refactor: 优化指标统计逻辑，减少锁的使用，提高性能

internal/metrics/metrics.go

@@ -1,7 +1,6 @@
 package metrics
 
 import (
-	"sync"
 	"sync/atomic"
 	"time"
 )
@@ -10,13 +9,12 @@ import (
 // 只针对转发请求调用 Inc。
 
 type bucket struct {
-	second int64 // Unix 秒
-	count  int64
+	second atomic.Int64 // Unix 秒
+	count  atomic.Int64
 }
 
 var (
 	buckets [60]bucket
-	mu      sync.Mutex
 	total   atomic.Int64
 )
 
@@ -24,14 +22,18 @@ var (
 func Inc() {
 	now := time.Now().Unix()
 	idx := now % 60
-	mu.Lock()
 	b := &buckets[idx]
-	if b.second != now { // 该槽位属于旧秒，重置
-		b.second = now
-		b.count = 0
+	for {
+		sec := b.second.Load()
+		if sec == now {
+			b.count.Add(1)
+			break
+		}
+		if b.second.CompareAndSwap(sec, now) {
+			b.count.Store(1)
+			break
+		}
 	}
-	b.count++
-	mu.Unlock()
 	total.Add(1)
 }
 
@@ -39,10 +41,8 @@ func Inc() {
 func QPS() int64 {
 	now := time.Now().Unix()
 	idx := now % 60
-	mu.Lock()
-	b := buckets[idx]
-	mu.Unlock()
-	if b.second == now { return b.count }
+	b := &buckets[idx]
+	if b.second.Load() == now { return b.count.Load() }
 	return 0
 }
 
@@ -50,14 +50,12 @@ func QPS() int64 {
 func QPM() int64 {
 	now := time.Now().Unix()
 	var sum int64
-	mu.Lock()
-	for i := 0; i < 60; i++ {
-		b := buckets[i]
-		if now-b.second < 60 { // 在窗口内
-			sum += b.count
+	for i := range 60 {
+		sec := buckets[i].second.Load()
+		if sec <= now && now-sec < 60 { // 在窗口内
+			sum += buckets[i].count.Load()
 		}
 	}
-	mu.Unlock()
 	return sum
 }