说明：   环形缓冲区的实现原理,在通信程序中，经常使用环形缓冲区作为数据结构来存放通信中发送和接收的数据。环形缓冲区是一个先进先出的循环缓冲区，可以向通信程序提供对缓冲区的互斥访问
(The principle of the ring buffer, in the communication process, often use ring buffers to store the data as a data structure to send and receive communications. FIFO ring buffer is a circular buffer that can provide exclusive access to the buffer to the communication program)