go-billy afero wrapper

[Maldris]

As a bit of a test as one of my projects uses spf13/afero for all other disk operations I implemented the go-billy interface as a wrapper for afero for use in go-git.

https://github.com/Maldris/go-billy-afero

This was done as a quick and dirty implementation to test the concept, but as part of it, I have gotten optional support for Symlink and ReadLink merged into afero.

To revisit the idea and look at potentially cleaning it up for actual use, I would appreciate some feedback to see what needs to be done, and if this could be imported as a new filesystem option.

My main concern for support is the file Lock and Unlock methods, which do not have equivalents in afero. To control the behaviour within memory I've provided a mutex, however if multiple instances are created in different processes, or multiple applications try to access the same file, this is an inadequate solution, requiring additional application level logic.

[gebv]

As far as I understood go-git uses go-billy only for git worktree (like snapshots).
And go-git not works in parallel with FS. Then it is not required mutexes on files? Can only be one mutex for all worktree - lock if worktree is modificatios. But I think it's application layer.

The core message - required mutex on files for go-git for worktree? Please advice

[smola]

@gebv go-git uses go-billy for all filesystem operations, including everything in the GIT_DIR (.git), not just the worktree.