1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | loops |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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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 { ... }); |
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12 | |
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13 | # one-shot or repeating timers |
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14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
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15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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16 | |
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17 | print AnyEvent->now; # prints current event loop time |
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18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
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19 | |
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20 | # POSIX signal |
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21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
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22 | |
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23 | # child process exit |
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24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
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25 | my ($pid, $status) = @_; |
11 | ... |
26 | ... |
12 | }); |
27 | }); |
13 | |
28 | |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
29 | # called when event loop idle (if applicable) |
15 | ... |
30 | my $w = AnyEvent->idle (cb => sub { ... }); |
16 | }); |
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17 | |
31 | |
18 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
20 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
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35 | # use a condvar in callback mode: |
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36 | $w->cb (sub { $_[0]->recv }); |
21 | |
37 | |
22 | INTRODUCTION/TUTORIAL |
38 | INTRODUCTION/TUTORIAL |
23 | This manpage is mainly a reference manual. If you are interested in a |
39 | 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 |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
25 | manpage. |
41 | manpage. |
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42 | |
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43 | SUPPORT |
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44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
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45 | channel, too. |
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46 | |
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47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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48 | Repository, at <http://anyevent.schmorp.de>, for more info. |
26 | |
49 | |
27 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
50 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
28 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
51 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
29 | nowadays. So what is different about AnyEvent? |
52 | nowadays. So what is different about AnyEvent? |
30 | |
53 | |
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123 | These watchers are normal Perl objects with normal Perl lifetime. After |
146 | These watchers are normal Perl objects with normal Perl lifetime. After |
124 | creating a watcher it will immediately "watch" for events and invoke the |
147 | creating a watcher it will immediately "watch" for events and invoke the |
125 | callback when the event occurs (of course, only when the event model is |
148 | callback when the event occurs (of course, only when the event model is |
126 | in control). |
149 | in control). |
127 | |
150 | |
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151 | Note that callbacks must not permanently change global variables |
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152 | potentially in use by the event loop (such as $_ or $[) and that |
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153 | callbacks must not "die". The former is good programming practise in |
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154 | Perl and the latter stems from the fact that exception handling differs |
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155 | widely between event loops. |
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156 | |
128 | To disable the watcher you have to destroy it (e.g. by setting the |
157 | To disable the watcher you have to destroy it (e.g. by setting the |
129 | variable you store it in to "undef" or otherwise deleting all references |
158 | variable you store it in to "undef" or otherwise deleting all references |
130 | to it). |
159 | to it). |
131 | |
160 | |
132 | All watchers are created by calling a method on the "AnyEvent" class. |
161 | All watchers are created by calling a method on the "AnyEvent" class. |
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144 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
173 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
145 | my variables are only visible after the statement in which they are |
174 | my variables are only visible after the statement in which they are |
146 | declared. |
175 | declared. |
147 | |
176 | |
148 | I/O WATCHERS |
177 | I/O WATCHERS |
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178 | $w = AnyEvent->io ( |
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179 | fh => <filehandle_or_fileno>, |
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180 | poll => <"r" or "w">, |
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181 | cb => <callback>, |
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182 | ); |
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183 | |
149 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
184 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
150 | the following mandatory key-value pairs as arguments: |
185 | the following mandatory key-value pairs as arguments: |
151 | |
186 | |
152 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events |
187 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
153 | (AnyEvent might or might not keep a reference to this file handle). |
188 | events (AnyEvent might or might not keep a reference to this file |
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189 | handle). Note that only file handles pointing to things for which |
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190 | non-blocking operation makes sense are allowed. This includes sockets, |
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191 | most character devices, pipes, fifos and so on, but not for example |
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192 | files or block devices. |
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193 | |
154 | "poll" must be a string that is either "r" or "w", which creates a |
194 | "poll" must be a string that is either "r" or "w", which creates a |
155 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
195 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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196 | |
156 | is the callback to invoke each time the file handle becomes ready. |
197 | "cb" is the callback to invoke each time the file handle becomes ready. |
157 | |
198 | |
158 | Although the callback might get passed parameters, their value and |
199 | Although the callback might get passed parameters, their value and |
159 | presence is undefined and you cannot rely on them. Portable AnyEvent |
200 | presence is undefined and you cannot rely on them. Portable AnyEvent |
160 | callbacks cannot use arguments passed to I/O watcher callbacks. |
201 | callbacks cannot use arguments passed to I/O watcher callbacks. |
161 | |
202 | |
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175 | warn "read: $input\n"; |
216 | warn "read: $input\n"; |
176 | undef $w; |
217 | undef $w; |
177 | }); |
218 | }); |
178 | |
219 | |
179 | TIME WATCHERS |
220 | TIME WATCHERS |
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221 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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222 | |
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223 | $w = AnyEvent->timer ( |
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224 | after => <fractional_seconds>, |
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225 | interval => <fractional_seconds>, |
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226 | cb => <callback>, |
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227 | ); |
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228 | |
180 | You can create a time watcher by calling the "AnyEvent->timer" method |
229 | You can create a time watcher by calling the "AnyEvent->timer" method |
181 | with the following mandatory arguments: |
230 | with the following mandatory arguments: |
182 | |
231 | |
183 | "after" specifies after how many seconds (fractional values are |
232 | "after" specifies after how many seconds (fractional values are |
184 | supported) the callback should be invoked. "cb" is the callback to |
233 | supported) the callback should be invoked. "cb" is the callback to |
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293 | In either case, if you care (and in most cases, you don't), then you |
342 | 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 |
343 | can get whatever behaviour you want with any event loop, by taking |
295 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
344 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
296 | account. |
345 | account. |
297 | |
346 | |
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347 | AnyEvent->now_update |
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348 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
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349 | current time for each loop iteration (see the discussion of |
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350 | AnyEvent->now, above). |
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351 | |
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352 | When a callback runs for a long time (or when the process sleeps), |
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353 | then this "current" time will differ substantially from the real |
