Programmatically do "Git blame -w" in C#

Question

I need to programmatically get the last author of a specific line in the Git history with C#. I tried using libgit2sharp :

var repo = new LibGit2Sharp.Repository(gitRepositoryPath);
string relativePath = MakeRelativeSimple(filename);
var blameHunks = repo.Blame(relativePath);
// next : find the hunk which overlap the desired line number

But this is the equivalent of the command

git blame <file>

And in fact I need

git blame -w <file> (to ignore whitespace when comparing)

Libgit2sharp do not set the -w switch and don't provide any parameter/option to set it. What are my options ? Do you know any other library compatible with the -w switch of the blame command ?

@Jeremy : not at all, I didn't know NGit. I spent so much time on this question that I prefered ask for feedback. — JYL, Apr 04 '16 at 12:12
Cool, this is a really good feature request for the LibGit2Sharp dev team :) If you ask them politely referencing a link to this Q, you might encourage one of the core team or a contributor to add it while this Q has an active bounty attached... Otherwise Evk should get it (+1). Fingers crossed that's enough to persuade because then you wouldn't need to rely on 2 libraries. — Jeremy Thompson, Apr 04 '16 at 12:18
@Jeremy : the feature request is already [here](https://github.com/libgit2/libgit2sharp/issues/1177) (since Aug 2015). — JYL, Apr 04 '16 at 19:43
The problem with lib2gitSharp is that it is using lib2git, which is "a portable, pure C implementation of the Git core methods provided as a re-entrant linkable library with a solid API, allowing you to write native speed custom Git applications in any language which supports C bindings." which doesn't have the whitespace option. It doesn't execute git, so you can add -w, it implements everything. I tried to implement it myself, but C code makes me dizzy. Probably you will have to do with NGIT. — Siderite Zackwehdex, Apr 08 '16 at 04:11

score 4 · Accepted Answer · answered Apr 06 '16 at 06:08

4

When I hit similar advanced scenarios where the git lib isn't cutting it, I just shell out using start process to the real git command line. It's not sexy, but it's mighty effective.

answered Apr 06 '16 at 06:08

robrich

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I though about that before, but I need to do this for about 2000 files in my solution, and feared on performance. I'll try it as a last resort. – JYL Apr 06 '16 at 13:22
In fact this way is really faster than using libGit2Sharp in my case. With a test repository of 818 files (4570 commits), with a blame on each file: using direct process : average of 181 ms. per blame ; using ligGit2Sharp : average of 1235 ms per blame. – JYL Apr 14 '16 at 13:50
necro posting because this is still the #1 hit for this question. It is now 2019 and the blame implementation in libgit2 is still an order of magnitude slower than command line git according to https://github.com/libgit2/libgit2/issues/3027 – Ammo Goettsch Apr 05 '20 at 23:24

score 3 · Answer 2 · answered Apr 04 '16 at 09:11

3

Maybe using NGIT library will help. That is direct (automatic) port of java JGIT library. Install via nuget package, then:

    static void Main() {
        var git = Git.Init().SetDirectory("C:\\MyGitRepo").Call();            
        string relativePath = "MyFolder/MyFile.cs";            
        var blameHunks = git.Blame().SetFilePath(relativePath).SetTextComparator(RawTextComparator.WS_IGNORE_ALL).Call();
        blameHunks.ComputeAll();
        var firstLineCommit = blameHunks.GetSourceCommit(0);
        // next : find the hunk which overlap the desired line number
        Console.ReadKey();
    }

Note SetTextComparator(RawTextComparator.WS_IGNORE_ALL) part.

answered Apr 04 '16 at 09:11

Evk

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Thanks for the answer, I'll try this the next week. – JYL Apr 04 '16 at 12:15
No way to make this working. Some commits are nice, and some others are just null. Especially when there are whitespace differences. I don't know if I have a wrong or missing option, or if it's just due to the outdated sources of ngit (compared to jgit). I give up, I'm going back to basics (robrich solution). – JYL Apr 11 '16 at 15:07
Nevertheless I give you the bounty because the answer is theoretically correct and is given with an appropriate code sample. Thanks. – JYL Apr 11 '16 at 15:13

score 1 · Answer 3 · answered Jan 07 '18 at 05:32

Unfortunately, libgit2sharp is too slow on extracting blames and using this feature is impractical in real scenarios. So, the best way I think is to employ a Powershell script to use the underlying superfast native git. And then redirect the result to your application.

git blame -l -e -c {commit-sha} -- "{file-path}" | where { $_ -match '(?<sha>\w{40})\s+\(<(?<email>[\w\.\-]+@[\w\-]+\.\w{2,3})>\s+(?<datetime>\d\d\d\d-\d\d-\d\d\s\d\d\:\d\d:\d\d\s-\d\d\d\d)\s+(?<lineNumber>\d+)\)\w*' } | 
foreach { new-object PSObject –prop @{  Email = $matches['email'];lineNumber = $matches['lineNumber'];dateTime = $matches['dateTime'];Sha = $matches['sha']}}

Programmatically do "Git blame -w" in C#

3 Answers3