Coro/Coro/AnyEvent.pm

=head1 NAME

Coro::AnyEvent - integrate threads into AnyEvent

=head1 SYNOPSIS

 use Coro;
 use AnyEvent;
 # using both Coro and AnyEvent will automatically load Coro::AnyEvent

 # or load it manually for it's utility functions:
 use Coro::AnyEvent;

 Coro::AnyEvent::sleep 5;     # block current thread for 5s
 Coro::AnyEvent::poll;        # poll for new events once
 Coro::AnyEvent::idle;        # block until process no longer busy
 Coro::AnyEvent::idle_upto 5; # same, but only up to 5 seconds

 Coro::AnyEvent::readable $fh, 60
    or die "fh didn't become readable within 60 seconds\n";

=head1 DESCRIPTION

When one naively starts to use threads in Perl, one will quickly run
into the problem that threads that block on a syscall (sleeping,
reading from a socket etc.) will block all threads.

If one then uses an event loop, the problem is that the event loop has
no knowledge of threads and will not run them before it polls for new
events, again blocking the whole process.

This module integrates threads into any event loop supported by
AnyEvent, combining event-based programming with coroutine-based
programming in a natural way.

As of Coro 5.21 and newer, this module gets loaded automatically when
AnyEvent initialises itself and Coro is used in the same process, thus
there is no need to load it manually if you just want your threads to
coexist with AnyEvent.

If you want to use any functions from this module, you of course still
need to C<use Coro::AnyEvent>, just as with other perl modules.

Also, this module autodetects the event loop used (by relying on
L<AnyEvent>) and will either automatically defer to the high-performance
L<Coro::EV> or L<Coro::Event> modules, or will use a generic integration
method that should work with any event loop supported by L<AnyEvent>.

=head1 USAGE

=head2 RUN AN EVENT LOOP - OR NOT?

For performance reasons, it is recommended that the main program or
something else runs the event loop of the event model you use, i.e.

   use Gtk2; # <- the event model
   use AnyEvent;
   use Coro:

   # initialise stuff
   async { ... };

   # now run mainloop of Gtk2
   main Gtk2;

You can move the event loop into a thread as well, although this tends to
get confusing:

   use Gtk2;
   use AnyEvent;
   use Coro:

   async { main Gtk2 };

   # do other things...
   while () {
      use Coro::AnyEvent;
      Coro::AnyEvent::sleep 1;
      print "ping...\n";
   }

You can also do nothing, in which case Coro:AnyEvent will invoke the event
loop as needed, which is less efficient, but sometimes very convenient.

What you I<MUST NOT DO EVER> is to block inside an event loop
callback. The reason is that most event loops are not reentrant and this
can cause a deadlock at best and corrupt memory at worst.

Coro will try to catch you when you block in the event loop
("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and
only works when you do not run your own event loop.

To avoid this problem, simply do not block inside an event callback
- start a new thread (e.g. with C<Coro:async_pool>) or use
C<Coro::unblock_sub>.

=head2 INVERSION OF CONTROL

If you need to wait for a single event, the rouse functions will come in
handy (see the Coro manpage for details):

   # wait for single SIGINT
   {
      my $int_w = AnyEvent->signal (signal => "INT", cb => Coro::rouse_cb);
      Coro::rouse_wait;
   }

=head2 EVENT MODULES OTHER THEN ANYEVENT

Keep in mind that, as shipped, Coro and Coro::AnyEvent only work with
AnyEvent, and only when AnyEvent is actually used (i.e. initialised), so
this will not work:

   # does not work: EV without AnyEvent is not recognised
   use EV;
   use Coro;

   EV::loop;

And neither does this, unless you actually I<use> AnyEvent for something:

   # does not work: AnyEvent must be initialised (e.g. by creating watchers)
   use EV;
   use AnyEvent;
   use Coro;

   EV::loop;

This does work, however, because you create a watcher (condvars work,
too), thus forcing AnyEvent to initialise itself:

   # does work: AnyEvent is actually used
   use EV;
   use AnyEvent;
   use Coro;

   my $timer = AE::timer 1, 1, sub { };

   EV::loop;

And if you want to use AnyEvent just to bridge between Coro and your event
model of choice, you can simply force it to initialise itself, like this:

   # does work: AnyEvent is initialised manually
   use POE;
   use AnyEvent;
   use Coro;

   AnyEvent::detect; # force AnyEvent to integrate Coro into POE
   POE::Kernel->run;

=head1 FUNCTIONS

Coro::AnyEvent also offers a few functions that might be useful.

