IPC::Lock::Memcached - memcached based locking
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.
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")) { }
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 to Brad Fitzpatrick for Cache::Memcached. It just works. Thanks to Perrin Harkins for a little review and encouraging me to add a warning.
Earl Cahill, <cpan@spack.net>
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.
To install IPC::Lock, copy and paste the appropriate command in to your terminal.
cpanm
cpanm IPC::Lock
CPAN shell
perl -MCPAN -e shell install IPC::Lock
For more information on module installation, please visit the detailed CPAN module installation guide.