annotate rust/hg-cpython/src/dagops.rs @ 46472:98e39f04d60e

upgrade: implement partial upgrade for upgrading persistent-nodemap

Upgrading repositories to use persistent nodemap should be fast and easy as it
requires only two things:

1) Updating the requirements
2) Writing a persistent-nodemap on disk

For both of the steps above, we don't need to edit existing revlogs.

This patch makes upgrade only do the above mentioned two steps if we are
only upgarding to use persistent-nodemap feature.

Since `nodemap.persist_nodemap()` assumes that there exists a nodemap file for
the given revlog if we are trying to call it, this patch adds `force` argument
to create a file if does not exist which is true in our upgrade case.

The test changes demonstrate that we no longer write nodemap files for manifest
after upgrade which I think is desirable.

Differential Revision: https://phab.mercurial-scm.org/D9936

// dagops.rs
//
// Copyright 2019 Georges Racinet <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Bindings for the `hg::dagops` module provided by the
//! `hg-core` package.
//!
//! From Python, this will be seen as `mercurial.rustext.dagop`
use crate::{conversion::rev_pyiter_collect, exceptions::GraphError};
use cpython::{PyDict, PyModule, PyObject, PyResult, Python};
use hg::dagops;
use hg::Revision;
use std::collections::HashSet;

use crate::revlog::pyindex_to_graph;

/// Using the the `index`, return heads out of any Python iterable of Revisions
///
/// This is the Rust counterpart for `mercurial.dagop.headrevs`
pub fn headrevs(
    py: Python,
    index: PyObject,
    revs: PyObject,
) -> PyResult<HashSet<Revision>> {
    let mut as_set: HashSet<Revision> = rev_pyiter_collect(py, &revs)?;
    dagops::retain_heads(&pyindex_to_graph(py, index)?, &mut as_set)
        .map_err(|e| GraphError::pynew(py, e))?;
    Ok(as_set)
}

/// Create the module, with `__package__` given from parent
pub fn init_module(py: Python, package: &str) -> PyResult<PyModule> {
    let dotted_name = &format!("{}.dagop", package);
    let m = PyModule::new(py, dotted_name)?;
    m.add(py, "__package__", package)?;
    m.add(py, "__doc__", "DAG operations - Rust implementation")?;
    m.add(
        py,
        "headrevs",
        py_fn!(py, headrevs(index: PyObject, revs: PyObject)),
    )?;

    let sys = PyModule::import(py, "sys")?;
    let sys_modules: PyDict = sys.get(py, "modules")?.extract(py)?;
    sys_modules.set_item(py, dotted_name, &m)?;
    // Example C code (see pyexpat.c and import.c) will "give away the
    // reference", but we won't because it will be consumed once the
    // Rust PyObject is dropped.
    Ok(m)
}