refactor(server/pprof): 简化 switch 语句并移除未使用变量

- 将 switch 语句改为更简洁的 case 匹配形式
- 移除未使用的 cpuProfileWriter 变量
- 忽略 Flush/WriteTo 等无关的错误返回值

Co-Authored-By: Claude <noreply@anthropic.com>

internal/server/pprof.go

@@ -105,18 +105,18 @@ func (h *PprofHandler) ServeHTTP(ctx *fasthttp.RequestCtx) {
 	path := string(ctx.Path())
 	subPath := path[len(h.path):]
 
-	switch {
-	case subPath == "" || subPath == "/":
+	switch subPath {
+	case "", "/":
 		h.handleIndex(ctx)
-	case subPath == "/profile":
+	case "/profile":
 		h.handleCPU(ctx)
-	case subPath == "/heap":
+	case "/heap":
 		h.handleHeap(ctx)
-	case subPath == "/goroutine":
+	case "/goroutine":
 		h.handleGoroutine(ctx)
-	case subPath == "/block":
+	case "/block":
 		h.handleBlock(ctx)
-	case subPath == "/mutex":
+	case "/mutex":
 		h.handleMutex(ctx)
 	default:
 		ctx.SetStatusCode(fasthttp.StatusNotFound)
@@ -187,8 +187,8 @@ func (h *PprofHandler) handleCPU(ctx *fasthttp.RequestCtx) {
 	ctx.SetBodyStreamWriter(func(w *bufio.Writer) {
 		// 启动 CPU profile
 		if err := startCPUProfile(wrapBufioWriter(w)); err != nil {
-			w.WriteString("Error starting CPU profile: " + err.Error())
-			w.Flush()
+			_, _ = w.WriteString("Error starting CPU profile: " + err.Error())
+			_ = w.Flush()
 			return
 		}
 
@@ -197,7 +197,7 @@ func (h *PprofHandler) handleCPU(ctx *fasthttp.RequestCtx) {
 
 		// 厉止 CPU profile
 		stopCPUProfile()
-		w.Flush()
+		_ = w.Flush()
 	})
 }
 
@@ -206,7 +206,7 @@ func (h *PprofHandler) handleHeap(ctx *fasthttp.RequestCtx) {
 	ctx.SetContentType("application/octet-stream")
 	ctx.SetBodyStreamWriter(func(w *bufio.Writer) {
 		writeHeapProfile(wrapBufioWriter(w))
-		w.Flush()
+		_ = w.Flush()
 	})
 }
 
@@ -215,7 +215,7 @@ func (h *PprofHandler) handleGoroutine(ctx *fasthttp.RequestCtx) {
 	ctx.SetContentType("application/octet-stream")
 	ctx.SetBodyStreamWriter(func(w *bufio.Writer) {
 		writeGoroutineProfile(wrapBufioWriter(w))
-		w.Flush()
+		_ = w.Flush()
 	})
 }
 
@@ -224,7 +224,7 @@ func (h *PprofHandler) handleBlock(ctx *fasthttp.RequestCtx) {
 	ctx.SetContentType("application/octet-stream")
 	ctx.SetBodyStreamWriter(func(w *bufio.Writer) {
 		writeBlockProfile(wrapBufioWriter(w))
-		w.Flush()
+		_ = w.Flush()
 	})
 }
 
@@ -233,6 +233,6 @@ func (h *PprofHandler) handleMutex(ctx *fasthttp.RequestCtx) {
 	ctx.SetContentType("application/octet-stream")
 	ctx.SetBodyStreamWriter(func(w *bufio.Writer) {
 		writeMutexProfile(wrapBufioWriter(w))
-		w.Flush()
+		_ = w.Flush()
 	})
-}
+}

internal/server/pprof_impl.go

@@ -14,8 +14,7 @@ import (
 )
 
 var (
-	cpuProfileMu    sync.Mutex
-	cpuProfileWriter io.Writer
+	cpuProfileMu     sync.Mutex
 	cpuProfileActive bool
 )
 
@@ -38,7 +37,6 @@ func startCPUProfile(w io.Writer) error {
 		return err
 	}
 
-	cpuProfileWriter = w
 	cpuProfileActive = true
 	return nil
 }
@@ -51,21 +49,20 @@ func stopCPUProfile() {
 	if cpuProfileActive {
 		pprof.StopCPUProfile()
 		cpuProfileActive = false
-		cpuProfileWriter = nil
 	}
 }
 
 // writeHeapProfile 写入内存分配 profile。
 func writeHeapProfile(w io.Writer) {
 	runtime.GC() // 先执行 GC，获取更准确的数据
-	pprof.WriteHeapProfile(w)
+	_ = pprof.WriteHeapProfile(w)
 }
 
 // writeGoroutineProfile 写入 Goroutine stack traces。
 func writeGoroutineProfile(w io.Writer) {
 	p := pprof.Lookup("goroutine")
 	if p != nil {
-		p.WriteTo(w, 0)
+		_ = p.WriteTo(w, 0)
 	}
 }
 
@@ -73,7 +70,7 @@ func writeGoroutineProfile(w io.Writer) {
 func writeBlockProfile(w io.Writer) {
 	p := pprof.Lookup("block")
 	if p != nil {
-		p.WriteTo(w, 0)
+		_ = p.WriteTo(w, 0)
 	}
 }
 
@@ -81,7 +78,7 @@ func writeBlockProfile(w io.Writer) {
 func writeMutexProfile(w io.Writer) {
 	p := pprof.Lookup("mutex")
 	if p != nil {
-		p.WriteTo(w, 0)
+		_ = p.WriteTo(w, 0)
 	}
 }
 
@@ -93,7 +90,7 @@ type bufioWriterAdapter struct {
 func (a *bufioWriterAdapter) Write(p []byte) (n int, err error) {
 	n, err = a.w.Write(p)
 	if err == nil {
-		a.w.Flush()
+		_ = a.w.Flush()
 	}
 	return n, err
 }
@@ -101,4 +98,4 @@ func (a *bufioWriterAdapter) Write(p []byte) (n int, err error) {
 // wrapBufioWriter 将 bufio.Writer 包装为 io.Writer。
 func wrapBufioWriter(w *bufio.Writer) io.Writer {
 	return &bufioWriterAdapter{w: w}
-}
+}