add basic command framework and apiserver

pkg/apiserver/router_swapper.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2016 The GoStor Authors All rights reserved.
+
+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 apiserver contains the code that provides a rest.ful api service.
+package apiserver
+
+import (
+	"net/http"
+	"sync"
+
+	"github.com/gorilla/mux"
+)
+
+// routerSwapper is an http.Handler that allow you to swap
+// mux routers.
+type routerSwapper struct {
+	mu     sync.Mutex
+	router *mux.Router
+}
+
+// Swap changes the old router with the new one.
+func (rs *routerSwapper) Swap(newRouter *mux.Router) {
+	rs.mu.Lock()
+	rs.router = newRouter
+	rs.mu.Unlock()
+}
+
+// ServeHTTP makes the routerSwapper to implement the http.Handler interface.
+func (rs *routerSwapper) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	rs.mu.Lock()
+	router := rs.router
+	rs.mu.Unlock()
+	router.ServeHTTP(w, r)
+}