1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - provide framework for multiple event loops |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | loops |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
|
|
10 | # file descriptor readable |
10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
11 | |
12 | |
|
|
13 | # one-shot or repeating timers |
12 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
13 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
14 | |
16 | |
15 | print AnyEvent->now; # prints current event loop time |
17 | print AnyEvent->now; # prints current event loop time |
16 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
17 | |
19 | |
|
|
20 | # POSIX signal |
18 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
19 | |
22 | |
|
|
23 | # child process exit |
20 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
21 | my ($pid, $status) = @_; |
25 | my ($pid, $status) = @_; |
22 | ... |
26 | ... |
23 | }); |
27 | }); |
|
|
28 | |
|
|
29 | # called when event loop idle (if applicable) |
|
|
30 | my $w = AnyEvent->idle (cb => sub { ... }); |
24 | |
31 | |
25 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
26 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
27 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
28 | # use a condvar in callback mode: |
35 | # use a condvar in callback mode: |
… | |
… | |
132 | These watchers are normal Perl objects with normal Perl lifetime. After |
139 | These watchers are normal Perl objects with normal Perl lifetime. After |
133 | creating a watcher it will immediately "watch" for events and invoke the |
140 | creating a watcher it will immediately "watch" for events and invoke the |
134 | callback when the event occurs (of course, only when the event model is |
141 | callback when the event occurs (of course, only when the event model is |
135 | in control). |
142 | in control). |
136 | |
143 | |
|
|
144 | Note that callbacks must not permanently change global variables |
|
|
145 | potentially in use by the event loop (such as $_ or $[) and that |
|
|
146 | callbacks must not "die". The former is good programming practise in |
|
|
147 | Perl and the latter stems from the fact that exception handling differs |
|
|
148 | widely between event loops. |
|
|
149 | |
137 | To disable the watcher you have to destroy it (e.g. by setting the |
150 | To disable the watcher you have to destroy it (e.g. by setting the |
138 | variable you store it in to "undef" or otherwise deleting all references |
151 | variable you store it in to "undef" or otherwise deleting all references |
139 | to it). |
152 | to it). |
140 | |
153 | |
141 | All watchers are created by calling a method on the "AnyEvent" class. |
154 | All watchers are created by calling a method on the "AnyEvent" class. |
… | |
… | |
156 | |
169 | |
157 | I/O WATCHERS |
170 | I/O WATCHERS |
158 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
159 | the following mandatory key-value pairs as arguments: |
172 | the following mandatory key-value pairs as arguments: |
160 | |
173 | |
161 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events |
174 | "fh" is the Perl *file handle* (*not* file descriptor) to watch for |
162 | (AnyEvent might or might not keep a reference to this file handle). |
175 | events (AnyEvent might or might not keep a reference to this file |
|
|
176 | handle). Note that only file handles pointing to things for which |
|
|
177 | non-blocking operation makes sense are allowed. This includes sockets, |
|
|
178 | most character devices, pipes, fifos and so on, but not for example |
|
|
179 | files or block devices. |
|
|
180 | |
163 | "poll" must be a string that is either "r" or "w", which creates a |
181 | "poll" must be a string that is either "r" or "w", which creates a |
164 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
182 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
|
|
183 | |
165 | is the callback to invoke each time the file handle becomes ready. |
184 | "cb" is the callback to invoke each time the file handle becomes ready. |
166 | |
185 | |
167 | Although the callback might get passed parameters, their value and |
186 | Although the callback might get passed parameters, their value and |
168 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
169 | callbacks cannot use arguments passed to I/O watcher callbacks. |
188 | callbacks cannot use arguments passed to I/O watcher callbacks. |
170 | |
189 | |
… | |
… | |
301 | |
320 | |
302 | In either case, if you care (and in most cases, you don't), then you |
321 | In either case, if you care (and in most cases, you don't), then you |
303 | can get whatever behaviour you want with any event loop, by taking |
322 | can get whatever behaviour you want with any event loop, by taking |
304 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
323 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
305 | account. |
324 | account. |
|
|
325 | |
|
|
326 | AnyEvent->now_update |
|
|
327 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
|
|
328 | current time for each loop iteration (see the discussion of |
|
|
329 | AnyEvent->now, above). |
|
|
330 | |
|
|
331 | When a callback runs for a long time (or when the process sleeps), |
|
|
332 | then this "current" time will differ substantially from the real |
|
|
333 | time, which might affect timers and time-outs. |
|
|
334 | |
|
|
335 | When this is the case, you can call this method, which will update |
|
|
336 | the event loop's idea of "current time". |
|
|
337 | |
|
|
338 | Note that updating the time *might* cause some events to be handled. |
306 | |
339 | |
307 | SIGNAL WATCHERS |
340 | SIGNAL WATCHERS |
308 | You can watch for signals using a signal watcher, "signal" is the signal |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
309 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
310 | callback to be invoked whenever a signal occurs. |
343 | callback to be invoked whenever a signal occurs. |
… | |
… | |
374 | ); |
407 | ); |
375 | |
408 | |
376 | # do something else, then wait for process exit |
409 | # do something else, then wait for process exit |
377 | $done->recv; |
410 | $done->recv; |
378 | |
411 | |
|
|
412 | IDLE WATCHERS |
|
|
413 | Sometimes there is a need to do something, but it is not so important to |
|
|
414 | do it instantly, but only when there is nothing better to do. This |
|
|
415 | "nothing better to do" is usually defined to be "no other events need |
|
|
416 | attention by the event loop". |
|
|
417 | |
|
|
418 | Idle watchers ideally get invoked when the event loop has nothing better |
|
|
419 | to do, just before it would block the process to wait for new events. |
|
|
420 | Instead of blocking, the idle watcher is invoked. |
|
|
421 | |
|
|
422 | Most event loops unfortunately do not really support idle watchers (only |
|
|
423 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
|
|
424 | will simply call the callback "from time to time". |
|
|
425 | |
|
|
426 | Example: read lines from STDIN, but only process them when the program |
|
|
427 | is otherwise idle: |
|
|
428 | |
|
|
429 | my @lines; # read data |
|
|
430 | my $idle_w; |
|
|
431 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
432 | push @lines, scalar <STDIN>; |
|
|
433 | |
|
|
434 | # start an idle watcher, if not already done |
|
|
435 | $idle_w ||= AnyEvent->idle (cb => sub { |
|
|
436 | # handle only one line, when there are lines left |
|
|
437 | if (my $line = shift @lines) { |
|
|
438 | print "handled when idle: $line"; |
|
|
439 | } else { |
|
|
440 | # otherwise disable the idle watcher again |
|
|
441 | undef $idle_w; |
|
|
442 | } |
|
|
443 | }); |
|
|
444 | }); |
|
|
445 | |
379 | CONDITION VARIABLES |
446 | CONDITION VARIABLES |
380 | If you are familiar with some event loops you will know that all of them |
447 | If you are familiar with some event loops you will know that all of them |
381 | require you to run some blocking "loop", "run" or similar function that |
448 | require you to run some blocking "loop", "run" or similar function that |
382 | will actively watch for new events and call your callbacks. |
449 | will actively watch for new events and call your callbacks. |
383 | |
450 | |
… | |
… | |
870 | mentioned will be used, and preference will be given to protocols |
937 | mentioned will be used, and preference will be given to protocols |
871 | mentioned earlier in the list. |
938 | mentioned earlier in the list. |
872 | |
939 | |
873 | This variable can effectively be used for denial-of-service attacks |
940 | This variable can effectively be used for denial-of-service attacks |
874 | against local programs (e.g. when setuid), although the impact is |
941 | against local programs (e.g. when setuid), although the impact is |
875 | likely small, as the program has to handle connection errors |
942 | likely small, as the program has to handle conenction and other |
876 | already- |
943 | failures anyways. |
877 | |
944 | |
878 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
945 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
879 | IPv6, but support both and try to use both. |
946 | IPv6, but support both and try to use both. |
880 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
947 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
881 | resolve or contact IPv6 addresses. |
948 | resolve or contact IPv6 addresses. |
… | |
… | |
1131 | *destroy* is the time, in microseconds, that it takes to destroy a |
1198 | *destroy* is the time, in microseconds, that it takes to destroy a |
1132 | single watcher. |
1199 | single watcher. |
1133 | |
1200 | |
1134 | Results |
1201 | Results |
1135 | name watchers bytes create invoke destroy comment |
1202 | name watchers bytes create invoke destroy comment |
1136 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1203 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1137 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1204 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1138 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1205 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1139 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1206 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1140 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1207 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1141 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1208 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1142 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1209 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1143 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1210 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1144 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1211 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1145 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1212 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1146 | |
1213 | |
1147 | Discussion |
1214 | Discussion |
1148 | The benchmark does *not* measure scalability of the event loop very |
1215 | The benchmark does *not* measure scalability of the event loop very |
1149 | well. For example, a select-based event loop (such as the pure perl one) |
1216 | well. For example, a select-based event loop (such as the pure perl one) |
1150 | can never compete with an event loop that uses epoll when the number of |
1217 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1387 | |
1454 | |
1388 | BUGS |
1455 | BUGS |
1389 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1456 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1390 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1457 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1391 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1458 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1392 | annoying mamleaks, such as leaking on "map" and "grep" but it is usually |
1459 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1393 | not as pronounced). |
1460 | not as pronounced). |
1394 | |
1461 | |
1395 | SEE ALSO |
1462 | SEE ALSO |
1396 | Utility functions: AnyEvent::Util. |
1463 | Utility functions: AnyEvent::Util. |
1397 | |
1464 | |