329
1330 @models = (); # free probe data
1331
1332 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1333 unshift @ISA, $MODEL;
1334
1335 # now nuke some methods that are overridden by the backend.
1336 # SUPER is not allowed.
1337 for (qw(time signal child idle)) {
1338 undef &{"AnyEvent::Base::$_"}
1339 if defined &{"$MODEL\::$_"};
1340 }
1341
1342 if ($ENV{PERL_ANYEVENT_STRICT}) {
1343 eval { require AnyEvent::Strict };
1344 warn "AnyEvent: cannot load AnyEvent::Strict: $@"
1345 if $@ && $VERBOSE;
1346 }
1347
1348 (shift @post_detect)->() while @post_detect;
1349
1350 *post_detect = sub(&) {
1351 shift->();
1352
1353 undef
1354 };
1225 1355
1226 $MODEL 1356 $MODEL
1227} 1357}
1228 1358
1229sub AUTOLOAD { 1359sub AUTOLOAD {
1230 (my $func = $AUTOLOAD) =~ s/.*://; 1360 (my $func = $AUTOLOAD) =~ s/.*://;
1231 1361
1232 $method{$func} 1362 $method{$func}
1233 or Carp::croak "$func: not a valid method for AnyEvent objects"; 1363 or Carp::croak "$func: not a valid AnyEvent class method";
1234 1364
1235 detect unless $MODEL; 1365 detect;
1236 1366
1237 my $class = shift; 1367 my $class = shift;
1238 $class->$func (@_); 1368 $class->$func (@_);
1369}
1370
1371our $POSTPONE_W;
1372our @POSTPONE;
1373
1374sub _postpone_exec {
1375 undef $POSTPONE_W;
1376 (pop @POSTPONE)->()
1377 while @POSTPONE;
1378}
1379
1380sub postpone(&) {
1381 push @POSTPONE, shift;
1382
1383 $POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
1384
1385 ()
1239} 1386}
1240 1387
1241# utility function to dup a filehandle. this is used by many backends 1388# utility function to dup a filehandle. this is used by many backends
1242# to support binding more than one watcher per filehandle (they usually 1389# to support binding more than one watcher per filehandle (they usually
1243# allow only one watcher per fd, so we dup it to get a different one). 1390# allow only one watcher per fd, so we dup it to get a different one).
1253 # we assume CLOEXEC is already set by perl in all important cases 1400 # we assume CLOEXEC is already set by perl in all important cases
1254 1401
1255 ($fh2, $rw) 1402 ($fh2, $rw)
1256} 1403}
1257 1404
1405=head1 SIMPLIFIED AE API
1406
1407Starting with version 5.0, AnyEvent officially supports a second, much
1408simpler, API that is designed to reduce the calling, typing and memory
1409overhead by using function call syntax and a fixed number of parameters.
1410
1411See the L<AE> manpage for details.
1412
1413=cut
1414
1415package AE;
1416
1417our $VERSION = $AnyEvent::VERSION;
1418
1419# fall back to the main API by default - backends and AnyEvent::Base
1420# implementations can overwrite these.
1421
1422sub io($$$) {
1423 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
1424}
1425
1426sub timer($$$) {
1427 AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
1428}
1429
1430sub signal($$) {
1431 AnyEvent->signal (signal => $_[0], cb => $_[1])
1432}
1433
1434sub child($$) {
1435 AnyEvent->child (pid => $_[0], cb => $_[1])
1436}
1437
1438sub idle($) {
1439 AnyEvent->idle (cb => $_[0])
1440}
1441
1442sub cv(;&) {
1443 AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
1444}
1445
1446sub now() {
1447 AnyEvent->now
1448}
1449
1450sub now_update() {
1451 AnyEvent->now_update
1452}
1453
1454sub time() {
1455 AnyEvent->time
1456}
1457
1458*postpone = \&AnyEvent::postpone;
1459
1258package AnyEvent::Base; 1460package AnyEvent::Base;
1259 1461
1260# default implementations for many methods 1462# default implementations for many methods
1261 1463
1262sub _time { 1464sub time {
1465 eval q{ # poor man's autoloading {}
1263 # probe for availability of Time::HiRes 1466 # probe for availability of Time::HiRes
1264 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1467 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1265 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8; 1468 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1266 *_time = \&Time::HiRes::time; 1469 *AE::time = \&Time::HiRes::time;
1267 # if (eval "use POSIX (); (POSIX::times())... 1470 # if (eval "use POSIX (); (POSIX::times())...
1268 } else { 1471 } else {
1269 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE; 1472 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1270 *_time = sub { time }; # epic fail 1473 *AE::time = sub (){ time }; # epic fail
1474 }
1475
1476 *time = sub { AE::time }; # different prototypes
1271 } 1477 };
1478 die if $@;
1272 1479
1273 &_time 1480 &time
1274} 1481}
1275 1482
1276sub time { _time } 1483*now = \&time;
1277sub now { _time } 1484
1278sub now_update { } 1485sub now_update { }
1279 1486
1487sub _poll {
1488 Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
1489}
1490
1280# default implementation for ->condvar 1491# default implementation for ->condvar
1492# in fact, the default should not be overwritten
1281 1493
1282sub condvar { 1494sub condvar {
1495 eval q{ # poor man's autoloading {}
1496 *condvar = sub {
1283 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1497 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1498 };
1499
1500 *AE::cv = sub (;&) {
1501 bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
1502 };
1503 };
1504 die if $@;
1505
1506 &condvar
1284} 1507}
1285 1508
1286# default implementation for ->signal 1509# default implementation for ->signal
1287 1510
1288our $HAVE_ASYNC_INTERRUPT; 1511our $HAVE_ASYNC_INTERRUPT;
1512
1513sub _have_async_interrupt() {
1514 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
1515 && eval "use Async::Interrupt 1.02 (); 1")
1516 unless defined $HAVE_ASYNC_INTERRUPT;
1517
1518 $HAVE_ASYNC_INTERRUPT
1519}
1520
1289our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1521our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1290our (%SIG_ASY, %SIG_ASY_W); 1522our (%SIG_ASY, %SIG_ASY_W);
1291our ($SIG_COUNT, $SIG_TW); 1523our ($SIG_COUNT, $SIG_TW);
1292 1524
1293sub _signal_exec {
1294 $HAVE_ASYNC_INTERRUPT
1295 ? $SIGPIPE_R->drain
1296 : sysread $SIGPIPE_R, my $dummy, 9;
1297
1298 while (%SIG_EV) {
1299 for (keys %SIG_EV) {
1300 delete $SIG_EV{$_};
1301 $_->() for values %{ $SIG_CB{$_} || {} };
1302 }
1303 }
1304}
1305
1306# install a dumym wakeupw atcher to reduce signal catching latency 1525# install a dummy wakeup watcher to reduce signal catching latency
1526# used by Impls
1307sub _sig_add() { 1527sub _sig_add() {
1308 unless ($SIG_COUNT++) { 1528 unless ($SIG_COUNT++) {
1309 # try to align timer on a full-second boundary, if possible 1529 # try to align timer on a full-second boundary, if possible
1310 my $NOW = AnyEvent->now; 1530 my $NOW = AE::now;
1311 1531
1312 $SIG_TW = AnyEvent->timer ( 1532 $SIG_TW = AE::timer
1313 after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW), 1533 $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1314 interval => $MAX_SIGNAL_LATENCY, 1534 $MAX_SIGNAL_LATENCY,
1315 cb => sub { }, # just for the PERL_ASYNC_CHECK 1535 sub { } # just for the PERL_ASYNC_CHECK
1316 ); 1536 ;
1317 } 1537 }
1318} 1538}
1319 1539
1320sub _sig_del { 1540sub _sig_del {
1321 undef $SIG_TW 1541 undef $SIG_TW
1322 unless --$SIG_COUNT; 1542 unless --$SIG_COUNT;
1323} 1543}
1324 1544
1545our $_sig_name_init; $_sig_name_init = sub {
1546 eval q{ # poor man's autoloading {}
1547 undef $_sig_name_init;
1548
1549 if (_have_async_interrupt) {
1550 *sig2num = \&Async::Interrupt::sig2num;
1551 *sig2name = \&Async::Interrupt::sig2name;
1552 } else {
1553 require Config;
1554
1555 my %signame2num;
1556 @signame2num{ split ' ', $Config::Config{sig_name} }
1557 = split ' ', $Config::Config{sig_num};
1558
1559 my @signum2name;
1560 @signum2name[values %signame2num] = keys %signame2num;
1561
1562 *sig2num = sub($) {
1563 $_[0] > 0 ? shift : $signame2num{+shift}
1564 };
1565 *sig2name = sub ($) {
1566 $_[0] > 0 ? $signum2name[+shift] : shift
1567 };
1568 }
1569 };
1570 die if $@;
1571};
1572
1573sub sig2num ($) { &$_sig_name_init; &sig2num }
1574sub sig2name($) { &$_sig_name_init; &sig2name }
1575
1325sub _signal { 1576sub signal {
1326 my (undef, %arg) = @_; 1577 eval q{ # poor man's autoloading {}
1578 # probe for availability of Async::Interrupt
1579 if (_have_async_interrupt) {
1580 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1327 1581
1328 my $signal = uc $arg{signal} 1582 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1329 or Carp::croak "required option 'signal' is missing"; 1583 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1330 1584
1331 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1585 } else {
1586 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1332 1587
1333 if ($HAVE_ASYNC_INTERRUPT) { 1588 if (AnyEvent::WIN32) {
1334 # async::interrupt 1589 require AnyEvent::Util;
1335 1590
1336 $SIG_ASY{$signal} ||= do { 1591 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1337 my $asy = new Async::Interrupt 1592 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
1338 cb => sub { undef $SIG_EV{$signal} }, 1593 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
1339 signal => $signal, 1594 } else {
1340 pipe => [$SIGPIPE_R->filenos], 1595 pipe $SIGPIPE_R, $SIGPIPE_W;
1596 fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1597 fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1598
1599 # not strictly required, as $^F is normally 2, but let's make sure...
