// https://github.com/googleapis/google-cloud-cpp/issues/4482 is done.
GCSFile::GCSFile(google::cloud::storage::Client&& gcs_client)
    : gcs_client(gcs_client), block_cache_lock() {
  const char* append_mode = std::getenv(kAppendMode);
  compose = (append_mode != nullptr) && (!strcmp(kAppendMode, append_mode));

  uint64_t value;
  block_size = kDefaultBlockSize;