这篇文章将为大家详细讲解有关dubbo-go中roundRobinLoadBalance的作用是什么,文章内容质量较高,因此小编分享给大家做个参考,希望大家阅读完这篇文章后对相关知识有一定的了解。
dubbo-go-v1.4.2/cluster/loadbalance/round_robin.go
const (
// RoundRobin ...
RoundRobin = "roundrobin"
// COMPLETE ...
COMPLETE = 0
// UPDATING ...
UPDATING = 1
)
var (
methodWeightMap sync.Map // [string]invokers
state = int32(COMPLETE) // update lock acquired ?
recyclePeriod = 60 * time.Second.Nanoseconds()
)
func init() {
extension.SetLoadbalance(RoundRobin, NewRoundRobinLoadBalance)
}
type roundRobinLoadBalance struct{}
// NewRoundRobinLoadBalance ...
func NewRoundRobinLoadBalance() cluster.LoadBalance {
return &roundRobinLoadBalance{}
}
roundRobinLoadBalance的NewRoundRobinLoadBalance方法创建了roundRobinLoadBalance
dubbo-go-v1.4.2/cluster/loadbalance/round_robin.go
func (lb *roundRobinLoadBalance) Select(invokers []protocol.Invoker, invocation protocol.Invocation) protocol.Invoker {
count := len(invokers)
if count == 0 {
return nil
}
if count == 1 {
return invokers[0]
}
key := invokers[0].GetUrl().Path + "." + invocation.MethodName()
cache, _ := methodWeightMap.LoadOrStore(key, &cachedInvokers{})
cachedInvokers := cache.(*cachedInvokers)
var (
clean = false
totalWeight = int64(0)
maxCurrentWeight = int64(math.MinInt64)
now = time.Now()
selectedInvoker protocol.Invoker
selectedWeightRobin *weightedRoundRobin
)
for _, invoker := range invokers {
var weight = GetWeight(invoker, invocation)
if weight < 0 {
weight = 0
}
identifier := invoker.GetUrl().Key()
loaded, found := cachedInvokers.LoadOrStore(identifier, &weightedRoundRobin{weight: weight})
weightRobin := loaded.(*weightedRoundRobin)
if !found {
clean = true
}
if weightRobin.Weight() != weight {
weightRobin.setWeight(weight)
}
currentWeight := weightRobin.increaseCurrent()
weightRobin.lastUpdate = &now
if currentWeight > maxCurrentWeight {
maxCurrentWeight = currentWeight
selectedInvoker = invoker
selectedWeightRobin = weightRobin
}
totalWeight += weight
}
cleanIfRequired(clean, cachedInvokers, &now)
if selectedWeightRobin != nil {
selectedWeightRobin.Current(totalWeight)
return selectedInvoker
}
// should never happen
return invokers[0]
}
Select方法遍历invokers,通过weightRobin.increaseCurrent()作为currentWeight,若currentWeight大于maxCurrentWeight则更新maxCurrentWeight,设置selectedInvoker为当前invoker,设置selectedWeightRobin为当前weightRobin;之后对于selectedWeightRobin不为nil的执行selectedWeightRobin.Current(totalWeight),返回selectedInvoker
roundRobinLoadBalance的NewRoundRobinLoadBalance方法创建了roundRobinLoadBalance;其Select方法遍历invokers,通过weightRobin.increaseCurrent()作为currentWeight,若currentWeight大于maxCurrentWeight则更新maxCurrentWeight,设置selectedInvoker为当前invoker,设置selectedWeightRobin为当前weightRobin
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原文链接:https://my.oschina.net/go4it/blog/4492843