branching: merge stable into default

mercurial/helptext/rust.txt

@@ -0,0 +1,94 b''
+Mercurial can be augmented with Rust extensions for speeding up certain
+operations.
+
+Compatibility
+=============
+
+Though the Rust extensions are only tested by the project under Linux, users of
+MacOS, FreeBSD and other UNIX-likes have been using the Rust extensions. Your
+mileage may vary, but by all means do give us feedback or signal your interest
+for better support.
+
+No Rust extensions are available for Windows at this time.
+
+Features
+========
+
+The following operations are sped up when using Rust:
+    - discovery of differences between repositories (pull/push)
+    - nodemap (see :hg:`help config.format.use-persistent-nodemap`)
+    - all commands using the dirstate (status, commit, diff, add, update, etc.)
+    - dirstate-v2 (see :hg:`help config.format.exp-rc-dirstate-v2`)
+    - iteration over ancestors in a graph
+
+More features are in the works, and improvements on the above listed are still
+in progress. For more experimental work see the "rhg" section.
+
+Checking for Rust
+=================
+
+You may already have the Rust extensions depending on how you install Mercurial.
+
+  $ hg debuginstall | grep -i rust
+  checking Rust extensions (installed)
+  checking module policy (rust+c-allow)
+
+If those lines don't even exist, you're using an old version of `hg` which does
+not have any Rust extensions yet.
+
+Installing
+==========
+
+You will need `cargo` to be in your `$PATH`. See the "MSRV" section for which
+version to use.
+
+Using pip
+---------
+
+Users of `pip` can install the Rust extensions with the following command:
+
+  $ pip install mercurial --global-option --rust --no-use-pep517
+
+`--no-use-pep517` is here to tell `pip` to preserve backwards compatibility with
+the legacy `setup.py` system. Mercurial has not yet migrated its complex setup
+to the new system, so we still need this to add compiled extensions.
+
+This might take a couple of minutes because you're compiling everything.
+
+See the "Checking for Rust" section to see if the install succeeded.
+
+From your distribution
+----------------------
+
+Some distributions are shipping Mercurial with Rust extensions enabled and
+pre-compiled (meaning you won't have to install `cargo`), or allow you to
+specify an install flag. Check with your specific distribution for how to do
+that, or ask their team to add support for hg+Rust!
+
+From source
+-----------
+
+Please refer to the `rust/README.rst` file in the Mercurial repository for
+instructions on how to install from source.
+
+MSRV
+====
+
+The minimum supported Rust version is currently 1.48.0. The project's policy is
+to follow the version from Debian stable, to make the distributions' job easier.
+
+rhg
+===
+
+There exists an experimental pure-Rust version of Mercurial called `rhg` with a
+fallback mechanism for unsupported invocations. It allows for much faster
+execution of certain commands while adding no discernable overhead for the rest.
+
+The only way of trying it out is by building it from source. Please refer to
+`rust/README.rst` in the Mercurial repository.
+
+Contributing
+============
+
+If you would like to help the Rust endeavor, please refer to `rust/README.rst`
+in the Mercurial repository.

.hgsigs

@@ -220,3 +220,4 b' 750920b18aaaddd654756be40dec59d90f2643be'
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.hgtags

@@ -233,3 +233,4 b' 750920b18aaaddd654756be40dec59d90f2643be'
 6ee0244fc1cf889ae543d2ce0ec45201ae0be6e1 5.9.3
 a44bb185f6bdbecc754996d8386722e2f0123b0a 6.0rc0
 5d08b289e2e526259d7d5ea32b70fe76d5b327d7 6.0
+799fdf4cca80cb9ae40537a90995e6bd163ebc0b 6.0.1

mercurial/help.py

@@ -484,6 +484,15 b' helptable = sorted('
             TOPIC_CATEGORY_IDS,
         ),
         (
+            [
+                b'rust',
+                b'rustext',
+            ],
+            _(b'Rust in Mercurial'),
+            loaddoc(b'rust'),
+            TOPIC_CATEGORY_CONFIG,
+        ),
+        (
             [b'filesets', b'fileset'],
             _(b"Specifying File Sets"),
             loaddoc(b'filesets'),

mercurial/helptext/config.txt

@@ -915,29 +915,60 b' https://www.mercurial-scm.org/wiki/Missi'
 
     Enabled by default.
 
+``exp-rc-dirstate-v2``
+    Enable or disable the experimental "dirstate-v2" feature. The dirstate
+    functionality is shared by all commands interacting with the working copy.
+    The new version is more robust, faster and stores more information.
+
+    The performance-improving version of this feature is currently only
+    implemented in Rust (see :hg:`help rust`), so people not using a version of
+    Mercurial compiled with the Rust parts might actually suffer some slowdown.
+    For this reason, such versions will by default refuse to access repositories
+    with "dirstate-v2" enabled.
+
+    This behavior can be adjusted via configuration: check
+    :hg:`help config.storage.dirstate-v2.slow-path` for details.
+
+    Repositories with this on-disk format require Mercurial 6.0 or above.
+
+    By default this format variant is disabled if the fast implementation is not
+    available, and enabled by default if the fast implementation is available.
+
+    To accomodate installations of Mercurial without the fast implementation,
+    you can downgrade your repository. To do so run the following command:
+
+    $ hg debugupgraderepo \
+          --run \
+          --config format.exp-rc-dirstate-v2=False \
+          --config storage.dirstate-v2.slow-path=allow
+
+    For a more comprehensive guide, see :hg:`help internals.dirstate-v2`.
+
 ``use-persistent-nodemap``
     Enable or disable the "persistent-nodemap" feature which improves
-    performance if the rust extensions are available.
-
-    The "persistence-nodemap" persist the "node -> rev" on disk removing the
+    performance if the Rust extensions are available.
+
+    The "persistent-nodemap" persist the "node -> rev" on disk removing the
     need to dynamically build that mapping for each Mercurial invocation. This
-    significantly reduce the startup cost of various local and server-side
-    operation for larger repository.
-
-    The performance improving version of this feature is currently only
-    implemented in Rust, so people not using a version of Mercurial compiled
-    with the Rust part  might actually suffer some slowdown. For this reason,
-    Such version will by default refuse to access such repositories. That
-    behavior can be controlled by configuration. Check
+    significantly reduces the startup cost of various local and server-side
+    operation for larger repositories.
+
+    The performance-improving version of this feature is currently only
+    implemented in Rust (see :hg:`help rust`), so people not using a version of
+    Mercurial compiled with the Rust parts might actually suffer some slowdown.
+    For this reason, such versions will by default refuse to access repositories
+    with "persistent-nodemap".
+
+    This behavior can be adjusted via configuration: check
     :hg:`help config.storage.revlog.persistent-nodemap.slow-path` for details.
 
-    Repository with this on-disk format require Mercurial version 5.4 or above.
-
-    By default this format variant is disabled if fast implementation is not
-    available and enabled by default if the fast implementation is available.
-
-    To accomodate install of Mercurial without the fast implementation you can
-    downgrade your repository. To do so run the following command:
+    Repositories with this on-disk format require Mercurial 5.4 or above.
+
+    By default this format variant is disabled if the fast implementation is not
+    available, and enabled by default if the fast implementation is available.
+
+    To accomodate installations of Mercurial without the fast implementation,
+    you can downgrade your repository. To do so run the following command:
 
     $ hg debugupgraderepo \
           --run \

rust/README.rst

@@ -6,15 +6,18 b' This directory contains various Rust cod'
 Rust is not required to use (or build) Mercurial, but using it
 improves performance in some areas.
 
-There are currently three independent rust projects:
-- chg. An implementation of chg, in rust instead of C.
-- hgcli. A project that provide a (mostly) self-contained "hg" binary,
+There are currently four independent Rust projects:
+- chg. An implementation of chg, in Rust instead of C.
+- hgcli. A project that provides a (mostly) self-contained "hg" binary,
   for ease of deployment and a bit of speed, using PyOxidizer. See
   hgcli/README.md.
 - hg-core (and hg-cpython): implementation of some
-  functionality of mercurial in rust, e.g. ancestry computations in
+  functionality of mercurial in Rust, e.g. ancestry computations in
   revision graphs, status or pull discovery. The top-level ``Cargo.toml`` file
   defines a workspace containing these crates.
+- rhg: a pure Rust implementation of Mercurial, with a fallback mechanism for
+  unsupported invocations. It reuses the logic `hg-core` but completely forgoes
+  interaction with Python. See `rust/rhg/README.md` for more details.
 
 Using Rust code
 ===============

tests/test-globalopts.t

@@ -414,6 +414,7 b' Testing -h/--help:'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   
@@ -548,6 +549,7 b' Testing -h/--help:'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   

tests/test-help-hide.t

@@ -113,6 +113,7 b' Test hiding some commands (which also ha'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   
@@ -251,6 +252,7 b' Test hiding some topics.'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   

tests/test-help.t

@@ -165,6 +165,7 b' the extension is unknown.'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   
@@ -295,6 +296,7 b' the extension is unknown.'
    hgweb         Configuring hgweb
    merge-tools   Merge Tools
    pager         Pager Support
+   rust          Rust in Mercurial
   
   Concepts:
   
@@ -1595,6 +1597,8 b' Separate sections from subsections'
   
       "usefncache"
   
+      "exp-rc-dirstate-v2"
+  
       "use-persistent-nodemap"
   
       "use-share-safe"
@@ -2425,6 +2429,13 b' Dish up an empty repo; serve it cold.'
   Specifying Revisions
   </td></tr>
   <tr><td>
+  <a href="/help/rust">
+  rust
+  </a>
+  </td><td>
+  Rust in Mercurial
+  </td></tr>
+  <tr><td>
   <a href="/help/scripting">
   scripting
   </a>

tests/test-hgweb-json.t

@@ -2324,6 +2324,10 b' help/ shows help topics'
         "topic": "revisions"
       },
       {
+        "summary": "Rust in Mercurial",
+        "topic": "rust"
+      },
+      {
         "summary": "Using Mercurial from scripts and automation",
         "topic": "scripting"
       },