dirstate-tree: optimize HashMap lookups with raw_entry_mut This switches to using `HashMap` from the hashbrown crate, in order to use its `raw_entry_mut` method. The standard library?s `HashMap` is also based on this same crate, but `raw_entry_mut` is not yet stable there: https://github.com/rust-lang/rust/issues/56167 Using version 0.9 because 0.10 is yanked and 0.11?requires Rust 1.49 This replaces in `DirstateMap::get_or_insert_node` a call to `HashMap<K, V>::entry` with `K = WithBasename<Cow<'on_disk, HgPath>>`. `entry` takes and consumes an "owned" `key: K` parameter, in case a new entry ends up inserted. This key is converted by `to_cow` from a value that borrows the `'path` lifetime. When this function is called by `Dirstate::new_v1`, `'path` is in fact the same as `'on_disk` so `to_cow` can return an owned key that contains `Cow::Borrowed`. For other callers, `to_cow` needs to create a `Cow::Owned` and thus make a costly heap memory allocation. This is wasteful if this key was already present in the map. Even when inserting a new node this is typically the case for its ancestor nodes (assuming most directories have numerous descendants). Differential Revision: https://phab.mercurial-scm.org/D12317

// debugdata.rs
//
// Copyright 2020 Antoine Cezar <antoine.cezar@octobus.net>
//
// 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::repo::Repo;
use crate::revlog::revlog::{Revlog, RevlogError};

/// Kind of data to debug
#[derive(Debug, Copy, Clone)]
pub enum DebugDataKind {
    Changelog,
    Manifest,
}

/// Dump the contents data of a revision.
pub fn debug_data(
    repo: &Repo,
    revset: &str,
    kind: DebugDataKind,
) -> Result<Vec<u8>, RevlogError> {
    let index_file = match kind {
        DebugDataKind::Changelog => "00changelog.i",
        DebugDataKind::Manifest => "00manifest.i",
    };
    let revlog = Revlog::open(repo, index_file, None)?;
    let rev =
        crate::revset::resolve_rev_number_or_hex_prefix(revset, &revlog)?;
    let data = revlog.get_rev_data(rev)?;
    Ok(data.into_owned())
}