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 - various supported event loops |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
… | |
… | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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20 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
… | |
… | |
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 |
… | |
… | |
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 the |
82 | to detect the currently loaded event loop by probing whether one of the |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
83 | following modules is already loaded: L<EV>, |
85 | L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found, |
84 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
86 | the module tries to load these modules in the stated order. The first one |
85 | L<POE>. The first one found is used. If none are found, the module tries |
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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 |
87 | that can be successfully loaded will be used. If, after this, still none |
88 | be successfully loaded will be used. If, after this, still none could be |
88 | could be found, AnyEvent will fall back to a pure-perl event loop, which |
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
89 | is not very efficient, but should work everywhere. |
90 | very efficient, but should work everywhere. |
90 | |
91 | |
91 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | an event model explicitly before first using AnyEvent will likely make |
93 | an event model explicitly before first using AnyEvent will likely make |
93 | that model the default. For example: |
94 | that model the default. For example: |
94 | |
95 | |
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134 | |
135 | |
135 | 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, |
136 | 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 |
137 | declared. |
138 | declared. |
138 | |
139 | |
139 | =head2 IO WATCHERS |
140 | =head2 I/O WATCHERS |
140 | |
141 | |
141 | 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 |
142 | with the following mandatory key-value pairs as arguments: |
143 | with the following mandatory key-value pairs as arguments: |
143 | |
144 | |
144 | 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 |
145 | 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>, |
146 | creates a watcher waiting for "r"eadable or "w"ritable events, |
147 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
147 | 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 |
148 | becomes ready. |
149 | becomes ready. |
149 | |
150 | |
150 | File handles will be kept alive, so as long as the watcher exists, the |
151 | Although the callback might get passed parameters, their value and |
151 | file handle exists, too. |
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. |
152 | |
154 | |
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155 | The I/O watcher might use the underlying file descriptor or a copy of it. |
153 | 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 |
154 | on the underlying file descriptor. |
157 | underlying file descriptor. |
155 | |
158 | |
156 | Some event loops issue spurious readyness notifications, so you should |
159 | Some event loops issue spurious readyness notifications, so you should |
157 | 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 |
158 | handles. |
161 | handles. |
159 | |
162 | |
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170 | |
173 | |
171 | 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 >> |
172 | method with the following mandatory arguments: |
175 | method with the following mandatory arguments: |
173 | |
176 | |
174 | C<after> specifies after how many seconds (fractional values are |
177 | C<after> specifies after how many seconds (fractional values are |
175 | 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 |
176 | 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. |
177 | |
184 | |
178 | 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 |
179 | 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 |
180 | and Glib). |
187 | and Glib). |
181 | |
188 | |
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206 | |
213 | |
207 | There are two ways to handle timers: based on real time (relative, "fire |
214 | There are two ways to handle timers: based on real time (relative, "fire |
208 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
215 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
209 | o'clock"). |
216 | o'clock"). |
210 | |
217 | |
211 | While most event loops expect timers to specified in a relative way, they use |
218 | While most event loops expect timers to specified in a relative way, they |
212 | absolute time internally. This makes a difference when your clock "jumps", |
219 | use absolute time internally. This makes a difference when your clock |
213 | for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to |
220 | "jumps", for example, when ntp decides to set your clock backwards from |
214 | 2008-01-01, a watcher that you created to fire "after" a second might actually take |
221 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
215 | six years to finally fire. |
222 | fire "after" a second might actually take six years to finally fire. |
216 | |
223 | |
217 | AnyEvent cannot compensate for this. The only event loop that is conscious |
224 | AnyEvent cannot compensate for this. The only event loop that is conscious |
218 | about these issues is L<EV>, which offers both relative (ev_timer) and |
225 | about these issues is L<EV>, which offers both relative (ev_timer, based |
219 | absolute (ev_periodic) timers. |
226 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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227 | timers. |
220 | |
228 | |
221 | AnyEvent always prefers relative timers, if available, matching the |
229 | AnyEvent always prefers relative timers, if available, matching the |
222 | AnyEvent API. |
230 | AnyEvent API. |
223 | |
231 | |
224 | =head2 SIGNAL WATCHERS |
232 | =head2 SIGNAL WATCHERS |
225 | |
233 | |
226 | 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 |
227 | 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 |
228 | be invoked whenever a signal occurs. |
236 | be invoked whenever a signal occurs. |
229 | |
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 | |
230 | Multiple signals occurances can be clumped together into one callback |
242 | Multiple signal occurances can be clumped together into one callback |
231 | invocation, and callback invocation will be synchronous. synchronous means |
243 | invocation, and callback invocation will be synchronous. synchronous means |
232 | 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, |
233 | but it is guarenteed not to interrupt any other callbacks. |
245 | but it is guarenteed not to interrupt any other callbacks. |
234 | |
246 | |
235 | The main advantage of using these watchers is that you can share a signal |
247 | The main advantage of using these watchers is that you can share a signal |
… | |
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248 | |
260 | |
249 | 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 |
250 | 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 |
251 | 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 |
252 | 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 |
253 | 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. |
254 | |
267 | |
255 | 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 | my $pid = fork or exit 5; |
256 | |
285 | |
257 | my $w = AnyEvent->child ( |
286 | my $w = AnyEvent->child ( |
258 | pid => 1333, |
287 | pid => $pid, |
259 | cb => sub { |
288 | cb => sub { |
260 | my ($pid, $status) = @_; |
289 | my ($pid, $status) = @_; |
261 | warn "pid $pid exited with status $status"; |
290 | warn "pid $pid exited with status $status"; |
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291 | $done->send; |
262 | }, |
292 | }, |
263 | ); |
293 | ); |
264 | |
294 | |
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295 | # do something else, then wait for process exit |
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296 | $done->recv; |
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297 | |
265 | =head2 CONDITION VARIABLES |
298 | =head2 CONDITION VARIABLES |
266 | |
299 | |
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300 | If you are familiar with some event loops you will know that all of them |
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301 | require you to run some blocking "loop", "run" or similar function that |
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302 | will actively watch for new events and call your callbacks. |
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303 | |
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304 | AnyEvent is different, it expects somebody else to run the event loop and |
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305 | will only block when necessary (usually when told by the user). |
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306 | |
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307 | The instrument to do that is called a "condition variable", so called |
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308 | because they represent a condition that must become true. |
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309 | |
267 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
268 | method without any arguments. |
311 | >> method, usually without arguments. The only argument pair allowed is |
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312 | C<cb>, which specifies a callback to be called when the condition variable |
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313 | becomes true. |
269 | |
314 | |
270 | A condition variable waits for a condition - precisely that the C<< |
315 | After creation, the conditon variable is "false" until it becomes "true" |
271 | ->broadcast >> method has been called. |
316 | by calling the C<send> method. |
272 | |
317 | |
273 | They are very useful to signal that a condition has been fulfilled, for |
318 | Condition variables are similar to callbacks, except that you can |
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319 | optionally wait for them. They can also be called merge points - points |
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320 | in time where multiple outstandign events have been processed. And yet |
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321 | another way to call them is transations - each condition variable can be |
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322 | used to represent a transaction, which finishes at some point and delivers |
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323 | a result. |
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324 | |
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325 | Condition variables are very useful to signal that something has finished, |
274 | example, if you write a module that does asynchronous http requests, |
326 | for example, if you write a module that does asynchronous http requests, |
275 | then a condition variable would be the ideal candidate to signal the |
327 | then a condition variable would be the ideal candidate to signal the |
276 | availability of results. |
328 | availability of results. The user can either act when the callback is |
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329 | called or can synchronously C<< ->recv >> for the results. |
277 | |
330 | |
278 | You can also use condition variables to block your main program until |
331 | You can also use them to simulate traditional event loops - for example, |
279 | an event occurs - for example, you could C<< ->wait >> in your main |
332 | you can block your main program until an event occurs - for example, you |
280 | program until the user clicks the Quit button in your app, which would C<< |
333 | could C<< ->recv >> in your main program until the user clicks the Quit |
281 | ->broadcast >> the "quit" event. |
334 | button of your app, which would C<< ->send >> the "quit" event. |
282 | |
335 | |
283 | Note that condition variables recurse into the event loop - if you have |
336 | Note that condition variables recurse into the event loop - if you have |
284 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
337 | two pieces of code that call C<< ->recv >> in a round-robbin fashion, you |
285 | lose. Therefore, condition variables are good to export to your caller, but |
338 | lose. Therefore, condition variables are good to export to your caller, but |
286 | you should avoid making a blocking wait yourself, at least in callbacks, |
339 | you should avoid making a blocking wait yourself, at least in callbacks, |
287 | as this asks for trouble. |
340 | as this asks for trouble. |
288 | |
341 | |
289 | This object has two methods: |
342 | Condition variables are represented by hash refs in perl, and the keys |
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343 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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344 | easy (it is often useful to build your own transaction class on top of |
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345 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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346 | it's C<new> method in your own C<new> method. |
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347 | |
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348 | There are two "sides" to a condition variable - the "producer side" which |
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349 | eventually calls C<< -> send >>, and the "consumer side", which waits |
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350 | for the send to occur. |
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351 | |
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352 | Example: |
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353 | |
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354 | # wait till the result is ready |
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355 | my $result_ready = AnyEvent->condvar; |
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356 | |
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357 | # do something such as adding a timer |
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358 | # or socket watcher the calls $result_ready->send |
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359 | # when the "result" is ready. |
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360 | # in this case, we simply use a timer: |
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361 | my $w = AnyEvent->timer ( |
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362 | after => 1, |
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363 | cb => sub { $result_ready->send }, |
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364 | ); |
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365 | |
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366 | # this "blocks" (while handling events) till the callback |
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367 | # calls send |
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368 | $result_ready->recv; |
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369 | |
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370 | =head3 METHODS FOR PRODUCERS |
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371 | |
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372 | These methods should only be used by the producing side, i.e. the |
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373 | code/module that eventually sends the signal. Note that it is also |
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374 | the producer side which creates the condvar in most cases, but it isn't |
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375 | uncommon for the consumer to create it as well. |
290 | |
376 | |
291 | =over 4 |
377 | =over 4 |
292 | |
378 | |
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379 | =item $cv->send (...) |
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380 | |
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381 | Flag the condition as ready - a running C<< ->recv >> and all further |
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382 | calls to C<recv> will (eventually) return after this method has been |
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383 | called. If nobody is waiting the send will be remembered. |
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384 | |
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385 | If a callback has been set on the condition variable, it is called |
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386 | immediately from within send. |
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387 | |
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388 | Any arguments passed to the C<send> call will be returned by all |
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389 | future C<< ->recv >> calls. |
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390 | |
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391 | =item $cv->croak ($error) |
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392 | |
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393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
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394 | C<Carp::croak> with the given error message/object/scalar. |
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395 | |
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396 | This can be used to signal any errors to the condition variable |
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397 | user/consumer. |
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398 | |
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399 | =item $cv->begin ([group callback]) |
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400 | |
293 | =item $cv->wait |
401 | =item $cv->end |
294 | |
402 | |
295 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
403 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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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<< ->send >>, but that is not required. If no |
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413 | callback was set, C<send> 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->send (\%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<send> 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 | C<send> 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 | =over 4 |
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458 | |
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459 | =item $cv->recv |
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460 | |
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461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
296 | called on c<$cv>, while servicing other watchers normally. |
462 | >> methods have been called on c<$cv>, while servicing other watchers |
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463 | normally. |
297 | |
464 | |
298 | You can only wait once on a condition - additional calls will return |
465 | You can only wait once on a condition - additional calls are valid but |
299 | immediately. |
466 | will return immediately. |
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467 | |
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468 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
469 | function will call C<croak>. |
|
|
470 | |
|
|
471 | In list context, all parameters passed to C<send> will be returned, |
|
|
472 | in scalar context only the first one will be returned. |
300 | |
473 | |
301 | Not all event models support a blocking wait - some die in that case |
474 | Not all event models support a blocking wait - some die in that case |
302 | (programs might want to do that to stay interactive), so I<if you are |
475 | (programs might want to do that to stay interactive), so I<if you are |
303 | using this from a module, never require a blocking wait>, but let the |
476 | using this from a module, never require a blocking wait>, but let the |
304 | caller decide whether the call will block or not (for example, by coupling |
477 | caller decide whether the call will block or not (for example, by coupling |
305 | condition variables with some kind of request results and supporting |
478 | condition variables with some kind of request results and supporting |
306 | callbacks so the caller knows that getting the result will not block, |
479 | callbacks so the caller knows that getting the result will not block, |
307 | while still suppporting blocking waits if the caller so desires). |
480 | while still suppporting blocking waits if the caller so desires). |
308 | |
481 | |
309 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
310 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
311 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
312 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
485 | can supply. |
313 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
|
|
314 | from different coroutines, however). |
|
|
315 | |
486 | |
316 | =item $cv->broadcast |
487 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
488 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
489 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
490 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
491 | coroutine (one that doesn't run the event loop). |
317 | |
492 | |
318 | Flag the condition as ready - a running C<< ->wait >> and all further |
493 | You can ensure that C<< -recv >> never blocks by setting a callback and |
319 | calls to C<wait> will (eventually) return after this method has been |
494 | only calling C<< ->recv >> from within that callback (or at a later |
320 | called. If nobody is waiting the broadcast will be remembered.. |
495 | time). This will work even when the event loop does not support blocking |
|
|
496 | waits otherwise. |
|
|
497 | |
|
|
498 | =item $bool = $cv->ready |
|
|
499 | |
|
|
500 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
501 | C<croak> have been called. |
|
|
502 | |
|
|
503 | =item $cb = $cv->cb ([new callback]) |
|
|
504 | |
|
|
505 | This is a mutator function that returns the callback set and optionally |
|
|
506 | replaces it before doing so. |
|
|
507 | |
|
|
508 | The callback will be called when the condition becomes "true", i.e. when |
|
|
509 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
510 | or at any later time is guaranteed not to block. |
321 | |
511 | |
322 | =back |
512 | =back |
323 | |
|
|
324 | Example: |
|
|
325 | |
|
|
326 | # wait till the result is ready |
|
|
327 | my $result_ready = AnyEvent->condvar; |
|
|
328 | |
|
|
329 | # do something such as adding a timer |
|
|
330 | # or socket watcher the calls $result_ready->broadcast |
|
|
331 | # when the "result" is ready. |
|
|
332 | # in this case, we simply use a timer: |
|
|
333 | my $w = AnyEvent->timer ( |
|
|
334 | after => 1, |
|
|
335 | cb => sub { $result_ready->broadcast }, |
|
|
336 | ); |
|
|
337 | |
|
|
338 | # this "blocks" (while handling events) till the watcher |
|
|
339 | # calls broadcast |
|
|
340 | $result_ready->wait; |
|
|
341 | |
513 | |
342 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
514 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
343 | |
515 | |
344 | =over 4 |
516 | =over 4 |
345 | |
517 | |
… | |
… | |
351 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
523 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
352 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
524 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
353 | |
525 | |
354 | The known classes so far are: |
526 | The known classes so far are: |
355 | |
527 | |
356 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
357 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
358 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
528 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
359 | AnyEvent::Impl::Event based on Event, also second best choice :) |
529 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
530 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
360 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
531 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
361 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
532 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
362 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
533 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
363 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
534 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
535 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
536 | |
|
|
537 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
538 | watching file handles. However, you can use WxWidgets through the |
|
|
539 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
540 | second, which was considered to be too horrible to even consider for |
|
|
541 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
542 | it's adaptor. |
|
|
543 | |
|
|
544 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
545 | autodetecting them. |
364 | |
546 | |
365 | =item AnyEvent::detect |
547 | =item AnyEvent::detect |
366 | |
548 | |
367 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
549 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
368 | if necessary. You should only call this function right before you would |
550 | if necessary. You should only call this function right before you would |
369 | have created an AnyEvent watcher anyway, that is, as late as possible at |
551 | have created an AnyEvent watcher anyway, that is, as late as possible at |
370 | runtime. |
552 | runtime. |
371 | |
553 | |
|
|
554 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
555 | |
|
|
556 | Arranges for the code block to be executed as soon as the event model is |
|
|
557 | autodetected (or immediately if this has already happened). |
|
|
558 | |
|
|
559 | If called in scalar or list context, then it creates and returns an object |
|
|
560 | that automatically removes the callback again when it is destroyed. See |
|
|
561 | L<Coro::BDB> for a case where this is useful. |
|
|
562 | |
|
|
563 | =item @AnyEvent::post_detect |
|
|
564 | |
|
|
565 | If there are any code references in this array (you can C<push> to it |
|
|
566 | before or after loading AnyEvent), then they will called directly after |
|
|
567 | the event loop has been chosen. |
|
|
568 | |
|
|
569 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
570 | if it contains a true value then the event loop has already been detected, |
|
|
571 | and the array will be ignored. |
|
|
572 | |
|
|
573 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
574 | |
372 | =back |
575 | =back |
373 | |
576 | |
374 | =head1 WHAT TO DO IN A MODULE |
577 | =head1 WHAT TO DO IN A MODULE |
375 | |
578 | |
376 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
579 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
… | |
… | |
379 | Be careful when you create watchers in the module body - AnyEvent will |
582 | Be careful when you create watchers in the module body - AnyEvent will |
380 | decide which event module to use as soon as the first method is called, so |
583 | decide which event module to use as soon as the first method is called, so |
381 | by calling AnyEvent in your module body you force the user of your module |
584 | by calling AnyEvent in your module body you force the user of your module |
382 | to load the event module first. |
585 | to load the event module first. |
383 | |
586 | |
384 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
587 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
385 | the C<< ->broadcast >> method has been called on it already. This is |
588 | the C<< ->send >> method has been called on it already. This is |
386 | because it will stall the whole program, and the whole point of using |
589 | because it will stall the whole program, and the whole point of using |
387 | events is to stay interactive. |
590 | events is to stay interactive. |
388 | |
591 | |
389 | It is fine, however, to call C<< ->wait >> when the user of your module |
592 | It is fine, however, to call C<< ->recv >> when the user of your module |
390 | requests it (i.e. if you create a http request object ad have a method |
593 | requests it (i.e. if you create a http request object ad have a method |
391 | called C<results> that returns the results, it should call C<< ->wait >> |
594 | called C<results> that returns the results, it should call C<< ->recv >> |
392 | freely, as the user of your module knows what she is doing. always). |
595 | freely, as the user of your module knows what she is doing. always). |
393 | |
596 | |
394 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
597 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
395 | |
598 | |
396 | There will always be a single main program - the only place that should |
599 | There will always be a single main program - the only place that should |
… | |
… | |
410 | |
613 | |
411 | You can chose to use a rather inefficient pure-perl implementation by |
614 | You can chose to use a rather inefficient pure-perl implementation by |
412 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
