Golang Server.LockShardForAction方法代碼示例

// LockShard will lock the shard in the topology server.
// UnlockShard should be called if this returns no error.
func (n *ActionNode) LockShard(ctx context.Context, ts topo.Server, keyspace, shard string) (lockPath string, err error) {
	log.Infof("Locking shard %v/%v for action %v", keyspace, shard, n.Action)

	span := trace.NewSpanFromContext(ctx)
	span.StartClient("TopoServer.LockShardForAction")
	span.Annotate("action", n.Action)
	span.Annotate("keyspace", keyspace)
	span.Annotate("shard", shard)
	defer span.Finish()

	return ts.LockShardForAction(ctx, keyspace, shard, n.ToJSON())
}

// LockShard will lock the shard in the topology server.
// UnlockShard should be called if this returns no error.
func (n *ActionNode) LockShard(ctx context.Context, ts topo.Server, keyspace, shard string) (lockPath string, err error) {
	log.Infof("Locking shard %v/%v for action %v", keyspace, shard, n.Action)

	ctx, cancel := context.WithTimeout(ctx, *LockTimeout)
	defer cancel()

	span := trace.NewSpanFromContext(ctx)
	span.StartClient("TopoServer.LockShardForAction")
	span.Annotate("action", n.Action)
	span.Annotate("keyspace", keyspace)
	span.Annotate("shard", shard)
	defer span.Finish()

	j, err := n.ToJSON()
	if err != nil {
		return "", err
	}
	return ts.LockShardForAction(ctx, keyspace, shard, j)
}

// checkShardLockUnblocks makes sure that a routine waiting on a lock
// is unblocked when another routine frees the lock
func checkShardLockUnblocks(ctx context.Context, t *testing.T, ts topo.Server) {
	unblock := make(chan struct{})
	finished := make(chan struct{})

	// as soon as we're unblocked, we try to lock the shard
	go func() {
		<-unblock
		lockPath, err := ts.LockShardForAction(ctx, "test_keyspace", "10-20", "fake-content")
		if err != nil {
			t.Fatalf("LockShardForAction(test_keyspace, 10-20) failed: %v", err)
		}
		if err = ts.UnlockShardForAction(ctx, "test_keyspace", "10-20", lockPath, "fake-results"); err != nil {
			t.Fatalf("UnlockShardForAction(test_keyspace, 10-20): %v", err)
		}
		close(finished)
	}()

	// lock the shard
	lockPath2, err := ts.LockShardForAction(ctx, "test_keyspace", "10-20", "fake-content")
	if err != nil {
		t.Fatalf("LockShardForAction(test_keyspace, 10-20) failed: %v", err)
	}

	// unblock the go routine so it starts waiting
	close(unblock)

	// sleep for a while so we're sure the go routine is blocking
	time.Sleep(timeUntilLockIsTaken)

	if err = ts.UnlockShardForAction(ctx, "test_keyspace", "10-20", lockPath2, "fake-results"); err != nil {
		t.Fatalf("UnlockShardForAction(test_keyspace, 10-20): %v", err)
	}

	timeout := time.After(10 * time.Second)
	select {
	case <-finished:
	case <-timeout:
		t.Fatalf("unlocking timed out")
	}
}

func checkShardLockTimeout(ctx context.Context, t *testing.T, ts topo.Server) {
	lockPath, err := ts.LockShardForAction(ctx, "test_keyspace", "10-20", "fake-content")
	if err != nil {
		t.Fatalf("LockShardForAction: %v", err)
	}

	// test we can't take the lock again
	fastCtx, cancel := context.WithTimeout(ctx, timeUntilLockIsTaken)
	if _, err := ts.LockShardForAction(fastCtx, "test_keyspace", "10-20", "unused-fake-content"); err != topo.ErrTimeout {
		t.Fatalf("LockShardForAction(again): %v", err)
	}
	cancel()

	// test we can interrupt taking the lock
	interruptCtx, cancel := context.WithCancel(ctx)
	go func() {
		time.Sleep(timeUntilLockIsTaken)
		cancel()
	}()
	if _, err := ts.LockShardForAction(interruptCtx, "test_keyspace", "10-20", "unused-fake-content"); err != topo.ErrInterrupted {
		t.Fatalf("LockShardForAction(interrupted): %v", err)
	}

	if err := ts.UnlockShardForAction(ctx, "test_keyspace", "10-20", lockPath, "fake-results"); err != nil {
		t.Fatalf("UnlockShardForAction(): %v", err)
	}

	// test we can't unlock again
	if err := ts.UnlockShardForAction(ctx, "test_keyspace", "10-20", lockPath, "fake-results"); err == nil {
		t.Error("UnlockShardForAction(again) worked")
	}
}

func CheckShardLock(t *testing.T, ts topo.Server) {
	if err := ts.CreateKeyspace("test_keyspace", &topo.Keyspace{}); err != nil {
		t.Fatalf("CreateKeyspace: %v", err)
	}
	if err := topo.CreateShard(ts, "test_keyspace", "10-20"); err != nil {
		t.Fatalf("CreateShard: %v", err)
	}

	interrupted := make(chan struct{}, 1)
	lockPath, err := ts.LockShardForAction("test_keyspace", "10-20", "fake-content", 5*time.Second, interrupted)
	if err != nil {
		t.Fatalf("LockShardForAction: %v", err)
	}

	// test we can't take the lock again
	if _, err := ts.LockShardForAction("test_keyspace", "10-20", "unused-fake-content", time.Second/2, interrupted); err != topo.ErrTimeout {
		t.Errorf("LockShardForAction(again): %v", err)
	}

	// test we can interrupt taking the lock
	go func() {
		time.Sleep(time.Second / 2)
		close(interrupted)
	}()
	if _, err := ts.LockShardForAction("test_keyspace", "10-20", "unused-fake-content", 5*time.Second, interrupted); err != topo.ErrInterrupted {
		t.Errorf("LockShardForAction(interrupted): %v", err)
	}

	if err := ts.UnlockShardForAction("test_keyspace", "10-20", lockPath, "fake-results"); err != nil {
		t.Errorf("UnlockShardForAction(): %v", err)
	}

	// test we can't unlock again
	if err := ts.UnlockShardForAction("test_keyspace", "10-20", lockPath, "fake-results"); err == nil {
		t.Error("UnlockShardForAction(again) worked")
	}

	// test we can't lock a non-existing shard
	interrupted = make(chan struct{}, 1)
	if _, err := ts.LockShardForAction("test_keyspace", "20-30", "fake-content", 5*time.Second, interrupted); err == nil {
		t.Fatalf("LockShardForAction(test_keyspace/20-30) worked for non-existing shard")
	}
}

func checkShardLockMissing(ctx context.Context, t *testing.T, ts topo.Server) {
	// test we can't lock a non-existing shard
	if _, err := ts.LockShardForAction(ctx, "test_keyspace", "20-30", "fake-content"); err == nil {
		t.Fatalf("LockShardForAction(test_keyspace/20-30) worked for non-existing shard")
	}
}

// LockShard will lock the shard in the topology server.
// UnlockShard should be called if this returns no error.
func (n *ActionNode) LockShard(ts topo.Server, keyspace, shard string, lockTimeout time.Duration, interrupted chan struct{}) (lockPath string, err error) {
	log.Infof("Locking shard %v/%v for action %v", keyspace, shard, n.Action)
	return ts.LockShardForAction(keyspace, shard, n.ToJson(), lockTimeout, interrupted)
}