1 | NAME |
1 | => NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - provide framework for multiple event loops |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
5 | loops |
5 | loops |
6 | |
6 | |
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46 | that isn't itself. What's worse, all the potential users of your module |
46 | that isn't itself. What's worse, all the potential users of your module |
47 | are *also* forced to use the same event loop you use. |
47 | are *also* forced to use the same event loop you use. |
48 | |
48 | |
49 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
49 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
50 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if your |
51 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
52 | module uses one of those, every user of your module has to use it, too. |
52 | module uses one of those, every user of your module has to use it, too. |
53 | But if your module uses AnyEvent, it works transparently with all event |
53 | But if your module uses AnyEvent, it works transparently with all event |
54 | models it supports (including stuff like POE and IO::Async, as long as |
54 | models it supports (including stuff like POE and IO::Async, as long as |
55 | those use one of the supported event loops. It is trivial to add new |
55 | those use one of the supported event loops. It is trivial to add new |
56 | event loops to AnyEvent, too, so it is future-proof). |
56 | event loops to AnyEvent, too, so it is future-proof). |
57 | |
57 | |
58 | In addition to being free of having to use *the one and only true event |
58 | In addition to being free of having to use *the one and only true event |
59 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
59 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
60 | modules, you get an enourmous amount of code and strict rules you have |
60 | modules, you get an enormous amount of code and strict rules you have to |
61 | to follow. AnyEvent, on the other hand, is lean and up to the point, by |
61 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
62 | only offering the functionality that is necessary, in as thin as a |
62 | only offering the functionality that is necessary, in as thin as a |
63 | wrapper as technically possible. |
63 | wrapper as technically possible. |
64 | |
64 | |
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65 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
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66 | useful functionality, such as an asynchronous DNS resolver, 100% |
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67 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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68 | such as Windows) and lots of real-world knowledge and workarounds for |
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69 | platform bugs and differences. |
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70 | |
65 | Of course, if you want lots of policy (this can arguably be somewhat |
71 | Now, if you *do want* lots of policy (this can arguably be somewhat |
66 | useful) and you want to force your users to use the one and only event |
72 | useful) and you want to force your users to use the one and only event |
67 | model, you should *not* use this module. |
73 | model, you should *not* use this module. |
68 | |
74 | |
69 | DESCRIPTION |
75 | DESCRIPTION |
70 | AnyEvent provides an identical interface to multiple event loops. This |
76 | AnyEvent provides an identical interface to multiple event loops. This |
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99 | starts using it, all bets are off. Maybe you should tell their authors |
105 | starts using it, all bets are off. Maybe you should tell their authors |
100 | to use AnyEvent so their modules work together with others seamlessly... |
106 | to use AnyEvent so their modules work together with others seamlessly... |
101 | |
107 | |
102 | The pure-perl implementation of AnyEvent is called |
108 | The pure-perl implementation of AnyEvent is called |
103 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
109 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
104 | explicitly. |
110 | explicitly and enjoy the high availability of that event loop :) |
105 | |
111 | |
106 | WATCHERS |
112 | WATCHERS |
107 | AnyEvent has the central concept of a *watcher*, which is an object that |
113 | AnyEvent has the central concept of a *watcher*, which is an object that |
108 | stores relevant data for each kind of event you are waiting for, such as |
114 | stores relevant data for each kind of event you are waiting for, such as |
109 | the callback to call, the filehandle to watch, etc. |
115 | the callback to call, the file handle to watch, etc. |
110 | |
116 | |
111 | These watchers are normal Perl objects with normal Perl lifetime. After |
117 | These watchers are normal Perl objects with normal Perl lifetime. After |
112 | creating a watcher it will immediately "watch" for events and invoke the |
118 | creating a watcher it will immediately "watch" for events and invoke the |
113 | callback when the event occurs (of course, only when the event model is |
119 | callback when the event occurs (of course, only when the event model is |
114 | in control). |
120 | in control). |
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220 | on wallclock time) timers. |
226 | on wallclock time) timers. |
221 | |
227 | |
222 | AnyEvent always prefers relative timers, if available, matching the |
228 | AnyEvent always prefers relative timers, if available, matching the |
223 | AnyEvent API. |
229 | AnyEvent API. |
224 | |
230 | |
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231 | AnyEvent has two additional methods that return the "current time": |
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232 | |
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233 | AnyEvent->time |
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234 | This returns the "current wallclock time" as a fractional number of |
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235 | seconds since the Epoch (the same thing as "time" or |
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236 | "Time::HiRes::time" return, and the result is guaranteed to be |
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237 | compatible with those). |
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238 | |
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239 | It progresses independently of any event loop processing, i.e. each |
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240 | call will check the system clock, which usually gets updated |
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241 | frequently. |
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242 | |
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243 | AnyEvent->now |
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244 | This also returns the "current wallclock time", but unlike "time", |
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245 | above, this value might change only once per event loop iteration, |
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246 | depending on the event loop (most return the same time as "time", |
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247 | above). This is the time that AnyEvent's timers get scheduled |
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248 | against. |
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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 |
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251 | function to call when you want to know the current time.* |
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252 | |
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253 | This function is also often faster then "AnyEvent->time", and thus |
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254 | the preferred method if you want some timestamp (for example, |
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255 | AnyEvent::Handle uses this to update it's activity timeouts). |
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256 | |
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257 | The rest of this section is only of relevance if you try to be very |
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258 | exact with your timing, you can skip it without bad conscience. |
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259 | |
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260 | For a practical example of when these times differ, consider |
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261 | Event::Lib and 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 |
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264 | at time=500 (assume no other callbacks delay processing). In your |
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265 | callback, you wait a second by executing "sleep 1" (blocking the |
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266 | process for a second) and then (at time=501) you create a relative |
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267 | timer that fires after three seconds. |
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268 | |
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269 | With Event::Lib, "AnyEvent->time" and "AnyEvent->now" will both |
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270 | return 501, because that is the current time, and the timer will be |
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271 | scheduled to fire at time=504 (501 + 3). |
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272 | |
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273 | With EV, "AnyEvent->time" returns 501 (as that is the current time), |
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274 | but "AnyEvent->now" returns 500, as that is the time the last event |
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275 | processing phase started. With EV, your timer gets scheduled to run |
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276 | at time=503 (500 + 3). |
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277 | |
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278 | In one sense, 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, |
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280 | most callbacks do not expect large delays in processing, so this |
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281 | causes a higher drift (and a lot more system calls to get the |
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282 | current time). |
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283 | |
