add OptOnStartCombined (#68)

actor/combine.go

@@ -26,6 +26,7 @@ func (b *CombineBuilder) Build() Actor {
 	a := &combinedActor{
 		actors:       b.actors,
 		onStopFunc:   b.options.Combined.OnStopFunc,
+		onStartFunc:  b.options.Combined.OnStartFunc,
 		stopTogether: b.options.Combined.StopTogether,
 		stopping:     &atomic.Bool{},
 	}
@@ -44,8 +45,10 @@ func (b *CombineBuilder) WithOptions(opt ...CombinedOption) *CombineBuilder {
 type combinedActor struct {
 	actors       []Actor
 	onStopFunc   func()
+	onStartFunc  func(Context)
 	stopTogether bool
 
+	ctx          *context
 	runningCount atomic.Int32
 	running      bool
 	runningLock  sync.Mutex
@@ -70,6 +73,11 @@ func (a *combinedActor) onActorStopped() {
 	if a.stopTogether && a.stopping.CompareAndSwap(false, true) {
 		// Run stop in goroutine because wrapped actor
 		// should not wait for other actors to stop.
+		//
+		// Also if a.Stop() is called from same gorutine it would
+		// be recoursive call without exit condition. Therfore
+		// it is need to call a.Stop() from other goroutine,
+		// regardless of first invariant.
 		go a.Stop()
 	}
 }
@@ -82,6 +90,12 @@ func (a *combinedActor) Stop() {
 		return
 	}
 
+	if ctx := a.ctx; ctx != nil {
+		ctx.end()
+
+		a.ctx = nil
+	}
+
 	a.running = false
 	a.runningLock.Unlock()
 
@@ -98,11 +112,18 @@ func (a *combinedActor) Start() {
 		return
 	}
 
+	ctx := newContext()
+	a.ctx = ctx
+
 	a.stopping.Store(false)
 	a.running = true
 
 	a.runningLock.Unlock()
 
+	if fn := a.onStartFunc; fn != nil {
+		fn(ctx)
+	}
+
 	for _, actor := range a.actors {
 		a.runningCount.Add(1)
 		actor.Start()

actor/combine_test.go

@@ -75,16 +75,17 @@ func Test_Combine_OptStopTogether(t *testing.T) {
 	}
 }
 
-func Test_Combine_OptOnStop(t *testing.T) {
+func Test_Combine_OptOnStopOptOnStart(t *testing.T) {
 	t.Parallel()
 
 	const actorsCount = 5
 
+	onStatC, onStartOpt := createCombinedOnStartOption(t, 1)
 	onStopC, onStopOpt := createCombinedOnStopOption(t, 1)
 	actors := createActors(actorsCount)
 
 	a := Combine(actors...).
-		WithOptions(onStopOpt).
+		WithOptions(onStopOpt, onStartOpt).
 		Build()
 
 	a.Start()
@@ -94,6 +95,7 @@ func Test_Combine_OptOnStop(t *testing.T) {
 	a.Stop() // should have no effect
 	a.Stop() // should have no effect
 	assert.Equal(t, `🌚`, <-onStopC)
+	assert.Equal(t, `🌞`, <-onStatC)
 }
 
 func Test_Combine_OptOnStop_AfterActorStops(t *testing.T) {
@@ -143,14 +145,29 @@ func createActor(i int, opts ...Option) Actor {
 func createCombinedOnStopOption(t *testing.T, count int) (<-chan any, CombinedOption) {
 	t.Helper()
 
-	onStopC := make(chan any, count)
-	onStopFunc := func() {
+	c := make(chan any, count)
+	fn := func() {
 		select {
-		case onStopC <- `🌚`:
+		case c <- `🌚`:
 		default:
 			t.Fatal("onStopFunc should be called only once")
 		}
 	}
 
-	return onStopC, OptOnStopCombined(onStopFunc)
+	return c, OptOnStopCombined(fn)
+}
+
+func createCombinedOnStartOption(t *testing.T, count int) (<-chan any, CombinedOption) {
+	t.Helper()
+
+	c := make(chan any, count)
+	fn := func(_ Context) {
+		select {
+		case c <- `🌞`:
+		default:
+			t.Fatal("onStart should be called only once")
+		}
+	}
+
+	return c, OptOnStartCombined(fn)
 }

actor/options.go

@@ -70,13 +70,20 @@ func OptStopTogether() CombinedOption {
 	}
 }
 
-// OptOnStopCombined will is called after all combined actors are stopped.
+// OptOnStopCombined is called after all combined actors are stopped.
 func OptOnStopCombined(f func()) CombinedOption {
 	return func(o *options) {
 		o.Combined.OnStopFunc = f
 	}
 }
 
+// OptOnStartCombined is called before all.
+func OptOnStartCombined(f func(Context)) CombinedOption {
+	return func(o *options) {
+		o.Combined.OnStartFunc = f
+	}
+}
+
 type (
 	option func(o *options)
 
@@ -99,6 +106,7 @@ type optionsActor struct {
 type optionsCombined struct {
 	StopTogether bool
 	OnStopFunc   func()
+	OnStartFunc  func(Context)
 }
 
 type optionsMailbox struct {

actor/options_test.go

@@ -116,4 +116,20 @@ func testCombinedOptions(t *testing.T) {
 		assert.Empty(t, opts.Actor)
 		assert.Empty(t, opts.Mailbox)
 	}
+
+	{ // Assert that OnStartCombined will be set
+		opts := NewOptions(OptOnStartCombined(func(Context) {}))
+		assert.NotNil(t, opts.Combined.OnStartFunc)
+
+		assert.Empty(t, opts.Actor)
+		assert.Empty(t, opts.Mailbox)
+	}
+
+	{ // Assert that OnStopCombined will be set
+		opts := NewOptions(OptOnStopCombined(func() {}))
+		assert.NotNil(t, opts.Combined.OnStopFunc)
+
+		assert.Empty(t, opts.Actor)
+		assert.Empty(t, opts.Mailbox)
+	}
 }