Fix another deadlock inside CreateObjectPart() code, premature return without Unlocking()

Also this patch changes the cache key element to be interface{} type not string.

pkg/server/rpc/setdonut.go

@@ -0,0 +1,43 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package rpc
+
+import "net/http"
+
+// DonutService donut service
+type DonutService struct{}
+
+// DonutArgs collections of disks and name to initialize donut
+type DonutArgs struct {
+	Name  string
+	Disks []string
+}
+
+// Reply reply for successful or failed Set operation
+type Reply struct {
+	Message string `json:"message"`
+	Error   error  `json:"error"`
+}
+
+func setDonutArgs(args *DonutArgs, reply *Reply) error {
+	return nil
+}
+
+// Set method
+func (s *DonutService) Set(r *http.Request, args *DonutArgs, reply *Reply) error {
+	return setDonutArgs(args, reply)
+}