IPC::Semaphore(3pPerl Programmers Reference GuiIPC::Semaphore(3p)NAMEIPC::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
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 identif-
ier 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 processes waiting for the sema-
phore "SEM" to become greater than its current value
getpid ( SEM )
Returns the process id of the last process that per-
formed an operation on the semaphore "SEM".
getval ( SEM )
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Returns the current value of the semaphore "SEM".
getzcnt ( SEM )
Returns the number of processes waiting for the sema-
phore "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" struc-
ture 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 fol-
lowing fields. For a description of these fields see
your system documentation.
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uid
gid
cuid
cgid
mode
ctime
otime
nsems
SEE ALSO
IPC::SysV Class::Struct semget semctl semop
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.
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