… | |
… | |
5 | loops |
5 | loops |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
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 | |
22 | INTRODUCTION/TUTORIAL |
31 | INTRODUCTION/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. |
… | |
… | |
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 |
… | |
… | |
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 | |
|
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137 | Note that callbacks must not permanently change global variables |
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138 | potentially in use by the event loop (such as $_ or $[) and that |
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139 | callbacks must not "die". The former is good programming practise in |
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|
140 | Perl and the latter stems from the fact that exception handling differs |
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141 | widely between event loops. |
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|
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. |
… | |
… | |
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 |
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168 | events (AnyEvent might or might not keep a reference to this file |
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169 | handle). Note that only file handles pointing to things for which |
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170 | non-blocking operation makes sense are allowed. This includes sockets, |
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171 | most character devices, pipes, fifos and so on, but not for example |
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172 | files or block devices. |
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|
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 | |
… | |
… | |
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 | }); |
… | |
… | |
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 |
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|
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 |
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|
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"). |
… | |
… | |
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 | |
298 | SIGNAL WATCHERS |
319 | SIGNAL WATCHERS |
299 | You can watch for signals using a signal watcher, "signal" is the signal |
320 | 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 |
321 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
301 | whenever a signal occurs. |
322 | callback to be invoked whenever a signal occurs. |
302 | |
323 | |
303 | Although the callback might get passed parameters, their value and |
324 | Although the callback might get passed parameters, their value and |
304 | presence is undefined and you cannot rely on them. Portable AnyEvent |
325 | presence is undefined and you cannot rely on them. Portable AnyEvent |
305 | callbacks cannot use arguments passed to signal watcher callbacks. |
326 | callbacks cannot use arguments passed to signal watcher callbacks. |
306 | |
327 | |
… | |
… | |
321 | |
342 | |
322 | CHILD PROCESS WATCHERS |
343 | CHILD PROCESS WATCHERS |
323 | You can also watch on a child process exit and catch its exit status. |
344 | You can also watch on a child process exit and catch its exit status. |
324 | |
345 | |
325 | The child process is specified by the "pid" argument (if set to 0, it |
346 | 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 |
347 | 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 |
348 | 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 |
349 | on any trace events (stopped/continued). |
329 | and exit status (as returned by waitpid), so unlike other watcher types, |
350 | |
330 | you *can* rely on child watcher callback arguments. |
351 | The callback will be called with the pid and exit status (as returned by |
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|
352 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
|
|
353 | callback arguments. |
|
|
354 | |
|
|
355 | This watcher type works by installing a signal handler for "SIGCHLD", |
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|
356 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
|
|
357 | random child processes (waiting for specific child processes, e.g. |
|
|
358 | inside "system", is just fine). |
331 | |
359 | |
332 | There is a slight catch to child watchers, however: you usually start |
360 | 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 |
361 | them *after* the child process was created, and this means the process |
334 | could have exited already (and no SIGCHLD will be sent anymore). |
362 | could have exited already (and no SIGCHLD will be sent anymore). |
335 | |
363 | |
… | |
… | |
371 | The instrument to do that is called a "condition variable", so called |
399 | The instrument to do that is called a "condition variable", so called |
372 | because they represent a condition that must become true. |
400 | because they represent a condition that must become true. |
373 | |
401 | |
374 | Condition variables can be created by calling the "AnyEvent->condvar" |
402 | Condition variables can be created by calling the "AnyEvent->condvar" |
375 | method, usually without arguments. The only argument pair allowed is |
403 | method, usually without arguments. The only argument pair allowed is |
|
|
404 | |
376 | "cb", which specifies a callback to be called when the condition |
405 | "cb", which specifies a callback to be called when the condition |
377 | variable becomes true. |
406 | variable becomes true, with the condition variable as the first argument |
|
|
407 | (but not the results). |
378 | |
408 | |
379 | After creation, the condition variable is "false" until it becomes |
409 | After creation, the condition variable is "false" until it becomes |
380 | "true" by calling the "send" method (or calling the condition variable |
410 | "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 |
411 | as if it were a callback, read about the caveats in the description for |
382 | the "->send" method). |
412 | the "->send" method). |
… | |
… | |
438 | |
468 | |
439 | my $done = AnyEvent->condvar; |
469 | my $done = AnyEvent->condvar; |
440 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
470 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
441 | $done->recv; |
471 | $done->recv; |
442 | |
472 | |
|
|
473 | Example: Imagine an API that returns a condvar and doesn't support |
|
|
474 | callbacks. This is how you make a synchronous call, for example from the |
|
|
475 | main program: |
|
|
476 | |
|
|
477 | use AnyEvent::CouchDB; |
|
|
478 | |
|
|
479 | ... |
|
|
480 | |
|
|
481 | my @info = $couchdb->info->recv; |
|
|
482 | |
|
|
483 | And this is how you would just ste a callback to be called whenever the |
|
|
484 | results are available: |
|
|
485 | |
|
|
486 | $couchdb->info->cb (sub { |
|
|
487 | my @info = $_[0]->recv; |
|
|
488 | }); |
|
|
489 | |
443 | METHODS FOR PRODUCERS |
490 | METHODS FOR PRODUCERS |
444 | These methods should only be used by the producing side, i.e. the |
491 | 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 |
492 | 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 |
493 | producer side which creates the condvar in most cases, but it isn't |
447 | uncommon for the consumer to create it as well. |
494 | uncommon for the consumer to create it as well. |
… | |
… | |
567 | |
614 | |
568 | $bool = $cv->ready |
615 | $bool = $cv->ready |
569 | Returns true when the condition is "true", i.e. whether "send" or |
616 | Returns true when the condition is "true", i.e. whether "send" or |
570 | "croak" have been called. |
617 | "croak" have been called. |
571 | |
618 | |
572 | $cb = $cv->cb ([new callback]) |
619 | $cb = $cv->cb ($cb->($cv)) |
573 | This is a mutator function that returns the callback set and |
620 | This is a mutator function that returns the callback set and |
574 | optionally replaces it before doing so. |
621 | optionally replaces it before doing so. |
575 | |
622 | |
576 | The callback will be called when the condition becomes "true", i.e. |
623 | 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 |
624 | when "send" or "croak" are called, with the only argument being the |
… | |
… | |
698 | AnyEvent::Util |
745 | AnyEvent::Util |
699 | Contains various utility functions that replace often-used but |
746 | Contains various utility functions that replace often-used but |
700 | blocking functions such as "inet_aton" by event-/callback-based |
747 | blocking functions such as "inet_aton" by event-/callback-based |
701 | versions. |
748 | versions. |
702 | |
749 | |
703 | AnyEvent::Handle |
|
|
704 | Provide read and write buffers and manages watchers for reads and |
|
|
705 | writes. |
|
|
706 | |
|
|
707 | AnyEvent::Socket |
750 | AnyEvent::Socket |
708 | Provides various utility functions for (internet protocol) sockets, |
751 | Provides various utility functions for (internet protocol) sockets, |
709 | addresses and name resolution. Also functions to create non-blocking |
752 | addresses and name resolution. Also functions to create non-blocking |
710 | tcp connections or tcp servers, with IPv6 and SRV record support and |
753 | tcp connections or tcp servers, with IPv6 and SRV record support and |
711 | more. |
754 | more. |
712 | |
755 | |
|
|
756 | AnyEvent::Handle |
|
|
757 | Provide read and write buffers, manages watchers for reads and |
|
|
758 | writes, supports raw and formatted I/O, I/O queued and fully |
|
|
759 | transparent and non-blocking SSL/TLS. |
|
|
760 | |
713 | AnyEvent::DNS |
761 | AnyEvent::DNS |
714 | Provides rich asynchronous DNS resolver capabilities. |
762 | Provides rich asynchronous DNS resolver capabilities. |
715 | |
763 | |
|
|
764 | AnyEvent::HTTP |
|
|
765 | A simple-to-use HTTP library that is capable of making a lot of |
|
|
766 | concurrent HTTP requests. |
|
|
767 | |
716 | AnyEvent::HTTPD |
768 | AnyEvent::HTTPD |
717 | Provides a simple web application server framework. |
769 | Provides a simple web application server framework. |
718 | |
770 | |
719 | AnyEvent::FastPing |
771 | AnyEvent::FastPing |
720 | The fastest ping in the west. |
772 | The fastest ping in the west. |
721 | |
773 | |
|
|
774 | AnyEvent::DBI |
|
|
775 | Executes DBI requests asynchronously in a proxy process. |
|
|
776 | |
|
|
777 | AnyEvent::AIO |
|
|
778 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
779 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
780 | together. |
|
|
781 | |
|
|
782 | AnyEvent::BDB |
|
|
783 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
784 | fuses BDB and AnyEvent together. |
|
|
785 | |
|
|
786 | AnyEvent::GPSD |
|
|
787 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
788 | information. |
|
|
789 | |
|
|
790 | AnyEvent::IGS |
|
|
791 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
792 | App::IGS). |
|
|
793 | |
|
|
794 | AnyEvent::IRC |
|
|
795 | AnyEvent based IRC client module family (replacing the older |
722 | Net::IRC3 |
796 | Net::IRC3). |
723 | AnyEvent based IRC client module family. |
|
|
724 | |
797 | |
725 | Net::XMPP2 |
798 | Net::XMPP2 |
726 | AnyEvent based XMPP (Jabber protocol) module family. |
799 | AnyEvent based XMPP (Jabber protocol) module family. |
727 | |
800 | |
728 | Net::FCP |
801 | Net::FCP |
… | |
… | |
733 | High level API for event-based execution flow control. |
806 | High level API for event-based execution flow control. |
734 | |
807 | |
735 | Coro |
808 | Coro |
736 | Has special support for AnyEvent via Coro::AnyEvent. |
809 | Has special support for AnyEvent via Coro::AnyEvent. |
737 | |
810 | |
738 | AnyEvent::AIO, IO::AIO |
|
|
739 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
740 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
741 | together. |
|
|
742 | |
|
|
743 | AnyEvent::BDB, BDB |
|
|
744 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently |
|
|
745 | fuses IO::AIO and AnyEvent together. |
|
|
746 | |
|
|
747 | IO::Lambda |
811 | IO::Lambda |
748 | The lambda approach to I/O - don't ask, look there. Can use |
812 | The lambda approach to I/O - don't ask, look there. Can use |
749 | AnyEvent. |
813 | AnyEvent. |
750 | |
814 | |
751 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
815 | ERROR AND EXCEPTION HANDLING |
752 | This is an advanced topic that you do not normally need to use AnyEvent |
816 | In general, AnyEvent does not do any error handling - it relies on the |
753 | in a module. This section is only of use to event loop authors who want |
817 | caller to do that if required. The AnyEvent::Strict module (see also the |
754 | to provide AnyEvent compatibility. |
818 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
819 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
820 | development. |
755 | |
821 | |
756 | If you need to support another event library which isn't directly |
822 | As for exception handling (i.e. runtime errors and exceptions thrown |
757 | supported by AnyEvent, you can supply your own interface to it by |
823 | while executing a callback), this is not only highly event-loop |
758 | pushing, before the first watcher gets created, the package name of the |
824 | specific, but also not in any way wrapped by this module, as this is the |
759 | event module and the package name of the interface to use onto |
825 | job of the main program. |
760 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
761 | AnyEvent, so it is reasonably cheap. |
|
|
762 | |
826 | |
763 | Example: |
827 | The pure perl event loop simply re-throws the exception (usually within |
764 | |
828 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
765 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
829 | Glib uses "install_exception_handler" and so on. |
766 | |
|
|
767 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
768 | package/class when it finds the "urxvt" package/module is already |
|
|
769 | loaded. |
|
|
770 | |
|
|
771 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
772 | will first check for the presence of urxvt by trying to "use" the |
|
|
773 | "urxvt::anyevent" module. |
|
|
774 | |
|
|
775 | The class should provide implementations for all watcher types. See |
|
|
776 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
777 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
778 | the sources. |
|
|
779 | |
|
|
780 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
781 | provide suitable (hopefully) replacements. |
|
|
782 | |
|
|
783 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
784 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
785 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
786 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
787 | part of the *rxvt-unicode* distribution. |
|
|
788 | |
|
|
789 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
790 | condition variables: code blocking while waiting for a condition will |
|
|
791 | "die". This still works with most modules/usages, and blocking calls |
|
|
792 | must not be done in an interactive application, so it makes sense. |
|
|
793 | |
830 | |
794 | ENVIRONMENT VARIABLES |
831 | ENVIRONMENT VARIABLES |
795 | The following environment variables are used by this module: |
832 | The following environment variables are used by this module or its |
|
|
833 | submodules: |
796 | |
834 | |
797 | "PERL_ANYEVENT_VERBOSE" |
835 | "PERL_ANYEVENT_VERBOSE" |
798 | By default, AnyEvent will be completely silent except in fatal |
836 | By default, AnyEvent will be completely silent except in fatal |
799 | conditions. You can set this environment variable to make AnyEvent |
837 | conditions. You can set this environment variable to make AnyEvent |
800 | more talkative. |
838 | more talkative. |
… | |
… | |
803 | conditions, such as not being able to load the event model specified |
841 | conditions, such as not being able to load the event model specified |
804 | by "PERL_ANYEVENT_MODEL". |
842 | by "PERL_ANYEVENT_MODEL". |
805 | |
843 | |
806 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
844 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
807 | event model it chooses. |
845 | event model it chooses. |
|
|
846 | |
|
|
847 | "PERL_ANYEVENT_STRICT" |
|
|
848 | AnyEvent does not do much argument checking by default, as thorough |
|
|
849 | argument checking is very costly. Setting this variable to a true |
|
|
850 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
|
|
851 | thoroughly check the arguments passed to most method calls. If it |
|
|
852 | finds any problems it will croak. |
|
|
853 | |
|
|
854 | In other words, enables "strict" mode. |
|
|
855 | |
|
|
856 | Unlike "use strict", it is definitely recommended ot keep it off in |
|
|
857 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
|
|
858 | while developing programs can be very useful, however. |
808 | |
859 | |
809 | "PERL_ANYEVENT_MODEL" |
860 | "PERL_ANYEVENT_MODEL" |
810 | This can be used to specify the event model to be used by AnyEvent, |
861 | This can be used to specify the event model to be used by AnyEvent, |
811 | before auto detection and -probing kicks in. It must be a string |
862 | before auto detection and -probing kicks in. It must be a string |
812 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
863 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
831 | mentioned will be used, and preference will be given to protocols |
882 | mentioned will be used, and preference will be given to protocols |
832 | mentioned earlier in the list. |
883 | mentioned earlier in the list. |
833 | |
884 | |
834 | This variable can effectively be used for denial-of-service attacks |
885 | This variable can effectively be used for denial-of-service attacks |
835 | against local programs (e.g. when setuid), although the impact is |
886 | against local programs (e.g. when setuid), although the impact is |
836 | likely small, as the program has to handle connection errors |
887 | likely small, as the program has to handle conenction and other |
837 | already- |
888 | failures anyways. |
838 | |
889 | |
839 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
890 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
840 | IPv6, but support both and try to use both. |
891 | IPv6, but support both and try to use both. |
841 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
892 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
842 | resolve or contact IPv6 addresses. |
893 | resolve or contact IPv6 addresses. |
… | |
… | |
853 | EDNS0 in its DNS requests. |
904 | EDNS0 in its DNS requests. |
854 | |
905 | |
855 | "PERL_ANYEVENT_MAX_FORKS" |
906 | "PERL_ANYEVENT_MAX_FORKS" |
856 | The maximum number of child processes that |
907 | The maximum number of child processes that |
857 | "AnyEvent::Util::fork_call" will create in parallel. |
908 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
909 | |
|
|
910 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
911 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
912 | in a module. This section is only of use to event loop authors who want |
|
|
913 | to provide AnyEvent compatibility. |
|
|
914 | |
|
|
915 | If you need to support another event library which isn't directly |
|
|
916 | supported by AnyEvent, you can supply your own interface to it by |
|
|
917 | pushing, before the first watcher gets created, the package name of the |
|
|
918 | event module and the package name of the interface to use onto |
|
|
919 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
920 | AnyEvent, so it is reasonably cheap. |
|
|
921 | |
|
|
922 | Example: |
|
|
923 | |
|
|
924 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
925 | |
|
|
926 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
927 | package/class when it finds the "urxvt" package/module is already |
|
|
928 | loaded. |
|
|
929 | |
|
|
930 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
931 | will first check for the presence of urxvt by trying to "use" the |
|
|
932 | "urxvt::anyevent" module. |
|
|
933 | |
|
|
934 | The class should provide implementations for all watcher types. See |
|
|
935 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
936 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
937 | the sources. |
|
|
938 | |
|
|
939 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
940 | provide suitable (hopefully) replacements. |
|
|
941 | |
|
|
942 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
943 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
944 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
945 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
946 | part of the *rxvt-unicode* distribution. |
|
|
947 | |
|
|
948 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
949 | condition variables: code blocking while waiting for a condition will |
|
|
950 | "die". This still works with most modules/usages, and blocking calls |
|
|
951 | must not be done in an interactive application, so it makes sense. |
858 | |
952 | |
859 | EXAMPLE PROGRAM |
953 | EXAMPLE PROGRAM |
860 | The following program uses an I/O watcher to read data from STDIN, a |
954 | The following program uses an I/O watcher to read data from STDIN, a |
861 | timer to display a message once per second, and a condition variable to |
955 | timer to display a message once per second, and a condition variable to |
862 | quit the program when the user enters quit: |
956 | quit the program when the user enters quit: |
… | |
… | |
1049 | *destroy* is the time, in microseconds, that it takes to destroy a |
1143 | *destroy* is the time, in microseconds, that it takes to destroy a |
1050 | single watcher. |
1144 | single watcher. |
1051 | |
1145 | |
1052 | Results |
1146 | Results |
1053 | name watchers bytes create invoke destroy comment |
1147 | name watchers bytes create invoke destroy comment |
1054 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1148 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1055 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1149 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1056 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1150 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1057 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1151 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1058 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1152 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1059 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1153 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1060 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1154 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1061 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1155 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1062 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1156 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1063 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1157 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1064 | |
1158 | |
1065 | Discussion |
1159 | Discussion |
1066 | The benchmark does *not* measure scalability of the event loop very |
1160 | The benchmark does *not* measure scalability of the event loop very |
1067 | well. For example, a select-based event loop (such as the pure perl one) |
1161 | well. For example, a select-based event loop (such as the pure perl one) |
1068 | can never compete with an event loop that uses epoll when the number of |
1162 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1249 | |
1343 | |
1250 | Summary |
1344 | Summary |
1251 | * C-based event loops perform very well with small number of watchers, |
1345 | * C-based event loops perform very well with small number of watchers, |
1252 | as the management overhead dominates. |
1346 | as the management overhead dominates. |
1253 | |
1347 | |
|
|
1348 | SIGNALS |
|
|
1349 | AnyEvent currently installs handlers for these signals: |
|
|
1350 | |
|
|
1351 | SIGCHLD |
|
|
1352 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1353 | emulation for event loops that do not support them natively. Also, |
|
|
1354 | some event loops install a similar handler. |
|
|
1355 | |
|
|
1356 | SIGPIPE |
|
|
1357 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1358 | "undef" when AnyEvent gets loaded. |
|
|
1359 | |
|
|
1360 | The rationale for this is that AnyEvent users usually do not really |
|
|
1361 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1362 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1363 | spurious and rare program exits as a lot of people do not expect |
|
|
1364 | "SIGPIPE" when writing to some random socket. |
|
|
1365 | |
|
|
1366 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1367 | it is that this way, the handler will be restored to defaults on |
|
|
1368 | exec. |
|
|
1369 | |
|
|
1370 | Feel free to install your own handler, or reset it to defaults. |
|
|
1371 | |
1254 | FORK |
1372 | FORK |
1255 | Most event libraries are not fork-safe. The ones who are usually are |
1373 | Most event libraries are not fork-safe. The ones who are usually are |
1256 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1374 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1257 | Only EV is fully fork-aware. |
1375 | Only EV is fully fork-aware. |
1258 | |
1376 | |
… | |
… | |
1274 | |
1392 | |
1275 | use AnyEvent; |
1393 | use AnyEvent; |
1276 | |
1394 | |
1277 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1395 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1278 | be used to probe what backend is used and gain other information (which |
1396 | be used to probe what backend is used and gain other information (which |
1279 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1397 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
|
|
1398 | and $ENV{PERL_ANYEGENT_STRICT}. |
|
|
1399 | |
|
|
1400 | BUGS |
|
|
1401 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
|
|
1402 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
|
|
1403 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
|
|
1404 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
|
|
1405 | not as pronounced). |
1280 | |
1406 | |
1281 | SEE ALSO |
1407 | SEE ALSO |
1282 | Utility functions: AnyEvent::Util. |
1408 | Utility functions: AnyEvent::Util. |
1283 | |
1409 | |
1284 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1410 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |