NAME¶
IPC::Semaphore - SysV Semaphore IPC object class
SYNOPSIS¶
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;
DESCRIPTION¶
A class providing an object based interface to SysV IPC semaphores.
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. 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 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
SEE ALSO¶
IPC::SysV, Class::Struct, semget, semctl, semop
AUTHORS¶
Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz <mhx@cpan.org>
COPYRIGHT¶
Version 2.x, Copyright (C) 2007-2010, 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.