It's like alias_method, but it's lock_method!
Lets you lock a method so that only one process can call it at a time. Defaults to using lockfiles on the local file system, but can be configured to store the locks in Memcached or Redis, allowing the method locks to hold over multiple hosts.
require 'lock_method' class Blog attr_accessor :url def get_latest_entries sleep 5 end lock_method :get_latest_entries # used by lock_method to differentiate between instances def as_lock url end end
Then you can do
my_blog.get_latest_entries => it will start... my_blog.get_latest_entries => this will raise LockMethod::Locked if you try to run it before the other call finishes
Just in case, you can clear them
Pays attention to method arguments
If you lock Foo.bar(*args), calling Foo.bar(:baz) will not lock out Foo.bar(:zoo).
If you want to lock instance methods, you should define #as_lock on those instances.
Locking across hosts
If you want to lock across hosts, just use shared storage, like a remote Redis or memcached instance.
If you want to lock locally, but you're using shared storage, just get the hostname of the locking instance into the as_lock.
Configuration (and supported cache clients)
The default is to use filesystem lockfiles, usually in /tmp/lock_method/*.
If you want to share locks among various machines, you can use a Memcached or Redis client:
LockMethod.config.storage = Memcached.new '127.0.0.1:11211'
LockMethod.config.storage = Redis.new
or this might even work…
LockMethod.config.storage = Rails.cache
See Config for the full list of supported caches.
Copyright 2011 Seamus Abshere