Coro/Coro.pm

=head1 NAME

Coro - coroutine process abstraction

=head1 SYNOPSIS

 use Coro;

 async {
    # some asynchronous thread of execution
 };

 # alternatively create an async coroutine like this:

 sub some_func : Coro {
    # some more async code
 }

 cede;

=head1 DESCRIPTION

This module collection manages coroutines. Coroutines are similar
to threads but don't run in parallel at the same time even on SMP
machines. The specific flavor of coroutine use din this module also
guarentees you that it will not switch between coroutines unless
necessary, at easily-identified points in your program, so locking and
parallel access are rarely an issue, making coroutine programming much
safer than threads programming.

(Perl, however, does not natively support real threads but instead does a
very slow and memory-intensive emulation of processes using threads. This
is a performance win on Windows machines, and a loss everywhere else).

In this module, coroutines are defined as "callchain + lexical variables +
@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
its own set of lexicals and its own set of perls most important global
variables.

=cut

package Coro;

use strict;
no warnings "uninitialized";

use Coro::State;

use base qw(Coro::State Exporter);

our $idle;    # idle handler
our $main;    # main coroutine
our $current; # current coroutine

our $VERSION = '3.3';

our @EXPORT = qw(async cede schedule terminate current unblock_sub);
our %EXPORT_TAGS = (
      prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
);
our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));

{
   my @async;
   my $init;

   # this way of handling attributes simply is NOT scalable ;()
   sub import {
      no strict 'refs';

      Coro->export_to_level (1, @_);

      my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
      *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
         my ($package, $ref) = (shift, shift);
         my @attrs;
         for (@_) {
            if ($_ eq "Coro") {
               push @async, $ref;
               unless ($init++) {
                  eval q{
                     sub INIT {
                        &async(pop @async) while @async;
                     }
                  };
               }
            } else {
               push @attrs, $_;
            }
         }
         return $old ? $old->($package, $ref, @attrs) : @attrs;
      };
   }

}

=over 4

=item $main

This coroutine represents the main program.

=cut

$main = new Coro;

=item $current (or as function: current)

The current coroutine (the last coroutine switched to). The initial value
is C<$main> (of course).

This variable is B<strictly> I<read-only>. It is provided for performance
reasons. If performance is not essentiel you are encouraged to use the
C<Coro::current> function instead.

=cut

# maybe some other module used Coro::Specific before...
$main->{specific} = $current->{specific}
   if $current;

_set_current $main;

sub current() { $current }

=item $idle

A callback that is called whenever the scheduler finds no ready coroutines
to run. The default implementation prints "FATAL: deadlock detected" and
exits, because the program has no other way to continue.

This hook is overwritten by modules such as C<Coro::Timer> and
C<Coro::Event> to wait on an external event that hopefully wake up a
coroutine so the scheduler can run it.

Please note that if your callback recursively invokes perl (e.g. for event
handlers), then it must be prepared to be called recursively.

=cut

$idle = sub {
   require Carp;
   Carp::croak ("FATAL: deadlock detected");
};

# this coroutine is necessary because a coroutine
# cannot destroy itself.
my @destroy;
my $manager; $manager = new Coro sub {
   while () {
      # by overwriting the state object with the manager we destroy it
      # while still being able to schedule this coroutine (in case it has
      # been readied multiple times. this is harmless since the manager
      # can be called as many times as neccessary and will always
      # remove itself from the runqueue
      while (@destroy) {
         my $coro = pop @destroy;

         $coro->{status} ||= [];

         $_->ready                for @{(delete $coro->{join}      ) || []};
         $_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) || []};

         # the next line destroys the coro state, but keeps the
         # coroutine itself intact (we basically make it a zombie
         # coroutine that always runs the manager thread, so it's possible
         # to transfer() to this coroutine).
         $coro->_clone_state_from ($manager);
      }
      &schedule;
   }
};

# static methods. not really.

=back

=head2 STATIC METHODS

Static methods are actually functions that operate on the current coroutine only.

=over 4

=item async { ... } [@args...]

Create a new asynchronous coroutine and return it's coroutine object
(usually unused). When the sub returns the new coroutine is automatically
terminated.

Calling C<exit> in a coroutine will not work correctly, so do not do that.

When the coroutine dies, the program will exit, just as in the main
program.

   # create a new coroutine that just prints its arguments
   async {
      print "@_\n";
   } 1,2,3,4;

=cut

sub async(&@) {
   my $pid = new Coro @_;
   $pid->ready;
   $pid
}

=item schedule

Calls the scheduler. Please note that the current coroutine will not be put
into the ready queue, so calling this function usually means you will
never be called again unless something else (e.g. an event handler) calls
ready.

The canonical way to wait on external events is this:

   {
      # remember current coroutine
      my $current = $Coro::current;

      # register a hypothetical event handler
      on_event_invoke sub {
         # wake up sleeping coroutine
         $current->ready;
         undef $current;
      };

      # call schedule until event occured.
      # in case we are woken up for other reasons
      # (current still defined), loop.
      Coro::schedule while $current;
   }

=item cede

"Cede" to other coroutines. This function puts the current coroutine into the
ready queue and calls C<schedule>, which has the effect of giving up the
current "timeslice" to other coroutines of the same or higher priority.

=item Coro::cede_notself

Works like cede, but is not exported by default and will cede to any
coroutine, regardless of priority, once.

=item terminate [arg...]

Terminates the current coroutine with the given status values (see L<cancel>).

=cut

sub terminate {
   $current->cancel (@_);
}

=back

# dynamic methods

=head2 COROUTINE METHODS

These are the methods you can call on coroutine objects.

=over 4

=item new Coro \&sub [, @args...]

Create a new coroutine and return it. When the sub returns the coroutine
automatically terminates as if C<terminate> with the returned values were
called. To make the coroutine run you must first put it into the ready queue
by calling the ready method.

Calling C<exit> in a coroutine will not work correctly, so do not do that.

=cut

sub _run_coro {
   terminate &{+shift};
}

sub new {
   my $class = shift;

   $class->SUPER::new (\&_run_coro, @_)
}

=item $success = $coroutine->ready

Put the given coroutine into the ready queue (according to it's priority)
and return true. If the coroutine is already in the ready queue, do nothing
and return false.

=item $is_ready = $coroutine->is_ready

Return wether the coroutine is currently the ready queue or not,

=item $coroutine->cancel (arg...)

Terminates the given coroutine and makes it return the given arguments as
status (default: the empty list).

=cut

sub cancel {
   my $self = shift;
   $self->{status} = [@_];
   push @destroy, $self;
   $manager->ready;
   &schedule if $current == $self;
}

=item $coroutine->join

Wait until the coroutine terminates and return any values given to the
C<terminate> or C<cancel> functions. C<join> can be called multiple times
from multiple coroutine.

=cut

sub join {
   my $self = shift;
   unless ($self->{status}) {
      push @{$self->{join}}, $current;
      &schedule;
   }
   wantarray ? @{$self->{status}} : $self->{status}[0];
}

=item $coroutine->on_destroy (\&cb)

Registers a callback that is called when this coroutine gets destroyed,
but before it is joined. The callback gets passed the terminate arguments,
if any.

=cut

sub on_destroy {
   my ($self, $cb) = @_;

   push @{ $self->{destroy_cb} }, $cb;
}

=item $oldprio = $coroutine->prio ($newprio)

Sets (or gets, if the argument is missing) the priority of the
coroutine. Higher priority coroutines get run before lower priority
coroutines. Priorities are small signed integers (currently -4 .. +3),
that you can refer to using PRIO_xxx constants (use the import tag :prio
to get then):

   PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
       3    >     1     >      0      >    -1    >    -3     >    -4

   # set priority to HIGH
   current->prio(PRIO_HIGH);

The idle coroutine ($Coro::idle) always has a lower priority than any
existing coroutine.

Changing the priority of the current coroutine will take effect immediately,
but changing the priority of coroutines in the ready queue (but not
running) will only take effect after the next schedule (of that
coroutine). This is a bug that will be fixed in some future version.

=item $newprio = $coroutine->nice ($change)

Similar to C<prio>, but subtract the given value from the priority (i.e.
higher values mean lower priority, just as in unix).

=item $olddesc = $coroutine->desc ($newdesc)

Sets (or gets in case the argument is missing) the description for this
coroutine. This is just a free-form string you can associate with a coroutine.

=cut

sub desc {
   my $old = $_[0]{desc};
   $_[0]{desc} = $_[1] if @_ > 1;
   $old;
}

=back

=head2 GLOBAL FUNCTIONS

=over 4

=item Coro::nready

Returns the number of coroutines that are currently in the ready state,
i.e. that can be swicthed to. The value C<0> means that the only runnable
coroutine is the currently running one, so C<cede> would have no effect,
and C<schedule> would cause a deadlock unless there is an idle handler
that wakes up some coroutines.

=item unblock_sub { ... }

This utility function takes a BLOCK or code reference and "unblocks" it,
returning the new coderef. This means that the new coderef will return
immediately without blocking, returning nothing, while the original code
ref will be called (with parameters) from within its own coroutine.

The reason this fucntion exists is that many event libraries (such as the
venerable L<Event|Event> module) are not coroutine-safe (a weaker form
of thread-safety). This means you must not block within event callbacks,
otherwise you might suffer from crashes or worse.

This function allows your callbacks to block by executing them in another
coroutine where it is safe to block. One example where blocking is handy
is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
disk.

In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
creating event callbacks that want to block.

=cut

our @unblock_pool;
our @unblock_queue;
our $UNBLOCK_POOL_SIZE = 2;

sub unblock_handler_ {
   while () {
      my ($cb, @arg) = @{ delete $Coro::current->{arg} };
      $cb->(@arg);

      last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
      push @unblock_pool, $Coro::current;
      schedule;
   }        
}           

our $unblock_scheduler = async {
   while () {
      while (my $cb = pop @unblock_queue) {
         my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
         $handler->{arg} = $cb;
         $handler->ready;
         cede;
      }

      schedule;
   }
};

sub unblock_sub(&) {
   my $cb = shift;

   sub {
      push @unblock_queue, [$cb, @_];
      $unblock_scheduler->ready;
   }
}

=back

=cut

1;

=head1 BUGS/LIMITATIONS

 - you must make very sure that no coro is still active on global
   destruction. very bad things might happen otherwise (usually segfaults).

 - this module is not thread-safe. You should only ever use this module
   from the same thread (this requirement might be losened in the future
   to allow per-thread schedulers, but Coro::State does not yet allow
   this).

=head1 SEE ALSO

Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.

Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.

Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.

Embedding: L<Coro:MakeMaker>

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

Revision:	1.102
Committed:	Fri Dec 29 11:37:49 2006 UTC (17 years, 5 months ago) by root
Branch:	MAIN
Changes since 1.101:	+5 -0 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	Coro - coroutine process abstraction
4
5	=head1 SYNOPSIS
6
7	use Coro;
8
9	async {
10	# some asynchronous thread of execution
11	};
12
13	# alternatively create an async coroutine like this:
14
15	sub some_func : Coro {
16	# some more async code
17	}
18
19	cede;
20
21	=head1 DESCRIPTION
22
23	This module collection manages coroutines. Coroutines are similar
24	to threads but don't run in parallel at the same time even on SMP
25	machines. The specific flavor of coroutine use din this module also
26	guarentees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.
30
31	(Perl, however, does not natively support real threads but instead does a
32	very slow and memory-intensive emulation of processes using threads. This
33	is a performance win on Windows machines, and a loss everywhere else).
34
35	In this module, coroutines are defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
37	its own set of lexicals and its own set of perls most important global
38	variables.
39
40	=cut
41
42	package Coro;
43
44	use strict;
45	no warnings "uninitialized";
46
47	use Coro::State;
48
49	use base qw(Coro::State Exporter);
50
51	our $idle; # idle handler
52	our $main; # main coroutine
53	our $current; # current coroutine
54
55	our $VERSION = '3.3';
56
57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62
63	{
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96
97	=over 4
98
99	=item $main
100
101	This coroutine represents the main program.
102
103	=cut
104
105	$main = new Coro;
106
107	=item $current (or as function: current)
108
109	The current coroutine (the last coroutine switched to). The initial value
110	is C<$main> (of course).
111
112	This variable is B<strictly> I<read-only>. It is provided for performance
113	reasons. If performance is not essentiel you are encouraged to use the
114	C<Coro::current> function instead.
115
116	=cut
117
118	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}
120	if $current;
121
122	_set_current $main;
123
124	sub current() { $current }
125
126	=item $idle
127
128	A callback that is called whenever the scheduler finds no ready coroutines
129	to run. The default implementation prints "FATAL: deadlock detected" and
130	exits, because the program has no other way to continue.
131
132	This hook is overwritten by modules such as C<Coro::Timer> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.
135
136	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.
138
139	=cut
140
141	$idle = sub {
142	require Carp;
143	Carp::croak ("FATAL: deadlock detected");
144	};
145
146	# this coroutine is necessary because a coroutine
147	# cannot destroy itself.
148	my @destroy;
149	my $manager; $manager = new Coro sub {
150	while () {
151	# by overwriting the state object with the manager we destroy it
152	# while still being able to schedule this coroutine (in case it has
153	# been readied multiple times. this is harmless since the manager
154	# can be called as many times as neccessary and will always
155	# remove itself from the runqueue
156	while (@destroy) {
157	my $coro = pop @destroy;
158
159	$coro->{status} \|\|= [];
160
161	$_->ready for @{(delete $coro->{join} ) \|\| []};
162	$_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) \|\| []};
163
164	# the next line destroys the coro state, but keeps the
165	# coroutine itself intact (we basically make it a zombie
166	# coroutine that always runs the manager thread, so it's possible
167	# to transfer() to this coroutine).
168	$coro->_clone_state_from ($manager);
169	}
170	&schedule;
171	}
172	};
173
174	# static methods. not really.
175
176	=back
177
178	=head2 STATIC METHODS
179
180	Static methods are actually functions that operate on the current coroutine only.
181
182	=over 4
183
184	=item async { ... } [@args...]
185
186	Create a new asynchronous coroutine and return it's coroutine object
187	(usually unused). When the sub returns the new coroutine is automatically
188	terminated.
189
190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
191
192	When the coroutine dies, the program will exit, just as in the main
193	program.
194
195	# create a new coroutine that just prints its arguments
196	async {
197	print "@_\n";
198	} 1,2,3,4;
199
200	=cut
201
202	sub async(&@) {
203	my $pid = new Coro @_;
204	$pid->ready;
205	$pid
206	}
207
208	=item schedule
209
210	Calls the scheduler. Please note that the current coroutine will not be put
211	into the ready queue, so calling this function usually means you will
212	never be called again unless something else (e.g. an event handler) calls
213	ready.
214
215	The canonical way to wait on external events is this:
216
217	{
218	# remember current coroutine
219	my $current = $Coro::current;
220
221	# register a hypothetical event handler
222	on_event_invoke sub {
223	# wake up sleeping coroutine
224	$current->ready;
225	undef $current;
226	};
227
228	# call schedule until event occured.
229	# in case we are woken up for other reasons
230	# (current still defined), loop.
231	Coro::schedule while $current;
232	}
233
234	=item cede
235
236	"Cede" to other coroutines. This function puts the current coroutine into the
237	ready queue and calls C<schedule>, which has the effect of giving up the
238	current "timeslice" to other coroutines of the same or higher priority.
239
240	=item Coro::cede_notself
241
242	Works like cede, but is not exported by default and will cede to any
243	coroutine, regardless of priority, once.
244
245	=item terminate [arg...]
246
247	Terminates the current coroutine with the given status values (see L<cancel>).
248
249	=cut
250
251	sub terminate {
252	$current->cancel (@_);
253	}
254
255	=back
256
257	# dynamic methods
258
259	=head2 COROUTINE METHODS
260
261	These are the methods you can call on coroutine objects.
262
263	=over 4
264
265	=item new Coro \&sub [, @args...]
266
267	Create a new coroutine and return it. When the sub returns the coroutine
268	automatically terminates as if C<terminate> with the returned values were
269	called. To make the coroutine run you must first put it into the ready queue
270	by calling the ready method.
271
272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
273
274	=cut
275
276	sub _run_coro {
277	terminate &{+shift};
278	}
279
280	sub new {
281	my $class = shift;
282
283	$class->SUPER::new (\&_run_coro, @_)
284	}
285
286	=item $success = $coroutine->ready
287
288	Put the given coroutine into the ready queue (according to it's priority)
289	and return true. If the coroutine is already in the ready queue, do nothing
290	and return false.
291
292	=item $is_ready = $coroutine->is_ready
293
294	Return wether the coroutine is currently the ready queue or not,
295
296	=item $coroutine->cancel (arg...)
297
298	Terminates the given coroutine and makes it return the given arguments as
299	status (default: the empty list).
300
301	=cut
302
303	sub cancel {
304	my $self = shift;
305	$self->{status} = [@_];
306	push @destroy, $self;
307	$manager->ready;
308	&schedule if $current == $self;
309	}
310
311	=item $coroutine->join
312
313	Wait until the coroutine terminates and return any values given to the
314	C<terminate> or C<cancel> functions. C<join> can be called multiple times
315	from multiple coroutine.
316
317	=cut
318
319	sub join {
320	my $self = shift;
321	unless ($self->{status}) {
322	push @{$self->{join}}, $current;
323	&schedule;
324	}
325	wantarray ? @{$self->{status}} : $self->{status}[0];
326	}
327
328	=item $coroutine->on_destroy (\&cb)
329
330	Registers a callback that is called when this coroutine gets destroyed,
331	but before it is joined. The callback gets passed the terminate arguments,
332	if any.
333
334	=cut
335
336	sub on_destroy {
337	my ($self, $cb) = @_;
338
339	push @{ $self->{destroy_cb} }, $cb;
340	}
341
342	=item $oldprio = $coroutine->prio ($newprio)
343
344	Sets (or gets, if the argument is missing) the priority of the
345	coroutine. Higher priority coroutines get run before lower priority
346	coroutines. Priorities are small signed integers (currently -4 .. +3),
347	that you can refer to using PRIO_xxx constants (use the import tag :prio
348	to get then):
349
350	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
351	3 > 1 > 0 > -1 > -3 > -4
352
353	# set priority to HIGH
354	current->prio(PRIO_HIGH);
355
356	The idle coroutine ($Coro::idle) always has a lower priority than any
357	existing coroutine.
358
359	Changing the priority of the current coroutine will take effect immediately,
360	but changing the priority of coroutines in the ready queue (but not
361	running) will only take effect after the next schedule (of that
362	coroutine). This is a bug that will be fixed in some future version.
363
364	=item $newprio = $coroutine->nice ($change)
365
366	Similar to C<prio>, but subtract the given value from the priority (i.e.
367	higher values mean lower priority, just as in unix).
368
369	=item $olddesc = $coroutine->desc ($newdesc)
370
371	Sets (or gets in case the argument is missing) the description for this
372	coroutine. This is just a free-form string you can associate with a coroutine.
373
374	=cut
375
376	sub desc {
377	my $old = $_[0]{desc};
378	$_[0]{desc} = $_[1] if @_ > 1;
379	$old;
380	}
381
382	=back
383
384	=head2 GLOBAL FUNCTIONS
385
386	=over 4
387
388	=item Coro::nready
389
390	Returns the number of coroutines that are currently in the ready state,
391	i.e. that can be swicthed to. The value C<0> means that the only runnable
392	coroutine is the currently running one, so C<cede> would have no effect,
393	and C<schedule> would cause a deadlock unless there is an idle handler
394	that wakes up some coroutines.
395
396	=item unblock_sub { ... }
397
398	This utility function takes a BLOCK or code reference and "unblocks" it,
399	returning the new coderef. This means that the new coderef will return
400	immediately without blocking, returning nothing, while the original code
401	ref will be called (with parameters) from within its own coroutine.
402
403	The reason this fucntion exists is that many event libraries (such as the
404	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
405	of thread-safety). This means you must not block within event callbacks,
406	otherwise you might suffer from crashes or worse.
407
408	This function allows your callbacks to block by executing them in another
409	coroutine where it is safe to block. One example where blocking is handy
410	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
411	disk.
412
413	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
414	creating event callbacks that want to block.
415
416	=cut
417
418	our @unblock_pool;
419	our @unblock_queue;
420	our $UNBLOCK_POOL_SIZE = 2;
421
422	sub unblock_handler_ {
423	while () {
424	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
425	$cb->(@arg);
426
427	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
428	push @unblock_pool, $Coro::current;
429	schedule;
430	}
431	}
432
433	our $unblock_scheduler = async {
434	while () {
435	while (my $cb = pop @unblock_queue) {
436	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
437	$handler->{arg} = $cb;
438	$handler->ready;
439	cede;
440	}
441
442	schedule;
443	}
444	};
445
446	sub unblock_sub(&) {
447	my $cb = shift;
448
449	sub {
450	push @unblock_queue, [$cb, @_];
451	$unblock_scheduler->ready;
452	}
453	}
454
455	=back
456
457	=cut
458
459	1;
460
461	=head1 BUGS/LIMITATIONS
462
463	- you must make very sure that no coro is still active on global
464	destruction. very bad things might happen otherwise (usually segfaults).
465
466	- this module is not thread-safe. You should only ever use this module
467	from the same thread (this requirement might be losened in the future
468	to allow per-thread schedulers, but Coro::State does not yet allow
469	this).
470
471	=head1 SEE ALSO
472
473	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
474
475	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
476
477	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
478
479	Embedding: L<Coro:MakeMaker>
480
481	=head1 AUTHOR
482
483	Marc Lehmann <schmorp@schmorp.de>
484	http://home.schmorp.de/
485
486	=cut
487