615 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
413 | behaviour everywhere, but letting AnyEvent chose is generally better. |
616 | behaviour everywhere, but letting AnyEvent chose is generally better. |
414 | |
617 | |
|
|
618 | =head1 OTHER MODULES |
|
|
619 | |
|
|
620 | The following is a non-exhaustive list of additional modules that use |
|
|
621 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
622 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
623 | available via CPAN. |
|
|
624 | |
|
|
625 | =over 4 |
|
|
626 | |
|
|
627 | =item L<AnyEvent::Util> |
|
|
628 | |
|
|
629 | Contains various utility functions that replace often-used but blocking |
|
|
630 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
631 | |
|
|
632 | =item L<AnyEvent::Handle> |
|
|
633 | |
|
|
634 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
635 | |
|
|
636 | =item L<AnyEvent::HTTPD> |
|
|
637 | |
|
|
638 | Provides a simple web application server framework. |
|
|
639 | |
|
|
640 | =item L<AnyEvent::DNS> |
|
|
641 | |
|
|
642 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
643 | L<AnyEvent::Util> offers. |
|
|
644 | |
|
|
645 | =item L<AnyEvent::FastPing> |
|
|
646 | |
|
|
647 | The fastest ping in the west. |
|
|
648 | |
|
|
649 | =item L<Net::IRC3> |
|
|
650 | |
|
|
651 | AnyEvent based IRC client module family. |
|
|
652 | |
|
|
653 | =item L<Net::XMPP2> |
|
|
654 | |
|
|
655 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
656 | |
|
|
657 | =item L<Net::FCP> |
|
|
658 | |
|
|
659 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
660 | of AnyEvent. |
|
|
661 | |
|
|
662 | =item L<Event::ExecFlow> |
|
|
663 | |
|
|
664 | High level API for event-based execution flow control. |
|
|
665 | |
|
|
666 | =item L<Coro> |
|
|
667 | |
|
|
668 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
669 | |
|
|
670 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
671 | |
|
|
672 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
673 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
674 | together. |
|
|
675 | |
|
|
676 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
677 | |
|
|
678 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
679 | IO::AIO and AnyEvent together. |
|
|
680 | |
|
|
681 | =item L<IO::Lambda> |
|
|
682 | |
|
|
683 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
684 | |
|
|
685 | =back |
|
|
686 | |
415 | =cut |
687 | =cut |
416 | |
688 | |
417 | package AnyEvent; |
689 | package AnyEvent; |
418 | |
690 | |
419 | no warnings; |
691 | no warnings; |
420 | use strict; |
692 | use strict; |
421 | |
693 | |
422 | use Carp; |
694 | use Carp; |
423 | |
695 | |
424 | our $VERSION = '3.12'; |
696 | our $VERSION = '3.51'; |
425 | our $MODEL; |
697 | our $MODEL; |
426 | |
698 | |
427 | our $AUTOLOAD; |
699 | our $AUTOLOAD; |
428 | our @ISA; |
700 | our @ISA; |
429 | |
701 | |
430 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
702 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
431 | |
703 | |
432 | our @REGISTRY; |
704 | our @REGISTRY; |
433 | |
705 | |
434 | my @models = ( |
706 | my @models = ( |
435 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
436 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
437 | [EV:: => AnyEvent::Impl::EV::], |
707 | [EV:: => AnyEvent::Impl::EV::], |
438 | [Event:: => AnyEvent::Impl::Event::], |
708 | [Event:: => AnyEvent::Impl::Event::], |
|
|
709 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
710 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
711 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
712 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
713 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
439 | [Glib:: => AnyEvent::Impl::Glib::], |
714 | [Glib:: => AnyEvent::Impl::Glib::], |
440 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
441 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
442 | [Event::Lib:: => AnyEvent::Impl::EventLib::], |
715 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
716 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
717 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
443 | ); |
718 | ); |
444 | |
719 | |
445 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
720 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
|
|
721 | |
|
|
722 | our @post_detect; |
|
|
723 | |
|
|
724 | sub post_detect(&) { |
|
|
725 | my ($cb) = @_; |
|
|
726 | |
|
|
727 | if ($MODEL) { |
|
|
728 | $cb->(); |
|
|
729 | |
|
|
730 | 1 |
|
|
731 | } else { |
|
|
732 | push @post_detect, $cb; |
|
|
733 | |
|
|
734 | defined wantarray |
|
|
735 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
736 | : () |
|
|
737 | } |
|
|
738 | } |
|
|
739 | |
|
|
740 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
741 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
742 | } |
446 | |
743 | |
447 | sub detect() { |
744 | sub detect() { |
448 | unless ($MODEL) { |
745 | unless ($MODEL) { |
449 | no strict 'refs'; |
746 | no strict 'refs'; |
450 | |
747 | |
451 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
748 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
452 | my $model = "AnyEvent::Impl::$1"; |
749 | my $model = "AnyEvent::Impl::$1"; |
453 | if (eval "require $model") { |
750 | if (eval "require $model") { |
454 | $MODEL = $model; |
751 | $MODEL = $model; |
455 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
752 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
753 | } else { |
|
|
754 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
456 | } |
755 | } |
457 | } |
756 | } |
458 | |
757 | |
459 | # check for already loaded models |
758 | # check for already loaded models |
460 | unless ($MODEL) { |
759 | unless ($MODEL) { |
… | |
… | |
482 | last; |
781 | last; |
483 | } |
782 | } |
484 | } |
783 | } |
485 | |
784 | |
486 | $MODEL |
785 | $MODEL |
487 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; |
786 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
488 | } |
787 | } |
489 | } |
788 | } |
490 | |
789 | |
491 | unshift @ISA, $MODEL; |
790 | unshift @ISA, $MODEL; |
492 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
791 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
792 | |
|
|
793 | (shift @post_detect)->() while @post_detect; |
493 | } |
794 | } |
494 | |
795 | |
495 | $MODEL |
796 | $MODEL |
496 | } |
797 | } |
497 | |
798 | |
… | |
… | |
507 | $class->$func (@_); |
808 | $class->$func (@_); |
508 | } |
809 | } |
509 | |
810 | |
510 | package AnyEvent::Base; |
811 | package AnyEvent::Base; |
511 | |
812 | |
512 | # default implementation for ->condvar, ->wait, ->broadcast |
813 | # default implementation for ->condvar |
513 | |
814 | |
514 | sub condvar { |
815 | sub condvar { |
515 | bless \my $flag, "AnyEvent::Base::CondVar" |
816 | bless {}, AnyEvent::CondVar:: |
516 | } |
|
|
517 | |
|
|
518 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
519 | ${$_[0]}++; |
|
|
520 | } |
|
|
521 | |
|
|
522 | sub AnyEvent::Base::CondVar::wait { |
|
|
523 | AnyEvent->one_event while !${$_[0]}; |
|
|
524 | } |
817 | } |
525 | |
818 | |
526 | # default implementation for ->signal |
819 | # default implementation for ->signal |
527 | |
820 | |
528 | our %SIG_CB; |
821 | our %SIG_CB; |
… | |
… | |
602 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
895 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
603 | |
896 | |
604 | undef $CHLD_W unless keys %PID_CB; |
