1 |
root |
1.1 |
=head1 NAME |
2 |
|
|
|
3 |
|
|
Coro::Semaphore - non-binary semaphores |
4 |
|
|
|
5 |
|
|
=head1 SYNOPSIS |
6 |
|
|
|
7 |
|
|
use Coro::Semaphore; |
8 |
|
|
|
9 |
root |
1.3 |
$sig = new Coro::Semaphore [initial value]; |
10 |
root |
1.1 |
|
11 |
|
|
$sig->down; # wait for signal |
12 |
|
|
|
13 |
|
|
# ... some other "thread" |
14 |
|
|
|
15 |
|
|
$sig->up; |
16 |
|
|
|
17 |
|
|
=head1 DESCRIPTION |
18 |
|
|
|
19 |
|
|
=over 4 |
20 |
|
|
|
21 |
|
|
=cut |
22 |
|
|
|
23 |
|
|
package Coro::Semaphore; |
24 |
|
|
|
25 |
|
|
use Coro::Process (); |
26 |
|
|
|
27 |
|
|
$VERSION = 0.01; |
28 |
|
|
|
29 |
root |
1.3 |
=item new [inital count, default zero] |
30 |
|
|
|
31 |
|
|
Creates a new sempahore object with the given initial lock count. The |
32 |
|
|
default lock count is 1, which means it is unlocked by default. |
33 |
|
|
|
34 |
|
|
=cut |
35 |
|
|
|
36 |
root |
1.1 |
sub new { |
37 |
root |
1.2 |
bless [defined $_[1] ? $_[1] : 1], $_[0]; |
38 |
root |
1.1 |
} |
39 |
|
|
|
40 |
root |
1.3 |
=item $sem->down |
41 |
|
|
|
42 |
|
|
Decrement the counter, therefore "locking" the semaphore. This method |
43 |
|
|
waits until the semaphore is available if the counter is zero. |
44 |
|
|
|
45 |
|
|
=cut |
46 |
|
|
|
47 |
root |
1.1 |
sub down { |
48 |
|
|
my $self = shift; |
49 |
|
|
while ($self->[0] <= 0) { |
50 |
|
|
push @{$self->[1]}, $Coro::current; |
51 |
|
|
Coro::Process::schedule; |
52 |
|
|
} |
53 |
|
|
--$self->[0]; |
54 |
|
|
} |
55 |
|
|
|
56 |
root |
1.3 |
=item $sem->up |
57 |
|
|
|
58 |
|
|
Unlock the semaphore again. |
59 |
|
|
|
60 |
|
|
=cut |
61 |
|
|
|
62 |
root |
1.1 |
sub up { |
63 |
|
|
my $self = shift; |
64 |
root |
1.2 |
if (++$self->[0] > 0) { |
65 |
root |
1.1 |
(shift @{$self->[1]})->ready if @{$self->[1]}; |
66 |
|
|
} |
67 |
|
|
} |
68 |
root |
1.3 |
|
69 |
|
|
=item $sem->try |
70 |
|
|
|
71 |
|
|
Try to C<down> the semaphore. Returns true when this was possible, |
72 |
|
|
otherwise return false and leave the semaphore unchanged. |
73 |
|
|
|
74 |
|
|
=cut |
75 |
root |
1.1 |
|
76 |
|
|
sub try { |
77 |
|
|
my $self = shift; |
78 |
|
|
if ($self->[0] > 0) { |
79 |
|
|
--$self->[0]; |
80 |
|
|
return 1; |
81 |
|
|
} else { |
82 |
|
|
return 0; |
83 |
|
|
} |
84 |
|
|
} |
85 |
|
|
|
86 |
|
|
1; |
87 |
|
|
|
88 |
|
|
=back |
89 |
|
|
|
90 |
|
|
=head1 AUTHOR |
91 |
|
|
|
92 |
|
|
Marc Lehmann <pcg@goof.com> |
93 |
|
|
http://www.goof.com/pcg/marc/ |
94 |
|
|
|
95 |
|
|
=cut |
96 |
|
|
|