Function doIncreasePageCache

src/tests/containerizer/memory_test_helper.cpp:234–283

static Try<Nothing> doIncreasePageCache(const vector<string>& tokens)
{
  const Bytes UNIT = Megabytes(1);

  if (tokens.size() < 2) {
    return Error("Expect at least one argument");
  }

  Try<Bytes> size = Bytes::parse(tokens[1]);
  if (size.isError()) {
    return Error("The first argument '" + tokens[1] + "' is not a byte size");
  }

  // TODO(chzhcn): Currently, we assume the current working directory
  // is a temporary directory and will be cleaned up when the test
  // finishes. Since the child process will inherit the current
  // working directory from the parent process, that means the test
  // that uses this helper probably needs to inherit from
  // TemporaryDirectoryTest. Consider relaxing this constraint.
  Try<string> path = os::mktemp(path::join(os::getcwd(), "XXXXXX"));
  if (path.isError()) {
    return Error("Failed to create a temporary file: " + path.error());
  }

  Try<int_fd> fd = os::open(path.get(), O_WRONLY);
  if (fd.isError()) {
    return Error("Failed to open file: " + fd.error());
  }

  // NOTE: We are doing round-down here to calculate the number of
  // writes to do.
  for (uint64_t i = 0; i < size->bytes() / UNIT.bytes(); i++) {
    // Write UNIT size to disk at a time. The content isn't important.
    Try<Nothing> write = os::write(fd.get(), string(UNIT.bytes(), 'a'));
    if (write.isError()) {
      os::close(fd.get());
      return Error("Failed to write file: " + write.error());
    }

    // Use fsync to make sure data is written to disk.
    Try<Nothing> fsync = os::fsync(fd.get());
    if (fsync.isError()) {
      os::close(fd.get());
      return Error("Failed to fsync: " + fsync.error());
    }
  }

  os::close(fd.get());
  return Nothing();
}


const char MemoryTestHelper::NAME[] = "Memory";