Golang Server.LockSrvShardForAction方法代码示例

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

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

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

// checkSrvShardLockUnblocks makes sure that a routine waiting on a lock
// is unblocked when another routine frees the lock
func checkSrvShardLockUnblocks(ctx context.Context, t *testing.T, ts topo.Server) {
	cell := getLocalCell(ctx, t, ts)
	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.LockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", "fake-content")
		if err != nil {
			t.Fatalf("LockSrvShardForAction(test, test_keyspace, 10-20) failed: %v", err)
		}
		if err = ts.UnlockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", lockPath, "fake-results"); err != nil {
			t.Fatalf("UnlockSrvShardForAction(test, test_keyspace, 10-20): %v", err)
		}
		close(finished)
	}()

	// lock the shard
	lockPath2, err := ts.LockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", "fake-content")
	if err != nil {
		t.Fatalf("LockSrvShardForAction(test, 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.UnlockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", lockPath2, "fake-results"); err != nil {
		t.Fatalf("UnlockSrvShardForAction(test, test_keyspace, 10-20): %v", err)
	}

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

func checkSrvShardLockGeneral(ctx context.Context, t *testing.T, ts topo.Server) {
	cell := getLocalCell(ctx, t, ts)

	// make sure we can create the lock even if no directory exists
	lockPath, err := ts.LockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", "fake-content")
	if err != nil {
		t.Fatalf("LockSrvShardForAction: %v", err)
	}

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

	// now take the lock again after the root exists
	lockPath, err = ts.LockSrvShardForAction(ctx, cell, "test_keyspace", "10-20", "fake-content")
	if err != nil {
		t.Fatalf("LockSrvShardForAction: %v", err)
	}

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

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

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

}

func CheckSrvShardLock(t *testing.T, ts topo.Server) {
	// make sure we can create the lock even if no directory exists
	interrupted := make(chan struct{}, 1)
	lockPath, err := ts.LockSrvShardForAction("test", "test_keyspace", "10-20", "fake-content", 5*time.Second, interrupted)
	if err != nil {
		t.Fatalf("LockSrvShardForAction: %v", err)
	}

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

	// now take the lock again after the root exists
	lockPath, err = ts.LockSrvShardForAction("test", "test_keyspace", "10-20", "fake-content", 5*time.Second, interrupted)
	if err != nil {
		t.Fatalf("LockSrvShardForAction: %v", err)
	}

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

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

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

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

}

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