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Revision 1.44 by root, Mon Apr 7 19:42:18 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
5Event, Coro, Glib, Tk, Perl - various supported event loops 5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
… …
14 14
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores wether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->wait; # enters "main loop" till $condvar gets ->broadcast 20 $w->wait; # enters "main loop" till $condvar gets ->broadcast
21 $w->broadcast; # wake up current and all future wait's 21 $w->broadcast; # wake up current and all future wait's
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
… …
29policy> and AnyEvent is I<small and efficient>. 29policy> and AnyEvent is I<small and efficient>.
30 30
31First and foremost, I<AnyEvent is not an event model> itself, it only 31First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a 32interfaces to whatever event model the main program happens to use in a
33pragmatic way. For event models and certain classes of immortals alike, 33pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality, and AnyEvent 34the statement "there can only be one" is a bitter reality: In general,
35helps hiding the differences. 35only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops.
36 37
37The goal of AnyEvent is to offer module authors the ability to do event 38The goal of AnyEvent is to offer module authors the ability to do event
38programming (waiting for I/O or timer events) without subscribing to a 39programming (waiting for I/O or timer events) without subscribing to a
39religion, a way of living, and most importantly: without forcing your 40religion, a way of living, and most importantly: without forcing your
40module users into the same thing by forcing them to use the same event 41module users into the same thing by forcing them to use the same event
41model you use. 42model you use.
42 43
43For modules like POE or IO::Async (which is actually doing all I/O 44For modules like POE or IO::Async (which is a total misnomer as it is
44I<synchronously>...), using them in your module is like joining a 45actually doing all I/O I<synchronously>...), using them in your module is
45cult: After you joined, you are dependent on them and you cannot use 46like joining a cult: After you joined, you are dependent on them and you
46anything else, as it is simply incompatible to everything that isn't 47cannot use anything else, as it is simply incompatible to everything that
47itself. 48isn't itself. What's worse, all the potential users of your module are
49I<also> forced to use the same event loop you use.
48 50
49AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk 51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50works fine etc. etc. but none of these work together with the rest: POE 52fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51+ IO::Async? no go. Tk + Event? no go. If your module uses one of 53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
52those, every user of your module has to use it, too. If your module 54your module uses one of those, every user of your module has to use it,
53uses AnyEvent, it works transparently with all event models it supports 55too. But if your module uses AnyEvent, it works transparently with all
54(including stuff like POE and IO::Async). 56event models it supports (including stuff like POE and IO::Async, as long
57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof).
55 59
56In addition of being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
57model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
58modules, you get an enourmous amount of code and strict rules you have 62modules, you get an enourmous amount of code and strict rules you have to
59to follow. AnyEvent, on the other hand, is lean and to the point by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
60offering the functionality that is useful, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
61technically possible. 65technically possible.
62 66
63Of course, if you want lots of policy (this is arguably somewhat useful 67Of course, if you want lots of policy (this can arguably be somewhat
64in many cases) and you want to force your users to the one and only event 68useful) and you want to force your users to use the one and only event
65model your module forces on them, you should I<not> use this module. 69model, you should I<not> use this module.
66 70
67 71
68=head1 DESCRIPTION 72=head1 DESCRIPTION
69 73
70L<AnyEvent> provides an identical interface to multiple event loops. This 74L<AnyEvent> provides an identical interface to multiple event loops. This
71allows module authors to utilise an event loop without forcing module 75allows module authors to utilise an event loop without forcing module
72users to use the same event loop (as only a single event loop can coexist 76users to use the same event loop (as only a single event loop can coexist
73peacefully at any one time). 77peacefully at any one time).
74 78
75The interface itself is vaguely similar but not identical to the Event 79The interface itself is vaguely similar, but not identical to the L<Event>
76module. 80module.
77 81
78On the first call of any method, the module tries to detect the currently 82During the first call of any watcher-creation method, the module tries
79loaded event loop by probing wether any of the following modules is 83to detect the currently loaded event loop by probing whether one of the
80loaded: 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>,
81used. 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,
82order 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
83used. 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
84event 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
123Only 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
124a socket you can have one r + one w, not any more (limitation comes from 151copy of it alive/open.
