Mercurial > hg
view rust/README.rst @ 39814:d059cb669632
wireprotov2: allow multiple fields to follow revision maps
The *data wire protocol commands emit a series of CBOR values.
Because revision/delta data may be large, their data is emitted
outside the map as a top-level bytestring value.
Before this commit, we'd emit a single optional bytestring
value after the revision descriptor map. This got the job done.
But it was limiting in that we could only send a single field.
And, it required the consumer to know that the presence of a
key in the map implied the existence of a following bytestring
value.
This commit changes the encoding strategy so top-level bytestring
values in the stream are explicitly denoted in a "fieldsfollowing"
key. This key contains an array defining what fields that follow
and the expected size of each field.
By defining things this way, we can easily send N bytestring
values without any ambiguity about their order. In addition,
clients only need to know how to parse ``fieldsfollowing`` to
know if extra values are present.
Because this breaks backwards compatibility, we've bumped the version
number of the wire protocol version 2 API endpoint.
Differential Revision: https://phab.mercurial-scm.org/D4620
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Thu, 20 Sep 2018 12:57:23 -0700 |
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.