NAME

IPC::Lock - simple and safe local/network locking

SYNOPSIS

IPC::Lock is a base module and depends on other objects to implement it.

Current modules include IPC::Lock::Memcached.  

Please refer to a child module for their respective usage.

Generally, you instantiate a $lock object via new.  The new will contain
connection parameters.

Then call

$lock->lock($key)

where $key is a unique identifier.  The default value set for the lock comes
from $self->atomic_value, which by default is

return "$self->{hostname}:$$:" . scalar gettimeofday;

The value can potentially be used for debugging.

When $lock leaves scope,

$lock->unlock

gets called.  When called via destroy, unlock will destroy the last 
$key that was locked.  To avoid relying on this magic, call 
$lock->unlock explicitly.

PARAMETERS

The following parameters can be set in the instantiation:

ttl       - number of seconds the lock should last, default is 60
patience  - number of seconds to wait for a lock, default is 2
increment - number of seconds to wait between atomic attempts, default is 0.05

So, to instantiate with a ttl of a day, patience of a minute and increment of a second

my $lock = IPC::Lock::Child->new({
    ttl       => 86400,
    patience  => 60,
    increment => 1,
});

DESCRIPTION

Simple way to lock across multiple boxes.  Child modules need to implement two methods

atomic - a way to lock atomically
unatomic - a way to undo your atomic function

THANKS

Thanks to Perrin Harkins for suggesting the IPC::Lock namespace. Thanks to File::NFSLock for graceful_sig.

AUTHOR

Earl Cahill, <cpan@spack.net>

COPYRIGHT AND LICENSE

Copyright (C) 2005 by Earl Cahill

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.7 or, at your option, any later version of Perl 5 you may have available.