1 | =head1 NAME |
1 | =head1 => NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - provide framework for multiple event loops |
4 | |
4 | |
5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
… | |
… | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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20 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
… | |
… | |
48 | isn't itself. What's worse, all the potential users of your module are |
48 | isn't itself. What's worse, all the potential users of your module are |
49 | I<also> forced to use the same event loop you use. |
49 | I<also> forced to use the same event loop you use. |
50 | |
50 | |
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
53 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
54 | your module uses one of those, every user of your module has to use it, |
54 | your module uses one of those, every user of your module has to use it, |
55 | too. But if your module uses AnyEvent, it works transparently with all |
55 | too. But if your module uses AnyEvent, it works transparently with all |
56 | event models it supports (including stuff like POE and IO::Async, as long |
56 | event models it supports (including stuff like POE and IO::Async, as long |
57 | as those use one of the supported event loops. It is trivial to add new |
57 | as those use one of the supported event loops. It is trivial to add new |
58 | event loops to AnyEvent, too, so it is future-proof). |
58 | event loops to AnyEvent, too, so it is future-proof). |
59 | |
59 | |
60 | In addition to being free of having to use I<the one and only true event |
60 | In addition to being free of having to use I<the one and only true event |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
62 | modules, you get an enourmous amount of code and strict rules you have to |
62 | modules, you get an enormous amount of code and strict rules you have to |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
65 | technically possible. |
65 | technically possible. |
66 | |
66 | |
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67 | Of course, AnyEvent comes with a big (and fully optional!) toolbox |
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68 | of useful functionality, such as an asynchronous DNS resolver, 100% |
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69 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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70 | such as Windows) and lots of real-world knowledge and workarounds for |
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71 | platform bugs and differences. |
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72 | |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
73 | Now, if you I<do want> lots of policy (this can arguably be somewhat |
68 | useful) and you want to force your users to use the one and only event |
74 | useful) and you want to force your users to use the one and only event |
69 | model, you should I<not> use this module. |
75 | model, you should I<not> use this module. |
70 | |
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71 | |
76 | |
72 | =head1 DESCRIPTION |
77 | =head1 DESCRIPTION |
73 | |
78 | |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
79 | L<AnyEvent> provides an identical interface to multiple event loops. This |
75 | allows module authors to utilise an event loop without forcing module |
80 | allows module authors to utilise an event loop without forcing module |
… | |
… | |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
84 | The interface itself is vaguely similar, but not identical to the L<Event> |
80 | module. |
85 | module. |
81 | |
86 | |
82 | During the first call of any watcher-creation method, the module tries |
87 | During the first call of any watcher-creation method, the module tries |
83 | to detect the currently loaded event loop by probing whether one of the |
88 | to detect the currently loaded event loop by probing whether one of the |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
89 | following modules is already loaded: L<EV>, |
85 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
90 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
86 | L<POE>. The first one found is used. If none are found, the module tries |
91 | L<POE>. The first one found is used. If none are found, the module tries |
87 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
92 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
88 | adaptor should always succeed) in the order given. The first one that can |
93 | adaptor should always succeed) in the order given. The first one that can |
89 | be successfully loaded will be used. If, after this, still none could be |
94 | be successfully loaded will be used. If, after this, still none could be |
… | |
… | |
103 | starts using it, all bets are off. Maybe you should tell their authors to |
108 | starts using it, all bets are off. Maybe you should tell their authors to |
104 | use AnyEvent so their modules work together with others seamlessly... |
109 | use AnyEvent so their modules work together with others seamlessly... |
105 | |
110 | |
106 | The pure-perl implementation of AnyEvent is called |
111 | The pure-perl implementation of AnyEvent is called |
107 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
112 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
108 | explicitly. |
113 | explicitly and enjoy the high availability of that event loop :) |
109 | |
114 | |
110 | =head1 WATCHERS |
115 | =head1 WATCHERS |
111 | |
116 | |
112 | AnyEvent has the central concept of a I<watcher>, which is an object that |
117 | AnyEvent has the central concept of a I<watcher>, which is an object that |
113 | stores relevant data for each kind of event you are waiting for, such as |
118 | stores relevant data for each kind of event you are waiting for, such as |
114 | the callback to call, the filehandle to watch, etc. |
119 | the callback to call, the file handle to watch, etc. |
115 | |
120 | |
116 | These watchers are normal Perl objects with normal Perl lifetime. After |
121 | These watchers are normal Perl objects with normal Perl lifetime. After |
117 | creating a watcher it will immediately "watch" for events and invoke the |
122 | creating a watcher it will immediately "watch" for events and invoke the |
118 | callback when the event occurs (of course, only when the event model |
123 | callback when the event occurs (of course, only when the event model |
119 | is in control). |
124 | is in control). |
… | |
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228 | timers. |
233 | timers. |
229 | |
234 | |
230 | AnyEvent always prefers relative timers, if available, matching the |
235 | AnyEvent always prefers relative timers, if available, matching the |
231 | AnyEvent API. |
236 | AnyEvent API. |
232 | |
237 | |
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238 | AnyEvent has two additional methods that return the "current time": |
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239 | |
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240 | =over 4 |
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241 | |
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242 | =item AnyEvent->time |
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243 | |
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244 | This returns the "current wallclock time" as a fractional number of |
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245 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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246 | return, and the result is guaranteed to be compatible with those). |
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247 | |
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248 | It progresses independently of any event loop processing. |
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249 | |
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250 | In almost all cases (in all cases if you don't care), this is the function |
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251 | to call when you want to know the current time. |
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252 | |
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253 | =item AnyEvent->now |
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254 | |
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255 | This also returns the "current wallclock time", but unlike C<time>, above, |
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256 | this value might change only once per event loop iteration, depending on |
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257 | the event loop (most return the same time as C<time>, above). This is the |
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258 | time that AnyEvent timers get scheduled against. |
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259 | |
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260 | For a practical example of when these times differ, consider L<Event::Lib> |
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261 | and L<EV> and the following set-up: |
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262 | |
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263 | The event loop is running and has just invoked one of your callback at |
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264 | time=500 (assume no other callbacks delay processing). In your callback, |
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265 | you wait a second by executing C<sleep 1> (blocking the process for a |
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266 | second) and then (at time=501) you create a relative timer that fires |
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267 | after three seconds. |
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268 | |
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269 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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270 | both return C<501>, because that is the current time, and the timer will |
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271 | be scheduled to fire at time=504 (C<501> + C<3>). |
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272 | |
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273 | With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current |
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274 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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275 | last event processing phase started. With L<EV>, your timer gets scheduled |
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276 | to run at time=503 (C<500> + C<3>). |
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277 | |
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278 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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279 | regardless of any delays introduced by event processing. However, most |
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280 | callbacks do not expect large delays in processing, so this causes a |
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281 | higher drift (and a lot more syscalls to get the current time). |
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282 | |
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283 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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284 | the same time, regardless of how long event processing actually took. |
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285 | |
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286 | In either case, if you care (and in most cases, you don't), then you |
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287 | can get whatever behaviour you want with any event loop, by taking the |
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288 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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289 | account. |
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290 | |
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291 | =back |
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292 | |
233 | =head2 SIGNAL WATCHERS |
293 | =head2 SIGNAL WATCHERS |
234 | |
294 | |
235 | You can watch for signals using a signal watcher, C<signal> is the signal |
295 | You can watch for signals using a signal watcher, C<signal> is the signal |
236 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
296 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
237 | be invoked whenever a signal occurs. |
297 | be invoked whenever a signal occurs. |
238 | |
298 | |
239 | Although the callback might get passed parameters, their value and |
299 | Although the callback might get passed parameters, their value and |
240 | presence is undefined and you cannot rely on them. Portable AnyEvent |
300 | presence is undefined and you cannot rely on them. Portable AnyEvent |
241 | callbacks cannot use arguments passed to signal watcher callbacks. |
301 | callbacks cannot use arguments passed to signal watcher callbacks. |
242 | |
302 | |
243 | Multiple signal occurances can be clumped together into one callback |
303 | Multiple signal occurrences can be clumped together into one callback |
244 | invocation, and callback invocation will be synchronous. synchronous means |
304 | invocation, and callback invocation will be synchronous. Synchronous means |
245 | that it might take a while until the signal gets handled by the process, |
305 | that it might take a while until the signal gets handled by the process, |
246 | but it is guarenteed not to interrupt any other callbacks. |
306 | but it is guaranteed not to interrupt any other callbacks. |
247 | |
307 | |
248 | The main advantage of using these watchers is that you can share a signal |
308 | The main advantage of using these watchers is that you can share a signal |
249 | between multiple watchers. |
309 | between multiple watchers. |
250 | |
310 | |
251 | This watcher might use C<%SIG>, so programs overwriting those signals |
311 | This watcher might use C<%SIG>, so programs overwriting those signals |
… | |
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280 | |
340 | |
281 | Example: fork a process and wait for it |
341 | Example: fork a process and wait for it |
282 | |
342 | |
283 | my $done = AnyEvent->condvar; |
343 | my $done = AnyEvent->condvar; |
284 | |
344 | |
285 | AnyEvent::detect; # force event module to be initialised |
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286 | |
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287 | my $pid = fork or exit 5; |
345 | my $pid = fork or exit 5; |
288 | |
346 | |
289 | my $w = AnyEvent->child ( |
347 | my $w = AnyEvent->child ( |
290 | pid => $pid, |
348 | pid => $pid, |
291 | cb => sub { |
349 | cb => sub { |
292 | my ($pid, $status) = @_; |
350 | my ($pid, $status) = @_; |
293 | warn "pid $pid exited with status $status"; |
351 | warn "pid $pid exited with status $status"; |
294 | $done->broadcast; |
352 | $done->send; |
295 | }, |
353 | }, |
296 | ); |
354 | ); |
297 | |
355 | |
298 | # do something else, then wait for process exit |
356 | # do something else, then wait for process exit |
299 | $done->wait; |
357 | $done->recv; |
300 | |
358 | |
301 | =head2 CONDITION VARIABLES |
359 | =head2 CONDITION VARIABLES |
302 | |
360 | |
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361 | If you are familiar with some event loops you will know that all of them |
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362 | require you to run some blocking "loop", "run" or similar function that |
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363 | will actively watch for new events and call your callbacks. |
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364 | |
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365 | AnyEvent is different, it expects somebody else to run the event loop and |
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366 | will only block when necessary (usually when told by the user). |
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367 | |
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368 | The instrument to do that is called a "condition variable", so called |
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369 | because they represent a condition that must become true. |
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370 | |
303 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
371 | Condition variables can be created by calling the C<< AnyEvent->condvar |
304 | method without any arguments. |
372 | >> method, usually without arguments. The only argument pair allowed is |
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373 | C<cb>, which specifies a callback to be called when the condition variable |
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374 | becomes true. |
305 | |
375 | |
306 | A condition variable waits for a condition - precisely that the C<< |
376 | After creation, the condition variable is "false" until it becomes "true" |
307 | ->broadcast >> method has been called. |
377 | by calling the C<send> method (or calling the condition variable as if it |
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378 | were a callback, read about the caveats in the description for the C<< |
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379 | ->send >> method). |
308 | |
380 | |
309 | They are very useful to signal that a condition has been fulfilled, for |
381 | Condition variables are similar to callbacks, except that you can |
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382 | optionally wait for them. They can also be called merge points - points |
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383 | in time where multiple outstanding events have been processed. And yet |
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384 | another way to call them is transactions - each condition variable can be |
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385 | used to represent a transaction, which finishes at some point and delivers |
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386 | a result. |
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387 | |
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388 | Condition variables are very useful to signal that something has finished, |
310 | example, if you write a module that does asynchronous http requests, |
389 | for example, if you write a module that does asynchronous http requests, |
311 | then a condition variable would be the ideal candidate to signal the |
390 | then a condition variable would be the ideal candidate to signal the |
312 | availability of results. |
391 | availability of results. The user can either act when the callback is |
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392 | called or can synchronously C<< ->recv >> for the results. |
313 | |
393 | |
314 | You can also use condition variables to block your main program until |
394 | You can also use them to simulate traditional event loops - for example, |
315 | an event occurs - for example, you could C<< ->wait >> in your main |
395 | you can block your main program until an event occurs - for example, you |
316 | program until the user clicks the Quit button in your app, which would C<< |
396 | could C<< ->recv >> in your main program until the user clicks the Quit |
317 | ->broadcast >> the "quit" event. |
397 | button of your app, which would C<< ->send >> the "quit" event. |
318 | |
398 | |
319 | Note that condition variables recurse into the event loop - if you have |
399 | Note that condition variables recurse into the event loop - if you have |
320 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
400 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
321 | lose. Therefore, condition variables are good to export to your caller, but |
401 | lose. Therefore, condition variables are good to export to your caller, but |
322 | you should avoid making a blocking wait yourself, at least in callbacks, |
402 | you should avoid making a blocking wait yourself, at least in callbacks, |
323 | as this asks for trouble. |
403 | as this asks for trouble. |
324 | |
404 | |
325 | This object has two methods: |
405 | Condition variables are represented by hash refs in perl, and the keys |
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406 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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407 | easy (it is often useful to build your own transaction class on top of |
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408 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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409 | it's C<new> method in your own C<new> method. |
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410 | |
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411 | There are two "sides" to a condition variable - the "producer side" which |
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412 | eventually calls C<< -> send >>, and the "consumer side", which waits |
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413 | for the send to occur. |
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414 | |
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415 | Example: wait for a timer. |
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416 | |
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417 | # wait till the result is ready |
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418 | my $result_ready = AnyEvent->condvar; |
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419 | |
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420 | # do something such as adding a timer |
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421 | # or socket watcher the calls $result_ready->send |
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422 | # when the "result" is ready. |
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423 | # in this case, we simply use a timer: |
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424 | my $w = AnyEvent->timer ( |
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425 | after => 1, |
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426 | cb => sub { $result_ready->send }, |
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427 | ); |
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428 | |
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429 | # this "blocks" (while handling events) till the callback |
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430 | # calls send |
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431 | $result_ready->recv; |
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432 | |
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433 | Example: wait for a timer, but take advantage of the fact that |
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434 | condition variables are also code references. |
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435 | |
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436 | my $done = AnyEvent->condvar; |
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437 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
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438 | $done->recv; |
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439 | |
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440 | =head3 METHODS FOR PRODUCERS |
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441 | |
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442 | These methods should only be used by the producing side, i.e. the |
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443 | code/module that eventually sends the signal. Note that it is also |
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444 | the producer side which creates the condvar in most cases, but it isn't |
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445 | uncommon for the consumer to create it as well. |
326 | |
446 | |
327 | =over 4 |
447 | =over 4 |
328 | |
448 | |
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449 | =item $cv->send (...) |
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450 | |
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451 | Flag the condition as ready - a running C<< ->recv >> and all further |
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452 | calls to C<recv> will (eventually) return after this method has been |
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453 | called. If nobody is waiting the send will be remembered. |
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454 | |
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455 | If a callback has been set on the condition variable, it is called |
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456 | immediately from within send. |
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457 | |
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458 | Any arguments passed to the C<send> call will be returned by all |
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459 | future C<< ->recv >> calls. |
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460 | |
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461 | Condition variables are overloaded so one can call them directly |
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462 | (as a code reference). Calling them directly is the same as calling |
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463 | C<send>. Note, however, that many C-based event loops do not handle |
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464 | overloading, so as tempting as it may be, passing a condition variable |
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465 | instead of a callback does not work. Both the pure perl and EV loops |
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466 | support overloading, however, as well as all functions that use perl to |
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467 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
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468 | example). |
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469 | |
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470 | =item $cv->croak ($error) |
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471 | |
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472 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
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473 | C<Carp::croak> with the given error message/object/scalar. |
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474 | |
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475 | This can be used to signal any errors to the condition variable |
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476 | user/consumer. |
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477 | |
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478 | =item $cv->begin ([group callback]) |
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479 | |
329 | =item $cv->wait |
480 | =item $cv->end |
330 | |
481 | |
331 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
482 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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483 | |
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484 | These two methods can be used to combine many transactions/events into |
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485 | one. For example, a function that pings many hosts in parallel might want |
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486 | to use a condition variable for the whole process. |
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487 | |
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488 | Every call to C<< ->begin >> will increment a counter, and every call to |
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489 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
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490 | >>, the (last) callback passed to C<begin> will be executed. That callback |
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491 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
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492 | callback was set, C<send> will be called without any arguments. |
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493 | |
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494 | Let's clarify this with the ping example: |
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495 | |
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496 | my $cv = AnyEvent->condvar; |
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497 | |
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498 | my %result; |
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499 | $cv->begin (sub { $cv->send (\%result) }); |
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500 | |
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501 | for my $host (@list_of_hosts) { |
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502 | $cv->begin; |
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503 | ping_host_then_call_callback $host, sub { |
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504 | $result{$host} = ...; |
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505 | $cv->end; |
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506 | }; |
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507 | } |
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508 | |
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509 | $cv->end; |
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510 | |
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511 | This code fragment supposedly pings a number of hosts and calls |
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512 | C<send> after results for all then have have been gathered - in any |
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513 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
514 | each ping request and calls C<end> when it has received some result for |
|
|
515 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
516 | results arrive is not relevant. |
|
|
517 | |
|
|
518 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
519 | loop, which serves two important purposes: first, it sets the callback |
|
|
520 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
521 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
522 | doesn't execute once). |
|
|
523 | |
|
|
524 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
525 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
526 | is called at least once, and then, for each subrequest you start, call |
|
|
527 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
528 | |
|
|
529 | =back |
|
|
530 | |
|
|
531 | =head3 METHODS FOR CONSUMERS |
|
|
532 | |
|
|
533 | These methods should only be used by the consuming side, i.e. the |
|
|
534 | code awaits the condition. |
|
|
535 | |
|
|
536 | =over 4 |
|
|
537 | |
|
|
538 | =item $cv->recv |
|
|
539 | |
|
|
540 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
332 | called on c<$cv>, while servicing other watchers normally. |
541 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
542 | normally. |
333 | |
543 | |
334 | You can only wait once on a condition - additional calls will return |
544 | You can only wait once on a condition - additional calls are valid but |
335 | immediately. |
545 | will return immediately. |
|
|
546 | |
|
|
547 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
548 | function will call C<croak>. |
|
|
549 | |
|
|
550 | In list context, all parameters passed to C<send> will be returned, |
|
|
551 | in scalar context only the first one will be returned. |
336 | |
552 | |
337 | Not all event models support a blocking wait - some die in that case |
553 | Not all event models support a blocking wait - some die in that case |
338 | (programs might want to do that to stay interactive), so I<if you are |
554 | (programs might want to do that to stay interactive), so I<if you are |
339 | using this from a module, never require a blocking wait>, but let the |
555 | using this from a module, never require a blocking wait>, but let the |
340 | caller decide whether the call will block or not (for example, by coupling |
556 | caller decide whether the call will block or not (for example, by coupling |
341 | condition variables with some kind of request results and supporting |
557 | condition variables with some kind of request results and supporting |
342 | callbacks so the caller knows that getting the result will not block, |
558 | callbacks so the caller knows that getting the result will not block, |
343 | while still suppporting blocking waits if the caller so desires). |
559 | while still supporting blocking waits if the caller so desires). |
344 | |
560 | |
345 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
561 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
346 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
562 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
347 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
563 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
348 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
564 | can supply. |
349 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
|
|
350 | from different coroutines, however). |
|
|
351 | |
565 | |
352 | =item $cv->broadcast |
566 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
567 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
568 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
569 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
570 | coroutine (one that doesn't run the event loop). |
353 | |
571 | |
354 | Flag the condition as ready - a running C<< ->wait >> and all further |
572 | You can ensure that C<< -recv >> never blocks by setting a callback and |
355 | calls to C<wait> will (eventually) return after this method has been |
573 | only calling C<< ->recv >> from within that callback (or at a later |
356 | called. If nobody is waiting the broadcast will be remembered.. |
574 | time). This will work even when the event loop does not support blocking |
|
|
575 | waits otherwise. |
|
|
576 | |
|
|
577 | =item $bool = $cv->ready |
|
|
578 | |
|
|
579 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
580 | C<croak> have been called. |
|
|
581 | |
|
|
582 | =item $cb = $cv->cb ([new callback]) |
|
|
583 | |
|
|
584 | This is a mutator function that returns the callback set and optionally |
|
|
585 | replaces it before doing so. |
|
|
586 | |
|
|
587 | The callback will be called when the condition becomes "true", i.e. when |
|
|
588 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
589 | or at any later time is guaranteed not to block. |
357 | |
590 | |
358 | =back |
591 | =back |
359 | |
|
|
360 | Example: |
|
|
361 | |
|
|
362 | # wait till the result is ready |
|
|
363 | my $result_ready = AnyEvent->condvar; |
|
|
364 | |
|
|
365 | # do something such as adding a timer |
|
|
366 | # or socket watcher the calls $result_ready->broadcast |
|
|
367 | # when the "result" is ready. |
|
|
368 | # in this case, we simply use a timer: |
|
|
369 | my $w = AnyEvent->timer ( |
|
|
370 | after => 1, |
|
|
371 | cb => sub { $result_ready->broadcast }, |
|
|
372 | ); |
|
|
373 | |
|
|
374 | # this "blocks" (while handling events) till the watcher |
|
|
375 | # calls broadcast |
|
|
376 | $result_ready->wait; |
|
|
377 | |
592 | |
378 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
593 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
379 | |
594 | |
380 | =over 4 |
595 | =over 4 |
381 | |
596 | |
… | |
… | |
387 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
602 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
388 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
603 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
389 | |
604 | |
390 | The known classes so far are: |
605 | The known classes so far are: |
391 | |
606 | |
392 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
393 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
394 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
607 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
395 | AnyEvent::Impl::Event based on Event, second best choice. |
608 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
609 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
396 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
610 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
397 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
398 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
611 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
399 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
612 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
400 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
613 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
401 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
614 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
402 | |
615 | |
… | |
… | |
415 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
628 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
416 | if necessary. You should only call this function right before you would |
629 | if necessary. You should only call this function right before you would |
417 | have created an AnyEvent watcher anyway, that is, as late as possible at |
630 | have created an AnyEvent watcher anyway, that is, as late as possible at |
418 | runtime. |
631 | runtime. |
419 | |
632 | |
|
|
633 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
634 | |
|
|
635 | Arranges for the code block to be executed as soon as the event model is |
|
|
636 | autodetected (or immediately if this has already happened). |
|
|
637 | |
|
|
638 | If called in scalar or list context, then it creates and returns an object |
|
|
639 | that automatically removes the callback again when it is destroyed. See |
|
|
640 | L<Coro::BDB> for a case where this is useful. |
|
|
641 | |
|
|
642 | =item @AnyEvent::post_detect |
|
|
643 | |
|
|
644 | If there are any code references in this array (you can C<push> to it |
|
|
645 | before or after loading AnyEvent), then they will called directly after |
|
|
646 | the event loop has been chosen. |
|
|
647 | |
|
|
648 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
649 | if it contains a true value then the event loop has already been detected, |
|
|
650 | and the array will be ignored. |
|
|
651 | |
|
|
652 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
653 | |
420 | =back |
654 | =back |
421 | |
655 | |
422 | =head1 WHAT TO DO IN A MODULE |
656 | =head1 WHAT TO DO IN A MODULE |
423 | |
657 | |
424 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
658 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
… | |
… | |
427 | Be careful when you create watchers in the module body - AnyEvent will |
661 | Be careful when you create watchers in the module body - AnyEvent will |
428 | decide which event module to use as soon as the first method is called, so |
662 | decide which event module to use as soon as the first method is called, so |
429 | by calling AnyEvent in your module body you force the user of your module |
663 | by calling AnyEvent in your module body you force the user of your module |
430 | to load the event module first. |
664 | to load the event module first. |
431 | |
665 | |
432 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
666 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
433 | the C<< ->broadcast >> method has been called on it already. This is |
667 | the C<< ->send >> method has been called on it already. This is |
434 | because it will stall the whole program, and the whole point of using |
668 | because it will stall the whole program, and the whole point of using |
435 | events is to stay interactive. |
669 | events is to stay interactive. |
436 | |
670 | |
437 | It is fine, however, to call C<< ->wait >> when the user of your module |
671 | It is fine, however, to call C<< ->recv >> when the user of your module |
438 | requests it (i.e. if you create a http request object ad have a method |
672 | requests it (i.e. if you create a http request object ad have a method |
439 | called C<results> that returns the results, it should call C<< ->wait >> |
673 | called C<results> that returns the results, it should call C<< ->recv >> |
440 | freely, as the user of your module knows what she is doing. always). |
674 | freely, as the user of your module knows what she is doing. always). |
441 | |
675 | |
442 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
676 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
443 | |
677 | |
444 | There will always be a single main program - the only place that should |
678 | There will always be a single main program - the only place that should |
… | |
… | |
446 | |
680 | |
447 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
681 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
448 | do anything special (it does not need to be event-based) and let AnyEvent |
682 | do anything special (it does not need to be event-based) and let AnyEvent |
449 | decide which implementation to chose if some module relies on it. |
683 | decide which implementation to chose if some module relies on it. |
450 | |
684 | |
451 | If the main program relies on a specific event model. For example, in |
685 | If the main program relies on a specific event model - for example, in |
452 | Gtk2 programs you have to rely on the Glib module. You should load the |
686 | Gtk2 programs you have to rely on the Glib module - you should load the |
453 | event module before loading AnyEvent or any module that uses it: generally |
687 | event module before loading AnyEvent or any module that uses it: generally |
454 | speaking, you should load it as early as possible. The reason is that |
688 | speaking, you should load it as early as possible. The reason is that |
455 | modules might create watchers when they are loaded, and AnyEvent will |
689 | modules might create watchers when they are loaded, and AnyEvent will |
456 | decide on the event model to use as soon as it creates watchers, and it |
690 | decide on the event model to use as soon as it creates watchers, and it |
457 | might chose the wrong one unless you load the correct one yourself. |
691 | might chose the wrong one unless you load the correct one yourself. |
458 | |
692 | |
459 | You can chose to use a rather inefficient pure-perl implementation by |
693 | You can chose to use a pure-perl implementation by loading the |
460 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
694 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
461 | behaviour everywhere, but letting AnyEvent chose is generally better. |
695 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
696 | |
|
|
697 | =head2 MAINLOOP EMULATION |
|
|
698 | |
|
|
699 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
700 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
701 | |
|
|
702 | In that case, you can use a condition variable like this: |
|
|
703 | |
|
|
704 | AnyEvent->condvar->recv; |
|
|
705 | |
|
|
706 | This has the effect of entering the event loop and looping forever. |
|
|
707 | |
|
|
708 | Note that usually your program has some exit condition, in which case |
|
|
709 | it is better to use the "traditional" approach of storing a condition |
|
|
710 | variable somewhere, waiting for it, and sending it when the program should |
|
|
711 | exit cleanly. |
|
|
712 | |
|
|
713 | |
|
|
714 | =head1 OTHER MODULES |
|
|
715 | |
|
|
716 | The following is a non-exhaustive list of additional modules that use |
|
|
717 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
718 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
719 | available via CPAN. |
|
|
720 | |
|
|
721 | =over 4 |
|
|
722 | |
|
|
723 | =item L<AnyEvent::Util> |
|
|
724 | |
|
|
725 | Contains various utility functions that replace often-used but blocking |
|
|
726 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
727 | |
|
|
728 | =item L<AnyEvent::Handle> |
|
|
729 | |
|
|
730 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
731 | |
|
|
732 | =item L<AnyEvent::Socket> |
|
|
733 | |
|
|
734 | Provides various utility functions for (internet protocol) sockets, |
|
|
735 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
736 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
737 | |
|
|
738 | =item L<AnyEvent::DNS> |
|
|
739 | |
|
|
740 | Provides rich asynchronous DNS resolver capabilities. |
|
|
741 | |
|
|
742 | =item L<AnyEvent::HTTPD> |
|
|
743 | |
|
|
744 | Provides a simple web application server framework. |
|
|
745 | |
|
|
746 | =item L<AnyEvent::FastPing> |
|
|
747 | |
|
|
748 | The fastest ping in the west. |
|
|
749 | |
|
|
750 | =item L<Net::IRC3> |
|
|
751 | |
|
|
752 | AnyEvent based IRC client module family. |
|
|
753 | |
|
|
754 | =item L<Net::XMPP2> |
|
|
755 | |
|
|
756 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
757 | |
|
|
758 | =item L<Net::FCP> |
|
|
759 | |
|
|
760 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
761 | of AnyEvent. |
|
|
762 | |
|
|
763 | =item L<Event::ExecFlow> |
|
|
764 | |
|
|
765 | High level API for event-based execution flow control. |
|
|
766 | |
|
|
767 | =item L<Coro> |
|
|
768 | |
|
|
769 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
770 | |
|
|
771 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
772 | |
|
|
773 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
774 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
775 | together. |
|
|
776 | |
|
|
777 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
778 | |
|
|
779 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
780 | IO::AIO and AnyEvent together. |
|
|
781 | |
|
|
782 | =item L<IO::Lambda> |
|
|
783 | |
|
|
784 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
785 | |
|
|
786 | =back |
462 | |
787 | |
463 | =cut |
788 | =cut |
464 | |
789 | |
465 | package AnyEvent; |
790 | package AnyEvent; |
466 | |
791 | |
467 | no warnings; |
792 | no warnings; |
468 | use strict; |
793 | use strict; |
469 | |
794 | |
470 | use Carp; |
795 | use Carp; |
471 | |
796 | |
472 | our $VERSION = '3.3'; |
797 | our $VERSION = '4.05'; |
473 | our $MODEL; |
798 | our $MODEL; |
474 | |
799 | |
475 | our $AUTOLOAD; |
800 | our $AUTOLOAD; |
476 | our @ISA; |
801 | our @ISA; |
477 | |
802 | |
|
|
803 | our @REGISTRY; |
|
|
804 | |
|
|
805 | our $WIN32; |
|
|
806 | |
|
|
807 | BEGIN { |
|
|
808 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
809 | eval "sub WIN32(){ $win32 }"; |
|
|
810 | } |
|
|
811 | |
478 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
812 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
479 | |
813 | |
480 | our @REGISTRY; |
814 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
815 | |
|
|
816 | { |
|
|
817 | my $idx; |
|
|
818 | $PROTOCOL{$_} = ++$idx |
|
|
819 | for reverse split /\s*,\s*/, |
|
|
820 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
821 | } |
481 | |
822 | |
482 | my @models = ( |
823 | my @models = ( |
483 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
484 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
485 | [EV:: => AnyEvent::Impl::EV::], |
824 | [EV:: => AnyEvent::Impl::EV::], |
486 | [Event:: => AnyEvent::Impl::Event::], |
825 | [Event:: => AnyEvent::Impl::Event::], |
487 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
488 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
489 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
490 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
491 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
826 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
492 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
827 | # everything below here will not be autoprobed |
|
|
828 | # as the pureperl backend should work everywhere |
|
|
829 | # and is usually faster |
|
|
830 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
831 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
493 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
832 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
494 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
833 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
495 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
834 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
835 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
836 | [Prima:: => AnyEvent::Impl::POE::], |
496 | ); |
837 | ); |
497 | |
838 | |
498 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
839 | our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); |
|
|
840 | |
|
|
841 | our @post_detect; |
|
|
842 | |
|
|
843 | sub post_detect(&) { |
|
|
844 | my ($cb) = @_; |
|
|
845 | |
|
|
846 | if ($MODEL) { |
|
|
847 | $cb->(); |
|
|
848 | |
|
|
849 | 1 |
|
|
850 | } else { |
|
|
851 | push @post_detect, $cb; |
|
|
852 | |
|
|
853 | defined wantarray |
|
|
854 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
855 | : () |
|
|
856 | } |
|
|
857 | } |
|
|
858 | |
|
|
859 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
860 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
861 | } |
499 | |
862 | |
500 | sub detect() { |
863 | sub detect() { |
501 | unless ($MODEL) { |
864 | unless ($MODEL) { |
502 | no strict 'refs'; |
865 | no strict 'refs'; |
|
|
866 | local $SIG{__DIE__}; |
503 | |
867 | |
504 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
868 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
505 | my $model = "AnyEvent::Impl::$1"; |
869 | my $model = "AnyEvent::Impl::$1"; |
506 | if (eval "require $model") { |
870 | if (eval "require $model") { |
507 | $MODEL = $model; |
871 | $MODEL = $model; |
… | |
… | |
537 | last; |
901 | last; |
538 | } |
902 | } |
539 | } |
903 | } |
540 | |
904 | |
541 | $MODEL |
905 | $MODEL |
542 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
906 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
543 | } |
907 | } |
544 | } |
908 | } |
545 | |
909 | |
546 | unshift @ISA, $MODEL; |
910 | unshift @ISA, $MODEL; |
547 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
911 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
912 | |
|
|
913 | (shift @post_detect)->() while @post_detect; |
548 | } |
914 | } |
549 | |
915 | |
550 | $MODEL |
916 | $MODEL |
551 | } |
917 | } |
552 | |
918 | |
… | |
… | |
562 | $class->$func (@_); |
928 | $class->$func (@_); |
563 | } |
929 | } |
564 | |
930 | |
565 | package AnyEvent::Base; |
931 | package AnyEvent::Base; |
566 | |
932 | |
|
|
933 | # default implementation for now and time |
|
|
934 | |
|
|
935 | use Time::HiRes (); |
|
|
936 | |
|
|
937 | sub time { Time::HiRes::time } |
|
|
938 | sub now { Time::HiRes::time } |
|
|
939 | |
567 | # default implementation for ->condvar, ->wait, ->broadcast |
940 | # default implementation for ->condvar |
568 | |
941 | |
569 | sub condvar { |
942 | sub condvar { |
570 | bless \my $flag, "AnyEvent::Base::CondVar" |
943 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
571 | } |
|
|
572 | |
|
|
573 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
574 | ${$_[0]}++; |
|
|
575 | } |
|
|
576 | |
|
|
577 | sub AnyEvent::Base::CondVar::wait { |
|
|
578 | AnyEvent->one_event while !${$_[0]}; |
|
|
579 | } |
944 | } |
580 | |
945 | |
581 | # default implementation for ->signal |
946 | # default implementation for ->signal |
582 | |
947 | |
583 | our %SIG_CB; |
948 | our %SIG_CB; |
… | |
… | |
636 | or Carp::croak "required option 'pid' is missing"; |
1001 | or Carp::croak "required option 'pid' is missing"; |
637 | |
1002 | |
638 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1003 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
639 | |
1004 | |
640 | unless ($WNOHANG) { |
1005 | unless ($WNOHANG) { |
641 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
1006 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
642 | } |
1007 | } |
643 | |
1008 | |
644 | unless ($CHLD_W) { |
1009 | unless ($CHLD_W) { |
645 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
1010 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
646 | # child could be a zombie already, so make at least one round |
1011 | # child could be a zombie already, so make at least one round |
… | |
… | |
656 | delete $PID_CB{$pid}{$cb}; |
1021 | delete $PID_CB{$pid}{$cb}; |
657 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1022 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
658 | |
1023 | |
659 | undef $CHLD_W unless keys %PID_CB; |
1024 | undef $CHLD_W unless keys %PID_CB; |
660 | } |
1025 | } |
|
|
1026 | |
|
|
1027 | package AnyEvent::CondVar; |
|
|
1028 | |
|
|
1029 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1030 | |
|
|
1031 | package AnyEvent::CondVar::Base; |
|
|
1032 | |
|
|
1033 | use overload |
|
|
1034 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1035 | fallback => 1; |
|
|
1036 | |
|
|
1037 | sub _send { |
|
|
1038 | # nop |
|
|
1039 | } |
|
|
1040 | |
|
|
1041 | sub send { |
|
|
1042 | my $cv = shift; |
|
|
1043 | $cv->{_ae_sent} = [@_]; |
|
|
1044 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1045 | $cv->_send; |
|
|
1046 | } |
|
|
1047 | |
|
|
1048 | sub croak { |
|
|
1049 | $_[0]{_ae_croak} = $_[1]; |
|
|
1050 | $_[0]->send; |
|
|
1051 | } |
|
|
1052 | |
|
|
1053 | sub ready { |
|
|
1054 | $_[0]{_ae_sent} |
|
|
1055 | } |
|
|
1056 | |
|
|
1057 | sub _wait { |
|
|
1058 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1059 | } |
|
|
1060 | |
|
|
1061 | sub recv { |
|
|
1062 | $_[0]->_wait; |
|
|
1063 | |
|
|
1064 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1065 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1066 | } |
|
|
1067 | |
|
|
1068 | sub cb { |
|
|
1069 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1070 | $_[0]{_ae_cb} |
|
|
1071 | } |
|
|
1072 | |
|
|
1073 | sub begin { |
|
|
1074 | ++$_[0]{_ae_counter}; |
|
|
1075 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1076 | } |
|
|
1077 | |
|
|
1078 | sub end { |
|
|
1079 | return if --$_[0]{_ae_counter}; |
|
|
1080 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1081 | } |
|
|
1082 | |
|
|
1083 | # undocumented/compatibility with pre-3.4 |
|
|
1084 | *broadcast = \&send; |
|
|
1085 | *wait = \&_wait; |
661 | |
1086 | |
662 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1087 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
663 | |
1088 | |
664 | This is an advanced topic that you do not normally need to use AnyEvent in |
1089 | This is an advanced topic that you do not normally need to use AnyEvent in |
665 | a module. This section is only of use to event loop authors who want to |
1090 | a module. This section is only of use to event loop authors who want to |
… | |
… | |
722 | model it chooses. |
1147 | model it chooses. |
723 | |
1148 | |
724 | =item C<PERL_ANYEVENT_MODEL> |
1149 | =item C<PERL_ANYEVENT_MODEL> |
725 | |
1150 | |
726 | This can be used to specify the event model to be used by AnyEvent, before |
1151 | This can be used to specify the event model to be used by AnyEvent, before |
727 | autodetection and -probing kicks in. It must be a string consisting |
1152 | auto detection and -probing kicks in. It must be a string consisting |
728 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
1153 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
729 | and the resulting module name is loaded and if the load was successful, |
1154 | and the resulting module name is loaded and if the load was successful, |
730 | used as event model. If it fails to load AnyEvent will proceed with |
1155 | used as event model. If it fails to load AnyEvent will proceed with |
731 | autodetection and -probing. |
1156 | auto detection and -probing. |
732 | |
1157 | |
733 | This functionality might change in future versions. |
1158 | This functionality might change in future versions. |
734 | |
1159 | |
735 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
1160 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
736 | could start your program like this: |
1161 | could start your program like this: |
737 | |
1162 | |
738 | PERL_ANYEVENT_MODEL=Perl perl ... |
1163 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1164 | |
|
|
1165 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1166 | |
|
|
1167 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1168 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1169 | of auto probing). |
|
|
1170 | |
|
|
1171 | Must be set to a comma-separated list of protocols or address families, |
|
|
1172 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1173 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1174 | list. |
|
|
1175 | |
|
|
1176 | This variable can effectively be used for denial-of-service attacks |
|
|
1177 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1178 | small, as the program has to handle connection errors already- |
|
|
1179 | |
|
|
1180 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1181 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1182 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1183 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1184 | IPv6, but prefer IPv6 over IPv4. |
|
|
1185 | |
|
|
1186 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1187 | |
|
|
1188 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1189 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1190 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1191 | default. |
|
|
1192 | |
|
|
1193 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1194 | EDNS0 in its DNS requests. |
|
|
1195 | |
|
|
1196 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1197 | |
|
|
1198 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1199 | will create in parallel. |
739 | |
1200 | |
740 | =back |
1201 | =back |
741 | |
1202 | |
742 | =head1 EXAMPLE PROGRAM |
1203 | =head1 EXAMPLE PROGRAM |
743 | |
1204 | |
… | |
… | |
754 | poll => 'r', |
1215 | poll => 'r', |
755 | cb => sub { |
1216 | cb => sub { |
756 | warn "io event <$_[0]>\n"; # will always output <r> |
1217 | warn "io event <$_[0]>\n"; # will always output <r> |
757 | chomp (my $input = <STDIN>); # read a line |
1218 | chomp (my $input = <STDIN>); # read a line |
758 | warn "read: $input\n"; # output what has been read |
1219 | warn "read: $input\n"; # output what has been read |
759 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1220 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
760 | }, |
1221 | }, |
761 | ); |
1222 | ); |
762 | |
1223 | |
763 | my $time_watcher; # can only be used once |
1224 | my $time_watcher; # can only be used once |
764 | |
1225 | |
… | |
… | |
769 | }); |
1230 | }); |
770 | } |
1231 | } |
771 | |
1232 | |
772 | new_timer; # create first timer |
1233 | new_timer; # create first timer |
773 | |
1234 | |
774 | $cv->wait; # wait until user enters /^q/i |
1235 | $cv->recv; # wait until user enters /^q/i |
775 | |
1236 | |
776 | =head1 REAL-WORLD EXAMPLE |
1237 | =head1 REAL-WORLD EXAMPLE |
777 | |
1238 | |
778 | Consider the L<Net::FCP> module. It features (among others) the following |
1239 | Consider the L<Net::FCP> module. It features (among others) the following |
779 | API calls, which are to freenet what HTTP GET requests are to http: |
1240 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
829 | syswrite $txn->{fh}, $txn->{request} |
1290 | syswrite $txn->{fh}, $txn->{request} |
830 | or die "connection or write error"; |
1291 | or die "connection or write error"; |
831 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1292 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
832 | |
1293 | |
833 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1294 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
834 | result and signals any possible waiters that the request ahs finished: |
1295 | result and signals any possible waiters that the request has finished: |
835 | |
1296 | |
836 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1297 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
837 | |
1298 | |
838 | if (end-of-file or data complete) { |
1299 | if (end-of-file or data complete) { |
839 | $txn->{result} = $txn->{buf}; |
1300 | $txn->{result} = $txn->{buf}; |
840 | $txn->{finished}->broadcast; |
1301 | $txn->{finished}->send; |
841 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1302 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
842 | } |
1303 | } |
843 | |
1304 | |
844 | The C<result> method, finally, just waits for the finished signal (if the |
1305 | The C<result> method, finally, just waits for the finished signal (if the |
845 | request was already finished, it doesn't wait, of course, and returns the |
1306 | request was already finished, it doesn't wait, of course, and returns the |
846 | data: |
1307 | data: |
847 | |
1308 | |
848 | $txn->{finished}->wait; |
1309 | $txn->{finished}->recv; |
849 | return $txn->{result}; |
1310 | return $txn->{result}; |
850 | |
1311 | |
851 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1312 | The actual code goes further and collects all errors (C<die>s, exceptions) |
852 | that occured during request processing. The C<result> method detects |
1313 | that occurred during request processing. The C<result> method detects |
853 | whether an exception as thrown (it is stored inside the $txn object) |
1314 | whether an exception as thrown (it is stored inside the $txn object) |
854 | and just throws the exception, which means connection errors and other |
1315 | and just throws the exception, which means connection errors and other |
855 | problems get reported tot he code that tries to use the result, not in a |
1316 | problems get reported tot he code that tries to use the result, not in a |
856 | random callback. |
1317 | random callback. |
857 | |
1318 | |
… | |
… | |
888 | |
1349 | |
889 | my $quit = AnyEvent->condvar; |
1350 | my $quit = AnyEvent->condvar; |
890 | |
1351 | |
891 | $fcp->txn_client_get ($url)->cb (sub { |
1352 | $fcp->txn_client_get ($url)->cb (sub { |
892 | ... |
1353 | ... |
893 | $quit->broadcast; |
1354 | $quit->send; |
894 | }); |
1355 | }); |
895 | |
1356 | |
896 | $quit->wait; |
1357 | $quit->recv; |
897 | |
1358 | |
898 | |
1359 | |
899 | =head1 BENCHMARK |
1360 | =head1 BENCHMARKS |
900 | |
1361 | |
901 | To give you an idea of the performance and overheads that AnyEvent adds |
1362 | To give you an idea of the performance and overheads that AnyEvent adds |
902 | over the event loops themselves (and to give you an impression of the |
1363 | over the event loops themselves and to give you an impression of the speed |
903 | speed of various event loops), here is a benchmark of various supported |
1364 | of various event loops I prepared some benchmarks. |
904 | event models natively and with anyevent. The benchmark creates a lot of |
1365 | |
905 | timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to |
1366 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1367 | |
|
|
1368 | Here is a benchmark of various supported event models used natively and |
|
|
1369 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1370 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
906 | become writable, which it is), lets them fire exactly once and destroys |
1371 | which it is), lets them fire exactly once and destroys them again. |
907 | them again. |
|
|
908 | |
1372 | |
909 | Rewriting the benchmark to use many different sockets instead of using |
1373 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
910 | the same filehandle for all I/O watchers results in a much longer runtime |
1374 | distribution. |
911 | (socket creation is expensive), but qualitatively the same figures, so it |
|
|
912 | was not used. |
|
|
913 | |
1375 | |
914 | =head2 Explanation of the columns |
1376 | =head3 Explanation of the columns |
915 | |
1377 | |
916 | I<watcher> is the number of event watchers created/destroyed. Since |
1378 | I<watcher> is the number of event watchers created/destroyed. Since |
917 | different event models feature vastly different performances, each event |
1379 | different event models feature vastly different performances, each event |
918 | loop was given a number of watchers so that overall runtime is acceptable |
1380 | loop was given a number of watchers so that overall runtime is acceptable |
919 | and similar between tested event loop (and keep them from crashing): Glib |
1381 | and similar between tested event loop (and keep them from crashing): Glib |
… | |
… | |
929 | all watchers, to avoid adding memory overhead. That means closure creation |
1391 | all watchers, to avoid adding memory overhead. That means closure creation |
930 | and memory usage is not included in the figures. |
1392 | and memory usage is not included in the figures. |
931 | |
1393 | |
932 | I<invoke> is the time, in microseconds, used to invoke a simple |
1394 | I<invoke> is the time, in microseconds, used to invoke a simple |
933 | callback. The callback simply counts down a Perl variable and after it was |
1395 | callback. The callback simply counts down a Perl variable and after it was |
934 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
1396 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
935 | signal the end of this phase. |
1397 | signal the end of this phase. |
936 | |
1398 | |
937 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
1399 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
938 | watcher. |
1400 | watcher. |
939 | |
1401 | |
940 | =head2 Results |
1402 | =head3 Results |
941 | |
1403 | |
942 | name watchers bytes create invoke destroy comment |
1404 | name watchers bytes create invoke destroy comment |
943 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1405 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
944 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1406 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
945 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1407 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
946 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1408 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
947 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1409 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
948 | Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers |
1410 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
949 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1411 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
950 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1412 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
951 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1413 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
952 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1414 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
953 | |
1415 | |
954 | =head2 Discussion |
1416 | =head3 Discussion |
955 | |
1417 | |
956 | The benchmark does I<not> measure scalability of the event loop very |
1418 | The benchmark does I<not> measure scalability of the event loop very |
957 | well. For example, a select-based event loop (such as the pure perl one) |
1419 | well. For example, a select-based event loop (such as the pure perl one) |
958 | can never compete with an event loop that uses epoll when the number of |
1420 | can never compete with an event loop that uses epoll when the number of |
959 | file descriptors grows high. In this benchmark, all events become ready at |
1421 | file descriptors grows high. In this benchmark, all events become ready at |
960 | the same time, so select/poll-based implementations get an unnatural speed |
1422 | the same time, so select/poll-based implementations get an unnatural speed |
961 | boost. |
1423 | boost. |
962 | |
1424 | |
|
|
1425 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1426 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1427 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1428 | higher number of watchers at a disadvantage. |
|
|
1429 | |
|
|
1430 | To put the range of results into perspective, consider that on the |
|
|
1431 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1432 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1433 | cycles with POE. |
|
|
1434 | |
963 | C<EV> is the sole leader regarding speed and memory use, which are both |
1435 | C<EV> is the sole leader regarding speed and memory use, which are both |
964 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1436 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
965 | far less memory than any other event loop and is still faster than Event |
1437 | far less memory than any other event loop and is still faster than Event |
966 | natively. |
1438 | natively. |
967 | |
1439 | |
… | |
… | |
970 | interpreter and the backend itself). Nevertheless this shows that it |
1442 | interpreter and the backend itself). Nevertheless this shows that it |
971 | adds very little overhead in itself. Like any select-based backend its |
1443 | adds very little overhead in itself. Like any select-based backend its |
972 | performance becomes really bad with lots of file descriptors (and few of |
1444 | performance becomes really bad with lots of file descriptors (and few of |
973 | them active), of course, but this was not subject of this benchmark. |
1445 | them active), of course, but this was not subject of this benchmark. |
974 | |
1446 | |
975 | The C<Event> module has a relatively high setup and callback invocation cost, |
1447 | The C<Event> module has a relatively high setup and callback invocation |
976 | but overall scores on the third place. |
1448 | cost, but overall scores in on the third place. |
977 | |
1449 | |
978 | C<Glib>'s memory usage is quite a bit bit higher, but it features a |
1450 | C<Glib>'s memory usage is quite a bit higher, but it features a |
979 | faster callback invocation and overall ends up in the same class as |
1451 | faster callback invocation and overall ends up in the same class as |
980 | C<Event>. However, Glib scales extremely badly, doubling the number of |
1452 | C<Event>. However, Glib scales extremely badly, doubling the number of |
981 | watchers increases the processing time by more than a factor of four, |
1453 | watchers increases the processing time by more than a factor of four, |
982 | making it completely unusable when using larger numbers of watchers |
1454 | making it completely unusable when using larger numbers of watchers |
983 | (note that only a single file descriptor was used in the benchmark, so |
1455 | (note that only a single file descriptor was used in the benchmark, so |
… | |
… | |
989 | file descriptor is dup()ed for each watcher. This shows that the dup() |
1461 | file descriptor is dup()ed for each watcher. This shows that the dup() |
990 | employed by some adaptors is not a big performance issue (it does incur a |
1462 | employed by some adaptors is not a big performance issue (it does incur a |
991 | hidden memory cost inside the kernel which is not reflected in the figures |
1463 | hidden memory cost inside the kernel which is not reflected in the figures |
992 | above). |
1464 | above). |
993 | |
1465 | |
994 | C<POE>, regardless of underlying event loop (whether using its pure |
1466 | C<POE>, regardless of underlying event loop (whether using its pure perl |
995 | perl select-based backend or the Event module, the POE-EV backend |
1467 | select-based backend or the Event module, the POE-EV backend couldn't |
996 | couldn't be tested because it wasn't working) shows abysmal performance |
1468 | be tested because it wasn't working) shows abysmal performance and |
997 | and memory usage: Watchers use almost 30 times as much memory as |
1469 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
998 | EV watchers, and 10 times as much memory as Event (the high memory |
1470 | as EV watchers, and 10 times as much memory as Event (the high memory |
999 | requirements are caused by requiring a session for each watcher). Watcher |
1471 | requirements are caused by requiring a session for each watcher). Watcher |
1000 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
1472 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1473 | implementation. |
|
|
1474 | |
1001 | implementation. The design of the POE adaptor class in AnyEvent can not |
1475 | The design of the POE adaptor class in AnyEvent can not really account |
1002 | really account for this, as session creation overhead is small compared |
1476 | for the performance issues, though, as session creation overhead is |
1003 | to execution of the state machine, which is coded pretty optimally within |
1477 | small compared to execution of the state machine, which is coded pretty |
1004 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
1478 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1479 | using multiple sessions is not a good approach, especially regarding |
|
|
1480 | memory usage, even the author of POE could not come up with a faster |
|
|
1481 | design). |
1005 | |
1482 | |
1006 | =head2 Summary |
1483 | =head3 Summary |
1007 | |
1484 | |
1008 | =over 4 |
1485 | =over 4 |
1009 | |
1486 | |
1010 | =item * Using EV through AnyEvent is faster than any other event loop |
1487 | =item * Using EV through AnyEvent is faster than any other event loop |
1011 | (even when used without AnyEvent), but most event loops have acceptable |
1488 | (even when used without AnyEvent), but most event loops have acceptable |
… | |
… | |
1013 | |
1490 | |
1014 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
1491 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
1015 | the actual event loop, only with extremely fast event loops such as EV |
1492 | the actual event loop, only with extremely fast event loops such as EV |
1016 | adds AnyEvent significant overhead. |
1493 | adds AnyEvent significant overhead. |
1017 | |
1494 | |
1018 | =item * You should simply avoid POE like the plague if you want performance or |
1495 | =item * You should avoid POE like the plague if you want performance or |
1019 | reasonable memory usage. |
1496 | reasonable memory usage. |
1020 | |
1497 | |
1021 | =back |
1498 | =back |
1022 | |
1499 | |
|
|
1500 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1501 | |
|
|
1502 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1503 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1504 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1505 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1506 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1507 | |
|
|
1508 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1509 | are active at any one point (so there is a constant number of active |
|
|
1510 | fds for each loop iteration, but which fds these are is random). The |
|
|
1511 | timeout is reset each time something is read because that reflects how |
|
|
1512 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1513 | |
|
|
1514 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1515 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1516 | connections, most of which are idle at any one point in time. |
|
|
1517 | |
|
|
1518 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1519 | distribution. |
|
|
1520 | |
|
|
1521 | =head3 Explanation of the columns |
|
|
1522 | |
|
|
1523 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1524 | each server has a read and write socket end). |
|
|
1525 | |
|
|
1526 | I<create> is the time it takes to create a socket pair (which is |
|
|
1527 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1528 | |
|
|
1529 | I<request>, the most important value, is the time it takes to handle a |
|
|
1530 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1531 | it to another server. This includes deleting the old timeout and creating |
|
|
1532 | a new one that moves the timeout into the future. |
|
|
1533 | |
|
|
1534 | =head3 Results |
|
|
1535 | |
|
|
1536 | name sockets create request |
|
|
1537 | EV 20000 69.01 11.16 |
|
|
1538 | Perl 20000 73.32 35.87 |
|
|
1539 | Event 20000 212.62 257.32 |
|
|
1540 | Glib 20000 651.16 1896.30 |
|
|
1541 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1542 | |
|
|
1543 | =head3 Discussion |
|
|
1544 | |
|
|
1545 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1546 | particular event loop. |
|
|
1547 | |
|
|
1548 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1549 | is relatively high, though. |
|
|
1550 | |
|
|
1551 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1552 | loops Event and Glib. |
|
|
1553 | |
|
|
1554 | Event suffers from high setup time as well (look at its code and you will |
|
|
1555 | understand why). Callback invocation also has a high overhead compared to |
|
|
1556 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1557 | uses select or poll in basically all documented configurations. |
|
|
1558 | |
|
|
1559 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1560 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1561 | |
|
|
1562 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1563 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1564 | it uses a C-based event loop in this case. |
|
|
1565 | |
|
|
1566 | =head3 Summary |
|
|
1567 | |
|
|
1568 | =over 4 |
|
|
1569 | |
|
|
1570 | =item * The pure perl implementation performs extremely well. |
|
|
1571 | |
|
|
1572 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1573 | |
|
|
1574 | =back |
|
|
1575 | |
|
|
1576 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1577 | |
|
|
1578 | While event loops should scale (and select-based ones do not...) even to |
|
|
1579 | large servers, most programs we (or I :) actually write have only a few |
|
|
1580 | I/O watchers. |
|
|
1581 | |
|
|
1582 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1583 | case, but it uses only eight "servers", of which three are active at any |
|
|
1584 | one time. This should reflect performance for a small server relatively |
|
|
1585 | well. |
|
|
1586 | |
|
|
1587 | The columns are identical to the previous table. |
|
|
1588 | |
|
|
1589 | =head3 Results |
|
|
1590 | |
|
|
1591 | name sockets create request |
|
|
1592 | EV 16 20.00 6.54 |
|
|
1593 | Perl 16 25.75 12.62 |
|
|
1594 | Event 16 81.27 35.86 |
|
|
1595 | Glib 16 32.63 15.48 |
|
|
1596 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1597 | |
|
|
1598 | =head3 Discussion |
|
|
1599 | |
|
|
1600 | The benchmark tries to test the performance of a typical small |
|
|
1601 | server. While knowing how various event loops perform is interesting, keep |
|
|
1602 | in mind that their overhead in this case is usually not as important, due |
|
|
1603 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1604 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1605 | them). |
|
|
1606 | |
|
|
1607 | EV is again fastest. |
|
|
1608 | |
|
|
1609 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1610 | loops Event and Glib, although the difference is too small to really |
|
|
1611 | matter. |
|
|
1612 | |
|
|
1613 | POE also performs much better in this case, but is is still far behind the |
|
|
1614 | others. |
|
|
1615 | |
|
|
1616 | =head3 Summary |
|
|
1617 | |
|
|
1618 | =over 4 |
|
|
1619 | |
|
|
1620 | =item * C-based event loops perform very well with small number of |
|
|
1621 | watchers, as the management overhead dominates. |
|
|
1622 | |
|
|
1623 | =back |
|
|
1624 | |
1023 | |
1625 | |
1024 | =head1 FORK |
1626 | =head1 FORK |
1025 | |
1627 | |
1026 | Most event libraries are not fork-safe. The ones who are usually are |
1628 | Most event libraries are not fork-safe. The ones who are usually are |
1027 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1629 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1630 | calls. Only L<EV> is fully fork-aware. |
1028 | |
1631 | |
1029 | If you have to fork, you must either do so I<before> creating your first |
1632 | If you have to fork, you must either do so I<before> creating your first |
1030 | watcher OR you must not use AnyEvent at all in the child. |
1633 | watcher OR you must not use AnyEvent at all in the child. |
1031 | |
1634 | |
1032 | |
1635 | |
… | |
… | |
1044 | |
1647 | |
1045 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1648 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1046 | |
1649 | |
1047 | use AnyEvent; |
1650 | use AnyEvent; |
1048 | |
1651 | |
|
|
1652 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1653 | be used to probe what backend is used and gain other information (which is |
|
|
1654 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1655 | |
1049 | |
1656 | |
1050 | =head1 SEE ALSO |
1657 | =head1 SEE ALSO |
1051 | |
1658 | |
1052 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1659 | Utility functions: L<AnyEvent::Util>. |
1053 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
1660 | |
|
|
1661 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
1054 | L<Event::Lib>, L<Qt>, L<POE>. |
1662 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
1055 | |
1663 | |
1056 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1664 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
1057 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
1665 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
1058 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
1666 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
1059 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
1667 | L<AnyEvent::Impl::POE>. |
1060 | |
1668 | |
|
|
1669 | Non-blocking file handles, sockets, TCP clients and |
|
|
1670 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1671 | |
|
|
1672 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1673 | |
|
|
1674 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1675 | |
1061 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1676 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
1062 | |
1677 | |
1063 | |
1678 | |
1064 | =head1 AUTHOR |
1679 | =head1 AUTHOR |
1065 | |
1680 | |
1066 | Marc Lehmann <schmorp@schmorp.de> |
1681 | Marc Lehmann <schmorp@schmorp.de> |