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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 });
21 30
22INTRODUCTION/TUTORIAL 31INTRODUCTION/TUTORIAL
23 This manpage is mainly a reference manual. If you are interested in a 32 This manpage is mainly a reference manual. If you are interested in a
24 tutorial or some gentle introduction, have a look at the AnyEvent::Intro 33 tutorial or some gentle introduction, have a look at the AnyEvent::Intro
25 manpage. 34 manpage.
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30 39
31 Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of 40 Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of
32 policy* and AnyEvent is *small and efficient*. 41 policy* and AnyEvent is *small and efficient*.
33 42
34 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
35 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
36 pragmatic way. For event models and certain classes of immortals alike, 45 pragmatic way. For event models and certain classes of immortals alike,
37 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,
38 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.
39 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.
40 50
41 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
42 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
43 religion, a way of living, and most importantly: without forcing your 53 religion, a way of living, and most importantly: without forcing your
44 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
45 model you use. 55 model you use.
46 56
47 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
48 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
49 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
50 cannot use anything else, as it is simply incompatible to everything 60 cannot use anything else, as they are simply incompatible to everything
51 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
52 are *also* forced to use the same event loop you use. 62 are *also* forced to use the same event loop you use.
53 63
54 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 64 AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
55 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
56 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
57 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.
58 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
59 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
60 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
61 event loops to AnyEvent, too, so it is future-proof). 71 to AnyEvent, too, so it is future-proof).
62 72
63 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
64 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
65 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
66 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
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122 These watchers are normal Perl objects with normal Perl lifetime. After 132 These watchers are normal Perl objects with normal Perl lifetime. After
123 creating a watcher it will immediately "watch" for events and invoke the 133 creating a watcher it will immediately "watch" for events and invoke the
124 callback when the event occurs (of course, only when the event model is 134 callback when the event occurs (of course, only when the event model is
125 in control). 135 in control).
126 136
137 Note that callbacks must not permanently change global variables
138 potentially in use by the event loop (such as $_ or $[) and that
139 callbacks must not "die". The former is good programming practise in
140 Perl and the latter stems from the fact that exception handling differs
141 widely between event loops.
142
127 To disable the watcher you have to destroy it (e.g. by setting the 143 To disable the watcher you have to destroy it (e.g. by setting the
128 variable you store it in to "undef" or otherwise deleting all references 144 variable you store it in to "undef" or otherwise deleting all references
129 to it). 145 to it).
130 146
131 All watchers are created by calling a method on the "AnyEvent" class. 147 All watchers are created by calling a method on the "AnyEvent" class.
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146 162
147 I/O WATCHERS 163 I/O WATCHERS
148 You can create an I/O watcher by calling the "AnyEvent->io" method with 164 You can create an I/O watcher by calling the "AnyEvent->io" method with
149 the following mandatory key-value pairs as arguments: 165 the following mandatory key-value pairs as arguments:
150 166
151 "fh" the Perl *file handle* (*not* file descriptor) to watch for events. 167 "fh" is the Perl *file handle* (*not* file descriptor) to watch for
168 events (AnyEvent might or might not keep a reference to this file
169 handle). Note that only file handles pointing to things for which
170 non-blocking operation makes sense are allowed. This includes sockets,
171 most character devices, pipes, fifos and so on, but not for example
172 files or block devices.
173
152 "poll" must be a string that is either "r" or "w", which creates a 174 "poll" must be a string that is either "r" or "w", which creates a
153 watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" 175 watcher waiting for "r"eadable or "w"ritable events, respectively.
176
154 is the callback to invoke each time the file handle becomes ready. 177 "cb" is the callback to invoke each time the file handle becomes ready.
155 178
156 Although the callback might get passed parameters, their value and 179 Although the callback might get passed parameters, their value and
157 presence is undefined and you cannot rely on them. Portable AnyEvent 180 presence is undefined and you cannot rely on them. Portable AnyEvent
158 callbacks cannot use arguments passed to I/O watcher callbacks. 181 callbacks cannot use arguments passed to I/O watcher callbacks.
