Follow-up to https://github.com/zed-industries/zed/pull/2777
Refs https://github.com/zed-industries/community/issues/1770
In this PR, I reworked the way that git statuses are retrieved. In a
huge repository like `WebKit`, the really slow part of computing a list
of git statuses is the *unstaged* portion of the diff. For the *staged*
diff, `git` can avoid comparing the contents of unchanged directories,
because the index contains hashes of every tree. But for the *unstaged*
portion, Git needs to compare every file in the worktree against the
index. In the common case, when there are no changes, it's enough to
check the `mtime` of every file (because the index stores the mtimes of
files when they are added). But this still requires an `lstat` call to
retrieve each file's metadata.
I realized that this is redundant work, because the worktree is
*already* calling `lstat` on every file, and caching their metadata. So
in this PR, I've changed the `Repository` API so that there are separate
methods for retrieving a file's *staged* and *unstaged* statuses. The
*staged* statuses are retrieved in one giant batch, like before, to
reduce our git calls (which also have an inherent cost). But the
`unstaged` statuses are retrieved one-by-one, after we load files'
mtimes. Often, all that's required is an index lookup, and an mtime
comparison.
With this optimization, it once again becomes pretty responsive to open
`WebKit` or `chromium` in Zed.
Release Notes:
- Optimized the loading of project file when working in very large git
repositories
a01d973477