private val readCompleteLatch = CountDownLatch(1)

  // The lists are held as a large array of UTF-8 bytes. This is to avoid allocating lots of strings
  // that will likely never be used. Each rule is separated by '\n'. Please see the
  // PublicSuffixListGenerator class for how these lists are generated.
  // Guarded by this.
  private lateinit var publicSuffixListBytes: ByteArray