| 1 |
=head1 NAME |
| 2 |
|
| 3 |
Coro::Semaphore - non-binary semaphores |
| 4 |
|
| 5 |
=head1 SYNOPSIS |
| 6 |
|
| 7 |
use Coro::Semaphore; |
| 8 |
|
| 9 |
$sig = new Coro::Semaphore [initial value]; |
| 10 |
|
| 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 (); |
| 26 |
|
| 27 |
$VERSION = 0.08; |
| 28 |
|
| 29 |
=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 |
sub new { |
| 37 |
bless [defined $_[1] ? $_[1] : 1], $_[0]; |
| 38 |
} |
| 39 |
|
| 40 |
=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 |
sub down { |
| 48 |
my $self = shift; |
| 49 |
while ($self->[0] <= 0) { |
| 50 |
push @{$self->[1]}, $Coro::current; |
| 51 |
Coro::schedule; |
| 52 |
} |
| 53 |
--$self->[0]; |
| 54 |
} |
| 55 |
|
| 56 |
=item $sem->up |
| 57 |
|
| 58 |
Unlock the semaphore again. |
| 59 |
|
| 60 |
=cut |
| 61 |
|
| 62 |
sub up { |
| 63 |
my $self = shift; |
| 64 |
if (++$self->[0] > 0) { |
| 65 |
(shift @{$self->[1]})->ready if @{$self->[1]}; |
| 66 |
} |
| 67 |
} |
| 68 |
|
| 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 |
|
| 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 |
|
