class RWLock{
  private:
    // Synchronization variables
    Lock lock;
    CV readGo;
    CV writeGo;

    // State variables
    int activeReaders;
    int activeWriters;
    int waitingReaders;
    int waitingWriters;

  public:
    RWLock();
    ~RWLock() {};
    void startRead();
    void doneRead();
    void startWrite();
    void doneWrite();

  private:
    bool readShouldWait();
    bool writeShouldWait();
};