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1=> NAME 1NAME
2 AnyEvent - provide framework for multiple event loops 2 AnyEvent - provide framework for multiple event loops
3 3
4 EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event 4 EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event
5 loops 5 loops
6 6
7SYNOPSIS 7SYNOPSIS
8 use AnyEvent; 8 use AnyEvent;
9 9
10 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { 10 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
11 ...
12 });
13 11
14 my $w = AnyEvent->timer (after => $seconds, cb => sub { 12 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
13 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
14
15 print AnyEvent->now; # prints current event loop time
16 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
17
18 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
19
20 my $w = AnyEvent->child (pid => $pid, cb => sub {
21 my ($pid, $status) = @_;
15 ... 22 ...
16 }); 23 });
17 24
18 my $w = AnyEvent->condvar; # stores whether a condition was flagged 25 my $w = AnyEvent->condvar; # stores whether a condition was flagged
19 $w->send; # wake up current and all future recv's 26 $w->send; # wake up current and all future recv's
20 $w->recv; # enters "main loop" till $condvar gets ->send 27 $w->recv; # enters "main loop" till $condvar gets ->send
28 # use a condvar in callback mode:
29 $w->cb (sub { $_[0]->recv });
30
31INTRODUCTION/TUTORIAL
32 This manpage is mainly a reference manual. If you are interested in a
33 tutorial or some gentle introduction, have a look at the AnyEvent::Intro
34 manpage.
21 35
22WHY YOU SHOULD USE THIS MODULE (OR NOT) 36WHY YOU SHOULD USE THIS MODULE (OR NOT)
23 Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 37 Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
24 nowadays. So what is different about AnyEvent? 38 nowadays. So what is different about AnyEvent?
25 39
26 Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of 40 Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of
27 policy* and AnyEvent is *small and efficient*. 41 policy* and AnyEvent is *small and efficient*.
28 42
29 First and foremost, *AnyEvent is not an event model* itself, it only 43 First and foremost, *AnyEvent is not an event model* itself, it only
30 interfaces to whatever event model the main program happens to use in a 44 interfaces to whatever event model the main program happens to use, in a
31 pragmatic way. For event models and certain classes of immortals alike, 45 pragmatic way. For event models and certain classes of immortals alike,
32 the statement "there can only be one" is a bitter reality: In general, 46 the statement "there can only be one" is a bitter reality: In general,
33 only one event loop can be active at the same time in a process. 47 only one event loop can be active at the same time in a process.
34 AnyEvent helps hiding the differences between those event loops. 48 AnyEvent cannot change this, but it can hide the differences between
49 those event loops.
35 50
36 The goal of AnyEvent is to offer module authors the ability to do event 51 The goal of AnyEvent is to offer module authors the ability to do event
37 programming (waiting for I/O or timer events) without subscribing to a 52 programming (waiting for I/O or timer events) without subscribing to a
38 religion, a way of living, and most importantly: without forcing your 53 religion, a way of living, and most importantly: without forcing your
39 module users into the same thing by forcing them to use the same event 54 module users into the same thing by forcing them to use the same event
40 model you use. 55 model you use.
41 56
42 For modules like POE or IO::Async (which is a total misnomer as it is 57 For modules like POE or IO::Async (which is a total misnomer as it is
43 actually doing all I/O *synchronously*...), using them in your module is 58 actually doing all I/O *synchronously*...), using them in your module is
44 like joining a cult: After you joined, you are dependent on them and you 59 like joining a cult: After you joined, you are dependent on them and you
45 cannot use anything else, as it is simply incompatible to everything 60 cannot use anything else, as they are simply incompatible to everything
46 that isn't itself. What's worse, all the potential users of your module 61 that isn't them. What's worse, all the potential users of your module
47 are *also* forced to use the same event loop you use. 62 are *also* forced to use the same event loop you use.
48 63
49 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 64 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50 fine. AnyEvent + Tk works fine etc. etc. but none of these work together 65 fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51 with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your 66 with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your
52 module uses one of those, every user of your module has to use it, too. 67 module uses one of those, every user of your module has to use it, too.
