From eca4b928d2b14fa940233eba3458df52077a9ede Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Sun, 12 Aug 2018 14:25:31 -0700
Subject: [PATCH] ensure master server count is odd

---
 weed/command/master.go | 32 ++++++++++++++++++++++++++------
 weed/command/server.go |  8 ++------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/weed/command/master.go b/weed/command/master.go
index c1b9cf5ae..ac5902b60 100644
--- a/weed/command/master.go
+++ b/weed/command/master.go
@@ -35,7 +35,7 @@ var (
 	masterIp                = cmdMaster.Flag.String("ip", "localhost", "master <ip>|<server> address")
 	masterBindIp            = cmdMaster.Flag.String("ip.bind", "0.0.0.0", "ip address to bind to")
 	metaFolder              = cmdMaster.Flag.String("mdir", os.TempDir(), "data directory to store meta data")
-	masterPeers             = cmdMaster.Flag.String("peers", "", "other master nodes in comma separated ip:port list, example: 127.0.0.1:9093,127.0.0.1:9094")
+	masterPeers             = cmdMaster.Flag.String("peers", "", "all master nodes in comma separated ip:port list, example: 127.0.0.1:9093,127.0.0.1:9094")
 	volumeSizeLimitMB       = cmdMaster.Flag.Uint("volumeSizeLimitMB", 30*1000, "Master stops directing writes to oversized volumes.")
 	volumePreallocate       = cmdMaster.Flag.Bool("volumePreallocate", false, "Preallocate disk space for volumes.")
 	mpulse                  = cmdMaster.Flag.Int("pulseSeconds", 5, "number of seconds between heartbeats")
@@ -86,11 +86,7 @@ func runMaster(cmd *Command, args []string) bool {
 
 	go func() {
 		time.Sleep(100 * time.Millisecond)
-		myMasterAddress := *masterIp + ":" + strconv.Itoa(*mport)
-		var peers []string
-		if *masterPeers != "" {
-			peers = strings.Split(*masterPeers, ",")
-		}
+		myMasterAddress, peers := checkPeers(*masterIp, *mport, *masterPeers)
 		raftServer := weed_server.NewRaftServer(r, peers, myMasterAddress, *metaFolder, ms.Topo, *mpulse)
 		ms.SetRaftServer(raftServer)
 	}()
@@ -117,3 +113,27 @@ func runMaster(cmd *Command, args []string) bool {
 
 	return true
 }
+
+func checkPeers(masterIp string, masterPort int, peers string) (masterAddress string, cleanedPeers []string) {
+	masterAddress = masterIp + ":" + strconv.Itoa(masterPort)
+	if peers != "" {
+		cleanedPeers = strings.Split(peers, ",")
+	}
+
+	hasSelf := false
+	for _, peer := range cleanedPeers {
+		if peer == masterAddress {
+			hasSelf = true
+			break
+		}
+	}
+
+	peerCount := len(cleanedPeers)
+	if !hasSelf {
+		peerCount += 1
+	}
+	if peerCount %2 == 0 {
+		glog.Fatalf("Only odd number of masters are supported!")
+	}
+	return
+}
diff --git a/weed/command/server.go b/weed/command/server.go
index 983b3075f..b0c6a1ed5 100644
--- a/weed/command/server.go
+++ b/weed/command/server.go
@@ -58,7 +58,7 @@ var (
 	serverDataCenter              = cmdServer.Flag.String("dataCenter", "", "current volume server's data center name")
 	serverRack                    = cmdServer.Flag.String("rack", "", "current volume server's rack name")
 	serverWhiteListOption         = cmdServer.Flag.String("whiteList", "", "comma separated Ip addresses having write permission. No limit if empty.")
-	serverPeers                   = cmdServer.Flag.String("master.peers", "", "other master nodes in comma separated ip:masterPort list")
+	serverPeers                   = cmdServer.Flag.String("master.peers", "", "all master nodes in comma separated ip:masterPort list")
 	serverSecureKey               = cmdServer.Flag.String("secure.secret", "", "secret to encrypt Json Web Token(JWT)")
 	serverGarbageThreshold        = cmdServer.Flag.String("garbageThreshold", "0.3", "threshold to vacuum and reclaim spaces")
 	masterPort                    = cmdServer.Flag.Int("master.port", 9333, "master server http listen port")
@@ -191,11 +191,7 @@ func runServer(cmd *Command, args []string) bool {
 		go func() {
 			raftWaitForMaster.Wait()
 			time.Sleep(100 * time.Millisecond)
-			myAddress := *serverIp + ":" + strconv.Itoa(*masterPort)
-			var peers []string
-			if *serverPeers != "" {
-				peers = strings.Split(*serverPeers, ",")
-			}
+			myAddress, peers := checkPeers(*serverIp, *masterPort, *serverPeers)
 			raftServer := weed_server.NewRaftServer(r, peers, myAddress, *masterMetaFolder, ms.Topo, *volumePulse)
 			ms.SetRaftServer(raftServer)
 			volumeWait.Done()