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 - various supported event loops |
5 | EV, Event, Coro::EV, Coro::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 | |
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66 | |
66 | |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
67 | Of course, if you 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 |
68 | useful) and you want to force your users to use the one and only event |
69 | model, you should I<not> use this module. |
69 | model, you should I<not> use this module. |
70 | |
70 | |
71 | |
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72 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
73 | |
72 | |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
75 | allows module authors to utilise an event loop without forcing module |
74 | allows module authors to utilise an event loop without forcing module |
76 | users to use the same event loop (as only a single event loop can coexist |
75 | users to use the same event loop (as only a single event loop can coexist |
… | |
… | |
78 | |
77 | |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
78 | The interface itself is vaguely similar, but not identical to the L<Event> |
80 | module. |
79 | module. |
81 | |
80 | |
82 | During the first call of any watcher-creation method, the module tries |
81 | 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 |
82 | to detect the currently loaded event loop by probing whether one of the |
84 | the following modules is already loaded: L<Coro::EV>, L<Coro::Event>, |
83 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
85 | L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one |
84 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
86 | found is used. If none are found, the module tries to load these modules |
85 | L<POE>. The first one found is used. If none are found, the module tries |
87 | (excluding Event::Lib and Qt) in the order given. The first one that can |
86 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
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87 | adaptor should always succeed) in the order given. The first one that can |
88 | be successfully loaded will be used. If, after this, still none could be |
88 | be successfully loaded will be used. If, after this, still none could be |
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
90 | very efficient, but should work everywhere. |
90 | very efficient, but should work everywhere. |
91 | |
91 | |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
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135 | |
135 | |
136 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
136 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
137 | my variables are only visible after the statement in which they are |
137 | my variables are only visible after the statement in which they are |
138 | declared. |
138 | declared. |
139 | |
139 | |
140 | =head2 IO WATCHERS |
140 | =head2 I/O WATCHERS |
141 | |
141 | |
142 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
142 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
143 | with the following mandatory key-value pairs as arguments: |
143 | with the following mandatory key-value pairs as arguments: |
144 | |
144 | |
145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for |
145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
146 | events. C<poll> must be a string that is either C<r> or C<w>, which |
146 | for events. C<poll> must be a string that is either C<r> or C<w>, |
147 | creates a watcher waiting for "r"eadable or "w"ritable events, |
147 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
148 | respectively. C<cb> is the callback to invoke each time the file handle |
148 | respectively. C<cb> is the callback to invoke each time the file handle |
149 | becomes ready. |
149 | becomes ready. |
150 | |
150 | |
151 | As long as the I/O watcher exists it will keep the file descriptor or a |
151 | Although the callback might get passed parameters, their value and |
152 | copy of it alive/open. |
152 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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153 | callbacks cannot use arguments passed to I/O watcher callbacks. |
153 | |
154 | |
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155 | The I/O watcher might use the underlying file descriptor or a copy of it. |
154 | It is not allowed to close a file handle as long as any watcher is active |
156 | You must not close a file handle as long as any watcher is active on the |
155 | on the underlying file descriptor. |
157 | underlying file descriptor. |
156 | |
158 | |
157 | Some event loops issue spurious readyness notifications, so you should |
159 | Some event loops issue spurious readyness notifications, so you should |
158 | always use non-blocking calls when reading/writing from/to your file |
160 | always use non-blocking calls when reading/writing from/to your file |
159 | handles. |
161 | handles. |
160 | |
162 | |
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171 | |
173 | |
172 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
174 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
173 | method with the following mandatory arguments: |
175 | method with the following mandatory arguments: |
174 | |
176 | |
175 | C<after> specifies after how many seconds (fractional values are |
177 | C<after> specifies after how many seconds (fractional values are |
176 | supported) should the timer activate. C<cb> the callback to invoke in that |
178 | supported) the callback should be invoked. C<cb> is the callback to invoke |
177 | case. |
179 | in that case. |
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180 | |
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181 | Although the callback might get passed parameters, their value and |
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182 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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183 | callbacks cannot use arguments passed to time watcher callbacks. |
178 | |
184 | |
179 | The timer callback will be invoked at most once: if you want a repeating |
185 | The timer callback will be invoked at most once: if you want a repeating |
180 | timer you have to create a new watcher (this is a limitation by both Tk |
186 | timer you have to create a new watcher (this is a limitation by both Tk |
181 | and Glib). |
187 | and Glib). |
182 | |
188 | |
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227 | |
233 | |
228 | You can watch for signals using a signal watcher, C<signal> is the signal |
234 | You can watch for signals using a signal watcher, C<signal> is the signal |
229 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
235 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
230 | be invoked whenever a signal occurs. |
236 | be invoked whenever a signal occurs. |
231 | |
237 | |
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238 | Although the callback might get passed parameters, their value and |
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239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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240 | callbacks cannot use arguments passed to signal watcher callbacks. |
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241 | |
232 | Multiple signal occurances can be clumped together into one callback |
242 | Multiple signal occurances can be clumped together into one callback |
233 | invocation, and callback invocation will be synchronous. synchronous means |
243 | invocation, and callback invocation will be synchronous. synchronous means |
234 | that it might take a while until the signal gets handled by the process, |
244 | that it might take a while until the signal gets handled by the process, |
235 | but it is guarenteed not to interrupt any other callbacks. |
245 | but it is guarenteed not to interrupt any other callbacks. |
236 | |
246 | |
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250 | |
260 | |
251 | The child process is specified by the C<pid> argument (if set to C<0>, it |
261 | The child process is specified by the C<pid> argument (if set to C<0>, it |
252 | watches for any child process exit). The watcher will trigger as often |
262 | watches for any child process exit). The watcher will trigger as often |
253 | as status change for the child are received. This works by installing a |
263 | as status change for the child are received. This works by installing a |
254 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
264 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
255 | and exit status (as returned by waitpid). |
265 | and exit status (as returned by waitpid), so unlike other watcher types, |
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266 | you I<can> rely on child watcher callback arguments. |
256 | |
267 | |
257 | Example: wait for pid 1333 |
268 | There is a slight catch to child watchers, however: you usually start them |
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269 | I<after> the child process was created, and this means the process could |
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270 | have exited already (and no SIGCHLD will be sent anymore). |
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271 | |
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272 | Not all event models handle this correctly (POE doesn't), but even for |
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273 | event models that I<do> handle this correctly, they usually need to be |
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274 | loaded before the process exits (i.e. before you fork in the first place). |
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275 | |
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276 | This means you cannot create a child watcher as the very first thing in an |
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277 | AnyEvent program, you I<have> to create at least one watcher before you |
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278 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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279 | |
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280 | Example: fork a process and wait for it |
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281 | |
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282 | my $done = AnyEvent->condvar; |
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283 | |
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284 | AnyEvent::detect; # force event module to be initialised |
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285 | |
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286 | my $pid = fork or exit 5; |
258 | |
287 | |
259 | my $w = AnyEvent->child ( |
288 | my $w = AnyEvent->child ( |
260 | pid => 1333, |
289 | pid => $pid, |
261 | cb => sub { |
290 | cb => sub { |
262 | my ($pid, $status) = @_; |
291 | my ($pid, $status) = @_; |
263 | warn "pid $pid exited with status $status"; |
292 | warn "pid $pid exited with status $status"; |
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293 | $done->broadcast; |
264 | }, |
294 | }, |
265 | ); |
295 | ); |
266 | |
296 | |
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297 | # do something else, then wait for process exit |
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298 | $done->wait; |
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299 | |
267 | =head2 CONDITION VARIABLES |
300 | =head2 CONDITION VARIABLES |
268 | |
301 | |
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302 | If you are familiar with some event loops you will know that all of them |
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303 | require you to run some blocking "loop", "run" or similar function that |
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304 | will actively watch for new events and call your callbacks. |
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305 | |
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306 | AnyEvent is different, it expects somebody else to run the event loop and |
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307 | will only block when necessary (usually when told by the user). |
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308 | |
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309 | The instrument to do that is called a "condition variable", so called |
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310 | because they represent a condition that must become true. |
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311 | |
269 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
312 | Condition variables can be created by calling the C<< AnyEvent->condvar |
270 | method without any arguments. |
313 | >> method, usually without arguments. The only argument pair allowed is |
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314 | C<cb>, which specifies a callback to be called when the condition variable |
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315 | becomes true. |
271 | |
316 | |
272 | A condition variable waits for a condition - precisely that the C<< |
317 | After creation, the conditon variable is "false" until it becomes "true" |
273 | ->broadcast >> method has been called. |
318 | by calling the C<broadcast> method. |
274 | |
319 | |
275 | They are very useful to signal that a condition has been fulfilled, for |
320 | Condition variables are similar to callbacks, except that you can |
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321 | optionally wait for them. They can also be called merge points - points |
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322 | in time where multiple outstandign events have been processed. And yet |
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323 | another way to call them is transations - each condition variable can be |
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324 | used to represent a transaction, which finishes at some point and delivers |
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325 | a result. |
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326 | |
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327 | Condition variables are very useful to signal that something has finished, |
276 | example, if you write a module that does asynchronous http requests, |
328 | for example, if you write a module that does asynchronous http requests, |
277 | then a condition variable would be the ideal candidate to signal the |
329 | then a condition variable would be the ideal candidate to signal the |
278 | availability of results. |
330 | availability of results. The user can either act when the callback is |
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331 | called or can synchronously C<< ->wait >> for the results. |
279 | |
332 | |
280 | You can also use condition variables to block your main program until |
333 | You can also use them to simulate traditional event loops - for example, |
281 | an event occurs - for example, you could C<< ->wait >> in your main |
334 | you can block your main program until an event occurs - for example, you |
282 | program until the user clicks the Quit button in your app, which would C<< |
335 | could C<< ->wait >> in your main program until the user clicks the Quit |
283 | ->broadcast >> the "quit" event. |
336 | button of your app, which would C<< ->broadcast >> the "quit" event. |
284 | |
337 | |
285 | Note that condition variables recurse into the event loop - if you have |
338 | Note that condition variables recurse into the event loop - if you have |
286 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
339 | two pieces of code that call C<< ->wait >> in a round-robbin fashion, you |
287 | lose. Therefore, condition variables are good to export to your caller, but |
340 | lose. Therefore, condition variables are good to export to your caller, but |
288 | you should avoid making a blocking wait yourself, at least in callbacks, |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
289 | as this asks for trouble. |
342 | as this asks for trouble. |
290 | |
343 | |
291 | This object has two methods: |
344 | Condition variables are represented by hash refs in perl, and the keys |
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345 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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346 | easy (it is often useful to build your own transaction class on top of |
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347 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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348 | it's C<new> method in your own C<new> method. |
292 | |
349 | |
293 | =over 4 |
350 | There are two "sides" to a condition variable - the "producer side" which |
294 | |
351 | eventually calls C<< -> broadcast >>, and the "consumer side", which waits |
295 | =item $cv->wait |
352 | for the broadcast to occur. |
296 | |
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297 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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298 | called on c<$cv>, while servicing other watchers normally. |
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299 | |
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300 | You can only wait once on a condition - additional calls will return |
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301 | immediately. |
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302 | |
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303 | Not all event models support a blocking wait - some die in that case |
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304 | (programs might want to do that to stay interactive), so I<if you are |
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305 | using this from a module, never require a blocking wait>, but let the |
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306 | caller decide whether the call will block or not (for example, by coupling |
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307 | condition variables with some kind of request results and supporting |
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308 | callbacks so the caller knows that getting the result will not block, |
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309 | while still suppporting blocking waits if the caller so desires). |
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310 | |
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311 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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312 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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313 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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314 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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315 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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316 | from different coroutines, however). |
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317 | |
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318 | =item $cv->broadcast |
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319 | |
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320 | Flag the condition as ready - a running C<< ->wait >> and all further |
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321 | calls to C<wait> will (eventually) return after this method has been |
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322 | called. If nobody is waiting the broadcast will be remembered.. |
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323 | |
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324 | =back |
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325 | |
353 | |
326 | Example: |
354 | Example: |
327 | |
355 | |
328 | # wait till the result is ready |
356 | # wait till the result is ready |
329 | my $result_ready = AnyEvent->condvar; |
357 | my $result_ready = AnyEvent->condvar; |
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335 | my $w = AnyEvent->timer ( |
363 | my $w = AnyEvent->timer ( |
336 | after => 1, |
364 | after => 1, |
337 | cb => sub { $result_ready->broadcast }, |
365 | cb => sub { $result_ready->broadcast }, |
338 | ); |
366 | ); |
339 | |
367 | |
340 | # this "blocks" (while handling events) till the watcher |
368 | # this "blocks" (while handling events) till the callback |
341 | # calls broadcast |
369 | # calls broadcast |
342 | $result_ready->wait; |
370 | $result_ready->wait; |
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371 | |
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372 | =head3 METHODS FOR PRODUCERS |
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373 | |
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374 | These methods should only be used by the producing side, i.e. the |
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375 | code/module that eventually broadcasts the signal. Note that it is also |
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376 | the producer side which creates the condvar in most cases, but it isn't |
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377 | uncommon for the consumer to create it as well. |
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378 | |
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379 | =over 4 |
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380 | |
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381 | =item $cv->broadcast (...) |
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382 | |
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383 | Flag the condition as ready - a running C<< ->wait >> and all further |
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384 | calls to C<wait> will (eventually) return after this method has been |
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385 | called. If nobody is waiting the broadcast will be remembered. |
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386 | |
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387 | If a callback has been set on the condition variable, it is called |
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388 | immediately from within broadcast. |
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389 | |
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390 | Any arguments passed to the C<broadcast> call will be returned by all |
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391 | future C<< ->wait >> calls. |
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392 | |
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393 | =item $cv->croak ($error) |
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394 | |
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395 | Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke |
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396 | C<Carp::croak> with the given error message/object/scalar. |
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397 | |
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398 | This can be used to signal any errors to the condition variable |
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399 | user/consumer. |
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400 | |
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401 | =item $cv->begin ([group callback]) |
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402 | |
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403 | =item $cv->end |
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404 | |
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405 | These two methods can be used to combine many transactions/events into |
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406 | one. For example, a function that pings many hosts in parallel might want |
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407 | to use a condition variable for the whole process. |
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408 | |
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409 | Every call to C<< ->begin >> will increment a counter, and every call to |
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410 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
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411 | >>, the (last) callback passed to C<begin> will be executed. That callback |
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412 | is I<supposed> to call C<< ->broadcast >>, but that is not required. If no |
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413 | callback was set, C<broadcast> will be called without any arguments. |
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414 | |
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415 | Let's clarify this with the ping example: |
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416 | |
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417 | my $cv = AnyEvent->condvar; |
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418 | |
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419 | my %result; |
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420 | $cv->begin (sub { $cv->broadcast (\%result) }); |
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421 | |
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422 | for my $host (@list_of_hosts) { |
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423 | $cv->begin; |
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424 | ping_host_then_call_callback $host, sub { |
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425 | $result{$host} = ...; |
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426 | $cv->end; |
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427 | }; |
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428 | } |
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429 | |
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430 | $cv->end; |
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431 | |
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432 | This code fragment supposedly pings a number of hosts and calls |
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433 | C<broadcast> after results for all then have have been gathered - in any |
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434 | order. To achieve this, the code issues a call to C<begin> when it starts |
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435 | each ping request and calls C<end> when it has received some result for |
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436 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
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437 | results arrive is not relevant. |
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438 | |
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439 | There is an additional bracketing call to C<begin> and C<end> outside the |
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440 | loop, which serves two important purposes: first, it sets the callback |
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441 | to be called once the counter reaches C<0>, and second, it ensures that |
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442 | broadcast is called even when C<no> hosts are being pinged (the loop |
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443 | doesn't execute once). |
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444 | |
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445 | This is the general pattern when you "fan out" into multiple subrequests: |
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446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
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447 | is called at least once, and then, for each subrequest you start, call |
