ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro/Coro/Semaphore.pm
(Generate patch)

Comparing Coro/Coro/Semaphore.pm (file contents):
Revision 1.34 by root, Thu May 8 00:55:30 2003 UTC vs.
Revision 1.92 by root, Fri May 29 07:01:18 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3Coro::Semaphore - non-binary semaphores 3Coro::Semaphore - counting semaphores
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use Coro::Semaphore; 7 use Coro::Semaphore;
8 8
… …
31 31
32=cut 32=cut
33 33
34package Coro::Semaphore; 34package Coro::Semaphore;
35 35
36no warnings qw(uninitialized); 36no warnings;
37 37
38use Coro (); 38use Coro ();
39 39
40$VERSION = 0.652; 40$VERSION = 5.132;
41 41
42=item new [inital count] 42=item new [inital count]
43 43
44Creates a new sempahore object with the given initial lock count. The 44Creates a new sempahore object with the given initial lock count. The
45default lock count is 1, which means it is unlocked by default. Zero (or 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 46negative values) are also allowed, in which case the semaphore is locked
47by default. 47by default.
48 48
49=cut 49=item $sem->count
50 50
51sub new { 51Returns the current semaphore count.
52 bless [defined $_[1] ? $_[1] : 1], $_[0]; 52
53} 53=item $sem->adjust ($diff)
54
55Atomically adds the amount given to the current semaphore count. If the
56count becomes positive, wakes up any waiters. Does not block if the count
57becomes negative, however.
54 58
55=item $sem->down 59=item $sem->down
56 60
57Decrement the counter, therefore "locking" the semaphore. This method 61Decrement the counter, therefore "locking" the semaphore. This method
58waits until the semaphore is available if the counter is zero. 62waits until the semaphore is available if the counter is zero.
59 63
60=item $status = $sem->timed_down($timeout) 64=item $sem->wait
61 65
62Like C<down>, but returns false if semaphore couldn't be acquired within 66Similar to C<down>, but does not actually decrement the counter. Instead,
63$timeout seconds, otherwise true. 67when this function returns, a following call to C<down> or C<try> is
68guaranteed to succeed without blocking, until the next coroutine switch
69(C<cede> etc.).
70
71Note that using C<wait> is much less efficient than using C<down>, so try
72to prefer C<down> whenever possible.
73
74=item $sem->wait ($callback)
75
76If you pass a callback argument to C<wait>, it will not wait, but
77immediately return. The callback will be called as soon as the semaphore
78becomes available (which might be instantly), and gets passed the
79semaphore as first argument.
80
81The callback might C<down> the semaphore exactly once, might wake up other
82coroutines, but is I<NOT> allowed to block (switch to other coroutines).
83
84This is considered a rather experimental interface, and is subject to
85change.
64 86
65=cut 87=cut
66 88
67sub down { 89#=item $status = $sem->timed_down ($timeout)
68 while ($_[0][0] <= 0) { 90#
69 push @{$_[0][1]}, $Coro::current; 91#Like C<down>, but returns false if semaphore couldn't be acquired within
70 Coro::schedule; 92#$timeout seconds, otherwise true.
71 }
72 --$_[0][0];
73}
74 93
75sub timed_down { 94#sub timed_down {
76 require Coro::Timer; 95# require Coro::Timer;
77 my $timeout = Coro::Timer::timeout($_[1]); 96# my $timeout = Coro::Timer::timeout ($_[1]);
78 97#
79 while ($_[0][0] <= 0) { 98# while ($_[0][0] <= 0) {
80 push @{$_[0][1]}, $Coro::current; 99# push @{$_[0][1]}, $Coro::current;
81 Coro::schedule; 100# &Coro::schedule;
82 if ($timeout) { 101# if ($timeout) {
83 # ugly as hell. slow, too, btw! 102# # ugly as hell. slow, too, btw!
84 for (0..$#{$_[0][1]}) { 103# for (0..$#{$_[0][1]}) {
85 if ($_[0][1][$_] == $Coro::current) { 104# if ($_[0][1][$_] == $Coro::current) {
86 splice @{$_[0][1]}, $_, 1; 105# splice @{$_[0][1]}, $_, 1;
87 return; 106# return;
88 } 107# }
89 } 108# }
90 die; 109# die;
91 } 110# }
92 } 111# }
93 112#
94 --$_[0][0]; 113# --$_[0][0];
95 return 1; 114# return 1;
96} 115#}
97 116
98=item $sem->up 117=item $sem->up
99 118
100Unlock the semaphore again. 119Unlock the semaphore again.
101
102=cut
103
104sub up {
105 if (++$_[0][0] > 0) {
106 (shift @{$_[0][1]})->ready if @{$_[0][1]};
107 }
108}
109 120
110=item $sem->try 121=item $sem->try
111 122
112Try to C<down> the semaphore. Returns true when this was possible, 123Try to C<down> the semaphore. Returns true when this was possible,
113otherwise return false and leave the semaphore unchanged. 124otherwise return false and leave the semaphore unchanged.
114 125
115=cut
116
117sub try {
118 if ($_[0][0] > 0) {
119 --$_[0][0];
120 return 1;
121 } else {
122 return 0;
123 }
124}
125
126=item $sem->waiters 126=item $sem->waiters
127 127
128In scalar context, returns the number of coroutines waiting for this 128In scalar context, returns the number of coroutines waiting for this
129semaphore. 129semaphore.
130
131=cut
132
133sub waiters {
134 @{$_[0][1]};
135}
136 130
137=item $guard = $sem->guard 131=item $guard = $sem->guard
138 132
139This method calls C<down> and then creates a guard object. When the guard 133This method calls C<down> and then creates a guard object. When the guard
140object is destroyed it automatically calls C<up>. 134object is destroyed it automatically calls C<up>.
141 135
142=item $guard = $sem->timed_guard($timeout)
143
144Like C<guard>, but returns undef if semaphore couldn't be acquired within
145$timeout seconds, otherwise the guard object.
146
147=cut 136=cut
148 137
149sub guard { 138sub guard {
150 &down; 139 &down;
151 # double indirection because bless works on the referenced
152 # object, not (only) on the reference itself.
153 bless \\$_[0], Coro::Semaphore::guard::; 140 bless [$_[0]], Coro::Semaphore::guard::
154} 141}
155 142
143#=item $guard = $sem->timed_guard ($timeout)
144#
145#Like C<guard>, but returns undef if semaphore couldn't be acquired within
146#$timeout seconds, otherwise the guard object.
147
156sub timed_guard { 148#sub timed_guard {
157 &timed_down 149# &timed_down
158 ? bless \\$_[0], Coro::Semaphore::guard:: 150# ? bless \\$_[0], Coro::Semaphore::guard::
159 : (); 151# : ();
160} 152#}
161 153
162sub Coro::Semaphore::guard::DESTROY { 154sub Coro::Semaphore::guard::DESTROY {
163 &up(${${$_[0]}}); 155 &up($_[0][0]);
164} 156}
165
1661;
167 157
168=back 158=back
169 159
170=head1 AUTHOR 160=head1 AUTHOR
171 161
172 Marc Lehmann <pcg@goof.com> 162 Marc Lehmann <schmorp@schmorp.de>
173 http://www.goof.com/pcg/marc/ 163 http://home.schmorp.de/
174 164
175=cut 165=cut
176 166
1671
168

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines