agent: Adding reload RPC command

command/agent/rpc.go

@@ -50,6 +50,7 @@ const (
 	monitorCommand    = "monitor"
 	leaveCommand      = "leave"
 	statsCommand      = "stats"
+	reloadCommand     = "reload"
 )
 
 const (
@@ -156,6 +157,7 @@ type AgentRPC struct {
 	listener  net.Listener
 	logger    *log.Logger
 	logWriter *logWriter
+	reloadCh  chan struct{}
 	stop      bool
 	stopCh    chan struct{}
 }
@@ -211,6 +213,7 @@ func NewAgentRPC(agent *Agent, listener net.Listener,
 		listener:  listener,
 		logger:    log.New(logOutput, "", log.LstdFlags),
 		logWriter: logWriter,
+		reloadCh:  make(chan struct{}, 1),
 		stopCh:    make(chan struct{}),
 	}
 	go rpc.listen()
@@ -236,6 +239,12 @@ func (i *AgentRPC) Shutdown() {
 	}
 }
 
+// ReloadCh returns a channel that can be watched for
+// when a reload is being triggered.
+func (i *AgentRPC) ReloadCh() <-chan struct{} {
+	return i.reloadCh
+}
+
 // listen is a long running routine that listens for new clients
 func (i *AgentRPC) listen() {
 	for {
@@ -361,6 +370,9 @@ func (i *AgentRPC) handleRequest(client *rpcClient, reqHeader *requestHeader) er
 	case statsCommand:
 		return i.handleStats(client, seq)
 
+	case reloadCommand:
+		return i.handleReload(client, seq)
+
 	default:
 		respHeader := responseHeader{Seq: seq, Error: unsupportedCommand}
 		client.Send(&respHeader, nil)
@@ -559,6 +571,18 @@ func (i *AgentRPC) handleStats(client *rpcClient, seq uint64) error {
 	return client.Send(&header, resp)
 }
 
+func (i *AgentRPC) handleReload(client *rpcClient, seq uint64) error {
+	// Push to the reload channel
+	select {
+	case i.reloadCh <- struct{}{}:
+	default:
+	}
+
+	// Always succeed
+	resp := responseHeader{Seq: seq, Error: ""}
+	return client.Send(&resp, nil)
+}
+
 // Used to convert an error to a string representation
 func errToString(err error) string {
 	if err == nil {