Mercurial > hg
view tests/test-hardlinks.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 | 4441705b7111 |
children | cbc4425e81b5 |
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#require hardlink $ cat > nlinks.py <<EOF > from __future__ import print_function > import sys > from mercurial import util > for f in sorted(sys.stdin.readlines()): > f = f[:-1] > print(util.nlinks(f), f) > EOF $ nlinksdir() > { > find "$@" -type f | $PYTHON $TESTTMP/nlinks.py > } Some implementations of cp can't create hardlinks (replaces 'cp -al' on Linux): $ cat > linkcp.py <<EOF > from __future__ import absolute_import > import sys > from mercurial import util > util.copyfiles(sys.argv[1], sys.argv[2], hardlink=True) > EOF $ linkcp() > { > $PYTHON $TESTTMP/linkcp.py $1 $2 > } Prepare repo r1: $ hg init r1 $ cd r1 $ echo c1 > f1 $ hg add f1 $ hg ci -m0 $ mkdir d1 $ cd d1 $ echo c2 > f2 $ hg add f2 $ hg ci -m1 $ cd ../.. $ nlinksdir r1/.hg/store 1 r1/.hg/store/00changelog.i 1 r1/.hg/store/00manifest.i 1 r1/.hg/store/data/d1/f2.i 1 r1/.hg/store/data/f1.i 1 r1/.hg/store/fncache 1 r1/.hg/store/phaseroots 1 r1/.hg/store/undo 1 r1/.hg/store/undo.backup.fncache 1 r1/.hg/store/undo.backupfiles 1 r1/.hg/store/undo.phaseroots Create hardlinked clone r2: $ hg clone -U --debug r1 r2 --config progress.debug=true linking: 1 linking: 2 linking: 3 linking: 4 linking: 5 linking: 6 linking: 7 linked 7 files Create non-hardlinked clone r3: $ hg clone --pull r1 r3 requesting all changes adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 2 files new changesets 40d85e9847f2:7069c422939c updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved Repos r1 and r2 should now contain hardlinked files: $ nlinksdir r1/.hg/store 2 r1/.hg/store/00changelog.i 2 r1/.hg/store/00manifest.i 2 r1/.hg/store/data/d1/f2.i 2 r1/.hg/store/data/f1.i 2 r1/.hg/store/fncache 1 r1/.hg/store/phaseroots 1 r1/.hg/store/undo 1 r1/.hg/store/undo.backup.fncache 1 r1/.hg/store/undo.backupfiles 1 r1/.hg/store/undo.phaseroots $ nlinksdir r2/.hg/store 2 r2/.hg/store/00changelog.i 2 r2/.hg/store/00manifest.i 2 r2/.hg/store/data/d1/f2.i 2 r2/.hg/store/data/f1.i 2 r2/.hg/store/fncache Repo r3 should not be hardlinked: $ nlinksdir r3/.hg/store 1 r3/.hg/store/00changelog.i 1 r3/.hg/store/00manifest.i 1 r3/.hg/store/data/d1/f2.i 1 r3/.hg/store/data/f1.i 1 r3/.hg/store/fncache 1 r3/.hg/store/phaseroots 1 r3/.hg/store/undo 1 r3/.hg/store/undo.backupfiles 1 r3/.hg/store/undo.phaseroots Create a non-inlined filelog in r3: $ cd r3/d1 >>> f = open('data1', 'wb') >>> for x in range(10000): ... f.write("%s\n" % str(x)) >>> f.close() $ for j in 0 1 2 3 4 5 6 7 8 9; do > cat data1 >> f2 > hg commit -m$j > done $ cd ../.. $ nlinksdir r3/.hg/store 1 r3/.hg/store/00changelog.i 1 r3/.hg/store/00manifest.i 1 r3/.hg/store/data/d1/f2.d 1 r3/.hg/store/data/d1/f2.i 1 r3/.hg/store/data/f1.i 1 r3/.hg/store/fncache 1 r3/.hg/store/phaseroots 1 r3/.hg/store/undo 1 r3/.hg/store/undo.backup.fncache 1 r3/.hg/store/undo.backup.phaseroots 1 r3/.hg/store/undo.backupfiles 1 r3/.hg/store/undo.phaseroots Push to repo r1 should break up most hardlinks in r2: $ hg -R r2 verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 2 changesets, 2 total revisions $ cd r3 $ hg push pushing to $TESTTMP/r1 searching for changes adding changesets adding manifests adding file changes added 10 changesets with 10 changes to 1 files $ cd .. $ nlinksdir r2/.hg/store 1 r2/.hg/store/00changelog.i 1 r2/.hg/store/00manifest.i 1 r2/.hg/store/data/d1/f2.i 2 r2/.hg/store/data/f1.i [12] r2/\.hg/store/fncache (re) #if hardlink-whitelisted $ nlinksdir r2/.hg/store/fncache 2 r2/.hg/store/fncache #endif $ hg -R r2 verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 2 changesets, 2 total revisions $ cd r1 $ hg up 1 files updated, 0 files merged, 0 files removed, 0 files unresolved Committing a change to f1 in r1 must break up hardlink f1.i in r2: $ echo c1c1 >> f1 $ hg ci -m00 $ cd .. $ nlinksdir r2/.hg/store 1 r2/.hg/store/00changelog.i 1 r2/.hg/store/00manifest.i 1 r2/.hg/store/data/d1/f2.i 1 r2/.hg/store/data/f1.i [12] r2/\.hg/store/fncache (re) #if hardlink-whitelisted $ nlinksdir r2/.hg/store/fncache 2 r2/.hg/store/fncache #endif Create a file which exec permissions we will change $ cd r3 $ echo "echo hello world" > f3 $ hg add f3 $ hg ci -mf3 $ cd .. $ cd r3 $ hg tip --template '{rev}:{node|short}\n' 12:d3b77733a28a $ echo bla > f1 $ chmod +x f3 $ hg ci -m1 $ cd .. Create hardlinked copy r4 of r3 (on Linux, we would call 'cp -al'): $ linkcp r3 r4 'checklink' is produced by hardlinking a symlink, which is undefined whether the symlink should be followed or not. It does behave differently on Linux and BSD. Just remove it so the test pass on both platforms. $ rm -f r4/.hg/cache/checklink r4 has hardlinks in the working dir (not just inside .hg): $ nlinksdir r4 2 r4/.hg/00changelog.i 2 r4/.hg/branch 2 r4/.hg/cache/branch2-base 2 r4/.hg/cache/branch2-served 2 r4/.hg/cache/checkisexec (execbit !) ? r4/.hg/cache/checklink-target (glob) (symlink !) 2 r4/.hg/cache/checknoexec (execbit !) 2 r4/.hg/cache/rbc-names-v1 2 r4/.hg/cache/rbc-revs-v1 2 r4/.hg/dirstate 2 r4/.hg/fsmonitor.state (fsmonitor !) 2 r4/.hg/hgrc 2 r4/.hg/last-message.txt 2 r4/.hg/requires 2 r4/.hg/store/00changelog.i 2 r4/.hg/store/00manifest.i 2 r4/.hg/store/data/d1/f2.d 2 r4/.hg/store/data/d1/f2.i 2 r4/.hg/store/data/f1.i 2 r4/.hg/store/data/f3.i 2 r4/.hg/store/fncache 2 r4/.hg/store/phaseroots 2 r4/.hg/store/undo 2 r4/.hg/store/undo.backup.fncache 2 r4/.hg/store/undo.backup.phaseroots 2 r4/.hg/store/undo.backupfiles 2 r4/.hg/store/undo.phaseroots [24] r4/\.hg/undo\.backup\.dirstate (re) 2 r4/.hg/undo.bookmarks 2 r4/.hg/undo.branch 2 r4/.hg/undo.desc [24] r4/\.hg/undo\.dirstate (re) 2 r4/d1/data1 2 r4/d1/f2 2 r4/f1 2 r4/f3 Update back to revision 12 in r4 should break hardlink of file f1 and f3: #if hardlink-whitelisted $ nlinksdir r4/.hg/undo.backup.dirstate r4/.hg/undo.dirstate 4 r4/.hg/undo.backup.dirstate 4 r4/.hg/undo.dirstate #endif $ hg -R r4 up 12 2 files updated, 0 files merged, 0 files removed, 0 files unresolved (execbit !) 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-execbit !) $ nlinksdir r4 2 r4/.hg/00changelog.i 1 r4/.hg/branch 2 r4/.hg/cache/branch2-base 2 r4/.hg/cache/branch2-served 2 r4/.hg/cache/checkisexec (execbit !) 2 r4/.hg/cache/checklink-target (symlink !) 2 r4/.hg/cache/checknoexec (execbit !) 2 r4/.hg/cache/rbc-names-v1 2 r4/.hg/cache/rbc-revs-v1 1 r4/.hg/dirstate 1 r4/.hg/fsmonitor.state (fsmonitor !) 2 r4/.hg/hgrc 2 r4/.hg/last-message.txt 2 r4/.hg/requires 2 r4/.hg/store/00changelog.i 2 r4/.hg/store/00manifest.i 2 r4/.hg/store/data/d1/f2.d 2 r4/.hg/store/data/d1/f2.i 2 r4/.hg/store/data/f1.i 2 r4/.hg/store/data/f3.i 2 r4/.hg/store/fncache 2 r4/.hg/store/phaseroots 2 r4/.hg/store/undo 2 r4/.hg/store/undo.backup.fncache 2 r4/.hg/store/undo.backup.phaseroots 2 r4/.hg/store/undo.backupfiles 2 r4/.hg/store/undo.phaseroots [24] r4/\.hg/undo\.backup\.dirstate (re) 2 r4/.hg/undo.bookmarks 2 r4/.hg/undo.branch 2 r4/.hg/undo.desc [24] r4/\.hg/undo\.dirstate (re) 2 r4/d1/data1 2 r4/d1/f2 1 r4/f1 1 r4/f3 (execbit !) 2 r4/f3 (no-execbit !) #if hardlink-whitelisted $ nlinksdir r4/.hg/undo.backup.dirstate r4/.hg/undo.dirstate 4 r4/.hg/undo.backup.dirstate 4 r4/.hg/undo.dirstate #endif Test hardlinking outside hg: $ mkdir x $ echo foo > x/a $ linkcp x y $ echo bar >> y/a No diff if hardlink: $ diff x/a y/a Test mq hardlinking: $ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init a $ cd a $ hg qimport -n foo - << EOF > # HG changeset patch > # Date 1 0 > diff -r 2588a8b53d66 a > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/a Wed Jul 23 15:54:29 2008 +0200 > @@ -0,0 +1,1 @@ > +a > EOF adding foo to series file $ hg qpush applying foo now at: foo $ cd .. $ linkcp a b $ cd b $ hg qimport -n bar - << EOF > # HG changeset patch > # Date 2 0 > diff -r 2588a8b53d66 a > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/b Wed Jul 23 15:54:29 2008 +0200 > @@ -0,0 +1,1 @@ > +b > EOF adding bar to series file $ hg qpush applying bar now at: bar $ cat .hg/patches/status 430ed4828a74fa4047bc816a25500f7472ab4bfe:foo 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c:bar $ cat .hg/patches/series foo bar $ cat ../a/.hg/patches/status 430ed4828a74fa4047bc816a25500f7472ab4bfe:foo $ cat ../a/.hg/patches/series foo Test tags hardlinking: $ hg qdel -r qbase:qtip patch foo finalized without changeset message patch bar finalized without changeset message $ hg tag -l lfoo $ hg tag foo $ cd .. $ linkcp b c $ cd c $ hg tag -l -r 0 lbar $ hg tag -r 0 bar $ cat .hgtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo 430ed4828a74fa4047bc816a25500f7472ab4bfe bar $ cat .hg/localtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo 430ed4828a74fa4047bc816a25500f7472ab4bfe lbar $ cat ../b/.hgtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo $ cat ../b/.hg/localtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo $ cd ..