IPC::Semaphore(3)Perl Programmers Reference GuidIPC::Semaphore(3)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;
DESCRIPTIONMETHODS
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
o KEY is equal to IPC_PRIVATE
o 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.
getall
Returns the values of the semaphore set as an array.
getncnt ( SEM )
Returns the number of processed waiting for the
semaphore SEM to become greater than it's 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.
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getzcnt ( SEM )
Returns the number of processed 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 the semop manpage 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 (oly 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 Nth 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 you system documentation.
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uid
gid
cuid
cgid
mode
ctime
otime
nsems
SEE ALSO
the IPC::SysV manpage the Class::Struct manpage the semget
manpage the semctl manpage the semop manpage
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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