feat: add comprehensive tests for StreamScannerHandler functionality

- Introduced a new test file for StreamScannerHandler, covering various scenarios including nil inputs, empty bodies, chunk processing, order preservation, and handler failures.
- Enhanced error handling and data processing logic in StreamScannerHandler to improve robustness and performance.

relay/helper/stream_scanner.go

@@ -176,10 +176,32 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 		})
 	}
 
+	dataChan := make(chan string, 10)
+
+	wg.Add(1)
+	gopool.Go(func() {
+		defer func() {
+			wg.Done()
+			if r := recover(); r != nil {
+				logger.LogError(c, fmt.Sprintf("data handler goroutine panic: %v", r))
+			}
+			common.SafeSendBool(stopChan, true)
+		}()
+		for data := range dataChan {
+			writeMutex.Lock()
+			success := dataHandler(data)
+			writeMutex.Unlock()
+			if !success {
+				return
+			}
+		}
+	})
+
 	// Scanner goroutine with improved error handling
 	wg.Add(1)
 	common.RelayCtxGo(ctx, func() {
 		defer func() {
+			close(dataChan)
 			wg.Done()
 			if r := recover(); r != nil {
 				logger.LogError(c, fmt.Sprintf("scanner goroutine panic: %v", r))
@@ -222,22 +244,9 @@ func StreamScannerHandler(c *gin.Context, resp *http.Response, info *relaycommon
 			if !strings.HasPrefix(data, "[DONE]") {
 				info.SetFirstResponseTime()
 				info.ReceivedResponseCount++
-				// 使用超时机制防止写操作阻塞
-				done := make(chan bool, 1)
-				gopool.Go(func() {
-					writeMutex.Lock()
-					defer writeMutex.Unlock()
-					done <- dataHandler(data)
-				})
 
 				select {
-				case success := <-done:
-					if !success {
-						return
-					}
-				case <-time.After(10 * time.Second):
-					logger.LogError(c, "data handler timeout")
-					return
+				case dataChan <- data:
 				case <-ctx.Done():
 					return
 				case <-stopChan: