Contents

require 'dalli-elasticache'
require 'alephant/logger'

module Alephant
  module Broker
    module Cache
      class Client
        include Logger

        DEFAULT_TTL  = 2592000

        def initialize
          unless config_endpoint.nil?
            @@elasticache ||= ::Dalli::ElastiCache.new(config_endpoint, { :expires_in => ttl })
            @@client ||= @@elasticache.client
          else
            logger.debug "Broker::Cache::Client#initialize: No config endpoint, NullClient used"
            logger.metric("NoConfigEndpoint", opts.merge(:function => "initialize"))
            @@client = NullClient.new
          end
        end

        def get(key, &block)
          begin
            versioned_key = versioned key
            result = @@client.get versioned_key
            logger.info "Broker::Cache::Client#get key: #{versioned_key} - #{result ? 'hit' : 'miss'}"
            logger.metric(
              "GetKeyMiss",
              opts[:dimensions].merge(:function => "get")
            ) unless result
            result ? result : set(key, block.call)
          rescue StandardError => e
            block.call if block_given?
          end
        end

        def set(key, value, ttl = nil)
          value.tap { |o| @@client.set(versioned(key), o, ttl) }
        end

        private

        def opts
          {
            :dimensions => {
              :module   => "AlephantBrokerCache",
              :class    => "Client"
            }
          }
        end

        def config_endpoint
          Broker.config['elasticache_config_endpoint']
        end

        def ttl
          Broker.config['elasticache_ttl'] || DEFAULT_TTL
        end

        def versioned(key)
          [key, cache_version].compact.join('_')
        end

        def cache_version
          Broker.config['elasticache_cache_version']
        end
      end

      class NullClient
        def get(key); end

        def set(key, value, ttl = nil)
          value
        end
      end
    end
  end
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
alephant-broker-3.5.1	lib/alephant/broker/cache.rb