# Auto-generated file -- DO NOT EDIT!!!!!

=head1 NAME

KinoSearch::Store::Lock - Abstract class representing an interprocess mutex lock.

=head1 SYNOPSIS

    my $lock = $lock_factory->make_lock(
        name    => 'write',
        timeout => 5000,
    );
    $lock->obtain or die "can't get lock for " . $lock->get_name;
    do_stuff();
    $lock->release;



=head1 DESCRIPTION

Abstract class representing an interprocess mutex lock.

The Lock class produces an interprocess mutex lock.  The default subclass
uses dot-lock files, but alternative implementations are possible.

Each lock must have a name which is unique per resource to be locked.  Each
lock also has an "hostname" which should be unique per machine; it is
used to help clear away stale locks.

=head1 CONSTRUCTORS

=head2 new( I<[labeled params]> )

    my $lock = KinoSearch::Store::Lock->new(
        name     => 'commit',     # required
        folder   => $folder,      # required
        hostname => $hostname,    # required
        timeout  => 5000,         # default: 0
        interval => 1000,         # default: 100
    );

Abstract constructor.

=over

=item *

B<folder> - A Folder.

=item *

B<name> - File-system-friendly string identifying the resource to be
locked.

=item *

B<hostname> - A unique per-machine identifier.

=item *

B<timeout> - Time in milliseconds to keep retrying before abandoning
the attempt to obtain() a lock.

=item *

B<interval> - Time in milliseconds between retries.

=back



=head1 METHODS

=head2 obtain()

Call request() once per C<< interval >> until request() returns
success or the C<< timeout >> has been reached.

Returns: true on success, false otherwise.



=head1 ABSTRACT METHODS

=head2 request()

Make one attempt to acquire the lock. 

The semantics of request() differ depending on whether shared() returns
true.  If the Lock is shared(), then request() should not fail if
another lock is held against the resource identified by
C<< name >> (though it might fail for other reasons).  If it is
not shared() -- i.e. it's an exclusive (write) lock -- then other locks
should cause request() to fail.

Returns: true on success, false on failure.

=head2 release()

Release the lock.

=head2 is_locked()

Indicate whether the resource identified by this lock's name is
currently locked.

Returns: true if the resource is locked, false otherwise.

=head2 clear_stale()

Release all locks that meet the following three conditions: the lock
name matches, the hostname matches, and the process id that the lock
was created under no longer identifies an active process.



=head1 INHERITANCE

KinoSearch::Store::Lock isa L<KinoSearch::Obj>.


=head1 COPYRIGHT AND LICENSE

Copyright 2005-2009 Marvin Humphrey

This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut