From f5d49c5842169daa0de2f08509ae20ae8a3e1248 Mon Sep 17 00:00:00 2001
From: Teo Koon Peng <koonpeng@google.com>
Date: Wed, 27 Nov 2024 11:40:54 +0800
Subject: [PATCH 1/2] add exponential backoff when connection to server fails

Signed-off-by: Teo Koon Peng <koonpeng@google.com>
---
 src/go/cmd/http-relay-client/client/client.go | 51 +++++++++++--------
 1 file changed, 31 insertions(+), 20 deletions(-)

diff --git a/src/go/cmd/http-relay-client/client/client.go b/src/go/cmd/http-relay-client/client/client.go
index 325d5668..6ff7c7f8 100644
--- a/src/go/cmd/http-relay-client/client/client.go
+++ b/src/go/cmd/http-relay-client/client/client.go
@@ -718,31 +718,42 @@ func (c *Client) localProxy(remote, local *http.Client) error {
 	relayURL := c.buildRelayURL()
 
 	var req *pb.HttpRequest = nil
-	var err error = nil
 
-	deadline := time.Now().Add(5 * time.Second)
-	for time.Now().Before(deadline) {
+	exponentialBackoff := backoff.ExponentialBackOff{
+		InitialInterval:     time.Second,
+		RandomizationFactor: 0,
+		Multiplier:          1.5,
+		MaxInterval:         10 * time.Second,
+		MaxElapsedTime:      60 * time.Second,
+		Clock:               backoff.SystemClock,
+	}
+
+	err := backoff.RetryNotify(func() error {
+		var err error
 		req, err = c.getRequest(remote, relayURL)
-		if err != nil {
-			if errors.Is(err, ErrTimeout) {
-				return err
-			} else if errors.Is(err, ErrForbidden) {
-				slog.Error("failed to authenticate to cloud-api, restarting", ilog.Err(err))
-				os.Exit(1)
-			} else if errors.Is(err, syscall.ECONNREFUSED) {
-				slog.Warn("Failed to connect to relay server. Retrying.")
-				continue
-			} else {
-				return fmt.Errorf("failed to get request from relay: %v", err)
-			}
-		} else {
-			break
+		if errors.Is(err, ErrTimeout) {
+			return backoff.Permanent(err)
 		}
-	}
+		return err
+	}, &exponentialBackoff, func(err error, _ time.Duration) {
+		if err == nil {
+			return
+		}
+		if errors.Is(err, ErrForbidden) {
+			slog.Error("failed to authenticate to cloud-api, restarting", ilog.Err(err))
+			os.Exit(1)
+		} else if errors.Is(err, syscall.ECONNREFUSED) {
+			slog.Warn("Failed to connect to relay server. Retrying.")
+			return
+		}
+	})
 
 	if err != nil {
-		slog.Error("failed to connect to cloud-api, restarting", ilog.Err(err))
-		os.Exit(1)
+		if pe, ok := err.(*backoff.PermanentError); ok {
+			return fmt.Errorf("failed to get request from relay: %v", pe.Err)
+		} else {
+			return err
+		}
 	}
 
 	// Forward the request to the backend.

From a1a2ac3fc8204e831a38dc9c97eb7df952066e2c Mon Sep 17 00:00:00 2001
From: Teo Koon Peng <koonpeng@google.com>
Date: Mon, 2 Dec 2024 10:16:13 +0800
Subject: [PATCH 2/2] change initial interval to 100 ms; remove unneeded cast

Signed-off-by: Teo Koon Peng <koonpeng@google.com>
---
 src/go/cmd/http-relay-client/client/client.go | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/go/cmd/http-relay-client/client/client.go b/src/go/cmd/http-relay-client/client/client.go
index 6ff7c7f8..d734176a 100644
--- a/src/go/cmd/http-relay-client/client/client.go
+++ b/src/go/cmd/http-relay-client/client/client.go
@@ -720,7 +720,7 @@ func (c *Client) localProxy(remote, local *http.Client) error {
 	var req *pb.HttpRequest = nil
 
 	exponentialBackoff := backoff.ExponentialBackOff{
-		InitialInterval:     time.Second,
+		InitialInterval:     100 * time.Millisecond,
 		RandomizationFactor: 0,
 		Multiplier:          1.5,
 		MaxInterval:         10 * time.Second,
@@ -749,11 +749,7 @@ func (c *Client) localProxy(remote, local *http.Client) error {
 	})
 
 	if err != nil {
-		if pe, ok := err.(*backoff.PermanentError); ok {
-			return fmt.Errorf("failed to get request from relay: %v", pe.Err)
-		} else {
-			return err
-		}
+		return err
 	}
 
 	// Forward the request to the backend.