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Revision 1.199 by root, Fri Mar 27 10:49:50 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
121These watchers are normal Perl objects with normal Perl lifetime. After 137These watchers are normal Perl objects with normal Perl lifetime. After
122creating a watcher it will immediately "watch" for events and invoke the 138creating a watcher it will immediately "watch" for events and invoke the
123callback when the event occurs (of course, only when the event model 139callback when the event occurs (of course, only when the event model
124is in control). 140is in control).
125 141
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
126To 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
127variable 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
128to it). 150to it).
129 151
130All 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.
132Many watchers either are used with "recursion" (repeating timers for 154Many watchers either are used with "recursion" (repeating timers for
133example), or need to refer to their watcher object in other ways. 155example), or need to refer to their watcher object in other ways.
134 156
135An any way to achieve that is this pattern: 157An any way to achieve that is this pattern:
136 158
137 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 159 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138 # you can use $w here, for example to undef it 160 # you can use $w here, for example to undef it
139 undef $w; 161 undef $w;
140 }); 162 });
141 163
142Note 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,
143my variables are only visible after the statement in which they are 165my variables are only visible after the statement in which they are
144declared. 166declared.
145 167
146=head2 I/O WATCHERS 168=head2 I/O WATCHERS
147 169
148You 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
149with the following mandatory key-value pairs as arguments: 171with the following mandatory key-value pairs as arguments:
150 172
151C<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
152for 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
153which creates a watcher waiting for "r"eadable or "w"ritable events, 181watcher waiting for "r"eadable or "w"ritable events, respectively.
182
154respectively. 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.
155becomes ready.
156 184
157Although the callback might get passed parameters, their value and 185Although the callback might get passed parameters, their value and
158presence is undefined and you cannot rely on them. Portable AnyEvent 186presence is undefined and you cannot rely on them. Portable AnyEvent
159callbacks cannot use arguments passed to I/O watcher callbacks. 187callbacks cannot use arguments passed to I/O watcher callbacks.
160 188
164 192
165Some event loops issue spurious readyness notifications, so you should 193Some event loops issue spurious readyness notifications, so you should
166always use non-blocking calls when reading/writing from/to your file 194always use non-blocking calls when reading/writing from/to your file
167handles. 195handles.
168 196
169Example:
170
171 # 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
172 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 200 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173 chomp (my $input = <STDIN>); 201 chomp (my $input = <STDIN>);
174 warn "read: $input\n"; 202 warn "read: $input\n";
175 undef $w; 203 undef $w;
176 }); 204 });
186 214
187Although the callback might get passed parameters, their value and 215Although the callback might get passed parameters, their value and
188presence is undefined and you cannot rely on them. Portable AnyEvent 216presence is undefined and you cannot rely on them. Portable AnyEvent
189callbacks cannot use arguments passed to time watcher callbacks. 217callbacks cannot use arguments passed to time watcher callbacks.
190 218
191The 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
192timer 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
193and 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.
194 224
195Example: 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.
196 228
197 # fire an event after 7.7 seconds 229Example: fire an event after 7.7 seconds.
230
198 my $w = AnyEvent->timer (after => 7.7, cb => sub { 231 my $w = AnyEvent->timer (after => 7.7, cb => sub {
199 warn "timeout\n"; 232 warn "timeout\n";
200 }); 233 });
201 234
202 # to cancel the timer: 235 # to cancel the timer:
203 undef $w; 236 undef $w;
204 237
205Example 2:
206
207 # fire an event after 0.5 seconds, then roughly every second 238Example 2: fire an event after 0.5 seconds, then roughly every second.
208 my $w;
209 239
210 my $cb = sub {
211 # cancel the old timer while creating a new one
212 $w = AnyEvent->timer (after => 1, cb => $cb); 240 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
241 warn "timeout\n";
213 }; 242 };
214
215 # start the "loop" by creating the first watcher
216 $w = AnyEvent->timer (after => 0.5, cb => $cb);
217 243
218=head3 TIMING ISSUES 244=head3 TIMING ISSUES
219 245
220There 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
221in 10 seconds") and based on wallclock time (absolute, "fire at 12 247in 10 seconds") and based on wallclock time (absolute, "fire at 12
233timers. 259timers.
234 260
235AnyEvent always prefers relative timers, if available, matching the 261AnyEvent always prefers relative timers, if available, matching the
236AnyEvent API. 262AnyEvent API.
237 263
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
238=head2 SIGNAL WATCHERS 327=head2 SIGNAL WATCHERS
239 328
240You 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
241I<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
242be invoked whenever a signal occurs. 331callback to be invoked whenever a signal occurs.
243 332
244Although the callback might get passed parameters, their value and 333Although the callback might get passed parameters, their value and
245presence is undefined and you cannot rely on them. Portable AnyEvent 334presence is undefined and you cannot rely on them. Portable AnyEvent
246callbacks cannot use arguments passed to signal watcher callbacks. 335callbacks cannot use arguments passed to signal watcher callbacks.
247 336
263=head2 CHILD PROCESS WATCHERS 352=head2 CHILD PROCESS WATCHERS
264 353
265You 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.
266 355
267The 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
268watches for any child process exit). The watcher will trigger as often 357watches for any child process exit). The watcher will triggered only when
269as 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
270signal handler for C<SIGCHLD>. The callback will be called with the pid 359any trace events (stopped/continued).
271and exit status (as returned by waitpid), so unlike other watcher types, 360
272you 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).
273 369
274There 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
275I<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
276have exited already (and no SIGCHLD will be sent anymore). 372have exited already (and no SIGCHLD will be sent anymore).
277 373
283AnyEvent 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
284C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 380C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
285 381
286Example: fork a process and wait for it 382Example: fork a process and wait for it
287 383
288 my $done = AnyEvent->condvar; 384 my $done = AnyEvent->condvar;
289 385
290 my $pid = fork or exit 5; 386 my $pid = fork or exit 5;
291 387
292 my $w = AnyEvent->child ( 388 my $w = AnyEvent->child (
293 pid => $pid, 389 pid => $pid,
294 cb => sub { 390 cb => sub {
295 my ($pid, $status) = @_; 391 my ($pid, $status) = @_;
296 warn "pid $pid exited with status $status"; 392 warn "pid $pid exited with status $status";
297 $done->send; 393 $done->send;
298 }, 394 },
299 ); 395 );
300 396
301 # do something else, then wait for process exit 397 # do something else, then wait for process exit
302 $done->recv; 398 $done->recv;
303 399
304=head2 CONDITION VARIABLES 400=head2 CONDITION VARIABLES
305 401
306If 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
307require you to run some blocking "loop", "run" or similar function that 403require you to run some blocking "loop", "run" or similar function that
313The instrument to do that is called a "condition variable", so called 409The instrument to do that is called a "condition variable", so called
314because they represent a condition that must become true. 410because they represent a condition that must become true.
315 411
316Condition variables can be created by calling the C<< AnyEvent->condvar 412Condition variables can be created by calling the C<< AnyEvent->condvar
317>> method, usually without arguments. The only argument pair allowed is 413>> method, usually without arguments. The only argument pair allowed is
414
318C<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
319becomes true. 416becomes true, with the condition variable as the first argument (but not
417the results).
320 418
321After creation, the condition variable is "false" until it becomes "true" 419After creation, the condition variable is "false" until it becomes "true"
322by calling the C<send> method (or calling the condition variable as if it 420by calling the C<send> method (or calling the condition variable as if it
323were a callback, read about the caveats in the description for the C<< 421were a callback, read about the caveats in the description for the C<<
324->send >> method). 422->send >> method).
380 478
381 my $done = AnyEvent->condvar; 479 my $done = AnyEvent->condvar;
382 my $delay = AnyEvent->timer (after => 5, cb => $done); 480 my $delay = AnyEvent->timer (after => 5, cb => $done);
383 $done->recv; 481 $done->recv;
384 482
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
385=head3 METHODS FOR PRODUCERS 500=head3 METHODS FOR PRODUCERS
386 501
387These 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
388code/module that eventually sends the signal. Note that it is also 503code/module that eventually sends the signal. Note that it is also
389the 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
522=item $bool = $cv->ready 637=item $bool = $cv->ready
523 638
524Returns 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
525C<croak> have been called. 640C<croak> have been called.
526 641
527=item $cb = $cv->cb ([new callback]) 642=item $cb = $cv->cb ($cb->($cv))
528 643
529This is a mutator function that returns the callback set and optionally 644This is a mutator function that returns the callback set and optionally
530replaces it before doing so. 645replaces it before doing so.
