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 current);
@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 (or as function: 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;

sub current() { $current }

=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:	1.19
Committed:	Sat Jul 21 03:44:06 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.18:	+4 -2 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	$VERSION = 0.09;
37
38	@EXPORT = qw(async yield schedule terminate current);
39	@EXPORT_OK = qw($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 $current (or as function: current)
78
79	The current coroutine (the last coroutine switched to). The initial value is C<$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	sub current() { $current }
91
92	=item $idle
93
94	The coroutine to switch to when no other coroutine is running. The default
95	implementation prints "FATAL: deadlock detected" and exits.
96
97	=cut
98
99	# should be done using priorities :(
100	our $idle = new Coro sub {
101	print STDERR "FATAL: deadlock detected\n";
102	exit(51);
103	};
104
105	# we really need priorities...
106	my @ready; # the ready queue. hehe, rather broken ;)
107
108	# static methods. not really.
109
110	=head2 STATIC METHODS
111
112	Static methods are actually functions that operate on the current process only.
113
114	=over 4
115
116	=item async { ... } [@args...]
117
118	Create a new asynchronous process and return it's process object
119	(usually unused). When the sub returns the new process is automatically
120	terminated.
121
122	# create a new coroutine that just prints its arguments
123	async {
124	print "@_\n";
125	} 1,2,3,4;
126
127	The coderef you submit MUST NOT be a closure that refers to variables
128	in an outer scope. This does NOT work. Pass arguments into it instead.
129
130	=cut
131
132	sub async(&@) {
133	my $pid = new Coro @_;
134	$pid->ready;
135	$pid;
136	}
137
138	=item schedule
139
140	Calls the scheduler. Please note that the current process will not be put
141	into the ready queue, so calling this function usually means you will
142	never be called again.
143
144	=cut
145
146	my $prev;
147
148	sub schedule {
149	# should be done using priorities :(
150	($prev, $current) = ($current, shift @ready \|\| $idle);
151	Coro::State::transfer($prev, $current);
152	}
153
154	=item yield
155
156	Yield to other processes. This function puts the current process into the
157	ready queue and calls C<schedule>.
158
159	=cut
160
161	sub yield {
162	$current->ready;
163	&schedule;
164	}
165
166	=item terminate
167
168	Terminates the current process.
169
170	Future versions of this function will allow result arguments.
171
172	=cut
173
174	sub terminate {
175	$current->{_results} = [@_];
176	&schedule;
177	}
178
179	=back
180
181	# dynamic methods
182
183	=head2 PROCESS METHODS
184
185	These are the methods you can call on process objects.
186
187	=over 4
188
189	=item new Coro \&sub [, @args...]
190
191	Create a new process and return it. When the sub returns the process
192	automatically terminates. To start the process you must first put it into
193	the ready queue by calling the ready method.
194
195	The coderef you submit MUST NOT be a closure that refers to variables
196	in an outer scope. This does NOT work. Pass arguments into it instead.
197
198	=cut
199
200	sub _newcoro {
201	terminate &{+shift};
202	}
203
204	sub new {
205	my $class = shift;
206	bless {
207	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
208	}, $class;
209	}
210
211	=item $process->ready
212
213	Put the current process into the ready queue.
214
215	=cut
216
217	sub ready {
218	push @ready, $_[0];
219	}
220
221	=back
222
223	=cut
224
225	1;
226
227	=head1 BUGS/LIMITATIONS
228
229	- could be faster, especially when the core would introduce special
230	support for coroutines (like it does for threads).
231	- there is still a memleak on coroutine termination that I could not
232	identify. Could be as small as a single SV.
233	- this module is not well-tested.
234	- if variables or arguments "disappear" (become undef) or become
235	corrupted please contact the author so he cen iron out the
236	remaining bugs.
237	- this module is not thread-safe. You must only ever use this module from
238	the same thread (this requirement might be loosened in the future to
239	allow per-thread schedulers, but Coro::Satte does not yet allow this).
240
241	=head1 SEE ALSO
242
243	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
244	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
245
246	=head1 AUTHOR
247
248	Marc Lehmann <pcg@goof.com>
249	http://www.goof.com/pcg/marc/
250
251	=cut
252