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284 | In another sense, EV is more exact, as your timer will be scheduled |
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285 | at the same time, regardless of how long event processing actually |
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286 | took. |
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287 | |
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288 | In either case, if you care (and in most cases, you don't), then you |
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289 | can get whatever behaviour you want with any event loop, by taking |
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290 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
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291 | account. |
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292 | |
225 | SIGNAL WATCHERS |
293 | SIGNAL WATCHERS |
226 | You can watch for signals using a signal watcher, "signal" is the signal |
294 | You can watch for signals using a signal watcher, "signal" is the signal |
227 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
295 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
228 | whenever a signal occurs. |
296 | whenever a signal occurs. |
229 | |
297 | |
230 | Although the callback might get passed parameters, their value and |
298 | Although the callback might get passed parameters, their value and |
231 | presence is undefined and you cannot rely on them. Portable AnyEvent |
299 | presence is undefined and you cannot rely on them. Portable AnyEvent |
232 | callbacks cannot use arguments passed to signal watcher callbacks. |
300 | callbacks cannot use arguments passed to signal watcher callbacks. |
233 | |
301 | |
234 | Multiple signal occurances can be clumped together into one callback |
302 | Multiple signal occurrences can be clumped together into one callback |
235 | invocation, and callback invocation will be synchronous. synchronous |
303 | invocation, and callback invocation will be synchronous. Synchronous |
236 | means that it might take a while until the signal gets handled by the |
304 | means that it might take a while until the signal gets handled by the |
237 | process, but it is guarenteed not to interrupt any other callbacks. |
305 | process, but it is guaranteed not to interrupt any other callbacks. |
238 | |
306 | |
239 | The main advantage of using these watchers is that you can share a |
307 | The main advantage of using these watchers is that you can share a |
240 | signal between multiple watchers. |
308 | signal between multiple watchers. |
241 | |
309 | |
242 | This watcher might use %SIG, so programs overwriting those signals |
310 | This watcher might use %SIG, so programs overwriting those signals |
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301 | Condition variables can be created by calling the "AnyEvent->condvar" |
369 | Condition variables can be created by calling the "AnyEvent->condvar" |
302 | method, usually without arguments. The only argument pair allowed is |
370 | method, usually without arguments. The only argument pair allowed is |
303 | "cb", which specifies a callback to be called when the condition |
371 | "cb", which specifies a callback to be called when the condition |
304 | variable becomes true. |
372 | variable becomes true. |
305 | |
373 | |
306 | After creation, the conditon variable is "false" until it becomes "true" |
374 | After creation, the condition variable is "false" until it becomes |
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375 | "true" by calling the "send" method (or calling the condition variable |
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376 | as if it were a callback, read about the caveats in the description for |
307 | by calling the "send" method. |
377 | the "->send" method). |
308 | |
378 | |
309 | Condition variables are similar to callbacks, except that you can |
379 | Condition variables are similar to callbacks, except that you can |
310 | optionally wait for them. They can also be called merge points - points |
380 | optionally wait for them. They can also be called merge points - points |
311 | in time where multiple outstandign events have been processed. And yet |
381 | in time where multiple outstanding events have been processed. And yet |
312 | another way to call them is transations - each condition variable can be |
382 | another way to call them is transactions - each condition variable can |
313 | used to represent a transaction, which finishes at some point and |
383 | be used to represent a transaction, which finishes at some point and |
314 | delivers a result. |
384 | delivers a result. |
315 | |
385 | |
316 | Condition variables are very useful to signal that something has |
386 | Condition variables are very useful to signal that something has |
317 | finished, for example, if you write a module that does asynchronous http |
387 | finished, for example, if you write a module that does asynchronous http |
318 | requests, then a condition variable would be the ideal candidate to |
388 | requests, then a condition variable would be the ideal candidate to |
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323 | you can block your main program until an event occurs - for example, you |
393 | you can block your main program until an event occurs - for example, you |
324 | could "->recv" in your main program until the user clicks the Quit |