159 182
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163 186
164 Some event loops issue spurious readyness notifications, so you should 187 Some event loops issue spurious readyness notifications, so you should
165 always use non-blocking calls when reading/writing from/to your file 188 always use non-blocking calls when reading/writing from/to your file
166 handles. 189 handles.
167 190
168 Example:
169
170 # wait for readability of STDIN, then read a line and disable the watcher 191 Example: wait for readability of STDIN, then read a line and disable the
192 watcher.
193
171 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 194 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
172 chomp (my $input = <STDIN>); 195 chomp (my $input = <STDIN>);
173 warn "read: $input\n"; 196 warn "read: $input\n";
174 undef $w; 197 undef $w;
175 }); 198 });
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184 207
185 Although the callback might get passed parameters, their value and 208 Although the callback might get passed parameters, their value and
186 presence is undefined and you cannot rely on them. Portable AnyEvent 209 presence is undefined and you cannot rely on them. Portable AnyEvent
187 callbacks cannot use arguments passed to time watcher callbacks. 210 callbacks cannot use arguments passed to time watcher callbacks.
188 211
189 The timer callback will be invoked at most once: if you want a repeating 212 The callback will normally be invoked once only. If you specify another
190 timer you have to create a new watcher (this is a limitation by both Tk 213 parameter, "interval", as a strictly positive number (> 0), then the
191 and Glib). 214 callback will be invoked regularly at that interval (in fractional
215 seconds) after the first invocation. If "interval" is specified with a
216 false value, then it is treated as if it were missing.
192 217
193 Example: 218 The callback will be rescheduled before invoking the callback, but no
219 attempt is done to avoid timer drift in most backends, so the interval
220 is only approximate.
194 221
195 # fire an event after 7.7 seconds 222 Example: fire an event after 7.7 seconds.
223
196 my $w = AnyEvent->timer (after => 7.7, cb => sub { 224 my $w = AnyEvent->timer (after => 7.7, cb => sub {
197 warn "timeout\n"; 225 warn "timeout\n";
198 }); 226 });
199 227
200 # to cancel the timer: 228 # to cancel the timer:
201 undef $w; 229 undef $w;
202 230
203 Example 2:
204
205 # fire an event after 0.5 seconds, then roughly every second 231 Example 2: fire an event after 0.5 seconds, then roughly every second.
206 my $w;
207 232
208 my $cb = sub {
209 # cancel the old timer while creating a new one
210 $w = AnyEvent->timer (after => 1, cb => $cb); 233 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
234 warn "timeout\n";
211 }; 235 };
212
213 # start the "loop" by creating the first watcher
214 $w = AnyEvent->timer (after => 0.5, cb => $cb);
215 236
216 TIMING ISSUES 237 TIMING ISSUES
217 There are two ways to handle timers: based on real time (relative, "fire 238 There are two ways to handle timers: based on real time (relative, "fire
218 in 10 seconds") and based on wallclock time (absolute, "fire at 12 239 in 10 seconds") and based on wallclock time (absolute, "fire at 12
219 o'clock"). 240 o'clock").
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293 In either case, if you care (and in most cases, you don't), then you 314 In either case, if you care (and in most cases, you don't), then you
294 can get whatever behaviour you want with any event loop, by taking 315 can get whatever behaviour you want with any event loop, by taking
295 the difference between "AnyEvent->time" and "AnyEvent->now" into 316 the difference between "AnyEvent->time" and "AnyEvent->now" into
296 account. 317 account.
297 318
319 AnyEvent->now_update
320 Some event loops (such as EV or AnyEvent::Impl::Perl) cache the
321 current time for each loop iteration (see the discussion of
322 AnyEvent->now, above).
323
324 When a callback runs for a long time (or when the process sleeps),
325 then this "current" time will differ substantially from the real
326 time, which might affect timers and time-outs.
327
328 When this is the case, you can call this method, which will update
329 the event loop's idea of "current time".