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354 | time, which might affect timers and time-outs. |
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355 | |
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356 | When this is the case, you can call this method, which will update |
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357 | the event loop's idea of "current time". |
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358 | |
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359 | Note that updating the time *might* cause some events to be handled. |
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360 | |
298 | SIGNAL WATCHERS |
361 | SIGNAL WATCHERS |
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362 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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363 | |
299 | You can watch for signals using a signal watcher, "signal" is the signal |
364 | You can watch for signals using a signal watcher, "signal" is the signal |
300 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
365 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
301 | callback to be invoked whenever a signal occurs. |
366 | callback to be invoked whenever a signal occurs. |
302 | |
367 | |
303 | Although the callback might get passed parameters, their value and |
368 | Although the callback might get passed parameters, their value and |
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308 | invocation, and callback invocation will be synchronous. Synchronous |
373 | invocation, and callback invocation will be synchronous. Synchronous |
309 | means that it might take a while until the signal gets handled by the |
374 | means that it might take a while until the signal gets handled by the |
310 | process, but it is guaranteed not to interrupt any other callbacks. |
375 | process, but it is guaranteed not to interrupt any other callbacks. |
311 | |
376 | |
312 | The main advantage of using these watchers is that you can share a |
377 | The main advantage of using these watchers is that you can share a |
313 | signal between multiple watchers. |
378 | signal between multiple watchers, and AnyEvent will ensure that signals |
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379 | will not interrupt your program at bad times. |
314 | |
380 | |
315 | This watcher might use %SIG, so programs overwriting those signals |
381 | This watcher might use %SIG (depending on the event loop used), so |
316 | directly will likely not work correctly. |
382 | programs overwriting those signals directly will likely not work |
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383 | correctly. |
317 | |
384 | |
318 | Example: exit on SIGINT |
385 | Example: exit on SIGINT |
319 | |
386 | |
320 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
387 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
321 | |
388 | |
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389 | Signal Races, Delays and Workarounds |
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390 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
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391 | callbacks to signals in a generic way, which is a pity, as you cannot do |
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392 | race-free signal handling in perl, requiring C libraries for this. |
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393 | AnyEvent will try to do it's best, which means in some cases, signals |
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394 | will be delayed. The maximum time a signal might be delayed is specified |
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395 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
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396 | can be changed only before the first signal watcher is created, and |
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397 | should be left alone otherwise. This variable determines how often |
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398 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
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399 | will cause fewer spurious wake-ups, which is better for power and CPU |
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400 | saving. |
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401 | |
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402 | All these problems can be avoided by installing the optional |
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403 | Async::Interrupt module, which works with most event loops. It will not |
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404 | work with inherently broken event loops such as Event or Event::Lib (and |
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405 | not with POE currently, as POE does it's own workaround with one-second |
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406 | latency). For those, you just have to suffer the delays. |
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407 | |
322 | CHILD PROCESS WATCHERS |
408 | CHILD PROCESS WATCHERS |
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409 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
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410 | |
323 | You can also watch on a child process exit and catch its exit status. |
411 | You can also watch on a child process exit and catch its exit status. |
324 | |
412 | |
325 | The child process is specified by the "pid" argument (if set to 0, it |
413 | The child process is specified by the "pid" argument (one some backends, |
326 | watches for any child process exit). The watcher will trigger as often |
414 | using 0 watches for any child process exit, on others this will croak). |
327 | as status change for the child are received. This works by installing a |
415 | The watcher will be triggered only when the child process has finished |
328 | signal handler for "SIGCHLD". The callback will be called with the pid |
416 | and an exit status is available, not on any trace events |
329 | and exit status (as returned by waitpid), so unlike other watcher types, |
417 | (stopped/continued). |
330 | you *can* rely on child watcher callback arguments. |
418 | |
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419 | The callback will be called with the pid and exit status (as returned by |
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420 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
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421 | callback arguments. |
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422 | |
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423 | This watcher type works by installing a signal handler for "SIGCHLD", |
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424 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
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425 | random child processes (waiting for specific child processes, e.g. |
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426 | inside "system", is just fine). |
331 | |
427 | |
332 | There is a slight catch to child watchers, however: you usually start |
428 | 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 |
429 | them *after* the child process was created, and this means the process |
334 | could have exited already (and no SIGCHLD will be sent anymore). |
430 | could have exited already (and no SIGCHLD will be sent anymore). |
335 | |
431 | |
336 | Not all event models handle this correctly (POE doesn't), but even for |
432 | Not all event models handle this correctly (neither POE nor IO::Async |
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433 | do, see their AnyEvent::Impl manpages for details), but even for event |
337 | event models that *do* handle this correctly, they usually need to be |
434 | models that *do* handle this correctly, they usually need to be loaded |
338 | loaded before the process exits (i.e. before you fork in the first |
435 | before the process exits (i.e. before you fork in the first place). |
339 | place). |
436 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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437 | of when you start the watcher. |
340 | |
438 | |
341 | This means you cannot create a child watcher as the very first thing in |
439 | This means you cannot create a child watcher as the very first thing in |
342 | an AnyEvent program, you *have* to create at least one watcher before |
440 | an AnyEvent program, you *have* to create at least one watcher before |
343 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
441 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
344 | |
442 | |
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443 | As most event loops do not support waiting for child events, they will |
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444 | be emulated by AnyEvent in most cases, in which the latency and race |
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445 | problems mentioned in the description of signal watchers apply. |
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446 | |
345 | Example: fork a process and wait for it |
447 | Example: fork a process and wait for it |
346 | |
448 | |
347 | my $done = AnyEvent->condvar; |
449 | my $done = AnyEvent->condvar; |
348 | |
450 | |
349 | my $pid = fork or exit 5; |
451 | my $pid = fork or exit 5; |
350 | |
452 | |
351 | my $w = AnyEvent->child ( |
453 | my $w = AnyEvent->child ( |
352 | pid => $pid, |
454 | pid => $pid, |
353 | cb => sub { |
455 | cb => sub { |
354 | my ($pid, $status) = @_; |
456 | my ($pid, $status) = @_; |
355 | warn "pid $pid exited with status $status"; |
457 | warn "pid $pid exited with status $status"; |
356 | $done->send; |
458 | $done->send; |
357 | }, |
459 | }, |
358 | ); |
460 | ); |
359 | |
461 | |
360 | # do something else, then wait for process exit |
462 | # do something else, then wait for process exit |
361 | $done->recv; |
463 | $done->recv; |
362 | |
464 | |
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465 | IDLE WATCHERS |
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466 | $w = AnyEvent->idle (cb => <callback>); |
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467 | |
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468 | Sometimes there is a need to do something, but it is not so important to |
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469 | do it instantly, but only when there is nothing better to do. This |
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470 | "nothing better to do" is usually defined to be "no other events need |
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471 | attention by the event loop". |
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472 | |
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473 | Idle watchers ideally get invoked when the event loop has nothing better |
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474 | to do, just before it would block the process to wait for new events. |
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475 | Instead of blocking, the idle watcher is invoked. |
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476 | |
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477 | Most event loops unfortunately do not really support idle watchers (only |
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478 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
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479 | will simply call the callback "from time to time". |
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480 | |
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481 | Example: read lines from STDIN, but only process them when the program |
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482 | is otherwise idle: |
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483 | |
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484 | my @lines; # read data |
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485 | my $idle_w; |
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486 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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487 | push @lines, scalar <STDIN>; |
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488 | |
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489 | # start an idle watcher, if not already done |
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490 | $idle_w ||= AnyEvent->idle (cb => sub { |
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491 | # handle only one line, when there are lines left |
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492 | if (my $line = shift @lines) { |
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493 | print "handled when idle: $line"; |
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494 | } else { |
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495 | # otherwise disable the idle watcher again |
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496 | undef $idle_w; |
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497 | } |
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498 | }); |
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499 | }); |
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500 | |
363 | CONDITION VARIABLES |
501 | CONDITION VARIABLES |
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502 | $cv = AnyEvent->condvar; |
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503 | |
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504 | $cv->send (<list>); |
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505 | my @res = $cv->recv; |
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506 | |
364 | If you are familiar with some event loops you will know that all of them |
507 | If you are familiar with some event loops you will know that all of them |
365 | require you to run some blocking "loop", "run" or similar function that |
508 | require you to run some blocking "loop", "run" or similar function that |
366 | will actively watch for new events and call your callbacks. |
509 | will actively watch for new events and call your callbacks. |
367 | |
510 | |
368 | AnyEvent is different, it expects somebody else to run the event loop |
511 | AnyEvent is slightly different: it expects somebody else to run the |
369 | and will only block when necessary (usually when told by the user). |
512 | event loop and will only block when necessary (usually when told by the |
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513 | user). |
370 | |
514 | |
371 | The instrument to do that is called a "condition variable", so called |
515 | The instrument to do that is called a "condition variable", so called |
372 | because they represent a condition that must become true. |
516 | because they represent a condition that must become true. |
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517 | |
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518 | Now is probably a good time to look at the examples further below. |
373 | |
519 | |
374 | Condition variables can be created by calling the "AnyEvent->condvar" |
520 | Condition variables can be created by calling the "AnyEvent->condvar" |
375 | method, usually without arguments. The only argument pair allowed is |
521 | method, usually without arguments. The only argument pair allowed is |
376 | "cb", which specifies a callback to be called when the condition |
522 | "cb", which specifies a callback to be called when the condition |
377 | variable becomes true. |
523 | variable becomes true, with the condition variable as the first argument |
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524 | (but not the results). |
378 | |
525 | |
379 | After creation, the condition variable is "false" until it becomes |
526 | After creation, the condition variable is "false" until it becomes |
380 | "true" by calling the "send" method (or calling the condition variable |
527 | "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 |
528 | as if it were a callback, read about the caveats in the description for |
382 | the "->send" method). |
529 | the "->send" method). |
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384 | Condition variables are similar to callbacks, except that you can |
531 | Condition variables are similar to callbacks, except that you can |
385 | optionally wait for them. They can also be called merge points - points |
532 | optionally wait for them. They can also be called merge points - points |
386 | in time where multiple outstanding events have been processed. And yet |
533 | in time where multiple outstanding events have been processed. And yet |
387 | another way to call them is transactions - each condition variable can |
534 | another way to call them is transactions - each condition variable can |
388 | be used to represent a transaction, which finishes at some point and |
535 | be used to represent a transaction, which finishes at some point and |
389 | delivers a result. |
536 | delivers a result. And yet some people know them as "futures" - a |
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537 | promise to compute/deliver something that you can wait for. |
390 | |
538 | |
391 | Condition variables are very useful to signal that something has |
539 | Condition variables are very useful to signal that something has |
392 | finished, for example, if you write a module that does asynchronous http |
540 | finished, for example, if you write a module that does asynchronous http |
393 | requests, then a condition variable would be the ideal candidate to |
541 | requests, then a condition variable would be the ideal candidate to |
394 | signal the availability of results. The user can either act when the |
542 | signal the availability of results. The user can either act when the |
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428 | after => 1, |
576 | after => 1, |
429 | cb => sub { $result_ready->send }, |
577 | cb => sub { $result_ready->send }, |
430 | ); |
578 | ); |
431 | |
579 | |
432 | # this "blocks" (while handling events) till the callback |
580 | # this "blocks" (while handling events) till the callback |
433 | # calls send |
581 | # calls -<send |
434 | $result_ready->recv; |
582 | $result_ready->recv; |
435 | |
583 | |
436 | Example: wait for a timer, but take advantage of the fact that condition |
584 | Example: wait for a timer, but take advantage of the fact that condition |
437 | variables are also code references. |
585 | variables are also callable directly. |
438 | |
586 | |
439 | my $done = AnyEvent->condvar; |
587 | my $done = AnyEvent->condvar; |
440 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
588 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
441 | $done->recv; |
589 | $done->recv; |
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590 | |
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591 | Example: Imagine an API that returns a condvar and doesn't support |
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592 | callbacks. This is how you make a synchronous call, for example from the |
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593 | main program: |
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594 | |
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595 | use AnyEvent::CouchDB; |
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596 | |
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597 | ... |
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598 | |
|
|
599 | my @info = $couchdb->info->recv; |
|
|
600 | |
|
|
601 | And this is how you would just set a callback to be called whenever the |
|
|
602 | results are available: |
|
|
603 | |
|
|
604 | $couchdb->info->cb (sub { |
|
|
605 | my @info = $_[0]->recv; |
|
|
606 | }); |
442 | |
607 | |
443 | METHODS FOR PRODUCERS |
608 | METHODS FOR PRODUCERS |
444 | These methods should only be used by the producing side, i.e. the |
609 | 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 |
610 | 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 |
611 | producer side which creates the condvar in most cases, but it isn't |
… | |
… | |
456 | |
621 | |
457 | Any arguments passed to the "send" call will be returned by all |
622 | Any arguments passed to the "send" call will be returned by all |
458 | future "->recv" calls. |
623 | future "->recv" calls. |
459 | |
624 | |
460 | Condition variables are overloaded so one can call them directly (as |
625 | Condition variables are overloaded so one can call them directly (as |
461 | a code reference). Calling them directly is the same as calling |
626 | if they were a code reference). Calling them directly is the same as |
462 | "send". Note, however, that many C-based event loops do not handle |
627 | calling "send". |
463 | overloading, so as tempting as it may be, passing a condition |
|
|
464 | variable instead of a callback does not work. Both the pure perl and |
|
|
465 | EV loops support overloading, however, as well as all functions that |
|
|
466 | use perl to invoke a callback (as in AnyEvent::Socket and |
|
|
467 | AnyEvent::DNS for example). |
|
|
468 | |
628 | |
469 | $cv->croak ($error) |
629 | $cv->croak ($error) |
470 | Similar to send, but causes all call's to "->recv" to invoke |
630 | Similar to send, but causes all call's to "->recv" to invoke |
471 | "Carp::croak" with the given error message/object/scalar. |
631 | "Carp::croak" with the given error message/object/scalar. |
472 | |
632 | |
473 | This can be used to signal any errors to the condition variable |
633 | This can be used to signal any errors to the condition variable |
474 | user/consumer. |
634 | user/consumer. Doing it this way instead of calling "croak" directly |
|
|
635 | delays the error detetcion, but has the overwhelmign advantage that |
|
|
636 | it diagnoses the error at the place where the result is expected, |
|
|
637 | and not deep in some event clalback without connection to the actual |
|
|
638 | code causing the problem. |
475 | |
639 | |
476 | $cv->begin ([group callback]) |
640 | $cv->begin ([group callback]) |
477 | $cv->end |
641 | $cv->end |
478 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
479 | |
|
|
480 | These two methods can be used to combine many transactions/events |
642 | These two methods can be used to combine many transactions/events |
481 | into one. For example, a function that pings many hosts in parallel |
643 | into one. For example, a function that pings many hosts in parallel |
482 | might want to use a condition variable for the whole process. |
644 | might want to use a condition variable for the whole process. |
483 | |
645 | |
484 | Every call to "->begin" will increment a counter, and every call to |
646 | Every call to "->begin" will increment a counter, and every call to |
485 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
647 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
486 | (last) callback passed to "begin" will be executed. That callback is |
648 | (last) callback passed to "begin" will be executed. That callback is |
487 | *supposed* to call "->send", but that is not required. If no |
649 | *supposed* to call "->send", but that is not required. If no |
488 | callback was set, "send" will be called without any arguments. |
650 | callback was set, "send" will be called without any arguments. |
489 | |
651 | |
490 | Let's clarify this with the ping example: |
652 | You can think of "$cv->send" giving you an OR condition (one call |
|
|
653 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
|
|
654 | condition (all "begin" calls must be "end"'ed before the condvar |
|
|
655 | sends). |
|
|
656 | |
|
|
657 | Let's start with a simple example: you have two I/O watchers (for |
|
|
658 | example, STDOUT and STDERR for a program), and you want to wait for |
|
|
659 | both streams to close before activating a condvar: |
|
|
660 | |
|
|
661 | my $cv = AnyEvent->condvar; |
|
|
662 | |
|
|
663 | $cv->begin; # first watcher |
|
|
664 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
|
|
665 | defined sysread $fh1, my $buf, 4096 |
|
|
666 | or $cv->end; |
|
|
667 | }); |
|
|
668 | |
|
|
669 | $cv->begin; # second watcher |
|
|
670 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
|
|
671 | defined sysread $fh2, my $buf, 4096 |
|
|
672 | or $cv->end; |
|
|
673 | }); |
|
|
674 | |
|
|
675 | $cv->recv; |
|
|
676 | |
|
|
677 | This works because for every event source (EOF on file handle), |
|
|
678 | there is one call to "begin", so the condvar waits for all calls to |
|
|
679 | "end" before sending. |
|
|
680 | |
|
|
681 | The ping example mentioned above is slightly more complicated, as |
|
|
682 | the there are results to be passwd back, and the number of tasks |
|
|
683 | that are begung can potentially be zero: |
491 | |
684 | |
492 | my $cv = AnyEvent->condvar; |
685 | my $cv = AnyEvent->condvar; |
493 | |
686 | |
494 | my %result; |
687 | my %result; |
495 | $cv->begin (sub { $cv->send (\%result) }); |
688 | $cv->begin (sub { $cv->send (\%result) }); |
… | |
… | |
515 | the loop, which serves two important purposes: first, it sets the |
708 | the loop, which serves two important purposes: first, it sets the |
516 | callback to be called once the counter reaches 0, and second, it |
709 | callback to be called once the counter reaches 0, and second, it |
517 | ensures that "send" is called even when "no" hosts are being pinged |
710 | ensures that "send" is called even when "no" hosts are being pinged |
518 | (the loop doesn't execute once). |
711 | (the loop doesn't execute once). |
519 | |
712 | |
520 | This is the general pattern when you "fan out" into multiple |
713 | This is the general pattern when you "fan out" into multiple (but |
521 | subrequests: use an outer "begin"/"end" pair to set the callback and |
714 | potentially none) subrequests: use an outer "begin"/"end" pair to |
522 | ensure "end" is called at least once, and then, for each subrequest |
715 | set the callback and ensure "end" is called at least once, and then, |
523 | you start, call "begin" and for each subrequest you finish, call |
716 | for each subrequest you start, call "begin" and for each subrequest |
524 | "end". |
717 | you finish, call "end". |
525 | |
718 | |
526 | METHODS FOR CONSUMERS |
719 | METHODS FOR CONSUMERS |
527 | These methods should only be used by the consuming side, i.e. the code |
720 | These methods should only be used by the consuming side, i.e. the code |
528 | awaits the condition. |
721 | awaits the condition. |
529 | |
722 | |
… | |
… | |
538 | function will call "croak". |
731 | function will call "croak". |
539 | |
732 | |
540 | In list context, all parameters passed to "send" will be returned, |
733 | In list context, all parameters passed to "send" will be returned, |
541 | in scalar context only the first one will be returned. |
734 | in scalar context only the first one will be returned. |
542 | |
735 | |
|
|
736 | Note that doing a blocking wait in a callback is not supported by |
|
|
737 | any event loop, that is, recursive invocation of a blocking "->recv" |
|
|
738 | is not allowed, and the "recv" call will "croak" if such a condition |
|
|
739 | is detected. This condition can be slightly loosened by using |
|
|
740 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
|
|
741 | thread that doesn't run the event loop itself. |
|
|
742 | |
543 | Not all event models support a blocking wait - some die in that case |
743 | Not all event models support a blocking wait - some die in that case |
544 | (programs might want to do that to stay interactive), so *if you are |
744 | (programs might want to do that to stay interactive), so *if you are |
545 | using this from a module, never require a blocking wait*, but let |
745 | using this from a module, never require a blocking wait*. Instead, |
546 | the caller decide whether the call will block or not (for example, |
746 | let the caller decide whether the call will block or not (for |
547 | by coupling condition variables with some kind of request results |
747 | example, by coupling condition variables with some kind of request |
548 | and supporting callbacks so the caller knows that getting the result |
748 | results and supporting callbacks so the caller knows that getting |
549 | will not block, while still supporting blocking waits if the caller |
749 | the result will not block, while still supporting blocking waits if |
550 | so desires). |
750 | the caller so desires). |
551 | |
|
|
552 | Another reason *never* to "->recv" in a module is that you cannot |
|
|
553 | sensibly have two "->recv"'s in parallel, as that would require |
|
|
554 | multiple interpreters or coroutines/threads, none of which |
|
|
555 | "AnyEvent" can supply. |
|
|
556 | |
|
|
557 | The Coro module, however, *can* and *does* supply coroutines and, in |
|
|
558 | fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe |
|
|
559 | versions and also integrates coroutines into AnyEvent, making |
|
|
560 | blocking "->recv" calls perfectly safe as long as they are done from |
|
|
561 | another coroutine (one that doesn't run the event loop). |
|
|
562 | |
751 | |
563 | You can ensure that "-recv" never blocks by setting a callback and |
752 | You can ensure that "-recv" never blocks by setting a callback and |
564 | only calling "->recv" from within that callback (or at a later |
753 | only calling "->recv" from within that callback (or at a later |
565 | time). This will work even when the event loop does not support |
754 | time). This will work even when the event loop does not support |
566 | blocking waits otherwise. |
755 | blocking waits otherwise. |
567 | |
756 | |
568 | $bool = $cv->ready |
757 | $bool = $cv->ready |
569 | Returns true when the condition is "true", i.e. whether "send" or |
758 | Returns true when the condition is "true", i.e. whether "send" or |
570 | "croak" have been called. |
759 | "croak" have been called. |
571 | |
760 | |
572 | $cb = $cv->cb ([new callback]) |
761 | $cb = $cv->cb ($cb->($cv)) |
573 | This is a mutator function that returns the callback set and |
762 | This is a mutator function that returns the callback set and |
574 | optionally replaces it before doing so. |
763 | optionally replaces it before doing so. |
575 | |
764 | |
576 | The callback will be called when the condition becomes "true", i.e. |
765 | The callback will be called when the condition becomes (or already |
577 | when "send" or "croak" are called, with the only argument being the |
766 | was) "true", i.e. when "send" or "croak" are called (or were |
578 | condition variable itself. Calling "recv" inside the callback or at |
767 | called), with the only argument being the condition variable itself. |
|
|
768 | Calling "recv" inside the callback or at any later time is |
579 | any later time is guaranteed not to block. |
769 | guaranteed not to block. |
|
|
770 | |
|
|
771 | SUPPORTED EVENT LOOPS/BACKENDS |
|
|
772 | The available backend classes are (every class has its own manpage): |
|
|
773 | |
|
|
774 | Backends that are autoprobed when no other event loop can be found. |
|
|
775 | EV is the preferred backend when no other event loop seems to be in |
|
|
776 | use. If EV is not installed, then AnyEvent will try Event, and, |
|
|
777 | failing that, will fall back to its own pure-perl implementation, |
|
|
778 | which is available everywhere as it comes with AnyEvent itself. |
|
|
779 | |
|
|
780 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
781 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
782 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
783 | |
|
|
784 | Backends that are transparently being picked up when they are used. |
|
|
785 | These will be used when they are currently loaded when the first |
|
|
786 | watcher is created, in which case it is assumed that the application |
|
|
787 | is using them. This means that AnyEvent will automatically pick the |
|
|
788 | right backend when the main program loads an event module before |
|
|
789 | anything starts to create watchers. Nothing special needs to be done |
|
|
790 | by the main program. |
|
|
791 | |
|
|
792 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
793 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
794 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
795 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
796 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
797 | |
|
|
798 | Backends with special needs. |
|
|
799 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
800 | otherwise be picked up automatically. As long as the main program |
|
|
801 | instantiates the application before any AnyEvent watchers are |
|
|
802 | created, everything should just work. |
|
|
803 | |
|
|
804 | AnyEvent::Impl::Qt based on Qt. |
|
|
805 | |
|
|
806 | Support for IO::Async can only be partial, as it is too broken and |
|
|
807 | architecturally limited to even support the AnyEvent API. It also is |
|
|
808 | the only event loop that needs the loop to be set explicitly, so it |
|
|
809 | can only be used by a main program knowing about AnyEvent. See |
|
|
810 | AnyEvent::Impl::Async for the gory details. |
|
|
811 | |
|
|
812 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
813 | |
|
|
814 | Event loops that are indirectly supported via other backends. |
|
|
815 | Some event loops can be supported via other modules: |
|
|
816 | |
|
|
817 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
818 | |
|
|
819 | WxWidgets has no support for watching file handles. However, you can |
|
|
820 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
821 | simply polls 20 times per second, which was considered to be too |
|
|
822 | horrible to even consider for AnyEvent. |
|
|
823 | |
|
|
824 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
825 | POE backend, so it can be supported through POE. |
|
|
826 | |
|
|
827 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
828 | load POE when detecting them, in the hope that POE will pick them |
|
|
829 | up, in which case everything will be automatic. |
580 | |
830 | |
581 | GLOBAL VARIABLES AND FUNCTIONS |
831 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
832 | These are not normally required to use AnyEvent, but can be useful to |
|
|
833 | write AnyEvent extension modules. |
|
|
834 | |
582 | $AnyEvent::MODEL |
835 | $AnyEvent::MODEL |
583 | Contains "undef" until the first watcher is being created. Then it |
836 | Contains "undef" until the first watcher is being created, before |
|
|
837 | the backend has been autodetected. |
|
|
838 | |
584 | contains the event model that is being used, which is the name of |
839 | Afterwards it contains the event model that is being used, which is |
585 | the Perl class implementing the model. This class is usually one of |
840 | the name of the Perl class implementing the model. This class is |
586 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
841 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
587 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
842 | other class in the case AnyEvent has been extended at runtime (e.g. |
588 | |
843 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
589 | The known classes so far are: |
|
|
590 | |
|
|
591 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
592 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
593 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
594 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
595 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
596 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
597 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
598 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
599 | |
|
|
600 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
601 | watching file handles. However, you can use WxWidgets through the |
|
|
602 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
603 | second, which was considered to be too horrible to even consider for |
|
|
604 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
|
|
605 | using it's adaptor. |
|
|
606 | |
|
|
607 | AnyEvent knows about Prima and Wx and will try to use POE when |
|
|
608 | autodetecting them. |
|
|
609 | |
844 | |
610 | AnyEvent::detect |
845 | AnyEvent::detect |
611 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
846 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
612 | if necessary. You should only call this function right before you |
847 | if necessary. You should only call this function right before you |
613 | would have created an AnyEvent watcher anyway, that is, as late as |
848 | would have created an AnyEvent watcher anyway, that is, as late as |
614 | possible at runtime. |
849 | possible at runtime, and not e.g. while initialising of your module. |
|
|
850 | |
|
|
851 | If you need to do some initialisation before AnyEvent watchers are |
|
|
852 | created, use "post_detect". |
615 | |
853 | |
616 | $guard = AnyEvent::post_detect { BLOCK } |
854 | $guard = AnyEvent::post_detect { BLOCK } |
617 | Arranges for the code block to be executed as soon as the event |
855 | Arranges for the code block to be executed as soon as the event |
618 | model is autodetected (or immediately if this has already happened). |
856 | model is autodetected (or immediately if this has already happened). |
619 | |
857 | |
|
|
858 | The block will be executed *after* the actual backend has been |
|
|
859 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
860 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
861 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
862 | AnyEvent::AIO to see how this is used. |
|
|
863 | |
|
|
864 | The most common usage is to create some global watchers, without |
|
|
865 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
866 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
867 | block to avoid autodetecting the event module at load time. |
|
|
868 | |
620 | If called in scalar or list context, then it creates and returns an |
869 | If called in scalar or list context, then it creates and returns an |
621 | object that automatically removes the callback again when it is |
870 | object that automatically removes the callback again when it is |
|
|
871 | destroyed (or "undef" when the hook was immediately executed). See |
622 | destroyed. See Coro::BDB for a case where this is useful. |
872 | AnyEvent::AIO for a case where this is useful. |
|
|
873 | |
|
|
874 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
875 | $WATCHER. Only do so after the event loop is initialised, though. |
|
|
876 | |
|
|
877 | our WATCHER; |
|
|
878 | |
|
|
879 | my $guard = AnyEvent::post_detect { |
|
|
880 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
881 | }; |
|
|
882 | |
|
|
883 | # the ||= is important in case post_detect immediately runs the block, |
|
|
884 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
885 | # post_detect guard to the same variable has the advantage of users being |
|
|
886 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
887 | |
|
|
888 | $WATCHER ||= $guard; |
623 | |
889 | |
624 | @AnyEvent::post_detect |
890 | @AnyEvent::post_detect |
625 | If there are any code references in this array (you can "push" to it |
891 | If there are any code references in this array (you can "push" to it |
626 | before or after loading AnyEvent), then they will called directly |
892 | before or after loading AnyEvent), then they will called directly |
627 | after the event loop has been chosen. |
893 | after the event loop has been chosen. |
628 | |
894 | |
629 | You should check $AnyEvent::MODEL before adding to this array, |
895 | You should check $AnyEvent::MODEL before adding to this array, |
630 | though: if it contains a true value then the event loop has already |
896 | though: if it is defined then the event loop has already been |
631 | been detected, and the array will be ignored. |
897 | detected, and the array will be ignored. |
632 | |
898 | |
633 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
899 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
900 | allows it,as it takes care of these details. |
|
|
901 | |
|
|
902 | This variable is mainly useful for modules that can do something |
|
|
903 | useful when AnyEvent is used and thus want to know when it is |
|
|
904 | initialised, but do not need to even load it by default. This array |
|
|
905 | provides the means to hook into AnyEvent passively, without loading |
|
|
906 | it. |
634 | |
907 | |
635 | WHAT TO DO IN A MODULE |
908 | WHAT TO DO IN A MODULE |
636 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
909 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
637 | freely, but you should not load a specific event module or rely on it. |
910 | freely, but you should not load a specific event module or rely on it. |
638 | |
911 | |
… | |
… | |
689 | variable somewhere, waiting for it, and sending it when the program |
962 | variable somewhere, waiting for it, and sending it when the program |
690 | should exit cleanly. |
963 | should exit cleanly. |
691 | |
964 | |
692 | OTHER MODULES |
965 | OTHER MODULES |
693 | The following is a non-exhaustive list of additional modules that use |
966 | The following is a non-exhaustive list of additional modules that use |
694 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
967 | AnyEvent as a client and can therefore be mixed easily with other |
695 | in the same program. Some of the modules come with AnyEvent, some are |
968 | AnyEvent modules and other event loops in the same program. Some of the |
696 | available via CPAN. |
969 | modules come with AnyEvent, most are available via CPAN. |
697 | |
970 | |
698 | AnyEvent::Util |
971 | AnyEvent::Util |
699 | Contains various utility functions that replace often-used but |
972 | Contains various utility functions that replace often-used but |
700 | blocking functions such as "inet_aton" by event-/callback-based |
973 | blocking functions such as "inet_aton" by event-/callback-based |
701 | versions. |
974 | versions. |
… | |
… | |
707 | more. |
980 | more. |
708 | |
981 | |
709 | AnyEvent::Handle |
982 | AnyEvent::Handle |
710 | Provide read and write buffers, manages watchers for reads and |
