ringhash: more e2e tests from c-core (#7334)

internal/testutils/blocking_context_dialer.go

@@ -21,36 +21,109 @@ package testutils
 import (
 	"context"
 	"net"
+	"sync"
+
+	"google.golang.org/grpc/grpclog"
 )
 
+var logger = grpclog.Component("testutils")
+
 // BlockingDialer is a dialer that waits for Resume() to be called before
 // dialing.
 type BlockingDialer struct {
-	dialer  *net.Dialer
+	// mu protects holds.
-	blockCh chan struct{}
+	mu sync.Mutex
+	// holds maps network addresses to a list of holds for that address.
+	holds map[string][]*Hold
 }
 
 // NewBlockingDialer returns a dialer that waits for Resume() to be called
 // before dialing.
 func NewBlockingDialer() *BlockingDialer {
 	return &BlockingDialer{
-		dialer:  &net.Dialer{},
+		holds: make(map[string][]*Hold),
-		blockCh: make(chan struct{}),
 	}
 }
 
 // DialContext implements a context dialer for use with grpc.WithContextDialer
 // dial option for a BlockingDialer.
 func (d *BlockingDialer) DialContext(ctx context.Context, addr string) (net.Conn, error) {
+	d.mu.Lock()
+	holds := d.holds[addr]
+	if len(holds) == 0 {
+		// No hold for this addr.
+		d.mu.Unlock()
+		return (&net.Dialer{}).DialContext(ctx, "tcp", addr)
+	}
+	hold := holds[0]
+	d.holds[addr] = holds[1:]
+	d.mu.Unlock()
+
+	logger.Infof("Hold %p: Intercepted connection attempt to addr %q", hold, addr)
+	close(hold.waitCh)
 	select {
-	case <-d.blockCh:
+	case err := <-hold.blockCh:
+		if err != nil {
+			return nil, err
+		}
+		return (&net.Dialer{}).DialContext(ctx, "tcp", addr)
 	case <-ctx.Done():
+		logger.Infof("Hold %p: Connection attempt to addr %q timed out", hold, addr)
 		return nil, ctx.Err()
 	}
-	return d.dialer.DialContext(ctx, "tcp", addr)
 }
 
-// Resume unblocks the dialer. It panics if called more than once.
+// Hold is a handle to a single connection attempt. It can be used to block,
-func (d *BlockingDialer) Resume() {
+// fail and succeed connection attempts.
-	close(d.blockCh)
+type Hold struct {
+	// dialer is the dialer that created this hold.
+	dialer *BlockingDialer
+	// waitCh is closed when a connection attempt is received.
+	waitCh chan struct{}
+	// blockCh receives the value to return from DialContext for this connection
+	// attempt (nil on resume, an error on fail). It receives at most 1 value.
+	blockCh chan error
+	// addr is the address that this hold is for.
+	addr string
+}
+
+// Hold blocks the dialer when a connection attempt is made to the given addr.
+// A hold is valid for exactly one connection attempt. Multiple holds for an
+// addr can be added, and they will apply in the order that the connections are
+// attempted.
+func (d *BlockingDialer) Hold(addr string) *Hold {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	h := Hold{dialer: d, blockCh: make(chan error, 1), waitCh: make(chan struct{}), addr: addr}
+	d.holds[addr] = append(d.holds[addr], &h)
+	return &h
+}
+
+// Wait blocks until there is a connection attempt on this Hold, or the context
+// expires. Return false if the context has expired, true otherwise.
+func (h *Hold) Wait(ctx context.Context) bool {
+	logger.Infof("Hold %p: Waiting for a connection attempt to addr %q", h, h.addr)
+	select {
+	case <-ctx.Done():
+		return false
+	case <-h.waitCh:
+		return true
+	}
+}
+
+// Resume unblocks the dialer for the given addr. Either Resume or Fail must be
+// called at most once on a hold. Otherwise, Resume panics.
+func (h *Hold) Resume() {
+	logger.Infof("Hold %p: Resuming connection attempt to addr %q", h, h.addr)
+	h.blockCh <- nil
+	close(h.blockCh)
+}
+
+// Fail fails the connection attempt. Either Resume or Fail must be
+// called at most once on a hold. Otherwise, Resume panics.
+func (h *Hold) Fail(err error) {
+	logger.Infof("Hold %p: Failing connection attempt to addr %q", h, h.addr)
+	h.blockCh <- err
+	close(h.blockCh)
 }

internal/testutils/blocking_context_dialer_test.go

@@ -0,0 +1,201 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package testutils
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+)
+
+const (
+	testTimeout      = 5 * time.Second
+	testShortTimeout = 10 * time.Millisecond
+)
+
+func (s) TestBlockingDialer_NoHold(t *testing.T) {
+	lis, err := LocalTCPListener()
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	defer lis.Close()
+
+	d := NewBlockingDialer()
+
+	// This should not block.
+	ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+	conn, err := d.DialContext(ctx, lis.Addr().String())
+	if err != nil {
+		t.Fatalf("Failed to dial: %v", err)
+	}
+	conn.Close()
+}
+
+func (s) TestBlockingDialer_HoldWaitResume(t *testing.T) {
+	lis, err := LocalTCPListener()
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	defer lis.Close()
+
+	d := NewBlockingDialer()
+	h := d.Hold(lis.Addr().String())
+
+	done := make(chan struct{})
+	ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+	go func() {
+		defer close(done)
+		conn, err := d.DialContext(ctx, lis.Addr().String())
+		if err != nil {
+			t.Errorf("BlockingDialer.DialContext() got error: %v, want success", err)
+			return
+		}
+		conn.Close()
+	}()
+
+	// This should block until the goroutine above is scheduled.
+	if !h.Wait(ctx) {
+		t.Fatalf("Timeout while waiting for a connection attempt to %q", h.addr)
+	}
+	select {
+	case <-done:
+		t.Fatalf("Expected dialer to be blocked.")
+	case <-time.After(testShortTimeout):
+	}
+
+	h.Resume() // Unblock the above goroutine.
+
+	select {
+	case <-done:
+	case <-ctx.Done():
+		t.Errorf("Timeout waiting for connection attempt to resume.")
+	}
+}
+
+func (s) TestBlockingDialer_HoldWaitFail(t *testing.T) {
+	lis, err := LocalTCPListener()
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	defer lis.Close()
+
+	d := NewBlockingDialer()
+	h := d.Hold(lis.Addr().String())
+
+	wantErr := errors.New("test error")
+
+	dialError := make(chan error)
+	ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+	go func() {
+		_, err := d.DialContext(ctx, lis.Addr().String())
+		dialError <- err
+	}()
+
+	if !h.Wait(ctx) {
+		t.Fatalf("Timeout while waiting for a connection attempt to " + h.addr)
+	}
+	select {
+	case err = <-dialError:
+		t.Errorf("DialContext got unblocked with err %v. Want DialContext to still be blocked after Wait()", err)
+	case <-time.After(testShortTimeout):
+	}
+
+	h.Fail(wantErr)
+
+	select {
+	case err = <-dialError:
+		if !errors.Is(err, wantErr) {
+			t.Errorf("BlockingDialer.DialContext() after Fail(): got error %v, want %v", err, wantErr)
+		}
+	case <-ctx.Done():
+		t.Errorf("Timeout waiting for connection attempt to fail.")
+	}
+}
+
+func (s) TestBlockingDialer_ContextCanceled(t *testing.T) {
+	lis, err := LocalTCPListener()
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	defer lis.Close()
+
+	d := NewBlockingDialer()
+	h := d.Hold(lis.Addr().String())
+
+	dialErr := make(chan error)
+	testCtx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+
+	ctx, cancel := context.WithCancel(testCtx)
+	defer cancel()
+	go func() {
+		_, err := d.DialContext(ctx, lis.Addr().String())
+		dialErr <- err
+	}()
+	if !h.Wait(testCtx) {
+		t.Errorf("Timeout while waiting for a connection attempt to %q", h.addr)
+	}
+
+	cancel()
+
+	select {
+	case err = <-dialErr:
+		if !errors.Is(err, context.Canceled) {
+			t.Errorf("BlockingDialer.DialContext() after context cancel: got error %v, want %v", err, context.Canceled)
+		}
+	case <-testCtx.Done():
+		t.Errorf("Timeout while waiting for Wait to return.")
+	}
+
+	h.Resume() // noop, just make sure nothing bad happen.
+}
+
+func (s) TestBlockingDialer_CancelWait(t *testing.T) {
+	lis, err := LocalTCPListener()
+	if err != nil {
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	defer lis.Close()
+
+	d := NewBlockingDialer()
+	h := d.Hold(lis.Addr().String())
+
+	testCtx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+
+	ctx, cancel := context.WithCancel(testCtx)
+	cancel()
+	done := make(chan struct{})
+	go func() {
+		if h.Wait(ctx) {
+			t.Errorf("Expected cancel to return false when context expires")
+		}
+		done <- struct{}{}
+	}()
+
+	select {
+	case <-done:
+	case <-testCtx.Done():
+		t.Errorf("Timeout while waiting for Wait to return.")
+	}
+}