1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - real threads in perl |
3 | Coro - the only real threads in perl |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
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29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
32 | manpage. This manpage mainly contains reference information. |
32 | manpage. This manpage mainly contains reference information. |
33 | |
33 | |
34 | This module collection manages coroutines, that is, cooperative |
34 | This module collection manages continuations in general, most often |
35 | threads. Coroutines are similar to kernel threads but don't (in general) |
35 | in the form of cooperative threads (also called coroutines in the |
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36 | documentation). They are similar to kernel threads but don't (in general) |
36 | run in parallel at the same time even on SMP machines. The specific flavor |
37 | run in parallel at the same time even on SMP machines. The specific flavor |
37 | of coroutine used in this module also guarantees you that it will not |
38 | of thread offered by this module also guarantees you that it will not |
38 | switch between coroutines unless necessary, at easily-identified points |
39 | switch between threads unless necessary, at easily-identified points in |
39 | in your program, so locking and parallel access are rarely an issue, |
40 | your program, so locking and parallel access are rarely an issue, making |
40 | making coroutine programming much safer and easier than using other thread |
41 | thread programming much safer and easier than using other thread models. |
41 | models. |
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42 | |
42 | |
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
44 | but only the windows process emulation ported to unix), Coro provides a |
44 | but only the windows process emulation ported to unix), Coro provides a |
45 | full shared address space, which makes communication between coroutines |
45 | full shared address space, which makes communication between threads |
46 | very easy. And coroutines are fast, too: disabling the Windows process |
46 | very easy. And threads are fast, too: disabling the Windows process |
47 | emulation code in your perl and using Coro can easily result in a two to |
47 | emulation code in your perl and using Coro can easily result in a two to |
48 | four times speed increase for your programs. |
48 | four times speed increase for your programs. |
49 | |
49 | |
50 | Coro achieves that by supporting multiple running interpreters that share |
50 | Coro achieves that by supporting multiple running interpreters that share |
51 | data, which is especially useful to code pseudo-parallel processes and |
51 | data, which is especially useful to code pseudo-parallel processes and |
52 | for event-based programming, such as multiple HTTP-GET requests running |
52 | for event-based programming, such as multiple HTTP-GET requests running |
53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
54 | into an event-based environment. |
54 | into an event-based environment. |
55 | |
55 | |
56 | In this module, a coroutines is defined as "callchain + lexical variables |
56 | In this module, a thread is defined as "callchain + lexical variables + |
57 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
58 | callchain, its own set of lexicals and its own set of perls most important |
58 | its own set of lexicals and its own set of perls most important global |
59 | global variables (see L<Coro::State> for more configuration and background |
59 | variables (see L<Coro::State> for more configuration and background info). |
60 | info). |
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61 | |
60 | |
62 | See also the C<SEE ALSO> section at the end of this document - the Coro |
61 | See also the C<SEE ALSO> section at the end of this document - the Coro |
63 | module family is quite large. |
62 | module family is quite large. |
64 | |
63 | |
65 | =cut |
64 | =cut |
66 | |
65 | |
67 | package Coro; |
66 | package Coro; |
68 | |
67 | |
69 | use strict qw(vars subs); |
68 | use strict qw(vars subs); |
70 | no warnings "uninitialized"; |
69 | no warnings "uninitialized"; |
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70 | |
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71 | use Guard (); |
71 | |
72 | |
72 | use Coro::State; |
73 | use Coro::State; |
73 | |
74 | |
74 | use base qw(Coro::State Exporter); |
75 | use base qw(Coro::State Exporter); |
75 | |
76 | |
76 | our $idle; # idle handler |
77 | our $idle; # idle handler |
77 | our $main; # main coroutine |
78 | our $main; # main coroutine |
78 | our $current; # current coroutine |
79 | our $current; # current coroutine |
79 | |
80 | |
80 | our $VERSION = "5.0"; |
81 | our $VERSION = 5.13; |
81 | |
82 | |
82 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
83 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
83 | our %EXPORT_TAGS = ( |
84 | our %EXPORT_TAGS = ( |
84 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
85 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
85 | ); |
86 | ); |
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115 | sub current() { $current } # [DEPRECATED] |
116 | sub current() { $current } # [DEPRECATED] |
116 | |
117 | |
117 | =item $Coro::idle |
118 | =item $Coro::idle |
118 | |
119 | |
119 | This variable is mainly useful to integrate Coro into event loops. It is |
120 | This variable is mainly useful to integrate Coro into event loops. It is |
120 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
121 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
121 | pretty low-level functionality. |
122 | pretty low-level functionality. |
122 | |
123 | |
123 | This variable stores a callback that is called whenever the scheduler |
124 | This variable stores either a coroutine or a callback. |
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125 | |
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126 | If it is a callback, the it is called whenever the scheduler finds no |
124 | finds no ready coroutines to run. The default implementation prints |
127 | ready coroutines to run. The default implementation prints "FATAL: |
125 | "FATAL: deadlock detected" and exits, because the program has no other way |
128 | deadlock detected" and exits, because the program has no other way to |
126 | to continue. |
129 | continue. |
127 | |
130 | |
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131 | If it is a coroutine object, then this object will be readied (without |
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132 | invoking any ready hooks, however) when the scheduler finds no other ready |
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133 | coroutines to run. |
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134 | |
128 | This hook is overwritten by modules such as C<Coro::Timer> and |
135 | This hook is overwritten by modules such as C<Coro::EV> and |
129 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
136 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
130 | coroutine so the scheduler can run it. |
137 | coroutine so the scheduler can run it. |
131 | |
138 | |
132 | Note that the callback I<must not>, under any circumstances, block |
139 | Note that the callback I<must not>, under any circumstances, block |
133 | the current coroutine. Normally, this is achieved by having an "idle |
140 | the current coroutine. Normally, this is achieved by having an "idle |
134 | coroutine" that calls the event loop and then blocks again, and then |
141 | coroutine" that calls the event loop and then blocks again, and then |
135 | readying that coroutine in the idle handler. |
142 | readying that coroutine in the idle handler, or by simply placing the idle |
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143 | coroutine in this variable. |
136 | |
144 | |
137 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
145 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
138 | technique. |
146 | technique. |
139 | |
147 | |
140 | Please note that if your callback recursively invokes perl (e.g. for event |
148 | Please note that if your callback recursively invokes perl (e.g. for event |
… | |
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169 | |
177 | |
170 | =over 4 |
178 | =over 4 |
171 | |
179 | |
172 | =item async { ... } [@args...] |
180 | =item async { ... } [@args...] |
173 | |
181 | |
174 | Create a new coroutine and return it's coroutine object (usually |
182 | Create a new coroutine and return its coroutine object (usually |
175 | unused). The coroutine will be put into the ready queue, so |
183 | unused). The coroutine will be put into the ready queue, so |
176 | it will start running automatically on the next scheduler run. |
184 | it will start running automatically on the next scheduler run. |
177 | |
185 | |
178 | The first argument is a codeblock/closure that should be executed in the |
186 | The first argument is a codeblock/closure that should be executed in the |
179 | coroutine. When it returns argument returns the coroutine is automatically |
187 | coroutine. When it returns argument returns the coroutine is automatically |
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306 | |
314 | |
307 | =item terminate [arg...] |
315 | =item terminate [arg...] |
308 | |
316 | |
309 | Terminates the current coroutine with the given status values (see L<cancel>). |
317 | Terminates the current coroutine with the given status values (see L<cancel>). |
310 | |
318 | |
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319 | =item Coro::on_enter BLOCK, Coro::on_leave BLOCK |
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320 | |
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321 | These function install enter and leave winders in the current scope. The |
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322 | enter block will be executed when on_enter is called and whenever the |
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323 | current coroutine is re-entered by the scheduler, while the leave block is |
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324 | executed whenever the current coroutine is blocked by the scheduler, and |
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325 | also when the containing scope is exited (by whatever means, be it exit, |
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326 | die, last etc.). |
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327 | |
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328 | I<Neither invoking the scheduler, nor exceptions, are allowed within those |
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329 | BLOCKs>. That means: do not even think about calling C<die> without an |
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330 | eval, and do not even think of entering the scheduler in any way. |
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331 | |
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332 | Since both BLOCKs are tied to the current scope, they will automatically |
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333 | be removed when the current scope exits. |
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334 | |
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335 | These functions implement the same concept as C<dynamic-wind> in scheme |
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336 | does, and are useful when you want to localise some resource to a specific |
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337 | coroutine. |
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338 | |
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339 | They slow down coroutine switching considerably for coroutines that use |
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340 | them (But coroutine switching is still reasonably fast if the handlers are |
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341 | fast). |
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342 | |
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343 | These functions are best understood by an example: The following function |
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344 | will change the current timezone to "Antarctica/South_Pole", which |
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345 | requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>, |
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346 | which remember/change the current timezone and restore the previous |
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347 | value, respectively, the timezone is only changes for the coroutine that |
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348 | installed those handlers. |
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349 | |
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350 | use POSIX qw(tzset); |
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351 | |
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352 | async { |
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353 | my $old_tz; # store outside TZ value here |
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354 | |
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355 | Coro::on_enter { |
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356 | $old_tz = $ENV{TZ}; # remember the old value |
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357 | |
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358 | $ENV{TZ} = "Antarctica/South_Pole"; |
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359 | tzset; # enable new value |
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360 | }; |
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361 | |
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362 | Coro::on_leave { |
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363 | $ENV{TZ} = $old_tz; |
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364 | tzset; # restore old value |
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365 | }; |
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366 | |
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367 | # at this place, the timezone is Antarctica/South_Pole, |
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368 | # without disturbing the TZ of any other coroutine. |
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369 | }; |
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370 | |
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371 | This can be used to localise about any resource (locale, uid, current |
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372 | working directory etc.) to a block, despite the existance of other |
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373 | coroutines. |
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374 | |
311 | =item killall |
375 | =item killall |
312 | |
376 | |
313 | Kills/terminates/cancels all coroutines except the currently running |
377 | Kills/terminates/cancels all coroutines except the currently running one. |
314 | one. This is useful after a fork, either in the child or the parent, as |
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315 | usually only one of them should inherit the running coroutines. |
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316 | |
378 | |
317 | Note that while this will try to free some of the main programs resources, |
379 | Note that while this will try to free some of the main interpreter |
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380 | resources if the calling coroutine isn't the main coroutine, but one |
318 | you cannot free all of them, so if a coroutine that is not the main |
381 | cannot free all of them, so if a coroutine that is not the main coroutine |
319 | program calls this function, there will be some one-time resource leak. |
382 | calls this function, there will be some one-time resource leak. |
320 | |
383 | |
321 | =cut |
384 | =cut |
322 | |
385 | |
323 | sub killall { |
386 | sub killall { |
324 | for (Coro::State::list) { |
387 | for (Coro::State::list) { |
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346 | See C<async> and C<Coro::State::new> for additional info about the |
409 | See C<async> and C<Coro::State::new> for additional info about the |
347 | coroutine environment. |
410 | coroutine environment. |
348 | |
411 | |
349 | =cut |
412 | =cut |
350 | |
413 | |
351 | sub _terminate { |
414 | sub _coro_run { |
352 | terminate &{+shift}; |
415 | terminate &{+shift}; |
353 | } |
416 | } |
354 | |
417 | |
355 | =item $success = $coroutine->ready |
418 | =item $success = $coroutine->ready |
356 | |
419 | |
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531 | would cause a deadlock unless there is an idle handler that wakes up some |
594 | would cause a deadlock unless there is an idle handler that wakes up some |
532 | coroutines. |
595 | coroutines. |
533 | |
596 | |
534 | =item my $guard = Coro::guard { ... } |
597 | =item my $guard = Coro::guard { ... } |
535 | |
598 | |
536 | This creates and returns a guard object. Nothing happens until the object |
599 | This function still exists, but is deprecated. Please use the |
537 | gets destroyed, in which case the codeblock given as argument will be |
600 | C<Guard::guard> function instead. |
538 | executed. This is useful to free locks or other resources in case of a |
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539 | runtime error or when the coroutine gets canceled, as in both cases the |
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540 | guard block will be executed. The guard object supports only one method, |
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541 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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542 | |
601 | |
543 | Example: set some flag and clear it again when the coroutine gets canceled |
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544 | or the function returns: |
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545 | |
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546 | sub do_something { |
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547 | my $guard = Coro::guard { $busy = 0 }; |
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548 | $busy = 1; |
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549 | |
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550 | # do something that requires $busy to be true |
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551 | } |
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552 | |
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553 | =cut |
602 | =cut |
554 | |
603 | |
555 | sub guard(&) { |
604 | BEGIN { *guard = \&Guard::guard } |
556 | bless \(my $cb = $_[0]), "Coro::guard" |
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557 | } |
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558 | |
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559 | sub Coro::guard::cancel { |
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560 | ${$_[0]} = sub { }; |
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561 | } |
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562 | |
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563 | sub Coro::guard::DESTROY { |
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564 | ${$_[0]}->(); |
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565 | } |
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566 | |
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567 | |
605 | |
568 | =item unblock_sub { ... } |
606 | =item unblock_sub { ... } |
569 | |
607 | |
570 | This utility function takes a BLOCK or code reference and "unblocks" it, |
608 | This utility function takes a BLOCK or code reference and "unblocks" it, |
571 | returning a new coderef. Unblocking means that calling the new coderef |
609 | returning a new coderef. Unblocking means that calling the new coderef |
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573 | original code ref will be called (with parameters) from within another |
611 | original code ref will be called (with parameters) from within another |
574 | coroutine. |
612 | coroutine. |
575 | |
613 | |
576 | The reason this function exists is that many event libraries (such as the |
614 | The reason this function exists is that many event libraries (such as the |
577 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
615 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
578 | of thread-safety). This means you must not block within event callbacks, |
616 | of reentrancy). This means you must not block within event callbacks, |
579 | otherwise you might suffer from crashes or worse. The only event library |
617 | otherwise you might suffer from crashes or worse. The only event library |
580 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
618 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
581 | |
619 | |
582 | This function allows your callbacks to block by executing them in another |
620 | This function allows your callbacks to block by executing them in another |
583 | coroutine where it is safe to block. One example where blocking is handy |
621 | coroutine where it is safe to block. One example where blocking is handy |
… | |
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629 | } |
667 | } |
630 | } |
668 | } |
631 | |
669 | |
632 | =item $cb = Coro::rouse_cb |
670 | =item $cb = Coro::rouse_cb |
633 | |
671 | |
634 | Create and return a "rouse callback". That's a code reference that, when |
672 | Create and return a "rouse callback". That's a code reference that, |
635 | called, will save its arguments and notify the owner coroutine of the |
673 | when called, will remember a copy of its arguments and notify the owner |
636 | callback. |
674 | coroutine of the callback. |
637 | |
675 | |
638 | See the next function. |
676 | See the next function. |
639 | |
677 | |
640 | =item @args = Coro::rouse_wait [$cb] |
678 | =item @args = Coro::rouse_wait [$cb] |
641 | |
679 | |
642 | Wait for the specified rouse callback (or the last one tht was created in |
680 | Wait for the specified rouse callback (or the last one that was created in |
643 | this coroutine). |
681 | this coroutine). |
644 | |
682 | |
645 | As soon as the callback is invoked (or when the calback was invoked before |
683 | As soon as the callback is invoked (or when the callback was invoked |
646 | C<rouse_wait>), it will return a copy of the arguments originally passed |
684 | before C<rouse_wait>), it will return the arguments originally passed to |
647 | to the rouse callback. |
685 | the rouse callback. |
648 | |
686 | |
649 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
687 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
650 | |
688 | |
651 | =back |
689 | =back |
652 | |
690 | |
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675 | |
713 | |
676 | Coro offers two functions specifically designed to make this easy, |
714 | Coro offers two functions specifically designed to make this easy, |
677 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
715 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
678 | |
716 | |
679 | The first function, C<rouse_cb>, generates and returns a callback that, |
717 | The first function, C<rouse_cb>, generates and returns a callback that, |
680 | when invoked, will save it's arguments and notify the coroutine that |
718 | when invoked, will save its arguments and notify the coroutine that |
681 | created the callback. |
719 | created the callback. |
682 | |
720 | |
683 | The second function, C<rouse_wait>, waits for the callback to be called |
721 | The second function, C<rouse_wait>, waits for the callback to be called |
684 | (by calling C<schedule> to go to sleep) and returns the arguments |
722 | (by calling C<schedule> to go to sleep) and returns the arguments |
685 | originally passed to the callback. |
723 | originally passed to the callback. |
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732 | fix your libc and use a saner backend. |
770 | fix your libc and use a saner backend. |
733 | |
771 | |
734 | =item perl process emulation ("threads") |
772 | =item perl process emulation ("threads") |
735 | |
773 | |
736 | This module is not perl-pseudo-thread-safe. You should only ever use this |
774 | This module is not perl-pseudo-thread-safe. You should only ever use this |
737 | module from the same thread (this requirement might be removed in the |
775 | module from the first thread (this requirement might be removed in the |
738 | future to allow per-thread schedulers, but Coro::State does not yet allow |
776 | future to allow per-thread schedulers, but Coro::State does not yet allow |
739 | this). I recommend disabling thread support and using processes, as having |
777 | this). I recommend disabling thread support and using processes, as having |
740 | the windows process emulation enabled under unix roughly halves perl |
778 | the windows process emulation enabled under unix roughly halves perl |
741 | performance, even when not used. |
779 | performance, even when not used. |
742 | |
780 | |
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759 | |
797 | |
760 | Debugging: L<Coro::Debug>. |
798 | Debugging: L<Coro::Debug>. |
761 | |
799 | |
762 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
800 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
763 | |
801 | |
764 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
802 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
765 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
803 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
766 | |
804 | |
767 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
805 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
768 | |
806 | |
769 | Compatibility: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
807 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
770 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
808 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
771 | L<Coro::Select>. |
809 | L<Coro::Select>. |
772 | |
810 | |
773 | XS API: L<Coro::MakeMaker>. |
811 | XS API: L<Coro::MakeMaker>. |
774 | |
812 | |
775 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
813 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
776 | |
814 | |
777 | =head1 AUTHOR |
815 | =head1 AUTHOR |
778 | |
816 | |
779 | Marc Lehmann <schmorp@schmorp.de> |
817 | Marc Lehmann <schmorp@schmorp.de> |
780 | http://home.schmorp.de/ |
818 | http://home.schmorp.de/ |