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1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's
20 $w->wait; # enters "main loop" till $condvar gets ->broadcast 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->broadcast; # wake up current and all future wait's 22
23=head1 INTRODUCTION/TUTORIAL
24
25This manpage is mainly a reference manual. If you are interested
26in a tutorial or some gentle introduction, have a look at the
27L<AnyEvent::Intro> manpage.
22 28
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 29=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 30
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 31Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 32nowadays. So what is different about AnyEvent?
27 33
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 34Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>. 35policy> and AnyEvent is I<small and efficient>.
30 36
31First and foremost, I<AnyEvent is not an event model> itself, it only 37First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a 38interfaces to whatever event model the main program happens to use, in a
33pragmatic way. For event models and certain classes of immortals alike, 39pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality: In general, 40the statement "there can only be one" is a bitter reality: In general,
35only one event loop can be active at the same time in a process. AnyEvent 41only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops. 42cannot change this, but it can hide the differences between those event
43loops.
37 44
38The goal of AnyEvent is to offer module authors the ability to do event 45The goal of AnyEvent is to offer module authors the ability to do event
39programming (waiting for I/O or timer events) without subscribing to a 46programming (waiting for I/O or timer events) without subscribing to a
40religion, a way of living, and most importantly: without forcing your 47religion, a way of living, and most importantly: without forcing your
41module users into the same thing by forcing them to use the same event 48module users into the same thing by forcing them to use the same event
42model you use. 49model you use.
43 50
44For modules like POE or IO::Async (which is a total misnomer as it is 51For modules like POE or IO::Async (which is a total misnomer as it is
45actually doing all I/O I<synchronously>...), using them in your module is 52actually doing all I/O I<synchronously>...), using them in your module is
46like joining a cult: After you joined, you are dependent on them and you 53like joining a cult: After you joined, you are dependent on them and you
47cannot use anything else, as it is simply incompatible to everything that 54cannot use anything else, as they are simply incompatible to everything
48isn't itself. What's worse, all the potential users of your module are 55that isn't them. What's worse, all the potential users of your
49I<also> forced to use the same event loop you use. 56module are I<also> forced to use the same event loop you use.
50 57
51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 58AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52fine. AnyEvent + Tk works fine etc. etc. but none of these work together 59fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if 60with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54your module uses one of those, every user of your module has to use it, 61your module uses one of those, every user of your module has to use it,
55too. But if your module uses AnyEvent, it works transparently with all 62too. But if your module uses AnyEvent, it works transparently with all
56event models it supports (including stuff like POE and IO::Async, as long 63event models it supports (including stuff like IO::Async, as long as those
57as those use one of the supported event loops. It is trivial to add new 64use one of the supported event loops. It is trivial to add new event loops
58event loops to AnyEvent, too, so it is future-proof). 65to AnyEvent, too, so it is future-proof).
59 66
60In addition to being free of having to use I<the one and only true event 67In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 68model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enourmous amount of code and strict rules you have to 69modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 70follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as 71offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 72technically possible.
66 73
74Of course, AnyEvent comes with a big (and fully optional!) toolbox
75of useful functionality, such as an asynchronous DNS resolver, 100%
76non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
77such as Windows) and lots of real-world knowledge and workarounds for
78platform bugs and differences.
79
67Of course, if you want lots of policy (this can arguably be somewhat 80Now, if you I<do want> lots of policy (this can arguably be somewhat
68useful) and you want to force your users to use the one and only event 81useful) and you want to force your users to use the one and only event
69model, you should I<not> use this module. 82model, you should I<not> use this module.
70 83
71=head1 DESCRIPTION 84=head1 DESCRIPTION
72 85
78The interface itself is vaguely similar, but not identical to the L<Event> 91The interface itself is vaguely similar, but not identical to the L<Event>
79module. 92module.
80 93
81During the first call of any watcher-creation method, the module tries 94During the first call of any watcher-creation method, the module tries
82to detect the currently loaded event loop by probing whether one of the 95to detect the currently loaded event loop by probing whether one of the
83following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, 96following modules is already loaded: L<EV>,
84L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, 97L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85L<POE>. The first one found is used. If none are found, the module tries 98L<POE>. The first one found is used. If none are found, the module tries
86to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl 99to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87adaptor should always succeed) in the order given. The first one that can 100adaptor should always succeed) in the order given. The first one that can
88be successfully loaded will be used. If, after this, still none could be 101be successfully loaded will be used. If, after this, still none could be
102starts using it, all bets are off. Maybe you should tell their authors to 115starts using it, all bets are off. Maybe you should tell their authors to
103use AnyEvent so their modules work together with others seamlessly... 116use AnyEvent so their modules work together with others seamlessly...
104 117
105The pure-perl implementation of AnyEvent is called 118The pure-perl implementation of AnyEvent is called
106C<AnyEvent::Impl::Perl>. Like other event modules you can load it 119C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107explicitly. 120explicitly and enjoy the high availability of that event loop :)
108 121
109=head1 WATCHERS 122=head1 WATCHERS
110 123
111AnyEvent has the central concept of a I<watcher>, which is an object that 124AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 125stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 126the callback to call, the file handle to watch, etc.
114 127
115These watchers are normal Perl objects with normal Perl lifetime. After 128These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 129creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 130callback when the event occurs (of course, only when the event model
118is in control). 131is in control).
126Many watchers either are used with "recursion" (repeating timers for 139Many watchers either are used with "recursion" (repeating timers for
127example), or need to refer to their watcher object in other ways. 140example), or need to refer to their watcher object in other ways.
128 141
129An any way to achieve that is this pattern: 142An any way to achieve that is this pattern:
130 143
131 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 144 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132 # you can use $w here, for example to undef it 145 # you can use $w here, for example to undef it
133 undef $w; 146 undef $w;
134 }); 147 });
135 148
136Note that C<my $w; $w => combination. This is necessary because in Perl, 149Note that C<my $w; $w => combination. This is necessary because in Perl,
137my variables are only visible after the statement in which they are 150my variables are only visible after the statement in which they are
138declared. 151declared.
139 152
140=head2 I/O WATCHERS 153=head2 I/O WATCHERS
141 154
142You can create an I/O watcher by calling the C<< AnyEvent->io >> method 155You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143with the following mandatory key-value pairs as arguments: 156with the following mandatory key-value pairs as arguments:
144 157
145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch 158C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
146for events. C<poll> must be a string that is either C<r> or C<w>, 159(AnyEvent might or might not keep a reference to this file handle). C<poll>
147which creates a watcher waiting for "r"eadable or "w"ritable events, 160must be a string that is either C<r> or C<w>, which creates a watcher
148respectively. C<cb> is the callback to invoke each time the file handle 161waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149becomes ready. 162callback to invoke each time the file handle becomes ready.
150 163
151Although the callback might get passed parameters, their value and 164Although the callback might get passed parameters, their value and
152presence is undefined and you cannot rely on them. Portable AnyEvent 165presence is undefined and you cannot rely on them. Portable AnyEvent
153callbacks cannot use arguments passed to I/O watcher callbacks. 166callbacks cannot use arguments passed to I/O watcher callbacks.
154 167
158 171
159Some event loops issue spurious readyness notifications, so you should 172Some event loops issue spurious readyness notifications, so you should
160always use non-blocking calls when reading/writing from/to your file 173always use non-blocking calls when reading/writing from/to your file
161handles. 174handles.
