IPC::Semaphore

Section: Perl Programmers Reference Guide (3)
Updated: perl 5.005, patch 02
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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
*
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.


 

Index

NAME
SYNOPSIS
DESCRIPTION
METHODS
SEE ALSO
AUTHOR
COPYRIGHT

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Time: 15:39:52 GMT, July 31, 2024