—

              
################################################################################
#
#  Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz <mhx@cpan.org>.
#  Version 1.x, Copyright (C) 1997, Graham Barr <gbarr@pobox.com>.
#
#  This program is free software; you can redistribute it and/or
#  modify it under the same terms as Perl itself.
#
################################################################################
package IPC::Semaphore;
use IPC::SysV qw(GETNCNT GETZCNT GETVAL SETVAL GETPID GETALL SETALL
                 IPC_STAT IPC_SET IPC_RMID);
use strict;
use vars qw($VERSION);
use Carp;
$VERSION = '2.09';
# Figure out if we have support for native sized types
my $N = do { my $foo = eval { pack "L!", 0 }; $@ ? '' : '!' };
{
    package IPC::Semaphore::stat;
    use Class::Struct qw(struct);
    struct 'IPC::Semaphore::stat' => [
        uid     => '$',
        gid     => '$',
        cuid    => '$',
        cgid    => '$',
        mode    => '$',
        ctime   => '$',
        otime   => '$',
        nsems   => '$',
    ];
}
sub new {
    @_ == 4 || croak __PACKAGE__ . '->new( KEY, NSEMS, FLAGS )';
    my $class = shift;
    my $id = semget($_[0],$_[1],$_[2]);
    defined($id)
        ? bless \$id, $class
        : undef;
}
sub id {
    my $self = shift;
    $$self;
}
sub remove {
    my $self = shift;
    my $result = semctl($$self,0,IPC_RMID,0);
    undef $$self;
    $result;
}
sub getncnt {
    @_ == 2 || croak '$sem->getncnt( SEM )';
    my $self = shift;
    my $sem = shift;
    my $v = semctl($$self,$sem,GETNCNT,0);
    $v ? 0 + $v : undef;
}
sub getzcnt {
    @_ == 2 || croak '$sem->getzcnt( SEM )';
    my $self = shift;
    my $sem = shift;
    my $v = semctl($$self,$sem,GETZCNT,0);
    $v ? 0 + $v : undef;
}
sub getval {
    @_ == 2 || croak '$sem->getval( SEM )';
    my $self = shift;
    my $sem = shift;
    my $v = semctl($$self,$sem,GETVAL,0);
    $v ? 0 + $v : undef;
}
sub getpid {
    @_ == 2 || croak '$sem->getpid( SEM )';
    my $self = shift;
    my $sem = shift;
    my $v = semctl($$self,$sem,GETPID,0);
    $v ? 0 + $v : undef;
}
sub op {
    @_ >= 4 || croak '$sem->op( OPLIST )';
    my $self = shift;
    croak 'Bad arg count' if @_ % 3;
    my $data = pack("s$N*",@_);
    semop($$self,$data);
}
sub stat {
    my $self = shift;
    my $data = "";
    semctl($$self,0,IPC_STAT,$data)
        or return undef;
    IPC::Semaphore::stat->new->unpack($data);
}
sub set {
    my $self = shift;
    my $ds;
    if(@_ == 1) {
        $ds = shift;
    }
    else {
        croak 'Bad arg count' if @_ % 2;
        my %arg = @_;
        $ds = $self->stat
                or return undef;
        my($key,$val);
        $ds->$key($val)
            while(($key,$val) = each %arg);
    }
    my $v = semctl($$self,0,IPC_SET,$ds->pack);
    $v ? 0 + $v : undef;
}
sub getall {
    my $self = shift;
    my $data = "";
    semctl($$self,0,GETALL,$data)
        or return ();
    (unpack("s$N*",$data));
}
sub setall {
    my $self = shift;
    my $data = pack("s$N*",@_);
    semctl($$self,0,SETALL,$data);
}
sub setval {
    @_ == 3 || croak '$sem->setval( SEM, VAL )';
    my $self = shift;
    my $sem = shift;
    my $val = shift;
    semctl($$self,$sem,SETVAL,$val);
}
1;
__END__
HideShow 157 lines of Pod
=head1 NAME
IPC::Semaphore - SysV Semaphore IPC object class
=head1 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;
=head1 DESCRIPTION
A class providing an object based interface to SysV IPC semaphores.
=head1 METHODS
=over 4
=item new ( KEY , NSEMS , FLAGS )
Create a new semaphore set associated with C<KEY>. C<NSEMS> is the number
of semaphores in the set. A new set is created if
=over 4
=item *
C<KEY> is equal to C<IPC_PRIVATE>
=item *
C<KEY> does not already have a semaphore identifier
associated with it, and C<I<FLAGS> & IPC_CREAT> is true.
=back
On creation of a new semaphore set C<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.
=item getall
Returns the values of the semaphore set as an array.
=item getncnt ( SEM )
Returns the number of processes waiting for the semaphore C<SEM> to
become greater than its current value
=item getpid ( SEM )
Returns the process id of the last process that performed an operation
on the semaphore C<SEM>.
=item getval ( SEM )
Returns the current value of the semaphore C<SEM>.
=item getzcnt ( SEM )
Returns the number of processes waiting for the semaphore C<SEM> to
become zero.
=item id
Returns the system identifier for the semaphore set.
=item op ( OPLIST )
C<OPLIST> is a list of operations to pass to C<semop>. C<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 L<semop(2)> for more details. For example
    $sem->op(
        0, -1, IPC_NOWAIT,
        1,  1, IPC_NOWAIT
    );
=item remove
Remove and destroy the semaphore set from the system.
=item set ( STAT )
=item set ( NAME => VALUE [, NAME => VALUE ...] )
C<set> will set the following values of the C<stat> structure associated
with the semaphore set.
    uid
    gid
    mode (only the permission bits)
C<set> accepts either a stat object, as returned by the C<stat> method,
or a list of I<name>-I<value> pairs.
=item setall ( VALUES )
Sets all values in the semaphore set to those given on the C<VALUES> list.
C<VALUES> must contain the correct number of values.
=item setval ( N , VALUE )
Set the C<N>th value in the semaphore set to C<VALUE>
=item stat
Returns an object of type C<IPC::Semaphore::stat> which is a sub-class of
C<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
=back
=head1 SEE ALSO
L<IPC::SysV>, L<Class::Struct>, L<semget(2)>, L<semctl(2)>, L<semop(2)>
=head1 AUTHORS
Graham Barr <gbarr@pobox.com>,
Marcus Holland-Moritz <mhx@cpan.org>
=head1 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.
=cut