NewBuffer create a buffer with the options.

WithBufferingIdleTime defines the idle time of the background goroutine keeping when the self-defined queue is empty.

WithChannelCapacity set the channel capacity, this value could not be changed after the Buffer is created.

WithQueueCapacity set the self-defined queue capacity, this value could be changed by SetCapacity method.

WithQueuePolicy defines the policy when the queue is full.

Buffer provides the channel that capacity can be extended dynamically.