---

Manual Reference Pages  - IPC::Semaphore (3pm)

---

IPC::Semaphore - SysV Semaphore IPC object class

CONTENTS

    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;

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

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.
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 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 Nth 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

IPC::SysV Class::Struct semget semctl semop

Graham Barr <gbarr@pobox.com>

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.

Jump to page    or go to Top of page |  Section 3pm |  Main Index.