162 175
163Example:
164
165 # wait for readability of STDIN, then read a line and disable the watcher 176Example: wait for readability of STDIN, then read a line and disable the
177watcher.
178
166 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 179 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167 chomp (my $input = <STDIN>); 180 chomp (my $input = <STDIN>);
168 warn "read: $input\n"; 181 warn "read: $input\n";
169 undef $w; 182 undef $w;
170 }); 183 });
180 193
181Although the callback might get passed parameters, their value and 194Although the callback might get passed parameters, their value and
182presence is undefined and you cannot rely on them. Portable AnyEvent 195presence is undefined and you cannot rely on them. Portable AnyEvent
183callbacks cannot use arguments passed to time watcher callbacks. 196callbacks cannot use arguments passed to time watcher callbacks.
184 197
185The timer callback will be invoked at most once: if you want a repeating 198The callback will normally be invoked once only. If you specify another
186timer you have to create a new watcher (this is a limitation by both Tk 199parameter, C<interval>, as a strictly positive number (> 0), then the
187and Glib). 200callback will be invoked regularly at that interval (in fractional
201seconds) after the first invocation. If C<interval> is specified with a
202false value, then it is treated as if it were missing.
188 203
189Example: 204The callback will be rescheduled before invoking the callback, but no
205attempt is done to avoid timer drift in most backends, so the interval is
206only approximate.
190 207
191 # fire an event after 7.7 seconds 208Example: fire an event after 7.7 seconds.
209
192 my $w = AnyEvent->timer (after => 7.7, cb => sub { 210 my $w = AnyEvent->timer (after => 7.7, cb => sub {
193 warn "timeout\n"; 211 warn "timeout\n";
194 }); 212 });
195 213
196 # to cancel the timer: 214 # to cancel the timer:
197 undef $w; 215 undef $w;
198 216
199Example 2:
200
201 # fire an event after 0.5 seconds, then roughly every second 217Example 2: fire an event after 0.5 seconds, then roughly every second.
202 my $w;
203 218
204 my $cb = sub {
205 # cancel the old timer while creating a new one
206 $w = AnyEvent->timer (after => 1, cb => $cb); 219 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
220 warn "timeout\n";
207 }; 221 };
208
209 # start the "loop" by creating the first watcher
210 $w = AnyEvent->timer (after => 0.5, cb => $cb);
211 222
212=head3 TIMING ISSUES 223=head3 TIMING ISSUES
213 224
214There are two ways to handle timers: based on real time (relative, "fire 225There are two ways to handle timers: based on real time (relative, "fire
215in 10 seconds") and based on wallclock time (absolute, "fire at 12 226in 10 seconds") and based on wallclock time (absolute, "fire at 12
227timers. 238timers.
228 239
229AnyEvent always prefers relative timers, if available, matching the 240AnyEvent always prefers relative timers, if available, matching the
230AnyEvent API. 241AnyEvent API.
231 242
243AnyEvent has two additional methods that return the "current time":
244
245=over 4
246
247=item AnyEvent->time
248
249This returns the "current wallclock time" as a fractional number of
250seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
251return, and the result is guaranteed to be compatible with those).
252
253It progresses independently of any event loop processing, i.e. each call
254will check the system clock, which usually gets updated frequently.
255
256=item AnyEvent->now
257
258This also returns the "current wallclock time", but unlike C<time>, above,
259this value might change only once per event loop iteration, depending on
260the event loop (most return the same time as C<time>, above). This is the
261time that AnyEvent's timers get scheduled against.
262
263I<In almost all cases (in all cases if you don't care), this is the
264function to call when you want to know the current time.>
265
266This function is also often faster then C<< AnyEvent->time >>, and
267thus the preferred method if you want some timestamp (for example,
268L<AnyEvent::Handle> uses this to update it's activity timeouts).
269
270The rest of this section is only of relevance if you try to be very exact
271with your timing, you can skip it without bad conscience.
272
273For a practical example of when these times differ, consider L<Event::Lib>
274and L<EV> and the following set-up:
275
276The event loop is running and has just invoked one of your callback at
277time=500 (assume no other callbacks delay processing). In your callback,
278you wait a second by executing C<sleep 1> (blocking the process for a
279second) and then (at time=501) you create a relative timer that fires
280after three seconds.
281
282With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
283both return C<501>, because that is the current time, and the timer will
284be scheduled to fire at time=504 (C<501> + C<3>).
285
286With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
287time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
288last event processing phase started. With L<EV>, your timer gets scheduled
289to run at time=503 (C<500> + C<3>).
290
291In one sense, L<Event::Lib> is more exact, as it uses the current time
292regardless of any delays introduced by event processing. However, most
293callbacks do not expect large delays in processing, so this causes a
294higher drift (and a lot more system calls to get the current time).
295
296In another sense, L<EV> is more exact, as your timer will be scheduled at
297the same time, regardless of how long event processing actually took.
298
299In either case, if you care (and in most cases, you don't), then you
300can get whatever behaviour you want with any event loop, by taking the
301difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
302account.
303
304=back
305
232=head2 SIGNAL WATCHERS 306=head2 SIGNAL WATCHERS
233 307
234You can watch for signals using a signal watcher, C<signal> is the signal 308You can watch for signals using a signal watcher, C<signal> is the signal
235I<name> without any C<SIG> prefix, C<cb> is the Perl callback to 309I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236be invoked whenever a signal occurs. 310callback to be invoked whenever a signal occurs.
237 311
238Although the callback might get passed parameters, their value and 312Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 313presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 314callbacks cannot use arguments passed to signal watcher callbacks.
241 315
242Multiple signal occurances can be clumped together into one callback 316Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 317invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 318that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 319but it is guaranteed not to interrupt any other callbacks.
246 320
247The main advantage of using these watchers is that you can share a signal 321The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 322between multiple watchers.
249 323
250This watcher might use C<%SIG>, so programs overwriting those signals 324This watcher might use C<%SIG>, so programs overwriting those signals
277AnyEvent program, you I<have> to create at least one watcher before you 351AnyEvent program, you I<have> to create at least one watcher before you
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 352C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 353
280Example: fork a process and wait for it 354Example: fork a process and wait for it
281 355
282 my $done = AnyEvent->condvar; 356 my $done = AnyEvent->condvar;
283 357
284 AnyEvent::detect; # force event module to be initialised
285
286 my $pid = fork or exit 5; 358 my $pid = fork or exit 5;
287 359
288 my $w = AnyEvent->child ( 360 my $w = AnyEvent->child (
289 pid => $pid, 361 pid => $pid,
290 cb => sub { 362 cb => sub {
291 my ($pid, $status) = @_; 363 my ($pid, $status) = @_;
292 warn "pid $pid exited with status $status"; 364 warn "pid $pid exited with status $status";
293 $done->broadcast; 365 $done->send;
294 }, 366 },
295 ); 367 );
296 368
297 # do something else, then wait for process exit 369 # do something else, then wait for process exit
298 $done->wait; 370 $done->recv;
299 371
300=head2 CONDITION VARIABLES 372=head2 CONDITION VARIABLES
301 373
374If you are familiar with some event loops you will know that all of them
375require you to run some blocking "loop", "run" or similar function that
376will actively watch for new events and call your callbacks.
