… | |
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14 | |
14 | |
15 | $sig->up; |
15 | $sig->up; |
16 | |
16 | |
17 | =head1 DESCRIPTION |
17 | =head1 DESCRIPTION |
18 | |
18 | |
19 | This module implements counted semaphores. You can initialize a mutex |
19 | This module implements counting semaphores. You can initialize a mutex |
20 | with any level of parallel users, that is, you can intialize a sempahore |
20 | with any level of parallel users, that is, you can intialize a sempahore |
21 | that can be C<down>ed more than once until it blocks. There is no owner |
21 | that can be C<down>ed more than once until it blocks. There is no owner |
22 | associated with semaphores, so one coroutine can C<down> it while another |
22 | associated with semaphores, so one coroutine can C<down> it while another |
23 | can C<up> it. |
23 | can C<up> it. |
24 | |
24 | |
… | |
… | |
31 | |
31 | |
32 | =cut |
32 | =cut |
33 | |
33 | |
34 | package Coro::Semaphore; |
34 | package Coro::Semaphore; |
35 | |
35 | |
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36 | BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") } |
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37 | |
36 | use Coro (); |
38 | use Coro (); |
37 | |
39 | |
38 | $VERSION = 0.45; |
40 | $VERSION = 0.95; |
39 | |
41 | |
40 | =item new [inital count, default one] |
42 | =item new [inital count] |
41 | |
43 | |
42 | Creates a new sempahore object with the given initial lock count. The |
44 | Creates a new sempahore object with the given initial lock count. The |
43 | default lock count is 1, which means it is unlocked by default. Zero (or |
45 | default lock count is 1, which means it is unlocked by default. Zero (or |
44 | negative values) are also allowed, in which case the semaphore is locked |
46 | negative values) are also allowed, in which case the semaphore is locked |
45 | by default. |
47 | by default. |
… | |
… | |
53 | =item $sem->down |
55 | =item $sem->down |
54 | |
56 | |
55 | Decrement the counter, therefore "locking" the semaphore. This method |
57 | Decrement the counter, therefore "locking" the semaphore. This method |
56 | waits until the semaphore is available if the counter is zero. |
58 | waits until the semaphore is available if the counter is zero. |
57 | |
59 | |
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60 | =item $status = $sem->timed_down($timeout) |
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61 | |
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62 | Like C<down>, but returns false if semaphore couldn't be acquired within |
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63 | $timeout seconds, otherwise true. |
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64 | |
58 | =cut |
65 | =cut |
59 | |
66 | |
60 | sub down { |
67 | sub down { |
61 | my $self = shift; |
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62 | while ($self->[0] <= 0) { |
68 | while ($_[0][0] <= 0) { |
63 | push @{$self->[1]}, $Coro::current; |
69 | push @{$_[0][1]}, $Coro::current; |
64 | Coro::schedule; |
70 | Coro::schedule; |
65 | } |
71 | } |
66 | --$self->[0]; |
72 | --$_[0][0]; |
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73 | } |
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74 | |
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75 | sub timed_down { |
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76 | require Coro::Timer; |
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77 | my $timeout = Coro::Timer::timeout($_[1]); |
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78 | |
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79 | while ($_[0][0] <= 0) { |
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80 | push @{$_[0][1]}, $Coro::current; |
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81 | Coro::schedule; |
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82 | if ($timeout) { |
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83 | # ugly as hell. slow, too, btw! |
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84 | for (0..$#{$_[0][1]}) { |
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85 | if ($_[0][1][$_] == $Coro::current) { |
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86 | splice @{$_[0][1]}, $_, 1; |
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87 | return; |
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88 | } |
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89 | } |
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90 | die; |
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91 | } |
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92 | } |
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93 | |
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94 | --$_[0][0]; |
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95 | return 1; |
67 | } |
96 | } |
68 | |
97 | |
69 | =item $sem->up |
98 | =item $sem->up |
70 | |
99 | |
71 | Unlock the semaphore again. |
100 | Unlock the semaphore again. |
72 | |
101 | |
73 | =cut |
102 | =cut |
74 | |
103 | |
75 | sub up { |
104 | sub up { |
76 | my $self = shift; |
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77 | if (++$self->[0] > 0) { |
105 | if (++$_[0][0] > 0) { |
78 | (shift @{$self->[1]})->ready if @{$self->[1]}; |
106 | (shift @{$_[0][1]})->ready if @{$_[0][1]}; |
79 | } |
107 | } |
80 | } |
108 | } |
81 | |
109 | |
82 | =item $sem->try |
110 | =item $sem->try |
83 | |
111 | |
… | |
… | |
85 | otherwise return false and leave the semaphore unchanged. |
113 | otherwise return false and leave the semaphore unchanged. |
86 | |
114 | |
87 | =cut |
115 | =cut |
88 | |
116 | |
89 | sub try { |
117 | sub try { |
90 | my $self = shift; |
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91 | if ($self->[0] > 0) { |
118 | if ($_[0][0] > 0) { |
92 | --$self->[0]; |
119 | --$_[0][0]; |
93 | return 1; |
120 | return 1; |
94 | } else { |
121 | } else { |
95 | return 0; |
122 | return 0; |
96 | } |
123 | } |
|
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124 | } |
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125 | |
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126 | =item $sem->waiters |
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127 | |
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128 | In scalar context, returns the number of coroutines waiting for this |
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129 | semaphore. |
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130 | |
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131 | =cut |
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132 | |
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133 | sub waiters { |
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134 | @{$_[0][1]}; |
97 | } |
135 | } |
98 | |
136 | |
99 | =item $guard = $sem->guard |
137 | =item $guard = $sem->guard |
100 | |
138 | |
101 | This method calls C<down> and then creates a guard object. When the guard |
139 | This method calls C<down> and then creates a guard object. When the guard |
102 | object is destroyed it automatically calls C<up>. |
140 | object is destroyed it automatically calls C<up>. |
103 | |
141 | |
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142 | =item $guard = $sem->timed_guard($timeout) |
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143 | |
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144 | Like C<guard>, but returns undef if semaphore couldn't be acquired within |
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145 | $timeout seconds, otherwise the guard object. |
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146 | |
104 | =cut |
147 | =cut |
105 | |
148 | |
106 | sub guard { |
149 | sub guard { |
107 | $_[0]->down; |
150 | &down; |
108 | # double indirection because bless works on the referenced |
151 | # double indirection because bless works on the referenced |
109 | # object, not (only) on the reference itself. |
152 | # object, not (only) on the reference itself. |
110 | bless \\$_[0], Coro::Semaphore::Guard::; |
153 | bless \\$_[0], Coro::Semaphore::guard::; |
111 | } |
154 | } |
112 | |
155 | |
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156 | sub timed_guard { |
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157 | &timed_down |
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158 | ? bless \\$_[0], Coro::Semaphore::guard:: |
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159 | : (); |
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160 | } |
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161 | |
113 | sub Coro::Semaphore::Guard::DESTROY { |
162 | sub Coro::Semaphore::guard::DESTROY { |
114 | ${${$_[0]}}->up; |
163 | &up(${${$_[0]}}); |
115 | } |
164 | } |
116 | |
165 | |
117 | 1; |
166 | 1; |
118 | |
167 | |
119 | =back |
168 | =back |