=over 4

=cut

package Coro::AnyEvent;

use common::sense;

use Coro;
use AnyEvent ();

our $VERSION = 6.04;

#############################################################################
# idle handler

our $IDLE;

#############################################################################
# 0-timeout idle emulation watcher

our $ACTIVITY;

sub _activity {
   $ACTIVITY ||= AE::timer 0, 0, \&_schedule;
}

Coro::_set_readyhook (\&AnyEvent::detect);

AnyEvent::post_detect {
   my $model = $AnyEvent::MODEL;

   if ($model eq "AnyEvent::Impl::EV" and eval { require Coro::EV }) {
      # provide faster versions of some functions
      Coro::EV::_set_readyhook ();

      eval '
         *sleep = \&Coro::EV::timer_once;
         *poll  = \&Coro::EV::_poll;
         *idle  = sub() {
            my $w = EV::idle Coro::rouse_cb;
            Coro::rouse_wait;
         };
         *idle_upto = sub($) {
            my $cb = Coro::rouse_cb;
            my $t = EV::timer $_[0], 0, $cb;
            my $w = EV::idle $cb;
            Coro::rouse_wait;
         };
         *readable = sub($;$) {
            EV::READ  & Coro::EV::timed_io_once $_[0], EV::READ , $_[1]
         };
         *writable = sub($;$) {
            EV::WRITE & Coro::EV::timed_io_once $_[0], EV::WRITE, $_[1]
         };
      ';
      die if $@;

   } elsif ($model eq "AnyEvent::Impl::Event" and eval { require Coro::Event }) {
      Coro::_set_readyhook undef;
      # let Coro::Event do its thing
   } else {
      # do the inefficient thing ourselves
      Coro::_set_readyhook \&_activity;

      $IDLE = new Coro sub {
         my $_poll = AnyEvent->can ("_poll")
                  || AnyEvent->can ("one_event"); # AnyEvent < 6.0

         while () {
            $_poll->();
            Coro::schedule if Coro::nready;
         }
      };
      $IDLE->{desc} = "[AnyEvent idle process]";

      $Coro::idle = $IDLE;

      # call the readyhook, in case coroutines were already readied
      _activity;
   }

   # augment condvars
   unshift @AnyEvent::CondVar::ISA, "Coro::AnyEvent::CondVar";
};

=item Coro::AnyEvent::poll

This call will block the current thread until the event loop has polled
for potential new events and instructs the event loop to poll for new
events once, without blocking.

Note that this call will not actually execute the poll, nor will it wait
until there are some events, just block until the event loop has polled
for new events, so other threads will have a chance to run.

This is useful when you have a thread that does some computations, but you
still want to poll for new events from time to time. Simply call C<poll>
from time to time:

   my $long_calc = async {
      for (1..10000) {
         Coro::AnyEvent::poll:
         # do some stuff, make sure it takes at least 0.001s or so
      }
   }

Although you should also consider C<idle> or C<idle_upto> in such cases.

=item Coro::AnyEvent::sleep $seconds

This blocks the current thread for at least the given number of seconds.

=item Coro::AnyEvent::idle

This call is similar to C<poll> in that it will also poll for
events. Unlike C<poll>, it will only resume the thread once there are no
events to handle anymore, i.e. when the process is otherwise idle.

This is good for background threads that shouldn't use CPU time when
foreground jobs are ready to run.

=item Coro::AnyEvent::idle_upto $seconds

Like C<idle>, but with a maximum waiting time.

If your process is busy handling events, calling C<idle> can mean that
your thread will never be resumed. To avoid this, you can use C<idle_upto>
and specify a timeout, after which your thread will be resumed even if the
process is completely busy.

=item Coro::AnyEvent::readable $fh_or_fileno[, $timeout]

=item Coro::AnyEvent::writable $fh_or_fileno[, $timeout]

Blocks the current thread until the given file handle (or file descriptor)
becomes readable (or writable), or the given timeout has elapsed,
whichever happens first. No timeout counts as infinite timeout.

Returns true when the file handle became ready, false when a timeout
occured.

Note that these functions are quite inefficient as compared to using a
single watcher (they recreate watchers on every invocation) or compared to
using Coro::Handle.

Note also that they only work for sources that have reasonable
non-blocking behaviour (e.g. not files).

Example: wait until STDIN becomes readable, then quit the program.

   use Coro::AnyEvent;
   print "press enter to quit...\n";
   Coro::AnyEvent::readable *STDIN;
   exit 0;

=cut

sub poll() {
   my $w = AE::timer 0, 0, Coro::rouse_cb;
   Coro::rouse_wait;
}

sub sleep($) {
   my $w = AE::timer $_[0], 0, Coro::rouse_cb;
   Coro::rouse_wait;
}

sub idle() {
   my $w = AE::idle Coro::rouse_cb;
   Coro::rouse_wait;
}

sub idle_upto($) {
   my $cb = Coro::rouse_cb;
   my $t = AE::timer shift, 0, $cb;
   my $w = AE::idle $cb;
   Coro::rouse_wait;
}

sub readable($;$) {
   my $cb = Coro::rouse_cb;
   my $w = AE::io $_[0], 0, sub { $cb->(1) };
   my $t = defined $_[1] && AE::timer $_[1], 0, sub { $cb->(0) };
   Coro::rouse_wait
}

sub writable($;$) {
   my $cb = Coro::rouse_cb;
   my $w = AE::io $_[0], 1, sub { $cb->(1) };
   my $t = defined $_[1] && AE::timer $_[1], 0, sub { $cb->(0) };
   Coro::rouse_wait
}

sub Coro::AnyEvent::CondVar::send {
   (delete $_[0]{_ae_coro})->ready if $_[0]{_ae_coro};

   AnyEvent::CondVar::Base::send $_[0];
};

sub Coro::AnyEvent::CondVar::recv {
   until ($_[0]{_ae_sent}) {
      local $_[0]{_ae_coro} = $Coro::current;
      Coro::schedule;
   }

   AnyEvent::CondVar::Base::recv $_[0];
};

1;

=back

=head1 IMPLEMENTATION DETAILS

Unfortunately, few event loops (basically only L<EV> and L<Event>)
support the kind of integration required for smooth operations well, and
consequently, AnyEvent cannot completely offer the functionality required
by this module, so we need to improvise.

Here is what this module does when it has to work with other event loops:

=over 4

=item * run ready threads before blocking the process

Each time a thread is put into the ready queue (and there are no other
threads in the ready queue), a timer with an C<after> value of C<0> is
registered with AnyEvent.

This creates something similar to an I<idle> watcher, i.e. a watcher
that keeps the event loop from blocking but still polls for new
events. (Unfortunately, some badly designed event loops (e.g. Event::Lib)
don't support a timeout of C<0> and will always block for a bit).

The callback for that timer will C<cede> to other threads of the same or
higher priority for as long as such threads exists. This has the effect of
running all threads that have work to do until all threads block to wait
for external events.

If no threads of equal or higher priority are ready, it will cede to any
thread, but only once. This has the effect of running lower-priority
threads as well, but it will not keep higher priority threads from
receiving new events.

The priority used is simply the priority of the thread that runs the event
loop, usually the main program, which usually has a priority of C<0>. Note
that Coro::AnyEvent does I<not> run an event loop for you, so unless the
main program runs one, there will simply be no event loop to C<cede> to
(event handling will still work, somewhat inefficiently, but any thread
will have a higher priority than event handling in that case).

=item * provide a suitable idle callback.

In addition to hooking into C<ready>, this module will also provide a
C<$Coro::idle> handler that runs the event loop. It is best not to take
advantage of this too often, as this is rather inefficient, but it should
work perfectly fine.

=item * provide overrides for AnyEvent's condvars

This module installs overrides for AnyEvent's condvars. That is, when
the module is loaded it will provide its own condition variables. This
makes them coroutine-safe, i.e. you can safely block on them from within a
coroutine.

=item * lead to data corruption or worse

As C<unblock_sub> cannot be used by this module (as it is the module
that implements it, basically), you must not call into the event
loop recursively from any coroutine. This is not usually a difficult
restriction to live with, just use condvars, C<unblock_sub> or other means
of inter-coroutine-communications.

If you use a module that supports AnyEvent (or uses the same event loop
as AnyEvent, making the compatible), and it offers callbacks of any kind,
then you must not block in them, either (or use e.g. C<unblock_sub>), see
the description of C<unblock_sub> in the L<Coro> module.

This also means that you should load the module as early as possible,
as only condvars created after this module has been loaded will work
correctly.

