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 | Event, Coro, Glib, Tk, Perl - various supported event loops |
5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl - 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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14 | |
14 | |
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 wether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->broadcast; # wake up current and all future wait's |
21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
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23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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24 | |
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25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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26 | nowadays. So what is different about AnyEvent? |
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27 | |
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28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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29 | policy> and AnyEvent is I<small and efficient>. |
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30 | |
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31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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32 | interfaces to whatever event model the main program happens to use in a |
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33 | pragmatic way. For event models and certain classes of immortals alike, |
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34 | the statement "there can only be one" is a bitter reality, and AnyEvent |
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35 | helps hiding the differences. |
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36 | |
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37 | The goal of AnyEvent is to offer module authors the ability to do event |
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38 | programming (waiting for I/O or timer events) without subscribing to a |
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39 | religion, a way of living, and most importantly: without forcing your |
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40 | module users into the same thing by forcing them to use the same event |
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41 | model you use. |
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42 | |
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43 | For modules like POE or IO::Async (which is actually doing all I/O |
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44 | I<synchronously>...), using them in your module is like joining a |
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45 | cult: After you joined, you are dependent on them and you cannot use |
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46 | anything else, as it is simply incompatible to everything that isn't |
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47 | itself. |
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48 | |
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49 | AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
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50 | works fine etc. etc. but none of these work together with the rest: POE |
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51 | + IO::Async? no go. Tk + Event? no go. If your module uses one of |
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52 | those, every user of your module has to use it, too. If your module |
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53 | uses AnyEvent, it works transparently with all event models it supports |
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54 | (including stuff like POE and IO::Async). |
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55 | |
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56 | In addition of being free of having to use I<the one and only true event |
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57 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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58 | modules, you get an enourmous amount of code and strict rules you have |
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59 | to follow. AnyEvent, on the other hand, is lean and to the point by only |
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60 | offering the functionality that is useful, in as thin as a wrapper as |
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61 | technically possible. |
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62 | |
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63 | Of course, if you want lots of policy (this can arguably be somewhat |
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64 | useful) and you want to force your users to use the one and only event |
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65 | model, you should I<not> use this module. |
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66 | |
22 | |
67 | |
23 | =head1 DESCRIPTION |
68 | =head1 DESCRIPTION |
24 | |
69 | |
25 | L<AnyEvent> provides an identical interface to multiple event loops. This |
70 | L<AnyEvent> provides an identical interface to multiple event loops. This |
26 | allows module authors to utilise an event loop without forcing module |
71 | allows module authors to utilise an event loop without forcing module |
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29 | |
74 | |
30 | The interface itself is vaguely similar but not identical to the Event |
75 | The interface itself is vaguely similar but not identical to the Event |
31 | module. |
76 | module. |
32 | |
77 | |
33 | On the first call of any method, the module tries to detect the currently |
78 | On the first call of any method, the module tries to detect the currently |
34 | loaded event loop by probing wether any of the following modules is |
79 | loaded event loop by probing whether any of the following modules is |
35 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
80 | loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, L<Event>, L<Glib>, L<Tk>. The |
36 | used. If none is found, the module tries to load these modules in the |
81 | first one found is used. If none are found, the module tries to load these |
37 | order given. The first one that could be successfully loaded will be |
82 | modules in the order given. The first one that could be successfully |
38 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
83 | loaded will be used. If still none could be found, AnyEvent will fall back |
39 | event loop, which is also not very efficient. |
84 | to a pure-perl event loop, which is also not very efficient. |
40 | |
85 | |
41 | Because AnyEvent first checks for modules that are already loaded, loading |
86 | Because AnyEvent first checks for modules that are already loaded, loading |
42 | an Event model explicitly before first using AnyEvent will likely make |
87 | an Event model explicitly before first using AnyEvent will likely make |
43 | that model the default. For example: |
88 | that model the default. For example: |
44 | |
89 | |
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70 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
115 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
71 | the following mandatory arguments: |
116 | the following mandatory arguments: |
72 | |
117 | |
73 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
118 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
74 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
119 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
75 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback |
120 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
76 | to invoke everytime the filehandle becomes ready. |
121 | to invoke everytime the filehandle becomes ready. |
77 | |
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78 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
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79 | a socket you can have one r + one w, not any more (limitation comes from |
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80 | Tk - if you are sure you are not using Tk this limitation is gone). |
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81 | |
122 | |
82 | Filehandles will be kept alive, so as long as the watcher exists, the |
123 | Filehandles will be kept alive, so as long as the watcher exists, the |
83 | filehandle exists, too. |
124 | filehandle exists, too. |
84 | |
125 | |
85 | Example: |
126 | Example: |
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109 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
150 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
110 | warn "timeout\n"; |
151 | warn "timeout\n"; |
111 | }); |
152 | }); |
112 | |
153 | |
113 | # to cancel the timer: |
154 | # to cancel the timer: |
114 | undef $w |
155 | undef $w; |
115 | |
156 | |
116 | =head2 CONDITION WATCHERS |
157 | =head2 CONDITION WATCHERS |
117 | |
158 | |
118 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
159 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
119 | method without any arguments. |
160 | method without any arguments. |
120 | |
161 | |
121 | A condition watcher watches for a condition - precisely that the C<< |
162 | A condition watcher watches for a condition - precisely that the C<< |
122 | ->broadcast >> method has been called. |
163 | ->broadcast >> method has been called. |
123 | |
164 | |
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165 | Note that condition watchers recurse into the event loop - if you have |
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166 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
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167 | lose. Therefore, condition watchers are good to export to your caller, but |
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168 | you should avoid making a blocking wait, at least in callbacks, as this |
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169 | usually asks for trouble. |
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170 | |
124 | The watcher has only two methods: |
171 | The watcher has only two methods: |
125 | |
172 | |
126 | =over 4 |
173 | =over 4 |
127 | |
174 | |
128 | =item $cv->wait |
175 | =item $cv->wait |
129 | |
176 | |
130 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
177 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
131 | called on c<$cv>, while servicing other watchers normally. |
178 | called on c<$cv>, while servicing other watchers normally. |
132 | |
179 | |
133 | Not all event models support a blocking wait - some die in that case, so |
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134 | if you are using this from a module, never require a blocking wait, but |
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135 | let the caller decide wether the call will block or not (for example, |
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136 | by coupling condition variables with some kind of request results and |
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137 | supporting callbacks so the caller knows that getting the result will not |
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138 | block, while still suppporting blockign waits if the caller so desires). |
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139 | |
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140 | You can only wait once on a condition - additional calls will return |
180 | You can only wait once on a condition - additional calls will return |
141 | immediately. |
181 | immediately. |
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182 | |
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183 | Not all event models support a blocking wait - some die in that case |
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184 | (programs might want to do that so they stay interactive), so I<if you |
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185 | are using this from a module, never require a blocking wait>, but let the |
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186 | caller decide whether the call will block or not (for example, by coupling |
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187 | condition variables with some kind of request results and supporting |
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188 | callbacks so the caller knows that getting the result will not block, |
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189 | while still suppporting blocking waits if the caller so desires). |
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190 | |
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191 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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192 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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193 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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194 | can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
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195 | explicitly support concurrent C<< ->wait >>'s from different coroutines, |
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196 | however). |
142 | |
197 | |
143 | =item $cv->broadcast |
198 | =item $cv->broadcast |
144 | |
199 | |
145 | Flag the condition as ready - a running C<< ->wait >> and all further |
200 | Flag the condition as ready - a running C<< ->wait >> and all further |
146 | calls to C<wait> will return after this method has been called. If nobody |
201 | calls to C<wait> will return after this method has been called. If nobody |
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174 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
229 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
175 | |
230 | |
176 | =head2 CHILD PROCESS WATCHERS |
231 | =head2 CHILD PROCESS WATCHERS |
177 | |
232 | |
178 | You can also listen for the status of a child process specified by the |
233 | You can also listen for the status of a child process specified by the |
179 | C<pid> argument. The watcher will only trigger once. This works by |
234 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
180 | installing a signal handler for C<SIGCHLD>. |
235 | trigger as often as status change for the child are received. This works |
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236 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
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237 | the pid and exit status (as returned by waitpid). |
181 | |
238 | |
182 | Example: wait for pid 1333 |
239 | Example: wait for pid 1333 |
183 | |
240 | |
184 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
241 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
185 | |
242 | |
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195 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
252 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
196 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
253 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
197 | |
254 | |
198 | The known classes so far are: |
255 | The known classes so far are: |
199 | |
256 | |
200 | AnyEvent::Impl::Coro based on Coro::Event, best choise. |
257 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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258 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
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259 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
201 | AnyEvent::Impl::Event based on Event, also best choice :) |
260 | AnyEvent::Impl::Event based on Event, also second best choice :) |
202 | AnyEvent::Impl::Glib based on Glib, second-best choice. |
261 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
203 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
262 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
204 | AnyEvent::Impl::Perl pure-perl implementation, inefficient. |
263 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
205 | |
264 | |
206 | =item AnyEvent::detect |
265 | =item AnyEvent::detect |
207 | |
266 | |
208 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
267 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
209 | necessary. You should only call this function right before you would have |
268 | necessary. You should only call this function right before you would have |
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248 | no warnings; |
307 | no warnings; |
249 | use strict; |
308 | use strict; |
250 | |
309 | |
251 | use Carp; |
310 | use Carp; |
252 | |
311 | |
253 | our $VERSION = '2.53'; |
312 | our $VERSION = '3.1'; |
254 | our $MODEL; |
313 | our $MODEL; |
255 | |
314 | |
256 | our $AUTOLOAD; |
315 | our $AUTOLOAD; |
257 | our @ISA; |
316 | our @ISA; |
258 | |
317 | |
259 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
318 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
260 | |
319 | |
261 | our @REGISTRY; |
320 | our @REGISTRY; |
262 | |
321 | |
263 | my @models = ( |
322 | my @models = ( |
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323 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
264 | [Coro::Event:: => AnyEvent::Impl::Coro::], |
324 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
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325 | [EV:: => AnyEvent::Impl::EV::], |
265 | [Event:: => AnyEvent::Impl::Event::], |
326 | [Event:: => AnyEvent::Impl::Event::], |
266 | [Glib:: => AnyEvent::Impl::Glib::], |
327 | [Glib:: => AnyEvent::Impl::Glib::], |
267 | [Tk:: => AnyEvent::Impl::Tk::], |
328 | [Tk:: => AnyEvent::Impl::Tk::], |
268 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
329 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
269 | ); |
330 | ); |
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299 | last; |
360 | last; |
300 | } |
361 | } |
301 | } |
362 | } |
302 | |
363 | |
303 | $MODEL |
364 | $MODEL |
304 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; |
365 | 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."; |
305 | } |
366 | } |
306 | |
367 | |
307 | unshift @ISA, $MODEL; |
368 | unshift @ISA, $MODEL; |
308 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
369 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
309 | } |
370 | } |
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367 | |
428 | |
368 | # default implementation for ->child |
429 | # default implementation for ->child |
369 | |
430 | |
370 | our %PID_CB; |
431 | our %PID_CB; |
371 | our $CHLD_W; |
432 | our $CHLD_W; |
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433 | our $CHLD_DELAY_W; |
372 | our $PID_IDLE; |
434 | our $PID_IDLE; |
373 | our $WNOHANG; |
435 | our $WNOHANG; |
374 | |
436 | |
375 | sub _child_wait { |
437 | sub _child_wait { |
376 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
438 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
377 | $_->() for values %{ (delete $PID_CB{$pid}) || {} }; |
439 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
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440 | (values %{ $PID_CB{0} || {} }); |
378 | } |
441 | } |
379 | |
442 | |
380 | undef $PID_IDLE; |
443 | undef $PID_IDLE; |
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444 | } |
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445 | |
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446 | sub _sigchld { |
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447 | # make sure we deliver these changes "synchronous" with the event loop. |
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448 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
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449 | undef $CHLD_DELAY_W; |
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450 | &_child_wait; |
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451 | }); |
381 | } |
452 | } |
382 | |
453 | |
383 | sub child { |
454 | sub child { |
384 | my (undef, %arg) = @_; |
455 | my (undef, %arg) = @_; |
385 | |
456 | |
386 | my $pid = uc $arg{pid} |
457 | defined (my $pid = $arg{pid} + 0) |
387 | or Carp::croak "required option 'pid' is missing"; |
458 | or Carp::croak "required option 'pid' is missing"; |
388 | |
459 | |
389 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
460 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
390 | |
461 | |
391 | unless ($WNOHANG) { |
462 | unless ($WNOHANG) { |
392 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
463 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
393 | } |
464 | } |
394 | |
465 | |
395 | unless ($CHLD_W) { |
466 | unless ($CHLD_W) { |
396 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); |
467 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
397 | # child could be a zombie already |
468 | # child could be a zombie already, so make at least one round |
398 | $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); |
469 | &_sigchld; |
399 | } |
470 | } |
400 | |
471 | |
401 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
472 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
402 | } |
473 | } |
403 | |
474 | |
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556 | $txn->{finished}->wait; |
627 | $txn->{finished}->wait; |
557 | return $txn->{result}; |
628 | return $txn->{result}; |
558 | |
629 | |
559 | The actual code goes further and collects all errors (C<die>s, exceptions) |
630 | The actual code goes further and collects all errors (C<die>s, exceptions) |
560 | that occured during request processing. The C<result> method detects |
631 | that occured during request processing. The C<result> method detects |
561 | wether an exception as thrown (it is stored inside the $txn object) |
632 | whether an exception as thrown (it is stored inside the $txn object) |
562 | and just throws the exception, which means connection errors and other |
633 | and just throws the exception, which means connection errors and other |
563 | problems get reported tot he code that tries to use the result, not in a |
634 | problems get reported tot he code that tries to use the result, not in a |
564 | random callback. |
635 | random callback. |
565 | |
636 | |
566 | All of this enables the following usage styles: |
637 | All of this enables the following usage styles: |
567 | |
638 | |
568 | 1. Blocking: |
639 | 1. Blocking: |
569 | |
640 | |
570 | my $data = $fcp->client_get ($url); |
641 | my $data = $fcp->client_get ($url); |
571 | |
642 | |
572 | 2. Blocking, but parallelizing: |
643 | 2. Blocking, but running in parallel: |
573 | |
644 | |
574 | my @datas = map $_->result, |
645 | my @datas = map $_->result, |
575 | map $fcp->txn_client_get ($_), |
646 | map $fcp->txn_client_get ($_), |
576 | @urls; |
647 | @urls; |
577 | |
648 | |
578 | Both blocking examples work without the module user having to know |
649 | Both blocking examples work without the module user having to know |
579 | anything about events. |
650 | anything about events. |
580 | |
651 | |
581 | 3a. Event-based in a main program, using any support Event module: |
652 | 3a. Event-based in a main program, using any supported event module: |
582 | |
653 | |
583 | use Event; |
654 | use EV; |
584 | |
655 | |
585 | $fcp->txn_client_get ($url)->cb (sub { |
656 | $fcp->txn_client_get ($url)->cb (sub { |
586 | my $txn = shift; |
657 | my $txn = shift; |
587 | my $data = $txn->result; |
658 | my $data = $txn->result; |
588 | ... |
659 | ... |
589 | }); |
660 | }); |
590 | |
661 | |
591 | Event::loop; |
662 | EV::loop; |
592 | |
663 | |
593 | 3b. The module user could use AnyEvent, too: |
664 | 3b. The module user could use AnyEvent, too: |
594 | |
665 | |
595 | use AnyEvent; |
666 | use AnyEvent; |
596 | |
667 | |
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603 | |
674 | |
604 | $quit->wait; |
675 | $quit->wait; |
605 | |
676 | |
606 | =head1 SEE ALSO |
677 | =head1 SEE ALSO |
607 | |
678 | |
608 | Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. |
679 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
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680 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
609 | |
681 | |
610 | Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. |
682 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
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683 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
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684 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
611 | |
685 | |
612 | Nontrivial usage example: L<Net::FCP>. |
686 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
613 | |
687 | |
614 | =head1 |
688 | =head1 |
615 | |
689 | |
616 | =cut |
690 | =cut |
617 | |
691 | |