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.IX Title "IPC::Semaphore 3"
.TH IPC::Semaphore 3 "2002-06-01" "perl v5.8.0" "Perl Programmers Reference Guide"
IPC::Semaphore \- SysV Semaphore IPC object class
\& use IPC::SysV qw(IPC_PRIVATE S_IRWXU IPC_CREAT);
\& $sem = new IPC::Semaphore(IPC_PRIVATE, 10, S_IRWXU | IPC_CREAT);
\& $sem->setall( (0) x 10);
\& $ncnt = $sem->getncnt;
\& $zcnt = $sem->getzcnt;
A class providing an object based interface to SysV \s-1IPC\s0 semaphores.
.IP "new ( \s-1KEY\s0 , \s-1NSEMS\s0 , \s-1FLAGS\s0 )" 4
.IX Item "new ( KEY , NSEMS , FLAGS )"
Create a new semaphore set associated with \f(CW\*(C`KEY\*(C'\fR. \f(CW\*(C`NSEMS\*(C'\fR is the number
of semaphores in the set. A new set is created if
\&\f(CW\*(C`KEY\*(C'\fR is equal to \f(CW\*(C`IPC_PRIVATE\*(C'\fR
\&\f(CW\*(C`KEY\*(C'\fR does not already have a semaphore identifier
associated with it, and \f(CW\*(C`\f(CI\s-1FLAGS\s0\f(CW & IPC_CREAT\*(C'\fR is true.
On creation of a new semaphore set \f(CW\*(C`FLAGS\*(C'\fR is used to set the
Returns the values of the semaphore set as an array.
.IP "getncnt ( \s-1SEM\s0 )" 4
.IX Item "getncnt ( SEM )"
Returns the number of processes waiting for the semaphore \f(CW\*(C`SEM\*(C'\fR to
become greater than its current value
.IP "getpid ( \s-1SEM\s0 )" 4
.IX Item "getpid ( SEM )"
Returns the process id of the last process that performed an operation
on the semaphore \f(CW\*(C`SEM\*(C'\fR.
.IP "getval ( \s-1SEM\s0 )" 4
.IX Item "getval ( SEM )"
Returns the current value of the semaphore \f(CW\*(C`SEM\*(C'\fR.
.IP "getzcnt ( \s-1SEM\s0 )" 4
.IX Item "getzcnt ( SEM )"
Returns the number of processes waiting for the semaphore \f(CW\*(C`SEM\*(C'\fR to
Returns the system identifier for the semaphore set.
.IP "op ( \s-1OPLIST\s0 )" 4
\&\f(CW\*(C`OPLIST\*(C'\fR is a list of operations to pass to \f(CW\*(C`semop\*(C'\fR. \f(CW\*(C`OPLIST\*(C'\fR 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
Remove and destroy the semaphore set from the system.
.IP "set ( \s-1STAT\s0 )" 4
.IP "set ( \s-1NAME\s0 => \s-1VALUE\s0 [, \s-1NAME\s0 => \s-1VALUE\s0 ...] )" 4
.IX Item "set ( NAME => VALUE [, NAME => VALUE ...] )"
\&\f(CW\*(C`set\*(C'\fR will set the following values of the \f(CW\*(C`stat\*(C'\fR structure associated
\& mode (only the permission bits)
\&\f(CW\*(C`set\*(C'\fR accepts either a stat object, as returned by the \f(CW\*(C`stat\*(C'\fR method,
or a list of \fIname\fR\-\fIvalue\fR pairs.
.IP "setall ( \s-1VALUES\s0 )" 4
.IX Item "setall ( VALUES )"
Sets all values in the semaphore set to those given on the \f(CW\*(C`VALUES\*(C'\fR list.
\&\f(CW\*(C`VALUES\*(C'\fR must contain the correct number of values.
.IP "setval ( N , \s-1VALUE\s0 )" 4
.IX Item "setval ( N , VALUE )"
Set the \f(CW\*(C`N\*(C'\fRth value in the semaphore set to \f(CW\*(C`VALUE\*(C'\fR
Returns an object of type \f(CW\*(C`IPC::Semaphore::stat\*(C'\fR which is a sub-class of
\&\f(CW\*(C`Class::Struct\*(C'\fR. It provides the following fields. For a description
of these fields see your system documentation.
IPC::SysV Class::Struct semget semctl semop
Graham Barr <gbarr@pobox.com>
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.