rust/hg-core/src/dirstate.rs

dirstate-tree: Add the new `status()` algorithm

With the dirstate organized in a tree that mirrors the structure of the
filesystem tree, we can traverse both trees at the same time in order to
compare them. This is hopefully more efficient that building multiple
big hashmaps for all of the repository’s contents.

Differential Revision: https://phab.mercurial-scm.org/D10547

// dirstate module
//
// 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.

use crate::errors::HgError;
use crate::revlog::Node;
use crate::{utils::hg_path::HgPathBuf, FastHashMap};
use bytes_cast::{unaligned, BytesCast};
use std::convert::TryFrom;

pub mod dirs_multiset;
pub mod dirstate_map;
pub mod parsers;
pub mod status;

#[derive(Debug, PartialEq, Clone, BytesCast)]
#[repr(C)]
pub struct DirstateParents {
    pub p1: Node,
    pub p2: Node,
}

/// The C implementation uses all signed types. This will be an issue
/// either when 4GB+ source files are commonplace or in 2038, whichever
/// comes first.
#[derive(Debug, PartialEq, Copy, Clone)]
pub struct DirstateEntry {
    pub state: EntryState,
    pub mode: i32,
    pub mtime: i32,
    pub size: i32,
}

impl DirstateEntry {
    pub fn is_non_normal(&self) -> bool {
        self.state != EntryState::Normal || self.mtime == MTIME_UNSET
    }

    pub fn is_from_other_parent(&self) -> bool {
        self.state == EntryState::Normal && self.size == SIZE_FROM_OTHER_PARENT
    }

    // TODO: other platforms
    #[cfg(unix)]
    pub fn mode_changed(
        &self,
        filesystem_metadata: &std::fs::Metadata,
    ) -> bool {
        use std::os::unix::fs::MetadataExt;
        const EXEC_BIT_MASK: u32 = 0o100;
        let dirstate_exec_bit = (self.mode as u32) & EXEC_BIT_MASK;
        let fs_exec_bit = filesystem_metadata.mode() & EXEC_BIT_MASK;
        dirstate_exec_bit != fs_exec_bit
    }
}

#[derive(BytesCast)]
#[repr(C)]
struct RawEntry {
    state: u8,
    mode: unaligned::I32Be,
    size: unaligned::I32Be,
    mtime: unaligned::I32Be,
    length: unaligned::I32Be,
}

const MTIME_UNSET: i32 = -1;

/// A `DirstateEntry` with a size of `-2` means that it was merged from the
/// other parent. This allows revert to pick the right status back during a
/// merge.
pub const SIZE_FROM_OTHER_PARENT: i32 = -2;

pub type StateMap = FastHashMap<HgPathBuf, DirstateEntry>;
pub type StateMapIter<'a> =
    Box<dyn Iterator<Item = (&'a HgPathBuf, &'a DirstateEntry)> + Send + 'a>;

pub type CopyMap = FastHashMap<HgPathBuf, HgPathBuf>;
pub type CopyMapIter<'a> =
    Box<dyn Iterator<Item = (&'a HgPathBuf, &'a HgPathBuf)> + Send + 'a>;

#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum EntryState {
    Normal,
    Added,
    Removed,
    Merged,
    Unknown,
}

impl EntryState {
    pub fn is_tracked(self) -> bool {
        use EntryState::*;
        match self {
            Normal | Added | Merged => true,
            Removed | Unknown => false,
        }
    }
}

impl TryFrom<u8> for EntryState {
    type Error = HgError;

    fn try_from(value: u8) -> Result<Self, Self::Error> {
        match value {
            b'n' => Ok(EntryState::Normal),
            b'a' => Ok(EntryState::Added),
            b'r' => Ok(EntryState::Removed),
            b'm' => Ok(EntryState::Merged),
            b'?' => Ok(EntryState::Unknown),
            _ => Err(HgError::CorruptedRepository(format!(
                "Incorrect dirstate entry state {}",
                value
            ))),
        }
    }
}

impl Into<u8> for EntryState {
    fn into(self) -> u8 {
        match self {
            EntryState::Normal => b'n',
            EntryState::Added => b'a',
            EntryState::Removed => b'r',
            EntryState::Merged => b'm',
            EntryState::Unknown => b'?',
        }
    }
}