1IPC::Semaphore(3pm)    Perl Programmers Reference Guide    IPC::Semaphore(3pm)
2
3
4

NAME

6       IPC::Semaphore - SysV Semaphore IPC object class
7

SYNOPSIS

9           use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR IPC_CREAT);
10           use IPC::Semaphore;
11
12           $sem = IPC::Semaphore->new(IPC_PRIVATE, 10, S_IRUSR | S_IWUSR | IPC_CREAT);
13
14           $sem->setall( (0) x 10);
15
16           @sem = $sem->getall;
17
18           $ncnt = $sem->getncnt;
19
20           $zcnt = $sem->getzcnt;
21
22           $ds = $sem->stat;
23
24           $sem->remove;
25

DESCRIPTION

27       A class providing an object based interface to SysV IPC semaphores.
28

METHODS

30       new ( KEY , NSEMS , FLAGS )
31           Create a new semaphore set associated with "KEY". "NSEMS" is the
32           number of semaphores in the set. A new set is created if
33
34           ·   "KEY" is equal to "IPC_PRIVATE"
35
36           ·   "KEY" does not already have a semaphore identifier associated
37               with it, and "FLAGS & IPC_CREAT" is true.
38
39           On creation of a new semaphore set "FLAGS" is used to set the
40           permissions.  Be careful not to set any flags that the Sys V IPC
41           implementation does not allow: in some systems setting execute bits
42           makes the operations fail.
43
44       getall
45           Returns the values of the semaphore set as an array.
46
47       getncnt ( SEM )
48           Returns the number of processes waiting for the semaphore "SEM" to
49           become greater than its current value
50
51       getpid ( SEM )
52           Returns the process id of the last process that performed an
53           operation on the semaphore "SEM".
54
55       getval ( SEM )
56           Returns the current value of the semaphore "SEM".
57
58       getzcnt ( SEM )
59           Returns the number of processes waiting for the semaphore "SEM" to
60           become zero.
61
62       id  Returns the system identifier for the semaphore set.
63
64       op ( OPLIST )
65           "OPLIST" is a list of operations to pass to "semop". "OPLIST" is a
66           concatenation of smaller lists, each which has three values. The
67           first is the semaphore number, the second is the operation and the
68           last is a flags value. See semop for more details. For example
69
70               $sem->op(
71                   0, -1, IPC_NOWAIT,
72                   1,  1, IPC_NOWAIT
73               );
74
75       remove
76           Remove and destroy the semaphore set from the system.
77
78       set ( STAT )
79       set ( NAME => VALUE [, NAME => VALUE ...] )
80           "set" will set the following values of the "stat" structure
81           associated with the semaphore set.
82
83               uid
84               gid
85               mode (only the permission bits)
86
87           "set" accepts either a stat object, as returned by the "stat"
88           method, or a list of name-value pairs.
89
90       setall ( VALUES )
91           Sets all values in the semaphore set to those given on the "VALUES"
92           list.  "VALUES" must contain the correct number of values.
93
94       setval ( N , VALUE )
95           Set the "N"th value in the semaphore set to "VALUE"
96
97       stat
98           Returns an object of type "IPC::Semaphore::stat" which is a sub-
99           class of "Class::Struct". It provides the following fields. For a
100           description of these fields see your system documentation.
101
102               uid
103               gid
104               cuid
105               cgid
106               mode
107               ctime
108               otime
109               nsems
110

SEE ALSO

112       IPC::SysV, Class::Struct, semget, semctl, semop
113

AUTHORS

115       Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz <mhx@cpan.org>
116

118       Version 2.x, Copyright (C) 2007-2010, Marcus Holland-Moritz.
119
120       Version 1.x, Copyright (c) 1997, Graham Barr.
121
122       This program is free software; you can redistribute it and/or modify it
123       under the same terms as Perl itself.
124
125
126
127perl v5.16.3                      2013-03-04               IPC::Semaphore(3pm)
Impressum