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() {
      # by overwriting the state object with the manager we destroy it
      # while still being able to schedule this coroutine (in case it has
      # been readied multiple times. this is harmless since the manager
      # can be called as many times as neccessary and will always
      # remove itself from the runqueue
      (pop @destroy)->{_coro_state} = $manager->{_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:	1.37
Committed:	Mon Sep 24 02:25:44 2001 UTC (22 years, 8 months ago) by root
Branch:	MAIN
Changes since 1.36:	+6 -1 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	root	1.22	cede;
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	root	1.23	+ @_ + $_ + $@ + $^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	root	1.22
33	root	1.8	=cut
34
35			package Coro;
36
37	root	1.36	no warnings qw(uninitialized);
38
39	root	1.8	use Coro::State;
40
41			use base Exporter;
42
43	root	1.34	$VERSION = 0.5;
44	root	1.8
45	root	1.22	@EXPORT = qw(async cede schedule terminate current);
46	root	1.31	%EXPORT_TAGS = (
47			prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48			);
49			@EXPORT_OK = @{$EXPORT_TAGS{prio}};
50	root	1.8
51			{
52			my @async;
53	root	1.26	my $init;
54	root	1.8
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, $ref;
65	root	1.26	unless ($init++) {
66			eval q{
67			sub INIT {
68			&async(pop @async) while @async;
69			}
70			};
71			}
72	root	1.8	} else {
73	root	1.17	push @attrs, $_;
74	root	1.8	}
75			}
76	root	1.17	return $old ? $old->($package, $ref, @attrs) : @attrs;
77	root	1.8	};
78			}
79
80			}
81
82			=item $main
83	root	1.2
84	root	1.8	This coroutine represents the main program.
85	root	1.1
86			=cut
87
88	root	1.9	our $main = new Coro;
89	root	1.8
90	root	1.19	=item $current (or as function: current)
91	root	1.1
92	root	1.8	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
93	root	1.1
94	root	1.8	=cut
95
96			# maybe some other module used Coro::Specific before...
97			if ($current) {
98			$main->{specific} = $current->{specific};
99	root	1.1	}
100
101	root	1.9	our $current = $main;
102	root	1.19
103			sub current() { $current }
104	root	1.9
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	root	1.8
118	root	1.24	# this coroutine is necessary because a coroutine
119			# cannot destroy itself.
120			my @destroy;
121			my $manager = new Coro sub {
122			while() {
123	root	1.37	# by overwriting the state object with the manager we destroy it
124			# while still being able to schedule this coroutine (in case it has
125			# been readied multiple times. this is harmless since the manager
126			# can be called as many times as neccessary and will always
127			# remove itself from the runqueue
128			(pop @destroy)->{_coro_state} = $manager->{_coro_state} while @destroy;
129	root	1.24	&schedule;
130			}
131			};
132
133	root	1.8	# static methods. not really.
134
135			=head2 STATIC METHODS
136
137			Static methods are actually functions that operate on the current process only.
138
139			=over 4
140
141	root	1.13	=item async { ... } [@args...]
142	root	1.8
143			Create a new asynchronous process and return it's process object
144			(usually unused). When the sub returns the new process is automatically
145			terminated.
146
147	root	1.13	# create a new coroutine that just prints its arguments
148			async {
149			print "@_\n";
150			} 1,2,3,4;
151
152			The coderef you submit MUST NOT be a closure that refers to variables
153			in an outer scope. This does NOT work. Pass arguments into it instead.
154
155	root	1.8	=cut
156
157	root	1.13	sub async(&@) {
158			my $pid = new Coro @_;
159	root	1.24	$manager->ready; # this ensures that the stack is cloned from the manager
160	root	1.11	$pid->ready;
161			$pid;
162	root	1.8	}
163	root	1.1
164	root	1.8	=item schedule
165	root	1.6
166	root	1.8	Calls the scheduler. Please note that the current process will not be put
167			into the ready queue, so calling this function usually means you will
168			never be called again.
169	root	1.1
170			=cut
171
172	root	1.22	=item cede
173	root	1.1
174	root	1.22	"Cede" to other processes. This function puts the current process into the
175			ready queue and calls C<schedule>, which has the effect of giving up the
176			current "timeslice" to other coroutines of the same or higher priority.
177	root	1.7
178	root	1.8	=cut
179
180			=item terminate
181	root	1.7
182	root	1.8	Terminates the current process.
183	root	1.1
184	root	1.13	Future versions of this function will allow result arguments.
185
186	root	1.1	=cut
187
188	root	1.8	sub terminate {
189	root	1.28	$current->cancel;
190	root	1.23	&schedule;
191	root	1.28	die; # NORETURN
192	root	1.1	}
193	root	1.6
194	root	1.8	=back
195
196			# dynamic methods
197
198			=head2 PROCESS METHODS
199
200			These are the methods you can call on process objects.
201	root	1.6
202	root	1.8	=over 4
203
204	root	1.13	=item new Coro \&sub [, @args...]
205	root	1.8
206			Create a new process and return it. When the sub returns the process
207			automatically terminates. To start the process you must first put it into
208			the ready queue by calling the ready method.
209	root	1.6
210	root	1.13	The coderef you submit MUST NOT be a closure that refers to variables
211			in an outer scope. This does NOT work. Pass arguments into it instead.
212
213	root	1.6	=cut
214
215	root	1.13	sub _newcoro {
216			terminate &{+shift};
217			}
218
219	root	1.8	sub new {
220			my $class = shift;
221			bless {
222	root	1.13	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
223	root	1.8	}, $class;
224			}
225	root	1.6
226	root	1.8	=item $process->ready
227	root	1.1
228	root	1.8	Put the current process into the ready queue.
229	root	1.1
230	root	1.8	=cut
231	root	1.28
232			=item $process->cancel
233
234			Like C<terminate>, but terminates the specified process instead.
235
236			=cut
237
238			sub cancel {
239			push @destroy, $_[0];
240			$manager->ready;
241	root	1.35	&schedule if $current == $_[0];
242	root	1.31	}
243
244			=item $oldprio = $process->prio($newprio)
245
246			Sets the priority of the process. Higher priority processes get run before
247			lower priority processes. Priorities are smalled signed integer (currently
248			-4 .. +3), that you can refer to using PRIO_xxx constants (use the import
249			tag :prio to get then):
250
251			PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
252			3 > 1 > 0 > -1 > -3 > -4
253
254			# set priority to HIGH
255			current->prio(PRIO_HIGH);
256
257			The idle coroutine ($Coro::idle) always has a lower priority than any
258			existing coroutine.
259
260			Changing the priority of the current process will take effect immediately,
261			but changing the priority of processes in the ready queue (but not
262			running) will only take effect after the next schedule (of that
263			process). This is a bug that will be fixed in some future version.
264
265			=cut
266
267			sub prio {
268			my $old = $_[0]{prio};
269			$_[0]{prio} = $_[1] if @_ > 1;
270			$old;
271			}
272
273			=item $newprio = $process->nice($change)
274
275			Similar to C<prio>, but subtract the given value from the priority (i.e.
276			higher values mean lower priority, just as in unix).
277
278			=cut
279
280			sub nice {
281			$_[0]{prio} -= $_[1];
282	root	1.8	}
283	root	1.1
284	root	1.8	=back
285	root	1.2
286	root	1.8	=cut
287	root	1.2
288	root	1.8	1;
289	root	1.14
290	root	1.17	=head1 BUGS/LIMITATIONS
291	root	1.14
292	root	1.33	- you must make very sure that no coro is still active on global destruction.
293			very bad things might happen otherwise (usually segfaults).
294	root	1.17	- this module is not thread-safe. You must only ever use this module from
295			the same thread (this requirement might be loosened in the future to
296	root	1.20	allow per-thread schedulers, but Coro::State does not yet allow this).
297	root	1.9
298			=head1 SEE ALSO
299
300			L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
301	root	1.25	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
302	root	1.26	L<Coro::Handle>, L<Coro::Socket>.
303	root	1.1
304			=head1 AUTHOR
305
306			Marc Lehmann <pcg@goof.com>
307			http://www.goof.com/pcg/marc/
308
309			=cut
310