[3.4] backport: add backoff to client config

Signed-off-by: Allen Ray <alray@redhat.com>

clientv3/client.go

@@ -212,15 +212,30 @@ func (c *Client) dialSetupOpts(creds grpccredentials.TransportCredentials, dopts
 		opts = append(opts, grpc.WithInsecure())
 	}
 
+	unaryMaxRetries := defaultUnaryMaxRetries
+	if c.cfg.MaxUnaryRetries > 0 {
+		unaryMaxRetries = c.cfg.MaxUnaryRetries
+	}
+
+	backoffWaitBetween := defaultBackoffWaitBetween
+	if c.cfg.BackoffWaitBetween > 0 {
+		backoffWaitBetween = c.cfg.BackoffWaitBetween
+	}
+
+	backoffJitterFraction := defaultBackoffJitterFraction
+	if c.cfg.BackoffJitterFraction > 0 {
+		backoffJitterFraction = c.cfg.BackoffJitterFraction
+	}
+
 	// Interceptor retry and backoff.
 	// TODO: Replace all of clientv3/retry.go with RetryPolicy:
 	// https://github.com/grpc/grpc-proto/blob/cdd9ed5c3d3f87aef62f373b93361cf7bddc620d/grpc/service_config/service_config.proto#L130
-	rrBackoff := withBackoff(c.roundRobinQuorumBackoff(defaultBackoffWaitBetween, defaultBackoffJitterFraction))
+	rrBackoff := withBackoff(c.roundRobinQuorumBackoff(backoffWaitBetween, backoffJitterFraction))
 	opts = append(opts,
 		// Disable stream retry by default since go-grpc-middleware/retry does not support client streams.
 		// Streams that are safe to retry are enabled individually.
 		grpc.WithStreamInterceptor(c.streamClientInterceptor(c.lg, withMax(0), rrBackoff)),
-		grpc.WithUnaryInterceptor(c.unaryClientInterceptor(c.lg, withMax(defaultUnaryMaxRetries), rrBackoff)),
+		grpc.WithUnaryInterceptor(c.unaryClientInterceptor(c.lg, withMax(unaryMaxRetries), rrBackoff)),
 	)
 
 	return opts, nil

clientv3/client_test.go

@@ -142,6 +142,57 @@ func TestDialNoTimeout(t *testing.T) {
 	c.Close()
 }
 
+func TestMaxUnaryRetries(t *testing.T) {
+	maxUnaryRetries := uint(10)
+	cfg := Config{
+		Endpoints:       []string{"127.0.0.1:12345"},
+		MaxUnaryRetries: maxUnaryRetries,
+	}
+	c, err := New(cfg)
+	if c == nil || err != nil {
+		t.Fatalf("new client with MaxUnaryRetries should succeed, got %v", err)
+	}
+	defer c.Close()
+
+	if c.cfg.MaxUnaryRetries != maxUnaryRetries {
+		t.Fatalf("client MaxUnaryRetries should be %d, got %d", maxUnaryRetries, c.cfg.MaxUnaryRetries)
+	}
+}
+
+func TestBackoff(t *testing.T) {
+	backoffWaitBetween := 100 * time.Millisecond
+	cfg := Config{
+		Endpoints:          []string{"127.0.0.1:12345"},
+		BackoffWaitBetween: backoffWaitBetween,
+	}
+	c, err := New(cfg)
+	if c == nil || err != nil {
+		t.Fatalf("new client with BackoffWaitBetween should succeed, got %v", err)
+	}
+	defer c.Close()
+
+	if c.cfg.BackoffWaitBetween != backoffWaitBetween {
+		t.Fatalf("client BackoffWaitBetween should be %v, got %v", backoffWaitBetween, c.cfg.BackoffWaitBetween)
+	}
+}
+
+func TestBackoffJitterFraction(t *testing.T) {
+	backoffJitterFraction := float64(0.9)
+	cfg := Config{
+		Endpoints:             []string{"127.0.0.1:12345"},
+		BackoffJitterFraction: backoffJitterFraction,
+	}
+	c, err := New(cfg)
+	if c == nil || err != nil {
+		t.Fatalf("new client with BackoffJitterFraction should succeed, got %v", err)
+	}
+	defer c.Close()
+
+	if c.cfg.BackoffJitterFraction != backoffJitterFraction {
+		t.Fatalf("client BackoffJitterFraction should be %v, got %v", backoffJitterFraction, c.cfg.BackoffJitterFraction)
+	}
+}
+
 func TestIsHaltErr(t *testing.T) {
 	if !isHaltErr(nil, fmt.Errorf("etcdserver: some etcdserver error")) {
 		t.Errorf(`error prefixed with "etcdserver: " should be Halted by default`)

clientv3/config.go

@@ -84,5 +84,14 @@ type Config struct {
 	// PermitWithoutStream when set will allow client to send keepalive pings to server without any active streams(RPCs).
 	PermitWithoutStream bool `json:"permit-without-stream"`
 
+	// MaxUnaryRetries is the maximum number of retries for unary RPCs.
+	MaxUnaryRetries uint `json:"max-unary-retries"`
+
+	// BackoffWaitBetween is the wait time before retrying an RPC.
+	BackoffWaitBetween time.Duration `json:"backoff-wait-between"`
+
+	// BackoffJitterFraction is the jitter fraction to randomize backoff wait time.
+	BackoffJitterFraction float64 `json:"backoff-jitter-fraction"`
+
 	// TODO: support custom balancer picker
 }