comparison rust/hg-core/src/matchers.rs @ 51109:687e192dae16

rust-matchers: fix quadratic complexity in `FileMatcher`

Concretely, this command:

```
$ echo hg up -r <nodeid>; time hg revert dir1 dir2 -r <othernode> --debug
hg up -r <nodeid>

real	0m14.690s
user	0m14.766s
sys	0m5.430s
```

was much slower despite using 16 cores before this change.
The approach taken here is the same one used in match.py, in exactmatcher.

This changeset was originally written by Valentin Gatien-Baron in a private
repository.
I have redacted the commit message and did a minor clean up of the code.

51108:0250e45040f1

//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Structs and types for matching files and directories.

use crate::{
    dirstate::dirs_multiset::DirsChildrenMultiset,
    filepatterns::{
        build_single_regex, filter_subincludes, get_patterns_from_file,

    DirsMultiset, FastHashMap, IgnorePattern, PatternError, PatternSyntax,
};

use crate::dirstate::status::IgnoreFnType;
use crate::filepatterns::normalize_path_bytes;
use std::borrow::ToOwned;
use std::collections::HashSet;
use std::fmt::{Display, Error, Formatter};
use std::ops::Deref;
use std::path::{Path, PathBuf};

#[derive(Debug, PartialEq)]
pub enum VisitChildrenSet {
    /// Don't visit anything
    Empty,

/// ```
#[derive(Debug)]
pub struct FileMatcher {
    files: HashSet<HgPathBuf>,
    dirs: DirsMultiset,
}

impl FileMatcher {
    pub fn new(files: Vec<HgPathBuf>) -> Result<Self, HgPathError> {
        let dirs = DirsMultiset::from_manifest(&files)?;
        Ok(Self {
            files: HashSet::from_iter(files.into_iter()),
            dirs,
        })
    }
    fn inner_matches(&self, filename: &HgPath) -> bool {
        self.files.contains(filename.as_ref())
    }

    }
    fn matches(&self, filename: &HgPath) -> bool {
        self.inner_matches(filename)
    }
    fn visit_children_set(&self, directory: &HgPath) -> VisitChildrenSet {
        if self.files.is_empty() || !self.dirs.contains(&directory) {
            return VisitChildrenSet::Empty;
        }
        let mut candidates: HashSet<HgPathBuf> =
            self.dirs.iter().cloned().collect();

        candidates.extend(self.files.iter().cloned());
        candidates.remove(HgPath::new(b""));

        if !directory.as_ref().is_empty() {
            let directory = [directory.as_ref().as_bytes(), b"/"].concat();
            candidates = candidates
                .iter()
                .filter_map(|c| {
                    if c.as_bytes().starts_with(&directory) {
                        Some(HgPathBuf::from_bytes(
                            &c.as_bytes()[directory.len()..],
                        ))
                    } else {
                        None
                    }
                })
                .collect();
        }

        // `self.dirs` includes all of the directories, recursively, so if
        // we're attempting to match 'foo/bar/baz.txt', it'll have '', 'foo',
        // 'foo/bar' in it. Thus we can safely ignore a candidate that has a
        // '/' in it, indicating it's for a subdir-of-a-subdir; the immediate

51109:687e192dae16

//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Structs and types for matching files and directories.

use format_bytes::format_bytes;
use once_cell::sync::OnceCell;

use crate::{
    dirstate::dirs_multiset::DirsChildrenMultiset,
    filepatterns::{
        build_single_regex, filter_subincludes, get_patterns_from_file,

    DirsMultiset, FastHashMap, IgnorePattern, PatternError, PatternSyntax,
};

use crate::dirstate::status::IgnoreFnType;
use crate::filepatterns::normalize_path_bytes;
use std::collections::HashSet;
use std::fmt::{Display, Error, Formatter};
use std::ops::Deref;
use std::path::{Path, PathBuf};
use std::{borrow::ToOwned, collections::BTreeSet};

#[derive(Debug, PartialEq)]
pub enum VisitChildrenSet {
    /// Don't visit anything
    Empty,

/// ```
#[derive(Debug)]
pub struct FileMatcher {
    files: HashSet<HgPathBuf>,
    dirs: DirsMultiset,
    sorted_visitchildrenset_candidates: OnceCell<BTreeSet<HgPathBuf>>,
}

impl FileMatcher {
    pub fn new(files: Vec<HgPathBuf>) -> Result<Self, HgPathError> {
        let dirs = DirsMultiset::from_manifest(&files)?;
        Ok(Self {
            files: HashSet::from_iter(files.into_iter()),
            dirs,
            sorted_visitchildrenset_candidates: OnceCell::new(),
        })
    }
    fn inner_matches(&self, filename: &HgPath) -> bool {
        self.files.contains(filename.as_ref())
    }

    }
    fn matches(&self, filename: &HgPath) -> bool {
        self.inner_matches(filename)
    }
    fn visit_children_set(&self, directory: &HgPath) -> VisitChildrenSet {
        if self.files.is_empty() || !self.dirs.contains(directory) {
            return VisitChildrenSet::Empty;
        }

        let compute_candidates = || -> BTreeSet<HgPathBuf> {
            let mut candidates: BTreeSet<HgPathBuf> =
                self.dirs.iter().cloned().collect();
            candidates.extend(self.files.iter().cloned());
            candidates.remove(HgPath::new(b""));
            candidates
        };
        let candidates =
            if directory.as_ref().is_empty() {
                compute_candidates()
            } else {
                let sorted_candidates = self
                    .sorted_visitchildrenset_candidates
                    .get_or_init(compute_candidates);
                let directory_bytes = directory.as_ref().as_bytes();
                let start: HgPathBuf =
                    format_bytes!(b"{}/", directory_bytes).into();
                let start_len = start.len();
                // `0` sorts after `/`
                let end = format_bytes!(b"{}0", directory_bytes).into();
                BTreeSet::from_iter(sorted_candidates.range(start..end).map(
                    |c| HgPathBuf::from_bytes(&c.as_bytes()[start_len..]),
                ))
            };

        // `self.dirs` includes all of the directories, recursively, so if
        // we're attempting to match 'foo/bar/baz.txt', it'll have '', 'foo',
        // 'foo/bar' in it. Thus we can safely ignore a candidate that has a
        // '/' in it, indicating it's for a subdir-of-a-subdir; the immediate