Unfortunately, we can't completely remove the ctx from git.Repository,
because the CatFileBatch still heavily depends on a parent context.
If we remove the Repository ctx, the CatFileBatch will become a mess and
create a lot of unnecessary git processes.
http://localhost:3000/-/admin/monitor/perftrace
* Before: open a repo home, dozens of git processes (duplicate cat-file)
* After: only a few (no duplicate cat-file)
Regression of the ctx removal from "git.Repository" struct (the old code
was already wrong and can still cause 500, the "ctx removal" just makes
the problem easier to reproduce).
Merge duplicate code.
Reviewd by codex: no actionable findings.
1. Storing "ctx" in a long-living object is wrong
2. Make the commit & tree cacheable (for the future performance
optimization)
3. Also fix some bad designs like `// FIXME: bad design, this field can
be nil if the commit is from "last commit cache"`
ref:
* #33893
wxiaoguang