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.

In this module, coroutines are defined as "callchain + lexical variables
+ @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's
own set of lexicals and it's own set of perl's most important global
variables.

=cut

package Coro;

use Coro::State;

use base Exporter;

$VERSION = 0.10;

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

{
   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::State 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:	1.20
Committed:	Sat Jul 21 18:21:45 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.19:	+8 -5 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	1.20	In this module, coroutines are defined as "callchain + lexical variables
29			+ @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's
30			own set of lexicals and it's own set of perl's most important global
31			variables.
32
33	root	1.8	=cut
34
35			package Coro;
36
37			use Coro::State;
38
39			use base Exporter;
40
41	root	1.20	$VERSION = 0.10;
42	root	1.8
43	root	1.19	@EXPORT = qw(async yield schedule terminate current);
44	root	1.8	@EXPORT_OK = qw($current);
45
46			{
47			my @async;
48
49			# this way of handling attributes simply is NOT scalable ;()
50			sub import {
51			Coro->export_to_level(1, @_);
52			my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
53			*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
54			my ($package, $ref) = (shift, shift);
55			my @attrs;
56			for (@_) {
57			if ($_ eq "Coro") {
58			push @async, $ref;
59			} else {
60	root	1.17	push @attrs, $_;
61	root	1.8	}
62			}
63	root	1.17	return $old ? $old->($package, $ref, @attrs) : @attrs;
64	root	1.8	};
65			}
66
67			sub INIT {
68	root	1.20	&async(pop @async) while @async;
69	root	1.8	}
70			}
71
72			=item $main
73	root	1.2
74	root	1.8	This coroutine represents the main program.
75	root	1.1
76			=cut
77
78	root	1.9	our $main = new Coro;
79	root	1.8
80	root	1.19	=item $current (or as function: current)
81	root	1.1
82	root	1.8	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
83	root	1.1
84	root	1.8	=cut
85
86			# maybe some other module used Coro::Specific before...
87			if ($current) {
88			$main->{specific} = $current->{specific};
89	root	1.1	}
90
91	root	1.9	our $current = $main;
92	root	1.19
93			sub current() { $current }
94	root	1.9
95			=item $idle
96
97			The coroutine to switch to when no other coroutine is running. The default
98			implementation prints "FATAL: deadlock detected" and exits.
99
100			=cut
101
102			# should be done using priorities :(
103			our $idle = new Coro sub {
104			print STDERR "FATAL: deadlock detected\n";
105			exit(51);
106			};
107	root	1.8
108			# we really need priorities...
109	root	1.16	my @ready; # the ready queue. hehe, rather broken ;)
110	root	1.8
111			# static methods. not really.
112
113			=head2 STATIC METHODS
114
115			Static methods are actually functions that operate on the current process only.
116
117			=over 4
118
119	root	1.13	=item async { ... } [@args...]
120	root	1.8
121			Create a new asynchronous process and return it's process object
122			(usually unused). When the sub returns the new process is automatically
123			terminated.
124
125	root	1.13	# create a new coroutine that just prints its arguments
126			async {
127			print "@_\n";
128			} 1,2,3,4;
129
130			The coderef you submit MUST NOT be a closure that refers to variables
131			in an outer scope. This does NOT work. Pass arguments into it instead.
132
133	root	1.8	=cut
134
135	root	1.13	sub async(&@) {
136			my $pid = new Coro @_;
137	root	1.11	$pid->ready;
138			$pid;
139	root	1.8	}
140	root	1.1
141	root	1.8	=item schedule
142	root	1.6
143	root	1.8	Calls the scheduler. Please note that the current process will not be put
144			into the ready queue, so calling this function usually means you will
145			never be called again.
146	root	1.1
147			=cut
148
149	root	1.8	my $prev;
150
151			sub schedule {
152	root	1.9	# should be done using priorities :(
153			($prev, $current) = ($current, shift @ready \|\| $idle);
154	root	1.8	Coro::State::transfer($prev, $current);
155	root	1.1	}
156
157	root	1.8	=item yield
158	root	1.1
159	root	1.8	Yield to other processes. This function puts the current process into the
160			ready queue and calls C<schedule>.
161	root	1.7
162	root	1.8	=cut
163
164			sub yield {
165			$current->ready;
166			&schedule;
167			}
168	root	1.7
169	root	1.8	=item terminate
170	root	1.7
171	root	1.8	Terminates the current process.
172	root	1.1
173	root	1.13	Future versions of this function will allow result arguments.
174
175	root	1.1	=cut
176
177	root	1.8	sub terminate {
178	root	1.13	$current->{_results} = [@_];
179	root	1.8	&schedule;
180	root	1.1	}
181	root	1.6
182	root	1.8	=back
183
184			# dynamic methods
185
186			=head2 PROCESS METHODS
187
188			These are the methods you can call on process objects.
189	root	1.6
190	root	1.8	=over 4
191
192	root	1.13	=item new Coro \&sub [, @args...]
193	root	1.8
194			Create a new process and return it. When the sub returns the process
195			automatically terminates. To start the process you must first put it into
196			the ready queue by calling the ready method.
197	root	1.6
198	root	1.13	The coderef you submit MUST NOT be a closure that refers to variables
199			in an outer scope. This does NOT work. Pass arguments into it instead.
200
201	root	1.6	=cut
202
203	root	1.13	sub _newcoro {
204			terminate &{+shift};
205			}
206
207	root	1.8	sub new {
208			my $class = shift;
209			bless {
210	root	1.13	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
211	root	1.8	}, $class;
212			}
213	root	1.6
214	root	1.8	=item $process->ready
215	root	1.1
216	root	1.8	Put the current process into the ready queue.
217	root	1.1
218	root	1.8	=cut
219	root	1.1
220	root	1.8	sub ready {
221			push @ready, $_[0];
222			}
223	root	1.1
224	root	1.8	=back
225	root	1.2
226	root	1.8	=cut
227	root	1.2
228	root	1.8	1;
229	root	1.14
230	root	1.17	=head1 BUGS/LIMITATIONS
231	root	1.14
232			- could be faster, especially when the core would introduce special
233			support for coroutines (like it does for threads).
234			- there is still a memleak on coroutine termination that I could not
235			identify. Could be as small as a single SV.
236			- this module is not well-tested.
237	root	1.17	- if variables or arguments "disappear" (become undef) or become
238			corrupted please contact the author so he cen iron out the
239			remaining bugs.
240			- this module is not thread-safe. You must only ever use this module from
241			the same thread (this requirement might be loosened in the future to
242	root	1.20	allow per-thread schedulers, but Coro::State does not yet allow this).
243	root	1.9
244			=head1 SEE ALSO
245
246			L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
247	root	1.10	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
248	root	1.1
249			=head1 AUTHOR
250
251			Marc Lehmann <pcg@goof.com>
252			http://www.goof.com/pcg/marc/
253
254			=cut
255