IPC::SemaphoreSection: Perl Programmers Reference Guide (3)
Index Return to Main Contents
NAMEIPC::Semaphore - SysV Semaphore IPC object class
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;
DESCRIPTIONA 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.
- 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.
- 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 for more details. For example
$sem->op( 0, -1, IPC_NOWAIT, 1, 1, IPC_NOWAIT );
- 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"
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
SEE ALSOIPC::SysV Class::Struct semget semctl semop
AUTHORGraham Barr <email@example.com>
COPYRIGHTCopyright (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.