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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.144 by root, Thu May 29 00:14:35 2008 UTC vs.
Revision 1.228 by root, Wed Jul 8 01:11:12 2009 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
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
6event loops.
6 7
7=head1 SYNOPSIS 8=head1 SYNOPSIS
8 9
9 use AnyEvent; 10 use AnyEvent;
10 11
12 # file descriptor readable
11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { 13 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
14
15 # one-shot or repeating timers
16 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
17 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
18
19 print AnyEvent->now; # prints current event loop time
20 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
21
22 # POSIX signal
23 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
24
25 # child process exit
26 my $w = AnyEvent->child (pid => $pid, cb => sub {
27 my ($pid, $status) = @_;
12 ... 28 ...
13 }); 29 });
14 30
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 31 # called when event loop idle (if applicable)
16 ... 32 my $w = AnyEvent->idle (cb => sub { ... });
17 });
18 33
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 34 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's 35 $w->send; # wake up current and all future recv's
21 $w->recv; # enters "main loop" till $condvar gets ->send 36 $w->recv; # enters "main loop" till $condvar gets ->send
37 # use a condvar in callback mode:
38 $w->cb (sub { $_[0]->recv });
39
40=head1 INTRODUCTION/TUTORIAL
41
42This manpage is mainly a reference manual. If you are interested
43in a tutorial or some gentle introduction, have a look at the
44L<AnyEvent::Intro> manpage.
22 45
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 46=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 47
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 48Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 49nowadays. So what is different about AnyEvent?
27 50
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of 51Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>. 52policy> and AnyEvent is I<small and efficient>.
30 53
31First and foremost, I<AnyEvent is not an event model> itself, it only 54First 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 55interfaces to whatever event model the main program happens to use, in a
33pragmatic way. For event models and certain classes of immortals alike, 56pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality: In general, 57the statement "there can only be one" is a bitter reality: In general,
35only one event loop can be active at the same time in a process. AnyEvent 58only one event loop can be active at the same time in a process. AnyEvent
36helps hiding the differences between those event loops. 59cannot change this, but it can hide the differences between those event
60loops.
37 61
38The goal of AnyEvent is to offer module authors the ability to do event 62The goal of AnyEvent is to offer module authors the ability to do event
39programming (waiting for I/O or timer events) without subscribing to a 63programming (waiting for I/O or timer events) without subscribing to a
40religion, a way of living, and most importantly: without forcing your 64religion, a way of living, and most importantly: without forcing your
41module users into the same thing by forcing them to use the same event 65module users into the same thing by forcing them to use the same event
42model you use. 66model you use.
43 67
44For modules like POE or IO::Async (which is a total misnomer as it is 68For modules like POE or IO::Async (which is a total misnomer as it is
45actually doing all I/O I<synchronously>...), using them in your module is 69actually doing all I/O I<synchronously>...), using them in your module is
46like joining a cult: After you joined, you are dependent on them and you 70like joining a cult: After you joined, you are dependent on them and you
47cannot use anything else, as it is simply incompatible to everything that 71cannot use anything else, as they are simply incompatible to everything
48isn't itself. What's worse, all the potential users of your module are 72that isn't them. What's worse, all the potential users of your
49I<also> forced to use the same event loop you use. 73module are I<also> forced to use the same event loop you use.
50 74
51AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works 75AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52fine. AnyEvent + Tk works fine etc. etc. but none of these work together 76fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if 77with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54your module uses one of those, every user of your module has to use it, 78your module uses one of those, every user of your module has to use it,
55too. But if your module uses AnyEvent, it works transparently with all 79too. But if your module uses AnyEvent, it works transparently with all
56event models it supports (including stuff like POE and IO::Async, as long 80event models it supports (including stuff like IO::Async, as long as those
57as those use one of the supported event loops. It is trivial to add new 81use one of the supported event loops. It is trivial to add new event loops
58event loops to AnyEvent, too, so it is future-proof). 82to AnyEvent, too, so it is future-proof).
59 83
60In addition to being free of having to use I<the one and only true event 84In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 85model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enormous amount of code and strict rules you have to 86modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 87follow. AnyEvent, on the other hand, is lean and up to the point, by only
121These watchers are normal Perl objects with normal Perl lifetime. After 145These watchers are normal Perl objects with normal Perl lifetime. After
122creating a watcher it will immediately "watch" for events and invoke the 146creating a watcher it will immediately "watch" for events and invoke the
123callback when the event occurs (of course, only when the event model 147callback when the event occurs (of course, only when the event model
124is in control). 148is in control).
125 149
150Note that B<callbacks must not permanently change global variables>
151potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152callbacks must not C<die> >>. The former is good programming practise in
153Perl and the latter stems from the fact that exception handling differs
154widely between event loops.
155
126To disable the watcher you have to destroy it (e.g. by setting the 156To disable the watcher you have to destroy it (e.g. by setting the
127variable you store it in to C<undef> or otherwise deleting all references 157variable you store it in to C<undef> or otherwise deleting all references
128to it). 158to it).
129 159
130All watchers are created by calling a method on the C<AnyEvent> class. 160All watchers are created by calling a method on the C<AnyEvent> class.
132Many watchers either are used with "recursion" (repeating timers for 162Many watchers either are used with "recursion" (repeating timers for
133example), or need to refer to their watcher object in other ways. 163example), or need to refer to their watcher object in other ways.
134 164
135An any way to achieve that is this pattern: 165An any way to achieve that is this pattern:
136 166
137 my $w; $w = AnyEvent->type (arg => value ..., cb => sub { 167 my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138 # you can use $w here, for example to undef it 168 # you can use $w here, for example to undef it
139 undef $w; 169 undef $w;
140 }); 170 });
141 171
142Note that C<my $w; $w => combination. This is necessary because in Perl, 172Note that C<my $w; $w => combination. This is necessary because in Perl,
143my variables are only visible after the statement in which they are 173my variables are only visible after the statement in which they are
144declared. 174declared.
145 175
146=head2 I/O WATCHERS 176=head2 I/O WATCHERS
147 177
148You can create an I/O watcher by calling the C<< AnyEvent->io >> method 178You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149with the following mandatory key-value pairs as arguments: 179with the following mandatory key-value pairs as arguments:
150 180
151C<fh> the Perl I<file handle> (I<not> file descriptor) to watch 181C<fh> is the Perl I<file handle> (I<not> file descriptor, see below) to
182watch for events (AnyEvent might or might not keep a reference to this
183file handle). Note that only file handles pointing to things for which
184non-blocking operation makes sense are allowed. This includes sockets,
185most character devices, pipes, fifos and so on, but not for example files
186or block devices.
187
152for events. C<poll> must be a string that is either C<r> or C<w>, 188C<poll> must be a string that is either C<r> or C<w>, which creates a
153which creates a watcher waiting for "r"eadable or "w"ritable events, 189watcher waiting for "r"eadable or "w"ritable events, respectively.
190
154respectively. C<cb> is the callback to invoke each time the file handle 191C<cb> is the callback to invoke each time the file handle becomes ready.
155becomes ready.
156 192
157Although the callback might get passed parameters, their value and 193Although the callback might get passed parameters, their value and
158presence is undefined and you cannot rely on them. Portable AnyEvent 194presence is undefined and you cannot rely on them. Portable AnyEvent
159callbacks cannot use arguments passed to I/O watcher callbacks. 195callbacks cannot use arguments passed to I/O watcher callbacks.
160 196
164 200
165Some event loops issue spurious readyness notifications, so you should 201Some event loops issue spurious readyness notifications, so you should
166always use non-blocking calls when reading/writing from/to your file 202always use non-blocking calls when reading/writing from/to your file
167handles. 203handles.
168 204
169Example:
170
171 # wait for readability of STDIN, then read a line and disable the watcher 205Example: wait for readability of STDIN, then read a line and disable the
206watcher.
207
172 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { 208 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173 chomp (my $input = <STDIN>); 209 chomp (my $input = <STDIN>);
174 warn "read: $input\n"; 210 warn "read: $input\n";
175 undef $w; 211 undef $w;
176 }); 212 });
177 213
214=head3 GETTING A FILE HANDLE FROM A FILE DESCRIPTOR
215
216It is not uncommon to only have a file descriptor, while AnyEvent requires
217a Perl file handle.
218
219There are basically two methods to convert a file descriptor into a file handle. If you own
220the file descriptor, you can open it with C<&=>, as in:
221
222 open my $fh, "<&=$fileno" or die "xxx: ยง!";
223
224This will "own" the file descriptor, meaning that when C<$fh> is
225destroyed, it will automatically close the C<$fileno>. Also, note that
226the open mode (read, write, read/write) must correspond with how the
227underlying file descriptor was opened.
228
229In many cases, taking over the file descriptor is now what you want, in
230which case the only alternative is to dup the file descriptor:
231
232 open my $fh, "<&$fileno" or die "xxx: $!";
233
234This has the advantage of not closing the file descriptor and the
235disadvantage of making a slow copy.
236
178=head2 TIME WATCHERS 237=head2 TIME WATCHERS
179 238
180You can create a time watcher by calling the C<< AnyEvent->timer >> 239You can create a time watcher by calling the C<< AnyEvent->timer >>
181method with the following mandatory arguments: 240method with the following mandatory arguments:
182 241
186 245
187Although the callback might get passed parameters, their value and 246Although the callback might get passed parameters, their value and
188presence is undefined and you cannot rely on them. Portable AnyEvent 247presence is undefined and you cannot rely on them. Portable AnyEvent
189callbacks cannot use arguments passed to time watcher callbacks. 248callbacks cannot use arguments passed to time watcher callbacks.
190 249
191The timer callback will be invoked at most once: if you want a repeating 250The callback will normally be invoked once only. If you specify another
192timer you have to create a new watcher (this is a limitation by both Tk 251parameter, C<interval>, as a strictly positive number (> 0), then the
193and Glib). 252callback will be invoked regularly at that interval (in fractional
253seconds) after the first invocation. If C<interval> is specified with a
254false value, then it is treated as if it were missing.
194 255
195Example: 256The callback will be rescheduled before invoking the callback, but no
257attempt is done to avoid timer drift in most backends, so the interval is
258only approximate.
196 259
197 # fire an event after 7.7 seconds 260Example: fire an event after 7.7 seconds.
261
198 my $w = AnyEvent->timer (after => 7.7, cb => sub { 262 my $w = AnyEvent->timer (after => 7.7, cb => sub {
199 warn "timeout\n"; 263 warn "timeout\n";
200 }); 264 });
201 265
202 # to cancel the timer: 266 # to cancel the timer:
203 undef $w; 267 undef $w;
204 268
205Example 2:
206
207 # fire an event after 0.5 seconds, then roughly every second 269Example 2: fire an event after 0.5 seconds, then roughly every second.
208 my $w;
209 270
210 my $cb = sub {
211 # cancel the old timer while creating a new one
212 $w = AnyEvent->timer (after => 1, cb => $cb); 271 my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
272 warn "timeout\n";
213 }; 273 };
214
215 # start the "loop" by creating the first watcher
216 $w = AnyEvent->timer (after => 0.5, cb => $cb);
217 274
218=head3 TIMING ISSUES 275=head3 TIMING ISSUES
219 276
220There are two ways to handle timers: based on real time (relative, "fire 277There are two ways to handle timers: based on real time (relative, "fire
221in 10 seconds") and based on wallclock time (absolute, "fire at 12 278in 10 seconds") and based on wallclock time (absolute, "fire at 12
294In either case, if you care (and in most cases, you don't), then you 351In either case, if you care (and in most cases, you don't), then you
295can get whatever behaviour you want with any event loop, by taking the 352can get whatever behaviour you want with any event loop, by taking the
296difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into 353difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297account. 354account.
298 355
356=item AnyEvent->now_update
357
358Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
359the current time for each loop iteration (see the discussion of L<<
360AnyEvent->now >>, above).
361
362When a callback runs for a long time (or when the process sleeps), then
363this "current" time will differ substantially from the real time, which
364might affect timers and time-outs.
365
366When this is the case, you can call this method, which will update the
367event loop's idea of "current time".
368
369Note that updating the time I<might> cause some events to be handled.
370
299=back 371=back
300 372
301=head2 SIGNAL WATCHERS 373=head2 SIGNAL WATCHERS
302 374
303You can watch for signals using a signal watcher, C<signal> is the signal 375You can watch for signals using a signal watcher, C<signal> is the signal
304I<name> without any C<SIG> prefix, C<cb> is the Perl callback to 376I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
305be invoked whenever a signal occurs. 377callback to be invoked whenever a signal occurs.
306 378
307Although the callback might get passed parameters, their value and 379Although the callback might get passed parameters, their value and
308presence is undefined and you cannot rely on them. Portable AnyEvent 380presence is undefined and you cannot rely on them. Portable AnyEvent
309callbacks cannot use arguments passed to signal watcher callbacks. 381callbacks cannot use arguments passed to signal watcher callbacks.
310 382
326=head2 CHILD PROCESS WATCHERS 398=head2 CHILD PROCESS WATCHERS
327 399
328You can also watch on a child process exit and catch its exit status. 400You can also watch on a child process exit and catch its exit status.
329 401
330The child process is specified by the C<pid> argument (if set to C<0>, it 402The child process is specified by the C<pid> argument (if set to C<0>, it
331watches for any child process exit). The watcher will trigger as often 403watches for any child process exit). The watcher will triggered only when
332as status change for the child are received. This works by installing a 404the child process has finished and an exit status is available, not on
333signal handler for C<SIGCHLD>. The callback will be called with the pid 405any trace events (stopped/continued).
334and exit status (as returned by waitpid), so unlike other watcher types, 406
335you I<can> rely on child watcher callback arguments. 407The callback will be called with the pid and exit status (as returned by
408waitpid), so unlike other watcher types, you I<can> rely on child watcher
409callback arguments.
410
411This watcher type works by installing a signal handler for C<SIGCHLD>,
412and since it cannot be shared, nothing else should use SIGCHLD or reap
413random child processes (waiting for specific child processes, e.g. inside
414C<system>, is just fine).
336 415
337There is a slight catch to child watchers, however: you usually start them 416There is a slight catch to child watchers, however: you usually start them
338I<after> the child process was created, and this means the process could 417I<after> the child process was created, and this means the process could
339have exited already (and no SIGCHLD will be sent anymore). 418have exited already (and no SIGCHLD will be sent anymore).
340 419
341Not all event models handle this correctly (POE doesn't), but even for 420Not all event models handle this correctly (neither POE nor IO::Async do,
421see their AnyEvent::Impl manpages for details), but even for event models
342event models that I<do> handle this correctly, they usually need to be 422that I<do> handle this correctly, they usually need to be loaded before
343loaded before the process exits (i.e. before you fork in the first place). 423the process exits (i.e. before you fork in the first place). AnyEvent's
424pure perl event loop handles all cases correctly regardless of when you
425start the watcher.
344 426
345This means you cannot create a child watcher as the very first thing in an 427This means you cannot create a child watcher as the very first
346AnyEvent program, you I<have> to create at least one watcher before you 428thing in an AnyEvent program, you I<have> to create at least one
347C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 429watcher before you C<fork> the child (alternatively, you can call
430C<AnyEvent::detect>).
348 431
349Example: fork a process and wait for it 432Example: fork a process and wait for it
350 433
351 my $done = AnyEvent->condvar; 434 my $done = AnyEvent->condvar;
352 435
353 my $pid = fork or exit 5; 436 my $pid = fork or exit 5;
354 437
355 my $w = AnyEvent->child ( 438 my $w = AnyEvent->child (
356 pid => $pid, 439 pid => $pid,
357 cb => sub { 440 cb => sub {
358 my ($pid, $status) = @_; 441 my ($pid, $status) = @_;
359 warn "pid $pid exited with status $status"; 442 warn "pid $pid exited with status $status";
360 $done->send; 443 $done->send;
361 }, 444 },
362 ); 445 );
363 446
364 # do something else, then wait for process exit 447 # do something else, then wait for process exit
365 $done->recv; 448 $done->recv;
449
450=head2 IDLE WATCHERS
451
452Sometimes there is a need to do something, but it is not so important
453to do it instantly, but only when there is nothing better to do. This
454"nothing better to do" is usually defined to be "no other events need
455attention by the event loop".
456
457Idle watchers ideally get invoked when the event loop has nothing
458better to do, just before it would block the process to wait for new
459events. Instead of blocking, the idle watcher is invoked.
460
461Most event loops unfortunately do not really support idle watchers (only
462EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
463will simply call the callback "from time to time".
464
465Example: read lines from STDIN, but only process them when the
466program is otherwise idle:
467
468 my @lines; # read data
469 my $idle_w;
470 my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
471 push @lines, scalar <STDIN>;
472
473 # start an idle watcher, if not already done
474 $idle_w ||= AnyEvent->idle (cb => sub {
475 # handle only one line, when there are lines left
476 if (my $line = shift @lines) {
477 print "handled when idle: $line";
478 } else {
479 # otherwise disable the idle watcher again
480 undef $idle_w;
481 }
482 });
483 });
366 484
367=head2 CONDITION VARIABLES 485=head2 CONDITION VARIABLES
368 486
369If you are familiar with some event loops you will know that all of them 487If you are familiar with some event loops you will know that all of them
370require you to run some blocking "loop", "run" or similar function that 488require you to run some blocking "loop", "run" or similar function that
376The instrument to do that is called a "condition variable", so called 494The instrument to do that is called a "condition variable", so called
377because they represent a condition that must become true. 495because they represent a condition that must become true.
378 496
379Condition variables can be created by calling the C<< AnyEvent->condvar 497Condition variables can be created by calling the C<< AnyEvent->condvar
380>> method, usually without arguments. The only argument pair allowed is 498>> method, usually without arguments. The only argument pair allowed is
499
381C<cb>, which specifies a callback to be called when the condition variable 500C<cb>, which specifies a callback to be called when the condition variable
382becomes true. 501becomes true, with the condition variable as the first argument (but not
502the results).
383 503
384After creation, the condition variable is "false" until it becomes "true" 504After creation, the condition variable is "false" until it becomes "true"
385by calling the C<send> method (or calling the condition variable as if it 505by calling the C<send> method (or calling the condition variable as if it
386were a callback, read about the caveats in the description for the C<< 506were a callback, read about the caveats in the description for the C<<
387->send >> method). 507->send >> method).
443 563
444 my $done = AnyEvent->condvar; 564 my $done = AnyEvent->condvar;
445 my $delay = AnyEvent->timer (after => 5, cb => $done); 565 my $delay = AnyEvent->timer (after => 5, cb => $done);
446 $done->recv; 566 $done->recv;
447 567
568Example: Imagine an API that returns a condvar and doesn't support
569callbacks. This is how you make a synchronous call, for example from
570the main program:
571
572 use AnyEvent::CouchDB;
573
574 ...
575
576 my @info = $couchdb->info->recv;
577
578And this is how you would just ste a callback to be called whenever the
579results are available:
580
581 $couchdb->info->cb (sub {
582 my @info = $_[0]->recv;
583 });
584
448=head3 METHODS FOR PRODUCERS 585=head3 METHODS FOR PRODUCERS
449 586
450These methods should only be used by the producing side, i.e. the 587These methods should only be used by the producing side, i.e. the
451code/module that eventually sends the signal. Note that it is also 588code/module that eventually sends the signal. Note that it is also
452the producer side which creates the condvar in most cases, but it isn't 589the producer side which creates the condvar in most cases, but it isn't
485 622
486=item $cv->begin ([group callback]) 623=item $cv->begin ([group callback])
487 624
488=item $cv->end 625=item $cv->end
489 626
490These two methods are EXPERIMENTAL and MIGHT CHANGE.
491
492These two methods can be used to combine many transactions/events into 627These two methods can be used to combine many transactions/events into
493one. For example, a function that pings many hosts in parallel might want 628one. For example, a function that pings many hosts in parallel might want
494to use a condition variable for the whole process. 629to use a condition variable for the whole process.
495 630
496Every call to C<< ->begin >> will increment a counter, and every call to 631Every call to C<< ->begin >> will increment a counter, and every call to
497C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 632C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
498>>, the (last) callback passed to C<begin> will be executed. That callback 633>>, the (last) callback passed to C<begin> will be executed. That callback
499is I<supposed> to call C<< ->send >>, but that is not required. If no 634is I<supposed> to call C<< ->send >>, but that is not required. If no
500callback was set, C<send> will be called without any arguments. 635callback was set, C<send> will be called without any arguments.
501 636
502Let's clarify this with the ping example: 637You can think of C<< $cv->send >> giving you an OR condition (one call
638sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
639condition (all C<begin> calls must be C<end>'ed before the condvar sends).
640
641Let's start with a simple example: you have two I/O watchers (for example,
642STDOUT and STDERR for a program), and you want to wait for both streams to
643close before activating a condvar:
644
645 my $cv = AnyEvent->condvar;
646
647 $cv->begin; # first watcher
648 my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
649 defined sysread $fh1, my $buf, 4096
650 or $cv->end;
651 });
652
653 $cv->begin; # second watcher
654 my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
655 defined sysread $fh2, my $buf, 4096
656 or $cv->end;
657 });
658
659 $cv->recv;
660
661This works because for every event source (EOF on file handle), there is
662one call to C<begin>, so the condvar waits for all calls to C<end> before
663sending.
664
665The ping example mentioned above is slightly more complicated, as the
666there are results to be passwd back, and the number of tasks that are
667begung can potentially be zero:
503 668
504 my $cv = AnyEvent->condvar; 669 my $cv = AnyEvent->condvar;
505 670
506 my %result; 671 my %result;
507 $cv->begin (sub { $cv->send (\%result) }); 672 $cv->begin (sub { $cv->send (\%result) });
527loop, which serves two important purposes: first, it sets the callback 692loop, which serves two important purposes: first, it sets the callback
528to be called once the counter reaches C<0>, and second, it ensures that 693to be called once the counter reaches C<0>, and second, it ensures that
529C<send> is called even when C<no> hosts are being pinged (the loop 694C<send> is called even when C<no> hosts are being pinged (the loop
530doesn't execute once). 695doesn't execute once).
531 696
532This is the general pattern when you "fan out" into multiple subrequests: 697This is the general pattern when you "fan out" into multiple (but
533use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 698potentially none) subrequests: use an outer C<begin>/C<end> pair to set
534is called at least once, and then, for each subrequest you start, call 699the callback and ensure C<end> is called at least once, and then, for each
535C<begin> and for each subrequest you finish, call C<end>. 700subrequest you start, call C<begin> and for each subrequest you finish,
701call C<end>.
536 702
537=back 703=back
538 704
539=head3 METHODS FOR CONSUMERS 705=head3 METHODS FOR CONSUMERS
540 706
585=item $bool = $cv->ready 751=item $bool = $cv->ready
586 752
587Returns true when the condition is "true", i.e. whether C<send> or 753Returns true when the condition is "true", i.e. whether C<send> or
588C<croak> have been called. 754C<croak> have been called.
589 755
590=item $cb = $cv->cb ([new callback]) 756=item $cb = $cv->cb ($cb->($cv))
591 757
592This is a mutator function that returns the callback set and optionally 758This is a mutator function that returns the callback set and optionally
593replaces it before doing so. 759replaces it before doing so.
594 760
595The callback will be called when the condition becomes "true", i.e. when 761The callback will be called when the condition becomes "true", i.e. when
596C<send> or C<croak> are called. Calling C<recv> inside the callback 762C<send> or C<croak> are called, with the only argument being the condition
597or at any later time is guaranteed not to block. 763variable itself. Calling C<recv> inside the callback or at any later time
764is guaranteed not to block.
598 765
599=back 766=back
600 767
601=head1 GLOBAL VARIABLES AND FUNCTIONS 768=head1 GLOBAL VARIABLES AND FUNCTIONS
602 769
619 AnyEvent::Impl::Tk based on Tk, very bad choice. 786 AnyEvent::Impl::Tk based on Tk, very bad choice.
620 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 787 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 788 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622 AnyEvent::Impl::POE based on POE, not generic enough for full support. 789 AnyEvent::Impl::POE based on POE, not generic enough for full support.
623 790
791 # warning, support for IO::Async is only partial, as it is too broken
792 # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
793 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
794
624There is no support for WxWidgets, as WxWidgets has no support for 795There is no support for WxWidgets, as WxWidgets has no support for
625watching file handles. However, you can use WxWidgets through the 796watching file handles. However, you can use WxWidgets through the
626POE Adaptor, as POE has a Wx backend that simply polls 20 times per 797POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627second, which was considered to be too horrible to even consider for 798second, which was considered to be too horrible to even consider for
628AnyEvent. Likewise, other POE backends can be used by AnyEvent by using 799AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
731=item L<AnyEvent::Util> 902=item L<AnyEvent::Util>
732 903
733Contains various utility functions that replace often-used but blocking 904Contains various utility functions that replace often-used but blocking
734functions such as C<inet_aton> by event-/callback-based versions. 905functions such as C<inet_aton> by event-/callback-based versions.
735 906
736=item L<AnyEvent::Handle>
737
738Provide read and write buffers and manages watchers for reads and writes.
739
740=item L<AnyEvent::Socket> 907=item L<AnyEvent::Socket>
741 908
742Provides various utility functions for (internet protocol) sockets, 909Provides various utility functions for (internet protocol) sockets,
743addresses and name resolution. Also functions to create non-blocking tcp 910addresses and name resolution. Also functions to create non-blocking tcp
744connections or tcp servers, with IPv6 and SRV record support and more. 911connections or tcp servers, with IPv6 and SRV record support and more.
745 912
913=item L<AnyEvent::Handle>
914
915Provide read and write buffers, manages watchers for reads and writes,
916supports raw and formatted I/O, I/O queued and fully transparent and
917non-blocking SSL/TLS.
918
746=item L<AnyEvent::DNS> 919=item L<AnyEvent::DNS>
747 920
748Provides rich asynchronous DNS resolver capabilities. 921Provides rich asynchronous DNS resolver capabilities.
749 922
923=item L<AnyEvent::HTTP>
924
925A simple-to-use HTTP library that is capable of making a lot of concurrent
926HTTP requests.
927
750=item L<AnyEvent::HTTPD> 928=item L<AnyEvent::HTTPD>
751 929
752Provides a simple web application server framework. 930Provides a simple web application server framework.
753 931
754=item L<AnyEvent::FastPing> 932=item L<AnyEvent::FastPing>
755 933
756The fastest ping in the west. 934The fastest ping in the west.
757 935
936=item L<AnyEvent::DBI>
937
938Executes L<DBI> requests asynchronously in a proxy process.
939
940=item L<AnyEvent::AIO>
941
942Truly asynchronous I/O, should be in the toolbox of every event
943programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
944together.
945
946=item L<AnyEvent::BDB>
947
948Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
949L<BDB> and AnyEvent together.
950
951=item L<AnyEvent::GPSD>
952
953A non-blocking interface to gpsd, a daemon delivering GPS information.
954
955=item L<AnyEvent::IGS>
956
957A non-blocking interface to the Internet Go Server protocol (used by
958L<App::IGS>).
959
758=item L<Net::IRC3> 960=item L<AnyEvent::IRC>
759 961
760AnyEvent based IRC client module family. 962AnyEvent based IRC client module family (replacing the older Net::IRC3).
761 963
762=item L<Net::XMPP2> 964=item L<Net::XMPP2>
763 965
764AnyEvent based XMPP (Jabber protocol) module family. 966AnyEvent based XMPP (Jabber protocol) module family.
765 967
774 976
775=item L<Coro> 977=item L<Coro>
776 978
777Has special support for AnyEvent via L<Coro::AnyEvent>. 979Has special support for AnyEvent via L<Coro::AnyEvent>.
778 980
779=item L<AnyEvent::AIO>, L<IO::AIO>
780
781Truly asynchronous I/O, should be in the toolbox of every event
782programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
783together.
784
785=item L<AnyEvent::BDB>, L<BDB>
786
787Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
788IO::AIO and AnyEvent together.
789
790=item L<IO::Lambda> 981=item L<IO::Lambda>
791 982
792The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 983The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793 984
794=back 985=back
796=cut 987=cut
797 988
798package AnyEvent; 989package AnyEvent;
799 990
800no warnings; 991no warnings;
801use strict; 992use strict qw(vars subs);
802 993
803use Carp; 994use Carp;
804 995
805our $VERSION = '4.05'; 996our $VERSION = 4.8;
806our $MODEL; 997our $MODEL;
807 998
808our $AUTOLOAD; 999our $AUTOLOAD;
809our @ISA; 1000our @ISA;
810 1001
811our @REGISTRY; 1002our @REGISTRY;
812 1003
813our $WIN32; 1004our $WIN32;
814 1005
815BEGIN { 1006BEGIN {
816 my $win32 = ! ! ($^O =~ /mswin32/i); 1007 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
817 eval "sub WIN32(){ $win32 }"; 1008 eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
1009
1010 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1011 if ${^TAINT};
818} 1012}
819 1013
820our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1014our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
821 1015
822our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 1016our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
840 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1034 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
841 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 1035 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1036 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843 [Wx:: => AnyEvent::Impl::POE::], 1037 [Wx:: => AnyEvent::Impl::POE::],
844 [Prima:: => AnyEvent::Impl::POE::], 1038 [Prima:: => AnyEvent::Impl::POE::],
1039 # IO::Async is just too broken - we would need workaorunds for its
1040 # byzantine signal and broken child handling, among others.
1041 # IO::Async is rather hard to detect, as it doesn't have any
1042 # obvious default class.
1043# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1044# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1045# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
845); 1046);
846 1047
847our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); 1048our %method = map +($_ => 1),
1049 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
848 1050
849our @post_detect; 1051our @post_detect;
850 1052
851sub post_detect(&) { 1053sub post_detect(&) {
852 my ($cb) = @_; 1054 my ($cb) = @_;
857 1 1059 1
858 } else { 1060 } else {
859 push @post_detect, $cb; 1061 push @post_detect, $cb;
860 1062
861 defined wantarray 1063 defined wantarray
862 ? bless \$cb, "AnyEvent::Util::PostDetect" 1064 ? bless \$cb, "AnyEvent::Util::postdetect"
863 : () 1065 : ()
864 } 1066 }
865} 1067}
866 1068
867sub AnyEvent::Util::PostDetect::DESTROY { 1069sub AnyEvent::Util::postdetect::DESTROY {
868 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1070 @post_detect = grep $_ != ${$_[0]}, @post_detect;
869} 1071}
870 1072
871sub detect() { 1073sub detect() {
872 unless ($MODEL) { 1074 unless ($MODEL) {
909 last; 1111 last;
910 } 1112 }
911 } 1113 }
912 1114
913 $MODEL 1115 $MODEL
914 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 1116 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
915 } 1117 }
916 } 1118 }
917 1119
1120 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1121
918 unshift @ISA, $MODEL; 1122 unshift @ISA, $MODEL;
919 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 1123
1124 require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
920 1125
921 (shift @post_detect)->() while @post_detect; 1126 (shift @post_detect)->() while @post_detect;
922 } 1127 }
923 1128
924 $MODEL 1129 $MODEL
934 1139
935 my $class = shift; 1140 my $class = shift;
936 $class->$func (@_); 1141 $class->$func (@_);
937} 1142}
938 1143
1144# utility function to dup a filehandle. this is used by many backends
1145# to support binding more than one watcher per filehandle (they usually
1146# allow only one watcher per fd, so we dup it to get a different one).
1147sub _dupfh($$;$$) {
1148 my ($poll, $fh, $r, $w) = @_;
1149
1150 # cygwin requires the fh mode to be matching, unix doesn't
1151 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1152 : $poll eq "w" ? ($w, ">")
1153 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1154
1155 open my $fh2, "$mode&" . fileno $fh
1156 or die "cannot dup() filehandle: $!,";
1157
1158 # we assume CLOEXEC is already set by perl in all important cases
1159
1160 ($fh2, $rw)
1161}
1162
939package AnyEvent::Base; 1163package AnyEvent::Base;
940 1164
941# default implementation for now and time 1165# default implementations for many methods
942 1166
943use Time::HiRes (); 1167BEGIN {
1168 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1169 *_time = \&Time::HiRes::time;
1170 # if (eval "use POSIX (); (POSIX::times())...
1171 } else {
1172 *_time = sub { time }; # epic fail
1173 }
1174}
944 1175
945sub time { Time::HiRes::time } 1176sub time { _time }
946sub now { Time::HiRes::time } 1177sub now { _time }
1178sub now_update { }
947 1179
948# default implementation for ->condvar 1180# default implementation for ->condvar
949 1181
950sub condvar { 1182sub condvar {
951 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1183 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
952} 1184}
953 1185
954# default implementation for ->signal 1186# default implementation for ->signal
955 1187
956our %SIG_CB; 1188our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1189
1190sub _signal_exec {
1191 sysread $SIGPIPE_R, my $dummy, 4;
1192
1193 while (%SIG_EV) {
1194 for (keys %SIG_EV) {
1195 delete $SIG_EV{$_};
1196 $_->() for values %{ $SIG_CB{$_} || {} };
1197 }
1198 }
1199}
957 1200
958sub signal { 1201sub signal {
959 my (undef, %arg) = @_; 1202 my (undef, %arg) = @_;
960 1203
1204 unless ($SIGPIPE_R) {
1205 require Fcntl;
1206
1207 if (AnyEvent::WIN32) {
1208 require AnyEvent::Util;
1209
1210 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1211 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1212 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1213 } else {
1214 pipe $SIGPIPE_R, $SIGPIPE_W;
1215 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1216 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1217
1218 # not strictly required, as $^F is normally 2, but let's make sure...
1219 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1220 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1221 }
1222
1223 $SIGPIPE_R
1224 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1225
1226 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1227 }
1228
961 my $signal = uc $arg{signal} 1229 my $signal = uc $arg{signal}
962 or Carp::croak "required option 'signal' is missing"; 1230 or Carp::croak "required option 'signal' is missing";
963 1231
964 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1232 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
965 $SIG{$signal} ||= sub { 1233 $SIG{$signal} ||= sub {
966 $_->() for values %{ $SIG_CB{$signal} || {} }; 1234 local $!;
1235 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1236 undef $SIG_EV{$signal};
967 }; 1237 };
968 1238
969 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1239 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
970} 1240}
971 1241
972sub AnyEvent::Base::Signal::DESTROY { 1242sub AnyEvent::Base::signal::DESTROY {
973 my ($signal, $cb) = @{$_[0]}; 1243 my ($signal, $cb) = @{$_[0]};
974 1244
975 delete $SIG_CB{$signal}{$cb}; 1245 delete $SIG_CB{$signal}{$cb};
976 1246
1247 # delete doesn't work with older perls - they then
1248 # print weird messages, or just unconditionally exit
1249 # instead of getting the default action.
977 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; 1250 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
978} 1251}
979 1252
980# default implementation for ->child 1253# default implementation for ->child
981 1254
982our %PID_CB; 1255our %PID_CB;
983our $CHLD_W; 1256our $CHLD_W;
984our $CHLD_DELAY_W; 1257our $CHLD_DELAY_W;
985our $PID_IDLE;
986our $WNOHANG; 1258our $WNOHANG;
987 1259
988sub _child_wait { 1260sub _sigchld {
989 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1261 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
990 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1262 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
991 (values %{ $PID_CB{0} || {} }); 1263 (values %{ $PID_CB{0} || {} });
992 } 1264 }
993
994 undef $PID_IDLE;
995}
996
997sub _sigchld {
998 # make sure we deliver these changes "synchronous" with the event loop.
999 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1000 undef $CHLD_DELAY_W;
1001 &_child_wait;
1002 });
1003} 1265}
1004 1266
1005sub child { 1267sub child {
1006 my (undef, %arg) = @_; 1268 my (undef, %arg) = @_;
1007 1269
1008 defined (my $pid = $arg{pid} + 0) 1270 defined (my $pid = $arg{pid} + 0)
1009 or Carp::croak "required option 'pid' is missing"; 1271 or Carp::croak "required option 'pid' is missing";
1010 1272
1011 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1273 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1012 1274
1013 unless ($WNOHANG) {
1014 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1275 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015 }
1016 1276
1017 unless ($CHLD_W) { 1277 unless ($CHLD_W) {
1018 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1278 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1019 # child could be a zombie already, so make at least one round 1279 # child could be a zombie already, so make at least one round
1020 &_sigchld; 1280 &_sigchld;
1021 } 1281 }
1022 1282
1023 bless [$pid, $arg{cb}], "AnyEvent::Base::Child" 1283 bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1024} 1284}
1025 1285
1026sub AnyEvent::Base::Child::DESTROY { 1286sub AnyEvent::Base::child::DESTROY {
1027 my ($pid, $cb) = @{$_[0]}; 1287 my ($pid, $cb) = @{$_[0]};
1028 1288
1029 delete $PID_CB{$pid}{$cb}; 1289 delete $PID_CB{$pid}{$cb};
1030 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1290 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031 1291
1032 undef $CHLD_W unless keys %PID_CB; 1292 undef $CHLD_W unless keys %PID_CB;
1293}
1294
1295# idle emulation is done by simply using a timer, regardless
1296# of whether the process is idle or not, and not letting
1297# the callback use more than 50% of the time.
1298sub idle {
1299 my (undef, %arg) = @_;
1300
1301 my ($cb, $w, $rcb) = $arg{cb};
1302
1303 $rcb = sub {
1304 if ($cb) {
1305 $w = _time;
1306 &$cb;
1307 $w = _time - $w;
1308
1309 # never use more then 50% of the time for the idle watcher,
1310 # within some limits
1311 $w = 0.0001 if $w < 0.0001;
1312 $w = 5 if $w > 5;
1313
1314 $w = AnyEvent->timer (after => $w, cb => $rcb);
1315 } else {
1316 # clean up...
1317 undef $w;
1318 undef $rcb;
1319 }
1320 };
1321
1322 $w = AnyEvent->timer (after => 0.05, cb => $rcb);
1323
1324 bless \\$cb, "AnyEvent::Base::idle"
1325}
1326
1327sub AnyEvent::Base::idle::DESTROY {
1328 undef $${$_[0]};
1033} 1329}
1034 1330
1035package AnyEvent::CondVar; 1331package AnyEvent::CondVar;
1036 1332
1037our @ISA = AnyEvent::CondVar::Base::; 1333our @ISA = AnyEvent::CondVar::Base::;
1089} 1385}
1090 1386
1091# undocumented/compatibility with pre-3.4 1387# undocumented/compatibility with pre-3.4
1092*broadcast = \&send; 1388*broadcast = \&send;
1093*wait = \&_wait; 1389*wait = \&_wait;
1390
1391=head1 ERROR AND EXCEPTION HANDLING
1392
1393In general, AnyEvent does not do any error handling - it relies on the
1394caller to do that if required. The L<AnyEvent::Strict> module (see also
1395the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1396checking of all AnyEvent methods, however, which is highly useful during
1397development.
1398
1399As for exception handling (i.e. runtime errors and exceptions thrown while
1400executing a callback), this is not only highly event-loop specific, but
1401also not in any way wrapped by this module, as this is the job of the main
1402program.
1403
1404The pure perl event loop simply re-throws the exception (usually
1405within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1406$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1407so on.
1408
1409=head1 ENVIRONMENT VARIABLES
1410
1411The following environment variables are used by this module or its
1412submodules.
1413
1414Note that AnyEvent will remove I<all> environment variables starting with
1415C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
1416enabled.
1417
1418=over 4
1419
1420=item C<PERL_ANYEVENT_VERBOSE>
1421
1422By default, AnyEvent will be completely silent except in fatal
1423conditions. You can set this environment variable to make AnyEvent more
1424talkative.
1425
1426When set to C<1> or higher, causes AnyEvent to warn about unexpected
1427conditions, such as not being able to load the event model specified by
1428C<PERL_ANYEVENT_MODEL>.
1429
1430When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1431model it chooses.
1432
1433=item C<PERL_ANYEVENT_STRICT>
1434
1435AnyEvent does not do much argument checking by default, as thorough
1436argument checking is very costly. Setting this variable to a true value
1437will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1438check the arguments passed to most method calls. If it finds any problems,
1439it will croak.
1440
1441In other words, enables "strict" mode.
1442
1443Unlike C<use strict>, it is definitely recommended to keep it off in
1444production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1445developing programs can be very useful, however.
1446
1447=item C<PERL_ANYEVENT_MODEL>
1448
1449This can be used to specify the event model to be used by AnyEvent, before
1450auto detection and -probing kicks in. It must be a string consisting
1451entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1452and the resulting module name is loaded and if the load was successful,
1453used as event model. If it fails to load AnyEvent will proceed with
1454auto detection and -probing.
1455
1456This functionality might change in future versions.
1457
1458For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1459could start your program like this:
1460
1461 PERL_ANYEVENT_MODEL=Perl perl ...
1462
1463=item C<PERL_ANYEVENT_PROTOCOLS>
1464
1465Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1466for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1467of auto probing).
1468
1469Must be set to a comma-separated list of protocols or address families,
1470current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1471used, and preference will be given to protocols mentioned earlier in the
1472list.
1473
1474This variable can effectively be used for denial-of-service attacks
1475against local programs (e.g. when setuid), although the impact is likely
1476small, as the program has to handle conenction and other failures anyways.
1477
1478Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1479but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1480- only support IPv4, never try to resolve or contact IPv6
1481addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1482IPv6, but prefer IPv6 over IPv4.
1483
1484=item C<PERL_ANYEVENT_EDNS0>
1485
1486Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1487for DNS. This extension is generally useful to reduce DNS traffic, but
1488some (broken) firewalls drop such DNS packets, which is why it is off by
1489default.
1490
1491Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1492EDNS0 in its DNS requests.
1493
1494=item C<PERL_ANYEVENT_MAX_FORKS>
1495
1496The maximum number of child processes that C<AnyEvent::Util::fork_call>
1497will create in parallel.
1498
1499=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
1500
1501The default value for the C<max_outstanding> parameter for the default DNS
1502resolver - this is the maximum number of parallel DNS requests that are
1503sent to the DNS server.
1504
1505=item C<PERL_ANYEVENT_RESOLV_CONF>
1506
1507The file to use instead of F</etc/resolv.conf> (or OS-specific
1508configuration) in the default resolver. When set to the empty string, no
1509default config will be used.
1510
1511=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
1512
1513When neither C<ca_file> nor C<ca_path> was specified during
1514L<AnyEvent::TLS> context creation, and either of these environment
1515variables exist, they will be used to specify CA certificate locations
1516instead of a system-dependent default.
1517
1518=back
1094 1519
1095=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1520=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096 1521
1097This is an advanced topic that you do not normally need to use AnyEvent in 1522This is an advanced topic that you do not normally need to use AnyEvent in
1098a module. This section is only of use to event loop authors who want to 1523a module. This section is only of use to event loop authors who want to
1132 1557
1133I<rxvt-unicode> also cheats a bit by not providing blocking access to 1558I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134condition variables: code blocking while waiting for a condition will 1559condition variables: code blocking while waiting for a condition will
1135C<die>. This still works with most modules/usages, and blocking calls must 1560C<die>. This still works with most modules/usages, and blocking calls must
1136not be done in an interactive application, so it makes sense. 1561not be done in an interactive application, so it makes sense.
1137
1138=head1 ENVIRONMENT VARIABLES
1139
1140The following environment variables are used by this module:
1141
1142=over 4
1143
1144=item C<PERL_ANYEVENT_VERBOSE>
1145
1146By default, AnyEvent will be completely silent except in fatal
1147conditions. You can set this environment variable to make AnyEvent more
1148talkative.
1149
1150When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151conditions, such as not being able to load the event model specified by
1152C<PERL_ANYEVENT_MODEL>.
1153
1154When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155model it chooses.
1156
1157=item C<PERL_ANYEVENT_MODEL>
1158
1159This can be used to specify the event model to be used by AnyEvent, before
1160auto detection and -probing kicks in. It must be a string consisting
1161entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162and the resulting module name is loaded and if the load was successful,
1163used as event model. If it fails to load AnyEvent will proceed with
1164auto detection and -probing.
1165
1166This functionality might change in future versions.
1167
1168For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169could start your program like this:
1170
1171 PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177of auto probing).
1178
1179Must be set to a comma-separated list of protocols or address families,
1180current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181used, and preference will be given to protocols mentioned earlier in the
1182list.
1183
1184This variable can effectively be used for denial-of-service attacks
1185against local programs (e.g. when setuid), although the impact is likely
1186small, as the program has to handle connection errors already-
1187
1188Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190- only support IPv4, never try to resolve or contact IPv6
1191addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192IPv6, but prefer IPv6 over IPv4.
1193
1194=item C<PERL_ANYEVENT_EDNS0>
1195
1196Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197for DNS. This extension is generally useful to reduce DNS traffic, but
1198some (broken) firewalls drop such DNS packets, which is why it is off by
1199default.
1200
1201Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202EDNS0 in its DNS requests.
1203
1204=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207will create in parallel.
1208
1209=back
1210 1562
1211=head1 EXAMPLE PROGRAM 1563=head1 EXAMPLE PROGRAM
1212 1564
1213The following program uses an I/O watcher to read data from STDIN, a timer 1565The following program uses an I/O watcher to read data from STDIN, a timer
1214to display a message once per second, and a condition variable to quit the 1566to display a message once per second, and a condition variable to quit the
1408watcher. 1760watcher.
1409 1761
1410=head3 Results 1762=head3 Results
1411 1763
1412 name watchers bytes create invoke destroy comment 1764 name watchers bytes create invoke destroy comment
1413 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1765 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1414 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1766 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1415 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1767 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1416 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1768 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1417 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1769 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1418 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1770 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1771 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
1772 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1419 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1773 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1420 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1774 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1421 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1775 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1422 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1776 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1423 1777
1424=head3 Discussion 1778=head3 Discussion
1425 1779
1426The benchmark does I<not> measure scalability of the event loop very 1780The benchmark does I<not> measure scalability of the event loop very
1427well. For example, a select-based event loop (such as the pure perl one) 1781well. For example, a select-based event loop (such as the pure perl one)
1452performance becomes really bad with lots of file descriptors (and few of 1806performance becomes really bad with lots of file descriptors (and few of
1453them active), of course, but this was not subject of this benchmark. 1807them active), of course, but this was not subject of this benchmark.
1454 1808
1455The C<Event> module has a relatively high setup and callback invocation 1809The C<Event> module has a relatively high setup and callback invocation
1456cost, but overall scores in on the third place. 1810cost, but overall scores in on the third place.
1811
1812C<IO::Async> performs admirably well, about on par with C<Event>, even
1813when using its pure perl backend.
1457 1814
1458C<Glib>'s memory usage is quite a bit higher, but it features a 1815C<Glib>'s memory usage is quite a bit higher, but it features a
1459faster callback invocation and overall ends up in the same class as 1816faster callback invocation and overall ends up in the same class as
1460C<Event>. However, Glib scales extremely badly, doubling the number of 1817C<Event>. However, Glib scales extremely badly, doubling the number of
1461watchers increases the processing time by more than a factor of four, 1818watchers increases the processing time by more than a factor of four,
1539it to another server. This includes deleting the old timeout and creating 1896it to another server. This includes deleting the old timeout and creating
1540a new one that moves the timeout into the future. 1897a new one that moves the timeout into the future.
1541 1898
1542=head3 Results 1899=head3 Results
1543 1900
1544 name sockets create request 1901 name sockets create request
1545 EV 20000 69.01 11.16 1902 EV 20000 69.01 11.16
1546 Perl 20000 73.32 35.87 1903 Perl 20000 73.32 35.87
1904 IOAsync 20000 157.00 98.14 epoll
1905 IOAsync 20000 159.31 616.06 poll
1547 Event 20000 212.62 257.32 1906 Event 20000 212.62 257.32
1548 Glib 20000 651.16 1896.30 1907 Glib 20000 651.16 1896.30
1549 POE 20000 349.67 12317.24 uses POE::Loop::Event 1908 POE 20000 349.67 12317.24 uses POE::Loop::Event
1550 1909
1551=head3 Discussion 1910=head3 Discussion
1552 1911
1553This benchmark I<does> measure scalability and overall performance of the 1912This benchmark I<does> measure scalability and overall performance of the
1554particular event loop. 1913particular event loop.
1556EV is again fastest. Since it is using epoll on my system, the setup time 1915EV is again fastest. Since it is using epoll on my system, the setup time
1557is relatively high, though. 1916is relatively high, though.
1558 1917
1559Perl surprisingly comes second. It is much faster than the C-based event 1918Perl surprisingly comes second. It is much faster than the C-based event
1560loops Event and Glib. 1919loops Event and Glib.
1920
1921IO::Async performs very well when using its epoll backend, and still quite
1922good compared to Glib when using its pure perl backend.
1561 1923
1562Event suffers from high setup time as well (look at its code and you will 1924Event suffers from high setup time as well (look at its code and you will
1563understand why). Callback invocation also has a high overhead compared to 1925understand why). Callback invocation also has a high overhead compared to
1564the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event 1926the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565uses select or poll in basically all documented configurations. 1927uses select or poll in basically all documented configurations.
1628=item * C-based event loops perform very well with small number of 1990=item * C-based event loops perform very well with small number of
1629watchers, as the management overhead dominates. 1991watchers, as the management overhead dominates.
1630 1992
1631=back 1993=back
1632 1994
1995=head2 THE IO::Lambda BENCHMARK
1996
1997Recently I was told about the benchmark in the IO::Lambda manpage, which
1998could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1999simply compares IO::Lambda with POE, and IO::Lambda looks better (which
2000shouldn't come as a surprise to anybody). As such, the benchmark is
2001fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
2002very optimal. But how would AnyEvent compare when used without the extra
2003baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
2004
2005The benchmark itself creates an echo-server, and then, for 500 times,
2006connects to the echo server, sends a line, waits for the reply, and then
2007creates the next connection. This is a rather bad benchmark, as it doesn't
2008test the efficiency of the framework or much non-blocking I/O, but it is a
2009benchmark nevertheless.
2010
2011 name runtime
2012 Lambda/select 0.330 sec
2013 + optimized 0.122 sec
2014 Lambda/AnyEvent 0.327 sec
2015 + optimized 0.138 sec
2016 Raw sockets/select 0.077 sec
2017 POE/select, components 0.662 sec
2018 POE/select, raw sockets 0.226 sec
2019 POE/select, optimized 0.404 sec
2020
2021 AnyEvent/select/nb 0.085 sec
2022 AnyEvent/EV/nb 0.068 sec
2023 +state machine 0.134 sec
2024
2025The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
2026benchmarks actually make blocking connects and use 100% blocking I/O,
2027defeating the purpose of an event-based solution. All of the newly
2028written AnyEvent benchmarks use 100% non-blocking connects (using
2029AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
2030resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
2031generally require a lot more bookkeeping and event handling than blocking
2032connects (which involve a single syscall only).
2033
2034The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
2035offers similar expressive power as POE and IO::Lambda, using conventional
2036Perl syntax. This means that both the echo server and the client are 100%
2037non-blocking, further placing it at a disadvantage.
2038
2039As you can see, the AnyEvent + EV combination even beats the
2040hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2041backend easily beats IO::Lambda and POE.
2042
2043And even the 100% non-blocking version written using the high-level (and
2044slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
2045large margin, even though it does all of DNS, tcp-connect and socket I/O
2046in a non-blocking way.
2047
2048The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2049F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2050part of the IO::lambda distribution and were used without any changes.
2051
2052
2053=head1 SIGNALS
2054
2055AnyEvent currently installs handlers for these signals:
2056
2057=over 4
2058
2059=item SIGCHLD
2060
2061A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
2062emulation for event loops that do not support them natively. Also, some
2063event loops install a similar handler.
2064
2065If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
2066reset it to default, to avoid losing child exit statuses.
2067
2068=item SIGPIPE
2069
2070A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2071when AnyEvent gets loaded.
2072
2073The rationale for this is that AnyEvent users usually do not really depend
2074on SIGPIPE delivery (which is purely an optimisation for shell use, or
2075badly-written programs), but C<SIGPIPE> can cause spurious and rare
2076program exits as a lot of people do not expect C<SIGPIPE> when writing to
2077some random socket.
2078
2079The rationale for installing a no-op handler as opposed to ignoring it is
2080that this way, the handler will be restored to defaults on exec.
2081
2082Feel free to install your own handler, or reset it to defaults.
2083
2084=back
2085
2086=cut
2087
2088undef $SIG{CHLD}
2089 if $SIG{CHLD} eq 'IGNORE';
2090
2091$SIG{PIPE} = sub { }
2092 unless defined $SIG{PIPE};
1633 2093
1634=head1 FORK 2094=head1 FORK
1635 2095
1636Most event libraries are not fork-safe. The ones who are usually are 2096Most event libraries are not fork-safe. The ones who are usually are
1637because they rely on inefficient but fork-safe C<select> or C<poll> 2097because they rely on inefficient but fork-safe C<select> or C<poll>
1651specified in the variable. 2111specified in the variable.
1652 2112
1653You can make AnyEvent completely ignore this variable by deleting it 2113You can make AnyEvent completely ignore this variable by deleting it
1654before the first watcher gets created, e.g. with a C<BEGIN> block: 2114before the first watcher gets created, e.g. with a C<BEGIN> block:
1655 2115
1656 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 2116 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657 2117
1658 use AnyEvent; 2118 use AnyEvent;
1659 2119
1660Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 2120Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661be used to probe what backend is used and gain other information (which is 2121be used to probe what backend is used and gain other information (which is
1662probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 2122probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
2123$ENV{PERL_ANYEVENT_STRICT}.
2124
2125Note that AnyEvent will remove I<all> environment variables starting with
2126C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
2127enabled.
2128
2129
2130=head1 BUGS
2131
2132Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
2133to work around. If you suffer from memleaks, first upgrade to Perl 5.10
2134and check wether the leaks still show up. (Perl 5.10.0 has other annoying
2135memleaks, such as leaking on C<map> and C<grep> but it is usually not as
2136pronounced).
1663 2137
1664 2138
1665=head1 SEE ALSO 2139=head1 SEE ALSO
1666 2140
1667Utility functions: L<AnyEvent::Util>. 2141Utility functions: L<AnyEvent::Util>.
1684Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 2158Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1685 2159
1686 2160
1687=head1 AUTHOR 2161=head1 AUTHOR
1688 2162
1689 Marc Lehmann <schmorp@schmorp.de> 2163 Marc Lehmann <schmorp@schmorp.de>
1690 http://home.schmorp.de/ 2164 http://home.schmorp.de/
1691 2165
1692=cut 2166=cut
1693 2167
16941 21681
1695 2169

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines