rust/README.rst
author Augie Fackler <augie@google.com>
Wed, 03 Apr 2019 11:46:29 -0400
changeset 42054 399ed3e86a49
parent 35569 964212780daf
child 44114 8a3b045d9086
permissions -rw-r--r--
py2exe: add workaround to allow bundling of hgext3rd.* extensions py2exe doesn't know how to handle namespace packages *at all*, so it treats them like normal packages. As a result, if we try and bundle hgext3rd.evolve in a py2exe build, it won't work if we install evolve into the virtualenv. In order to work around this, tortoisehg installs hgext3rd.evolve etc into its staged hg directory, since it doesn't use a virtualenv. As a workaround for us, we'll just allow any extra packages users want bundled are part of hg during the pseudo-install phase that py2exe uses. I'm not happy about this, but it *works*. As a sample of how you'd make an MSI with evolve bundled: import os import shutil import subprocess import tempfile def stage_evolve(version): """Stage evolve for inclusion in py2exe binary.""" with tempfile.TemporaryDirectory() as temp: evolve = os.path.join(temp, "evolve") subprocess.check_call([ "hg.exe", "clone", "https://www.mercurial-scm.org/repo/evolve/", "--update", version, evolve, ]) dest = os.path.join('..', 'hgext3rd', 'evolve') if os.path.exists(dest): shutil.rmtree(dest) shutil.copytree(os.path.join(evolve, "hgext3rd", "evolve"), dest) def main(): stage_evolve('tip') print("\0") print("hgext3rd") print("hgext3rd.evolve") print("hgext3rd.evolve.hack") print("hgext3rd.evolve.thirdparty") if __name__ == "__main__": main() is a script you can pass to the wix/build.py as --extra-packages-script, and the resulting .msi will have an hg binary with evolve baked in. users will still need to enable evolve in their hgrc, so you'd probably also want to bundle configs in your msi for an enterprise environment, but that's already easy to do with the support for extra features and wxs files in the wix build process. Differential Revision: https://phab.mercurial-scm.org/D6189

===================
Mercurial Rust Code
===================

This directory contains various Rust code for the Mercurial project.

The top-level ``Cargo.toml`` file defines a workspace containing
all primary Mercurial crates.

Building
========

To build the Rust components::

   $ cargo build

If you prefer a non-debug / release configuration::

   $ cargo build --release

Features
--------

The following Cargo features are available:

localdev (default)
   Produce files that work with an in-source-tree build.

   In this mode, the build finds and uses a ``python2.7`` binary from
   ``PATH``. The ``hg`` binary assumes it runs from ``rust/target/<target>hg``
   and it finds Mercurial files at ``dirname($0)/../../../``.

Build Mechanism
---------------

The produced ``hg`` binary is *bound* to a CPython installation. The
binary links against and loads a CPython library that is discovered
at build time (by a ``build.rs`` Cargo build script). The Python
standard library defined by this CPython installation is also used.

Finding the appropriate CPython installation to use is done by
the ``python27-sys`` crate's ``build.rs``. Its search order is::

1. ``PYTHON_SYS_EXECUTABLE`` environment variable.
2. ``python`` executable on ``PATH``
3. ``python2`` executable on ``PATH``
4. ``python2.7`` executable on ``PATH``

Additional verification of the found Python will be performed by our
``build.rs`` to ensure it meets Mercurial's requirements.

Details about the build-time configured Python are built into the
produced ``hg`` binary. This means that a built ``hg`` binary is only
suitable for a specific, well-defined role. These roles are controlled
by Cargo features (see above).

Running
=======

The ``hgcli`` crate produces an ``hg`` binary. You can run this binary
via ``cargo run``::

   $ cargo run --manifest-path hgcli/Cargo.toml

Or directly::

   $ target/debug/hg
   $ target/release/hg

You can also run the test harness with this binary::

   $ ./run-tests.py --with-hg ../rust/target/debug/hg

.. note::

   Integration with the test harness is still preliminary. Remember to
   ``cargo build`` after changes because the test harness doesn't yet
   automatically build Rust code.