|IPC::Semaphore(3perl)||Perl Programmers Reference Guide||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.
- 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
"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 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
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
uid gid cuid cgid mode ctime otime nsems
IPC::SysV, Class::Struct, semget(2), semctl(2), semop(2)
Graham Barr <email@example.com>, Marcus Holland-Moritz <firstname.lastname@example.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.