Manpages - IPC_Semaphore.3perl

IPC::Semaphore - SysV Semaphore IPC object class

use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR IPC_CREAT); use IPC::Semaphore; $sem = IPC::Semaphore->new(IPC_PRIVATE, 10, S_IRUSR | S_IWUSR | 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. Be careful not to set any flags that the Sys V IPC implementation does not allow: in some systems setting execute bits makes the operations fail.

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 (2) 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 N=th 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 (2), semctl (2), semop (2)

Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz <mhx@cpan.org>

Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz.

Version 1.x, Copyright (c) 1997, Graham Barr.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.