897 | undef $CHLD_W unless keys %PID_CB; |
605 | } |
898 | } |
606 | |
899 | |
|
|
900 | package AnyEvent::CondVar; |
|
|
901 | |
|
|
902 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
903 | |
|
|
904 | package AnyEvent::CondVar::Base; |
|
|
905 | |
|
|
906 | sub _send { |
|
|
907 | # nop |
|
|
908 | } |
|
|
909 | |
|
|
910 | sub send { |
|
|
911 | my $cv = shift; |
|
|
912 | $cv->{_ae_sent} = [@_]; |
|
|
913 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
914 | $cv->_send; |
|
|
915 | } |
|
|
916 | |
|
|
917 | sub croak { |
|
|
918 | $_[0]{_ae_croak} = $_[1]; |
|
|
919 | $_[0]->send; |
|
|
920 | } |
|
|
921 | |
|
|
922 | sub ready { |
|
|
923 | $_[0]{_ae_sent} |
|
|
924 | } |
|
|
925 | |
|
|
926 | sub _wait { |
|
|
927 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
928 | } |
|
|
929 | |
|
|
930 | sub recv { |
|
|
931 | $_[0]->_wait; |
|
|
932 | |
|
|
933 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
934 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
935 | } |
|
|
936 | |
|
|
937 | sub cb { |
|
|
938 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
939 | $_[0]{_ae_cb} |
|
|
940 | } |
|
|
941 | |
|
|
942 | sub begin { |
|
|
943 | ++$_[0]{_ae_counter}; |
|
|
944 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
945 | } |
|
|
946 | |
|
|
947 | sub end { |
|
|
948 | return if --$_[0]{_ae_counter}; |
|
|
949 | &{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb}; |
|
|
950 | } |
|
|
951 | |
|
|
952 | # undocumented/compatibility with pre-3.4 |
|
|
953 | *broadcast = \&send; |
|
|
954 | *wait = \&_wait; |
|
|
955 | |
607 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
956 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
608 | |
957 | |
609 | This is an advanced topic that you do not normally need to use AnyEvent in |
958 | This is an advanced topic that you do not normally need to use AnyEvent in |
610 | a module. This section is only of use to event loop authors who want to |
959 | a module. This section is only of use to event loop authors who want to |
611 | provide AnyEvent compatibility. |
960 | provide AnyEvent compatibility. |
… | |
… | |
653 | |
1002 | |
654 | =over 4 |
1003 | =over 4 |
655 | |
1004 | |
656 | =item C<PERL_ANYEVENT_VERBOSE> |
1005 | =item C<PERL_ANYEVENT_VERBOSE> |
657 | |
1006 | |
|
|
1007 | By default, AnyEvent will be completely silent except in fatal |
|
|
1008 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1009 | talkative. |
|
|
1010 | |
|
|
1011 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1012 | conditions, such as not being able to load the event model specified by |
|
|
1013 | C<PERL_ANYEVENT_MODEL>. |
|
|
1014 | |
658 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
1015 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
659 | model it chooses. |
1016 | model it chooses. |
660 | |
1017 | |
661 | =item C<PERL_ANYEVENT_MODEL> |
1018 | =item C<PERL_ANYEVENT_MODEL> |
662 | |
1019 | |
… | |
… | |
676 | |
1033 | |
677 | =back |
1034 | =back |
678 | |
1035 | |
679 | =head1 EXAMPLE PROGRAM |
1036 | =head1 EXAMPLE PROGRAM |
680 | |
1037 | |
681 | The following program uses an IO watcher to read data from STDIN, a timer |
1038 | The following program uses an I/O watcher to read data from STDIN, a timer |
682 | to display a message once per second, and a condition variable to quit the |
1039 | to display a message once per second, and a condition variable to quit the |
683 | program when the user enters quit: |
1040 | program when the user enters quit: |
684 | |
1041 | |
685 | use AnyEvent; |
1042 | use AnyEvent; |
686 | |
1043 | |
… | |
… | |
691 | poll => 'r', |
1048 | poll => 'r', |
692 | cb => sub { |
1049 | cb => sub { |
693 | warn "io event <$_[0]>\n"; # will always output <r> |
1050 | warn "io event <$_[0]>\n"; # will always output <r> |
694 | chomp (my $input = <STDIN>); # read a line |
1051 | chomp (my $input = <STDIN>); # read a line |
695 | warn "read: $input\n"; # output what has been read |
1052 | warn "read: $input\n"; # output what has been read |
696 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1053 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
697 | }, |
1054 | }, |
698 | ); |
1055 | ); |
699 | |
1056 | |
700 | my $time_watcher; # can only be used once |
1057 | my $time_watcher; # can only be used once |
701 | |
1058 | |
… | |
… | |
706 | }); |
1063 | }); |
707 | } |
1064 | } |
708 | |
1065 | |
709 | new_timer; # create first timer |
1066 | new_timer; # create first timer |
710 | |
1067 | |
711 | $cv->wait; # wait until user enters /^q/i |
1068 | $cv->recv; # wait until user enters /^q/i |
712 | |
1069 | |
713 | =head1 REAL-WORLD EXAMPLE |
1070 | =head1 REAL-WORLD EXAMPLE |
714 | |
1071 | |
715 | Consider the L<Net::FCP> module. It features (among others) the following |
1072 | Consider the L<Net::FCP> module. It features (among others) the following |
716 | API calls, which are to freenet what HTTP GET requests are to http: |
1073 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
772 | |
1129 | |
773 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1130 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
774 | |
1131 | |
775 | if (end-of-file or data complete) { |
1132 | if (end-of-file or data complete) { |
776 | $txn->{result} = $txn->{buf}; |
1133 | $txn->{result} = $txn->{buf}; |
777 | $txn->{finished}->broadcast; |
1134 | $txn->{finished}->send; |
778 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1135 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
779 | } |
1136 | } |
780 | |
1137 | |
781 | The C<result> method, finally, just waits for the finished signal (if the |
1138 | The C<result> method, finally, just waits for the finished signal (if the |
782 | request was already finished, it doesn't wait, of course, and returns the |
1139 | request was already finished, it doesn't wait, of course, and returns the |
783 | data: |
1140 | data: |
784 | |
1141 | |
785 | $txn->{finished}->wait; |
1142 | $txn->{finished}->recv; |
786 | return $txn->{result}; |
1143 | return $txn->{result}; |
787 | |
1144 | |
788 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1145 | The actual code goes further and collects all errors (C<die>s, exceptions) |
789 | that occured during request processing. The C<result> method detects |
1146 | that occured during request processing. The C<result> method detects |
790 | whether an exception as thrown (it is stored inside the $txn object) |
1147 | whether an exception as thrown (it is stored inside the $txn object) |
… | |
… | |
825 | |
1182 | |
826 | my $quit = AnyEvent->condvar; |
1183 | my $quit = AnyEvent->condvar; |
827 | |
1184 | |
828 | $fcp->txn_client_get ($url)->cb (sub { |
1185 | $fcp->txn_client_get ($url)->cb (sub { |
829 | ... |
1186 | ... |
830 | $quit->broadcast; |
1187 | $quit->send; |
831 | }); |
1188 | }); |
832 | |
1189 | |
833 | $quit->wait; |
1190 | $quit->recv; |
|
|
1191 | |
|
|
1192 | |
|
|
1193 | =head1 BENCHMARKS |
|
|
1194 | |
|
|
1195 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1196 | over the event loops themselves and to give you an impression of the speed |
|
|
1197 | of various event loops I prepared some benchmarks. |
|
|
1198 | |
|
|
1199 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1200 | |
|
|
1201 | Here is a benchmark of various supported event models used natively and |
|
|
1202 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
1203 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1204 | which it is), lets them fire exactly once and destroys them again. |
|
|
1205 | |
|
|
1206 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1207 | distribution. |
|
|
1208 | |
|
|
1209 | =head3 Explanation of the columns |
|
|
1210 | |
|
|
1211 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1212 | different event models feature vastly different performances, each event |
|
|
1213 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1214 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1215 | would probably take thousands of years if asked to process the same number |
|
|
1216 | of watchers as EV in this benchmark. |
|
|
1217 | |
|
|
1218 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1219 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1220 | and Perl-based overheads. |
|
|
1221 | |
|
|
1222 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1223 | takes to create a single watcher. The callback is a closure shared between |
|
|
1224 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1225 | and memory usage is not included in the figures. |
|
|
1226 | |
|
|
1227 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1228 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1229 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1230 | signal the end of this phase. |
|
|
1231 | |
|
|
1232 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1233 | watcher. |
|
|
1234 | |
|
|
1235 | =head3 Results |
|
|
1236 | |
|
|
1237 | name watchers bytes create invoke destroy comment |
|
|
1238 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1239 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1240 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1241 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1242 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1243 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1244 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1245 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1246 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1247 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1248 | |
|
|
1249 | =head3 Discussion |
|
|
1250 | |
|
|
1251 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1252 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1253 | can never compete with an event loop that uses epoll when the number of |
|
|
1254 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1255 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1256 | boost. |
|
|
1257 | |
|
|
1258 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1259 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1260 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1261 | higher number of watchers at a disadvantage. |
|
|
1262 | |
|
|
1263 | To put the range of results into perspective, consider that on the |
|
|
1264 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1265 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1266 | cycles with POE. |
|
|
1267 | |
|
|
1268 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1269 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1270 | far less memory than any other event loop and is still faster than Event |
|
|
1271 | natively. |
|
|
1272 | |
|
|
1273 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1274 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1275 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1276 | adds very little overhead in itself. Like any select-based backend its |
|
|
1277 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1278 | them active), of course, but this was not subject of this benchmark. |
|
|
1279 | |
|
|
1280 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1281 | cost, but overall scores in on the third place. |
|
|
1282 | |
|
|
1283 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1284 | faster callback invocation and overall ends up in the same class as |
|
|
1285 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1286 | watchers increases the processing time by more than a factor of four, |
|
|
1287 | making it completely unusable when using larger numbers of watchers |
|
|
1288 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1289 | inefficiencies of C<poll> do not account for this). |
|
|
1290 | |
|
|
1291 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1292 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1293 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1294 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1295 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1296 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1297 | above). |
|
|
1298 | |
|
|
1299 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1300 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1301 | be tested because it wasn't working) shows abysmal performance and |
|
|
1302 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1303 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1304 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1305 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1306 | implementation. |
|
|
1307 | |
|
|
1308 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1309 | for the performance issues, though, as session creation overhead is |
|
|
1310 | small compared to execution of the state machine, which is coded pretty |
|
|
1311 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1312 | using multiple sessions is not a good approach, especially regarding |
|
|
1313 | memory usage, even the author of POE could not come up with a faster |
|
|
1314 | design). |
|
|
1315 | |
|
|
1316 | =head3 Summary |
|
|
1317 | |
|
|
1318 | =over 4 |
|
|
1319 | |
|
|
1320 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1321 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1322 | performance with or without AnyEvent. |
|
|
1323 | |
|
|
1324 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1325 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1326 | adds AnyEvent significant overhead. |
|
|
1327 | |
|
|
1328 | =item * You should avoid POE like the plague if you want performance or |
|
|
1329 | reasonable memory usage. |
|
|
1330 | |
|
|
1331 | =back |
|
|
1332 | |
|
|
1333 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1334 | |
|
|
1335 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
1336 | creating a number of "servers": each server consists of a socketpair, a |
|
|
1337 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1338 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1339 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1340 | |
|
|
1341 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1342 | are active at any one point (so there is a constant number of active |
|
|
1343 | fds for each loop iterstaion, but which fds these are is random). The |
|
|
1344 | timeout is reset each time something is read because that reflects how |
|
|
1345 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1346 | |
|
|
1347 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 |
|
|
1348 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1349 | connections, most of which are idle at any one point in time. |
|
|
1350 | |
|
|
1351 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1352 | distribution. |
|
|
1353 | |
|
|
1354 | =head3 Explanation of the columns |
|
|
1355 | |
|
|
1356 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1357 | each server has a read and write socket end). |
