rust/hg-core/src/dirstate/status.rs

dirstate-tree: Make Rust DirstateMap bindings go through a trait object

This changeset starts a series that adds an experiment to make status faster
by changing the dirstate (first only in memory and later also on disk) to
be shaped as a tree matching the directory structure, instead of the current
flat collection of entries. The status algorithm can then traverse this tree
dirstate at the same time as it traverses the filesystem.

We (Octobus) have made prototypes that show promising results but are prone
to bitrot. We would like to start upstreaming some experimental Rust code that
goes in this direction, but to avoid disrupting users it should only be
enabled by some run-time opt-in while keeping the existing dirstate structure
and status algorithm as-is.

The `DirstateMap` type and `status` function look like the appropriate
boundary. This adds a new trait that abstracts everything Python bindings need
and makes those bindings go through a `dyn` trait object. Later we’ll have two
implementations of this trait, and the same bindings can use either.

Differential Revision: https://phab.mercurial-scm.org/D10362

// status.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.

//! Rust implementation of dirstate.status (dirstate.py).
//! It is currently missing a lot of functionality compared to the Python one
//! and will only be triggered in narrow cases.

use crate::utils::path_auditor::PathAuditor;
use crate::{
    dirstate::SIZE_FROM_OTHER_PARENT,
    filepatterns::PatternFileWarning,
    matchers::{get_ignore_function, Matcher, VisitChildrenSet},
    utils::{
        files::{find_dirs, HgMetadata},
        hg_path::{
            hg_path_to_path_buf, os_string_to_hg_path_buf, HgPath, HgPathBuf,
            HgPathError,
        },
    },
    CopyMap, DirstateEntry, DirstateMap, EntryState, FastHashMap,
    PatternError,
};
use lazy_static::lazy_static;
use micro_timer::timed;
use rayon::prelude::*;
use std::{
    borrow::Cow,
    collections::HashSet,
    fmt,
    fs::{read_dir, DirEntry},
    io::ErrorKind,
    ops::Deref,
    path::{Path, PathBuf},
};

/// Wrong type of file from a `BadMatch`
/// Note: a lot of those don't exist on all platforms.
#[derive(Debug, Copy, Clone)]
pub enum BadType {
    CharacterDevice,
    BlockDevice,
    FIFO,
    Socket,
    Directory,
    Unknown,
}

impl fmt::Display for BadType {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str(match self {
            BadType::CharacterDevice => "character device",
            BadType::BlockDevice => "block device",
            BadType::FIFO => "fifo",
            BadType::Socket => "socket",
            BadType::Directory => "directory",
            BadType::Unknown => "unknown",
        })
    }
}

/// Was explicitly matched but cannot be found/accessed
#[derive(Debug, Copy, Clone)]
pub enum BadMatch {
    OsError(i32),
    BadType(BadType),
}

/// Enum used to dispatch new status entries into the right collections.
/// Is similar to `crate::EntryState`, but represents the transient state of
/// entries during the lifetime of a command.
#[derive(Debug, Copy, Clone)]
pub enum Dispatch {
    Unsure,
    Modified,
    Added,
    Removed,
    Deleted,
    Clean,
    Unknown,
    Ignored,
    /// Empty dispatch, the file is not worth listing
    None,
    /// Was explicitly matched but cannot be found/accessed
    Bad(BadMatch),
    Directory {
        /// True if the directory used to be a file in the dmap so we can say
        /// that it's been removed.
        was_file: bool,
    },
}

type IoResult<T> = std::io::Result<T>;

/// `Box<dyn Trait>` is syntactic sugar for `Box<dyn Trait, 'static>`, so add
/// an explicit lifetime here to not fight `'static` bounds "out of nowhere".
type IgnoreFnType<'a> = Box<dyn for<'r> Fn(&'r HgPath) -> bool + Sync + 'a>;

/// We have a good mix of owned (from directory traversal) and borrowed (from
/// the dirstate/explicit) paths, this comes up a lot.
pub type HgPathCow<'a> = Cow<'a, HgPath>;

/// A path with its computed ``Dispatch`` information
type DispatchedPath<'a> = (HgPathCow<'a>, Dispatch);

/// The conversion from `HgPath` to a real fs path failed.
/// `22` is the error code for "Invalid argument"
const INVALID_PATH_DISPATCH: Dispatch = Dispatch::Bad(BadMatch::OsError(22));

/// Dates and times that are outside the 31-bit signed range are compared
/// modulo 2^31. This should prevent hg from behaving badly with very large
/// files or corrupt dates while still having a high probability of detecting
/// changes. (issue2608)
/// TODO I haven't found a way of having `b` be `Into<i32>`, since `From<u64>`
/// is not defined for `i32`, and there is no `As` trait. This forces the
/// caller to cast `b` as `i32`.
fn mod_compare(a: i32, b: i32) -> bool {
    a & i32::max_value() != b & i32::max_value()
}

/// Return a sorted list containing information about the entries
/// in the directory.
///
/// * `skip_dot_hg` - Return an empty vec if `path` contains a `.hg` directory
fn list_directory(
    path: impl AsRef<Path>,
    skip_dot_hg: bool,
) -> std::io::Result<Vec<(HgPathBuf, DirEntry)>> {
    let mut results = vec![];
    let entries = read_dir(path.as_ref())?;

    for entry in entries {
        let entry = entry?;
        let filename = os_string_to_hg_path_buf(entry.file_name())?;
        let file_type = entry.file_type()?;
        if skip_dot_hg && filename.as_bytes() == b".hg" && file_type.is_dir() {
            return Ok(vec![]);
        } else {
            results.push((filename, entry))
        }
    }

    results.sort_unstable_by_key(|e| e.0.clone());
    Ok(results)
}

/// The file corresponding to the dirstate entry was found on the filesystem.
fn dispatch_found(
    filename: impl AsRef<HgPath>,
    entry: DirstateEntry,
    metadata: HgMetadata,
    copy_map: &CopyMap,
    options: StatusOptions,
) -> Dispatch {
    let DirstateEntry {
        state,
        mode,
        mtime,
        size,
    } = entry;

    let HgMetadata {
        st_mode,
        st_size,
        st_mtime,
        ..
    } = metadata;

    match state {
        EntryState::Normal => {
            let size_changed = mod_compare(size, st_size as i32);
            let mode_changed =
                (mode ^ st_mode as i32) & 0o100 != 0o000 && options.check_exec;
            let metadata_changed = size >= 0 && (size_changed || mode_changed);
            let other_parent = size == SIZE_FROM_OTHER_PARENT;

            if metadata_changed
                || other_parent
                || copy_map.contains_key(filename.as_ref())
            {
                if metadata.is_symlink() && size_changed {
                    // issue6456: Size returned may be longer due to encryption
                    // on EXT-4 fscrypt. TODO maybe only do it on EXT4?
                    Dispatch::Unsure
                } else {
                    Dispatch::Modified
                }
            } else if mod_compare(mtime, st_mtime as i32)
                || st_mtime == options.last_normal_time
            {
                // the file may have just been marked as normal and
                // it may have changed in the same second without
                // changing its size. This can happen if we quickly
                // do multiple commits. Force lookup, so we don't
                // miss such a racy file change.
                Dispatch::Unsure
            } else if options.list_clean {
                Dispatch::Clean
            } else {
                Dispatch::None
            }
        }
        EntryState::Merged => Dispatch::Modified,
        EntryState::Added => Dispatch::Added,
        EntryState::Removed => Dispatch::Removed,
        EntryState::Unknown => Dispatch::Unknown,
    }
}

/// The file corresponding to this Dirstate entry is missing.
fn dispatch_missing(state: EntryState) -> Dispatch {
    match state {
        // File was removed from the filesystem during commands
        EntryState::Normal | EntryState::Merged | EntryState::Added => {
            Dispatch::Deleted
        }
        // File was removed, everything is normal
        EntryState::Removed => Dispatch::Removed,
        // File is unknown to Mercurial, everything is normal
        EntryState::Unknown => Dispatch::Unknown,
    }
}

fn dispatch_os_error(e: &std::io::Error) -> Dispatch {
    Dispatch::Bad(BadMatch::OsError(
        e.raw_os_error().expect("expected real OS error"),
    ))
}

lazy_static! {
    static ref DEFAULT_WORK: HashSet<&'static HgPath> = {
        let mut h = HashSet::new();
        h.insert(HgPath::new(b""));
        h
    };
}

#[derive(Debug, Copy, Clone)]
pub struct StatusOptions {
    /// Remember the most recent modification timeslot for status, to make
    /// sure we won't miss future size-preserving file content modifications
    /// that happen within the same timeslot.
    pub last_normal_time: i64,
    /// Whether we are on a filesystem with UNIX-like exec flags
    pub check_exec: bool,
    pub list_clean: bool,
    pub list_unknown: bool,
    pub list_ignored: bool,
    /// Whether to collect traversed dirs for applying a callback later.
    /// Used by `hg purge` for example.
    pub collect_traversed_dirs: bool,
}

#[derive(Debug)]
pub struct DirstateStatus<'a> {
    pub modified: Vec<HgPathCow<'a>>,
    pub added: Vec<HgPathCow<'a>>,
    pub removed: Vec<HgPathCow<'a>>,
    pub deleted: Vec<HgPathCow<'a>>,
    pub clean: Vec<HgPathCow<'a>>,
    pub ignored: Vec<HgPathCow<'a>>,
    pub unknown: Vec<HgPathCow<'a>>,
    pub bad: Vec<(HgPathCow<'a>, BadMatch)>,
    /// Only filled if `collect_traversed_dirs` is `true`
    pub traversed: Vec<HgPathBuf>,
}

#[derive(Debug, derive_more::From)]
pub enum StatusError {
    /// Generic IO error
    IO(std::io::Error),
    /// An invalid path that cannot be represented in Mercurial was found
    Path(HgPathError),
    /// An invalid "ignore" pattern was found
    Pattern(PatternError),
}

pub type StatusResult<T> = Result<T, StatusError>;

impl fmt::Display for StatusError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            StatusError::IO(error) => error.fmt(f),
            StatusError::Path(error) => error.fmt(f),
            StatusError::Pattern(error) => error.fmt(f),
        }
    }
}

/// Gives information about which files are changed in the working directory
/// and how, compared to the revision we're based on
pub struct Status<'a, M: ?Sized + Matcher + Sync> {
    dmap: &'a DirstateMap,
    pub(crate) matcher: &'a M,
    root_dir: PathBuf,
    pub(crate) options: StatusOptions,
    ignore_fn: IgnoreFnType<'a>,
}

impl<'a, M> Status<'a, M>
where
    M: ?Sized + Matcher + Sync,
{
    pub fn new(
        dmap: &'a DirstateMap,
        matcher: &'a M,
        root_dir: PathBuf,
        ignore_files: Vec<PathBuf>,
        options: StatusOptions,
    ) -> StatusResult<(Self, Vec<PatternFileWarning>)> {
        // Needs to outlive `dir_ignore_fn` since it's captured.

        let (ignore_fn, warnings): (IgnoreFnType, _) =
            if options.list_ignored || options.list_unknown {
                get_ignore_function(ignore_files, &root_dir)?
            } else {
                (Box::new(|&_| true), vec![])
            };

        Ok((
            Self {
                dmap,
                matcher,
                root_dir,
                options,
                ignore_fn,
            },
            warnings,
        ))
    }

    /// Is the path ignored?
    pub fn is_ignored(&self, path: impl AsRef<HgPath>) -> bool {
        (self.ignore_fn)(path.as_ref())
    }

    /// Is the path or one of its ancestors ignored?
    pub fn dir_ignore(&self, dir: impl AsRef<HgPath>) -> bool {
        // Only involve ignore mechanism if we're listing unknowns or ignored.
        if self.options.list_ignored || self.options.list_unknown {
            if self.is_ignored(&dir) {
                true
            } else {
                for p in find_dirs(dir.as_ref()) {
                    if self.is_ignored(p) {
                        return true;
                    }
                }
                false
            }
        } else {
            true
        }
    }

