rust-dirstate: use a struct as arguments for the high-level `reset_state`

This makes the interface a lot clearer at the call site and prevents silly
mistakes, as an API with a bunch of booleans is prone to errors.

This refactor adds a `from_empty` parameter for a fast-path when resetting
and entry we're sure does not exist. It will be used in the upcoming update
Rust fastpath, and was not split to prevent more churn.

rust/hg-core/src/dirstate_tree/dirstate_map.rs

@@ -1,1935 +1,2051
 use bytes_cast::BytesCast;
 use std::borrow::Cow;
 use std::path::PathBuf;
 
 use super::on_disk;
 use super::on_disk::DirstateV2ParseError;
 use super::owning::OwningDirstateMap;
 use super::path_with_basename::WithBasename;
 use crate::dirstate::parsers::pack_entry;
 use crate::dirstate::parsers::packed_entry_size;
 use crate::dirstate::parsers::parse_dirstate_entries;
 use crate::dirstate::CopyMapIter;
 use crate::dirstate::DirstateV2Data;
 use crate::dirstate::ParentFileData;
 use crate::dirstate::StateMapIter;
 use crate::dirstate::TruncatedTimestamp;
 use crate::matchers::Matcher;
 use crate::utils::filter_map_results;
 use crate::utils::hg_path::{HgPath, HgPathBuf};
 use crate::DirstateEntry;
 use crate::DirstateError;
 use crate::DirstateMapError;
 use crate::DirstateParents;
 use crate::DirstateStatus;
 use crate::FastHashbrownMap as FastHashMap;
 use crate::PatternFileWarning;
 use crate::StatusError;
 use crate::StatusOptions;
 
 /// Append to an existing data file if the amount of unreachable data (not used
 /// anymore) is less than this fraction of the total amount of existing data.
 const ACCEPTABLE_UNREACHABLE_BYTES_RATIO: f32 = 0.5;
 
 #[derive(Debug, PartialEq, Eq)]
 /// Version of the on-disk format
 pub enum DirstateVersion {
     V1,
     V2,
 }
 
 #[derive(Debug, PartialEq, Eq)]
 pub enum DirstateMapWriteMode {
     Auto,
     ForceNewDataFile,
     ForceAppend,
 }
 
 #[derive(Debug)]
 pub struct DirstateMap<'on_disk> {
     /// Contents of the `.hg/dirstate` file
     pub(super) on_disk: &'on_disk [u8],
 
     pub(super) root: ChildNodes<'on_disk>,
 
     /// Number of nodes anywhere in the tree that have `.entry.is_some()`.
     pub(super) nodes_with_entry_count: u32,
 
     /// Number of nodes anywhere in the tree that have
     /// `.copy_source.is_some()`.
     pub(super) nodes_with_copy_source_count: u32,
 
     /// See on_disk::Header
     pub(super) ignore_patterns_hash: on_disk::IgnorePatternsHash,
 
     /// How many bytes of `on_disk` are not used anymore
     pub(super) unreachable_bytes: u32,
 
     /// Size of the data used to first load this `DirstateMap`. Used in case
     /// we need to write some new metadata, but no new data on disk,
     /// as well as to detect writes that have happened in another process
     /// since first read.
     pub(super) old_data_size: usize,
 
     /// UUID used when first loading this `DirstateMap`. Used to check if
     /// the UUID has been changed by another process since first read.
     /// Can be `None` if using dirstate v1 or if it's a brand new dirstate.
     pub(super) old_uuid: Option<Vec<u8>>,
 
     /// Identity of the dirstate file (for dirstate-v1) or the docket file
     /// (v2). Used to detect if the file has changed from another process.
     /// Since it's always written atomically, we can compare the inode to
     /// check the file identity.
     ///
     /// TODO On non-Unix systems, something like hashing is a possibility?
     pub(super) identity: Option<u64>,
 
     pub(super) dirstate_version: DirstateVersion,
 
     /// Controlled by config option `devel.dirstate.v2.data_update_mode`
     pub(super) write_mode: DirstateMapWriteMode,
 }
 
 /// Using a plain `HgPathBuf` of the full path from the repository root as a
 /// map key would also work: all paths in a given map have the same parent
 /// path, so comparing full paths gives the same result as comparing base
 /// names. However `HashMap` would waste time always re-hashing the same
 /// string prefix.
 pub(super) type NodeKey<'on_disk> = WithBasename<Cow<'on_disk, HgPath>>;
 
 /// Similar to `&'tree Cow<'on_disk, HgPath>`, but can also be returned
 /// for on-disk nodes that don’t actually have a `Cow` to borrow.
 #[derive(Debug)]
 pub(super) enum BorrowedPath<'tree, 'on_disk> {
     InMemory(&'tree HgPathBuf),
     OnDisk(&'on_disk HgPath),
 }
 
 #[derive(Debug)]
 pub(super) enum ChildNodes<'on_disk> {
     InMemory(FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>),
     OnDisk(&'on_disk [on_disk::Node]),
 }
 
 #[derive(Debug)]
 pub(super) enum ChildNodesRef<'tree, 'on_disk> {
     InMemory(&'tree FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>),
     OnDisk(&'on_disk [on_disk::Node]),
 }
 
 #[derive(Debug)]
 pub(super) enum NodeRef<'tree, 'on_disk> {
     InMemory(&'tree NodeKey<'on_disk>, &'tree Node<'on_disk>),
     OnDisk(&'on_disk on_disk::Node),
 }
 
 impl<'tree, 'on_disk> BorrowedPath<'tree, 'on_disk> {
     pub fn detach_from_tree(&self) -> Cow<'on_disk, HgPath> {
         match *self {
             BorrowedPath::InMemory(in_memory) => Cow::Owned(in_memory.clone()),
             BorrowedPath::OnDisk(on_disk) => Cow::Borrowed(on_disk),
         }
     }
 }
 
 impl<'tree, 'on_disk> std::ops::Deref for BorrowedPath<'tree, 'on_disk> {
     type Target = HgPath;
 
     fn deref(&self) -> &HgPath {
         match *self {
             BorrowedPath::InMemory(in_memory) => in_memory,
             BorrowedPath::OnDisk(on_disk) => on_disk,
         }
     }
 }
 
 impl Default for ChildNodes<'_> {
     fn default() -> Self {
         ChildNodes::InMemory(Default::default())
     }
 }
 
 impl<'on_disk> ChildNodes<'on_disk> {
     pub(super) fn as_ref<'tree>(
         &'tree self,
     ) -> ChildNodesRef<'tree, 'on_disk> {
         match self {
             ChildNodes::InMemory(nodes) => ChildNodesRef::InMemory(nodes),
             ChildNodes::OnDisk(nodes) => ChildNodesRef::OnDisk(nodes),
         }
     }
 
     pub(super) fn is_empty(&self) -> bool {
         match self {
             ChildNodes::InMemory(nodes) => nodes.is_empty(),
             ChildNodes::OnDisk(nodes) => nodes.is_empty(),
         }
     }
 
     fn make_mut(
         &mut self,
         on_disk: &'on_disk [u8],
         unreachable_bytes: &mut u32,
     ) -> Result<
         &mut FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>,
         DirstateV2ParseError,
     > {
         match self {
             ChildNodes::InMemory(nodes) => Ok(nodes),
             ChildNodes::OnDisk(nodes) => {
                 *unreachable_bytes +=
                     std::mem::size_of_val::<[on_disk::Node]>(*nodes) as u32;
                 let nodes = nodes
                     .iter()
                     .map(|node| {
                         Ok((
                             node.path(on_disk)?,
                             node.to_in_memory_node(on_disk)?,
                         ))
                     })
                     .collect::<Result<_, _>>()?;
                 *self = ChildNodes::InMemory(nodes);
                 match self {
                     ChildNodes::InMemory(nodes) => Ok(nodes),
                     ChildNodes::OnDisk(_) => unreachable!(),
                 }
             }
         }
     }
 }
 
 impl<'tree, 'on_disk> ChildNodesRef<'tree, 'on_disk> {
     pub(super) fn get(
         &self,
         base_name: &HgPath,
         on_disk: &'on_disk [u8],
     ) -> Result<Option<NodeRef<'tree, 'on_disk>>, DirstateV2ParseError> {
         match self {
             ChildNodesRef::InMemory(nodes) => Ok(nodes
                 .get_key_value(base_name)
                 .map(|(k, v)| NodeRef::InMemory(k, v))),
             ChildNodesRef::OnDisk(nodes) => {
                 let mut parse_result = Ok(());
                 let search_result = nodes.binary_search_by(|node| {
                     match node.base_name(on_disk) {
                         Ok(node_base_name) => node_base_name.cmp(base_name),
                         Err(e) => {
                             parse_result = Err(e);
                             // Dummy comparison result, `search_result` won’t
                             // be used since `parse_result` is an error
                             std::cmp::Ordering::Equal
                         }
                     }
                 });
                 parse_result.map(|()| {
                     search_result.ok().map(|i| NodeRef::OnDisk(&nodes[i]))
                 })
             }
         }
     }
 
     /// Iterate in undefined order
     pub(super) fn iter(
         &self,
     ) -> impl Iterator<Item = NodeRef<'tree, 'on_disk>> {
         match self {
             ChildNodesRef::InMemory(nodes) => itertools::Either::Left(
                 nodes.iter().map(|(k, v)| NodeRef::InMemory(k, v)),
             ),
             ChildNodesRef::OnDisk(nodes) => {
                 itertools::Either::Right(nodes.iter().map(NodeRef::OnDisk))
             }
         }
     }
 
     /// Iterate in parallel in undefined order
     pub(super) fn par_iter(
         &self,
     ) -> impl rayon::iter::ParallelIterator<Item = NodeRef<'tree, 'on_disk>>
     {
         use rayon::prelude::*;
         match self {
             ChildNodesRef::InMemory(nodes) => rayon::iter::Either::Left(
                 nodes.par_iter().map(|(k, v)| NodeRef::InMemory(k, v)),
             ),
             ChildNodesRef::OnDisk(nodes) => rayon::iter::Either::Right(
                 nodes.par_iter().map(NodeRef::OnDisk),
             ),
         }
     }
 
     pub(super) fn sorted(&self) -> Vec<NodeRef<'tree, 'on_disk>> {
         match self {
             ChildNodesRef::InMemory(nodes) => {
                 let mut vec: Vec<_> = nodes
                     .iter()
                     .map(|(k, v)| NodeRef::InMemory(k, v))
                     .collect();
                 fn sort_key<'a>(node: &'a NodeRef) -> &'a HgPath {
                     match node {
                         NodeRef::InMemory(path, _node) => path.base_name(),
                         NodeRef::OnDisk(_) => unreachable!(),
                     }
                 }
                 // `sort_unstable_by_key` doesn’t allow keys borrowing from the
                 // value: https://github.com/rust-lang/rust/issues/34162
                 vec.sort_unstable_by(|a, b| sort_key(a).cmp(sort_key(b)));
                 vec
             }
             ChildNodesRef::OnDisk(nodes) => {
                 // Nodes on disk are already sorted
                 nodes.iter().map(NodeRef::OnDisk).collect()
             }
         }
     }
 }
 
 impl<'tree, 'on_disk> NodeRef<'tree, 'on_disk> {
     pub(super) fn full_path(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<&'tree HgPath, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(path, _node) => Ok(path.full_path()),
             NodeRef::OnDisk(node) => node.full_path(on_disk),
         }
     }
 
     /// Returns a `BorrowedPath`, which can be turned into a `Cow<'on_disk,
     /// HgPath>` detached from `'tree`
     pub(super) fn full_path_borrowed(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<BorrowedPath<'tree, 'on_disk>, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(path, _node) => match path.full_path() {
                 Cow::Borrowed(on_disk) => Ok(BorrowedPath::OnDisk(on_disk)),
                 Cow::Owned(in_memory) => Ok(BorrowedPath::InMemory(in_memory)),
             },
             NodeRef::OnDisk(node) => {
                 Ok(BorrowedPath::OnDisk(node.full_path(on_disk)?))
             }
         }
     }
 
     pub(super) fn base_name(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<&'tree HgPath, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(path, _node) => Ok(path.base_name()),
             NodeRef::OnDisk(node) => node.base_name(on_disk),
         }
     }
 
     pub(super) fn children(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<ChildNodesRef<'tree, 'on_disk>, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(_path, node) => Ok(node.children.as_ref()),
             NodeRef::OnDisk(node) => {
                 Ok(ChildNodesRef::OnDisk(node.children(on_disk)?))
             }
         }
     }
 
     pub(super) fn has_copy_source(&self) -> bool {
         match self {
             NodeRef::InMemory(_path, node) => node.copy_source.is_some(),
             NodeRef::OnDisk(node) => node.has_copy_source(),
         }
     }
 
     pub(super) fn copy_source(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<Option<&'tree HgPath>, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(_path, node) => Ok(node.copy_source.as_deref()),
             NodeRef::OnDisk(node) => node.copy_source(on_disk),
         }
     }
     /// Returns a `BorrowedPath`, which can be turned into a `Cow<'on_disk,
     /// HgPath>` detached from `'tree`
     pub(super) fn copy_source_borrowed(
         &self,
         on_disk: &'on_disk [u8],
     ) -> Result<Option<BorrowedPath<'tree, 'on_disk>>, DirstateV2ParseError>
     {
         Ok(match self {
             NodeRef::InMemory(_path, node) => {
                 node.copy_source.as_ref().map(|source| match source {
                     Cow::Borrowed(on_disk) => BorrowedPath::OnDisk(on_disk),
                     Cow::Owned(in_memory) => BorrowedPath::InMemory(in_memory),
                 })
             }
             NodeRef::OnDisk(node) => {
                 node.copy_source(on_disk)?.map(BorrowedPath::OnDisk)
             }
         })
     }
 
     pub(super) fn entry(
         &self,
     ) -> Result<Option<DirstateEntry>, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(_path, node) => {
                 Ok(node.data.as_entry().copied())
             }
             NodeRef::OnDisk(node) => node.entry(),
         }
     }
 
     pub(super) fn cached_directory_mtime(
         &self,
     ) -> Result<Option<TruncatedTimestamp>, DirstateV2ParseError> {
         match self {
             NodeRef::InMemory(_path, node) => Ok(match node.data {
                 NodeData::CachedDirectory { mtime } => Some(mtime),
                 _ => None,
             }),
             NodeRef::OnDisk(node) => node.cached_directory_mtime(),
         }
     }
 
     pub(super) fn descendants_with_entry_count(&self) -> u32 {
         match self {
             NodeRef::InMemory(_path, node) => {
                 node.descendants_with_entry_count
             }
             NodeRef::OnDisk(node) => node.descendants_with_entry_count.get(),
         }
     }
 
     pub(super) fn tracked_descendants_count(&self) -> u32 {
         match self {
             NodeRef::InMemory(_path, node) => node.tracked_descendants_count,
             NodeRef::OnDisk(node) => node.tracked_descendants_count.get(),
         }
     }
 }
 
 /// Represents a file or a directory
 #[derive(Default, Debug)]
 pub(super) struct Node<'on_disk> {
     pub(super) data: NodeData,
 
     pub(super) copy_source: Option<Cow<'on_disk, HgPath>>,
 
     pub(super) children: ChildNodes<'on_disk>,
 
     /// How many (non-inclusive) descendants of this node have an entry.
     pub(super) descendants_with_entry_count: u32,
 
     /// How many (non-inclusive) descendants of this node have an entry whose
     /// state is "tracked".
     pub(super) tracked_descendants_count: u32,
 }
 
 #[derive(Debug, Default)]
 pub(super) enum NodeData {
     Entry(DirstateEntry),
     CachedDirectory {
         mtime: TruncatedTimestamp,
     },
     #[default]
     None,
 }
 
 impl NodeData {
     fn has_entry(&self) -> bool {
         matches!(self, NodeData::Entry(_))
     }
 
     fn as_entry(&self) -> Option<&DirstateEntry> {
         match self {
             NodeData::Entry(entry) => Some(entry),
             _ => None,
         }
     }
 
     fn as_entry_mut(&mut self) -> Option<&mut DirstateEntry> {
         match self {
             NodeData::Entry(entry) => Some(entry),
             _ => None,
         }
     }
 }
 
 impl<'on_disk> DirstateMap<'on_disk> {
     pub(super) fn empty(on_disk: &'on_disk [u8]) -> Self {
         Self {
             on_disk,
             root: ChildNodes::default(),
             nodes_with_entry_count: 0,
             nodes_with_copy_source_count: 0,
             ignore_patterns_hash: [0; on_disk::IGNORE_PATTERNS_HASH_LEN],
             unreachable_bytes: 0,
             old_data_size: 0,
             old_uuid: None,
             identity: None,
             dirstate_version: DirstateVersion::V1,
             write_mode: DirstateMapWriteMode::Auto,
         }
     }
 
     #[logging_timer::time("trace")]
     pub fn new_v2(
         on_disk: &'on_disk [u8],
         data_size: usize,
         metadata: &[u8],
         uuid: Vec<u8>,
         identity: Option<u64>,
     ) -> Result<Self, DirstateError> {
         if let Some(data) = on_disk.get(..data_size) {
             Ok(on_disk::read(data, metadata, uuid, identity)?)
         } else {
             Err(DirstateV2ParseError::new("not enough bytes on disk").into())
         }
     }
 
     #[logging_timer::time("trace")]
     pub fn new_v1(
         on_disk: &'on_disk [u8],
         identity: Option<u64>,
     ) -> Result<(Self, Option<DirstateParents>), DirstateError> {
         let mut map = Self::empty(on_disk);
         map.identity = identity;
 
         if map.on_disk.is_empty() {
             return Ok((map, None));
         }
 
         let parents = parse_dirstate_entries(
             map.on_disk,
             |path, entry, copy_source| {
                 let tracked = entry.tracked();
                 let node = Self::get_or_insert_node_inner(
                     map.on_disk,
                     &mut map.unreachable_bytes,
                     &mut map.root,
                     path,
                     WithBasename::to_cow_borrowed,
                     |ancestor| {
                         if tracked {
                             ancestor.tracked_descendants_count += 1
                         }
                         ancestor.descendants_with_entry_count += 1
                     },
                 )?;
                 assert!(
                     !node.data.has_entry(),
                     "duplicate dirstate entry in read"
                 );
                 assert!(
                     node.copy_source.is_none(),
                     "duplicate dirstate entry in read"
                 );
                 node.data = NodeData::Entry(*entry);
                 node.copy_source = copy_source.map(Cow::Borrowed);
                 map.nodes_with_entry_count += 1;
                 if copy_source.is_some() {
                     map.nodes_with_copy_source_count += 1
                 }
                 Ok(())
             },
         )?;
         let parents = Some(*parents);
 
         Ok((map, parents))
     }
 
     /// Assuming dirstate-v2 format, returns whether the next write should
     /// append to the existing data file that contains `self.on_disk` (true),
     /// or create a new data file from scratch (false).
     pub(super) fn write_should_append(&self) -> bool {
         match self.write_mode {
             DirstateMapWriteMode::ForceAppend => true,
             DirstateMapWriteMode::ForceNewDataFile => false,
             DirstateMapWriteMode::Auto => {
                 let ratio =
                     self.unreachable_bytes as f32 / self.on_disk.len() as f32;
                 ratio < ACCEPTABLE_UNREACHABLE_BYTES_RATIO
             }
         }
     }
 
     fn get_node<'tree>(
         &'tree self,
         path: &HgPath,
     ) -> Result<Option<NodeRef<'tree, 'on_disk>>, DirstateV2ParseError> {
         let mut children = self.root.as_ref();
         let mut components = path.components();
         let mut component =
             components.next().expect("expected at least one components");
         loop {
             if let Some(child) = children.get(component, self.on_disk)? {
                 if let Some(next_component) = components.next() {
                     component = next_component;
                     children = child.children(self.on_disk)?;
                 } else {
                     return Ok(Some(child));
                 }
             } else {
                 return Ok(None);
             }
         }
     }
 
     pub fn has_node(
         &self,
         path: &HgPath,
     ) -> Result<bool, DirstateV2ParseError> {
         let node = self.get_node(path)?;
         Ok(node.is_some())
     }
 
     /// Returns a mutable reference to the node at `path` if it exists
     ///
     /// `each_ancestor` is a callback that is called for each ancestor node
     /// when descending the tree. It is used to keep the different counters
     /// of the `DirstateMap` up-to-date.
     fn get_node_mut<'tree>(
         &'tree mut self,
         path: &HgPath,
         each_ancestor: impl FnMut(&mut Node),
     ) -> Result<Option<&'tree mut Node<'on_disk>>, DirstateV2ParseError> {
         Self::get_node_mut_inner(
             self.on_disk,
             &mut self.unreachable_bytes,
             &mut self.root,
             path,
             each_ancestor,
         )
     }
 
     /// Lower-level version of `get_node_mut`.
     ///
     /// This takes `root` instead of `&mut self` so that callers can mutate
     /// other fields while the returned borrow is still valid.
     ///
     /// `each_ancestor` is a callback that is called for each ancestor node
     /// when descending the tree. It is used to keep the different counters
     /// of the `DirstateMap` up-to-date.
     fn get_node_mut_inner<'tree>(
         on_disk: &'on_disk [u8],
         unreachable_bytes: &mut u32,
         root: &'tree mut ChildNodes<'on_disk>,
         path: &HgPath,
         mut each_ancestor: impl FnMut(&mut Node),
     ) -> Result<Option<&'tree mut Node<'on_disk>>, DirstateV2ParseError> {
         let mut children = root;
         let mut components = path.components();
         let mut component =
             components.next().expect("expected at least one components");
         loop {
             if let Some(child) = children
                 .make_mut(on_disk, unreachable_bytes)?
                 .get_mut(component)
             {
                 if let Some(next_component) = components.next() {
                     each_ancestor(child);
                     component = next_component;
                     children = &mut child.children;
                 } else {
                     return Ok(Some(child));
                 }
             } else {
                 return Ok(None);
             }
         }
     }
 
     /// Get a mutable reference to the node at `path`, creating it if it does
     /// not exist.
     ///
     /// `each_ancestor` is a callback that is called for each ancestor node
     /// when descending the tree. It is used to keep the different counters
     /// of the `DirstateMap` up-to-date.
     fn get_or_insert_node<'tree, 'path>(
         &'tree mut self,
         path: &'path HgPath,
         each_ancestor: impl FnMut(&mut Node),
     ) -> Result<&'tree mut Node<'on_disk>, DirstateV2ParseError> {
         Self::get_or_insert_node_inner(
             self.on_disk,
             &mut self.unreachable_bytes,
             &mut self.root,
             path,
             WithBasename::to_cow_owned,
             each_ancestor,
         )
     }
 
     /// Lower-level version of `get_or_insert_node_inner`, which is used when
     /// parsing disk data to remove allocations for new nodes.
     fn get_or_insert_node_inner<'tree, 'path>(
         on_disk: &'on_disk [u8],
         unreachable_bytes: &mut u32,
         root: &'tree mut ChildNodes<'on_disk>,
         path: &'path HgPath,
         to_cow: impl Fn(
             WithBasename<&'path HgPath>,
         ) -> WithBasename<Cow<'on_disk, HgPath>>,
         mut each_ancestor: impl FnMut(&mut Node),
     ) -> Result<&'tree mut Node<'on_disk>, DirstateV2ParseError> {
         let mut child_nodes = root;
         let mut inclusive_ancestor_paths =
             WithBasename::inclusive_ancestors_of(path);
         let mut ancestor_path = inclusive_ancestor_paths
             .next()
             .expect("expected at least one inclusive ancestor");
         loop {
             let (_, child_node) = child_nodes
                 .make_mut(on_disk, unreachable_bytes)?
                 .raw_entry_mut()
                 .from_key(ancestor_path.base_name())
                 .or_insert_with(|| (to_cow(ancestor_path), Node::default()));
             if let Some(next) = inclusive_ancestor_paths.next() {
                 each_ancestor(child_node);
                 ancestor_path = next;
                 child_nodes = &mut child_node.children;
             } else {
                 return Ok(child_node);
             }
         }
     }
 
     #[allow(clippy::too_many_arguments)]
     fn reset_state(
         &mut self,
         filename: &HgPath,
         old_entry_opt: Option<DirstateEntry>,
         wc_tracked: bool,
         p1_tracked: bool,
         p2_info: bool,
         has_meaningful_mtime: bool,
         parent_file_data_opt: Option<ParentFileData>,
     ) -> Result<(), DirstateError> {
         let (had_entry, was_tracked) = match old_entry_opt {
             Some(old_entry) => (true, old_entry.tracked()),
             None => (false, false),
         };
         let node = self.get_or_insert_node(filename, |ancestor| {
             if !had_entry {
                 ancestor.descendants_with_entry_count += 1;
             }
             if was_tracked {
                 if !wc_tracked {
                     ancestor.tracked_descendants_count = ancestor
                         .tracked_descendants_count
                         .checked_sub(1)
                         .expect("tracked count to be >= 0");
                 }
             } else if wc_tracked {
                 ancestor.tracked_descendants_count += 1;
             }
         })?;
 
