func writeNodeIDToFile()

in cmd/ndb-pod-initializer/main.go [141:195]
36 lines of code
6 McCabe index (conditional complexity)

func writeNodeIDToFile(hostname, ndbConnectString string) (nodeId int, nodeIdPool []int, nodeType mgmapi.NodeTypeEnum) {
	// All nodeIds are sequentially assigned based on the ordinal indices
	// of the StatefulSet pods. So deduce the nodeId of the first MySQL
	// Cluster node of same nodeType (i.e) the node with StatefulSet ordinal
	// index 0, of same type. Then the nodeId of the current node will be
	// startNodeId + pod ordinal index.
	var startNodeIdOfSameNodeType int
	switch getPodMySQLClusterNodeType(hostname) {
	case constants.NdbNodeTypeMgmd:
		// Management nodes have nodeId 1 and 2.
		startNodeIdOfSameNodeType = 1
		nodeType = mgmapi.NodeTypeMGM
	case constants.NdbNodeTypeNdbmtd:
		// Data nodes' nodeId continue sequentially
		// after the Management nodes' nodeIds.
		numOfManagementNode := len(strings.Split(ndbConnectString, ",")) - 1
		startNodeIdOfSameNodeType = numOfManagementNode + 1
		nodeType = mgmapi.NodeTypeNDB
	case constants.NdbNodeTypeMySQLD:
		nodeType = mgmapi.NodeTypeAPI
	}

	// Extract pod ordinal index from hostname.
	// Hostname will be of form <ndbcluster name>-<node-type>-<sfset pod ordinal index>
	tokens := strings.Split(hostname, "-")
	podOrdinalIndex, _ := strconv.ParseInt(tokens[len(tokens)-1], 10, 32)

	// Calculate nodeId
	var nodeIdText string
	if nodeType == mgmapi.NodeTypeAPI {
		// For MySQL Servers, if connection pool is enabled, successive
		// nodeIds are assigned to a single MySQL Server
		ndbConnectionPoolSize, _ := strconv.ParseInt(os.Getenv("NDB_CONNECTION_POOL_SIZE"), 10, 32)
		startNodeId := constants.NdbNodeTypeAPIStartNodeId + int(ndbConnectionPoolSize)*int(podOrdinalIndex)
		endNodeId := startNodeId + int(ndbConnectionPoolSize)
		for ; startNodeId < endNodeId; startNodeId++ {
			nodeIdPool = append(nodeIdPool, startNodeId)
			nodeIdText += fmt.Sprintf("%d,", startNodeId)
		}
		nodeIdText = nodeIdText[:len(nodeIdText)-1]
	} else {
		nodeId = startNodeIdOfSameNodeType + int(podOrdinalIndex)
		nodeIdText = fmt.Sprintf("%d", nodeId)
	}

	// Persist the nodeId into a file to be used by other scripts/commands
	f, err := os.OpenFile(statefulset.NodeIdFilePath,
		os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
	failOnError(err, "Failed to create file %q : %s", statefulset.NodeIdFilePath, err)

	_, err = f.WriteString(nodeIdText)
	failOnError(err, "Failed to write nodeId to file : %s", err)

	return nodeId, nodeIdPool, nodeType
}