377
378AnyEvent is different, it expects somebody else to run the event loop and
379will only block when necessary (usually when told by the user).
380
381The instrument to do that is called a "condition variable", so called
382because they represent a condition that must become true.
383
302Condition variables can be created by calling the C<< AnyEvent->condvar >> 384Condition variables can be created by calling the C<< AnyEvent->condvar
303method without any arguments. 385>> method, usually without arguments. The only argument pair allowed is
386C<cb>, which specifies a callback to be called when the condition variable
387becomes true.
304 388
305A condition variable waits for a condition - precisely that the C<< 389After creation, the condition variable is "false" until it becomes "true"
306->broadcast >> method has been called. 390by calling the C<send> method (or calling the condition variable as if it
391were a callback, read about the caveats in the description for the C<<
392->send >> method).
307 393
308They are very useful to signal that a condition has been fulfilled, for 394Condition variables are similar to callbacks, except that you can
395optionally wait for them. They can also be called merge points - points
396in time where multiple outstanding events have been processed. And yet
397another way to call them is transactions - each condition variable can be
398used to represent a transaction, which finishes at some point and delivers
399a result.
400
401Condition variables are very useful to signal that something has finished,
309example, if you write a module that does asynchronous http requests, 402for example, if you write a module that does asynchronous http requests,
310then a condition variable would be the ideal candidate to signal the 403then a condition variable would be the ideal candidate to signal the
311availability of results. 404availability of results. The user can either act when the callback is
405called or can synchronously C<< ->recv >> for the results.
312 406
313You can also use condition variables to block your main program until 407You can also use them to simulate traditional event loops - for example,
314an event occurs - for example, you could C<< ->wait >> in your main 408you can block your main program until an event occurs - for example, you
315program until the user clicks the Quit button in your app, which would C<< 409could C<< ->recv >> in your main program until the user clicks the Quit
316->broadcast >> the "quit" event. 410button of your app, which would C<< ->send >> the "quit" event.
317 411
318Note that condition variables recurse into the event loop - if you have 412Note that condition variables recurse into the event loop - if you have
319two pirces of code that call C<< ->wait >> in a round-robbin fashion, you 413two pieces of code that call C<< ->recv >> in a round-robin fashion, you
320lose. Therefore, condition variables are good to export to your caller, but 414lose. Therefore, condition variables are good to export to your caller, but
321you should avoid making a blocking wait yourself, at least in callbacks, 415you should avoid making a blocking wait yourself, at least in callbacks,
322as this asks for trouble. 416as this asks for trouble.
323 417
324This object has two methods: 418Condition variables are represented by hash refs in perl, and the keys
419used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
420easy (it is often useful to build your own transaction class on top of
421AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
422it's C<new> method in your own C<new> method.
423
424There are two "sides" to a condition variable - the "producer side" which
425eventually calls C<< -> send >>, and the "consumer side", which waits
426for the send to occur.
427
428Example: wait for a timer.
429
430 # wait till the result is ready
431 my $result_ready = AnyEvent->condvar;
432
433 # do something such as adding a timer
434 # or socket watcher the calls $result_ready->send
435 # when the "result" is ready.
436 # in this case, we simply use a timer:
437 my $w = AnyEvent->timer (
438 after => 1,
439 cb => sub { $result_ready->send },
440 );
441
442 # this "blocks" (while handling events) till the callback
443 # calls send
444 $result_ready->recv;
445
446Example: wait for a timer, but take advantage of the fact that
447condition variables are also code references.
448
449 my $done = AnyEvent->condvar;
450 my $delay = AnyEvent->timer (after => 5, cb => $done);
451 $done->recv;
452
453=head3 METHODS FOR PRODUCERS
454
455These methods should only be used by the producing side, i.e. the
456code/module that eventually sends the signal. Note that it is also
457the producer side which creates the condvar in most cases, but it isn't
458uncommon for the consumer to create it as well.
325 459
326=over 4 460=over 4
327 461
462=item $cv->send (...)
463
464Flag the condition as ready - a running C<< ->recv >> and all further
465calls to C<recv> will (eventually) return after this method has been
466called. If nobody is waiting the send will be remembered.
467
468If a callback has been set on the condition variable, it is called
469immediately from within send.
470
471Any arguments passed to the C<send> call will be returned by all
472future C<< ->recv >> calls.
473
474Condition variables are overloaded so one can call them directly
475(as a code reference). Calling them directly is the same as calling
476C<send>. Note, however, that many C-based event loops do not handle
477overloading, so as tempting as it may be, passing a condition variable
478instead of a callback does not work. Both the pure perl and EV loops
479support overloading, however, as well as all functions that use perl to
480invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
481example).
482
483=item $cv->croak ($error)
484
485Similar to send, but causes all call's to C<< ->recv >> to invoke
486C<Carp::croak> with the given error message/object/scalar.
487
488This can be used to signal any errors to the condition variable
489user/consumer.
490
491=item $cv->begin ([group callback])
492
328=item $cv->wait 493=item $cv->end
329 494
330Wait (blocking if necessary) until the C<< ->broadcast >> method has been 495These two methods are EXPERIMENTAL and MIGHT CHANGE.
496
497These two methods can be used to combine many transactions/events into
498one. For example, a function that pings many hosts in parallel might want
499to use a condition variable for the whole process.
500
501Every call to C<< ->begin >> will increment a counter, and every call to
502C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
503>>, the (last) callback passed to C<begin> will be executed. That callback
504is I<supposed> to call C<< ->send >>, but that is not required. If no
505callback was set, C<send> will be called without any arguments.
506
507Let's clarify this with the ping example:
508
509 my $cv = AnyEvent->condvar;
510
511 my %result;
512 $cv->begin (sub { $cv->send (\%result) });
513
514 for my $host (@list_of_hosts) {
515 $cv->begin;
516 ping_host_then_call_callback $host, sub {
517 $result{$host} = ...;
518 $cv->end;
519 };
520 }
521
522 $cv->end;
523
524This code fragment supposedly pings a number of hosts and calls
525C<send> after results for all then have have been gathered - in any
526order. To achieve this, the code issues a call to C<begin> when it starts
527each ping request and calls C<end> when it has received some result for
528it. Since C<begin> and C<end> only maintain a counter, the order in which
529results arrive is not relevant.
530
531There is an additional bracketing call to C<begin> and C<end> outside the
532loop, which serves two important purposes: first, it sets the callback
533to be called once the counter reaches C<0>, and second, it ensures that
534C<send> is called even when C<no> hosts are being pinged (the loop
535doesn't execute once).
536
537This is the general pattern when you "fan out" into multiple subrequests:
538use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
539is called at least once, and then, for each subrequest you start, call
540C<begin> and for each subrequest you finish, call C<end>.
541
542=back
543
544=head3 METHODS FOR CONSUMERS
545
546These methods should only be used by the consuming side, i.e. the
547code awaits the condition.
548
549=over 4
550
551=item $cv->recv
552
553Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331called on c<$cv>, while servicing other watchers normally. 554>> methods have been called on c<$cv>, while servicing other watchers
555normally.
332 556
333You can only wait once on a condition - additional calls will return 557You can only wait once on a condition - additional calls are valid but
334immediately. 558will return immediately.
559
560If an error condition has been set by calling C<< ->croak >>, then this
561function will call C<croak>.
562
563In list context, all parameters passed to C<send> will be returned,
564in scalar context only the first one will be returned.
335 565
336Not all event models support a blocking wait - some die in that case 566Not all event models support a blocking wait - some die in that case
337(programs might want to do that to stay interactive), so I<if you are 567(programs might want to do that to stay interactive), so I<if you are
338using this from a module, never require a blocking wait>, but let the 568using this from a module, never require a blocking wait>, but let the
339caller decide whether the call will block or not (for example, by coupling 569caller decide whether the call will block or not (for example, by coupling
340condition variables with some kind of request results and supporting 570condition variables with some kind of request results and supporting
341callbacks so the caller knows that getting the result will not block, 571callbacks so the caller knows that getting the result will not block,
342while still suppporting blocking waits if the caller so desires). 572while still supporting blocking waits if the caller so desires).
343 573
344Another reason I<never> to C<< ->wait >> in a module is that you cannot 574Another reason I<never> to C<< ->recv >> in a module is that you cannot
345sensibly have two C<< ->wait >>'s in parallel, as that would require 575sensibly have two C<< ->recv >>'s in parallel, as that would require
346multiple interpreters or coroutines/threads, none of which C<AnyEvent> 576multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 577can supply.
348L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349from different coroutines, however).
350 578
351=item $cv->broadcast 579The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
580fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
581versions and also integrates coroutines into AnyEvent, making blocking
582C<< ->recv >> calls perfectly safe as long as they are done from another
583coroutine (one that doesn't run the event loop).
352 584
353Flag the condition as ready - a running C<< ->wait >> and all further 585You can ensure that C<< -recv >> never blocks by setting a callback and
354calls to C<wait> will (eventually) return after this method has been 586only calling C<< ->recv >> from within that callback (or at a later
355called. If nobody is waiting the broadcast will be remembered.. 587time). This will work even when the event loop does not support blocking
588waits otherwise.
589
590=item $bool = $cv->ready
591
592Returns true when the condition is "true", i.e. whether C<send> or
593C<croak> have been called.
594
595=item $cb = $cv->cb ([new callback])
596
597This is a mutator function that returns the callback set and optionally
598replaces it before doing so.
599
600The callback will be called when the condition becomes "true", i.e. when
601C<send> or C<croak> are called, with the only argument being the condition
602variable itself. Calling C<recv> inside the callback or at any later time
603is guaranteed not to block.
356 604
357=back 605=back
358
359Example:
360
361 # wait till the result is ready
362 my $result_ready = AnyEvent->condvar;
363
364 # do something such as adding a timer
365 # or socket watcher the calls $result_ready->broadcast
366 # when the "result" is ready.
367 # in this case, we simply use a timer:
368 my $w = AnyEvent->timer (
369 after => 1,
370 cb => sub { $result_ready->broadcast },
371 );
372
373 # this "blocks" (while handling events) till the watcher
374 # calls broadcast
375 $result_ready->wait;
376 606
377=head1 GLOBAL VARIABLES AND FUNCTIONS 607=head1 GLOBAL VARIABLES AND FUNCTIONS
378 608
379=over 4 609=over 4
380 610
386C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 616C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 617AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388 618
389The known classes so far are: 619The known classes so far are:
390 620
391 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 621 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394 AnyEvent::Impl::Event based on Event, second best choice. 622 AnyEvent::Impl::Event based on Event, second best choice.
623 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395 AnyEvent::Impl::Glib based on Glib, third-best choice. 624 AnyEvent::Impl::Glib based on Glib, third-best choice.
396 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397 AnyEvent::Impl::Tk based on Tk, very bad choice. 625 AnyEvent::Impl::Tk based on Tk, very bad choice.
398 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 626 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 627 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400 AnyEvent::Impl::POE based on POE, not generic enough for full support. 628 AnyEvent::Impl::POE based on POE, not generic enough for full support.
401 629
414Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 642Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415if necessary. You should only call this function right before you would 643if necessary. You should only call this function right before you would
416have created an AnyEvent watcher anyway, that is, as late as possible at 644have created an AnyEvent watcher anyway, that is, as late as possible at
417runtime. 645runtime.
418 646
647=item $guard = AnyEvent::post_detect { BLOCK }
648
649Arranges for the code block to be executed as soon as the event model is
650autodetected (or immediately if this has already happened).
651
652If called in scalar or list context, then it creates and returns an object
653that automatically removes the callback again when it is destroyed. See
654L<Coro::BDB> for a case where this is useful.
655
656=item @AnyEvent::post_detect
657
658If there are any code references in this array (you can C<push> to it
659before or after loading AnyEvent), then they will called directly after
660the event loop has been chosen.
661
662You should check C<$AnyEvent::MODEL> before adding to this array, though:
663if it contains a true value then the event loop has already been detected,
664and the array will be ignored.
665
666Best use C<AnyEvent::post_detect { BLOCK }> instead.
667
419=back 668=back
420 669
421=head1 WHAT TO DO IN A MODULE 670=head1 WHAT TO DO IN A MODULE
422 671
423As a module author, you should C<use AnyEvent> and call AnyEvent methods 672As a module author, you should C<use AnyEvent> and call AnyEvent methods
426Be careful when you create watchers in the module body - AnyEvent will 675Be careful when you create watchers in the module body - AnyEvent will
427decide which event module to use as soon as the first method is called, so 676decide which event module to use as soon as the first method is called, so
428by calling AnyEvent in your module body you force the user of your module 677by calling AnyEvent in your module body you force the user of your module
429to load the event module first. 678to load the event module first.
430 679
431Never call C<< ->wait >> on a condition variable unless you I<know> that 680Never call C<< ->recv >> on a condition variable unless you I<know> that
432the C<< ->broadcast >> method has been called on it already. This is 681the C<< ->send >> method has been called on it already. This is
433because it will stall the whole program, and the whole point of using 682because it will stall the whole program, and the whole point of using
434events is to stay interactive. 683events is to stay interactive.
435 684
436It is fine, however, to call C<< ->wait >> when the user of your module 685It is fine, however, to call C<< ->recv >> when the user of your module
437requests it (i.e. if you create a http request object ad have a method 686requests it (i.e. if you create a http request object ad have a method
438called C<results> that returns the results, it should call C<< ->wait >> 687called C<results> that returns the results, it should call C<< ->recv >>
439freely, as the user of your module knows what she is doing. always). 688freely, as the user of your module knows what she is doing. always).
440 689
441=head1 WHAT TO DO IN THE MAIN PROGRAM 690=head1 WHAT TO DO IN THE MAIN PROGRAM
442 691
443There will always be a single main program - the only place that should 692There will always be a single main program - the only place that should
445 694
446If it doesn't care, it can just "use AnyEvent" and use it itself, or not 695If it doesn't care, it can just "use AnyEvent" and use it itself, or not
447do anything special (it does not need to be event-based) and let AnyEvent 696do anything special (it does not need to be event-based) and let AnyEvent
448decide which implementation to chose if some module relies on it. 697decide which implementation to chose if some module relies on it.
449 698
450If the main program relies on a specific event model. For example, in 699If the main program relies on a specific event model - for example, in
451Gtk2 programs you have to rely on the Glib module. You should load the 700Gtk2 programs you have to rely on the Glib module - you should load the
452event module before loading AnyEvent or any module that uses it: generally 701event module before loading AnyEvent or any module that uses it: generally
453speaking, you should load it as early as possible. The reason is that 702speaking, you should load it as early as possible. The reason is that
454modules might create watchers when they are loaded, and AnyEvent will 703modules might create watchers when they are loaded, and AnyEvent will
455decide on the event model to use as soon as it creates watchers, and it 704decide on the event model to use as soon as it creates watchers, and it
456might chose the wrong one unless you load the correct one yourself. 705might chose the wrong one unless you load the correct one yourself.
457 706
458You can chose to use a rather inefficient pure-perl implementation by 707You can chose to use a pure-perl implementation by loading the
459loading the C<AnyEvent::Impl::Perl> module, which gives you similar 708C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460behaviour everywhere, but letting AnyEvent chose is generally better. 709everywhere, but letting AnyEvent chose the model is generally better.
710
711=head2 MAINLOOP EMULATION
712
713Sometimes (often for short test scripts, or even standalone programs who
714only want to use AnyEvent), you do not want to run a specific event loop.
715
716In that case, you can use a condition variable like this:
717
718 AnyEvent->condvar->recv;
719
720This has the effect of entering the event loop and looping forever.
721
722Note that usually your program has some exit condition, in which case
723it is better to use the "traditional" approach of storing a condition
724variable somewhere, waiting for it, and sending it when the program should
725exit cleanly.
726
461 727
462=head1 OTHER MODULES 728=head1 OTHER MODULES
463 729
464The following is a non-exhaustive list of additional modules that use 730The following is a non-exhaustive list of additional modules that use
465AnyEvent and can therefore be mixed easily with other AnyEvent modules 731AnyEvent and can therefore be mixed easily with other AnyEvent modules
471=item L<AnyEvent::Util> 737=item L<AnyEvent::Util>
472 738
473Contains various utility functions that replace often-used but blocking 739Contains various utility functions that replace often-used but blocking
474functions such as C<inet_aton> by event-/callback-based versions. 740functions such as C<inet_aton> by event-/callback-based versions.
475 741
742=item L<AnyEvent::Socket>
743
744Provides various utility functions for (internet protocol) sockets,
745addresses and name resolution. Also functions to create non-blocking tcp
746connections or tcp servers, with IPv6 and SRV record support and more.
747
476=item L<AnyEvent::Handle> 748=item L<AnyEvent::Handle>
477 749
478Provide read and write buffers and manages watchers for reads and writes. 750Provide read and write buffers, manages watchers for reads and writes,
751supports raw and formatted I/O, I/O queued and fully transparent and
752non-blocking SSL/TLS.
479 753
480=item L<AnyEvent::Socket> 754=item L<AnyEvent::DNS>
481 755
482Provides a means to do non-blocking connects, accepts etc. 756Provides rich asynchronous DNS resolver capabilities.
757
758=item L<AnyEvent::HTTP>
759
760A simple-to-use HTTP library that is capable of making a lot of concurrent
761HTTP requests.
483 762
484=item L<AnyEvent::HTTPD> 763=item L<AnyEvent::HTTPD>
485 764
486Provides a simple web application server framework. 765Provides a simple web application server framework.
487 766
488=item L<AnyEvent::DNS>
489
490Provides asynchronous DNS resolver capabilities, beyond what
491L<AnyEvent::Util> offers.
492
493=item L<AnyEvent::FastPing> 767=item L<AnyEvent::FastPing>
494 768
495The fastest ping in the west. 769The fastest ping in the west.
770
771=item L<AnyEvent::DBI>
772
773Executes L<DBI> requests asynchronously in a proxy process.
774
775=item L<AnyEvent::AIO>
776
777Truly asynchronous I/O, should be in the toolbox of every event
778programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
779together.
780
781=item L<AnyEvent::BDB>
782
783Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
784L<BDB> and AnyEvent together.
785
786=item L<AnyEvent::GPSD>
787
788A non-blocking interface to gpsd, a daemon delivering GPS information.
789
790=item L<AnyEvent::IGS>
791
792A non-blocking interface to the Internet Go Server protocol (used by
793L<App::IGS>).
496 794
497=item L<Net::IRC3> 795=item L<Net::IRC3>
498 796
499AnyEvent based IRC client module family. 797AnyEvent based IRC client module family.
500 798
511 809
512High level API for event-based execution flow control. 810High level API for event-based execution flow control.
513 811
514=item L<Coro> 812=item L<Coro>
515 813
516Has special support for AnyEvent. 814Has special support for AnyEvent via L<Coro::AnyEvent>.
517 815
518=item L<IO::Lambda> 816=item L<IO::Lambda>
519 817
520The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 818The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521
522=item L<IO::AIO>
523
524Truly asynchronous I/O, should be in the toolbox of every event
525programmer. Can be trivially made to use AnyEvent.
526
527=item L<BDB>
528
529Truly asynchronous Berkeley DB access. Can be trivially made to use
530AnyEvent.
531 819
532=back 820=back
533 821
534=cut 822=cut
535 823
538no warnings; 826no warnings;
539use strict; 827use strict;
540 828
541use Carp; 829use Carp;
542 830
543our $VERSION = '3.3'; 831our $VERSION = 4.2;
544our $MODEL; 832our $MODEL;
545 833
546our $AUTOLOAD; 834our $AUTOLOAD;
547our @ISA; 835our @ISA;
548 836
837our @REGISTRY;
838
839our $WIN32;
840
841BEGIN {
842 my $win32 = ! ! ($^O =~ /mswin32/i);
843 eval "sub WIN32(){ $win32 }";
844}
845
549our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 846our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550 847
551our @REGISTRY; 848our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
849
850{
851 my $idx;
852 $PROTOCOL{$_} = ++$idx
853 for reverse split /\s*,\s*/,
854 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
855}
552 856
553my @models = ( 857my @models = (
554 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
555 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556 [EV:: => AnyEvent::Impl::EV::], 858 [EV:: => AnyEvent::Impl::EV::],
557 [Event:: => AnyEvent::Impl::Event::], 859 [Event:: => AnyEvent::Impl::Event::],
558 [Glib:: => AnyEvent::Impl::Glib::],
559 [Tk:: => AnyEvent::Impl::Tk::],
560 [Wx:: => AnyEvent::Impl::POE::],
561 [Prima:: => AnyEvent::Impl::POE::],
562 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 860 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563 # everything below here will not be autoprobed as the pureperl backend should work everywhere 861 # everything below here will not be autoprobed
862 # as the pureperl backend should work everywhere
863 # and is usually faster
864 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
865 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 866 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 867 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 868 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
869 [Wx:: => AnyEvent::Impl::POE::],
870 [Prima:: => AnyEvent::Impl::POE::],
567); 871);
568 872
569our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); 873our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
874
875our @post_detect;
876
877sub post_detect(&) {
878 my ($cb) = @_;
879
880 if ($MODEL) {
881 $cb->();
882
883 1
884 } else {
885 push @post_detect, $cb;
886
887 defined wantarray
888 ? bless \$cb, "AnyEvent::Util::PostDetect"
889 : ()
890 }
891}
892
893sub AnyEvent::Util::PostDetect::DESTROY {
894 @post_detect = grep $_ != ${$_[0]}, @post_detect;
895}
570 896
571sub detect() { 897sub detect() {
572 unless ($MODEL) { 898 unless ($MODEL) {
573 no strict 'refs'; 899 no strict 'refs';
900 local $SIG{__DIE__};
574 901
575 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 902 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576 my $model = "AnyEvent::Impl::$1"; 903 my $model = "AnyEvent::Impl::$1";
577 if (eval "require $model") { 904 if (eval "require $model") {
578 $MODEL = $model; 905 $MODEL = $model;
608 last; 935 last;
609 } 936 }
610 } 937 }
611 938
612 $MODEL 939 $MODEL
613 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; 940 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
614 } 941 }
615 } 942 }
616 943
944 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945
617 unshift @ISA, $MODEL; 946 unshift @ISA, $MODEL;
618 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 947
948 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
949
950 (shift @post_detect)->() while @post_detect;
619 } 951 }
620 952
621 $MODEL 953 $MODEL
622} 954}
623 955
631 963
632 my $class = shift; 964 my $class = shift;
633 $class->$func (@_); 965 $class->$func (@_);
634} 966}
635 967
968# utility function to dup a filehandle. this is used by many backends
969# to support binding more than one watcher per filehandle (they usually
970# allow only one watcher per fd, so we dup it to get a different one).
971sub _dupfh($$$$) {
972 my ($poll, $fh, $r, $w) = @_;
973
974 require Fcntl;
975
976 # cygwin requires the fh mode to be matching, unix doesn't
977 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
978 : $poll eq "w" ? ($w, ">")
979 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
980
981 open my $fh2, "$mode&" . fileno $fh
982 or die "cannot dup() filehandle: $!";
983
984 # we assume CLOEXEC is already set by perl in all important cases
985
986 ($fh2, $rw)
987}
988
636package AnyEvent::Base; 989package AnyEvent::Base;
637 990
991# default implementation for now and time
992
993use Time::HiRes ();
994
995sub time { Time::HiRes::time }
996sub now { Time::HiRes::time }
997
638# default implementation for ->condvar, ->wait, ->broadcast 998# default implementation for ->condvar
639 999
640sub condvar { 1000sub condvar {
641 bless \my $flag, "AnyEvent::Base::CondVar" 1001 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642}
643
644sub AnyEvent::Base::CondVar::broadcast {
645 ${$_[0]}++;
646}
647
648sub AnyEvent::Base::CondVar::wait {
649 AnyEvent->one_event while !${$_[0]};
650} 1002}
651 1003
652# default implementation for ->signal 1004# default implementation for ->signal
653 1005
654our %SIG_CB; 1006our %SIG_CB;
670sub AnyEvent::Base::Signal::DESTROY { 1022sub AnyEvent::Base::Signal::DESTROY {
671 my ($signal, $cb) = @{$_[0]}; 1023 my ($signal, $cb) = @{$_[0]};
672 1024
673 delete $SIG_CB{$signal}{$cb}; 1025 delete $SIG_CB{$signal}{$cb};
674 1026
675 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1027 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
676} 1028}
677 1029
678# default implementation for ->child 1030# default implementation for ->child
679 1031
680our %PID_CB; 1032our %PID_CB;
707 or Carp::croak "required option 'pid' is missing"; 1059 or Carp::croak "required option 'pid' is missing";
708 1060
709 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1061 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
710 1062
711 unless ($WNOHANG) { 1063 unless ($WNOHANG) {
712 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 1064 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
713 } 1065 }
714 1066
715 unless ($CHLD_W) { 1067 unless ($CHLD_W) {
716 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1068 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717 # child could be a zombie already, so make at least one round 1069 # child could be a zombie already, so make at least one round
727 delete $PID_CB{$pid}{$cb}; 1079 delete $PID_CB{$pid}{$cb};
728 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1080 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729 1081
730 undef $CHLD_W unless keys %PID_CB; 1082 undef $CHLD_W unless keys %PID_CB;
731} 1083}
1084
1085package AnyEvent::CondVar;
1086
1087our @ISA = AnyEvent::CondVar::Base::;
1088
1089package AnyEvent::CondVar::Base;
1090
1091use overload
1092 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1093 fallback => 1;
1094
1095sub _send {
1096 # nop
1097}
1098
1099sub send {
1100 my $cv = shift;
1101 $cv->{_ae_sent} = [@_];
1102 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
1103 $cv->_send;
1104}
1105
1106sub croak {
1107 $_[0]{_ae_croak} = $_[1];
1108 $_[0]->send;
1109}
1110
1111sub ready {
1112 $_[0]{_ae_sent}
1113}
1114
1115sub _wait {
1116 AnyEvent->one_event while !$_[0]{_ae_sent};
1117}
1118
1119sub recv {
1120 $_[0]->_wait;
1121
1122 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1123 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1124}
1125
1126sub cb {
1127 $_[0]{_ae_cb} = $_[1] if @_ > 1;
1128 $_[0]{_ae_cb}
1129}
1130
1131sub begin {
1132 ++$_[0]{_ae_counter};
1133 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1134}
1135
1136sub end {
1137 return if --$_[0]{_ae_counter};
1138 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1139}
1140
1141# undocumented/compatibility with pre-3.4
1142*broadcast = \&send;
1143*wait = \&_wait;
732 1144
733=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1145=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734 1146
735This is an advanced topic that you do not normally need to use AnyEvent in 1147This is an advanced topic that you do not normally need to use AnyEvent in
736a module. This section is only of use to event loop authors who want to 1148a module. This section is only of use to event loop authors who want to
790C<PERL_ANYEVENT_MODEL>. 1202C<PERL_ANYEVENT_MODEL>.
791 1203
792When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1204When set to C<2> or higher, cause AnyEvent to report to STDERR which event
793model it chooses. 1205model it chooses.
794 1206
1207=item C<PERL_ANYEVENT_STRICT>
1208
1209AnyEvent does not do much argument checking by default, as thorough
1210argument checking is very costly. Setting this variable to a true value
1211will cause AnyEvent to thoroughly check the arguments passed to most
1212method calls and croaks if it finds any problems. In other words, enables
1213"strict" mode. Unlike C<use strict> it is definitely recommended ot keep
1214it off in production.
1215
795=item C<PERL_ANYEVENT_MODEL> 1216=item C<PERL_ANYEVENT_MODEL>
796 1217
797This can be used to specify the event model to be used by AnyEvent, before 1218This can be used to specify the event model to be used by AnyEvent, before
798autodetection and -probing kicks in. It must be a string consisting 1219auto detection and -probing kicks in. It must be a string consisting
799entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1220entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800and the resulting module name is loaded and if the load was successful, 1221and the resulting module name is loaded and if the load was successful,
801used as event model. If it fails to load AnyEvent will proceed with 1222used as event model. If it fails to load AnyEvent will proceed with
802autodetection and -probing. 1223auto detection and -probing.
803 1224
804This functionality might change in future versions. 1225This functionality might change in future versions.
805 1226
806For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1227For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
807could start your program like this: 1228could start your program like this:
808 1229
809 PERL_ANYEVENT_MODEL=Perl perl ... 1230 PERL_ANYEVENT_MODEL=Perl perl ...
1231
1232=item C<PERL_ANYEVENT_PROTOCOLS>
1233
1234Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1235for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1236of auto probing).
1237
1238Must be set to a comma-separated list of protocols or address families,
1239current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1240used, and preference will be given to protocols mentioned earlier in the
1241list.
1242
1243This variable can effectively be used for denial-of-service attacks
1244against local programs (e.g. when setuid), although the impact is likely
1245small, as the program has to handle connection errors already-
1246
1247Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1248but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1249- only support IPv4, never try to resolve or contact IPv6
1250addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1251IPv6, but prefer IPv6 over IPv4.
1252
1253=item C<PERL_ANYEVENT_EDNS0>
1254
1255Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1256for DNS. This extension is generally useful to reduce DNS traffic, but
1257some (broken) firewalls drop such DNS packets, which is why it is off by
1258default.
1259
1260Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1261EDNS0 in its DNS requests.
1262
1263=item C<PERL_ANYEVENT_MAX_FORKS>
1264
1265The maximum number of child processes that C<AnyEvent::Util::fork_call>
1266will create in parallel.
810 1267
811=back 1268=back
812 1269
813=head1 EXAMPLE PROGRAM 1270=head1 EXAMPLE PROGRAM
814 1271
825 poll => 'r', 1282 poll => 'r',
826 cb => sub { 1283 cb => sub {
827 warn "io event <$_[0]>\n"; # will always output <r> 1284 warn "io event <$_[0]>\n"; # will always output <r>
828 chomp (my $input = <STDIN>); # read a line 1285 chomp (my $input = <STDIN>); # read a line
829 warn "read: $input\n"; # output what has been read 1286 warn "read: $input\n"; # output what has been read
830 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1287 $cv->send if $input =~ /^q/i; # quit program if /^q/i
831 }, 1288 },
832 ); 1289 );
833 1290
834 my $time_watcher; # can only be used once 1291 my $time_watcher; # can only be used once
835 1292
840 }); 1297 });
841 } 1298 }
842 1299
843 new_timer; # create first timer 1300 new_timer; # create first timer
844 1301
845 $cv->wait; # wait until user enters /^q/i 1302 $cv->recv; # wait until user enters /^q/i
846 1303
847=head1 REAL-WORLD EXAMPLE 1304=head1 REAL-WORLD EXAMPLE
848 1305
849Consider the L<Net::FCP> module. It features (among others) the following 1306Consider the L<Net::FCP> module. It features (among others) the following
850API calls, which are to freenet what HTTP GET requests are to http: 1307API calls, which are to freenet what HTTP GET requests are to http:
900 syswrite $txn->{fh}, $txn->{request} 1357 syswrite $txn->{fh}, $txn->{request}
901 or die "connection or write error"; 1358 or die "connection or write error";
902 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1359 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
903 1360
904Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1361Again, C<fh_ready_r> waits till all data has arrived, and then stores the
905result and signals any possible waiters that the request ahs finished: 1362result and signals any possible waiters that the request has finished:
906 1363
907 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1364 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908 1365
909 if (end-of-file or data complete) { 1366 if (end-of-file or data complete) {
910 $txn->{result} = $txn->{buf}; 1367 $txn->{result} = $txn->{buf};
911 $txn->{finished}->broadcast; 1368 $txn->{finished}->send;
912 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1369 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
913 } 1370 }
914 1371
915The C<result> method, finally, just waits for the finished signal (if the 1372The C<result> method, finally, just waits for the finished signal (if the
916request was already finished, it doesn't wait, of course, and returns the 1373request was already finished, it doesn't wait, of course, and returns the
917data: 1374data:
918 1375
919 $txn->{finished}->wait; 1376 $txn->{finished}->recv;
920 return $txn->{result}; 1377 return $txn->{result};
921 1378
922The actual code goes further and collects all errors (C<die>s, exceptions) 1379The actual code goes further and collects all errors (C<die>s, exceptions)
923that occured during request processing. The C<result> method detects 1380that occurred during request processing. The C<result> method detects
924whether an exception as thrown (it is stored inside the $txn object) 1381whether an exception as thrown (it is stored inside the $txn object)
925and just throws the exception, which means connection errors and other 1382and just throws the exception, which means connection errors and other
926problems get reported tot he code that tries to use the result, not in a 1383problems get reported tot he code that tries to use the result, not in a
927random callback. 1384random callback.
928 1385
959 1416
960 my $quit = AnyEvent->condvar; 1417 my $quit = AnyEvent->condvar;
961 1418
962 $fcp->txn_client_get ($url)->cb (sub { 1419 $fcp->txn_client_get ($url)->cb (sub {
963 ... 1420 ...
964 $quit->broadcast; 1421 $quit->send;
965 }); 1422 });
966 1423
967 $quit->wait; 1424 $quit->recv;
968 1425
969 1426
970=head1 BENCHMARKS 1427=head1 BENCHMARKS
971 1428
972To give you an idea of the performance and overheads that AnyEvent adds 1429To give you an idea of the performance and overheads that AnyEvent adds
974of various event loops I prepared some benchmarks. 1431of various event loops I prepared some benchmarks.
975 1432
976=head2 BENCHMARKING ANYEVENT OVERHEAD 1433=head2 BENCHMARKING ANYEVENT OVERHEAD
977 1434
978Here is a benchmark of various supported event models used natively and 1435Here is a benchmark of various supported event models used natively and
979through anyevent. The benchmark creates a lot of timers (with a zero 1436through AnyEvent. The benchmark creates a lot of timers (with a zero
980timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1437timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981which it is), lets them fire exactly once and destroys them again. 1438which it is), lets them fire exactly once and destroys them again.
982 1439
983Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1440Source code for this benchmark is found as F<eg/bench> in the AnyEvent
984distribution. 1441distribution.
1001all watchers, to avoid adding memory overhead. That means closure creation 1458all watchers, to avoid adding memory overhead. That means closure creation
1002and memory usage is not included in the figures. 1459and memory usage is not included in the figures.
1003 1460
1004I<invoke> is the time, in microseconds, used to invoke a simple 1461I<invoke> is the time, in microseconds, used to invoke a simple
1005callback. The callback simply counts down a Perl variable and after it was 1462callback. The callback simply counts down a Perl variable and after it was
1006invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1463invoked "watcher" times, it would C<< ->send >> a condvar once to
1007signal the end of this phase. 1464signal the end of this phase.
1008 1465
1009I<destroy> is the time, in microseconds, that it takes to destroy a single 1466I<destroy> is the time, in microseconds, that it takes to destroy a single
1010watcher. 1467watcher.
1011 1468
1071file descriptor is dup()ed for each watcher. This shows that the dup() 1528file descriptor is dup()ed for each watcher. This shows that the dup()
1072employed by some adaptors is not a big performance issue (it does incur a 1529employed by some adaptors is not a big performance issue (it does incur a
1073hidden memory cost inside the kernel which is not reflected in the figures 1530hidden memory cost inside the kernel which is not reflected in the figures
1074above). 1531above).
1075 1532
1076C<POE>, regardless of underlying event loop (whether using its pure 1533C<POE>, regardless of underlying event loop (whether using its pure perl
1077perl select-based backend or the Event module, the POE-EV backend 1534select-based backend or the Event module, the POE-EV backend couldn't
1078couldn't be tested because it wasn't working) shows abysmal performance 1535be tested because it wasn't working) shows abysmal performance and
1079and memory usage: Watchers use almost 30 times as much memory as 1536memory usage with AnyEvent: Watchers use almost 30 times as much memory
1080EV watchers, and 10 times as much memory as Event (the high memory 1537as EV watchers, and 10 times as much memory as Event (the high memory
1081requirements are caused by requiring a session for each watcher). Watcher 1538requirements are caused by requiring a session for each watcher). Watcher
1082invocation speed is almost 900 times slower than with AnyEvent's pure perl 1539invocation speed is almost 900 times slower than with AnyEvent's pure perl
1540implementation.
1541
1083implementation. The design of the POE adaptor class in AnyEvent can not 1542The design of the POE adaptor class in AnyEvent can not really account
1084really account for this, as session creation overhead is small compared 1543for the performance issues, though, as session creation overhead is
1085to execution of the state machine, which is coded pretty optimally within 1544small compared to execution of the state machine, which is coded pretty
1086L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. 1545optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
1546using multiple sessions is not a good approach, especially regarding
1547memory usage, even the author of POE could not come up with a faster
1548design).
1087 1549
1088=head3 Summary 1550=head3 Summary
1089 1551
1090=over 4 1552=over 4
1091 1553
1102 1564
1103=back 1565=back
1104 1566
1105=head2 BENCHMARKING THE LARGE SERVER CASE 1567=head2 BENCHMARKING THE LARGE SERVER CASE
1106 1568
1107This benchmark atcually benchmarks the event loop itself. It works by 1569This benchmark actually benchmarks the event loop itself. It works by
1108creating a number of "servers": each server consists of a socketpair, a 1570creating a number of "servers": each server consists of a socket pair, a
1109timeout watcher that gets reset on activity (but never fires), and an I/O 1571timeout watcher that gets reset on activity (but never fires), and an I/O
1110watcher waiting for input on one side of the socket. Each time the socket 1572watcher waiting for input on one side of the socket. Each time the socket
1111watcher reads a byte it will write that byte to a random other "server". 1573watcher reads a byte it will write that byte to a random other "server".
1112 1574
1113The effect is that there will be a lot of I/O watchers, only part of which 1575The effect is that there will be a lot of I/O watchers, only part of which
1114are active at any one point (so there is a constant number of active 1576are active at any one point (so there is a constant number of active
1115fds for each loop iterstaion, but which fds these are is random). The 1577fds for each loop iteration, but which fds these are is random). The
1116timeout is reset each time something is read because that reflects how 1578timeout is reset each time something is read because that reflects how
1117most timeouts work (and puts extra pressure on the event loops). 1579most timeouts work (and puts extra pressure on the event loops).
1118 1580
1119In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1581In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1120(1%) are active. This mirrors the activity of large servers with many 1582(1%) are active. This mirrors the activity of large servers with many
1121connections, most of which are idle at any one point in time. 1583connections, most of which are idle at any one point in time.
1122 1584
1123Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1585Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1124distribution. 1586distribution.
1126=head3 Explanation of the columns 1588=head3 Explanation of the columns
1127 1589
1128I<sockets> is the number of sockets, and twice the number of "servers" (as 1590I<sockets> is the number of sockets, and twice the number of "servers" (as
1129each server has a read and write socket end). 1591each server has a read and write socket end).
1130 1592
1131I<create> is the time it takes to create a socketpair (which is 1593I<create> is the time it takes to create a socket pair (which is
1132nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1594nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1133 1595
1134I<request>, the most important value, is the time it takes to handle a 1596I<request>, the most important value, is the time it takes to handle a
1135single "request", that is, reading the token from the pipe and forwarding 1597single "request", that is, reading the token from the pipe and forwarding
1136it to another server. This includes deleting the old timeout and creating 1598it to another server. This includes deleting the old timeout and creating
1170 1632
1171=head3 Summary 1633=head3 Summary
1172 1634
1173=over 4 1635=over 4
1174 1636
1175=item * The pure perl implementation performs extremely well, considering 1637=item * The pure perl implementation performs extremely well.
1176that it uses select.
1177 1638
1178=item * Avoid Glib or POE in large projects where performance matters. 1639=item * Avoid Glib or POE in large projects where performance matters.
1179 1640
1180=back 1641=back
1181 1642
1210speed most when you have lots of watchers, not when you only have a few of 1671speed most when you have lots of watchers, not when you only have a few of
1211them). 1672them).
1212 1673
1213EV is again fastest. 1674EV is again fastest.
1214 1675
1215Perl again comes second. It is noticably faster than the C-based event 1676Perl again comes second. It is noticeably faster than the C-based event
1216loops Event and Glib, although the difference is too small to really 1677loops Event and Glib, although the difference is too small to really
1217matter. 1678matter.
1218 1679
1219POE also performs much better in this case, but is is still far behind the 1680POE also performs much better in this case, but is is still far behind the
1220others. 1681others.
1230 1691
1231 1692
1232=head1 FORK 1693=head1 FORK
1233 1694
1234Most event libraries are not fork-safe. The ones who are usually are 1695Most event libraries are not fork-safe. The ones who are usually are
1235because they are so inefficient. Only L<EV> is fully fork-aware. 1696because they rely on inefficient but fork-safe C<select> or C<poll>
1697calls. Only L<EV> is fully fork-aware.
1236 1698
1237If you have to fork, you must either do so I<before> creating your first 1699If you have to fork, you must either do so I<before> creating your first
1238watcher OR you must not use AnyEvent at all in the child. 1700watcher OR you must not use AnyEvent at all in the child.
1239 1701
1240 1702
1248specified in the variable. 1710specified in the variable.
1249 1711
1250You can make AnyEvent completely ignore this variable by deleting it 1712You can make AnyEvent completely ignore this variable by deleting it
1251before the first watcher gets created, e.g. with a C<BEGIN> block: 1713before the first watcher gets created, e.g. with a C<BEGIN> block:
1252 1714
1253 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1715 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1254 1716
1255 use AnyEvent; 1717 use AnyEvent;
1718
1719Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1720be used to probe what backend is used and gain other information (which is
1721probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1722$ENV{PERL_ANYEGENT_STRICT}.
1723
1724
1725=head1 BUGS
1726
1727Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1728to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1729and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1730mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
1731pronounced).
1256 1732
1257 1733
1258=head1 SEE ALSO 1734=head1 SEE ALSO
1259 1735
1260Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1736Utility functions: L<AnyEvent::Util>.
1261L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 1737
1738Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1262L<Event::Lib>, L<Qt>, L<POE>. 1739L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1263 1740
1264Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1741Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1265L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1742L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1266L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1743L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1267L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1744L<AnyEvent::Impl::POE>.
1268 1745
1746Non-blocking file handles, sockets, TCP clients and
1747servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1748
1749Asynchronous DNS: L<AnyEvent::DNS>.
1750
1751Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1752
1269Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1753Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1270 1754
1271 1755
1272=head1 AUTHOR 1756=head1 AUTHOR
1273 1757
1274 Marc Lehmann <schmorp@schmorp.de> 1758 Marc Lehmann <schmorp@schmorp.de>
1275 http://home.schmorp.de/ 1759 http://home.schmorp.de/
1276 1760
1277=cut 1761=cut
1278 1762
12791 17631
1280 1764

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