08/12 20:44

## 序

``````const (
name = "random"
)

func init() {
}

}

}
``````

## Select

``````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)]
}
``````
• Select方法先判断invokers数量，若只有一个则返回invokers[0]；之后遍历invokers计算totalWeight及sameWeight，若totalWeight大于0且sameWeight为false则使用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]；若都没有选中，则返回invokers[rand.Intn(length)]

0
0 收藏

0 评论
0 收藏
0