Function fetchSize

src/slave/containerizer/fetcher.cpp:308–360

Find out how large a potential download from the given URI is.

// Find out how large a potential download from the given URI is.
static Try<Bytes> fetchSize(
    const string& uri,
    const Option<string>& frameworksHome)
{
  VLOG(1) << "Fetching size for URI: " << uri;

  Result<string> path = Fetcher::uriToLocalPath(uri, frameworksHome);
  if (path.isError()) {
    return Error(path.error());
  }
  if (path.isSome()) {
    Try<Bytes> size = os::stat::size(
        path.get(), os::stat::FollowSymlink::FOLLOW_SYMLINK);
    if (size.isError()) {
      return Error("Could not determine file size for: '" + path.get() +
                     "', error: " + size.error());
    }
    return size.get();
  }

  if (Fetcher::isNetUri(uri)) {
    Try<Bytes> size = net::contentLength(uri);
    if (size.isError()) {
      return Error(size.error());
    }
    if (size.get() == 0) {
      return Error("URI reported content-length 0: " + uri);
    }

    return size.get();
  }

  // TODO(hausdorff): (MESOS-5460) Explore adding support for fetching from
  // HDFS.
#ifndef __WINDOWS__
  Try<Owned<HDFS>> hdfs = HDFS::create();
  if (hdfs.isError()) {
    return Error("Failed to create HDFS client: " + hdfs.error());
  }

  Future<Bytes> size = hdfs.get()->du(uri);
  size.await();

  if (!size.isReady()) {
    return Error("Hadoop client could not determine size: " +
                 (size.isFailed() ? size.failure() : "discarded"));
  }

  return size.get();
#else
  return Error("Windows currently does not support fetching files from HDFS");
#endif // __WINDOWS__
}


Future<Nothing> FetcherProcess::fetch(