531 646
532The 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
533C<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
534or 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.
535 651
536=back 652=back
537 653
538=head1 GLOBAL VARIABLES AND FUNCTIONS 654=head1 GLOBAL VARIABLES AND FUNCTIONS
539 655
668=item L<AnyEvent::Util> 784=item L<AnyEvent::Util>
669 785
670Contains various utility functions that replace often-used but blocking 786Contains various utility functions that replace often-used but blocking
671functions such as C<inet_aton> by event-/callback-based versions. 787functions such as C<inet_aton> by event-/callback-based versions.
672 788
673=item L<AnyEvent::Handle>
674
675Provide read and write buffers and manages watchers for reads and writes.
676
677=item L<AnyEvent::Socket> 789=item L<AnyEvent::Socket>
678 790
679Provides various utility functions for (internet protocol) sockets, 791Provides various utility functions for (internet protocol) sockets,
680addresses and name resolution. Also functions to create non-blocking tcp 792addresses and name resolution. Also functions to create non-blocking tcp
681connections or tcp servers, with IPv6 and SRV record support and more. 793connections or tcp servers, with IPv6 and SRV record support and more.
682 794
795=item L<AnyEvent::Handle>
796
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
683=item L<AnyEvent::DNS> 801=item L<AnyEvent::DNS>
684 802
685Provides rich asynchronous DNS resolver capabilities. 803Provides rich asynchronous DNS resolver capabilities.
686 804
805=item L<AnyEvent::HTTP>
806
807A simple-to-use HTTP library that is capable of making a lot of concurrent
808HTTP requests.
809
687=item L<AnyEvent::HTTPD> 810=item L<AnyEvent::HTTPD>
688 811
689Provides a simple web application server framework. 812Provides a simple web application server framework.
690 813
691=item L<AnyEvent::FastPing> 814=item L<AnyEvent::FastPing>
692 815
693The fastest ping in the west. 816The fastest ping in the west.
694 817
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
695=item L<Net::IRC3> 842=item L<AnyEvent::IRC>
696 843
697AnyEvent based IRC client module family. 844AnyEvent based IRC client module family (replacing the older Net::IRC3).
698 845
699=item L<Net::XMPP2> 846=item L<Net::XMPP2>
700 847
701AnyEvent based XMPP (Jabber protocol) module family. 848AnyEvent based XMPP (Jabber protocol) module family.
702 849
711 858
712=item L<Coro> 859=item L<Coro>
713 860
714Has special support for AnyEvent via L<Coro::AnyEvent>. 861Has special support for AnyEvent via L<Coro::AnyEvent>.
715 862
716=item L<AnyEvent::AIO>, L<IO::AIO>
717
718Truly asynchronous I/O, should be in the toolbox of every event
719programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
720together.
721
722=item L<AnyEvent::BDB>, L<BDB>
723
724Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
725IO::AIO and AnyEvent together.
726
727=item L<IO::Lambda> 863=item L<IO::Lambda>
728 864
729The 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.
730 866
731=back 867=back
733=cut 869=cut
734 870
735package AnyEvent; 871package AnyEvent;
736 872
737no warnings; 873no warnings;
738use strict; 874use strict qw(vars subs);
739 875
740use Carp; 876use Carp;
741 877
742our $VERSION = '4.05'; 878our $VERSION = 4.35;
743our $MODEL; 879our $MODEL;
744 880
745our $AUTOLOAD; 881our $AUTOLOAD;
746our @ISA; 882our @ISA;
747 883
779 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 915 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
780 [Wx:: => AnyEvent::Impl::POE::], 916 [Wx:: => AnyEvent::Impl::POE::],
781 [Prima:: => AnyEvent::Impl::POE::], 917 [Prima:: => AnyEvent::Impl::POE::],
782); 918);
783 919
784our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 920our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
785 921
786our @post_detect; 922our @post_detect;
787 923
788sub post_detect(&) { 924sub post_detect(&) {
789 my ($cb) = @_; 925 my ($cb) = @_;
850 $MODEL 986 $MODEL
851 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 987 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
852 } 988 }
853 } 989 }
854 990
991 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
992
855 unshift @ISA, $MODEL; 993 unshift @ISA, $MODEL;
856 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 994
995 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
857 996
858 (shift @post_detect)->() while @post_detect; 997 (shift @post_detect)->() while @post_detect;
859 } 998 }
860 999
861 $MODEL 1000 $MODEL
871 1010
872 my $class = shift; 1011 my $class = shift;
873 $class->$func (@_); 1012 $class->$func (@_);
874} 1013}
875 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
876package AnyEvent::Base; 1034package AnyEvent::Base;
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 }
877 1049
878# default implementation for ->condvar 1050# default implementation for ->condvar
879 1051
880sub condvar { 1052sub condvar {
881 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1053 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
882} 1054}
883 1055
884# default implementation for ->signal 1056# default implementation for ->signal
885 1057
886our %SIG_CB; 1058our ($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}
887 1070
888sub signal { 1071sub signal {
889 my (undef, %arg) = @_; 1072 my (undef, %arg) = @_;
890 1073
1074 unless ($SIGPIPE_R) {
1075 if (AnyEvent::WIN32) {
1076 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1077 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1078 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1079 } else {
1080 pipe $SIGPIPE_R, $SIGPIPE_W;
1081 require Fcntl;
1082 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1083 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1084 }
1085
1086 $SIGPIPE_R
1087 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1088
1089 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1090 }
1091
891 my $signal = uc $arg{signal} 1092 my $signal = uc $arg{signal}
892 or Carp::croak "required option 'signal' is missing"; 1093 or Carp::croak "required option 'signal' is missing";
893 1094
894 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1095 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
895 $SIG{$signal} ||= sub { 1096 $SIG{$signal} ||= sub {
896 $_->() for values %{ $SIG_CB{$signal} || {} }; 1097 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1098 undef $SIG_EV{$signal};
897 }; 1099 };
898 1100
899 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1101 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
900} 1102}
901 1103
902sub AnyEvent::Base::Signal::DESTROY { 1104sub AnyEvent::Base::Signal::DESTROY {
903 my ($signal, $cb) = @{$_[0]}; 1105 my ($signal, $cb) = @{$_[0]};
904 1106
905 delete $SIG_CB{$signal}{$cb}; 1107 delete $SIG_CB{$signal}{$cb};
906 1108
907 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1109 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
908} 1110}
909 1111
910# default implementation for ->child 1112# default implementation for ->child
911 1113
912our %PID_CB; 1114our %PID_CB;
1020 1222
1021# undocumented/compatibility with pre-3.4 1223# undocumented/compatibility with pre-3.4
1022*broadcast = \&send; 1224*broadcast = \&send;
1023*wait = \&_wait; 1225*wait = \&_wait;
1024 1226
1227=head1 ERROR AND EXCEPTION HANDLING
1228
1229In general, AnyEvent does not do any error handling - it relies on the
1230caller to do that if required. The L<AnyEvent::Strict> module (see also
1231the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1232checking of all AnyEvent methods, however, which is highly useful during
1233development.
1234
1235As for exception handling (i.e. runtime errors and exceptions thrown while
1236executing a callback), this is not only highly event-loop specific, but
1237also not in any way wrapped by this module, as this is the job of the main
1238program.
1239
1240The pure perl event loop simply re-throws the exception (usually
1241within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1242$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1243so on.
1244
1245=head1 ENVIRONMENT VARIABLES
1246
1247The following environment variables are used by this module or its
1248submodules:
1249
1250=over 4
1251
1252=item C<PERL_ANYEVENT_VERBOSE>
1253
1254By default, AnyEvent will be completely silent except in fatal
1255conditions. You can set this environment variable to make AnyEvent more
1256talkative.
1257
1258When set to C<1> or higher, causes AnyEvent to warn about unexpected
1259conditions, such as not being able to load the event model specified by
1260C<PERL_ANYEVENT_MODEL>.
1261
1262When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1263model it chooses.
1264
1265=item C<PERL_ANYEVENT_STRICT>
1266
1267AnyEvent does not do much argument checking by default, as thorough
1268argument checking is very costly. Setting this variable to a true value
1269will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1270check the arguments passed to most method calls. If it finds any problems
1271it will croak.
1272
1273In other words, enables "strict" mode.
1274
1275Unlike C<use strict>, it is definitely recommended ot keep it off in
1276production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1277developing programs can be very useful, however.
1278
1279=item C<PERL_ANYEVENT_MODEL>
1280
1281This can be used to specify the event model to be used by AnyEvent, before
1282auto detection and -probing kicks in. It must be a string consisting
1283entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1284and the resulting module name is loaded and if the load was successful,
1285used as event model. If it fails to load AnyEvent will proceed with
1286auto detection and -probing.
1287
1288This functionality might change in future versions.
1289
1290For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1291could start your program like this:
1292
1293 PERL_ANYEVENT_MODEL=Perl perl ...
1294
1295=item C<PERL_ANYEVENT_PROTOCOLS>
1296
1297Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1298for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1299of auto probing).
1300
1301Must be set to a comma-separated list of protocols or address families,
1302current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1303used, and preference will be given to protocols mentioned earlier in the
1304list.
1305
1306This variable can effectively be used for denial-of-service attacks
1307against local programs (e.g. when setuid), although the impact is likely
1308small, as the program has to handle conenction and other failures anyways.
1309
1310Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1311but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1312- only support IPv4, never try to resolve or contact IPv6
1313addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1314IPv6, but prefer IPv6 over IPv4.
1315
1316=item C<PERL_ANYEVENT_EDNS0>
1317
1318Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1319for DNS. This extension is generally useful to reduce DNS traffic, but
1320some (broken) firewalls drop such DNS packets, which is why it is off by
1321default.
1322
1323Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1324EDNS0 in its DNS requests.
1325
1326=item C<PERL_ANYEVENT_MAX_FORKS>
1327
1328The maximum number of child processes that C<AnyEvent::Util::fork_call>
1329will create in parallel.
1330
1331=back
1332
1025=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1333=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1026 1334
1027This is an advanced topic that you do not normally need to use AnyEvent in 1335This is an advanced topic that you do not normally need to use AnyEvent in
1028a module. This section is only of use to event loop authors who want to 1336a module. This section is only of use to event loop authors who want to
1029provide AnyEvent compatibility. 1337provide AnyEvent compatibility.
1062 1370
1063I<rxvt-unicode> also cheats a bit by not providing blocking access to 1371I<rxvt-unicode> also cheats a bit by not providing blocking access to
1064condition variables: code blocking while waiting for a condition will 1372condition variables: code blocking while waiting for a condition will
1065C<die>. This still works with most modules/usages, and blocking calls must 1373C<die>. This still works with most modules/usages, and blocking calls must
1066not be done in an interactive application, so it makes sense. 1374not be done in an interactive application, so it makes sense.
1067
1068=head1 ENVIRONMENT VARIABLES
1069
1070The following environment variables are used by this module:
1071
1072=over 4
1073
1074=item C<PERL_ANYEVENT_VERBOSE>
1075
1076By default, AnyEvent will be completely silent except in fatal
1077conditions. You can set this environment variable to make AnyEvent more
1078talkative.
1079
1080When set to C<1> or higher, causes AnyEvent to warn about unexpected
1081conditions, such as not being able to load the event model specified by
1082C<PERL_ANYEVENT_MODEL>.
1083
1084When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1085model it chooses.
1086
1087=item C<PERL_ANYEVENT_MODEL>
1088
1089This can be used to specify the event model to be used by AnyEvent, before
1090auto detection and -probing kicks in. It must be a string consisting
1091entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1092and the resulting module name is loaded and if the load was successful,
1093used as event model. If it fails to load AnyEvent will proceed with
1094auto detection and -probing.
1095
1096This functionality might change in future versions.
1097
1098For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1099could start your program like this:
1100
1101 PERL_ANYEVENT_MODEL=Perl perl ...
1102
1103=item C<PERL_ANYEVENT_PROTOCOLS>
1104
1105Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1106for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1107of auto probing).
1108
1109Must be set to a comma-separated list of protocols or address families,
1110current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1111used, and preference will be given to protocols mentioned earlier in the
1112list.
1113
1114This variable can effectively be used for denial-of-service attacks
1115against local programs (e.g. when setuid), although the impact is likely
1116small, as the program has to handle connection errors already-
1117
1118Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1119but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1120- only support IPv4, never try to resolve or contact IPv6
1121addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1122IPv6, but prefer IPv6 over IPv4.
1123
1124=item C<PERL_ANYEVENT_EDNS0>
1125
1126Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1127for DNS. This extension is generally useful to reduce DNS traffic, but
1128some (broken) firewalls drop such DNS packets, which is why it is off by
1129default.
1130
1131Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1132EDNS0 in its DNS requests.
