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

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.

getall
    Returns the values of the semaphore set as an array.

getncnt ( SEM )
    Returns the number of processed waiting for the semaphore SEM to become greater than it's 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 processed 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 the semop manpage 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 (oly 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 you system documentation.

        uid
        gid
        cuid
        cgid
        mode
        ctime
        otime
        nsems

SEE ALSO
the IPC::SysV manpage the Class::Struct manpage the semget manpage the semctl manpage the semop manpage

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.