Coro/Coro.pm

=head1 NAME

Coro - coroutine process abstraction

=head1 SYNOPSIS

 use Coro;

 async {
    # some asynchronous thread of execution
 };

 # alternatively create an async process like this:

 sub some_func : Coro {
    # some more async code
 }

 yield;

=head1 DESCRIPTION

This module collection manages coroutines. Coroutines are similar to
Threads but don't run in parallel.

This module is still experimental, see the BUGS section below.

=cut

package Coro;

use Coro::State;

use base Exporter;

$VERSION = 0.09;

@EXPORT = qw(async yield schedule terminate);
@EXPORT_OK = qw($current);

{
   use subs 'async';

   my @async;

   # this way of handling attributes simply is NOT scalable ;()
   sub import {
      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;
            } else {
               push @attrs, $_;
            }
         }
         return $old ? $old->($package, $ref, @attrs) : @attrs;
      };
   }

   sub INIT {
      async pop @async while @async;
   }
}

=item $main

This coroutine represents the main program.

=cut

our $main = new Coro;

=item $current

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

=cut

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

our $current = $main;

=item $idle

The coroutine to switch to when no other coroutine is running. The default
implementation prints "FATAL: deadlock detected" and exits.

=cut

# should be done using priorities :(
our $idle = new Coro sub {
   print STDERR "FATAL: deadlock detected\n";
   exit(51);
};

# we really need priorities...
my @ready; # the ready queue. hehe, rather broken ;)

# static methods. not really.

=head2 STATIC METHODS

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

=over 4

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

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

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

The coderef you submit MUST NOT be a closure that refers to variables
in an outer scope. This does NOT work. Pass arguments into it instead.

=cut

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

=item schedule

Calls the scheduler. Please note that the current process will not be put
into the ready queue, so calling this function usually means you will
never be called again.

=cut

my $prev;

sub schedule {
   # should be done using priorities :(
   ($prev, $current) = ($current, shift @ready || $idle);
   Coro::State::transfer($prev, $current);
}

=item yield

Yield to other processes. This function puts the current process into the
ready queue and calls C<schedule>.

=cut

sub yield {
   $current->ready;
   &schedule;
}

=item terminate

Terminates the current process.

Future versions of this function will allow result arguments.

=cut

sub terminate {
   $current->{_results} = [@_];
   &schedule;
}

=back

# dynamic methods

=head2 PROCESS METHODS

These are the methods you can call on process objects.

=over 4

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

Create a new process and return it. When the sub returns the process
automatically terminates. To start the process you must first put it into
the ready queue by calling the ready method.

The coderef you submit MUST NOT be a closure that refers to variables
in an outer scope. This does NOT work. Pass arguments into it instead.

=cut

sub _newcoro {
   terminate &{+shift};
}

sub new {
   my $class = shift;
   bless {
      _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
   }, $class;
}

=item $process->ready

Put the current process into the ready queue.

=cut

sub ready {
   push @ready, $_[0];
}

=back

=cut

1;

=head1 BUGS/LIMITATIONS

 - could be faster, especially when the core would introduce special
   support for coroutines (like it does for threads).
 - there is still a memleak on coroutine termination that I could not
   identify. Could be as small as a single SV.
 - this module is not well-tested.
 - if variables or arguments "disappear" (become undef) or become
   corrupted please contact the author so he cen iron out the
   remaining bugs.
 - this module is not thread-safe. You must only ever use this module from
   the same thread (this requirement might be loosened in the future to
   allow per-thread schedulers, but Coro::Satte does not yet allow this).

=head1 SEE ALSO

L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.

=head1 AUTHOR

 Marc Lehmann <pcg@goof.com>
 http://www.goof.com/pcg/marc/

=cut

Revision:	1.18
Committed:	Sat Jul 21 02:49:09 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.17:	+1 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3	root	1.8	Coro - coroutine process abstraction
4	root	1.1
5			=head1 SYNOPSIS
6
7			use Coro;
8
9	root	1.8	async {
10			# some asynchronous thread of execution
11	root	1.2	};
12
13	root	1.8	# alternatively create an async process like this:
14	root	1.6
15	root	1.8	sub some_func : Coro {
16			# some more async code
17			}
18
19			yield;
20	root	1.2
21	root	1.1	=head1 DESCRIPTION
22
23	root	1.14	This module collection manages coroutines. Coroutines are similar to
24			Threads but don't run in parallel.
25
26			This module is still experimental, see the BUGS section below.
27
28	root	1.8	=cut
29
30			package Coro;
31
32			use Coro::State;
33
34			use base Exporter;
35
36	root	1.18	$VERSION = 0.09;
37	root	1.8
38	root	1.13	@EXPORT = qw(async yield schedule terminate);
39	root	1.8	@EXPORT_OK = qw($current);
40
41			{
42			use subs 'async';
43
44			my @async;
45
46			# this way of handling attributes simply is NOT scalable ;()
47			sub import {
48			Coro->export_to_level(1, @_);
49			my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
50			*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
51			my ($package, $ref) = (shift, shift);
52			my @attrs;
53			for (@_) {
54			if ($_ eq "Coro") {
55			push @async, $ref;
56			} else {
57	root	1.17	push @attrs, $_;
58	root	1.8	}
59			}
60	root	1.17	return $old ? $old->($package, $ref, @attrs) : @attrs;
61	root	1.8	};
62			}
63
64			sub INIT {
65			async pop @async while @async;
66			}
67			}
68
69			=item $main
70	root	1.2
71	root	1.8	This coroutine represents the main program.
72	root	1.1
73			=cut
74
75	root	1.9	our $main = new Coro;
76	root	1.8
77			=item $current
78	root	1.1
79	root	1.8	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
80	root	1.1
81	root	1.8	=cut
82
83			# maybe some other module used Coro::Specific before...
84			if ($current) {
85			$main->{specific} = $current->{specific};
86	root	1.1	}
87
88	root	1.9	our $current = $main;
89
90			=item $idle
91
92			The coroutine to switch to when no other coroutine is running. The default
93			implementation prints "FATAL: deadlock detected" and exits.
94
95			=cut
96
97			# should be done using priorities :(
98			our $idle = new Coro sub {
99			print STDERR "FATAL: deadlock detected\n";
100			exit(51);
101			};
102	root	1.8
103			# we really need priorities...
104	root	1.16	my @ready; # the ready queue. hehe, rather broken ;)
105	root	1.8
106			# static methods. not really.
107
108			=head2 STATIC METHODS
109
110			Static methods are actually functions that operate on the current process only.
111
112			=over 4
113
114	root	1.13	=item async { ... } [@args...]
115	root	1.8
116			Create a new asynchronous process and return it's process object
117			(usually unused). When the sub returns the new process is automatically
118			terminated.
119
120	root	1.13	# create a new coroutine that just prints its arguments
121			async {
122			print "@_\n";
123			} 1,2,3,4;
124
125			The coderef you submit MUST NOT be a closure that refers to variables
126			in an outer scope. This does NOT work. Pass arguments into it instead.
127
128	root	1.8	=cut
129
130	root	1.13	sub async(&@) {
131			my $pid = new Coro @_;
132	root	1.11	$pid->ready;
133			$pid;
134	root	1.8	}
135	root	1.1
136	root	1.8	=item schedule
137	root	1.6
138	root	1.8	Calls the scheduler. Please note that the current process will not be put
139			into the ready queue, so calling this function usually means you will
140			never be called again.
141	root	1.1
142			=cut
143
144	root	1.8	my $prev;
145
146			sub schedule {
147	root	1.9	# should be done using priorities :(
148			($prev, $current) = ($current, shift @ready \|\| $idle);
149	root	1.8	Coro::State::transfer($prev, $current);
150	root	1.1	}
151
152	root	1.8	=item yield
153	root	1.1
154	root	1.8	Yield to other processes. This function puts the current process into the
155			ready queue and calls C<schedule>.
156	root	1.7
157	root	1.8	=cut
158
159			sub yield {
160			$current->ready;
161			&schedule;
162			}
163	root	1.7
164	root	1.8	=item terminate
165	root	1.7
166	root	1.8	Terminates the current process.
167	root	1.1
168	root	1.13	Future versions of this function will allow result arguments.
169
170	root	1.1	=cut
171
172	root	1.8	sub terminate {
173	root	1.13	$current->{_results} = [@_];
174	root	1.8	&schedule;
175	root	1.1	}
176	root	1.6
177	root	1.8	=back
178
179			# dynamic methods
180
181			=head2 PROCESS METHODS
182
183			These are the methods you can call on process objects.
184	root	1.6
185	root	1.8	=over 4
186
187	root	1.13	=item new Coro \&sub [, @args...]
188	root	1.8
189			Create a new process and return it. When the sub returns the process
190			automatically terminates. To start the process you must first put it into
191			the ready queue by calling the ready method.
192	root	1.6
193	root	1.13	The coderef you submit MUST NOT be a closure that refers to variables
194			in an outer scope. This does NOT work. Pass arguments into it instead.
195
196	root	1.6	=cut
197
198	root	1.13	sub _newcoro {
199			terminate &{+shift};
200			}
201
202	root	1.8	sub new {
203			my $class = shift;
204			bless {
205	root	1.13	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
206	root	1.8	}, $class;
207			}
208	root	1.6
209	root	1.8	=item $process->ready
210	root	1.1
211	root	1.8	Put the current process into the ready queue.
212	root	1.1
213	root	1.8	=cut
214	root	1.1
215	root	1.8	sub ready {
216			push @ready, $_[0];
217			}
218	root	1.1
219	root	1.8	=back
220	root	1.2
221	root	1.8	=cut
222	root	1.2
223	root	1.8	1;
224	root	1.14
225	root	1.17	=head1 BUGS/LIMITATIONS
226	root	1.14
227			- could be faster, especially when the core would introduce special
228			support for coroutines (like it does for threads).
229			- there is still a memleak on coroutine termination that I could not
230			identify. Could be as small as a single SV.
231			- this module is not well-tested.
232	root	1.17	- if variables or arguments "disappear" (become undef) or become
233			corrupted please contact the author so he cen iron out the
234			remaining bugs.
235			- this module is not thread-safe. You must only ever use this module from
236			the same thread (this requirement might be loosened in the future to
237			allow per-thread schedulers, but Coro::Satte does not yet allow this).
238	root	1.9
239			=head1 SEE ALSO
240
241			L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
242	root	1.10	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
243	root	1.1
244			=head1 AUTHOR
245
246			Marc Lehmann <pcg@goof.com>
247			http://www.goof.com/pcg/marc/
248
249			=cut
250