Golang state.Watch函數代碼示例

// WaitForCluster waits until node observes that the cluster wide config is
// committed to raft. This ensures that we can see and serve informations
// related to the cluster.
func WaitForCluster(ctx context.Context, n *Node) (cluster *api.Cluster, err error) {
	watch, cancel := state.Watch(n.MemoryStore().WatchQueue(), state.EventCreateCluster{})
	defer cancel()

	var clusters []*api.Cluster
	n.MemoryStore().View(func(readTx store.ReadTx) {
		clusters, err = store.FindClusters(readTx, store.ByName(store.DefaultClusterName))
	})

	if err != nil {
		return nil, err
	}

	if len(clusters) == 1 {
		cluster = clusters[0]
	} else {
		select {
		case e := <-watch:
			cluster = e.(state.EventCreateCluster).Cluster
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}

	return cluster, nil
}

// Run is the ConstraintEnforcer's main loop.
func (ce *ConstraintEnforcer) Run() {
	defer close(ce.doneChan)

	watcher, cancelWatch := state.Watch(ce.store.WatchQueue(), state.EventUpdateNode{})
	defer cancelWatch()

	var (
		nodes []*api.Node
		err   error
	)
	ce.store.View(func(readTx store.ReadTx) {
		nodes, err = store.FindNodes(readTx, store.All)
	})
	if err != nil {
		log.L.WithError(err).Error("failed to check nodes for noncompliant tasks")
	} else {
		for _, node := range nodes {
			ce.shutdownNoncompliantTasks(node)
		}
	}

	for {
		select {
		case event := <-watcher:
			node := event.(state.EventUpdateNode).Node
			ce.shutdownNoncompliantTasks(node)
		case <-ce.stopChan:
			return
		}
	}
}

func TestSchedulerNoReadyNodes(t *testing.T) {
	ctx := context.Background()
	initialTask := &api.Task{
		ID:           "id1",
		DesiredState: api.TaskStateRunning,
		ServiceAnnotations: api.Annotations{
			Name: "name1",
		},
		Status: api.TaskStatus{
			State: api.TaskStatePending,
		},
	}

	s := store.NewMemoryStore(nil)
	assert.NotNil(t, s)
	defer s.Close()

	err := s.Update(func(tx store.Tx) error {
		// Add initial task
		assert.NoError(t, store.CreateTask(tx, initialTask))
		return nil
	})
	assert.NoError(t, err)

	scheduler := New(s)

	watch, cancel := state.Watch(s.WatchQueue(), state.EventUpdateTask{})
	defer cancel()

	go func() {
		assert.NoError(t, scheduler.Run(ctx))
	}()
	defer scheduler.Stop()

	failure := watchAssignmentFailure(t, watch)
	assert.Equal(t, "no suitable node", failure.Status.Message)

	err = s.Update(func(tx store.Tx) error {
		// Create a ready node. The task should get assigned to this
		// node.
		node := &api.Node{
			ID: "newnode",
			Spec: api.NodeSpec{
				Annotations: api.Annotations{
					Name: "newnode",
				},
			},
			Status: api.NodeStatus{
				State: api.NodeStatus_READY,
			},
		}
		assert.NoError(t, store.CreateNode(tx, node))
		return nil
	})
	assert.NoError(t, err)

	assignment := watchAssignment(t, watch)
	assert.Equal(t, "newnode", assignment.NodeID)
}

func (u *Updater) updateTask(ctx context.Context, slot slot, updated *api.Task) error {
	// Kick off the watch before even creating the updated task. This is in order to avoid missing any event.
	taskUpdates, cancel := state.Watch(u.watchQueue, state.EventUpdateTask{
		Task:   &api.Task{ID: updated.ID},
		Checks: []state.TaskCheckFunc{state.TaskCheckID},
	})
	defer cancel()

	var delayStartCh <-chan struct{}
	// Atomically create the updated task and bring down the old one.
	_, err := u.store.Batch(func(batch *store.Batch) error {
		err := batch.Update(func(tx store.Tx) error {
			if err := store.CreateTask(tx, updated); err != nil {
				return err
			}
			return nil
		})
		if err != nil {
			return err
		}

		u.removeOldTasks(ctx, batch, slot)

		for _, t := range slot {
			if t.DesiredState == api.TaskStateRunning {
				// Wait for the old task to stop or time out, and then set the new one
				// to RUNNING.
				delayStartCh = u.restarts.DelayStart(ctx, nil, t, updated.ID, 0, true)
				break
			}
		}

		return nil

	})
	if err != nil {
		return err
	}

	if delayStartCh != nil {
		<-delayStartCh
	}

	// Wait for the new task to come up.
	// TODO(aluzzardi): Consider adding a timeout here.
	for {
		select {
		case e := <-taskUpdates:
			updated = e.(state.EventUpdateTask).Task
			if updated.Status.State >= api.TaskStateRunning {
				return nil
			}
		case <-u.stopChan:
			return nil
		}
	}
}

func (u *Updater) updateTask(ctx context.Context, original, updated *api.Task) error {
	log.G(ctx).Debugf("replacing %s with %s", original.ID, updated.ID)
	// Kick off the watch before even creating the updated task. This is in order to avoid missing any event.
	taskUpdates, cancel := state.Watch(u.watchQueue, state.EventUpdateTask{
		Task:   &api.Task{ID: updated.ID},
		Checks: []state.TaskCheckFunc{state.TaskCheckID},
	})
	defer cancel()

	var delayStartCh <-chan struct{}
	// Atomically create the updated task and bring down the old one.
	err := u.store.Update(func(tx store.Tx) error {
		t := store.GetTask(tx, original.ID)
		if t == nil {
			return fmt.Errorf("task %s not found while trying to update it", original.ID)
		}
		if t.DesiredState > api.TaskStateRunning {
			return fmt.Errorf("task %s was already shut down when reached by updater", original.ID)
		}
		t.DesiredState = api.TaskStateShutdown
		if err := store.UpdateTask(tx, t); err != nil {
			return err
		}

		if err := store.CreateTask(tx, updated); err != nil {
			return err
		}

		// Wait for the old task to stop or time out, and then set the new one
		// to RUNNING.
		delayStartCh = u.restarts.DelayStart(ctx, tx, original, updated.ID, 0, true)

		return nil

	})
	if err != nil {
		return err
	}

	<-delayStartCh

	// Wait for the new task to come up.
	// TODO(aluzzardi): Consider adding a timeout here.
	for {
		select {
		case e := <-taskUpdates:
			updated = e.(state.EventUpdateTask).Task
			if updated.Status.State >= api.TaskStateRunning {
				return nil
			}
		case <-u.stopChan:
			return nil
		}
	}
}

// NewTaskReaper creates a new TaskReaper.
func NewTaskReaper(store *store.MemoryStore) *TaskReaper {
	watcher, cancel := state.Watch(store.WatchQueue(), state.EventCreateTask{}, state.EventUpdateCluster{})

	return &TaskReaper{
		store:       store,
		watcher:     watcher,
		cancelWatch: cancel,
		dirty:       make(map[instanceTuple]struct{}),
		stopChan:    make(chan struct{}),
		doneChan:    make(chan struct{}),
	}
}

func (s *subscription) Run(ctx context.Context) {
	s.ctx, s.cancel = context.WithCancel(ctx)

	if s.follow() {
		wq := s.store.WatchQueue()
		ch, cancel := state.Watch(wq, state.EventCreateTask{}, state.EventUpdateTask{})
		go func() {
			defer cancel()
			s.watch(ch)
		}()
	}

	s.match()
}

func TestSetup(t *testing.T) {
	store := store.NewMemoryStore(nil)
	assert.NotNil(t, store)
	defer store.Close()

	watch, cancel := state.Watch(store.WatchQueue() /*state.EventCreateTask{}, state.EventUpdateTask{}*/)
	defer cancel()

	observedTask1 := SetupCluster(t, store, watch)

	assert.Equal(t, observedTask1.Status.State, api.TaskStateNew)
	assert.Equal(t, observedTask1.ServiceAnnotations.Name, "name1")
	assert.Equal(t, observedTask1.NodeID, "id1")
}

func TestAddNode(t *testing.T) {
	store := store.NewMemoryStore(nil)
	assert.NotNil(t, store)
	defer store.Close()

	watch, cancel := state.Watch(store.WatchQueue())
	defer cancel()

	SetupCluster(t, store, watch)

	addNode(t, store, node2)
	observedTask2 := testutils.WatchTaskCreate(t, watch)
	assert.Equal(t, observedTask2.Status.State, api.TaskStateNew)
	assert.Equal(t, observedTask2.ServiceAnnotations.Name, "name1")
	assert.Equal(t, observedTask2.NodeID, "id2")
}

func TestDeleteService(t *testing.T) {
	store := store.NewMemoryStore(nil)
	assert.NotNil(t, store)
	defer store.Close()

	watch, cancel := state.Watch(store.WatchQueue())
	defer cancel()

	SetupCluster(t, store, watch)

	deleteService(t, store, service1)
	// task should be deleted
	observedTask := testutils.WatchTaskDelete(t, watch)
	assert.Equal(t, observedTask.ServiceAnnotations.Name, "name1")
	assert.Equal(t, observedTask.NodeID, "id1")
}

func TestDeleteNode(t *testing.T) {
	store := store.NewMemoryStore(nil)
	assert.NotNil(t, store)

	SetupCluster(t, store)

	watch, cancel := state.Watch(store.WatchQueue())
	defer cancel()

	skipEvents(t, watch)

	deleteNode(t, store, node1)
	// task should be set to dead
	observedTask := watchShutdownTask(t, watch)
	assert.Equal(t, observedTask.ServiceAnnotations.Name, "name1")
	assert.Equal(t, observedTask.NodeID, "id1")
}

func TestAddService(t *testing.T) {
	store := store.NewMemoryStore(nil)
	assert.NotNil(t, store)

	SetupCluster(t, store)

	watch, cancel := state.Watch(store.WatchQueue())
	defer cancel()

	skipEvents(t, watch)

	addService(t, store, service2)
	observedTask := watchTaskCreate(t, watch)
	assert.Equal(t, observedTask.Status.State, api.TaskStateNew)
	assert.Equal(t, observedTask.ServiceAnnotations.Name, "name2")
	assert.True(t, observedTask.NodeID == "id1")
}

// ViewAndWatch calls a callback which can observe the state of this
// MemoryStore. It also returns a channel that will return further events from
// this point so the snapshot can be kept up to date. The watch channel must be
// released with watch.StopWatch when it is no longer needed. The channel is
// guaranteed to get all events after the moment of the snapshot, and only
// those events.
func ViewAndWatch(store *MemoryStore, cb func(ReadTx) error, specifiers ...state.Event) (watch chan events.Event, cancel func(), err error) {
	// Using Update to lock the store and guarantee consistency between
	// the watcher and the the state seen by the callback. snapshotReadTx
	// exposes this Tx as a ReadTx so the callback can't modify it.
	err = store.Update(func(tx Tx) error {
		if err := cb(tx); err != nil {
			return err
		}
		watch, cancel = state.Watch(store.WatchQueue(), specifiers...)
		return nil
	})
	if watch != nil && err != nil {
		cancel()
		cancel = nil
		watch = nil
	}
	return
}

func TestSchedulerFaultyNode(t *testing.T) {
	ctx := context.Background()

	taskTemplate := &api.Task{
		ServiceID:    "service1",
		DesiredState: api.TaskStateRunning,
		ServiceAnnotations: api.Annotations{
			Name: "name1",
		},
		Status: api.TaskStatus{
			State: api.TaskStatePending,
		},
	}

	node1 := &api.Node{
		ID: "id1",
		Spec: api.NodeSpec{
			Annotations: api.Annotations{
				Name: "id1",
			},
		},
		Status: api.NodeStatus{
			State: api.NodeStatus_READY,
		},
	}

	node2 := &api.Node{
		ID: "id2",
		Spec: api.NodeSpec{
			Annotations: api.Annotations{
				Name: "id2",
			},
		},
		Status: api.NodeStatus{
			State: api.NodeStatus_READY,
		},
	}

	s := store.NewMemoryStore(nil)
	assert.NotNil(t, s)
	defer s.Close()

	err := s.Update(func(tx store.Tx) error {
		// Add initial nodes, and one task assigned to node id1
		assert.NoError(t, store.CreateNode(tx, node1))
		assert.NoError(t, store.CreateNode(tx, node2))

		task1 := taskTemplate.Copy()
		task1.ID = "id1"
		task1.NodeID = "id1"
		task1.Status.State = api.TaskStateRunning
		assert.NoError(t, store.CreateTask(tx, task1))
		return nil
	})
	assert.NoError(t, err)

	scheduler := New(s)

	watch, cancel := state.Watch(s.WatchQueue(), state.EventUpdateTask{})
	defer cancel()

	go func() {
		assert.NoError(t, scheduler.Run(ctx))
	}()
	defer scheduler.Stop()

	for i := 0; i != 8; i++ {
		// Simulate a task failure cycle
		newTask := taskTemplate.Copy()
		newTask.ID = identity.NewID()

		err = s.Update(func(tx store.Tx) error {
			assert.NoError(t, store.CreateTask(tx, newTask))
			return nil
		})
		assert.NoError(t, err)

		assignment := watchAssignment(t, watch)
		assert.Equal(t, newTask.ID, assignment.ID)

		if i < 5 {
			// The first 5 attempts should be assigned to node id2 because
			// it has no replicas of the service.
			assert.Equal(t, "id2", assignment.NodeID)
		} else {
			// The next ones should be assigned to id1, since we'll
			// flag id2 as potentially faulty.
			assert.Equal(t, "id1", assignment.NodeID)
		}

		err = s.Update(func(tx store.Tx) error {
			newTask := store.GetTask(tx, newTask.ID)
			require.NotNil(t, newTask)
			newTask.Status.State = api.TaskStateFailed
			assert.NoError(t, store.UpdateTask(tx, newTask))
			return nil
		})
		assert.NoError(t, err)
	}
}

func benchScheduler(b *testing.B, nodes, tasks int, networkConstraints bool) {
	ctx := context.Background()

	for iters := 0; iters < b.N; iters++ {
		b.StopTimer()
		s := store.NewMemoryStore(nil)
		scheduler := New(s)

		watch, cancel := state.Watch(s.WatchQueue(), state.EventUpdateTask{})

		go func() {
			_ = scheduler.Run(ctx)
		}()

		// Let the scheduler get started
		runtime.Gosched()

		_ = s.Update(func(tx store.Tx) error {
			// Create initial nodes and tasks
			for i := 0; i < nodes; i++ {
				n := &api.Node{
					ID: identity.NewID(),
					Spec: api.NodeSpec{
						Annotations: api.Annotations{
							Name:   "name" + strconv.Itoa(i),
							Labels: make(map[string]string),
						},
					},
					Status: api.NodeStatus{
						State: api.NodeStatus_READY,
					},
					Description: &api.NodeDescription{
						Engine: &api.EngineDescription{},
					},
				}
				// Give every third node a special network
				if i%3 == 0 {
					n.Description.Engine.Plugins = []api.PluginDescription{
						{
							Name: "network",
							Type: "Network",
						},
					}

				}
				err := store.CreateNode(tx, n)
				if err != nil {
					panic(err)
				}
			}
			for i := 0; i < tasks; i++ {
				id := "task" + strconv.Itoa(i)
				t := &api.Task{
					ID:           id,
					DesiredState: api.TaskStateRunning,
					ServiceAnnotations: api.Annotations{
						Name: id,
					},
					Status: api.TaskStatus{
						State: api.TaskStatePending,
					},
				}
				if networkConstraints {
					t.Networks = []*api.NetworkAttachment{
						{
							Network: &api.Network{
								DriverState: &api.Driver{
									Name: "network",
								},
							},
						},
					}
				}
				err := store.CreateTask(tx, t)
				if err != nil {
					panic(err)
				}
			}
			b.StartTimer()
			return nil
		})

		for i := 0; i != tasks; i++ {
			<-watch
		}

		scheduler.Stop()
		cancel()
		s.Close()
	}
}