Author image Marvin Humphrey
and 1 contributors

NAME

KinoSearch::Store::Lock - Interprocess mutex lock.

SYNOPSIS

    my $lock = $lock_factory->make_lock(
        lock_name => 'commit',
        timeout   => 5000,
    );
    $lock->obtain or die "can't get lock on " . $lock->get_filename;
    do_stuff();
    $lock->release;

DESCRIPTION

The Lock class produces an interprocess mutex lock, using a lock "file". What exactly constitutes that "file" depends on the Folder implementation.

Each lock must have a name which is unique per resource to be locked. The filename for the lockfile will be derived from it, e.g. "write" will generate the file "write.lock".

Each lock also has an "agent id", a string which should be unique per-host; it is used to help clear away stale lockfiles.

CONSTRUCTOR

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

Create a Lock. Takes named parameters.

  • lock_name - String identifying the resource to be locked.

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

  • folder - An object which isa KinoSearch::Store::Folder.

  • agent_id - An identifying string, usually the host name.

METHODS

obtain

    $lock->obtain or die "Couldn't get lock";

Attempt to aquire lock once per second until the timeout has been reached. Returns true upon success, false otherwise.

release

    $lock->release;

Release the lock.

is_locked

    do_stuff() if $lock->is_locked;

Returns a boolean indicating whether the resource identified by this lock's lock_name string is currently locked.

clear_stale

    $lock->clear_stale;
    $lock->obtain or die "Can't get lock";

Release all locks that meet the following criteria:

  1. lock_name matches.

  2. agent_id matches.

  3. The process id that the lock was created under no longer identifies an active process.

COPYRIGHT

Copyright 2005-2007 Marvin Humphrey

LICENSE, DISCLAIMER, BUGS, etc.

See KinoSearch version 0.20.