Function findMembersByTopic

groupbalancer.go:301–328

findMembersByTopic groups the memberGroupMetadata by topic.

(members []GroupMember)

// findMembersByTopic groups the memberGroupMetadata by topic.
func findMembersByTopic(members []GroupMember) map[string][]GroupMember {
	membersByTopic := map[string][]GroupMember{}
	for _, member := range members {
		for _, topic := range member.Topics {
			membersByTopic[topic] = append(membersByTopic[topic], member)
		}
	}

	// normalize ordering of members to enabling grouping across topics by partitions
	//
	// Want:
	// 		C0 [T0/P0, T1/P0]
	// 		C1 [T0/P1, T1/P1]
	//
	// Not:
	// 		C0 [T0/P0, T1/P1]
	// 		C1 [T0/P1, T1/P0]
	//
	// Even though the later is still round robin, the partitions are crossed
	//
	for _, members := range membersByTopic {
		sort.Slice(members, func(i, j int) bool {
			return members[i].ID < members[j].ID
		})
	}

	return membersByTopic
}

// findGroupBalancer returns the GroupBalancer with the specified protocolName
// from the slice provided.