remcached: multi operation should return immediately if empty + spec

lib/remcached.rb

@@ -90,6 +90,11 @@ def delete(contents, &callback)
     ##
 
     def multi_operation(request_klass, contents_list, &callback)
+      if contents_list.empty?
+        callback.call []
+        return self
+      end
+
       results = {}
 
       # Assemble client connections per keys

spec/memcached_spec.rb

@@ -250,6 +250,19 @@ def key(n)
         }
       end
     end
+
+    context "when the multi operation is empty" do
+      it "should return immediately" do
+        @results = []
+        @calls = 0
+        Memcached.multi_add([]) { |responses|
+          @results += responses
+          @calls += 1
+        }
+        @results.should be_empty
+        @calls.should == 1
+      end
+    end
   end
 
 end