Remove NotificationQueuer.Close

In order to cleanup the dual stop + close we introduce a queueLock allowing for a since queueCloser func to be returned by Open instead of a done channel which requires a Close call.

Author: boekkooi-fresh

driver/sql/projection_notification_processor.go

@@ -12,7 +12,6 @@ import (
 type (
 	// ProjectionNotificationProcessor provides a way to Trigger a notification using a set of background processes.
 	ProjectionNotificationProcessor struct {
-		done            chan struct{}
 		queueProcessors int
 
 		logger  goengine.Logger
@@ -83,7 +82,7 @@ func (b *ProjectionNotificationProcessor) Execute(ctx context.Context, handler P
 
 // Start starts the background processes that will call the ProcessHandler based on the notification queued by Exec
 func (b *ProjectionNotificationProcessor) Start(ctx context.Context, handler ProcessHandler) func() {
-	b.done = b.notificationQueue.Open()
+	queueClose := b.notificationQueue.Open()
 
 	var wg sync.WaitGroup
 	wg.Add(b.queueProcessors)
@@ -98,9 +97,8 @@ func (b *ProjectionNotificationProcessor) Start(ctx context.Context, handler Pro
 	runtime.Gosched()
 
 	return func() {
-		close(b.done)
+		queueClose()
 		wg.Wait()
-		b.notificationQueue.Close()
 	}
 }
 

driver/sql/projection_notification_processor_test.go

@@ -73,8 +73,11 @@ func TestStartProcessor(t *testing.T) {
 			channel <- notification
 			called := false
 
-			expect.Open().DoAndReturn(func() chan struct{} {
-				return done
+			expect.Open().DoAndReturn(func() func() {
+				return func() {
+					close(done)
+					close(channel)
+				}
 			}).AnyTimes()
 
 			expect.Next(gomock.Eq(ctx)).DoAndReturn(func(ctx context.Context) (*sql.ProjectionNotification, bool) {
@@ -85,10 +88,6 @@ func TestStartProcessor(t *testing.T) {
 				return notification, false
 			}).AnyTimes()
 
-			expect.Close().Do(func() {
-				close(channel)
-			})
-
 			processor, err := sql.NewBackgroundProcessor(queueProcessorsCount, queueBufferSize, nil, nil, notificationQueue)
 			require.NoError(t, err)
 

driver/sql/projection_notification_queue.go

@@ -3,20 +3,17 @@ package sql
 import (
 	"context"
 	"errors"
+	"sync"
 	"time"
 )
 
-// Ensure the NotificationQueue.Queue is a ProjectionTrigger
-var _ ProjectionTrigger = (&NotificationQueue{}).Queue
-
-// Ensure the NotificationQueue.ReQueue is a ProjectionTrigger
-var _ ProjectionTrigger = (&NotificationQueue{}).ReQueue
+// Ensure the NotificationQueue is a NotificationQueuer
+var _ NotificationQueuer = &NotificationQueue{}
 
 type (
 	// NotificationQueuer describes a smart queue for projection notifications
 	NotificationQueuer interface {
-		Open() chan struct{}
-		Close()
+		Open() func()
 
 		Empty() bool
 		Next(context.Context) (*ProjectionNotification, bool)
@@ -31,6 +28,7 @@ type (
 		metrics     Metrics
 		done        chan struct{}
 		queue       chan *ProjectionNotification
+		queueLock   sync.Mutex
 		queueBuffer int
 	}
 )
@@ -48,16 +46,21 @@ func newNotificationQueue(queueBuffer int, retryDelay time.Duration, metrics Met
 }
 
 // Open enables the queue for business
-func (nq *NotificationQueue) Open() chan struct{} {
+func (nq *NotificationQueue) Open() func() {
+	nq.queueLock.Lock()
+	defer nq.queueLock.Unlock()
+
 	nq.done = make(chan struct{})
 	nq.queue = make(chan *ProjectionNotification, nq.queueBuffer)
 
-	return nq.done
-}
+	return func() {
+		close(nq.done)
 
-// Close closes the queue channel
-func (nq *NotificationQueue) Close() {
-	close(nq.queue)
+		nq.queueLock.Lock()
+		defer nq.queueLock.Unlock()
+
+		close(nq.queue)
+	}
 }
 
 // Empty returns whether the queue is empty
@@ -75,7 +78,7 @@ func (nq *NotificationQueue) Next(ctx context.Context) (*ProjectionNotification,
 			return nil, true
 		case notification := <-nq.queue:
 			if notification != nil && notification.ValidAfter.After(time.Now()) {
-				nq.queue <- notification
+				nq.queueNotification(notification)
 				continue
 			}
 			return notification, false
@@ -95,7 +98,8 @@ func (nq *NotificationQueue) Queue(ctx context.Context, notification *Projection
 
 	nq.metrics.QueueNotification(notification)
 
-	nq.queue <- notification
+	nq.queueNotification(notification)
+
 	return nil
 }
 
@@ -105,3 +109,10 @@ func (nq *NotificationQueue) ReQueue(ctx context.Context, notification *Projecti
 
 	return nq.Queue(ctx, notification)
 }
+
+func (nq *NotificationQueue) queueNotification(notification *ProjectionNotification) {
+	nq.queueLock.Lock()
+	defer nq.queueLock.Unlock()
+
+	nq.queue <- notification
+}