Scott Baker | 2d89798 | 2019-09-24 11:50:08 -0700 | [diff] [blame^] | 1 | package cluster |
| 2 | |
| 3 | import ( |
| 4 | "math" |
| 5 | "sort" |
| 6 | |
| 7 | "github.com/Shopify/sarama" |
| 8 | ) |
| 9 | |
| 10 | // NotificationType defines the type of notification |
| 11 | type NotificationType uint8 |
| 12 | |
| 13 | // String describes the notification type |
| 14 | func (t NotificationType) String() string { |
| 15 | switch t { |
| 16 | case RebalanceStart: |
| 17 | return "rebalance start" |
| 18 | case RebalanceOK: |
| 19 | return "rebalance OK" |
| 20 | case RebalanceError: |
| 21 | return "rebalance error" |
| 22 | } |
| 23 | return "unknown" |
| 24 | } |
| 25 | |
| 26 | const ( |
| 27 | UnknownNotification NotificationType = iota |
| 28 | RebalanceStart |
| 29 | RebalanceOK |
| 30 | RebalanceError |
| 31 | ) |
| 32 | |
| 33 | // Notification are state events emitted by the consumers on rebalance |
| 34 | type Notification struct { |
| 35 | // Type exposes the notification type |
| 36 | Type NotificationType |
| 37 | |
| 38 | // Claimed contains topic/partitions that were claimed by this rebalance cycle |
| 39 | Claimed map[string][]int32 |
| 40 | |
| 41 | // Released contains topic/partitions that were released as part of this rebalance cycle |
| 42 | Released map[string][]int32 |
| 43 | |
| 44 | // Current are topic/partitions that are currently claimed to the consumer |
| 45 | Current map[string][]int32 |
| 46 | } |
| 47 | |
| 48 | func newNotification(current map[string][]int32) *Notification { |
| 49 | return &Notification{ |
| 50 | Type: RebalanceStart, |
| 51 | Current: current, |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | func (n *Notification) success(current map[string][]int32) *Notification { |
| 56 | o := &Notification{ |
| 57 | Type: RebalanceOK, |
| 58 | Claimed: make(map[string][]int32), |
| 59 | Released: make(map[string][]int32), |
| 60 | Current: current, |
| 61 | } |
| 62 | for topic, partitions := range current { |
| 63 | o.Claimed[topic] = int32Slice(partitions).Diff(int32Slice(n.Current[topic])) |
| 64 | } |
| 65 | for topic, partitions := range n.Current { |
| 66 | o.Released[topic] = int32Slice(partitions).Diff(int32Slice(current[topic])) |
| 67 | } |
| 68 | return o |
| 69 | } |
| 70 | |
| 71 | // -------------------------------------------------------------------- |
| 72 | |
| 73 | type topicInfo struct { |
| 74 | Partitions []int32 |
| 75 | MemberIDs []string |
| 76 | } |
| 77 | |
| 78 | func (info topicInfo) Perform(s Strategy) map[string][]int32 { |
| 79 | if s == StrategyRoundRobin { |
| 80 | return info.RoundRobin() |
| 81 | } |
| 82 | return info.Ranges() |
| 83 | } |
| 84 | |
| 85 | func (info topicInfo) Ranges() map[string][]int32 { |
| 86 | sort.Strings(info.MemberIDs) |
| 87 | |
| 88 | mlen := len(info.MemberIDs) |
| 89 | plen := len(info.Partitions) |
| 90 | res := make(map[string][]int32, mlen) |
| 91 | |
| 92 | for pos, memberID := range info.MemberIDs { |
| 93 | n, i := float64(plen)/float64(mlen), float64(pos) |
| 94 | min := int(math.Floor(i*n + 0.5)) |
| 95 | max := int(math.Floor((i+1)*n + 0.5)) |
| 96 | sub := info.Partitions[min:max] |
| 97 | if len(sub) > 0 { |
| 98 | res[memberID] = sub |
| 99 | } |
| 100 | } |
| 101 | return res |
| 102 | } |
| 103 | |
| 104 | func (info topicInfo) RoundRobin() map[string][]int32 { |
| 105 | sort.Strings(info.MemberIDs) |
| 106 | |
| 107 | mlen := len(info.MemberIDs) |
| 108 | res := make(map[string][]int32, mlen) |
| 109 | for i, pnum := range info.Partitions { |
| 110 | memberID := info.MemberIDs[i%mlen] |
| 111 | res[memberID] = append(res[memberID], pnum) |
| 112 | } |
| 113 | return res |
| 114 | } |
| 115 | |
| 116 | // -------------------------------------------------------------------- |
| 117 | |
| 118 | type balancer struct { |
| 119 | client sarama.Client |
| 120 | topics map[string]topicInfo |
| 121 | } |
| 122 | |
| 123 | func newBalancerFromMeta(client sarama.Client, members map[string]sarama.ConsumerGroupMemberMetadata) (*balancer, error) { |
| 124 | balancer := newBalancer(client) |
| 125 | for memberID, meta := range members { |
| 126 | for _, topic := range meta.Topics { |
| 127 | if err := balancer.Topic(topic, memberID); err != nil { |
| 128 | return nil, err |
| 129 | } |
| 130 | } |
| 131 | } |
| 132 | return balancer, nil |
| 133 | } |
| 134 | |
| 135 | func newBalancer(client sarama.Client) *balancer { |
| 136 | return &balancer{ |
| 137 | client: client, |
| 138 | topics: make(map[string]topicInfo), |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | func (r *balancer) Topic(name string, memberID string) error { |
| 143 | topic, ok := r.topics[name] |
| 144 | if !ok { |
| 145 | nums, err := r.client.Partitions(name) |
| 146 | if err != nil { |
| 147 | return err |
| 148 | } |
| 149 | topic = topicInfo{ |
| 150 | Partitions: nums, |
| 151 | MemberIDs: make([]string, 0, 1), |
| 152 | } |
| 153 | } |
| 154 | topic.MemberIDs = append(topic.MemberIDs, memberID) |
| 155 | r.topics[name] = topic |
| 156 | return nil |
| 157 | } |
| 158 | |
| 159 | func (r *balancer) Perform(s Strategy) map[string]map[string][]int32 { |
| 160 | res := make(map[string]map[string][]int32, 1) |
| 161 | for topic, info := range r.topics { |
| 162 | for memberID, partitions := range info.Perform(s) { |
| 163 | if _, ok := res[memberID]; !ok { |
| 164 | res[memberID] = make(map[string][]int32, 1) |
| 165 | } |
| 166 | res[memberID][topic] = partitions |
| 167 | } |
| 168 | } |
| 169 | return res |
| 170 | } |