lib/cached_resource/configuration.rb in cached_resource-2.2.0 vs lib/cached_resource/configuration.rb in cached_resource-2.3.0

@@ -14,33 +14,58 @@
 
     # Initialize a Configuration with the given options, overriding any
     # defaults. The following options exist for cached resource:
     # :enabled, default: true
     # :ttl, default: 604800
+    # :ttl_randomization, default: false,
+    # :ttl_randomization_scale, default: 1..2,
     # :collection_synchronize, default: false,
     # :collection_arguments, default: [:all]
     # :cache, default: Rails.cache or ActiveSupport::Cache::MemoryStore.new,
     # :logger, default: Rails.logger or ActiveSupport::BufferedLogger.new(NilIO.new)
     def initialize(options={})
       super({
         :enabled => true,
         :ttl => 604800,
+        :ttl_randomization => false,
+        :ttl_randomization_scale => 1..2,
         :collection_synchronize => false,
         :collection_arguments => [:all],
         :cache => defined?(Rails.cache)  && Rails.cache || CACHE,
         :logger => defined?(Rails.logger) && Rails.logger || LOGGER
       }.merge(options))
     end
 
+    # Determine the time until a cache entry should expire.  If ttl_randomization
+    # is enabled, then a the set ttl will be multiplied by a random
+    # value from ttl_randomization_scale.
+    def generate_ttl
+      ttl_randomization && randomized_ttl || ttl
+    end
+
     # Enables caching.
     def on!
       self.enabled = true
     end
 
     # Disables caching.
     def off!
       self.enabled = false
     end
 
-  end
-end
+    private
 
+    # Get a randomized ttl value between ttl * ttl_randomization_scale begin
+    # and ttl * ttl_randomization_scale end
+    def randomized_ttl
+      ttl * sample_range(ttl_randomization_scale)
+    end
+
+    # Choose a random value from within the given range, optionally
+    # seeded by seed.
+    def sample_range(range, seed=nil)
+      srand seed if seed
+      rand * (range.end - range.begin) + range.begin
+    end
+
+  end
+end
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