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 = 0.06;

@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, $name, @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; #d#
our @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

 - 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.

=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:	1.15
Committed:	Tue Jul 17 02:55:29 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.14:	+1 -1 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 process like this:
14
15	sub some_func : Coro {
16	# some more async code
17	}
18
19	yield;
20
21	=head1 DESCRIPTION
22
23	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	=cut
29
30	package Coro;
31
32	use Coro::State;
33
34	use base Exporter;
35
36	$VERSION = 0.06;
37
38	@EXPORT = qw(async yield schedule terminate);
39	@EXPORT_OK = qw($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	push @attrs, @_;
58	}
59	}
60	return $old ? $old->($package, $name, @attrs) : @attrs;
61	};
62	}
63
64	sub INIT {
65	async pop @async while @async;
66	}
67	}
68
69	=item $main
70
71	This coroutine represents the main program.
72
73	=cut
74
75	our $main = new Coro;
76
77	=item $current
78
79	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
80
81	=cut
82
83	# maybe some other module used Coro::Specific before...
84	if ($current) {
85	$main->{specific} = $current->{specific};
86	}
87
88	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
103	# we really need priorities...
104	## my @ready; #d#
105	our @ready = (); # the ready queue. hehe, rather broken ;)
106
107	# static methods. not really.
108
109	=head2 STATIC METHODS
110
111	Static methods are actually functions that operate on the current process only.
112
113	=over 4
114
115	=item async { ... } [@args...]
116
117	Create a new asynchronous process and return it's process object
118	(usually unused). When the sub returns the new process is automatically
119	terminated.
120
121	# create a new coroutine that just prints its arguments
122	async {
123	print "@_\n";
124	} 1,2,3,4;
125
126	The coderef you submit MUST NOT be a closure that refers to variables
127	in an outer scope. This does NOT work. Pass arguments into it instead.
128
129	=cut
130
131	sub async(&@) {
132	my $pid = new Coro @_;
133	$pid->ready;
134	$pid;
135	}
136
137	=item schedule
138
139	Calls the scheduler. Please note that the current process will not be put
140	into the ready queue, so calling this function usually means you will
141	never be called again.
142
143	=cut
144
145	my $prev;
146
147	sub schedule {
148	# should be done using priorities :(
149	($prev, $current) = ($current, shift @ready \|\| $idle);
150	Coro::State::transfer($prev, $current);
151	}
152
153	=item yield
154
155	Yield to other processes. This function puts the current process into the
156	ready queue and calls C<schedule>.
157
158	=cut
159
160	sub yield {
161	$current->ready;
162	&schedule;
163	}
164
165	=item terminate
166
167	Terminates the current process.
168
169	Future versions of this function will allow result arguments.
170
171	=cut
172
173	sub terminate {
174	$current->{_results} = [@_];
175	&schedule;
176	}
177
178	=back
179
180	# dynamic methods
181
182	=head2 PROCESS METHODS
183
184	These are the methods you can call on process objects.
185
186	=over 4
187
188	=item new Coro \&sub [, @args...]
189
190	Create a new process and return it. When the sub returns the process
191	automatically terminates. To start the process you must first put it into
192	the ready queue by calling the ready method.
193
194	The coderef you submit MUST NOT be a closure that refers to variables
195	in an outer scope. This does NOT work. Pass arguments into it instead.
196
197	=cut
198
199	sub _newcoro {
200	terminate &{+shift};
201	}
202
203	sub new {
204	my $class = shift;
205	bless {
206	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
207	}, $class;
208	}
209
210	=item $process->ready
211
212	Put the current process into the ready queue.
213
214	=cut
215
216	sub ready {
217	push @ready, $_[0];
218	}
219
220	=back
221
222	=cut
223
224	1;
225
226	=head1 BUGS
227
228	- could be faster, especially when the core would introduce special
229	support for coroutines (like it does for threads).
230	- there is still a memleak on coroutine termination that I could not
231	identify. Could be as small as a single SV.
232	- this module is not well-tested.
233
234	=head1 SEE ALSO
235
236	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
237	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
238
239	=head1 AUTHOR
240
241	Marc Lehmann <pcg@goof.com>
242	http://www.goof.com/pcg/marc/
243
244	=cut
245