func()

in store/cluster_shard.go [181:207]

• 26 lines of code
• 8 McCabe index (conditional complexity)

func (shard *Shard) promoteNewMaster(ctx context.Context, masterNodeID, preferredNodeID string) (string, error) {
	if len(shard.Nodes) <= 1 {
		return "", consts.ErrShardNoReplica
	}

	oldMasterNodeIndex := -1
	for i, node := range shard.Nodes {
		if node.IsMaster() {
			oldMasterNodeIndex = i
			break
		}
	}
	if oldMasterNodeIndex == -1 {
		return "", consts.ErrOldMasterNodeNotFound
	}
	if masterNodeID != "" && shard.Nodes[oldMasterNodeIndex].ID() != masterNodeID {
		return "", consts.ErrNodeIsNotMaster
	}
	newMasterNodeIndex := shard.getNewMasterNodeIndex(ctx, oldMasterNodeIndex, preferredNodeID)
	if newMasterNodeIndex == -1 {
		return "", consts.ErrShardNoMatchNewMaster
	}
	shard.Nodes[oldMasterNodeIndex].SetRole(RoleSlave)
	shard.Nodes[newMasterNodeIndex].SetRole(RoleMaster)
	preferredNewMasterNode := shard.Nodes[newMasterNodeIndex]
	return preferredNewMasterNode.ID(), nil
}