1 |
=head1 NAME |
2 |
|
3 |
Coro - create and manage simple coroutines |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use Coro; |
8 |
|
9 |
$new = new Coro sub { |
10 |
print "in coroutine, switching back\n"; |
11 |
$new->transfer($main); |
12 |
print "in coroutine again, switching back\n"; |
13 |
$new->transfer($main); |
14 |
}; |
15 |
|
16 |
$main = new Coro; |
17 |
|
18 |
print "in main, switching to coroutine\n"; |
19 |
$main->transfer($new); |
20 |
print "back in main, switch to coroutine again\n"; |
21 |
$main->transfer($new); |
22 |
print "back in main\n"; |
23 |
|
24 |
=head1 DESCRIPTION |
25 |
|
26 |
This module implements coroutines. Coroutines, similar to continuations, |
27 |
allow you to run more than one "thread of execution" in parallel. Unlike |
28 |
threads this, only voluntary switching is used so locking problems are |
29 |
greatly reduced. |
30 |
|
31 |
Although this is the "main" module of the Coro family it provides only |
32 |
low-level functionality. See L<Coro::Process> and related modules for a |
33 |
more useful process abstraction including scheduling. |
34 |
|
35 |
=over 4 |
36 |
|
37 |
=cut |
38 |
|
39 |
package Coro; |
40 |
|
41 |
BEGIN { |
42 |
$VERSION = 0.03; |
43 |
|
44 |
require XSLoader; |
45 |
XSLoader::load Coro, $VERSION; |
46 |
} |
47 |
|
48 |
=item $coro = new [$coderef [, @args]] |
49 |
|
50 |
Create a new coroutine and return it. The first C<transfer> call to this |
51 |
coroutine will start execution at the given coderef. If, the subroutine |
52 |
returns it will be executed again. |
53 |
|
54 |
If the coderef is omitted this function will create a new "empty" |
55 |
coroutine, i.e. a coroutine that cannot be transfered to but can be used |
56 |
to save the current coroutine in. |
57 |
|
58 |
=cut |
59 |
|
60 |
sub new { |
61 |
my $class = $_[0]; |
62 |
my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; |
63 |
bless _newprocess { |
64 |
do { |
65 |
eval { &$proc }; |
66 |
if ($@) { |
67 |
$error_msg = $@; |
68 |
$error_coro = _newprocess { }; |
69 |
&transfer($error_coro, $error); |
70 |
} |
71 |
} while (1); |
72 |
}, $class; |
73 |
} |
74 |
|
75 |
=item $prev->transfer($next) |
76 |
|
77 |
Save the state of the current subroutine in C<$prev> and switch to the |
78 |
coroutine saved in C<$next>. |
79 |
|
80 |
The "state" of a subroutine only ever includes scope, i.e. lexical |
81 |
variables and the current execution state. It does not save/restore any |
82 |
global variables such as C<$_> or C<$@> or any other special or non |
83 |
special variables. So remember that every function call that might call |
84 |
C<transfer> (such as C<Coro::Channel::put>) might clobber any global |
85 |
and/or special variables. Yes, this is by design ;) You cna always create |
86 |
your own process abstraction model that saves these variables. |
87 |
|
88 |
The 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 |
96 |
|
97 |
# I call the _transfer function from a perl function |
98 |
# because that way perl saves all important things on |
99 |
# the stack. Actually, I'd do it from within XS, but |
100 |
# I couldn't get it to work. |
101 |
sub transfer { |
102 |
_transfer($_[0], $_[1]); |
103 |
} |
104 |
|
105 |
=item $error, $error_msg, $error_coro |
106 |
|
107 |
This coroutine will be called on fatal errors. C<$error_msg> and |
108 |
C<$error_coro> return the error message and the error-causing coroutine |
109 |
(NOT an object) respectively. This API might change. |
110 |
|
111 |
=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 |
|
121 |
1; |
122 |
|
123 |
=back |
124 |
|
125 |
=head1 BUGS |
126 |
|
127 |
This module has not yet been extensively tested. |
128 |
|
129 |
=head1 SEE ALSO |
130 |
|
131 |
L<Coro::Process>, L<Coro::Signal>. |
132 |
|
133 |
=head1 AUTHOR |
134 |
|
135 |
Marc Lehmann <pcg@goof.com> |
136 |
http://www.goof.com/pcg/marc/ |
137 |
|
138 |
=cut |
139 |
|