Easy distributed locks using Redis - https://wombat.co/blog/easy_distributed_locks_using_redis/

wombat_mutex.rb

module Wombat
  # @example Lock while executing `do_something` or expire in 10 seconds
  #   Wombat::Mutex.exclusive 'my_key', 10 do
  #     do_something
  #   end
  #
  class Mutex
    class << self
      # @param key [String] the lock key
      # @param ttl [Fixnum] time to live in seconds
      # @yield the block to be exclusively executed
      def exclusive(key, ttl, &block)
        if lock(key, ttl)
          begin
            yield
          rescue => e
            Wombat.logger.error(e)
          ensure
            unlock(key)
          end
        end
      end

      # @param key [String] the lock key
      # @param ttl [Fixnum] time to live in seconds
      def lock(key, ttl)
        locked, _ = Wombat.redis.multi do
          Wombat.redis.setnx  mutex_key(key), Thread.current.object_id
          Wombat.redis.expire mutex_key(key), ttl
        end

        locked
      end

      # @param key [String] the lock key
      def unlock(key)
        !!Wombat.redis.del(mutex_key(key))
      end

      private

      def mutex_key(key)
        "#{key}_mutex_lock"
      end
    end
  end
end