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448 | C<begin> and for eahc subrequest you finish, call C<end>. |
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449 | |
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450 | =back |
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451 | |
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452 | =head3 METHODS FOR CONSUMERS |
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453 | |
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454 | These methods should only be used by the consuming side, i.e. the |
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455 | code awaits the condition. |
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456 | |
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457 | =item $cv->wait |
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458 | |
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459 | Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak |
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460 | >> methods have been called on c<$cv>, while servicing other watchers |
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461 | normally. |
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462 | |
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463 | You can only wait once on a condition - additional calls are valid but |
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464 | will return immediately. |
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465 | |
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466 | If an error condition has been set by calling C<< ->croak >>, then this |
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467 | function will call C<croak>. |
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468 | |
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469 | In list context, all parameters passed to C<broadcast> will be returned, |
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470 | in scalar context only the first one will be returned. |
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471 | |
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472 | Not all event models support a blocking wait - some die in that case |
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473 | (programs might want to do that to stay interactive), so I<if you are |
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474 | using this from a module, never require a blocking wait>, but let the |
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475 | caller decide whether the call will block or not (for example, by coupling |
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476 | condition variables with some kind of request results and supporting |
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477 | callbacks so the caller knows that getting the result will not block, |
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478 | while still suppporting blocking waits if the caller so desires). |
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479 | |
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480 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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481 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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482 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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483 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
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484 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
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485 | from different coroutines, however). |
|
|
486 | |
|
|
487 | You can ensure that C<< -wait >> never blocks by setting a callback and |
|
|
488 | only calling C<< ->wait >> from within that callback (or at a later |
|
|
489 | time). This will work even when the event loop does not support blocking |
|
|
490 | waits otherwise. |
|
|
491 | |
|
|
492 | =back |
343 | |
493 | |
344 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
494 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
345 | |
495 | |
346 | =over 4 |
496 | =over 4 |
347 | |
497 | |
… | |
… | |
357 | |
507 | |
358 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
508 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
359 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
509 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
360 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
510 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
361 | AnyEvent::Impl::Event based on Event, second best choice. |
511 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
512 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
362 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
513 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
363 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
514 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
364 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
365 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
515 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
366 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
516 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
517 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
518 | |
|
|
519 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
520 | watching file handles. However, you can use WxWidgets through the |
|
|
521 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
522 | second, which was considered to be too horrible to even consider for |
|
|
523 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
524 | it's adaptor. |
|
|
525 | |
|
|
526 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
527 | autodetecting them. |
367 | |
528 | |
368 | =item AnyEvent::detect |
529 | =item AnyEvent::detect |
369 | |
530 | |
370 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
531 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
371 | if necessary. You should only call this function right before you would |
532 | if necessary. You should only call this function right before you would |
… | |
… | |
413 | |
574 | |
414 | You can chose to use a rather inefficient pure-perl implementation by |
575 | You can chose to use a rather inefficient pure-perl implementation by |
415 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
576 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
416 | behaviour everywhere, but letting AnyEvent chose is generally better. |
577 | behaviour everywhere, but letting AnyEvent chose is generally better. |
417 | |
578 | |
|
|
579 | =head1 OTHER MODULES |
|
|
580 | |
|
|
581 | The following is a non-exhaustive list of additional modules that use |
|
|
582 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
583 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
584 | available via CPAN. |
|
|
585 | |
|
|
586 | =over 4 |
|
|
587 | |
|
|
588 | =item L<AnyEvent::Util> |
|
|
589 | |
|
|
590 | Contains various utility functions that replace often-used but blocking |
|
|
591 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
592 | |
|
|
593 | =item L<AnyEvent::Handle> |
|
|
594 | |
|
|
595 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
596 | |
|
|
597 | =item L<AnyEvent::Socket> |
|
|
598 | |
|
|
599 | Provides a means to do non-blocking connects, accepts etc. |
|
|
600 | |
|
|
601 | =item L<AnyEvent::HTTPD> |
|
|
602 | |
|
|
603 | Provides a simple web application server framework. |
|
|
604 | |
|
|
605 | =item L<AnyEvent::DNS> |
|
|
606 | |
|
|
607 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
608 | L<AnyEvent::Util> offers. |
|
|
609 | |
|
|
610 | =item L<AnyEvent::FastPing> |
|
|
611 | |
|
|
612 | The fastest ping in the west. |
|
|
613 | |
|
|
614 | =item L<Net::IRC3> |
|
|
615 | |
|
|
616 | AnyEvent based IRC client module family. |
|
|
617 | |
|
|
618 | =item L<Net::XMPP2> |
|
|
619 | |
|
|
620 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
621 | |
|
|
622 | =item L<Net::FCP> |
|
|
623 | |
|
|
624 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
625 | of AnyEvent. |
|
|
626 | |
|
|
627 | =item L<Event::ExecFlow> |
|
|
628 | |
|
|
629 | High level API for event-based execution flow control. |
|
|
630 | |
|
|
631 | =item L<Coro> |
|
|
632 | |
|
|
633 | Has special support for AnyEvent. |
|
|
634 | |
|
|
635 | =item L<IO::Lambda> |
|
|
636 | |
|
|
637 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
638 | |
|
|
639 | =item L<IO::AIO> |
|
|
640 | |
|
|
641 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
642 | programmer. Can be trivially made to use AnyEvent. |
|
|
643 | |
|
|
644 | =item L<BDB> |
|
|
645 | |
|
|
646 | Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
647 | AnyEvent. |
|
|
648 | |
|
|
649 | =back |
|
|
650 | |
418 | =cut |
651 | =cut |
419 | |
652 | |
420 | package AnyEvent; |
653 | package AnyEvent; |
421 | |
654 | |
422 | no warnings; |
655 | no warnings; |
423 | use strict; |
656 | use strict; |
424 | |
657 | |
425 | use Carp; |
658 | use Carp; |
426 | |
659 | |
427 | our $VERSION = '3.2'; |
660 | our $VERSION = '3.3'; |
428 | our $MODEL; |
661 | our $MODEL; |
429 | |
662 | |
430 | our $AUTOLOAD; |
663 | our $AUTOLOAD; |
431 | our @ISA; |
664 | our @ISA; |
432 | |
665 | |
… | |
… | |
437 | my @models = ( |
670 | my @models = ( |
438 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
671 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
439 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
672 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
440 | [EV:: => AnyEvent::Impl::EV::], |
673 | [EV:: => AnyEvent::Impl::EV::], |
441 | [Event:: => AnyEvent::Impl::Event::], |
674 | [Event:: => AnyEvent::Impl::Event::], |
|
|
675 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
676 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
677 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
678 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
679 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
442 | [Glib:: => AnyEvent::Impl::Glib::], |
680 | [Glib:: => AnyEvent::Impl::Glib::], |
443 | [Tk:: => AnyEvent::Impl::Tk::], |
681 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
444 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
445 | ); |
|
|
446 | my @models_detect = ( |
|
|
447 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
682 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
448 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
683 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
449 | ); |
684 | ); |
450 | |
685 | |
451 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
686 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
452 | |
687 | |
453 | sub detect() { |
688 | sub detect() { |
… | |
… | |
457 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
692 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
458 | my $model = "AnyEvent::Impl::$1"; |
693 | my $model = "AnyEvent::Impl::$1"; |
459 | if (eval "require $model") { |
694 | if (eval "require $model") { |
460 | $MODEL = $model; |
695 | $MODEL = $model; |
461 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
696 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
697 | } else { |
|
|
698 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
462 | } |
699 | } |
463 | } |
700 | } |
464 | |
701 | |
465 | # check for already loaded models |
702 | # check for already loaded models |
466 | unless ($MODEL) { |
703 | unless ($MODEL) { |
467 | for (@REGISTRY, @models, @models_detect) { |
704 | for (@REGISTRY, @models) { |
468 | my ($package, $model) = @$_; |
705 | my ($package, $model) = @$_; |
469 | if (${"$package\::VERSION"} > 0) { |
706 | if (${"$package\::VERSION"} > 0) { |
470 | if (eval "require $model") { |
707 | if (eval "require $model") { |
471 | $MODEL = $model; |
708 | $MODEL = $model; |
472 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
709 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
… | |
… | |
659 | |
896 | |
660 | =over 4 |
897 | =over 4 |
661 | |
898 | |
662 | =item C<PERL_ANYEVENT_VERBOSE> |
899 | =item C<PERL_ANYEVENT_VERBOSE> |
663 | |
900 | |
|
|
901 | By default, AnyEvent will be completely silent except in fatal |
|
|
902 | conditions. You can set this environment variable to make AnyEvent more |
|
|
903 | talkative. |
|
|
904 | |
|
|
905 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
906 | conditions, such as not being able to load the event model specified by |
|
|
907 | C<PERL_ANYEVENT_MODEL>. |
|
|
908 | |
664 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
909 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
665 | model it chooses. |
910 | model it chooses. |
666 | |
911 | |
667 | =item C<PERL_ANYEVENT_MODEL> |
912 | =item C<PERL_ANYEVENT_MODEL> |
668 | |
913 | |
… | |
… | |
682 | |
927 | |
683 | =back |
928 | =back |
684 | |
929 | |
685 | =head1 EXAMPLE PROGRAM |
930 | =head1 EXAMPLE PROGRAM |
686 | |
931 | |
687 | The following program uses an IO watcher to read data from STDIN, a timer |
932 | The following program uses an I/O watcher to read data from STDIN, a timer |
688 | to display a message once per second, and a condition variable to quit the |
933 | to display a message once per second, and a condition variable to quit the |
689 | program when the user enters quit: |
934 | program when the user enters quit: |
690 | |
935 | |
691 | use AnyEvent; |
936 | use AnyEvent; |
692 | |
937 | |
… | |
… | |
836 | $quit->broadcast; |
1081 | $quit->broadcast; |
837 | }); |
1082 | }); |
838 | |
1083 | |
839 | $quit->wait; |
1084 | $quit->wait; |
840 | |
1085 | |
|
|
1086 | |
|
|
1087 | =head1 BENCHMARKS |
|
|
1088 | |
|
|
1089 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1090 | over the event loops themselves and to give you an impression of the speed |
|
|
1091 | of various event loops I prepared some benchmarks. |
|
|
1092 | |
|
|
1093 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1094 | |
|
|
1095 | Here is a benchmark of various supported event models used natively and |
|
|
1096 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
1097 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1098 | which it is), lets them fire exactly once and destroys them again. |
|
|
1099 | |
|
|
1100 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1101 | distribution. |
|
|
1102 | |
|
|
1103 | =head3 Explanation of the columns |
|
|
1104 | |
|
|
1105 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1106 | different event models feature vastly different performances, each event |
|
|
1107 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1108 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1109 | would probably take thousands of years if asked to process the same number |
|
|
1110 | of watchers as EV in this benchmark. |
|
|
1111 | |
|
|
1112 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1113 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1114 | and Perl-based overheads. |
|
|
1115 | |
|
|
1116 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1117 | takes to create a single watcher. The callback is a closure shared between |
|
|
1118 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1119 | and memory usage is not included in the figures. |
|
|
1120 | |
|
|
1121 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1122 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1123 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
|
|
1124 | signal the end of this phase. |
|
|
1125 | |
|
|
1126 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1127 | watcher. |
|
|
1128 | |
|
|
1129 | =head3 Results |
|
|
1130 | |
|
|
1131 | name watchers bytes create invoke destroy comment |
|
|
1132 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1133 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1134 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1135 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1136 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1137 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1138 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1139 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1140 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1141 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1142 | |
|
|
1143 | =head3 Discussion |
|
|
1144 | |
|
|
1145 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1146 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1147 | can never compete with an event loop that uses epoll when the number of |
|
|
1148 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1149 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1150 | boost. |
|
|
1151 | |
|
|
1152 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1153 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1154 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1155 | higher number of watchers at a disadvantage. |
|
|
1156 | |
|
|
1157 | To put the range of results into perspective, consider that on the |
|
|
1158 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1159 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1160 | cycles with POE. |
|
|
1161 | |
|
|
1162 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1163 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1164 | far less memory than any other event loop and is still faster than Event |
|
|
1165 | natively. |
|
|
1166 | |
|
|
1167 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1168 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1169 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1170 | adds very little overhead in itself. Like any select-based backend its |
|
|
1171 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1172 | them active), of course, but this was not subject of this benchmark. |
|
|
1173 | |
|
|
1174 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1175 | cost, but overall scores in on the third place. |
|
|
1176 | |
|
|
1177 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1178 | faster callback invocation and overall ends up in the same class as |
|
|
1179 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1180 | watchers increases the processing time by more than a factor of four, |
|
|
1181 | making it completely unusable when using larger numbers of watchers |
|
|
1182 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1183 | inefficiencies of C<poll> do not account for this). |
|
|
1184 | |
|
|
1185 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1186 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1187 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1188 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1189 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1190 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1191 | above). |
|
|
1192 | |
|
|
1193 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1194 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1195 | be tested because it wasn't working) shows abysmal performance and |
|
|
1196 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1197 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1198 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1199 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1200 | implementation. |
|
|
1201 | |
|
|
1202 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1203 | for the performance issues, though, as session creation overhead is |
|
|
1204 | small compared to execution of the state machine, which is coded pretty |
|
|
1205 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1206 | using multiple sessions is not a good approach, especially regarding |
|
|
1207 | memory usage, even the author of POE could not come up with a faster |
|
|
1208 | design). |
|
|
1209 | |
|
|
1210 | =head3 Summary |
|
|
1211 | |
|
|
1212 | =over 4 |
|
|
1213 | |
|
|
1214 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1215 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1216 | performance with or without AnyEvent. |
|
|
1217 | |
|
|
1218 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1219 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1220 | adds AnyEvent significant overhead. |
|
|
1221 | |
|
|
1222 | =item * You should avoid POE like the plague if you want performance or |
|
|
1223 | reasonable memory usage. |
|
|
1224 | |
|
|
1225 | =back |
|
|
1226 | |
|
|
1227 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1228 | |
|
|
1229 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
1230 | creating a number of "servers": each server consists of a socketpair, a |
|
|
1231 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1232 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1233 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1234 | |
|
|
1235 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1236 | are active at any one point (so there is a constant number of active |
|
|
1237 | fds for each loop iterstaion, but which fds these are is random). The |
|
|
1238 | timeout is reset each time something is read because that reflects how |
|
|
1239 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1240 | |
|
|
1241 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
|
|
1242 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1243 | connections, most of which are idle at any one point in time. |
|
|
1244 | |
|
|
1245 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1246 | distribution. |
|
|
1247 | |
|
|
1248 | =head3 Explanation of the columns |
|
|
1249 | |
|
|
1250 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1251 | each server has a read and write socket end). |
|
|
1252 | |
|
|
1253 | I<create> is the time it takes to create a socketpair (which is |
|
|
1254 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1255 | |
|
|
1256 | I<request>, the most important value, is the time it takes to handle a |
|
|
1257 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1258 | it to another server. This includes deleting the old timeout and creating |
|
|
1259 | a new one that moves the timeout into the future. |
|
|
1260 | |
|
|
1261 | =head3 Results |
|
|
1262 | |
|
|
1263 | name sockets create request |
|
|
1264 | EV 20000 69.01 11.16 |
|
|
1265 | Perl 20000 73.32 35.87 |
|
|
1266 | Event 20000 212.62 257.32 |
|
|
1267 | Glib 20000 651.16 1896.30 |
|
|
1268 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1269 | |
|
|
1270 | =head3 Discussion |
|
|
1271 | |
|
|
1272 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1273 | particular event loop. |
|
|
1274 | |
|
|
1275 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1276 | is relatively high, though. |
|
|
1277 | |
|
|
1278 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1279 | loops Event and Glib. |
|
|
1280 | |
|
|
1281 | Event suffers from high setup time as well (look at its code and you will |
|
|
1282 | understand why). Callback invocation also has a high overhead compared to |
|
|
1283 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1284 | uses select or poll in basically all documented configurations. |
|
|
1285 | |
|
|
1286 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1287 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1288 | |
|
|
1289 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1290 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1291 | it uses a C-based event loop in this case. |
|
|
1292 | |
|
|
1293 | =head3 Summary |
|
|
1294 | |
|
|
1295 | =over 4 |
|
|
1296 | |
|
|
1297 | =item * The pure perl implementation performs extremely well. |
|
|
1298 | |
|
|
1299 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1300 | |
|
|
1301 | =back |
|
|
1302 | |
|
|
1303 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1304 | |
|
|
1305 | While event loops should scale (and select-based ones do not...) even to |
|
|
1306 | large servers, most programs we (or I :) actually write have only a few |
|
|
1307 | I/O watchers. |
|
|
1308 | |
|
|
1309 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1310 | case, but it uses only eight "servers", of which three are active at any |
|
|
1311 | one time. This should reflect performance for a small server relatively |
|
|
1312 | well. |
|
|
1313 | |
|
|
1314 | The columns are identical to the previous table. |
|
|
1315 | |
|
|
1316 | =head3 Results |
|
|
1317 | |
|
|
1318 | name sockets create request |
|
|
1319 | EV 16 20.00 6.54 |
|
|
1320 | Perl 16 25.75 12.62 |
|
|
1321 | Event 16 81.27 35.86 |
|
|
1322 | Glib 16 32.63 15.48 |
|
|
1323 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1324 | |
|
|
1325 | =head3 Discussion |
|
|
1326 | |
|
|
1327 | The benchmark tries to test the performance of a typical small |
|
|
1328 | server. While knowing how various event loops perform is interesting, keep |
|
|
1329 | in mind that their overhead in this case is usually not as important, due |
|
|
1330 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1331 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1332 | them). |
|
|
1333 | |
|
|
1334 | EV is again fastest. |
|
|
1335 | |
|
|
1336 | Perl again comes second. It is noticably faster than the C-based event |
|
|
1337 | loops Event and Glib, although the difference is too small to really |
|
|
1338 | matter. |
|
|
1339 | |
|
|
1340 | POE also performs much better in this case, but is is still far behind the |
|
|
1341 | others. |
|
|
1342 | |
|
|
1343 | =head3 Summary |
|
|
1344 | |
|
|
1345 | =over 4 |
|
|
1346 | |
|
|
1347 | =item * C-based event loops perform very well with small number of |
|
|
1348 | watchers, as the management overhead dominates. |
|
|
1349 | |
|
|
1350 | =back |
|
|
1351 | |
|
|
1352 | |
841 | =head1 FORK |
1353 | =head1 FORK |
842 | |
1354 | |
843 | Most event libraries are not fork-safe. The ones who are usually are |
1355 | Most event libraries are not fork-safe. The ones who are usually are |
844 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1356 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1357 | calls. Only L<EV> is fully fork-aware. |
845 | |
1358 | |
846 | If you have to fork, you must either do so I<before> creating your first |
1359 | If you have to fork, you must either do so I<before> creating your first |
847 | watcher OR you must not use AnyEvent at all in the child. |
1360 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1361 | |
848 | |
1362 | |
849 | =head1 SECURITY CONSIDERATIONS |
1363 | =head1 SECURITY CONSIDERATIONS |
850 | |
1364 | |
851 | AnyEvent can be forced to load any event model via |
1365 | AnyEvent can be forced to load any event model via |
852 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
1366 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
… | |
… | |
860 | |
1374 | |
861 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1375 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
862 | |
1376 | |
863 | use AnyEvent; |
1377 | use AnyEvent; |
864 | |
1378 | |
|
|
1379 | |
865 | =head1 SEE ALSO |
1380 | =head1 SEE ALSO |
866 | |
1381 | |
867 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1382 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
868 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
1383 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
869 | L<Event::Lib>, L<Qt>. |
1384 | L<Event::Lib>, L<Qt>, L<POE>. |
870 | |
1385 | |
871 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1386 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
872 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
1387 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
873 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
1388 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
874 | L<AnyEvent::Impl::Qt>. |
1389 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
875 | |
1390 | |
876 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1391 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
|
|
1392 | |
877 | |
1393 | |
878 | =head1 AUTHOR |
1394 | =head1 AUTHOR |
879 | |
1395 | |
880 | Marc Lehmann <schmorp@schmorp.de> |
1396 | Marc Lehmann <schmorp@schmorp.de> |
881 | http://home.schmorp.de/ |
1397 | http://home.schmorp.de/ |