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Revision 1.52 by root, Sat Apr 19 03:47:24 2008 UTC vs.
Revision 1.56 by root, Thu Apr 24 03:10:03 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
5EV, Event, Coro::EV, Coro::Event, 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
… …
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 whether any of the following modules is 83to detect the currently loaded event loop by probing whether one of the
80loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, L<Event>, L<Glib>, L<Tk>. The 84following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
81first one found is used. If none are found, the module tries to load these 85L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found,
82modules in the order given. The first one that could be successfully 86the module tries to load these modules in the stated order. The first one
83loaded will be used. If still none could be found, AnyEvent will fall back 87that can be successfully loaded will be used. If, after this, still none
84to a pure-perl event loop, which is also not very efficient. 88could be found, AnyEvent will fall back to a pure-perl event loop, which
89is not very efficient, but should work everywhere.
85 90
86Because AnyEvent first checks for modules that are already loaded, loading 91Because AnyEvent first checks for modules that are already loaded, loading
87an Event model explicitly before first using AnyEvent will likely make 92an event model explicitly before first using AnyEvent will likely make
88that model the default. For example: 93that model the default. For example:
89 94
90 use Tk; 95 use Tk;
91 use AnyEvent; 96 use AnyEvent;
92 97
93 # .. AnyEvent will likely default to Tk 98 # .. AnyEvent will likely default to Tk
99
100The I<likely> means that, if any module loads another event model and
101starts using it, all bets are off. Maybe you should tell their authors to
102use AnyEvent so their modules work together with others seamlessly...
94 103
95The pure-perl implementation of AnyEvent is called 104The pure-perl implementation of AnyEvent is called
96C<AnyEvent::Impl::Perl>. Like other event modules you can load it 105C<AnyEvent::Impl::Perl>. Like other event modules you can load it
97explicitly. 106explicitly.
98 107
… …
101AnyEvent has the central concept of a I<watcher>, which is an object that 110AnyEvent 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 111stores relevant data for each kind of event you are waiting for, such as
103the callback to call, the filehandle to watch, etc. 112the callback to call, the filehandle to watch, etc.
104 113
105These watchers are normal Perl objects with normal Perl lifetime. After 114These watchers are normal Perl objects with normal Perl lifetime. After
106creating a watcher it will immediately "watch" for events and invoke 115creating a watcher it will immediately "watch" for events and invoke the
116callback when the event occurs (of course, only when the event model
117is in control).
118
107the callback. To disable the watcher you have to destroy it (e.g. by 119To 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 120variable you store it in to C<undef> or otherwise deleting all references
109references to it). 121to it).
110 122
111All watchers are created by calling a method on the C<AnyEvent> class. 123All watchers are created by calling a method on the C<AnyEvent> class.
112 124
125Many watchers either are used with "recursion" (repeating timers for
126example), or need to refer to their watcher object in other ways.
127
128An any way to achieve that is this pattern:
129
130 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
131 # you can use $w here, for example to undef it
132 undef $w;
133 });
134
135Note that C<my $w; $w => combination. This is necessary because in Perl,
136my variables are only visible after the statement in which they are
137declared.
138
113=head2 IO WATCHERS 139=head2 IO WATCHERS
114 140
115You can create I/O watcher by calling the C<< AnyEvent->io >> method with 141You can create an I/O watcher by calling the C<< AnyEvent->io >> method
116the following mandatory arguments: 142with the following mandatory key-value pairs as arguments:
117 143
118C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 144C<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 145events. 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 146creates a watcher waiting for "r"eadable or "w"ritable events,
121to invoke everytime the filehandle becomes ready. 147respectively. C<cb> is the callback to invoke each time the file handle
148becomes ready.
122 149
123Filehandles will be kept alive, so as long as the watcher exists, the 150As long as the I/O watcher exists it will keep the file descriptor or a
124filehandle exists, too. 151copy of it alive/open.
152
153It is not allowed to close a file handle as long as any watcher is active
154on the underlying file descriptor.
155
156Some event loops issue spurious readyness notifications, so you should
157always use non-blocking calls when reading/writing from/to your file
158handles.
