judge组件在做告警断定的时候，会解析配置的告警策略，生成一个fn，由fn.Compute()计算是否触发，比方：

  • 配置 all(#3)>90 示意最近3次的数据都 > 90 触发；
  • 配置 max(#3)>90 示意最近3次的最大值 > 90 触发；
  • 配置 min(#3)<10 示意最近3次的最小值 < 10 触发；
  • 配置 avg(#3)>90 标识最近3次的avg > 90 触发；

本文次要介绍fn如何生成，fn如何计算。

1. 告警判断

告警断定的入口代码：解说judge代码时有介绍

  • ParseFuncFromString()生成fn;
  • fn.Compute(L)依据最近的数据计算，断定是否触发;
// modules/judge/store/judge.gofunc judgeItemWithStrategy(L *SafeLinkedList, strategy model.Strategy, firstItem *model.JudgeItem, now int64) {    fn, err := ParseFuncFromString(strategy.Func, strategy.Operator, strategy.RightValue)        historyData, leftValue, isTriggered, isEnough := fn.Compute(L)    // 以后的数据点太少，不足以做告警断定    if !isEnough {        return    }    ......}

2. 如何生成fn

fn由告警策略配置的string生成：比方配置 all(#3) > 90

  • str = all(#3)
  • operator = >
  • rightValue = 90
// modules/judge/store/func.go// @str: e.g. all(#3) sum(#3) avg(#10) // @opeartor: > < func ParseFuncFromString(str string, operator string, rightValue float64) (fn Function, err error) {    if str == "" {        return nil, fmt.Errorf("func can not be null!")    }    idx := strings.Index(str, "#")    args, err := atois(str[idx+1 : len(str)-1])    if err != nil {        return nil, err    }    switch str[:idx-1] {    case "max":        fn = &MaxFunction{Limit: args[0], Operator: operator, RightValue: rightValue}    case "min":        fn = &MinFunction{Limit: args[0], Operator: operator, RightValue: rightValue}    case "all":        fn = &AllFunction{Limit: args[0], Operator: operator, RightValue: rightValue}    case "sum":        fn = &SumFunction{Limit: args[0], Operator: operator, RightValue: rightValue}    case "avg":        fn = &AvgFunction{Limit: args[0], Operator: operator, RightValue: rightValue}    ......    default:        err = fmt.Errorf("not_supported_method")    }    return}

返回的Funtion是个interface类型，AllFunction、AvgFunction都实现了这个interface:

// modules/judge/store/func.gotype Function interface {    Compute(L *SafeLinkedList) (vs []*model.HistoryData, leftValue float64, isTriggered bool, isEnough bool)}

3. fn如何计算

fn的计算形式都在其实现的Compute()办法内;

AllFunction须要最近的点都要满足：

func (this AllFunction) Compute(L *SafeLinkedList) (vs []*model.HistoryData, leftValue float64, isTriggered bool, isEnough bool) {    vs, isEnough = L.HistoryData(this.Limit)    if !isEnough {        return    }    isTriggered = true    for i := 0; i < this.Limit; i++ {        isTriggered = checkIsTriggered(vs[i].Value, this.Operator, this.RightValue)        if !isTriggered {            break        }    }    leftValue = vs[0].Value    return}

checkIsTriggered()就是简略的数值判断：

// modules/judge/store/func.gofunc checkIsTriggered(leftValue float64, operator string, rightValue float64) (isTriggered bool) {    switch operator {    case "=", "==":        isTriggered = math.Abs(leftValue-rightValue) < 0.0001    case "!=":        isTriggered = math.Abs(leftValue-rightValue) > 0.0001    case "<":        isTriggered = leftValue < rightValue    case "<=":        isTriggered = leftValue <= rightValue    case ">":        isTriggered = leftValue > rightValue    case ">=":        isTriggered = leftValue >= rightValue    }    return}

MaxFunction须要最近N个点的最大值满足阈值：

func (this MaxFunction) Compute(L *SafeLinkedList) (vs []*model.HistoryData, leftValue float64, isTriggered bool, isEnough bool) {    vs, isEnough = L.HistoryData(this.Limit)    if !isEnough {        return    }    // 先计算最大值    max := vs[0].Value    for i := 1; i < this.Limit; i++ {        if max < vs[i].Value {            max = vs[i].Value        }    }    leftValue = max    // 断定最大值是否触发阈值    isTriggered = checkIsTriggered(leftValue, this.Operator, this.RightValue)    return}