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Revision 1.32 by root, Sat Nov 3 09:29:51 2007 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
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
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent?
27
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>.
30
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
33pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality: In general,
35only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops.
37
38The goal of AnyEvent is to offer module authors the ability to do event
39programming (waiting for I/O or timer events) without subscribing to a
40religion, a way of living, and most importantly: without forcing your
41module users into the same thing by forcing them to use the same event
42model you use.
43
44For modules like POE or IO::Async (which is a total misnomer as it is
45actually doing all I/O I<synchronously>...), using them in your module is
46like joining a cult: After you joined, you are dependent on them and you
47cannot use anything else, as it is simply incompatible to everything that
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.
50
51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
54your module uses one of those, every user of your module has to use it,
55too. But if your module uses AnyEvent, it works transparently with all
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).
59
60In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enourmous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as
65technically possible.
66
67Of course, if you want lots of policy (this can arguably be somewhat
68useful) and you want to force your users to use the one and only event
69model, you should I<not> use this module.
70
22 71
23=head1 DESCRIPTION 72=head1 DESCRIPTION
24 73
25L<AnyEvent> provides an identical interface to multiple event loops. This 74L<AnyEvent> provides an identical interface to multiple event loops. This
26allows module authors to utilise an event loop without forcing module 75allows module authors to utilise an event loop without forcing module
27users 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
28peacefully at any one time). 77peacefully at any one time).
29 78
30The interface itself is vaguely similar but not identical to the Event 79The interface itself is vaguely similar, but not identical to the L<Event>
31module. 80module.
32 81
33On 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
34loaded event loop by probing wether any of the following modules is 83to detect the currently loaded event loop by probing whether one of the
35loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is 84following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
36used. If none is found, the module tries to load these modules in the 85L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found,
37order given. The first one that could be successfully loaded will be 86the module tries to load these modules in the stated order. The first one
38used. If still none could be found, AnyEvent will fall back to a pure-perl 87that can be successfully loaded will be used. If, after this, still none
39event 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.
40 90
41Because AnyEvent first checks for modules that are already loaded, loading 91Because AnyEvent first checks for modules that are already loaded, loading
42an Event model explicitly before first using AnyEvent will likely make 92an event model explicitly before first using AnyEvent will likely make
43that model the default. For example: 93that model the default. For example:
44 94
45 use Tk; 95 use Tk;
46 use AnyEvent; 96 use AnyEvent;
47 97
48 # .. 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...
49 103
50The pure-perl implementation of AnyEvent is called 104The pure-perl implementation of AnyEvent is called
51C<AnyEvent::Impl::Perl>. Like other event modules you can load it 105C<AnyEvent::Impl::Perl>. Like other event modules you can load it
52explicitly. 106explicitly.
53 107
… …
56AnyEvent 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
57stores 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
58the callback to call, the filehandle to watch, etc. 112the callback to call, the filehandle to watch, etc.
59 113
60These watchers are normal Perl objects with normal Perl lifetime. After 114These watchers are normal Perl objects with normal Perl lifetime. After
61creating 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
62the 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
63setting 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
64references to it). 121to it).
65 122
66All 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.
67 124
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
68=head2 IO WATCHERS 139=head2 IO WATCHERS
69 140
70You 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
71the following mandatory arguments: 142with the following mandatory key-value pairs as arguments:
72 143
73C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 144C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
74events. 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
75a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback 146creates a watcher waiting for "r"eadable or "w"ritable events,
76to invoke everytime the filehandle becomes ready. 147respectively. C<cb> is the callback to invoke each time the file handle
148becomes ready.
77 149
78Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on 150As long as the I/O watcher exists it will keep the file descriptor or a
79a socket you can have one r + one w, not any more (limitation comes from 151copy of it alive/open.
80Tk - if you are sure you are not using Tk this limitation is gone).
81 152
82Filehandles will be kept alive, so as long as the watcher exists, the 153It is not allowed to close a file handle as long as any watcher is active
83filehandle exists, too. 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.
84 159
85Example: 160Example:
86 161
87 # 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
88 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 163 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
94=head2 TIME WATCHERS 169=head2 TIME WATCHERS
95 170
96You can create a time watcher by calling the C<< AnyEvent->timer >> 171You can create a time watcher by calling the C<< AnyEvent->timer >>
97method with the following mandatory arguments: 172method with the following mandatory arguments:
98 173
99C<after> after how many seconds (fractions are supported) should the timer 174C<after> specifies after how many seconds (fractional values are
100activate. C<cb> the callback to invoke. 175supported) should the timer activate. C<cb> the callback to invoke in that
176case.
101 177
102The 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
103timer 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
104and Glib). 180and Glib).
105 181
… …
109 my $w = AnyEvent->timer (after => 7.7, cb => sub { 185 my $w = AnyEvent->timer (after => 7.7, cb => sub {
110 warn "timeout\n"; 186 warn "timeout\n";
111 }); 187 });
112 188
113 # to cancel the timer: 189 # to cancel the timer:
114 undef $w 190 undef $w;
115 191
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
116=head2 CONDITION WATCHERS 265=head2 CONDITION VARIABLES
117 266
118Condition watchers can be created by calling the C<< AnyEvent->condvar >> 267Condition variables can be created by calling the C<< AnyEvent->condvar >>
119method without any arguments. 268method without any arguments.
120 269
121A condition watcher watches for a condition - precisely that the C<< 270A condition variable waits for a condition - precisely that the C<<
122->broadcast >> method has been called. 271->broadcast >> method has been called.
123 272
124The watcher has only two methods: 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
283Note that condition variables recurse into the event loop - if you have
284two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
285lose. Therefore, condition variables are good to export to your caller, but
286you should avoid making a blocking wait yourself, at least in callbacks,
287as this asks for trouble.
288
289This object has two methods:
125 290
126=over 4 291=over 4
127 292
128=item $cv->wait 293=item $cv->wait
129 294
130Wait (blocking if necessary) until the C<< ->broadcast >> method has been 295Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131called on c<$cv>, while servicing other watchers normally. 296called on c<$cv>, while servicing other watchers normally.
132 297
133Not all event models support a blocking wait - some die in that case, so
134if you are using this from a module, never require a blocking wait, but
135let the caller decide wether the call will block or not (for example,
136by coupling condition variables with some kind of request results and
137supporting callbacks so the caller knows that getting the result will not
138block, while still suppporting blockign waits if the caller so desires).
139
140You can only wait once on a condition - additional calls will return 298You can only wait once on a condition - additional calls will return
141immediately. 299immediately.
142 300
301Not all event models support a blocking wait - some die in that case
302(programs might want to do that to stay interactive), so I<if you are
303using this from a module, never require a blocking wait>, but let the
304caller decide whether the call will block or not (for example, by coupling
305condition variables with some kind of request results and supporting
306callbacks so the caller knows that getting the result will not block,
307while still suppporting blocking waits if the caller so desires).
308
309Another reason I<never> to C<< ->wait >> in a module is that you cannot
310sensibly have two C<< ->wait >>'s in parallel, as that would require
311multiple interpreters or coroutines/threads, none of which C<AnyEvent>
312can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
313L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
314from different coroutines, however).
315
143=item $cv->broadcast 316=item $cv->broadcast
144 317
145Flag the condition as ready - a running C<< ->wait >> and all further 318Flag the condition as ready - a running C<< ->wait >> and all further
146calls 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
147is waiting the broadcast will be remembered.. 320called. If nobody is waiting the broadcast will be remembered..
321
322=back
148 323
149Example: 324Example:
150 325
151 # wait till the result is ready 326 # wait till the result is ready
152 my $result_ready = AnyEvent->condvar; 327 my $result_ready = AnyEvent->condvar;
153 328
154 # do something such as adding a timer 329 # do something such as adding a timer
155 # or socket watcher the calls $result_ready->broadcast 330 # or socket watcher the calls $result_ready->broadcast
156 # 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 );
157 337
338 # this "blocks" (while handling events) till the watcher
339 # calls broadcast
158 $result_ready->wait; 340 $result_ready->wait;
159 341
160=back 342=head1 GLOBAL VARIABLES AND FUNCTIONS
161
162=head2 SIGNAL WATCHERS
163
164You can listen for signals using a signal watcher, C<signal> is the signal
165I<name> without any C<SIG> prefix. Multiple signals events can be clumped
166together into one callback invocation, and callback invocation might or
167might not be asynchronous.
168
169These watchers might use C<%SIG>, so programs overwriting those signals
170directly will likely not work correctly.
171
172Example: exit on SIGINT
173
174 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
175
176=head2 CHILD PROCESS WATCHERS
177
178You can also listen for the status of a child process specified by the
179C<pid> argument (or any child if the pid argument is 0). The watcher will
180trigger as often as status change for the child are received. This works
181by installing a signal handler for C<SIGCHLD>. The callback will be called with
182the pid and exit status (as returned by waitpid).
183
184Example: wait for pid 1333
185
186 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
187
188=head1 GLOBALS
189 343
190=over 4 344=over 4
191 345
192=item $AnyEvent::MODEL 346=item $AnyEvent::MODEL
193 347
… …
197C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 351C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
198AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 352AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
199 353
200The known classes so far are: 354The known classes so far are:
201 355
202 EV::AnyEvent based on EV (an interface to libev, best choice) 356 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
203 AnyEvent::Impl::Coro based on Coro::Event, second best choice. 357 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
358 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
204 AnyEvent::Impl::Event based on Event, also second best choice :) 359 AnyEvent::Impl::Event based on Event, second best choice.
205 AnyEvent::Impl::Glib based on Glib, second-best choice. 360 AnyEvent::Impl::Glib based on Glib, third-best choice.
206 AnyEvent::Impl::Tk based on Tk, very bad choice. 361 AnyEvent::Impl::Tk based on Tk, very bad choice.
207 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 362 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
363 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
364 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
208 365
209=item AnyEvent::detect 366=item AnyEvent::detect
210 367
211Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 368Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
212necessary. You should only call this function right before you would have 369if necessary. You should only call this function right before you would
213created an AnyEvent watcher anyway, that is, very late at runtime. 370have created an AnyEvent watcher anyway, that is, as late as possible at
371runtime.
214 372
215=back 373=back
216 374
217=head1 WHAT TO DO IN A MODULE 375=head1 WHAT TO DO IN A MODULE
218 376
219As a module author, you should "use AnyEvent" and call AnyEvent methods 377As a module author, you should C<use AnyEvent> and call AnyEvent methods
220freely, 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.
221 379
222Be careful when you create watchers in the module body - Anyevent will 380Be careful when you create watchers in the module body - AnyEvent will
223decide 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
224by 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
225to load the event module first. 383to load the event module first.
226 384
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
227=head1 WHAT TO DO IN THE MAIN PROGRAM 395=head1 WHAT TO DO IN THE MAIN PROGRAM
228 396
229There 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
230dictate which event model to use. 398dictate which event model to use.
231 399
232If 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
233do 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.
234 403
235If 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
236programs 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
237it before loading AnyEvent or any module that uses it, generally, as early 406event module before loading AnyEvent or any module that uses it: generally
238as possible. The reason is that modules might create watchers when they 407speaking, you should load it as early as possible. The reason is that
239are 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
240it 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
241correct one yourself. 410might chose the wrong one unless you load the correct one yourself.
242 411
243You can chose to use a rather inefficient pure-perl implementation by 412You can chose to use a rather inefficient pure-perl implementation by
244loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 413loading the C<AnyEvent::Impl::Perl> module, which gives you similar
245generally better. 414behaviour everywhere, but letting AnyEvent chose is generally better.
246 415
247=cut 416=cut
248 417
249package AnyEvent; 418package AnyEvent;
250 419
251no warnings; 420no warnings;
252use strict; 421use strict;
253 422
254use Carp; 423use Carp;
255 424
256our $VERSION = '2.55'; 425our $VERSION = '3.12';
257our $MODEL; 426our $MODEL;
258 427
259our $AUTOLOAD; 428our $AUTOLOAD;
260our @ISA; 429our @ISA;
261 430
262our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 431our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
263 432
264our @REGISTRY; 433our @REGISTRY;
265 434
266my @models = ( 435my @models = (
436 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
267 [Coro::Event:: => AnyEvent::Impl::Coro::], 437 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
268 [EV:: => EV::AnyEvent::], 438 [EV:: => AnyEvent::Impl::EV::],
269 [Event:: => AnyEvent::Impl::Event::], 439 [Event:: => AnyEvent::Impl::Event::],
270 [Glib:: => AnyEvent::Impl::Glib::], 440 [Glib:: => AnyEvent::Impl::Glib::],
271 [Tk:: => AnyEvent::Impl::Tk::], 441 [Tk:: => AnyEvent::Impl::Tk::],
272 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 442 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
273); 443);
444my @models_detect = (
445 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
446 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
447);
274 448
275our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 449our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
276 450
277sub detect() { 451sub detect() {
278 unless ($MODEL) { 452 unless ($MODEL) {
279 no strict 'refs'; 453 no strict 'refs';
280 454
455 if ($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 $verbose > 1;
460 }
461 }
462
281 # check for already loaded models 463 # check for already loaded models
464 unless ($MODEL) {
282 for (@REGISTRY, @models) { 465 for (@REGISTRY, @models, @models_detect) {
283 my ($package, $model) = @$_; 466 my ($package, $model) = @$_;
284 if (${"$package\::VERSION"} > 0) { 467 if (${"$package\::VERSION"} > 0) {
285 if (eval "require $model") { 468 if (eval "require $model") {
286 $MODEL = $model; 469 $MODEL = $model;
287 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 470 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
288 last; 471 last;
472 }
289 } 473 }
290 } 474 }
291 }
292 475
293 unless ($MODEL) { 476 unless ($MODEL) {
294 # try to load a model 477 # try to load a model
295 478
296 for (@REGISTRY, @models) { 479 for (@REGISTRY, @models) {
297 my ($package, $model) = @$_; 480 my ($package, $model) = @$_;
298 if (eval "require $package" 481 if (eval "require $package"
299 and ${"$package\::VERSION"} > 0 482 and ${"$package\::VERSION"} > 0
300 and eval "require $model") { 483 and eval "require $model") {
301 $MODEL = $model; 484 $MODEL = $model;
302 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 485 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
303 last; 486 last;
487 }
304 } 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.";
305 } 492 }
306
307 $MODEL
308 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk.";
309 } 493 }
310 494
311 unshift @ISA, $MODEL; 495 unshift @ISA, $MODEL;
312 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 496 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
313 } 497 }
… …
371 555
372# default implementation for ->child 556# default implementation for ->child
373 557
374our %PID_CB; 558our %PID_CB;
375our $CHLD_W; 559our $CHLD_W;
560our $CHLD_DELAY_W;
376our $PID_IDLE; 561our $PID_IDLE;
377our $WNOHANG; 562our $WNOHANG;
378 563
379sub _child_wait { 564sub _child_wait {
380 while (0 <= (my $pid = waitpid -1, $WNOHANG)) { 565 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
381 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 566 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
382 (values %{ $PID_CB{0} || {} }); 567 (values %{ $PID_CB{0} || {} });
383 } 568 }
384 569
385 undef $PID_IDLE; 570 undef $PID_IDLE;
386} 571}
387 572
573sub _sigchld {
574 # make sure we deliver these changes "synchronous" with the event loop.
575 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
576 undef $CHLD_DELAY_W;
577 &_child_wait;
578 });
579}
580
388sub child { 581sub child {
389 my (undef, %arg) = @_; 582 my (undef, %arg) = @_;
390 583
391 defined (my $pid = $arg{pid} + 0) 584 defined (my $pid = $arg{pid} + 0)
392 or Carp::croak "required option 'pid' is missing"; 585 or Carp::croak "required option 'pid' is missing";
… …
396 unless ($WNOHANG) { 589 unless ($WNOHANG) {
397 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 590 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
398 } 591 }
399 592
400 unless ($CHLD_W) { 593 unless ($CHLD_W) {
401 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); 594 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
402 # child could be a zombie already 595 # child could be a zombie already, so make at least one round
403 $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); 596 &_sigchld;
404 } 597 }
405 598
406 bless [$pid, $arg{cb}], "AnyEvent::Base::Child" 599 bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
407} 600}
408 601
… …
414 607
415 undef $CHLD_W unless keys %PID_CB; 608 undef $CHLD_W unless keys %PID_CB;
416} 609}
417 610
418=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 611=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
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.
419 616
420If you need to support another event library which isn't directly 617If you need to support another event library which isn't directly
421supported by AnyEvent, you can supply your own interface to it by 618supported by AnyEvent, you can supply your own interface to it by
422pushing, before the first watcher gets created, the package name of 619pushing, before the first watcher gets created, the package name of
423the 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
424C<@AnyEvent::REGISTRY>. You can do that before and even without loading 621C<@AnyEvent::REGISTRY>. You can do that before and even without loading
425AnyEvent. 622AnyEvent, so it is reasonably cheap.
426 623
427Example: 624Example:
428 625
429 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 626 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
430 627
431This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 628This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
432package/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
433AnyEvent 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
434first check for the presence of urxvt. 632will first check for the presence of urxvt by trying to C<use> the
633C<urxvt::anyevent> module.
435 634
436The class should provide implementations for all watcher types (see 635The class should provide implementations for all watcher types. See
437L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 636L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
438(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
439AnyEvent::Impl::Glib> to see the sources). 638see the sources.
440 639
640If you don't provide C<signal> and C<child> watchers than AnyEvent will
641provide suitable (hopefully) replacements.
642
441The 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)
442uses 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
443because it doesn't make sense outside the embedded interpreter inside 645in AnyEvent because it doesn't make sense outside the embedded interpreter
444I<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
445I<rxvt-unicode> distribution. 647I<rxvt-unicode> distribution.
446 648
447I<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
448condition variables: code blocking while waiting for a condition will 650condition variables: code blocking while waiting for a condition will
449C<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
450not be in an interactive application, so it makes sense. 652not be done in an interactive application, so it makes sense.
451 653
452=head1 ENVIRONMENT VARIABLES 654=head1 ENVIRONMENT VARIABLES
453 655
454The following environment variables are used by this module: 656The following environment variables are used by this module:
455 657
456C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 658=over 4
457model gets used.
458 659
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
459=head1 EXAMPLE 683=head1 EXAMPLE PROGRAM
460 684
461The 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
462to 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
463when the user enters quit: 687program when the user enters quit:
464 688
465 use AnyEvent; 689 use AnyEvent;
466 690
467 my $cv = AnyEvent->condvar; 691 my $cv = AnyEvent->condvar;
468 692
469 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 693 my $io_watcher = AnyEvent->io (
694 fh => \*STDIN,
695 poll => 'r',
696 cb => sub {
470 warn "io event <$_[0]>\n"; # will always output <r> 697 warn "io event <$_[0]>\n"; # will always output <r>
471 chomp (my $input = <STDIN>); # read a line 698 chomp (my $input = <STDIN>); # read a line
472 warn "read: $input\n"; # output what has been read 699 warn "read: $input\n"; # output what has been read
473 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 700 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
701 },
474 }); 702 );
475 703
476 my $time_watcher; # can only be used once 704 my $time_watcher; # can only be used once
477 705
478 sub new_timer { 706 sub new_timer {
479 $timer = AnyEvent->timer (after => 1, cb => sub { 707 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
561 $txn->{finished}->wait; 789 $txn->{finished}->wait;
562 return $txn->{result}; 790 return $txn->{result};
563 791
564The actual code goes further and collects all errors (C<die>s, exceptions) 792The actual code goes further and collects all errors (C<die>s, exceptions)
565that occured during request processing. The C<result> method detects 793that occured during request processing. The C<result> method detects
566wether an exception as thrown (it is stored inside the $txn object) 794whether an exception as thrown (it is stored inside the $txn object)
567and just throws the exception, which means connection errors and other 795and just throws the exception, which means connection errors and other
568problems get reported tot he code that tries to use the result, not in a 796problems get reported tot he code that tries to use the result, not in a
569random callback. 797random callback.
570 798
571All of this enables the following usage styles: 799All of this enables the following usage styles:
572 800
5731. Blocking: 8011. Blocking:
574 802
575 my $data = $fcp->client_get ($url); 803 my $data = $fcp->client_get ($url);
576 804
5772. Blocking, but parallelizing: 8052. Blocking, but running in parallel:
578 806
579 my @datas = map $_->result, 807 my @datas = map $_->result,
580 map $fcp->txn_client_get ($_), 808 map $fcp->txn_client_get ($_),
581 @urls; 809 @urls;
582 810
583Both blocking examples work without the module user having to know 811Both blocking examples work without the module user having to know
584anything about events. 812anything about events.
585 813
5863a. Event-based in a main program, using any support Event module: 8143a. Event-based in a main program, using any supported event module:
587 815
588 use Event; 816 use EV;
589 817
590 $fcp->txn_client_get ($url)->cb (sub { 818 $fcp->txn_client_get ($url)->cb (sub {
591 my $txn = shift; 819 my $txn = shift;
592 my $data = $txn->result; 820 my $data = $txn->result;
593 ... 821 ...
594 }); 822 });
595 823
596 Event::loop; 824 EV::loop;
597 825
5983b. The module user could use AnyEvent, too: 8263b. The module user could use AnyEvent, too:
599 827
600 use AnyEvent; 828 use AnyEvent;
601 829
… …
606 $quit->broadcast; 834 $quit->broadcast;
607 }); 835 });
608 836
609 $quit->wait; 837 $quit->wait;
610 838
839=head1 FORK
840
841Most event libraries are not fork-safe. The ones who are usually are
842because they are so inefficient. Only L<EV> is fully fork-aware.
843
844If you have to fork, you must either do so I<before> creating your first
845watcher OR you must not use AnyEvent at all in the child.
846
847=head1 SECURITY CONSIDERATIONS
848
849AnyEvent can be forced to load any event model via
850$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
611=head1 SEE ALSO 863=head1 SEE ALSO
612 864
613Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. 865Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
866L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
867L<Event::Lib>, L<Qt>.
614 868
869Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
615Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>. 870L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
871L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
872L<AnyEvent::Impl::Qt>.
616 873
617Nontrivial usage example: L<Net::FCP>. 874Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
618 875
619=head1 876=head1 AUTHOR
877
878 Marc Lehmann <schmorp@schmorp.de>
879 http://home.schmorp.de/
620 880
621=cut 881=cut
622 882
6231 8831
624 884

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