NAME

IPC::Lock::Memcached - memcached based locking

SYNOPSIS

            

              
              
IPC::Lock::Memcached extends IPC::Lock, and uses add and delete
for its atomic and unatomic methods.
use IPC::Lock::Memcached;
{
    my $lock = IPC::Lock::Memcached->new({
      memcached_servers => ["localhost:11211"],
    });
    ### following memcached tradition, spaces are not allowed in the key name
    ### and the user is expected to check such things themselves
    if($lock->lock("magic_key")) {
      ###
      ### do your thing
      ###    
       
      $lock->unlock;
    }
}
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.
            
          

A LITTLE WARNING

            

              
              
If you are running your Memcached servers right on the edge of memory capacity,
IPC::Lock::Memcached might not be for you.  Also, if you lose a memcached server,
you will lose your ability to lock.  Probably your $lock->lock method will never
return true.  Along similar lines, make sure you write your code tests to make
sure you actually got the lock.  Like
if($lock->lock("coolkey")) {
}
            
          

BENCHMARKS

            

              
              
Using a dual 1 ghz box
Local test without an extant memcached object
timethese(-5, {
  lock => sub {
    my $lock = IPC::Lock::Memcached->new({
      memcached_servers => ["localhost:11211"],
    });
    if($lock->lock("coolkey")) {
      $lock->unlock;
    }
  }
});
Benchmark: running lock for at least 5 CPU seconds...
  lock:  6 wallclock secs ( 4.59 usr +  0.53 sys =  5.12 CPU) @ 2302.54/s (n=11789)
Local test with an extant memcached object
my $lock = IPC::Lock::Memcached->new({
  memcached_servers => ["localhost:11211"],
});
timethese(-5, {
  lock => sub {
    if($lock->lock("coolkey")) {
      $lock->unlock;
    }
  }
});
Benchmark: running lock for at least 5 CPU seconds...
  lock:  7 wallclock secs ( 4.26 usr +  0.87 sys =  5.13 CPU) @ 3844.44/s (n=19722)
Pretty dang fast.  In other memcached benchmarks, for me, 
remote calls have actually been faster than local.
            
          

THANKS

Thanks to Brad Fitzpatrick for Cache::Memcached. It just works. Thanks to Perrin Harkins for a little review and encouraging me to add a warning.

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.