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Revision 1.60 by root, Fri Apr 25 01:05:26 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
213use absolute time internally. This makes a difference when your clock
214"jumps", for example, when ntp decides to set your clock backwards from
215the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
216fire "after" a second might actually take six 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, based
220on true relative time) and absolute (ev_periodic, based on wallclock time)
221timers.
222
223AnyEvent always prefers relative timers, if available, matching the
224AnyEvent API.
225
226=head2 SIGNAL WATCHERS
227
228You can watch for signals using a signal watcher, C<signal> is the signal
229I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
230be invoked whenever a signal occurs.
231
232Multiple signal occurances can be clumped together into one callback
233invocation, and callback invocation will be synchronous. synchronous means
234that it might take a while until the signal gets handled by the process,
235but it is guarenteed not to interrupt any other callbacks.
236
237The main advantage of using these watchers is that you can share a signal
238between multiple watchers.
239
240This watcher might use C<%SIG>, so programs overwriting those signals
241directly will likely not work correctly.
242
243Example: exit on SIGINT
244
245 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
246
247=head2 CHILD PROCESS WATCHERS
248
249You can also watch on a child process exit and catch its exit status.
250
251The child process is specified by the C<pid> argument (if set to C<0>, it
252watches for any child process exit). The watcher will trigger as often
253as status change for the child are received. This works by installing a
254signal handler for C<SIGCHLD>. The callback will be called with the pid
255and exit status (as returned by waitpid).
256
257Example: wait for pid 1333
258
259 my $w = AnyEvent->child (
260 pid => 1333,
261 cb => sub {
262 my ($pid, $status) = @_;
263 warn "pid $pid exited with status $status";
264 },
265 );
266
161=head2 CONDITION WATCHERS 267=head2 CONDITION VARIABLES
162 268
163Condition watchers can be created by calling the C<< AnyEvent->condvar >> 269Condition variables can be created by calling the C<< AnyEvent->condvar >>
164method without any arguments. 270method without any arguments.
165 271
166A condition watcher watches for a condition - precisely that the C<< 272A condition variable waits for a condition - precisely that the C<<
167->broadcast >> method has been called. 273->broadcast >> method has been called.
168 274
275They are very useful to signal that a condition has been fulfilled, for
276example, if you write a module that does asynchronous http requests,
277then a condition variable would be the ideal candidate to signal the
278availability of results.
279
280You can also use condition variables to block your main program until
281an event occurs - for example, you could C<< ->wait >> in your main
282program until the user clicks the Quit button in your app, which would C<<
283->broadcast >> the "quit" event.
284
169Note that condition watchers recurse into the event loop - if you have 285Note that condition variables recurse into the event loop - if you have
170two watchers that call C<< ->wait >> in a round-robbin fashion, you 286two 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 287lose. Therefore, condition variables are good to export to your caller, but
172you should avoid making a blocking wait, at least in callbacks, as this 288you should avoid making a blocking wait yourself, at least in callbacks,
173usually asks for trouble. 289as this asks for trouble.
174 290
175The watcher has only two methods: 291This object has two methods:
176 292
177=over 4 293=over 4
178 294
179=item $cv->wait 295=item $cv->wait
180 296
181Wait (blocking if necessary) until the C<< ->broadcast >> method has been 297Wait (blocking if necessary) until the C<< ->broadcast >> method has been
182called on c<$cv>, while servicing other watchers normally. 298called on c<$cv>, while servicing other watchers normally.
183 299
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 300You can only wait once on a condition - additional calls will return
192immediately. 301immediately.
193 302
303Not all event models support a blocking wait - some die in that case
304(programs might want to do that to stay interactive), so I<if you are
305using this from a module, never require a blocking wait>, but let the
306caller decide whether the call will block or not (for example, by coupling
307condition variables with some kind of request results and supporting
308callbacks so the caller knows that getting the result will not block,
309while still suppporting blocking waits if the caller so desires).
310
311Another reason I<never> to C<< ->wait >> in a module is that you cannot
312sensibly have two C<< ->wait >>'s in parallel, as that would require
313multiple interpreters or coroutines/threads, none of which C<AnyEvent>
314can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
315L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
316from different coroutines, however).
317
194=item $cv->broadcast 318=item $cv->broadcast
195 319
196Flag the condition as ready - a running C<< ->wait >> and all further 320Flag 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 321calls to C<wait> will (eventually) return after this method has been
198is waiting the broadcast will be remembered.. 322called. If nobody is waiting the broadcast will be remembered..
323
324=back
199 325
200Example: 326Example:
201 327
202 # wait till the result is ready 328 # wait till the result is ready
203 my $result_ready = AnyEvent->condvar; 329 my $result_ready = AnyEvent->condvar;
204 330
205 # do something such as adding a timer 331 # do something such as adding a timer
206 # or socket watcher the calls $result_ready->broadcast 332 # or socket watcher the calls $result_ready->broadcast
207 # when the "result" is ready. 333 # when the "result" is ready.
334 # in this case, we simply use a timer:
335 my $w = AnyEvent->timer (
336 after => 1,
337 cb => sub { $result_ready->broadcast },
338 );
208 339
340 # this "blocks" (while handling events) till the watcher
341 # calls broadcast
209 $result_ready->wait; 342 $result_ready->wait;
210 343
211=back 344=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
240 345
241=over 4 346=over 4
242 347
243=item $AnyEvent::MODEL 348=item $AnyEvent::MODEL
244 349
… …
249AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 354AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
250 355
251The known classes so far are: 356The known classes so far are:
252 357
253 AnyEvent::Impl::CoroEV based on Coro::EV, best choice. 358 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
254 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
255 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. 359 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
360 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
256 AnyEvent::Impl::Event based on Event, also second best choice :) 361 AnyEvent::Impl::Event based on Event, second best choice.
257 AnyEvent::Impl::Glib based on Glib, second-best choice. 362 AnyEvent::Impl::Glib based on Glib, third-best choice.
258 AnyEvent::Impl::Tk based on Tk, very bad choice. 363 AnyEvent::Impl::Tk based on Tk, very bad choice.
259 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 364 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
365 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
366 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
260 367
261=item AnyEvent::detect 368=item AnyEvent::detect
262 369
263Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 370Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
264necessary. You should only call this function right before you would have 371if necessary. You should only call this function right before you would
265created an AnyEvent watcher anyway, that is, very late at runtime. 372have created an AnyEvent watcher anyway, that is, as late as possible at
373runtime.
266 374
267=back 375=back
268 376
269=head1 WHAT TO DO IN A MODULE 377=head1 WHAT TO DO IN A MODULE
270 378
271As a module author, you should "use AnyEvent" and call AnyEvent methods 379As 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. 380freely, but you should not load a specific event module or rely on it.
273 381
274Be careful when you create watchers in the module body - Anyevent will 382Be 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 383decide 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 384by calling AnyEvent in your module body you force the user of your module
277to load the event module first. 385to load the event module first.
278 386
387Never call C<< ->wait >> on a condition variable unless you I<know> that
388the C<< ->broadcast >> method has been called on it already. This is
389because it will stall the whole program, and the whole point of using
390events is to stay interactive.
391
392It is fine, however, to call C<< ->wait >> when the user of your module
393requests it (i.e. if you create a http request object ad have a method
394called C<results> that returns the results, it should call C<< ->wait >>
395freely, as the user of your module knows what she is doing. always).
396
279=head1 WHAT TO DO IN THE MAIN PROGRAM 397=head1 WHAT TO DO IN THE MAIN PROGRAM
280 398
281There will always be a single main program - the only place that should 399There will always be a single main program - the only place that should
282dictate which event model to use. 400dictate which event model to use.
283 401
284If it doesn't care, it can just "use AnyEvent" and use it itself, or not 402If 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. 403do anything special (it does not need to be event-based) and let AnyEvent
404decide which implementation to chose if some module relies on it.
286 405
287If the main program relies on a specific event model (for example, in Gtk2 406If 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 407Gtk2 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 408event module before loading AnyEvent or any module that uses it: generally
290as possible. The reason is that modules might create watchers when they 409speaking, 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 410modules might create watchers when they are loaded, and AnyEvent will
292it creates watchers, and it might chose the wrong one unless you load the 411decide on the event model to use as soon as it creates watchers, and it
293correct one yourself. 412might chose the wrong one unless you load the correct one yourself.
294 413
295You can chose to use a rather inefficient pure-perl implementation by 414You can chose to use a rather inefficient pure-perl implementation by
296loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is 415loading the C<AnyEvent::Impl::Perl> module, which gives you similar
297generally better. 416behaviour everywhere, but letting AnyEvent chose is generally better.
298 417
299=cut 418=cut
300 419
301package AnyEvent; 420package AnyEvent;
302 421
303no warnings; 422no warnings;
304use strict; 423use strict;
305 424
306use Carp; 425use Carp;
307 426
308our $VERSION = '3.0'; 427our $VERSION = '3.2';
309our $MODEL; 428our $MODEL;
310 429
311our $AUTOLOAD; 430our $AUTOLOAD;
312our @ISA; 431our @ISA;
313 432
… …
315 434
316our @REGISTRY; 435our @REGISTRY;
317 436
318my @models = ( 437my @models = (
319 [Coro::EV:: => AnyEvent::Impl::CoroEV::], 438 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
439 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
320 [EV:: => AnyEvent::Impl::EV::], 440 [EV:: => AnyEvent::Impl::EV::],
321 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
322 [Event:: => AnyEvent::Impl::Event::], 441 [Event:: => AnyEvent::Impl::Event::],
323 [Glib:: => AnyEvent::Impl::Glib::], 442 [Glib:: => AnyEvent::Impl::Glib::],
324 [Tk:: => AnyEvent::Impl::Tk::], 443 [Tk:: => AnyEvent::Impl::Tk::],
325 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 444 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
326); 445);
446my @models_detect = (
447 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
448 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
449);
327 450
328our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); 451our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
329 452
330sub detect() { 453sub detect() {
331 unless ($MODEL) { 454 unless ($MODEL) {
332 no strict 'refs'; 455 no strict 'refs';
333 456
457 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
458 my $model = "AnyEvent::Impl::$1";
459 if (eval "require $model") {
460 $MODEL = $model;
461 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
462 } else {
463 warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
464 }
465 }
466
334 # check for already loaded models 467 # check for already loaded models
468 unless ($MODEL) {
335 for (@REGISTRY, @models) { 469 for (@REGISTRY, @models, @models_detect) {
336 my ($package, $model) = @$_; 470 my ($package, $model) = @$_;
337 if (${"$package\::VERSION"} > 0) { 471 if (${"$package\::VERSION"} > 0) {
338 if (eval "require $model") { 472 if (eval "require $model") {
339 $MODEL = $model; 473 $MODEL = $model;
340 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; 474 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
341 last; 475 last;
476 }
342 } 477 }
343 } 478 }
344 }
345 479
346 unless ($MODEL) { 480 unless ($MODEL) {
347 # try to load a model 481 # try to load a model
348 482
349 for (@REGISTRY, @models) { 483 for (@REGISTRY, @models) {
350 my ($package, $model) = @$_; 484 my ($package, $model) = @$_;
351 if (eval "require $package" 485 if (eval "require $package"
352 and ${"$package\::VERSION"} > 0 486 and ${"$package\::VERSION"} > 0
353 and eval "require $model") { 487 and eval "require $model") {
354 $MODEL = $model; 488 $MODEL = $model;
355 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 489 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
356 last; 490 last;
491 }
357 } 492 }
493
494 $MODEL
495 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 } 496 }
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 } 497 }
363 498
364 unshift @ISA, $MODEL; 499 unshift @ISA, $MODEL;
365 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 500 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
366 } 501 }
… …
477 undef $CHLD_W unless keys %PID_CB; 612 undef $CHLD_W unless keys %PID_CB;
478} 613}
479 614
480=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 615=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
481 616
617This is an advanced topic that you do not normally need to use AnyEvent in
618a module. This section is only of use to event loop authors who want to
619provide AnyEvent compatibility.
620
482If you need to support another event library which isn't directly 621If you need to support another event library which isn't directly
483supported by AnyEvent, you can supply your own interface to it by 622supported by AnyEvent, you can supply your own interface to it by
484pushing, before the first watcher gets created, the package name of 623pushing, before the first watcher gets created, the package name of
485the event module and the package name of the interface to use onto 624the event module and the package name of the interface to use onto
486C<@AnyEvent::REGISTRY>. You can do that before and even without loading 625C<@AnyEvent::REGISTRY>. You can do that before and even without loading
487AnyEvent. 626AnyEvent, so it is reasonably cheap.
488 627
489Example: 628Example:
490 629
491 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 630 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
492 631
493This tells AnyEvent to (literally) use the C<urxvt::anyevent::> 632This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
494package/class when it finds the C<urxvt> package/module is loaded. When 633package/class when it finds the C<urxvt> package/module is already loaded.
634
495AnyEvent is loaded and asked to find a suitable event model, it will 635When AnyEvent is loaded and asked to find a suitable event model, it
496first check for the presence of urxvt. 636will first check for the presence of urxvt by trying to C<use> the
637C<urxvt::anyevent> module.
497 638
498The class should provide implementations for all watcher types (see 639The class should provide implementations for all watcher types. See
499L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> 640L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
500(Source code) and so on for actual examples, use C<perldoc -m 641and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
501AnyEvent::Impl::Glib> to see the sources). 642see the sources.
502 643
644If you don't provide C<signal> and C<child> watchers than AnyEvent will
645provide suitable (hopefully) replacements.
646
503The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) 647The 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 648terminal emulator uses the above line as-is. An interface isn't included
505because it doesn't make sense outside the embedded interpreter inside 649in AnyEvent because it doesn't make sense outside the embedded interpreter
506I<rxvt-unicode>, and it is updated and maintained as part of the 650inside I<rxvt-unicode>, and it is updated and maintained as part of the
507I<rxvt-unicode> distribution. 651I<rxvt-unicode> distribution.
508 652
509I<rxvt-unicode> also cheats a bit by not providing blocking access to 653I<rxvt-unicode> also cheats a bit by not providing blocking access to
510condition variables: code blocking while waiting for a condition will 654condition variables: code blocking while waiting for a condition will
511C<die>. This still works with most modules/usages, and blocking calls must 655C<die>. This still works with most modules/usages, and blocking calls must
512not be in an interactive application, so it makes sense. 656not be done in an interactive application, so it makes sense.
513 657
514=head1 ENVIRONMENT VARIABLES 658=head1 ENVIRONMENT VARIABLES
515 659
516The following environment variables are used by this module: 660The following environment variables are used by this module:
517 661
518C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event 662=over 4
519model gets used.
520 663
664=item C<PERL_ANYEVENT_VERBOSE>
665
666By default, AnyEvent will be completely silent except in fatal
667conditions. You can set this environment variable to make AnyEvent more
668talkative.
669
670When set to C<1> or higher, causes AnyEvent to warn about unexpected
671conditions, such as not being able to load the event model specified by
672C<PERL_ANYEVENT_MODEL>.
673
674When set to C<2> or higher, cause AnyEvent to report to STDERR which event
675model it chooses.
676
677=item C<PERL_ANYEVENT_MODEL>
678
679This can be used to specify the event model to be used by AnyEvent, before
680autodetection and -probing kicks in. It must be a string consisting
681entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
682and the resulting module name is loaded and if the load was successful,
683used as event model. If it fails to load AnyEvent will proceed with
684autodetection and -probing.
685
686This functionality might change in future versions.
687
688For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
689could start your program like this:
690
691 PERL_ANYEVENT_MODEL=Perl perl ...
692
693=back
694
521=head1 EXAMPLE 695=head1 EXAMPLE PROGRAM
522 696
523The following program uses an io watcher to read data from stdin, a timer 697The 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 698to display a message once per second, and a condition variable to quit the
525when the user enters quit: 699program when the user enters quit:
526 700
527 use AnyEvent; 701 use AnyEvent;
528 702
529 my $cv = AnyEvent->condvar; 703 my $cv = AnyEvent->condvar;
530 704
531 my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 705 my $io_watcher = AnyEvent->io (
706 fh => \*STDIN,
707 poll => 'r',
708 cb => sub {
532 warn "io event <$_[0]>\n"; # will always output <r> 709 warn "io event <$_[0]>\n"; # will always output <r>
533 chomp (my $input = <STDIN>); # read a line 710 chomp (my $input = <STDIN>); # read a line
534 warn "read: $input\n"; # output what has been read 711 warn "read: $input\n"; # output what has been read
535 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 712 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
713 },
536 }); 714 );
537 715
538 my $time_watcher; # can only be used once 716 my $time_watcher; # can only be used once
539 717
540 sub new_timer { 718 sub new_timer {
541 $timer = AnyEvent->timer (after => 1, cb => sub { 719 $timer = AnyEvent->timer (after => 1, cb => sub {
… …
623 $txn->{finished}->wait; 801 $txn->{finished}->wait;
624 return $txn->{result}; 802 return $txn->{result};
625 803
626The actual code goes further and collects all errors (C<die>s, exceptions) 804The actual code goes further and collects all errors (C<die>s, exceptions)
627that occured during request processing. The C<result> method detects 805that occured during request processing. The C<result> method detects
628wether an exception as thrown (it is stored inside the $txn object) 806whether an exception as thrown (it is stored inside the $txn object)
629and just throws the exception, which means connection errors and other 807and 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 808problems get reported tot he code that tries to use the result, not in a
631random callback. 809random callback.
632 810
633All of this enables the following usage styles: 811All of this enables the following usage styles:
634 812
6351. Blocking: 8131. Blocking:
636 814
637 my $data = $fcp->client_get ($url); 815 my $data = $fcp->client_get ($url);
638 816
6392. Blocking, but parallelizing: 8172. Blocking, but running in parallel:
640 818
641 my @datas = map $_->result, 819 my @datas = map $_->result,
642 map $fcp->txn_client_get ($_), 820 map $fcp->txn_client_get ($_),
643 @urls; 821 @urls;
644 822
645Both blocking examples work without the module user having to know 823Both blocking examples work without the module user having to know
646anything about events. 824anything about events.
647 825
6483a. Event-based in a main program, using any support Event module: 8263a. Event-based in a main program, using any supported event module:
649 827
650 use Event; 828 use EV;
651 829
652 $fcp->txn_client_get ($url)->cb (sub { 830 $fcp->txn_client_get ($url)->cb (sub {
653 my $txn = shift; 831 my $txn = shift;
654 my $data = $txn->result; 832 my $data = $txn->result;
655 ... 833 ...
656 }); 834 });
657 835
658 Event::loop; 836 EV::loop;
659 837
6603b. The module user could use AnyEvent, too: 8383b. The module user could use AnyEvent, too:
661 839
662 use AnyEvent; 840 use AnyEvent;
663 841
… …
668 $quit->broadcast; 846 $quit->broadcast;
669 }); 847 });
670 848
671 $quit->wait; 849 $quit->wait;
672 850
851=head1 FORK
852
853Most event libraries are not fork-safe. The ones who are usually are
854because they are so inefficient. Only L<EV> is fully fork-aware.
855
856If you have to fork, you must either do so I<before> creating your first
857watcher OR you must not use AnyEvent at all in the child.
858
859=head1 SECURITY CONSIDERATIONS
860
861AnyEvent can be forced to load any event model via
862$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
863execute arbitrary code or directly gain access, it can easily be used to
864make the program hang or malfunction in subtle ways, as AnyEvent watchers
865will not be active when the program uses a different event model than
866specified in the variable.
867
868You can make AnyEvent completely ignore this variable by deleting it
869before the first watcher gets created, e.g. with a C<BEGIN> block:
870
871 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
872
873 use AnyEvent;
874
673=head1 SEE ALSO 875=head1 SEE ALSO
674 876
675Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>. 877Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
878L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
879L<Event::Lib>, L<Qt>.
676 880
881Implementations: 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>. 882L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
883L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
884L<AnyEvent::Impl::Qt>.
678 885
679Nontrivial usage example: L<Net::FCP>. 886Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
680 887
681=head1 888=head1 AUTHOR
889
890 Marc Lehmann <schmorp@schmorp.de>
891 http://home.schmorp.de/
682 892
683=cut 893=cut
684 894
6851 8951
686 896

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