983 | Provide read and write buffers, manages watchers for reads and |
711 | writes, supports raw and formatted I/O, I/O queued and fully |
984 | writes, supports raw and formatted I/O, I/O queued and fully |
712 | transparent and non-blocking SSL/TLS. |
985 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
713 | |
986 | |
714 | AnyEvent::DNS |
987 | AnyEvent::DNS |
715 | Provides rich asynchronous DNS resolver capabilities. |
988 | Provides rich asynchronous DNS resolver capabilities. |
716 | |
989 | |
717 | AnyEvent::HTTP |
990 | AnyEvent::HTTP |
… | |
… | |
738 | |
1011 | |
739 | AnyEvent::GPSD |
1012 | AnyEvent::GPSD |
740 | A non-blocking interface to gpsd, a daemon delivering GPS |
1013 | A non-blocking interface to gpsd, a daemon delivering GPS |
741 | information. |
1014 | information. |
742 | |
1015 | |
|
|
1016 | AnyEvent::IRC |
|
|
1017 | AnyEvent based IRC client module family (replacing the older |
|
|
1018 | Net::IRC3). |
|
|
1019 | |
|
|
1020 | AnyEvent::XMPP |
|
|
1021 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
1022 | older Net::XMPP2>. |
|
|
1023 | |
743 | AnyEvent::IGS |
1024 | AnyEvent::IGS |
744 | A non-blocking interface to the Internet Go Server protocol (used by |
1025 | A non-blocking interface to the Internet Go Server protocol (used by |
745 | App::IGS). |
1026 | App::IGS). |
746 | |
1027 | |
747 | Net::IRC3 |
|
|
748 | AnyEvent based IRC client module family. |
|
|
749 | |
|
|
750 | Net::XMPP2 |
|
|
751 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
752 | |
|
|
753 | Net::FCP |
1028 | Net::FCP |
754 | AnyEvent-based implementation of the Freenet Client Protocol, |
1029 | AnyEvent-based implementation of the Freenet Client Protocol, |
755 | birthplace of AnyEvent. |
1030 | birthplace of AnyEvent. |
756 | |
1031 | |
757 | Event::ExecFlow |
1032 | Event::ExecFlow |
758 | High level API for event-based execution flow control. |
1033 | High level API for event-based execution flow control. |
759 | |
1034 | |
760 | Coro |
1035 | Coro |
761 | Has special support for AnyEvent via Coro::AnyEvent. |
1036 | Has special support for AnyEvent via Coro::AnyEvent. |
762 | |
1037 | |
763 | IO::Lambda |
1038 | ERROR AND EXCEPTION HANDLING |
764 | The lambda approach to I/O - don't ask, look there. Can use |
1039 | In general, AnyEvent does not do any error handling - it relies on the |
765 | AnyEvent. |
1040 | caller to do that if required. The AnyEvent::Strict module (see also the |
|
|
1041 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
|
|
1042 | checking of all AnyEvent methods, however, which is highly useful during |
|
|
1043 | development. |
766 | |
1044 | |
767 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1045 | As for exception handling (i.e. runtime errors and exceptions thrown |
768 | This is an advanced topic that you do not normally need to use AnyEvent |
1046 | while executing a callback), this is not only highly event-loop |
769 | in a module. This section is only of use to event loop authors who want |
1047 | specific, but also not in any way wrapped by this module, as this is the |
770 | to provide AnyEvent compatibility. |
1048 | job of the main program. |
771 | |
1049 | |
772 | If you need to support another event library which isn't directly |
1050 | The pure perl event loop simply re-throws the exception (usually within |
773 | supported by AnyEvent, you can supply your own interface to it by |
1051 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
774 | pushing, before the first watcher gets created, the package name of the |
1052 | Glib uses "install_exception_handler" and so on. |
775 | event module and the package name of the interface to use onto |
|
|
776 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
777 | AnyEvent, so it is reasonably cheap. |
|
|
778 | |
|
|
779 | Example: |
|
|
780 | |
|
|
781 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
782 | |
|
|
783 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
784 | package/class when it finds the "urxvt" package/module is already |
|
|
785 | loaded. |
|
|
786 | |
|
|
787 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
788 | will first check for the presence of urxvt by trying to "use" the |
|
|
789 | "urxvt::anyevent" module. |
|
|
790 | |
|
|
791 | The class should provide implementations for all watcher types. See |
|
|
792 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
793 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
794 | the sources. |
|
|
795 | |
|
|
796 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
797 | provide suitable (hopefully) replacements. |
|
|
798 | |
|
|
799 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
800 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
801 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
802 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
803 | part of the *rxvt-unicode* distribution. |
|
|
804 | |
|
|
805 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
806 | condition variables: code blocking while waiting for a condition will |
|
|
807 | "die". This still works with most modules/usages, and blocking calls |
|
|
808 | must not be done in an interactive application, so it makes sense. |
|
|
809 | |
1053 | |
810 | ENVIRONMENT VARIABLES |
1054 | ENVIRONMENT VARIABLES |
811 | The following environment variables are used by this module: |
1055 | The following environment variables are used by this module or its |
|
|
1056 | submodules. |
|
|
1057 | |
|
|
1058 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1059 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1060 | enabled. |
812 | |
1061 | |
813 | "PERL_ANYEVENT_VERBOSE" |
1062 | "PERL_ANYEVENT_VERBOSE" |
814 | By default, AnyEvent will be completely silent except in fatal |
1063 | By default, AnyEvent will be completely silent except in fatal |
815 | conditions. You can set this environment variable to make AnyEvent |
1064 | conditions. You can set this environment variable to make AnyEvent |
816 | more talkative. |
1065 | more talkative. |
… | |
… | |
819 | conditions, such as not being able to load the event model specified |
1068 | conditions, such as not being able to load the event model specified |
820 | by "PERL_ANYEVENT_MODEL". |
1069 | by "PERL_ANYEVENT_MODEL". |
821 | |
1070 | |
822 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1071 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
823 | event model it chooses. |
1072 | event model it chooses. |
|
|
1073 | |
|
|
1074 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1075 | on which optional modules it loads and how it implements certain |
|
|
1076 | features. |
824 | |
1077 | |
825 | "PERL_ANYEVENT_STRICT" |
1078 | "PERL_ANYEVENT_STRICT" |
826 | AnyEvent does not do much argument checking by default, as thorough |
1079 | AnyEvent does not do much argument checking by default, as thorough |
827 | argument checking is very costly. Setting this variable to a true |
1080 | argument checking is very costly. Setting this variable to a true |
828 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1081 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
829 | thoroughly check the arguments passed to most method calls. If it |
1082 | thoroughly check the arguments passed to most method calls. If it |
830 | finds any problems it will croak. |
1083 | finds any problems, it will croak. |
831 | |
1084 | |
832 | In other words, enables "strict" mode. |
1085 | In other words, enables "strict" mode. |
833 | |
1086 | |
834 | Unlike "use strict" it is definitely recommended ot keep it off in |
1087 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
835 | production. |
1088 | is definitely recommended to keep it off in production. Keeping |
|
|
1089 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
|
|
1090 | programs can be very useful, however. |
836 | |
1091 | |
837 | "PERL_ANYEVENT_MODEL" |
1092 | "PERL_ANYEVENT_MODEL" |
838 | This can be used to specify the event model to be used by AnyEvent, |
1093 | This can be used to specify the event model to be used by AnyEvent, |
839 | before auto detection and -probing kicks in. It must be a string |
1094 | before auto detection and -probing kicks in. It must be a string |
840 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1095 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
859 | mentioned will be used, and preference will be given to protocols |
1114 | mentioned will be used, and preference will be given to protocols |
860 | mentioned earlier in the list. |
1115 | mentioned earlier in the list. |
861 | |
1116 | |
862 | This variable can effectively be used for denial-of-service attacks |
1117 | This variable can effectively be used for denial-of-service attacks |
863 | against local programs (e.g. when setuid), although the impact is |
1118 | against local programs (e.g. when setuid), although the impact is |
864 | likely small, as the program has to handle connection errors |
1119 | likely small, as the program has to handle conenction and other |
865 | already- |
1120 | failures anyways. |
866 | |
1121 | |
867 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1122 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
868 | IPv6, but support both and try to use both. |
1123 | IPv6, but support both and try to use both. |
869 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1124 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
870 | resolve or contact IPv6 addresses. |
1125 | resolve or contact IPv6 addresses. |
… | |
… | |
881 | EDNS0 in its DNS requests. |
1136 | EDNS0 in its DNS requests. |
882 | |
1137 | |
883 | "PERL_ANYEVENT_MAX_FORKS" |
1138 | "PERL_ANYEVENT_MAX_FORKS" |
884 | The maximum number of child processes that |
1139 | The maximum number of child processes that |
885 | "AnyEvent::Util::fork_call" will create in parallel. |
1140 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1141 | |
|
|
1142 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1143 | The default value for the "max_outstanding" parameter for the |
|
|
1144 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1145 | requests that are sent to the DNS server. |
|
|
1146 | |
|
|
1147 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1148 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1149 | configuration) in the default resolver. When set to the empty |
|
|
1150 | string, no default config will be used. |
|
|
1151 | |
|
|
1152 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1153 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1154 | AnyEvent::TLS context creation, and either of these environment |
|
|
1155 | variables exist, they will be used to specify CA certificate |
|
|
1156 | locations instead of a system-dependent default. |
|
|
1157 | |
|
|
1158 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1159 | When these are set to 1, then the respective modules are not loaded. |
|
|
1160 | Mostly good for testing AnyEvent itself. |
|
|
1161 | |
|
|
1162 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1163 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
1164 | in a module. This section is only of use to event loop authors who want |
|
|
1165 | to provide AnyEvent compatibility. |
|
|
1166 | |
|
|
1167 | If you need to support another event library which isn't directly |
|
|
1168 | supported by AnyEvent, you can supply your own interface to it by |
|
|
1169 | pushing, before the first watcher gets created, the package name of the |
|
|
1170 | event module and the package name of the interface to use onto |
|
|
1171 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
1172 | AnyEvent, so it is reasonably cheap. |
|
|
1173 | |
|
|
1174 | Example: |
|
|
1175 | |
|
|
1176 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
1177 | |
|
|
1178 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
1179 | package/class when it finds the "urxvt" package/module is already |
|
|
1180 | loaded. |
|
|
1181 | |
|
|
1182 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
1183 | will first check for the presence of urxvt by trying to "use" the |
|
|
1184 | "urxvt::anyevent" module. |
|
|
1185 | |
|
|
1186 | The class should provide implementations for all watcher types. See |
|
|
1187 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
1188 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
1189 | the sources. |
|
|
1190 | |
|
|
1191 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
1192 | provide suitable (hopefully) replacements. |
|
|
1193 | |
|
|
1194 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
1195 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1196 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
1197 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
1198 | part of the *rxvt-unicode* distribution. |
|
|
1199 | |
|
|
1200 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
1201 | condition variables: code blocking while waiting for a condition will |
|
|
1202 | "die". This still works with most modules/usages, and blocking calls |
|
|
1203 | must not be done in an interactive application, so it makes sense. |
886 | |
1204 | |
887 | EXAMPLE PROGRAM |
1205 | EXAMPLE PROGRAM |
888 | The following program uses an I/O watcher to read data from STDIN, a |
1206 | The following program uses an I/O watcher to read data from STDIN, a |
889 | timer to display a message once per second, and a condition variable to |
1207 | timer to display a message once per second, and a condition variable to |
890 | quit the program when the user enters quit: |
1208 | quit the program when the user enters quit: |
… | |
… | |
1077 | *destroy* is the time, in microseconds, that it takes to destroy a |
1395 | *destroy* is the time, in microseconds, that it takes to destroy a |
1078 | single watcher. |
1396 | single watcher. |
1079 | |
1397 | |
1080 | Results |
1398 | Results |
1081 | name watchers bytes create invoke destroy comment |
1399 | name watchers bytes create invoke destroy comment |
1082 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1400 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1083 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1401 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1084 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1402 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1085 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1403 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1086 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1404 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1087 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
1405 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1406 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1407 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1088 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1408 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1089 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1409 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1090 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1410 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1091 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1411 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1092 | |
1412 | |
1093 | Discussion |
1413 | Discussion |
1094 | The benchmark does *not* measure scalability of the event loop very |
1414 | The benchmark does *not* measure scalability of the event loop very |
1095 | well. For example, a select-based event loop (such as the pure perl one) |
1415 | well. For example, a select-based event loop (such as the pure perl one) |
1096 | can never compete with an event loop that uses epoll when the number of |
1416 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1121 | few of them active), of course, but this was not subject of this |
1441 | few of them active), of course, but this was not subject of this |
1122 | benchmark. |
1442 | benchmark. |
1123 | |
1443 | |
1124 | The "Event" module has a relatively high setup and callback invocation |
1444 | The "Event" module has a relatively high setup and callback invocation |
1125 | cost, but overall scores in on the third place. |
1445 | cost, but overall scores in on the third place. |
|
|
1446 | |
|
|
1447 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1448 | when using its pure perl backend. |
1126 | |
1449 | |
1127 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1450 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1128 | callback invocation and overall ends up in the same class as "Event". |
1451 | callback invocation and overall ends up in the same class as "Event". |
1129 | However, Glib scales extremely badly, doubling the number of watchers |
1452 | However, Glib scales extremely badly, doubling the number of watchers |
1130 | increases the processing time by more than a factor of four, making it |
1453 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1201 | single "request", that is, reading the token from the pipe and |
1524 | single "request", that is, reading the token from the pipe and |
1202 | forwarding it to another server. This includes deleting the old timeout |
1525 | forwarding it to another server. This includes deleting the old timeout |
1203 | and creating a new one that moves the timeout into the future. |
1526 | and creating a new one that moves the timeout into the future. |
1204 | |
1527 | |
1205 | Results |
1528 | Results |
1206 | name sockets create request |
1529 | name sockets create request |
1207 | EV 20000 69.01 11.16 |
1530 | EV 20000 69.01 11.16 |
1208 | Perl 20000 73.32 35.87 |
1531 | Perl 20000 73.32 35.87 |
|
|
1532 | IOAsync 20000 157.00 98.14 epoll |
|
|
1533 | IOAsync 20000 159.31 616.06 poll |
1209 | Event 20000 212.62 257.32 |
1534 | Event 20000 212.62 257.32 |
1210 | Glib 20000 651.16 1896.30 |
1535 | Glib 20000 651.16 1896.30 |
1211 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1536 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1212 | |
1537 | |
1213 | Discussion |
1538 | Discussion |
1214 | This benchmark *does* measure scalability and overall performance of the |
1539 | This benchmark *does* measure scalability and overall performance of the |
1215 | particular event loop. |
1540 | particular event loop. |
1216 | |
1541 | |
1217 | EV is again fastest. Since it is using epoll on my system, the setup |
1542 | EV is again fastest. Since it is using epoll on my system, the setup |
1218 | time is relatively high, though. |
1543 | time is relatively high, though. |
1219 | |
1544 | |
1220 | Perl surprisingly comes second. It is much faster than the C-based event |
1545 | Perl surprisingly comes second. It is much faster than the C-based event |
1221 | loops Event and Glib. |
1546 | loops Event and Glib. |
|
|
1547 | |
|
|
1548 | IO::Async performs very well when using its epoll backend, and still |
|
|
1549 | quite good compared to Glib when using its pure perl backend. |
1222 | |
1550 | |
1223 | Event suffers from high setup time as well (look at its code and you |
1551 | Event suffers from high setup time as well (look at its code and you |
1224 | will understand why). Callback invocation also has a high overhead |
1552 | will understand why). Callback invocation also has a high overhead |
1225 | compared to the "$_->() for .."-style loop that the Perl event loop |
1553 | compared to the "$_->() for .."-style loop that the Perl event loop |
1226 | uses. Event uses select or poll in basically all documented |
1554 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1277 | |
1605 | |
1278 | Summary |
1606 | Summary |
1279 | * C-based event loops perform very well with small number of watchers, |
1607 | * C-based event loops perform very well with small number of watchers, |
1280 | as the management overhead dominates. |
1608 | as the management overhead dominates. |
1281 | |
1609 | |
|
|
1610 | THE IO::Lambda BENCHMARK |
|
|
1611 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1612 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1613 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1614 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1615 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1616 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1617 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1618 | benchmark for AnyEvent. |
|
|
1619 | |
|
|
1620 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1621 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1622 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1623 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1624 | but it is a benchmark nevertheless. |
|
|
1625 | |
|
|
1626 | name runtime |
|
|
1627 | Lambda/select 0.330 sec |
|
|
1628 | + optimized 0.122 sec |
|
|
1629 | Lambda/AnyEvent 0.327 sec |
|
|
1630 | + optimized 0.138 sec |
|
|
1631 | Raw sockets/select 0.077 sec |
|
|
1632 | POE/select, components 0.662 sec |
|
|
1633 | POE/select, raw sockets 0.226 sec |
|
|
1634 | POE/select, optimized 0.404 sec |
|
|
1635 | |
|
|
1636 | AnyEvent/select/nb 0.085 sec |
|
|
1637 | AnyEvent/EV/nb 0.068 sec |
|
|
1638 | +state machine 0.134 sec |
|
|
1639 | |
|
|
1640 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1641 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1642 | defeating the purpose of an event-based solution. All of the newly |
|
|
1643 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1644 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1645 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1646 | connects generally require a lot more bookkeeping and event handling |
|
|
1647 | than blocking connects (which involve a single syscall only). |
|
|
1648 | |
|
|
1649 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1650 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1651 | conventional Perl syntax. This means that both the echo server and the |
|
|
1652 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1653 | |
|
|
1654 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1655 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1656 | backend easily beats IO::Lambda and POE. |
|
|
1657 | |
|
|
1658 | And even the 100% non-blocking version written using the high-level (and |
|
|
1659 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1660 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1661 | in a non-blocking way. |
|
|
1662 | |
|
|
1663 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1664 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1665 | part of the IO::lambda distribution and were used without any changes. |
|
|
1666 | |
|
|
1667 | SIGNALS |
|
|
1668 | AnyEvent currently installs handlers for these signals: |
|
|
1669 | |
|
|
1670 | SIGCHLD |
|
|
1671 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
|
|
1672 | emulation for event loops that do not support them natively. Also, |
|
|
1673 | some event loops install a similar handler. |
|
|
1674 | |
|
|
1675 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1676 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1677 | statuses. |
|
|
1678 | |
|
|
1679 | SIGPIPE |
|
|
1680 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
|
|
1681 | "undef" when AnyEvent gets loaded. |
|
|
1682 | |
|
|
1683 | The rationale for this is that AnyEvent users usually do not really |
|
|
1684 | depend on SIGPIPE delivery (which is purely an optimisation for |
|
|
1685 | shell use, or badly-written programs), but "SIGPIPE" can cause |
|
|
1686 | spurious and rare program exits as a lot of people do not expect |
|
|
1687 | "SIGPIPE" when writing to some random socket. |
|
|
1688 | |
|
|
1689 | The rationale for installing a no-op handler as opposed to ignoring |
|
|
1690 | it is that this way, the handler will be restored to defaults on |
|
|
1691 | exec. |
|
|
1692 | |
|
|
1693 | Feel free to install your own handler, or reset it to defaults. |
|
|
1694 | |
|
|
1695 | RECOMMENDED/OPTIONAL MODULES |
|
|
1696 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1697 | it's built-in modules) are required to use it. |
|
|
1698 | |
|
|
1699 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1700 | modules if they are installed. |
|
|
1701 | |
|
|
1702 | This section epxlains which additional modules will be used, and how |
|
|
1703 | they affect AnyEvent's operetion. |
|
|
1704 | |
|
|
1705 | Async::Interrupt |
|
|
1706 | This slightly arcane module is used to implement fast signal |
|
|
1707 | handling: To my knowledge, there is no way to do completely |
|
|
1708 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1709 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1710 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1711 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1712 | |
|
|
1713 | If this module is available, then it will be used to implement |
|
|
1714 | signal catching, which means that signals will not be delayed, and |
|
|
1715 | the event loop will not be interrupted regularly, which is more |
|
|
1716 | efficient (And good for battery life on laptops). |
|
|
1717 | |
|
|
1718 | This affects not just the pure-perl event loop, but also other event |
|
|
1719 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1720 | |
|
|
1721 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1722 | natively, and either employ their own workarounds (POE) or use |
|
|
1723 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1724 | Installing Async::Interrupt does nothing for those backends. |
|
|
1725 | |
|
|
1726 | EV This module isn't really "optional", as it is simply one of the |
|
|
1727 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1728 | best event loop available in terms of features, speed and stability: |
|
|
1729 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1730 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1731 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1732 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1733 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1734 | Glib::EV). |
|
|
1735 | |
|
|
1736 | Guard |
|
|
1737 | The guard module, when used, will be used to implement |
|
|
1738 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1739 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1740 | operation much. It is purely used for performance. |
|
|
1741 | |
|
|
1742 | JSON and JSON::XS |
|
|
1743 | This module is required when you want to read or write JSON data via |
|
|
1744 | AnyEvent::Handle. It is also written in pure-perl, but can take |
|
|
1745 | advantage of the ultra-high-speed JSON::XS module when it is |
|
|
1746 | installed. |
|
|
1747 | |
|
|
1748 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1749 | installed. |
|
|
1750 | |
|
|
1751 | Net::SSLeay |
|
|
1752 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1753 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1754 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1755 | |
|
|
1756 | Time::HiRes |
|
|
1757 | This module is part of perl since release 5.008. It will be used |
|
|
1758 | when the chosen event library does not come with a timing source on |
|
|
1759 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1760 | additionally use it to try to use a monotonic clock for timing |
|
|
1761 | stability. |
|
|
1762 | |
1282 | FORK |
1763 | FORK |
1283 | Most event libraries are not fork-safe. The ones who are usually are |
1764 | Most event libraries are not fork-safe. The ones who are usually are |
1284 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1765 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1285 | Only EV is fully fork-aware. |
1766 | Only EV is fully fork-aware. |
1286 | |
1767 | |
1287 | If you have to fork, you must either do so *before* creating your first |
1768 | If you have to fork, you must either do so *before* creating your first |
1288 | watcher OR you must not use AnyEvent at all in the child. |
1769 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1770 | something completely out of the scope of AnyEvent. |
1289 | |
1771 | |
1290 | SECURITY CONSIDERATIONS |
1772 | SECURITY CONSIDERATIONS |
1291 | AnyEvent can be forced to load any event model via |
1773 | AnyEvent can be forced to load any event model via |
1292 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1774 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1293 | to execute arbitrary code or directly gain access, it can easily be used |
1775 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1297 | |
1779 | |
1298 | You can make AnyEvent completely ignore this variable by deleting it |
1780 | You can make AnyEvent completely ignore this variable by deleting it |
1299 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1781 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1300 | |
1782 | |
1301 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1783 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1302 | |
1784 | |
1303 | use AnyEvent; |
1785 | use AnyEvent; |
1304 | |
1786 | |
1305 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1787 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1306 | be used to probe what backend is used and gain other information (which |
1788 | be used to probe what backend is used and gain other information (which |
1307 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1789 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1308 | and $ENV{PERL_ANYEGENT_STRICT}. |
1790 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1791 | |
|
|
1792 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1793 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1794 | enabled. |
1309 | |
1795 | |
1310 | BUGS |
1796 | BUGS |
1311 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1797 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1312 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1798 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1313 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1799 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1314 | annoying mamleaks, such as leaking on "map" and "grep" but it is usually |
1800 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1315 | not as pronounced). |
1801 | not as pronounced). |
1316 | |
1802 | |
1317 | SEE ALSO |
1803 | SEE ALSO |
1318 | Utility functions: AnyEvent::Util. |
1804 | Utility functions: AnyEvent::Util. |
1319 | |
1805 | |
1320 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1806 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1321 | Event::Lib, Qt, POE. |
1807 | Event::Lib, Qt, POE. |
1322 | |
1808 | |
1323 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1809 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1324 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1810 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1325 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1811 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1812 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
1326 | |
1813 | |
1327 | Non-blocking file handles, sockets, TCP clients and servers: |
1814 | Non-blocking file handles, sockets, TCP clients and servers: |
1328 | AnyEvent::Handle, AnyEvent::Socket. |
1815 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1329 | |
1816 | |
1330 | Asynchronous DNS: AnyEvent::DNS. |
1817 | Asynchronous DNS: AnyEvent::DNS. |
1331 | |
1818 | |
1332 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1819 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1333 | |
1820 | |
1334 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1821 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1822 | AnyEvent::HTTP. |
1335 | |
1823 | |
1336 | AUTHOR |
1824 | AUTHOR |
1337 | Marc Lehmann <schmorp@schmorp.de> |
1825 | Marc Lehmann <schmorp@schmorp.de> |
1338 | http://home.schmorp.de/ |
1826 | http://home.schmorp.de/ |
1339 | |
1827 | |