* 2000 ops.
   */
  private fun journalRebuildRequired(): Boolean {
    val redundantOpCompactThreshold = 2000
    return redundantOpCount >= redundantOpCompactThreshold &&
      redundantOpCount >= lruEntries.size
  }

  /**
   * Drops the entry for [key] if it exists and can be removed. If the entry for [key] is currently