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80 | module. |
80 | module. |
81 | |
81 | |
82 | During the first call of any watcher-creation method, the module tries |
82 | 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 |
83 | 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>, |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
85 | L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>, |
85 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
86 | L<POE>. The first one found is used. If none are found, the module tries |
86 | L<POE>. The first one found is used. If none are found, the module tries |
87 | to load these modules (excluding Event::Lib, Qt and POE as the pure perl |
87 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
88 | adaptor should always succeed) in the order given. The first one that can |
88 | adaptor should always succeed) in the order given. The first one that can |
89 | be successfully loaded will be used. If, after this, still none could be |
89 | be successfully loaded will be used. If, after this, still none could be |
90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
91 | very efficient, but should work everywhere. |
91 | very efficient, but should work everywhere. |
92 | |
92 | |
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147 | events. C<poll> must be a string that is either C<r> or C<w>, which |
147 | events. C<poll> must be a string that is either C<r> or C<w>, which |
148 | creates a watcher waiting for "r"eadable or "w"ritable events, |
148 | creates a watcher waiting for "r"eadable or "w"ritable events, |
149 | respectively. C<cb> is the callback to invoke each time the file handle |
149 | respectively. C<cb> is the callback to invoke each time the file handle |
150 | becomes ready. |
150 | becomes ready. |
151 | |
151 | |
152 | As long as the I/O watcher exists it will keep the file descriptor or a |
152 | The I/O watcher might use the underlying file descriptor or a copy of it. |
153 | copy of it alive/open. |
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|
154 | |
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155 | It is not allowed to close a file handle as long as any watcher is active |
153 | You must not close a file handle as long as any watcher is active on the |
156 | on the underlying file descriptor. |
154 | underlying file descriptor. |
157 | |
155 | |
158 | Some event loops issue spurious readyness notifications, so you should |
156 | Some event loops issue spurious readyness notifications, so you should |
159 | always use non-blocking calls when reading/writing from/to your file |
157 | always use non-blocking calls when reading/writing from/to your file |
160 | handles. |
158 | handles. |
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159 | |
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160 | Although the callback might get passed parameters, their value and |
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161 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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162 | callbacks cannot use arguments passed to I/O watcher callbacks. |
161 | |
163 | |
162 | Example: |
164 | Example: |
163 | |
165 | |
164 | # wait for readability of STDIN, then read a line and disable the watcher |
166 | # wait for readability of STDIN, then read a line and disable the watcher |
165 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
167 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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179 | |
181 | |
180 | The timer callback will be invoked at most once: if you want a repeating |
182 | The timer callback will be invoked at most once: if you want a repeating |
181 | timer you have to create a new watcher (this is a limitation by both Tk |
183 | timer you have to create a new watcher (this is a limitation by both Tk |
182 | and Glib). |
184 | and Glib). |
183 | |
185 | |
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|
186 | Although the callback might get passed parameters, their value and |
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|
187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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188 | callbacks cannot use arguments passed to time watcher callbacks. |
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|
189 | |
184 | Example: |
190 | Example: |
185 | |
191 | |
186 | # fire an event after 7.7 seconds |
192 | # fire an event after 7.7 seconds |
187 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
193 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
188 | warn "timeout\n"; |
194 | warn "timeout\n"; |
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253 | watches for any child process exit). The watcher will trigger as often |
259 | watches for any child process exit). The watcher will trigger as often |
254 | as status change for the child are received. This works by installing a |
260 | as status change for the child are received. This works by installing a |
255 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
261 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
256 | and exit status (as returned by waitpid). |
262 | and exit status (as returned by waitpid). |
257 | |
263 | |
258 | Example: wait for pid 1333 |
264 | There is a slight catch to child watchers, however: you usually start them |
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|
265 | I<after> the child process was created, and this means the process could |
|
|
266 | have exited already (and no SIGCHLD will be sent anymore). |
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|
267 | |
|
|
268 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
269 | event models that I<do> handle this correctly, they usually need to be |
|
|
270 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
271 | |
|
|
272 | This means you cannot create a child watcher as the very first thing in an |
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273 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
274 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
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|
275 | |
|
|
276 | Example: fork a process and wait for it |
|
|
277 | |
|
|
278 | my $done = AnyEvent->condvar; |
|
|
279 | |
|
|
280 | AnyEvent::detect; # force event module to be initialised |
|
|
281 | |
|
|
282 | my $pid = fork or exit 5; |
259 | |
283 | |
260 | my $w = AnyEvent->child ( |
284 | my $w = AnyEvent->child ( |
261 | pid => 1333, |
285 | pid => $pid, |
262 | cb => sub { |
286 | cb => sub { |
263 | my ($pid, $status) = @_; |
287 | my ($pid, $status) = @_; |
264 | warn "pid $pid exited with status $status"; |
288 | warn "pid $pid exited with status $status"; |
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|
289 | $done->broadcast; |
265 | }, |
290 | }, |
266 | ); |
291 | ); |
|
|
292 | |
|
|
293 | # do something else, then wait for process exit |
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|
294 | $done->wait; |
267 | |
295 | |
268 | =head2 CONDITION VARIABLES |
296 | =head2 CONDITION VARIABLES |
269 | |
297 | |
270 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
298 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
271 | method without any arguments. |
299 | method without any arguments. |
… | |
… | |
359 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
387 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
360 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
388 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
361 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
389 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
362 | AnyEvent::Impl::Event based on Event, second best choice. |
390 | AnyEvent::Impl::Event based on Event, second best choice. |
363 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
391 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
392 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
364 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
393 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
365 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
366 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
394 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
367 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
395 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
368 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
396 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
369 | |
397 | |
370 | There is no support for WxWidgets, as WxWidgets has no support for |
398 | There is no support for WxWidgets, as WxWidgets has no support for |
… | |
… | |
906 | |
934 | |
907 | =head2 Results |
935 | =head2 Results |
908 | |
936 | |
909 | name watchers bytes create invoke destroy comment |
937 | name watchers bytes create invoke destroy comment |
910 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
938 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
911 | EV/Any 100000 610 3.52 0.91 0.75 EV + AnyEvent watchers |
939 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
912 | CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal |
940 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
913 | Perl/Any 100000 513 4.91 0.92 1.15 pure perl implementation |
941 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
914 | Event/Event 16000 523 28.05 21.38 0.86 Event native interface |
942 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
915 | Event/Any 16000 943 34.43 20.48 1.39 Event + AnyEvent watchers |
943 | Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers |
916 | Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour |
944 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
917 | Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers |
945 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
918 | POE/Event 2000 6644 108.15 768.19 14.33 via POE::Loop::Event |
946 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
919 | POE/Select 2000 6343 94.69 807.65 562.69 via POE::Loop::Select |
947 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
920 | |
948 | |
921 | =head2 Discussion |
949 | =head2 Discussion |
922 | |
950 | |
923 | The benchmark does I<not> measure scalability of the event loop very |
951 | The benchmark does I<not> measure scalability of the event loop very |
924 | well. For example, a select-based event loop (such as the pure perl one) |
952 | well. For example, a select-based event loop (such as the pure perl one) |
… | |
… | |
926 | file descriptors grows high. In this benchmark, all events become ready at |
954 | file descriptors grows high. In this benchmark, all events become ready at |
927 | the same time, so select/poll-based implementations get an unnatural speed |
955 | the same time, so select/poll-based implementations get an unnatural speed |
928 | boost. |
956 | boost. |
929 | |
957 | |
930 | C<EV> is the sole leader regarding speed and memory use, which are both |
958 | C<EV> is the sole leader regarding speed and memory use, which are both |
931 | maximal/minimal, respectively. Even when going through AnyEvent, there are |
959 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
932 | only two event loops that use slightly less memory (the C<Event> module |
960 | far less memory than any other event loop and is still faster than Event |
933 | natively and the pure perl backend), and no faster event models, not even |
961 | natively. |
934 | C<Event> natively. |
|
|
935 | |
962 | |
936 | The pure perl implementation is hit in a few sweet spots (both the |
963 | The pure perl implementation is hit in a few sweet spots (both the |
937 | zero timeout and the use of a single fd hit optimisations in the perl |
964 | zero timeout and the use of a single fd hit optimisations in the perl |
938 | interpreter and the backend itself, and all watchers become ready at the |
965 | interpreter and the backend itself, and all watchers become ready at the |
939 | same time). Nevertheless this shows that it adds very little overhead in |
966 | same time). Nevertheless this shows that it adds very little overhead in |