snippet.rb

require 'forwardable'

module DataMapper::Adapters

  class MasterSlaveAdapter < AbstractAdapter
    extend Forwardable
    extend DataMapper::Migrations::SingletonMethods
    
    def_delegators :@master, :storage_exists?, :field_exists?, 
      :upgrade_model_storage, :create_model_storage, :destroy_model_storage, :alter_model_storage,
      :create_property_storage, :destroy_property_storage, :alter_property_storgae
    
    attr_reader :name
    
    def create(resources)
      @master.create(resources)
    end
    
    def read(query)
      @slave.read(query)
    end
    
    def update(attributes, collection)
      @master.update(attributes, collection)
    end
    
    def delete(collection)
      @master.delete(collection)
    end
    
  private
    
    def initialize(name, options)
      super(name, options)

      assert_kind_of 'options', @options[:master], Hash
      assert_kind_of 'options', @options[:slave],  Hash
      
      @master = ::DataMapper.setup("#{name}_master".intern, @options[:master])
      @slave  = ::DataMapper.setup("#{name}_slave".intern,  @options[:slave] )
    end
    
    def method_missing(meth, *args, &block)
      @slave.send(meth, *args, &block)
    end
    
  end
  
end