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1 | # Scalar - an opinionated repository management tool |
2 | ||
3 | Scalar is an add-on to Git that helps users take advantage of advanced | |
4 | performance features in Git. Originally implemented in C# using .NET Core, | |
5 | based on the learnings from the VFS for Git project, most of the techniques | |
6 | developed by the Scalar project have been integrated into core Git already: | |
7 | ||
8 | * partial clone, | |
9 | * commit graphs, | |
10 | * multi-pack index, | |
11 | * sparse checkout (cone mode), | |
12 | * scheduled background maintenance, | |
13 | * etc | |
14 | ||
15 | This directory contains the remaining parts of Scalar that are not (yet) in | |
16 | core Git. | |
17 | ||
18 | ## Roadmap | |
19 | ||
20 | The idea is to populate this directory via incremental patch series and | |
21 | eventually move to a top-level directory next to `gitk-git/` and to `git-gui/`. The | |
22 | current plan involves the following patch series: | |
23 | ||
24 | - `scalar-the-beginning`: The initial patch series which sets up | |
25 | `contrib/scalar/` and populates it with a minimal `scalar` command that | |
26 | demonstrates the fundamental ideas. | |
27 | ||
28 | - `scalar-c-and-C`: The `scalar` command learns about two options that can be | |
29 | specified before the command, `-c <key>=<value>` and `-C <directory>`. | |
30 | ||
31 | - `scalar-diagnose`: The `scalar` command is taught the `diagnose` subcommand. | |
32 | ||
33 | - `scalar-and-builtin-fsmonitor`: The built-in FSMonitor is enabled in `scalar | |
34 | register` and in `scalar clone`, for an enormous performance boost when | |
35 | working in large worktrees. This patch series necessarily depends on Jeff | |
36 | Hostetler's FSMonitor patch series to be integrated into Git. | |
37 | ||
38 | - `scalar-gentler-config-locking`: Scalar enlistments are registered in the | |
39 | user's Git config. This usually does not represent any problem because it is | |
40 | rare for a user to register an enlistment. However, in Scalar's functional | |
41 | tests, Scalar enlistments are created galore, and in parallel, which can lead | |
42 | to lock contention. This patch series works around that problem by re-trying | |
43 | to lock the config file in a gentle fashion. | |
44 | ||
45 | - `scalar-extra-docs`: Add some extensive documentation that has been written | |
46 | in the original Scalar project (all subject to discussion, of course). | |
47 | ||
48 | - `optionally-install-scalar`: Now that Scalar is feature (and documentation) | |
49 | complete and is verified in CI builds, let's offer to install it. | |
50 | ||
51 | - `move-scalar-to-toplevel`: Now that Scalar is complete, let's move it next to | |
52 | `gitk-git/` and to `git-gui/`, making it a top-level command. | |
53 | ||
54 | The following two patch series exist in Microsoft's fork of Git and are | |
55 | publicly available. There is no current plan to upstream them, not because I | |
56 | want to withhold these patches, but because I don't think the Git community is | |
57 | interested in these patches. | |
58 | ||
59 | There are some interesting ideas there, but the implementation is too specific | |
60 | to Azure Repos and/or VFS for Git to be of much help in general (and also: my | |
61 | colleagues tried to upstream some patches already and the enthusiasm for | |
62 | integrating things related to Azure Repos and VFS for Git can be summarized in | |
63 | very, very few words). | |
64 | ||
65 | These still exist mainly because the GVFS protocol is what Azure Repos has | |
66 | instead of partial clone, while Git is focused on improving partial clone: | |
67 | ||
68 | - `scalar-with-gvfs`: The primary purpose of this patch series is to support | |
69 | existing Scalar users whose repositories are hosted in Azure Repos (which | |
70 | does not support Git's partial clones, but supports its predecessor, the GVFS | |
71 | protocol, which is used by Scalar to emulate the partial clone). | |
72 | ||
73 | Since the GVFS protocol will never be supported by core Git, this patch | |
74 | series will remain in Microsoft's fork of Git. | |
75 | ||
76 | - `run-scalar-functional-tests`: The Scalar project developed a quite | |
77 | comprehensive set of integration tests (or, "Functional Tests"). They are the | |
78 | sole remaining part of the original C#-based Scalar project, and this patch | |
79 | adds a GitHub workflow that runs them all. | |
80 | ||
81 | Since the tests partially depend on features that are only provided in the | |
82 | `scalar-with-gvfs` patch series, this patch cannot be upstreamed. |