1 | =head1 NAME |
1 | =head1 => NAME |
2 | |
2 | |
3 | AnyEvent - ??? |
3 | AnyEvent - provide framework for multiple event loops |
|
|
4 | |
|
|
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
6 | |
8 | |
|
|
9 | use AnyEvent; |
|
|
10 | |
|
|
11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
|
|
12 | ... |
|
|
13 | }); |
|
|
14 | |
|
|
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
|
|
16 | ... |
|
|
17 | }); |
|
|
18 | |
|
|
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
|
|
20 | $w->send; # wake up current and all future recv's |
|
|
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
|
|
22 | |
|
|
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
|
|
24 | |
|
|
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
|
|
26 | nowadays. So what is different about AnyEvent? |
|
|
27 | |
|
|
28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
|
|
29 | policy> and AnyEvent is I<small and efficient>. |
|
|
30 | |
|
|
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
|
|
32 | interfaces to whatever event model the main program happens to use in a |
|
|
33 | pragmatic way. For event models and certain classes of immortals alike, |
|
|
34 | the statement "there can only be one" is a bitter reality: In general, |
|
|
35 | only one event loop can be active at the same time in a process. AnyEvent |
|
|
36 | helps hiding the differences between those event loops. |
|
|
37 | |
|
|
38 | The goal of AnyEvent is to offer module authors the ability to do event |
|
|
39 | programming (waiting for I/O or timer events) without subscribing to a |
|
|
40 | religion, a way of living, and most importantly: without forcing your |
|
|
41 | module users into the same thing by forcing them to use the same event |
|
|
42 | model you use. |
|
|
43 | |
|
|
44 | For modules like POE or IO::Async (which is a total misnomer as it is |
|
|
45 | actually doing all I/O I<synchronously>...), using them in your module is |
|
|
46 | like joining a cult: After you joined, you are dependent on them and you |
|
|
47 | cannot use anything else, as it is simply incompatible to everything that |
|
|
48 | isn't itself. What's worse, all the potential users of your module are |
|
|
49 | I<also> forced to use the same event loop you use. |
|
|
50 | |
|
|
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
|
|
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
|
|
53 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if |
|
|
54 | your module uses one of those, every user of your module has to use it, |
|
|
55 | too. But if your module uses AnyEvent, it works transparently with all |
|
|
56 | event models it supports (including stuff like POE and IO::Async, as long |
|
|
57 | as those use one of the supported event loops. It is trivial to add new |
|
|
58 | event loops to AnyEvent, too, so it is future-proof). |
|
|
59 | |
|
|
60 | In addition to being free of having to use I<the one and only true event |
|
|
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
|
|
62 | modules, you get an enormous amount of code and strict rules you have to |
|
|
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
|
|
64 | offering the functionality that is necessary, in as thin as a wrapper as |
|
|
65 | technically possible. |
|
|
66 | |
|
|
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 |
|
|
69 | model, you should I<not> use this module. |
|
|
70 | |
7 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
8 | |
72 | |
|
|
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
|
|
74 | allows module authors to utilise an event loop without forcing module |
|
|
75 | users to use the same event loop (as only a single event loop can coexist |
|
|
76 | peacefully at any one time). |
|
|
77 | |
|
|
78 | The interface itself is vaguely similar, but not identical to the L<Event> |
|
|
79 | module. |
|
|
80 | |
|
|
81 | During the first call of any watcher-creation method, the module tries |
|
|
82 | to detect the currently loaded event loop by probing whether one of the |
|
|
83 | following modules is already loaded: L<EV>, |
|
|
84 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
|
|
85 | L<POE>. The first one found is used. If none are found, the module tries |
|
|
86 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
|
|
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 |
|
|
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
|
|
90 | very efficient, but should work everywhere. |
|
|
91 | |
|
|
92 | Because AnyEvent first checks for modules that are already loaded, loading |
|
|
93 | an event model explicitly before first using AnyEvent will likely make |
|
|
94 | that model the default. For example: |
|
|
95 | |
|
|
96 | use Tk; |
|
|
97 | use AnyEvent; |
|
|
98 | |
|
|
99 | # .. AnyEvent will likely default to Tk |
|
|
100 | |
|
|
101 | The I<likely> means that, if any module loads another event model and |
|
|
102 | starts using it, all bets are off. Maybe you should tell their authors to |
|
|
103 | use AnyEvent so their modules work together with others seamlessly... |
|
|
104 | |
|
|
105 | The pure-perl implementation of AnyEvent is called |
|
|
106 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
|
|
107 | explicitly. |
|
|
108 | |
|
|
109 | =head1 WATCHERS |
|
|
110 | |
|
|
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
|
|
112 | stores relevant data for each kind of event you are waiting for, such as |
|
|
113 | the callback to call, the file handle to watch, etc. |
|
|
114 | |
|
|
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
|
|
116 | creating a watcher it will immediately "watch" for events and invoke the |
|
|
117 | callback when the event occurs (of course, only when the event model |
|
|
118 | is in control). |
|
|
119 | |
|
|
120 | To disable the watcher you have to destroy it (e.g. by setting the |
|
|
121 | variable you store it in to C<undef> or otherwise deleting all references |
|
|
122 | to it). |
|
|
123 | |
|
|
124 | All watchers are created by calling a method on the C<AnyEvent> class. |
|
|
125 | |
|
|
126 | Many watchers either are used with "recursion" (repeating timers for |
|
|
127 | example), or need to refer to their watcher object in other ways. |
|
|
128 | |
|
|
129 | An any way to achieve that is this pattern: |
|
|
130 | |
|
|
131 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
|
|
132 | # you can use $w here, for example to undef it |
|
|
133 | undef $w; |
|
|
134 | }); |
|
|
135 | |
|
|
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 |
|
|
138 | declared. |
|
|
139 | |
|
|
140 | =head2 I/O WATCHERS |
|
|
141 | |
|
|
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: |
|
|
144 | |
|
|
145 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
|
|
146 | for events. C<poll> must be a string that is either C<r> or C<w>, |
|
|
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 |
|
|
149 | becomes ready. |
|
|
150 | |
|
|
151 | Although the callback might get passed parameters, their value and |
|
|
152 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
153 | callbacks cannot use arguments passed to I/O watcher callbacks. |
|
|
154 | |
|
|
155 | The I/O watcher might use the underlying file descriptor or a copy of it. |
|
|
156 | You must not close a file handle as long as any watcher is active on the |
|
|
157 | underlying file descriptor. |
|
|
158 | |
|
|
159 | Some event loops issue spurious readyness notifications, so you should |
|
|
160 | always use non-blocking calls when reading/writing from/to your file |
|
|
161 | handles. |
|
|
162 | |
|
|
163 | Example: |
|
|
164 | |
|
|
165 | # wait for readability of STDIN, then read a line and disable the watcher |
|
|
166 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
167 | chomp (my $input = <STDIN>); |
|
|
168 | warn "read: $input\n"; |
|
|
169 | undef $w; |
|
|
170 | }); |
|
|
171 | |
|
|
172 | =head2 TIME WATCHERS |
|
|
173 | |
|
|
174 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
|
|
175 | method with the following mandatory arguments: |
|
|
176 | |
|
|
177 | C<after> specifies after how many seconds (fractional values are |
|
|
178 | supported) the callback should be invoked. C<cb> is the callback to invoke |
|
|
179 | in that case. |
|
|
180 | |
|
|
181 | Although the callback might get passed parameters, their value and |
|
|
182 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
183 | callbacks cannot use arguments passed to time watcher callbacks. |
|
|
184 | |
|
|
185 | The timer callback will be invoked at most once: if you want a repeating |
|
|
186 | timer you have to create a new watcher (this is a limitation by both Tk |
|
|
187 | and Glib). |
|
|
188 | |
|
|
189 | Example: |
|
|
190 | |
|
|
191 | # fire an event after 7.7 seconds |
|
|
192 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
|
|
193 | warn "timeout\n"; |
|
|
194 | }); |
|
|
195 | |
|
|
196 | # to cancel the timer: |
|
|
197 | undef $w; |
|
|
198 | |
|
|
199 | Example 2: |
|
|
200 | |
|
|
201 | # fire an event after 0.5 seconds, then roughly every second |
|
|
202 | my $w; |
|
|
203 | |
|
|
204 | my $cb = sub { |
|
|
205 | # cancel the old timer while creating a new one |
|
|
206 | $w = AnyEvent->timer (after => 1, cb => $cb); |
|
|
207 | }; |
|
|
208 | |
|
|
209 | # start the "loop" by creating the first watcher |
|
|
210 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
|
|
211 | |
|
|
212 | =head3 TIMING ISSUES |
|
|
213 | |
|
|
214 | There are two ways to handle timers: based on real time (relative, "fire |
|
|
215 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
|
|
216 | o'clock"). |
|
|
217 | |
|
|
218 | While most event loops expect timers to specified in a relative way, they |
|
|
219 | use absolute time internally. This makes a difference when your clock |
|
|
220 | "jumps", for example, when ntp decides to set your clock backwards from |
|
|
221 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
|
|
222 | fire "after" a second might actually take six years to finally fire. |
|
|
223 | |
|
|
224 | AnyEvent cannot compensate for this. The only event loop that is conscious |
|
|
225 | about these issues is L<EV>, which offers both relative (ev_timer, based |
|
|
226 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
|
|
227 | timers. |
|
|
228 | |
|
|
229 | AnyEvent always prefers relative timers, if available, matching the |
|
|
230 | AnyEvent API. |
|
|
231 | |
|
|
232 | =head2 SIGNAL WATCHERS |
|
|
233 | |
|
|
234 | You can watch for signals using a signal watcher, C<signal> is the signal |
|
|
235 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
|
|
236 | be invoked whenever a signal occurs. |
|
|
237 | |
|
|
238 | Although the callback might get passed parameters, their value and |
|
|
239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
|
|
240 | callbacks cannot use arguments passed to signal watcher callbacks. |
|
|
241 | |
|
|
242 | Multiple signal occurrences can be clumped together into one callback |
|
|
243 | invocation, and callback invocation will be synchronous. Synchronous means |
|
|
244 | that it might take a while until the signal gets handled by the process, |
|
|
245 | but it is guaranteed not to interrupt any other callbacks. |
|
|
246 | |
|
|
247 | The main advantage of using these watchers is that you can share a signal |
|
|
248 | between multiple watchers. |
|
|
249 | |
|
|
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
|
|
251 | directly will likely not work correctly. |
|
|
252 | |
|
|
253 | Example: exit on SIGINT |
|
|
254 | |
|
|
255 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
256 | |
|
|
257 | =head2 CHILD PROCESS WATCHERS |
|
|
258 | |
|
|
259 | You can also watch on a child process exit and catch its exit status. |
|
|
260 | |
|
|
261 | The child process is specified by the C<pid> argument (if set to C<0>, it |
|
|
262 | watches for any child process exit). The watcher will trigger as often |
|
|
263 | as status change for the child are received. This works by installing a |
|
|
264 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
|
|
265 | and exit status (as returned by waitpid), so unlike other watcher types, |
|
|
266 | you I<can> rely on child watcher callback arguments. |
|
|
267 | |
|
|
268 | There is a slight catch to child watchers, however: you usually start them |
|
|
269 | I<after> the child process was created, and this means the process could |
|
|
270 | have exited already (and no SIGCHLD will be sent anymore). |
|
|
271 | |
|
|
272 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
273 | event models that I<do> handle this correctly, they usually need to be |
|
|
274 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
275 | |
|
|
276 | This means you cannot create a child watcher as the very first thing in an |
|
|
277 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
278 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
|
|
279 | |
|
|
280 | Example: fork a process and wait for it |
|
|
281 | |
|
|
282 | my $done = AnyEvent->condvar; |
|
|
283 | |
|
|
284 | my $pid = fork or exit 5; |
|
|
285 | |
|
|
286 | my $w = AnyEvent->child ( |
|
|
287 | pid => $pid, |
|
|
288 | cb => sub { |
|
|
289 | my ($pid, $status) = @_; |
|
|
290 | warn "pid $pid exited with status $status"; |
|
|
291 | $done->send; |
|
|
292 | }, |
|
|
293 | ); |
|
|
294 | |
|
|
295 | # do something else, then wait for process exit |
|
|
296 | $done->recv; |
|
|
297 | |
|
|
298 | =head2 CONDITION VARIABLES |
|
|
299 | |
|
|
300 | If you are familiar with some event loops you will know that all of them |
|
|
301 | require you to run some blocking "loop", "run" or similar function that |
|
|
302 | will actively watch for new events and call your callbacks. |
|
|
303 | |
|
|
304 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
305 | will only block when necessary (usually when told by the user). |
|
|
306 | |
|
|
307 | The instrument to do that is called a "condition variable", so called |
|
|
308 | because they represent a condition that must become true. |
|
|
309 | |
|
|
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
|
|
311 | >> method, usually without arguments. The only argument pair allowed is |
|
|
312 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
313 | becomes true. |
|
|
314 | |
|
|
315 | After creation, the condition variable is "false" until it becomes "true" |
|
|
316 | by calling the C<send> method (or calling the condition variable as if it |
|
|
317 | were a callback). |
|
|
318 | |
|
|
319 | Condition variables are similar to callbacks, except that you can |
|
|
320 | optionally wait for them. They can also be called merge points - points |
|
|
321 | in time where multiple outstanding events have been processed. And yet |
|
|
322 | another way to call them is transactions - each condition variable can be |
|
|
323 | used to represent a transaction, which finishes at some point and delivers |
|
|
324 | a result. |
|
|
325 | |
|
|
326 | Condition variables are very useful to signal that something has finished, |
|
|
327 | for example, if you write a module that does asynchronous http requests, |
|
|
328 | then a condition variable would be the ideal candidate to signal the |
|
|
329 | availability of results. The user can either act when the callback is |
|
|
330 | called or can synchronously C<< ->recv >> for the results. |
|
|
331 | |
|
|
332 | You can also use them to simulate traditional event loops - for example, |
|
|
333 | you can block your main program until an event occurs - for example, you |
|
|
334 | could C<< ->recv >> in your main program until the user clicks the Quit |
|
|
335 | button of your app, which would C<< ->send >> the "quit" event. |
|
|
336 | |
|
|
337 | Note that condition variables recurse into the event loop - if you have |
|
|
338 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
|
|
339 | lose. Therefore, condition variables are good to export to your caller, but |
|
|
340 | you should avoid making a blocking wait yourself, at least in callbacks, |
|
|
341 | as this asks for trouble. |
|
|
342 | |
|
|
343 | Condition variables are represented by hash refs in perl, and the keys |
|
|
344 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
345 | easy (it is often useful to build your own transaction class on top of |
|
|
346 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
347 | it's C<new> method in your own C<new> method. |
|
|
348 | |
|
|
349 | There are two "sides" to a condition variable - the "producer side" which |
|
|
350 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
351 | for the send to occur. |
|
|
352 | |
|
|
353 | Example: wait for a timer. |
|
|
354 | |
|
|
355 | # wait till the result is ready |
|
|
356 | my $result_ready = AnyEvent->condvar; |
|
|
357 | |
|
|
358 | # do something such as adding a timer |
|
|
359 | # or socket watcher the calls $result_ready->send |
|
|
360 | # when the "result" is ready. |
|
|
361 | # in this case, we simply use a timer: |
|
|
362 | my $w = AnyEvent->timer ( |
|
|
363 | after => 1, |
|
|
364 | cb => sub { $result_ready->send }, |
|
|
365 | ); |
|
|
366 | |
|
|
367 | # this "blocks" (while handling events) till the callback |
|
|
368 | # calls send |
|
|
369 | $result_ready->recv; |
|
|
370 | |
|
|
371 | Example: wait for a timer, but take advantage of the fact that |
|
|
372 | condition variables are also code references. |
|
|
373 | |
|
|
374 | my $done = AnyEvent->condvar; |
|
|
375 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
376 | $done->recv; |
|
|
377 | |
|
|
378 | =head3 METHODS FOR PRODUCERS |
|
|
379 | |
|
|
380 | These methods should only be used by the producing side, i.e. the |
|
|
381 | code/module that eventually sends the signal. Note that it is also |
|
|
382 | the producer side which creates the condvar in most cases, but it isn't |
|
|
383 | uncommon for the consumer to create it as well. |
|
|
384 | |
9 | =over 4 |
385 | =over 4 |
10 | |
386 | |
|
|
387 | =item $cv->send (...) |
|
|
388 | |
|
|
389 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
390 | calls to C<recv> will (eventually) return after this method has been |
|
|
391 | called. If nobody is waiting the send will be remembered. |
|
|
392 | |
|
|
393 | If a callback has been set on the condition variable, it is called |
|
|
394 | immediately from within send. |
|
|
395 | |
|
|
396 | Any arguments passed to the C<send> call will be returned by all |
|
|
397 | future C<< ->recv >> calls. |
|
|
398 | |
|
|
399 | Condition variables are overloaded so one can call them directly (as a |
|
|
400 | code reference). Calling them directly is the same as calling C<send>. |
|
|
401 | |
|
|
402 | =item $cv->croak ($error) |
|
|
403 | |
|
|
404 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
405 | C<Carp::croak> with the given error message/object/scalar. |
|
|
406 | |
|
|
407 | This can be used to signal any errors to the condition variable |
|
|
408 | user/consumer. |
|
|
409 | |
|
|
410 | =item $cv->begin ([group callback]) |
|
|
411 | |
|
|
412 | =item $cv->end |
|
|
413 | |
|
|
414 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
415 | |
|
|
416 | These two methods can be used to combine many transactions/events into |
|
|
417 | one. For example, a function that pings many hosts in parallel might want |
|
|
418 | to use a condition variable for the whole process. |
|
|
419 | |
|
|
420 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
421 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
422 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
423 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
424 | callback was set, C<send> will be called without any arguments. |
|
|
425 | |
|
|
426 | Let's clarify this with the ping example: |
|
|
427 | |
|
|
428 | my $cv = AnyEvent->condvar; |
|
|
429 | |
|
|
430 | my %result; |
|
|
431 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
432 | |
|
|
433 | for my $host (@list_of_hosts) { |
|
|
434 | $cv->begin; |
|
|
435 | ping_host_then_call_callback $host, sub { |
|
|
436 | $result{$host} = ...; |
|
|
437 | $cv->end; |
|
|
438 | }; |
|
|
439 | } |
|
|
440 | |
|
|
441 | $cv->end; |
|
|
442 | |
|
|
443 | This code fragment supposedly pings a number of hosts and calls |
|
|
444 | C<send> after results for all then have have been gathered - in any |
|
|
445 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
446 | each ping request and calls C<end> when it has received some result for |
|
|
447 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
448 | results arrive is not relevant. |
|
|
449 | |
|
|
450 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
451 | loop, which serves two important purposes: first, it sets the callback |
|
|
452 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
453 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
454 | doesn't execute once). |
|
|
455 | |
|
|
456 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
457 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
458 | is called at least once, and then, for each subrequest you start, call |
|
|
459 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
460 | |
|
|
461 | =back |
|
|
462 | |
|
|
463 | =head3 METHODS FOR CONSUMERS |
|
|
464 | |
|
|
465 | These methods should only be used by the consuming side, i.e. the |
|
|
466 | code awaits the condition. |
|
|
467 | |
|
|
468 | =over 4 |
|
|
469 | |
|
|
470 | =item $cv->recv |
|
|
471 | |
|
|
472 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
|
|
473 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
474 | normally. |
|
|
475 | |
|
|
476 | You can only wait once on a condition - additional calls are valid but |
|
|
477 | will return immediately. |
|
|
478 | |
|
|
479 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
480 | function will call C<croak>. |
|
|
481 | |
|
|
482 | In list context, all parameters passed to C<send> will be returned, |
|
|
483 | in scalar context only the first one will be returned. |
|
|
484 | |
|
|
485 | Not all event models support a blocking wait - some die in that case |
|
|
486 | (programs might want to do that to stay interactive), so I<if you are |
|
|
487 | using this from a module, never require a blocking wait>, but let the |
|
|
488 | caller decide whether the call will block or not (for example, by coupling |
|
|
489 | condition variables with some kind of request results and supporting |
|
|
490 | callbacks so the caller knows that getting the result will not block, |
|
|
491 | while still supporting blocking waits if the caller so desires). |
|
|
492 | |
|
|
493 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
|
|
494 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
|
|
495 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
|
|
496 | can supply. |
|
|
497 | |
|
|
498 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
499 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
500 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
501 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
502 | coroutine (one that doesn't run the event loop). |
|
|
503 | |
|
|
504 | You can ensure that C<< -recv >> never blocks by setting a callback and |
|
|
505 | only calling C<< ->recv >> from within that callback (or at a later |
|
|
506 | time). This will work even when the event loop does not support blocking |
|
|
507 | waits otherwise. |
|
|
508 | |
|
|
509 | =item $bool = $cv->ready |
|
|
510 | |
|
|
511 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
512 | C<croak> have been called. |
|
|
513 | |
|
|
514 | =item $cb = $cv->cb ([new callback]) |
|
|
515 | |
|
|
516 | This is a mutator function that returns the callback set and optionally |
|
|
517 | replaces it before doing so. |
|
|
518 | |
|
|
519 | The callback will be called when the condition becomes "true", i.e. when |
|
|
520 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
521 | or at any later time is guaranteed not to block. |
|
|
522 | |
|
|
523 | =back |
|
|
524 | |
|
|
525 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
|
|
526 | |
|
|
527 | =over 4 |
|
|
528 | |
|
|
529 | =item $AnyEvent::MODEL |
|
|
530 | |
|
|
531 | Contains C<undef> until the first watcher is being created. Then it |
|
|
532 | contains the event model that is being used, which is the name of the |
|
|
533 | Perl class implementing the model. This class is usually one of the |
|
|
534 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
|
|
535 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
|
|
536 | |
|
|
537 | The known classes so far are: |
|
|
538 | |
|
|
539 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
540 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
541 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
542 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
543 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
544 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
545 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
546 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
547 | |
|
|
548 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
549 | watching file handles. However, you can use WxWidgets through the |
|
|
550 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
551 | second, which was considered to be too horrible to even consider for |
|
|
552 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
553 | it's adaptor. |
|
|
554 | |
|
|
555 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
556 | autodetecting them. |
|
|
557 | |
|
|
558 | =item AnyEvent::detect |
|
|
559 | |
|
|
560 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
|
|
561 | if necessary. You should only call this function right before you would |
|
|
562 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
563 | runtime. |
|
|
564 | |
|
|
565 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
566 | |
|
|
567 | Arranges for the code block to be executed as soon as the event model is |
|
|
568 | autodetected (or immediately if this has already happened). |
|
|
569 | |
|
|
570 | If called in scalar or list context, then it creates and returns an object |
|
|
571 | that automatically removes the callback again when it is destroyed. See |
|
|
572 | L<Coro::BDB> for a case where this is useful. |
|
|
573 | |
|
|
574 | =item @AnyEvent::post_detect |
|
|
575 | |
|
|
576 | If there are any code references in this array (you can C<push> to it |
|
|
577 | before or after loading AnyEvent), then they will called directly after |
|
|
578 | the event loop has been chosen. |
|
|
579 | |
|
|
580 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
581 | if it contains a true value then the event loop has already been detected, |
|
|
582 | and the array will be ignored. |
|
|
583 | |
|
|
584 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
585 | |
|
|
586 | =back |
|
|
587 | |
|
|
588 | =head1 WHAT TO DO IN A MODULE |
|
|
589 | |
|
|
590 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
|
|
591 | freely, but you should not load a specific event module or rely on it. |
|
|
592 | |
|
|
593 | Be careful when you create watchers in the module body - AnyEvent will |
|
|
594 | decide which event module to use as soon as the first method is called, so |
|
|
595 | by calling AnyEvent in your module body you force the user of your module |
|
|
596 | to load the event module first. |
|
|
597 | |
|
|
598 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
599 | the C<< ->send >> method has been called on it already. This is |
|
|
600 | because it will stall the whole program, and the whole point of using |
|
|
601 | events is to stay interactive. |
|
|
602 | |
|
|
603 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
604 | requests it (i.e. if you create a http request object ad have a method |
|
|
605 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
606 | freely, as the user of your module knows what she is doing. always). |
|
|
607 | |
|
|
608 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
|
|
609 | |
|
|
610 | There will always be a single main program - the only place that should |
|
|
611 | dictate which event model to use. |
|
|
612 | |
|
|
613 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
614 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
615 | decide which implementation to chose if some module relies on it. |
|
|
616 | |
|
|
617 | If the main program relies on a specific event model. For example, in |
|
|
618 | Gtk2 programs you have to rely on the Glib module. You should load the |
|
|
619 | event module before loading AnyEvent or any module that uses it: generally |
|
|
620 | speaking, you should load it as early as possible. The reason is that |
|
|
621 | modules might create watchers when they are loaded, and AnyEvent will |
|
|
622 | decide on the event model to use as soon as it creates watchers, and it |
|
|
623 | might chose the wrong one unless you load the correct one yourself. |
|
|
624 | |
|
|
625 | You can chose to use a rather inefficient pure-perl implementation by |
|
|
626 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
|
|
627 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
628 | |
|
|
629 | =head1 OTHER MODULES |
|
|
630 | |
|
|
631 | The following is a non-exhaustive list of additional modules that use |
|
|
632 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
633 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
634 | available via CPAN. |
|
|
635 | |
|
|
636 | =over 4 |
|
|
637 | |
|
|
638 | =item L<AnyEvent::Util> |
|
|
639 | |
|
|
640 | Contains various utility functions that replace often-used but blocking |
|
|
641 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
642 | |
|
|
643 | =item L<AnyEvent::Handle> |
|
|
644 | |
|
|
645 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
646 | |
|
|
647 | =item L<AnyEvent::Socket> |
|
|
648 | |
|
|
649 | Provides various utility functions for (internet protocol) sockets, |
|
|
650 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
651 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
652 | |
|
|
653 | =item L<AnyEvent::HTTPD> |
|
|
654 | |
|
|
655 | Provides a simple web application server framework. |
|
|
656 | |
|
|
657 | =item L<AnyEvent::DNS> |
|
|
658 | |
|
|
659 | Provides rich asynchronous DNS resolver capabilities. |
|
|
660 | |
|
|
661 | =item L<AnyEvent::FastPing> |
|
|
662 | |
|
|
663 | The fastest ping in the west. |
|
|
664 | |
|
|
665 | =item L<Net::IRC3> |
|
|
666 | |
|
|
667 | AnyEvent based IRC client module family. |
|
|
668 | |
|
|
669 | =item L<Net::XMPP2> |
|
|
670 | |
|
|
671 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
672 | |
|
|
673 | =item L<Net::FCP> |
|
|
674 | |
|
|
675 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
676 | of AnyEvent. |
|
|
677 | |
|
|
678 | =item L<Event::ExecFlow> |
|
|
679 | |
|
|
680 | High level API for event-based execution flow control. |
|
|
681 | |
|
|
682 | =item L<Coro> |
|
|
683 | |
|
|
684 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
685 | |
|
|
686 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
687 | |
|
|
688 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
689 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
690 | together. |
|
|
691 | |
|
|
692 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
693 | |
|
|
694 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
695 | IO::AIO and AnyEvent together. |
|
|
696 | |
|
|
697 | =item L<IO::Lambda> |
|
|
698 | |
|
|
699 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
700 | |
|
|
701 | =back |
|
|
702 | |
11 | =cut |
703 | =cut |
12 | |
704 | |
13 | package AnyEvent; |
705 | package AnyEvent; |
14 | |
706 | |
|
|
707 | no warnings; |
|
|
708 | use strict; |
|
|
709 | |
15 | use Carp; |
710 | use Carp; |
16 | |
711 | |
17 | $VERSION = 0.1; |
712 | our $VERSION = '4.03'; |
|
|
713 | our $MODEL; |
18 | |
714 | |
19 | no warnings; |
715 | our $AUTOLOAD; |
|
|
716 | our @ISA; |
|
|
717 | |
|
|
718 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
|
|
719 | |
|
|
720 | our @REGISTRY; |
|
|
721 | |
|
|
722 | our %PROTOCOL; # (ipv4|ipv6) => (1|2) |
|
|
723 | |
|
|
724 | { |
|
|
725 | my $idx; |
|
|
726 | $PROTOCOL{$_} = ++$idx |
|
|
727 | for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
728 | } |
20 | |
729 | |
21 | my @models = ( |
730 | my @models = ( |
22 | [Coro => Coro::Event::], |
731 | [EV:: => AnyEvent::Impl::EV::], |
23 | [Event => Event::], |
732 | [Event:: => AnyEvent::Impl::Event::], |
24 | [Glib => Glib::], |
733 | [Tk:: => AnyEvent::Impl::Tk::], |
25 | [Tk => Tk::], |
734 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
735 | [Prima:: => AnyEvent::Impl::POE::], |
|
|
736 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
737 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
738 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
739 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
740 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
741 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
26 | ); |
742 | ); |
27 | |
743 | |
|
|
744 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
|
|
745 | |
|
|
746 | our @post_detect; |
|
|
747 | |
|
|
748 | sub post_detect(&) { |
|
|
749 | my ($cb) = @_; |
|
|
750 | |
|
|
751 | if ($MODEL) { |
|
|
752 | $cb->(); |
|
|
753 | |
|
|
754 | 1 |
|
|
755 | } else { |
|
|
756 | push @post_detect, $cb; |
|
|
757 | |
|
|
758 | defined wantarray |
|
|
759 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
760 | : () |
|
|
761 | } |
|
|
762 | } |
|
|
763 | |
|
|
764 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
765 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
766 | } |
|
|
767 | |
|
|
768 | sub detect() { |
|
|
769 | unless ($MODEL) { |
|
|
770 | no strict 'refs'; |
|
|
771 | |
|
|
772 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
773 | my $model = "AnyEvent::Impl::$1"; |
|
|
774 | if (eval "require $model") { |
|
|
775 | $MODEL = $model; |
|
|
776 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
777 | } else { |
|
|
778 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
779 | } |
|
|
780 | } |
|
|
781 | |
|
|
782 | # check for already loaded models |
|
|
783 | unless ($MODEL) { |
|
|
784 | for (@REGISTRY, @models) { |
|
|
785 | my ($package, $model) = @$_; |
|
|
786 | if (${"$package\::VERSION"} > 0) { |
|
|
787 | if (eval "require $model") { |
|
|
788 | $MODEL = $model; |
|
|
789 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
|
|
790 | last; |
|
|
791 | } |
|
|
792 | } |
|
|
793 | } |
|
|
794 | |
|
|
795 | unless ($MODEL) { |
|
|
796 | # try to load a model |
|
|
797 | |
|
|
798 | for (@REGISTRY, @models) { |
|
|
799 | my ($package, $model) = @$_; |
|
|
800 | if (eval "require $package" |
|
|
801 | and ${"$package\::VERSION"} > 0 |
|
|
802 | and eval "require $model") { |
|
|
803 | $MODEL = $model; |
|
|
804 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
|
|
805 | last; |
|
|
806 | } |
|
|
807 | } |
|
|
808 | |
|
|
809 | $MODEL |
|
|
810 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
|
|
811 | } |
|
|
812 | } |
|
|
813 | |
|
|
814 | unshift @ISA, $MODEL; |
|
|
815 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
816 | |
|
|
817 | (shift @post_detect)->() while @post_detect; |
|
|
818 | } |
|
|
819 | |
|
|
820 | $MODEL |
|
|
821 | } |
|
|
822 | |
28 | sub AUTOLOAD { |
823 | sub AUTOLOAD { |
29 | $AUTOLOAD =~ s/.*://; |
824 | (my $func = $AUTOLOAD) =~ s/.*://; |
30 | |
825 | |
31 | for (@models) { |
826 | $method{$func} |
32 | my ($model, $package) = @$_; |
827 | or croak "$func: not a valid method for AnyEvent objects"; |
33 | if (defined ${"$package\::VERSION"}) { |
828 | |
34 | $EVENT = "AnyEvent::Impl::$model"; |
829 | detect unless $MODEL; |
35 | eval "require $EVENT"; die if $@; |
830 | |
36 | goto &{"$EVENT\::$AUTOLOAD"}; |
831 | my $class = shift; |
37 | } |
832 | $class->$func (@_); |
|
|
833 | } |
|
|
834 | |
|
|
835 | package AnyEvent::Base; |
|
|
836 | |
|
|
837 | # default implementation for ->condvar |
|
|
838 | |
|
|
839 | sub condvar { |
|
|
840 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
|
|
841 | } |
|
|
842 | |
|
|
843 | # default implementation for ->signal |
|
|
844 | |
|
|
845 | our %SIG_CB; |
|
|
846 | |
|
|
847 | sub signal { |
|
|
848 | my (undef, %arg) = @_; |
|
|
849 | |
|
|
850 | my $signal = uc $arg{signal} |
|
|
851 | or Carp::croak "required option 'signal' is missing"; |
|
|
852 | |
|
|
853 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
|
|
854 | $SIG{$signal} ||= sub { |
|
|
855 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
|
|
856 | }; |
|
|
857 | |
|
|
858 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
|
|
859 | } |
|
|
860 | |
|
|
861 | sub AnyEvent::Base::Signal::DESTROY { |
|
|
862 | my ($signal, $cb) = @{$_[0]}; |
|
|
863 | |
|
|
864 | delete $SIG_CB{$signal}{$cb}; |
|
|
865 | |
|
|
866 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
|
|
867 | } |
|
|
868 | |
|
|
869 | # default implementation for ->child |
|
|
870 | |
|
|
871 | our %PID_CB; |
|
|
872 | our $CHLD_W; |
|
|
873 | our $CHLD_DELAY_W; |
|
|
874 | our $PID_IDLE; |
|
|
875 | our $WNOHANG; |
|
|
876 | |
|
|
877 | sub _child_wait { |
|
|
878 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
879 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
880 | (values %{ $PID_CB{0} || {} }); |
38 | } |
881 | } |
39 | |
882 | |
40 | for (@models) { |
883 | undef $PID_IDLE; |
41 | my ($model, $package) = @$_; |
884 | } |
42 | $EVENT = "AnyEvent::Impl::$model"; |
885 | |
43 | if (eval "require $EVENT") { |
886 | sub _sigchld { |
44 | goto &{"$EVENT\::$AUTOLOAD"}; |
887 | # make sure we deliver these changes "synchronous" with the event loop. |
45 | } |
888 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
889 | undef $CHLD_DELAY_W; |
|
|
890 | &_child_wait; |
|
|
891 | }); |
|
|
892 | } |
|
|
893 | |
|
|
894 | sub child { |
|
|
895 | my (undef, %arg) = @_; |
|
|
896 | |
|
|
897 | defined (my $pid = $arg{pid} + 0) |
|
|
898 | or Carp::croak "required option 'pid' is missing"; |
|
|
899 | |
|
|
900 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
901 | |
|
|
902 | unless ($WNOHANG) { |
|
|
903 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
46 | } |
904 | } |
47 | |
905 | |
48 | die "No event module selected for AnyEvent and autodetect failed. Install any of these: Coro, Event, Glib or Tk."; |
906 | unless ($CHLD_W) { |
49 | } |
907 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
908 | # child could be a zombie already, so make at least one round |
|
|
909 | &_sigchld; |
|
|
910 | } |
50 | |
911 | |
51 | 1; |
912 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
|
|
913 | } |
52 | |
914 | |
|
|
915 | sub AnyEvent::Base::Child::DESTROY { |
|
|
916 | my ($pid, $cb) = @{$_[0]}; |
|
|
917 | |
|
|
918 | delete $PID_CB{$pid}{$cb}; |
|
|
919 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
920 | |
|
|
921 | undef $CHLD_W unless keys %PID_CB; |
|
|
922 | } |
|
|
923 | |
|
|
924 | package AnyEvent::CondVar; |
|
|
925 | |
|
|
926 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
927 | |
|
|
928 | package AnyEvent::CondVar::Base; |
|
|
929 | |
|
|
930 | use overload |
|
|
931 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
932 | fallback => 1; |
|
|
933 | |
|
|
934 | sub _send { |
|
|
935 | # nop |
|
|
936 | } |
|
|
937 | |
|
|
938 | sub send { |
|
|
939 | my $cv = shift; |
|
|
940 | $cv->{_ae_sent} = [@_]; |
|
|
941 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
942 | $cv->_send; |
|
|
943 | } |
|
|
944 | |
|
|
945 | sub croak { |
|
|
946 | $_[0]{_ae_croak} = $_[1]; |
|
|
947 | $_[0]->send; |
|
|
948 | } |
|
|
949 | |
|
|
950 | sub ready { |
|
|
951 | $_[0]{_ae_sent} |
|
|
952 | } |
|
|
953 | |
|
|
954 | sub _wait { |
|
|
955 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
956 | } |
|
|
957 | |
|
|
958 | sub recv { |
|
|
959 | $_[0]->_wait; |
|
|
960 | |
|
|
961 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
962 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
963 | } |
|
|
964 | |
|
|
965 | sub cb { |
|
|
966 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
967 | $_[0]{_ae_cb} |
|
|
968 | } |
|
|
969 | |
|
|
970 | sub begin { |
|
|
971 | ++$_[0]{_ae_counter}; |
|
|
972 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
973 | } |
|
|
974 | |
|
|
975 | sub end { |
|
|
976 | return if --$_[0]{_ae_counter}; |
|
|
977 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
978 | } |
|
|
979 | |
|
|
980 | # undocumented/compatibility with pre-3.4 |
|
|
981 | *broadcast = \&send; |
|
|
982 | *wait = \&_wait; |
|
|
983 | |
|
|
984 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
985 | |
|
|
986 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
987 | a module. This section is only of use to event loop authors who want to |
|
|
988 | provide AnyEvent compatibility. |
|
|
989 | |
|
|
990 | If you need to support another event library which isn't directly |
|
|
991 | supported by AnyEvent, you can supply your own interface to it by |
|
|
992 | pushing, before the first watcher gets created, the package name of |
|
|
993 | the event module and the package name of the interface to use onto |
|
|
994 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
|
|
995 | AnyEvent, so it is reasonably cheap. |
|
|
996 | |
|
|
997 | Example: |
|
|
998 | |
|
|
999 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
1000 | |
|
|
1001 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
|
|
1002 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
1003 | |
|
|
1004 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
1005 | will first check for the presence of urxvt by trying to C<use> the |
|
|
1006 | C<urxvt::anyevent> module. |
|
|
1007 | |
|
|
1008 | The class should provide implementations for all watcher types. See |
|
|
1009 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
|
|
1010 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
|
|
1011 | see the sources. |
|
|
1012 | |
|
|
1013 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
1014 | provide suitable (hopefully) replacements. |
|
|
1015 | |
|
|
1016 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
|
|
1017 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
1018 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
|
|
1019 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
|
|
1020 | I<rxvt-unicode> distribution. |
|
|
1021 | |
|
|
1022 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
|
|
1023 | condition variables: code blocking while waiting for a condition will |
|
|
1024 | C<die>. This still works with most modules/usages, and blocking calls must |
|
|
1025 | not be done in an interactive application, so it makes sense. |
|
|
1026 | |
|
|
1027 | =head1 ENVIRONMENT VARIABLES |
|
|
1028 | |
|
|
1029 | The following environment variables are used by this module: |
|
|
1030 | |
|
|
1031 | =over 4 |
|
|
1032 | |
|
|
1033 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1034 | |
|
|
1035 | By default, AnyEvent will be completely silent except in fatal |
|
|
1036 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1037 | talkative. |
|
|
1038 | |
|
|
1039 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1040 | conditions, such as not being able to load the event model specified by |
|
|
1041 | C<PERL_ANYEVENT_MODEL>. |
|
|
1042 | |
|
|
1043 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1044 | model it chooses. |
|
|
1045 | |
|
|
1046 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1047 | |
|
|
1048 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1049 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1050 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1051 | and the resulting module name is loaded and if the load was successful, |
|
|
1052 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1053 | auto detection and -probing. |
|
|
1054 | |
|
|
1055 | This functionality might change in future versions. |
|
|
1056 | |
|
|
1057 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1058 | could start your program like this: |
|
|
1059 | |
|
|
1060 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1061 | |
|
|
1062 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1063 | |
|
|
1064 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1065 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1066 | of auto probing). |
|
|
1067 | |
|
|
1068 | Must be set to a comma-separated list of protocols or address families, |
|
|
1069 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1070 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1071 | list. |
|
|
1072 | |
|
|
1073 | This variable can effectively be used for denial-of-service attacks |
|
|
1074 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1075 | small, as the program has to handle connection errors already- |
|
|
1076 | |
|
|
1077 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1078 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1079 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1080 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1081 | IPv6, but prefer IPv6 over IPv4. |
|
|
1082 | |
|
|
1083 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1084 | |
|
|
1085 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1086 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1087 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1088 | default. |
|
|
1089 | |
|
|
1090 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1091 | EDNS0 in its DNS requests. |
|
|
1092 | |
|
|
1093 | =back |
|
|
1094 | |
|
|
1095 | =head1 EXAMPLE PROGRAM |
|
|
1096 | |
|
|
1097 | The following program uses an I/O watcher to read data from STDIN, a timer |
|
|
1098 | to display a message once per second, and a condition variable to quit the |
|
|
1099 | program when the user enters quit: |
|
|
1100 | |
|
|
1101 | use AnyEvent; |
|
|
1102 | |
|
|
1103 | my $cv = AnyEvent->condvar; |
|
|
1104 | |
|
|
1105 | my $io_watcher = AnyEvent->io ( |
|
|
1106 | fh => \*STDIN, |
|
|
1107 | poll => 'r', |
|
|
1108 | cb => sub { |
|
|
1109 | warn "io event <$_[0]>\n"; # will always output <r> |
|
|
1110 | chomp (my $input = <STDIN>); # read a line |
|
|
1111 | warn "read: $input\n"; # output what has been read |
|
|
1112 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1113 | }, |
|
|
1114 | ); |
|
|
1115 | |
|
|
1116 | my $time_watcher; # can only be used once |
|
|
1117 | |
|
|
1118 | sub new_timer { |
|
|
1119 | $timer = AnyEvent->timer (after => 1, cb => sub { |
|
|
1120 | warn "timeout\n"; # print 'timeout' about every second |
|
|
1121 | &new_timer; # and restart the time |
|
|
1122 | }); |
|
|
1123 | } |
|
|
1124 | |
|
|
1125 | new_timer; # create first timer |
|
|
1126 | |
|
|
1127 | $cv->recv; # wait until user enters /^q/i |
|
|
1128 | |
|
|
1129 | =head1 REAL-WORLD EXAMPLE |
|
|
1130 | |
|
|
1131 | Consider the L<Net::FCP> module. It features (among others) the following |
|
|
1132 | API calls, which are to freenet what HTTP GET requests are to http: |
|
|
1133 | |
|
|
1134 | my $data = $fcp->client_get ($url); # blocks |
|
|
1135 | |
|
|
1136 | my $transaction = $fcp->txn_client_get ($url); # does not block |
|
|
1137 | $transaction->cb ( sub { ... } ); # set optional result callback |
|
|
1138 | my $data = $transaction->result; # possibly blocks |
|
|
1139 | |
|
|
1140 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
|
|
1141 | given URL and waits till the data has arrived. It is defined to be: |
|
|
1142 | |
|
|
1143 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
|
|
1144 | |
|
|
1145 | And in fact is automatically generated. This is the blocking API of |
|
|
1146 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
|
|
1147 | |
|
|
1148 | More complicated is C<txn_client_get>: It only creates a transaction |
|
|
1149 | (completion, result, ...) object and initiates the transaction. |
|
|
1150 | |
|
|
1151 | my $txn = bless { }, Net::FCP::Txn::; |
|
|
1152 | |
|
|
1153 | It also creates a condition variable that is used to signal the completion |
|
|
1154 | of the request: |
|
|
1155 | |
|
|
1156 | $txn->{finished} = AnyAvent->condvar; |
|
|
1157 | |
|
|
1158 | It then creates a socket in non-blocking mode. |
|
|
1159 | |
|
|
1160 | socket $txn->{fh}, ...; |
|
|
1161 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
|
|
1162 | connect $txn->{fh}, ... |
|
|
1163 | and !$!{EWOULDBLOCK} |
|
|
1164 | and !$!{EINPROGRESS} |
|
|
1165 | and Carp::croak "unable to connect: $!\n"; |
|
|
1166 | |
|
|
1167 | Then it creates a write-watcher which gets called whenever an error occurs |
|
|
1168 | or the connection succeeds: |
|
|
1169 | |
|
|
1170 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
|
|
1171 | |
|
|
1172 | And returns this transaction object. The C<fh_ready_w> callback gets |
|
|
1173 | called as soon as the event loop detects that the socket is ready for |
|
|
1174 | writing. |
|
|
1175 | |
|
|
1176 | The C<fh_ready_w> method makes the socket blocking again, writes the |
|
|
1177 | request data and replaces the watcher by a read watcher (waiting for reply |
|
|
1178 | data). The actual code is more complicated, but that doesn't matter for |
|
|
1179 | this example: |
|
|
1180 | |
|
|
1181 | fcntl $txn->{fh}, F_SETFL, 0; |
|
|
1182 | syswrite $txn->{fh}, $txn->{request} |
|
|
1183 | or die "connection or write error"; |
|
|
1184 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
|
|
1185 | |
|
|
1186 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
|
|
1187 | result and signals any possible waiters that the request has finished: |
|
|
1188 | |
|
|