330
331 Note that updating the time *might* cause some events to be handled.
332
298 SIGNAL WATCHERS 333 SIGNAL WATCHERS
299 You can watch for signals using a signal watcher, "signal" is the signal 334 You can watch for signals using a signal watcher, "signal" is the signal
300 *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked 335 *name* in uppercase and without any "SIG" prefix, "cb" is the Perl
301 whenever a signal occurs. 336 callback to be invoked whenever a signal occurs.
302 337
303 Although the callback might get passed parameters, their value and 338 Although the callback might get passed parameters, their value and
304 presence is undefined and you cannot rely on them. Portable AnyEvent 339 presence is undefined and you cannot rely on them. Portable AnyEvent
305 callbacks cannot use arguments passed to signal watcher callbacks. 340 callbacks cannot use arguments passed to signal watcher callbacks.
306 341
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321 356
322 CHILD PROCESS WATCHERS 357 CHILD PROCESS WATCHERS
323 You can also watch on a child process exit and catch its exit status. 358 You can also watch on a child process exit and catch its exit status.
324 359
325 The child process is specified by the "pid" argument (if set to 0, it 360 The child process is specified by the "pid" argument (if set to 0, it
326 watches for any child process exit). The watcher will trigger as often 361 watches for any child process exit). The watcher will triggered only
327 as status change for the child are received. This works by installing a 362 when the child process has finished and an exit status is available, not
328 signal handler for "SIGCHLD". The callback will be called with the pid 363 on any trace events (stopped/continued).
329 and exit status (as returned by waitpid), so unlike other watcher types, 364
330 you *can* rely on child watcher callback arguments. 365 The callback will be called with the pid and exit status (as returned by
366 waitpid), so unlike other watcher types, you *can* rely on child watcher
367 callback arguments.
368
369 This watcher type works by installing a signal handler for "SIGCHLD",
370 and since it cannot be shared, nothing else should use SIGCHLD or reap
371 random child processes (waiting for specific child processes, e.g.
372 inside "system", is just fine).
331 373
332 There is a slight catch to child watchers, however: you usually start 374 There is a slight catch to child watchers, however: you usually start
333 them *after* the child process was created, and this means the process 375 them *after* the child process was created, and this means the process
334 could have exited already (and no SIGCHLD will be sent anymore). 376 could have exited already (and no SIGCHLD will be sent anymore).
335 377
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371 The instrument to do that is called a "condition variable", so called 413 The instrument to do that is called a "condition variable", so called
372 because they represent a condition that must become true. 414 because they represent a condition that must become true.
373 415
374 Condition variables can be created by calling the "AnyEvent->condvar" 416 Condition variables can be created by calling the "AnyEvent->condvar"
375 method, usually without arguments. The only argument pair allowed is 417 method, usually without arguments. The only argument pair allowed is
418
376 "cb", which specifies a callback to be called when the condition 419 "cb", which specifies a callback to be called when the condition
377 variable becomes true. 420 variable becomes true, with the condition variable as the first argument
421 (but not the results).
378 422
379 After creation, the condition variable is "false" until it becomes 423 After creation, the condition variable is "false" until it becomes
380 "true" by calling the "send" method (or calling the condition variable 424 "true" by calling the "send" method (or calling the condition variable
381 as if it were a callback, read about the caveats in the description for 425 as if it were a callback, read about the caveats in the description for
382 the "->send" method). 426 the "->send" method).
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438 482
439 my $done = AnyEvent->condvar; 483 my $done = AnyEvent->condvar;
440 my $delay = AnyEvent->timer (after => 5, cb => $done); 484 my $delay = AnyEvent->timer (after => 5, cb => $done);
441 $done->recv; 485 $done->recv;
442 486
487 Example: Imagine an API that returns a condvar and doesn't support
488 callbacks. This is how you make a synchronous call, for example from the
489 main program:
490
491 use AnyEvent::CouchDB;
492
493 ...
494
495 my @info = $couchdb->info->recv;
496
497 And this is how you would just ste a callback to be called whenever the
498 results are available:
499
500 $couchdb->info->cb (sub {
501 my @info = $_[0]->recv;
502 });
503
443 METHODS FOR PRODUCERS 504 METHODS FOR PRODUCERS
444 These methods should only be used by the producing side, i.e. the 505 These methods should only be used by the producing side, i.e. the
445 code/module that eventually sends the signal. Note that it is also the 506 code/module that eventually sends the signal. Note that it is also the
446 producer side which creates the condvar in most cases, but it isn't 507 producer side which creates the condvar in most cases, but it isn't
447 uncommon for the consumer to create it as well. 508 uncommon for the consumer to create it as well.
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567 628
568 $bool = $cv->ready 629 $bool = $cv->ready
569 Returns true when the condition is "true", i.e. whether "send" or 630 Returns true when the condition is "true", i.e. whether "send" or
570 "croak" have been called. 631 "croak" have been called.
571 632
572 $cb = $cv->cb ([new callback]) 633 $cb = $cv->cb ($cb->($cv))
573 This is a mutator function that returns the callback set and 634 This is a mutator function that returns the callback set and
574 optionally replaces it before doing so. 635 optionally replaces it before doing so.
575 636
576 The callback will be called when the condition becomes "true", i.e. 637 The callback will be called when the condition becomes "true", i.e.
577 when "send" or "croak" are called, with the only argument being the 638 when "send" or "croak" are called, with the only argument being the
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698 AnyEvent::Util 759 AnyEvent::Util
699 Contains various utility functions that replace often-used but 760 Contains various utility functions that replace often-used but
700 blocking functions such as "inet_aton" by event-/callback-based 761 blocking functions such as "inet_aton" by event-/callback-based
701 versions. 762 versions.
702 763
703 AnyEvent::Handle
704 Provide read and write buffers and manages watchers for reads and
705 writes.
706
707 AnyEvent::Socket 764 AnyEvent::Socket
708 Provides various utility functions for (internet protocol) sockets, 765 Provides various utility functions for (internet protocol) sockets,
709 addresses and name resolution. Also functions to create non-blocking 766 addresses and name resolution. Also functions to create non-blocking
710 tcp connections or tcp servers, with IPv6 and SRV record support and 767 tcp connections or tcp servers, with IPv6 and SRV record support and
711 more. 768 more.
712 769
770 AnyEvent::Handle
771 Provide read and write buffers, manages watchers for reads and
772 writes, supports raw and formatted I/O, I/O queued and fully
773 transparent and non-blocking SSL/TLS.
774
713 AnyEvent::DNS 775 AnyEvent::DNS
714 Provides rich asynchronous DNS resolver capabilities. 776 Provides rich asynchronous DNS resolver capabilities.
715 777
716 AnyEvent::HTTP 778 AnyEvent::HTTP
717 A simple-to-use HTTP library that is capable of making a lot of 779 A simple-to-use HTTP library that is capable of making a lot of
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724 The fastest ping in the west. 786 The fastest ping in the west.
725 787
726 AnyEvent::DBI 788 AnyEvent::DBI
727 Executes DBI requests asynchronously in a proxy process. 789 Executes DBI requests asynchronously in a proxy process.
728 790
791 AnyEvent::AIO
792 Truly asynchronous I/O, should be in the toolbox of every event
793 programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
794 together.
795
796 AnyEvent::BDB
797 Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
798 fuses BDB and AnyEvent together.
799
800 AnyEvent::GPSD
801 A non-blocking interface to gpsd, a daemon delivering GPS
802 information.
803
804 AnyEvent::IGS
805 A non-blocking interface to the Internet Go Server protocol (used by
806 App::IGS).
807
808 AnyEvent::IRC
809 AnyEvent based IRC client module family (replacing the older
729 Net::IRC3 810 Net::IRC3).
730 AnyEvent based IRC client module family.
731 811
732 Net::XMPP2 812 Net::XMPP2
733 AnyEvent based XMPP (Jabber protocol) module family. 813 AnyEvent based XMPP (Jabber protocol) module family.
734 814
735 Net::FCP 815 Net::FCP
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740 High level API for event-based execution flow control. 820 High level API for event-based execution flow control.
741 821
742 Coro 822 Coro
743 Has special support for AnyEvent via Coro::AnyEvent. 823 Has special support for AnyEvent via Coro::AnyEvent.
744 824
745 AnyEvent::AIO, IO::AIO
746 Truly asynchronous I/O, should be in the toolbox of every event
747 programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
748 together.
749
750 AnyEvent::BDB, BDB
751 Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently
752 fuses IO::AIO and AnyEvent together.
753
754 IO::Lambda 825 IO::Lambda
755 The lambda approach to I/O - don't ask, look there. Can use 826 The lambda approach to I/O - don't ask, look there. Can use
756 AnyEvent. 827 AnyEvent.
757 828
758SUPPLYING YOUR OWN EVENT MODEL INTERFACE 829ERROR AND EXCEPTION HANDLING
759 This is an advanced topic that you do not normally need to use AnyEvent 830 In general, AnyEvent does not do any error handling - it relies on the
760 in a module. This section is only of use to event loop authors who want 831 caller to do that if required. The AnyEvent::Strict module (see also the
761 to provide AnyEvent compatibility. 832 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict
833 checking of all AnyEvent methods, however, which is highly useful during
834 development.
762 835
763 If you need to support another event library which isn't directly 836 As for exception handling (i.e. runtime errors and exceptions thrown
764 supported by AnyEvent, you can supply your own interface to it by 837 while executing a callback), this is not only highly event-loop
765 pushing, before the first watcher gets created, the package name of the 838 specific, but also not in any way wrapped by this module, as this is the
766 event module and the package name of the interface to use onto 839 job of the main program.
767 @AnyEvent::REGISTRY. You can do that before and even without loading
768 AnyEvent, so it is reasonably cheap.
769 840
770 Example: 841 The pure perl event loop simply re-throws the exception (usually within
771 842 "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
772 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 843 Glib uses "install_exception_handler" and so on.
773
774 This tells AnyEvent to (literally) use the "urxvt::anyevent::"
775 package/class when it finds the "urxvt" package/module is already
776 loaded.
777
778 When AnyEvent is loaded and asked to find a suitable event model, it
779 will first check for the presence of urxvt by trying to "use" the
780 "urxvt::anyevent" module.
781
782 The class should provide implementations for all watcher types. See
783 AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
784 so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
785 the sources.
786
787 If you don't provide "signal" and "child" watchers than AnyEvent will
788 provide suitable (hopefully) replacements.
789
790 The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt)
791 terminal emulator uses the above line as-is. An interface isn't included
792 in AnyEvent because it doesn't make sense outside the embedded
793 interpreter inside *rxvt-unicode*, and it is updated and maintained as
794 part of the *rxvt-unicode* distribution.
795
796 *rxvt-unicode* also cheats a bit by not providing blocking access to
797 condition variables: code blocking while waiting for a condition will
798 "die". This still works with most modules/usages, and blocking calls
799 must not be done in an interactive application, so it makes sense.
800 844
801ENVIRONMENT VARIABLES 845ENVIRONMENT VARIABLES
802 The following environment variables are used by this module: 846 The following environment variables are used by this module or its
847 submodules:
803 848
804 "PERL_ANYEVENT_VERBOSE" 849 "PERL_ANYEVENT_VERBOSE"
805 By default, AnyEvent will be completely silent except in fatal 850 By default, AnyEvent will be completely silent except in fatal
806 conditions. You can set this environment variable to make AnyEvent 851 conditions. You can set this environment variable to make AnyEvent
807 more talkative. 852 more talkative.
… …
810 conditions, such as not being able to load the event model specified 855 conditions, such as not being able to load the event model specified
811 by "PERL_ANYEVENT_MODEL". 856 by "PERL_ANYEVENT_MODEL".
812 857
813 When set to 2 or higher, cause AnyEvent to report to STDERR which 858 When set to 2 or higher, cause AnyEvent to report to STDERR which
814 event model it chooses. 859 event model it chooses.
860
861 "PERL_ANYEVENT_STRICT"
862 AnyEvent does not do much argument checking by default, as thorough
863 argument checking is very costly. Setting this variable to a true
864 value will cause AnyEvent to load "AnyEvent::Strict" and then to
865 thoroughly check the arguments passed to most method calls. If it
866 finds any problems it will croak.
867
868 In other words, enables "strict" mode.
869
870 Unlike "use strict", it is definitely recommended ot keep it off in
871 production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment
872 while developing programs can be very useful, however.
815 873
816 "PERL_ANYEVENT_MODEL" 874 "PERL_ANYEVENT_MODEL"
817 This can be used to specify the event model to be used by AnyEvent, 875 This can be used to specify the event model to be used by AnyEvent,
818 before auto detection and -probing kicks in. It must be a string 876 before auto detection and -probing kicks in. It must be a string
819 consisting entirely of ASCII letters. The string "AnyEvent::Impl::" 877 consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
… …
838 mentioned will be used, and preference will be given to protocols 896 mentioned will be used, and preference will be given to protocols
839 mentioned earlier in the list. 897 mentioned earlier in the list.
840 898
841 This variable can effectively be used for denial-of-service attacks 899 This variable can effectively be used for denial-of-service attacks
842 against local programs (e.g. when setuid), although the impact is 900 against local programs (e.g. when setuid), although the impact is
843 likely small, as the program has to handle connection errors 901 likely small, as the program has to handle conenction and other
844 already- 902 failures anyways.
845 903
846 Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over 904 Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over
847 IPv6, but support both and try to use both. 905 IPv6, but support both and try to use both.
848 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to 906 "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
849 resolve or contact IPv6 addresses. 907 resolve or contact IPv6 addresses.
… …
860 EDNS0 in its DNS requests. 918 EDNS0 in its DNS requests.
861 919
862 "PERL_ANYEVENT_MAX_FORKS" 920 "PERL_ANYEVENT_MAX_FORKS"
863 The maximum number of child processes that 921 The maximum number of child processes that
864 "AnyEvent::Util::fork_call" will create in parallel. 922 "AnyEvent::Util::fork_call" will create in parallel.
923
924SUPPLYING YOUR OWN EVENT MODEL INTERFACE
925 This is an advanced topic that you do not normally need to use AnyEvent
926 in a module. This section is only of use to event loop authors who want
927 to provide AnyEvent compatibility.
928
929 If you need to support another event library which isn't directly
930 supported by AnyEvent, you can supply your own interface to it by
931 pushing, before the first watcher gets created, the package name of the
932 event module and the package name of the interface to use onto
933 @AnyEvent::REGISTRY. You can do that before and even without loading
934 AnyEvent, so it is reasonably cheap.
935
936 Example:
937
938 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
939
940 This tells AnyEvent to (literally) use the "urxvt::anyevent::"
941 package/class when it finds the "urxvt" package/module is already
942 loaded.
943
944 When AnyEvent is loaded and asked to find a suitable event model, it
945 will first check for the presence of urxvt by trying to "use" the
946 "urxvt::anyevent" module.
947
948 The class should provide implementations for all watcher types. See
949 AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
950 so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
951 the sources.
952
953 If you don't provide "signal" and "child" watchers than AnyEvent will
954 provide suitable (hopefully) replacements.
955
956 The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt)
957 terminal emulator uses the above line as-is. An interface isn't included
958 in AnyEvent because it doesn't make sense outside the embedded
959 interpreter inside *rxvt-unicode*, and it is updated and maintained as
960 part of the *rxvt-unicode* distribution.
961
962 *rxvt-unicode* also cheats a bit by not providing blocking access to
963 condition variables: code blocking while waiting for a condition will
964 "die". This still works with most modules/usages, and blocking calls
965 must not be done in an interactive application, so it makes sense.
865 966
866EXAMPLE PROGRAM 967EXAMPLE PROGRAM
867 The following program uses an I/O watcher to read data from STDIN, a 968 The following program uses an I/O watcher to read data from STDIN, a
868 timer to display a message once per second, and a condition variable to 969 timer to display a message once per second, and a condition variable to
869 quit the program when the user enters quit: 970 quit the program when the user enters quit:
… …
1056 *destroy* is the time, in microseconds, that it takes to destroy a 1157 *destroy* is the time, in microseconds, that it takes to destroy a
1057 single watcher. 1158 single watcher.
1058 1159
1059 Results 1160 Results
1060 name watchers bytes create invoke destroy comment 1161 name watchers bytes create invoke destroy comment
1061 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1162 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1062 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1163 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1063 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1164 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1064 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1165 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1065 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1166 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1066 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1167 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1067 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1168 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1068 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1169 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1069 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1170 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1070 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1171 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1071 1172
1072 Discussion 1173 Discussion
1073 The benchmark does *not* measure scalability of the event loop very 1174 The benchmark does *not* measure scalability of the event loop very
1074 well. For example, a select-based event loop (such as the pure perl one) 1175 well. For example, a select-based event loop (such as the pure perl one)
1075 can never compete with an event loop that uses epoll when the number of 1176 can never compete with an event loop that uses epoll when the number of
… …
1256 1357
1257 Summary 1358 Summary
1258 * C-based event loops perform very well with small number of watchers, 1359 * C-based event loops perform very well with small number of watchers,
1259 as the management overhead dominates. 1360 as the management overhead dominates.
1260 1361
1362SIGNALS
1363 AnyEvent currently installs handlers for these signals:
1364
1365 SIGCHLD
1366 A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1367 emulation for event loops that do not support them natively. Also,
1368 some event loops install a similar handler.
1369
1370 SIGPIPE
1371 A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1372 "undef" when AnyEvent gets loaded.
1373
1374 The rationale for this is that AnyEvent users usually do not really
1375 depend on SIGPIPE delivery (which is purely an optimisation for
1376 shell use, or badly-written programs), but "SIGPIPE" can cause
1377 spurious and rare program exits as a lot of people do not expect
1378 "SIGPIPE" when writing to some random socket.
1379
1380 The rationale for installing a no-op handler as opposed to ignoring
1381 it is that this way, the handler will be restored to defaults on
1382 exec.
1383
1384 Feel free to install your own handler, or reset it to defaults.
1385
1261FORK 1386FORK
1262 Most event libraries are not fork-safe. The ones who are usually are 1387 Most event libraries are not fork-safe. The ones who are usually are
1263 because they rely on inefficient but fork-safe "select" or "poll" calls. 1388 because they rely on inefficient but fork-safe "select" or "poll" calls.
1264 Only EV is fully fork-aware. 1389 Only EV is fully fork-aware.
1265 1390
… …
1281 1406
1282 use AnyEvent; 1407 use AnyEvent;
1283 1408
1284 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1409 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1285 be used to probe what backend is used and gain other information (which 1410 be used to probe what backend is used and gain other information (which
1286 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1411 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1412 and $ENV{PERL_ANYEGENT_STRICT}.
1287 1413
1288BUGS 1414BUGS
1289 Perl 5.8 has numerous memleaks that sometimes hit this module and are 1415 Perl 5.8 has numerous memleaks that sometimes hit this module and are
1290 hard to work around. If you suffer from memleaks, first upgrade to Perl 1416 hard to work around. If you suffer from memleaks, first upgrade to Perl
1291 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other 1417 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1292 annoying mamleaks, such as leaking on "map" and "grep" but it is usually 1418 annoying memleaks, such as leaking on "map" and "grep" but it is usually
1293 not as pronounced). 1419 not as pronounced).
1294 1420
1295SEE ALSO 1421SEE ALSO
1296 Utility functions: AnyEvent::Util. 1422 Utility functions: AnyEvent::Util.
1297 1423

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