Improve the commit history browsing performances

[flelli]

Method JGitRepository.walkHistory() is slow and thatàs probably due to the retrieval of all tags for each commit.
Its performances must be improved.

[sschuberth]

I'm also suffering from nyx --preset=simple infer to be insanely slow (when being mean and trying on a repository without any version tags).

But I'm wondering whether really JGitRepository.walkHistory() is the culprit, as I though the relevant code is not

nyx/modules/java/main/src/main/java/com/mooltiverse/oss/nyx/command/Infer.java

Line 232 in 96d0815

repository().walkHistory(null, null, c -> {

but

nyx/modules/go/nyx/command/infer.go

Line 227 in 96d0815

(*c.Repository()).WalkHistory(nil, nil, func(cc gitent.Commit) bool {

for the CLI tool.

Anyway, I believe the problem could be rather the algorithm. Instead of walking all history (as it seems), wouldn't it make more sense to determine only the latest tag (if any) on the current branch, any only from there walk up the history to determine the version increment based on conventional commits?

[flelli]

Hi @sschuberth ,

it's very likely, as you say, the issue is in the algorithm and ideas are welcome, considering that:

• we need to start to walk the history from the latest commit, not by the latest tag, because last commits (up to the latest tags) are exactly what we need to compute version increments
• the first parent criteria is required to comply with the history of significant commits and prevents us from using commits selected by any criteria other than sequential (i.e. browsing by tags would miss a bunch of significant commits and also potentially drive the browsing out of the range of commits visible starting from HEAD)

When I first noticed this issue I only had the Java implementation, no Go yet, so Java is affected for sure. Nonetheless, as you pointed out, the issue is the algorithm, regardless the language.

[sschuberth]

For testing, I was trying Git.SemVersioning.Gradle on the same project, which was much faster. Maybe we could borrow some ideas from https://github.com/jmongard/Git.SemVersioning.Gradle/blob/master/src/main/kotlin/git/semver/plugin/semver/VersionFinder.kt?

[sschuberth]

And for the Go version, maybe compare with https://github.com/PSanetra/git-semver.