[BUG] Handle auto refresh cache race condition

flytestdlib/cache/auto_refresh.go

@@ -118,7 +118,7 @@
 	lruMap          *lru.Cache
 	// Items that are currently being processed are in the processing set.
 	// It will prevent the same item from being processed multiple times by different workers.
-	processing  *syncSet
+	processing  *sync.Map
 	toDelete    *syncSet
 	syncPeriod  time.Duration
 	workqueue   workqueue.RateLimitingInterface
@@ -220,7 +220,7 @@
 	batch := make([]ItemWrapper, 0, 1)
 	batch = append(batch, itemWrapper{id: id, item: item})
 	w.workqueue.AddRateLimited(&batch)
-	w.processing.Insert(id)
+	w.processing.Store(id, time.Now())
 	return item, nil
 }
 
@@ -246,7 +246,7 @@
 		// If not ok, it means evicted between the item was evicted between getting the keys and this update loop
 		// which is fine, we can just ignore.
 		if value, ok := w.lruMap.Peek(k); ok {
-			if item, ok := value.(Item); !ok || (ok && !item.IsTerminal() && !w.processing.Contains(k)) {
+			if item, ok := value.(Item); !ok || (ok && !item.IsTerminal() && !w.inProcessing(k)) {
 				snapshot = append(snapshot, itemWrapper{
 					id:   k.(ItemID),
 					item: value.(Item),
@@ -264,7 +264,7 @@
 		b := batch
 		w.workqueue.AddRateLimited(&b)
 		for i := 1; i < len(b); i++ {
-			w.processing.Insert(b[i].GetID())
+			w.processing.Store(b[i].GetID(), time.Now())
 		}
 	}
 
@@ -316,7 +316,7 @@
 			newBatch := make(Batch, 0, len(*batch.(*Batch)))
 			for _, b := range *batch.(*Batch) {
 				itemID := b.GetID()
-				w.processing.Remove(itemID)
+				w.processing.Delete(itemID)
 				item, ok := w.lruMap.Get(itemID)
 				if !ok {
 					logger.Debugf(ctx, "item with id [%v] not found in cache", itemID)
@@ -359,6 +359,20 @@
 	}
 }
 
+// Checks if the item is currently being processed and returns false if the item has been in processing for too long
+func (w *autoRefresh) inProcessing(key interface{}) bool {
+	item, found := w.processing.Load(key)
+	if found {
+		// handle potential race conditions where the item is in processing but not in the workqueue
+		if timeItem, ok := item.(time.Time); ok && time.Since(timeItem) > (w.syncPeriod*5) {
+			w.processing.Delete(key)
+			return false
+		}
+		return true
+	}
+	return false
+}
+
 // Instantiates a new AutoRefresh Cache that syncs items in batches.
 func NewAutoRefreshBatchedCache(name string, createBatches CreateBatchesFunc, syncCb SyncFunc, syncRateLimiter workqueue.RateLimiter,
 	resyncPeriod time.Duration, parallelizm, size int, scope promutils.Scope) (AutoRefresh, error) {
@@ -376,7 +390,7 @@
 		createBatchesCb: createBatches,
 		syncCb:          syncCb,
 		lruMap:          lruCache,
-		processing:      newSyncSet(),
+		processing:      &sync.Map{},
 		toDelete:        newSyncSet(),
 		syncPeriod:      resyncPeriod,
 		workqueue:       workqueue.NewNamedRateLimitingQueue(syncRateLimiter, scope.CurrentScope()),

flytestdlib/cache/auto_refresh_test.go

@@ -210,3 +210,22 @@ func TestQueueBuildUp(t *testing.T) {
 	time.Sleep(5 * time.Second)
 	assert.Equal(t, int32(size), syncCount.Load())
 }
+
+func TestInProcessing(t *testing.T) {
+
+	syncPeriod := time.Millisecond
+	cache := &autoRefresh{
+		processing: &sync.Map{},
+		syncPeriod: syncPeriod,
+	}
+
+	assert.False(t, cache.inProcessing("test"))
+
+	cache.processing.Store("test", time.Now())
+	assert.True(t, cache.inProcessing("test"))
+
+	cache.processing.Store("test1", time.Now().Add(syncPeriod*-11))
+	assert.False(t, cache.inProcessing("test1"))
+	_, found := cache.processing.Load("test1")
+	assert.False(t, found)
+}