1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
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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26 | $locked = 1; |
26 | $locked = 1; |
27 | $lock->up; |
27 | $lock->up; |
28 | |
28 | |
29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | This module collection manages coroutines. Coroutines are similar to |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
32 | threads but don't (in general) run in parallel at the same time even |
32 | manpage. This manpage mainly contains reference information. |
33 | on SMP machines. The specific flavor of coroutine used in this module |
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34 | also guarantees you that it will not switch between coroutines unless |
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35 | necessary, at easily-identified points in your program, so locking and |
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36 | parallel access are rarely an issue, making coroutine programming much |
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37 | safer and easier than threads programming. |
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38 | |
33 | |
39 | Unlike a normal perl program, however, coroutines allow you to have |
34 | This module collection manages continuations in general, most often |
40 | multiple running interpreters that share data, which is especially useful |
35 | in the form of cooperative threads (also called coroutines in the |
41 | to code pseudo-parallel processes and for event-based programming, such as |
36 | documentation). They are similar to kernel threads but don't (in general) |
42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
37 | run in parallel at the same time even on SMP machines. The specific flavor |
43 | learn more. |
38 | of thread offered by this module also guarantees you that it will not |
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39 | switch between threads unless necessary, at easily-identified points in |
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40 | your program, so locking and parallel access are rarely an issue, making |
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41 | thread programming much safer and easier than using other thread models. |
44 | |
42 | |
45 | Coroutines are also useful because Perl has no support for threads (the so |
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
46 | called "threads" that perl offers are nothing more than the (bad) process |
44 | but only the windows process emulation ported to unix), Coro provides a |
47 | emulation coming from the Windows platform: On standard operating systems |
45 | full shared address space, which makes communication between threads |
48 | they serve no purpose whatsoever, except by making your programs slow and |
46 | very easy. And threads are fast, too: disabling the Windows process |
49 | making them use a lot of memory. Best disable them when building perl, or |
47 | emulation code in your perl and using Coro can easily result in a two to |
50 | aks your software vendor/distributor to do it for you). |
48 | four times speed increase for your programs. |
51 | |
49 | |
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50 | Coro achieves that by supporting multiple running interpreters that share |
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51 | data, which is especially useful to code pseudo-parallel processes and |
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52 | for event-based programming, such as multiple HTTP-GET requests running |
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53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
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54 | into an event-based environment. |
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55 | |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
56 | In this module, a thread is defined as "callchain + lexical variables + |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
54 | its own set of lexicals and its own set of perls most important global |
58 | its own set of lexicals and its own set of perls most important global |
55 | variables (see L<Coro::State> for more configuration). |
59 | variables (see L<Coro::State> for more configuration and background info). |
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60 | |
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61 | See also the C<SEE ALSO> section at the end of this document - the Coro |
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62 | module family is quite large. |
56 | |
63 | |
57 | =cut |
64 | =cut |
58 | |
65 | |
59 | package Coro; |
66 | package Coro; |
60 | |
67 | |
61 | use strict qw(vars subs); |
68 | use strict qw(vars subs); |
62 | no warnings "uninitialized"; |
69 | no warnings "uninitialized"; |
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70 | |
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71 | use Guard (); |
63 | |
72 | |
64 | use Coro::State; |
73 | use Coro::State; |
65 | |
74 | |
66 | use base qw(Coro::State Exporter); |
75 | use base qw(Coro::State Exporter); |
67 | |
76 | |
68 | our $idle; # idle handler |
77 | our $idle; # idle handler |
69 | our $main; # main coroutine |
78 | our $main; # main coroutine |
70 | our $current; # current coroutine |
79 | our $current; # current coroutine |
71 | |
80 | |
72 | our $VERSION = "5.0"; |
81 | our $VERSION = 5.13; |
73 | |
82 | |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
83 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
75 | our %EXPORT_TAGS = ( |
84 | our %EXPORT_TAGS = ( |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
85 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
77 | ); |
86 | ); |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
87 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
79 | |
88 | |
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89 | =head1 GLOBAL VARIABLES |
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90 | |
80 | =over 4 |
91 | =over 4 |
81 | |
92 | |
82 | =item $Coro::main |
93 | =item $Coro::main |
83 | |
94 | |
84 | This variable stores the coroutine object that represents the main |
95 | This variable stores the coroutine object that represents the main |
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105 | sub current() { $current } # [DEPRECATED] |
116 | sub current() { $current } # [DEPRECATED] |
106 | |
117 | |
107 | =item $Coro::idle |
118 | =item $Coro::idle |
108 | |
119 | |
109 | 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 |
110 | 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 |
111 | pretty low-level functionality. |
122 | pretty low-level functionality. |
112 | |
123 | |
113 | 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 |
114 | finds no ready coroutines to run. The default implementation prints |
127 | ready coroutines to run. The default implementation prints "FATAL: |
115 | "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 |
116 | to continue. |
129 | continue. |
117 | |
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 | |
118 | 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 |
119 | 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 |
120 | coroutine so the scheduler can run it. |
137 | coroutine so the scheduler can run it. |
121 | |
138 | |
122 | Note that the callback I<must not>, under any circumstances, block |
139 | Note that the callback I<must not>, under any circumstances, block |
123 | the current coroutine. Normally, this is achieved by having an "idle |
140 | the current coroutine. Normally, this is achieved by having an "idle |
124 | 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 |
125 | 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. |
126 | |
144 | |
127 | 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 |
128 | technique. |
146 | technique. |
129 | |
147 | |
130 | 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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153 | $manager->{desc} = "[coro manager]"; |
171 | $manager->{desc} = "[coro manager]"; |
154 | $manager->prio (PRIO_MAX); |
172 | $manager->prio (PRIO_MAX); |
155 | |
173 | |
156 | =back |
174 | =back |
157 | |
175 | |
158 | =head2 SIMPLE COROUTINE CREATION |
176 | =head1 SIMPLE COROUTINE CREATION |
159 | |
177 | |
160 | =over 4 |
178 | =over 4 |
161 | |
179 | |
162 | =item async { ... } [@args...] |
180 | =item async { ... } [@args...] |
163 | |
181 | |
164 | Create a new coroutine and return it's coroutine object (usually |
182 | Create a new coroutine and return its coroutine object (usually |
165 | unused). The coroutine will be put into the ready queue, so |
183 | unused). The coroutine will be put into the ready queue, so |
166 | it will start running automatically on the next scheduler run. |
184 | it will start running automatically on the next scheduler run. |
167 | |
185 | |
168 | 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 |
169 | 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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246 | } |
264 | } |
247 | } |
265 | } |
248 | |
266 | |
249 | =back |
267 | =back |
250 | |
268 | |
251 | =head2 STATIC METHODS |
269 | =head1 STATIC METHODS |
252 | |
270 | |
253 | Static methods are actually functions that operate on the current coroutine. |
271 | Static methods are actually functions that implicitly operate on the |
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272 | current coroutine. |
254 | |
273 | |
255 | =over 4 |
274 | =over 4 |
256 | |
275 | |
257 | =item schedule |
276 | =item schedule |
258 | |
277 | |
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298 | 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>). |
299 | |
318 | |
300 | =item killall |
319 | =item killall |
301 | |
320 | |
302 | Kills/terminates/cancels all coroutines except the currently running |
321 | Kills/terminates/cancels all coroutines except the currently running |
303 | one. This is useful after a fork, either in the child or the parent, as |
322 | one. This can be useful after a fork, either in the child or the parent, |
304 | usually only one of them should inherit the running coroutines. |
323 | as usually only one of them should inherit the running coroutines. |
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324 | |
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325 | Note that in the implementation, destructors run as normal, making this |
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326 | function not so useful after a fork. Future versions of this function |
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327 | might try to free resources without running any code. |
305 | |
328 | |
306 | Note that while this will try to free some of the main programs resources, |
329 | Note that while this will try to free some of the main programs resources, |
307 | you cannot free all of them, so if a coroutine that is not the main |
330 | you cannot free all of them, so if a coroutine that is not the main |
308 | program calls this function, there will be some one-time resource leak. |
331 | program calls this function, there will be some one-time resource leak. |
309 | |
332 | |
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316 | } |
339 | } |
317 | } |
340 | } |
318 | |
341 | |
319 | =back |
342 | =back |
320 | |
343 | |
321 | =head2 COROUTINE METHODS |
344 | =head1 COROUTINE OBJECT METHODS |
322 | |
345 | |
323 | These are the methods you can call on coroutine objects (or to create |
346 | These are the methods you can call on coroutine objects (or to create |
324 | them). |
347 | them). |
325 | |
348 | |
326 | =over 4 |
349 | =over 4 |
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335 | See C<async> and C<Coro::State::new> for additional info about the |
358 | See C<async> and C<Coro::State::new> for additional info about the |
336 | coroutine environment. |
359 | coroutine environment. |
337 | |
360 | |
338 | =cut |
361 | =cut |
339 | |
362 | |
340 | sub _terminate { |
363 | sub _coro_run { |
341 | terminate &{+shift}; |
364 | terminate &{+shift}; |
342 | } |
365 | } |
343 | |
366 | |
344 | =item $success = $coroutine->ready |
367 | =item $success = $coroutine->ready |
345 | |
368 | |
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505 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
528 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
506 | } |
529 | } |
507 | |
530 | |
508 | =back |
531 | =back |
509 | |
532 | |
510 | =head2 GLOBAL FUNCTIONS |
533 | =head1 GLOBAL FUNCTIONS |
511 | |
534 | |
512 | =over 4 |
535 | =over 4 |
513 | |
536 | |
514 | =item Coro::nready |
537 | =item Coro::nready |
515 | |
538 | |
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520 | would cause a deadlock unless there is an idle handler that wakes up some |
543 | would cause a deadlock unless there is an idle handler that wakes up some |
521 | coroutines. |
544 | coroutines. |
522 | |
545 | |
523 | =item my $guard = Coro::guard { ... } |
546 | =item my $guard = Coro::guard { ... } |
524 | |
547 | |
525 | This creates and returns a guard object. Nothing happens until the object |
548 | This function still exists, but is deprecated. Please use the |
526 | gets destroyed, in which case the codeblock given as argument will be |
549 | C<Guard::guard> function instead. |
527 | executed. This is useful to free locks or other resources in case of a |
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528 | runtime error or when the coroutine gets canceled, as in both cases the |
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529 | guard block will be executed. The guard object supports only one method, |
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530 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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531 | |
550 | |
532 | Example: set some flag and clear it again when the coroutine gets canceled |
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533 | or the function returns: |
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534 | |
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535 | sub do_something { |
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536 | my $guard = Coro::guard { $busy = 0 }; |
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537 | $busy = 1; |
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538 | |
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539 | # do something that requires $busy to be true |
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540 | } |
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541 | |
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542 | =cut |
551 | =cut |
543 | |
552 | |
544 | sub guard(&) { |
553 | BEGIN { *guard = \&Guard::guard } |
545 | bless \(my $cb = $_[0]), "Coro::guard" |
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546 | } |
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547 | |
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548 | sub Coro::guard::cancel { |
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549 | ${$_[0]} = sub { }; |
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550 | } |
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551 | |
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552 | sub Coro::guard::DESTROY { |
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553 | ${$_[0]}->(); |
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554 | } |
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555 | |
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556 | |
554 | |
557 | =item unblock_sub { ... } |
555 | =item unblock_sub { ... } |
558 | |
556 | |
559 | This utility function takes a BLOCK or code reference and "unblocks" it, |
557 | This utility function takes a BLOCK or code reference and "unblocks" it, |
560 | returning a new coderef. Unblocking means that calling the new coderef |
558 | returning a new coderef. Unblocking means that calling the new coderef |
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562 | original code ref will be called (with parameters) from within another |
560 | original code ref will be called (with parameters) from within another |
563 | coroutine. |
561 | coroutine. |
564 | |
562 | |
565 | The reason this function exists is that many event libraries (such as the |
563 | The reason this function exists is that many event libraries (such as the |
566 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
564 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
567 | of thread-safety). This means you must not block within event callbacks, |
565 | of reentrancy). This means you must not block within event callbacks, |
568 | otherwise you might suffer from crashes or worse. The only event library |
566 | otherwise you might suffer from crashes or worse. The only event library |
569 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
567 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
570 | |
568 | |
571 | This function allows your callbacks to block by executing them in another |
569 | This function allows your callbacks to block by executing them in another |
572 | coroutine where it is safe to block. One example where blocking is handy |
570 | coroutine where it is safe to block. One example where blocking is handy |
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618 | } |
616 | } |
619 | } |
617 | } |
620 | |
618 | |
621 | =item $cb = Coro::rouse_cb |
619 | =item $cb = Coro::rouse_cb |
622 | |
620 | |
623 | Create and return a "rouse callback". That's a code reference that, when |
621 | Create and return a "rouse callback". That's a code reference that, |
624 | called, will save its arguments and notify the owner coroutine of the |
622 | when called, will remember a copy of its arguments and notify the owner |
625 | callback. |
623 | coroutine of the callback. |
626 | |
624 | |
627 | See the next function. |
625 | See the next function. |
628 | |
626 | |
629 | =item @args = Coro::rouse_wait [$cb] |
627 | =item @args = Coro::rouse_wait [$cb] |
630 | |
628 | |
631 | Wait for the specified rouse callback (or the last one tht was created in |
629 | Wait for the specified rouse callback (or the last one that was created in |
632 | this coroutine). |
630 | this coroutine). |
633 | |
631 | |
634 | As soon as the callback is invoked (or when the calback was invoked before |
632 | As soon as the callback is invoked (or when the callback was invoked |
635 | C<rouse_wait>), it will return a copy of the arguments originally passed |
633 | before C<rouse_wait>), it will return the arguments originally passed to |
636 | to the rouse callback. |
634 | the rouse callback. |
637 | |
635 | |
638 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
636 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
639 | |
637 | |
640 | =back |
638 | =back |
641 | |
639 | |
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664 | |
662 | |
665 | Coro offers two functions specifically designed to make this easy, |
663 | Coro offers two functions specifically designed to make this easy, |
666 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
664 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
667 | |
665 | |
668 | The first function, C<rouse_cb>, generates and returns a callback that, |
666 | The first function, C<rouse_cb>, generates and returns a callback that, |
669 | when invoked, will save it's arguments and notify the coroutine that |
667 | when invoked, will save its arguments and notify the coroutine that |
670 | created the callback. |
668 | created the callback. |
671 | |
669 | |
672 | The second function, C<rouse_wait>, waits for the callback to be called |
670 | The second function, C<rouse_wait>, waits for the callback to be called |
673 | (by calling C<schedule> to go to sleep) and returns the arguments |
671 | (by calling C<schedule> to go to sleep) and returns the arguments |
674 | originally passed to the callback. |
672 | originally passed to the callback. |
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721 | fix your libc and use a saner backend. |
719 | fix your libc and use a saner backend. |
722 | |
720 | |
723 | =item perl process emulation ("threads") |
721 | =item perl process emulation ("threads") |
724 | |
722 | |
725 | This module is not perl-pseudo-thread-safe. You should only ever use this |
723 | This module is not perl-pseudo-thread-safe. You should only ever use this |
726 | module from the same thread (this requirement might be removed in the |
724 | module from the first thread (this requirement might be removed in the |
727 | future to allow per-thread schedulers, but Coro::State does not yet allow |
725 | future to allow per-thread schedulers, but Coro::State does not yet allow |
728 | this). I recommend disabling thread support and using processes, as having |
726 | this). I recommend disabling thread support and using processes, as having |
729 | the windows process emulation enabled under unix roughly halves perl |
727 | the windows process emulation enabled under unix roughly halves perl |
730 | performance, even when not used. |
728 | performance, even when not used. |
731 | |
729 | |
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748 | |
746 | |
749 | Debugging: L<Coro::Debug>. |
747 | Debugging: L<Coro::Debug>. |
750 | |
748 | |
751 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
749 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
752 | |
750 | |
753 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
751 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
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752 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
754 | |
753 | |
755 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
754 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
756 | |
755 | |
757 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
756 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
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757 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
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758 | L<Coro::Select>. |
758 | |
759 | |
759 | XS API: L<Coro::MakeMaker>. |
760 | XS API: L<Coro::MakeMaker>. |
760 | |
761 | |
761 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
762 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
762 | |
763 | |
763 | =head1 AUTHOR |
764 | =head1 AUTHOR |
764 | |
765 | |
765 | Marc Lehmann <schmorp@schmorp.de> |
766 | Marc Lehmann <schmorp@schmorp.de> |
766 | http://home.schmorp.de/ |
767 | http://home.schmorp.de/ |