From f2865b626f2422073f41b0b1a876de0d8db72dbd Mon Sep 17 00:00:00 2001
From: Matt Reiferson <mreiferson@gmail.com>
Date: Fri, 21 Dec 2012 07:52:55 -0500
Subject: [PATCH] nsqd: simplify optimized v2 message pump

---
 nsqd/protocol_v2.go | 96 +++++++++++++++++----------------------------
 1 file changed, 37 insertions(+), 59 deletions(-)

diff --git a/nsqd/protocol_v2.go b/nsqd/protocol_v2.go
index 2c61e9adb..4c688bc7b 100644
--- a/nsqd/protocol_v2.go
+++ b/nsqd/protocol_v2.go
@@ -161,6 +161,8 @@ func (p *ProtocolV2) Exec(client *ClientV2, params [][]byte) ([]byte, error) {
 func (p *ProtocolV2) messagePump(client *ClientV2) {
 	var err error
 	var buf bytes.Buffer
+	var clientMsgChan chan *nsq.Message
+	var flusherChan <-chan time.Time
 
 	// v2 opportunistically buffers data to clients to reduce write system calls
 	// we force flush in two cases:
@@ -178,78 +180,54 @@ func (p *ProtocolV2) messagePump(client *ClientV2) {
 	for {
 		if !client.IsReadyForMessages() {
 			// the client is not ready to receive messages...
+			clientMsgChan = nil
+			flusherChan = nil
 			// force flush
 			err = p.Flush(client)
 			if err != nil {
 				goto exit
 			}
 			flushed = true
-
-			select {
-			case <-client.ReadyStateChan:
-			case <-heartbeat.C:
-				err = p.Send(client, nsq.FrameTypeResponse, []byte("_heartbeat_"))
-				if err != nil {
-					log.Printf("PROTOCOL(V2): error sending heartbeat - %s", err.Error())
-				}
-			case <-client.ExitChan:
-				goto exit
-			}
 		} else if flushed {
 			// last iteration we flushed...
 			// do not select on the flusher ticker channel
-			select {
-			case <-client.ReadyStateChan:
-			case <-heartbeat.C:
-				err = p.Send(client, nsq.FrameTypeResponse, []byte("_heartbeat_"))
-				if err != nil {
-					log.Printf("PROTOCOL(V2): error sending heartbeat - %s", err.Error())
-				}
-			case msg, ok := <-client.Channel.clientMsgChan:
-				if !ok {
-					goto exit
-				}
-
-				err = p.SendMessage(client, msg, &buf)
-				if err != nil {
-					goto exit
-				}
-				flushed = false
-			case <-client.ExitChan:
-				goto exit
-			}
+			clientMsgChan = client.Channel.clientMsgChan
+			flusherChan = nil
 		} else {
-			// if there isn't any more data we should flush...
+			// we're buffered (if there isn't any more data we should flush)...
 			// select on the flusher ticker channel, too
-			select {
-			case <-flusher.C:
-				// if this case wins, we're either starved
-				// or we won the race between other channels...
-				// in either case, force flush
-				err := p.Flush(client)
-				if err != nil {
-					goto exit
-				}
-				flushed = true
-			case <-client.ReadyStateChan:
-			case <-heartbeat.C:
-				err = p.Send(client, nsq.FrameTypeResponse, []byte("_heartbeat_"))
-				if err != nil {
-					log.Printf("PROTOCOL(V2): error sending heartbeat - %s", err.Error())
-				}
-			case msg, ok := <-client.Channel.clientMsgChan:
-				if !ok {
-					goto exit
-				}
-
-				err = p.SendMessage(client, msg, &buf)
-				if err != nil {
-					goto exit
-				}
-				flushed = false
-			case <-client.ExitChan:
+			clientMsgChan = client.Channel.clientMsgChan
+			flusherChan = flusher.C
+		}
+
+		select {
+		case <-flusherChan:
+			// if this case wins, we're either starved
+			// or we won the race between other channels...
+			// in either case, force flush
+			err := p.Flush(client)
+			if err != nil {
+				goto exit
+			}
+			flushed = true
+		case <-client.ReadyStateChan:
+		case <-heartbeat.C:
+			err = p.Send(client, nsq.FrameTypeResponse, []byte("_heartbeat_"))
+			if err != nil {
+				log.Printf("PROTOCOL(V2): error sending heartbeat - %s", err.Error())
+			}
+		case msg, ok := <-clientMsgChan:
+			if !ok {
+				goto exit
+			}
+
+			err = p.SendMessage(client, msg, &buf)
+			if err != nil {
 				goto exit
 			}
+			flushed = false
+		case <-client.ExitChan:
+			goto exit
 		}
 	}