125Tk - if you are sure you are not using Tk this limitation is gone).
126 152
127Filehandles 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
128filehandle 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.
129 159
130Example: 160Example:
131 161
132 # 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
133 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 163 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
139=head2 TIME WATCHERS 169=head2 TIME WATCHERS
140 170
141You can create a time watcher by calling the C<< AnyEvent->timer >> 171You can create a time watcher by calling the C<< AnyEvent->timer >>
142method with the following mandatory arguments: 172method with the following mandatory arguments:
143 173
144C<after> after how many seconds (fractions are supported) should the timer 174C<after> specifies after how many seconds (fractional values are
145activate. C<cb> the callback to invoke. 175supported) should the timer activate. C<cb> the callback to invoke in that
176case.
146 177
147The 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
148timer 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
149and Glib). 180and Glib).
150 181
… …
156 }); 187 });
157 188
158 # to cancel the timer: 189 # to cancel the timer:
159 undef $w; 190 undef $w;
160 191
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
161=head2 CONDITION WATCHERS 265=head2 CONDITION VARIABLES
162 266
163Condition watchers can be created by calling the C<< AnyEvent->condvar >> 267Condition variables can be created by calling the C<< AnyEvent->condvar >>
164method without any arguments. 268method without any arguments.
165 269
166A condition watcher watches for a condition - precisely that the C<< 270A condition variable waits for a condition - precisely that the C<<
167->broadcast >> method has been called. 271->broadcast >> method has been called.
168 272
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
169Note that condition watchers recurse into the event loop - if you have 283Note that condition variables recurse into the event loop - if you have
170two 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
171lose. Therefore, condition watchers are good to export to your caller, but 285lose. Therefore, condition variables are good to export to your caller, but
172you should avoid making a blocking wait, at least in callbacks, as this 286you should avoid making a blocking wait yourself, at least in callbacks,
173usually asks for trouble. 287as this asks for trouble.
174 288
175The watcher has only two methods: 289This object has two methods:
176 290
177=over 4 291=over 4
178 292
179=item $cv->wait 293=item $cv->wait
180 294
181Wait (blocking if necessary) until the C<< ->broadcast >> method has been 295Wait (blocking if necessary) until the C<< ->broadcast >> method has been
182called on c<$cv>, while servicing other watchers normally. 296called on c<$cv>, while servicing other watchers normally.
183 297
184Not all event models support a blocking wait - some die in that case, so
185if you are using this from a module, never require a blocking wait, but
186let the caller decide wether the call will block or not (for example,
187by coupling condition variables with some kind of request results and
188supporting callbacks so the caller knows that getting the result will not
189block, while still suppporting blockign waits if the caller so desires).
190
191You can only wait once on a condition - additional calls will return 298You can only wait once on a condition - additional calls will return
192immediately. 299immediately.
193 300
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
194=item $cv->broadcast 316=item $cv->broadcast
195 317
196Flag the condition as ready - a running C<< ->wait >> and all further 318Flag the condition as ready - a running C<< ->wait >> and all further
197calls 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
198is waiting the broadcast will be remembered.. 320called. If nobody is waiting the broadcast will be remembered..
321
322=back
199 323
200Example: 324Example:
201 325
202 # wait till the result is ready 326 # wait till the result is ready
203 my $result_ready = AnyEvent->condvar; 327 my $result_ready = AnyEvent->condvar;
204 328
205 # do something such as adding a timer 329 # do something such as adding a timer
206 # or socket watcher the calls $result_ready->broadcast 330 # or socket watcher the calls $result_ready->broadcast
207 # 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 );
208 337
338 # this "blocks" (while handling events) till the watcher
339 # calls broadcast
209 $result_ready->wait; 340 $result_ready->wait;
210 341
211=back 342=head1 GLOBAL VARIABLES AND FUNCTIONS
212
213=head2 SIGNAL WATCHERS
214
215You can listen for signals using a signal watcher, C<signal> is the signal
216I<name> without any C<SIG> prefix. Multiple signals events can be clumped
217together into one callback invocation, and callback invocation might or
218might not be asynchronous.
219
220These watchers might use C<%SIG>, so programs overwriting those signals
221directly will likely not work correctly.
222
223Example: exit on SIGINT
224
225 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
226
227=head2 CHILD PROCESS WATCHERS
228
229You can also listen for the status of a child process specified by the
230C<pid> argument (or any child if the pid argument is 0). The watcher will
231trigger as often as status change for the child are received. This works
232by installing a signal handler for C<SIGCHLD>. The callback will be called with
233the pid and exit status (as returned by waitpid).
234
235Example: wait for pid 1333
236
237 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
238
239=head1 GLOBALS
240 343
241=over 4 344=over 4
242 345
243=item $AnyEvent::MODEL 346=item $AnyEvent::MODEL
244 347
… …
249AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 352AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
250 353
251The known classes so far are: 354The known classes so far are:
252 355
253 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 356 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
254 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
255 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 357 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
358 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
256 AnyEvent::Impl::Event based on Event, also second best choice :) 359 AnyEvent::Impl::Event based on Event, second best choice.
257 AnyEvent::Impl::Glib based on Glib, second-best choice. 360 AnyEvent::Impl::Glib based on Glib, third-best choice.
258 AnyEvent::Impl::Tk based on Tk, very bad choice. 361 AnyEvent::Impl::Tk based on Tk, very bad choice.
259 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 362 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
363 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
364 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
260 365
261=item AnyEvent::detect 366=item AnyEvent::detect
262 367
263Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 368Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
264necessary. You should only call this function right before you would have 369if necessary. You should only call this function right before you would
265created an AnyEvent watcher anyway, that is, very late at runtime. 370have created an AnyEvent watcher anyway, that is, as late as possible at
371runtime.
266 372
267=back 373=back
268 374
269=head1 WHAT TO DO IN A MODULE 375=head1 WHAT TO DO IN A MODULE
270 376
271As a module author, you should "use AnyEvent" and call AnyEvent methods 377As a module author, you should C<use AnyEvent> and call AnyEvent methods
272freely, 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.
273 379
274Be careful when you create watchers in the module body - Anyevent will 380Be careful when you create watchers in the module body - AnyEvent will
275decide 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
276by 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
277to load the event module first. 383to load the event module first.
278 384
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
279=head1 WHAT TO DO IN THE MAIN PROGRAM 395=head1 WHAT TO DO IN THE MAIN PROGRAM
280 396
281There 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
282dictate which event model to use. 398dictate which event model to use.
283 399
284If 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
285do 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.
286 403
287If 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
288programs 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
289it before loading AnyEvent or any module that uses it, generally, as early 406event module before loading AnyEvent or any module that uses it: generally
290as possible. The reason is that modules might create watchers when they 407speaking, you should load it as early as possible. The reason is that
291are 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
292it 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
293correct one yourself. 410might chose the wrong one unless you load the correct one yourself.
294 411
295You can chose to use a rather inefficient pure-perl implementation by 412You can chose to use a rather inefficient pure-perl implementation by
296loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 413loading the C<AnyEvent::Impl::Perl> module, which gives you similar
297generally better. 414behaviour everywhere, but letting AnyEvent chose is generally better.
298 415
299=cut 416=cut
300 417
301package AnyEvent; 418package AnyEvent;
302 419
303no warnings; 420no warnings;
304use strict; 421use strict;
305 422
306use Carp; 423use Carp;
307 424
308our $VERSION = '3.0'; 425our $VERSION = '3.12';
309our $MODEL; 426our $MODEL;
310 427
311our $AUTOLOAD; 428our $AUTOLOAD;
312our @ISA; 429our @ISA;
313 430
… …
315 432
316our @REGISTRY; 433our @REGISTRY;
317 434
318my @models = ( 435my @models = (
319 [Coro::EV:: => AnyEvent::Impl::CoroEV::], 436 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
437 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
320 [EV:: => AnyEvent::Impl::EV::], 438 [EV:: => AnyEvent::Impl::EV::],
321 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
322 [Event:: => AnyEvent::Impl::Event::], 439 [Event:: => AnyEvent::Impl::Event::],
323 [Glib:: => AnyEvent::Impl::Glib::], 440 [Glib:: => AnyEvent::Impl::Glib::],
324 [Tk:: => AnyEvent::Impl::Tk::], 441 [Tk:: => AnyEvent::Impl::Tk::],
325 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 442 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
326); 443);
444my @models_detect = (
445 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
446 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
447);
327 448
328our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 449our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
329 450
330sub detect() { 451sub detect() {
331 unless ($MODEL) { 452 unless ($MODEL) {
332 no strict 'refs'; 453 no strict 'refs';
333 454
455 if ($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 $verbose > 1;
460 }
461 }
462
334 # check for already loaded models 463 # check for already loaded models
464 unless ($MODEL) {
335 for (@REGISTRY, @models) { 465 for (@REGISTRY, @models, @models_detect) {
336 my ($package, $model) = @$_; 466 my ($package, $model) = @$_;
337 if (${"$package\::VERSION"} > 0) { 467 if (${"$package\::VERSION"} > 0) {
338 if (eval "require $model") { 468 if (eval "require $model") {
339 $MODEL = $model; 469 $MODEL = $model;
340 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 470 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
341 last; 471 last;
472 }
342 } 473 }
343 } 474 }
344 }
345 475
346 unless ($MODEL) { 476 unless ($MODEL) {
347 # try to load a model 477 # try to load a model
348 478
349 for (@REGISTRY, @models) { 479 for (@REGISTRY, @models) {
350 my ($package, $model) = @$_; 480 my ($package, $model) = @$_;
351 if (eval "require $package" 481 if (eval "require $package"
352 and ${"$package\::VERSION"} > 0 482 and ${"$package\::VERSION"} > 0
353 and eval "require $model") { 483 and eval "require $model") {
354 $MODEL = $model; 484 $MODEL = $model;
355 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 485 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
356 last; 486 last;
487 }
357 } 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.";
358 } 492 }
359
360 $MODEL
361 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.";
362 } 493 }
363 494
364 unshift @ISA, $MODEL; 495 unshift @ISA, $MODEL;
365 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 496 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
366 } 497 }
… …
477 undef $CHLD_W unless keys %PID_CB; 608 undef $CHLD_W unless keys %PID_CB;
478} 609}
479 610
480=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 611=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
481 612
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
482If you need to support another event library which isn't directly 617If you need to support another event library which isn't directly
483supported by AnyEvent, you can supply your own interface to it by 618supported by AnyEvent, you can supply your own interface to it by
484pushing, before the first watcher gets created, the package name of 619pushing, before the first watcher gets created, the package name of
485the 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
486C<@AnyEvent::REGISTRY>. You can do that before and even without loading 621C<@AnyEvent::REGISTRY>. You can do that before and even without loading
487AnyEvent. 622AnyEvent, so it is reasonably cheap.
488 623
489Example: 624Example:
490 625
491 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 626 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
492 627
493This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 628This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
494package/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
495AnyEvent 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
496first check for the presence of urxvt. 632will first check for the presence of urxvt by trying to C<use> the
633C<urxvt::anyevent> module.
497 634
498The class should provide implementations for all watcher types (see 635The class should provide implementations for all watcher types. See
499L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 636L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
500(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
501AnyEvent::Impl::Glib> to see the sources). 638see the sources.
502 639
640If you don't provide C<signal> and C<child> watchers than AnyEvent will
641provide suitable (hopefully) replacements.
642
503The 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)
504uses 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
505because it doesn't make sense outside the embedded interpreter inside 645in AnyEvent because it doesn't make sense outside the embedded interpreter
506I<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
507I<rxvt-unicode> distribution. 647I<rxvt-unicode> distribution.
508 648
509I<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
510condition variables: code blocking while waiting for a condition will 650condition variables: code blocking while waiting for a condition will
511C<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
512not be in an interactive application, so it makes sense. 652not be done in an interactive application, so it makes sense.
513 653
514=head1 ENVIRONMENT VARIABLES 654=head1 ENVIRONMENT VARIABLES
515 655
516The following environment variables are used by this module: 656The following environment variables are used by this module:
517 657
518C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 658=over 4
519model gets used.
520 659
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
521=head1 EXAMPLE 683=head1 EXAMPLE PROGRAM
522 684
523The 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
524to 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
525when the user enters quit: 687program when the user enters quit:
526 688
527 use AnyEvent; 689 use AnyEvent;
528 690
529 my $cv = AnyEvent->condvar; 691 my $cv = AnyEvent->condvar;
530 692
531 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 693 my $io_watcher = AnyEvent->io (
694 fh => \*STDIN,
695 poll => 'r',
696 cb => sub {
532 warn "io event <$_[0]>\n"; # will always output <r> 697 warn "io event <$_[0]>\n"; # will always output <r>
533 chomp (my $input = <STDIN>); # read a line 698 chomp (my $input = <STDIN>); # read a line
534 warn "read: $input\n"; # output what has been read 699 warn "read: $input\n"; # output what has been read
535 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 700 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
701 },
536 }); 702 );
537 703
538 my $time_watcher; # can only be used once 704 my $time_watcher; # can only be used once
539 705
540 sub new_timer { 706 sub new_timer {
541 $timer = AnyEvent->timer (after => 1, cb => sub { 707 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
623 $txn->{finished}->wait; 789 $txn->{finished}->wait;
624 return $txn->{result}; 790 return $txn->{result};
625 791
626The 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)
627that occured during request processing. The C<result> method detects 793that occured during request processing. The C<result> method detects
628wether an exception as thrown (it is stored inside the $txn object) 794whether an exception as thrown (it is stored inside the $txn object)
629and just throws the exception, which means connection errors and other 795and just throws the exception, which means connection errors and other
630problems 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
631random callback. 797random callback.
632 798
633All of this enables the following usage styles: 799All of this enables the following usage styles:
634 800
6351. Blocking: 8011. Blocking:
636 802
637 my $data = $fcp->client_get ($url); 803 my $data = $fcp->client_get ($url);
638 804
6392. Blocking, but parallelizing: 8052. Blocking, but running in parallel:
640 806
641 my @datas = map $_->result, 807 my @datas = map $_->result,
642 map $fcp->txn_client_get ($_), 808 map $fcp->txn_client_get ($_),
643 @urls; 809 @urls;
644 810
645Both blocking examples work without the module user having to know 811Both blocking examples work without the module user having to know
646anything about events. 812anything about events.
647 813
6483a. Event-based in a main program, using any support Event module: 8143a. Event-based in a main program, using any supported event module:
649 815
650 use Event; 816 use EV;
651 817
652 $fcp->txn_client_get ($url)->cb (sub { 818 $fcp->txn_client_get ($url)->cb (sub {
653 my $txn = shift; 819 my $txn = shift;
654 my $data = $txn->result; 820 my $data = $txn->result;
655 ... 821 ...
656 }); 822 });
657 823
658 Event::loop; 824 EV::loop;
659 825
6603b. The module user could use AnyEvent, too: 8263b. The module user could use AnyEvent, too:
661 827
662 use AnyEvent; 828 use AnyEvent;
663 829
… …
668 $quit->broadcast; 834 $quit->broadcast;
669 }); 835 });
670 836
671 $quit->wait; 837 $quit->wait;
672 838
839=head1 FORK
840
841Most event libraries are not fork-safe. The ones who are usually are
842because they are so inefficient. Only L<EV> is fully fork-aware.
843
844If you have to fork, you must either do so I<before> creating your first
845watcher OR you must not use AnyEvent at all in the child.
846
847=head1 SECURITY CONSIDERATIONS
848
849AnyEvent can be forced to load any event model via
850$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
673=head1 SEE ALSO 863=head1 SEE ALSO
674 864
675Event 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>.
676 868
869Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
677Implementations: 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>.
678 873
679Nontrivial usage example: L<Net::FCP>. 874Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
680 875
681=head1 876=head1 AUTHOR
877
878 Marc Lehmann <schmorp@schmorp.de>
879 http://home.schmorp.de/
682 880
683=cut 881=cut
684 882
6851 8831
686 884

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