1600 fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1601 fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1341 ; 1602 }
1342 $asy->pipe_autodrain (0);
1343 1603
1344 $asy 1604 $SIGPIPE_R
1605 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1606
1607 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1608 }
1609
1610 *signal = $HAVE_ASYNC_INTERRUPT
1611 ? sub {
1612 my (undef, %arg) = @_;
1613
1614 # async::interrupt
1615 my $signal = sig2num $arg{signal};
1616 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1617
1618 $SIG_ASY{$signal} ||= new Async::Interrupt
1619 cb => sub { undef $SIG_EV{$signal} },
1620 signal => $signal,
1621 pipe => [$SIGPIPE_R->filenos],
1622 pipe_autodrain => 0,
1623 ;
1624
1625 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1626 }
1627 : sub {
1628 my (undef, %arg) = @_;
1629
1630 # pure perl
1631 my $signal = sig2name $arg{signal};
1632 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1633
1634 $SIG{$signal} ||= sub {
1635 local $!;
1636 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1637 undef $SIG_EV{$signal};
1638 };
1639
1640 # can't do signal processing without introducing races in pure perl,
1641 # so limit the signal latency.
1642 _sig_add;
1643
1644 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1645 }
1646 ;
1647
1648 *AnyEvent::Base::signal::DESTROY = sub {
1649 my ($signal, $cb) = @{$_[0]};
1650
1651 _sig_del;
1652
1653 delete $SIG_CB{$signal}{$cb};
1654
1655 $HAVE_ASYNC_INTERRUPT
1656 ? delete $SIG_ASY{$signal}
1657 : # delete doesn't work with older perls - they then
1658 # print weird messages, or just unconditionally exit
1659 # instead of getting the default action.
1660 undef $SIG{$signal}
1661 unless keys %{ $SIG_CB{$signal} };
1345 }; 1662 };
1346 1663
1347 } else { 1664 *_signal_exec = sub {
1348 # pure perl 1665 $HAVE_ASYNC_INTERRUPT
1666 ? $SIGPIPE_R->drain
1667 : sysread $SIGPIPE_R, (my $dummy), 9;
1349 1668
1350 $SIG{$signal} ||= sub { 1669 while (%SIG_EV) {
1351 local $!; 1670 for (keys %SIG_EV) {
1352 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; 1671 delete $SIG_EV{$_};
1353 undef $SIG_EV{$signal}; 1672 $_->() for values %{ $SIG_CB{$_} || {} };
1673 }
1674 }
1354 }; 1675 };
1355
1356 # can't do signal processing without introducing races in pure perl,
1357 # so limit the signal latency.
1358 _sig_add;
1359 } 1676 };
1677 die if $@;
1360 1678
1361 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1362}
1363
1364sub signal {
1365 # probe for availability of Async::Interrupt
1366 if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
1367 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1368
1369 $HAVE_ASYNC_INTERRUPT = 1;
1370 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1371 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
1372
1373 } else {
1374 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1375
1376 require Fcntl;
1377
1378 if (AnyEvent::WIN32) {
1379 require AnyEvent::Util;
1380
1381 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1382 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1383 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1384 } else {
1385 pipe $SIGPIPE_R, $SIGPIPE_W;
1386 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1387 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1388
1389 # not strictly required, as $^F is normally 2, but let's make sure...
1390 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1391 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1392 }
1393
1394 $SIGPIPE_R
1395 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1396
1397 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1398 }
1399
1400 *signal = \&_signal;
1401 &signal 1679 &signal
1402}
1403
1404sub AnyEvent::Base::signal::DESTROY {
1405 my ($signal, $cb) = @{$_[0]};
1406
1407 _sig_del;
1408
1409 delete $SIG_CB{$signal}{$cb};
1410
1411 $HAVE_ASYNC_INTERRUPT
1412 ? delete $SIG_ASY{$signal}
1413 : # delete doesn't work with older perls - they then
1414 # print weird messages, or just unconditionally exit
1415 # instead of getting the default action.
1416 undef $SIG{$signal}
1417 unless keys %{ $SIG_CB{$signal} };
1418} 1680}
1419 1681
1420# default implementation for ->child 1682# default implementation for ->child
1421 1683
1422our %PID_CB; 1684our %PID_CB;
1423our $CHLD_W; 1685our $CHLD_W;
1424our $CHLD_DELAY_W; 1686our $CHLD_DELAY_W;
1425our $WNOHANG;
1426 1687
1427sub _sigchld { 1688# used by many Impl's
1428 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1689sub _emit_childstatus($$) {
1429 $_->($pid, $?) 1690 my (undef, $rpid, $rstatus) = @_;
1691
1692 $_->($rpid, $rstatus)
1430 for values %{ $PID_CB{$pid} || {} }, 1693 for values %{ $PID_CB{$rpid} || {} },
1431 values %{ $PID_CB{0} || {} }; 1694 values %{ $PID_CB{0} || {} };
1432 }
1433} 1695}
1434 1696
1435sub child { 1697sub child {
1698 eval q{ # poor man's autoloading {}
1699 *_sigchld = sub {
1700 my $pid;
1701
1702 AnyEvent->_emit_childstatus ($pid, $?)
1703 while ($pid = waitpid -1, WNOHANG) > 0;
1704 };
1705
1706 *child = sub {
1436 my (undef, %arg) = @_; 1707 my (undef, %arg) = @_;
1437 1708
1438 defined (my $pid = $arg{pid} + 0) 1709 my $pid = $arg{pid};
1439 or Carp::croak "required option 'pid' is missing"; 1710 my $cb = $arg{cb};
1440 1711
1441 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1712 $PID_CB{$pid}{$cb+0} = $cb;
1442 1713
1443 # WNOHANG is almost cetrainly 1 everywhere
1444 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1445 ? 1
1446 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1447
1448 unless ($CHLD_W) { 1714 unless ($CHLD_W) {
1449 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1715 $CHLD_W = AE::signal CHLD => \&_sigchld;
1450 # child could be a zombie already, so make at least one round 1716 # child could be a zombie already, so make at least one round
1451 &_sigchld; 1717 &_sigchld;
1452 } 1718 }
1453 1719
1454 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1720 bless [$pid, $cb+0], "AnyEvent::Base::child"
1455} 1721 };
1456 1722
1457sub AnyEvent::Base::child::DESTROY { 1723 *AnyEvent::Base::child::DESTROY = sub {
1458 my ($pid, $cb) = @{$_[0]}; 1724 my ($pid, $icb) = @{$_[0]};
1459 1725
1460 delete $PID_CB{$pid}{$cb}; 1726 delete $PID_CB{$pid}{$icb};
1461 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1727 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1462 1728
1463 undef $CHLD_W unless keys %PID_CB; 1729 undef $CHLD_W unless keys %PID_CB;
1730 };
1731 };
1732 die if $@;
1733
1734 &child
1464} 1735}
1465 1736
1466# idle emulation is done by simply using a timer, regardless 1737# idle emulation is done by simply using a timer, regardless
1467# of whether the process is idle or not, and not letting 1738# of whether the process is idle or not, and not letting
1468# the callback use more than 50% of the time. 1739# the callback use more than 50% of the time.
1469sub idle { 1740sub idle {
1741 eval q{ # poor man's autoloading {}
1742 *idle = sub {
1470 my (undef, %arg) = @_; 1743 my (undef, %arg) = @_;
1471 1744
1472 my ($cb, $w, $rcb) = $arg{cb}; 1745 my ($cb, $w, $rcb) = $arg{cb};
1473 1746
1474 $rcb = sub { 1747 $rcb = sub {
1475 if ($cb) { 1748 if ($cb) {
1476 $w = _time; 1749 $w = _time;
1477 &$cb; 1750 &$cb;
1478 $w = _time - $w; 1751 $w = _time - $w;
1479 1752
1480 # never use more then 50% of the time for the idle watcher, 1753 # never use more then 50% of the time for the idle watcher,
1481 # within some limits 1754 # within some limits
1482 $w = 0.0001 if $w < 0.0001; 1755 $w = 0.0001 if $w < 0.0001;
1483 $w = 5 if $w > 5; 1756 $w = 5 if $w > 5;
1484 1757
1485 $w = AnyEvent->timer (after => $w, cb => $rcb); 1758 $w = AE::timer $w, 0, $rcb;
1486 } else { 1759 } else {
1487 # clean up... 1760 # clean up...
1488 undef $w; 1761 undef $w;
1489 undef $rcb; 1762 undef $rcb;
1763 }
1764 };
1765
1766 $w = AE::timer 0.05, 0, $rcb;
1767
1768 bless \\$cb, "AnyEvent::Base::idle"
1490 } 1769 };
1770
1771 *AnyEvent::Base::idle::DESTROY = sub {
1772 undef $${$_[0]};
1773 };
1491 }; 1774 };
1775 die if $@;
1492 1776
1493 $w = AnyEvent->timer (after => 0.05, cb => $rcb); 1777 &idle
1494
1495 bless \\$cb, "AnyEvent::Base::idle"
1496}
1497
1498sub AnyEvent::Base::idle::DESTROY {
1499 undef $${$_[0]};
1500} 1778}
1501 1779
1502package AnyEvent::CondVar; 1780package AnyEvent::CondVar;
1503 1781
1504our @ISA = AnyEvent::CondVar::Base::; 1782our @ISA = AnyEvent::CondVar::Base::;
1783
1784# only to be used for subclassing
1785sub new {
1786 my $class = shift;
1787 bless AnyEvent->condvar (@_), $class
1788}
1505 1789
1506package AnyEvent::CondVar::Base; 1790package AnyEvent::CondVar::Base;
1507 1791
1508#use overload 1792#use overload
1509# '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1793# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1519 1803
1520sub _send { 1804sub _send {
1521 # nop 1805 # nop
1522} 1806}
1523 1807
1808sub _wait {
1809 AnyEvent->_poll until $_[0]{_ae_sent};
1810}
1811
1524sub send { 1812sub send {
1525 my $cv = shift; 1813 my $cv = shift;
1526 $cv->{_ae_sent} = [@_]; 1814 $cv->{_ae_sent} = [@_];
1527 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; 1815 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
1528 $cv->_send; 1816 $cv->_send;
1535 1823
1536sub ready { 1824sub ready {
1537 $_[0]{_ae_sent} 1825 $_[0]{_ae_sent}
1538} 1826}
1539 1827
1540sub _wait {
1541 $WAITING
1542 and !$_[0]{_ae_sent}
1543 and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
1544
1545 local $WAITING = 1;
1546 AnyEvent->one_event while !$_[0]{_ae_sent};
1547}
1548
1549sub recv { 1828sub recv {
1829 unless ($_[0]{_ae_sent}) {
1830 $WAITING
1831 and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
1832
1833 local $WAITING = 1;
1550 $_[0]->_wait; 1834 $_[0]->_wait;
1835 }
1551 1836
1552 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; 1837 $_[0]{_ae_croak}
1553 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] 1838 and Carp::croak $_[0]{_ae_croak};
1839
1840 wantarray
1841 ? @{ $_[0]{_ae_sent} }
1842 : $_[0]{_ae_sent}[0]
1554} 1843}
1555 1844
1556sub cb { 1845sub cb {
1557 $_[0]{_ae_cb} = $_[1] if @_ > 1; 1846 my $cv = shift;
1847
1848 @_
1849 and $cv->{_ae_cb} = shift
1850 and $cv->{_ae_sent}
1851 and (delete $cv->{_ae_cb})->($cv);
1852
1558 $_[0]{_ae_cb} 1853 $cv->{_ae_cb}
1559} 1854}
1560 1855
1561sub begin { 1856sub begin {
1562 ++$_[0]{_ae_counter}; 1857 ++$_[0]{_ae_counter};
1563 $_[0]{_ae_end_cb} = $_[1] if @_ > 1; 1858 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1568 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; 1863 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1569} 1864}
1570 1865
1571# undocumented/compatibility with pre-3.4 1866# undocumented/compatibility with pre-3.4
1572*broadcast = \&send; 1867*broadcast = \&send;
1573*wait = \&_wait; 1868*wait = \&recv;
1574 1869
1575=head1 ERROR AND EXCEPTION HANDLING 1870=head1 ERROR AND EXCEPTION HANDLING
1576 1871
1577In general, AnyEvent does not do any error handling - it relies on the 1872In general, AnyEvent does not do any error handling - it relies on the
1578caller to do that if required. The L<AnyEvent::Strict> module (see also 1873caller to do that if required. The L<AnyEvent::Strict> module (see also
1625check the arguments passed to most method calls. If it finds any problems, 1920check the arguments passed to most method calls. If it finds any problems,
1626it will croak. 1921it will croak.
1627 1922
1628In other words, enables "strict" mode. 1923In other words, enables "strict" mode.
1629 1924
1630Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense> 1925Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1631>>, it is definitely recommended to keep it off in production. Keeping 1926>>, it is definitely recommended to keep it off in production. Keeping
1632C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs 1927C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1633can be very useful, however. 1928can be very useful, however.
1634 1929
1635=item C<PERL_ANYEVENT_MODEL> 1930=item C<PERL_ANYEVENT_MODEL>
1641used as event model. If it fails to load AnyEvent will proceed with 1936used as event model. If it fails to load AnyEvent will proceed with
1642auto detection and -probing. 1937auto detection and -probing.
1643 1938
1644This functionality might change in future versions. 1939This functionality might change in future versions.
