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14 | |
14 | |
15 | $sig->up; |
15 | $sig->up; |
16 | |
16 | |
17 | =head1 DESCRIPTION |
17 | =head1 DESCRIPTION |
18 | |
18 | |
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19 | This module implements counted semaphores. You can initialize a mutex |
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20 | with any level of parallel users, that is, you can intialize a sempahore |
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21 | that can be C<down>ed more than once until it blocks. There is no owner |
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22 | associated with semaphores, so one coroutine can C<down> it while another |
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23 | can C<up> it. |
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24 | |
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25 | Counting semaphores are typically used to coordinate access to |
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26 | resources, with the semaphore count initialized to the number of free |
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27 | resources. Coroutines then increment the count when resources are added |
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28 | and decrement the count when resources are removed. |
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29 | |
19 | =over 4 |
30 | =over 4 |
20 | |
31 | |
21 | =cut |
32 | =cut |
22 | |
33 | |
23 | package Coro::Semaphore; |
34 | package Coro::Semaphore; |
24 | |
35 | |
25 | use Coro::Process (); |
36 | use Coro (); |
26 | |
37 | |
27 | $VERSION = 0.01; |
38 | $VERSION = 0.12; |
28 | |
39 | |
29 | =item new [inital count, default zero] |
40 | =item new [inital count, default one] |
30 | |
41 | |
31 | Creates a new sempahore object with the given initial lock count. The |
42 | 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. |
43 | default lock count is 1, which means it is unlocked by default. Zero (or |
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44 | negative values) are also allowed, in which case the semaphore is locked |
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45 | by default. |
33 | |
46 | |
34 | =cut |
47 | =cut |
35 | |
48 | |
36 | sub new { |
49 | sub new { |
37 | bless [defined $_[1] ? $_[1] : 1], $_[0]; |
50 | bless [defined $_[1] ? $_[1] : 1], $_[0]; |
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45 | =cut |
58 | =cut |
46 | |
59 | |
47 | sub down { |
60 | sub down { |
48 | my $self = shift; |
61 | my $self = shift; |
49 | while ($self->[0] <= 0) { |
62 | while ($self->[0] <= 0) { |
50 | push @{$self->[1]}, $Coro::Process::current; |
63 | push @{$self->[1]}, $Coro::current; |
51 | Coro::Process::schedule; |
64 | Coro::schedule; |
52 | } |
65 | } |
53 | --$self->[0]; |
66 | --$self->[0]; |
54 | } |
67 | } |
55 | |
68 | |
56 | =item $sem->up |
69 | =item $sem->up |