Add service API handler stubs for status, stop and restart (#3417)

cmd/admin-rpc-client.go

@@ -0,0 +1,163 @@
+/*
+ * Minio Cloud Storage, (C) 2014-2016 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 cmd
+
+import (
+	"net/rpc"
+	"net/url"
+	"path"
+	"sync"
+)
+
+// localAdminClient - represents admin operation to be executed locally.
+type localAdminClient struct {
+}
+
+// remoteAdminClient - represents admin operation to be executed
+// remotely, via RPC.
+type remoteAdminClient struct {
+	*AuthRPCClient
+}
+
+// stopRestarter - abstracts stop and restart operations for both
+// local and remote execution.
+type stopRestarter interface {
+	Stop() error
+	Restart() error
+}
+
+// Stop - Sends a message over channel to the go-routine responsible
+// for stopping the process.
+func (lc localAdminClient) Stop() error {
+	globalServiceSignalCh <- serviceStop
+	return nil
+}
+
+// Restart - Sends a message over channel to the go-routine
+// responsible for restarting the process.
+func (lc localAdminClient) Restart() error {
+	globalServiceSignalCh <- serviceRestart
+	return nil
+}
+
+// Stop - Sends stop command to remote server via RPC.
+func (rc remoteAdminClient) Stop() error {
+	args := GenericArgs{}
+	reply := GenericReply{}
+	err := rc.Call("Service.Shutdown", &args, &reply)
+	if err != nil && err == rpc.ErrShutdown {
+		rc.Close()
+	}
+	return err
+}
+
+// Restart - Sends restart command to remote server via RPC.
+func (rc remoteAdminClient) Restart() error {
+	args := GenericArgs{}
+	reply := GenericReply{}
+	err := rc.Call("Service.Restart", &args, &reply)
+	if err != nil && err == rpc.ErrShutdown {
+		rc.Close()
+	}
+	return err
+}
+
+// adminPeer - represents an entity that implements Stop and Restart methods.
+type adminPeer struct {
+	addr    string
+	svcClnt stopRestarter
+}
+
+// type alias for a collection of adminPeer.
+type adminPeers []adminPeer
+
+// makeAdminPeers - helper function to construct a collection of adminPeer.
+func makeAdminPeers(eps []*url.URL) adminPeers {
+	var servicePeers []adminPeer
+
+	// map to store peers that are already added to ret
+	seenAddr := make(map[string]bool)
+
+	// add local (self) as peer in the array
+	servicePeers = append(servicePeers, adminPeer{
+		globalMinioAddr,
+		localAdminClient{},
+	})
+	seenAddr[globalMinioAddr] = true
+
+	// iterate over endpoints to find new remote peers and add
+	// them to ret.
+	for _, ep := range eps {
+		if ep.Host == "" {
+			continue
+		}
+
+		// Check if the remote host has been added already
+		if !seenAddr[ep.Host] {
+			cfg := authConfig{
+				accessKey:   serverConfig.GetCredential().AccessKeyID,
+				secretKey:   serverConfig.GetCredential().SecretAccessKey,
+				address:     ep.Host,
+				secureConn:  isSSL(),
+				path:        path.Join(reservedBucket, servicePath),
+				loginMethod: "Service.LoginHandler",
+			}
+
+			servicePeers = append(servicePeers, adminPeer{
+				addr:    ep.Host,
+				svcClnt: &remoteAdminClient{newAuthClient(&cfg)},
+			})
+			seenAddr[ep.Host] = true
+		}
+	}
+
+	return servicePeers
+}
+
+// Initialize global adminPeer collection.
+func initGlobalAdminPeers(eps []*url.URL) {
+	globalAdminPeers = makeAdminPeers(eps)
+}
+
+// invokeServiceCmd - Invoke Stop/Restart command.
+func invokeServiceCmd(cp adminPeer, cmd serviceSignal) (err error) {
+	switch cmd {
+	case serviceStop:
+		err = cp.svcClnt.Stop()
+	case serviceRestart:
+		err = cp.svcClnt.Restart()
+	}
+	return err
+}
+
+// sendServiceCmd - Invoke Stop/Restart command on remote peers
+// adminPeer followed by on the local peer.
+func sendServiceCmd(cps adminPeers, cmd serviceSignal) {
+	// Send service command like stop or restart to all remote nodes and finally run on local node.
+	errs := make([]error, len(cps))
+	var wg sync.WaitGroup
+	remotePeers := cps[1:]
+	for i := range remotePeers {
+		wg.Add(1)
+		go func(idx int) {
+			defer wg.Done()
+			errs[idx] = invokeServiceCmd(remotePeers[idx], cmd)
+		}(i)
+	}
+	wg.Wait()
+	errs[0] = invokeServiceCmd(cps[0], cmd)
+}