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https://github.com/microsoft/scalar

Scalar: A set of tools and extensions for Git to allow very large monorepos to run on Git without a virtualization layer
https://github.com/microsoft/scalar

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Scalar: A set of tools and extensions for Git to allow very large monorepos to run on Git without a virtualization layer

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README 

        
![Scalar](Images/scalar-card.png)



## What is Scalar?



Scalar is a tool that helps Git scale to some of the largest Git repositories.

It achieves this by enabling some advanced Git features, such as:



* *Partial clone:* reduces time to get a working repository by not

  downloading all Git objects right away.



* *Background prefetch:* downloads Git object data from all remotes every

  hour, reducing the amount of time for foreground `git fetch` calls.



* *Sparse-checkout:* limits the size of your working directory.



* *File system monitor:* tracks the recently modified files and eliminates

  the need for Git to scan the entire worktree.



* *Commit-graph:* accelerates commit walks and reachability calculations,

   speeding up commands like `git log`.



* *Multi-pack-index:* enables fast object lookups across many pack-files.



* *Incremental repack:* Repacks the packed Git data into fewer pack-file

  without disrupting concurrent commands by using the multi-pack-index.



As new versions of Git are released, we update the list of features that

Scalar automatically configures. This reduces your effort to keep your

repositories as efficient as possible.



## Scalar has moved!



Through significant effort from our team, we have successfully transitioned

Scalar from a modified version of [VFS for Git][vfsforgit] into a thin shell

around core Git features. The Scalar executable has now been ported to be

included [in the `microsoft/git` fork][microsoft-git]. Please visit that

fork for all of your Scalar needs:



* Download [the latest `microsoft/git` release][releases].

* Read [the Scalar documentation][docs].

* Contribute changes [to the `scalar` CLI][scalar-cli].



### Why did Scalar move?



Scalar started as a modification of [VFS for Git][vfsforgit] to

create a working solution with a robust test suite in a short amount of

time. The goal was to depend more on features that exist within Git itself

instead of creating new functionality within this project. Since the start,

we have focused on this goal with efforts such as

[improving sparse-checkout performance in Git][sparse-checkout-blog],

[implementing background maintenance in Git][background-maintenance],

and [integrating the GVFS protocol into `microsoft/git`][remove-read-object]

which allowed us to [drop the `Scalar.Mount` process][remove-mount].

All of these changes reduced the size of the code in Scalar itself until

it could be replaced [with a small command-line interface][scalar-cli].



[sparse-checkout-blog]: https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/

[background-maintenance]: https://github.blog/2021-03-15-highlights-from-git-2-31/#introducing-git-maintenance

[remove-read-object]: https://github.com/microsoft/scalar/pull/122

[remove-mount]: https://github.com/microsoft/scalar/pull/222



Additional benefits to this change include making our release and

installation mechanism much simpler. Users now only need to install one

tool, not multiple, to take advantage of all of the benefits.



### What remains in this repository?



We are keeping the `microsoft/scalar` repository available since we have

linked to it and want to make sure those links continue to work. We

added pointers in several places to navigate readers to the `microsoft/git`

repository for the latest versions.



We also have a large set of functional tests that verify that Scalar

enlistments continue to work in a variety of advanced Git scenarios. These

tests are incredibly helpful as we advance features in `microsoft/git`, so

those tests remain in this repository. We run them as part of pull request

validation in `microsoft/git`, so no changes are made there without passing

this suite of tests.



### What if I already installed Scalar and want the new version?



We are working to ensure that users on the .NET version of Scalar have a

painless experience while changing to the new version.



* On Windows, users can [install `microsoft/git`][windows-install] and the

  installer will remove the .NET version and update any registered

  enlistments to work with the new version.



* On macOS, users should run `brew uninstall --cask scalar` or

  `brew uninstall --cask scalar-azrepos` depending on their version and

  then run `brew install --cask microsoft-git` to get the new version.

  At the moment, users on macOS will need to re-run `scalar register`

  on their enlistments to ensure they are registered for future upgrades.



* On Linux, there is no established uninstall mechanism, but the .NET

  version can be removed via `sudo rm -rf /usr/local/lib/scalar/`. Installing

  the new version will overwrite the `scalar` binary in `/usr/local/bin`.

  At the moment, users on Linux will need to re-run `scalar register`

  on their enlistments to ensure they are registered for future upgrades.



You can check if the new Scalar version is installed correctly by running

`scalar version` which should have the same output as `git version`.



## License



The Scalar source code in this repo is available under the MIT license. See [License.md](License.md).



## Code of Conduct



This project has adopted the [Microsoft Open Source Code of Conduct][conduct-code].

For more information see the [Code of Conduct FAQ][conduct-FAQ] or contact [[email protected]][conduct-email] with any additional questions or comments.



[vfsforgit]: https://github.com/microsoft/vfsforgit

[microsoft-git]: https://github.com/microsoft/git

[releases]: https://github.com/microsoft/git/releases

[windows-install]: https://github.com/microsoft/git#windows

[docs]: https://github.com/microsoft/git/blob/HEAD/contrib/scalar/docs/index.md

[scalar-cli]: https://github.com/microsoft/git/blob/HEAD/contrib/scalar/scalar.c

[conduct-code]: https://opensource.microsoft.com/codeofconduct/

[conduct-FAQ]: https://opensource.microsoft.com/codeofconduct/faq/

[conduct-email]: mailto:[email protected]