http2: add a more full-featured test net.Conn

Add a net.Conn implementation that plays nicely with testsyncGroup,
implements read/write timeouts, and gives control over buffering
to let us write tests that cause writes to a Conn to block at
specific points in time.

Change-Id: I9d870b211ac9d938a8c4a221277981cdb821a6e4
Reviewed-on: https://go-review.googlesource.com/c/net/+/586246
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

http2/clientconn_test.go

@@ -10,11 +10,10 @@ package http2
 import (
 	"bytes"
 	"context"
-	"errors"
 	"fmt"
 	"io"
-	"net"
 	"net/http"
+	"os"
 	"reflect"
 	"runtime"
 	"slices"
@@ -104,7 +103,7 @@ type testClientConn struct {
 
 	roundtrips []*testRoundTrip
 
-	netconn testClientConnNetConn
+	netconn *synctestNetConn
 }
 
 func newTestClientConnFromClientConn(t *testing.T, cc *ClientConn) *testClientConn {
@@ -114,22 +113,21 @@ func newTestClientConnFromClientConn(t *testing.T, cc *ClientConn) *testClientCo
 		cc:    cc,
 		group: cc.t.transportTestHooks.group.(*synctestGroup),
 	}
+	cli, srv := synctestNetPipe(tc.group)
+	srv.SetReadDeadline(tc.group.Now())
+	tc.netconn = srv
 	tc.enc = hpack.NewEncoder(&tc.encbuf)
-	tc.netconn.gate = newGate()
 
 	// all writes and reads are finished.
 	//
 	// cli is the ClientConn's side, srv is the side controlled by the test.
-	cc.tconn = &tc.netconn
-	tc.fr = NewFramer(
-		(*testClientConnNetConnWriteToClient)(&tc.netconn),
-		(*testClientConnNetConnReadFromClient)(&tc.netconn),
-	)
+	cc.tconn = cli
+	tc.fr = NewFramer(srv, srv)
 
 	tc.fr.ReadMetaHeaders = hpack.NewDecoder(initialHeaderTableSize, nil)
 	tc.fr.SetMaxReadFrameSize(10 << 20)
 	t.Cleanup(func() {
-		tc.closeWrite(io.EOF)
+		tc.closeWrite()
 	})
 	return tc
 }
@@ -138,8 +136,7 @@ func (tc *testClientConn) readClientPreface() {
 	tc.t.Helper()
 	// Read the client's HTTP/2 preface, sent prior to any HTTP/2 frames.
 	buf := make([]byte, len(clientPreface))
-	r := (*testClientConnNetConnReadFromClient)(&tc.netconn)
-	if _, err := io.ReadFull(r, buf); err != nil {
+	if _, err := io.ReadFull(tc.netconn, buf); err != nil {
 		tc.t.Fatalf("reading preface: %v", err)
 	}
 	if !bytes.Equal(buf, clientPreface) {
@@ -174,26 +171,23 @@ func (tc *testClientConn) advance(d time.Duration) {
 
 // hasFrame reports whether a frame is available to be read.
 func (tc *testClientConn) hasFrame() bool {
-	tc.netconn.lock()
-	defer tc.netconn.unlock()
-	return tc.netconn.fromConn.Len() > 0
+	return len(tc.netconn.Peek()) > 0
 }
 
 func (tc *testClientConn) isClosed() bool {
-	tc.netconn.lock()
-	defer tc.netconn.unlock()
-	return tc.netconn.fromConnClosed
+	return tc.netconn.IsClosedByPeer()
 }
 
 // readFrame reads the next frame from the conn.
 func (tc *testClientConn) readFrame() Frame {
+	tc.t.Helper()
 	tc.sync()
 	fr, err := tc.fr.ReadFrame()
-	if err == io.EOF {
+	if err == io.EOF || err == os.ErrDeadlineExceeded {
 		return nil
 	}
 	if err != nil {
-		return nil
+		tc.t.Fatalf("ReadFrame: %v", err)
 	}
 	return fr
 }
@@ -597,10 +591,8 @@ func (tc *testClientConn) writeWindowUpdate(streamID, incr uint32) {
 
