annotate rust/hg-cpython/src/parsers.rs @ 42748:7cae6bc29ff9

rust-parsers: switch to parse/pack_dirstate to mutate-on-loop

Both `parse_dirstate` and `pack_dirstate` can operate directly on the data
they're passed, which prevents the creation of intermediate data structures,
simplifies the function signatures and reduces boilerplate. They are exposed
directly to the Python for now, but a later patch will make use of them inside
`hg-core`.

Differential Revision: https://phab.mercurial-scm.org/D6628

// parsers.rs
//
// Copyright 2019 Raphaël Gomès <[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::dirstate::parsers` module provided by the
//! `hg-core` package.
//!
//! From Python, this will be seen as `mercurial.rustext.parsers`
//!
use cpython::{
    exc, PyBytes, PyDict, PyErr, PyInt, PyModule, PyResult, PyTuple, Python,
    ToPyObject,
};
use hg::{
    pack_dirstate, parse_dirstate, utils::copy_into_array, DirstateEntry,
    DirstatePackError, DirstateParents, DirstateParseError, PARENT_SIZE,
};
use std::collections::HashMap;

use libc::c_char;

use crate::dirstate::{decapsule_make_dirstate_tuple, extract_dirstate};
use std::time::Duration;

fn parse_dirstate_wrapper(
    py: Python,
    dmap: PyDict,
    copymap: PyDict,
    st: PyBytes,
) -> PyResult<PyTuple> {
    let mut dirstate_map = HashMap::new();
    let mut copies = HashMap::new();

    match parse_dirstate(&mut dirstate_map, &mut copies, st.data(py)) {
        Ok(parents) => {
            for (filename, entry) in dirstate_map {
                dmap.set_item(
                    py,
                    PyBytes::new(py, &filename),
                    decapsule_make_dirstate_tuple(py)?(
                        entry.state as c_char,
                        entry.mode,
                        entry.size,
                        entry.mtime,
                    ),
                )?;
            }
            for (path, copy_path) in copies {
                copymap.set_item(
                    py,
                    PyBytes::new(py, &path),
                    PyBytes::new(py, &copy_path),
                )?;
            }
            Ok(
                (PyBytes::new(py, &parents.p1), PyBytes::new(py, &parents.p2))
                    .to_py_object(py),
            )
        }
        Err(e) => Err(PyErr::new::<exc::ValueError, _>(
            py,
            match e {
                DirstateParseError::TooLittleData => {
                    "too little data for parents".to_string()
                }
                DirstateParseError::Overflow => {
                    "overflow in dirstate".to_string()
                }
                DirstateParseError::CorruptedEntry(e) => e,
                DirstateParseError::Damaged => {
                    "dirstate appears to be damaged".to_string()
                }
            },
        )),
    }
}

fn pack_dirstate_wrapper(
    py: Python,
    dmap: PyDict,
    copymap: PyDict,
    pl: PyTuple,
    now: PyInt,
) -> PyResult<PyBytes> {
    let p1 = pl.get_item(py, 0).extract::<PyBytes>(py)?;
    let p1: &[u8] = p1.data(py);
    let p2 = pl.get_item(py, 1).extract::<PyBytes>(py)?;
    let p2: &[u8] = p2.data(py);

    let mut dirstate_map = extract_dirstate(py, &dmap)?;

    let copies: Result<HashMap<Vec<u8>, Vec<u8>>, PyErr> = copymap
        .items(py)
        .iter()
        .map(|(key, value)| {
            Ok((
                key.extract::<PyBytes>(py)?.data(py).to_owned(),
                value.extract::<PyBytes>(py)?.data(py).to_owned(),
            ))
        })
        .collect();

    if p1.len() != PARENT_SIZE || p2.len() != PARENT_SIZE {
        return Err(PyErr::new::<exc::ValueError, _>(
            py,
            "expected a 20-byte hash".to_string(),
        ));
    }

    match pack_dirstate(
        &mut dirstate_map,
        &copies?,
        DirstateParents {
            p1: copy_into_array(&p1),
            p2: copy_into_array(&p2),
        },
        Duration::from_secs(now.value(py) as u64),
    ) {
        Ok(packed) => {
            for (
                filename,
                DirstateEntry {
                    state,
                    mode,
                    size,
                    mtime,
                },
            ) in dirstate_map
            {
                dmap.set_item(
                    py,
                    PyBytes::new(py, &filename[..]),
                    decapsule_make_dirstate_tuple(py)?(
                        state as c_char,
                        mode,
                        size,
                        mtime,
                    ),
                )?;
            }
            Ok(PyBytes::new(py, &packed))
        }
        Err(error) => Err(PyErr::new::<exc::ValueError, _>(
            py,
            match error {
                DirstatePackError::CorruptedParent => {
                    "expected a 20-byte hash".to_string()
                }
                DirstatePackError::CorruptedEntry(e) => e,
                DirstatePackError::BadSize(expected, actual) => {
                    format!("bad dirstate size: {} != {}", actual, expected)
                }
            },
        )),
    }
}

/// Create the module, with `__package__` given from parent
pub fn init_parsers_module(py: Python, package: &str) -> PyResult<PyModule> {
    let dotted_name = &format!("{}.parsers", package);
    let m = PyModule::new(py, dotted_name)?;

    m.add(py, "__package__", package)?;
    m.add(py, "__doc__", "Parsers - Rust implementation")?;

    m.add(
        py,
        "parse_dirstate",
        py_fn!(
            py,
            parse_dirstate_wrapper(dmap: PyDict, copymap: PyDict, st: PyBytes)
        ),
    )?;
    m.add(
        py,
        "pack_dirstate",
        py_fn!(
            py,
            pack_dirstate_wrapper(
                dmap: PyDict,
                copymap: PyDict,
                pl: PyTuple,
                now: PyInt
            )
        ),
    )?;

    let sys = PyModule::import(py, "sys")?;
    let sys_modules: PyDict = sys.get(py, "modules")?.extract(py)?;
    sys_modules.set_item(py, dotted_name, &m)?;

    Ok(m)
}