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Revision 1.206 by root, Mon Apr 20 14:34:18 2009 UTC

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, 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
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 enormous 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
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=item AnyEvent->now_update
326
327Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
328the current time for each loop iteration (see the discussion of L<<
329AnyEvent->now >>, above).
330
331When a callback runs for a long time (or when the process sleeps), then
332this "current" time will differ substantially from the real time, which
333might affect timers and time-outs.
334
335When this is the case, you can call this method, which will update the
336event loop's idea of "current time".
337
338Note that updating the time I<might> cause some events to be handled.
339
340=back
341
232=head2 SIGNAL WATCHERS 342=head2 SIGNAL WATCHERS
233 343
234You can watch for signals using a signal watcher, C<signal> is the signal 344You 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 345I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236be invoked whenever a signal occurs. 346callback to be invoked whenever a signal occurs.
237 347
238Although the callback might get passed parameters, their value and 348Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 349presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 350callbacks cannot use arguments passed to signal watcher callbacks.
241 351
257=head2 CHILD PROCESS WATCHERS 367=head2 CHILD PROCESS WATCHERS
258 368
259You can also watch on a child process exit and catch its exit status. 369You can also watch on a child process exit and catch its exit status.
260 370
261The child process is specified by the C<pid> argument (if set to C<0>, it 371The 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 372watches for any child process exit). The watcher will triggered only when
263as status change for the child are received. This works by installing a 373the 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 374any trace events (stopped/continued).
265and exit status (as returned by waitpid), so unlike other watcher types, 375
266you I<can> rely on child watcher callback arguments. 376The callback will be called with the pid and exit status (as returned by
377waitpid), so unlike other watcher types, you I<can> rely on child watcher
378callback arguments.
379
380This watcher type works by installing a signal handler for C<SIGCHLD>,
381and since it cannot be shared, nothing else should use SIGCHLD or reap
382random child processes (waiting for specific child processes, e.g. inside
383C<system>, is just fine).
267 384
268There is a slight catch to child watchers, however: you usually start them 385There 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 386I<after> the child process was created, and this means the process could
270have exited already (and no SIGCHLD will be sent anymore). 387have exited already (and no SIGCHLD will be sent anymore).
271 388
277AnyEvent program, you I<have> to create at least one watcher before you 394AnyEvent program, you I<have> to create at least one watcher before you
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 395C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 396
280Example: fork a process and wait for it 397Example: fork a process and wait for it
281 398
282 my $done = AnyEvent->condvar; 399 my $done = AnyEvent->condvar;
283 400
284 my $pid = fork or exit 5; 401 my $pid = fork or exit 5;
285 402
286 my $w = AnyEvent->child ( 403 my $w = AnyEvent->child (
287 pid => $pid, 404 pid => $pid,
288 cb => sub { 405 cb => sub {
289 my ($pid, $status) = @_; 406 my ($pid, $status) = @_;
290 warn "pid $pid exited with status $status"; 407 warn "pid $pid exited with status $status";
291 $done->send; 408 $done->send;
292 }, 409 },
293 ); 410 );
294 411
295 # do something else, then wait for process exit 412 # do something else, then wait for process exit
296 $done->recv; 413 $done->recv;
297 414
298=head2 CONDITION VARIABLES 415=head2 CONDITION VARIABLES
299 416
300If you are familiar with some event loops you will know that all of them 417If 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 418require you to run some blocking "loop", "run" or similar function that
307The instrument to do that is called a "condition variable", so called 424The instrument to do that is called a "condition variable", so called
308because they represent a condition that must become true. 425because they represent a condition that must become true.
309 426
310Condition variables can be created by calling the C<< AnyEvent->condvar 427Condition variables can be created by calling the C<< AnyEvent->condvar
311>> method, usually without arguments. The only argument pair allowed is 428>> method, usually without arguments. The only argument pair allowed is
429
312C<cb>, which specifies a callback to be called when the condition variable 430C<cb>, which specifies a callback to be called when the condition variable
313becomes true. 431becomes true, with the condition variable as the first argument (but not
432the results).
314 433
315After creation, the condition variable is "false" until it becomes "true" 434After creation, the condition variable is "false" until it becomes "true"
316by calling the C<send> method (or calling the condition variable as if it 435by calling the C<send> method (or calling the condition variable as if it
317were a callback, read about the caveats in the description for the C<< 436were a callback, read about the caveats in the description for the C<<
318->send >> method). 437->send >> method).
374 493
375 my $done = AnyEvent->condvar; 494 my $done = AnyEvent->condvar;
376 my $delay = AnyEvent->timer (after => 5, cb => $done); 495 my $delay = AnyEvent->timer (after => 5, cb => $done);
377 $done->recv; 496 $done->recv;
378 497
498Example: Imagine an API that returns a condvar and doesn't support
499callbacks. This is how you make a synchronous call, for example from
500the main program:
501
502 use AnyEvent::CouchDB;
503
504 ...
505
506 my @info = $couchdb->info->recv;
507
508And this is how you would just ste a callback to be called whenever the
509results are available:
510
511 $couchdb->info->cb (sub {
512 my @info = $_[0]->recv;
513 });
514
379=head3 METHODS FOR PRODUCERS 515=head3 METHODS FOR PRODUCERS
380 516
381These methods should only be used by the producing side, i.e. the 517These methods should only be used by the producing side, i.e. the
382code/module that eventually sends the signal. Note that it is also 518code/module that eventually sends the signal. Note that it is also
383the producer side which creates the condvar in most cases, but it isn't 519the producer side which creates the condvar in most cases, but it isn't
516=item $bool = $cv->ready 652=item $bool = $cv->ready
517 653
518Returns true when the condition is "true", i.e. whether C<send> or 654Returns true when the condition is "true", i.e. whether C<send> or
519C<croak> have been called. 655C<croak> have been called.
520 656
521=item $cb = $cv->cb ([new callback]) 657=item $cb = $cv->cb ($cb->($cv))
522 658
523This is a mutator function that returns the callback set and optionally 659This is a mutator function that returns the callback set and optionally
524replaces it before doing so. 660replaces it before doing so.
525 661
526The callback will be called when the condition becomes "true", i.e. when 662The callback will be called when the condition becomes "true", i.e. when
527C<send> or C<croak> are called. Calling C<recv> inside the callback 663C<send> or C<croak> are called, with the only argument being the condition
528or at any later time is guaranteed not to block. 664variable itself. Calling C<recv> inside the callback or at any later time
665is guaranteed not to block.
529 666
530=back 667=back
531 668
532=head1 GLOBAL VARIABLES AND FUNCTIONS 669=head1 GLOBAL VARIABLES AND FUNCTIONS
533 670
662=item L<AnyEvent::Util> 799=item L<AnyEvent::Util>
663 800
664Contains various utility functions that replace often-used but blocking 801Contains various utility functions that replace often-used but blocking
665functions such as C<inet_aton> by event-/callback-based versions. 802functions such as C<inet_aton> by event-/callback-based versions.
666 803
667=item L<AnyEvent::Handle>
668
669Provide read and write buffers and manages watchers for reads and writes.
670
671=item L<AnyEvent::Socket> 804=item L<AnyEvent::Socket>
672 805
673Provides various utility functions for (internet protocol) sockets, 806Provides various utility functions for (internet protocol) sockets,
674addresses and name resolution. Also functions to create non-blocking tcp 807addresses and name resolution. Also functions to create non-blocking tcp
675connections or tcp servers, with IPv6 and SRV record support and more. 808connections or tcp servers, with IPv6 and SRV record support and more.
676 809
810=item L<AnyEvent::Handle>
811
812Provide read and write buffers, manages watchers for reads and writes,
813supports raw and formatted I/O, I/O queued and fully transparent and
814non-blocking SSL/TLS.