 // closeWrite causes the net.Conn used by the ClientConn to return a error
 // from Read calls.
-func (tc *testClientConn) closeWrite(err error) {
-	tc.netconn.lock()
-	tc.netconn.toConnErr = err
-	tc.netconn.unlock()
+func (tc *testClientConn) closeWrite() {
+	tc.netconn.Close()
 	tc.sync()
 }
 
@@ -746,80 +738,6 @@ func diffHeaders(got, want http.Header) string {
 	return fmt.Sprintf("got:  %v\nwant: %v", got, want)
 }
 
-// testClientConnNetConn implements net.Conn,
-// and is the Conn used by a ClientConn under test.
-type testClientConnNetConn struct {
-	gate           gate
-	toConn         bytes.Buffer
-	toConnErr      error
-	fromConn       bytes.Buffer
-	fromConnClosed bool
-}
-
-func (c *testClientConnNetConn) lock() {
-	c.gate.lock()
-}
-
-func (c *testClientConnNetConn) unlock() {
-	c.gate.unlock(c.toConn.Len() > 0 || c.toConnErr != nil)
-}
-
-func (c *testClientConnNetConn) Read(b []byte) (n int, err error) {
-	if err := c.gate.waitAndLock(context.Background()); err != nil {
-		return 0, err
-	}
-	defer c.unlock()
-	if c.toConn.Len() == 0 && c.toConnErr != nil {
-		return 0, c.toConnErr
-	}
-	return c.toConn.Read(b)
-}
-
-func (c *testClientConnNetConn) Write(b []byte) (n int, err error) {
-	c.lock()
-	defer c.unlock()
-	return c.fromConn.Write(b)
-}
-
-func (c *testClientConnNetConn) Close() error {
-	c.lock()
-	defer c.unlock()
-	c.fromConnClosed = true
-	c.toConn.Reset()
-	if c.toConnErr == nil {
-		c.toConnErr = errors.New("connection closed")
-	}
-	return nil
-}
-
-func (*testClientConnNetConn) LocalAddr() (_ net.Addr)            { return }
-func (*testClientConnNetConn) RemoteAddr() (_ net.Addr)           { return }
-func (*testClientConnNetConn) SetDeadline(t time.Time) error      { return nil }
-func (*testClientConnNetConn) SetReadDeadline(t time.Time) error  { return nil }
-func (*testClientConnNetConn) SetWriteDeadline(t time.Time) error { return nil }
-
-// testClientConnNetConnWriteToClient is a view on a testClientConnNetConn
-// that implements an io.Writer that sends to the client conn under test.
-type testClientConnNetConnWriteToClient testClientConnNetConn
-
-func (w *testClientConnNetConnWriteToClient) Write(b []byte) (n int, err error) {
-	c := (*testClientConnNetConn)(w)
-	c.gate.lock()
-	defer c.unlock()
-	return c.toConn.Write(b)
-}
-
-// testClientConnNetConnReadFromClient is a view on a testClientConnNetConn
-// that implements an io.Reader that reads data sent by the client conn under test.
-type testClientConnNetConnReadFromClient testClientConnNetConn
-
-func (w *testClientConnNetConnReadFromClient) Read(b []byte) (n int, err error) {
-	c := (*testClientConnNetConn)(w)
-	c.gate.lock()
-	defer c.unlock()
-	return c.fromConn.Read(b)
-}
-
 // A testTransport allows testing Transport.RoundTrip against fake servers.
 // Tests that aren't specifically exercising RoundTrip's retry loop or connection pooling
 // should use testClientConn instead.
@@ -861,7 +779,7 @@ func newTestTransport(t *testing.T, opts ...func(*Transport)) *testTransport {
 			buf := make([]byte, 16*1024)
 			n := runtime.Stack(buf, true)
 			t.Logf("stacks:\n%s", buf[:n])
-			t.Fatalf("%v goroutines still running after test completed, expect 1", count-1)
+			t.Fatalf("%v goroutines still running after test completed, expect 1", count)
 		}
 	})