http2: do not retry dial if request context canceled

http2/client_conn_pool.go

@@ -94,9 +94,13 @@ func (p *clientConnPool) getClientConn(req *http.Request, addr string, dialOnMis
 		traceGetConn(req, addr)
 		call := p.getStartDialLocked(req.Context(), addr)
 		p.mu.Unlock()
-		<-call.done
-		if shouldRetryDial(call, req) {
-			continue
+		select {
+		case <-call.done:
+			if shouldRetryDial(call, req) {
+				continue
+			}
+		case <-req.Context().Done():
+			return nil, req.Context().Err()
 		}
 		cc, err := call.res, call.err
 		if err != nil {

http2/clientconn_test.go

@@ -10,10 +10,13 @@ package http2
 import (
 	"bytes"
 	"context"
+	"crypto/tls"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"reflect"
+	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -79,6 +82,56 @@ func TestTestClientConn(t *testing.T) {
 	rt.wantBody(nil)
 }
 
+// TestConnectTimeout tests that a request does not exceed request timeout + dial timeout
+func TestConnectTimeout(t *testing.T) {
+	tr := &Transport{
+		DialTLSContext: func(ctx context.Context, network, addr string, cfg *tls.Config) (net.Conn, error) {
+			// mock a net dialler with 1s timeout, encountering network issue
+			// keeping dialing until timeout
+			var dialer = net.Dialer{Timeout: time.Duration(-1)}
+			select {
+			case <-time.After(time.Second):
+			case <-ctx.Done():
+			}
+			return dialer.DialContext(ctx, network, addr)
+		},
+		AllowHTTP: true,
+	}
+
+	var sg sync.WaitGroup
+	parentCtx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	for j := 0; j < 2; j++ {
+		sg.Add(1)
+		go func() {
+			for i := 0; i < 10000; i++ {
+				sg.Add(1)
+				go func() {
+					ctx, _ := context.WithTimeout(parentCtx, time.Second)
+					req, err := http.NewRequestWithContext(ctx, "GET", "http://127.0.0.1:80", nil)
+					if err != nil {
+						t.Errorf("NewRequest: %v", err)
+					}
+
+					start := time.Now()
+					tr.RoundTrip(req)
+					duration := time.Since(start)
+					// duration should not exceed request timeout + dial timeout
+					if duration > 2*time.Second {
+						t.Errorf("RoundTrip took %s; want <2s", duration.String())
+					}
+					sg.Done()
+				}()
+				time.Sleep(1 * time.Millisecond)
+			}
+			sg.Done()
+		}()
+	}
+
+	sg.Wait()
+}
+
 // A testClientConn allows testing ClientConn.RoundTrip against a fake server.
 //
 // A test using testClientConn consists of: