http2: add configuration options when constructing http2 transport

This allows the caller to change some configurations of the http2
transport when constructing it from an http1 transport.

Author: Chao Xu

http2/transport.go

@@ -152,19 +152,47 @@ func (t *Transport) pingTimeout() time.Duration {
 
 }
 
+// TransportOptions contains options to configure HTTP/2 transport.
+type TransportOptions struct {
+	// ReadIdleTimeout is the timeout after which a health check using ping
+	// frame will be carried out if no frame is received on the connection.
+	// Note that a ping response will is considered a received frame, so if
+	// there is no other traffic on the connection, the health check will
+	// be performed every ReadIdleTimeout interval.
+	// If zero, no health check is performed.
+	ReadIdleTimeout time.Duration
+
+	// PingTimeout is the timeout after which the connection will be closed
+	// if a response to Ping is not received.
+	// Defaults to 15s.
+	PingTimeout time.Duration
+}
+
+// ConfigureTransport configures a net/http HTTP/1 Transport to use HTTP/2.
+// The options can be used to configure the HTTP/2 Transport.
+// It returns an error if t1 has already been HTTP/2-enabled.
+func ConfigureTransportWithOptions(t1 *http.Transport, o *TransportOptions) error {
+	_, err := configureTransport(t1, o)
+	return err
+}
+
 // ConfigureTransport configures a net/http HTTP/1 Transport to use HTTP/2.
 // It returns an error if t1 has already been HTTP/2-enabled.
 func ConfigureTransport(t1 *http.Transport) error {
-	_, err := configureTransport(t1)
+	_, err := configureTransport(t1, nil)
 	return err
 }
 
-func configureTransport(t1 *http.Transport) (*Transport, error) {
+func configureTransport(t1 *http.Transport, o *TransportOptions) (*Transport, error) {
 	connPool := new(clientConnPool)
 	t2 := &Transport{
 		ConnPool: noDialClientConnPool{connPool},
 		t1:       t1,
 	}
+	if o != nil {
+		t2.ReadIdleTimeout = o.ReadIdleTimeout
+		t2.PingTimeout = o.PingTimeout
+	}
 	connPool.t = t2
 	if err := registerHTTPSProtocol(t1, noDialH2RoundTripper{t2}); err != nil {
 		return nil, err

http2/transport_test.go

@@ -32,6 +32,7 @@ import (
 	"sync/atomic"
 	"testing"
 	"time"
+	"unsafe"
 
 	"golang.org/x/net/http2/hpack"
 )
@@ -594,6 +595,27 @@ func TestTransportDialTLS(t *testing.T) {
 	}
 }
 
+func TestConfigureTransportWithOptions(t *testing.T) {
+	t1 := &http.Transport{}
+	o := &TransportOptions{ReadIdleTimeout: 10, PingTimeout: 10}
+	err := ConfigureTransportWithOptions(t1, o)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rf := reflect.ValueOf(t1).Elem().FieldByName("altProto")
+	rf = reflect.NewAt(rf.Type(), unsafe.Pointer(rf.UnsafeAddr())).Elem()
+	v := rf.Interface().(atomic.Value)
+	altProto := v.Load().(map[string]http.RoundTripper)
+	rt := (altProto["https"]).(noDialH2RoundTripper)
+	t2 := rt.Transport
+	if e, a := o.ReadIdleTimeout, t2.ReadIdleTimeout; e != a {
+		t.Errorf("expected ReadIdleTimeout to be %d, got %d", e, a)
+	}
+	if e, a := o.PingTimeout, t2.PingTimeout; e != a {
+		t.Errorf("expected PingTimeout to be %d, got %d", e, a)
+	}
+}
+
 func TestConfigureTransport(t *testing.T) {
 	t1 := &http.Transport{}
 	err := ConfigureTransport(t1)