Commit Graph

6 Commits

Author SHA1 Message Date
Björn Rabenstein dccfb9db4e
histogram: Remove code replication via generics (#11361)
* histogram: Simplify iterators

We don't really need currLower and currUpper and can calculate it when
needed (as already done for the floatBucketIterator). The calculation
is cheap, while keeping those extra variables around costs RAM
(potentially a lot with many iterators).

* histogram: Convert Bucket/FloatBucket to one generic type

* histogram: Move some bucket iterator code into generic base iterator

* histogram: Remove cumulative iterator for FloatHistogram

We added it in the past for completeness (Histogram has one), but it
has never been used. Plus, even the cumulative iterator for Histogram
is only there for test reasons.

We can always add it back, and then maybe even using generics.

Signed-off-by: beorn7 <beorn@grafana.com>
2022-10-03 16:45:27 +05:30
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
Ganesh Vernekar 2474c6fb2c
Error on amending histograms on append (#11308)
* Error on amending histograms on append

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Rename Matches to Equals

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2022-09-19 13:10:30 +05:30
beorn7 6a820a646c histogram: Add FloatHistogram
Including a few adjustments for normal Histogram, too, e.g. use
pointer receiver to avoid the large copy on method calls.

Signed-off-by: beorn7 <beorn@grafana.com>
2021-11-23 19:40:49 +01:00
beorn7 f1065e44a4 model: String method for histogram.Histogram
This includes a regular bucket iterator and a string method for
histogram.Bucket.

Signed-off-by: beorn7 <beorn@grafana.com>
2021-11-11 17:29:22 +01:00
beorn7 7a8bb8222c Style cleanup of all the changes in sparsehistogram so far
A lot of this code was hacked together, literally during a
hackathon. This commit intends not to change the code substantially,
but just make the code obey the usual style practices.

A (possibly incomplete) list of areas:

* Generally address linter warnings.

* The `pgk` directory is deprecated as per dev-summit. No new packages should
  be added to it. I moved the new `pkg/histogram` package to `model`
  anticipating what's proposed in #9478.

* Make the naming of the Sparse Histogram more consistent. Including
  abbreviations, there were just too many names for it: SparseHistogram,
  Histogram, Histo, hist, his, shs, h. The idea is to call it "Histogram" in
  general. Only add "Sparse" if it is needed to avoid confusion with
  conventional Histograms (which is rare because the TSDB really has no notion
  of conventional Histograms). Use abbreviations only in local scope, and then
  really abbreviate (not just removing three out of seven letters like in
  "Histo"). This is in the spirit of
  https://github.com/golang/go/wiki/CodeReviewComments#variable-names

* Several other minor name changes.

* A lot of formatting of doc comments. For one, following
  https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences
  , but also layout question, anticipating how things will look like
  when rendered by `godoc` (even where `godoc` doesn't render them
  right now because they are for unexported types or not a doc comment
  at all but just a normal code comment - consistency is queen!).

* Re-enabled `TestQueryLog` and `TestEndopints` (they pass now,
  leaving them disabled was presumably an oversight).

* Bucket iterator for histogram.Histogram is now created with a
  method.

* HistogramChunk.iterator now allows iterator recycling. (I think
  @dieterbe only commented it out because he was confused by the
  question in the comment.)

* HistogramAppender.Append panics now because we decided to treat
  staleness marker differently.

Signed-off-by: beorn7 <beorn@grafana.com>
2021-10-11 13:02:03 +02:00