Mercurial > hg
view tests/test-clone-r.t @ 35569:964212780daf
rust: implementation of `hg`
This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.
If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.
Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.
It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.
Now onto the implementation.
We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.
The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.
There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):
* Validates that the Python interpreter that was detected by the
python27-sys crate provides a shared library (we only support
shared library linking at this time - although this restriction
could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
find the path to the Python interpreter.
The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.
Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.
In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.
Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:
* test-run-tests.t -- Warnings emitted about using an unexpected
Mercurial library. This is due to the hacky nature of setting the
Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
(This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.
It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.
Differential Revision: https://phab.mercurial-scm.org/D1581
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 10 Jan 2018 08:53:22 -0800 |
parents | eb586ed5d8ce |
children | 009d0283de5f |
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$ hg init test $ cd test $ echo 0 >> afile $ hg add afile $ hg commit -m "0.0" $ echo 1 >> afile $ hg commit -m "0.1" $ echo 2 >> afile $ hg commit -m "0.2" $ echo 3 >> afile $ hg commit -m "0.3" $ hg update -C 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo 1 >> afile $ hg commit -m "1.1" created new head $ echo 2 >> afile $ hg commit -m "1.2" $ echo a line > fred $ echo 3 >> afile $ hg add fred $ hg commit -m "1.3" $ hg mv afile adifferentfile $ hg commit -m "1.3m" $ hg update -C 3 1 files updated, 0 files merged, 2 files removed, 0 files unresolved $ hg mv afile anotherfile $ hg commit -m "0.3m" $ hg debugindex -f 1 afile rev flag offset length size ..... link p1 p2 nodeid (re) 0 0000 0 3 2 ..... 0 -1 -1 362fef284ce2 (re) 1 0000 3 5 4 ..... 1 0 -1 125144f7e028 (re) 2 0000 8 7 6 ..... 2 1 -1 4c982badb186 (re) 3 0000 15 9 8 ..... 3 2 -1 19b1fc555737 (re) $ hg debugindex adifferentfile rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 75 ..... 7 2565f3199a74 000000000000 000000000000 (re) $ hg debugindex anotherfile rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 75 ..... 8 2565f3199a74 000000000000 000000000000 (re) $ hg debugindex fred rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 8 ..... 6 12ab3bcc5ea4 000000000000 000000000000 (re) $ hg debugindex --manifest rev offset length ..... linkrev nodeid p1 p2 (re) 0 0 48 ..... 0 43eadb1d2d06 000000000000 000000000000 (re) 1 48 48 ..... 1 8b89697eba2c 43eadb1d2d06 000000000000 (re) 2 96 48 ..... 2 626a32663c2f 8b89697eba2c 000000000000 (re) 3 144 48 ..... 3 f54c32f13478 626a32663c2f 000000000000 (re) 4 192 .. ..... 6 de68e904d169 626a32663c2f 000000000000 (re) 5 2.. .. ..... 7 09bb521d218d de68e904d169 000000000000 (re) 6 3.. 54 ..... 8 1fde233dfb0f f54c32f13478 000000000000 (re) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 9 changesets, 7 total revisions $ cd .. $ for i in 0 1 2 3 4 5 6 7 8; do > echo > echo ---- hg clone -r "$i" test test-"$i" > hg clone -r "$i" test test-"$i" > cd test-"$i" > hg verify > cd .. > done ---- hg clone -r 0 test test-0 adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files new changesets f9ee2f85a263 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 1 changesets, 1 total revisions ---- hg clone -r 1 test test-1 adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets f9ee2f85a263:34c2bf6b0626 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 2 changesets, 2 total revisions ---- hg clone -r 2 test test-2 adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets f9ee2f85a263:e38ba6f5b7e0 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions ---- hg clone -r 3 test test-3 adding changesets adding manifests adding file changes added 4 changesets with 4 changes to 1 files new changesets f9ee2f85a263:eebf5a27f8ca updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 4 changesets, 4 total revisions ---- hg clone -r 4 test test-4 adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets f9ee2f85a263:095197eb4973 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 2 changesets, 2 total revisions ---- hg clone -r 5 test test-5 adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets f9ee2f85a263:1bb50a9436a7 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions ---- hg clone -r 6 test test-6 adding changesets adding manifests adding file changes added 4 changesets with 5 changes to 2 files new changesets f9ee2f85a263:7373c1169842 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 4 changesets, 5 total revisions ---- hg clone -r 7 test test-7 adding changesets adding manifests adding file changes added 5 changesets with 6 changes to 3 files new changesets f9ee2f85a263:a6a34bfa0076 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 3 files, 5 changesets, 6 total revisions ---- hg clone -r 8 test test-8 adding changesets adding manifests adding file changes added 5 changesets with 5 changes to 2 files new changesets f9ee2f85a263:aa35859c02ea updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 5 changesets, 5 total revisions $ cd test-8 $ hg pull ../test-7 pulling from ../test-7 searching for changes adding changesets adding manifests adding file changes added 4 changesets with 2 changes to 3 files (+1 heads) new changesets 095197eb4973:a6a34bfa0076 (run 'hg heads' to see heads, 'hg merge' to merge) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 9 changesets, 7 total revisions $ cd .. $ hg clone test test-9 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd test-9 $ hg branch foobar marked working directory as branch foobar (branches are permanent and global, did you want a bookmark?) $ echo file2 >> file2 $ hg add file2 $ hg commit -m "changeset9" $ echo file3 >> file3 $ hg add file3 $ hg commit -m "changeset10" $ cd .. $ hg clone -r 9 -u foobar test-9 test-10 adding changesets adding manifests adding file changes added 6 changesets with 6 changes to 3 files new changesets f9ee2f85a263:7100abb79635 updating to branch foobar 2 files updated, 0 files merged, 0 files removed, 0 files unresolved