本文主要研究一下dubbo-go的randomLoadBalance
dubbo-go-v1.4.2/cluster/loadbalance/random.go
const (
name = "random"
)
func init() {
extension.SetLoadbalance(name, NewRandomLoadBalance)
}
type randomLoadBalance struct {
}
// NewRandomLoadBalance ...
func NewRandomLoadBalance() cluster.LoadBalance {
return &randomLoadBalance{}
}
dubbo-go-v1.4.2/cluster/loadbalance/random.go
func (lb *randomLoadBalance) Select(invokers []protocol.Invoker, invocation protocol.Invocation) protocol.Invoker {
var length int
if length = len(invokers); length == 1 {
return invokers[0]
}
sameWeight := true
weights := make([]int64, length)
firstWeight := GetWeight(invokers[0], invocation)
totalWeight := firstWeight
weights[0] = firstWeight
for i := 1; i < length; i++ {
weight := GetWeight(invokers[i], invocation)
weights[i] = weight
totalWeight += weight
if sameWeight && weight != firstWeight {
sameWeight = false
}
}
if totalWeight > 0 && !sameWeight {
// If (not every invoker has the same weight & at least one invoker's weight>0), select randomly based on totalWeight.
offset := rand.Int63n(totalWeight)
for i := 0; i < length; i++ {
offset -= weights[i]
if offset < 0 {
return invokers[i]
}
}
}
// If all invokers have the same weight value or totalWeight=0, return evenly.
return invokers[rand.Intn(length)]
}
randomLoadBalance的NewRandomLoadBalance方法创建randomLoadBalance;其Select方法使用了带weight的方法,具体就是使用rand.Int63n(totalWeight)随机一个offset,之后遍历weights,用offset挨个去减weights[i],若offset小于0,则返回invokers[i]
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原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。