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  1. Oct 28, 2018
  2. Oct 15, 2018
  3. Oct 08, 2018
    • Georges Racinet's avatar
      rust: rustlazyancestors.__contains__ · 72b94f94
      Georges Racinet authored
      This changeset provides a Rust implementation of
      the iteration performed by lazyancestor.__contains__
      
      It has the advantage over the Python iteration to use
      the 'seen' set encapsuled into the dedicated iterator (self._containsiter),
      rather than storing emitted items in another set (self._containsseen),
      and hence should reduce the memory footprint.
      
      Also, there's no need to convert intermediate emitted revisions back into
      Python integers.
      
      At this point, it would be tempting to implement the whole lazyancestor object
      in Rust, but that would lead to more C wrapping code (two objects) for
      little expected benefits.
      72b94f94
  4. Oct 06, 2018
  5. Oct 07, 2018
  6. Oct 06, 2018
    • Yuya Nishihara's avatar
      rust-chg: depend on log and tokio_timer · 7623199d
      Yuya Nishihara authored
      I'll start porting the daemon management functions from chg of C, which
      will be difficult to debug without some logging facility. AFAIK, the log
      crate is easy-to-use and widely used.
      
      tokio_timer provides sleep() helper to be used while spawning a server
      process.
      7623199d
  7. Oct 07, 2018
  8. Sep 27, 2018
    • Georges Racinet's avatar
      rust: iterator bindings to C code · a36c5e23
      Georges Racinet authored
      In this changeset, still made of Rust code only,
      we expose the Rust iterator for instantiation and
      consumption from C code.
      
      The idea is that both the index and index_get_parents()
      will be passed from the C extension, hence avoiding a hard
      link dependency to parsers.so, so that the crate can
      still be built and tested independently.
      
      On the other hand, parsers.so will use the symbols
      defined in this changeset.
      a36c5e23
    • Georges Racinet's avatar
      rust: pure Rust lazyancestors iterator · dbc28c91
      Georges Racinet authored
      This is the first of a patch series aiming to provide an
      alternative implementation in the Rust programming language
      of the _lazyancestorsiter from the ancestor module.
      
      This iterator has been brought to our attention by the people at
      Octobus, as a potential good candidate for incremental "oxydation"
      (rewriting in Rust), because it has shown performance issues lately
      and it merely deals with ints (revision numbers) obtained by calling
      the index, whih should be directly callable from Rust code,
      being itself implemented as a C extension.
      
      The idea behind this series is to provide a minimal example of Rust code
      collaborating with existing C and Python code. To open the way to gradually
      rewriting more of Mercurial's Python code in Rust, without being forced to pay
      a large initial cost of rewriting the existing fast core into Rust.
      
      This patch does not introduce any bindings to other Mercurial code
      yet. Instead, it introduces the necessary abstractions to address the problem
      independently, and unit-test it.
      
      Since this is the first use of Rust as a Python module within Mercurial,
      the hg-core crate gets created within this patch. See its Cargo.toml for more
      details.
      
      Someone with a rustc/cargo installation may chdir into rust/hg-core and
      run the tests by issuing:
      
         cargo test --lib
      
      The algorithm is a bit simplified (see details in docstrings),
      and at its simplest becomes rather trivial, showcasing that Rust has
      batteries included too: BinaryHeap, the Rust analog of Python's heapq
      does actually all the work.
      
      The implementation can be further optimized and probably be made more
      idiomatic Rust.
      dbc28c91
  9. Sep 25, 2018
  10. Sep 24, 2018
  11. Sep 29, 2018
  12. Sep 24, 2018
    • Yuya Nishihara's avatar
      rust-chg: add future that handles "attachio" request · 7a0ffdd4
      Yuya Nishihara authored
      This is the sequence to send client-side stdio and pager stdin to the
      server.
      7a0ffdd4
    • Yuya Nishihara's avatar
      rust-chg: add parser for request messages sent to "S" channel · b1d8acd8
      Yuya Nishihara authored
      The data structure is documented at chgserver.py:channeledsystem().
      b1d8acd8
    • Yuya Nishihara's avatar
      rust-chg: add wrapper around C function · a8be2cff
      Yuya Nishihara authored
      a8be2cff
    • Yuya Nishihara's avatar
      rust-chg: add function to send fds via domain socket · 208cb7a9
      Yuya Nishihara authored
      As a beginning, I wrote some C.
      
      It's extracted from attachio() of contrib/chg/hgclient.c. Maybe it could
      be rewritten in Rust by using the libc (and/or nix) crates, but doing that
      wouldn't be trivial as the code depends on CMSG_*() macros. IMO, using C
      is better here.
      208cb7a9
    • Yuya Nishihara's avatar
      rust-chg: update dependencies · 86acdfe8
      Yuya Nishihara authored
      86acdfe8
    • Yuya Nishihara's avatar
      rust-chg: add project skeleton · aab43d58
      Yuya Nishihara authored
      This directory will host the reimplementation of cHg in Rust. It will use
      Tokio [1], and tokio-hglib [2] which I wrote for an oxidized CHg, no idea
      if there's such carbon bonding in nature btw.
      
       [1]: https://tokio.rs/
       [2]: https://bitbucket.org/yuja/tokio-hglib/
      
      The reasoning for depending on Tokio is that it will allow us to handle Unix
      signals in a safer way. Well, I believed that until I found a weird function,
      handlestopsignal(), in cHg codebase. It resends the same signal to the same
      process by temporarily masking the handler, which can't be inherently async.
      So the signal handlers will stay in C, which means there isn't actually much
      reason to write async code right now, other than I've already done most of
      the async stuff, and slightly easier pager handling.
      
      The reasoning for the rewrite is that it will eventually be possible to port
      server-side config validation back to the client side, which will reduce
      the complexity of the current daemon management. It will also encourage us
      to write frontend library (e.g. command line and config parsers) in Rust.
      
      The license is GPL2+ because it's likely to include derived work from the
      cHg of C. The rust/chg crate is excluded from the root workspace as it's
      unclear how the whole rust packages should be laid out. That can be revisited
      later.
      aab43d58
  13. Jan 12, 2018
  14. Jan 11, 2018
  15. Jan 10, 2018
    • Gregory Szorc's avatar
      rust: implementation of `hg` · 96421278
      Gregory Szorc authored
      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
      96421278
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