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 - 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 | |
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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? |
… | |
… | |
57 | as those use one of the supported event loops. It is trivial to add new |
57 | as those use one of the supported event loops. It is trivial to add new |
58 | event loops to AnyEvent, too, so it is future-proof). |
58 | event loops to AnyEvent, too, so it is future-proof). |
59 | |
59 | |
60 | In addition to being free of having to use I<the one and only true event |
60 | In addition to being free of having to use I<the one and only true event |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
62 | modules, you get an enourmous amount of code and strict rules you have to |
62 | modules, you get an enormous amount of code and strict rules you have to |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
65 | technically possible. |
65 | technically possible. |
66 | |
66 | |
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 | |
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71 | |
70 | |
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 |
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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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107 | |
108 | |
108 | =head1 WATCHERS |
109 | =head1 WATCHERS |
109 | |
110 | |
110 | AnyEvent has the central concept of a I<watcher>, which is an object that |
111 | AnyEvent has the central concept of a I<watcher>, which is an object that |
111 | stores relevant data for each kind of event you are waiting for, such as |
112 | stores relevant data for each kind of event you are waiting for, such as |
112 | the callback to call, the filehandle to watch, etc. |
113 | the callback to call, the file handle to watch, etc. |
113 | |
114 | |
114 | These watchers are normal Perl objects with normal Perl lifetime. After |
115 | These watchers are normal Perl objects with normal Perl lifetime. After |
115 | creating a watcher it will immediately "watch" for events and invoke the |
116 | creating a watcher it will immediately "watch" for events and invoke the |
116 | callback when the event occurs (of course, only when the event model |
117 | callback when the event occurs (of course, only when the event model |
117 | is in control). |
118 | is in control). |
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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 occurrences 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 guaranteed 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 |
236 | between multiple watchers. |
248 | between multiple watchers. |
237 | |
249 | |
238 | This watcher might use C<%SIG>, so programs overwriting those signals |
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
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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 condition variable is "false" until it becomes "true" |
271 | ->broadcast >> method has been called. |
316 | by calling the C<send> method (or calling the condition variable as if it |
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317 | were a callback, read about the caveats in the description for the C<< |
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318 | ->send >> method). |
272 | |
319 | |
273 | They are very useful to signal that a condition has been fulfilled, for |
320 | Condition variables are similar to callbacks, except that you can |
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321 | optionally wait for them. They can also be called merge points - points |
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322 | in time where multiple outstanding events have been processed. And yet |
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323 | another way to call them is transactions - each condition variable can be |
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324 | used to represent a transaction, which finishes at some point and delivers |
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325 | a result. |
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326 | |
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327 | Condition variables are very useful to signal that something has finished, |
274 | example, if you write a module that does asynchronous http requests, |
328 | 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 |
329 | then a condition variable would be the ideal candidate to signal the |
276 | availability of results. |
330 | availability of results. The user can either act when the callback is |
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331 | called or can synchronously C<< ->recv >> for the results. |
277 | |
332 | |
278 | You can also use condition variables to block your main program until |
333 | You can also use them to simulate traditional event loops - for example, |
279 | an event occurs - for example, you could C<< ->wait >> in your main |
334 | you can block your main program until an event occurs - for example, you |
280 | program until the user clicks the Quit button in your app, which would C<< |
335 | could C<< ->recv >> in your main program until the user clicks the Quit |
281 | ->broadcast >> the "quit" event. |
336 | button of your app, which would C<< ->send >> the "quit" event. |
282 | |
337 | |
283 | Note that condition variables recurse into the event loop - if you have |
338 | Note that condition variables recurse into the event loop - if you have |
284 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
339 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
285 | lose. Therefore, condition variables are good to export to your caller, but |
340 | lose. Therefore, condition variables are good to export to your caller, but |
286 | you should avoid making a blocking wait yourself, at least in callbacks, |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
287 | as this asks for trouble. |
342 | as this asks for trouble. |
288 | |
343 | |
289 | This object has two methods: |
344 | Condition variables are represented by hash refs in perl, and the keys |
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345 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
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346 | easy (it is often useful to build your own transaction class on top of |
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347 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
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348 | it's C<new> method in your own C<new> method. |
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349 | |
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350 | There are two "sides" to a condition variable - the "producer side" which |
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351 | eventually calls C<< -> send >>, and the "consumer side", which waits |
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352 | for the send to occur. |
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353 | |
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354 | Example: wait for a timer. |
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355 | |
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356 | # wait till the result is ready |
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357 | my $result_ready = AnyEvent->condvar; |
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358 | |
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359 | # do something such as adding a timer |
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360 | # or socket watcher the calls $result_ready->send |
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361 | # when the "result" is ready. |
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362 | # in this case, we simply use a timer: |
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363 | my $w = AnyEvent->timer ( |
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364 | after => 1, |
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365 | cb => sub { $result_ready->send }, |
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366 | ); |
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367 | |
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368 | # this "blocks" (while handling events) till the callback |
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369 | # calls send |
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370 | $result_ready->recv; |
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371 | |
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372 | Example: wait for a timer, but take advantage of the fact that |
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373 | condition variables are also code references. |
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374 | |
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375 | my $done = AnyEvent->condvar; |
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376 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
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377 | $done->recv; |
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378 | |
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379 | =head3 METHODS FOR PRODUCERS |
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380 | |
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381 | These methods should only be used by the producing side, i.e. the |
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382 | code/module that eventually sends the signal. Note that it is also |
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383 | the producer side which creates the condvar in most cases, but it isn't |
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384 | uncommon for the consumer to create it as well. |
290 | |
385 | |
291 | =over 4 |
386 | =over 4 |
292 | |
387 | |
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388 | =item $cv->send (...) |
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389 | |
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390 | Flag the condition as ready - a running C<< ->recv >> and all further |
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391 | calls to C<recv> will (eventually) return after this method has been |
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392 | called. If nobody is waiting the send will be remembered. |
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393 | |
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394 | If a callback has been set on the condition variable, it is called |
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395 | immediately from within send. |
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396 | |
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397 | Any arguments passed to the C<send> call will be returned by all |
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398 | future C<< ->recv >> calls. |
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399 | |
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400 | Condition variables are overloaded so one can call them directly |
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401 | (as a code reference). Calling them directly is the same as calling |
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402 | C<send>. Note, however, that many C-based event loops do not handle |
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403 | overloading, so as tempting as it may be, passing a condition variable |
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404 | instead of a callback does not work. Both the pure perl and EV loops |
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405 | support overloading, however, as well as all functions that use perl to |
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406 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
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407 | example). |
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408 | |
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409 | =item $cv->croak ($error) |
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410 | |
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411 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
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412 | C<Carp::croak> with the given error message/object/scalar. |
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413 | |
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414 | This can be used to signal any errors to the condition variable |
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415 | user/consumer. |
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416 | |
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417 | =item $cv->begin ([group callback]) |
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418 | |
293 | =item $cv->wait |
419 | =item $cv->end |
294 | |
420 | |
295 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
421 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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422 | |
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423 | These two methods can be used to combine many transactions/events into |
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424 | one. For example, a function that pings many hosts in parallel might want |
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425 | to use a condition variable for the whole process. |
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426 | |
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427 | Every call to C<< ->begin >> will increment a counter, and every call to |
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428 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
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429 | >>, the (last) callback passed to C<begin> will be executed. That callback |
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430 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
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431 | callback was set, C<send> will be called without any arguments. |
|
|
432 | |
|
|
433 | Let's clarify this with the ping example: |
|
|
434 | |
|
|
435 | my $cv = AnyEvent->condvar; |
|
|
436 | |
|
|
437 | my %result; |
|
|
438 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
439 | |
|
|
440 | for my $host (@list_of_hosts) { |
|
|
441 | $cv->begin; |
|
|
442 | ping_host_then_call_callback $host, sub { |
|
|
443 | $result{$host} = ...; |
|
|
444 | $cv->end; |
|
|
445 | }; |
|
|
446 | } |
|
|
447 | |
|
|
448 | $cv->end; |
|
|
449 | |
|
|
450 | This code fragment supposedly pings a number of hosts and calls |
|
|
451 | C<send> after results for all then have have been gathered - in any |
|
|
452 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
453 | each ping request and calls C<end> when it has received some result for |
|
|
454 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
455 | results arrive is not relevant. |
|
|
456 | |
|
|
457 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
458 | loop, which serves two important purposes: first, it sets the callback |
|
|
459 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
460 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
461 | doesn't execute once). |
|
|
462 | |
|
|
463 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
464 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
465 | is called at least once, and then, for each subrequest you start, call |
|
|
466 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
467 | |
|
|
468 | =back |
|
|
469 | |
|
|
470 | =head3 METHODS FOR CONSUMERS |
|
|
471 | |
|
|
472 | These methods should only be used by the consuming side, i.e. the |
|
|
473 | code awaits the condition. |
|
|
474 | |
|
|
475 | =over 4 |
|
|
476 | |
|
|
477 | =item $cv->recv |
|
|
478 | |
|
|
479 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
296 | called on c<$cv>, while servicing other watchers normally. |
480 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
481 | normally. |
297 | |
482 | |
298 | You can only wait once on a condition - additional calls will return |
483 | You can only wait once on a condition - additional calls are valid but |
299 | immediately. |
484 | will return immediately. |
|
|
485 | |
|
|
486 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
487 | function will call C<croak>. |
|
|
488 | |
|
|
489 | In list context, all parameters passed to C<send> will be returned, |
|
|
490 | in scalar context only the first one will be returned. |
300 | |
491 | |
301 | Not all event models support a blocking wait - some die in that case |
492 | 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 |
493 | (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 |
494 | 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 |
495 | caller decide whether the call will block or not (for example, by coupling |
305 | condition variables with some kind of request results and supporting |
496 | condition variables with some kind of request results and supporting |
306 | callbacks so the caller knows that getting the result will not block, |
497 | callbacks so the caller knows that getting the result will not block, |
307 | while still suppporting blocking waits if the caller so desires). |
498 | while still supporting blocking waits if the caller so desires). |
308 | |
499 | |
309 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
500 | 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 |
501 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
311 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
502 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
312 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
503 | can supply. |
313 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
|
|
314 | from different coroutines, however). |
|
|
315 | |
504 | |
316 | =item $cv->broadcast |
505 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
506 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
507 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
508 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
509 | coroutine (one that doesn't run the event loop). |
317 | |
510 | |
318 | Flag the condition as ready - a running C<< ->wait >> and all further |
511 | 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 |
512 | only calling C<< ->recv >> from within that callback (or at a later |
320 | called. If nobody is waiting the broadcast will be remembered.. |
513 | time). This will work even when the event loop does not support blocking |
|
|
514 | waits otherwise. |
|
|
515 | |
|
|
516 | =item $bool = $cv->ready |
|
|
517 | |
|
|
518 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
519 | C<croak> have been called. |
|
|
520 | |
|
|
521 | =item $cb = $cv->cb ([new callback]) |
|
|
522 | |
|
|
523 | This is a mutator function that returns the callback set and optionally |
|
|
524 | replaces it before doing so. |
|
|
525 | |
|
|
526 | The callback will be called when the condition becomes "true", i.e. when |
|
|
527 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
528 | or at any later time is guaranteed not to block. |
321 | |
529 | |
322 | =back |
530 | =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 | |
531 | |
342 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
532 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
343 | |
533 | |
344 | =over 4 |
534 | =over 4 |
345 | |
535 | |
… | |
… | |
351 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
541 | 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>). |
542 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
353 | |
543 | |
354 | The known classes so far are: |
544 | The known classes so far are: |
355 | |
545 | |
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). |
546 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
359 | AnyEvent::Impl::Event based on Event, also second best choice :) |
547 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
548 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
360 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
549 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
361 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
550 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
362 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
551 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
552 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
553 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
554 | |
|
|
555 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
556 | watching file handles. However, you can use WxWidgets through the |
|
|
557 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
558 | second, which was considered to be too horrible to even consider for |
|
|
559 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
560 | it's adaptor. |
|
|
561 | |
|
|
562 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
563 | autodetecting them. |
363 | |
564 | |
364 | =item AnyEvent::detect |
565 | =item AnyEvent::detect |
365 | |
566 | |
366 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
567 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
367 | if necessary. You should only call this function right before you would |
568 | if necessary. You should only call this function right before you would |
368 | have created an AnyEvent watcher anyway, that is, as late as possible at |
569 | have created an AnyEvent watcher anyway, that is, as late as possible at |
369 | runtime. |
570 | runtime. |
370 | |
571 | |
|
|
572 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
573 | |
|
|
574 | Arranges for the code block to be executed as soon as the event model is |
|
|
575 | autodetected (or immediately if this has already happened). |
|
|
576 | |
|
|
577 | If called in scalar or list context, then it creates and returns an object |
|
|
578 | that automatically removes the callback again when it is destroyed. See |
|
|
579 | L<Coro::BDB> for a case where this is useful. |
|
|
580 | |
|
|
581 | =item @AnyEvent::post_detect |
|
|
582 | |
|
|
583 | If there are any code references in this array (you can C<push> to it |
|
|
584 | before or after loading AnyEvent), then they will called directly after |
|
|
585 | the event loop has been chosen. |
|
|
586 | |
|
|
587 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
588 | if it contains a true value then the event loop has already been detected, |
|
|
589 | and the array will be ignored. |
|
|
590 | |
|
|
591 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
|
|
592 | |
371 | =back |
593 | =back |
372 | |
594 | |
373 | =head1 WHAT TO DO IN A MODULE |
595 | =head1 WHAT TO DO IN A MODULE |
374 | |
596 | |
375 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
597 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
… | |
… | |
378 | Be careful when you create watchers in the module body - AnyEvent will |
600 | Be careful when you create watchers in the module body - AnyEvent will |
379 | decide which event module to use as soon as the first method is called, so |
601 | decide which event module to use as soon as the first method is called, so |
380 | by calling AnyEvent in your module body you force the user of your module |
602 | by calling AnyEvent in your module body you force the user of your module |
381 | to load the event module first. |
603 | to load the event module first. |
382 | |
604 | |
383 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
605 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
384 | the C<< ->broadcast >> method has been called on it already. This is |
606 | the C<< ->send >> method has been called on it already. This is |
385 | because it will stall the whole program, and the whole point of using |
607 | because it will stall the whole program, and the whole point of using |
386 | events is to stay interactive. |
608 | events is to stay interactive. |
387 | |
609 | |
388 | It is fine, however, to call C<< ->wait >> when the user of your module |
610 | It is fine, however, to call C<< ->recv >> when the user of your module |
389 | requests it (i.e. if you create a http request object ad have a method |
611 | requests it (i.e. if you create a http request object ad have a method |
390 | called C<results> that returns the results, it should call C<< ->wait >> |
612 | called C<results> that returns the results, it should call C<< ->recv >> |
391 | freely, as the user of your module knows what she is doing. always). |
613 | freely, as the user of your module knows what she is doing. always). |
392 | |
614 | |
393 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
615 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
394 | |
616 | |
395 | There will always be a single main program - the only place that should |
617 | There will always be a single main program - the only place that should |
… | |
… | |
397 | |
619 | |
398 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
620 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
399 | do anything special (it does not need to be event-based) and let AnyEvent |
621 | do anything special (it does not need to be event-based) and let AnyEvent |
400 | decide which implementation to chose if some module relies on it. |
622 | decide which implementation to chose if some module relies on it. |
401 | |
623 | |
402 | If the main program relies on a specific event model. For example, in |
624 | If the main program relies on a specific event model - for example, in |
403 | Gtk2 programs you have to rely on the Glib module. You should load the |
625 | Gtk2 programs you have to rely on the Glib module - you should load the |
404 | event module before loading AnyEvent or any module that uses it: generally |
626 | event module before loading AnyEvent or any module that uses it: generally |
405 | speaking, you should load it as early as possible. The reason is that |
627 | speaking, you should load it as early as possible. The reason is that |
406 | modules might create watchers when they are loaded, and AnyEvent will |
628 | modules might create watchers when they are loaded, and AnyEvent will |
407 | decide on the event model to use as soon as it creates watchers, and it |
629 | decide on the event model to use as soon as it creates watchers, and it |
408 | might chose the wrong one unless you load the correct one yourself. |
630 | might chose the wrong one unless you load the correct one yourself. |
409 | |
631 | |
410 | You can chose to use a rather inefficient pure-perl implementation by |
632 | You can chose to use a pure-perl implementation by loading the |
411 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
633 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
412 | behaviour everywhere, but letting AnyEvent chose is generally better. |
634 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
635 | |
|
|
636 | =head2 MAINLOOP EMULATION |
|
|
637 | |
|
|
638 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
639 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
640 | |
|
|
641 | In that case, you can use a condition variable like this: |
|
|
642 | |
|
|
643 | AnyEvent->condvar->recv; |
|
|
644 | |
|
|
645 | This has the effect of entering the event loop and looping forever. |
|
|
646 | |
|
|
647 | Note that usually your program has some exit condition, in which case |
|
|
648 | it is better to use the "traditional" approach of storing a condition |
|
|
649 | variable somewhere, waiting for it, and sending it when the program should |
|
|
650 | exit cleanly. |
|
|
651 | |
|
|
652 | |
|
|
653 | =head1 OTHER MODULES |
|
|
654 | |
|
|
655 | The following is a non-exhaustive list of additional modules that use |
|
|
656 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
657 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
658 | available via CPAN. |
|
|
659 | |
|
|
660 | =over 4 |
|
|
661 | |
|
|
662 | =item L<AnyEvent::Util> |
|
|
663 | |
|
|
664 | Contains various utility functions that replace often-used but blocking |
|
|
665 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
666 | |
|
|
667 | =item L<AnyEvent::Handle> |
|
|
668 | |
|
|
669 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
670 | |
|
|
671 | =item L<AnyEvent::Socket> |
|
|
672 | |
|
|
673 | Provides various utility functions for (internet protocol) sockets, |
|
|
674 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
675 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
676 | |
|
|
677 | =item L<AnyEvent::DNS> |
|
|
678 | |
|
|
679 | Provides rich asynchronous DNS resolver capabilities. |
|
|
680 | |
|
|
681 | =item L<AnyEvent::HTTPD> |
|
|
682 | |
|
|
683 | Provides a simple web application server framework. |
|
|
684 | |
|
|
685 | =item L<AnyEvent::FastPing> |
|
|
686 | |
|
|
687 | The fastest ping in the west. |
|
|
688 | |
|
|
689 | =item L<Net::IRC3> |
|
|
690 | |
|
|
691 | AnyEvent based IRC client module family. |
|
|
692 | |
|
|
693 | =item L<Net::XMPP2> |
|
|
694 | |
|
|
695 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
696 | |
|
|
697 | =item L<Net::FCP> |
|
|
698 | |
|
|
699 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
700 | of AnyEvent. |
|
|
701 | |
|
|
702 | =item L<Event::ExecFlow> |
|
|
703 | |
|
|
704 | High level API for event-based execution flow control. |
|
|
705 | |
|
|
706 | =item L<Coro> |
|
|
707 | |
|
|
708 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
709 | |
|
|
710 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
711 | |
|
|
712 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
713 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
714 | together. |
|
|
715 | |
|
|
716 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
717 | |
|
|
718 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
719 | IO::AIO and AnyEvent together. |
|
|
720 | |
|
|
721 | =item L<IO::Lambda> |
|
|
722 | |
|
|
723 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
724 | |
|
|
725 | =back |
413 | |
726 | |
414 | =cut |
727 | =cut |
415 | |
728 | |
416 | package AnyEvent; |
729 | package AnyEvent; |
417 | |
730 | |
418 | no warnings; |
731 | no warnings; |
419 | use strict; |
732 | use strict; |
420 | |
733 | |
421 | use Carp; |
734 | use Carp; |
422 | |
735 | |
423 | our $VERSION = '3.11'; |
736 | our $VERSION = '4.03'; |
424 | our $MODEL; |
737 | our $MODEL; |
425 | |
738 | |
426 | our $AUTOLOAD; |
739 | our $AUTOLOAD; |
427 | our @ISA; |
740 | our @ISA; |
428 | |
741 | |
|
|
742 | our @REGISTRY; |
|
|
743 | |
|
|
744 | our $WIN32; |
|
|
745 | |
|
|
746 | BEGIN { |
|
|
747 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
748 | eval "sub WIN32(){ $win32 }"; |
|
|
749 | } |
|
|
750 | |
429 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
751 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
430 | |
752 | |
431 | our @REGISTRY; |
753 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
754 | |
|
|
755 | { |
|
|
756 | my $idx; |
|
|
757 | $PROTOCOL{$_} = ++$idx |
|
|
758 | for reverse split /\s*,\s*/, |
|
|
759 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
760 | } |
|
|
761 | |
|
|
762 | sub import { |
|
|
763 | shift; |
|
|
764 | return unless @_; |
|
|
765 | |
|
|
766 | my $pkg = caller; |
|
|
767 | |
|
|
768 | no strict 'refs'; |
|
|
769 | |
|
|
770 | for (@_) { |
|
|
771 | *{"$pkg\::WIN32"} = *WIN32 if $_ eq "WIN32"; |
|
|
772 | } |
|
|
773 | } |
432 | |
774 | |
433 | my @models = ( |
775 | my @models = ( |
434 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
435 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
436 | [EV:: => AnyEvent::Impl::EV::], |
776 | [EV:: => AnyEvent::Impl::EV::], |
437 | [Event:: => AnyEvent::Impl::Event::], |
777 | [Event:: => AnyEvent::Impl::Event::], |
438 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
439 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
440 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
778 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
779 | # everything below here will not be autoprobed |
|
|
780 | # as the pureperl backend should work everywhere |
|
|
781 | # and is usually faster |
|
|
782 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
783 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
784 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
785 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
786 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
787 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
788 | [Prima:: => AnyEvent::Impl::POE::], |
441 | ); |
789 | ); |
442 | |
790 | |
443 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
791 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
|
|
792 | |
|
|
793 | our @post_detect; |
|
|
794 | |
|
|
795 | sub post_detect(&) { |
|
|
796 | my ($cb) = @_; |
|
|
797 | |
|
|
798 | if ($MODEL) { |
|
|
799 | $cb->(); |
|
|
800 | |
|
|
801 | 1 |
|
|
802 | } else { |
|
|
803 | push @post_detect, $cb; |
|
|
804 | |
|
|
805 | defined wantarray |
|
|
806 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
807 | : () |
|
|
808 | } |
|
|
809 | } |
|
|
810 | |
|
|
811 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
812 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
813 | } |
444 | |
814 | |
445 | sub detect() { |
815 | sub detect() { |
446 | unless ($MODEL) { |
816 | unless ($MODEL) { |
447 | no strict 'refs'; |
817 | no strict 'refs'; |
|
|
818 | local $SIG{__DIE__}; |
|
|
819 | |
|
|
820 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
821 | my $model = "AnyEvent::Impl::$1"; |
|
|
822 | if (eval "require $model") { |
|
|
823 | $MODEL = $model; |
|
|
824 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
825 | } else { |
|
|
826 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
827 | } |
|
|
828 | } |
448 | |
829 | |
449 | # check for already loaded models |
830 | # check for already loaded models |
|
|
831 | unless ($MODEL) { |
450 | for (@REGISTRY, @models) { |
832 | for (@REGISTRY, @models) { |
451 | my ($package, $model) = @$_; |
833 | my ($package, $model) = @$_; |
452 | if (${"$package\::VERSION"} > 0) { |
834 | if (${"$package\::VERSION"} > 0) { |
453 | if (eval "require $model") { |
835 | if (eval "require $model") { |
454 | $MODEL = $model; |
836 | $MODEL = $model; |
455 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
837 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
456 | last; |
838 | last; |
|
|
839 | } |
457 | } |
840 | } |
458 | } |
841 | } |
459 | } |
|
|
460 | |
842 | |
461 | unless ($MODEL) { |
843 | unless ($MODEL) { |
462 | # try to load a model |
844 | # try to load a model |
463 | |
845 | |
464 | for (@REGISTRY, @models) { |
846 | for (@REGISTRY, @models) { |
465 | my ($package, $model) = @$_; |
847 | my ($package, $model) = @$_; |
466 | if (eval "require $package" |
848 | if (eval "require $package" |
467 | and ${"$package\::VERSION"} > 0 |
849 | and ${"$package\::VERSION"} > 0 |
468 | and eval "require $model") { |
850 | and eval "require $model") { |
469 | $MODEL = $model; |
851 | $MODEL = $model; |
470 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
852 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
471 | last; |
853 | last; |
|
|
854 | } |
472 | } |
855 | } |
|
|
856 | |
|
|
857 | $MODEL |
|
|
858 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
473 | } |
859 | } |
474 | |
|
|
475 | $MODEL |
|
|
476 | 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), Glib or Tk."; |
|
|
477 | } |
860 | } |
478 | |
861 | |
479 | unshift @ISA, $MODEL; |
862 | unshift @ISA, $MODEL; |
480 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
863 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
864 | |
|
|
865 | (shift @post_detect)->() while @post_detect; |
481 | } |
866 | } |
482 | |
867 | |
483 | $MODEL |
868 | $MODEL |
484 | } |
869 | } |
485 | |
870 | |
… | |
… | |
495 | $class->$func (@_); |
880 | $class->$func (@_); |
496 | } |
881 | } |
497 | |
882 | |
498 | package AnyEvent::Base; |
883 | package AnyEvent::Base; |
499 | |
884 | |
500 | # default implementation for ->condvar, ->wait, ->broadcast |
885 | # default implementation for ->condvar |
501 | |
886 | |
502 | sub condvar { |
887 | sub condvar { |
503 | bless \my $flag, "AnyEvent::Base::CondVar" |
888 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
504 | } |
|
|
505 | |
|
|
506 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
507 | ${$_[0]}++; |
|
|
508 | } |
|
|
509 | |
|
|
510 | sub AnyEvent::Base::CondVar::wait { |
|
|
511 | AnyEvent->one_event while !${$_[0]}; |
|
|
512 | } |
889 | } |
513 | |
890 | |
514 | # default implementation for ->signal |
891 | # default implementation for ->signal |
515 | |
892 | |
516 | our %SIG_CB; |
893 | our %SIG_CB; |
… | |
… | |
569 | or Carp::croak "required option 'pid' is missing"; |
946 | or Carp::croak "required option 'pid' is missing"; |
570 | |
947 | |
571 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
948 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
572 | |
949 | |
573 | unless ($WNOHANG) { |
950 | unless ($WNOHANG) { |
574 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
951 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
575 | } |
952 | } |
576 | |
953 | |
577 | unless ($CHLD_W) { |
954 | unless ($CHLD_W) { |
578 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
955 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
579 | # child could be a zombie already, so make at least one round |
956 | # child could be a zombie already, so make at least one round |
… | |
… | |
589 | delete $PID_CB{$pid}{$cb}; |
966 | delete $PID_CB{$pid}{$cb}; |
590 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
967 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
591 | |
968 | |
592 | undef $CHLD_W unless keys %PID_CB; |
969 | undef $CHLD_W unless keys %PID_CB; |
593 | } |
970 | } |
|
|
971 | |
|
|
972 | package AnyEvent::CondVar; |
|
|
973 | |
|
|
974 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
975 | |
|
|
976 | package AnyEvent::CondVar::Base; |
|
|
977 | |
|
|
978 | use overload |
|
|
979 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
980 | fallback => 1; |
|
|
981 | |
|
|
982 | sub _send { |
|
|
983 | # nop |
|
|
984 | } |
|
|
985 | |
|
|
986 | sub send { |
|
|
987 | my $cv = shift; |
|
|
988 | $cv->{_ae_sent} = [@_]; |
|
|
989 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
990 | $cv->_send; |
|
|
991 | } |
|
|
992 | |
|
|
993 | sub croak { |
|
|
994 | $_[0]{_ae_croak} = $_[1]; |
|
|
995 | $_[0]->send; |
|
|
996 | } |
|
|
997 | |
|
|
998 | sub ready { |
|
|
999 | $_[0]{_ae_sent} |
|
|
1000 | } |
|
|
1001 | |
|
|
1002 | sub _wait { |
|
|
1003 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1004 | } |
|
|
1005 | |
|
|
1006 | sub recv { |
|
|
1007 | $_[0]->_wait; |
|
|
1008 | |
|
|
1009 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1010 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1011 | } |
|
|
1012 | |
|
|
1013 | sub cb { |
|
|
1014 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1015 | $_[0]{_ae_cb} |
|
|
1016 | } |
|
|
1017 | |
|
|
1018 | sub begin { |
|
|
1019 | ++$_[0]{_ae_counter}; |
|
|
1020 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1021 | } |
|
|
1022 | |
|
|
1023 | sub end { |
|
|
1024 | return if --$_[0]{_ae_counter}; |
|
|
1025 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1026 | } |
|
|
1027 | |
|
|
1028 | # undocumented/compatibility with pre-3.4 |
|
|
1029 | *broadcast = \&send; |
|
|
1030 | *wait = \&_wait; |
594 | |
1031 | |
595 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1032 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
596 | |
1033 | |
597 | This is an advanced topic that you do not normally need to use AnyEvent in |
1034 | This is an advanced topic that you do not normally need to use AnyEvent in |
598 | a module. This section is only of use to event loop authors who want to |
1035 | a module. This section is only of use to event loop authors who want to |
… | |
… | |
637 | |
1074 | |
638 | =head1 ENVIRONMENT VARIABLES |
1075 | =head1 ENVIRONMENT VARIABLES |
639 | |
1076 | |
640 | The following environment variables are used by this module: |
1077 | The following environment variables are used by this module: |
641 | |
1078 | |
642 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, cause AnyEvent to |
1079 | =over 4 |
643 | report to STDERR which event model it chooses. |
1080 | |
|
|
1081 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1082 | |
|
|
1083 | By default, AnyEvent will be completely silent except in fatal |
|
|
1084 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1085 | talkative. |
|
|
1086 | |
|
|
1087 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1088 | conditions, such as not being able to load the event model specified by |
|
|
1089 | C<PERL_ANYEVENT_MODEL>. |
|
|
1090 | |
|
|
1091 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1092 | model it chooses. |
|
|
1093 | |
|
|
1094 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1095 | |
|
|
1096 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1097 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1098 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1099 | and the resulting module name is loaded and if the load was successful, |
|
|
1100 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1101 | auto detection and -probing. |
|
|
1102 | |
|
|
1103 | This functionality might change in future versions. |
|
|
1104 | |
|
|
1105 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1106 | could start your program like this: |
|
|
1107 | |
|
|
1108 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1109 | |
|
|
1110 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1111 | |
|
|
1112 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1113 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1114 | of auto probing). |
|
|
1115 | |
|
|
1116 | Must be set to a comma-separated list of protocols or address families, |
|
|
1117 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1118 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1119 | list. |
|
|
1120 | |
|
|
1121 | This variable can effectively be used for denial-of-service attacks |
|
|
1122 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1123 | small, as the program has to handle connection errors already- |
|
|
1124 | |
|
|
1125 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1126 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1127 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1128 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1129 | IPv6, but prefer IPv6 over IPv4. |
|
|
1130 | |
|
|
1131 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1132 | |
|
|
1133 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1134 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1135 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1136 | default. |
|
|
1137 | |
|
|
1138 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1139 | EDNS0 in its DNS requests. |
|
|
1140 | |
|
|
1141 | =back |
644 | |
1142 | |
645 | =head1 EXAMPLE PROGRAM |
1143 | =head1 EXAMPLE PROGRAM |
646 | |
1144 | |
647 | The following program uses an IO watcher to read data from STDIN, a timer |
1145 | The following program uses an I/O watcher to read data from STDIN, a timer |
648 | to display a message once per second, and a condition variable to quit the |
1146 | to display a message once per second, and a condition variable to quit the |
649 | program when the user enters quit: |
1147 | program when the user enters quit: |
650 | |
1148 | |
651 | use AnyEvent; |
1149 | use AnyEvent; |
652 | |
1150 | |
… | |
… | |
657 | poll => 'r', |
1155 | poll => 'r', |
658 | cb => sub { |
1156 | cb => sub { |
659 | warn "io event <$_[0]>\n"; # will always output <r> |
1157 | warn "io event <$_[0]>\n"; # will always output <r> |
660 | chomp (my $input = <STDIN>); # read a line |
1158 | chomp (my $input = <STDIN>); # read a line |
661 | warn "read: $input\n"; # output what has been read |
1159 | warn "read: $input\n"; # output what has been read |
662 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1160 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
663 | }, |
1161 | }, |
664 | ); |
1162 | ); |
665 | |
1163 | |
666 | my $time_watcher; # can only be used once |
1164 | my $time_watcher; # can only be used once |
667 | |
1165 | |
… | |
… | |
672 | }); |
1170 | }); |
673 | } |
1171 | } |
674 | |
1172 | |
675 | new_timer; # create first timer |
1173 | new_timer; # create first timer |
676 | |
1174 | |
677 | $cv->wait; # wait until user enters /^q/i |
1175 | $cv->recv; # wait until user enters /^q/i |
678 | |
1176 | |
679 | =head1 REAL-WORLD EXAMPLE |
1177 | =head1 REAL-WORLD EXAMPLE |
680 | |
1178 | |
681 | Consider the L<Net::FCP> module. It features (among others) the following |
1179 | Consider the L<Net::FCP> module. It features (among others) the following |
682 | API calls, which are to freenet what HTTP GET requests are to http: |
1180 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
732 | syswrite $txn->{fh}, $txn->{request} |
1230 | syswrite $txn->{fh}, $txn->{request} |
733 | or die "connection or write error"; |
1231 | or die "connection or write error"; |
734 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1232 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
735 | |
1233 | |
736 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1234 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
737 | result and signals any possible waiters that the request ahs finished: |
1235 | result and signals any possible waiters that the request has finished: |
738 | |
1236 | |
739 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1237 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
740 | |
1238 | |
741 | if (end-of-file or data complete) { |
1239 | if (end-of-file or data complete) { |
742 | $txn->{result} = $txn->{buf}; |
1240 | $txn->{result} = $txn->{buf}; |
743 | $txn->{finished}->broadcast; |
1241 | $txn->{finished}->send; |
744 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1242 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
745 | } |
1243 | } |
746 | |
1244 | |
747 | The C<result> method, finally, just waits for the finished signal (if the |
1245 | The C<result> method, finally, just waits for the finished signal (if the |
748 | request was already finished, it doesn't wait, of course, and returns the |
1246 | request was already finished, it doesn't wait, of course, and returns the |
749 | data: |
1247 | data: |
750 | |
1248 | |
751 | $txn->{finished}->wait; |
1249 | $txn->{finished}->recv; |
752 | return $txn->{result}; |
1250 | return $txn->{result}; |
753 | |
1251 | |
754 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1252 | The actual code goes further and collects all errors (C<die>s, exceptions) |
755 | that occured during request processing. The C<result> method detects |
1253 | that occurred during request processing. The C<result> method detects |
756 | whether an exception as thrown (it is stored inside the $txn object) |
1254 | whether an exception as thrown (it is stored inside the $txn object) |
757 | and just throws the exception, which means connection errors and other |
1255 | and just throws the exception, which means connection errors and other |
758 | problems get reported tot he code that tries to use the result, not in a |
1256 | problems get reported tot he code that tries to use the result, not in a |
759 | random callback. |
1257 | random callback. |
760 | |
1258 | |
… | |
… | |
791 | |
1289 | |
792 | my $quit = AnyEvent->condvar; |
1290 | my $quit = AnyEvent->condvar; |
793 | |
1291 | |
794 | $fcp->txn_client_get ($url)->cb (sub { |
1292 | $fcp->txn_client_get ($url)->cb (sub { |
795 | ... |
1293 | ... |
796 | $quit->broadcast; |
1294 | $quit->send; |
797 | }); |
1295 | }); |
798 | |
1296 | |
799 | $quit->wait; |
1297 | $quit->recv; |
|
|
1298 | |
|
|
1299 | |
|
|
1300 | =head1 BENCHMARKS |
|
|
1301 | |
|
|
1302 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1303 | over the event loops themselves and to give you an impression of the speed |
|
|
1304 | of various event loops I prepared some benchmarks. |
|
|
1305 | |
|
|
1306 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1307 | |
|
|
1308 | Here is a benchmark of various supported event models used natively and |
|
|
1309 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1310 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1311 | which it is), lets them fire exactly once and destroys them again. |
|
|
1312 | |
|
|
1313 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1314 | distribution. |
|
|
1315 | |
|
|
1316 | =head3 Explanation of the columns |
|
|
1317 | |
|
|
1318 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1319 | different event models feature vastly different performances, each event |
|
|
1320 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1321 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1322 | would probably take thousands of years if asked to process the same number |
|
|
1323 | of watchers as EV in this benchmark. |
|
|
1324 | |
|
|
1325 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1326 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1327 | and Perl-based overheads. |
|
|
1328 | |
|
|
1329 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1330 | takes to create a single watcher. The callback is a closure shared between |
|
|
1331 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1332 | and memory usage is not included in the figures. |
|
|
1333 | |
|
|
1334 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1335 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1336 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1337 | signal the end of this phase. |
|
|
1338 | |
|
|
1339 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1340 | watcher. |
|
|
1341 | |
|
|
1342 | =head3 Results |
|
|
1343 | |
|
|
1344 | name watchers bytes create invoke destroy comment |
|
|
1345 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1346 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1347 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1348 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1349 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1350 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1351 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1352 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1353 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1354 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1355 | |
|
|
1356 | =head3 Discussion |
|
|
1357 | |
|
|
1358 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1359 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1360 | can never compete with an event loop that uses epoll when the number of |
|
|
1361 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1362 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1363 | boost. |
|
|
1364 | |
|
|
1365 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1366 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1367 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1368 | higher number of watchers at a disadvantage. |
|
|
1369 | |
|
|
1370 | To put the range of results into perspective, consider that on the |
|
|
1371 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1372 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1373 | cycles with POE. |
|
|
1374 | |
|
|
1375 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1376 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1377 | far less memory than any other event loop and is still faster than Event |
|
|
1378 | natively. |
|
|
1379 | |
|
|
1380 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1381 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1382 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1383 | adds very little overhead in itself. Like any select-based backend its |
|
|
1384 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1385 | them active), of course, but this was not subject of this benchmark. |
|
|
1386 | |
|
|
1387 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1388 | cost, but overall scores in on the third place. |
|
|
1389 | |
|
|
1390 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1391 | faster callback invocation and overall ends up in the same class as |
|
|
1392 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1393 | watchers increases the processing time by more than a factor of four, |
|
|
1394 | making it completely unusable when using larger numbers of watchers |
|
|
1395 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1396 | inefficiencies of C<poll> do not account for this). |
|
|
1397 | |
|
|
1398 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1399 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1400 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1401 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1402 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1403 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1404 | above). |
|
|
1405 | |
|
|
1406 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1407 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1408 | be tested because it wasn't working) shows abysmal performance and |
|
|
1409 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1410 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1411 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1412 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1413 | implementation. |
|
|
1414 | |
|
|
1415 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1416 | for the performance issues, though, as session creation overhead is |
|
|
1417 | small compared to execution of the state machine, which is coded pretty |
|
|
1418 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1419 | using multiple sessions is not a good approach, especially regarding |
|
|
1420 | memory usage, even the author of POE could not come up with a faster |
|
|
1421 | design). |
|
|
1422 | |
|
|
1423 | =head3 Summary |
|
|
1424 | |
|
|
1425 | =over 4 |
|
|
1426 | |
|
|
1427 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1428 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1429 | performance with or without AnyEvent. |
|
|
1430 | |
|
|
1431 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1432 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1433 | adds AnyEvent significant overhead. |
|
|
1434 | |
|
|
1435 | =item * You should avoid POE like the plague if you want performance or |
|
|
1436 | reasonable memory usage. |
|
|
1437 | |
|
|
1438 | =back |
|
|
1439 | |
|
|
1440 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1441 | |
|
|
