ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/AnyEvent/lib/AnyEvent.pm
(Generate patch)

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.42 by root, Mon Apr 7 19:40:12 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 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 26nowadays. So what is different about AnyEvent?
27 27
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
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.
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.
62 70
63 71
64=head1 DESCRIPTION 72=head1 DESCRIPTION
65 73
66L<AnyEvent> provides an identical interface to multiple event loops. This 74L<AnyEvent> provides an identical interface to multiple event loops. This
67allows module authors to utilise an event loop without forcing module 75allows module authors to utilise an event loop without forcing module
68users 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
69peacefully at any one time). 77peacefully at any one time).
70 78
71The interface itself is vaguely similar but not identical to the Event 79The interface itself is vaguely similar, but not identical to the L<Event>
72module. 80module.
73 81
74On 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
75loaded event loop by probing wether any of the following modules is 83to detect the currently loaded event loop by probing whether one of
76loaded: 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
77used. 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
78order 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
79used. 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
80event 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.
81 91
82Because AnyEvent first checks for modules that are already loaded, loading 92Because AnyEvent first checks for modules that are already loaded, loading
83an Event model explicitly before first using AnyEvent will likely make 93an event model explicitly before first using AnyEvent will likely make
84that model the default. For example: 94that model the default. For example:
85 95
86 use Tk; 96 use Tk;
87 use AnyEvent; 97 use AnyEvent;
88 98
89 # .. 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...
90 104
91The pure-perl implementation of AnyEvent is called 105The pure-perl implementation of AnyEvent is called
92C<AnyEvent::Impl::Perl>. Like other event modules you can load it 106C<AnyEvent::Impl::Perl>. Like other event modules you can load it
93explicitly. 107explicitly.
94 108
… …
97AnyEvent 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
98stores 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
99the callback to call, the filehandle to watch, etc. 113the callback to call, the filehandle to watch, etc.
100 114
101These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
102creating 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
103the 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
104setting 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
105references to it). 122to it).
106 123
107All 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.
108 125
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
109=head2 IO WATCHERS 140=head2 IO WATCHERS
110 141
111You 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
112the following mandatory arguments: 143with the following mandatory key-value pairs as arguments:
113 144
114C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
115events. 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
116a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback 147creates a watcher waiting for "r"eadable or "w"ritable events,
117to invoke everytime the filehandle becomes ready. 148respectively. C<cb> is the callback to invoke each time the file handle
149becomes ready.
118 150
119Only 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
120a socket you can have one r + one w, not any more (limitation comes from 152copy of it alive/open.
121Tk - if you are sure you are not using Tk this limitation is gone).
122 153
123Filehandles 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
124filehandle 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.
125 160
126Example: 161Example:
127 162
128 # 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
129 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 164 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
135=head2 TIME WATCHERS 170=head2 TIME WATCHERS
136 171
137You can create a time watcher by calling the C<< AnyEvent->timer >> 172You can create a time watcher by calling the C<< AnyEvent->timer >>
138method with the following mandatory arguments: 173method with the following mandatory arguments:
139 174
140C<after> after how many seconds (fractions are supported) should the timer 175C<after> specifies after how many seconds (fractional values are
141activate. C<cb> the callback to invoke. 176supported) should the timer activate. C<cb> the callback to invoke in that
177case.
142 178
143The 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
144timer 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
145and Glib). 181and Glib).
146 182
… …
152 }); 188 });
153 189
154 # to cancel the timer: 190 # to cancel the timer:
155 undef $w; 191 undef $w;
156 192
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
157=head2 CONDITION WATCHERS 266=head2 CONDITION VARIABLES
158 267
159Condition watchers can be created by calling the C<< AnyEvent->condvar >> 268Condition variables can be created by calling the C<< AnyEvent->condvar >>
160method without any arguments. 269method without any arguments.
161 270
162A condition watcher watches for a condition - precisely that the C<< 271A condition variable waits for a condition - precisely that the C<<
163->broadcast >> method has been called. 272->broadcast >> method has been called.
164 273
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
165Note that condition watchers recurse into the event loop - if you have 284Note that condition variables recurse into the event loop - if you have
166two 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
167lose. Therefore, condition watchers are good to export to your caller, but 286lose. Therefore, condition variables are good to export to your caller, but
168you should avoid making a blocking wait, at least in callbacks, as this 287you should avoid making a blocking wait yourself, at least in callbacks,
169usually asks for trouble. 288as this asks for trouble.
170 289
171The watcher has only two methods: 290This object has two methods:
172 291
173=over 4 292=over 4
174 293
175=item $cv->wait 294=item $cv->wait
176 295
177Wait (blocking if necessary) until the C<< ->broadcast >> method has been 296Wait (blocking if necessary) until the C<< ->broadcast >> method has been
178called on c<$cv>, while servicing other watchers normally. 297called on c<$cv>, while servicing other watchers normally.
179 298
180Not all event models support a blocking wait - some die in that case, so
181if you are using this from a module, never require a blocking wait, but
182let the caller decide wether the call will block or not (for example,
183by coupling condition variables with some kind of request results and
184supporting callbacks so the caller knows that getting the result will not
185block, while still suppporting blockign waits if the caller so desires).
186
187You can only wait once on a condition - additional calls will return 299You can only wait once on a condition - additional calls will return
188immediately. 300immediately.
189 301
302Not all event models support a blocking wait - some die in that case
303(programs might want to do that to stay interactive), so I<if you are
304using this from a module, never require a blocking wait>, but let the
305caller decide whether the call will block or not (for example, by coupling
306condition variables with some kind of request results and supporting
307callbacks so the caller knows that getting the result will not block,
308while still suppporting blocking waits if the caller so desires).
309
310Another reason I<never> to C<< ->wait >> in a module is that you cannot
311sensibly have two C<< ->wait >>'s in parallel, as that would require
312multiple interpreters or coroutines/threads, none of which C<AnyEvent>
313can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
314L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
315from different coroutines, however).
316
190=item $cv->broadcast 317=item $cv->broadcast
191 318
192Flag the condition as ready - a running C<< ->wait >> and all further 319Flag the condition as ready - a running C<< ->wait >> and all further
193calls 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
194is waiting the broadcast will be remembered.. 321called. If nobody is waiting the broadcast will be remembered..
322
323=back
195 324
196Example: 325Example:
197 326
198 # wait till the result is ready 327 # wait till the result is ready
199 my $result_ready = AnyEvent->condvar; 328 my $result_ready = AnyEvent->condvar;
200 329
201 # do something such as adding a timer 330 # do something such as adding a timer
202 # or socket watcher the calls $result_ready->broadcast 331 # or socket watcher the calls $result_ready->broadcast
203 # 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 );
204 338
339 # this "blocks" (while handling events) till the watcher
340 # calls broadcast
205 $result_ready->wait; 341 $result_ready->wait;
206 342
207=back 343=head1 GLOBAL VARIABLES AND FUNCTIONS
208
209=head2 SIGNAL WATCHERS
210
211You can listen for signals using a signal watcher, C<signal> is the signal
212I<name> without any C<SIG> prefix. Multiple signals events can be clumped
213together into one callback invocation, and callback invocation might or
214might not be asynchronous.
215
216These watchers might use C<%SIG>, so programs overwriting those signals
217directly will likely not work correctly.
218
219Example: exit on SIGINT
220
221 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
222
223=head2 CHILD PROCESS WATCHERS
224
225You can also listen for the status of a child process specified by the
226C<pid> argument (or any child if the pid argument is 0). The watcher will
227trigger as often as status change for the child are received. This works
228by installing a signal handler for C<SIGCHLD>. The callback will be called with
229the pid and exit status (as returned by waitpid).
230
231Example: wait for pid 1333
232
233 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
234
235=head1 GLOBALS
236 344
237=over 4 345=over 4
238 346
239=item $AnyEvent::MODEL 347=item $AnyEvent::MODEL
240 348
… …
245AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 353AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
246 354
247The known classes so far are: 355The known classes so far are:
248 356
249 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 357 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
250 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
251 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 358 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
359 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
252 AnyEvent::Impl::Event based on Event, also second best choice :) 360 AnyEvent::Impl::Event based on Event, second best choice.
253 AnyEvent::Impl::Glib based on Glib, second-best choice. 361 AnyEvent::Impl::Glib based on Glib, third-best choice.
254 AnyEvent::Impl::Tk based on Tk, very bad choice. 362 AnyEvent::Impl::Tk based on Tk, very bad choice.
255 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 363 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
364 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
365 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
256 366
257=item AnyEvent::detect 367=item AnyEvent::detect
258 368
259Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 369Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
260necessary. You should only call this function right before you would have 370if necessary. You should only call this function right before you would
261created an AnyEvent watcher anyway, that is, very late at runtime. 371have created an AnyEvent watcher anyway, that is, as late as possible at
372runtime.
262 373
263=back 374=back
264 375
265=head1 WHAT TO DO IN A MODULE 376=head1 WHAT TO DO IN A MODULE
266 377
267As a module author, you should "use AnyEvent" and call AnyEvent methods 378As a module author, you should C<use AnyEvent> and call AnyEvent methods
268freely, 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.
269 380
270Be careful when you create watchers in the module body - Anyevent will 381Be careful when you create watchers in the module body - AnyEvent will
271decide 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
272by 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
273to load the event module first. 384to load the event module first.
274 385
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
275=head1 WHAT TO DO IN THE MAIN PROGRAM 396=head1 WHAT TO DO IN THE MAIN PROGRAM
276 397
277There 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
278dictate which event model to use. 399dictate which event model to use.
279 400
280If 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
281do 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.
282 404
283If 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
284programs 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
285it before loading AnyEvent or any module that uses it, generally, as early 407event module before loading AnyEvent or any module that uses it: generally
286as possible. The reason is that modules might create watchers when they 408speaking, you should load it as early as possible. The reason is that
287are 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
288it 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
289correct one yourself. 411might chose the wrong one unless you load the correct one yourself.
290 412
291You can chose to use a rather inefficient pure-perl implementation by 413You can chose to use a rather inefficient pure-perl implementation by
292loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 414loading the C<AnyEvent::Impl::Perl> module, which gives you similar
293generally better. 415behaviour everywhere, but letting AnyEvent chose is generally better.
294 416
295=cut 417=cut
296 418
297package AnyEvent; 419package AnyEvent;
298 420
299no warnings; 421no warnings;
300use strict; 422use strict;
301 423
302use Carp; 424use Carp;
303 425
304our $VERSION = '3.0'; 426our $VERSION = '3.12';
305our $MODEL; 427our $MODEL;
306 428
307our $AUTOLOAD; 429our $AUTOLOAD;
308our @ISA; 430our @ISA;
309 431
… …
311 433
312our @REGISTRY; 434our @REGISTRY;
313 435
314my @models = ( 436my @models = (
315 [Coro::EV:: => AnyEvent::Impl::CoroEV::], 437 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
438 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
316 [EV:: => AnyEvent::Impl::EV::], 439 [EV:: => AnyEvent::Impl::EV::],
317 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
318 [Event:: => AnyEvent::Impl::Event::], 440 [Event:: => AnyEvent::Impl::Event::],
319 [Glib:: => AnyEvent::Impl::Glib::], 441 [Glib:: => AnyEvent::Impl::Glib::],
320 [Tk:: => AnyEvent::Impl::Tk::], 442 [Tk:: => AnyEvent::Impl::Tk::],
321 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 443 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
322); 444);
445my @models_detect = (
446 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
447 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
448);
323 449
324our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 450our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
325 451
326sub detect() { 452sub detect() {
327 unless ($MODEL) { 453 unless ($MODEL) {
328 no strict 'refs'; 454 no strict 'refs';
329 455
456 if ($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 $verbose > 1;
461 }
462 }
463
330 # check for already loaded models 464 # check for already loaded models
465 unless ($MODEL) {
331 for (@REGISTRY, @models) { 466 for (@REGISTRY, @models, @models_detect) {
332 my ($package, $model) = @$_; 467 my ($package, $model) = @$_;
333 if (${"$package\::VERSION"} > 0) { 468 if (${"$package\::VERSION"} > 0) {
334 if (eval "require $model") { 469 if (eval "require $model") {
335 $MODEL = $model; 470 $MODEL = $model;
336 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 471 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
337 last; 472 last;
473 }
338 } 474 }
339 } 475 }
340 }
341 476
342 unless ($MODEL) { 477 unless ($MODEL) {
343 # try to load a model 478 # try to load a model
344 479
345 for (@REGISTRY, @models) { 480 for (@REGISTRY, @models) {
346 my ($package, $model) = @$_; 481 my ($package, $model) = @$_;
347 if (eval "require $package" 482 if (eval "require $package"
348 and ${"$package\::VERSION"} > 0 483 and ${"$package\::VERSION"} > 0
349 and eval "require $model") { 484 and eval "require $model") {
350 $MODEL = $model; 485 $MODEL = $model;
351 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 486 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
352 last; 487 last;
488 }
353 } 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.";
354 } 493 }
355
356 $MODEL
357 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.";
358 } 494 }
359 495
360 unshift @ISA, $MODEL; 496 unshift @ISA, $MODEL;
361 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 497 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
362 } 498 }
… …
473 undef $CHLD_W unless keys %PID_CB; 609 undef $CHLD_W unless keys %PID_CB;
474} 610}
475 611
476=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 612=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
477 613
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
478If you need to support another event library which isn't directly 618If you need to support another event library which isn't directly
479supported by AnyEvent, you can supply your own interface to it by 619supported by AnyEvent, you can supply your own interface to it by
480pushing, before the first watcher gets created, the package name of 620pushing, before the first watcher gets created, the package name of
481the 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
482C<@AnyEvent::REGISTRY>. You can do that before and even without loading 622C<@AnyEvent::REGISTRY>. You can do that before and even without loading
483AnyEvent. 623AnyEvent, so it is reasonably cheap.
484 624
485Example: 625Example:
486 626
487 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 627 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
488 628
489This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 629This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
490package/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
491AnyEvent 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
492first check for the presence of urxvt. 633will first check for the presence of urxvt by trying to C<use> the
634C<urxvt::anyevent> module.
493 635
494The class should provide implementations for all watcher types (see 636The class should provide implementations for all watcher types. See
495L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 637L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
496(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
497AnyEvent::Impl::Glib> to see the sources). 639see the sources.
498 640
641If you don't provide C<signal> and C<child> watchers than AnyEvent will
642provide suitable (hopefully) replacements.
643
499The 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)
500uses 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
501because it doesn't make sense outside the embedded interpreter inside 646in AnyEvent because it doesn't make sense outside the embedded interpreter
502I<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
503I<rxvt-unicode> distribution. 648I<rxvt-unicode> distribution.
504 649
505I<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
506condition variables: code blocking while waiting for a condition will 651condition variables: code blocking while waiting for a condition will
507C<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
508not be in an interactive application, so it makes sense. 653not be done in an interactive application, so it makes sense.
509 654
510=head1 ENVIRONMENT VARIABLES 655=head1 ENVIRONMENT VARIABLES
511 656
512The following environment variables are used by this module: 657The following environment variables are used by this module:
513 658
514C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 659=over 4
515model gets used.