         let v2_data = if let Some(parent_file_data) = parent_file_data_opt {
             DirstateV2Data {
                 wc_tracked,
                 p1_tracked,
                 p2_info,
                 mode_size: parent_file_data.mode_size,
                 mtime: if has_meaningful_mtime {
                     parent_file_data.mtime
                 } else {
                     None
                 },
                 ..Default::default()
             }
         } else {
             DirstateV2Data {
                 wc_tracked,
                 p1_tracked,
                 p2_info,
                 ..Default::default()
             }
         };
         node.data = NodeData::Entry(DirstateEntry::from_v2_data(v2_data));
         if !had_entry {
             self.nodes_with_entry_count += 1;
         }
         Ok(())
     }
 
     fn set_tracked(
         &mut self,
         filename: &HgPath,
         old_entry_opt: Option<DirstateEntry>,
     ) -> Result<bool, DirstateV2ParseError> {
         let was_tracked = old_entry_opt.map_or(false, |e| e.tracked());
         let had_entry = old_entry_opt.is_some();
         let tracked_count_increment = u32::from(!was_tracked);
         let mut new = false;
 
         let node = self.get_or_insert_node(filename, |ancestor| {
             if !had_entry {
                 ancestor.descendants_with_entry_count += 1;
             }
 
             ancestor.tracked_descendants_count += tracked_count_increment;
         })?;
         if let Some(old_entry) = old_entry_opt {
             let mut e = old_entry;
             if e.tracked() {
                 // XXX
                 // This is probably overkill for more case, but we need this to
                 // fully replace the `normallookup` call with `set_tracked`
                 // one. Consider smoothing this in the future.
                 e.set_possibly_dirty();
             } else {
                 new = true;
                 e.set_tracked();
             }
             node.data = NodeData::Entry(e)
         } else {
             node.data = NodeData::Entry(DirstateEntry::new_tracked());
             self.nodes_with_entry_count += 1;
             new = true;
         };
         Ok(new)
     }
 
     /// Set a node as untracked in the dirstate.
     ///
     /// It is the responsibility of the caller to remove the copy source and/or
     /// the entry itself if appropriate.
     ///
     /// # Panics
     ///
     /// Panics if the node does not exist.
     fn set_untracked(
         &mut self,
         filename: &HgPath,
         old_entry: DirstateEntry,
     ) -> Result<(), DirstateV2ParseError> {
         let node = self
             .get_node_mut(filename, |ancestor| {
                 ancestor.tracked_descendants_count = ancestor
                     .tracked_descendants_count
                     .checked_sub(1)
                     .expect("tracked_descendants_count should be >= 0");
             })?
             .expect("node should exist");
         let mut new_entry = old_entry;
         new_entry.set_untracked();
         node.data = NodeData::Entry(new_entry);
         Ok(())
     }
 
     /// Set a node as clean in the dirstate.
     ///
     /// It is the responsibility of the caller to remove the copy source.
     ///
     /// # Panics
     ///
     /// Panics if the node does not exist.
     fn set_clean(
         &mut self,
         filename: &HgPath,
         old_entry: DirstateEntry,
         mode: u32,
         size: u32,
         mtime: TruncatedTimestamp,
     ) -> Result<(), DirstateError> {
         let node = self
             .get_node_mut(filename, |ancestor| {
                 if !old_entry.tracked() {
                     ancestor.tracked_descendants_count += 1;
                 }
             })?
             .expect("node should exist");
         let mut new_entry = old_entry;
         new_entry.set_clean(mode, size, mtime);
         node.data = NodeData::Entry(new_entry);
         Ok(())
     }
 
     /// Set a node as possibly dirty in the dirstate.
     ///
     /// # Panics
     ///
     /// Panics if the node does not exist.
     fn set_possibly_dirty(
         &mut self,
         filename: &HgPath,
     ) -> Result<(), DirstateError> {
         let node = self
             .get_node_mut(filename, |_ancestor| {})?
             .expect("node should exist");
         let entry = node.data.as_entry_mut().expect("entry should exist");
         entry.set_possibly_dirty();
         node.data = NodeData::Entry(*entry);
         Ok(())
     }
 
     /// Clears the cached mtime for the (potential) folder at `path`.
     pub(super) fn clear_cached_mtime(
         &mut self,
         path: &HgPath,
     ) -> Result<(), DirstateV2ParseError> {
         let node = match self.get_node_mut(path, |_ancestor| {})? {
             Some(node) => node,
             None => return Ok(()),
         };
         if let NodeData::CachedDirectory { .. } = &node.data {
             node.data = NodeData::None
         }
         Ok(())
     }
 
     /// Sets the cached mtime for the (potential) folder at `path`.
     pub(super) fn set_cached_mtime(
         &mut self,
         path: &HgPath,
         mtime: TruncatedTimestamp,
     ) -> Result<(), DirstateV2ParseError> {
         let node = match self.get_node_mut(path, |_ancestor| {})? {
             Some(node) => node,
             None => return Ok(()),
         };
         match &node.data {
             NodeData::Entry(_) => {} // Don’t overwrite an entry
             NodeData::CachedDirectory { .. } | NodeData::None => {
                 node.data = NodeData::CachedDirectory { mtime }
             }
         }
         Ok(())
     }
 
     fn iter_nodes<'tree>(
         &'tree self,
     ) -> impl Iterator<
         Item = Result<NodeRef<'tree, 'on_disk>, DirstateV2ParseError>,
     > + 'tree {
         // Depth first tree traversal.
         //
         // If we could afford internal iteration and recursion,
         // this would look like:
         //
         // ```
         // fn traverse_children(
         //     children: &ChildNodes,
         //     each: &mut impl FnMut(&Node),
         // ) {
         //     for child in children.values() {
         //         traverse_children(&child.children, each);
         //         each(child);
         //     }
         // }
         // ```
         //
         // However we want an external iterator and therefore can’t use the
         // call stack. Use an explicit stack instead:
         let mut stack = Vec::new();
         let mut iter = self.root.as_ref().iter();
         std::iter::from_fn(move || {
             while let Some(child_node) = iter.next() {
                 let children = match child_node.children(self.on_disk) {
                     Ok(children) => children,
                     Err(error) => return Some(Err(error)),
                 };
                 // Pseudo-recursion
                 let new_iter = children.iter();
                 let old_iter = std::mem::replace(&mut iter, new_iter);
                 stack.push((child_node, old_iter));
             }
             // Found the end of a `children.iter()` iterator.
             if let Some((child_node, next_iter)) = stack.pop() {
                 // "Return" from pseudo-recursion by restoring state from the
                 // explicit stack
                 iter = next_iter;
 
                 Some(Ok(child_node))
             } else {
                 // Reached the bottom of the stack, we’re done
                 None
             }
         })
     }
 
     fn count_dropped_path(unreachable_bytes: &mut u32, path: Cow<HgPath>) {
         if let Cow::Borrowed(path) = path {
             *unreachable_bytes += path.len() as u32
         }
     }
 
     pub(crate) fn set_write_mode(&mut self, write_mode: DirstateMapWriteMode) {
         self.write_mode = write_mode;
     }
 }
 
+/// Sets the parameters for resetting a dirstate entry
+pub struct DirstateEntryReset<'a> {
+    /// Which entry are we resetting
+    pub filename: &'a HgPath,
+    /// Whether the entry is tracked in the working copy
+    pub wc_tracked: bool,
+    /// Whether the entry is tracked in p1
+    pub p1_tracked: bool,
+    /// Whether the entry has merge information
+    pub p2_info: bool,
+    /// Whether the entry's mtime should be trusted
+    pub has_meaningful_mtime: bool,
+    /// Information from the parent file data (from the manifest)
+    pub parent_file_data_opt: Option<ParentFileData>,
+    /// Set this to `true` if you are *certain* that there is no old entry for
+    /// this filename. Yield better performance in cases where we do a lot
+    /// of additions to the dirstate.
+    pub from_empty: bool,
+}
+
 type DebugDirstateTuple<'a> = (&'a HgPath, (u8, i32, i32, i32));
 
 impl OwningDirstateMap {
     pub fn clear(&mut self) {
         self.with_dmap_mut(|map| {
             map.root = Default::default();
             map.nodes_with_entry_count = 0;
             map.nodes_with_copy_source_count = 0;
             map.unreachable_bytes = map.on_disk.len() as u32;
         });
     }
 
     pub fn set_tracked(
         &mut self,
         filename: &HgPath,
     ) -> Result<bool, DirstateV2ParseError> {
         let old_entry_opt = self.get(filename)?;
         self.with_dmap_mut(|map| map.set_tracked(filename, old_entry_opt))
     }
 
     pub fn set_untracked(
         &mut self,
         filename: &HgPath,
     ) -> Result<bool, DirstateError> {
         let old_entry_opt = self.get(filename)?;
         match old_entry_opt {
             None => Ok(false),
             Some(old_entry) => {
                 if !old_entry.tracked() {
                     // `DirstateMap::set_untracked` is not a noop if
                     // already not tracked as it will decrement the
                     // tracked counters while going down.
                     return Ok(true);
                 }
                 if old_entry.added() {
                     // Untracking an "added" entry will just result in a
                     // worthless entry (and other parts of the code will
                     // complain about it), just drop it entirely.
                     self.drop_entry_and_copy_source(filename)?;
                     return Ok(true);
                 }
                 if !old_entry.p2_info() {
                     self.copy_map_remove(filename)?;
                 }
 
                 self.with_dmap_mut(|map| {
                     map.set_untracked(filename, old_entry)?;
                     Ok(true)
                 })
             }
         }
     }
 
     pub fn set_clean(
         &mut self,
         filename: &HgPath,
         mode: u32,
         size: u32,
         mtime: TruncatedTimestamp,
     ) -> Result<(), DirstateError> {
         let old_entry = match self.get(filename)? {
             None => {
                 return Err(
                     DirstateMapError::PathNotFound(filename.into()).into()
                 )
             }
             Some(e) => e,
         };
         self.copy_map_remove(filename)?;
         self.with_dmap_mut(|map| {
             map.set_clean(filename, old_entry, mode, size, mtime)
         })
     }
 
     pub fn set_possibly_dirty(
         &mut self,
         filename: &HgPath,
     ) -> Result<(), DirstateError> {
         if self.get(filename)?.is_none() {
             return Err(DirstateMapError::PathNotFound(filename.into()).into());
         }
         self.with_dmap_mut(|map| map.set_possibly_dirty(filename))
     }
 
