GeezerVison

Windowed algorithms assume time moves forward. When it does not, nothing fails loudly: a window holds samples that never coexisted, a rate is computed over a negative interval, a duplicate is counted twice. Retries, buffers flushed after a reconnect, several producers writing into one topic and a clock stepped backwards all cause this, and the cheap defence is to check the order explicitly.

Each timestamp is compared with the previous one and classified as INCREASING, DUPLICATE or BACKWARDS. The checker only reports, it does not reorder or drop anything, so lastTimestamp is always the most recent sample, not the largest. It also keeps the worst backwards step, which is what you need to size a reordering buffer. O(1) time per sample and O(1) state; non-finite timestamps are refused.

Tests: the first timestamp is always accepted, an ordered stream has no violations, duplicates and backwards steps are counted separately, the worst step is the largest one and not the last one, the stream is not reordered, scan returns one verdict per timestamp, and reset restores the initial state.

Signed-off-by: alxkm <[email protected]>

Signed-off-by: alxkm <[email protected]>