beorn7 a7c519930e histograms: Add Compact method to the normal integer Histogram ... And use the new method to call to compact Histograms during parsing. This happens for both `Histogram` and `FloatHistogram`. In this way, if targets decide to optimize the exposition size by merging spans with empty buckets in between, we still get a normalized results. It will also normalize away any valid but weird representations like empty spans, spans with offset zero, and empty buckets at the start or end of a span. The implementation seemed easy at first as it just turns the `compactBuckets` helper into a generic function (which now got its own file). However, the integer Histograms have delta buckets instead of absolute buckets, which had to be treated specially in the generic `compactBuckets` function. To make sure it works, I have added plenty of explicit tests for `Histogram` in addition to the `FloatHistogram` tests. I have also updated the doc comment for the `Compact` method. Based on the insights now expressed in the doc comment, compacting with a maxEmptyBuckets > 0 is rarely useful. Therefore, this commit also sets the value to 0 in the two cases we were using 3 so far. We might still want to reconsider, so I don't want to remove the maxEmptyBuckets parameter right now. Signed-off-by: beorn7 <beorn@grafana.com>		2022-09-27 13:04:16 +02:00
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config.yml	histograms: Add Compact method to the normal integer Histogram	2022-09-27 13:04:16 +02:00