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
#require serve
$ hg init test
$ cd test
$ for i in 0 1 2 3 4 5 6 7 8; do
> echo $i >> foo
> hg commit -A -m $i
> done
adding foo
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 9 changesets, 9 total revisions
$ hg serve -p $HGPORT -d --pid-file=hg.pid
$ cat hg.pid >> $DAEMON_PIDS
$ cd ..
$ hg init new
http incoming
$ hg -R new incoming http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming -r 4 http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
local incoming
$ hg -R new incoming test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming -r 4 test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
limit to 2 changesets
$ hg -R new incoming -l 2 test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
limit to 2 changesets, test with -p --git
$ hg -R new incoming -l 2 -p --git test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
diff --git a/foo b/foo
new file mode 100644
--- /dev/null
+++ b/foo
@@ -0,0 +1,1 @@
+0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
diff --git a/foo b/foo
--- a/foo
+++ b/foo
@@ -1,1 +1,2 @@
0
+1
test with --bundle
$ hg -R new incoming --bundle test.hg http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming --bundle test2.hg test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
test the resulting bundles
$ hg init temp
$ hg init temp2
$ hg -R temp unbundle test.hg
adding changesets
adding manifests
adding file changes
added 9 changesets with 9 changes to 1 files
new changesets 00a43fa82f62:e4feb4ac9035
(run 'hg update' to get a working copy)
$ hg -R temp2 unbundle test2.hg
adding changesets
adding manifests
adding file changes
added 9 changesets with 9 changes to 1 files
new changesets 00a43fa82f62:e4feb4ac9035
(run 'hg update' to get a working copy)
$ hg -R temp tip
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R temp2 tip
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ rm -r temp temp2 new
test outgoing
$ hg clone test test-dev
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd test-dev
$ for i in 9 10 11 12 13; do
> echo $i >> foo
> hg commit -A -m $i
> done
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 14 changesets, 14 total revisions
$ cd ..
$ hg -R test-dev outgoing test
comparing with test
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
changeset: 12:e576b1bed305
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 12
changeset: 13:96bbff09a7cc
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 13
test outgoing with secret changesets
$ hg -R test-dev phase --force --secret 9
$ hg -R test-dev outgoing test
comparing with test
searching for changes
no changes found (ignored 5 secret changesets)
[1]
$ hg -R test-dev phase --draft -r 'head()'
limit to 3 changesets
$ hg -R test-dev outgoing -l 3 test
comparing with test
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
$ hg -R test-dev outgoing http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
changeset: 12:e576b1bed305
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 12
changeset: 13:96bbff09a7cc
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 13
$ hg -R test-dev outgoing -r 11 http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
incoming from empty remote repository
$ hg init r1
$ hg init r2
$ echo a > r1/foo
$ hg -R r1 ci -Ama
adding foo
$ hg -R r1 incoming r2 --bundle x.hg
comparing with r2
searching for changes
no changes found
[1]
Create a "split" repo that pulls from r1 and pushes to r2, using default-push
$ hg clone r1 split
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cat > split/.hg/hgrc << EOF
> [paths]
> default = $TESTTMP/r3
> default-push = $TESTTMP/r2
> EOF
$ hg -R split outgoing
comparing with $TESTTMP/r2
searching for changes
changeset: 0:3e92d79f743a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Use default:pushurl instead of default-push
Windows needs a leading slash to make a URL that passes all of the checks
$ WD=`pwd`
#if windows
$ WD="/$WD"
#endif
$ cat > split/.hg/hgrc << EOF
> [paths]
> default = $WD/r3
> default:pushurl = file://$WD/r2
> EOF
$ hg -R split outgoing
comparing with file:/*/$TESTTMP/r2 (glob)
searching for changes
changeset: 0:3e92d79f743a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Push and then double-check outgoing
$ echo a >> split/foo
$ hg -R split commit -Ama
$ hg -R split push
pushing to file:/*/$TESTTMP/r2 (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
$ hg -R split outgoing
comparing with file:/*/$TESTTMP/r2 (glob)
searching for changes
no changes found
[1]