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diff --git a/contrib/scalar/README.md b/contrib/scalar/README.md new file mode 100644 index 0000000000..634b5771ed --- /dev/null +++ b/contrib/scalar/README.md @@ -0,0 +1,82 @@ +# Scalar - an opinionated repository management tool + +Scalar is an add-on to Git that helps users take advantage of advanced +performance features in Git. Originally implemented in C# using .NET Core, +based on the learnings from the VFS for Git project, most of the techniques +developed by the Scalar project have been integrated into core Git already: + +* partial clone, +* commit graphs, +* multi-pack index, +* sparse checkout (cone mode), +* scheduled background maintenance, +* etc + +This directory contains the remaining parts of Scalar that are not (yet) in +core Git. + +## Roadmap + +The idea is to populate this directory via incremental patch series and +eventually move to a top-level directory next to `gitk-git/` and to `git-gui/`. The +current plan involves the following patch series: + +- `scalar-the-beginning`: The initial patch series which sets up + `contrib/scalar/` and populates it with a minimal `scalar` command that + demonstrates the fundamental ideas. + +- `scalar-c-and-C`: The `scalar` command learns about two options that can be + specified before the command, `-c <key>=<value>` and `-C <directory>`. + +- `scalar-diagnose`: The `scalar` command is taught the `diagnose` subcommand. + +- `scalar-and-builtin-fsmonitor`: The built-in FSMonitor is enabled in `scalar + register` and in `scalar clone`, for an enormous performance boost when + working in large worktrees. This patch series necessarily depends on Jeff + Hostetler's FSMonitor patch series to be integrated into Git. + +- `scalar-gentler-config-locking`: Scalar enlistments are registered in the + user's Git config. This usually does not represent any problem because it is + rare for a user to register an enlistment. However, in Scalar's functional + tests, Scalar enlistments are created galore, and in parallel, which can lead + to lock contention. This patch series works around that problem by re-trying + to lock the config file in a gentle fashion. + +- `scalar-extra-docs`: Add some extensive documentation that has been written + in the original Scalar project (all subject to discussion, of course). + +- `optionally-install-scalar`: Now that Scalar is feature (and documentation) + complete and is verified in CI builds, let's offer to install it. + +- `move-scalar-to-toplevel`: Now that Scalar is complete, let's move it next to + `gitk-git/` and to `git-gui/`, making it a top-level command. + +The following two patch series exist in Microsoft's fork of Git and are +publicly available. There is no current plan to upstream them, not because I +want to withhold these patches, but because I don't think the Git community is +interested in these patches. + +There are some interesting ideas there, but the implementation is too specific +to Azure Repos and/or VFS for Git to be of much help in general (and also: my +colleagues tried to upstream some patches already and the enthusiasm for +integrating things related to Azure Repos and VFS for Git can be summarized in +very, very few words). + +These still exist mainly because the GVFS protocol is what Azure Repos has +instead of partial clone, while Git is focused on improving partial clone: + +- `scalar-with-gvfs`: The primary purpose of this patch series is to support + existing Scalar users whose repositories are hosted in Azure Repos (which + does not support Git's partial clones, but supports its predecessor, the GVFS + protocol, which is used by Scalar to emulate the partial clone). + + Since the GVFS protocol will never be supported by core Git, this patch + series will remain in Microsoft's fork of Git. + +- `run-scalar-functional-tests`: The Scalar project developed a quite + comprehensive set of integration tests (or, "Functional Tests"). They are the + sole remaining part of the original C#-based Scalar project, and this patch + adds a GitHub workflow that runs them all. + + Since the tests partially depend on features that are only provided in the + `scalar-with-gvfs` patch series, this patch cannot be upstreamed. |