53 But if your module uses AnyEvent, it works transparently with all event 68 But if your module uses AnyEvent, it works transparently with all event
54 models it supports (including stuff like POE and IO::Async, as long as 69 models it supports (including stuff like IO::Async, as long as those use
55 those use one of the supported event loops. It is trivial to add new 70 one of the supported event loops. It is trivial to add new event loops
56 event loops to AnyEvent, too, so it is future-proof). 71 to AnyEvent, too, so it is future-proof).
57 72
58 In addition to being free of having to use *the one and only true event 73 In addition to being free of having to use *the one and only true event
59 model*, AnyEvent also is free of bloat and policy: with POE or similar 74 model*, AnyEvent also is free of bloat and policy: with POE or similar
60 modules, you get an enormous amount of code and strict rules you have to 75 modules, you get an enormous amount of code and strict rules you have to
61 follow. AnyEvent, on the other hand, is lean and up to the point, by 76 follow. AnyEvent, on the other hand, is lean and up to the point, by
… …
128 Many watchers either are used with "recursion" (repeating timers for 143 Many watchers either are used with "recursion" (repeating timers for
129 example), or need to refer to their watcher object in other ways. 144 example), or need to refer to their watcher object in other ways.
130 145
131 An any way to achieve that is this pattern: 146 An any way to achieve that is this pattern:
132 147
133 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 148 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
134 # you can use $w here, for example to undef it 149 # you can use $w here, for example to undef it
135 undef $w; 150 undef $w;
136 }); 151 });
137 152
138 Note that "my $w; $w =" combination. This is necessary because in Perl, 153 Note that "my $w; $w =" combination. This is necessary because in Perl,
139 my variables are only visible after the statement in which they are 154 my variables are only visible after the statement in which they are
140 declared. 155 declared.
141 156
142 I/O WATCHERS 157 I/O WATCHERS
143 You can create an I/O watcher by calling the "AnyEvent->io" method with 158 You can create an I/O watcher by calling the "AnyEvent->io" method with
144 the following mandatory key-value pairs as arguments: 159 the following mandatory key-value pairs as arguments:
145 160
146 "fh" the Perl *file handle* (*not* file descriptor) to watch for events. 161 "fh" the Perl *file handle* (*not* file descriptor) to watch for events
162 (AnyEvent might or might not keep a reference to this file handle).
147 "poll" must be a string that is either "r" or "w", which creates a 163 "poll" must be a string that is either "r" or "w", which creates a
148 watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" 164 watcher waiting for "r"eadable or "w"ritable events, respectively. "cb"
149 is the callback to invoke each time the file handle becomes ready. 165 is the callback to invoke each time the file handle becomes ready.
150 166
151 Although the callback might get passed parameters, their value and 167 Although the callback might get passed parameters, their value and
… …
158 174
159 Some event loops issue spurious readyness notifications, so you should 175 Some event loops issue spurious readyness notifications, so you should
160 always use non-blocking calls when reading/writing from/to your file 176 always use non-blocking calls when reading/writing from/to your file
161 handles. 177 handles.
162 178
163 Example:
164
165 # wait for readability of STDIN, then read a line and disable the watcher 179 Example: wait for readability of STDIN, then read a line and disable the
180 watcher.
181
166 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 182 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167 chomp (my $input = <STDIN>); 183 chomp (my $input = <STDIN>);
168 warn "read: $input\n"; 184 warn "read: $input\n";
169 undef $w; 185 undef $w;
170 }); 186 });
… …
179 195
180 Although the callback might get passed parameters, their value and 196 Although the callback might get passed parameters, their value and
181 presence is undefined and you cannot rely on them. Portable AnyEvent 197 presence is undefined and you cannot rely on them. Portable AnyEvent
182 callbacks cannot use arguments passed to time watcher callbacks. 198 callbacks cannot use arguments passed to time watcher callbacks.
183 199
184 The timer callback will be invoked at most once: if you want a repeating 200 The callback will normally be invoked once only. If you specify another
185 timer you have to create a new watcher (this is a limitation by both Tk 201 parameter, "interval", as a strictly positive number (> 0), then the
186 and Glib). 202 callback will be invoked regularly at that interval (in fractional
203 seconds) after the first invocation. If "interval" is specified with a
204 false value, then it is treated as if it were missing.
187 205
188 Example: 206 The callback will be rescheduled before invoking the callback, but no
207 attempt is done to avoid timer drift in most backends, so the interval
208 is only approximate.
189 209
190 # fire an event after 7.7 seconds 210 Example: fire an event after 7.7 seconds.
211
191 my $w = AnyEvent->timer (after => 7.7, cb => sub { 212 my $w = AnyEvent->timer (after => 7.7, cb => sub {
192 warn "timeout\n"; 213 warn "timeout\n";
193 }); 214 });
194 215
195 # to cancel the timer: 216 # to cancel the timer:
196 undef $w; 217 undef $w;
197 218
198 Example 2:
199
200 # fire an event after 0.5 seconds, then roughly every second 219 Example 2: fire an event after 0.5 seconds, then roughly every second.
201 my $w;
202 220
203 my $cb = sub {
204 # cancel the old timer while creating a new one
205 $w = AnyEvent->timer (after => 1, cb => $cb); 221 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
222 warn "timeout\n";
206 }; 223 };
207
208 # start the "loop" by creating the first watcher
209 $w = AnyEvent->timer (after => 0.5, cb => $cb);
210 224
211 TIMING ISSUES 225 TIMING ISSUES
212 There are two ways to handle timers: based on real time (relative, "fire 226 There are two ways to handle timers: based on real time (relative, "fire
213 in 10 seconds") and based on wallclock time (absolute, "fire at 12 227 in 10 seconds") and based on wallclock time (absolute, "fire at 12
214 o'clock"). 228 o'clock").
… …
290 the difference between "AnyEvent->time" and "AnyEvent->now" into 304 the difference between "AnyEvent->time" and "AnyEvent->now" into
291 account. 305 account.
292 306
293 SIGNAL WATCHERS 307 SIGNAL WATCHERS
294 You can watch for signals using a signal watcher, "signal" is the signal 308 You can watch for signals using a signal watcher, "signal" is the signal
295 *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked 309 *name* in uppercase and without any "SIG" prefix, "cb" is the Perl
296 whenever a signal occurs. 310 callback to be invoked whenever a signal occurs.
297 311
298 Although the callback might get passed parameters, their value and 312 Although the callback might get passed parameters, their value and
299 presence is undefined and you cannot rely on them. Portable AnyEvent 313 presence is undefined and you cannot rely on them. Portable AnyEvent
300 callbacks cannot use arguments passed to signal watcher callbacks. 314 callbacks cannot use arguments passed to signal watcher callbacks.
301 315
… …
316 330
317 CHILD PROCESS WATCHERS 331 CHILD PROCESS WATCHERS
318 You can also watch on a child process exit and catch its exit status. 332 You can also watch on a child process exit and catch its exit status.
319 333
320 The child process is specified by the "pid" argument (if set to 0, it 334 The child process is specified by the "pid" argument (if set to 0, it
321 watches for any child process exit). The watcher will trigger as often 335 watches for any child process exit). The watcher will triggered only
322 as status change for the child are received. This works by installing a 336 when the child process has finished and an exit status is available, not
323 signal handler for "SIGCHLD". The callback will be called with the pid 337 on any trace events (stopped/continued).
324 and exit status (as returned by waitpid), so unlike other watcher types, 338
325 you *can* rely on child watcher callback arguments. 339 The callback will be called with the pid and exit status (as returned by
340 waitpid), so unlike other watcher types, you *can* rely on child watcher
341 callback arguments.
342
343 This watcher type works by installing a signal handler for "SIGCHLD",
344 and since it cannot be shared, nothing else should use SIGCHLD or reap
345 random child processes (waiting for specific child processes, e.g.
346 inside "system", is just fine).
326 347
327 There is a slight catch to child watchers, however: you usually start 348 There is a slight catch to child watchers, however: you usually start
328 them *after* the child process was created, and this means the process 349 them *after* the child process was created, and this means the process
329 could have exited already (and no SIGCHLD will be sent anymore). 350 could have exited already (and no SIGCHLD will be sent anymore).
330 351
… …
337 an AnyEvent program, you *have* to create at least one watcher before 358 an AnyEvent program, you *have* to create at least one watcher before
338 you "fork" the child (alternatively, you can call "AnyEvent::detect"). 359 you "fork" the child (alternatively, you can call "AnyEvent::detect").
339 360
340 Example: fork a process and wait for it 361 Example: fork a process and wait for it
341 362
342 my $done = AnyEvent->condvar; 363 my $done = AnyEvent->condvar;
343 364
344 my $pid = fork or exit 5; 365 my $pid = fork or exit 5;
345 366
346 my $w = AnyEvent->child ( 367 my $w = AnyEvent->child (
347 pid => $pid, 368 pid => $pid,
348 cb => sub { 369 cb => sub {
349 my ($pid, $status) = @_; 370 my ($pid, $status) = @_;
350 warn "pid $pid exited with status $status"; 371 warn "pid $pid exited with status $status";
351 $done->send; 372 $done->send;
352 }, 373 },
353 ); 374 );
354 375
355 # do something else, then wait for process exit 376 # do something else, then wait for process exit
356 $done->recv; 377 $done->recv;
357 378
358 CONDITION VARIABLES 379 CONDITION VARIABLES
359 If you are familiar with some event loops you will know that all of them 380 If you are familiar with some event loops you will know that all of them
360 require you to run some blocking "loop", "run" or similar function that 381 require you to run some blocking "loop", "run" or similar function that
361 will actively watch for new events and call your callbacks. 382 will actively watch for new events and call your callbacks.
… …
366 The instrument to do that is called a "condition variable", so called 387 The instrument to do that is called a "condition variable", so called
367 because they represent a condition that must become true. 388 because they represent a condition that must become true.
368 389
369 Condition variables can be created by calling the "AnyEvent->condvar" 390 Condition variables can be created by calling the "AnyEvent->condvar"
370 method, usually without arguments. The only argument pair allowed is 391 method, usually without arguments. The only argument pair allowed is
392
371 "cb", which specifies a callback to be called when the condition 393 "cb", which specifies a callback to be called when the condition
372 variable becomes true. 394 variable becomes true, with the condition variable as the first argument
395 (but not the results).
373 396
374 After creation, the condition variable is "false" until it becomes 397 After creation, the condition variable is "false" until it becomes
375 "true" by calling the "send" method (or calling the condition variable 398 "true" by calling the "send" method (or calling the condition variable
376 as if it were a callback, read about the caveats in the description for 399 as if it were a callback, read about the caveats in the description for
377 the "->send" method). 400 the "->send" method).
… …
433 456
434 my $done = AnyEvent->condvar; 457 my $done = AnyEvent->condvar;
435 my $delay = AnyEvent->timer (after => 5, cb => $done); 458 my $delay = AnyEvent->timer (after => 5, cb => $done);
436 $done->recv; 459 $done->recv;
437 460
461 Example: Imagine an API that returns a condvar and doesn't support
462 callbacks. This is how you make a synchronous call, for example from the
463 main program:
464
465 use AnyEvent::CouchDB;
466
467 ...
468
469 my @info = $couchdb->info->recv;
470
471 And this is how you would just ste a callback to be called whenever the
472 results are available:
473
474 $couchdb->info->cb (sub {
475 my @info = $_[0]->recv;
476 });
477
438 METHODS FOR PRODUCERS 478 METHODS FOR PRODUCERS
439 These methods should only be used by the producing side, i.e. the 479 These methods should only be used by the producing side, i.e. the
440 code/module that eventually sends the signal. Note that it is also the 480 code/module that eventually sends the signal. Note that it is also the
441 producer side which creates the condvar in most cases, but it isn't 481 producer side which creates the condvar in most cases, but it isn't
442 uncommon for the consumer to create it as well. 482 uncommon for the consumer to create it as well.
… …
562 602
563 $bool = $cv->ready 603 $bool = $cv->ready
564 Returns true when the condition is "true", i.e. whether "send" or 604 Returns true when the condition is "true", i.e. whether "send" or
565 "croak" have been called. 605 "croak" have been called.
566 606
567 $cb = $cv->cb ([new callback]) 607 $cb = $cv->cb ($cb->($cv))
568 This is a mutator function that returns the callback set and 608 This is a mutator function that returns the callback set and
569 optionally replaces it before doing so. 609 optionally replaces it before doing so.
570 610
571 The callback will be called when the condition becomes "true", i.e. 611 The callback will be called when the condition becomes "true", i.e.
572 when "send" or "croak" are called. Calling "recv" inside the 612 when "send" or "croak" are called, with the only argument being the
613 condition variable itself. Calling "recv" inside the callback or at
573 callback or at any later time is guaranteed not to block. 614 any later time is guaranteed not to block.
574 615
575GLOBAL VARIABLES AND FUNCTIONS 616GLOBAL VARIABLES AND FUNCTIONS
576 $AnyEvent::MODEL 617 $AnyEvent::MODEL
577 Contains "undef" until the first watcher is being created. Then it 618 Contains "undef" until the first watcher is being created. Then it
578 contains the event model that is being used, which is the name of 619 contains the event model that is being used, which is the name of
… …
692 AnyEvent::Util 733 AnyEvent::Util
693 Contains various utility functions that replace often-used but 734 Contains various utility functions that replace often-used but
694 blocking functions such as "inet_aton" by event-/callback-based 735 blocking functions such as "inet_aton" by event-/callback-based
695 versions. 736 versions.
696 737
697 AnyEvent::Handle
698 Provide read and write buffers and manages watchers for reads and
699 writes.
700
701 AnyEvent::Socket 738 AnyEvent::Socket
702 Provides various utility functions for (internet protocol) sockets, 739 Provides various utility functions for (internet protocol) sockets,
703 addresses and name resolution. Also functions to create non-blocking 740 addresses and name resolution. Also functions to create non-blocking
704 tcp connections or tcp servers, with IPv6 and SRV record support and 741 tcp connections or tcp servers, with IPv6 and SRV record support and
705 more. 742 more.
706 743
744 AnyEvent::Handle
745 Provide read and write buffers, manages watchers for reads and
746 writes, supports raw and formatted I/O, I/O queued and fully
747 transparent and non-blocking SSL/TLS.
748
707 AnyEvent::DNS 749 AnyEvent::DNS
708 Provides rich asynchronous DNS resolver capabilities. 750 Provides rich asynchronous DNS resolver capabilities.
709 751
752 AnyEvent::HTTP
753 A simple-to-use HTTP library that is capable of making a lot of
754 concurrent HTTP requests.
755
710 AnyEvent::HTTPD 756 AnyEvent::HTTPD
711 Provides a simple web application server framework. 757 Provides a simple web application server framework.
712 758
713 AnyEvent::FastPing 759 AnyEvent::FastPing
714 The fastest ping in the west. 760 The fastest ping in the west.
715 761
762 AnyEvent::DBI
763 Executes DBI requests asynchronously in a proxy process.
764
765 AnyEvent::AIO
766 Truly asynchronous I/O, should be in the toolbox of every event
767 programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
768 together.
769
770 AnyEvent::BDB
771 Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
772 fuses BDB and AnyEvent together.
773
774 AnyEvent::GPSD
775 A non-blocking interface to gpsd, a daemon delivering GPS
776 information.
777
778 AnyEvent::IGS
779 A non-blocking interface to the Internet Go Server protocol (used by
780 App::IGS).
781
782 AnyEvent::IRC
783 AnyEvent based IRC client module family (replacing the older
716 Net::IRC3 784 Net::IRC3).
717 AnyEvent based IRC client module family.
718 785
719 Net::XMPP2 786 Net::XMPP2
720 AnyEvent based XMPP (Jabber protocol) module family. 787 AnyEvent based XMPP (Jabber protocol) module family.
721 788
722 Net::FCP 789 Net::FCP
… …
727 High level API for event-based execution flow control. 794 High level API for event-based execution flow control.
728 795
729 Coro 796 Coro
730 Has special support for AnyEvent via Coro::AnyEvent. 797 Has special support for AnyEvent via Coro::AnyEvent.
731 798
732 AnyEvent::AIO, IO::AIO
733 Truly asynchronous I/O, should be in the toolbox of every event
734 programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
735 together.
