view rust/README.rst @ 36534:5faeabb07cf5

debugcommands: support for triggering push protocol The mechanism for pushing to a remote is a bit more complicated than other commands. On SSH, we wait for a positive reply from the server before we start sending the bundle payload. This commit adds a mechanism to the "command" action in `hg debugwireproto` to trigger the "push protocol" and to specify a file whose contents should be submitted as the command payload. With this new feature, we implement a handful of tests for the "unbundle" command. We try to cover various server failures and hook/output scenarios so protocol behavior is as comprehensively tested as possible. Even with so much test output, we only cover bundle1 with Python hooks. There's still a lot of test coverage that needs to be implemented. But this is certainly a good start. Because there are so many new tests, we split these tests into their own test file. In order to make output deterministic, we need to disable the doublepipe primitive. We add an option to `hg debugwireproto` to do that. Because something in the bowels of the peer does a read of stderr, we still capture read I/O from stderr. So there is test coverage of what the server emits. The tests around I/O capture some wonkiness. For example, interleaved ui.write() and ui.write_err() calls are emitted in order. However, (presumably due to buffering), print() to sys.stdout and sys.stderr aren't in order. We currently only test bundle1 because bundle2 is substantially harder to test because it is more complicated (the server responds with a stream containing a bundle2 instead of a frame). Differential Revision: https://phab.mercurial-scm.org/D2471
author Gregory Szorc <gregory.szorc@gmail.com>
date Mon, 26 Feb 2018 18:01:13 -0800
parents 964212780daf
children 8a3b045d9086
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===================
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.