http2: add IdleConnTimeout to http2.Transport

Exposes an IdleConnTimeout on http2.Transport directly, rather than rely on configuring it through the underlying http1 transport.

For golang/go#57893

Change-Id: Ibe506da39e314aebec1cd6df64937982182a37ca
GitHub-Last-Rev: cc8f171
GitHub-Pull-Request: #173
Reviewed-on: https://go-review.googlesource.com/c/net/+/497195
Reviewed-by: Damien Neil <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>

Author: dastbe

http2/transport.go

@@ -147,6 +147,12 @@ type Transport struct {
 	// waiting for their turn.
 	StrictMaxConcurrentStreams bool
 
+	// IdleConnTimeout is the maximum amount of time an idle
+	// (keep-alive) connection will remain idle before closing
+	// itself.
+	// Zero means no limit.
+	IdleConnTimeout time.Duration
+
 	// 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
@@ -3150,9 +3156,17 @@ func (rt noDialH2RoundTripper) RoundTrip(req *http.Request) (*http.Response, err
 }
 
 func (t *Transport) idleConnTimeout() time.Duration {
+	// to keep things backwards compatible, we use non-zero values of
+	// IdleConnTimeout, followed by using the IdleConnTimeout on the underlying
+	// http1 transport, followed by 0
+	if t.IdleConnTimeout != 0 {
+		return t.IdleConnTimeout
+	}
+
 	if t.t1 != nil {
 		return t.t1.IdleConnTimeout
 	}
+
 	return 0
 }
 

http2/transport_test.go

@@ -95,6 +95,68 @@ func startH2cServer(t *testing.T) net.Listener {
 	return l
 }
 
+func TestIdleConnTimeout(t *testing.T) {
+	for _, test := range []struct {
+		idleConnTimeout time.Duration
+		wait            time.Duration
+		baseTransport   *http.Transport
+		wantConns       int32
+	}{{
+		idleConnTimeout: 2 * time.Second,
+		wait:            1 * time.Second,
+		baseTransport:   nil,
+		wantConns:       1,
+	}, {
+		idleConnTimeout: 1 * time.Second,
+		wait:            2 * time.Second,
+		baseTransport:   nil,
+		wantConns:       5,
+	}, {
+		idleConnTimeout: 0 * time.Second,
+		wait:            1 * time.Second,
+		baseTransport: &http.Transport{
+			IdleConnTimeout: 2 * time.Second,
+		},
+		wantConns: 1,
+	}} {
+		var gotConns int32
+
+		st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
+			io.WriteString(w, r.RemoteAddr)
+		}, optOnlyServer)
+		defer st.Close()
+
+		tr := &Transport{
+			IdleConnTimeout: test.idleConnTimeout,
+			TLSClientConfig: tlsConfigInsecure,
+		}
+		defer tr.CloseIdleConnections()
+
+		for i := 0; i < 5; i++ {
+			req, _ := http.NewRequest("GET", st.ts.URL, http.NoBody)
+			trace := &httptrace.ClientTrace{
+				GotConn: func(connInfo httptrace.GotConnInfo) {
+					if !connInfo.Reused {
+						atomic.AddInt32(&gotConns, 1)
+					}
+				},
+			}
+			req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
+
+			_, err := tr.RoundTrip(req)
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+
+			<-time.After(test.wait)
+		}
+
+		if gotConns != test.wantConns {
+			t.Errorf("incorrect gotConns: %d != %d", gotConns, test.wantConns)
+		}
+	}
+}
+
 func TestTransportH2c(t *testing.T) {
 	l := startH2cServer(t)
 	defer l.Close()