ipc::semaphore(3)
NAME
IPC::Semaphore - SysV Semaphore IPC object class
SYNOPSIS
use IPC::SysV qw(IPC_PRIVATE S_IRWXU IPC_CREAT); use IPC::Semaphore; $sem = new IPC::Semaphore(IPC_PRIVATE, 10, S_IRWXU 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 iden
tifier associated with it, and "FLAGS & IPC_CREAT"
is true. - On creation of a new semaphore set "FLAGS" is used to
set the permissions. - 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 per
formed 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 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 semctl semop
AUTHOR
Graham Barr <gbarr@pobox.com>
COPYRIGHT
- Copyright (c) 1997 Graham Barr. All rights reserved. This
program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.