|
|
1358 | |
|
|
1359 | I<create> is the time it takes to create a socketpair (which is |
|
|
1360 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1361 | |
|
|
1362 | I<request>, the most important value, is the time it takes to handle a |
|
|
1363 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1364 | it to another server. This includes deleting the old timeout and creating |
|
|
1365 | a new one that moves the timeout into the future. |
|
|
1366 | |
|
|
1367 | =head3 Results |
|
|
1368 | |
|
|
1369 | name sockets create request |
|
|
1370 | EV 20000 69.01 11.16 |
|
|
1371 | Perl 20000 73.32 35.87 |
|
|
1372 | Event 20000 212.62 257.32 |
|
|
1373 | Glib 20000 651.16 1896.30 |
|
|
1374 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1375 | |
|
|
1376 | =head3 Discussion |
|
|
1377 | |
|
|
1378 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1379 | particular event loop. |
|
|
1380 | |
|
|
1381 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1382 | is relatively high, though. |
|
|
1383 | |
|
|
1384 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1385 | loops Event and Glib. |
|
|
1386 | |
|
|
1387 | Event suffers from high setup time as well (look at its code and you will |
|
|
1388 | understand why). Callback invocation also has a high overhead compared to |
|
|
1389 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1390 | uses select or poll in basically all documented configurations. |
|
|
1391 | |
|
|
1392 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1393 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1394 | |
|
|
1395 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1396 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1397 | it uses a C-based event loop in this case. |
|
|
1398 | |
|
|
1399 | =head3 Summary |
|
|
1400 | |
|
|
1401 | =over 4 |
|
|
1402 | |
|
|
1403 | =item * The pure perl implementation performs extremely well. |
|
|
1404 | |
|
|
1405 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1406 | |
|
|
1407 | =back |
|
|
1408 | |
|
|
1409 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1410 | |
|
|
1411 | While event loops should scale (and select-based ones do not...) even to |
|
|
1412 | large servers, most programs we (or I :) actually write have only a few |
|
|
1413 | I/O watchers. |
|
|
1414 | |
|
|
1415 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1416 | case, but it uses only eight "servers", of which three are active at any |
|
|
1417 | one time. This should reflect performance for a small server relatively |
|
|
1418 | well. |
|
|
1419 | |
|
|
1420 | The columns are identical to the previous table. |
|
|
1421 | |
|
|
1422 | =head3 Results |
|
|
1423 | |
|
|
1424 | name sockets create request |
|
|
1425 | EV 16 20.00 6.54 |
|
|
1426 | Perl 16 25.75 12.62 |
|
|
1427 | Event 16 81.27 35.86 |
|
|
1428 | Glib 16 32.63 15.48 |
|
|
1429 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1430 | |
|
|
1431 | =head3 Discussion |
|
|
1432 | |
|
|
1433 | The benchmark tries to test the performance of a typical small |
|
|
1434 | server. While knowing how various event loops perform is interesting, keep |
|
|
1435 | in mind that their overhead in this case is usually not as important, due |
|
|
1436 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1437 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1438 | them). |
|
|
1439 | |
|
|
1440 | EV is again fastest. |
|
|
1441 | |
|
|
1442 | Perl again comes second. It is noticably faster than the C-based event |
|
|
1443 | loops Event and Glib, although the difference is too small to really |
|
|
1444 | matter. |
|
|
1445 | |
|
|
1446 | POE also performs much better in this case, but is is still far behind the |
|
|
1447 | others. |
|
|
1448 | |
|
|
1449 | =head3 Summary |
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1450 | |
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|
1451 | =over 4 |
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1452 | |
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|
1453 | =item * C-based event loops perform very well with small number of |
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1454 | watchers, as the management overhead dominates. |
|
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1455 | |
|
|
1456 | =back |
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|
1457 | |
834 | |
1458 | |
835 | =head1 FORK |
1459 | =head1 FORK |
836 | |
1460 | |
837 | Most event libraries are not fork-safe. The ones who are usually are |
1461 | Most event libraries are not fork-safe. The ones who are usually are |
838 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1462 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1463 | calls. Only L<EV> is fully fork-aware. |
839 | |
1464 | |
840 | If you have to fork, you must either do so I<before> creating your first |
1465 | If you have to fork, you must either do so I<before> creating your first |
841 | watcher OR you must not use AnyEvent at all in the child. |
1466 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1467 | |
842 | |
1468 | |
843 | =head1 SECURITY CONSIDERATIONS |
1469 | =head1 SECURITY CONSIDERATIONS |
844 | |
1470 | |
845 | AnyEvent can be forced to load any event model via |
1471 | AnyEvent can be forced to load any event model via |
846 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
1472 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
… | |
… | |
854 | |
1480 | |
855 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1481 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
856 | |
1482 | |
857 | use AnyEvent; |
1483 | use AnyEvent; |
858 | |
1484 | |
|
|
1485 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1486 | be used to probe what backend is used and gain other information (which is |
|
|
1487 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
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1488 | |
|
|
1489 | |
859 | =head1 SEE ALSO |
1490 | =head1 SEE ALSO |
860 | |
1491 | |
861 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1492 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
862 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
1493 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
863 | L<Event::Lib>. |
|
|
864 | |
1494 | |
865 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1495 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
866 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
1496 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
867 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>. |
1497 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1498 | L<AnyEvent::Impl::POE>. |
|
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1499 | |
|
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1500 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
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1501 | |
|
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1502 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
868 | |
1503 | |
869 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1504 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
|
|
1505 | |
870 | |
1506 | |
871 | =head1 AUTHOR |
1507 | =head1 AUTHOR |
872 | |
1508 | |
873 | Marc Lehmann <schmorp@schmorp.de> |
1509 | Marc Lehmann <schmorp@schmorp.de> |
874 | http://home.schmorp.de/ |
1510 | http://home.schmorp.de/ |