controller: deduplicate items in queue (#17168)

agent/consul/controller/queue/defer.go

@@ -41,7 +41,7 @@ type deferredRequest[T ItemType] struct {
 // future processing
 type deferQueue[T ItemType] struct {
 	heap    *deferHeap[T]
-	entries map[T]*deferredRequest[T]
+	entries map[string]*deferredRequest[T]
 
 	addChannel     chan *deferredRequest[T]
 	heartbeat      *time.Ticker
@@ -55,7 +55,7 @@ func NewDeferQueue[T ItemType](tick time.Duration) DeferQueue[T] {
 
 	return &deferQueue[T]{
 		heap:       dHeap,
-		entries:    make(map[T]*deferredRequest[T]),
+		entries:    make(map[string]*deferredRequest[T]),
 		addChannel: make(chan *deferredRequest[T]),
 		heartbeat:  time.NewTicker(tick),
 	}
@@ -78,7 +78,7 @@ func (q *deferQueue[T]) Defer(ctx context.Context, item T, until time.Time) {
 
 // deferEntry adds a deferred request to the priority queue
 func (q *deferQueue[T]) deferEntry(entry *deferredRequest[T]) {
-	existing, exists := q.entries[entry.item]
+	existing, exists := q.entries[entry.item.Key()]
 	if exists {
 		// insert or update the item deferral time
 		if existing.enqueueAt.After(entry.enqueueAt) {
@@ -90,7 +90,7 @@ func (q *deferQueue[T]) deferEntry(entry *deferredRequest[T]) {
 	}
 
 	heap.Push(q.heap, entry)
-	q.entries[entry.item] = entry
+	q.entries[entry.item.Key()] = entry
 }
 
 // readyRequest returns a pointer to the next ready Request or
@@ -108,7 +108,7 @@ func (q *deferQueue[T]) readyRequest() *T {
 	}
 
 	entry = heap.Pop(q.heap).(*deferredRequest[T])
-	delete(q.entries, entry.item)
+	delete(q.entries, entry.item.Key())
 	return &entry.item
 }
 
@@ -182,8 +182,6 @@ func (q *deferQueue[T]) Process(ctx context.Context, callback func(item T)) {
 	}
 }
 
-var _ heap.Interface = &deferHeap[string]{}
-
 // deferHeap implements heap.Interface
 type deferHeap[T ItemType] []*deferredRequest[T]
 

agent/consul/controller/queue/queue.go

@@ -13,7 +13,10 @@ import (
 // https://github.com/kubernetes/client-go/blob/release-1.25/util/workqueue/queue.go
 
 // ItemType is the type constraint for items in the WorkQueue.
-type ItemType comparable
+type ItemType interface {
+	// Key returns a string that will be used to de-duplicate items in the queue.
+	Key() string
+}
 
 // WorkQueue is an interface for a work queue with semantics to help with
 // retries and rate limiting.
@@ -43,9 +46,9 @@ type queue[T ItemType] struct {
 
 	// dirty holds the working set of all Requests, whether they are being
 	// processed or not
-	dirty map[T]struct{}
+	dirty map[string]struct{}
 	// processing holds the set of current requests being processed
-	processing map[T]struct{}
+	processing map[string]struct{}
 
 	// deferred is an internal priority queue that tracks deferred
 	// Requests
@@ -66,8 +69,8 @@ type queue[T ItemType] struct {
 func RunWorkQueue[T ItemType](ctx context.Context, baseBackoff, maxBackoff time.Duration) WorkQueue[T] {
 	q := &queue[T]{
 		ratelimiter: NewRateLimiter[T](baseBackoff, maxBackoff),
-		dirty:       make(map[T]struct{}),
-		processing:  make(map[T]struct{}),
+		dirty:       make(map[string]struct{}),
+		processing:  make(map[string]struct{}),
 		cond:        sync.NewCond(&sync.Mutex{}),
 		deferred:    NewDeferQueue[T](500 * time.Millisecond),
 		ctx:         ctx,
@@ -115,8 +118,8 @@ func (q *queue[T]) Get() (item T, shutdown bool) {
 
 	item, q.queue = q.queue[0], q.queue[1:]
 
-	q.processing[item] = struct{}{}
-	delete(q.dirty, item)
+	q.processing[item.Key()] = struct{}{}
+	delete(q.dirty, item.Key())
 
 	return item, false
 }
@@ -129,12 +132,12 @@ func (q *queue[T]) Add(item T) {
 	if q.shuttingDown() {
 		return
 	}
-	if _, ok := q.dirty[item]; ok {
+	if _, ok := q.dirty[item.Key()]; ok {
 		return
 	}
 
-	q.dirty[item] = struct{}{}
-	if _, ok := q.processing[item]; ok {
+	q.dirty[item.Key()] = struct{}{}
+	if _, ok := q.processing[item.Key()]; ok {
 		return
 	}
 
@@ -175,8 +178,8 @@ func (q *queue[T]) Done(item T) {
 	q.cond.L.Lock()
 	defer q.cond.L.Unlock()
 
-	delete(q.processing, item)
-	if _, ok := q.dirty[item]; ok {
+	delete(q.processing, item.Key())
+	if _, ok := q.dirty[item.Key()]; ok {
 		q.queue = append(q.queue, item)
 		q.cond.Signal()
 	}

agent/consul/controller/queue/rate.go

@@ -22,10 +22,8 @@ type Limiter[T ItemType] interface {
 	Forget(request T)
 }
 
-var _ Limiter[string] = &ratelimiter[string]{}
-
 type ratelimiter[T ItemType] struct {
-	failures map[T]int
+	failures map[string]int
 	base     time.Duration
 	max      time.Duration
 	mutex    sync.RWMutex
@@ -35,7 +33,7 @@ type ratelimiter[T ItemType] struct {
 // backoff.
 func NewRateLimiter[T ItemType](base, max time.Duration) Limiter[T] {
 	return &ratelimiter[T]{
-		failures: make(map[T]int),
+		failures: make(map[string]int),
 		base:     base,
 		max:      max,
 	}
@@ -47,8 +45,8 @@ func (r *ratelimiter[T]) NextRetry(request T) time.Duration {
 	r.mutex.RLock()
 	defer r.mutex.RUnlock()
 
-	exponent := r.failures[request]
-	r.failures[request] = r.failures[request] + 1
+	exponent := r.failures[request.Key()]
+	r.failures[request.Key()] = r.failures[request.Key()] + 1
 
 	backoff := float64(r.base.Nanoseconds()) * math.Pow(2, float64(exponent))
 	// make sure we don't overflow time.Duration
@@ -69,5 +67,5 @@ func (r *ratelimiter[T]) Forget(request T) {
 	r.mutex.Lock()
 	defer r.mutex.Unlock()
 
-	delete(r.failures, request)
+	delete(r.failures, request.Key())
 }

agent/consul/controller/queue/rate_test.go

@@ -12,6 +12,8 @@ import (
 
 type Request struct{ Kind string }
 
+func (r Request) Key() string { return r.Kind }
+
 func TestRateLimiter_Backoff(t *testing.T) {
 	t.Parallel()
 

agent/consul/controller/queue_test.go

@@ -10,8 +10,6 @@ import (
 	"github.com/hashicorp/consul/agent/consul/controller/queue"
 )
 
-var _ queue.WorkQueue[string] = &countingWorkQueue[string]{}
-
 type countingWorkQueue[T queue.ItemType] struct {
 	getCounter            uint64
 	addCounter            uint64

agent/consul/controller/reconciler.go

@@ -20,6 +20,18 @@ type Request struct {
 	Meta *acl.EnterpriseMeta
 }
 
+// Key satisfies the queue.ItemType interface. It returns a string which will be
+// used to de-duplicate requests in the queue.
+func (r Request) Key() string {
+	return fmt.Sprintf(
+		`kind=%q,name=%q,part=%q,ns=%q`,
+		r.Kind,
+		r.Name,
+		r.Meta.PartitionOrDefault(),
+		r.Meta.NamespaceOrDefault(),
+	)
+}
+
 // RequeueAfterError is an error that allows a Reconciler to override the
 // exponential backoff behavior of the Controller, rather than applying
 // the backoff algorithm, returning a RequeueAfterError will cause the

internal/controller/api.go

@@ -127,6 +127,19 @@ type Request struct {
 	ID *pbresource.ID
 }
 
+// Key satisfies the queue.ItemType interface. It returns a string which will be
+// used to de-duplicate requests in the queue.
+func (r Request) Key() string {
+	return fmt.Sprintf(
+		"part=%q,peer=%q,ns=%q,name=%q,uid=%q",
+		r.ID.Tenancy.Partition,
+		r.ID.Tenancy.PeerName,
+		r.ID.Tenancy.Namespace,
+		r.ID.Name,
+		r.ID.Uid,
+	)
+}
+
 // Runtime contains the dependencies required by reconcilers.
 type Runtime struct {
 	Client pbresource.ResourceServiceClient

internal/controller/controller.go

@@ -43,11 +43,13 @@ func (c *controllerRunner) run(ctx context.Context) error {
 
 	for _, watch := range c.ctrl.watches {
 		watch := watch
-		mapQueue := runQueue[*pbresource.Resource](groupCtx, c.ctrl)
+		mapQueue := runQueue[mapperRequest](groupCtx, c.ctrl)
 
 		// Watched Type Events → Mapper Queue
 		group.Go(func() error {
-			return c.watch(groupCtx, watch.watchedType, mapQueue.Add)
+			return c.watch(groupCtx, watch.watchedType, func(res *pbresource.Resource) {
+				mapQueue.Add(mapperRequest{res: res})
+			})
 		})
 
 		// Mapper Queue → Mapper → Reconciliation Queue
@@ -96,13 +98,13 @@ func (c *controllerRunner) watch(ctx context.Context, typ *pbresource.Type, add
 func (c *controllerRunner) runMapper(
 	ctx context.Context,
 	w watch,
-	from queue.WorkQueue[*pbresource.Resource],
+	from queue.WorkQueue[mapperRequest],
 	to queue.WorkQueue[Request],
 ) error {
 	logger := c.logger.With("watched_resource_type", resource.ToGVK(w.watchedType))
 
 	for {
-		res, shutdown := from.Get()
+		item, shutdown := from.Get()
 		if shutdown {
 			return nil
 		}
@@ -110,12 +112,12 @@ func (c *controllerRunner) runMapper(
 		var reqs []Request
 		err := c.handlePanic(func() error {
 			var err error
-			reqs, err = w.mapper(ctx, c.runtime(), res)
+			reqs, err = w.mapper(ctx, c.runtime(), item.res)
 			return err
 		})
 		if err != nil {
-			from.AddRateLimited(res)
-			from.Done(res)
+			from.AddRateLimited(item)
+			from.Done(item)
 			continue
 		}
 
@@ -130,8 +132,8 @@ func (c *controllerRunner) runMapper(
 			to.Add(r)
 		}
 
-		from.Forget(res)
-		from.Done(res)
+		from.Forget(item)
+		from.Done(item)
 	}
 }
 
@@ -183,3 +185,19 @@ func (c *controllerRunner) runtime() Runtime {
 		Logger: c.logger,
 	}
 }
+
+type mapperRequest struct{ res *pbresource.Resource }
+
+// Key satisfies the queue.ItemType interface. It returns a string which will be
+// used to de-duplicate requests in the queue.
+func (i mapperRequest) Key() string {
+	return fmt.Sprintf(
+		"type=%q,part=%q,peer=%q,ns=%q,name=%q,uid=%q",
+		resource.ToGVK(i.res.Id.Type),
+		i.res.Id.Tenancy.Partition,
+		i.res.Id.Tenancy.PeerName,
+		i.res.Id.Tenancy.Namespace,
+		i.res.Id.Name,
+		i.res.Id.Uid,
+	)
+}