marshal_store.rb

module Merb::Cache
  # The installed cache stores don't serialize the data before
  # caching it.  The MarshalStore serializes the data using Marshal.dump
  # and Marshal.load.
  #
  # NOTE: to be useful with DataMapper, make sure to use the edge version
  # of dm-core 0.9.8 or later, otherwise you'll be left with an error that
  # looks like "no marshal_dump is defined for class Thread".
  # (thanks dkubb: http://github.com/sam/dm-core/commit/83ea752d5604726b00ff11c55c0fbd2c39607c16)
  class MarshalStore < AbstractStrategyStore
    def writable?(key, parameters = {}, conditions = {})
      true
    end

    def read(key, parameters = {})
      deserialize(@stores.capture_first {|c| c.read(key, parameters)})
    end

    def write(key, data = nil, parameters = {}, conditions = {})
      if writable?(key, parameters, conditions)
        @stores.capture_first {|c| c.write(key, serialize(data), parameters, conditions)}
      end
    end

    def write_all(key, data = nil, parameters = {}, conditions = {})
      if writable?(key, parameters, conditions)
        @stores.map {|c| c.write_all(key, serialize(data), parameters, conditions)}.all?
      end
    end

    def fetch(key, parameters = {}, conditions = {}, &blk)
      wrapper_blk = lambda { serialize(blk.call) }
      deserialize(read(key, parameters) || @stores.capture_first {|s| s.fetch(key, parameters, conditions, &wrapper_blk)})
    end

    def exists?(key, parameters = {})
      @stores.capture_first {|c| c.exists?(key, parameters)}
    end

    def delete(key, parameters = {})
      @stores.map {|c| c.delete(key, parameters)}.any?
    end

    def delete_all!
      @stores.map {|c| c.delete_all! }.all?
    end

    def serialize(data)
      return if data.nil?

      Marshal.dump(data)
    end

    def deserialize(data)
      return if data.nil?

      Marshal.load(data)
    end
  end
end