class CustomReadWriteLock {

    private val mutex = Mutex()
    private var readers = 0
    private val noReaders = Channel<Unit>(1) // 用于控制没有读者时通知写操作
suspend fun <T> read(action: suspend () -> T): T {
    mutex.withLock {
        readers++
    }
    try {
        return action()
    } finally {
        mutex.withLock {
            readers--
            if (readers == 0) {
                noReaders.trySend(Unit)  // 读取者为0，通知写操作可以继续
            }
        }
    }
}

suspend fun <T> write(action: suspend () -> T): T {
    mutex.withLock {
        if (readers > 0) {
            noReaders.receive()  // 如果还有读者，等待读者完成
        }
    }

    return mutex.withLock {
        try {
            action()
        } finally {
            if (readers == 0) {
                noReaders.trySend(Unit)  // 完成写操作后，如果没有读者，重置状态
            }
        }
    }
  }
}