Commit Graph

33 Commits (d3dfe486fc99d0a96f89c87225c871685765f967)

Author SHA1 Message Date
Marc Tudurí 78c5ce3196
Drop old inmemory samples (#13002)
* Drop old inmemory samples

Co-authored-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Avoid copying timeseries when the feature is disabled

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Run gofmt

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Clarify docs

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Add more logging info

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Remove loggers

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* optimize function and add tests

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Simplify filter

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* rename var

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Update help info from metrics

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* use metrics to keep track of drop elements during buildWriteRequest

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* rename var in tests

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* pass time.Now as parameter

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Change buildwriterequest during retries

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Revert "Remove loggers"

This reverts commit 54f91dfcae20488944162335ab4ad8be459df1ab.

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* use log level debug for loggers

Signed-off-by: Marc Tuduri <marctc@protonmail.com>

* Fix linter

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Remove noisy debug-level logs; add 'reason' label to drop metrics

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Remove accidentally committed files

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Propagate logger to buildWriteRequest to log dropped data

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Fix docs comment

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Make drop reason more specific

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Remove unnecessary pass of logger

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Use snake_case for reason label

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Fix dropped samples metric

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

---------

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Signed-off-by: Marc Tuduri <marctc@protonmail.com>
Signed-off-by: Paschalis Tsilias <tpaschalis@users.noreply.github.com>
Co-authored-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>
Co-authored-by: Paschalis Tsilias <tpaschalis@users.noreply.github.com>
2024-01-05 10:40:30 -08:00
Arthur Silva Sens 5082655392
Append Created Timestamps (#12733)
* Append created timestamps.

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Log when created timestamps are ignored

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Proposed changes to Append CT PR.

Changes:

* Changed textparse Parser interface for consistency and robustness.
* Changed CT interface to be more explicit and handle validation.
* Simplified test, change scrapeManager to allow testability.
* Added TODOs.

Signed-off-by: bwplotka <bwplotka@gmail.com>

* Updates.

Signed-off-by: bwplotka <bwplotka@gmail.com>

* Addressed comments.

Signed-off-by: bwplotka <bwplotka@gmail.com>

* Refactor head_appender test

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Fix linter issues

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Use model.Sample in head appender test

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

---------

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>
Signed-off-by: bwplotka <bwplotka@gmail.com>
Co-authored-by: bwplotka <bwplotka@gmail.com>
2023-12-11 08:43:42 +00:00
Filip Petkovski 10a82f87fd
Enable reusing memory when converting between histogram types
The 'ToFloat' method on integer histograms currently allocates new memory
each time it is called.

This commit adds an optional *FloatHistogram parameter that can be used
to reuse span and bucket slices. It is up to the caller to make sure the
input float histogram is not used anymore after the call.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>
2023-12-08 10:22:59 +01:00
Matthieu MOREL 9c4782f1cc
golangci-lint: enable testifylint linter (#13254)
Signed-off-by: Matthieu MOREL <matthieu.morel35@gmail.com>
2023-12-07 11:35:01 +00:00
Julien Pivotto 986fde06b2
Merge pull request #11688 from damnever/fix/datamodelvalidation-remotewriteapi
Validate the metric names and labels in the remote write handler
2023-07-04 13:52:02 +02:00
Jeanette Tan e9a1e26ab7 Perform integer/float histogram type checking on conversions, and use a consistent method for determining integer vs float histogram
Signed-off-by: Jeanette Tan <jeanette.tan@grafana.com>
2023-04-22 02:27:15 +08:00
beorn7 c3c7d44d84 lint: Adjust to the lint warnings raised by current versions of golint-ci
We haven't updated golint-ci in our CI yet, but this commit prepares
for that.

There are a lot of new warnings, and it is mostly because the "revive"
linter got updated. I agree with most of the new warnings, mostly
around not naming unused function parameters (although it is justified
in some cases for documentation purposes – while things like mocks are
a good example where not naming the parameter is clearer).

I'm pretty upset about the "empty block" warning to include `for`
loops. It's such a common pattern to do something in the head of the
`for` loop and then have an empty block. There is still an open issue
about this: https://github.com/mgechev/revive/issues/810 I have
disabled "revive" altogether in files where empty blocks are used
excessively, and I have made the effort to add individual
`// nolint:revive` where empty blocks are used just once or twice.
It's borderline noisy, though, but let's go with it for now.

I should mention that none of the "empty block" warnings for `for`
loop bodies were legitimate.

Signed-off-by: beorn7 <beorn@grafana.com>
2023-04-19 17:10:10 +02:00
Justin Lei 83f43982c9 Add support for native histograms to concreteSeriesIterator
Signed-off-by: Justin Lei <justin.lei@grafana.com>
2023-04-06 09:54:15 -07:00
Xiaochao Dong (@damnever) 2b7202c4cc Validate the metric names and labels in the remote write handler
Signed-off-by: Xiaochao Dong (@damnever) <the.xcdong@gmail.com>
2023-04-05 19:09:05 +08:00
Jesus Vazquez 136956cca4
Attempt to append ooo sample at the end first (#11615)
This is an optimization on the existing append in OOOChunk.

What we've been doing so far is find the place inside the out-of-order
slice where the new sample should go in and then place it there and move
any samples to the right if necessary. This is OK but requires a binary
search every time the slice is bigger than 0.

The optimization is opinionated and suggests that although out-of-order
samples can be out-of-order amongst themselves they'll probably be in
order thus we can probably optimistically append at the end and if not
do the binary search.

OOOChunks are capped to 30 samples by default so this is a small
optimization but everything adds up, specially if you handle many active
timeseries with out-of-order samples.

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>
Signed-off-by: Jesus Vazquez <jesusvazquez@users.noreply.github.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
2023-01-13 19:00:50 +05:30
Marc Tudurí 721f33dbb0
histograms: Add remote-write support for Float Histograms (#11817)
* adapt code.go and write_handler.go to support float histograms
* adapt watcher.go to support float histograms
* wip adapt queue_manager.go to support float histograms
* address comments for metrics in queue_manager.go
* set test cases for queue manager
* use same counts for histograms and float histograms
* refactor createHistograms tests
* fix float histograms ref in watcher_test.go
* address PR comments

Signed-off-by: Marc Tuduri <marctc@protonmail.com>
2023-01-13 16:39:20 +05:30
Marc Tudurí 9474610baf
Support FloatHistogram in TSDB (#11522)
Extends Appender.AppendHistogram function to accept the FloatHistogram. TSDB supports appending, querying, WAL replay, for this new type of histogram.

Signed-off-by: Marc Tudurí <marctc@protonmail.com>
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
2022-12-28 14:25:07 +05:30
beorn7 c9fd3c235d Merge branch 'main' into sparsehistogram 2022-08-10 17:54:37 +02:00
Levi Harrison 0db6b072bc
Export `histogramToHistogramProto()` (#11046)
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2022-07-21 10:12:50 -04:00
Paschalis Tsilias d1122e0743
Introduce TSDB changes for appending metadata to the WAL (#10972)
* Append metadata to the WAL

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Remove extra whitespace; Reword some docstrings and comments

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Use RLock() for hasNewMetadata check

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Use single byte for metric type in RefMetadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Update proposed WAL format for single-byte type metadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Implementa MetadataAppender interface for the Agent

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Address first round of review comments

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Amend description of metadata in wal.md

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Correct key used to retrieve metadata from cache

When we're setting metadata entries in the scrapeCace, we're using the
p.Help(), p.Unit(), p.Type() helpers, which retrieve the series name and
use it as the cache key. When checking for cache entries though, we used
p.Series() as the key, which included the metric name _with_ its labels.
That meant that we were never actually hitting the cache. We're fixing
this by utiling the __name__ internal label for correctly getting the
cache entries after they've been set by setHelp(), setType() or
setUnit().

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Put feature behind a feature flag

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix AppendMetadata docstring

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Reorder WAL format document

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Change error message of AppendMetadata; Fix access of s.meta in AppendMetadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Reuse temporary buffer in Metadata encoder

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Only keep latest metadata for each refID during checkpointing

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix test that's referencing decoding metadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Avoid creating metadata block if no new metadata are present

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Add tests for corrupt metadata block and relevant record type

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix CR comments

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Extract logic about changing metadata in an anonymous function

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Implement new proposed WAL format and amend relevant tests

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Use 'const' for metadata field names

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Apply metadata to head memSeries in Commit, not in AppendMetadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Add docstring and rename extracted helper in scrape.go

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Add tests for tsdb-related cases

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix linter issues vol1

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix linter issues vol2

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix Windows test by closing WAL reader files

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Use switch instead of two if statements in metadata decoding

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix review comments around TestMetadata* tests

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Add code for replaying WAL; test correctness of in-memory data after a replay

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Remove scrape-loop related code from PR

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Address first round of comments

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Simplify tests by sorting slices before comparison

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix test to use separate transactions

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Empty out buffer and record slices after encoding latest metadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix linting issue

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Update calculation for DroppedMetadata metric

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Rename MetadataAppender interface and AppendMetadata method to MetadataUpdater/UpdateMetadata

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Reuse buffer when encoding latest metadata for each series

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Fix review comments; Check all returned error values using two helpers

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Simplify use of helpers

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>

* Satisfy linter

Signed-off-by: Paschalis Tsilias <paschalist0@gmail.com>
2022-07-19 10:58:52 +02:00
beorn7 87351f2318 prompb: Modify layout of histograms
Note: This is deliberately an incompatible change. Since we have never
used histograms in remote read/write yet, there is no point in keeping
compatibility. This _is_, however, compatible to the state in the main
branch.

This commit flattens the bucket message into top-level fields. This
has the disadvantage of now having two triples of fields prefixed with
`negative_...` or `positive_...`. However, with this structure, we
save one tag on the wire. And, perhaps more importantly, we mirror the
structure of the `histogram.Histogram` Go type.

This commit also adjusts `repeated` fields to use names in the plural
form, as it is also the case for the fields that already existed.

This also adds a doc comment to `HistogramProtoToHistogram` and
changes its return type to a pointer (which is more convenient and
probably more efficient).

Signed-off-by: beorn7 <beorn@grafana.com>
2022-07-14 17:47:17 +02:00
Levi Harrison 08f3ddb864
Sparse histogram remote-write support (#11001) 2022-07-14 09:13:12 -04:00
beorn7 3bc711e333 Merge branch 'main' into sparsehistogram 2022-05-04 13:37:13 +02:00
Matthieu MOREL e2ede285a2
refactor: move from io/ioutil to io and os packages (#10528)
* refactor: move from io/ioutil to io and os packages
* use fs.DirEntry instead of os.FileInfo after os.ReadDir

Signed-off-by: MOREL Matthieu <matthieu.morel@cnp.fr>
2022-04-27 11:24:36 +02:00
beorn7 5d4db805ac Merge branch 'main' into sparsehistogram 2021-11-17 19:57:31 +01:00
beorn7 4c28d9fac7 Move to histogram.Histogram pointers
This is to avoid copying the many fields of a histogram.Histogram all
the time.

This also fixes a bunch of formerly broken tests.

Signed-off-by: beorn7 <beorn@grafana.com>
2021-11-12 23:17:35 +01:00
beorn7 c954cd9d1d Move packages out of deprecated pkg directory
This creates a new `model` directory and moves all data-model related
packages over there:
  exemplar labels relabel rulefmt textparse timestamp value

All the others are more or less utilities and have been moved to `util`:
  gate logging modetimevfs pool runtime

Signed-off-by: beorn7 <beorn@grafana.com>
2021-11-09 08:03:10 +01:00
Dieter Plaetinck cda025b5b5
TSDB: demistify SeriesRefs and ChunkRefs (#9536)
* TSDB: demistify seriesRefs and ChunkRefs

The TSDB package contains many types of series and chunk references,
all shrouded in uint types.  Often the same uint value may
actually mean one of different types, in non-obvious ways.

This PR aims to clarify the code and help navigating to relevant docs,
usage, etc much quicker.

Concretely:

* Use appropriately named types and document their semantics and
  relations.
* Make multiplexing and demuxing of types explicit
  (on the boundaries between concrete implementations and generic
  interfaces).
* Casting between different types should be free.  None of the changes
  should have any impact on how the code runs.

TODO: Implement BlockSeriesRef where appropriate (for a future PR)

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* agent: demistify seriesRefs and ChunkRefs

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>
2021-11-06 15:40:04 +05:30
Bryan Boreham 5afa606ecb
Remote-write: reuse memory for marshalling (#9412)
By holding a `proto.Buffer` per shard and passing it down to where
marshalling is done, we avoid creating a lot of garbage.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
2021-10-29 14:44:40 -07:00
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
beorn7 fd5ea4e0b5 Merge branch 'main' into sparsehistogram 2021-10-07 23:16:42 +02:00
Serge Catudal d77c985f8c
Add initial support for exemplar to the remote write receiver endpoint (#9319)
* Add initial support for exemplar to the remote write receiver endpoint

Signed-off-by: Serge Catudal <serge.catudal@gmail.com>

* Update storage remote write handler tests with exemplars

Signed-off-by: Serge Catudal <serge.catudal@gmail.com>

* Update remote write handler in order to have a distinct checkAppendExemplarError function from scrape

Signed-off-by: Serge Catudal <serge.catudal@gmail.com>
2021-09-21 14:53:27 -06:00
Ganesh Vernekar 04ad56d9b8
Append sparse histograms into the Head block (#9013)
* Append sparse histograms into the Head block

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

* Add AtHistogram() to Iterator interface. Make HistoChunk conform to Chunk interface.

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2021-06-29 20:08:46 +05:30
Ganesh Vernekar 64bea6999e
HistogramAppender interface for sparse histograms (#9007)
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2021-06-28 20:30:55 +05:30
Levi Harrison b5f6f8fb36 Switched to go-kit/log
Signed-off-by: Levi Harrison <git@leviharrison.dev>
2021-06-11 12:28:36 -04:00
Callum Styan 289ba11b79
Add circular in-memory exemplars storage (#6635)
* Add circular in-memory exemplars storage

Signed-off-by: Callum Styan <callumstyan@gmail.com>
Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
Signed-off-by: Martin Disibio <mdisibio@gmail.com>

Co-authored-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
Co-authored-by: Tom Wilkie <tom.wilkie@gmail.com>
Co-authored-by: Martin Disibio <mdisibio@gmail.com>

* Fix some comments, clean up exemplar metrics struct and exemplar tests.

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

* Fix exemplar query api null vs empty array issue.

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

Co-authored-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
Co-authored-by: Tom Wilkie <tom.wilkie@gmail.com>
Co-authored-by: Martin Disibio <mdisibio@gmail.com>
2021-03-16 15:17:45 +05:30
Tom Wilkie 7369561305
Combine Appender.Add and AddFast into a single Append method. (#8489)
This moves the label lookup into TSDB, whilst still keeping the cached-ref optimisation for repeated Appends.

This makes the API easier to consume and implement.  In particular this change is motivated by the scrape-time-aggregation work, which I don't think is possible to implement without it as it needs access to label values.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>
2021-02-18 17:37:00 +05:30
Tom Wilkie d479151f1f Various enhancements and refactorings for remote write receiver:
- Remove unrelated changes
- Refactor code out of the API module - that is already getting pretty crowded.
- Don't track reference for AddFast in remote write.  This has the potential to consume unlimited server-side memory if a malicious client pushes a different label set for every series.  For now, its easier and safer to always use the 'slow' path.
- Return 400 on out of order samples.
- Use remote.DecodeWriteRequest in the remote write adapters.
- Put this behing the 'remote-write-server' feature flag
- Add some (very) basic docs.
- Used named return & add test for commit error propagation

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>
2021-02-08 20:41:23 +00:00