… | |
… | |
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 | |
|
|
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. |
… | |
… | |
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 | |
… | |
… | |
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 |
|
|
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"). |
… | |
… | |
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 | |
… | |
… | |
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 | |
… | |
… | |
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). |
… | |
… | |
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. |
… | |
… | |
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 |
… | |
… | |
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 |
… | |
… | |
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 |
… | |
… | |
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 | |
758 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
829 | ERROR 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 | |
801 | ENVIRONMENT VARIABLES |
845 | ENVIRONMENT 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 | |
|
|
924 | SUPPLYING 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 | |
866 | EXAMPLE PROGRAM |
967 | EXAMPLE 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 | |
|
|
1362 | SIGNALS |
|
|
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 | |
1261 | FORK |
1386 | FORK |
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 | |
1288 | BUGS |
1414 | BUGS |
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 | |
1295 | SEE ALSO |
1421 | SEE ALSO |
1296 | Utility functions: AnyEvent::Util. |
1422 | Utility functions: AnyEvent::Util. |
1297 | |
1423 | |