IPC::Semaphore

See the current Perl documentation for IPC::Semaphore.

Here is our local, out-dated (pre-5.6) version:

IPC::Semaphore - SysV Semaphore IPC object class

    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-&g
    

    


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 <EM>FLAGS</EM> & 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.

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 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 (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.


    uid
    gid
    cuid
    cgid
    mode
    ctime
    otime
    nsems




SEE ALSO

SysV  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.