1189 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
|
|
1190 | |
|
|
1191 | if (end-of-file or data complete) { |
|
|
1192 | $txn->{result} = $txn->{buf}; |
|
|
1193 | $txn->{finished}->send; |
|
|
1194 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
|
|
1195 | } |
|
|
1196 | |
|
|
1197 | The C<result> method, finally, just waits for the finished signal (if the |
|
|
1198 | request was already finished, it doesn't wait, of course, and returns the |
|
|
1199 | data: |
|
|
1200 | |
|
|
1201 | $txn->{finished}->recv; |
|
|
1202 | return $txn->{result}; |
|
|
1203 | |
|
|
1204 | The actual code goes further and collects all errors (C<die>s, exceptions) |
|
|
1205 | that occurred during request processing. The C<result> method detects |
|
|
1206 | whether an exception as thrown (it is stored inside the $txn object) |
|
|
1207 | and just throws the exception, which means connection errors and other |
|
|
1208 | problems get reported tot he code that tries to use the result, not in a |
|
|
1209 | random callback. |
|
|
1210 | |
|
|
1211 | All of this enables the following usage styles: |
|
|
1212 | |
|
|
1213 | 1. Blocking: |
|
|
1214 | |
|
|
1215 | my $data = $fcp->client_get ($url); |
|
|
1216 | |
|
|
1217 | 2. Blocking, but running in parallel: |
|
|
1218 | |
|
|
1219 | my @datas = map $_->result, |
|
|
1220 | map $fcp->txn_client_get ($_), |
|
|
1221 | @urls; |
|
|
1222 | |
|
|
1223 | Both blocking examples work without the module user having to know |
|
|
1224 | anything about events. |
|
|
1225 | |
|
|
1226 | 3a. Event-based in a main program, using any supported event module: |
|
|
1227 | |
|
|
1228 | use EV; |
|
|
1229 | |
|
|
1230 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
1231 | my $txn = shift; |
|
|
1232 | my $data = $txn->result; |
|
|
1233 | ... |
|
|
1234 | }); |
|
|
1235 | |
|
|
1236 | EV::loop; |
|
|
1237 | |
|
|
1238 | 3b. The module user could use AnyEvent, too: |
|
|
1239 | |
|
|
1240 | use AnyEvent; |
|
|
1241 | |
|
|
1242 | my $quit = AnyEvent->condvar; |
|
|
1243 | |
|
|
1244 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
1245 | ... |
|
|
1246 | $quit->send; |
|
|
1247 | }); |
|
|
1248 | |
|
|
1249 | $quit->recv; |
|
|
1250 | |
|
|
1251 | |
|
|
1252 | =head1 BENCHMARKS |
|
|
1253 | |
|
|
1254 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1255 | over the event loops themselves and to give you an impression of the speed |
|
|
1256 | of various event loops I prepared some benchmarks. |
|
|
1257 | |
|
|
1258 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1259 | |
|
|
1260 | Here is a benchmark of various supported event models used natively and |
|
|
1261 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1262 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1263 | which it is), lets them fire exactly once and destroys them again. |
|
|
1264 | |
|
|
1265 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1266 | distribution. |
|
|
1267 | |
|
|
1268 | =head3 Explanation of the columns |
|
|
1269 | |
|
|
1270 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1271 | different event models feature vastly different performances, each event |
|
|
1272 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1273 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1274 | would probably take thousands of years if asked to process the same number |
|
|
1275 | of watchers as EV in this benchmark. |
|
|
1276 | |
|
|
1277 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1278 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1279 | and Perl-based overheads. |
|
|
1280 | |
|
|
1281 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1282 | takes to create a single watcher. The callback is a closure shared between |
|
|
1283 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1284 | and memory usage is not included in the figures. |
|
|
1285 | |
|
|
1286 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1287 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1288 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1289 | signal the end of this phase. |
|
|
1290 | |
|
|
1291 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1292 | watcher. |
|
|
1293 | |
|
|
1294 | =head3 Results |
|
|
1295 | |
|
|
1296 | name watchers bytes create invoke destroy comment |
|
|
1297 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1298 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1299 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1300 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1301 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1302 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1303 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1304 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1305 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1306 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1307 | |
|
|
1308 | =head3 Discussion |
|
|
1309 | |
|
|
1310 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1311 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1312 | can never compete with an event loop that uses epoll when the number of |
|
|
1313 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1314 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1315 | boost. |
|
|
1316 | |
|
|
1317 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1318 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1319 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1320 | higher number of watchers at a disadvantage. |
|
|
1321 | |
|
|
1322 | To put the range of results into perspective, consider that on the |
|
|
1323 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1324 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1325 | cycles with POE. |
|
|
1326 | |
|
|
1327 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1328 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1329 | far less memory than any other event loop and is still faster than Event |
|
|
1330 | natively. |
|
|
1331 | |
|
|
1332 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1333 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1334 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1335 | adds very little overhead in itself. Like any select-based backend its |
|
|
1336 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1337 | them active), of course, but this was not subject of this benchmark. |
|
|
1338 | |
|
|
1339 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1340 | cost, but overall scores in on the third place. |
|
|
1341 | |
|
|
1342 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1343 | faster callback invocation and overall ends up in the same class as |
|
|
1344 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1345 | watchers increases the processing time by more than a factor of four, |
|
|
1346 | making it completely unusable when using larger numbers of watchers |
|
|
1347 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1348 | inefficiencies of C<poll> do not account for this). |
|
|
1349 | |
|
|
1350 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1351 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1352 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1353 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1354 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1355 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1356 | above). |
|
|
1357 | |
|
|
1358 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1359 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1360 | be tested because it wasn't working) shows abysmal performance and |
|
|
1361 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1362 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1363 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1364 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1365 | implementation. |
|
|
1366 | |
|
|
1367 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1368 | for the performance issues, though, as session creation overhead is |
|
|
1369 | small compared to execution of the state machine, which is coded pretty |
|
|
1370 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1371 | using multiple sessions is not a good approach, especially regarding |
|
|