736
737 AnyEvent::BDB, BDB
738 Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently
739 fuses IO::AIO and AnyEvent together.
740
741 IO::Lambda 799 IO::Lambda
742 The lambda approach to I/O - don't ask, look there. Can use 800 The lambda approach to I/O - don't ask, look there. Can use
743 AnyEvent. 801 AnyEvent.
744 802
745SUPPLYING YOUR OWN EVENT MODEL INTERFACE 803ERROR AND EXCEPTION HANDLING
746 This is an advanced topic that you do not normally need to use AnyEvent 804 In general, AnyEvent does not do any error handling - it relies on the
747 in a module. This section is only of use to event loop authors who want 805 caller to do that if required. The AnyEvent::Strict module (see also the
748 to provide AnyEvent compatibility. 806 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict
807 checking of all AnyEvent methods, however, which is highly useful during
808 development.
749 809
750 If you need to support another event library which isn't directly 810 As for exception handling (i.e. runtime errors and exceptions thrown
751 supported by AnyEvent, you can supply your own interface to it by 811 while executing a callback), this is not only highly event-loop
752 pushing, before the first watcher gets created, the package name of the 812 specific, but also not in any way wrapped by this module, as this is the
753 event module and the package name of the interface to use onto 813 job of the main program.
754 @AnyEvent::REGISTRY. You can do that before and even without loading
755 AnyEvent, so it is reasonably cheap.
756 814
757 Example: 815 The pure perl event loop simply re-throws the exception (usually within
758 816 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
759 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 817 Glib uses "install_exception_handler" and so on.
760
761 This tells AnyEvent to (literally) use the "urxvt::anyevent::"
762 package/class when it finds the "urxvt" package/module is already
763 loaded.
764
765 When AnyEvent is loaded and asked to find a suitable event model, it
766 will first check for the presence of urxvt by trying to "use" the
767 "urxvt::anyevent" module.
768
769 The class should provide implementations for all watcher types. See
770 AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
771 so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
772 the sources.
773
774 If you don't provide "signal" and "child" watchers than AnyEvent will
775 provide suitable (hopefully) replacements.
776
777 The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt)
778 terminal emulator uses the above line as-is. An interface isn't included
779 in AnyEvent because it doesn't make sense outside the embedded
780 interpreter inside *rxvt-unicode*, and it is updated and maintained as
781 part of the *rxvt-unicode* distribution.
782
783 *rxvt-unicode* also cheats a bit by not providing blocking access to
784 condition variables: code blocking while waiting for a condition will
785 "die". This still works with most modules/usages, and blocking calls
786 must not be done in an interactive application, so it makes sense.
787 818
788ENVIRONMENT VARIABLES 819ENVIRONMENT VARIABLES
789 The following environment variables are used by this module: 820 The following environment variables are used by this module or its
821 submodules:
790 822
791 "PERL_ANYEVENT_VERBOSE" 823 "PERL_ANYEVENT_VERBOSE"
792 By default, AnyEvent will be completely silent except in fatal 824 By default, AnyEvent will be completely silent except in fatal
793 conditions. You can set this environment variable to make AnyEvent 825 conditions. You can set this environment variable to make AnyEvent
794 more talkative. 826 more talkative.
… …
797 conditions, such as not being able to load the event model specified 829 conditions, such as not being able to load the event model specified
798 by "PERL_ANYEVENT_MODEL". 830 by "PERL_ANYEVENT_MODEL".
799 831
800 When set to 2 or higher, cause AnyEvent to report to STDERR which 832 When set to 2 or higher, cause AnyEvent to report to STDERR which
801 event model it chooses. 833 event model it chooses.
834
835 "PERL_ANYEVENT_STRICT"
836 AnyEvent does not do much argument checking by default, as thorough
837 argument checking is very costly. Setting this variable to a true
838 value will cause AnyEvent to load "AnyEvent::Strict" and then to
839 thoroughly check the arguments passed to most method calls. If it
840 finds any problems it will croak.
841
842 In other words, enables "strict" mode.
843
844 Unlike "use strict", it is definitely recommended ot keep it off in
845 production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment
846 while developing programs can be very useful, however.
802 847
803 "PERL_ANYEVENT_MODEL" 848 "PERL_ANYEVENT_MODEL"
804 This can be used to specify the event model to be used by AnyEvent, 849 This can be used to specify the event model to be used by AnyEvent,
805 before auto detection and -probing kicks in. It must be a string 850 before auto detection and -probing kicks in. It must be a string
806 consisting entirely of ASCII letters. The string "AnyEvent::Impl::" 851 consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
… …
811 This functionality might change in future versions. 856 This functionality might change in future versions.
812 857
813 For example, to force the pure perl model (AnyEvent::Impl::Perl) you 858 For example, to force the pure perl model (AnyEvent::Impl::Perl) you
814 could start your program like this: 859 could start your program like this:
815 860
816 PERL_ANYEVENT_MODEL=Perl perl ... 861 PERL_ANYEVENT_MODEL=Perl perl ...
817 862
818 "PERL_ANYEVENT_PROTOCOLS" 863 "PERL_ANYEVENT_PROTOCOLS"
819 Used by both AnyEvent::DNS and AnyEvent::Socket to determine 864 Used by both AnyEvent::DNS and AnyEvent::Socket to determine
820 preferences for IPv4 or IPv6. The default is unspecified (and might 865 preferences for IPv4 or IPv6. The default is unspecified (and might
821 change, or be the result of auto probing). 866 change, or be the result of auto probing).
… …
847 EDNS0 in its DNS requests. 892 EDNS0 in its DNS requests.
848 893
849 "PERL_ANYEVENT_MAX_FORKS" 894 "PERL_ANYEVENT_MAX_FORKS"
850 The maximum number of child processes that 895 The maximum number of child processes that
851 "AnyEvent::Util::fork_call" will create in parallel. 896 "AnyEvent::Util::fork_call" will create in parallel.
897
898SUPPLYING YOUR OWN EVENT MODEL INTERFACE
899 This is an advanced topic that you do not normally need to use AnyEvent
900 in a module. This section is only of use to event loop authors who want
901 to provide AnyEvent compatibility.
902
903 If you need to support another event library which isn't directly
904 supported by AnyEvent, you can supply your own interface to it by
905 pushing, before the first watcher gets created, the package name of the
906 event module and the package name of the interface to use onto
907 @AnyEvent::REGISTRY. You can do that before and even without loading
908 AnyEvent, so it is reasonably cheap.
909
910 Example:
911
912 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
913
914 This tells AnyEvent to (literally) use the "urxvt::anyevent::"
915 package/class when it finds the "urxvt" package/module is already
916 loaded.
917
918 When AnyEvent is loaded and asked to find a suitable event model, it
919 will first check for the presence of urxvt by trying to "use" the
920 "urxvt::anyevent" module.
921
922 The class should provide implementations for all watcher types. See
923 AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
924 so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
925 the sources.
926
927 If you don't provide "signal" and "child" watchers than AnyEvent will
928 provide suitable (hopefully) replacements.
929
930 The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt)
931 terminal emulator uses the above line as-is. An interface isn't included
932 in AnyEvent because it doesn't make sense outside the embedded
933 interpreter inside *rxvt-unicode*, and it is updated and maintained as
934 part of the *rxvt-unicode* distribution.
935
936 *rxvt-unicode* also cheats a bit by not providing blocking access to
937 condition variables: code blocking while waiting for a condition will
938 "die". This still works with most modules/usages, and blocking calls
939 must not be done in an interactive application, so it makes sense.
852 940
853EXAMPLE PROGRAM 941EXAMPLE PROGRAM
854 The following program uses an I/O watcher to read data from STDIN, a 942 The following program uses an I/O watcher to read data from STDIN, a
855 timer to display a message once per second, and a condition variable to 943 timer to display a message once per second, and a condition variable to
856 quit the program when the user enters quit: 944 quit the program when the user enters quit:
… …
1043 *destroy* is the time, in microseconds, that it takes to destroy a 1131 *destroy* is the time, in microseconds, that it takes to destroy a
1044 single watcher. 1132 single watcher.
1045 1133
1046 Results 1134 Results
1047 name watchers bytes create invoke destroy comment 1135 name watchers bytes create invoke destroy comment
1048 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1136 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1049 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1137 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1050 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1138 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1051 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1139 Perl/Any 100000 452 4.14 0.75 0.99 pure perl implementation
1052 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1140 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1053 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1141 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1054 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1142 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1055 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1143 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1056 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1144 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1057 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1145 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1058 1146
1059 Discussion 1147 Discussion
1060 The benchmark does *not* measure scalability of the event loop very 1148 The benchmark does *not* measure scalability of the event loop very
1061 well. For example, a select-based event loop (such as the pure perl one) 1149 well. For example, a select-based event loop (such as the pure perl one)
1062 can never compete with an event loop that uses epoll when the number of 1150 can never compete with an event loop that uses epoll when the number of
… …
1243 1331
1244 Summary 1332 Summary
1245 * C-based event loops perform very well with small number of watchers, 1333 * C-based event loops perform very well with small number of watchers,
1246 as the management overhead dominates. 1334 as the management overhead dominates.
1247 1335
1336SIGNALS
1337 AnyEvent currently installs handlers for these signals:
1338
1339 SIGCHLD
1340 A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1341 emulation for event loops that do not support them natively. Also,
1342 some event loops install a similar handler.
1343
1344 SIGPIPE
1345 A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1346 "undef" when AnyEvent gets loaded.
1347
1348 The rationale for this is that AnyEvent users usually do not really
1349 depend on SIGPIPE delivery (which is purely an optimisation for
1350 shell use, or badly-written programs), but "SIGPIPE" can cause
1351 spurious and rare program exits as a lot of people do not expect
1352 "SIGPIPE" when writing to some random socket.
1353
1354 The rationale for installing a no-op handler as opposed to ignoring
1355 it is that this way, the handler will be restored to defaults on
1356 exec.
1357
1358 Feel free to install your own handler, or reset it to defaults.
1359
1248FORK 1360FORK
1249 Most event libraries are not fork-safe. The ones who are usually are 1361 Most event libraries are not fork-safe. The ones who are usually are
1250 because they rely on inefficient but fork-safe "select" or "poll" calls. 1362 because they rely on inefficient but fork-safe "select" or "poll" calls.
1251 Only EV is fully fork-aware. 1363 Only EV is fully fork-aware.
1252 1364
… …
1262 model than specified in the variable. 1374 model than specified in the variable.
1263 1375
1264 You can make AnyEvent completely ignore this variable by deleting it 1376 You can make AnyEvent completely ignore this variable by deleting it
1265 before the first watcher gets created, e.g. with a "BEGIN" block: 1377 before the first watcher gets created, e.g. with a "BEGIN" block:
1266 1378
1267 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1379 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1268 1380
1269 use AnyEvent; 1381 use AnyEvent;
1270 1382
1271 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1383 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1272 be used to probe what backend is used and gain other information (which 1384 be used to probe what backend is used and gain other information (which
1273 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1385 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1386 and $ENV{PERL_ANYEGENT_STRICT}.
1387
1388BUGS
1389 Perl 5.8 has numerous memleaks that sometimes hit this module and are
1390 hard to work around. If you suffer from memleaks, first upgrade to Perl
1391 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1392 annoying mamleaks, such as leaking on "map" and "grep" but it is usually
1393 not as pronounced).
1274 1394
1275SEE ALSO 1395SEE ALSO
1276 Utility functions: AnyEvent::Util. 1396 Utility functions: AnyEvent::Util.
1277 1397
1278 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, 1398 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
… …
1290 Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, 1410 Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1291 1411
1292 Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. 1412 Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.
1293 1413
1294AUTHOR 1414AUTHOR
1295 Marc Lehmann <schmorp@schmorp.de> 1415 Marc Lehmann <schmorp@schmorp.de>
1296 http://home.schmorp.de/ 1416 http://home.schmorp.de/
1297 1417

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