private function insertChunk($data)
{
$chunkDocument = ['files_id' => $this->documentId, 'n' => $this->chunkCount, 'data' => new Binary($data, Binary::TYPE_GENERIC)];
hash_update($this->hashContext, $data);
$this->collection->getChunkCollection()->insert($chunkDocument);
$this->length += StringHelper::byteLength($data);
$this->chunkCount++;
}