ActiveSupport::Cache::MemCacheStore extension

mem_cache_store.rb

#
# MemCacheStore extension which allows to find and delete the objects from cache by keys matched regexp.
#
# Idea was taken from http://github.com/martincik/memcache_store_with_delete_matched/

module ActiveSupport
  module Cache
    class MemCacheStore < Store

      cattr_accessor :keys_key_name

       def write_with_matched(key, value, options = nil)
         flush_keys(key) if write_without_matched(key, value, options)
       end
       alias_method_chain :write, :matched

       def delete_with_matched(key, options = nil)
         if delete_without_matched(key, options)
           keys.delete(key)
           flush_keys
         end
       end
       alias_method_chain :delete, :matched

       def delete_matched(matcher, options = nil)
         super
         keys.dup.each do |key|
           if key =~ matcher
             keys.delete(key) if delete_without_matched(key, options)
           end
         end
         flush_keys
       end

       def keys_key_name
         @@keys_key_name ||= "mem_cache_store_keys"
       end

       private

         def keys
           @keys ||= begin
             YAML.load(read(keys_key_name))
           rescue TypeError
             []
           end
         end

         def flush_keys(key = nil)
           unless key.nil? || keys.include?(key)
             keys << key
           end
           write_without_matched(keys_key_name, keys.compact.to_yaml)
           @keys = nil
         end

    end
  end
end

mem_cache_store_spec.rb

require File.dirname(__FILE__) + '/../spec_helper'

describe ActiveSupport::Cache::MemCacheStore do

  let(:cache) { ActiveSupport::Cache.lookup_store(:mem_cache_store) }

  context "with #delete_matched" do

    it "should find and delete objects by keys matched to regexp" do
      cache.write("1_0", "foo_1_0")
      cache.write("2_0", "foo_2_0")
      cache.write("2_1", "foo_2_1")
      cache.delete_matched(/2_.*/)
      cache.read("1_0").should == "foo_1_0"
      cache.read("2_0").should be_nil
      cache.read("2_1").should be_nil
    end

  end

end