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Revision 1.47 by root, Mon Apr 14 16:09:33 2008 UTC vs.
Revision 1.57 by root, Thu Apr 24 03:19:28 2008 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5Event, Coro, Glib, Tk, Perl - various supported event loops 5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
… …
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
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
… …
29policy> and AnyEvent is I<small and efficient>. 29policy> and AnyEvent is I<small and efficient>.
30 30
31First and foremost, I<AnyEvent is not an event model> itself, it only 31First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a 32interfaces to whatever event model the main program happens to use in a
33pragmatic way. For event models and certain classes of immortals alike, 33pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality, and AnyEvent 34the statement "there can only be one" is a bitter reality: In general,
35helps hiding the differences. 35only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops.
36 37
37The goal of AnyEvent is to offer module authors the ability to do event 38The goal of AnyEvent is to offer module authors the ability to do event
38programming (waiting for I/O or timer events) without subscribing to a 39programming (waiting for I/O or timer events) without subscribing to a
39religion, a way of living, and most importantly: without forcing your 40religion, a way of living, and most importantly: without forcing your
40module users into the same thing by forcing them to use the same event 41module users into the same thing by forcing them to use the same event
41model you use. 42model you use.
42 43
43For modules like POE or IO::Async (which is actually doing all I/O 44For modules like POE or IO::Async (which is a total misnomer as it is
44I<synchronously>...), using them in your module is like joining a 45actually doing all I/O I<synchronously>...), using them in your module is
45cult: After you joined, you are dependent on them and you cannot use 46like joining a cult: After you joined, you are dependent on them and you
46anything else, as it is simply incompatible to everything that isn't 47cannot use anything else, as it is simply incompatible to everything that
47itself. 48isn't itself. What's worse, all the potential users of your module are
49I<also> forced to use the same event loop you use.
48 50
49AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk 51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50works fine etc. etc. but none of these work together with the rest: POE 52fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51+ IO::Async? no go. Tk + Event? no go. If your module uses one of 53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
52those, every user of your module has to use it, too. If your module 54your module uses one of those, every user of your module has to use it,
53uses AnyEvent, it works transparently with all event models it supports 55too. But if your module uses AnyEvent, it works transparently with all
54(including stuff like POE and IO::Async). 56event models it supports (including stuff like POE and IO::Async, as long
57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof).
55 59
56In addition of being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
57model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
58modules, you get an enourmous amount of code and strict rules you have 62modules, you get an enourmous amount of code and strict rules you have to
59to follow. AnyEvent, on the other hand, is lean and to the point by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
60offering the functionality that is useful, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
61technically possible. 65technically possible.
62 66
63Of course, if you want lots of policy (this can arguably be somewhat 67Of course, if you want lots of policy (this can arguably be somewhat
64useful) and you want to force your users to use the one and only event 68useful) and you want to force your users to use the one and only event
65model, you should I<not> use this module. 69model, you should I<not> use this module.
… …
70L<AnyEvent> provides an identical interface to multiple event loops. This 74L<AnyEvent> provides an identical interface to multiple event loops. This
71allows module authors to utilise an event loop without forcing module 75allows module authors to utilise an event loop without forcing module
72users to use the same event loop (as only a single event loop can coexist 76users to use the same event loop (as only a single event loop can coexist
73peacefully at any one time). 77peacefully at any one time).
74 78
75The interface itself is vaguely similar but not identical to the Event 79The interface itself is vaguely similar, but not identical to the L<Event>
76module. 80module.
77 81
78On the first call of any method, the module tries to detect the currently 82During the first call of any watcher-creation method, the module tries
79loaded event loop by probing wether any of the following modules is 83to detect the currently loaded event loop by probing whether one of
80loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is 84the following modules is already loaded: L<Coro::EV>, L<Coro::Event>,
85L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one
81used. If none is found, the module tries to load these modules in the 86found is used. If none are found, the module tries to load these modules
82order given. The first one that could be successfully loaded will be 87(excluding Event::Lib and Qt) in the order given. The first one that can
83used. If still none could be found, AnyEvent will fall back to a pure-perl 88be successfully loaded will be used. If, after this, still none could be
84event loop, which is also not very efficient. 89found, AnyEvent will fall back to a pure-perl event loop, which is not
90very efficient, but should work everywhere.
85 91
86Because AnyEvent first checks for modules that are already loaded, loading 92Because AnyEvent first checks for modules that are already loaded, loading
87an Event model explicitly before first using AnyEvent will likely make 93an event model explicitly before first using AnyEvent will likely make
88that model the default. For example: 94that model the default. For example:
89 95
90 use Tk; 96 use Tk;
91 use AnyEvent; 97 use AnyEvent;
92 98
93 # .. AnyEvent will likely default to Tk 99 # .. AnyEvent will likely default to Tk
100
101The I<likely> means that, if any module loads another event model and
102starts using it, all bets are off. Maybe you should tell their authors to
103use AnyEvent so their modules work together with others seamlessly...
94 104
95The pure-perl implementation of AnyEvent is called 105The pure-perl implementation of AnyEvent is called
96C<AnyEvent::Impl::Perl>. Like other event modules you can load it 106C<AnyEvent::Impl::Perl>. Like other event modules you can load it
97explicitly. 107explicitly.
98 108
… …
101AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
102stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
103the callback to call, the filehandle to watch, etc. 113the callback to call, the filehandle to watch, etc.
104 114
105These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
106creating a watcher it will immediately "watch" for events and invoke 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model
118is in control).
119
107the callback. To disable the watcher you have to destroy it (e.g. by 120To disable the watcher you have to destroy it (e.g. by setting the
108setting the variable that stores it to C<undef> or otherwise deleting all 121variable you store it in to C<undef> or otherwise deleting all references
109references to it). 122to it).
110 123
111All watchers are created by calling a method on the C<AnyEvent> class. 124All watchers are created by calling a method on the C<AnyEvent> class.
112 125
126Many watchers either are used with "recursion" (repeating timers for
127example), or need to refer to their watcher object in other ways.
128
129An any way to achieve that is this pattern:
130
131 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132 # you can use $w here, for example to undef it
133 undef $w;
134 });
135
136Note that C<my $w; $w => combination. This is necessary because in Perl,
137my variables are only visible after the statement in which they are
138declared.
139
113=head2 IO WATCHERS 140=head2 IO WATCHERS
114 141
115You can create I/O watcher by calling the C<< AnyEvent->io >> method with 142You can create an I/O watcher by calling the C<< AnyEvent->io >> method
116the following mandatory arguments: 143with the following mandatory key-value pairs as arguments:
117 144
118C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
119events. C<poll> must be a string that is either C<r> or C<w>, that creates 146events. C<poll> must be a string that is either C<r> or C<w>, which
120a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback 147creates a watcher waiting for "r"eadable or "w"ritable events,
121to invoke everytime the filehandle becomes ready. 148respectively. C<cb> is the callback to invoke each time the file handle
149becomes ready.
122 150
123Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on 151As long as the I/O watcher exists it will keep the file descriptor or a
124a socket you can have one r + one w, not any more (limitation comes from 152copy of it alive/open.
125Tk - if you are sure you are not using Tk this limitation is gone).
126 153
127Filehandles will be kept alive, so as long as the watcher exists, the 154It is not allowed to close a file handle as long as any watcher is active
128filehandle exists, too. 155on the underlying file descriptor.
156
157Some event loops issue spurious readyness notifications, so you should
158always use non-blocking calls when reading/writing from/to your file
159handles.
129 160
130Example: 161Example:
131 162
132 # wait for readability of STDIN, then read a line and disable the watcher 163 # wait for readability of STDIN, then read a line and disable the watcher
133 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 164 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
139=head2 TIME WATCHERS 170=head2 TIME WATCHERS
140 171
141You can create a time watcher by calling the C<< AnyEvent->timer >> 172You can create a time watcher by calling the C<< AnyEvent->timer >>
142method with the following mandatory arguments: 173method with the following mandatory arguments:
143 174
144C<after> after how many seconds (fractions are supported) should the timer 175C<after> specifies after how many seconds (fractional values are
145activate. C<cb> the callback to invoke. 176supported) should the timer activate. C<cb> the callback to invoke in that
177case.
146 178
147The timer callback will be invoked at most once: if you want a repeating 179The timer callback will be invoked at most once: if you want a repeating
148timer you have to create a new watcher (this is a limitation by both Tk 180timer you have to create a new watcher (this is a limitation by both Tk
149and Glib). 181and Glib).
150 182
… …
156 }); 188 });
157 189
158 # to cancel the timer: 190 # to cancel the timer:
159 undef $w; 191 undef $w;
160 192
193Example 2:
194
195 # fire an event after 0.5 seconds, then roughly every second
196 my $w;
197
198 my $cb = sub {
199 # cancel the old timer while creating a new one
200 $w = AnyEvent->timer (after => 1, cb => $cb);
201 };
202
203 # start the "loop" by creating the first watcher
204 $w = AnyEvent->timer (after => 0.5, cb => $cb);
205
206=head3 TIMING ISSUES
207
208There are two ways to handle timers: based on real time (relative, "fire
209in 10 seconds") and based on wallclock time (absolute, "fire at 12
210o'clock").
211
212While most event loops expect timers to specified in a relative way, they use
213absolute time internally. This makes a difference when your clock "jumps",
214for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to
2152008-01-01, a watcher that you created to fire "after" a second might actually take
216six years to finally fire.
217
218AnyEvent cannot compensate for this. The only event loop that is conscious
219about these issues is L<EV>, which offers both relative (ev_timer) and
220absolute (ev_periodic) timers.
221
222AnyEvent always prefers relative timers, if available, matching the
223AnyEvent API.
224
225=head2 SIGNAL WATCHERS
226
227You can watch for signals using a signal watcher, C<signal> is the signal
228I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
229be invoked whenever a signal occurs.
230
231Multiple signals occurances can be clumped together into one callback
232invocation, and callback invocation will be synchronous. synchronous means
233that it might take a while until the signal gets handled by the process,
234but it is guarenteed not to interrupt any other callbacks.
235
236The main advantage of using these watchers is that you can share a signal
237between multiple watchers.
238
239This watcher might use C<%SIG>, so programs overwriting those signals
240directly will likely not work correctly.
241
242Example: exit on SIGINT
243
244 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
245
246=head2 CHILD PROCESS WATCHERS
247
248You can also watch on a child process exit and catch its exit status.
249
250The child process is specified by the C<pid> argument (if set to C<0>, it
251watches for any child process exit). The watcher will trigger as often
252as status change for the child are received. This works by installing a
253signal handler for C<SIGCHLD>. The callback will be called with the pid
254and exit status (as returned by waitpid).
255
256Example: wait for pid 1333
257
258 my $w = AnyEvent->child (
259 pid => 1333,
260 cb => sub {
261 my ($pid, $status) = @_;
262 warn "pid $pid exited with status $status";
263 },
264 );
265
161=head2 CONDITION WATCHERS 266=head2 CONDITION VARIABLES
162 267
163Condition watchers can be created by calling the C<< AnyEvent->condvar >> 268Condition variables can be created by calling the C<< AnyEvent->condvar >>
164method without any arguments. 269method without any arguments.
165 270
166A condition watcher watches for a condition - precisely that the C<< 271A condition variable waits for a condition - precisely that the C<<
167->broadcast >> method has been called. 272->broadcast >> method has been called.
168 273
274They are very useful to signal that a condition has been fulfilled, for
275example, if you write a module that does asynchronous http requests,
276then a condition variable would be the ideal candidate to signal the
277availability of results.
278
279You can also use condition variables to block your main program until
280an event occurs - for example, you could C<< ->wait >> in your main
281program until the user clicks the Quit button in your app, which would C<<
282->broadcast >> the "quit" event.
283
169Note that condition watchers recurse into the event loop - if you have 284Note that condition variables recurse into the event loop - if you have
170two watchers that call C<< ->wait >> in a round-robbin fashion, you 285two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
171lose. Therefore, condition watchers are good to export to your caller, but 286lose. Therefore, condition variables are good to export to your caller, but
172you should avoid making a blocking wait, at least in callbacks, as this 287you should avoid making a blocking wait yourself, at least in callbacks,
173usually asks for trouble. 288as this asks for trouble.
174 289
175The watcher has only two methods: 290This object has two methods:
176 291
177=over 4 292=over 4
178 293
179=item $cv->wait 294=item $cv->wait
180 295
… …
183 298
184You can only wait once on a condition - additional calls will return 299You can only wait once on a condition - additional calls will return
185immediately. 300immediately.
186 301
187Not all event models support a blocking wait - some die in that case 302Not all event models support a blocking wait - some die in that case
188(programs might want to do that so they stay interactive), so I<if you 303(programs might want to do that to stay interactive), so I<if you are
189are using this from a module, never require a blocking wait>, but let the 304using this from a module, never require a blocking wait>, but let the
190caller decide wether the call will block or not (for example, by coupling 305caller decide whether the call will block or not (for example, by coupling
191condition variables with some kind of request results and supporting 306condition variables with some kind of request results and supporting
192callbacks so the caller knows that getting the result will not block, 307callbacks so the caller knows that getting the result will not block,
193while still suppporting blocking waits if the caller so desires). 308while still suppporting blocking waits if the caller so desires).
194 309
195Another reason I<never> to C<< ->wait >> in a module is that you cannot 310Another reason I<never> to C<< ->wait >> in a module is that you cannot
196sensibly have two C<< ->wait >>'s in parallel, as that would require 311sensibly have two C<< ->wait >>'s in parallel, as that would require
197multiple interpreters or coroutines/threads, none of which C<AnyEvent> 312multiple interpreters or coroutines/threads, none of which C<AnyEvent>
198can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> 313can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
199explicitly support concurrent C<< ->wait >>'s from different coroutines, 314L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
200however). 315from different coroutines, however).
201 316
202=item $cv->broadcast 317=item $cv->broadcast
203 318
204Flag the condition as ready - a running C<< ->wait >> and all further 319Flag the condition as ready - a running C<< ->wait >> and all further
205calls to C<wait> will return after this method has been called. If nobody 320calls to C<wait> will (eventually) return after this method has been
206is waiting the broadcast will be remembered.. 321called. If nobody is waiting the broadcast will be remembered..
322
323=back
207 324
208Example: 325Example:
209 326
210 # wait till the result is ready 327 # wait till the result is ready
211 my $result_ready = AnyEvent->condvar; 328 my $result_ready = AnyEvent->condvar;
212 329
213 # do something such as adding a timer 330 # do something such as adding a timer
214 # or socket watcher the calls $result_ready->broadcast 331 # or socket watcher the calls $result_ready->broadcast
215 # when the "result" is ready. 332 # when the "result" is ready.
333 # in this case, we simply use a timer:
334 my $w = AnyEvent->timer (
335 after => 1,
336 cb => sub { $result_ready->broadcast },
337 );
216 338
339 # this "blocks" (while handling events) till the watcher
340 # calls broadcast
217 $result_ready->wait; 341 $result_ready->wait;
218 342
219=back 343=head1 GLOBAL VARIABLES AND FUNCTIONS
220
221=head2 SIGNAL WATCHERS
222
223You can listen for signals using a signal watcher, C<signal> is the signal
224I<name> without any C<SIG> prefix. Multiple signals events can be clumped
225together into one callback invocation, and callback invocation might or
226might not be asynchronous.
227
228These watchers might use C<%SIG>, so programs overwriting those signals
229directly will likely not work correctly.
230
231Example: exit on SIGINT
232
233 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
234
235=head2 CHILD PROCESS WATCHERS
236
237You can also listen for the status of a child process specified by the
238C<pid> argument (or any child if the pid argument is 0). The watcher will
239trigger as often as status change for the child are received. This works
240by installing a signal handler for C<SIGCHLD>. The callback will be called with
241the pid and exit status (as returned by waitpid).
242
243Example: wait for pid 1333
244
245 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
246
247=head1 GLOBALS
248 344
249=over 4 345=over 4
250 346
251=item $AnyEvent::MODEL 347=item $AnyEvent::MODEL
252 348
… …
257AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 353AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
258 354
259The known classes so far are: 355The known classes so far are:
260 356
261 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 357 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
262 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
263 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 358 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
359 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
264 AnyEvent::Impl::Event based on Event, also second best choice :) 360 AnyEvent::Impl::Event based on Event, second best choice.
265 AnyEvent::Impl::Glib based on Glib, second-best choice. 361 AnyEvent::Impl::Glib based on Glib, third-best choice.
266 AnyEvent::Impl::Tk based on Tk, very bad choice. 362 AnyEvent::Impl::Tk based on Tk, very bad choice.
267 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 363 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
364 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
365 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
268 366
269=item AnyEvent::detect 367=item AnyEvent::detect
270 368
271Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 369Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
272necessary. You should only call this function right before you would have 370if necessary. You should only call this function right before you would
273created an AnyEvent watcher anyway, that is, very late at runtime. 371have created an AnyEvent watcher anyway, that is, as late as possible at
372runtime.
274 373
275=back 374=back
276 375
277=head1 WHAT TO DO IN A MODULE 376=head1 WHAT TO DO IN A MODULE
278 377
279As a module author, you should "use AnyEvent" and call AnyEvent methods 378As a module author, you should C<use AnyEvent> and call AnyEvent methods
280freely, but you should not load a specific event module or rely on it. 379freely, but you should not load a specific event module or rely on it.
281 380
282Be careful when you create watchers in the module body - Anyevent will 381Be careful when you create watchers in the module body - AnyEvent will
283decide which event module to use as soon as the first method is called, so 382decide which event module to use as soon as the first method is called, so
284by calling AnyEvent in your module body you force the user of your module 383by calling AnyEvent in your module body you force the user of your module
285to load the event module first. 384to load the event module first.
286 385
386Never call C<< ->wait >> on a condition variable unless you I<know> that
387the C<< ->broadcast >> method has been called on it already. This is
388because it will stall the whole program, and the whole point of using
389events is to stay interactive.
390
391It is fine, however, to call C<< ->wait >> when the user of your module
392requests it (i.e. if you create a http request object ad have a method
393called C<results> that returns the results, it should call C<< ->wait >>
394freely, as the user of your module knows what she is doing. always).
395
287=head1 WHAT TO DO IN THE MAIN PROGRAM 396=head1 WHAT TO DO IN THE MAIN PROGRAM
288 397
289There will always be a single main program - the only place that should 398There will always be a single main program - the only place that should
290dictate which event model to use. 399dictate which event model to use.
291 400
292If it doesn't care, it can just "use AnyEvent" and use it itself, or not 401If it doesn't care, it can just "use AnyEvent" and use it itself, or not
293do anything special and let AnyEvent decide which implementation to chose. 402do anything special (it does not need to be event-based) and let AnyEvent
403decide which implementation to chose if some module relies on it.
294 404
295If the main program relies on a specific event model (for example, in Gtk2 405If the main program relies on a specific event model. For example, in
296programs you have to rely on either Glib or Glib::Event), you should load 406Gtk2 programs you have to rely on the Glib module. You should load the
297it before loading AnyEvent or any module that uses it, generally, as early 407event module before loading AnyEvent or any module that uses it: generally
298as possible. The reason is that modules might create watchers when they 408speaking, you should load it as early as possible. The reason is that
299are loaded, and AnyEvent will decide on the event model to use as soon as 409modules might create watchers when they are loaded, and AnyEvent will
300it creates watchers, and it might chose the wrong one unless you load the 410decide on the event model to use as soon as it creates watchers, and it
301correct one yourself. 411might chose the wrong one unless you load the correct one yourself.
