lib/kisyo/cache.rb in kisyo-0.0.3 vs lib/kisyo/cache.rb in kisyo-0.0.4

@@ -3,26 +3,33 @@
     CACHE_SIZE = 100
 
     def initialize
       @keys = []
       @values = {}
+      @m = Mutex.new
     end
 
     def get(key)
       values[key]
     end
 
     def set(key, value)
-      keys << key
-      values[key] = value
+      m.synchronize do
+        if values[key]
+          return
+        end
 
-      if keys.size > CACHE_SIZE
-        oldest_key = keys.shift
-        values.delete(oldest_key)
+        keys << key
+        values[key] = value
+
+        if keys.size > CACHE_SIZE
+          oldest_key = keys.shift
+          values.delete(oldest_key)
+        end
       end
     end
 
     private
 
-    attr_reader :keys, :values
+    attr_reader :keys, :values, :m
   end
 end