IPC::Semaphore

IPC::Semaphore(3)      Perl Programmers Reference Guide      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.




























3rd Berkeley Distribution    perl 5.005, patch 02            IPC::Semaphore(3)