302 412
303You can chose to use a rather inefficient pure-perl implementation by 413You can chose to use a rather inefficient pure-perl implementation by
304loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 414loading the C<AnyEvent::Impl::Perl> module, which gives you similar
305generally better. 415behaviour everywhere, but letting AnyEvent chose is generally better.
306 416
307=cut 417=cut
308 418
309package AnyEvent; 419package AnyEvent;
310 420
311no warnings; 421no warnings;
312use strict; 422use strict;
313 423
314use Carp; 424use Carp;
315 425
316our $VERSION = '3.0'; 426our $VERSION = '3.12';
317our $MODEL; 427our $MODEL;
318 428
319our $AUTOLOAD; 429our $AUTOLOAD;
320our @ISA; 430our @ISA;
321 431
… …
323 433
324our @REGISTRY; 434our @REGISTRY;
325 435
326my @models = ( 436my @models = (
327 [Coro::EV:: => AnyEvent::Impl::CoroEV::], 437 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
438 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
328 [EV:: => AnyEvent::Impl::EV::], 439 [EV:: => AnyEvent::Impl::EV::],
329 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
330 [Event:: => AnyEvent::Impl::Event::], 440 [Event:: => AnyEvent::Impl::Event::],
331 [Glib:: => AnyEvent::Impl::Glib::], 441 [Glib:: => AnyEvent::Impl::Glib::],
332 [Tk:: => AnyEvent::Impl::Tk::], 442 [Tk:: => AnyEvent::Impl::Tk::],
333 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 443 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
334); 444);
445my @models_detect = (
446 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
447 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
448);
335 449
336our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 450our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
337 451
338sub detect() { 452sub detect() {
339 unless ($MODEL) { 453 unless ($MODEL) {
340 no strict 'refs'; 454 no strict 'refs';
341 455
456 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
457 my $model = "AnyEvent::Impl::$1";
458 if (eval "require $model") {
459 $MODEL = $model;
460 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
461 }
462 }
463
342 # check for already loaded models 464 # check for already loaded models
465 unless ($MODEL) {
343 for (@REGISTRY, @models) { 466 for (@REGISTRY, @models, @models_detect) {
344 my ($package, $model) = @$_; 467 my ($package, $model) = @$_;
345 if (${"$package\::VERSION"} > 0) { 468 if (${"$package\::VERSION"} > 0) {
346 if (eval "require $model") { 469 if (eval "require $model") {
347 $MODEL = $model; 470 $MODEL = $model;
348 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 471 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
349 last; 472 last;
473 }
350 } 474 }
351 } 475 }
352 }
353 476
354 unless ($MODEL) { 477 unless ($MODEL) {
355 # try to load a model 478 # try to load a model
356 479
357 for (@REGISTRY, @models) { 480 for (@REGISTRY, @models) {
358 my ($package, $model) = @$_; 481 my ($package, $model) = @$_;
359 if (eval "require $package" 482 if (eval "require $package"
360 and ${"$package\::VERSION"} > 0 483 and ${"$package\::VERSION"} > 0
361 and eval "require $model") { 484 and eval "require $model") {
362 $MODEL = $model; 485 $MODEL = $model;
363 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 486 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
364 last; 487 last;
488 }
365 } 489 }
490
491 $MODEL
492 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";
366 } 493 }
367
368 $MODEL
369 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.";
370 } 494 }
371 495
372 unshift @ISA, $MODEL; 496 unshift @ISA, $MODEL;
373 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 497 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
374 } 498 }
… …
485 undef $CHLD_W unless keys %PID_CB; 609 undef $CHLD_W unless keys %PID_CB;
486} 610}
487 611
488=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 612=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
489 613
614This is an advanced topic that you do not normally need to use AnyEvent in
615a module. This section is only of use to event loop authors who want to
616provide AnyEvent compatibility.
617
490If you need to support another event library which isn't directly 618If you need to support another event library which isn't directly
491supported by AnyEvent, you can supply your own interface to it by 619supported by AnyEvent, you can supply your own interface to it by
492pushing, before the first watcher gets created, the package name of 620pushing, before the first watcher gets created, the package name of
493the event module and the package name of the interface to use onto 621the event module and the package name of the interface to use onto
494C<@AnyEvent::REGISTRY>. You can do that before and even without loading 622C<@AnyEvent::REGISTRY>. You can do that before and even without loading
495AnyEvent. 623AnyEvent, so it is reasonably cheap.
496 624
497Example: 625Example:
498 626
499 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 627 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
500 628
501This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 629This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
502package/class when it finds the C<urxvt> package/module is loaded. When 630package/class when it finds the C<urxvt> package/module is already loaded.
631
503AnyEvent is loaded and asked to find a suitable event model, it will 632When AnyEvent is loaded and asked to find a suitable event model, it
504first check for the presence of urxvt. 633will first check for the presence of urxvt by trying to C<use> the
634C<urxvt::anyevent> module.
505 635
506The class should provide implementations for all watcher types (see 636The class should provide implementations for all watcher types. See
507L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 637L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
508(Source code) and so on for actual examples, use C<perldoc -m 638and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
509AnyEvent::Impl::Glib> to see the sources). 639see the sources.
510 640
641If you don't provide C<signal> and C<child> watchers than AnyEvent will
642provide suitable (hopefully) replacements.
643
511The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) 644The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
512uses the above line as-is. An interface isn't included in AnyEvent 645terminal emulator uses the above line as-is. An interface isn't included
513because it doesn't make sense outside the embedded interpreter inside 646in AnyEvent because it doesn't make sense outside the embedded interpreter
514I<rxvt-unicode>, and it is updated and maintained as part of the 647inside I<rxvt-unicode>, and it is updated and maintained as part of the
515I<rxvt-unicode> distribution. 648I<rxvt-unicode> distribution.
516 649
517I<rxvt-unicode> also cheats a bit by not providing blocking access to 650I<rxvt-unicode> also cheats a bit by not providing blocking access to
518condition variables: code blocking while waiting for a condition will 651condition variables: code blocking while waiting for a condition will
519C<die>. This still works with most modules/usages, and blocking calls must 652C<die>. This still works with most modules/usages, and blocking calls must
520not be in an interactive application, so it makes sense. 653not be done in an interactive application, so it makes sense.
521 654
522=head1 ENVIRONMENT VARIABLES 655=head1 ENVIRONMENT VARIABLES
523 656
524The following environment variables are used by this module: 657The following environment variables are used by this module:
525 658
526C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 659=over 4
527model gets used.
528 660
661=item C<PERL_ANYEVENT_VERBOSE>
662
663When set to C<2> or higher, cause AnyEvent to report to STDERR which event
664model it chooses.
665
666=item C<PERL_ANYEVENT_MODEL>
667
668This can be used to specify the event model to be used by AnyEvent, before
669autodetection and -probing kicks in. It must be a string consisting
670entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
671and the resulting module name is loaded and if the load was successful,
672used as event model. If it fails to load AnyEvent will proceed with
673autodetection and -probing.
674
675This functionality might change in future versions.
676
677For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
678could start your program like this:
679
680 PERL_ANYEVENT_MODEL=Perl perl ...
681
682=back
683
529=head1 EXAMPLE 684=head1 EXAMPLE PROGRAM
530 685
531The following program uses an io watcher to read data from stdin, a timer 686The following program uses an IO watcher to read data from STDIN, a timer
532to display a message once per second, and a condvar to exit the program 687to display a message once per second, and a condition variable to quit the
533when the user enters quit: 688program when the user enters quit:
534 689
535 use AnyEvent; 690 use AnyEvent;
536 691
537 my $cv = AnyEvent->condvar; 692 my $cv = AnyEvent->condvar;
538 693
539 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 694 my $io_watcher = AnyEvent->io (
695 fh => \*STDIN,
696 poll => 'r',
697 cb => sub {
540 warn "io event <$_[0]>\n"; # will always output <r> 698 warn "io event <$_[0]>\n"; # will always output <r>
541 chomp (my $input = <STDIN>); # read a line 699 chomp (my $input = <STDIN>); # read a line
542 warn "read: $input\n"; # output what has been read 700 warn "read: $input\n"; # output what has been read
543 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 701 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
702 },
544 }); 703 );
545 704
546 my $time_watcher; # can only be used once 705 my $time_watcher; # can only be used once
547 706
548 sub new_timer { 707 sub new_timer {
549 $timer = AnyEvent->timer (after => 1, cb => sub { 708 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
631 $txn->{finished}->wait; 790 $txn->{finished}->wait;
632 return $txn->{result}; 791 return $txn->{result};
633 792
634The actual code goes further and collects all errors (C<die>s, exceptions) 793The actual code goes further and collects all errors (C<die>s, exceptions)
635that occured during request processing. The C<result> method detects 794that occured during request processing. The C<result> method detects
636wether an exception as thrown (it is stored inside the $txn object) 795whether an exception as thrown (it is stored inside the $txn object)
637and just throws the exception, which means connection errors and other 796and just throws the exception, which means connection errors and other
638problems get reported tot he code that tries to use the result, not in a 797problems get reported tot he code that tries to use the result, not in a
639random callback. 798random callback.
640 799
641All of this enables the following usage styles: 800All of this enables the following usage styles:
642 801
6431. Blocking: 8021. Blocking:
644 803
645 my $data = $fcp->client_get ($url); 804 my $data = $fcp->client_get ($url);
646 805
6472. Blocking, but parallelizing: 8062. Blocking, but running in parallel:
648 807
649 my @datas = map $_->result, 808 my @datas = map $_->result,
650 map $fcp->txn_client_get ($_), 809 map $fcp->txn_client_get ($_),
651 @urls; 810 @urls;
652 811
653Both blocking examples work without the module user having to know 812Both blocking examples work without the module user having to know
654anything about events. 813anything about events.
655 814
6563a. Event-based in a main program, using any support Event module: 8153a. Event-based in a main program, using any supported event module:
657 816
658 use Event; 817 use EV;
659 818
660 $fcp->txn_client_get ($url)->cb (sub { 819 $fcp->txn_client_get ($url)->cb (sub {
661 my $txn = shift; 820 my $txn = shift;
662 my $data = $txn->result; 821 my $data = $txn->result;
663 ... 822 ...
664 }); 823 });
665 824
666 Event::loop; 825 EV::loop;
667 826
6683b. The module user could use AnyEvent, too: 8273b. The module user could use AnyEvent, too:
669 828
670 use AnyEvent; 829 use AnyEvent;
671 830
… …
676 $quit->broadcast; 835 $quit->broadcast;
677 }); 836 });
678 837
679 $quit->wait; 838 $quit->wait;
680 839
840=head1 FORK
841
842Most event libraries are not fork-safe. The ones who are usually are
843because they are so inefficient. Only L<EV> is fully fork-aware.
844
845If you have to fork, you must either do so I<before> creating your first
846watcher OR you must not use AnyEvent at all in the child.
847
848=head1 SECURITY CONSIDERATIONS
849
850AnyEvent can be forced to load any event model via
851$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
852execute arbitrary code or directly gain access, it can easily be used to
853make the program hang or malfunction in subtle ways, as AnyEvent watchers
854will not be active when the program uses a different event model than
855specified in the variable.
856
857You can make AnyEvent completely ignore this variable by deleting it
858before the first watcher gets created, e.g. with a C<BEGIN> block:
859
860 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
861
862 use AnyEvent;
863
681=head1 SEE ALSO 864=head1 SEE ALSO
682 865
683Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. 866Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
867L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
868L<Event::Lib>, L<Qt>.
684 869
870Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
685Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. 871L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
872L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
873L<AnyEvent::Impl::Qt>.
686 874
687Nontrivial usage example: L<Net::FCP>. 875Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
688 876
689=head1 877=head1 AUTHOR
878
879 Marc Lehmann <schmorp@schmorp.de>
880 http://home.schmorp.de/
690 881
691=cut 882=cut
692 883
6931 8841
694 885

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