Check CB Open and init connection for resolve hystrix attempt

Author: Runze Cui

redis.go

@@ -265,25 +265,39 @@ func (c *baseClient) withConn(
 		return err
 	}
 
-	// Request is allowed occasionally to close the cb and cb is still in open state
-	// Init the connection to avoid nested hystrix call during connection establishment
+	err := c.executeWithCircuitBreaker(ctx, fn, limiter)
+	limiter.ReportResult(err)
+	return err
+}
+
+func (c *baseClient) executeWithCircuitBreaker(
+	ctx context.Context,
+	fn func(context.Context, *pool.Conn) error,
+	limiter Limiter,
+) error {
+	// When circuit is open, try to establish connection first
+	// This is needed for circuit breaker recovery
 	if limiter.IsCBOpen() {
-		cn, err := c.getConn(ctx)
-		if err != nil {
+		if err := c.preConnect(ctx); err != nil {
 			return err
 		}
-
-		defer func() {
-			c.releaseConn(ctx, cn, err)
-		}()
 	}
 
-	err := limiter.Execute(func() error {
+	return limiter.Execute(func() error {
 		return c._withConn(ctx, fn)
 	})
+}
 
-	limiter.ReportResult(err)
-	return err
+func (c *baseClient) preConnect(ctx context.Context) error {
+	cn, err := c.getConn(ctx)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		c.releaseConn(ctx, cn, err)
+	}()
+	return nil
 }
 
 func (c *baseClient) _withConn(