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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

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

SysV Struct 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.


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