Circular buffer

[altavir]

A fixed size buffer, where you can add a new element automatically evicting last one (implemented by fixed size array with moving begin pointer).
In Java I would use ArrayDeque with manual adding and popping, but it is not very convenient and not thread safe.

[lamba92]

Well for concurrency you could always use AtomicFU for whatever object and make accessing it atomic.

[altavir]

Yep. It is not that easy to use though. I will implement it in kmath and if it works like I want, I will move it here.