[#625] Limit listing generator with maxKeys

Signed-off-by: Denis Kirillov <denis@nspcc.ru>

api/layer/object.go

@@ -528,12 +528,6 @@ func (n *layer) getLatestObjectsVersions(ctx context.Context, p allObjectParams)
 	objects = make([]*data.ObjectInfo, 0, p.MaxKeys)
 
 	for obj := range objOutCh {
-		// TODO (@kirillovdenis) : #625 #612, #525 reconsider stop condition
-		// currently we handle 3 more items to reduce the likelihood of missing the last object in batch
-		// (potentially we can miss it because of pool of workers)
-		if len(objects) == p.MaxKeys+3 {
-			break
-		}
 		objects = append(objects, obj)
 	}
 
@@ -554,6 +548,7 @@ func nodesGenerator(ctx context.Context, p allObjectParams, nodeVersions []*data
 	existed := make(map[string]struct{}, len(nodeVersions)) // to squash the same directories
 
 	go func() {
+		var generated int
 	LOOP:
 		for _, node := range nodeVersions {
 			if shouldSkip(node, p, existed) {
@@ -564,6 +559,10 @@ func nodesGenerator(ctx context.Context, p allObjectParams, nodeVersions []*data
 			case <-ctx.Done():
 				break LOOP
 			case nodeCh <- node:
+				generated++
+				if generated == p.MaxKeys+1 { // we use maxKeys+1 to be able to know nextMarker/nextContinuationToken
+					break LOOP
+				}
 			}
 		}
 		close(nodeCh)
@@ -596,12 +595,18 @@ func (n *layer) initWorkerPool(ctx context.Context, size int, p allObjectParams,
 				wg.Add(1)
 				err = pool.Submit(func() {
 					defer wg.Done()
-					if oi := n.objectInfoFromObjectsCacheOrNeoFS(ctx, p.Bucket, node, p.Prefix, p.Delimiter); oi != nil {
+					oi := n.objectInfoFromObjectsCacheOrNeoFS(ctx, p.Bucket, node, p.Prefix, p.Delimiter)
+					if oi == nil {
+						// try to get object again
+						if oi = n.objectInfoFromObjectsCacheOrNeoFS(ctx, p.Bucket, node, p.Prefix, p.Delimiter); oi == nil {
+							// form object info with data that the tree node contains
+							oi = getPartialObjectInfo(p.Bucket, node)
+						}
+					}
 					select {
 					case <-ctx.Done():
 					case objCh <- oi:
 					}
-					}
 				})
 				if err != nil {
 					wg.Done()
@@ -617,6 +622,18 @@ func (n *layer) initWorkerPool(ctx context.Context, size int, p allObjectParams,
 	return objCh, nil
 }
 
+// getPartialObjectInfo form data.ObjectInfo using data available in data.NodeVersion.
+func getPartialObjectInfo(bktInfo *data.BucketInfo, node *data.NodeVersion) *data.ObjectInfo {
+	return &data.ObjectInfo{
+		ID:      node.OID,
+		CID:     bktInfo.CID,
+		Bucket:  bktInfo.Name,
+		Name:    node.FilePath,
+		Size:    node.Size,
+		HashSum: node.ETag,
+	}
+}
+
 func (n *layer) bucketNodeVersions(ctx context.Context, bkt *data.BucketInfo, prefix string) ([]*data.NodeVersion, error) {
 	var err error
 
@@ -756,7 +773,7 @@ func (n *layer) objectInfoFromObjectsCacheOrNeoFS(ctx context.Context, bktInfo *
 		n.log.Warn("couldn't cache an object", zap.Error(err))
 	}
 
-	return processObjectInfoName(oi, prefix, delimiter)
+	return oi
 }
 
 func tryDirectory(bktInfo *data.BucketInfo, node *data.NodeVersion, prefix, delimiter string) *data.ObjectInfo {