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.
- 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(2)
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
Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz
<mhx@cpan.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.