Mercurial > hg
view tests/test-minirst.py.out @ 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 | 6582b3716ae0 |
| children | aaff3bc75306 |
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== paragraphs == 60 column format: ---------------------------------------------------------------------- This is some text in the first paragraph. A small indented paragraph. It is followed by some lines containing random whitespace. The third and final paragraph. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- This is some text in the first paragraph. A small indented paragraph. It is followed by some lines containing random whitespace. The third and final paragraph. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> This is some text in the first paragraph. </p> <p> A small indented paragraph. It is followed by some lines containing random whitespace. </p> <p> The third and final paragraph. </p> ---------------------------------------------------------------------- == definitions == 60 column format: ---------------------------------------------------------------------- A Term Definition. The indented lines make up the definition. Another Term Another definition. The final line in the definition determines the indentation, so this will be indented with four spaces. A Nested/Indented Term Definition. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- A Term Definition. The indented lines make up the definition. Another Term Another definition. The final line in the definition determines the indentation, so this will be indented with four spaces. A Nested/Indented Term Definition. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <dl> <dt>A Term <dd>Definition. The indented lines make up the definition. <dt>Another Term <dd>Another definition. The final line in the definition determines the indentation, so this will be indented with four spaces. <dt>A Nested/Indented Term <dd>Definition. </dl> ---------------------------------------------------------------------- == literals == 60 column format: ---------------------------------------------------------------------- The fully minimized form is the most convenient form: Hello literal world In the partially minimized form a paragraph simply ends with space-double-colon. //////////////////////////////////////// long un-wrapped line in a literal block \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ This literal block is started with '::', the so-called expanded form. The paragraph with '::' disappears in the final output. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- The fully minimized form is the most convenient form: Hello literal world In the partially minimized form a paragraph simply ends with space-double-colon. //////////////////////////////////////// long un-wrapped line in a literal block \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ This literal block is started with '::', the so-called expanded form. The paragraph with '::' disappears in the final output. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> The fully minimized form is the most convenient form: </p> <pre> Hello literal world </pre> <p> In the partially minimized form a paragraph simply ends with space-double-colon. </p> <pre> //////////////////////////////////////// long un-wrapped line in a literal block \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ </pre> <pre> This literal block is started with '::', the so-called expanded form. The paragraph with '::' disappears in the final output. </pre> ---------------------------------------------------------------------- == lists == 60 column format: ---------------------------------------------------------------------- - This is the first list item. Second paragraph in the first list item. - List items need not be separated by a blank line. - And will be rendered without one in any case. We can have indented lists: - This is an indented list item - Another indented list item: - A literal block in the middle of an indented list. (The above is not a list item since we are in the literal block.) Literal block with no indentation (apart from the two spaces added to all literal blocks). 1. This is an enumerated list (first item). 2. Continuing with the second item. (1) foo (2) bar 1) Another 2) List Line blocks are also a form of list: This is the first line. The line continues here. This is the second line. Bullet lists are also detected: * This is the first bullet * This is the second bullet It has 2 lines * This is the third bullet ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- - This is the first list item. Second paragraph in the first list item. - List items need not be separated by a blank line. - And will be rendered without one in any case. We can have indented lists: - This is an indented list item - Another indented list item: - A literal block in the middle of an indented list. (The above is not a list item since we are in the literal block.) Literal block with no indentation (apart from the two spaces added to all literal blocks). 1. This is an enumerated list (first item). 2. Continuing with the second item. (1) foo (2) bar 1) Another 2) List Line blocks are also a form of list: This is the first line. The line continues here. This is the second line. Bullet lists are also detected: * This is the first bullet * This is the second bullet It has 2 lines * This is the third bullet ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <ul> <li> This is the first list item. <p> Second paragraph in the first list item. </p> <li> List items need not be separated by a blank line. <li> And will be rendered without one in any case. </ul> <p> We can have indented lists: </p> <ul> <li> This is an indented list item <li> Another indented list item: <pre> - A literal block in the middle of an indented list. </pre> <pre> (The above is not a list item since we are in the literal block.) </pre> </ul> <pre> Literal block with no indentation (apart from the two spaces added to all literal blocks). </pre> <ol> <li> This is an enumerated list (first item). <li> Continuing with the second item. <li> foo <li> bar <li> Another <li> List </ol> <p> Line blocks are also a form of list: </p> <ol> <li> This is the first line. The line continues here. <li> This is the second line. </ol> <p> Bullet lists are also detected: </p> <ul> <li> This is the first bullet <li> This is the second bullet It has 2 lines <li> This is the third bullet </ul> ---------------------------------------------------------------------- == options == 60 column format: ---------------------------------------------------------------------- There is support for simple option lists, but only with long options: -X --exclude filter an option with a short and long option with an argument -I --include an option with both a short option and a long option --all Output all. --both Output both (this description is quite long). --long Output all day long. --par This option has two paragraphs in its description. This is the first. This is the second. Blank lines may be omitted between options (as above) or left in (as here). The next paragraph looks like an option list, but lacks the two-space marker after the option. It is treated as a normal paragraph: --foo bar baz ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- There is support for simple option lists, but only with long options: -X --exclude filter an option with a short and long option with an argumen t -I --include an option with both a short option and a long option --all Output all. --both Output both (this d escript ion is quite long). --long Output all day long. --par This option has two paragra phs in its des criptio n. This is the first. This is the second. Blank lines may be omitted between options (as above) or left in (as here). The next paragraph looks like an option list, but lacks the two-space marker after the option. It is treated as a normal paragraph: --foo bar baz ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> There is support for simple option lists, but only with long options: </p> <dl> <dt>-X --exclude filter <dd>an option with a short and long option with an argument <dt>-I --include <dd>an option with both a short option and a long option <dt> --all <dd>Output all. <dt> --both <dd>Output both (this description is quite long). <dt> --long <dd>Output all day long. <dt> --par <dd>This option has two paragraphs in its description. This is the first. <p> This is the second. Blank lines may be omitted between options (as above) or left in (as here). </p> </dl> <p> The next paragraph looks like an option list, but lacks the two-space marker after the option. It is treated as a normal paragraph: </p> <p> --foo bar baz </p> ---------------------------------------------------------------------- == fields == 60 column format: ---------------------------------------------------------------------- a First item. ab Second item. Indentation and wrapping is handled automatically. Next list: small The larger key below triggers full indentation here. much too large This key is big enough to get its own line. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- a First item. ab Second item. Indentation and wrapping is handled automatically. Next list: small The larger key below triggers full indentation here. much too large This key is big enough to get its own line. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <dl> <dt>a <dd>First item. <dt>ab <dd>Second item. Indentation and wrapping is handled automatically. </dl> <p> Next list: </p> <dl> <dt>small <dd>The larger key below triggers full indentation here. <dt>much too large <dd>This key is big enough to get its own line. </dl> ---------------------------------------------------------------------- == containers (normal) == 60 column format: ---------------------------------------------------------------------- Normal output. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Normal output. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Normal output. </p> ---------------------------------------------------------------------- == containers (verbose) == 60 column format: ---------------------------------------------------------------------- Normal output. Verbose output. ---------------------------------------------------------------------- ['debug', 'debug'] ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Normal output. Verbose output. ---------------------------------------------------------------------- ['debug', 'debug'] ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Normal output. </p> <p> Verbose output. </p> ---------------------------------------------------------------------- ['debug', 'debug'] ---------------------------------------------------------------------- == containers (debug) == 60 column format: ---------------------------------------------------------------------- Normal output. Initial debug output. ---------------------------------------------------------------------- ['verbose'] ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Normal output. Initial debug output. ---------------------------------------------------------------------- ['verbose'] ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Normal output. </p> <p> Initial debug output. </p> ---------------------------------------------------------------------- ['verbose'] ---------------------------------------------------------------------- == containers (verbose debug) == 60 column format: ---------------------------------------------------------------------- Normal output. Initial debug output. Verbose output. Debug output. ---------------------------------------------------------------------- [] ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Normal output. Initial debug output. Verbose output. Debug output. ---------------------------------------------------------------------- [] ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Normal output. </p> <p> Initial debug output. </p> <p> Verbose output. </p> <p> Debug output. </p> ---------------------------------------------------------------------- [] ---------------------------------------------------------------------- == roles == 60 column format: ---------------------------------------------------------------------- Please see 'hg add'. ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Please see 'hg add'. ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Please see 'hg add'. </p> ---------------------------------------------------------------------- == sections == 60 column format: ---------------------------------------------------------------------- Title ===== Section ------- Subsection '''''''''' Markup: "foo" and 'hg help' --------------------------- ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Title ===== Section ------- Subsection '''''''''' Markup: "foo" and 'hg help' --------------------------- ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <h1>Title</h1> <h2>Section</h2> <h3>Subsection</h3> <h2>Markup: "foo" and 'hg help'</h2> ---------------------------------------------------------------------- == admonitions == 60 column format: ---------------------------------------------------------------------- Note: This is a note - Bullet 1 - Bullet 2 Warning! This is a warning Second input line of warning !Danger! This is danger ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Note: This is a note - Bullet 1 - Bullet 2 Warning! This is a warning Second input line of warning !Danger! This is danger ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> <b>Note:</b> </p> <p> This is a note </p> <ul> <li> Bullet 1 <li> Bullet 2 </ul> <p> <b>Warning!</b> This is a warning Second input line of warning </p> <p> <b>!Danger!</b> This is danger </p> ---------------------------------------------------------------------- == comments == 60 column format: ---------------------------------------------------------------------- Some text. Some indented text. Empty comment above ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- Some text. Some indented text. Empty comment above ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <p> Some text. </p> <p> Some indented text. </p> <p> Empty comment above </p> ---------------------------------------------------------------------- === === ======================================== a b c === === ======================================== 1 2 3 foo bar baz this list is very very very long man === === ======================================== == table == 60 column format: ---------------------------------------------------------------------- a b c ------------------------------------------------ 1 2 3 foo bar baz this list is very very very long man ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- a b c ------------------------------ 1 2 3 foo bar baz this list is very very very long man ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <table> <tr><td>a</td> <td>b</td> <td>c</td></tr> <tr><td>1</td> <td>2</td> <td>3</td></tr> <tr><td>foo</td> <td>bar</td> <td>baz this list is very very very long man</td></tr> </table> ---------------------------------------------------------------------- = ==== ====================================== s long line goes on here xy tried to fix here by indenting = ==== ====================================== == table+nl == 60 column format: ---------------------------------------------------------------------- s long line goes on here xy tried to fix here by indenting ---------------------------------------------------------------------- 30 column format: ---------------------------------------------------------------------- s long line goes on here xy tried to fix here by indenting ---------------------------------------------------------------------- html format: ---------------------------------------------------------------------- <table> <tr><td>s</td> <td>long</td> <td>line goes on here</td></tr> <tr><td></td> <td>xy</td> <td>tried to fix here by indenting</td></tr> </table> ----------------------------------------------------------------------