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6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { 11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
12 ...
13 });
14 12
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 13 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15
16 print AnyEvent->now; # prints current event loop time
17 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18
19 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20
21 my $w = AnyEvent->child (pid => $pid, cb => sub {
22 my ($pid, $status) = @_;
16 ... 23 ...
17 }); 24 });
18 25
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 26 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's 27 $w->send; # wake up current and all future recv's
21 $w->recv; # enters "main loop" till $condvar gets ->send 28 $w->recv; # enters "main loop" till $condvar gets ->send
29 # use a condvar in callback mode:
30 $w->cb (sub { $_[0]->recv });
31
32=head1 INTRODUCTION/TUTORIAL
33
34This manpage is mainly a reference manual. If you are interested
35in a tutorial or some gentle introduction, have a look at the
36L<AnyEvent::Intro> manpage.
22 37
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 38=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 39
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 40Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 41nowadays. So what is different about AnyEvent?
27 42
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 43Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>. 44policy> and AnyEvent is I<small and efficient>.
30 45
31First and foremost, I<AnyEvent is not an event model> itself, it only 46First 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 47interfaces to whatever event model the main program happens to use, in a
33pragmatic way. For event models and certain classes of immortals alike, 48pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality: In general, 49the 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 50only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops. 51cannot change this, but it can hide the differences between those event
52loops.
37 53
38The goal of AnyEvent is to offer module authors the ability to do event 54The 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 55programming (waiting for I/O or timer events) without subscribing to a
40religion, a way of living, and most importantly: without forcing your 56religion, a way of living, and most importantly: without forcing your
41module users into the same thing by forcing them to use the same event 57module users into the same thing by forcing them to use the same event
42model you use. 58model you use.
43 59
44For modules like POE or IO::Async (which is a total misnomer as it is 60For 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 61actually 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 62like 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 63cannot use anything else, as they are simply incompatible to everything
48isn't itself. What's worse, all the potential users of your module are 64that isn't them. What's worse, all the potential users of your
49I<also> forced to use the same event loop you use. 65module are I<also> forced to use the same event loop you use.
50 66
51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 67AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52fine. AnyEvent + Tk works fine etc. etc. but none of these work together 68fine. 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 69with 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, 70your 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 71too. But if your module uses AnyEvent, it works transparently with all
56event models it supports (including stuff like POE and IO::Async, as long 72event 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 73use one of the supported event loops. It is trivial to add new event loops
58event loops to AnyEvent, too, so it is future-proof). 74to AnyEvent, too, so it is future-proof).
59 75
60In addition to being free of having to use I<the one and only true event 76In 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 77model>, 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 78modules, 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 79follow. 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 80offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 81technically possible.
66 82
83Of course, AnyEvent comes with a big (and fully optional!) toolbox
84of useful functionality, such as an asynchronous DNS resolver, 100%
85non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
86such as Windows) and lots of real-world knowledge and workarounds for
87platform bugs and differences.
88
67Of course, if you want lots of policy (this can arguably be somewhat 89Now, 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 90useful) and you want to force your users to use the one and only event
69model, you should I<not> use this module. 91model, you should I<not> use this module.
70 92
71=head1 DESCRIPTION 93=head1 DESCRIPTION
72 94
102starts using it, all bets are off. Maybe you should tell their authors to 124starts using it, all bets are off. Maybe you should tell their authors to
103use AnyEvent so their modules work together with others seamlessly... 125use AnyEvent so their modules work together with others seamlessly...
104 126
105The pure-perl implementation of AnyEvent is called 127The pure-perl implementation of AnyEvent is called
106C<AnyEvent::Impl::Perl>. Like other event modules you can load it 128C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107explicitly. 129explicitly and enjoy the high availability of that event loop :)
108 130
109=head1 WATCHERS 131=head1 WATCHERS
110 132
111AnyEvent has the central concept of a I<watcher>, which is an object that 133AnyEvent 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 134stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 135the callback to call, the file handle to watch, etc.
114 136
115These watchers are normal Perl objects with normal Perl lifetime. After 137These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 138creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 139callback when the event occurs (of course, only when the event model
118is in control). 140is in control).
119 141
142Note that B<callbacks must not permanently change global variables>
143potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
144callbacks must not C<die> >>. The former is good programming practise in
145Perl and the latter stems from the fact that exception handling differs
146widely between event loops.
147
120To disable the watcher you have to destroy it (e.g. by setting the 148To disable the watcher you have to destroy it (e.g. by setting the
121variable you store it in to C<undef> or otherwise deleting all references 149variable you store it in to C<undef> or otherwise deleting all references
122to it). 150to it).
123 151
124All watchers are created by calling a method on the C<AnyEvent> class. 152All watchers are created by calling a method on the C<AnyEvent> class.
126Many watchers either are used with "recursion" (repeating timers for 154Many watchers either are used with "recursion" (repeating timers for
127example), or need to refer to their watcher object in other ways. 155example), or need to refer to their watcher object in other ways.
128 156
129An any way to achieve that is this pattern: 157An any way to achieve that is this pattern:
130 158
131 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 159 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132 # you can use $w here, for example to undef it 160 # you can use $w here, for example to undef it
133 undef $w; 161 undef $w;
134 }); 162 });
135 163
136Note that C<my $w; $w => combination. This is necessary because in Perl, 164Note that C<my $w; $w => combination. This is necessary because in Perl,
137my variables are only visible after the statement in which they are 165my variables are only visible after the statement in which they are
138declared. 166declared.
139 167
140=head2 I/O WATCHERS 168=head2 I/O WATCHERS
141 169
142You can create an I/O watcher by calling the C<< AnyEvent->io >> method 170You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143with the following mandatory key-value pairs as arguments: 171with the following mandatory key-value pairs as arguments:
144 172
145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch 173C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
174for events (AnyEvent might or might not keep a reference to this file
175handle). Note that only file handles pointing to things for which
176non-blocking operation makes sense are allowed. This includes sockets,
177most character devices, pipes, fifos and so on, but not for example files
178or block devices.
179
146for events. C<poll> must be a string that is either C<r> or C<w>, 180C<poll> must be a string that is either C<r> or C<w>, which creates a
147which creates a watcher waiting for "r"eadable or "w"ritable events, 181watcher waiting for "r"eadable or "w"ritable events, respectively.
182
148respectively. C<cb> is the callback to invoke each time the file handle 183C<cb> is the callback to invoke each time the file handle becomes ready.
149becomes ready.
150 184
151Although the callback might get passed parameters, their value and 185Although the callback might get passed parameters, their value and
152presence is undefined and you cannot rely on them. Portable AnyEvent 186presence is undefined and you cannot rely on them. Portable AnyEvent
153callbacks cannot use arguments passed to I/O watcher callbacks. 187callbacks cannot use arguments passed to I/O watcher callbacks.
154 188
158 192
159Some event loops issue spurious readyness notifications, so you should 193Some event loops issue spurious readyness notifications, so you should
160always use non-blocking calls when reading/writing from/to your file 194always use non-blocking calls when reading/writing from/to your file
161handles. 195handles.
162 196
163Example:
164
165 # wait for readability of STDIN, then read a line and disable the watcher 197Example: wait for readability of STDIN, then read a line and disable the
198watcher.
199
166 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 200 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167 chomp (my $input = <STDIN>); 201 chomp (my $input = <STDIN>);
168 warn "read: $input\n"; 202 warn "read: $input\n";
169 undef $w; 203 undef $w;
170 }); 204 });
180 214
181Although the callback might get passed parameters, their value and 215Although the callback might get passed parameters, their value and
182presence is undefined and you cannot rely on them. Portable AnyEvent 216presence is undefined and you cannot rely on them. Portable AnyEvent
183callbacks cannot use arguments passed to time watcher callbacks. 217callbacks cannot use arguments passed to time watcher callbacks.
184 218
185The timer callback will be invoked at most once: if you want a repeating 219The 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 220parameter, C<interval>, as a strictly positive number (> 0), then the
187and Glib). 221callback will be invoked regularly at that interval (in fractional
222seconds) after the first invocation. If C<interval> is specified with a
223false value, then it is treated as if it were missing.
188 224
189Example: 225The callback will be rescheduled before invoking the callback, but no
226attempt is done to avoid timer drift in most backends, so the interval is
227only approximate.
190 228
191 # fire an event after 7.7 seconds 229Example: fire an event after 7.7 seconds.
230
192 my $w = AnyEvent->timer (after => 7.7, cb => sub { 231 my $w = AnyEvent->timer (after => 7.7, cb => sub {
193 warn "timeout\n"; 232 warn "timeout\n";
194 }); 233 });
195 234
196 # to cancel the timer: 235 # to cancel the timer:
197 undef $w; 236 undef $w;
198 237
199Example 2:
200
201 # fire an event after 0.5 seconds, then roughly every second 238Example 2: fire an event after 0.5 seconds, then roughly every second.
202 my $w;
203 239
204 my $cb = sub {
205 # cancel the old timer while creating a new one
206 $w = AnyEvent->timer (after => 1, cb => $cb); 240 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
241 warn "timeout\n";
207 }; 242 };
208
209 # start the "loop" by creating the first watcher
210 $w = AnyEvent->timer (after => 0.5, cb => $cb);
211 243
212=head3 TIMING ISSUES 244=head3 TIMING ISSUES
213 245
214There are two ways to handle timers: based on real time (relative, "fire 246There are two ways to handle timers: based on real time (relative, "fire
215in 10 seconds") and based on wallclock time (absolute, "fire at 12 247in 10 seconds") and based on wallclock time (absolute, "fire at 12
227timers. 259timers.
228 260
229AnyEvent always prefers relative timers, if available, matching the 261AnyEvent always prefers relative timers, if available, matching the
230AnyEvent API. 262AnyEvent API.
231 263
264AnyEvent has two additional methods that return the "current time":
265
266=over 4
267
268=item AnyEvent->time
269
270This returns the "current wallclock time" as a fractional number of
271seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
272return, and the result is guaranteed to be compatible with those).
273
274It progresses independently of any event loop processing, i.e. each call
275will check the system clock, which usually gets updated frequently.
276
277=item AnyEvent->now
278
279This also returns the "current wallclock time", but unlike C<time>, above,
280this value might change only once per event loop iteration, depending on
281the event loop (most return the same time as C<time>, above). This is the
282time that AnyEvent's timers get scheduled against.
283
284I<In almost all cases (in all cases if you don't care), this is the
285function to call when you want to know the current time.>
286
287This function is also often faster then C<< AnyEvent->time >>, and
288thus the preferred method if you want some timestamp (for example,
289L<AnyEvent::Handle> uses this to update it's activity timeouts).
290
291The rest of this section is only of relevance if you try to be very exact
292with your timing, you can skip it without bad conscience.
293
294For a practical example of when these times differ, consider L<Event::Lib>
295and L<EV> and the following set-up:
296
297The event loop is running and has just invoked one of your callback at
298time=500 (assume no other callbacks delay processing). In your callback,
299you wait a second by executing C<sleep 1> (blocking the process for a
300second) and then (at time=501) you create a relative timer that fires
301after three seconds.
302
303With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
304both return C<501>, because that is the current time, and the timer will
305be scheduled to fire at time=504 (C<501> + C<3>).
306
307With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
308time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
309last event processing phase started. With L<EV>, your timer gets scheduled
310to run at time=503 (C<500> + C<3>).
311
312In one sense, L<Event::Lib> is more exact, as it uses the current time
313regardless of any delays introduced by event processing. However, most
314callbacks do not expect large delays in processing, so this causes a
315higher drift (and a lot more system calls to get the current time).
316
317In another sense, L<EV> is more exact, as your timer will be scheduled at
318the same time, regardless of how long event processing actually took.
319
320In either case, if you care (and in most cases, you don't), then you
321can get whatever behaviour you want with any event loop, by taking the
322difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
323account.
324
325=back
326
232=head2 SIGNAL WATCHERS 327=head2 SIGNAL WATCHERS
233 328
234You can watch for signals using a signal watcher, C<signal> is the signal 329You 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 330I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236be invoked whenever a signal occurs. 331callback to be invoked whenever a signal occurs.
237 332
238Although the callback might get passed parameters, their value and 333Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 334presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 335callbacks cannot use arguments passed to signal watcher callbacks.
241 336
242Multiple signal occurances can be clumped together into one callback 337Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 338invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 339that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 340but it is guaranteed not to interrupt any other callbacks.
246 341
247The main advantage of using these watchers is that you can share a signal 342The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 343between multiple watchers.
249 344
250This watcher might use C<%SIG>, so programs overwriting those signals 345This watcher might use C<%SIG>, so programs overwriting those signals
257=head2 CHILD PROCESS WATCHERS 352=head2 CHILD PROCESS WATCHERS
258 353
259You can also watch on a child process exit and catch its exit status. 354You can also watch on a child process exit and catch its exit status.
260 355
261The child process is specified by the C<pid> argument (if set to C<0>, it 356The child process is specified by the C<pid> argument (if set to C<0>, it
262watches for any child process exit). The watcher will trigger as often 357watches for any child process exit). The watcher will triggered only when
263as status change for the child are received. This works by installing a 358the child process has finished and an exit status is available, not on
264signal handler for C<SIGCHLD>. The callback will be called with the pid 359any trace events (stopped/continued).
265and exit status (as returned by waitpid), so unlike other watcher types, 360
266you I<can> rely on child watcher callback arguments. 361The callback will be called with the pid and exit status (as returned by
362waitpid), so unlike other watcher types, you I<can> rely on child watcher
363callback arguments.
364
365This watcher type works by installing a signal handler for C<SIGCHLD>,
366and since it cannot be shared, nothing else should use SIGCHLD or reap
367random child processes (waiting for specific child processes, e.g. inside
368C<system>, is just fine).
