From f390edc5cda49d71f660e433c12d8995601f0630 Mon Sep 17 00:00:00 2001
From: Jehiah Czebotar <jehiah@gmail.com>
Date: Sun, 22 Nov 2020 23:34:35 -0500
Subject: [PATCH] review comments: simplify messagePump

---
 nsqd/channel.go     | 14 +++-----
 nsqd/protocol_v2.go | 78 +++++++++++++++------------------------------
 2 files changed, 31 insertions(+), 61 deletions(-)

diff --git a/nsqd/channel.go b/nsqd/channel.go
index f1f09ad09..8f9b2b73e 100644
--- a/nsqd/channel.go
+++ b/nsqd/channel.go
@@ -41,11 +41,9 @@ type Channel struct {
 
 	sync.RWMutex
 
-	topicName      string
-	name           string
-	topologyRegion string
-	topologyZone   string
-	ctx            *context
+	topicName string
+	name      string
+	ctx       *context
 
 	backend BackendQueue
 
@@ -81,18 +79,16 @@ func NewChannel(topicName string, channelName string, ctx *context,
 	c := &Channel{
 		topicName:      topicName,
 		name:           channelName,
-		topologyRegion: ctx.nsqd.getOpts().TopologyRegion,
-		topologyZone:   ctx.nsqd.getOpts().TopologyZone,
 		memoryMsgChan:  nil,
 		clients:        make(map[int64]Consumer),
 		deleteCallback: deleteCallback,
 		ctx:            ctx,
 	}
 
-	if c.topologyRegion != "" {
+	if ctx.nsqd.getOpts().TopologyRegion != "" {
 		c.regionLocalMsgChan = make(chan *Message, 0)
 	}
-	if c.topologyZone != "" {
+	if ctx.nsqd.getOpts().TopologyZone != "" {
 		c.zoneLocalMsgChan = make(chan *Message, 0)
 	}
 
diff --git a/nsqd/protocol_v2.go b/nsqd/protocol_v2.go
index 39c4e0992..bf10b1034 100644
--- a/nsqd/protocol_v2.go
+++ b/nsqd/protocol_v2.go
@@ -211,7 +211,7 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 	// with >1 clients having >1 RDY counts
 	var flusherChan <-chan time.Time
 	var sampleRate int32
-	var topologyRegion, topologyZone string
+	var regionLocal, zoneLocal bool
 
 	subEventChan := client.SubEventChan
 	identifyEventChan := client.IdentifyEventChan
@@ -233,6 +233,8 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 	close(startedChan)
 
 	for {
+		var b []byte
+		var msg *Message
 		if subChannel == nil || !client.IsReadyForMessages() {
 			// the client is not ready to receive messages...
 			memoryMsgChan = nil
@@ -252,10 +254,10 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 			// last iteration we flushed...
 			// do not select on the flusher ticker channel
 			memoryMsgChan = subChannel.memoryMsgChan
-			if subChannel.topologyZone == topologyZone && topologyZone != "" {
+			if zoneLocal {
 				zoneMsgChan = subChannel.zoneLocalMsgChan
 			}
-			if subChannel.topologyRegion == topologyRegion && topologyRegion != "" {
+			if regionLocal {
 				regionMsgChan = subChannel.regionLocalMsgChan
 			}
 			backendMsgChan = subChannel.backend.ReadChan()
@@ -264,10 +266,10 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 			// we're buffered (if there isn't any more data we should flush)...
 			// select on the flusher ticker channel, too
 			memoryMsgChan = subChannel.memoryMsgChan
-			if subChannel.topologyZone == topologyZone && topologyZone != "" {
+			if zoneLocal {
 				zoneMsgChan = subChannel.zoneLocalMsgChan
 			}
-			if subChannel.topologyRegion == topologyRegion && topologyRegion != "" {
+			if regionLocal {
 				regionMsgChan = subChannel.regionLocalMsgChan
 			}
 			backendMsgChan = subChannel.backend.ReadChan()
@@ -311,64 +313,37 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 			}
 
 			msgTimeout = identifyData.MsgTimeout
-			topologyRegion = identifyData.TopologyRegion
-			topologyZone = identifyData.TopologyZone
+			if identifyData.TopologyZone == p.ctx.nsqd.getOpts().TopologyZone {
+				zoneLocal = true
+			}
+			if identifyData.TopologyRegion == p.ctx.nsqd.getOpts().TopologyRegion {
+				regionLocal = true
+			}
 		case <-heartbeatChan:
 			err = p.Send(client, frameTypeResponse, heartbeatBytes)
 			if err != nil {
 				goto exit
 			}
-		case b := <-backendMsgChan:
-			if sampleRate > 0 && rand.Int31n(100) > sampleRate {
-				continue
-			}
-
-			msg, err := decodeMessage(b)
+		case b = <-backendMsgChan:
+			// decodeMessage then handle 'msg'
+		case msg = <-zoneMsgChan:
+		case msg = <-regionMsgChan:
+		case msg = <-memoryMsgChan:
+		case <-client.ExitChan:
+			goto exit
+		}
+		if len(b) != 0 {
+			msg, err = decodeMessage(b)
 			if err != nil {
 				p.ctx.nsqd.logf(LOG_ERROR, "failed to decode message - %s", err)
 				continue
 			}
-			msg.Attempts++
-
-			subChannel.StartInFlightTimeout(msg, client.ID, msgTimeout)
-			client.SendingMessage()
-			err = p.SendMessage(client, msg)
-			if err != nil {
-				goto exit
-			}
-			flushed = false
-		case msg := <-zoneMsgChan:
-			if sampleRate > 0 && rand.Int31n(100) > sampleRate {
-				continue
-			}
-			msg.Attempts++
-
-			subChannel.StartInFlightTimeout(msg, client.ID, msgTimeout)
-			client.SendingMessage()
-			err = p.SendMessage(client, msg)
-			if err != nil {
-				goto exit
-			}
-			flushed = false
-		case msg := <-regionMsgChan:
-			if sampleRate > 0 && rand.Int31n(100) > sampleRate {
-				continue
-			}
-			msg.Attempts++
-
-			subChannel.StartInFlightTimeout(msg, client.ID, msgTimeout)
-			client.SendingMessage()
-			err = p.SendMessage(client, msg)
-			if err != nil {
-				goto exit
-			}
-			flushed = false
-		case msg := <-memoryMsgChan:
+		}
+		if msg != nil {
 			if sampleRate > 0 && rand.Int31n(100) > sampleRate {
 				continue
 			}
 			msg.Attempts++
-
 			subChannel.StartInFlightTimeout(msg, client.ID, msgTimeout)
 			client.SendingMessage()
 			err = p.SendMessage(client, msg)
@@ -376,9 +351,8 @@ func (p *protocolV2) messagePump(client *clientV2, startedChan chan bool) {
 				goto exit
 			}
 			flushed = false
-		case <-client.ExitChan:
-			goto exit
 		}
+
 	}
 
 exit: