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Comparing Coro/Coro/Semaphore.pm (file contents):
Revision 1.23 by root, Tue Nov 6 20:34:11 2001 UTC vs.
Revision 1.82 by root, Wed Nov 19 11:11:10 2008 UTC

… …
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$VERSION = 0.52; 40$VERSION = 5.0;
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
64=item $sem->wait
65
66Similar to C<down>, but does not actually decrement the counter. Instead,
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.
86
60=cut 87=cut
61 88
62sub down { 89#=item $status = $sem->timed_down ($timeout)
90#
91#Like C<down>, but returns false if semaphore couldn't be acquired within
92#$timeout seconds, otherwise true.
93
94#sub timed_down {
95# require Coro::Timer;
96# my $timeout = Coro::Timer::timeout ($_[1]);
97#
63 while ($_[0][0] <= 0) { 98# while ($_[0][0] <= 0) {
64 push @{$_[0][1]}, $Coro::current; 99# push @{$_[0][1]}, $Coro::current;
65 Coro::schedule; 100# &Coro::schedule;
101# if ($timeout) {
102# # ugly as hell. slow, too, btw!
103# for (0..$#{$_[0][1]}) {
104# if ($_[0][1][$_] == $Coro::current) {
105# splice @{$_[0][1]}, $_, 1;
106# return;
107# }
108# }
109# die;
110# }
66 } 111# }
112#
67 --$_[0][0]; 113# --$_[0][0];
68} 114# return 1;
115#}
69 116
70=item $sem->up 117=item $sem->up
71 118
72Unlock the semaphore again. 119Unlock the semaphore again.
73
74=cut
75
76sub up {
77 if (++$_[0][0] > 0) {
78 (shift @{$_[0][1]})->ready if @{$_[0][1]};
79 }
80}
81 120
82=item $sem->try 121=item $sem->try
83 122
84Try to C<down> the semaphore. Returns true when this was possible, 123Try to C<down> the semaphore. Returns true when this was possible,
85otherwise return false and leave the semaphore unchanged. 124otherwise return false and leave the semaphore unchanged.
86 125
87=cut
88
89sub try {
90 if ($_[0][0] > 0) {
91 --$_[0][0];
92 return 1;
93 } else {
94 return 0;
95 }
96}
97
98=item $sem->waiters 126=item $sem->waiters
99 127
100In scalar context, returns the number of coroutines waiting for this 128In scalar context, returns the number of coroutines waiting for this
101semaphore. 129semaphore.
102
103=cut
104
105sub waiters {
106 @{$_[0][1]};
107}
108 130
109=item $guard = $sem->guard 131=item $guard = $sem->guard
110 132
111This method calls C<down> and then creates a guard object. When the guard 133This method calls C<down> and then creates a guard object. When the guard
112object is destroyed it automatically calls C<up>. 134object is destroyed it automatically calls C<up>.
… …
115 137
116sub guard { 138sub guard {
117 &down; 139 &down;
118 # double indirection because bless works on the referenced 140 # double indirection because bless works on the referenced
119 # object, not (only) on the reference itself. 141 # object, not (only) on the reference itself.
120 bless \\$_[0], Coro::Semaphore::Guard::; 142 bless \\$_[0], Coro::Semaphore::guard::;
121} 143}
122 144
145#=item $guard = $sem->timed_guard ($timeout)
146#
147#Like C<guard>, but returns undef if semaphore couldn't be acquired within
148#$timeout seconds, otherwise the guard object.
149
150#sub timed_guard {
151# &timed_down
152# ? bless \\$_[0], Coro::Semaphore::guard::
153# : ();
154#}
155
123sub Coro::Semaphore::Guard::DESTROY { 156sub Coro::Semaphore::guard::DESTROY {
124 &up(${${$_[0]}}); 157 &up(${${$_[0]}});
125} 158}
126
1271;
128 159
129=back 160=back
130 161
131=head1 AUTHOR 162=head1 AUTHOR
132 163
133 Marc Lehmann <pcg@goof.com> 164 Marc Lehmann <schmorp@schmorp.de>
134 http://www.goof.com/pcg/marc/ 165 http://home.schmorp.de/
135 166
136=cut 167=cut
137 168
1691
170

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