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 = 0.08;

@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:	1.17
Committed:	Thu Jul 19 02:45:09 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.16:	+10 -4 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	$VERSION = 0.08;
37
38	@EXPORT = qw(async yield schedule terminate);
39	@EXPORT_OK = qw($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, $ref, @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; # the ready queue. hehe, rather broken ;)
105
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	=item async { ... } [@args...]
115
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	# 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	=cut
129
130	sub async(&@) {
131	my $pid = new Coro @_;
132	$pid->ready;
133	$pid;
134	}
135
136	=item schedule
137
138	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
142	=cut
143
144	my $prev;
145
146	sub schedule {
147	# should be done using priorities :(
148	($prev, $current) = ($current, shift @ready \|\| $idle);
149	Coro::State::transfer($prev, $current);
150	}
151
152	=item yield
153
154	Yield to other processes. This function puts the current process into the
155	ready queue and calls C<schedule>.
156
157	=cut
158
159	sub yield {
160	$current->ready;
161	&schedule;
162	}
163
164	=item terminate
165
166	Terminates the current process.
167
168	Future versions of this function will allow result arguments.
169
170	=cut
171
172	sub terminate {
173	$current->{_results} = [@_];
174	&schedule;
175	}
176
177	=back
178
179	# dynamic methods
180
181	=head2 PROCESS METHODS
182
183	These are the methods you can call on process objects.
184
185	=over 4
186
187	=item new Coro \&sub [, @args...]
188
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
193	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	=cut
197
198	sub _newcoro {
199	terminate &{+shift};
200	}
201
202	sub new {
203	my $class = shift;
204	bless {
205	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
206	}, $class;
207	}
208
209	=item $process->ready
210
211	Put the current process into the ready queue.
212
213	=cut
214
215	sub ready {
216	push @ready, $_[0];
217	}
218
219	=back
220
221	=cut
222
223	1;
224
225	=head1 BUGS/LIMITATIONS
226
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	- 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
239	=head1 SEE ALSO
240
241	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
242	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
243
244	=head1 AUTHOR
245
246	Marc Lehmann <pcg@goof.com>
247	http://www.goof.com/pcg/marc/
248
249	=cut
250