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Revision 1.44 by root, Mon Apr 7 19:42:18 2008 UTC vs.
Revision 1.57 by root, Thu Apr 24 03:19:28 2008 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5Event, Coro, Glib, Tk, Perl - various supported event loops 5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
… …
14 14
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores wether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->wait; # enters "main loop" till $condvar gets ->broadcast 20 $w->wait; # enters "main loop" till $condvar gets ->broadcast
21 $w->broadcast; # wake up current and all future wait's 21 $w->broadcast; # wake up current and all future wait's
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
… …
29policy> and AnyEvent is I<small and efficient>. 29policy> and AnyEvent is I<small and efficient>.
30 30
31First and foremost, I<AnyEvent is not an event model> itself, it only 31First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a 32interfaces to whatever event model the main program happens to use in a
33pragmatic way. For event models and certain classes of immortals alike, 33pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality, and AnyEvent 34the statement "there can only be one" is a bitter reality: In general,
35helps hiding the differences. 35only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops.
36 37
37The goal of AnyEvent is to offer module authors the ability to do event 38The goal of AnyEvent is to offer module authors the ability to do event
38programming (waiting for I/O or timer events) without subscribing to a 39programming (waiting for I/O or timer events) without subscribing to a
39religion, a way of living, and most importantly: without forcing your 40religion, a way of living, and most importantly: without forcing your
40module users into the same thing by forcing them to use the same event 41module users into the same thing by forcing them to use the same event
41model you use. 42model you use.
42 43
43For modules like POE or IO::Async (which is actually doing all I/O 44For modules like POE or IO::Async (which is a total misnomer as it is
44I<synchronously>...), using them in your module is like joining a 45actually doing all I/O I<synchronously>...), using them in your module is
45cult: After you joined, you are dependent on them and you cannot use 46like joining a cult: After you joined, you are dependent on them and you
46anything else, as it is simply incompatible to everything that isn't 47cannot use anything else, as it is simply incompatible to everything that
47itself. 48isn't itself. What's worse, all the potential users of your module are
49I<also> forced to use the same event loop you use.
48 50
49AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk 51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50works fine etc. etc. but none of these work together with the rest: POE 52fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51+ IO::Async? no go. Tk + Event? no go. If your module uses one of 53with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
52those, every user of your module has to use it, too. If your module 54your module uses one of those, every user of your module has to use it,
53uses AnyEvent, it works transparently with all event models it supports 55too. But if your module uses AnyEvent, it works transparently with all
54(including stuff like POE and IO::Async). 56event models it supports (including stuff like POE and IO::Async, as long
57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof).
55 59
56In addition of being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
57model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
58modules, you get an enourmous amount of code and strict rules you have 62modules, you get an enourmous amount of code and strict rules you have to
59to follow. AnyEvent, on the other hand, is lean and to the point by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
60offering the functionality that is useful, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
61technically possible. 65technically possible.
62 66
63Of course, if you want lots of policy (this 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
80loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is 84the following modules is already loaded: L<Coro::EV>, L<Coro::Event>,
85L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one
81used. If none is found, the module tries to load these modules in the 86found is used. If none are found, the module tries to load these modules
82order given. The first one that could be successfully loaded will be 87(excluding Event::Lib and Qt) in the order given. The first one that can
83used. If still none could be found, AnyEvent will fall back to a pure-perl 88be successfully loaded will be used. If, after this, still none could be
84event loop, which is also not very efficient. 89found, AnyEvent will fall back to a pure-perl event loop, which is not
90very efficient, but should work everywhere.
85 91
86Because AnyEvent first checks for modules that are already loaded, loading 92Because AnyEvent first checks for modules that are already loaded, loading
87an Event model explicitly before first using AnyEvent will likely make 93an event model explicitly before first using AnyEvent will likely make
88that model the default. For example: 94that model the default. For example:
89 95
90 use Tk; 96 use Tk;
91 use AnyEvent; 97 use AnyEvent;
92 98
93 # .. AnyEvent will likely default to Tk 99 # .. AnyEvent will likely default to Tk
100
101The I<likely> means that, if any module loads another event model and
102starts using it, all bets are off. Maybe you should tell their authors to
103use AnyEvent so their modules work together with others seamlessly...
94 104
95The pure-perl implementation of AnyEvent is called 105The pure-perl implementation of AnyEvent is called
96C<AnyEvent::Impl::Perl>. Like other event modules you can load it 106C<AnyEvent::Impl::Perl>. Like other event modules you can load it
97explicitly. 107explicitly.
98 108
… …
101AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
102stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
103the callback to call, the filehandle to watch, etc. 113the callback to call, the filehandle to watch, etc.
104 114
105These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
106creating a watcher it will immediately "watch" for events and invoke 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model
118is in control).
119
107the callback. To disable the watcher you have to destroy it (e.g. by 120To disable the watcher you have to destroy it (e.g. by setting the
108setting the variable that stores it to C<undef> or otherwise deleting all 121variable you store it in to C<undef> or otherwise deleting all references
109references to it). 122to it).
110 123
111All watchers are created by calling a method on the C<AnyEvent> class. 124All watchers are created by calling a method on the C<AnyEvent> class.
112 125
126Many watchers either are used with "recursion" (repeating timers for
127example), or need to refer to their watcher object in other ways.
128
129An any way to achieve that is this pattern:
130
131 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132 # you can use $w here, for example to undef it
133 undef $w;
134 });
135
136Note that C<my $w; $w => combination. This is necessary because in Perl,
137my variables are only visible after the statement in which they are
138declared.
139
113=head2 IO WATCHERS 140=head2 IO WATCHERS
114 141
115You can create I/O watcher by calling the C<< AnyEvent->io >> method with 142You can create an I/O watcher by calling the C<< AnyEvent->io >> method
116the following mandatory arguments: 143with the following mandatory key-value pairs as arguments:
117 144
118C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 145C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
119events. C<poll> must be a string that is either C<r> or C<w>, that creates 146events. C<poll> must be a string that is either C<r> or C<w>, which
120a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback 147creates a watcher waiting for "r"eadable or "w"ritable events,
121to invoke everytime the filehandle becomes ready. 148respectively. C<cb> is the callback to invoke each time the file handle
149becomes ready.
122 150
123Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on 151As long as the I/O watcher exists it will keep the file descriptor or a
124a socket you can have one r + one w, not any more (limitation comes from 152copy of it alive/open.
125Tk - if you are sure you are not using Tk this limitation is gone).
126 153
127Filehandles will be kept alive, so as long as the watcher exists, the 154It is not allowed to close a file handle as long as any watcher is active
128filehandle exists, too. 155on the underlying file descriptor.
156
157Some event loops issue spurious readyness notifications, so you should
158always use non-blocking calls when reading/writing from/to your file
159handles.
129 160
130Example: 161Example:
131 162
132 # wait for readability of STDIN, then read a line and disable the watcher 163 # wait for readability of STDIN, then read a line and disable the watcher
133 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 164 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
… …
139=head2 TIME WATCHERS 170=head2 TIME WATCHERS
140 171
141You can create a time watcher by calling the C<< AnyEvent->timer >> 172You can create a time watcher by calling the C<< AnyEvent->timer >>
142method with the following mandatory arguments: 173method with the following mandatory arguments:
143 174
144C<after> after how many seconds (fractions are supported) should the timer 175C<after> specifies after how many seconds (fractional values are
145activate. C<cb> the callback to invoke. 176supported) should the timer activate. C<cb> the callback to invoke in that
177case.
146 178
147The timer callback will be invoked at most once: if you want a repeating 179The timer callback will be invoked at most once: if you want a repeating
148timer you have to create a new watcher (this is a limitation by both Tk 180timer you have to create a new watcher (this is a limitation by both Tk
149and Glib). 181and Glib).
150 182
… …
156 }); 188 });
157 189
158 # to cancel the timer: 190 # to cancel the timer:
159 undef $w; 191 undef $w;
160 192
193Example 2:
194
195 # fire an event after 0.5 seconds, then roughly every second
196 my $w;
197
198 my $cb = sub {
199 # cancel the old timer while creating a new one
200 $w = AnyEvent->timer (after => 1, cb => $cb);
201 };
202
203 # start the "loop" by creating the first watcher
204 $w = AnyEvent->timer (after => 0.5, cb => $cb);
205
206=head3 TIMING ISSUES
207
208There are two ways to handle timers: based on real time (relative, "fire
209in 10 seconds") and based on wallclock time (absolute, "fire at 12
210o'clock").
211
212While most event loops expect timers to specified in a relative way, they use
213absolute time internally. This makes a difference when your clock "jumps",
214for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to
2152008-01-01, a watcher that you created to fire "after" a second might actually take
216six years to finally fire.
217
218AnyEvent cannot compensate for this. The only event loop that is conscious
219about these issues is L<EV>, which offers both relative (ev_timer) and
220absolute (ev_periodic) timers.
221
222AnyEvent always prefers relative timers, if available, matching the
223AnyEvent API.
224
225=head2 SIGNAL WATCHERS
226
227You can watch for signals using a signal watcher, C<signal> is the signal
228I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
229be invoked whenever a signal occurs.
230
231Multiple signals occurances can be clumped together into one callback
232invocation, and callback invocation will be synchronous. synchronous means
233that it might take a while until the signal gets handled by the process,
234but it is guarenteed not to interrupt any other callbacks.
235
236The main advantage of using these watchers is that you can share a signal
237between multiple watchers.
238
239This watcher might use C<%SIG>, so programs overwriting those signals
240directly will likely not work correctly.
241
242Example: exit on SIGINT
243
244 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
245
246=head2 CHILD PROCESS WATCHERS
247
248You can also watch on a child process exit and catch its exit status.
249
250The child process is specified by the C<pid> argument (if set to C<0>, it
251watches for any child process exit). The watcher will trigger as often
252as status change for the child are received. This works by installing a
253signal handler for C<SIGCHLD>. The callback will be called with the pid
254and exit status (as returned by waitpid).
255
256Example: wait for pid 1333
257
258 my $w = AnyEvent->child (
259 pid => 1333,
260 cb => sub {
261 my ($pid, $status) = @_;
262 warn "pid $pid exited with status $status";
263 },
264 );
265
161=head2 CONDITION WATCHERS 266=head2 CONDITION VARIABLES
162 267
163Condition watchers can be created by calling the C<< AnyEvent->condvar >> 268Condition variables can be created by calling the C<< AnyEvent->condvar >>
164method without any arguments. 269method without any arguments.
165 270
166A condition watcher watches for a condition - precisely that the C<< 271A condition variable waits for a condition - precisely that the C<<
167->broadcast >> method has been called. 272->broadcast >> method has been called.
168 273
274They are very useful to signal that a condition has been fulfilled, for
275example, if you write a module that does asynchronous http requests,
276then a condition variable would be the ideal candidate to signal the
277availability of results.
278
279You can also use condition variables to block your main program until
280an event occurs - for example, you could C<< ->wait >> in your main
281program until the user clicks the Quit button in your app, which would C<<
282->broadcast >> the "quit" event.
283
169Note that condition watchers recurse into the event loop - if you have 284Note that condition variables recurse into the event loop - if you have
170two watchers that call C<< ->wait >> in a round-robbin fashion, you 285two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
171lose. Therefore, condition watchers are good to export to your caller, but 286lose. Therefore, condition variables are good to export to your caller, but
172you should avoid making a blocking wait, at least in callbacks, as this 287you should avoid making a blocking wait yourself, at least in callbacks,
173usually asks for trouble. 288as this asks for trouble.
174 289
175The watcher has only two methods: 290This object has two methods:
176 291
177=over 4 292=over 4
178 293
179=item $cv->wait 294=item $cv->wait
180 295
181Wait (blocking if necessary) until the C<< ->broadcast >> method has been 296Wait (blocking if necessary) until the C<< ->broadcast >> method has been
182called on c<$cv>, while servicing other watchers normally. 297called on c<$cv>, while servicing other watchers normally.
183 298
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 299You can only wait once on a condition - additional calls will return
192immediately. 300immediately.
193 301
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
194=item $cv->broadcast 317=item $cv->broadcast
195 318
196Flag the condition as ready - a running C<< ->wait >> and all further 319Flag 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 320calls to C<wait> will (eventually) return after this method has been
198is waiting the broadcast will be remembered.. 321called. If nobody is waiting the broadcast will be remembered..
322
323=back
199 324
200Example: 325Example:
201 326
202 # wait till the result is ready 327 # wait till the result is ready
203 my $result_ready = AnyEvent->condvar; 328 my $result_ready = AnyEvent->condvar;
204 329
205 # do something such as adding a timer 330 # do something such as adding a timer
206 # or socket watcher the calls $result_ready->broadcast 331 # or socket watcher the calls $result_ready->broadcast
207 # 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 );
208 338
339 # this "blocks" (while handling events) till the watcher
340 # calls broadcast
209 $result_ready->wait; 341 $result_ready->wait;
210 342
211=back 343=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
240 344
241=over 4 345=over 4
242 346
243=item $AnyEvent::MODEL 347=item $AnyEvent::MODEL
244 348
… …
249AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 353AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
250 354
251The known classes so far are: 355The known classes so far are:
252 356
253 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 357 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
254 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
255 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 358 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
359 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
256 AnyEvent::Impl::Event based on Event, also second best choice :) 360 AnyEvent::Impl::Event based on Event, second best choice.
257 AnyEvent::Impl::Glib based on Glib, second-best choice. 361 AnyEvent::Impl::Glib based on Glib, third-best choice.
258 AnyEvent::Impl::Tk based on Tk, very bad choice. 362 AnyEvent::Impl::Tk based on Tk, very bad choice.
259 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 363 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
364 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
365 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
260 366
261=item AnyEvent::detect 367=item AnyEvent::detect
262 368
263Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 369Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
264necessary. You should only call this function right before you would have 370if necessary. You should only call this function right before you would
265created an AnyEvent watcher anyway, that is, very late at runtime. 371have created an AnyEvent watcher anyway, that is, as late as possible at
372runtime.
266 373
267=back 374=back
268 375
269=head1 WHAT TO DO IN A MODULE 376=head1 WHAT TO DO IN A MODULE
270 377
271As a module author, you should "use AnyEvent" and call AnyEvent methods 378As 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. 379freely, but you should not load a specific event module or rely on it.
273 380
274Be careful when you create watchers in the module body - Anyevent will 381Be 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 382decide 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 383by calling AnyEvent in your module body you force the user of your module
277to load the event module first. 384to load the event module first.
278 385
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
279=head1 WHAT TO DO IN THE MAIN PROGRAM 396=head1 WHAT TO DO IN THE MAIN PROGRAM
280 397
281There 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
282dictate which event model to use. 399dictate which event model to use.
283 400
284If 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
285do 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.
286 404
287If 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
288programs 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
289it before loading AnyEvent or any module that uses it, generally, as early 407event module before loading AnyEvent or any module that uses it: generally
290as possible. The reason is that modules might create watchers when they 408speaking, 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 409modules might create watchers when they are loaded, and AnyEvent will
292it 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
293correct one yourself. 411might chose the wrong one unless you load the correct one yourself.
294 412
295You can chose to use a rather inefficient pure-perl implementation by 413You can chose to use a rather inefficient pure-perl implementation by
296loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 414loading the C<AnyEvent::Impl::Perl> module, which gives you similar
297generally better. 415behaviour everywhere, but letting AnyEvent chose is generally better.
298 416
299=cut 417=cut
300 418
301package AnyEvent; 419package AnyEvent;
302 420
303no warnings; 421no warnings;
304use strict; 422use strict;
305 423
306use Carp; 424use Carp;
307 425
308our $VERSION = '3.0'; 426our $VERSION = '3.12';
309our $MODEL; 427our $MODEL;
310 428
311our $AUTOLOAD; 429our $AUTOLOAD;
312our @ISA; 430our @ISA;
313 431
… …
315 433
316our @REGISTRY; 434our @REGISTRY;
317 435
318my @models = ( 436my @models = (
319 [Coro::EV:: => AnyEvent::Impl::CoroEV::], 437 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
438 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
320 [EV:: => AnyEvent::Impl::EV::], 439 [EV:: => AnyEvent::Impl::EV::],
321 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
322 [Event:: => AnyEvent::Impl::Event::], 440 [Event:: => AnyEvent::Impl::Event::],
323 [Glib:: => AnyEvent::Impl::Glib::], 441 [Glib:: => AnyEvent::Impl::Glib::],
324 [Tk:: => AnyEvent::Impl::Tk::], 442 [Tk:: => AnyEvent::Impl::Tk::],
325 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 443 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
326); 444);
445my @models_detect = (
446 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
447 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
448);
327 449
328our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 450our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
329 451
330sub detect() { 452sub detect() {
331 unless ($MODEL) { 453 unless ($MODEL) {
332 no strict 'refs'; 454 no strict 'refs';
333 455
456 if ($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 $verbose > 1;
461 }
462 }
463
334 # check for already loaded models 464 # check for already loaded models
465 unless ($MODEL) {
335 for (@REGISTRY, @models) { 466 for (@REGISTRY, @models, @models_detect) {
336 my ($package, $model) = @$_; 467 my ($package, $model) = @$_;
337 if (${"$package\::VERSION"} > 0) { 468 if (${"$package\::VERSION"} > 0) {
338 if (eval "require $model") { 469 if (eval "require $model") {
339 $MODEL = $model; 470 $MODEL = $model;
340 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 471 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
341 last; 472 last;
473 }
342 } 474 }
343 } 475 }
344 }
345 476
346 unless ($MODEL) { 477 unless ($MODEL) {
347 # try to load a model 478 # try to load a model
348 479
349 for (@REGISTRY, @models) { 480 for (@REGISTRY, @models) {
350 my ($package, $model) = @$_; 481 my ($package, $model) = @$_;
351 if (eval "require $package" 482 if (eval "require $package"
352 and ${"$package\::VERSION"} > 0 483 and ${"$package\::VERSION"} > 0
353 and eval "require $model") { 484 and eval "require $model") {
354 $MODEL = $model; 485 $MODEL = $model;
355 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 486 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
356 last; 487 last;
488 }
357 } 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.";
358 } 493 }
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 } 494 }
363 495
364 unshift @ISA, $MODEL; 496 unshift @ISA, $MODEL;
365 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 497 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
366 } 498 }
… …
477 undef $CHLD_W unless keys %PID_CB; 609 undef $CHLD_W unless keys %PID_CB;
478} 610}
479 611
480=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 612=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
481 613
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
482If you need to support another event library which isn't directly 618If you need to support another event library which isn't directly
483supported by AnyEvent, you can supply your own interface to it by 619supported by AnyEvent, you can supply your own interface to it by
484pushing, before the first watcher gets created, the package name of 620pushing, before the first watcher gets created, the package name of
485the 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
486C<@AnyEvent::REGISTRY>. You can do that before and even without loading 622C<@AnyEvent::REGISTRY>. You can do that before and even without loading
487AnyEvent. 623AnyEvent, so it is reasonably cheap.
488 624
489Example: 625Example:
490 626
491 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 627 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
492 628
493This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 629This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
494package/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
495AnyEvent 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
496first check for the presence of urxvt. 633will first check for the presence of urxvt by trying to C<use> the
634C<urxvt::anyevent> module.
497 635
498The class should provide implementations for all watcher types (see 636The class should provide implementations for all watcher types. See
499L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 637L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
500(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
501AnyEvent::Impl::Glib> to see the sources). 639see the sources.
502 640
641If you don't provide C<signal> and C<child> watchers than AnyEvent will
642provide suitable (hopefully) replacements.
643
503The 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)
504uses 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
505because it doesn't make sense outside the embedded interpreter inside 646in AnyEvent because it doesn't make sense outside the embedded interpreter
506I<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
507I<rxvt-unicode> distribution. 648I<rxvt-unicode> distribution.
508 649
509I<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
510condition variables: code blocking while waiting for a condition will 651condition variables: code blocking while waiting for a condition will
511C<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
512not be in an interactive application, so it makes sense. 653not be done in an interactive application, so it makes sense.
513 654
514=head1 ENVIRONMENT VARIABLES 655=head1 ENVIRONMENT VARIABLES
515 656
516The following environment variables are used by this module: 657The following environment variables are used by this module:
517 658
518C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 659=over 4
519model gets used.
520 660
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
521=head1 EXAMPLE 684=head1 EXAMPLE PROGRAM
522 685
523The 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
524to 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
525when the user enters quit: 688program when the user enters quit:
526 689
527 use AnyEvent; 690 use AnyEvent;
528 691
529 my $cv = AnyEvent->condvar; 692 my $cv = AnyEvent->condvar;
530 693
531 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 694 my $io_watcher = AnyEvent->io (
695 fh => \*STDIN,
696 poll => 'r',
697 cb => sub {
532 warn "io event <$_[0]>\n"; # will always output <r> 698 warn "io event <$_[0]>\n"; # will always output <r>
533 chomp (my $input = <STDIN>); # read a line 699 chomp (my $input = <STDIN>); # read a line
534 warn "read: $input\n"; # output what has been read 700 warn "read: $input\n"; # output what has been read
535 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 701 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
702 },
536 }); 703 );
537 704
538 my $time_watcher; # can only be used once 705 my $time_watcher; # can only be used once
539 706
540 sub new_timer { 707 sub new_timer {
541 $timer = AnyEvent->timer (after => 1, cb => sub { 708 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
623 $txn->{finished}->wait; 790 $txn->{finished}->wait;
624 return $txn->{result}; 791 return $txn->{result};
625 792
626The 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)
627that occured during request processing. The C<result> method detects 794that occured during request processing. The C<result> method detects
628wether an exception as thrown (it is stored inside the $txn object) 795whether an exception as thrown (it is stored inside the $txn object)
629and just throws the exception, which means connection errors and other 796and 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 797problems get reported tot he code that tries to use the result, not in a
631random callback. 798random callback.
632 799
633All of this enables the following usage styles: 800All of this enables the following usage styles:
634 801
6351. Blocking: 8021. Blocking:
636 803
637 my $data = $fcp->client_get ($url); 804 my $data = $fcp->client_get ($url);
638 805
6392. Blocking, but parallelizing: 8062. Blocking, but running in parallel:
640 807
641 my @datas = map $_->result, 808 my @datas = map $_->result,
642 map $fcp->txn_client_get ($_), 809 map $fcp->txn_client_get ($_),
643 @urls; 810 @urls;
644 811
645Both blocking examples work without the module user having to know 812Both blocking examples work without the module user having to know
646anything about events. 813anything about events.
647 814
6483a. Event-based in a main program, using any support Event module: 8153a. Event-based in a main program, using any supported event module:
649 816
650 use Event; 817 use EV;
651 818
652 $fcp->txn_client_get ($url)->cb (sub { 819 $fcp->txn_client_get ($url)->cb (sub {
653 my $txn = shift; 820 my $txn = shift;
654 my $data = $txn->result; 821 my $data = $txn->result;
655 ... 822 ...
656 }); 823 });
657 824
658 Event::loop; 825 EV::loop;
659 826
6603b. The module user could use AnyEvent, too: 8273b. The module user could use AnyEvent, too:
661 828
662 use AnyEvent; 829 use AnyEvent;
663 830
… …
668 $quit->broadcast; 835 $quit->broadcast;
669 }); 836 });
670 837
671 $quit->wait; 838 $quit->wait;
672 839
840=head1 FORK
841
842Most event libraries are not fork-safe. The ones who are usually are
843because they are so inefficient. Only L<EV> is fully fork-aware.
844
845If you have to fork, you must either do so I<before> creating your first
846watcher OR you must not use AnyEvent at all in the child.
847
848=head1 SECURITY CONSIDERATIONS
849
850AnyEvent can be forced to load any event model via
851$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
673=head1 SEE ALSO 864=head1 SEE ALSO
674 865
675Event 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>.
676 869
870Implementations: 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>. 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>.
678 874
679Nontrivial usage example: L<Net::FCP>. 875Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
680 876
681=head1 877=head1 AUTHOR
878
879 Marc Lehmann <schmorp@schmorp.de>
880 http://home.schmorp.de/
682 881
683=cut 882=cut
684 883
6851 8841
686 885

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