=back

=head1 SEE ALSO

L<AnyEvent>, to see which event loops are supported, L<Coro::EV> and
L<Coro::Event> for more efficient and more correct solutions (they will be
used automatically if applicable).

=head1 AUTHOR

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

=cut

Revision:	1.73
Committed:	Wed Aug 3 14:52:19 2011 UTC (12 years, 10 months ago) by root
Branch:	MAIN
CVS Tags:	rel-6_04
Changes since 1.72:	+17 -12 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3	root	1.39	Coro::AnyEvent - integrate threads into AnyEvent
4	root	1.1
5			=head1 SYNOPSIS
6
7			use Coro;
8	root	1.54	use AnyEvent;
9			# using both Coro and AnyEvent will automatically load Coro::AnyEvent
10	root	1.1
11	root	1.62	# or load it manually for it's utility functions:
12			use Coro::AnyEvent;
13
14			Coro::AnyEvent::sleep 5; # block current thread for 5s
15			Coro::AnyEvent::poll; # poll for new events once
16			Coro::AnyEvent::idle; # block until process no longer busy
17			Coro::AnyEvent::idle_upto 5; # same, but only up to 5 seconds
18
19			Coro::AnyEvent::readable $fh, 60
20	root	1.63	or die "fh didn't become readable within 60 seconds\n";
21	root	1.2
22	root	1.39	=head1 DESCRIPTION
23	root	1.2
24	root	1.39	When one naively starts to use threads in Perl, one will quickly run
25			into the problem that threads that block on a syscall (sleeping,
26			reading from a socket etc.) will block all threads.
27	root	1.2
28			If one then uses an event loop, the problem is that the event loop has
29	root	1.39	no knowledge of threads and will not run them before it polls for new
30	root	1.2	events, again blocking the whole process.
31
32	root	1.39	This module integrates threads into any event loop supported by
33	root	1.2	AnyEvent, combining event-based programming with coroutine-based
34			programming in a natural way.
35
36	root	1.54	As of Coro 5.21 and newer, this module gets loaded automatically when
37			AnyEvent initialises itself and Coro is used in the same process, thus
38			there is no need to load it manually if you just want your threads to
39			coexist with AnyEvent.
40
41			If you want to use any functions from this module, you of course still
42			need to C<use Coro::AnyEvent>, just as with other perl modules.
43	root	1.1
44	root	1.55	Also, this module autodetects the event loop used (by relying on
45			L<AnyEvent>) and will either automatically defer to the high-performance
46			L<Coro::EV> or L<Coro::Event> modules, or will use a generic integration
47			method that should work with any event loop supported by L<AnyEvent>.
48
49	root	1.39	=head1 USAGE
50	root	1.1
51	root	1.55	=head2 RUN AN EVENT LOOP - OR NOT?
52
53			For performance reasons, it is recommended that the main program or
54			something else runs the event loop of the event model you use, i.e.
55
56			use Gtk2; # <- the event model
57			use AnyEvent;
58			use Coro:
59
60			# initialise stuff
61			async { ... };
62
63			# now run mainloop of Gtk2
64			main Gtk2;
65
66			You can move the event loop into a thread as well, although this tends to
67			get confusing:
68
69			use Gtk2;
70			use AnyEvent;
71			use Coro:
72
73			async { main Gtk2 };
74
75			# do other things...
76			while () {
77			use Coro::AnyEvent;
78			Coro::AnyEvent::sleep 1;
79			print "ping...\n";
80			}
81
82			You can also do nothing, in which case Coro:AnyEvent will invoke the event
83			loop as needed, which is less efficient, but sometimes very convenient.
84
85			What you I<MUST NOT DO EVER> is to block inside an event loop
86			callback. The reason is that most event loops are not reentrant and this
87			can cause a deadlock at best and corrupt memory at worst.
88
89			Coro will try to catch you when you block in the event loop
90			("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and
91			only works when you do not run your own event loop.
92
93			To avoid this problem, simply do not block inside an event callback
94			- start a new thread (e.g. with C<Coro:async_pool>) or use
95			C<Coro::unblock_sub>.
96
97			=head2 INVERSION OF CONTROL
98	root	1.2
99	root	1.55	If you need to wait for a single event, the rouse functions will come in
100			handy (see the Coro manpage for details):
101	root	1.39
102	root	1.40	# wait for single SIGINT
103			{
104			my $int_w = AnyEvent->signal (signal => "INT", cb => Coro::rouse_cb);
105			Coro::rouse_wait;
106			}
107	root	1.39
108	root	1.54	=head2 EVENT MODULES OTHER THEN ANYEVENT
109
110			Keep in mind that, as shipped, Coro and Coro::AnyEvent only work with
111			AnyEvent, and only when AnyEvent is actually used (i.e. initialised), so
112			this will not work:
113
114	root	1.55	# does not work: EV without AnyEvent is not recognised
115	root	1.54	use EV;
116			use Coro;
117
118			EV::loop;
119
120			And neither does this, unless you actually I<use> AnyEvent for something:
121
122	root	1.55	# does not work: AnyEvent must be initialised (e.g. by creating watchers)
123	root	1.54	use EV;
124			use AnyEvent;
125			use Coro;
126
127			EV::loop;
128
129			This does work, however, because you create a watcher (condvars work,
130			too), thus forcing AnyEvent to initialise itself:
131
132			# does work: AnyEvent is actually used
133			use EV;
134			use AnyEvent;
135			use Coro;
136
137			my $timer = AE::timer 1, 1, sub { };
138
139			EV::loop;
140
141			And if you want to use AnyEvent just to bridge between Coro and your event
142			model of choice, you can simply force it to initialise itself, like this:
143
144			# does work: AnyEvent is initialised manually
145			use POE;
146			use AnyEvent;
147			use Coro;
148
149	root	1.55	AnyEvent::detect; # force AnyEvent to integrate Coro into POE
150	root	1.54	POE::Kernel->run;
151
152	root	1.40	=head1 FUNCTIONS
153	root	1.2
154	root	1.55	Coro::AnyEvent also offers a few functions that might be useful.
155	root	1.2
156	root	1.4	=over 4
157
158	root	1.1	=cut
159
160			package Coro::AnyEvent;
161
162	root	1.52	use common::sense;
163	root	1.1
164			use Coro;
165			use AnyEvent ();
166
167	root	1.73	our $VERSION = 6.04;
168	root	1.1
169	root	1.5	#############################################################################
170			# idle handler
171
172	root	1.9	our $IDLE;
173	root	1.1
174	root	1.5	#############################################################################
175			# 0-timeout idle emulation watcher
176
177	root	1.1	our $ACTIVITY;
178
179			sub _activity {
180	root	1.51	$ACTIVITY \|\|= AE::timer 0, 0, \&_schedule;
181	root	1.1	}
182
183	root	1.14	Coro::_set_readyhook (\&AnyEvent::detect);
184	root	1.8
185			AnyEvent::post_detect {
186			my $model = $AnyEvent::MODEL;
187	root	1.1
188	root	1.40	if ($model eq "AnyEvent::Impl::EV" and eval { require Coro::EV }) {
189	root	1.58	# provide faster versions of some functions
190			Coro::EV::_set_readyhook ();
191	root	1.40
192			eval '
193			*sleep = \&Coro::EV::timer_once;
194	root	1.48	*poll = \&Coro::EV::_poll;
195	root	1.52	*idle = sub() {
196	root	1.40	my $w = EV::idle Coro::rouse_cb;
197			Coro::rouse_wait;
198			};
199	root	1.52	*idle_upto = sub($) {
200	root	1.40	my $cb = Coro::rouse_cb;
201			my $t = EV::timer $_[0], 0, $cb;
202			my $w = EV::idle $cb;
203			Coro::rouse_wait;
204			};
205	root	1.52	*readable = sub($;$) {
206	root	1.40	EV::READ & Coro::EV::timed_io_once $_[0], EV::READ , $_[1]
207			};
208	root	1.52	*writable = sub($;$) {
209	root	1.40	EV::WRITE & Coro::EV::timed_io_once $_[0], EV::WRITE, $_[1]
210			};
211			';
212			die if $@;
213
214			} elsif ($model eq "AnyEvent::Impl::Event" and eval { require Coro::Event }) {
215	root	1.58	Coro::_set_readyhook undef;
216	root	1.40	# let Coro::Event do its thing
217	root	1.1	} else {
218	root	1.40	# do the inefficient thing ourselves
219	root	1.1	Coro::_set_readyhook \&_activity;
220	root	1.9
221			$IDLE = new Coro sub {
222	root	1.72	my $_poll = AnyEvent->can ("_poll")
223			\|\| AnyEvent->can ("one_event"); # AnyEvent < 6.0
224	root	1.40
225	root	1.9	while () {
226	root	1.72	$_poll->();
227	root	1.55	Coro::schedule if Coro::nready;
228	root	1.9	}
229			};
230			$IDLE->{desc} = "[AnyEvent idle process]";
231
232	root	1.32	$Coro::idle = $IDLE;
233	root	1.47
234			# call the readyhook, in case coroutines were already readied
235			_activity;
236	root	1.1	}
237	root	1.72
238			# augment condvars
239	root	1.73	unshift @AnyEvent::CondVar::ISA, "Coro::AnyEvent::CondVar";
240	root	1.8	};
241	root	1.5
242	root	1.40	=item Coro::AnyEvent::poll
243
244			This call will block the current thread until the event loop has polled
245	root	1.68	for potential new events and instructs the event loop to poll for new
246			events once, without blocking.
247	root	1.40
248	root	1.68	Note that this call will not actually execute the poll, nor will it wait
249			until there are some events, just block until the event loop has polled
250			for new events, so other threads will have a chance to run.
251	root	1.40
252			This is useful when you have a thread that does some computations, but you
253			still want to poll for new events from time to time. Simply call C<poll>
254			from time to time:
255
256			my $long_calc = async {
257			for (1..10000) {
258			Coro::AnyEvent::poll:
259			# do some stuff, make sure it takes at least 0.001s or so
260			}
261			}
262
263			Although you should also consider C<idle> or C<idle_upto> in such cases.
264
265			=item Coro::AnyEvent::sleep $seconds
266
267			This blocks the current thread for at least the given number of seconds.
268
269			=item Coro::AnyEvent::idle
270
271			This call is similar to C<poll> in that it will also poll for
272			events. Unlike C<poll>, it will only resume the thread once there are no
273			events to handle anymore, i.e. when the process is otherwise idle.
274
275	root	1.56	This is good for background threads that shouldn't use CPU time when
276			foreground jobs are ready to run.
277
278	root	1.40	=item Coro::AnyEvent::idle_upto $seconds
279
280			Like C<idle>, but with a maximum waiting time.
281
282			If your process is busy handling events, calling C<idle> can mean that
283			your thread will never be resumed. To avoid this, you can use C<idle_upto>
284			and specify a timeout, after which your thread will be resumed even if the
285			process is completely busy.
286
287	root	1.44	=item Coro::AnyEvent::readable $fh_or_fileno[, $timeout]
288	root	1.40
289	root	1.44	=item Coro::AnyEvent::writable $fh_or_fileno[, $timeout]
290	root	1.40
291	root	1.44	Blocks the current thread until the given file handle (or file descriptor)
292			becomes readable (or writable), or the given timeout has elapsed,
293			whichever happens first. No timeout counts as infinite timeout.
294	root	1.40
295			Returns true when the file handle became ready, false when a timeout
296			occured.
297
298			Note that these functions are quite inefficient as compared to using a
299			single watcher (they recreate watchers on every invocation) or compared to
300			using Coro::Handle.
301
302			Note also that they only work for sources that have reasonable
303			non-blocking behaviour (e.g. not files).
304
305			Example: wait until STDIN becomes readable, then quit the program.
306
307			use Coro::AnyEvent;
308			print "press enter to quit...\n";
309			Coro::AnyEvent::readable *STDIN;
310			exit 0;
311
312			=cut
313
314			sub poll() {
315	root	1.51	my $w = AE::timer 0, 0, Coro::rouse_cb;
316	root	1.40	Coro::rouse_wait;
317			}
318
319			sub sleep($) {
320	root	1.51	my $w = AE::timer $_[0], 0, Coro::rouse_cb;
321	root	1.40	Coro::rouse_wait;
322			}
323
324			sub idle() {
325	root	1.51	my $w = AE::idle Coro::rouse_cb;
326	root	1.40	Coro::rouse_wait;
327			}
328
329			sub idle_upto($) {
330			my $cb = Coro::rouse_cb;
331	root	1.51	my $t = AE::timer shift, 0, $cb;
332			my $w = AE::idle $cb;
333	root	1.40	Coro::rouse_wait;
334			}
335
336			sub readable($;$) {
337			my $cb = Coro::rouse_cb;
338	root	1.51	my $w = AE::io $_[0], 0, sub { $cb->(1) };
339			my $t = defined $_[1] && AE::timer $_[1], 0, sub { $cb->(0) };
340	root	1.40	Coro::rouse_wait
341			}
342
343			sub writable($;$) {
344			my $cb = Coro::rouse_cb;
345	root	1.51	my $w = AE::io $_[0], 1, sub { $cb->(1) };
346			my $t = defined $_[1] && AE::timer $_[1], 0, sub { $cb->(0) };
347	root	1.40	Coro::rouse_wait
348			}
349
350	root	1.73	sub Coro::AnyEvent::CondVar::send {
351			(delete $_[0]{_ae_coro})->ready if $_[0]{_ae_coro};
352
353			AnyEvent::CondVar::Base::send $_[0];
354			};
355
356			sub Coro::AnyEvent::CondVar::recv {
357			until ($_[0]{_ae_sent}) {
358			local $_[0]{_ae_coro} = $Coro::current;
359			Coro::schedule;
360			}
361
362			AnyEvent::CondVar::Base::recv $_[0];
363			};
364
365	root	1.1	1;
366
367	root	1.40	=back
368
369			=head1 IMPLEMENTATION DETAILS
370
371			Unfortunately, few event loops (basically only L<EV> and L<Event>)
372			support the kind of integration required for smooth operations well, and
373			consequently, AnyEvent cannot completely offer the functionality required
374			by this module, so we need to improvise.
375
376			Here is what this module does when it has to work with other event loops:
377
378			=over 4
379
380			=item * run ready threads before blocking the process
381
382			Each time a thread is put into the ready queue (and there are no other
383			threads in the ready queue), a timer with an C<after> value of C<0> is
384			registered with AnyEvent.
385
386			This creates something similar to an I<idle> watcher, i.e. a watcher
387			that keeps the event loop from blocking but still polls for new
388			events. (Unfortunately, some badly designed event loops (e.g. Event::Lib)
389			don't support a timeout of C<0> and will always block for a bit).
390
391			The callback for that timer will C<cede> to other threads of the same or
392			higher priority for as long as such threads exists. This has the effect of
393			running all threads that have work to do until all threads block to wait
394			for external events.
395
396			If no threads of equal or higher priority are ready, it will cede to any
397			thread, but only once. This has the effect of running lower-priority
398			threads as well, but it will not keep higher priority threads from
399			receiving new events.
400
401			The priority used is simply the priority of the thread that runs the event
402			loop, usually the main program, which usually has a priority of C<0>. Note
403			that Coro::AnyEvent does I<not> run an event loop for you, so unless the
404			main program runs one, there will simply be no event loop to C<cede> to
405			(event handling will still work, somewhat inefficiently, but any thread
406			will have a higher priority than event handling in that case).
407
408			=item * provide a suitable idle callback.
409
410			In addition to hooking into C<ready>, this module will also provide a
411			C<$Coro::idle> handler that runs the event loop. It is best not to take
412			advantage of this too often, as this is rather inefficient, but it should
413			work perfectly fine.
414
415			=item * provide overrides for AnyEvent's condvars
416
417			This module installs overrides for AnyEvent's condvars. That is, when
418			the module is loaded it will provide its own condition variables. This
419			makes them coroutine-safe, i.e. you can safely block on them from within a
420			coroutine.
421
422			=item * lead to data corruption or worse
423
424			As C<unblock_sub> cannot be used by this module (as it is the module
425			that implements it, basically), you must not call into the event
426			loop recursively from any coroutine. This is not usually a difficult
427			restriction to live with, just use condvars, C<unblock_sub> or other means
428			of inter-coroutine-communications.
429
430			If you use a module that supports AnyEvent (or uses the same event loop
431			as AnyEvent, making the compatible), and it offers callbacks of any kind,
432			then you must not block in them, either (or use e.g. C<unblock_sub>), see
433			the description of C<unblock_sub> in the L<Coro> module.
434
435			This also means that you should load the module as early as possible,
436			as only condvars created after this module has been loaded will work
437			correctly.
438
439			=back
440
441	root	1.3	=head1 SEE ALSO
442
443			L<AnyEvent>, to see which event loops are supported, L<Coro::EV> and
444			L<Coro::Event> for more efficient and more correct solutions (they will be
445			used automatically if applicable).
446
447	root	1.1	=head1 AUTHOR
448
449			Marc Lehmann <schmorp@schmorp.de>
450			http://home.schmorp.de/
451
452			=cut
453