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aggressivemergedelta: document rename and move to `revlog` section...
aggressivemergedelta: document rename and move to `revlog` section The config does not follow our naming guideline and "Aggressive" is probably a word to keep away from users. The option does not truly fit in the `format` section. It can be turned on and off for existing repository without much consequence regarding compatibility. A new `revlog` option is created to control behavior related to revlog writing and reading. We can see multiple other config options that could be migrated there. * format.maxchainlen * experimental.mmapindexthreshold * experimental.sparse-read.density-threshold (in an updated form) * experimental.sparse-read.min-gap-size (in an updated form) In addition, we can foresee at least a couple of sparse-revlog related option coming too (to reduce delta chain length and increase snapshot reuse) These two extra options might fit there too. Unless we want to create a section dedicated to caches and performance. * format.chunkcachesize * format.manifestcachesize For now, we only migrate `optimize-delta-parent-choice` since it is getting out of experimental. It is too close to the release to move the other one. In addition, we still lack proper the prioritization of alias that would help renaming them without bad consequence for users. (Not fully happy about the `revlog` name but could not find better).
Boris Feld -
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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.