perf: 端口扫描自适应超时，基于 RTT 采样动态调整连接超时

core/adaptive_timeout.go

@@ -0,0 +1,92 @@
+package core
+
+import (
+	"math"
+	"sync"
+	"time"
+)
+
+// AdaptiveTimeout 基于 RTT 采样的自适应超时计算器
+// 算法：timeout = mean(RTT) + 4 * stddev(RTT)，clamp 到 [min, max]
+// 冷启动阶段（样本不足）返回用户配置的固定超时
+type AdaptiveTimeout struct {
+	mu       sync.Mutex
+	samples  []float64 // 环形缓冲区，单位 ms
+	pos      int       // 写入位置
+	count    int       // 已采集总数
+	size     int       // 缓冲区容量
+	minTO    time.Duration
+	maxTO    time.Duration
+	warmup   int // 冷启动所需最小样本数
+	cachedTO time.Duration
+	dirty    bool
+}
+
+// NewAdaptiveTimeout 创建自适应超时计算器
+// maxTimeout: 用户配置的超时上限（即原始固定超时）
+func NewAdaptiveTimeout(maxTimeout time.Duration) *AdaptiveTimeout {
+	return &AdaptiveTimeout{
+		samples: make([]float64, 64),
+		size:    64,
+		minTO:   100 * time.Millisecond,
+		maxTO:   maxTimeout,
+		warmup:  10,
+	}
+}
+
+// Record 记录一次成功连接的 RTT
+func (a *AdaptiveTimeout) Record(rtt time.Duration) {
+	a.mu.Lock()
+	a.samples[a.pos%a.size] = float64(rtt.Milliseconds())
+	a.pos++
+	a.count++
+	a.dirty = true
+	a.mu.Unlock()
+}
+
+// Timeout 获取当前推荐超时值
+// 样本不足时返回 maxTO（冷启动）
+func (a *AdaptiveTimeout) Timeout() time.Duration {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	if a.count < a.warmup {
+		return a.maxTO
+	}
+
+	if !a.dirty {
+		return a.cachedTO
+	}
+
+	n := a.size
+	if a.count < a.size {
+		n = a.count
+	}
+
+	var sum float64
+	for i := 0; i < n; i++ {
+		sum += a.samples[i]
+	}
+	mean := sum / float64(n)
+
+	var variance float64
+	for i := 0; i < n; i++ {
+		d := a.samples[i] - mean
+		variance += d * d
+	}
+	stddev := math.Sqrt(variance / float64(n))
+
+	ms := mean + 4*stddev
+	to := time.Duration(ms) * time.Millisecond
+
+	if to < a.minTO {
+		to = a.minTO
+	}
+	if to > a.maxTO {
+		to = a.maxTO
+	}
+
+	a.cachedTO = to
+	a.dirty = false
+	return to
+}