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Comparing Coro/Coro/Semaphore.pm (file contents):
Revision 1.6 by root, Tue Jul 17 15:42:28 2001 UTC vs.
Revision 1.20 by root, Mon Sep 24 00:51:19 2001 UTC

… …
14 14
15 $sig->up; 15 $sig->up;
16 16
17=head1 DESCRIPTION 17=head1 DESCRIPTION
18 18
19This module implements counting semaphores. You can initialize a mutex
20with any level of parallel users, that is, you can intialize a sempahore
21that can be C<down>ed more than once until it blocks. There is no owner
22associated with semaphores, so one coroutine can C<down> it while another
23can C<up> it.
24
25Counting semaphores are typically used to coordinate access to
26resources, with the semaphore count initialized to the number of free
27resources. Coroutines then increment the count when resources are added
28and decrement the count when resources are removed.
29
19=over 4 30=over 4
20 31
21=cut 32=cut
22 33
23package Coro::Semaphore; 34package Coro::Semaphore;
24 35
36no warnings;
37
25use Coro (); 38use Coro ();
26 39
27$VERSION = 0.07; 40$VERSION = 0.5;
28 41
29=item new [inital count, default zero] 42=item new [inital count]
30 43
31Creates a new sempahore object with the given initial lock count. The 44Creates a new sempahore object with the given initial lock count. The
32default lock count is 1, which means it is unlocked by default. 45default lock count is 1, which means it is unlocked by default. Zero (or
46negative values) are also allowed, in which case the semaphore is locked
47by default.
33 48
34=cut 49=cut
35 50
36sub new { 51sub new {
37 bless [defined $_[1] ? $_[1] : 1], $_[0]; 52 bless [defined $_[1] ? $_[1] : 1], $_[0];
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43waits until the semaphore is available if the counter is zero. 58waits until the semaphore is available if the counter is zero.
44 59
45=cut 60=cut
46 61
47sub down { 62sub down {
48 my $self = shift;
49 while ($self->[0] <= 0) { 63 while ($_[0][0] <= 0) {
50 push @{$self->[1]}, $Coro::current; 64 push @{$_[0][1]}, $Coro::current;
51 Coro::schedule; 65 Coro::schedule;
52 } 66 }
53 --$self->[0]; 67 --$_[0][0];
54} 68}
55 69
56=item $sem->up 70=item $sem->up
57 71
58Unlock the semaphore again. 72Unlock the semaphore again.
59 73
60=cut 74=cut
61 75
62sub up { 76sub up {
63 my $self = shift;
64 if (++$self->[0] > 0) { 77 if (++$_[0][0] > 0) {
65 (shift @{$self->[1]})->ready if @{$self->[1]}; 78 (shift @{$_[0][1]})->ready if @{$_[0][1]};
66 } 79 }
67} 80}
68 81
69=item $sem->try 82=item $sem->try
70 83
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72otherwise return false and leave the semaphore unchanged. 85otherwise return false and leave the semaphore unchanged.
73 86
74=cut 87=cut
75 88
76sub try { 89sub try {
77 my $self = shift;
78 if ($self->[0] > 0) { 90 if ($_[0][0] > 0) {
79 --$self->[0]; 91 --$_[0][0];
80 return 1; 92 return 1;
81 } else { 93 } else {
82 return 0; 94 return 0;
83 } 95 }
96}
97
98=item $sem->waiters
99
100In scalar context, returns the number of coroutines waiting for this
101semaphore.
102
103=cut
104
105sub waiters {
106 @{$_[0][1]};
107}
108
109=item $guard = $sem->guard
110
111This method calls C<down> and then creates a guard object. When the guard
112object is destroyed it automatically calls C<up>.
113
114=cut
115
116sub guard {
117 &down;
118 # double indirection because bless works on the referenced
119 # object, not (only) on the reference itself.
120 bless \\$_[0], Coro::Semaphore::Guard::;
121}
122
123sub Coro::Semaphore::Guard::DESTROY {
124 &up(${${$_[0]}});
84} 125}
85 126
861; 1271;
87 128
88=back 129=back

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