101 lines
2.6 KiB
Go
101 lines
2.6 KiB
Go
package dispatch
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import (
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"math"
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)
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// EffectiveWeight 权重合成函数 W(c)（纯函数）。
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//
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// W(c) = baseWeight × tierFactor × healthFactor × headroom^γ × costFactor × rampFactor
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//
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// 返回合成权重与分解明细（供决策日志 / ForwardingTrace）。
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func EffectiveWeight(c Channel, pol *RoutingPolicy) (float64, WeightBreakdown) {
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bd := WeightBreakdown{
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Base: c.BaseWeight,
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Tier: tierFactor(c.Tier, pol),
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Health: healthFactor(c, pol),
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Headroom: headroomFactor(c, pol),
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Cost: costFactor(c, pol),
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Ramp: rampFactor(c, pol),
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}
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if bd.Base <= 0 {
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bd.Base = 0
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}
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bd.Effective = bd.Base * bd.Tier * bd.Health * bd.Headroom * bd.Cost * bd.Ramp
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return bd.Effective, bd
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}
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// tierFactor 层级偏置。未配置的层级视为 0（不参与，由扩组兜底救回）。
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func tierFactor(t Tier, pol *RoutingPolicy) float64 {
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f, ok := pol.TierFactors[t]
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if !ok {
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return 0
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}
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return math.Max(f, 0)
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}
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// healthFactor 健康因子：
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//
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// clamp(succEwma, 0.01, 1)^α × latencyPenalty
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// latencyPenalty = clamp(latRef / max(latEwma, latRef), 0.5, 1.0)
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func healthFactor(c Channel, pol *RoutingPolicy) float64 {
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succ := c.SuccEwma
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if succ <= 0 && c.LatEwmaMs == 0 {
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// 无任何健康数据（新渠道）视为满分
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succ = 1
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}
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succ = clamp(succ, 0.01, 1.0)
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f := math.Pow(succ, pol.Health.Alpha)
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latRef := pol.Health.LatRefMs
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if latRef > 0 && c.LatEwmaMs > latRef {
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f *= clamp(latRef/c.LatEwmaMs, 0.5, 1.0)
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}
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return f
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}
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// headroomFactor 负载余量因子：(1 - inflight/softLimit)^γ。
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// 无容量信息（SoftLimit<=0）时恒为 1。
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func headroomFactor(c Channel, pol *RoutingPolicy) float64 {
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if c.SoftLimit <= 0 {
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return 1
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}
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headroom := 1 - float64(c.Inflight)/float64(c.SoftLimit)
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if headroom <= 0 {
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return 0
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}
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return math.Pow(headroom, pol.Load.Gamma)
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}
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// costFactor 成本因子：clamp((1/costRatio)^β, min, max)。
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// CostRatio 是无量纲比例（非金额，float64 不受 decimal 强约束），<=0 视为 1.0。
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func costFactor(c Channel, pol *RoutingPolicy) float64 {
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ratio := c.CostRatio
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if ratio <= 0 {
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ratio = 1.0
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}
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return clamp(math.Pow(1.0/ratio, pol.Cost.Beta), pol.Cost.Min, pol.Cost.Max)
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}
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// rampFactor 爬坡因子：新渠道 / 熔断恢复后从小流量爬坡。
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func rampFactor(c Channel, pol *RoutingPolicy) float64 {
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if c.RampElapsedMs < 0 {
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return 1
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}
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window := pol.Ramp.WindowSeconds * 1000
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if window <= 0 {
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return 1
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}
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return clamp(float64(c.RampElapsedMs)/float64(window), pol.Ramp.Floor, 1.0)
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}
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func clamp(v, lo, hi float64) float64 {
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if v < lo {
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return lo
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}
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if v > hi {
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return hi
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}
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return v
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}
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