net/http: update bundled http2, pass through Transport.CloseIdleConnections

Wire up Transport.CloseIdleConnections to http2.Transport.CloseIdleConnections.

Updates x/net/http2 to git rev c92cdcb0 for https://golang.org/cl/18678

Fixes #13975

Change-Id: I1183a31256104ff95ae7621e5788cfeee741b1aa
Reviewed-on: https://go-review.googlesource.com/18679Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/http/h2_bundle.go

@@ -246,11 +246,11 @@ func http2filterOutClientConn(in []*http2ClientConn, exclude *http2ClientConn) [
 	return out
 }
 
-func http2configureTransport(t1 *Transport) error {
+func http2configureTransport(t1 *Transport) (*http2Transport, error) {
 	connPool := new(http2clientConnPool)
 	t2 := &http2Transport{ConnPool: http2noDialClientConnPool{connPool}}
 	if err := http2registerHTTPSProtocol(t1, http2noDialH2RoundTripper{t2}); err != nil {
-		return err
+		return nil, err
 	}
 	if t1.TLSClientConfig == nil {
 		t1.TLSClientConfig = new(tls.Config)
@@ -279,7 +279,7 @@ func http2configureTransport(t1 *Transport) error {
 	} else {
 		m["h2"] = upgradeFn
 	}
-	return nil
+	return t2, nil
 }
 
 // registerHTTPSProtocol calls Transport.RegisterProtocol but
@@ -4348,7 +4348,8 @@ var http2errTransportVersion = errors.New("http2: ConfigureTransport is only sup
 // It requires Go 1.6 or later and returns an error if the net/http package is too old
 // or if t1 has already been HTTP/2-enabled.
 func http2ConfigureTransport(t1 *Transport) error {
-	return http2configureTransport(t1)
+	_, err := http2configureTransport(t1)
+	return err
 }
 
 func (t *http2Transport) connPool() http2ClientConnPool {

src/net/http/transport.go

@@ -142,10 +142,14 @@ type Transport struct {
 	// If TLSNextProto is nil, HTTP/2 support is enabled automatically.
 	TLSNextProto map[string]func(authority string, c *tls.Conn) RoundTripper
 
-	nextProtoOnce sync.Once // guards initialization of TLSNextProto (onceSetNextProtoDefaults)
+	// nextProtoOnce guards initialization of TLSNextProto and
+	// h2transport (via onceSetNextProtoDefaults)
+	nextProtoOnce sync.Once
+	h2transport   *http2Transport // non-nil if http2 wired up
 
 	// TODO: tunable on global max cached connections
 	// TODO: tunable on timeout on cached connections
+	// TODO: tunable on max per-host TCP dials in flight (Issue 13957)
 }
 
 // onceSetNextProtoDefaults initializes TLSNextProto.
@@ -157,9 +161,11 @@ func (t *Transport) onceSetNextProtoDefaults() {
 	if t.TLSNextProto != nil {
 		return
 	}
-	err := http2ConfigureTransport(t)
+	t2, err := http2configureTransport(t)
 	if err != nil {
 		log.Printf("Error enabling Transport HTTP/2 support: %v", err)
+	} else {
+		t.h2transport = t2
 	}
 }
 
@@ -367,6 +373,7 @@ func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) {
 // a "keep-alive" state. It does not interrupt any connections currently
 // in use.
 func (t *Transport) CloseIdleConnections() {
+	t.nextProtoOnce.Do(t.onceSetNextProtoDefaults)
 	t.idleMu.Lock()
 	m := t.idleConn
 	t.idleConn = nil
@@ -378,6 +385,9 @@ func (t *Transport) CloseIdleConnections() {
 			pconn.close(errCloseIdleConns)
 		}
 	}
+	if t2 := t.h2transport; t2 != nil {
+		t2.CloseIdleConnections()
+	}
 }
 
 // CancelRequest cancels an in-flight request by closing its connection.