Merge branch 'master' into shutdown-error-option

app_test.go

@@ -1281,6 +1281,26 @@ func TestAppStart(t *testing.T) {
 		err := app.Start(context.Background()).Error()
 		assert.Contains(t, err, "OnStart hook added by go.uber.org/fx_test.TestAppStart.func10.1 failed: goroutine exited without returning")
 	})
+
+	t.Run("StartTwiceWithHooksErrors", func(t *testing.T) {
+		t.Parallel()
+
+		app := fxtest.New(t,
+			Invoke(func(lc Lifecycle) {
+				lc.Append(Hook{
+					OnStart: func(ctx context.Context) error { return nil },
+					OnStop:  func(ctx context.Context) error { return nil },
+				})
+			}),
+		)
+		assert.NoError(t, app.Start(context.Background()))
+		err := app.Start(context.Background())
+		if assert.Error(t, err) {
+			assert.ErrorContains(t, err, "attempted to start lifecycle when in state: started")
+		}
+		app.Stop(context.Background())
+		assert.NoError(t, app.Start(context.Background()))
+	})
 }
 
 func TestAppStop(t *testing.T) {

internal/lifecycle/lifecycle.go

@@ -123,10 +123,38 @@ type Hook struct {
 	callerFrame fxreflect.Frame
 }
 
+type appState int
+
+const (
+	stopped appState = iota
+	starting
+	incompleteStart
+	started
+	stopping
+)
+
+func (as appState) String() string {
+	switch as {
+	case stopped:
+		return "stopped"
+	case starting:
+		return "starting"
+	case incompleteStart:
+		return "incompleteStart"
+	case started:
+		return "started"
+	case stopping:
+		return "stopping"
+	default:
+		return "invalidState"
+	}
+}
+
 // Lifecycle coordinates application lifecycle hooks.
 type Lifecycle struct {
 	clock        fxclock.Clock
 	logger       fxevent.Logger
+	state        appState
 	hooks        []Hook
 	numStarted   int
 	startRecords HookRecords
@@ -157,9 +185,23 @@ func (l *Lifecycle) Start(ctx context.Context) error {
 	}
 
 	l.mu.Lock()
+	if l.state != stopped {
+		defer l.mu.Unlock()
+		return fmt.Errorf("attempted to start lifecycle when in state: %v", l.state)
+	}
+	l.numStarted = 0
+	l.state = starting
+
 	l.startRecords = make(HookRecords, 0, len(l.hooks))
 	l.mu.Unlock()
 
+	var returnState appState = incompleteStart
+	defer func() {
+		l.mu.Lock()
+		l.state = returnState
+		l.mu.Unlock()
+	}()
+
 	for _, hook := range l.hooks {
 		// if ctx has cancelled, bail out of the loop.
 		if err := ctx.Err(); err != nil {
@@ -187,6 +229,7 @@ func (l *Lifecycle) Start(ctx context.Context) error {
 		l.numStarted++
 	}
 
+	returnState = started
 	return nil
 }
 
@@ -221,6 +264,20 @@ func (l *Lifecycle) Stop(ctx context.Context) error {
 		return errors.New("called OnStop with nil context")
 	}
 
+	l.mu.Lock()
+	if l.state != started && l.state != incompleteStart {
+		defer l.mu.Unlock()
+		return fmt.Errorf("attempted to stop lifecycle when in state: %v", l.state)
+	}
+	l.state = stopping
+	l.mu.Unlock()
+
+	defer func() {
+		l.mu.Lock()
+		l.state = stopped
+		l.mu.Unlock()
+	}()
+
 	l.mu.Lock()
 	l.stopRecords = make(HookRecords, 0, l.numStarted)
 	l.mu.Unlock()

internal/lifecycle/lifecycle_test.go

@@ -71,6 +71,7 @@ func TestLifecycleStart(t *testing.T) {
 		assert.NoError(t, l.Start(context.Background()))
 		assert.Equal(t, 2, count)
 	})
+
 	t.Run("ErrHaltsChainAndRollsBack", func(t *testing.T) {
 		t.Parallel()
 
@@ -143,6 +144,18 @@ func TestLifecycleStart(t *testing.T) {
 		// stop hooks.
 		require.NoError(t, l.Stop(ctx))
 	})
+
+	t.Run("StartWhileStartedErrors", func(t *testing.T) {
+		t.Parallel()
+
+		l := New(testLogger(t), fxclock.System)
+		assert.NoError(t, l.Start(context.Background()))
+		err := l.Start(context.Background())
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "attempted to start lifecycle when in state: started")
+		assert.NoError(t, l.Stop(context.Background()))
+		assert.NoError(t, l.Start(context.Background()))
+	})
 }
 
 func TestLifecycleStop(t *testing.T) {
@@ -152,6 +165,7 @@ func TestLifecycleStop(t *testing.T) {
 		t.Parallel()
 
 		l := New(testLogger(t), fxclock.System)
+		l.Start(context.Background())
 		assert.Nil(t, l.Stop(context.Background()), "no lifecycle hooks should have resulted in stop returning nil")
 	})
 
@@ -317,6 +331,16 @@ func TestLifecycleStop(t *testing.T) {
 		assert.Contains(t, err.Error(), "called OnStop with nil context")
 
 	})
+
+	t.Run("StopWhileStoppedErrors", func(t *testing.T) {
+		t.Parallel()
+
+		l := New(testLogger(t), fxclock.System)
+		err := l.Stop(context.Background())
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "attempted to stop lifecycle when in state: stopped")
+	})
+
 }
 
 func TestHookRecordsFormat(t *testing.T) {