annotate rust/hg-core/src/dirstate/dirstate_tree.rs @ 45562:b51167d70f5a

rust: add `dirstate_tree` module

Mercurial needs to represent the filesystem hierarchy on which it operates, for
example in the dirstate. Its current on-disk representation is an unsorted, flat
structure that gets transformed in the current Rust code into a `HashMap`.
This loses the hierarchical information of the dirstate, leading to some
unfortunate performance and algorithmic compromises.

This module adds an implementation of a radix tree that is specialized for
representing the dirstate: its unit is the path component. I have made no
efforts to optimize either its memory footprint or its insertion speed: they're
pretty bad for now.

Following will be a few patches that modify the dirstate.status logic to use
that new hierarchical information, fixing issue 6335 in the same swing.

Differential Revision: https://phab.mercurial-scm.org/D9085

// dirstate_tree.rs
//
// Copyright 2020, 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.

//! Special-case radix tree that matches a filesystem hierarchy for use in the
//! dirstate.
//! It has not been optimized at all yet.

pub mod iter;
pub mod node;
pub mod tree;