IPC::Semaphore(3perl) Perl Programmers Reference Guide IPC::Semaphore(3perl)
NAME
IPC::Semaphore - SysV Semaphore IPC object class
SYNOPSIS
use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR IPC_CREAT);
use IPC::Semaphore;
$sem = IPC::Semaphore->new(IPC_PRIVATE, 10, S_IRUSR | S_IWUSR | IPC_CREAT);
$sem->setall( (0) x 10);
@sem = $sem->getall;
$ncnt = $sem->getncnt;
$zcnt = $sem->getzcnt;
$ds = $sem->stat;
$sem->remove;
DESCRIPTION
A class providing an object based interface to SysV IPC semaphores.
METHODS
new ( KEY , NSEMS , FLAGS )
Create a new semaphore set associated with "KEY". "NSEMS" is the
number of semaphores in the set. A new set is created if
• "KEY" is equal to "IPC_PRIVATE"
• "KEY" does not already have a semaphore identifier associated
with it, and "FLAGS & IPC_CREAT" is true.
On creation of a new semaphore set "FLAGS" is used to set the
permissions. Be careful not to set any flags that the Sys V IPC
implementation does not allow: in some systems setting execute bits
makes the operations fail.
getall
Returns the values of the semaphore set as an array.
getncnt ( SEM )
Returns the number of processes waiting for the semaphore "SEM" to
become greater than its current value
getpid ( SEM )
Returns the process id of the last process that performed an
operation on the semaphore "SEM".
getval ( SEM )
Returns the current value of the semaphore "SEM".
getzcnt ( SEM )
Returns the number of processes waiting for the semaphore "SEM" to
become zero.
id Returns the system identifier for the semaphore set.
op ( OPLIST )
"OPLIST" is a list of operations to pass to "semop". "OPLIST" is a
concatenation of smaller lists, each which has three values. The
first is the semaphore number, the second is the operation and the
last is a flags value. See semop(2) for more details. For example
$sem->op(
0, -1, IPC_NOWAIT,
1, 1, IPC_NOWAIT
);
remove
Remove and destroy the semaphore set from the system.
set ( STAT )
set ( NAME => VALUE [, NAME => VALUE ...] )
"set" will set the following values of the "stat" structure
associated with the semaphore set.
uid
gid
mode (only the permission bits)
"set" accepts either a stat object, as returned by the "stat"
method, or a list of name-value pairs.
setall ( VALUES )
Sets all values in the semaphore set to those given on the "VALUES"
list. "VALUES" must contain the correct number of values.
setval ( N , VALUE )
Set the "N"th value in the semaphore set to "VALUE"
stat
Returns an object of type "IPC::Semaphore::stat" which is a sub-
class of "Class::Struct". It provides the following fields. For a
description of these fields see your system documentation.
uid
gid
cuid
cgid
mode
ctime
otime
nsems
SEE ALSO
IPC::SysV, Class::Struct, semget(2), semctl(2), semop(2)
AUTHORS
Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz <mhx@cpan.org>
COPYRIGHT
Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz.
Version 1.x, Copyright (c) 1997, Graham Barr.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.40.1 2026-08-30 IPC::Semaphore(3perl)
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