reverted changes to throttler for ignoring duplicate events. This caused

more problems since state is immutable but some state of agents and
client is not immutable so it ignored events that were not really
duplicates.
This reverts commit f6b0211336.

cmd/converge/notifier.go

@@ -7,7 +7,7 @@ import (
 )
 
 type StateNotifier struct {
-	throttler                     *throttling.AsyncThrottler[*models.State]
+	throttler                     *throttling.AsyncThrottler[models.State]
 	webNotificationChannel        chan *models.State
 	prometheusNotificationChannel chan *models.State
 }

pkg/support/throttling/async_throttler.go

@@ -5,15 +5,15 @@ import (
 	"time"
 )
 
-type AsyncThrottler[T comparable] struct {
+type AsyncThrottler[T any] struct {
 	throttler Throttler[T]
 	ctx       context.Context
 	cancel    context.CancelFunc
-	events    chan T
+	events    chan *T
 	ticker    *time.Ticker
 }
 
-func NewAsyncThrottler[T comparable](notifier func(t T),
+func NewAsyncThrottler[T any](notifier func(t *T),
 	minDelay time.Duration,
 	pollInterval time.Duration) *AsyncThrottler[T] {
 	ctx, cancel := context.WithCancel(context.Background())
@@ -21,7 +21,7 @@ func NewAsyncThrottler[T comparable](notifier func(t T),
 		throttler: NewThrottler[T](notifier, minDelay),
 		ctx:       ctx,
 		cancel:    cancel,
-		events:    make(chan T),
+		events:    make(chan *T),
 		ticker:    time.NewTicker(pollInterval),
 	}
 	go func() {
@@ -39,7 +39,7 @@ func NewAsyncThrottler[T comparable](notifier func(t T),
 	return &throttler
 }
 
-func (throttler *AsyncThrottler[T]) Notify(value T) {
+func (throttler *AsyncThrottler[T]) Notify(value *T) {
 	throttler.events <- value
 }
 

pkg/support/throttling/async_throttler_test.go

@@ -9,15 +9,15 @@ func (suite *ThrottlerTestSuite) Test_AsyncDeliverOneValue() {
 
 	pollInterval := 10 * time.Millisecond
 
-	throttler := NewAsyncThrottler[int](func(v int) {
-		value = v
+	throttler := NewAsyncThrottler[int](func(v *int) {
+		value = *v
 	}, time.Second, pollInterval)
 	defer throttler.Stop()
 
 	t0 := time.Now()
 	v := 1
 	currentTime.now = t0
-	throttler.Notify(v)
+	throttler.Notify(&v)
 	time.Sleep(2 * pollInterval)
 	suite.Equal(v, value)
 
@@ -33,8 +33,8 @@ func (suite *ThrottlerTestSuite) Test_AsyncTwoNotificationsInSHortSucessionSecon
 
 	pollInterval := 10 * time.Millisecond
 
-	throttler := NewAsyncThrottler[int](func(v int) {
-		value = v
+	throttler := NewAsyncThrottler[int](func(v *int) {
+		value = *v
 	}, time.Second, pollInterval)
 	defer throttler.Stop()
 
@@ -44,12 +44,12 @@ func (suite *ThrottlerTestSuite) Test_AsyncTwoNotificationsInSHortSucessionSecon
 	v2 := 2
 	v3 := 3
 	currentTime.now = t0
-	throttler.Notify(v1)
+	throttler.Notify(&v1)
 	time.Sleep(2 * pollInterval)
 	suite.Equal(v1, value)
 
-	throttler.Notify(v2)
-	throttler.Notify(v3)
+	throttler.Notify(&v2)
+	throttler.Notify(&v3)
 	time.Sleep(2 * pollInterval)
 	suite.Equal(v1, value)
 

pkg/support/throttling/throtller_test.go

@@ -6,14 +6,14 @@ import (
 
 func (suite *ThrottlerTestSuite) Test_throttlerImmediateNotificationAfterInitialized() {
 	value := 0
-	throttler := NewThrottler[int](func(v int) {
-		value = v
+	throttler := NewThrottler[int](func(v *int) {
+		value = *v
 	}, 1.0)
 