815
677=item L<AnyEvent::DNS> 816=item L<AnyEvent::DNS>
678 817
679Provides rich asynchronous DNS resolver capabilities. 818Provides rich asynchronous DNS resolver capabilities.
680 819
820=item L<AnyEvent::HTTP>
821
822A simple-to-use HTTP library that is capable of making a lot of concurrent
823HTTP requests.
824
681=item L<AnyEvent::HTTPD> 825=item L<AnyEvent::HTTPD>
682 826
683Provides a simple web application server framework. 827Provides a simple web application server framework.
684 828
685=item L<AnyEvent::FastPing> 829=item L<AnyEvent::FastPing>
686 830
687The fastest ping in the west. 831The fastest ping in the west.
688 832
833=item L<AnyEvent::DBI>
834
835Executes L<DBI> requests asynchronously in a proxy process.
836
837=item L<AnyEvent::AIO>
838
839Truly asynchronous I/O, should be in the toolbox of every event
840programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
841together.
842
843=item L<AnyEvent::BDB>
844
845Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
846L<BDB> and AnyEvent together.
847
848=item L<AnyEvent::GPSD>
849
850A non-blocking interface to gpsd, a daemon delivering GPS information.
851
852=item L<AnyEvent::IGS>
853
854A non-blocking interface to the Internet Go Server protocol (used by
855L<App::IGS>).
856
689=item L<Net::IRC3> 857=item L<AnyEvent::IRC>
690 858
691AnyEvent based IRC client module family. 859AnyEvent based IRC client module family (replacing the older Net::IRC3).
692 860
693=item L<Net::XMPP2> 861=item L<Net::XMPP2>
694 862
695AnyEvent based XMPP (Jabber protocol) module family. 863AnyEvent based XMPP (Jabber protocol) module family.
696 864
705 873
706=item L<Coro> 874=item L<Coro>
707 875
708Has special support for AnyEvent via L<Coro::AnyEvent>. 876Has special support for AnyEvent via L<Coro::AnyEvent>.
709 877
710=item L<AnyEvent::AIO>, L<IO::AIO>
711
712Truly asynchronous I/O, should be in the toolbox of every event
713programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714together.
715
716=item L<AnyEvent::BDB>, L<BDB>
717
718Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719IO::AIO and AnyEvent together.
720
721=item L<IO::Lambda> 878=item L<IO::Lambda>
722 879
723The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 880The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724 881
725=back 882=back
727=cut 884=cut
728 885
729package AnyEvent; 886package AnyEvent;
730 887
731no warnings; 888no warnings;
732use strict; 889use strict qw(vars subs);
733 890
734use Carp; 891use Carp;
735 892
736our $VERSION = '4.04'; 893our $VERSION = 4.352;
737our $MODEL; 894our $MODEL;
738 895
739our $AUTOLOAD; 896our $AUTOLOAD;
740our @ISA; 897our @ISA;
741 898
755{ 912{
756 my $idx; 913 my $idx;
757 $PROTOCOL{$_} = ++$idx 914 $PROTOCOL{$_} = ++$idx
758 for reverse split /\s*,\s*/, 915 for reverse split /\s*,\s*/,
759 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 916 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
760}
761
762sub import {
763 shift;
764 return unless @_;
765
766 my $pkg = caller;
767
768 no strict 'refs';
769
770 for (@_) {
771 *{"$pkg\::WIN32"} = *WIN32 if $_ eq "WIN32";
772 }
773} 917}
774 918
775my @models = ( 919my @models = (
776 [EV:: => AnyEvent::Impl::EV::], 920 [EV:: => AnyEvent::Impl::EV::],
777 [Event:: => AnyEvent::Impl::Event::], 921 [Event:: => AnyEvent::Impl::Event::],
786 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 930 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
787 [Wx:: => AnyEvent::Impl::POE::], 931 [Wx:: => AnyEvent::Impl::POE::],
788 [Prima:: => AnyEvent::Impl::POE::], 932 [Prima:: => AnyEvent::Impl::POE::],
789); 933);
790 934
791our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 935our %method = map +($_ => 1),
936 qw(io timer time now now_update signal child condvar one_event DESTROY);
792 937
793our @post_detect; 938our @post_detect;
794 939
795sub post_detect(&) { 940sub post_detect(&) {
796 my ($cb) = @_; 941 my ($cb) = @_;
853 last; 998 last;
854 } 999 }
855 } 1000 }
856 1001
857 $MODEL 1002 $MODEL
858 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 1003 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
859 } 1004 }
860 } 1005 }
861 1006
1007 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1008
862 unshift @ISA, $MODEL; 1009 unshift @ISA, $MODEL;
863 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 1010
1011 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
864 1012
865 (shift @post_detect)->() while @post_detect; 1013 (shift @post_detect)->() while @post_detect;
866 } 1014 }
867 1015
868 $MODEL 1016 $MODEL
878 1026
879 my $class = shift; 1027 my $class = shift;
880 $class->$func (@_); 1028 $class->$func (@_);
881} 1029}
882 1030
1031# utility function to dup a filehandle. this is used by many backends
1032# to support binding more than one watcher per filehandle (they usually
1033# allow only one watcher per fd, so we dup it to get a different one).
1034sub _dupfh($$$$) {
1035 my ($poll, $fh, $r, $w) = @_;
1036
1037 # cygwin requires the fh mode to be matching, unix doesn't
1038 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1039 : $poll eq "w" ? ($w, ">")
1040 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1041
1042 open my $fh2, "$mode&" . fileno $fh
1043 or die "cannot dup() filehandle: $!,";
1044
1045 # we assume CLOEXEC is already set by perl in all important cases
1046
1047 ($fh2, $rw)
1048}
1049
883package AnyEvent::Base; 1050package AnyEvent::Base;
1051
1052# default implementations for many methods
1053
1054BEGIN {
1055 if (eval "use Time::HiRes (); time (); 1") {
1056 *_time = \&Time::HiRes::time;
1057 # if (eval "use POSIX (); (POSIX::times())...
1058 } else {
1059 *_time = sub { time }; # epic fail
1060 }
1061}
1062
1063sub time { _time }
1064sub now { _time }
1065sub now_update { }
884 1066
885# default implementation for ->condvar 1067# default implementation for ->condvar
886 1068
887sub condvar { 1069sub condvar {
888 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1070 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
889} 1071}
890 1072
891# default implementation for ->signal 1073# default implementation for ->signal
892 1074
893our %SIG_CB; 1075our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1076
1077sub _signal_exec {
1078 sysread $SIGPIPE_R, my $dummy, 4;
1079
1080 while (%SIG_EV) {
1081 for (keys %SIG_EV) {
1082 delete $SIG_EV{$_};
1083 $_->() for values %{ $SIG_CB{$_} || {} };
1084 }
1085 }
1086}
894 1087
895sub signal { 1088sub signal {
896 my (undef, %arg) = @_; 1089 my (undef, %arg) = @_;
897 1090
1091 unless ($SIGPIPE_R) {
1092 require Fcntl;
1093
1094 if (AnyEvent::WIN32) {
1095 require AnyEvent::Util;
1096
1097 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1098 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1099 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1100 } else {
1101 pipe $SIGPIPE_R, $SIGPIPE_W;
1102 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1103 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1104 }
1105
1106 $SIGPIPE_R
1107 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1108
1109 # not strictly required, as $^F is normally 2, but let's make sure...
1110 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1111 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1112
1113 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1114 }
1115
898 my $signal = uc $arg{signal} 1116 my $signal = uc $arg{signal}
899 or Carp::croak "required option 'signal' is missing"; 1117 or Carp::croak "required option 'signal' is missing";
900 1118
901 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1119 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
902 $SIG{$signal} ||= sub { 1120 $SIG{$signal} ||= sub {
903 $_->() for values %{ $SIG_CB{$signal} || {} }; 1121 local $!;
1122 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1123 undef $SIG_EV{$signal};
904 }; 1124 };
905 1125
906 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1126 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
907} 1127}
908 1128
909sub AnyEvent::Base::Signal::DESTROY { 1129sub AnyEvent::Base::Signal::DESTROY {
910 my ($signal, $cb) = @{$_[0]}; 1130 my ($signal, $cb) = @{$_[0]};
911 1131
912 delete $SIG_CB{$signal}{$cb}; 1132 delete $SIG_CB{$signal}{$cb};
913 1133
914 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1134 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
915} 1135}
916 1136
917# default implementation for ->child 1137# default implementation for ->child
918 1138
919our %PID_CB; 1139our %PID_CB;
1027 1247
1028# undocumented/compatibility with pre-3.4 1248# undocumented/compatibility with pre-3.4
1029*broadcast = \&send; 1249*broadcast = \&send;
1030*wait = \&_wait; 1250*wait = \&_wait;
1031 1251
1252=head1 ERROR AND EXCEPTION HANDLING
1253
1254In general, AnyEvent does not do any error handling - it relies on the
1255caller to do that if required. The L<AnyEvent::Strict> module (see also
1256the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1257checking of all AnyEvent methods, however, which is highly useful during
1258development.
1259
1260As for exception handling (i.e. runtime errors and exceptions thrown while
1261executing a callback), this is not only highly event-loop specific, but
1262also not in any way wrapped by this module, as this is the job of the main
1263program.
1264
1265The pure perl event loop simply re-throws the exception (usually
1266within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1267$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1268so on.
1269
1270=head1 ENVIRONMENT VARIABLES
1271
1272The following environment variables are used by this module or its
1273submodules:
1274
1275=over 4
1276
1277=item C<PERL_ANYEVENT_VERBOSE>
1278
1279By default, AnyEvent will be completely silent except in fatal
1280conditions. You can set this environment variable to make AnyEvent more
1281talkative.
1282
1283When set to C<1> or higher, causes AnyEvent to warn about unexpected
1284conditions, such as not being able to load the event model specified by
1285C<PERL_ANYEVENT_MODEL>.
1286
1287When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1288model it chooses.
1289
1290=item C<PERL_ANYEVENT_STRICT>
1291
1292AnyEvent does not do much argument checking by default, as thorough
1293argument checking is very costly. Setting this variable to a true value
1294will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1295check the arguments passed to most method calls. If it finds any problems
1296it will croak.
1297
1298In other words, enables "strict" mode.
1299
1300Unlike C<use strict>, it is definitely recommended ot keep it off in
1301production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1302developing programs can be very useful, however.
1303
1304=item C<PERL_ANYEVENT_MODEL>
1305
1306This can be used to specify the event model to be used by AnyEvent, before
1307auto detection and -probing kicks in. It must be a string consisting
1308entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1309and the resulting module name is loaded and if the load was successful,
1310used as event model. If it fails to load AnyEvent will proceed with
1311auto detection and -probing.
1312
1313This functionality might change in future versions.
1314
1315For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1316could start your program like this:
1317
1318 PERL_ANYEVENT_MODEL=Perl perl ...
1319
1320=item C<PERL_ANYEVENT_PROTOCOLS>
1321
1322Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1323for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1324of auto probing).
1325
1326Must be set to a comma-separated list of protocols or address families,
1327current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1328used, and preference will be given to protocols mentioned earlier in the
1329list.
1330
1331This variable can effectively be used for denial-of-service attacks
1332against local programs (e.g. when setuid), although the impact is likely
1333small, as the program has to handle conenction and other failures anyways.
1334
1335Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1336but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1337- only support IPv4, never try to resolve or contact IPv6
1338addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1339IPv6, but prefer IPv6 over IPv4.
1340
1341=item C<PERL_ANYEVENT_EDNS0>
1342
1343Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1344for DNS. This extension is generally useful to reduce DNS traffic, but
1345some (broken) firewalls drop such DNS packets, which is why it is off by
1346default.
1347
1348Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1349EDNS0 in its DNS requests.
1350
1351=item C<PERL_ANYEVENT_MAX_FORKS>
1352
1353The maximum number of child processes that C<AnyEvent::Util::fork_call>
1354will create in parallel.
1355
1356=back
1357
1032=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1358=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1033 1359
1034This is an advanced topic that you do not normally need to use AnyEvent in 1360This is an advanced topic that you do not normally need to use AnyEvent in
1035a module. This section is only of use to event loop authors who want to 1361a module. This section is only of use to event loop authors who want to
1036provide AnyEvent compatibility. 1362provide AnyEvent compatibility.
1069 1395
1070I<rxvt-unicode> also cheats a bit by not providing blocking access to 1396I<rxvt-unicode> also cheats a bit by not providing blocking access to
1071condition variables: code blocking while waiting for a condition will 1397condition variables: code blocking while waiting for a condition will
1072C<die>. This still works with most modules/usages, and blocking calls must 1398C<die>. This still works with most modules/usages, and blocking calls must
1073not be done in an interactive application, so it makes sense. 1399not be done in an interactive application, so it makes sense.
1074
1075=head1 ENVIRONMENT VARIABLES
1076
1077The following environment variables are used by this module:
1078
1079=over 4
1080
1081=item C<PERL_ANYEVENT_VERBOSE>
1082
1083By default, AnyEvent will be completely silent except in fatal
1084conditions. You can set this environment variable to make AnyEvent more
1085talkative.
1086
1087When set to C<1> or higher, causes AnyEvent to warn about unexpected
1088conditions, such as not being able to load the event model specified by
1089C<PERL_ANYEVENT_MODEL>.
1090
1091When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1092model it chooses.
1093
1094=item C<PERL_ANYEVENT_MODEL>
1095
1096This can be used to specify the event model to be used by AnyEvent, before
1097auto detection and -probing kicks in. It must be a string consisting
1098entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1099and the resulting module name is loaded and if the load was successful,
1100used as event model. If it fails to load AnyEvent will proceed with
1101auto detection and -probing.
1102
1103This functionality might change in future versions.
1104
1105For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1106could start your program like this:
1107
1108 PERL_ANYEVENT_MODEL=Perl perl ...
1109
1110=item C<PERL_ANYEVENT_PROTOCOLS>
1111
1112Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1113for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1114of auto probing).
1115
1116Must be set to a comma-separated list of protocols or address families,
1117current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1118used, and preference will be given to protocols mentioned earlier in the
1119list.
1120
1121This variable can effectively be used for denial-of-service attacks
1122against local programs (e.g. when setuid), although the impact is likely
1123small, as the program has to handle connection errors already-
1124
1125Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1126but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1127- only support IPv4, never try to resolve or contact IPv6
1128addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1129IPv6, but prefer IPv6 over IPv4.
1130
1131=item C<PERL_ANYEVENT_EDNS0>
1132
1133Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1134for DNS. This extension is generally useful to reduce DNS traffic, but
1135some (broken) firewalls drop such DNS packets, which is why it is off by
1136default.
1137
1138Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1139EDNS0 in its DNS requests.
1140
1141=back
1142 1400
1143=head1 EXAMPLE PROGRAM 1401=head1 EXAMPLE PROGRAM
1144 1402
1145The following program uses an I/O watcher to read data from STDIN, a timer 1403The following program uses an I/O watcher to read data from STDIN, a timer
1146to display a message once per second, and a condition variable to quit the 1404to display a message once per second, and a condition variable to quit the
1340watcher. 1598watcher.
1341 1599
1342=head3 Results 1600=head3 Results
1343 1601
1344 name watchers bytes create invoke destroy comment 1602 name watchers bytes create invoke destroy comment
1345 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1603 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1346 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1604 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1347 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1605 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1348 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1606 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1349 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1607 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1350 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1608 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1351 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1609 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1352 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1610 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1353 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1611 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1354 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1612 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1355 1613
1356=head3 Discussion 1614=head3 Discussion
1357 1615
1358The benchmark does I<not> measure scalability of the event loop very 1616The benchmark does I<not> measure scalability of the event loop very
1359well. For example, a select-based event loop (such as the pure perl one) 1617well. For example, a select-based event loop (such as the pure perl one)
1561watchers, as the management overhead dominates. 1819watchers, as the management overhead dominates.
1562 1820
1563=back 1821=back
1564 1822
1565 1823
1824=head1 SIGNALS
1825
1826AnyEvent currently installs handlers for these signals:
1827
1828=over 4
1829
1830=item SIGCHLD
1831
1832A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1833emulation for event loops that do not support them natively. Also, some
1834event loops install a similar handler.
1835
1836=item SIGPIPE
1837
1838A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1839when AnyEvent gets loaded.
1840
1841The rationale for this is that AnyEvent users usually do not really depend
1842on SIGPIPE delivery (which is purely an optimisation for shell use, or
1843badly-written programs), but C<SIGPIPE> can cause spurious and rare
1844program exits as a lot of people do not expect C<SIGPIPE> when writing to
1845some random socket.
1846
1847The rationale for installing a no-op handler as opposed to ignoring it is
1848that this way, the handler will be restored to defaults on exec.
1849
1850Feel free to install your own handler, or reset it to defaults.
1851
1852=back
1853
1854=cut
1855
1856$SIG{PIPE} = sub { }
1857 unless defined $SIG{PIPE};
1858
1859
1566=head1 FORK 1860=head1 FORK
1567 1861
1568Most event libraries are not fork-safe. The ones who are usually are 1862Most event libraries are not fork-safe. The ones who are usually are
1569because they rely on inefficient but fork-safe C<select> or C<poll> 1863because they rely on inefficient but fork-safe C<select> or C<poll>
1570calls. Only L<EV> is fully fork-aware. 1864calls. Only L<EV> is fully fork-aware.
1583specified in the variable. 1877specified in the variable.
1584 1878
1585You can make AnyEvent completely ignore this variable by deleting it 1879You can make AnyEvent completely ignore this variable by deleting it
1586before the first watcher gets created, e.g. with a C<BEGIN> block: 1880before the first watcher gets created, e.g. with a C<BEGIN> block:
1587 1881
1588 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1882 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1589 1883
1590 use AnyEvent; 1884 use AnyEvent;
1591 1885
1592Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1886Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1593be used to probe what backend is used and gain other information (which is 1887be used to probe what backend is used and gain other information (which is
1594probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1888probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1889$ENV{PERL_ANYEGENT_STRICT}.
1890
1891
1892=head1 BUGS
1893
1894Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1895to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1896and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1897memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1898pronounced).
1595 1899
1596 1900
1597=head1 SEE ALSO 1901=head1 SEE ALSO
1598 1902
1599Utility functions: L<AnyEvent::Util>. 1903Utility functions: L<AnyEvent::Util>.
1616Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 1920Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1617 1921
1618 1922
1619=head1 AUTHOR 1923=head1 AUTHOR
1620 1924
1621 Marc Lehmann <schmorp@schmorp.de> 1925 Marc Lehmann <schmorp@schmorp.de>
1622 http://home.schmorp.de/ 1926 http://home.schmorp.de/
1623 1927
1624=cut 1928=cut
1625 1929
16261 19301
1627 1931

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