ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro/Coro.pm
(Generate patch)

Comparing Coro/Coro.pm (file contents):
Revision 1.7 by root, Fri Jul 13 13:05:38 2001 UTC vs.
Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC

1=head1 NAME 1=head1 NAME
2 2
3Coro - create and manage simple coroutines 3Coro - coroutine process abstraction
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use Coro; 7 use Coro;
8 8
9 $new = new Coro sub { 9 async {
10 print "in coroutine, switching back\n"; 10 # some asynchronous thread of execution
11 $new->transfer($main);
12 print "in coroutine again, switching back\n";
13 $new->transfer($main);
14 }; 11 };
15 12
16 $main = new Coro; 13 # alternatively create an async process like this:
17 14
18 print "in main, switching to coroutine\n"; 15 sub some_func : Coro {
19 $main->transfer($new); 16 # some more async code
20 print "back in main, switch to coroutine again\n"; 17 }
21 $main->transfer($new); 18
22 print "back in main\n"; 19 yield;
23 20
24=head1 DESCRIPTION 21=head1 DESCRIPTION
25 22
26This module implements coroutines. Coroutines, similar to continuations, 23=cut
27allow you to run more than one "thread of execution" in parallel. Unlike
28threads this, only voluntary switching is used so locking problems are
29greatly reduced.
30 24
31Although this is the "main" module of the Coro family it provides only 25package Coro;
32low-level functionality. See L<Coro::Process> and related modules for a 26
33more useful process abstraction including scheduling. 27use Coro::State;
28
29use base Exporter;
30
31$VERSION = 0.04;
32
33@EXPORT = qw(async yield schedule);
34@EXPORT_OK = qw($current);
35
36{
37 use subs 'async';
38
39 my @async;
40
41 # this way of handling attributes simply is NOT scalable ;()
42 sub import {
43 Coro->export_to_level(1, @_);
44 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
45 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
46 my ($package, $ref) = (shift, shift);
47 my @attrs;
48 for (@_) {
49 if ($_ eq "Coro") {
50 push @async, $ref;
51 } else {
52 push @attrs, @_;
53 }
54 }
55 return $old ? $old->($package, $name, @attrs) : @attrs;
56 };
57 }
58
59 sub INIT {
60 async pop @async while @async;
61 }
62}
63
64=item $main
65
66This coroutine represents the main program.
67
68=cut
69
70our $main = new Coro;
71
72=item $current
73
74The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
75
76=cut
77
78# maybe some other module used Coro::Specific before...
79if ($current) {
80 $main->{specific} = $current->{specific};
81}
82
83our $current = $main;
84
85=item $idle
86
87The coroutine to switch to when no other coroutine is running. The default
88implementation prints "FATAL: deadlock detected" and exits.
89
90=cut
91
92# should be done using priorities :(
93our $idle = new Coro sub {
94 print STDERR "FATAL: deadlock detected\n";
95 exit(51);
96};
97
98# we really need priorities...
99my @ready = (); # the ready queue. hehe, rather broken ;)
100
101# static methods. not really.
102
103=head2 STATIC METHODS
104
105Static methods are actually functions that operate on the current process only.
34 106
35=over 4 107=over 4
36 108
37=cut 109=item async { ... };
38 110
39package Coro; 111Create a new asynchronous process and return it's process object
112(usually unused). When the sub returns the new process is automatically
113terminated.
40 114
41BEGIN { 115=cut
42 $VERSION = 0.03;
43 116
44 require XSLoader; 117sub async(&) {
45 XSLoader::load Coro, $VERSION; 118 my $pid = new Coro $_[0];
119 $pid->ready;
120 $pid;
46} 121}
47 122
48=item $coro = new [$coderef [, @args]] 123=item schedule
49 124
50Create a new coroutine and return it. The first C<transfer> call to this 125Calls the scheduler. Please note that the current process will not be put
51coroutine will start execution at the given coderef. If, the subroutine 126into the ready queue, so calling this function usually means you will
52returns it will be executed again. 127never be called again.
53 128
54If the coderef is omitted this function will create a new "empty" 129=cut
55coroutine, i.e. a coroutine that cannot be transfered to but can be used 130
56to save the current coroutine in. 131my $prev;
132
133sub schedule {
134 # should be done using priorities :(
135 ($prev, $current) = ($current, shift @ready || $idle);
136 Coro::State::transfer($prev, $current);
137}
138
139=item yield
140
141Yield to other processes. This function puts the current process into the
142ready queue and calls C<schedule>.
143
144=cut
145
146sub yield {
147 $current->ready;
148 &schedule;
149}
150
151=item terminate
152
153Terminates the current process.
154
155=cut
156
157sub terminate {
158 &schedule;
159}
160
161=back
162
163# dynamic methods
164
165=head2 PROCESS METHODS
166
167These are the methods you can call on process objects.
168
169=over 4
170
171=item new Coro \&sub;
172
173Create a new process and return it. When the sub returns the process
174automatically terminates. To start the process you must first put it into
175the ready queue by calling the ready method.
57 176
58=cut 177=cut
59 178
60sub new { 179sub new {
180 my $class = shift;
61 my $class = $_[0]; 181 my $proc = $_[0];
62 my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; 182 bless {
63 bless _newprocess { 183 _coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),
64 do {
65 eval { &$proc };
66 if ($@) {
67 $error_msg = $@;
68 $error_coro = _newprocess { };
69 &transfer($error_coro, $error);
70 }
71 } while (1);
72 }, $class; 184 }, $class;
73} 185}
74 186
75=item $prev->transfer($next) 187=item $process->ready
76 188
77Save the state of the current subroutine in C<$prev> and switch to the 189Put the current process into the ready queue.
78coroutine saved in C<$next>.
79 190
80The "state" of a subroutine only ever includes scope, i.e. lexical
81variables and the current execution state. It does not save/restore any
82global variables such as C<$_> or C<$@> or any other special or non
83special variables. So remember that every function call that might call
84C<transfer> (such as C<Coro::Channel::put>) might clobber any global
85and/or special variables. Yes, this is by design ;) You cna always create
86your own process abstraction model that saves these variables.
87
88The easiest way to do this is to create your own scheduling primitive like this:
89
90 sub schedule {
91 local ($_, $@, ...);
92 $old->transfer($new);
93 }
94
95=cut 191=cut
96 192
97# I call the _transfer function from a perl function 193sub ready {
98# because that way perl saves all important things on 194 push @ready, $_[0];
99# the stack. Actually, I'd do it from within XS, but
100# I couldn't get it to work.
101sub transfer {
102 _transfer($_[0], $_[1]);
103} 195}
104 196
105=item $error, $error_msg, $error_coro 197=back
106 198
107This coroutine will be called on fatal errors. C<$error_msg> and
108C<$error_coro> return the error message and the error-causing coroutine
109(NOT an object) respectively. This API might change.
110
111=cut 199=cut
112
113$error_msg =
114$error_coro = undef;
115
116$error = _newprocess {
117 print STDERR "FATAL: $error_msg\nprogram aborted\n";
118 exit 50;
119};
120 200
1211; 2011;
122 202
123=back
124
125=head1 BUGS
126
127This module has not yet been extensively tested.
128
129=head1 SEE ALSO 203=head1 SEE ALSO
130 204
131L<Coro::Process>, L<Coro::Signal>. 205L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
206L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.
132 207
133=head1 AUTHOR 208=head1 AUTHOR
134 209
135 Marc Lehmann <pcg@goof.com> 210 Marc Lehmann <pcg@goof.com>
136 http://www.goof.com/pcg/marc/ 211 http://www.goof.com/pcg/marc/

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines