graceful-takeover-auto switchover failed. when i set true for PreventCrossDataCenterMasterFailover.

go/inst/instance_topology.go

@@ -2202,25 +2202,71 @@ func getPriorityBinlogFormatForCandidate(replicas [](*Instance)) (priorityBinlog
 	return sorted.First(), nil
 }
 
+// getPriorityDataCenterForCandidate returns the replica datacenter found
+// among given instances. This will be used for choosing best candidate for promotion.
+func getPriorityDataCenterForCandidate(replicas [](*Instance)) (priorityDataCenter string, err error) {
+	if len(replicas) == 0 {
+                return "", log.Errorf("empty replicas list in getPriorityBinlogFormatForCandidate")
+	}
+	candidate := ""
+	for _, replica := range replicas {
+		candidate = replica.DataCenter
+		return candidate, nil
+	}
+	return "", nil
+}
+
+// IsDataCenterCandiadateReplica compare master's datacenter and replica datacenter.
+// if master's datacenter eq replica datacenter return true
+func IsDataCenterCandiadateReplica(priorityDataCenter string, replica *Instance) bool {
+	masterOfDesignatedInstance, _ := GetInstanceMaster(replica)
+	if masterOfDesignatedInstance.DataCenter == priorityDataCenter {
+		log.Debugf("instance %+v is banned because of promotion rule", replica.Key)
+		return true
+	}
+	if matched, _ := regexp.MatchString(config.Config.DataCenterPattern, replica.Key.Hostname); matched {
+		return true
+	}
+	return false
+}
+
 // chooseCandidateReplica
 func chooseCandidateReplica(replicas [](*Instance)) (candidateReplica *Instance, aheadReplicas, equalReplicas, laterReplicas, cannotReplicateReplicas [](*Instance), err error) {
 	if len(replicas) == 0 {
 		return candidateReplica, aheadReplicas, equalReplicas, laterReplicas, cannotReplicateReplicas, fmt.Errorf("No replicas found given in chooseCandidateReplica")
 	}
 	priorityMajorVersion, _ := getPriorityMajorVersionForCandidate(replicas)
 	priorityBinlogFormat, _ := getPriorityBinlogFormatForCandidate(replicas)
-
-	for _, replica := range replicas {
-		replica := replica
-		if isGenerallyValidAsCandidateReplica(replica) &&
-			!IsBannedFromBeingCandidateReplica(replica) &&
-			!IsSmallerMajorVersion(priorityMajorVersion, replica.MajorVersionString()) &&
-			!IsSmallerBinlogFormat(priorityBinlogFormat, replica.Binlog_format) {
-			// this is the one
-			candidateReplica = replica
-			break
-		}
-	}
+	// priorityDataCenter return boll for candidate
+	priorityDataCenter, _ :=  getPriorityDataCenterForCandidate(replicas)
+
+
+	if config.Config.PreventCrossDataCenterMasterFailover {
+                for _, replica := range replicas {
+                        replica := replica
+                        if isGenerallyValidAsCandidateReplica(replica) &&
+                                !IsBannedFromBeingCandidateReplica(replica) &&
+                                !IsSmallerMajorVersion(priorityMajorVersion, replica.MajorVersionString()) &&
+                                !IsSmallerBinlogFormat(priorityBinlogFormat, replica.Binlog_format) &&
+                                IsDataCenterCandiadateReplica(priorityDataCenter, replica) {
+                                // this is the one
+                                candidateReplica = replica
+                                break
+                        }
+                }
+        } else {
+                for _, replica := range replicas {
+                        replica := replica
+                        if isGenerallyValidAsCandidateReplica(replica) &&
+                                !IsBannedFromBeingCandidateReplica(replica) &&
+                                !IsSmallerMajorVersion(priorityMajorVersion, replica.MajorVersionString()) &&
+                                !IsSmallerBinlogFormat(priorityBinlogFormat, replica.Binlog_format) {
+                                // this is the one
+                                candidateReplica = replica
+                                break
+                        }
+                }
+        }
 	if candidateReplica == nil {
 		// Unable to find a candidate that will master others.
 		// Instead, pick a (single) replica which is not banned.