125 159
126Example: 160Example:
127 161
128 # wait for readability of STDIN, then read a line and disable the watcher 162 # wait for readability of STDIN, then read a line and disable the watcher
129 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 163 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
135=head2 TIME WATCHERS 169=head2 TIME WATCHERS
136 170
137You can create a time watcher by calling the C<< AnyEvent->timer >> 171You can create a time watcher by calling the C<< AnyEvent->timer >>
138method with the following mandatory arguments: 172method with the following mandatory arguments:
139 173
140C<after> after how many seconds (fractions are supported) should the timer 174C<after> specifies after how many seconds (fractional values are
141activate. C<cb> the callback to invoke. 175supported) should the timer activate. C<cb> the callback to invoke in that
176case.
142 177
143The timer callback will be invoked at most once: if you want a repeating 178The timer callback will be invoked at most once: if you want a repeating
144timer you have to create a new watcher (this is a limitation by both Tk 179timer you have to create a new watcher (this is a limitation by both Tk
145and Glib). 180and Glib).
146 181
… …
152 }); 187 });
153 188
154 # to cancel the timer: 189 # to cancel the timer:
155 undef $w; 190 undef $w;
156 191
192Example 2:
193
194 # fire an event after 0.5 seconds, then roughly every second
195 my $w;
196
197 my $cb = sub {
198 # cancel the old timer while creating a new one
199 $w = AnyEvent->timer (after => 1, cb => $cb);
200 };
201
202 # start the "loop" by creating the first watcher
203 $w = AnyEvent->timer (after => 0.5, cb => $cb);
204
205=head3 TIMING ISSUES
206
207There are two ways to handle timers: based on real time (relative, "fire
208in 10 seconds") and based on wallclock time (absolute, "fire at 12
209o'clock").
210
211While most event loops expect timers to specified in a relative way, they use
212absolute time internally. This makes a difference when your clock "jumps",
213for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to
2142008-01-01, a watcher that you created to fire "after" a second might actually take
215six years to finally fire.
216
217AnyEvent cannot compensate for this. The only event loop that is conscious
218about these issues is L<EV>, which offers both relative (ev_timer) and
219absolute (ev_periodic) timers.
220
221AnyEvent always prefers relative timers, if available, matching the
222AnyEvent API.
223
224=head2 SIGNAL WATCHERS
225
226You can watch for signals using a signal watcher, C<signal> is the signal
227I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
228be invoked whenever a signal occurs.
229
230Multiple signals occurances can be clumped together into one callback
231invocation, and callback invocation will be synchronous. synchronous means
232that it might take a while until the signal gets handled by the process,
233but it is guarenteed not to interrupt any other callbacks.
234
235The main advantage of using these watchers is that you can share a signal
236between multiple watchers.
237
238This watcher might use C<%SIG>, so programs overwriting those signals
239directly will likely not work correctly.
240
241Example: exit on SIGINT
242
243 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
244
245=head2 CHILD PROCESS WATCHERS
246
247You can also watch on a child process exit and catch its exit status.
248
249The child process is specified by the C<pid> argument (if set to C<0>, it
250watches for any child process exit). The watcher will trigger as often
251as status change for the child are received. This works by installing a
252signal handler for C<SIGCHLD>. The callback will be called with the pid
253and exit status (as returned by waitpid).
254
255Example: wait for pid 1333
256
257 my $w = AnyEvent->child (
258 pid => 1333,
259 cb => sub {
260 my ($pid, $status) = @_;
261 warn "pid $pid exited with status $status";
262 },
263 );
264
157=head2 CONDITION WATCHERS 265=head2 CONDITION VARIABLES
158 266
159Condition watchers can be created by calling the C<< AnyEvent->condvar >> 267Condition variables can be created by calling the C<< AnyEvent->condvar >>
160method without any arguments. 268method without any arguments.
161 269
162A condition watcher watches for a condition - precisely that the C<< 270A condition variable waits for a condition - precisely that the C<<
163->broadcast >> method has been called. 271->broadcast >> method has been called.
164 272
273They are very useful to signal that a condition has been fulfilled, for
274example, if you write a module that does asynchronous http requests,
275then a condition variable would be the ideal candidate to signal the
276availability of results.
277
278You can also use condition variables to block your main program until
279an event occurs - for example, you could C<< ->wait >> in your main
280program until the user clicks the Quit button in your app, which would C<<
281->broadcast >> the "quit" event.
282
165Note that condition watchers recurse into the event loop - if you have 283Note that condition variables recurse into the event loop - if you have
166two watchers that call C<< ->wait >> in a round-robbin fashion, you 284two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
167lose. Therefore, condition watchers are good to export to your caller, but 285lose. Therefore, condition variables are good to export to your caller, but
168you should avoid making a blocking wait, at least in callbacks, as this 286you should avoid making a blocking wait yourself, at least in callbacks,
169usually asks for trouble. 287as this asks for trouble.
170 288
171The watcher has only two methods: 289This object has two methods:
172 290
173=over 4 291=over 4
174 292
175=item $cv->wait 293=item $cv->wait
176 294
… …
179 297
180You can only wait once on a condition - additional calls will return 298You can only wait once on a condition - additional calls will return
181immediately. 299immediately.
182 300
183Not all event models support a blocking wait - some die in that case 301Not all event models support a blocking wait - some die in that case
184(programs might want to do that so they stay interactive), so I<if you 302(programs might want to do that to stay interactive), so I<if you are
185are using this from a module, never require a blocking wait>, but let the 303using this from a module, never require a blocking wait>, but let the
186caller decide whether the call will block or not (for example, by coupling 304caller decide whether the call will block or not (for example, by coupling
187condition variables with some kind of request results and supporting 305condition variables with some kind of request results and supporting
188callbacks so the caller knows that getting the result will not block, 306callbacks so the caller knows that getting the result will not block,
189while still suppporting blocking waits if the caller so desires). 307while still suppporting blocking waits if the caller so desires).
190 308
191Another reason I<never> to C<< ->wait >> in a module is that you cannot 309Another reason I<never> to C<< ->wait >> in a module is that you cannot
192sensibly have two C<< ->wait >>'s in parallel, as that would require 310sensibly have two C<< ->wait >>'s in parallel, as that would require
193multiple interpreters or coroutines/threads, none of which C<AnyEvent> 311multiple interpreters or coroutines/threads, none of which C<AnyEvent>
194can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> 312can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
195explicitly support concurrent C<< ->wait >>'s from different coroutines, 313L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
196however). 314from different coroutines, however).
197 315
198=item $cv->broadcast 316=item $cv->broadcast
199 317
200Flag the condition as ready - a running C<< ->wait >> and all further 318Flag the condition as ready - a running C<< ->wait >> and all further
201calls to C<wait> will return after this method has been called. If nobody 319calls to C<wait> will (eventually) return after this method has been
202is waiting the broadcast will be remembered.. 320called. If nobody is waiting the broadcast will be remembered..
321
322=back
203 323
204Example: 324Example:
205 325
206 # wait till the result is ready 326 # wait till the result is ready
207 my $result_ready = AnyEvent->condvar; 327 my $result_ready = AnyEvent->condvar;
208 328
209 # do something such as adding a timer 329 # do something such as adding a timer
210 # or socket watcher the calls $result_ready->broadcast 330 # or socket watcher the calls $result_ready->broadcast
211 # when the "result" is ready. 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 );
212 337
338 # this "blocks" (while handling events) till the watcher
339 # calls broadcast
213 $result_ready->wait; 340 $result_ready->wait;
214 341
215=back 342=head1 GLOBAL VARIABLES AND FUNCTIONS
216
217=head2 SIGNAL WATCHERS
218
219You can listen for signals using a signal watcher, C<signal> is the signal
220I<name> without any C<SIG> prefix. Multiple signals events can be clumped
221together into one callback invocation, and callback invocation might or
222might not be asynchronous.
223
224These watchers might use C<%SIG>, so programs overwriting those signals
225directly will likely not work correctly.
226
227Example: exit on SIGINT
228
229 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
230
231=head2 CHILD PROCESS WATCHERS
232
233You can also listen for the status of a child process specified by the
234C<pid> argument (or any child if the pid argument is 0). The watcher will
235trigger as often as status change for the child are received. This works
236by installing a signal handler for C<SIGCHLD>. The callback will be called with
237the pid and exit status (as returned by waitpid).
238
239Example: wait for pid 1333
240
241 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
242
243=head1 GLOBALS
244 343
245=over 4 344=over 4
246 345
247=item $AnyEvent::MODEL 346=item $AnyEvent::MODEL
248 347
… …
254 353
255The known classes so far are: 354The known classes so far are:
256 355
257 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 356 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
258 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 357 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
259 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). 358 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
260 AnyEvent::Impl::Event based on Event, also second best choice :) 359 AnyEvent::Impl::Event based on Event, second best choice.
261 AnyEvent::Impl::Glib based on Glib, third-best choice. 360 AnyEvent::Impl::Glib based on Glib, third-best choice.
262 AnyEvent::Impl::Tk based on Tk, very bad choice. 361 AnyEvent::Impl::Tk based on Tk, very bad choice.
263 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. 362 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
363 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
364 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
264 365
265=item AnyEvent::detect 366=item AnyEvent::detect
266 367
267Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 368Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
268necessary. You should only call this function right before you would have 369if necessary. You should only call this function right before you would
269created an AnyEvent watcher anyway, that is, very late at runtime. 370have created an AnyEvent watcher anyway, that is, as late as possible at
371runtime.
270 372
271=back 373=back
272 374
273=head1 WHAT TO DO IN A MODULE 375=head1 WHAT TO DO IN A MODULE
274 376
275As a module author, you should "use AnyEvent" and call AnyEvent methods 377As a module author, you should C<use AnyEvent> and call AnyEvent methods
276freely, but you should not load a specific event module or rely on it. 378freely, but you should not load a specific event module or rely on it.
277 379
278Be careful when you create watchers in the module body - Anyevent will 380Be careful when you create watchers in the module body - AnyEvent will
279decide which event module to use as soon as the first method is called, so 381decide which event module to use as soon as the first method is called, so
280by calling AnyEvent in your module body you force the user of your module 382by calling AnyEvent in your module body you force the user of your module
281to load the event module first. 383to load the event module first.
282 384
385Never call C<< ->wait >> on a condition variable unless you I<know> that
386the C<< ->broadcast >> method has been called on it already. This is
387because it will stall the whole program, and the whole point of using
388events is to stay interactive.
389
390It is fine, however, to call C<< ->wait >> when the user of your module
391requests it (i.e. if you create a http request object ad have a method
392called C<results> that returns the results, it should call C<< ->wait >>
393freely, as the user of your module knows what she is doing. always).
394
283=head1 WHAT TO DO IN THE MAIN PROGRAM 395=head1 WHAT TO DO IN THE MAIN PROGRAM
284 396
285There will always be a single main program - the only place that should 397There will always be a single main program - the only place that should
286dictate which event model to use. 398dictate which event model to use.
287 399
288If it doesn't care, it can just "use AnyEvent" and use it itself, or not 400If it doesn't care, it can just "use AnyEvent" and use it itself, or not
289do anything special and let AnyEvent decide which implementation to chose. 401do anything special (it does not need to be event-based) and let AnyEvent
402decide which implementation to chose if some module relies on it.
290 403
291If the main program relies on a specific event model (for example, in Gtk2 404If the main program relies on a specific event model. For example, in
292programs you have to rely on either Glib or Glib::Event), you should load 405Gtk2 programs you have to rely on the Glib module. You should load the
293it before loading AnyEvent or any module that uses it, generally, as early 406event module before loading AnyEvent or any module that uses it: generally
294as possible. The reason is that modules might create watchers when they 407speaking, you should load it as early as possible. The reason is that
295are loaded, and AnyEvent will decide on the event model to use as soon as 408modules might create watchers when they are loaded, and AnyEvent will
296it creates watchers, and it might chose the wrong one unless you load the 409decide on the event model to use as soon as it creates watchers, and it
297correct one yourself. 410might chose the wrong one unless you load the correct one yourself.
298 411
299You can chose to use a rather inefficient pure-perl implementation by 412You can chose to use a rather inefficient pure-perl implementation by
300loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 413loading the C<AnyEvent::Impl::Perl> module, which gives you similar
301generally better. 414behaviour everywhere, but letting AnyEvent chose is generally better.
302 415
303=cut 416=cut
304 417
305package AnyEvent; 418package AnyEvent;
306 419
307no warnings; 420no warnings;
308use strict; 421use strict;
309 422
310use Carp; 423use Carp;
311 424
312our $VERSION = '3.1'; 425our $VERSION = '3.12';
313our $MODEL; 426our $MODEL;
314 427
315our $AUTOLOAD; 428our $AUTOLOAD;
316our @ISA; 429our @ISA;
317 430
… …
326 [Event:: => AnyEvent::Impl::Event::], 439 [Event:: => AnyEvent::Impl::Event::],
327 [Glib:: => AnyEvent::Impl::Glib::], 440 [Glib:: => AnyEvent::Impl::Glib::],
328 [Tk:: => AnyEvent::Impl::Tk::], 441 [Tk:: => AnyEvent::Impl::Tk::],
329 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 442 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
330); 443);
444my @models_detect = (
445 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
446 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
447);
331 448
332our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 449our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
333 450
334sub detect() { 451sub detect() {
335 unless ($MODEL) { 452 unless ($MODEL) {
336 no strict 'refs'; 453 no strict 'refs';
337 454
455 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
456 my $model = "AnyEvent::Impl::$1";
457 if (eval "require $model") {
458 $MODEL = $model;
459 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
460 }
461 }
462
338 # check for already loaded models 463 # check for already loaded models
464 unless ($MODEL) {
339 for (@REGISTRY, @models) { 465 for (@REGISTRY, @models, @models_detect) {
340 my ($package, $model) = @$_; 466 my ($package, $model) = @$_;
341 if (${"$package\::VERSION"} > 0) { 467 if (${"$package\::VERSION"} > 0) {
342 if (eval "require $model") { 468 if (eval "require $model") {
343 $MODEL = $model; 469 $MODEL = $model;
344 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 470 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
345 last; 471 last;
472 }
346 } 473 }
347 } 474 }
348 }
349 475
350 unless ($MODEL) { 476 unless ($MODEL) {
351 # try to load a model 477 # try to load a model
352 478
353 for (@REGISTRY, @models) { 479 for (@REGISTRY, @models) {
354 my ($package, $model) = @$_; 480 my ($package, $model) = @$_;
355 if (eval "require $package" 481 if (eval "require $package"
356 and ${"$package\::VERSION"} > 0 482 and ${"$package\::VERSION"} > 0
357 and eval "require $model") { 483 and eval "require $model") {
358 $MODEL = $model; 484 $MODEL = $model;
359 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 485 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
360 last; 486 last;
487 }
361 } 488 }
489
490 $MODEL
491 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.";
362 } 492 }
363
364 $MODEL
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.";
366 } 493 }
367 494
368 unshift @ISA, $MODEL; 495 unshift @ISA, $MODEL;
369 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 496 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
370 } 497 }
… …
481 undef $CHLD_W unless keys %PID_CB; 608 undef $CHLD_W unless keys %PID_CB;
482} 609}
483 610
484=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 611=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
485 612
613This is an advanced topic that you do not normally need to use AnyEvent in
614a module. This section is only of use to event loop authors who want to
615provide AnyEvent compatibility.
616
486If you need to support another event library which isn't directly 617If you need to support another event library which isn't directly
487supported by AnyEvent, you can supply your own interface to it by 618supported by AnyEvent, you can supply your own interface to it by
488pushing, before the first watcher gets created, the package name of 619pushing, before the first watcher gets created, the package name of
489the event module and the package name of the interface to use onto 620the event module and the package name of the interface to use onto
490C<@AnyEvent::REGISTRY>. You can do that before and even without loading 621C<@AnyEvent::REGISTRY>. You can do that before and even without loading
491AnyEvent. 622AnyEvent, so it is reasonably cheap.
492 623
493Example: 624Example:
494 625
495 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 626 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
496 627
497This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 628This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
498package/class when it finds the C<urxvt> package/module is loaded. When 629package/class when it finds the C<urxvt> package/module is already loaded.
630
499AnyEvent is loaded and asked to find a suitable event model, it will 631When AnyEvent is loaded and asked to find a suitable event model, it
500first check for the presence of urxvt. 632will first check for the presence of urxvt by trying to C<use> the
633C<urxvt::anyevent> module.
501 634
502The class should provide implementations for all watcher types (see 635The class should provide implementations for all watcher types. See
503L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 636L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
504(Source code) and so on for actual examples, use C<perldoc -m 637and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
505AnyEvent::Impl::Glib> to see the sources). 638see the sources.
506 639
640If you don't provide C<signal> and C<child> watchers than AnyEvent will
641provide suitable (hopefully) replacements.
642
507The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) 643The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
508uses the above line as-is. An interface isn't included in AnyEvent 644terminal emulator uses the above line as-is. An interface isn't included
509because it doesn't make sense outside the embedded interpreter inside 645in AnyEvent because it doesn't make sense outside the embedded interpreter
510I<rxvt-unicode>, and it is updated and maintained as part of the 646inside I<rxvt-unicode>, and it is updated and maintained as part of the
511I<rxvt-unicode> distribution. 647I<rxvt-unicode> distribution.
512 648
513I<rxvt-unicode> also cheats a bit by not providing blocking access to 649I<rxvt-unicode> also cheats a bit by not providing blocking access to
514condition variables: code blocking while waiting for a condition will 650condition variables: code blocking while waiting for a condition will
515C<die>. This still works with most modules/usages, and blocking calls must 651C<die>. This still works with most modules/usages, and blocking calls must
516not be in an interactive application, so it makes sense. 652not be done in an interactive application, so it makes sense.
517 653
518=head1 ENVIRONMENT VARIABLES 654=head1 ENVIRONMENT VARIABLES
519 655
520The following environment variables are used by this module: 656The following environment variables are used by this module:
521 657
522C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 658=over 4
523model gets used.
524 659
660=item C<PERL_ANYEVENT_VERBOSE>
661
662When set to C<2> or higher, cause AnyEvent to report to STDERR which event
663model it chooses.
664
665=item C<PERL_ANYEVENT_MODEL>
666
667This can be used to specify the event model to be used by AnyEvent, before
668autodetection and -probing kicks in. It must be a string consisting
669entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
670and the resulting module name is loaded and if the load was successful,
671used as event model. If it fails to load AnyEvent will proceed with
672autodetection and -probing.
673
674This functionality might change in future versions.
675
676For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
677could start your program like this:
678
679 PERL_ANYEVENT_MODEL=Perl perl ...
680
681=back
682
525=head1 EXAMPLE 683=head1 EXAMPLE PROGRAM
526 684
527The following program uses an io watcher to read data from stdin, a timer 685The following program uses an IO watcher to read data from STDIN, a timer
528to display a message once per second, and a condvar to exit the program 686to display a message once per second, and a condition variable to quit the
529when the user enters quit: 687program when the user enters quit:
530 688
531 use AnyEvent; 689 use AnyEvent;
532 690
533 my $cv = AnyEvent->condvar; 691 my $cv = AnyEvent->condvar;
534 692
535 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 693 my $io_watcher = AnyEvent->io (
694 fh => \*STDIN,
695 poll => 'r',
696 cb => sub {
536 warn "io event <$_[0]>\n"; # will always output <r> 697 warn "io event <$_[0]>\n"; # will always output <r>
537 chomp (my $input = <STDIN>); # read a line 698 chomp (my $input = <STDIN>); # read a line
538 warn "read: $input\n"; # output what has been read 699 warn "read: $input\n"; # output what has been read
539 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 700 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
701 },
540 }); 702 );
541 703
542 my $time_watcher; # can only be used once 704 my $time_watcher; # can only be used once
543 705
544 sub new_timer { 706 sub new_timer {
545 $timer = AnyEvent->timer (after => 1, cb => sub { 707 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
672 $quit->broadcast; 834 $quit->broadcast;
673 }); 835 });
674 836
675 $quit->wait; 837 $quit->wait;
676 838
839=head1 FORK
840
841Most event libraries are not fork-safe. The ones who are usually are
842because they are so inefficient. Only L<EV> is fully fork-aware.
843
844If you have to fork, you must either do so I<before> creating your first
845watcher OR you must not use AnyEvent at all in the child.
846
847=head1 SECURITY CONSIDERATIONS
848
849AnyEvent can be forced to load any event model via
850$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
851execute arbitrary code or directly gain access, it can easily be used to
852make the program hang or malfunction in subtle ways, as AnyEvent watchers
853will not be active when the program uses a different event model than
854specified in the variable.
855
856You can make AnyEvent completely ignore this variable by deleting it
857before the first watcher gets created, e.g. with a C<BEGIN> block:
858
859 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
860
861 use AnyEvent;
862
677=head1 SEE ALSO 863=head1 SEE ALSO
678 864
679Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 865Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
680L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. 866L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
867L<Event::Lib>, L<Qt>.
681 868
682Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 869Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
683L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, 870L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
684L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. 871L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
872L<AnyEvent::Impl::Qt>.
685 873
686Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 874Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
687 875
688=head1 876=head1 AUTHOR
877
878 Marc Lehmann <schmorp@schmorp.de>
879 http://home.schmorp.de/
689 880
690=cut 881=cut
691 882
6921 8831
693 884

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