Commit Graph

116 Commits

Author SHA1 Message Date
beorn7 c00c6ed01f promql: Add more test cases for `histogram_quantile`
This is motivated by the doubts raised in #7970.

Signed-off-by: beorn7 <beorn@grafana.com>
2021-10-20 16:15:44 +02:00
Julien Pivotto c812ee794e
PromQL: Comment flaky test (#9545)
Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2021-10-19 13:13:56 +02:00
Julien Pivotto a18224d02d
make aggregations deterministic (#9459)
* Add deterministic test for aggregations

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

* Make aggregations deterministic

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

* Increase testing

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2021-10-17 15:16:38 +05:30
ziollek 55f9147b44
Add atan2 to scalar operators - issue #9485 (#9515)
* Add atan2 to scalar operators

Signed-off-by: Tomasz Ziolkowski <tomasz.ziolkowski@allegro.pl>
2021-10-15 16:03:11 +02:00
Levi Harrison 587cb95093 Add operator tests
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-23 10:30:46 -04:00
Levi Harrison 6faca22eec Add inverse hyperbolic functions
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-15 22:47:10 -04:00
Levi Harrison 53d88fd147 Added hyperbolic trig functions
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-15 22:47:10 -04:00
Levi Harrison a8ad569db8 Change spaces to tabs
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-15 22:47:10 -04:00
Levi Harrison f1d94cc5f6 Split and shortened tests
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-15 22:47:10 -04:00
Levi Harrison 814cd5844d Added tests
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-09-15 22:47:09 -04:00
Darshan Chaudhary c4f2e9eec5
Add present_over_time (#9097)
* Add present_over_time

Signed-off-by: darshanime <deathbullet@gmail.com>

* Add tests for present_over_time

Signed-off-by: darshanime <deathbullet@gmail.com>

* Address PR comments

Signed-off-by: darshanime <deathbullet@gmail.com>

* Add documentation for present_over_time

Signed-off-by: darshanime <deathbullet@gmail.com>

* Update documentation

Signed-off-by: darshanime <deathbullet@gmail.com>

* Update documentation comment

Signed-off-by: darshanime <deathbullet@gmail.com>
2021-07-29 12:38:11 +02:00
pschou aff3c702ab
promql: Add sgn, clamp and last_over_time functions (#8457)
* Add sgn, clamp and last_over_time functions

Signed-off-by: schou <pschou@users.noreply.github.com>
2021-02-20 16:34:52 +01:00
Ganesh Vernekar 9199fcb8d1
'@ <timestamp>' modifier (#8121)
This commit adds `@ <timestamp>` modifier as per this design doc: https://docs.google.com/document/d/1uSbD3T2beM-iX4-Hp7V074bzBRiRNlqUdcWP6JTDQSs/edit.

An example query:

```
rate(process_cpu_seconds_total[1m]) 
  and
topk(7, rate(process_cpu_seconds_total[1h] @ 1234))
```

which ranks based on last 1h rate and w.r.t. unix timestamp 1234 but actually plots the 1m rate.

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2021-01-20 16:27:39 +05:30
Ganesh Vernekar d30da66d77
Fix timestamp() method for vector selector inside paren (#8164)
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-11-09 18:21:50 +05:30
Harold Dost bf7c771f54
promql: Organize legacy tests into appropriate files (#7989)
* Separate tests into:
** Aggregators
** Functions
** Operators
** Selectors
* Remove simple files and place tests into other files.
* Eliminate some of the _over_time tests since there are already plenty of
  edge cases present in the functions.test file.

Relates to #740

Signed-off-by: Harold Dost <harolddost@gmail.com>
2020-10-07 10:09:20 +01:00
Brian Brazil 924ce978b7
Don't do literal regex matching optimisation when case insensitive. (#8013)
Fixes #7994

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
2020-10-06 13:16:26 +01:00
Julien Pivotto 6f9e7ff750
Drop metric name in bool comparison between two instant vectors (#7819)
* Drop metric name in bool comparison between two instant vectors

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-08-22 21:04:03 +02:00
Julien Pivotto 20ab94fedf
Hints: Separating out the range and offsets of PromQL subqueries (#7667)
Fix #7629

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-08-11 07:21:39 +01:00
Julien Pivotto d77b56e88e
Fix avg_over_time for nan and float64 overflows (#7346)
* Fix avg_over_time with Inf and NaN values

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-07-13 17:30:50 +02:00
Julien Pivotto 72425d4e3d
Add group() aggregator (#7480)
* Add group() aggregator

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-06-30 16:51:18 +02:00
Linas Medžiūnas 7eaffa7180
Fix off-by-one error in funcHistogramQuantile / ensureMonotonic (#7393)
* Fix off-by-one error in funcHistogramQuantile / ensureMonotonic
* Additional coverage for nonmonotonic histogram buckets

Signed-off-by: Linas Medziunas <linas.medziunas@gmail.com>
2020-06-15 11:32:10 +01:00
B++ d6374ae1b6
Return NaN for histogram_quantile when buckets have 0 observations (#7318)
Signed-off-by: jberny <f.bernardi89@gmail.com>
2020-06-01 09:40:39 +01:00
Callum Styan 5bb7f00d00
change labelset comparison in promql engine to avoid false positive during detection of duplicates (#7058)
* Use go1.14 new hash/maphash to hash both RHS and LHS instead of XOR'ing
which has been resulting in hash collisions.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Refactor engine labelset signature generation, just use labels.Labels
instead of hashes.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Address review comments; function comments + store result of
lhs.String+rhs.String as key.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Replace all signatureFunc usage with signatureFuncString.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Make optimizations to labels String function and generation of rhs+lhs
as string in resultMetric.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Use separate string functions that don't use strconv just for engine
maps.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Use a byte invalid separator instead of quoting and have a buffer
attached to EvalNodeHelper instead of using a global pool in the labels
package.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Address review comments.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Address more review comments, labels has a function that now builds a
byte slice without turning it into a string.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* Use two different non-ascii hex codes as byte separators between labels
and between sets of labels when building bytes of a Labels struct.

Signed-off-by: Callum Styan <callumstyan@gmail.com>

* We only need the 2nd byte invalid sep. at the beginning of a
labels.Bytes

Signed-off-by: Callum Styan <callumstyan@gmail.com>
2020-05-12 14:03:15 -07:00
Tobias Guggenmos 3a204be6b7 PromQL: Fix string and parentheses handling in engine (#6612)
* WIP: PromQL: Allow engine to return strings

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>

* Add test suggested by @roidelapluie

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>

* Fix typo in React UI

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>

* Fix parenthesis handling for functions and aggregator params

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>

* Add more tests

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>

* Fix React UI test

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>
2020-01-15 18:31:58 +01:00
Tobias Guggenmos d8bc24349c PromQL: Fix unary operator precedence (#6579)
* PromQL: Fix unary operator precedence

Fixes #6575

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>
2020-01-08 14:07:10 +00:00
Julien Pivotto e0afec906f add absent_over_time (#6490)
* Implement absent_over_time

Fixes #2882

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-01-03 15:26:12 +00:00
Julien Pivotto 4b3bab890d Fix absent output where two label matchers are identical (#6493)
Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2019-12-20 14:33:33 +00:00
Julius Volz bc1c7f1809 Fix scalar-vector comparisons (#5454)
* Fix scalar-vector comparisons

Fixes https://github.com/prometheus/prometheus/issues/5452

Signed-off-by: Julius Volz <julius.volz@gmail.com>
2019-04-11 10:42:16 +01:00
Daisy T 683fbc59ec exponentation operator to drop metric name in result of op operation (#5329)
Signed-off-by: Daisy T <daisyts@gmx.com>
2019-03-12 10:21:42 +00:00
Brian Brazil 858c363e94 Fix panic when aggregator param is not a literal.
The return value for checkForSeriesSetExpansion
is always nil, simplify.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
2019-03-04 12:00:05 +00:00
Brian Brazil c66aeb3fff
In histogram_quantile merge buckets with equivalent le values (#5158)
This makes things generally more resilient, and will
help with OpenMetrics transitions (and inconsistencies).

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
2019-02-01 10:22:44 +00:00
Ganesh Vernekar dbe55c1352 Subquery (#4831)
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2018-12-22 13:47:13 +00:00
Ben Kochie c6399296dc
Fix spelling/typos (#4921)
* Fix spelling/typos

Fix spelling/typos reported by codespell/misspell.
* UK -> US spelling changes.

Signed-off-by: Ben Kochie <superq@gmail.com>
2018-11-27 17:44:29 +01:00
Thomas Jackson abf6fe0a98 Change max/min over_time to handle NaNs properly (#4386)
We only want to return a NaN if the NaN is the only value

Signed-off-by: Thomas Jackson <jacksontj.89@gmail.com>

Fixes #4385
2018-09-26 08:58:16 +01:00
Harsh Agarwal 18a9a390b5 Add duplicate-labelset check for range/instant vectors (#4589)
Signed-off-by: Harsh Agarwal <cs15btech11019@iith.ac.in>
2018-09-18 10:46:13 +01:00
Dan Cech 9f4cb06a37 use Welford/Knuth method to compute standard deviation and variance (#4533)
* use Welford/Knuth method to compute standard deviation and variance, avoids float precision issues
* use better method for calculating avg and avg_over_time

Signed-off-by: Dan Cech <dcech@grafana.com>
2018-08-26 10:28:47 +01:00
Brian Brazil dd6781add2 Optimise PromQL (#3966)
* Move range logic to 'eval'

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make aggregegate range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* PromQL is statically typed, so don't eval to find the type.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Extend rangewrapper to multiple exprs

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Start making function evaluation ranged

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make instant queries a special case of range queries

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Eliminate evalString

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Evaluate range vector functions one series at a time

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make unary operators range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make binops range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Pass time to range-aware functions.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make simple _over_time functions range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reduce allocs when working with matrix selectors

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Add basic benchmark for range evaluation

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reuse objects for function arguments

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Do dropmetricname and allocating output vector only once.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Add range-aware support for range vector functions with params

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Optimise holt_winters, cut cpu and allocs by ~25%

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make rate&friends range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make more functions range aware. Document calling convention.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make date functions range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make simple math functions range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Convert more functions to be range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make more functions range aware

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Specialcase timestamp() with vector selector arg for range awareness

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove transition code for functions

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove the rest of the engine transition code

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove more obselete code

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove the last uses of the eval* functions

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove engine finalizers to prevent corruption

The finalizers set by matrixSelector were being called
just before the value they were retruning to the pool
was then being provided to the caller. Thus a concurrent query
could corrupt the data that the user has just been returned.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Add new benchmark suite for range functinos

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Migrate existing benchmarks to new system

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Expand promql benchmarks

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Simply test by removing unused range code

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* When testing instant queries, check range queries too.

To protect against subsequent steps in a range query being
affected by the previous steps, add a test that evaluates
an instant query that we know works again as a range query
with the tiimestamp we care about not being the first step.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reuse ring for matrix iters. Put query results back in pool.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reuse buffer when iterating over matrix selectors

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Unary minus should remove metric name

Cut down benchmarks for faster runs.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reduce repetition in benchmark test cases

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Work series by series when doing normal vectorSelectors

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Optimise benchmark setup, cuts time by 60%

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Have rangeWrapper use an evalNodeHelper to cache across steps

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Use evalNodeHelper with functions

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Cache dropMetricName within a node evaluation.

This saves both the calculations and allocs done by dropMetricName
across steps.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reuse input vectors in rangewrapper

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Reuse the point slices in the matrixes input/output by rangeWrapper

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make benchmark setup faster using AddFast

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Simplify benchmark code.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Add caching in VectorBinop

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Use xor to have one-level resultMetric hash key

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Add more benchmarks

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Call Query.Close in apiv1

This allows point slices allocated for the response data
to be reused by later queries, saving allocations.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Optimise histogram_quantile

It's now 5-10% faster with 97% less garbage generated for 1k steps

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make the input collection in rangeVector linear rather than quadratic

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Optimise label_replace, for 1k steps 15x fewer allocs and 3x faster

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Optimise label_join, 1.8x faster and 11x less memory for 1k steps

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Expand benchmarks, cleanup comments, simplify numSteps logic.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Address Fabian's comments

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Comments from Alin.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Address jrv's comments

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Remove dead code

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Address Simon's comments.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Rename populateIterators, pre-init some sizes

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Handle case where function has non-matrix args first

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Split rangeWrapper out to rangeEval function, improve comments

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Cleanup and make things more consistent

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Make EvalNodeHelper public

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

* Fabian's comments.

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>
2018-06-04 15:47:45 +02:00
David King 6286c10df0 Fix OOM when a large K is used in topk queries (#4087)
This attempts to close #3973.

Handles cases where the length of the input vector to an aggregate topk
/ bottomk function is less than the K paramater. The change updates
Prometheus to allocate a result vector the same length as the input
vector in these cases.

Previously Prometheus would out-of-memory panic for large K values. This
change makes that unlikely unless the size of the input vector is
equally large.

Signed-off-by: David King <dave@davbo.org>
2018-04-16 09:03:04 +01:00
Krasi Georgiev a53d4ed197 drop metric name for bool modifier (#3821)
fixes #3820
2018-02-11 16:15:55 +00:00
Krasi Georgiev 4801573b64 time() return milliseconds (#3811) 2018-02-08 11:39:13 +00:00
Brian Brazil b418063d1a
Add tests for negative selectors. (#3616)
https://github.com/prometheus/prometheus/issues/3575
2017-12-23 14:06:37 +00:00
Brian Brazil 99905f82a6 Remove keep_common modifier.
See #3060
2017-10-05 13:27:48 +01:00
Brian Brazil b2ac3d2d86 Remove count_scalar and drop_common_labels.
For #3060
2017-10-05 13:27:48 +01:00
Brian Brazil 67274f0794 Remove 4 interval staleness heuristic. (#3244)
This means that if there is no stale marker, only the usual staleness
delta (5m) applies.

It has occured to me that there is an oddity in the heurestic. It works
fine as long as you have 2 points within the last 5m, but breaks down
when the time window advances to the point where you have just 1 point.

Consider you had points at t=0 and t=10. With the heurestic it goes stale
at t=51, up until t=300. However from t=301 until t=310 we only
see the t=10 point and the series comes back to life. That is not
desirable.

I don't see a way to keep this form of heurestic working given this
issue, so thus I'm removing it.
2017-10-05 12:55:14 +01:00
Fabian Reinartz ca2b68889b Merge branch 'master' into dev-2.0 2017-06-23 13:15:44 +02:00
Harsh Agarwal 16867c89a7 implement label_join issue 1147 (#2806)
Replace OptionalArgs int with Variadic int.
2017-06-16 14:51:22 +01:00
Brian Brazil 220e78b9c3 Consider a series stale after 4.1 intervals with no data.
To cover the cases where stale markers may not be available,
we need to infer the interval and mark series stale based on that.
As we're lacking stale markers this is less accurate, however
it should be good enough for these cases.

We need 4 intervals as if say we had data at t=0 and t=10,
coming via federation. The next data point should be at t=20 however it
could take up to t=30 for it actually to be ingested, t=40 for it to be
scraped via federation and t=50 for it to be ingested.
We then add 10% on to that for slack, as we do elsewhere.
2017-05-24 14:27:17 +01:00
Brian Brazil 80b40e6d91 Add initial staleness handing to promql.
For instant vectors, if "stale" is the newest sample
ignore the timeseries.

For range vectors, filter out "stale" samples.

Make it possible to inject "stale" samples in promql tests.
2017-05-16 18:33:51 +01:00
Brian Brazil 517b81f927 Add timestamp() function.
Make the timestamp of instant vectors be the timestamp of the sample
rather than the evaluation. We were not using this anywhere, so this is
safe.

Add a function to return the timestamp of samples in an instant vector.

Fixes #1557
2017-05-12 12:00:31 +01:00
Jack Neely 896f951e68 Force buckets in a histogram to be monotonic for quantile estimation (#2610)
* Force buckets in a histogram to be monotonic for quantile estimation

The assumption that bucket counts increase monotonically with increasing
upperBound may be violated during:

  * Recording rule evaluation of histogram_quantile, especially when rate()
     has been applied to the underlying bucket timeseries.
  * Evaluation of histogram_quantile computed over federated bucket
     timeseries, especially when rate() has been applied

This is because scraped data is not made available to RR evalution or
federation atomically, so some buckets are computed with data from the N
most recent scrapes, but the other buckets are missing the most recent
observations.

Monotonicity is usually guaranteed because if a bucket with upper bound
u1 has count c1, then any bucket with a higher upper bound u > u1 must
have counted all c1 observations and perhaps more, so that c  >= c1.

Randomly interspersed partial sampling breaks that guarantee, and rate()
exacerbates it. Specifically, suppose bucket le=1000 has a count of 10 from
4 samples but the bucket with le=2000 has a count of 7, from 3 samples. The
monotonicity is broken. It is exacerbated by rate() because under normal
operation, cumulative counting of buckets will cause the bucket counts to
diverge such that small differences from missing samples are not a problem.
rate() removes this divergence.)

bucketQuantile depends on that monotonicity to do a binary search for the
bucket with the qth percentile count, so breaking the monotonicity
guarantee causes bucketQuantile() to return undefined (nonsense) results.

As a somewhat hacky solution until the Prometheus project is ready to
accept the changes required to make scrapes atomic, we calculate the
"envelope" of the histogram buckets, essentially removing any decreases
in the count between successive buckets.

* Fix up comment docs for ensureMonotonic

* ensureMonotonic: Use switch statement

Use switch statement rather than if/else for better readability.
Process the most frequent cases first.
2017-04-14 16:21:49 +02:00