view rust/hg-cpython/src/discovery.rs @ 50979:4c5f6e95df84

rust: make `Revision` a newtype

This change is the one we've been building towards during this series.
The aim is to make `Revision` mean more than a simple integer, holding
the information that it is valid for a given revlog index.
While this still allows for programmer error, since creating a revision
directly and querying a different index with a "checked" revision are
still possible, the friction created by the newtype will hopefully make
us think twice about which type to use.

Enough of the Rust ecosystem relies on the newtype pattern to be
efficiently optimized away (even compiler in codegen tests¹), so I'm not
worried about this being a fundamental problem.

[1] https://github.com/rust-lang/rust/blob/7a70647f195f6b0a0f1ebd72b1542ba91a32f43a/tests/codegen/vec-in-place.rs#L47

// discovery.rs
//
// Copyright 2018 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::discovery` module provided by the
//! `hg-core` crate. From Python, this will be seen as `rustext.discovery`
//!
//! # Classes visible from Python:
//! - [`PartialDiscover`] is the Rust implementation of
//!   `mercurial.setdiscovery.partialdiscovery`.

use crate::PyRevision;
use crate::{
    cindex::Index, conversion::rev_pyiter_collect, exceptions::GraphError,
};
use cpython::{
    ObjectProtocol, PyClone, PyDict, PyModule, PyObject, PyResult, PyTuple,
    Python, PythonObject, ToPyObject,
};
use hg::discovery::PartialDiscovery as CorePartialDiscovery;
use hg::Revision;
use std::collections::HashSet;

use std::cell::RefCell;

use crate::revlog::pyindex_to_graph;

py_class!(pub class PartialDiscovery |py| {
    data inner: RefCell<Box<CorePartialDiscovery<Index>>>;
    data index: RefCell<Index>;

    // `_respectsize` is currently only here to replicate the Python API and
    // will be used in future patches inside methods that are yet to be
    // implemented.
    def __new__(
        _cls,
        repo: PyObject,
        targetheads: PyObject,
        respectsize: bool,
        randomize: bool = true
    ) -> PyResult<PartialDiscovery> {
        let index = repo.getattr(py, "changelog")?.getattr(py, "index")?;
        let index = pyindex_to_graph(py, index)?;
        let target_heads = rev_pyiter_collect(py, &targetheads, &index)?;
        Self::create_instance(
            py,
            RefCell::new(Box::new(CorePartialDiscovery::new(
                index.clone_ref(py),
                target_heads,
                respectsize,
                randomize,
            ))),
            RefCell::new(index),
        )
    }

    def addcommons(&self, commons: PyObject) -> PyResult<PyObject> {
        let index = self.index(py).borrow();
        let commons_vec: Vec<_> = rev_pyiter_collect(py, &commons, &*index)?;
        let mut inner = self.inner(py).borrow_mut();
        inner.add_common_revisions(commons_vec)
        .map_err(|e| GraphError::pynew(py, e))?;
    Ok(py.None())
}

    def addmissings(&self, missings: PyObject) -> PyResult<PyObject> {
        let index = self.index(py).borrow();
        let missings_vec: Vec<_> = rev_pyiter_collect(py, &missings, &*index)?;
        let mut inner = self.inner(py).borrow_mut();
        inner.add_missing_revisions(missings_vec)
            .map_err(|e| GraphError::pynew(py, e))?;
        Ok(py.None())
    }

    def addinfo(&self, sample: PyObject) -> PyResult<PyObject> {
        let mut missing: Vec<Revision> = Vec::new();
        let mut common: Vec<Revision> = Vec::new();
        for info in sample.iter(py)? { // info is a pair (Revision, bool)
            let mut revknown = info?.iter(py)?;
            let rev: PyRevision = revknown.next().unwrap()?.extract(py)?;
            // This is fine since we're just using revisions as integers
            // for the purposes of discovery
            let rev = Revision(rev.0);
            let known: bool = revknown.next().unwrap()?.extract(py)?;
            if known {
                common.push(rev);
            } else {
                missing.push(rev);
            }
        }
        let mut inner = self.inner(py).borrow_mut();
        inner.add_common_revisions(common)
            .map_err(|e| GraphError::pynew(py, e))?;
        inner.add_missing_revisions(missing)
            .map_err(|e| GraphError::pynew(py, e))?;
        Ok(py.None())
    }

    def hasinfo(&self) -> PyResult<bool> {
        Ok(self.inner(py).borrow().has_info())
    }

    def iscomplete(&self) -> PyResult<bool> {
        Ok(self.inner(py).borrow().is_complete())
    }

    def stats(&self) -> PyResult<PyDict> {
        let stats = self.inner(py).borrow().stats();
        let as_dict: PyDict = PyDict::new(py);
        as_dict.set_item(py, "undecided",
                         stats.undecided.map(
                             |l| l.to_py_object(py).into_object())
                             .unwrap_or_else(|| py.None()))?;
        Ok(as_dict)
    }

    def commonheads(&self) -> PyResult<HashSet<PyRevision>> {
        let res = self.inner(py).borrow().common_heads()
                    .map_err(|e| GraphError::pynew(py, e))?;
        Ok(res.into_iter().map(Into::into).collect())
    }

    def takefullsample(&self, _headrevs: PyObject,
                       size: usize) -> PyResult<PyObject> {
        let mut inner = self.inner(py).borrow_mut();
        let sample = inner.take_full_sample(size)
            .map_err(|e| GraphError::pynew(py, e))?;
        let as_vec: Vec<PyObject> = sample
            .iter()
            .map(|rev| PyRevision(rev.0).to_py_object(py).into_object())
            .collect();
        Ok(PyTuple::new(py, as_vec.as_slice()).into_object())
    }

    def takequicksample(&self, headrevs: PyObject,
                        size: usize) -> PyResult<PyObject> {
        let index = self.index(py).borrow();
        let mut inner = self.inner(py).borrow_mut();
        let revsvec: Vec<_> = rev_pyiter_collect(py, &headrevs, &*index)?;
        let sample = inner.take_quick_sample(revsvec, size)
            .map_err(|e| GraphError::pynew(py, e))?;
        let as_vec: Vec<PyObject> = sample
            .iter()
            .map(|rev| PyRevision(rev.0).to_py_object(py).into_object())
            .collect();
        Ok(PyTuple::new(py, as_vec.as_slice()).into_object())
    }

});

/// Create the module, with __package__ given from parent
pub fn init_module(py: Python, package: &str) -> PyResult<PyModule> {
    let dotted_name = &format!("{}.discovery", package);
    let m = PyModule::new(py, dotted_name)?;
    m.add(py, "__package__", package)?;
    m.add(
        py,
        "__doc__",
        "Discovery of common node sets - Rust implementation",
    )?;
    m.add_class::<PartialDiscovery>(py)?;

    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)
}