516 660
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
517=head1 EXAMPLE 684=head1 EXAMPLE PROGRAM
518 685
519The 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
520to 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
521when the user enters quit: 688program when the user enters quit:
522 689
523 use AnyEvent; 690 use AnyEvent;
524 691
525 my $cv = AnyEvent->condvar; 692 my $cv = AnyEvent->condvar;
526 693
527 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 694 my $io_watcher = AnyEvent->io (
695 fh => \*STDIN,
696 poll => 'r',
697 cb => sub {
528 warn "io event <$_[0]>\n"; # will always output <r> 698 warn "io event <$_[0]>\n"; # will always output <r>
529 chomp (my $input = <STDIN>); # read a line 699 chomp (my $input = <STDIN>); # read a line
530 warn "read: $input\n"; # output what has been read 700 warn "read: $input\n"; # output what has been read
531 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 701 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
702 },
532 }); 703 );
533 704
534 my $time_watcher; # can only be used once 705 my $time_watcher; # can only be used once
535 706
536 sub new_timer { 707 sub new_timer {
537 $timer = AnyEvent->timer (after => 1, cb => sub { 708 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
619 $txn->{finished}->wait; 790 $txn->{finished}->wait;
620 return $txn->{result}; 791 return $txn->{result};
621 792
622The 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)
623that occured during request processing. The C<result> method detects 794that occured during request processing. The C<result> method detects
624wether an exception as thrown (it is stored inside the $txn object) 795whether an exception as thrown (it is stored inside the $txn object)
625and just throws the exception, which means connection errors and other 796and just throws the exception, which means connection errors and other
626problems 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
627random callback. 798random callback.
628 799
629All of this enables the following usage styles: 800All of this enables the following usage styles:
630 801
6311. Blocking: 8021. Blocking:
632 803
633 my $data = $fcp->client_get ($url); 804 my $data = $fcp->client_get ($url);
634 805
6352. Blocking, but parallelizing: 8062. Blocking, but running in parallel:
636 807
637 my @datas = map $_->result, 808 my @datas = map $_->result,
638 map $fcp->txn_client_get ($_), 809 map $fcp->txn_client_get ($_),
639 @urls; 810 @urls;
640 811
641Both blocking examples work without the module user having to know 812Both blocking examples work without the module user having to know
642anything about events. 813anything about events.
643 814
6443a. Event-based in a main program, using any support Event module: 8153a. Event-based in a main program, using any supported event module:
645 816
646 use Event; 817 use EV;
647 818
648 $fcp->txn_client_get ($url)->cb (sub { 819 $fcp->txn_client_get ($url)->cb (sub {
649 my $txn = shift; 820 my $txn = shift;
650 my $data = $txn->result; 821 my $data = $txn->result;
651 ... 822 ...
652 }); 823 });
653 824
654 Event::loop; 825 EV::loop;
655 826
6563b. The module user could use AnyEvent, too: 8273b. The module user could use AnyEvent, too:
657 828
658 use AnyEvent; 829 use AnyEvent;
659 830
… …
664 $quit->broadcast; 835 $quit->broadcast;
665 }); 836 });
666 837
667 $quit->wait; 838 $quit->wait;
668 839
840=head1 FORK
841
842Most event libraries are not fork-safe. The ones who are usually are
843because they are so inefficient. Only L<EV> is fully fork-aware.
844
845If you have to fork, you must either do so I<before> creating your first
846watcher OR you must not use AnyEvent at all in the child.
847
848=head1 SECURITY CONSIDERATIONS
849
850AnyEvent can be forced to load any event model via
851$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
669=head1 SEE ALSO 864=head1 SEE ALSO
670 865
671Event 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>.
672 869
870Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
673Implementations: 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>.
674 874
675Nontrivial usage example: L<Net::FCP>. 875Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
676 876
677=head1 877=head1 AUTHOR
878
879 Marc Lehmann <schmorp@schmorp.de>
880 http://home.schmorp.de/
678 881
679=cut 882=cut
680 883
6811 8841
682 885

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines