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1=head1 NAME 1=head1 NAME
2 2
3Coro - the real perl threads 3Coro - the only real threads in perl
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use Coro; 7 use Coro;
8 8
26 $locked = 1; 26 $locked = 1;
27 $lock->up; 27 $lock->up;
28 28
29=head1 DESCRIPTION 29=head1 DESCRIPTION
30 30
31This module collection manages coroutines, that is, cooperative 31For a tutorial-style introduction, please read the L<Coro::Intro>
32threads. Coroutines are similar to kernel threads but don't (in general) 32manpage. This manpage mainly contains reference information.
33
34This module collection manages continuations in general, most often
35in the form of cooperative threads (also called coroutines in the
36documentation). They are similar to kernel threads but don't (in general)
33run in parallel at the same time even on SMP machines. The specific flavor 37run in parallel at the same time even on SMP machines. The specific flavor
34of coroutine used in this module also guarantees you that it will not 38of thread offered by this module also guarantees you that it will not
35switch between coroutines unless necessary, at easily-identified points 39switch between threads unless necessary, at easily-identified points in
36in your program, so locking and parallel access are rarely an issue, 40your program, so locking and parallel access are rarely an issue, making
37making coroutine programming much safer and easier than using other thread 41thread programming much safer and easier than using other thread models.
38models.
39 42
40Unlike the so-called "Perl threads" (which are not actually real threads 43Unlike the so-called "Perl threads" (which are not actually real threads
41but only the windows process emulation ported to unix), Coro provides a 44but only the windows process emulation ported to unix), Coro provides a
42full shared address space, which makes communication between coroutines 45full shared address space, which makes communication between threads
43very easy. And coroutines are fast, too: disabling the Windows process 46very easy. And threads are fast, too: disabling the Windows process
44emulation code in your perl and using Coro can easily result in a two to 47emulation code in your perl and using Coro can easily result in a two to
45four times speed increase for your programs. 48four times speed increase for your programs.
46 49
47Coro achieves that by supporting multiple running interpreters that share 50Coro achieves that by supporting multiple running interpreters that share
48data, which is especially useful to code pseudo-parallel processes and 51data, which is especially useful to code pseudo-parallel processes and
49for event-based programming, such as multiple HTTP-GET requests running 52for event-based programming, such as multiple HTTP-GET requests running
50concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro 53concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
51into an event-based environment. 54into an event-based environment.
52 55
53In this module, a coroutines is defined as "callchain + lexical variables 56In this module, a thread is defined as "callchain + lexical variables +
54+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own 57@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,
55callchain, its own set of lexicals and its own set of perls most important 58its own set of lexicals and its own set of perls most important global
56global variables (see L<Coro::State> for more configuration and background 59variables (see L<Coro::State> for more configuration and background info).
57info).
58 60
59See also the C<SEE ALSO> section at the end of this document - the Coro 61See also the C<SEE ALSO> section at the end of this document - the Coro
60module family is quite large. 62module family is quite large.
61 63
62=cut 64=cut
72 74
73our $idle; # idle handler 75our $idle; # idle handler
74our $main; # main coroutine 76our $main; # main coroutine
75our $current; # current coroutine 77our $current; # current coroutine
76 78
77our $VERSION = "5.0"; 79our $VERSION = 5.13;
78 80
79our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 81our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
80our %EXPORT_TAGS = ( 82our %EXPORT_TAGS = (
81 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 83 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
82); 84);
112sub current() { $current } # [DEPRECATED] 114sub current() { $current } # [DEPRECATED]
113 115
114=item $Coro::idle 116=item $Coro::idle
115 117
116This variable is mainly useful to integrate Coro into event loops. It is 118This variable is mainly useful to integrate Coro into event loops. It is
117usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is 119usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
118pretty low-level functionality. 120pretty low-level functionality.
119 121
120This variable stores a callback that is called whenever the scheduler 122This variable stores either a coroutine or a callback.
123
124If it is a callback, the it is called whenever the scheduler finds no
121finds no ready coroutines to run. The default implementation prints 125ready coroutines to run. The default implementation prints "FATAL:
122"FATAL: deadlock detected" and exits, because the program has no other way 126deadlock detected" and exits, because the program has no other way to
123to continue. 127continue.
124 128
129If it is a coroutine object, then this object will be readied (without
130invoking any ready hooks, however) when the scheduler finds no other ready
131coroutines to run.
132
125This hook is overwritten by modules such as C<Coro::Timer> and 133This hook is overwritten by modules such as C<Coro::EV> and
126C<Coro::AnyEvent> to wait on an external event that hopefully wake up a 134C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
127coroutine so the scheduler can run it. 135coroutine so the scheduler can run it.
128 136
129Note that the callback I<must not>, under any circumstances, block 137Note that the callback I<must not>, under any circumstances, block
130the current coroutine. Normally, this is achieved by having an "idle 138the current coroutine. Normally, this is achieved by having an "idle
131coroutine" that calls the event loop and then blocks again, and then 139coroutine" that calls the event loop and then blocks again, and then
132readying that coroutine in the idle handler. 140readying that coroutine in the idle handler, or by simply placing the idle
141coroutine in this variable.
133 142
134See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this 143See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
135technique. 144technique.
136 145
137Please note that if your callback recursively invokes perl (e.g. for event 146Please note that if your callback recursively invokes perl (e.g. for event
166 175
167=over 4 176=over 4
168 177
169=item async { ... } [@args...] 178=item async { ... } [@args...]
170 179
171Create a new coroutine and return it's coroutine object (usually 180Create a new coroutine and return its coroutine object (usually
172unused). The coroutine will be put into the ready queue, so 181unused). The coroutine will be put into the ready queue, so
173it will start running automatically on the next scheduler run. 182it will start running automatically on the next scheduler run.
174 183
175The first argument is a codeblock/closure that should be executed in the 184The first argument is a codeblock/closure that should be executed in the
176coroutine. When it returns argument returns the coroutine is automatically 185coroutine. When it returns argument returns the coroutine is automatically
306Terminates the current coroutine with the given status values (see L<cancel>). 315Terminates the current coroutine with the given status values (see L<cancel>).
307 316
308=item killall 317=item killall
309 318
310Kills/terminates/cancels all coroutines except the currently running 319Kills/terminates/cancels all coroutines except the currently running
311one. This is useful after a fork, either in the child or the parent, as 320one. This can be useful after a fork, either in the child or the parent,
312usually only one of them should inherit the running coroutines. 321as usually only one of them should inherit the running coroutines.
322
323Note that in the implementation, destructors run as normal, making this
324function not so useful after a fork. Future versions of this function
325might try to free resources without running any code.
313 326
314Note that while this will try to free some of the main programs resources, 327Note that while this will try to free some of the main programs resources,
315you cannot free all of them, so if a coroutine that is not the main 328you cannot free all of them, so if a coroutine that is not the main
316program calls this function, there will be some one-time resource leak. 329program calls this function, there will be some one-time resource leak.
317 330
343See C<async> and C<Coro::State::new> for additional info about the 356See C<async> and C<Coro::State::new> for additional info about the
344coroutine environment. 357coroutine environment.
345 358
346=cut 359=cut
347 360
348sub _terminate { 361sub _coro_run {
349 terminate &{+shift}; 362 terminate &{+shift};
350} 363}
351 364
352=item $success = $coroutine->ready 365=item $success = $coroutine->ready
353 366
528would cause a deadlock unless there is an idle handler that wakes up some 541would cause a deadlock unless there is an idle handler that wakes up some
529coroutines. 542coroutines.
530 543
531=item my $guard = Coro::guard { ... } 544=item my $guard = Coro::guard { ... }
532 545
533This creates and returns a guard object. Nothing happens until the object 546This function still exists, but is deprecated. Please use the
534gets destroyed, in which case the codeblock given as argument will be 547C<Guard::guard> function instead.
535executed. This is useful to free locks or other resources in case of a
536runtime error or when the coroutine gets canceled, as in both cases the
537guard block will be executed. The guard object supports only one method,
538C<< ->cancel >>, which will keep the codeblock from being executed.
539 548
540Example: set some flag and clear it again when the coroutine gets canceled
541or the function returns:
542
543 sub do_something {
544 my $guard = Coro::guard { $busy = 0 };
545 $busy = 1;
546
547 # do something that requires $busy to be true
548 }
549
550=cut 549=cut
551 550
552sub guard(&) { 551BEGIN { *guard = \&Guard::guard }
553 bless \(my $cb = $_[0]), "Coro::guard"
554}
555
556sub Coro::guard::cancel {
557 ${$_[0]} = sub { };
558}
559
560sub Coro::guard::DESTROY {
561 ${$_[0]}->();
562}
563
564 552
565=item unblock_sub { ... } 553=item unblock_sub { ... }
566 554
567This utility function takes a BLOCK or code reference and "unblocks" it, 555This utility function takes a BLOCK or code reference and "unblocks" it,
568returning a new coderef. Unblocking means that calling the new coderef 556returning a new coderef. Unblocking means that calling the new coderef
570original code ref will be called (with parameters) from within another 558original code ref will be called (with parameters) from within another
571coroutine. 559coroutine.
572 560
573The reason this function exists is that many event libraries (such as the 561The reason this function exists is that many event libraries (such as the
574venerable L<Event|Event> module) are not coroutine-safe (a weaker form 562venerable L<Event|Event> module) are not coroutine-safe (a weaker form
575of thread-safety). This means you must not block within event callbacks, 563of reentrancy). This means you must not block within event callbacks,
576otherwise you might suffer from crashes or worse. The only event library 564otherwise you might suffer from crashes or worse. The only event library
577currently known that is safe to use without C<unblock_sub> is L<EV>. 565currently known that is safe to use without C<unblock_sub> is L<EV>.
578 566
579This function allows your callbacks to block by executing them in another 567This function allows your callbacks to block by executing them in another
580coroutine where it is safe to block. One example where blocking is handy 568coroutine where it is safe to block. One example where blocking is handy
626 } 614 }
627} 615}
628 616
629=item $cb = Coro::rouse_cb 617=item $cb = Coro::rouse_cb
630 618
631Create and return a "rouse callback". That's a code reference that, when 619Create and return a "rouse callback". That's a code reference that,
632called, will save its arguments and notify the owner coroutine of the 620when called, will remember a copy of its arguments and notify the owner
633callback. 621coroutine of the callback.
634 622
635See the next function. 623See the next function.
636 624
637=item @args = Coro::rouse_wait [$cb] 625=item @args = Coro::rouse_wait [$cb]
638 626
639Wait for the specified rouse callback (or the last one tht was created in 627Wait for the specified rouse callback (or the last one that was created in
640this coroutine). 628this coroutine).
641 629
642As soon as the callback is invoked (or when the calback was invoked before 630As soon as the callback is invoked (or when the callback was invoked
643C<rouse_wait>), it will return a copy of the arguments originally passed 631before C<rouse_wait>), it will return the arguments originally passed to
644to the rouse callback. 632the rouse callback.
645 633
646See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 634See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
647 635
648=back 636=back
649 637
672 660
673Coro offers two functions specifically designed to make this easy, 661Coro offers two functions specifically designed to make this easy,
674C<Coro::rouse_cb> and C<Coro::rouse_wait>. 662C<Coro::rouse_cb> and C<Coro::rouse_wait>.
675 663
676The first function, C<rouse_cb>, generates and returns a callback that, 664The first function, C<rouse_cb>, generates and returns a callback that,
677when invoked, will save it's arguments and notify the coroutine that 665when invoked, will save its arguments and notify the coroutine that
678created the callback. 666created the callback.
679 667
680The second function, C<rouse_wait>, waits for the callback to be called 668The second function, C<rouse_wait>, waits for the callback to be called
681(by calling C<schedule> to go to sleep) and returns the arguments 669(by calling C<schedule> to go to sleep) and returns the arguments
682originally passed to the callback. 670originally passed to the callback.
729fix your libc and use a saner backend. 717fix your libc and use a saner backend.
730 718
731=item perl process emulation ("threads") 719=item perl process emulation ("threads")
732 720
733This module is not perl-pseudo-thread-safe. You should only ever use this 721This module is not perl-pseudo-thread-safe. You should only ever use this
734module from the same thread (this requirement might be removed in the 722module from the first thread (this requirement might be removed in the
735future to allow per-thread schedulers, but Coro::State does not yet allow 723future to allow per-thread schedulers, but Coro::State does not yet allow
736this). I recommend disabling thread support and using processes, as having 724this). I recommend disabling thread support and using processes, as having
737the windows process emulation enabled under unix roughly halves perl 725the windows process emulation enabled under unix roughly halves perl
738performance, even when not used. 726performance, even when not used.
739 727
756 744
757Debugging: L<Coro::Debug>. 745Debugging: L<Coro::Debug>.
758 746
759Support/Utility: L<Coro::Specific>, L<Coro::Util>. 747Support/Utility: L<Coro::Specific>, L<Coro::Util>.
760 748
761Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 749Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
750L<Coro::SemaphoreSet>, L<Coro::RWLock>.
762 751
763IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 752I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
764 753
765Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 754Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
755a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
756L<Coro::Select>.
766 757
767XS API: L<Coro::MakeMaker>. 758XS API: L<Coro::MakeMaker>.
768 759
769Low level Configuration, Coroutine Environment: L<Coro::State>. 760Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
770 761
771=head1 AUTHOR 762=head1 AUTHOR
772 763
773 Marc Lehmann <schmorp@schmorp.de> 764 Marc Lehmann <schmorp@schmorp.de>
774 http://home.schmorp.de/ 765 http://home.schmorp.de/

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