uint64 start = Env::Default()->NowSeconds();
  do {
    Env::Default()->SleepForMicroseconds(100000);
  } while (cache.CacheSize() == 24 && Env::Default()->NowSeconds() - start < 3);
  // There should be one block left in the cache, and it should be the first
  // block of "b".
  EXPECT_EQ(cache.CacheSize(), 8);
  TF_EXPECT_OK(ReadCache(&cache, "b", 0, 1, &out));
  EXPECT_EQ(calls, 3);

    RemoveFile_Locked(filename);
    it->second = file_signature;
    return false;
  }
  file_signature_map_[filename] = file_signature;
  return true;
}

size_t RamFileBlockCache::CacheSize() const {
  absl::MutexLock lock(&mu_);
  return cache_size_;
}

void RamFileBlockCache::Prune() {
  while (!stop_pruning_thread_.WaitForNotificationWithTimeout(
      absl::Microseconds(1000000))) {

  size_t block_size() const { return block_size_; }
  size_t max_bytes() const { return max_bytes_; }
  uint64_t max_staleness() const { return max_staleness_; }

  /// The current size (in bytes) of the cache.
  size_t CacheSize() const ABSL_LOCKS_EXCLUDED(mu_);

  // Returns true if the cache is enabled. If false, the BlockFetcher callback
  // is always executed during Read.