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IPC::Semaphore(3pm)    Perl Programmers Reference Guide    IPC::Semaphore(3pm)




NAME

       IPC::Semaphore - SysV Semaphore IPC object class


SYNOPSIS

           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;


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

           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.  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


SEE ALSO

       IPC::SysV(3), Class::Struct(3), semget(3), semctl(3), semop(3)


AUTHORS

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


COPYRIGHT

       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.



perl v5.26.1                      2017-07-18               IPC::Semaphore(3pm)

perl 5.26.1 - Generated Sun Nov 5 16:05:20 CST 2017
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