1442 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1443 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1444 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1445 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1446 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1447 | |
|
|
1448 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1449 | are active at any one point (so there is a constant number of active |
|
|
1450 | fds for each loop iteration, but which fds these are is random). The |
|
|
1451 | timeout is reset each time something is read because that reflects how |
|
|
1452 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1453 | |
|
|
1454 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1455 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1456 | connections, most of which are idle at any one point in time. |
|
|
1457 | |
|
|
1458 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1459 | distribution. |
|
|
1460 | |
|
|
1461 | =head3 Explanation of the columns |
|
|
1462 | |
|
|
1463 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1464 | each server has a read and write socket end). |
|
|
1465 | |
|
|
1466 | I<create> is the time it takes to create a socket pair (which is |
|
|
1467 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1468 | |
|
|
1469 | I<request>, the most important value, is the time it takes to handle a |
|
|
1470 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1471 | it to another server. This includes deleting the old timeout and creating |
|
|
1472 | a new one that moves the timeout into the future. |
|
|
1473 | |
|
|
1474 | =head3 Results |
|
|
1475 | |
|
|
1476 | name sockets create request |
|
|
1477 | EV 20000 69.01 11.16 |
|
|
1478 | Perl 20000 73.32 35.87 |
|
|
1479 | Event 20000 212.62 257.32 |
|
|
1480 | Glib 20000 651.16 1896.30 |
|
|
1481 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1482 | |
|
|
1483 | =head3 Discussion |
|
|
1484 | |
|
|
1485 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1486 | particular event loop. |
|
|
1487 | |
|
|
1488 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1489 | is relatively high, though. |
|
|
1490 | |
|
|
1491 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1492 | loops Event and Glib. |
|
|
1493 | |
|
|
1494 | Event suffers from high setup time as well (look at its code and you will |
|
|
1495 | understand why). Callback invocation also has a high overhead compared to |
|
|
1496 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1497 | uses select or poll in basically all documented configurations. |
|
|
1498 | |
|
|
1499 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1500 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1501 | |
|
|
1502 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1503 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1504 | it uses a C-based event loop in this case. |
|
|
1505 | |
|
|
1506 | =head3 Summary |
|
|
1507 | |
|
|
1508 | =over 4 |
|
|
1509 | |
|
|
1510 | =item * The pure perl implementation performs extremely well. |
|
|
1511 | |
|
|
1512 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1513 | |
|
|
1514 | =back |
|
|
1515 | |
|
|
1516 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1517 | |
|
|
1518 | While event loops should scale (and select-based ones do not...) even to |
|
|
1519 | large servers, most programs we (or I :) actually write have only a few |
|
|
1520 | I/O watchers. |
|
|
1521 | |
|
|
1522 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1523 | case, but it uses only eight "servers", of which three are active at any |
|
|
1524 | one time. This should reflect performance for a small server relatively |
|
|
1525 | well. |
|
|
1526 | |
|
|
1527 | The columns are identical to the previous table. |
|
|
1528 | |
|
|
1529 | =head3 Results |
|
|
1530 | |
|
|
1531 | name sockets create request |
|
|
1532 | EV 16 20.00 6.54 |
|
|
1533 | Perl 16 25.75 12.62 |
|
|
1534 | Event 16 81.27 35.86 |
|
|
1535 | Glib 16 32.63 15.48 |
|
|
1536 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1537 | |
|
|
1538 | =head3 Discussion |
|
|
1539 | |
|
|
1540 | The benchmark tries to test the performance of a typical small |
|
|
1541 | server. While knowing how various event loops perform is interesting, keep |
|
|
1542 | in mind that their overhead in this case is usually not as important, due |
|
|
1543 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1544 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1545 | them). |
|
|
1546 | |
|
|
1547 | EV is again fastest. |
|
|
1548 | |
|
|
1549 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1550 | loops Event and Glib, although the difference is too small to really |
|
|
1551 | matter. |
|
|
1552 | |
|
|
1553 | POE also performs much better in this case, but is is still far behind the |
|
|
1554 | others. |
|
|
1555 | |
|
|
1556 | =head3 Summary |
|
|
1557 | |
|
|
1558 | =over 4 |
|
|
1559 | |
|
|
1560 | =item * C-based event loops perform very well with small number of |
|
|
1561 | watchers, as the management overhead dominates. |
|
|
1562 | |
|
|
1563 | =back |
|
|
1564 | |
|
|
1565 | |
|
|
1566 | =head1 FORK |
|
|
1567 | |
|
|
1568 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1569 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1570 | calls. Only L<EV> is fully fork-aware. |
|
|
1571 | |
|
|
1572 | If you have to fork, you must either do so I<before> creating your first |
|
|
1573 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1574 | |
|
|
1575 | |
|
|
1576 | =head1 SECURITY CONSIDERATIONS |
|
|
1577 | |
|
|
1578 | AnyEvent can be forced to load any event model via |
|
|
1579 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1580 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1581 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1582 | will not be active when the program uses a different event model than |
|
|
1583 | specified in the variable. |
|
|
1584 | |
|
|
1585 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1586 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1587 | |
|
|
1588 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1589 | |
|
|
1590 | use AnyEvent; |
|
|
1591 | |
|
|
1592 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1593 | be used to probe what backend is used and gain other information (which is |
|
|
1594 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1595 | |
800 | |
1596 | |
801 | =head1 SEE ALSO |
1597 | =head1 SEE ALSO |
802 | |
1598 | |
803 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1599 | Utility functions: L<AnyEvent::Util>. |
804 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
|
|
805 | |
1600 | |
806 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1601 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1602 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
|
|
1603 | |
807 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
1604 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
808 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
1605 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1606 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1607 | L<AnyEvent::Impl::POE>. |
809 | |
1608 | |
|
|
1609 | Non-blocking file handles, sockets, TCP clients and |
|
|
1610 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1611 | |
|
|
1612 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1613 | |
|
|
1614 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1615 | |
810 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1616 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
811 | |
1617 | |
812 | =head1 |
1618 | |
|
|
1619 | =head1 AUTHOR |
|
|
1620 | |
|
|
1621 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1622 | http://home.schmorp.de/ |
813 | |
1623 | |
814 | =cut |
1624 | =cut |
815 | |
1625 | |
816 | 1 |
1626 | 1 |
817 | |
1627 | |