exponential_backoff.rb in resque-retry-1.1.4

- old
+ new

@@ -35,10 +35,38 @@
     #   end
     #
     module ExponentialBackoff
       include Resque::Plugins::Retry
 
+      # Raised if the min/max retry-delay multiplicand configuration is invalid
+      #
+      # @api public
+      class InvalidRetryDelayMultiplicandConfigurationException < StandardError; end
+
+      # Constants
+      #
+      # @api public
+      DEFAULT_RETRY_DELAY_MULTIPLICAND_MIN = 1.0
+      DEFAULT_RETRY_DELAY_MULTIPLICAND_MAX = 1.0
+
+      # Fail fast, when extended, if the "receiver" is misconfigured
+      #
+      # @api private
+      def self.extended(receiver)
+        retry_delay_multiplicand_min = \
+          receiver.instance_variable_get("@retry_delay_multiplicand_min") || \
+            DEFAULT_RETRY_DELAY_MULTIPLICAND_MIN
+        retry_delay_multiplicand_max = \
+          receiver.instance_variable_get("@retry_delay_multiplicand_max") || \
+            DEFAULT_RETRY_DELAY_MULTIPLICAND_MAX
+        if retry_delay_multiplicand_min > retry_delay_multiplicand_max
+          raise InvalidRetryDelayMultiplicandConfigurationException.new(
+            %{"@retry_delay_multiplicand_min" must be less than or equal to "@retry_delay_multiplicand_max"}
+          )
+        end
+      end
+
       # Defaults to the number of delays in the backoff strategy
       #
       # @return [Number] maximum number of retries
       #
       # @api private
@@ -50,14 +78,39 @@
       #
       # @return [Number] seconds to delay until the next retry.
       #
       # @api private
       def retry_delay
-        backoff_strategy[retry_attempt] || backoff_strategy.last
+        delay = backoff_strategy[retry_attempt] || backoff_strategy.last
+        delay_multiplicand = \
+          rand(retry_delay_multiplicand_min..retry_delay_multiplicand_max)
+        (delay * delay_multiplicand).to_i
       end
 
       # @abstract
+      # The minimum value (lower-bound) for the range that is is used in
+      # calculating the retry-delay product
+      #
+      # @return [Float]
+      #
+      # @api public
+      def retry_delay_multiplicand_min
+        @retry_delay_multiplicand_min ||= DEFAULT_RETRY_DELAY_MULTIPLICAND_MIN
+      end
+
+      # @abstract
+      # The maximum value (upper-bound) for the range that is is used in
+      # calculating the retry-delay product
+      #
+      # @return [Float]
+      #
+      # @api public
+      def retry_delay_multiplicand_max
+        @retry_delay_multiplicand_max ||= DEFAULT_RETRY_DELAY_MULTIPLICAND_MAX
+      end
+
+      # @abstract
       # The backoff strategy is used to vary the delay between retry attempts
       # 
       # @return [Array] array of delays. index = retry attempt
       #
       # @api public
@@ -65,6 +118,6 @@
         @backoff_strategy ||= [0, 60, 600, 3600, 10_800, 21_600]
       end
     end
 
   end
-end
\ No newline at end of file
+end