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本文主要研究一下rocketmq-client-go的strategy
AllocateStrategy
rocketmq-client-go-v2.0.0/consumer/strategy.go
type AllocateStrategy func(string, string, []*primitive.MessageQueue, []string) []*primitive.MessageQueue
- AllocateStrategy定义了一个func
AllocateByAveragely
rocketmq-client-go-v2.0.0/consumer/strategy.go
func AllocateByAveragely(consumerGroup, currentCID string, mqAll []*primitive.MessageQueue,
cidAll []string) []*primitive.MessageQueue {
if currentCID == "" || len(mqAll) == 0 || len(cidAll) == 0 {
return nil
}
var (
find bool
index int
)
for idx := range cidAll {
if cidAll[idx] == currentCID {
find = true
index = idx
break
}
}
if !find {
rlog.Warning("[BUG] ConsumerId not in cidAll", map[string]interface{}{
rlog.LogKeyConsumerGroup: consumerGroup,
"consumerId": currentCID,
"cidAll": cidAll,
})
return nil
}
mqSize := len(mqAll)
cidSize := len(cidAll)
mod := mqSize % cidSize
var averageSize int
if mqSize <= cidSize {
averageSize = 1
} else {
if mod > 0 && index < mod {
averageSize = mqSize/cidSize + 1
} else {
averageSize = mqSize / cidSize
}
}
var startIndex int
if mod > 0 && index < mod {
startIndex = index * averageSize
} else {
startIndex = index*averageSize + mod
}
num := utils.MinInt(averageSize, mqSize-startIndex)
result := make([]*primitive.MessageQueue, 0)
for i := 0; i < num; i++ {
result = append(result, mqAll[(startIndex+i)%mqSize])
}
return result
}
- AllocateByAveragely方法会计算averageSize,然后再根据averageSize计算startIndex,最后取
mqAll[(startIndex+i)%mqSize]
AllocateByAveragelyCircle
rocketmq-client-go-v2.0.0/consumer/strategy.go
func AllocateByAveragelyCircle(consumerGroup, currentCID string, mqAll []*primitive.MessageQueue,
cidAll []string) []*primitive.MessageQueue {
if currentCID == "" || len(mqAll) == 0 || len(cidAll) == 0 {
return nil
}
var (
find bool
index int
)
for idx := range cidAll {
if cidAll[idx] == currentCID {
find = true
index = idx
break
}
}
if !find {
rlog.Warning("[BUG] ConsumerId not in cidAll", map[string]interface{}{
rlog.LogKeyConsumerGroup: consumerGroup,
"consumerId": currentCID,
"cidAll": cidAll,
})
return nil
}
result := make([]*primitive.MessageQueue, 0)
for i := index; i < len(mqAll); i++ {
if i%len(cidAll) == index {
result = append(result, mqAll[i])
}
}
return result
}
- AllocateByAveragelyCircle方法取
i%len(cidAll) == index
的下标
AllocateByConfig
rocketmq-client-go-v2.0.0/consumer/strategy.go
func AllocateByConfig(list []*primitive.MessageQueue) AllocateStrategy {
return func(consumerGroup, currentCID string, mqAll []*primitive.MessageQueue, cidAll []string) []*primitive.MessageQueue {
return list
}
}
- AllocateByConfig直接返回配置的list
AllocateByMachineRoom
rocketmq-client-go-v2.0.0/consumer/strategy.go
func AllocateByMachineRoom(consumeridcs []string) AllocateStrategy {
return func(consumerGroup, currentCID string, mqAll []*primitive.MessageQueue, cidAll []string) []*primitive.MessageQueue {
if currentCID == "" || len(mqAll) == 0 || len(cidAll) == 0 {
return nil
}
var (
find bool
index int
)
for idx := range cidAll {
if cidAll[idx] == currentCID {
find = true
index = idx
break
}
}
if !find {
rlog.Warning("[BUG] ConsumerId not in cidAll", map[string]interface{}{
rlog.LogKeyConsumerGroup: consumerGroup,
"consumerId": currentCID,
"cidAll": cidAll,
})
return nil
}
var premqAll []*primitive.MessageQueue
for _, mq := range mqAll {
temp := strings.Split(mq.BrokerName, "@")
if len(temp) == 2 {
for _, idc := range consumeridcs {
if idc == temp[0] {
premqAll = append(premqAll, mq)
}
}
}
}
mod := len(premqAll) / len(cidAll)
rem := len(premqAll) % len(cidAll)
startIndex := mod * index
endIndex := startIndex + mod
result := make([]*primitive.MessageQueue, 0)
for i := startIndex; i < endIndex; i++ {
result = append(result, mqAll[i])
}
if rem > index {
result = append(result, premqAll[index+mod*len(cidAll)])
}
return result
}
}
- AllocateByMachineRoom方法对于startIndex与endIndex之间的取对应的mqAll[i],若rem大于index,则取premqAll[index+mod*len(cidAll)]
AllocateByConsistentHash
rocketmq-client-go-v2.0.0/consumer/strategy.go
func AllocateByConsistentHash(virtualNodeCnt int) AllocateStrategy {
return func(consumerGroup, currentCID string, mqAll []*primitive.MessageQueue, cidAll []string) []*primitive.MessageQueue {
if currentCID == "" || len(mqAll) == 0 || len(cidAll) == 0 {
return nil
}
var (
find bool
)
for idx := range cidAll {
if cidAll[idx] == currentCID {
find = true
break
}
}
if !find {
rlog.Warning("[BUG] ConsumerId not in cidAll", map[string]interface{}{
rlog.LogKeyConsumerGroup: consumerGroup,
"consumerId": currentCID,
"cidAll": cidAll,
})
return nil
}
c := consistent.New()
c.NumberOfReplicas = virtualNodeCnt
for _, cid := range cidAll {
c.Add(cid)
}
result := make([]*primitive.MessageQueue, 0)
for _, mq := range mqAll {
clientNode, err := c.Get(mq.String())
if err != nil {
rlog.Warning("[BUG] AllocateByConsistentHash err: %s", map[string]interface{}{
rlog.LogKeyUnderlayError: err,
})
}
if currentCID == clientNode {
result = append(result, mq)
}
}
return result
}
}
- AllocateByConsistentHash方法会使用consistent.New()来创建Consistent,然后根据virtualNodeCnt设置其NumberOfReplicas属性,然后通过c.Get(mq.String())获取clientNode
小结
AllocateStrategy定义了一个func;strategy.go提供了AllocateByAveragely、AllocateByAveragelyCircle、AllocateByConfig、AllocateByMachineRoom、AllocateByConsistentHash等方法
doc
来源:oschina
链接:https://my.oschina.net/go4it/blog/4365884