Round Tripper of Fission Router: parameters be configurable (#713)

The Round Tripper parameters of timeout, keep alive time and Max retry
times is configured in router system environment.

And they are set to Round Tripper when router service initializing.

This setup new nested structure `tsRoundTripperParams` to transfer them.

router/functionHandler.go

@@ -33,18 +33,24 @@ import (
 	executorClient "github.com/fission/fission/executor/client"
 )
 
+type tsRoundTripperParams struct {
+	timeout         time.Duration
+	timeoutExponent int
+	keepAlive       time.Duration
+	maxRetries      int
+}
+
 type functionHandler struct {
-	fmap        *functionServiceMap
-	executor    *executorClient.Client
-	function    *metav1.ObjectMeta
-	httpTrigger *crd.HTTPTrigger
+	fmap                 *functionServiceMap
+	executor             *executorClient.Client
+	function             *metav1.ObjectMeta
+	httpTrigger          *crd.HTTPTrigger
+	tsRoundTripperParams *tsRoundTripperParams
 }
 
 // A layer on top of http.DefaultTransport, with retries.
 type RetryingRoundTripper struct {
-	maxRetries     int
-	initialTimeout time.Duration
-	funcHandler    *functionHandler
+	funcHandler *functionHandler
 }
 
 // RoundTrip is a custom transport with retries for http requests that forwards the request to the right serviceUrl, obtained
@@ -92,7 +98,6 @@ func (roundTripper RetryingRoundTripper) RoundTrip(req *http.Request) (resp *htt
 	}
 
 	// set the timeout for transport context
-	timeout := roundTripper.initialTimeout
 	transport := http.DefaultTransport.(*http.Transport)
 	// Disables caching, Please refer to issue and specifically comment: https://github.com/fission/fission/issues/723#issuecomment-398781995
 	transport.DisableKeepAlives = true
@@ -104,7 +109,9 @@ func (roundTripper RetryingRoundTripper) RoundTrip(req *http.Request) (resp *htt
 		needExecutor = true
 	}
 
-	for i := 0; i < roundTripper.maxRetries-1; i++ {
+	executingTimeout := roundTripper.funcHandler.tsRoundTripperParams.timeout
+
+	for i := 0; i < roundTripper.funcHandler.tsRoundTripperParams.maxRetries-1; i++ {
 		if needExecutor {
 			log.Printf("Calling getServiceForFunction for function: %s", roundTripper.funcHandler.function.Name)
 
@@ -149,8 +156,8 @@ func (roundTripper RetryingRoundTripper) RoundTrip(req *http.Request) (resp *htt
 
 		// over-riding default settings.
 		transport.DialContext = (&net.Dialer{
-			Timeout:   timeout,
-			KeepAlive: 30 * time.Second,
+			Timeout:   executingTimeout,
+			KeepAlive: roundTripper.funcHandler.tsRoundTripperParams.keepAlive,
 		}).DialContext
 
 		overhead := time.Since(startTime)
@@ -183,9 +190,11 @@ func (roundTripper RetryingRoundTripper) RoundTrip(req *http.Request) (resp *htt
 		// just retry after backing off for timeout period.
 		if serviceUrlFromExecutor {
 			log.Printf("request to %s errored out. backing off for %v before retrying",
-				req.URL.Host, timeout)
-			timeout *= time.Duration(2)
-			time.Sleep(timeout)
+				req.URL.Host, executingTimeout)
+
+			executingTimeout = executingTimeout * time.Duration(roundTripper.funcHandler.tsRoundTripperParams.timeoutExponent)
+			time.Sleep(executingTimeout)
+
 			needExecutor = false
 			continue
 		} else {
@@ -231,9 +240,7 @@ func (fh *functionHandler) handler(responseWriter http.ResponseWriter, request *
 	proxy := &httputil.ReverseProxy{
 		Director: director,
 		Transport: &RetryingRoundTripper{
-			initialTimeout: 50 * time.Millisecond,
-			maxRetries:     10,
-			funcHandler:    fh,
+			funcHandler: fh,
 		},
 	}