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
 }

 cede;

=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 + C stack), 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;

no warnings qw(uninitialized);

use Coro::State;

use base Exporter;

$VERSION = 0.5;

@EXPORT = qw(async cede schedule terminate current);
%EXPORT_TAGS = (
      prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
);
@EXPORT_OK = @{$EXPORT_TAGS{prio}};

{
   my @async;
   my $init;

   # 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, $ref;
               unless ($init++) {
                  eval q{
                     sub INIT {
                        &async(pop @async) while @async;
                     }
                  };
               }
            } else {
               push @attrs, $_;
            }
         }
         return $old ? $old->($package, $ref, @attrs) : @attrs;
      };
   }

}

=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);
};

# this coroutine is necessary because a coroutine
# cannot destroy itself.
my @destroy;
my $manager = new Coro sub {
   while() {
      delete ((pop @destroy)->{_coro_state}) while @destroy;
      &schedule;
   }
};

# 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 @_;
   $manager->ready; # this ensures that the stack is cloned from the manager
   $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

=item cede

"Cede" to other processes. This function puts the current process into the
ready queue and calls C<schedule>, which has the effect of giving up the
current "timeslice" to other coroutines of the same or higher priority.

=cut

=item terminate

Terminates the current process.

Future versions of this function will allow result arguments.

=cut

sub terminate {
   $current->cancel;
   &schedule;
   die; # NORETURN
}

=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

=item $process->cancel

Like C<terminate>, but terminates the specified process instead.

=cut

sub cancel {
   push @destroy, $_[0];
   $manager->ready;
   &schedule if $current == $_[0];
}

=item $oldprio = $process->prio($newprio)

Sets the priority of the process. Higher priority processes get run before
lower priority processes. Priorities are smalled signed integer (currently
-4 .. +3), that you can refer to using PRIO_xxx constants (use the import
tag :prio to get then):

   PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
       3    >     1     >      0      >    -1    >    -3     >    -4

   # set priority to HIGH
   current->prio(PRIO_HIGH);

The idle coroutine ($Coro::idle) always has a lower priority than any
existing coroutine.

Changing the priority of the current process will take effect immediately,
but changing the priority of processes in the ready queue (but not
running) will only take effect after the next schedule (of that
process). This is a bug that will be fixed in some future version.

=cut

sub prio {
   my $old = $_[0]{prio};
   $_[0]{prio} = $_[1] if @_ > 1;
   $old;
}

=item $newprio = $process->nice($change)

Similar to C<prio>, but subtract the given value from the priority (i.e.
higher values mean lower priority, just as in unix).

=cut

sub nice {
   $_[0]{prio} -= $_[1];
}

=back

=cut

1;

=head1 BUGS/LIMITATIONS

 - you must make very sure that no coro is still active on global destruction.
   very bad things might happen otherwise (usually segfaults).
 - 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>, L<Coro::RWLock>,
L<Coro::Handle>, L<Coro::Socket>.

=head1 AUTHOR

 Marc Lehmann <pcg@goof.com>
 http://www.goof.com/pcg/marc/

=cut

Revision:	1.36
Committed:	Mon Sep 24 01:36:20 2001 UTC (22 years, 8 months ago) by root
Branch:	MAIN
Changes since 1.35:	+2 -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	cede;
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 + C stack), that is, a coroutine has it's own
30	callchain, it's own set of lexicals and it's own set of perl's most
31	important global variables.
32
33	=cut
34
35	package Coro;
36
37	no warnings qw(uninitialized);
38
39	use Coro::State;
40
41	use base Exporter;
42
43	$VERSION = 0.5;
44
45	@EXPORT = qw(async cede schedule terminate current);
46	%EXPORT_TAGS = (
47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48	);
49	@EXPORT_OK = @{$EXPORT_TAGS{prio}};
50
51	{
52	my @async;
53	my $init;
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, $ref;
65	unless ($init++) {
66	eval q{
67	sub INIT {
68	&async(pop @async) while @async;
69	}
70	};
71	}
72	} else {
73	push @attrs, $_;
74	}
75	}
76	return $old ? $old->($package, $ref, @attrs) : @attrs;
77	};
78	}
79
80	}
81
82	=item $main
83
84	This coroutine represents the main program.
85
86	=cut
87
88	our $main = new Coro;
89
90	=item $current (or as function: current)
91
92	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
93
94	=cut
95
96	# maybe some other module used Coro::Specific before...
97	if ($current) {
98	$main->{specific} = $current->{specific};
99	}
100
101	our $current = $main;
102
103	sub current() { $current }
104
105	=item $idle
106
107	The coroutine to switch to when no other coroutine is running. The default
108	implementation prints "FATAL: deadlock detected" and exits.
109
110	=cut
111
112	# should be done using priorities :(
113	our $idle = new Coro sub {
114	print STDERR "FATAL: deadlock detected\n";
115	exit(51);
116	};
117
118	# this coroutine is necessary because a coroutine
119	# cannot destroy itself.
120	my @destroy;
121	my $manager = new Coro sub {
122	while() {
123	delete ((pop @destroy)->{_coro_state}) while @destroy;
124	&schedule;
125	}
126	};
127
128	# static methods. not really.
129
130	=head2 STATIC METHODS
131
132	Static methods are actually functions that operate on the current process only.
133
134	=over 4
135
136	=item async { ... } [@args...]
137
138	Create a new asynchronous process and return it's process object
139	(usually unused). When the sub returns the new process is automatically
140	terminated.
141
142	# create a new coroutine that just prints its arguments
143	async {
144	print "@_\n";
145	} 1,2,3,4;
146
147	The coderef you submit MUST NOT be a closure that refers to variables
148	in an outer scope. This does NOT work. Pass arguments into it instead.
149
150	=cut
151
152	sub async(&@) {
153	my $pid = new Coro @_;
154	$manager->ready; # this ensures that the stack is cloned from the manager
155	$pid->ready;
156	$pid;
157	}
158
159	=item schedule
160
161	Calls the scheduler. Please note that the current process will not be put
162	into the ready queue, so calling this function usually means you will
163	never be called again.
164
165	=cut
166
167	=item cede
168
169	"Cede" to other processes. This function puts the current process into the
170	ready queue and calls C<schedule>, which has the effect of giving up the
171	current "timeslice" to other coroutines of the same or higher priority.
172
173	=cut
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->cancel;
185	&schedule;
186	die; # NORETURN
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	=item $process->cancel
228
229	Like C<terminate>, but terminates the specified process instead.
230
231	=cut
232
233	sub cancel {
234	push @destroy, $_[0];
235	$manager->ready;
236	&schedule if $current == $_[0];
237	}
238
239	=item $oldprio = $process->prio($newprio)
240
241	Sets the priority of the process. Higher priority processes get run before
242	lower priority processes. Priorities are smalled signed integer (currently
243	-4 .. +3), that you can refer to using PRIO_xxx constants (use the import
244	tag :prio to get then):
245
246	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
247	3 > 1 > 0 > -1 > -3 > -4
248
249	# set priority to HIGH
250	current->prio(PRIO_HIGH);
251
252	The idle coroutine ($Coro::idle) always has a lower priority than any
253	existing coroutine.
254
255	Changing the priority of the current process will take effect immediately,
256	but changing the priority of processes in the ready queue (but not
257	running) will only take effect after the next schedule (of that
258	process). This is a bug that will be fixed in some future version.
259
260	=cut
261
262	sub prio {
263	my $old = $_[0]{prio};
264	$_[0]{prio} = $_[1] if @_ > 1;
265	$old;
266	}
267
268	=item $newprio = $process->nice($change)
269
270	Similar to C<prio>, but subtract the given value from the priority (i.e.
271	higher values mean lower priority, just as in unix).
272
273	=cut
274
275	sub nice {
276	$_[0]{prio} -= $_[1];
277	}
278
279	=back
280
281	=cut
282
283	1;
284
285	=head1 BUGS/LIMITATIONS
286
287	- you must make very sure that no coro is still active on global destruction.
288	very bad things might happen otherwise (usually segfaults).
289	- this module is not thread-safe. You must only ever use this module from
290	the same thread (this requirement might be loosened in the future to
291	allow per-thread schedulers, but Coro::State does not yet allow this).
292
293	=head1 SEE ALSO
294
295	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
296	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
297	L<Coro::Handle>, L<Coro::Socket>.
298
299	=head1 AUTHOR
300
301	Marc Lehmann <pcg@goof.com>
302	http://www.goof.com/pcg/marc/
303
304	=cut
305