Performance improvements - profiling and simple caching

[erikbra]

Used the profiler to find hotspots, most were in Regex matching of
commit messages. Added simple static cache to IncrementStrategyFinder.

Runtime halved on medium-sized git codebase (~3 years of history). Same on GitVersion's own codebase.

There are several issues raised concerning performance issues, e.g. #1208, #1066, and more. I am also experiencing issues with a large-ish codebase, so I started looking into it. This one is a low-hanging fruit. Hopefully more to come (e.g. I also suspect that #360 has introduced rather heavy performance issues, but I'll look further into this in a separate PR)

Medium-sized codebase:

before:

       61.21 real        58.71 user         2.26 sys

after:

       29.75 real        29.63 user         0.18 sys

GitVersion codebase:

before:

real	0m2.364s
user	0m2.113s
sys	0m0.262s

after:

real	0m0.968s
user	0m0.869s
sys	0m0.097s

[asbjornu]

@erikbra, thank you so much for your time and effort looking into this! Highly appreciated! The AZDO build is failing, though – would you care to look into why?

[erikbra]

Really strange. The build fails only on Linux, and the error is not anywhere near where I've touched:

Mocks/MockRepository.cs(214,16): error CS0104: 'Index' is an ambiguous reference between 'LibGit2Sharp.Index' and 'System.Index' [/home/vsts/work/1/s/src/GitVersionCore.Tests/GitVersionCore.Tests.csproj]
Mocks/MockRepository.cs(7,35): error CS0738: 'MockRepository' does not implement interface member 'IRepository.Index'. 'MockRepository.Index' cannot implement 'IRepository.Index' because it does not have the matching return type of 'Index'. [/home/vsts/work/1/s/src/GitVersionCore.Tests/GitVersionCore.Tests.csproj]

I did try to fix it, even though it's unrelated. Don't have a linux box available right here, and it built on my Mac even before the change. Buut let's see if I nailed it anyway ;)

[erikbra]

Looks like the build error was introduced in master a couple of commits before my PR. But, nevermind, I fixed it in the PR :)

[asbjornu]

Fantastic! Thank you so much! 🙏

[erikbra]

Nice build pipeline in Azure DevOps btw... where does the "Release" task put stuff? Is it possible for me to use a pre-release of the GitVersion task in our own DevOps builds? Or is that a manual process? I'm thinking of using something like this in my .yml?

    - task: [email protected]+77
      displayName: Get nuget version
      inputs:
        runtime: 'core'

[arturcic]

You have to install https://marketplace.visualstudio.com/items?itemName=gittools.gitversion-preview into your organization in order to use it. This is the preview version we publish on non release version, basically on every not tagged commit

[erikbra]

Thanks, @arturcic . Worked like a charm. And run time on all our builds' GitVersion step is now down from 60-70s to ~20s. Happy, happy!!