1372 | memory usage, even the author of POE could not come up with a faster |
|
|
1373 | design). |
|
|
1374 | |
|
|
1375 | =head3 Summary |
|
|
1376 | |
|
|
1377 | =over 4 |
|
|
1378 | |
|
|
1379 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1380 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1381 | performance with or without AnyEvent. |
|
|
1382 | |
|
|
1383 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1384 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1385 | adds AnyEvent significant overhead. |
|
|
1386 | |
|
|
1387 | =item * You should avoid POE like the plague if you want performance or |
|
|
1388 | reasonable memory usage. |
|
|
1389 | |
|
|
1390 | =back |
|
|
1391 | |
|
|
1392 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1393 | |
|
|
1394 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1395 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1396 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1397 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1398 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1399 | |
|
|
1400 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1401 | are active at any one point (so there is a constant number of active |
|
|
1402 | fds for each loop iteration, but which fds these are is random). The |
|
|
1403 | timeout is reset each time something is read because that reflects how |
|
|
1404 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1405 | |
|
|
1406 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1407 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1408 | connections, most of which are idle at any one point in time. |
|
|
1409 | |
|
|
1410 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1411 | distribution. |
|
|
1412 | |
|
|
1413 | =head3 Explanation of the columns |
|
|
1414 | |
|
|
1415 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1416 | each server has a read and write socket end). |
|
|
1417 | |
|
|
1418 | I<create> is the time it takes to create a socket pair (which is |
|
|
1419 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1420 | |
|
|
1421 | I<request>, the most important value, is the time it takes to handle a |
|
|
1422 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1423 | it to another server. This includes deleting the old timeout and creating |
|
|
1424 | a new one that moves the timeout into the future. |
|
|
1425 | |
|
|
1426 | =head3 Results |
|
|
1427 | |
|
|
1428 | name sockets create request |
|
|
1429 | EV 20000 69.01 11.16 |
|
|
1430 | Perl 20000 73.32 35.87 |
|
|
1431 | Event 20000 212.62 257.32 |
|
|
1432 | Glib 20000 651.16 1896.30 |
|
|
1433 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1434 | |
|
|
1435 | =head3 Discussion |
|
|
1436 | |
|
|
1437 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1438 | particular event loop. |
|
|
1439 | |
|
|
1440 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1441 | is relatively high, though. |
|
|
1442 | |
|
|
1443 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1444 | loops Event and Glib. |
|
|
1445 | |
|
|
1446 | Event suffers from high setup time as well (look at its code and you will |
|
|
1447 | understand why). Callback invocation also has a high overhead compared to |
|
|
1448 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1449 | uses select or poll in basically all documented configurations. |
|
|
1450 | |
|
|
1451 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1452 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1453 | |
|
|
1454 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1455 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1456 | it uses a C-based event loop in this case. |
|
|
1457 | |
|
|
1458 | =head3 Summary |
|
|
1459 | |
|
|
1460 | =over 4 |
|
|
1461 | |
|
|
1462 | =item * The pure perl implementation performs extremely well. |
|
|
1463 | |
|
|
1464 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1465 | |
|
|
1466 | =back |
|
|
1467 | |
|
|
1468 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1469 | |
|
|
1470 | While event loops should scale (and select-based ones do not...) even to |
|
|
1471 | large servers, most programs we (or I :) actually write have only a few |
|
|
1472 | I/O watchers. |
|
|
1473 | |
|
|
1474 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1475 | case, but it uses only eight "servers", of which three are active at any |
|
|
1476 | one time. This should reflect performance for a small server relatively |
|
|
1477 | well. |
|
|
1478 | |
|
|
1479 | The columns are identical to the previous table. |
|
|
1480 | |
|
|
1481 | =head3 Results |
|
|
1482 | |
|
|
1483 | name sockets create request |
|
|
1484 | EV 16 20.00 6.54 |
|
|
1485 | Perl 16 25.75 12.62 |
|
|
1486 | Event 16 81.27 35.86 |
|
|
1487 | Glib 16 32.63 15.48 |
|
|
1488 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1489 | |
|
|
1490 | =head3 Discussion |
|
|
1491 | |
|
|
1492 | The benchmark tries to test the performance of a typical small |
|
|
1493 | server. While knowing how various event loops perform is interesting, keep |
|
|
1494 | in mind that their overhead in this case is usually not as important, due |
|
|
1495 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1496 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1497 | them). |
|
|
1498 | |
|
|
1499 | EV is again fastest. |
|
|
1500 | |
|
|
1501 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1502 | loops Event and Glib, although the difference is too small to really |
|
|
1503 | matter. |
|
|
1504 | |
|
|
1505 | POE also performs much better in this case, but is is still far behind the |
|
|
1506 | others. |
|
|
1507 | |
|
|
1508 | =head3 Summary |
|
|
1509 | |
|
|
1510 | =over 4 |
|
|
1511 | |
|
|
1512 | =item * C-based event loops perform very well with small number of |
|
|
1513 | watchers, as the management overhead dominates. |
|
|
1514 | |
|
|
1515 | =back |
|
|
1516 | |
|
|
1517 | |
|
|
1518 | =head1 FORK |
|
|
1519 | |
|
|
1520 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1521 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1522 | calls. Only L<EV> is fully fork-aware. |
|
|
1523 | |
|
|
1524 | If you have to fork, you must either do so I<before> creating your first |
|
|
1525 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1526 | |
|
|
1527 | |
|
|
1528 | =head1 SECURITY CONSIDERATIONS |
|
|
1529 | |
|
|
1530 | AnyEvent can be forced to load any event model via |
|
|
1531 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1532 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1533 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1534 | will not be active when the program uses a different event model than |
|
|
1535 | specified in the variable. |
|
|
1536 | |
|
|
1537 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1538 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1539 | |
|
|
1540 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1541 | |
|
|
1542 | use AnyEvent; |
|
|
1543 | |
|
|
1544 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1545 | be used to probe what backend is used and gain other information (which is |
|
|
1546 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1547 | |
|
|
1548 | |
|
|
1549 | =head1 SEE ALSO |
|
|
1550 | |
|
|
1551 | Utility functions: L<AnyEvent::Util>. |
|
|
1552 | |
|
|
1553 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1554 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
|
|
1555 | |
|
|
1556 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
|
|
1557 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1558 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1559 | L<AnyEvent::Impl::POE>. |
|
|
1560 | |
|
|
1561 | Non-blocking file handles, sockets, TCP clients and |
|
|
1562 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1563 | |
|
|
1564 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1565 | |
|
|
1566 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1567 | |
|
|
1568 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
|
|
1569 | |
|
|
1570 | |
|
|
1571 | =head1 AUTHOR |
|
|
1572 | |
|
|
1573 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1574 | http://home.schmorp.de/ |
|
|
1575 | |
|
|
1576 | =cut |
|
|
1577 | |
|
|
1578 | 1 |
|
|
1579 | |