 	t0 := time.Now()
 	v := 1
 	currentTime.now = t0
-	throttler.Notify(v)
+	throttler.Notify(&v)
 	suite.Equal(v, value)
 	value = 0
 	// subsequent ping will not lead to a notification
@@ -25,8 +25,8 @@ func (suite *ThrottlerTestSuite) Test_throttlerImmediateNotificationAfterInitial
 func (suite *ThrottlerTestSuite) Test_TwoNotificationsInSHortSucessionSecondOneIsDeliverdWithDelay() {
 	value := 0
 	delayMs := 1000
-	throttler := NewThrottler[int](func(v int) {
-		value = v
+	throttler := NewThrottler[int](func(v *int) {
+		value = *v
 	}, time.Duration(delayMs)*time.Millisecond)
 
 	t0 := time.Now()
@@ -35,10 +35,10 @@ func (suite *ThrottlerTestSuite) Test_TwoNotificationsInSHortSucessionSecondOneI
 	v2 := 2
 	v3 := 3
 	currentTime.now = t0
-	throttler.Notify(v1)
+	throttler.Notify(&v1)
 	suite.Equal(v1, value)
-	throttler.Notify(v2)
-	throttler.Notify(v3)
+	throttler.Notify(&v2)
+	throttler.Notify(&v3)
 	suite.Equal(v1, value)
 
 	currentTime.now = t0.Add(time.Duration(delayMs-1) * time.Millisecond)
@@ -55,29 +55,3 @@ func (suite *ThrottlerTestSuite) Test_TwoNotificationsInSHortSucessionSecondOneI
 	throttler.Ping()
 	suite.Equal(0, value)
 }
-
-func (suite *ThrottlerTestSuite) Test_DuplicateEventsIgnored() {
-	value := 0
-	mindelay := 1 * time.Second
-	throttler := NewThrottler[int](func(v int) {
-		value = v
-	}, mindelay)
-
-	t0 := time.Now()
-	v := 1
-	currentTime.now = t0
-	throttler.Notify(v)
-	suite.Equal(v, value)
-
-	// sending the same value again will not lead to a notification
-	value = 0
-	currentTime.now = currentTime.now.Add(2 * mindelay)
-	throttler.Notify(v)
-	suite.Equal(0, value)
-
-	// sending a different value later will lead to a new notification
-	currentTime.now = currentTime.now.Add(2 * mindelay)
-	v++
-	throttler.Notify(v)
-	suite.Equal(v, value)
-}

pkg/support/throttling/throttler.go

@@ -6,26 +6,20 @@ import (
 
 // Throttling notifications to prometheus and web clients
 // TO be used in a single-threaded manner.
-//
-// NOTE: the null value of type T is considered as a not-set value.
-//
-//	The best usage of Throttler is with a pointer type.
-type Throttler[T comparable] struct {
+type Throttler[T any] struct {
 	minDelay time.Duration
 	// ucntion to call to implement the notification.
-	notifier         func(t T)
+	notifier         func(t *T)
 	lastReportedTime time.Time
-	pendingValue     T
-	lastValue        T
+	pendingValue     *T
 }
 
-func NewThrottler[T comparable](notifier func(t T), minDelay time.Duration) Throttler[T] {
+func NewThrottler[T any](notifier func(t *T), minDelay time.Duration) Throttler[T] {
 	throttler := Throttler[T]{
 		minDelay:         minDelay,
 		notifier:         notifier,
 		lastReportedTime: time.Time{},
-		pendingValue:     *new(T),
-		lastValue:        *new(T),
+		pendingValue:     nil,
 	}
 	return throttler
 }
@@ -34,16 +28,11 @@ func NewThrottler[T comparable](notifier func(t T), minDelay time.Duration) Thro
 // for the last notification to be sent. If not, it is stored as a pending event to
 // be sent later. New events that come in before a notification is sent override the
 // pending event.
-func (throttler *Throttler[T]) Notify(value T) {
-	if throttler.lastValue == value {
-		// duplicate events are not sent.
-		return
-	}
+func (throttler *Throttler[T]) Notify(value *T) {
 	if clock.time().Sub(throttler.lastReportedTime) >= throttler.minDelay {
 		throttler.notifier(value)
 		throttler.lastReportedTime = clock.time()
-		throttler.lastValue = value
-		throttler.pendingValue = *new(T)
+		throttler.pendingValue = nil
 		return
 	}
 	throttler.pendingValue = value
@@ -52,7 +41,7 @@ func (throttler *Throttler[T]) Notify(value T) {
 // To be called periodically. It sends out any pending events if the time the last
 // notification was sent is long enough ago.
 func (throttler *Throttler[T]) Ping() {
-	if throttler.pendingValue != *new(T) {
+	if throttler.pendingValue != nil {
 		throttler.Notify(throttler.pendingValue)
 	}
 }