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 *
#	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	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	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	=cut
40
41	package Coro;
42
43	use Coro::State;
44
45	use base Exporter;
46
47	$VERSION = 0.10;
48
49	@EXPORT = qw(async yield schedule terminate current);
50	@EXPORT_OK = qw($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	push @attrs, $_;
67	}
68	}
69	return $old ? $old->($package, $ref, @attrs) : @attrs;
70	};
71	}
72
73	sub INIT {
74	&async(pop @async) while @async;
75	}
76	}
77
78	=item $main
79
80	This coroutine represents the main program.
81
82	=cut
83
84	our $main = new Coro;
85
86	=item $current (or as function: current)
87
88	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
89
90	=cut
91
92	# maybe some other module used Coro::Specific before...
93	if ($current) {
94	$main->{specific} = $current->{specific};
95	}
96
97	our $current = $main;
98
99	sub current() { $current }
100
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
114	# we really need priorities...
115	my @ready; # the ready queue. hehe, rather broken ;)
116
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	=item async { ... } [@args...]
126
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	# 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	=cut
140
141	sub async(&@) {
142	my $pid = new Coro @_;
143	$pid->ready;
144	$pid;
145	}
146
147	=item schedule
148
149	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
153	=cut
154
155	my $prev;
156
157	sub schedule {
158	# should be done using priorities :(
159	($prev, $current) = ($current, shift @ready \|\| $idle);
160	Coro::State::transfer($prev, $current);
161	}
162
163	=item yield
164
165	Yield to other processes. This function puts the current process into the
166	ready queue and calls C<schedule>.
167
168	=cut
169
170	sub yield {
171	$current->ready;
172	&schedule;
173	}
174
175	=item terminate
176
177	Terminates the current process.
178
179	Future versions of this function will allow result arguments.
180
181	=cut
182
183	sub terminate {
184	$current->{_results} = [@_];
185	delete $current->{_coro_state};
186	&schedule;
187	}
188
189	=back
190
191	# dynamic methods
192
193	=head2 PROCESS METHODS
194
195	These are the methods you can call on process objects.
196
197	=over 4
198
199	=item new Coro \&sub [, @args...]
200
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
205	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	=cut
209
210	sub _newcoro {
211	terminate &{+shift};
212	}
213
214	sub new {
215	my $class = shift;
216	bless {
217	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
218	}, $class;
219	}
220
221	=item $process->ready
222
223	Put the current process into the ready queue.
224
225	=cut
226
227	sub ready {
228	push @ready, $_[0];
229	}
230
231	=back
232
233	=cut
234
235	1;
236
237	=head1 BUGS/LIMITATIONS
238
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	- 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	allow per-thread schedulers, but Coro::State does not yet allow this).
250
251	=head1 SEE ALSO
252
253	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
254	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
255
256	=head1 AUTHOR
257
258	Marc Lehmann <pcg@goof.com>
259	http://www.goof.com/pcg/marc/
260
261	=cut
262