267 369
268There is a slight catch to child watchers, however: you usually start them 370There is a slight catch to child watchers, however: you usually start them
269I<after> the child process was created, and this means the process could 371I<after> the child process was created, and this means the process could
270have exited already (and no SIGCHLD will be sent anymore). 372have exited already (and no SIGCHLD will be sent anymore).
271 373
277AnyEvent program, you I<have> to create at least one watcher before you 379AnyEvent program, you I<have> to create at least one watcher before you
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 380C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 381
280Example: fork a process and wait for it 382Example: fork a process and wait for it
281 383
282 my $done = AnyEvent->condvar; 384 my $done = AnyEvent->condvar;
283 385
284 my $pid = fork or exit 5; 386 my $pid = fork or exit 5;
285 387
286 my $w = AnyEvent->child ( 388 my $w = AnyEvent->child (
287 pid => $pid, 389 pid => $pid,
288 cb => sub { 390 cb => sub {
289 my ($pid, $status) = @_; 391 my ($pid, $status) = @_;
290 warn "pid $pid exited with status $status"; 392 warn "pid $pid exited with status $status";
291 $done->send; 393 $done->send;
292 }, 394 },
293 ); 395 );
294 396
295 # do something else, then wait for process exit 397 # do something else, then wait for process exit
296 $done->recv; 398 $done->recv;
297 399
298=head2 CONDITION VARIABLES 400=head2 CONDITION VARIABLES
299 401
300If you are familiar with some event loops you will know that all of them 402If you are familiar with some event loops you will know that all of them
301require you to run some blocking "loop", "run" or similar function that 403require you to run some blocking "loop", "run" or similar function that
307The instrument to do that is called a "condition variable", so called 409The instrument to do that is called a "condition variable", so called
308because they represent a condition that must become true. 410because they represent a condition that must become true.
309 411
310Condition variables can be created by calling the C<< AnyEvent->condvar 412Condition variables can be created by calling the C<< AnyEvent->condvar
311>> method, usually without arguments. The only argument pair allowed is 413>> method, usually without arguments. The only argument pair allowed is
414
312C<cb>, which specifies a callback to be called when the condition variable 415C<cb>, which specifies a callback to be called when the condition variable
313becomes true. 416becomes true, with the condition variable as the first argument (but not
417the results).
314 418
315After creation, the conditon variable is "false" until it becomes "true" 419After creation, the condition variable is "false" until it becomes "true"
316by calling the C<send> method. 420by calling the C<send> method (or calling the condition variable as if it
421were a callback, read about the caveats in the description for the C<<
422->send >> method).
317 423
318Condition variables are similar to callbacks, except that you can 424Condition variables are similar to callbacks, except that you can
319optionally wait for them. They can also be called merge points - points 425optionally wait for them. They can also be called merge points - points
320in time where multiple outstandign events have been processed. And yet 426in time where multiple outstanding events have been processed. And yet
321another way to call them is transations - each condition variable can be 427another way to call them is transactions - each condition variable can be
322used to represent a transaction, which finishes at some point and delivers 428used to represent a transaction, which finishes at some point and delivers
323a result. 429a result.
324 430
325Condition variables are very useful to signal that something has finished, 431Condition variables are very useful to signal that something has finished,
326for example, if you write a module that does asynchronous http requests, 432for example, if you write a module that does asynchronous http requests,
332you can block your main program until an event occurs - for example, you 438you can block your main program until an event occurs - for example, you
333could C<< ->recv >> in your main program until the user clicks the Quit 439could C<< ->recv >> in your main program until the user clicks the Quit
334button of your app, which would C<< ->send >> the "quit" event. 440button of your app, which would C<< ->send >> the "quit" event.
335 441
336Note that condition variables recurse into the event loop - if you have 442Note that condition variables recurse into the event loop - if you have
337two pieces of code that call C<< ->recv >> in a round-robbin fashion, you 443two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338lose. Therefore, condition variables are good to export to your caller, but 444lose. Therefore, condition variables are good to export to your caller, but
339you should avoid making a blocking wait yourself, at least in callbacks, 445you should avoid making a blocking wait yourself, at least in callbacks,
340as this asks for trouble. 446as this asks for trouble.
341 447
342Condition variables are represented by hash refs in perl, and the keys 448Condition variables are represented by hash refs in perl, and the keys
347 453
348There are two "sides" to a condition variable - the "producer side" which 454There are two "sides" to a condition variable - the "producer side" which
349eventually calls C<< -> send >>, and the "consumer side", which waits 455eventually calls C<< -> send >>, and the "consumer side", which waits
350for the send to occur. 456for the send to occur.
351 457
352Example: 458Example: wait for a timer.
353 459
354 # wait till the result is ready 460 # wait till the result is ready
355 my $result_ready = AnyEvent->condvar; 461 my $result_ready = AnyEvent->condvar;
356 462
357 # do something such as adding a timer 463 # do something such as adding a timer
365 471
366 # this "blocks" (while handling events) till the callback 472 # this "blocks" (while handling events) till the callback
367 # calls send 473 # calls send
368 $result_ready->recv; 474 $result_ready->recv;
369 475
476Example: wait for a timer, but take advantage of the fact that
477condition variables are also code references.
478
479 my $done = AnyEvent->condvar;
480 my $delay = AnyEvent->timer (after => 5, cb => $done);
481 $done->recv;
482
483Example: Imagine an API that returns a condvar and doesn't support
484callbacks. This is how you make a synchronous call, for example from
485the main program:
486
487 use AnyEvent::CouchDB;
488
489 ...
490
491 my @info = $couchdb->info->recv;
492
493And this is how you would just ste a callback to be called whenever the
494results are available:
495
496 $couchdb->info->cb (sub {
497 my @info = $_[0]->recv;
498 });
499
370=head3 METHODS FOR PRODUCERS 500=head3 METHODS FOR PRODUCERS
371 501
372These methods should only be used by the producing side, i.e. the 502These methods should only be used by the producing side, i.e. the
373code/module that eventually sends the signal. Note that it is also 503code/module that eventually sends the signal. Note that it is also
374the producer side which creates the condvar in most cases, but it isn't 504the producer side which creates the condvar in most cases, but it isn't
385If a callback has been set on the condition variable, it is called 515If a callback has been set on the condition variable, it is called
386immediately from within send. 516immediately from within send.
387 517
388Any arguments passed to the C<send> call will be returned by all 518Any arguments passed to the C<send> call will be returned by all
389future C<< ->recv >> calls. 519future C<< ->recv >> calls.
520
521Condition variables are overloaded so one can call them directly
522(as a code reference). Calling them directly is the same as calling
523C<send>. Note, however, that many C-based event loops do not handle
524overloading, so as tempting as it may be, passing a condition variable
525instead of a callback does not work. Both the pure perl and EV loops
526support overloading, however, as well as all functions that use perl to
527invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
528example).
390 529
391=item $cv->croak ($error) 530=item $cv->croak ($error)
392 531
393Similar to send, but causes all call's to C<< ->recv >> to invoke 532Similar to send, but causes all call's to C<< ->recv >> to invoke
394C<Carp::croak> with the given error message/object/scalar. 533C<Carp::croak> with the given error message/object/scalar.
443doesn't execute once). 582doesn't execute once).
444 583
445This is the general pattern when you "fan out" into multiple subrequests: 584This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 585use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 586is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 587C<begin> and for each subrequest you finish, call C<end>.
449 588
450=back 589=back
451 590
452=head3 METHODS FOR CONSUMERS 591=head3 METHODS FOR CONSUMERS
453 592
475(programs might want to do that to stay interactive), so I<if you are 614(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 615using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 616caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 617condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 618callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 619while still supporting blocking waits if the caller so desires).
481 620
482Another reason I<never> to C<< ->recv >> in a module is that you cannot 621Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->recv >>'s in parallel, as that would require 622sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 623multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 624can supply.
498=item $bool = $cv->ready 637=item $bool = $cv->ready
499 638
500Returns true when the condition is "true", i.e. whether C<send> or 639Returns true when the condition is "true", i.e. whether C<send> or
501C<croak> have been called. 640C<croak> have been called.
502 641
503=item $cb = $cv->cb ([new callback]) 642=item $cb = $cv->cb ($cb->($cv))
504 643
505This is a mutator function that returns the callback set and optionally 644This is a mutator function that returns the callback set and optionally
506replaces it before doing so. 645replaces it before doing so.
507 646
508The callback will be called when the condition becomes "true", i.e. when 647The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<recv> inside the callback 648C<send> or C<croak> are called, with the only argument being the condition
510or at any later time is guaranteed not to block. 649variable itself. Calling C<recv> inside the callback or at any later time
650is guaranteed not to block.
511 651
512=back 652=back
513 653
514=head1 GLOBAL VARIABLES AND FUNCTIONS 654=head1 GLOBAL VARIABLES AND FUNCTIONS
515 655
601 741
602If it doesn't care, it can just "use AnyEvent" and use it itself, or not 742If it doesn't care, it can just "use AnyEvent" and use it itself, or not
603do anything special (it does not need to be event-based) and let AnyEvent 743do anything special (it does not need to be event-based) and let AnyEvent
604decide which implementation to chose if some module relies on it. 744decide which implementation to chose if some module relies on it.
605 745
606If the main program relies on a specific event model. For example, in 746If the main program relies on a specific event model - for example, in
607Gtk2 programs you have to rely on the Glib module. You should load the 747Gtk2 programs you have to rely on the Glib module - you should load the
608event module before loading AnyEvent or any module that uses it: generally 748event module before loading AnyEvent or any module that uses it: generally
609speaking, you should load it as early as possible. The reason is that 749speaking, you should load it as early as possible. The reason is that
610modules might create watchers when they are loaded, and AnyEvent will 750modules might create watchers when they are loaded, and AnyEvent will
611decide on the event model to use as soon as it creates watchers, and it 751decide on the event model to use as soon as it creates watchers, and it
612might chose the wrong one unless you load the correct one yourself. 752might chose the wrong one unless you load the correct one yourself.
613 753
614You can chose to use a rather inefficient pure-perl implementation by 754You can chose to use a pure-perl implementation by loading the
615loading the C<AnyEvent::Impl::Perl> module, which gives you similar 755C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616behaviour everywhere, but letting AnyEvent chose is generally better. 756everywhere, but letting AnyEvent chose the model is generally better.
757
758=head2 MAINLOOP EMULATION
759
760Sometimes (often for short test scripts, or even standalone programs who
761only want to use AnyEvent), you do not want to run a specific event loop.
762
763In that case, you can use a condition variable like this:
764
765 AnyEvent->condvar->recv;
766
767This has the effect of entering the event loop and looping forever.
768
769Note that usually your program has some exit condition, in which case
770it is better to use the "traditional" approach of storing a condition
771variable somewhere, waiting for it, and sending it when the program should
772exit cleanly.
773
617 774
618=head1 OTHER MODULES 775=head1 OTHER MODULES
619 776
620The following is a non-exhaustive list of additional modules that use 777The following is a non-exhaustive list of additional modules that use
621AnyEvent and can therefore be mixed easily with other AnyEvent modules 778AnyEvent and can therefore be mixed easily with other AnyEvent modules
627=item L<AnyEvent::Util> 784=item L<AnyEvent::Util>
628 785
629Contains various utility functions that replace often-used but blocking 786Contains various utility functions that replace often-used but blocking
630functions such as C<inet_aton> by event-/callback-based versions. 787functions such as C<inet_aton> by event-/callback-based versions.
631 788
789=item L<AnyEvent::Socket>
790
791Provides various utility functions for (internet protocol) sockets,
792addresses and name resolution. Also functions to create non-blocking tcp
793connections or tcp servers, with IPv6 and SRV record support and more.
794
632=item L<AnyEvent::Handle> 795=item L<AnyEvent::Handle>
633 796
634Provide read and write buffers and manages watchers for reads and writes. 797Provide read and write buffers, manages watchers for reads and writes,
798supports raw and formatted I/O, I/O queued and fully transparent and
799non-blocking SSL/TLS.
800
801=item L<AnyEvent::DNS>
802
803Provides rich asynchronous DNS resolver capabilities.
804
805=item L<AnyEvent::HTTP>
806
807A simple-to-use HTTP library that is capable of making a lot of concurrent
808HTTP requests.
635 809
636=item L<AnyEvent::HTTPD> 810=item L<AnyEvent::HTTPD>
637 811
638Provides a simple web application server framework. 812Provides a simple web application server framework.
639 813
640=item L<AnyEvent::DNS>
641
642Provides asynchronous DNS resolver capabilities, beyond what
643L<AnyEvent::Util> offers.
644
645=item L<AnyEvent::FastPing> 814=item L<AnyEvent::FastPing>
646 815
647The fastest ping in the west. 816The fastest ping in the west.
648 817
818=item L<AnyEvent::DBI>
819
820Executes L<DBI> requests asynchronously in a proxy process.
821
822=item L<AnyEvent::AIO>
823
824Truly asynchronous I/O, should be in the toolbox of every event
825programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
826together.
827
828=item L<AnyEvent::BDB>
829
830Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
831L<BDB> and AnyEvent together.
832
833=item L<AnyEvent::GPSD>
834
835A non-blocking interface to gpsd, a daemon delivering GPS information.
836
837=item L<AnyEvent::IGS>
838
839A non-blocking interface to the Internet Go Server protocol (used by
840L<App::IGS>).
841
649=item L<Net::IRC3> 842=item L<AnyEvent::IRC>
650 843
651AnyEvent based IRC client module family. 844AnyEvent based IRC client module family (replacing the older Net::IRC3).
652 845
653=item L<Net::XMPP2> 846=item L<Net::XMPP2>
654 847
655AnyEvent based XMPP (Jabber protocol) module family. 848AnyEvent based XMPP (Jabber protocol) module family.
656 849
665 858
666=item L<Coro> 859=item L<Coro>
667 860
668Has special support for AnyEvent via L<Coro::AnyEvent>. 861Has special support for AnyEvent via L<Coro::AnyEvent>.
669 862
670=item L<AnyEvent::AIO>, L<IO::AIO>
671
672Truly asynchronous I/O, should be in the toolbox of every event
673programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
674together.
675
676=item L<AnyEvent::BDB>, L<BDB>
677
678Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
679IO::AIO and AnyEvent together.
680
681=item L<IO::Lambda> 863=item L<IO::Lambda>
682 864
683The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 865The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
684 866
685=back 867=back
687=cut 869=cut
688 870
689package AnyEvent; 871package AnyEvent;
690 872
691no warnings; 873no warnings;
692use strict; 874use strict qw(vars subs);
693 875
694use Carp; 876use Carp;
695 877
696our $VERSION = '3.41'; 878our $VERSION = 4.35;
697our $MODEL; 879our $MODEL;
698 880
699our $AUTOLOAD; 881our $AUTOLOAD;
700our @ISA; 882our @ISA;
701 883
884our @REGISTRY;
885
886our $WIN32;
887
888BEGIN {
889 my $win32 = ! ! ($^O =~ /mswin32/i);
890 eval "sub WIN32(){ $win32 }";
891}
892
702our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 893our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
703 894
704our @REGISTRY; 895our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
896
897{
898 my $idx;
899 $PROTOCOL{$_} = ++$idx
900 for reverse split /\s*,\s*/,
901 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
902}
705 903
706my @models = ( 904my @models = (
707 [EV:: => AnyEvent::Impl::EV::], 905 [EV:: => AnyEvent::Impl::EV::],
708 [Event:: => AnyEvent::Impl::Event::], 906 [Event:: => AnyEvent::Impl::Event::],
709 [Tk:: => AnyEvent::Impl::Tk::],
710 [Wx:: => AnyEvent::Impl::POE::],
711 [Prima:: => AnyEvent::Impl::POE::],
712 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 907 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
713 # everything below here will not be autoprobed as the pureperl backend should work everywhere 908 # everything below here will not be autoprobed
714 [Glib:: => AnyEvent::Impl::Glib::], 909 # as the pureperl backend should work everywhere
910 # and is usually faster
911 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
912 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
715 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 913 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
716 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 914 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
717 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 915 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
916 [Wx:: => AnyEvent::Impl::POE::],
917 [Prima:: => AnyEvent::Impl::POE::],
718); 918);
719 919
720our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 920our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
721 921
722our @post_detect; 922our @post_detect;
723 923
724sub post_detect(&) { 924sub post_detect(&) {
725 my ($cb) = @_; 925 my ($cb) = @_;
730 1 930 1
731 } else { 931 } else {
732 push @post_detect, $cb; 932 push @post_detect, $cb;
733 933
734 defined wantarray 934 defined wantarray
735 ? bless \$cb, "AnyEvent::Util::Guard" 935 ? bless \$cb, "AnyEvent::Util::PostDetect"
736 : () 936 : ()
737 } 937 }
738} 938}
739 939
740sub AnyEvent::Util::Guard::DESTROY { 940sub AnyEvent::Util::PostDetect::DESTROY {
741 @post_detect = grep $_ != ${$_[0]}, @post_detect; 941 @post_detect = grep $_ != ${$_[0]}, @post_detect;
742} 942}
743 943
744sub detect() { 944sub detect() {
745 unless ($MODEL) { 945 unless ($MODEL) {
746 no strict 'refs'; 946 no strict 'refs';
947 local $SIG{__DIE__};
747 948
748 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 949 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
749 my $model = "AnyEvent::Impl::$1"; 950 my $model = "AnyEvent::Impl::$1";
750 if (eval "require $model") { 951 if (eval "require $model") {
751 $MODEL = $model; 952 $MODEL = $model;
785 $MODEL 986 $MODEL
786 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 987 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
787 } 988 }
788 } 989 }
789 990
991 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
992
790 unshift @ISA, $MODEL; 993 unshift @ISA, $MODEL;
791 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 994
995 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
792 996
793 (shift @post_detect)->() while @post_detect; 997 (shift @post_detect)->() while @post_detect;
794 } 998 }
795 999
796 $MODEL 1000 $MODEL
806 1010
807 my $class = shift; 1011 my $class = shift;
808 $class->$func (@_); 1012 $class->$func (@_);
809} 1013}
810 1014
1015# utility function to dup a filehandle. this is used by many backends
1016# to support binding more than one watcher per filehandle (they usually
1017# allow only one watcher per fd, so we dup it to get a different one).
1018sub _dupfh($$$$) {
1019 my ($poll, $fh, $r, $w) = @_;
1020
1021 # cygwin requires the fh mode to be matching, unix doesn't
1022 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1023 : $poll eq "w" ? ($w, ">")
1024 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1025
1026 open my $fh2, "$mode&" . fileno $fh
1027 or die "cannot dup() filehandle: $!";
1028
1029 # we assume CLOEXEC is already set by perl in all important cases
1030
1031 ($fh2, $rw)
1032}
1033
811package AnyEvent::Base; 1034package AnyEvent::Base;
812 1035
1036# default implementation for now and time
1037
1038BEGIN {
1039 if (eval "use Time::HiRes (); time (); 1") {
1040 *_time = \&Time::HiRes::time;
1041 # if (eval "use POSIX (); (POSIX::times())...
1042 } else {
1043 *_time = sub { time }; # epic fail
1044 }
1045}
1046
1047sub time { _time }
1048sub now { _time }
1049
813# default implementation for ->condvar 1050# default implementation for ->condvar
814 1051
815sub condvar { 1052sub condvar {
816 bless {}, AnyEvent::CondVar:: 1053 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
817} 1054}
818 1055
819# default implementation for ->signal 1056# default implementation for ->signal
820 1057
821our %SIG_CB; 1058our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1059
1060sub _signal_exec {
1061 sysread $SIGPIPE_R, my $dummy, 4;
1062
1063 while (%SIG_EV) {
1064 for (keys %SIG_EV) {
1065 delete $SIG_EV{$_};
1066 $_->() for values %{ $SIG_CB{$_} || {} };
1067 }
1068 }
1069}
822 1070
823sub signal { 1071sub signal {
824 my (undef, %arg) = @_; 1072 my (undef, %arg) = @_;
825 1073
1074 unless ($SIGPIPE_R) {
1075 require Fcntl;
1076
1077 if (AnyEvent::WIN32) {
1078 require AnyEvent::Util;
1079
1080 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1081 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1082 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1083 } else {
1084 pipe $SIGPIPE_R, $SIGPIPE_W;
1085 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1086 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1087 }
1088
1089 $SIGPIPE_R
1090 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1091
1092 # not strictly required, as $^F is normally 2, but let's make sure...
1093 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1094 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1095
1096 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1097 }
1098
826 my $signal = uc $arg{signal} 1099 my $signal = uc $arg{signal}
827 or Carp::croak "required option 'signal' is missing"; 1100 or Carp::croak "required option 'signal' is missing";
828 1101
829 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1102 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
830 $SIG{$signal} ||= sub { 1103 $SIG{$signal} ||= sub {
831 $_->() for values %{ $SIG_CB{$signal} || {} }; 1104 local $!;
1105 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1106 undef $SIG_EV{$signal};
832 }; 1107 };
833 1108
834 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1109 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
835} 1110}
836 1111
837sub AnyEvent::Base::Signal::DESTROY { 1112sub AnyEvent::Base::Signal::DESTROY {
838 my ($signal, $cb) = @{$_[0]}; 1113 my ($signal, $cb) = @{$_[0]};
839 1114
840 delete $SIG_CB{$signal}{$cb}; 1115 delete $SIG_CB{$signal}{$cb};
841 1116
842 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1117 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
843} 1118}
844 1119
845# default implementation for ->child 1120# default implementation for ->child
846 1121
847our %PID_CB; 1122our %PID_CB;
874 or Carp::croak "required option 'pid' is missing"; 1149 or Carp::croak "required option 'pid' is missing";
875 1150
876 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1151 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
877 1152
878 unless ($WNOHANG) { 1153 unless ($WNOHANG) {
879 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 1154 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
880 } 1155 }
881 1156
882 unless ($CHLD_W) { 1157 unless ($CHLD_W) {
883 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1158 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
884 # child could be a zombie already, so make at least one round 1159 # child could be a zombie already, so make at least one round
901 1176
902our @ISA = AnyEvent::CondVar::Base::; 1177our @ISA = AnyEvent::CondVar::Base::;
903 1178
904package AnyEvent::CondVar::Base; 1179package AnyEvent::CondVar::Base;
905 1180
1181use overload
1182 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1183 fallback => 1;
1184
906sub _send { 1185sub _send {
907 # nop 1186 # nop
908} 1187}
909 1188
910sub send { 1189sub send {
944 $_[0]{_ae_end_cb} = $_[1] if @_ > 1; 1223 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
945} 1224}
946 1225
947sub end { 1226sub end {
948 return if --$_[0]{_ae_counter}; 1227 return if --$_[0]{_ae_counter};
949 &{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb}; 1228 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
950} 1229}
951 1230
952# undocumented/compatibility with pre-3.4 1231# undocumented/compatibility with pre-3.4
953*broadcast = \&send; 1232*broadcast = \&send;
954*wait = \&_wait; 1233*wait = \&_wait;
1234
1235=head1 ERROR AND EXCEPTION HANDLING
1236
1237In general, AnyEvent does not do any error handling - it relies on the
1238caller to do that if required. The L<AnyEvent::Strict> module (see also
1239the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1240checking of all AnyEvent methods, however, which is highly useful during
1241development.
1242
1243As for exception handling (i.e. runtime errors and exceptions thrown while
1244executing a callback), this is not only highly event-loop specific, but
1245also not in any way wrapped by this module, as this is the job of the main
1246program.
1247
1248The pure perl event loop simply re-throws the exception (usually
1249within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1250$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1251so on.
1252
1253=head1 ENVIRONMENT VARIABLES
1254
1255The following environment variables are used by this module or its
1256submodules:
1257
1258=over 4
1259
1260=item C<PERL_ANYEVENT_VERBOSE>
1261
1262By default, AnyEvent will be completely silent except in fatal
1263conditions. You can set this environment variable to make AnyEvent more
1264talkative.
1265
1266When set to C<1> or higher, causes AnyEvent to warn about unexpected
1267conditions, such as not being able to load the event model specified by
1268C<PERL_ANYEVENT_MODEL>.
1269
1270When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1271model it chooses.
1272
1273=item C<PERL_ANYEVENT_STRICT>
1274
1275AnyEvent does not do much argument checking by default, as thorough
1276argument checking is very costly. Setting this variable to a true value
1277will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1278check the arguments passed to most method calls. If it finds any problems
1279it will croak.
1280
1281In other words, enables "strict" mode.
1282
1283Unlike C<use strict>, it is definitely recommended ot keep it off in
1284production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1285developing programs can be very useful, however.
1286
1287=item C<PERL_ANYEVENT_MODEL>
1288
1289This can be used to specify the event model to be used by AnyEvent, before
1290auto detection and -probing kicks in. It must be a string consisting
1291entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1292and the resulting module name is loaded and if the load was successful,
1293used as event model. If it fails to load AnyEvent will proceed with
1294auto detection and -probing.
1295
1296This functionality might change in future versions.
1297
1298For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1299could start your program like this:
1300
1301 PERL_ANYEVENT_MODEL=Perl perl ...
1302
1303=item C<PERL_ANYEVENT_PROTOCOLS>
1304
1305Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1306for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1307of auto probing).
1308
1309Must be set to a comma-separated list of protocols or address families,
1310current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1311used, and preference will be given to protocols mentioned earlier in the
1312list.
1313
1314This variable can effectively be used for denial-of-service attacks
1315against local programs (e.g. when setuid), although the impact is likely
1316small, as the program has to handle conenction and other failures anyways.
1317
1318Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1319but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1320- only support IPv4, never try to resolve or contact IPv6
1321addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1322IPv6, but prefer IPv6 over IPv4.
1323
1324=item C<PERL_ANYEVENT_EDNS0>
1325
1326Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1327for DNS. This extension is generally useful to reduce DNS traffic, but
1328some (broken) firewalls drop such DNS packets, which is why it is off by
1329default.
1330
1331Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1332EDNS0 in its DNS requests.
1333
1334=item C<PERL_ANYEVENT_MAX_FORKS>
1335
1336The maximum number of child processes that C<AnyEvent::Util::fork_call>
1337will create in parallel.
1338
1339=back
955 1340
956=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1341=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
957 1342
958This is an advanced topic that you do not normally need to use AnyEvent in 1343This is an advanced topic that you do not normally need to use AnyEvent in
959a module. This section is only of use to event loop authors who want to 1344a module. This section is only of use to event loop authors who want to
993 1378
994I<rxvt-unicode> also cheats a bit by not providing blocking access to 1379I<rxvt-unicode> also cheats a bit by not providing blocking access to
995condition variables: code blocking while waiting for a condition will 1380condition variables: code blocking while waiting for a condition will
996C<die>. This still works with most modules/usages, and blocking calls must 1381C<die>. This still works with most modules/usages, and blocking calls must
997not be done in an interactive application, so it makes sense. 1382not be done in an interactive application, so it makes sense.
998
999=head1 ENVIRONMENT VARIABLES
1000
1001The following environment variables are used by this module:
1002
1003=over 4
1004
1005=item C<PERL_ANYEVENT_VERBOSE>
1006
1007By default, AnyEvent will be completely silent except in fatal
1008conditions. You can set this environment variable to make AnyEvent more
1009talkative.
1010
1011When set to C<1> or higher, causes AnyEvent to warn about unexpected
1012conditions, such as not being able to load the event model specified by
1013C<PERL_ANYEVENT_MODEL>.
1014
1015When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1016model it chooses.
1017
1018=item C<PERL_ANYEVENT_MODEL>
1019
1020This can be used to specify the event model to be used by AnyEvent, before
1021autodetection and -probing kicks in. It must be a string consisting
1022entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1023and the resulting module name is loaded and if the load was successful,
1024used as event model. If it fails to load AnyEvent will proceed with
1025autodetection and -probing.
1026
1027This functionality might change in future versions.
1028
1029For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1030could start your program like this:
1031
1032 PERL_ANYEVENT_MODEL=Perl perl ...
1033
1034=back
1035 1383
1036=head1 EXAMPLE PROGRAM 1384=head1 EXAMPLE PROGRAM
1037 1385
1038The following program uses an I/O watcher to read data from STDIN, a timer 1386The following program uses an I/O watcher to read data from STDIN, a timer
1039to display a message once per second, and a condition variable to quit the 1387to display a message once per second, and a condition variable to quit the
1048 poll => 'r', 1396 poll => 'r',
1049 cb => sub { 1397 cb => sub {
1050 warn "io event <$_[0]>\n"; # will always output <r> 1398 warn "io event <$_[0]>\n"; # will always output <r>
1051 chomp (my $input = <STDIN>); # read a line 1399 chomp (my $input = <STDIN>); # read a line
1052 warn "read: $input\n"; # output what has been read 1400 warn "read: $input\n"; # output what has been read
1053 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1401 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1054 }, 1402 },
1055 ); 1403 );
1056 1404
1057 my $time_watcher; # can only be used once 1405 my $time_watcher; # can only be used once
1058 1406
1063 }); 1411 });
1064 } 1412 }
1065 1413
1066 new_timer; # create first timer 1414 new_timer; # create first timer
1067 1415
1068 $cv->wait; # wait until user enters /^q/i 1416 $cv->recv; # wait until user enters /^q/i
1069 1417
1070=head1 REAL-WORLD EXAMPLE 1418=head1 REAL-WORLD EXAMPLE
1071 1419
1072Consider the L<Net::FCP> module. It features (among others) the following 1420Consider the L<Net::FCP> module. It features (among others) the following
1073API calls, which are to freenet what HTTP GET requests are to http: 1421API calls, which are to freenet what HTTP GET requests are to http:
1123 syswrite $txn->{fh}, $txn->{request} 1471 syswrite $txn->{fh}, $txn->{request}
1124 or die "connection or write error"; 1472 or die "connection or write error";
1125 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1473 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1126 1474
1127Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1475Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1128result and signals any possible waiters that the request ahs finished: 1476result and signals any possible waiters that the request has finished:
1129 1477
1130 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1478 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1131 1479
1132 if (end-of-file or data complete) { 1480 if (end-of-file or data complete) {
1133 $txn->{result} = $txn->{buf}; 1481 $txn->{result} = $txn->{buf};
1134 $txn->{finished}->broadcast; 1482 $txn->{finished}->send;
1135 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1483 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1136 } 1484 }
1137 1485
1138The C<result> method, finally, just waits for the finished signal (if the 1486The C<result> method, finally, just waits for the finished signal (if the
1139request was already finished, it doesn't wait, of course, and returns the 1487request was already finished, it doesn't wait, of course, and returns the
1140data: 1488data:
1141 1489
1142 $txn->{finished}->wait; 1490 $txn->{finished}->recv;
1143 return $txn->{result}; 1491 return $txn->{result};
1144 1492
1145The actual code goes further and collects all errors (C<die>s, exceptions) 1493The actual code goes further and collects all errors (C<die>s, exceptions)
1146that occured during request processing. The C<result> method detects 1494that occurred during request processing. The C<result> method detects
1147whether an exception as thrown (it is stored inside the $txn object) 1495whether an exception as thrown (it is stored inside the $txn object)
1148and just throws the exception, which means connection errors and other 1496and just throws the exception, which means connection errors and other
1149problems get reported tot he code that tries to use the result, not in a 1497problems get reported tot he code that tries to use the result, not in a
1150random callback. 1498random callback.
1151 1499
1182 1530
1183 my $quit = AnyEvent->condvar; 1531 my $quit = AnyEvent->condvar;
1184 1532
1185 $fcp->txn_client_get ($url)->cb (sub { 1533 $fcp->txn_client_get ($url)->cb (sub {
1186 ... 1534 ...
1187 $quit->broadcast; 1535 $quit->send;
1188 }); 1536 });
1189 1537
1190 $quit->wait; 1538 $quit->recv;
1191 1539
1192 1540
1193=head1 BENCHMARKS 1541=head1 BENCHMARKS
1194 1542
1195To give you an idea of the performance and overheads that AnyEvent adds 1543To give you an idea of the performance and overheads that AnyEvent adds
1197of various event loops I prepared some benchmarks. 1545of various event loops I prepared some benchmarks.
1198 1546
1199=head2 BENCHMARKING ANYEVENT OVERHEAD 1547=head2 BENCHMARKING ANYEVENT OVERHEAD
1200 1548
1201Here is a benchmark of various supported event models used natively and 1549Here is a benchmark of various supported event models used natively and
1202through anyevent. The benchmark creates a lot of timers (with a zero 1550through AnyEvent. The benchmark creates a lot of timers (with a zero
1203timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1551timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1204which it is), lets them fire exactly once and destroys them again. 1552which it is), lets them fire exactly once and destroys them again.
1205 1553
1206Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1554Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1207distribution. 1555distribution.
1224all watchers, to avoid adding memory overhead. That means closure creation 1572all watchers, to avoid adding memory overhead. That means closure creation
1225and memory usage is not included in the figures. 1573and memory usage is not included in the figures.
1226 1574
1227I<invoke> is the time, in microseconds, used to invoke a simple 1575I<invoke> is the time, in microseconds, used to invoke a simple
1228callback. The callback simply counts down a Perl variable and after it was 1576callback. The callback simply counts down a Perl variable and after it was
1229invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1577invoked "watcher" times, it would C<< ->send >> a condvar once to
1230signal the end of this phase. 1578signal the end of this phase.
1231 1579
1232I<destroy> is the time, in microseconds, that it takes to destroy a single 1580I<destroy> is the time, in microseconds, that it takes to destroy a single
1233watcher. 1581watcher.
1234 1582
1235=head3 Results 1583=head3 Results
1236 1584
1237 name watchers bytes create invoke destroy comment 1585 name watchers bytes create invoke destroy comment
1238 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1586 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1239 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1587 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1240 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1588 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1241 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1589 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1242 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1590 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1243 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1591 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1244 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1592 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1245 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1593 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1246 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1594 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1247 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1595 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1248 1596
1249=head3 Discussion 1597=head3 Discussion
1250 1598
1251The benchmark does I<not> measure scalability of the event loop very 1599The benchmark does I<not> measure scalability of the event loop very
1252well. For example, a select-based event loop (such as the pure perl one) 1600well. For example, a select-based event loop (such as the pure perl one)
1330 1678
1331=back 1679=back
1332 1680
1333=head2 BENCHMARKING THE LARGE SERVER CASE 1681=head2 BENCHMARKING THE LARGE SERVER CASE
1334 1682
1335This benchmark atcually benchmarks the event loop itself. It works by 1683This benchmark actually benchmarks the event loop itself. It works by
1336creating a number of "servers": each server consists of a socketpair, a 1684creating a number of "servers": each server consists of a socket pair, a
1337timeout watcher that gets reset on activity (but never fires), and an I/O 1685timeout watcher that gets reset on activity (but never fires), and an I/O
1338watcher waiting for input on one side of the socket. Each time the socket 1686watcher waiting for input on one side of the socket. Each time the socket
1339watcher reads a byte it will write that byte to a random other "server". 1687watcher reads a byte it will write that byte to a random other "server".
1340 1688
1341The effect is that there will be a lot of I/O watchers, only part of which 1689The effect is that there will be a lot of I/O watchers, only part of which
1342are active at any one point (so there is a constant number of active 1690are active at any one point (so there is a constant number of active
1343fds for each loop iterstaion, but which fds these are is random). The 1691fds for each loop iteration, but which fds these are is random). The
1344timeout is reset each time something is read because that reflects how 1692timeout is reset each time something is read because that reflects how
1345most timeouts work (and puts extra pressure on the event loops). 1693most timeouts work (and puts extra pressure on the event loops).
1346 1694
1347In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1695In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1348(1%) are active. This mirrors the activity of large servers with many 1696(1%) are active. This mirrors the activity of large servers with many
1349connections, most of which are idle at any one point in time. 1697connections, most of which are idle at any one point in time.
1350 1698
1351Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1699Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1352distribution. 1700distribution.
1354=head3 Explanation of the columns 1702=head3 Explanation of the columns
1355 1703
1356I<sockets> is the number of sockets, and twice the number of "servers" (as 1704I<sockets> is the number of sockets, and twice the number of "servers" (as
1357each server has a read and write socket end). 1705each server has a read and write socket end).
1358 1706
1359I<create> is the time it takes to create a socketpair (which is 1707I<create> is the time it takes to create a socket pair (which is
1360nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1708nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1361 1709
1362I<request>, the most important value, is the time it takes to handle a 1710I<request>, the most important value, is the time it takes to handle a
1363single "request", that is, reading the token from the pipe and forwarding 1711single "request", that is, reading the token from the pipe and forwarding
1364it to another server. This includes deleting the old timeout and creating 1712it to another server. This includes deleting the old timeout and creating
1437speed most when you have lots of watchers, not when you only have a few of 1785speed most when you have lots of watchers, not when you only have a few of
1438them). 1786them).
1439 1787
1440EV is again fastest. 1788EV is again fastest.
1441 1789
1442Perl again comes second. It is noticably faster than the C-based event 1790Perl again comes second. It is noticeably faster than the C-based event
1443loops Event and Glib, although the difference is too small to really 1791loops Event and Glib, although the difference is too small to really
1444matter. 1792matter.
1445 1793
1446POE also performs much better in this case, but is is still far behind the 1794POE also performs much better in this case, but is is still far behind the
1447others. 1795others.
1452 1800
1453=item * C-based event loops perform very well with small number of 1801=item * C-based event loops perform very well with small number of
1454watchers, as the management overhead dominates. 1802watchers, as the management overhead dominates.
1455 1803
1456=back 1804=back
1805
1806
1807=head1 SIGNALS
1808
1809AnyEvent currently installs handlers for these signals:
1810
1811=over 4
1812
1813=item SIGCHLD
1814
1815A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1816emulation for event loops that do not support them natively. Also, some
1817event loops install a similar handler.
1818
1819=item SIGPIPE
1820
1821A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1822when AnyEvent gets loaded.
1823
1824The rationale for this is that AnyEvent users usually do not really depend
1825on SIGPIPE delivery (which is purely an optimisation for shell use, or
1826badly-written programs), but C<SIGPIPE> can cause spurious and rare
1827program exits as a lot of people do not expect C<SIGPIPE> when writing to
1828some random socket.
1829
1830The rationale for installing a no-op handler as opposed to ignoring it is
1831that this way, the handler will be restored to defaults on exec.
1832
1833Feel free to install your own handler, or reset it to defaults.
1834
1835=back
1836
1837=cut
1838
1839$SIG{PIPE} = sub { }
1840 unless defined $SIG{PIPE};
1457 1841
1458 1842
1459=head1 FORK 1843=head1 FORK
1460 1844
1461Most event libraries are not fork-safe. The ones who are usually are 1845Most event libraries are not fork-safe. The ones who are usually are
1476specified in the variable. 1860specified in the variable.
1477 1861
1478You can make AnyEvent completely ignore this variable by deleting it 1862You can make AnyEvent completely ignore this variable by deleting it
1479before the first watcher gets created, e.g. with a C<BEGIN> block: 1863before the first watcher gets created, e.g. with a C<BEGIN> block:
1480 1864
1481 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1865 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1482 1866
1483 use AnyEvent; 1867 use AnyEvent;
1484 1868
1485Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1869Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1486be used to probe what backend is used and gain other information (which is 1870be used to probe what backend is used and gain other information (which is
1487probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1871probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1872$ENV{PERL_ANYEGENT_STRICT}.
1873
1874
1875=head1 BUGS
1876
1877Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1878to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1879and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1880memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1881pronounced).
1488 1882
1489 1883
1490=head1 SEE ALSO 1884=head1 SEE ALSO
1885
1886Utility functions: L<AnyEvent::Util>.
1491 1887
1492Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1888Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1493L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1889L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1494 1890
1495Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1891Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1496L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1892L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1497L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1893L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1498L<AnyEvent::Impl::POE>. 1894L<AnyEvent::Impl::POE>.
1499 1895
1896Non-blocking file handles, sockets, TCP clients and
1897servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1898
1899Asynchronous DNS: L<AnyEvent::DNS>.
1900
1500Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1901Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1501 1902
1502Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1903Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1503 1904
1504 1905
1505=head1 AUTHOR 1906=head1 AUTHOR
1506 1907
1507 Marc Lehmann <schmorp@schmorp.de> 1908 Marc Lehmann <schmorp@schmorp.de>
1508 http://home.schmorp.de/ 1909 http://home.schmorp.de/
1509 1910
1510=cut 1911=cut
1511 1912
15121 19131
1513 1914

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