    /// Get stat data about the files explicitly specified by the matcher.
    /// Returns a tuple of the directories that need to be traversed and the
    /// files with their corresponding `Dispatch`.
    /// TODO subrepos
    #[timed]
    pub fn walk_explicit(
        &self,
        traversed_sender: crossbeam_channel::Sender<HgPathBuf>,
    ) -> (Vec<DispatchedPath<'a>>, Vec<DispatchedPath<'a>>) {
        self.matcher
            .file_set()
            .unwrap_or(&DEFAULT_WORK)
            .par_iter()
            .flat_map(|&filename| -> Option<_> {
                // TODO normalization
                let normalized = filename;

                let buf = match hg_path_to_path_buf(normalized) {
                    Ok(x) => x,
                    Err(_) => {
                        return Some((
                            Cow::Borrowed(normalized),
                            INVALID_PATH_DISPATCH,
                        ))
                    }
                };
                let target = self.root_dir.join(buf);
                let st = target.symlink_metadata();
                let in_dmap = self.dmap.get(normalized);
                match st {
                    Ok(meta) => {
                        let file_type = meta.file_type();
                        return if file_type.is_file() || file_type.is_symlink()
                        {
                            if let Some(entry) = in_dmap {
                                return Some((
                                    Cow::Borrowed(normalized),
                                    dispatch_found(
                                        &normalized,
                                        *entry,
                                        HgMetadata::from_metadata(meta),
                                        &self.dmap.copy_map,
                                        self.options,
                                    ),
                                ));
                            }
                            Some((
                                Cow::Borrowed(normalized),
                                Dispatch::Unknown,
                            ))
                        } else if file_type.is_dir() {
                            if self.options.collect_traversed_dirs {
                                traversed_sender
                                    .send(normalized.to_owned())
                                    .expect("receiver should outlive sender");
                            }
                            Some((
                                Cow::Borrowed(normalized),
                                Dispatch::Directory {
                                    was_file: in_dmap.is_some(),
                                },
                            ))
                        } else {
                            Some((
                                Cow::Borrowed(normalized),
                                Dispatch::Bad(BadMatch::BadType(
                                    // TODO do more than unknown
                                    // Support for all `BadType` variant
                                    // varies greatly between platforms.
                                    // So far, no tests check the type and
                                    // this should be good enough for most
                                    // users.
                                    BadType::Unknown,
                                )),
                            ))
                        };
                    }
                    Err(_) => {
                        if let Some(entry) = in_dmap {
                            return Some((
                                Cow::Borrowed(normalized),
                                dispatch_missing(entry.state),
                            ));
                        }
                    }
                };
                None
            })
            .partition(|(_, dispatch)| match dispatch {
                Dispatch::Directory { .. } => true,
                _ => false,
            })
    }

    /// Walk the working directory recursively to look for changes compared to
    /// the current `DirstateMap`.
    ///
    /// This takes a mutable reference to the results to account for the
    /// `extend` in timings
    #[timed]
    pub fn traverse(
        &self,
        path: impl AsRef<HgPath>,
        old_results: &FastHashMap<HgPathCow<'a>, Dispatch>,
        results: &mut Vec<DispatchedPath<'a>>,
        traversed_sender: crossbeam_channel::Sender<HgPathBuf>,
    ) {
        // The traversal is done in parallel, so use a channel to gather
        // entries. `crossbeam_channel::Sender` is `Sync`, while `mpsc::Sender`
        // is not.
        let (files_transmitter, files_receiver) =
            crossbeam_channel::unbounded();

        self.traverse_dir(
            &files_transmitter,
            path,
            &old_results,
            traversed_sender,
        );

        // Disconnect the channel so the receiver stops waiting
        drop(files_transmitter);

        let new_results = files_receiver
            .into_iter()
            .par_bridge()
            .map(|(f, d)| (Cow::Owned(f), d));

        results.par_extend(new_results);
    }

    /// Dispatch a single entry (file, folder, symlink...) found during
    /// `traverse`. If the entry is a folder that needs to be traversed, it
    /// will be handled in a separate thread.
    fn handle_traversed_entry<'b>(
        &'a self,
        scope: &rayon::Scope<'b>,
        files_sender: &'b crossbeam_channel::Sender<(HgPathBuf, Dispatch)>,
        old_results: &'a FastHashMap<Cow<HgPath>, Dispatch>,
        filename: HgPathBuf,
        dir_entry: DirEntry,
        traversed_sender: crossbeam_channel::Sender<HgPathBuf>,
    ) -> IoResult<()>
    where
        'a: 'b,
    {
        let file_type = dir_entry.file_type()?;
        let entry_option = self.dmap.get(&filename);

        if filename.as_bytes() == b".hg" {
            // Could be a directory or a symlink
            return Ok(());
        }

        if file_type.is_dir() {
            self.handle_traversed_dir(
                scope,
                files_sender,
                old_results,
                entry_option,
                filename,
                traversed_sender,
            );
        } else if file_type.is_file() || file_type.is_symlink() {
            if let Some(entry) = entry_option {
                if self.matcher.matches_everything()
                    || self.matcher.matches(&filename)
                {
                    let metadata = dir_entry.metadata()?;
                    files_sender
                        .send((
                            filename.to_owned(),
                            dispatch_found(
                                &filename,
                                *entry,
                                HgMetadata::from_metadata(metadata),
                                &self.dmap.copy_map,
                                self.options,
                            ),
                        ))
                        .unwrap();
                }
            } else if (self.matcher.matches_everything()
                || self.matcher.matches(&filename))
                && !self.is_ignored(&filename)
            {
                if (self.options.list_ignored
                    || self.matcher.exact_match(&filename))
                    && self.dir_ignore(&filename)
                {
                    if self.options.list_ignored {
                        files_sender
                            .send((filename.to_owned(), Dispatch::Ignored))
                            .unwrap();
                    }
                } else if self.options.list_unknown {
                    files_sender
                        .send((filename.to_owned(), Dispatch::Unknown))
                        .unwrap();
                }
            } else if self.is_ignored(&filename) && self.options.list_ignored {
                files_sender
                    .send((filename.to_owned(), Dispatch::Ignored))
                    .unwrap();
            }
        } else if let Some(entry) = entry_option {
            // Used to be a file or a folder, now something else.
            if self.matcher.matches_everything()
                || self.matcher.matches(&filename)
            {
                files_sender
                    .send((filename.to_owned(), dispatch_missing(entry.state)))
                    .unwrap();
            }
        }

        Ok(())
    }

    /// A directory was found in the filesystem and needs to be traversed
    fn handle_traversed_dir<'b>(
        &'a self,
        scope: &rayon::Scope<'b>,
        files_sender: &'b crossbeam_channel::Sender<(HgPathBuf, Dispatch)>,
        old_results: &'a FastHashMap<Cow<HgPath>, Dispatch>,
        entry_option: Option<&'a DirstateEntry>,
        directory: HgPathBuf,
        traversed_sender: crossbeam_channel::Sender<HgPathBuf>,
    ) where
        'a: 'b,
    {
        scope.spawn(move |_| {
            // Nested `if` until `rust-lang/rust#53668` is stable
            if let Some(entry) = entry_option {
                // Used to be a file, is now a folder
                if self.matcher.matches_everything()
                    || self.matcher.matches(&directory)
                {
                    files_sender
                        .send((
                            directory.to_owned(),
                            dispatch_missing(entry.state),
                        ))
                        .unwrap();
                }
            }
            // Do we need to traverse it?
            if !self.is_ignored(&directory) || self.options.list_ignored {
                self.traverse_dir(
                    files_sender,
                    directory,
                    &old_results,
                    traversed_sender,
                )
            }
        });
    }

    /// Decides whether the directory needs to be listed, and if so handles the
    /// entries in a separate thread.
    fn traverse_dir(
        &self,
        files_sender: &crossbeam_channel::Sender<(HgPathBuf, Dispatch)>,
        directory: impl AsRef<HgPath>,
        old_results: &FastHashMap<Cow<HgPath>, Dispatch>,
        traversed_sender: crossbeam_channel::Sender<HgPathBuf>,
    ) {
        let directory = directory.as_ref();

        if self.options.collect_traversed_dirs {
            traversed_sender
                .send(directory.to_owned())
                .expect("receiver should outlive sender");
        }

        let visit_entries = match self.matcher.visit_children_set(directory) {
            VisitChildrenSet::Empty => return,
            VisitChildrenSet::This | VisitChildrenSet::Recursive => None,
            VisitChildrenSet::Set(set) => Some(set),
        };
        let buf = match hg_path_to_path_buf(directory) {
            Ok(b) => b,
            Err(_) => {
                files_sender
                    .send((directory.to_owned(), INVALID_PATH_DISPATCH))
                    .expect("receiver should outlive sender");
                return;
            }
        };
        let dir_path = self.root_dir.join(buf);

        let skip_dot_hg = !directory.as_bytes().is_empty();
        let entries = match list_directory(dir_path, skip_dot_hg) {
            Err(e) => {
                files_sender
                    .send((directory.to_owned(), dispatch_os_error(&e)))
                    .expect("receiver should outlive sender");
                return;
            }
            Ok(entries) => entries,
        };

        rayon::scope(|scope| {
            for (filename, dir_entry) in entries {
                if let Some(ref set) = visit_entries {
                    if !set.contains(filename.deref()) {
                        continue;
                    }
                }
                // TODO normalize
                let filename = if directory.is_empty() {
                    filename.to_owned()
                } else {
                    directory.join(&filename)
                };

                if !old_results.contains_key(filename.deref()) {
                    match self.handle_traversed_entry(
                        scope,
                        files_sender,
                        old_results,
                        filename,
                        dir_entry,
                        traversed_sender.clone(),
                    ) {
                        Err(e) => {
                            files_sender
                                .send((
                                    directory.to_owned(),
                                    dispatch_os_error(&e),
                                ))
                                .expect("receiver should outlive sender");
                        }
                        Ok(_) => {}
                    }
                }
            }
        })
    }

    /// Add the files in the dirstate to the results.
    ///
    /// This takes a mutable reference to the results to account for the
    /// `extend` in timings
    #[timed]
    pub fn extend_from_dmap(&self, results: &mut Vec<DispatchedPath<'a>>) {
        results.par_extend(
            self.dmap
                .par_iter()
                .filter(|(path, _)| self.matcher.matches(path))
                .map(move |(filename, entry)| {
                    let filename: &HgPath = filename;
                    let filename_as_path = match hg_path_to_path_buf(filename)
                    {
                        Ok(f) => f,
                        Err(_) => {
                            return (
                                Cow::Borrowed(filename),
                                INVALID_PATH_DISPATCH,
                            )
                        }
                    };
                    let meta = self
                        .root_dir
                        .join(filename_as_path)
                        .symlink_metadata();
                    match meta {
                        Ok(m)
                            if !(m.file_type().is_file()
                                || m.file_type().is_symlink()) =>
                        {
                            (
                                Cow::Borrowed(filename),
                                dispatch_missing(entry.state),
                            )
                        }
                        Ok(m) => (
                            Cow::Borrowed(filename),
                            dispatch_found(
                                filename,
                                *entry,
                                HgMetadata::from_metadata(m),
                                &self.dmap.copy_map,
                                self.options,
                            ),
                        ),
                        Err(e)
                            if e.kind() == ErrorKind::NotFound
                                || e.raw_os_error() == Some(20) =>
                        {
                            // Rust does not yet have an `ErrorKind` for
                            // `NotADirectory` (errno 20)
                            // It happens if the dirstate contains `foo/bar`
                            // and foo is not a
                            // directory
                            (
                                Cow::Borrowed(filename),
                                dispatch_missing(entry.state),
                            )
                        }
                        Err(e) => {
                            (Cow::Borrowed(filename), dispatch_os_error(&e))
                        }
                    }
                }),
        );
    }

    /// Checks all files that are in the dirstate but were not found during the
    /// working directory traversal. This means that the rest must
    /// be either ignored, under a symlink or under a new nested repo.
    ///
    /// This takes a mutable reference to the results to account for the
    /// `extend` in timings
    #[timed]
    pub fn handle_unknowns(&self, results: &mut Vec<DispatchedPath<'a>>) {
        let to_visit: Vec<(&HgPath, &DirstateEntry)> =
            if results.is_empty() && self.matcher.matches_everything() {
                self.dmap.iter().map(|(f, e)| (f.deref(), e)).collect()
            } else {
                // Only convert to a hashmap if needed.
                let old_results: FastHashMap<_, _> =
                    results.iter().cloned().collect();
                self.dmap
                    .iter()
                    .filter_map(move |(f, e)| {
                        if !old_results.contains_key(f.deref())
                            && self.matcher.matches(f)
                        {
                            Some((f.deref(), e))
                        } else {
                            None
                        }
                    })
                    .collect()
            };

        let path_auditor = PathAuditor::new(&self.root_dir);

        let new_results = to_visit.into_par_iter().filter_map(
            |(filename, entry)| -> Option<_> {
                // Report ignored items in the dmap as long as they are not
                // under a symlink directory.
                if path_auditor.check(filename) {
                    // TODO normalize for case-insensitive filesystems
                    let buf = match hg_path_to_path_buf(filename) {
                        Ok(x) => x,
                        Err(_) => {
                            return Some((
                                Cow::Owned(filename.to_owned()),
                                INVALID_PATH_DISPATCH,
                            ));
                        }
                    };
                    Some((
                        Cow::Owned(filename.to_owned()),
                        match self.root_dir.join(&buf).symlink_metadata() {
                            // File was just ignored, no links, and exists
                            Ok(meta) => {
                                let metadata = HgMetadata::from_metadata(meta);
                                dispatch_found(
                                    filename,
                                    *entry,
                                    metadata,
                                    &self.dmap.copy_map,
                                    self.options,
                                )
                            }
                            // File doesn't exist
                            Err(_) => dispatch_missing(entry.state),
                        },
                    ))
                } else {
                    // It's either missing or under a symlink directory which
                    // we, in this case, report as missing.
                    Some((
                        Cow::Owned(filename.to_owned()),
                        dispatch_missing(entry.state),
                    ))
                }
            },
        );

        results.par_extend(new_results);
    }
}

#[timed]
pub fn build_response<'a>(
    results: impl IntoIterator<Item = DispatchedPath<'a>>,
    traversed: Vec<HgPathBuf>,
) -> (Vec<HgPathCow<'a>>, DirstateStatus<'a>) {
    let mut lookup = vec![];
    let mut modified = vec![];
    let mut added = vec![];
    let mut removed = vec![];
    let mut deleted = vec![];
    let mut clean = vec![];
    let mut ignored = vec![];
    let mut unknown = vec![];
    let mut bad = vec![];

    for (filename, dispatch) in results.into_iter() {
        match dispatch {
            Dispatch::Unknown => unknown.push(filename),
            Dispatch::Unsure => lookup.push(filename),
            Dispatch::Modified => modified.push(filename),
            Dispatch::Added => added.push(filename),
            Dispatch::Removed => removed.push(filename),
            Dispatch::Deleted => deleted.push(filename),
            Dispatch::Clean => clean.push(filename),
            Dispatch::Ignored => ignored.push(filename),
            Dispatch::None => {}
            Dispatch::Bad(reason) => bad.push((filename, reason)),
            Dispatch::Directory { .. } => {}
        }
    }

    (
        lookup,
        DirstateStatus {
            modified,
            added,
            removed,
            deleted,
            clean,
            ignored,
            unknown,
            bad,
            traversed,
        },
    )
}

/// Get the status of files in the working directory.
///
/// This is the current entry-point for `hg-core` and is realistically unusable
/// outside of a Python context because its arguments need to provide a lot of
/// information that will not be necessary in the future.
#[timed]
pub fn status<'a>(
    dmap: &'a DirstateMap,
    matcher: &'a (dyn Matcher + Sync),
    root_dir: PathBuf,
    ignore_files: Vec<PathBuf>,
    options: StatusOptions,
) -> StatusResult<(
    (Vec<HgPathCow<'a>>, DirstateStatus<'a>),
    Vec<PatternFileWarning>,
)> {
    let (status, warnings) =
        Status::new(dmap, matcher, root_dir, ignore_files, options)?;

    Ok((status.run()?, warnings))
}