1. The output format is now versioned per the Semantic Versioning scheme. Mainline Prometheus will be adapted to use differing consumption methodologies as the generators' formats evolve to support legacy clients.
2. The telemetry outputter now supports GZIP output encoding. In sample runs, this cuts the output size in half.
3. Basic sanity tests are added for registration with varying levels of pedanticness.
4. We have support for base labels in the registration and emission phases.
5. We have label support for individual metric mutation operations.
6. A number of simplications have been made.
According to the documentation:
// WriteHeader sends an HTTP response header with status code.
// If WriteHeader is not called explicitly, the first call to Write
// will trigger an implicit WriteHeader(http.StatusOK).
// Thus explicit calls to WriteHeader are mainly used to
// send error codes.
and
// Header returns the header map that will be sent by WriteHeader.
// Changing the header after a call to WriteHeader (or Write) has
// no effect.
so calling `w.Header().Set(contentType, jsonContentType)` after calling
`w.WriteHeader` does not set the content type -- the call can be removed
though as it always set `http.StatusOK` which will be done anyways
- Provide better examples in the examples subdirectory.
- Make the comments consistent in terms of using multi-line format for future-proofing.
- Extract major constants out.
- Added normal and exponential distributions to one of the examples.
- Improved the naming of a couple of local variables.
- Handled an error in the AccumulatingBucket ValueForIndex function whereby
the vestigal old behavior was accidentally preserved and not updated.
This could have been caught had the tests been updated first.
- Simplify Histogram prospectiveIndexForPercentile such that various
small tasks it performs are extracted into separate functions for easier
testing and code comprehension.
- Remedy a regression in Histogram prospectiveIndexForPercentile whereby
the prospective index may have included the terminating element of a
bucket.
- Provide help for Histogram prospectiveIndexForPercentile such that requesting
the terminating element of a bucket will fast-forward to the first element of
the next non-empty bucket.
- Fix TallingBucket's boundary constant, because they were originally keyed toward
percentages [0, 100], not decimal-based ones. The antique tests had been
temporarily commented out, which prevented this regression from being exposed.
Matt T. Proud