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.

WARNING: When using this module, make sure that, at program end, no
coroutines are still running OR just call exit before falling off the
end. The reason for this is that some coroutine of yours might have called
into a C function, and falling off the end of main:: results in returning
to that C function instead if to the main C interpreter.

=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} = [@_];
   delete $current->{_coro_state};
   &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:	1.21
Committed:	Sun Jul 22 03:24:10 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.20:	+7 -0 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	1.21	WARNING: When using this module, make sure that, at program end, no
34			coroutines are still running OR just call exit before falling off the
35			end. The reason for this is that some coroutine of yours might have called
36			into a C function, and falling off the end of main:: results in returning
37			to that C function instead if to the main C interpreter.
38
39	root	1.8	=cut
40
41			package Coro;
42
43			use Coro::State;
44
45			use base Exporter;
46
47	root	1.20	$VERSION = 0.10;
48	root	1.8
49	root	1.19	@EXPORT = qw(async yield schedule terminate current);
50	root	1.8	@EXPORT_OK = qw($current);
51
52			{
53			my @async;
54
55			# this way of handling attributes simply is NOT scalable ;()
56			sub import {
57			Coro->export_to_level(1, @_);
58			my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59			*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60			my ($package, $ref) = (shift, shift);
61			my @attrs;
62			for (@_) {
63			if ($_ eq "Coro") {
64			push @async, $ref;
65			} else {
66	root	1.17	push @attrs, $_;
67	root	1.8	}
68			}
69	root	1.17	return $old ? $old->($package, $ref, @attrs) : @attrs;
70	root	1.8	};
71			}
72
73			sub INIT {
74	root	1.20	&async(pop @async) while @async;
75	root	1.8	}
76			}
77
78			=item $main
79	root	1.2
80	root	1.8	This coroutine represents the main program.
81	root	1.1
82			=cut
83
84	root	1.9	our $main = new Coro;
85	root	1.8
86	root	1.19	=item $current (or as function: current)
87	root	1.1
88	root	1.8	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
89	root	1.1
90	root	1.8	=cut
91
92			# maybe some other module used Coro::Specific before...
93			if ($current) {
94			$main->{specific} = $current->{specific};
95	root	1.1	}
96
97	root	1.9	our $current = $main;
98	root	1.19
99			sub current() { $current }
100	root	1.9
101			=item $idle
102
103			The coroutine to switch to when no other coroutine is running. The default
104			implementation prints "FATAL: deadlock detected" and exits.
105
106			=cut
107
108			# should be done using priorities :(
109			our $idle = new Coro sub {
110			print STDERR "FATAL: deadlock detected\n";
111			exit(51);
112			};
113	root	1.8
114			# we really need priorities...
115	root	1.16	my @ready; # the ready queue. hehe, rather broken ;)
116	root	1.8
117			# static methods. not really.
118
119			=head2 STATIC METHODS
120
121			Static methods are actually functions that operate on the current process only.
122
123			=over 4
124
125	root	1.13	=item async { ... } [@args...]
126	root	1.8
127			Create a new asynchronous process and return it's process object
128			(usually unused). When the sub returns the new process is automatically
129			terminated.
130
131	root	1.13	# create a new coroutine that just prints its arguments
132			async {
133			print "@_\n";
134			} 1,2,3,4;
135
136			The coderef you submit MUST NOT be a closure that refers to variables
137			in an outer scope. This does NOT work. Pass arguments into it instead.
138
139	root	1.8	=cut
140
141	root	1.13	sub async(&@) {
142			my $pid = new Coro @_;
143	root	1.11	$pid->ready;
144			$pid;
145	root	1.8	}
146	root	1.1
147	root	1.8	=item schedule
148	root	1.6
149	root	1.8	Calls the scheduler. Please note that the current process will not be put
150			into the ready queue, so calling this function usually means you will
151			never be called again.
152	root	1.1
153			=cut
154
155	root	1.8	my $prev;
156
157			sub schedule {
158	root	1.9	# should be done using priorities :(
159			($prev, $current) = ($current, shift @ready \|\| $idle);
160	root	1.8	Coro::State::transfer($prev, $current);
161	root	1.1	}
162
163	root	1.8	=item yield
164	root	1.1
165	root	1.8	Yield to other processes. This function puts the current process into the
166			ready queue and calls C<schedule>.
167	root	1.7
168	root	1.8	=cut
169
170			sub yield {
171			$current->ready;
172			&schedule;
173			}
174	root	1.7
175	root	1.8	=item terminate
176	root	1.7
177	root	1.8	Terminates the current process.
178	root	1.1
179	root	1.13	Future versions of this function will allow result arguments.
180
181	root	1.1	=cut
182
183	root	1.8	sub terminate {
184	root	1.13	$current->{_results} = [@_];
185	root	1.21	delete $current->{_coro_state};
186	root	1.8	&schedule;
187	root	1.1	}
188	root	1.6
189	root	1.8	=back
190
191			# dynamic methods
192
193			=head2 PROCESS METHODS
194
195			These are the methods you can call on process objects.
196	root	1.6
197	root	1.8	=over 4
198
199	root	1.13	=item new Coro \&sub [, @args...]
200	root	1.8
201			Create a new process and return it. When the sub returns the process
202			automatically terminates. To start the process you must first put it into
203			the ready queue by calling the ready method.
204	root	1.6
205	root	1.13	The coderef you submit MUST NOT be a closure that refers to variables
206			in an outer scope. This does NOT work. Pass arguments into it instead.
207
208	root	1.6	=cut
209
210	root	1.13	sub _newcoro {
211			terminate &{+shift};
212			}
213
214	root	1.8	sub new {
215			my $class = shift;
216			bless {
217	root	1.13	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
218	root	1.8	}, $class;
219			}
220	root	1.6
221	root	1.8	=item $process->ready
222	root	1.1
223	root	1.8	Put the current process into the ready queue.
224	root	1.1
225	root	1.8	=cut
226	root	1.1
227	root	1.8	sub ready {
228			push @ready, $_[0];
229			}
230	root	1.1
231	root	1.8	=back
232	root	1.2
233	root	1.8	=cut
234	root	1.2
235	root	1.8	1;
236	root	1.14
237	root	1.17	=head1 BUGS/LIMITATIONS
238	root	1.14
239			- could be faster, especially when the core would introduce special
240			support for coroutines (like it does for threads).
241			- there is still a memleak on coroutine termination that I could not
242			identify. Could be as small as a single SV.
243			- this module is not well-tested.
244	root	1.17	- if variables or arguments "disappear" (become undef) or become
245			corrupted please contact the author so he cen iron out the
246			remaining bugs.
247			- this module is not thread-safe. You must only ever use this module from
248			the same thread (this requirement might be loosened in the future to
249	root	1.20	allow per-thread schedulers, but Coro::State does not yet allow this).
250	root	1.9
251			=head1 SEE ALSO
252
253			L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
254	root	1.10	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
255	root	1.1
256			=head1 AUTHOR
257
258			Marc Lehmann <pcg@goof.com>
259			http://www.goof.com/pcg/marc/
260
261			=cut
262