1133
1134=item C<PERL_ANYEVENT_MAX_FORKS>
1135
1136The maximum number of child processes that C<AnyEvent::Util::fork_call>
1137will create in parallel.
1138
1139=back
1140 1375
1141=head1 EXAMPLE PROGRAM 1376=head1 EXAMPLE PROGRAM
1142 1377
1143The following program uses an I/O watcher to read data from STDIN, a timer 1378The following program uses an I/O watcher to read data from STDIN, a timer
1144to display a message once per second, and a condition variable to quit the 1379to display a message once per second, and a condition variable to quit the
1338watcher. 1573watcher.
1339 1574
1340=head3 Results 1575=head3 Results
1341 1576
1342 name watchers bytes create invoke destroy comment 1577 name watchers bytes create invoke destroy comment
1343 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1578 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1344 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1579 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1345 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1580 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1346 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1581 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1347 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1582 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1348 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1583 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1349 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1584 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1350 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1585 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1351 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1586 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1352 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1587 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1353 1588
1354=head3 Discussion 1589=head3 Discussion
1355 1590
1356The benchmark does I<not> measure scalability of the event loop very 1591The benchmark does I<not> measure scalability of the event loop very
1357well. For example, a select-based event loop (such as the pure perl one) 1592well. For example, a select-based event loop (such as the pure perl one)
1559watchers, as the management overhead dominates. 1794watchers, as the management overhead dominates.
1560 1795
1561=back 1796=back
1562 1797
1563 1798
1799=head1 SIGNALS
1800
1801AnyEvent currently installs handlers for these signals:
1802
1803=over 4
1804
1805=item SIGCHLD
1806
1807A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1808emulation for event loops that do not support them natively. Also, some
1809event loops install a similar handler.
1810
1811=item SIGPIPE
1812
1813A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1814when AnyEvent gets loaded.
1815
1816The rationale for this is that AnyEvent users usually do not really depend
1817on SIGPIPE delivery (which is purely an optimisation for shell use, or
1818badly-written programs), but C<SIGPIPE> can cause spurious and rare
1819program exits as a lot of people do not expect C<SIGPIPE> when writing to
1820some random socket.
1821
1822The rationale for installing a no-op handler as opposed to ignoring it is
1823that this way, the handler will be restored to defaults on exec.
1824
1825Feel free to install your own handler, or reset it to defaults.
1826
1827=back
1828
1829=cut
1830
1831$SIG{PIPE} = sub { }
1832 unless defined $SIG{PIPE};
1833
1834
1564=head1 FORK 1835=head1 FORK
1565 1836
1566Most event libraries are not fork-safe. The ones who are usually are 1837Most event libraries are not fork-safe. The ones who are usually are
1567because they rely on inefficient but fork-safe C<select> or C<poll> 1838because they rely on inefficient but fork-safe C<select> or C<poll>
1568calls. Only L<EV> is fully fork-aware. 1839calls. Only L<EV> is fully fork-aware.
1581specified in the variable. 1852specified in the variable.
1582 1853
1583You can make AnyEvent completely ignore this variable by deleting it 1854You can make AnyEvent completely ignore this variable by deleting it
1584before the first watcher gets created, e.g. with a C<BEGIN> block: 1855before the first watcher gets created, e.g. with a C<BEGIN> block:
1585 1856
1586 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1857 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1587 1858
1588 use AnyEvent; 1859 use AnyEvent;
1589 1860
1590Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1861Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1591be used to probe what backend is used and gain other information (which is 1862be used to probe what backend is used and gain other information (which is
1592probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1863probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1864$ENV{PERL_ANYEGENT_STRICT}.
1865
1866
1867=head1 BUGS
1868
1869Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1870to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1871and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1872memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1873pronounced).
1593 1874
1594 1875
1595=head1 SEE ALSO 1876=head1 SEE ALSO
1596 1877
1597Utility functions: L<AnyEvent::Util>. 1878Utility functions: L<AnyEvent::Util>.
1614Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 1895Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1615 1896
1616 1897
1617=head1 AUTHOR 1898=head1 AUTHOR
1618 1899
1619 Marc Lehmann <schmorp@schmorp.de> 1900 Marc Lehmann <schmorp@schmorp.de>
1620 http://home.schmorp.de/ 1901 http://home.schmorp.de/
1621 1902
1622=cut 1903=cut
1623 1904
16241 19051
1625 1906

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