394 | could "->recv" in your main program until the user clicks the Quit |
325 | button of your app, which would "->send" the "quit" event. |
395 | button of your app, which would "->send" the "quit" event. |
326 | |
396 | |
327 | Note that condition variables recurse into the event loop - if you have |
397 | Note that condition variables recurse into the event loop - if you have |
328 | two pieces of code that call "->recv" in a round-robbin fashion, you |
398 | two pieces of code that call "->recv" in a round-robin fashion, you |
329 | lose. Therefore, condition variables are good to export to your caller, |
399 | lose. Therefore, condition variables are good to export to your caller, |
330 | but you should avoid making a blocking wait yourself, at least in |
400 | but you should avoid making a blocking wait yourself, at least in |
331 | callbacks, as this asks for trouble. |
401 | callbacks, as this asks for trouble. |
332 | |
402 | |
333 | Condition variables are represented by hash refs in perl, and the keys |
403 | Condition variables are represented by hash refs in perl, and the keys |
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338 | |
408 | |
339 | There are two "sides" to a condition variable - the "producer side" |
409 | There are two "sides" to a condition variable - the "producer side" |
340 | which eventually calls "-> send", and the "consumer side", which waits |
410 | which eventually calls "-> send", and the "consumer side", which waits |
341 | for the send to occur. |
411 | for the send to occur. |
342 | |
412 | |
343 | Example: |
413 | Example: wait for a timer. |
344 | |
414 | |
345 | # wait till the result is ready |
415 | # wait till the result is ready |
346 | my $result_ready = AnyEvent->condvar; |
416 | my $result_ready = AnyEvent->condvar; |
347 | |
417 | |
348 | # do something such as adding a timer |
418 | # do something such as adding a timer |
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356 | |
426 | |
357 | # this "blocks" (while handling events) till the callback |
427 | # this "blocks" (while handling events) till the callback |
358 | # calls send |
428 | # calls send |
359 | $result_ready->recv; |
429 | $result_ready->recv; |
360 | |
430 | |
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431 | Example: wait for a timer, but take advantage of the fact that condition |
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432 | variables are also code references. |
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433 | |
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434 | my $done = AnyEvent->condvar; |
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435 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
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436 | $done->recv; |
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437 | |
361 | METHODS FOR PRODUCERS |
438 | METHODS FOR PRODUCERS |
362 | These methods should only be used by the producing side, i.e. the |
439 | These methods should only be used by the producing side, i.e. the |
363 | code/module that eventually sends the signal. Note that it is also the |
440 | code/module that eventually sends the signal. Note that it is also the |
364 | producer side which creates the condvar in most cases, but it isn't |
441 | producer side which creates the condvar in most cases, but it isn't |
365 | uncommon for the consumer to create it as well. |
442 | uncommon for the consumer to create it as well. |
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372 | If a callback has been set on the condition variable, it is called |
449 | If a callback has been set on the condition variable, it is called |
373 | immediately from within send. |
450 | immediately from within send. |
374 | |
451 | |
375 | Any arguments passed to the "send" call will be returned by all |
452 | Any arguments passed to the "send" call will be returned by all |
376 | future "->recv" calls. |
453 | future "->recv" calls. |
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454 | |
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455 | Condition variables are overloaded so one can call them directly (as |
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456 | a code reference). Calling them directly is the same as calling |
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457 | "send". Note, however, that many C-based event loops do not handle |
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458 | overloading, so as tempting as it may be, passing a condition |
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459 | variable instead of a callback does not work. Both the pure perl and |
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460 | EV loops support overloading, however, as well as all functions that |
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461 | use perl to invoke a callback (as in AnyEvent::Socket and |
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462 | AnyEvent::DNS for example). |
377 | |
463 | |
378 | $cv->croak ($error) |
464 | $cv->croak ($error) |
379 | Similar to send, but causes all call's to "->recv" to invoke |
465 | Similar to send, but causes all call's to "->recv" to invoke |
380 | "Carp::croak" with the given error message/object/scalar. |
466 | "Carp::croak" with the given error message/object/scalar. |
381 | |
467 | |
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427 | (the loop doesn't execute once). |
513 | (the loop doesn't execute once). |
428 | |
514 | |
429 | This is the general pattern when you "fan out" into multiple |
515 | This is the general pattern when you "fan out" into multiple |
430 | subrequests: use an outer "begin"/"end" pair to set the callback and |
516 | subrequests: use an outer "begin"/"end" pair to set the callback and |
431 | ensure "end" is called at least once, and then, for each subrequest |
517 | ensure "end" is called at least once, and then, for each subrequest |
432 | you start, call "begin" and for eahc subrequest you finish, call |
518 | you start, call "begin" and for each subrequest you finish, call |
433 | "end". |
519 | "end". |
434 | |
520 | |
435 | METHODS FOR CONSUMERS |
521 | METHODS FOR CONSUMERS |
436 | These methods should only be used by the consuming side, i.e. the code |
522 | These methods should only be used by the consuming side, i.e. the code |
437 | awaits the condition. |
523 | awaits the condition. |
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453 | (programs might want to do that to stay interactive), so *if you are |
539 | (programs might want to do that to stay interactive), so *if you are |
454 | using this from a module, never require a blocking wait*, but let |
540 | using this from a module, never require a blocking wait*, but let |
455 | the caller decide whether the call will block or not (for example, |
541 | the caller decide whether the call will block or not (for example, |
456 | by coupling condition variables with some kind of request results |
542 | by coupling condition variables with some kind of request results |
457 | and supporting callbacks so the caller knows that getting the result |
543 | and supporting callbacks so the caller knows that getting the result |
458 | will not block, while still suppporting blocking waits if the caller |
544 | will not block, while still supporting blocking waits if the caller |
459 | so desires). |
545 | so desires). |
460 | |
546 | |
461 | Another reason *never* to "->recv" in a module is that you cannot |
547 | Another reason *never* to "->recv" in a module is that you cannot |
462 | sensibly have two "->recv"'s in parallel, as that would require |
548 | sensibly have two "->recv"'s in parallel, as that would require |
463 | multiple interpreters or coroutines/threads, none of which |
549 | multiple interpreters or coroutines/threads, none of which |
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566 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
652 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
567 | do anything special (it does not need to be event-based) and let |
653 | do anything special (it does not need to be event-based) and let |
568 | AnyEvent decide which implementation to chose if some module relies on |
654 | AnyEvent decide which implementation to chose if some module relies on |
569 | it. |
655 | it. |
570 | |
656 | |
571 | If the main program relies on a specific event model. For example, in |
657 | If the main program relies on a specific event model - for example, in |
572 | Gtk2 programs you have to rely on the Glib module. You should load the |
658 | Gtk2 programs you have to rely on the Glib module - you should load the |
573 | event module before loading AnyEvent or any module that uses it: |
659 | event module before loading AnyEvent or any module that uses it: |
574 | generally speaking, you should load it as early as possible. The reason |
660 | generally speaking, you should load it as early as possible. The reason |
575 | is that modules might create watchers when they are loaded, and AnyEvent |
661 | is that modules might create watchers when they are loaded, and AnyEvent |
576 | will decide on the event model to use as soon as it creates watchers, |
662 | will decide on the event model to use as soon as it creates watchers, |
577 | and it might chose the wrong one unless you load the correct one |
663 | and it might chose the wrong one unless you load the correct one |
578 | yourself. |
664 | yourself. |
579 | |
665 | |
580 | You can chose to use a rather inefficient pure-perl implementation by |
666 | You can chose to use a pure-perl implementation by loading the |
581 | loading the "AnyEvent::Impl::Perl" module, which gives you similar |
667 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
582 | behaviour everywhere, but letting AnyEvent chose is generally better. |
668 | everywhere, but letting AnyEvent chose the model is generally better. |
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669 | |
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670 | MAINLOOP EMULATION |
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671 | Sometimes (often for short test scripts, or even standalone programs who |
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672 | only want to use AnyEvent), you do not want to run a specific event |
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673 | loop. |
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674 | |
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675 | In that case, you can use a condition variable like this: |
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676 | |
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677 | AnyEvent->condvar->recv; |
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678 | |
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679 | This has the effect of entering the event loop and looping forever. |
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680 | |
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681 | Note that usually your program has some exit condition, in which case it |
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682 | is better to use the "traditional" approach of storing a condition |
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683 | variable somewhere, waiting for it, and sending it when the program |
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684 | should exit cleanly. |
583 | |
685 | |
584 | OTHER MODULES |
686 | OTHER MODULES |
585 | The following is a non-exhaustive list of additional modules that use |
687 | The following is a non-exhaustive list of additional modules that use |
586 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
688 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
587 | in the same program. Some of the modules come with AnyEvent, some are |
689 | in the same program. Some of the modules come with AnyEvent, some are |
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594 | |
696 | |
595 | AnyEvent::Handle |
697 | AnyEvent::Handle |
596 | Provide read and write buffers and manages watchers for reads and |
698 | Provide read and write buffers and manages watchers for reads and |
597 | writes. |
699 | writes. |
598 | |
700 | |
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701 | AnyEvent::Socket |
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702 | Provides various utility functions for (internet protocol) sockets, |
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703 | addresses and name resolution. Also functions to create non-blocking |
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704 | tcp connections or tcp servers, with IPv6 and SRV record support and |
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705 | more. |
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706 | |
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707 | AnyEvent::DNS |
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708 | Provides rich asynchronous DNS resolver capabilities. |
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709 | |
599 | AnyEvent::HTTPD |
710 | AnyEvent::HTTPD |
600 | Provides a simple web application server framework. |
711 | Provides a simple web application server framework. |
601 | |
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602 | AnyEvent::DNS |
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603 | Provides asynchronous DNS resolver capabilities, beyond what |
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604 | AnyEvent::Util offers. |
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605 | |
712 | |
606 | AnyEvent::FastPing |
713 | AnyEvent::FastPing |
607 | The fastest ping in the west. |
714 | The fastest ping in the west. |
608 | |
715 | |
609 | Net::IRC3 |
716 | Net::IRC3 |
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693 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
800 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
694 | event model it chooses. |
801 | event model it chooses. |
695 | |
802 | |
696 | "PERL_ANYEVENT_MODEL" |
803 | "PERL_ANYEVENT_MODEL" |
697 | This can be used to specify the event model to be used by AnyEvent, |
804 | This can be used to specify the event model to be used by AnyEvent, |
698 | before autodetection and -probing kicks in. It must be a string |
805 | before auto detection and -probing kicks in. It must be a string |
699 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
806 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
700 | gets prepended and the resulting module name is loaded and if the |
807 | gets prepended and the resulting module name is loaded and if the |
701 | load was successful, used as event model. If it fails to load |
808 | load was successful, used as event model. If it fails to load |
702 | AnyEvent will proceed with autodetection and -probing. |
809 | AnyEvent will proceed with auto detection and -probing. |
703 | |
810 | |
704 | This functionality might change in future versions. |
811 | This functionality might change in future versions. |
705 | |
812 | |
706 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
813 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
707 | could start your program like this: |
814 | could start your program like this: |
708 | |
815 | |
709 | PERL_ANYEVENT_MODEL=Perl perl ... |
816 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
817 | |
|
|
818 | "PERL_ANYEVENT_PROTOCOLS" |
|
|
819 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
|
|
820 | preferences for IPv4 or IPv6. The default is unspecified (and might |
|
|
821 | change, or be the result of auto probing). |
|
|
822 | |
|
|
823 | Must be set to a comma-separated list of protocols or address |
|
|
824 | families, current supported: "ipv4" and "ipv6". Only protocols |
|
|
825 | mentioned will be used, and preference will be given to protocols |
|
|
826 | mentioned earlier in the list. |
|
|
827 | |
|
|
828 | This variable can effectively be used for denial-of-service attacks |
|
|
829 | against local programs (e.g. when setuid), although the impact is |
|
|
830 | likely small, as the program has to handle connection errors |
|
|
831 | already- |
|
|
832 | |
|
|
833 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
|
|
834 | IPv6, but support both and try to use both. |
|
|
835 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
|
|
836 | resolve or contact IPv6 addresses. |
|
|
837 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
|
|
838 | prefer IPv6 over IPv4. |
|
|
839 | |
|
|
840 | "PERL_ANYEVENT_EDNS0" |
|
|
841 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
|
|
842 | for DNS. This extension is generally useful to reduce DNS traffic, |
|
|
843 | but some (broken) firewalls drop such DNS packets, which is why it |
|
|
844 | is off by default. |
|
|
845 | |
|
|
846 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
|
|
847 | EDNS0 in its DNS requests. |
|
|
848 | |
|
|
849 | "PERL_ANYEVENT_MAX_FORKS" |
|
|
850 | The maximum number of child processes that |
|
|
851 | "AnyEvent::Util::fork_call" will create in parallel. |
710 | |
852 | |
711 | EXAMPLE PROGRAM |
853 | EXAMPLE PROGRAM |
712 | The following program uses an I/O watcher to read data from STDIN, a |
854 | The following program uses an I/O watcher to read data from STDIN, a |
713 | timer to display a message once per second, and a condition variable to |
855 | timer to display a message once per second, and a condition variable to |
714 | quit the program when the user enters quit: |
856 | quit the program when the user enters quit: |
… | |
… | |
796 | syswrite $txn->{fh}, $txn->{request} |
938 | syswrite $txn->{fh}, $txn->{request} |
797 | or die "connection or write error"; |
939 | or die "connection or write error"; |
798 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
940 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
799 | |
941 | |
800 | Again, "fh_ready_r" waits till all data has arrived, and then stores the |
942 | Again, "fh_ready_r" waits till all data has arrived, and then stores the |
801 | result and signals any possible waiters that the request ahs finished: |
943 | result and signals any possible waiters that the request has finished: |
802 | |
944 | |
803 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
945 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
804 | |
946 | |
805 | if (end-of-file or data complete) { |
947 | if (end-of-file or data complete) { |
806 | $txn->{result} = $txn->{buf}; |
948 | $txn->{result} = $txn->{buf}; |
… | |
… | |
814 | |
956 | |
815 | $txn->{finished}->recv; |
957 | $txn->{finished}->recv; |
816 | return $txn->{result}; |
958 | return $txn->{result}; |
817 | |
959 | |
818 | The actual code goes further and collects all errors ("die"s, |
960 | The actual code goes further and collects all errors ("die"s, |
819 | exceptions) that occured during request processing. The "result" method |
961 | exceptions) that occurred during request processing. The "result" method |
820 | detects whether an exception as thrown (it is stored inside the $txn |
962 | detects whether an exception as thrown (it is stored inside the $txn |
821 | object) and just throws the exception, which means connection errors and |
963 | object) and just throws the exception, which means connection errors and |
822 | other problems get reported tot he code that tries to use the result, |
964 | other problems get reported tot he code that tries to use the result, |
823 | not in a random callback. |
965 | not in a random callback. |
824 | |
966 | |
… | |
… | |
867 | over the event loops themselves and to give you an impression of the |
1009 | over the event loops themselves and to give you an impression of the |
868 | speed of various event loops I prepared some benchmarks. |
1010 | speed of various event loops I prepared some benchmarks. |
869 | |
1011 | |
870 | BENCHMARKING ANYEVENT OVERHEAD |
1012 | BENCHMARKING ANYEVENT OVERHEAD |
871 | Here is a benchmark of various supported event models used natively and |
1013 | Here is a benchmark of various supported event models used natively and |
872 | through anyevent. The benchmark creates a lot of timers (with a zero |
1014 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
873 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1015 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
874 | which it is), lets them fire exactly once and destroys them again. |
1016 | which it is), lets them fire exactly once and destroys them again. |
875 | |
1017 | |
876 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1018 | Source code for this benchmark is found as eg/bench in the AnyEvent |
877 | distribution. |
1019 | distribution. |
… | |
… | |
992 | |
1134 | |
993 | * You should avoid POE like the plague if you want performance or |
1135 | * You should avoid POE like the plague if you want performance or |
994 | reasonable memory usage. |
1136 | reasonable memory usage. |
995 | |
1137 | |
996 | BENCHMARKING THE LARGE SERVER CASE |
1138 | BENCHMARKING THE LARGE SERVER CASE |
997 | This benchmark atcually benchmarks the event loop itself. It works by |
1139 | This benchmark actually benchmarks the event loop itself. It works by |
998 | creating a number of "servers": each server consists of a socketpair, a |
1140 | creating a number of "servers": each server consists of a socket pair, a |
999 | timeout watcher that gets reset on activity (but never fires), and an |
1141 | timeout watcher that gets reset on activity (but never fires), and an |
1000 | I/O watcher waiting for input on one side of the socket. Each time the |
1142 | I/O watcher waiting for input on one side of the socket. Each time the |
1001 | socket watcher reads a byte it will write that byte to a random other |
1143 | socket watcher reads a byte it will write that byte to a random other |
1002 | "server". |
1144 | "server". |
1003 | |
1145 | |
1004 | The effect is that there will be a lot of I/O watchers, only part of |
1146 | The effect is that there will be a lot of I/O watchers, only part of |
1005 | which are active at any one point (so there is a constant number of |
1147 | which are active at any one point (so there is a constant number of |
1006 | active fds for each loop iterstaion, but which fds these are is random). |
1148 | active fds for each loop iteration, but which fds these are is random). |
1007 | The timeout is reset each time something is read because that reflects |
1149 | The timeout is reset each time something is read because that reflects |
1008 | how most timeouts work (and puts extra pressure on the event loops). |
1150 | how most timeouts work (and puts extra pressure on the event loops). |
1009 | |
1151 | |
1010 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which |
1152 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1011 | 100 (1%) are active. This mirrors the activity of large servers with |
1153 | 100 (1%) are active. This mirrors the activity of large servers with |
1012 | many connections, most of which are idle at any one point in time. |
1154 | many connections, most of which are idle at any one point in time. |
1013 | |
1155 | |
1014 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1156 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1015 | distribution. |
1157 | distribution. |
1016 | |
1158 | |
1017 | Explanation of the columns |
1159 | Explanation of the columns |
1018 | *sockets* is the number of sockets, and twice the number of "servers" |
1160 | *sockets* is the number of sockets, and twice the number of "servers" |
1019 | (as each server has a read and write socket end). |
1161 | (as each server has a read and write socket end). |
1020 | |
1162 | |
1021 | *create* is the time it takes to create a socketpair (which is |
1163 | *create* is the time it takes to create a socket pair (which is |
1022 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1164 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1023 | |
1165 | |
1024 | *request*, the most important value, is the time it takes to handle a |
1166 | *request*, the most important value, is the time it takes to handle a |
1025 | single "request", that is, reading the token from the pipe and |
1167 | single "request", that is, reading the token from the pipe and |
1026 | forwarding it to another server. This includes deleting the old timeout |
1168 | forwarding it to another server. This includes deleting the old timeout |
… | |
… | |
1090 | and speed most when you have lots of watchers, not when you only have a |
1232 | and speed most when you have lots of watchers, not when you only have a |
1091 | few of them). |
1233 | few of them). |
1092 | |
1234 | |
1093 | EV is again fastest. |
1235 | EV is again fastest. |
1094 | |
1236 | |
1095 | Perl again comes second. It is noticably faster than the C-based event |
1237 | Perl again comes second. It is noticeably faster than the C-based event |
1096 | loops Event and Glib, although the difference is too small to really |
1238 | loops Event and Glib, although the difference is too small to really |
1097 | matter. |
1239 | matter. |
1098 | |
1240 | |
1099 | POE also performs much better in this case, but is is still far behind |
1241 | POE also performs much better in this case, but is is still far behind |
1100 | the others. |
1242 | the others. |
… | |
… | |
1129 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1271 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1130 | be used to probe what backend is used and gain other information (which |
1272 | be used to probe what backend is used and gain other information (which |
1131 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1273 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
1132 | |
1274 | |
1133 | SEE ALSO |
1275 | SEE ALSO |
|
|
1276 | Utility functions: AnyEvent::Util. |
|
|
1277 | |
1134 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1278 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1135 | Event::Lib, Qt, POE. |
1279 | Event::Lib, Qt, POE. |
1136 | |
1280 | |
1137 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1281 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1138 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1282 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1139 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1283 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1140 | |
1284 | |
|
|
1285 | Non-blocking file handles, sockets, TCP clients and servers: |
|
|
1286 | AnyEvent::Handle, AnyEvent::Socket. |
|
|
1287 | |
|
|
1288 | Asynchronous DNS: AnyEvent::DNS. |
|
|
1289 | |
1141 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1290 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1142 | |
1291 | |
1143 | Nontrivial usage examples: Net::FCP, Net::XMPP2. |
1292 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1144 | |
1293 | |
1145 | AUTHOR |
1294 | AUTHOR |
1146 | Marc Lehmann <schmorp@schmorp.de> |
1295 | Marc Lehmann <schmorp@schmorp.de> |
1147 | http://home.schmorp.de/ |
1296 | http://home.schmorp.de/ |
1148 | |
1297 | |