1645 1940
1646For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1941For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1647could start your program like this: 1942could start your program like this:
1648 1943
1649 PERL_ANYEVENT_MODEL=Perl perl ... 1944 PERL_ANYEVENT_MODEL=Perl perl ...
1650 1945
1651=item C<PERL_ANYEVENT_PROTOCOLS> 1946=item C<PERL_ANYEVENT_PROTOCOLS>
1772 warn "read: $input\n"; # output what has been read 2067 warn "read: $input\n"; # output what has been read
1773 $cv->send if $input =~ /^q/i; # quit program if /^q/i 2068 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1774 }, 2069 },
1775 ); 2070 );
1776 2071
1777 my $time_watcher; # can only be used once
1778
1779 sub new_timer {
1780 $timer = AnyEvent->timer (after => 1, cb => sub { 2072 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1781 warn "timeout\n"; # print 'timeout' about every second 2073 warn "timeout\n"; # print 'timeout' at most every second
1782 &new_timer; # and restart the time
1783 }); 2074 });
1784 }
1785
1786 new_timer; # create first timer
1787 2075
1788 $cv->recv; # wait until user enters /^q/i 2076 $cv->recv; # wait until user enters /^q/i
1789 2077
1790=head1 REAL-WORLD EXAMPLE 2078=head1 REAL-WORLD EXAMPLE
1791 2079
1864 2152
1865The actual code goes further and collects all errors (C<die>s, exceptions) 2153The actual code goes further and collects all errors (C<die>s, exceptions)
1866that occurred during request processing. The C<result> method detects 2154that occurred during request processing. The C<result> method detects
1867whether an exception as thrown (it is stored inside the $txn object) 2155whether an exception as thrown (it is stored inside the $txn object)
1868and just throws the exception, which means connection errors and other 2156and just throws the exception, which means connection errors and other
1869problems get reported tot he code that tries to use the result, not in a 2157problems get reported to the code that tries to use the result, not in a
1870random callback. 2158random callback.
1871 2159
1872All of this enables the following usage styles: 2160All of this enables the following usage styles:
1873 2161
18741. Blocking: 21621. Blocking:
1922through AnyEvent. The benchmark creates a lot of timers (with a zero 2210through AnyEvent. The benchmark creates a lot of timers (with a zero
1923timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 2211timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1924which it is), lets them fire exactly once and destroys them again. 2212which it is), lets them fire exactly once and destroys them again.
1925 2213
1926Source code for this benchmark is found as F<eg/bench> in the AnyEvent 2214Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1927distribution. 2215distribution. It uses the L<AE> interface, which makes a real difference
2216for the EV and Perl backends only.
1928 2217
1929=head3 Explanation of the columns 2218=head3 Explanation of the columns
1930 2219
1931I<watcher> is the number of event watchers created/destroyed. Since 2220I<watcher> is the number of event watchers created/destroyed. Since
1932different event models feature vastly different performances, each event 2221different event models feature vastly different performances, each event
1953watcher. 2242watcher.
1954 2243
1955=head3 Results 2244=head3 Results
1956 2245
1957 name watchers bytes create invoke destroy comment 2246 name watchers bytes create invoke destroy comment
1958 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 2247 EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1959 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 2248 EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1960 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 2249 Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1961 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 2250 Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1962 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 2251 Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1963 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 2252 Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1964 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll 2253 IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1965 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll 2254 IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1966 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 2255 Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1967 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 2256 Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1968 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 2257 POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1969 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 2258 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1970 2259
1971=head3 Discussion 2260=head3 Discussion
1972 2261
1973The benchmark does I<not> measure scalability of the event loop very 2262The benchmark does I<not> measure scalability of the event loop very
1974well. For example, a select-based event loop (such as the pure perl one) 2263well. For example, a select-based event loop (such as the pure perl one)
1986benchmark machine, handling an event takes roughly 1600 CPU cycles with 2275benchmark machine, handling an event takes roughly 1600 CPU cycles with
1987EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU 2276EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1988cycles with POE. 2277cycles with POE.
1989 2278
1990C<EV> is the sole leader regarding speed and memory use, which are both 2279C<EV> is the sole leader regarding speed and memory use, which are both
1991maximal/minimal, respectively. Even when going through AnyEvent, it uses 2280maximal/minimal, respectively. When using the L<AE> API there is zero
2281overhead (when going through the AnyEvent API create is about 5-6 times
2282slower, with other times being equal, so still uses far less memory than
1992far less memory than any other event loop and is still faster than Event 2283any other event loop and is still faster than Event natively).
1993natively.
1994 2284
1995The pure perl implementation is hit in a few sweet spots (both the 2285The pure perl implementation is hit in a few sweet spots (both the
1996constant timeout and the use of a single fd hit optimisations in the perl 2286constant timeout and the use of a single fd hit optimisations in the perl
1997interpreter and the backend itself). Nevertheless this shows that it 2287interpreter and the backend itself). Nevertheless this shows that it
1998adds very little overhead in itself. Like any select-based backend its 2288adds very little overhead in itself. Like any select-based backend its
2072In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 2362In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
2073(1%) are active. This mirrors the activity of large servers with many 2363(1%) are active. This mirrors the activity of large servers with many
2074connections, most of which are idle at any one point in time. 2364connections, most of which are idle at any one point in time.
2075 2365
2076Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 2366Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
2077distribution. 2367distribution. It uses the L<AE> interface, which makes a real difference
2368for the EV and Perl backends only.
2078 2369
2079=head3 Explanation of the columns 2370=head3 Explanation of the columns
2080 2371
2081I<sockets> is the number of sockets, and twice the number of "servers" (as 2372I<sockets> is the number of sockets, and twice the number of "servers" (as
2082each server has a read and write socket end). 2373each server has a read and write socket end).
2090a new one that moves the timeout into the future. 2381a new one that moves the timeout into the future.
2091 2382
2092=head3 Results 2383=head3 Results
2093 2384
2094 name sockets create request 2385 name sockets create request
2095 EV 20000 69.01 11.16 2386 EV 20000 62.66 7.99
2096 Perl 20000 73.32 35.87 2387 Perl 20000 68.32 32.64
2097 IOAsync 20000 157.00 98.14 epoll 2388 IOAsync 20000 174.06 101.15 epoll
2098 IOAsync 20000 159.31 616.06 poll 2389 IOAsync 20000 174.67 610.84 poll
2099 Event 20000 212.62 257.32 2390 Event 20000 202.69 242.91
2100 Glib 20000 651.16 1896.30 2391 Glib 20000 557.01 1689.52
2101 POE 20000 349.67 12317.24 uses POE::Loop::Event 2392 POE 20000 341.54 12086.32 uses POE::Loop::Event
2102 2393
2103=head3 Discussion 2394=head3 Discussion
2104 2395
2105This benchmark I<does> measure scalability and overall performance of the 2396This benchmark I<does> measure scalability and overall performance of the
2106particular event loop. 2397particular event loop.
2232As you can see, the AnyEvent + EV combination even beats the 2523As you can see, the AnyEvent + EV combination even beats the
2233hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 2524hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2234backend easily beats IO::Lambda and POE. 2525backend easily beats IO::Lambda and POE.
2235 2526
2236And even the 100% non-blocking version written using the high-level (and 2527And even the 100% non-blocking version written using the high-level (and
2237slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a 2528slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2238large margin, even though it does all of DNS, tcp-connect and socket I/O 2529higher level ("unoptimised") abstractions by a large margin, even though
2239in a non-blocking way. 2530it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2240 2531
2241The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and 2532The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2242F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are 2533F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2243part of the IO::lambda distribution and were used without any changes. 2534part of the IO::Lambda distribution and were used without any changes.
2244 2535
2245 2536
2246=head1 SIGNALS 2537=head1 SIGNALS
2247 2538
2248AnyEvent currently installs handlers for these signals: 2539AnyEvent currently installs handlers for these signals:
2285 unless defined $SIG{PIPE}; 2576 unless defined $SIG{PIPE};
2286 2577
2287=head1 RECOMMENDED/OPTIONAL MODULES 2578=head1 RECOMMENDED/OPTIONAL MODULES
2288 2579
2289One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and 2580One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2290it's built-in modules) are required to use it. 2581its built-in modules) are required to use it.
2291 2582
2292That does not mean that AnyEvent won't take advantage of some additional 2583That does not mean that AnyEvent won't take advantage of some additional
2293modules if they are installed. 2584modules if they are installed.
2294 2585
2295This section epxlains which additional modules will be used, and how they 2586This section explains which additional modules will be used, and how they
2296affect AnyEvent's operetion. 2587affect AnyEvent's operation.
2297 2588
2298=over 4 2589=over 4
2299 2590
2300=item L<Async::Interrupt> 2591=item L<Async::Interrupt>
2301 2592
2306catch the signals) with some delay (default is 10 seconds, look for 2597catch the signals) with some delay (default is 10 seconds, look for
2307C<$AnyEvent::MAX_SIGNAL_LATENCY>). 2598C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2308 2599
2309If this module is available, then it will be used to implement signal 2600If this module is available, then it will be used to implement signal
2310catching, which means that signals will not be delayed, and the event loop 2601catching, which means that signals will not be delayed, and the event loop
2311will not be interrupted regularly, which is more efficient (And good for 2602will not be interrupted regularly, which is more efficient (and good for
2312battery life on laptops). 2603battery life on laptops).
2313 2604
2314This affects not just the pure-perl event loop, but also other event loops 2605This affects not just the pure-perl event loop, but also other event loops
2315that have no signal handling on their own (e.g. Glib, Tk, Qt). 2606that have no signal handling on their own (e.g. Glib, Tk, Qt).
2316 2607
2328automatic timer adjustments even when no monotonic clock is available, 2619automatic timer adjustments even when no monotonic clock is available,
2329can take avdantage of advanced kernel interfaces such as C<epoll> and 2620can take avdantage of advanced kernel interfaces such as C<epoll> and
2330C<kqueue>, and is the fastest backend I<by far>. You can even embed 2621C<kqueue>, and is the fastest backend I<by far>. You can even embed
2331L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>). 2622L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2332 2623
2624If you only use backends that rely on another event loop (e.g. C<Tk>),
2625then this module will do nothing for you.
2626
2333=item L<Guard> 2627=item L<Guard>
2334 2628
2335The guard module, when used, will be used to implement 2629The guard module, when used, will be used to implement
2336C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a 2630C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2337lot less memory), but otherwise doesn't affect guard operation much. It is 2631lot less memory), but otherwise doesn't affect guard operation much. It is
2338purely used for performance. 2632purely used for performance.
2339 2633
2340=item L<JSON> and L<JSON::XS> 2634=item L<JSON> and L<JSON::XS>
2341 2635
2342This module is required when you want to read or write JSON data via 2636One of these modules is required when you want to read or write JSON data
2343L<AnyEvent::Handle>. It is also written in pure-perl, but can take 2637via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
2344advantage of the ultra-high-speed L<JSON::XS> module when it is installed. 2638advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2345
2346In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2347installed.
2348 2639
2349=item L<Net::SSLeay> 2640=item L<Net::SSLeay>
2350 2641
2351Implementing TLS/SSL in Perl is certainly interesting, but not very 2642Implementing TLS/SSL in Perl is certainly interesting, but not very
2352worthwhile: If this module is installed, then L<AnyEvent::Handle> (with 2643worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2353the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL. 2644the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2354 2645
2355=item L<Time::HiRes> 2646=item L<Time::HiRes>
2356 2647
2357This module is part of perl since release 5.008. It will be used when the 2648This module is part of perl since release 5.008. It will be used when the
2358chosen event library does not come with a timing source on it's own. The 2649chosen event library does not come with a timing source of its own. The
2359pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to 2650pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
2360try to use a monotonic clock for timing stability. 2651try to use a monotonic clock for timing stability.
2361 2652
2362=back 2653=back
2363 2654
2364 2655
2365=head1 FORK 2656=head1 FORK
2366 2657
2367Most event libraries are not fork-safe. The ones who are usually are 2658Most event libraries are not fork-safe. The ones who are usually are
2368because they rely on inefficient but fork-safe C<select> or C<poll> 2659because they rely on inefficient but fork-safe C<select> or C<poll> calls
2369calls. Only L<EV> is fully fork-aware. 2660- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
2661are usually badly thought-out hacks that are incompatible with fork in
2662one way or another. Only L<EV> is fully fork-aware and ensures that you
2663continue event-processing in both parent and child (or both, if you know
2664what you are doing).
2665
2666This means that, in general, you cannot fork and do event processing in
2667the child if the event library was initialised before the fork (which
2668usually happens when the first AnyEvent watcher is created, or the library
2669is loaded).
2370 2670
2371If you have to fork, you must either do so I<before> creating your first 2671If you have to fork, you must either do so I<before> creating your first
2372watcher OR you must not use AnyEvent at all in the child OR you must do 2672watcher OR you must not use AnyEvent at all in the child OR you must do
2373something completely out of the scope of AnyEvent. 2673something completely out of the scope of AnyEvent.
2674
2675The problem of doing event processing in the parent I<and> the child
2676is much more complicated: even for backends that I<are> fork-aware or
2677fork-safe, their behaviour is not usually what you want: fork clones all
2678watchers, that means all timers, I/O watchers etc. are active in both
2679parent and child, which is almost never what you want. USing C<exec>
2680to start worker children from some kind of manage rprocess is usually
2681preferred, because it is much easier and cleaner, at the expense of having
2682to have another binary.
2374 2683
2375 2684
2376=head1 SECURITY CONSIDERATIONS 2685=head1 SECURITY CONSIDERATIONS
2377 2686
2378AnyEvent can be forced to load any event model via 2687AnyEvent can be forced to load any event model via
2408pronounced). 2717pronounced).
2409 2718
2410 2719
2411=head1 SEE ALSO 2720=head1 SEE ALSO
2412 2721
2722Tutorial/Introduction: L<AnyEvent::Intro>.
2723
2724FAQ: L<AnyEvent::FAQ>.
2725
2413Utility functions: L<AnyEvent::Util>. 2726Utility functions: L<AnyEvent::Util>.
2414 2727
2415Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 2728Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2416L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2729L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2417 2730
2418Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2731Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2419L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2732L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2420L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2733L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2421L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>. 2734L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2422 2735
2423Non-blocking file handles, sockets, TCP clients and 2736Non-blocking file handles, sockets, TCP clients and
2424servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>. 2737servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2425 2738
2426Asynchronous DNS: L<AnyEvent::DNS>. 2739Asynchronous DNS: L<AnyEvent::DNS>.
2427 2740
2428Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, 2741Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2429L<Coro::Event>,
2430 2742
2431Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>, 2743Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2432L<AnyEvent::HTTP>. 2744L<AnyEvent::HTTP>.
2433 2745
2434 2746
2435=head1 AUTHOR 2747=head1 AUTHOR
2436 2748

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