Name
    IPC::SRLock - Set/reset locking semantics to single thread processes

Version
    0.2.$Revision: 118 $

Synopsis
       use IPC::SRLock;

       my $config   = { tempdir => q(path_to_tmp_directory), type => q(fcntl) };

       my $lock_obj = IPC::SRLock->new( $config );

       $lock_obj->set( k => q(some_resource_identfier) );

       # This critical region of code is guaranteed to be single threaded

       $lock_obj->reset( k => q(some_resource_identfier) );

Description
    Provides set/reset locking methods which will force a critical region of
    code to run single threaded

Configuration and Environment
    This class defines accessors and mutators for these attributes:

    debug
       Turns on debug output. Defaults to 0

    log
       If set to a log object, it's "debug" method is called if debugging is
       turned on. Defaults to Class::Null

    name
       Used as the lock file names. Defaults to *ipc_srlock*

    nap_time
       How long to wait between polls of the lock table. Defaults to 0.5
       seconds

    patience
       Time in seconds to wait for a lock before giving up. If set to 0
       waits forever. Defaults to 0

    pid
       The process id doing the locking. Defaults to this processes id

    time_out
       Time in seconds before a lock is deemed to have expired. Defaults to
       300

    type
       Determines which factory subclass is loaded. Defaults to *fcntl*

Subroutines/Methods
  new
    This constructor implements the singleton pattern, ensures that the
    factory subclass is loaded in initialises it

  catch
    Expose the "catch" method in IPC::SRLock::ExceptionClass

  get_table
       my $data = $lock_obj->get_table;

    Returns a hash ref that contains the current lock table contents. The
    keys/values in the hash are suitable for passing to HTML::FormWidgets

  list
       my $array_ref = $lock_obj->list;

    Returns an array of hash refs that represent the current lock table

  reset
       $lock_obj->reset( k => q(some_resource_key) );

    Resets the lock referenced by the k attribute.

  set
       $lock_obj->set( k => q(some_resource_key) );

    Sets the specified lock. Attributes are:

    k  Unique key to identify the lock. Mandatory no default

    p  Explicitly set the process id associated with the lock. Defaults to
       the current process id

    t  Set the time to live for this lock. Defaults to five minutes. Setting
       it to zero makes the lock last indefinitely

  throw
    Expose the "throw" method in "IPC::SRLock::ExceptionClass"

  timeout_error
    Return the text of the the timeout message

  _arg_list
       my $args = $self->_arg_list( @rest );

    Returns a hash ref containing the passed parameter list. Enables methods
    to be called with either a list or a hash ref as it's input parameters

  _ensure_class_loaded
       $self->_ensure_class_loaded( $some_class );

    Require the requested class, throw an error if it doesn't load

  _hash_merge
       my $hash = $self->_hash_merge( { key1 => val1 }, { key2 => val2 } );

    Simplistic merging of two hashes

  _init
    Called by the constructor. Optionally overridden in the factory
    subclass. This allows subclass specific initialisation

  _list
    Should be overridden in the factory subclass

  _reset
    Should be overridden in the factory subclass

  _set
    Should be overridden in the factory subclass

Diagnostics
    Setting debug to true will cause the "set" methods to log the lock
    record at the debug level

Dependencies
    Class::Accessor::Fast
    Class::Inspector
    Class::Null
    Date::Format
    IPC::SRLock::ExceptionClass
    Time::Elapsed

Incompatibilities
    The sysv subclass will not work on cygwin

Bugs and Limitations
    Testing of the memcached subclass is skipped on all platforms as it
    requires "memcached" to be listening on the localhost's default
    memcached port *localhost:11211*

    There are no known bugs in this module. Please report problems to the
    address below. Patches are welcome

Author
    Peter Flanigan, "<Support at RoxSoft.co.uk>"

License and Copyright
    Copyright (c) 2008 Peter Flanigan. All rights reserved

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

    This program is distributed in the hope that it will be useful, but
    WITHOUT WARRANTY; without even the implied warranty of MERCHANTABILITY
    or FITNESS FOR A PARTICULAR PURPOSE

