How to see the buffer usage

Hey guys,

Akka stream has a nice feature, the buffers (with backpressure).

.buffer(1000, OverflowStrategy.backpressure())

It works pretty good but sometimes it is hard to decide how big it should be. I see in the logs if its full but not how much of this buffer is used. It could be also too large.
Is there a possibility too see how much data is in a buffer?

One way would be to tap the .buffer() step with two counting stations working with the same shared counter (increment it in the pre-step and decrement in the post-step).