Implement bulk delete (#7607)

Bulk delete at storage level in Multiple Delete Objects API

In order to accelerate bulk delete in Multiple Delete objects API,
a new bulk delete is introduced in storage layer, which will accept
a list of objects to delete rather than only one. Consequently,
a new API is also need to be added to Object API.

cmd/object-api-common.go

@@ -144,6 +144,78 @@ func cleanupDir(ctx context.Context, storage StorageAPI, volume, dirPath string)
 	return err
 }
 
+// Cleanup objects in bulk and recursively: each object will have a list of sub-files to delete in the backend
+func cleanupObjectsBulk(ctx context.Context, storage StorageAPI, volume string, objsPaths []string, errs []error) ([]error, error) {
+	// The list of files in disk to delete
+	var filesToDelete []string
+	// Map files to delete to the passed objsPaths
+	var filesToDeleteObjsIndexes []int
+
+	// Traverse and return the list of sub entries
+	var traverse func(string) ([]string, error)
+	traverse = func(entryPath string) ([]string, error) {
+		var output = make([]string, 0)
+		if !hasSuffix(entryPath, slashSeparator) {
+			output = append(output, entryPath)
+			return output, nil
+		}
+		entries, err := storage.ListDir(volume, entryPath, -1, "")
+		if err != nil {
+			if err == errFileNotFound {
+				return nil, nil
+			}
+			return nil, err
+		}
+
+		for _, entry := range entries {
+			subEntries, err := traverse(pathJoin(entryPath, entry))
+			if err != nil {
+				return nil, err
+			}
+			output = append(output, subEntries...)
+		}
+		return output, nil
+	}
+
+	// Find and collect the list of files to remove associated
+	// to the passed objects paths
+	for idx, objPath := range objsPaths {
+		if errs[idx] != nil {
+			continue
+		}
+		output, err := traverse(objPath)
+		if err != nil {
+			errs[idx] = err
+			continue
+		} else {
+			errs[idx] = nil
+		}
+		filesToDelete = append(filesToDelete, output...)
+		for i := 0; i < len(output); i++ {
+			filesToDeleteObjsIndexes = append(filesToDeleteObjsIndexes, idx)
+		}
+	}
+
+	// Reverse the list so remove can succeed
+	reverseStringSlice(filesToDelete)
+
+	dErrs, err := storage.DeleteFileBulk(volume, filesToDelete)
+	if err != nil {
+		return nil, err
+	}
+
+	// Map files deletion errors to the correspondent objects
+	for i := range dErrs {
+		if dErrs[i] != nil {
+			if errs[filesToDeleteObjsIndexes[i]] != nil {
+				errs[filesToDeleteObjsIndexes[i]] = dErrs[i]
+			}
+		}
+	}
+
+	return errs, nil
+}
+
 // Removes notification.xml for a given bucket, only used during DeleteBucket.
 func removeNotificationConfig(ctx context.Context, objAPI ObjectLayer, bucket string) error {
 	// Verify bucket is valid.