     pub fn reset_state(
         &mut self,
-        filename: &HgPath,
-        wc_tracked: bool,
-        p1_tracked: bool,
-        p2_info: bool,
-        has_meaningful_mtime: bool,
-        parent_file_data_opt: Option<ParentFileData>,
+        reset: DirstateEntryReset,
     ) -> Result<(), DirstateError> {
-        if !(p1_tracked || p2_info || wc_tracked) {
-            self.drop_entry_and_copy_source(filename)?;
+        if !(reset.p1_tracked || reset.p2_info || reset.wc_tracked) {
+            self.drop_entry_and_copy_source(reset.filename)?;
             return Ok(());
         }
-        self.copy_map_remove(filename)?;
-        let old_entry_opt = self.get(filename)?;
+        if !reset.from_empty {
+            self.copy_map_remove(reset.filename)?;
+        }
+
+        let old_entry_opt = if reset.from_empty {
+            None
+        } else {
+            self.get(reset.filename)?
+        };
+
         self.with_dmap_mut(|map| {
             map.reset_state(
-                filename,
+                reset.filename,
                 old_entry_opt,
-                wc_tracked,
-                p1_tracked,
-                p2_info,
-                has_meaningful_mtime,
-                parent_file_data_opt,
+                reset.wc_tracked,
+                reset.p1_tracked,
+                reset.p2_info,
+                reset.has_meaningful_mtime,
+                reset.parent_file_data_opt,
             )
         })
     }
 
     pub fn drop_entry_and_copy_source(
         &mut self,
         filename: &HgPath,
     ) -> Result<(), DirstateError> {
         let was_tracked = self.get(filename)?.map_or(false, |e| e.tracked());
         struct Dropped {
             was_tracked: bool,
             had_entry: bool,
             had_copy_source: bool,
         }
 
         /// If this returns `Ok(Some((dropped, removed)))`, then
         ///
         /// * `dropped` is about the leaf node that was at `filename`
         /// * `removed` is whether this particular level of recursion just
         ///   removed a node in `nodes`.
         fn recur<'on_disk>(
             on_disk: &'on_disk [u8],
             unreachable_bytes: &mut u32,
             nodes: &mut ChildNodes<'on_disk>,
             path: &HgPath,
         ) -> Result<Option<(Dropped, bool)>, DirstateV2ParseError> {
             let (first_path_component, rest_of_path) =
                 path.split_first_component();
             let nodes = nodes.make_mut(on_disk, unreachable_bytes)?;
             let node = if let Some(node) = nodes.get_mut(first_path_component)
             {
                 node
             } else {
                 return Ok(None);
             };
             let dropped;
             if let Some(rest) = rest_of_path {
                 if let Some((d, removed)) = recur(
                     on_disk,
                     unreachable_bytes,
                     &mut node.children,
                     rest,
                 )? {
                     dropped = d;
                     if dropped.had_entry {
                         node.descendants_with_entry_count = node
                             .descendants_with_entry_count
                             .checked_sub(1)
                             .expect(
                                 "descendants_with_entry_count should be >= 0",
                             );
                     }
                     if dropped.was_tracked {
                         node.tracked_descendants_count = node
                             .tracked_descendants_count
                             .checked_sub(1)
                             .expect(
                                 "tracked_descendants_count should be >= 0",
                             );
                     }
 
                     // Directory caches must be invalidated when removing a
                     // child node
                     if removed {
                         if let NodeData::CachedDirectory { .. } = &node.data {
                             node.data = NodeData::None
                         }
                     }
                 } else {
                     return Ok(None);
                 }
             } else {
                 let entry = node.data.as_entry();
                 let was_tracked = entry.map_or(false, |entry| entry.tracked());
                 let had_entry = entry.is_some();
                 if had_entry {
                     node.data = NodeData::None
                 }
                 let mut had_copy_source = false;
                 if let Some(source) = &node.copy_source {
                     DirstateMap::count_dropped_path(
                         unreachable_bytes,
                         Cow::Borrowed(source),
                     );
                     had_copy_source = true;
                     node.copy_source = None
                 }
                 dropped = Dropped {
                     was_tracked,
                     had_entry,
                     had_copy_source,
                 };
             }
             // After recursion, for both leaf (rest_of_path is None) nodes and
             // parent nodes, remove a node if it just became empty.
             let remove = !node.data.has_entry()
                 && node.copy_source.is_none()
                 && node.children.is_empty();
             if remove {
                 let (key, _) =
                     nodes.remove_entry(first_path_component).unwrap();
                 DirstateMap::count_dropped_path(
                     unreachable_bytes,
                     Cow::Borrowed(key.full_path()),
                 )
             }
             Ok(Some((dropped, remove)))
         }
 
         self.with_dmap_mut(|map| {
             if let Some((dropped, _removed)) = recur(
                 map.on_disk,
                 &mut map.unreachable_bytes,
                 &mut map.root,
                 filename,
             )? {
                 if dropped.had_entry {
                     map.nodes_with_entry_count = map
                         .nodes_with_entry_count
                         .checked_sub(1)
                         .expect("nodes_with_entry_count should be >= 0");
                 }
                 if dropped.had_copy_source {
                     map.nodes_with_copy_source_count = map
                         .nodes_with_copy_source_count
                         .checked_sub(1)
                         .expect("nodes_with_copy_source_count should be >= 0");
                 }
             } else {
                 debug_assert!(!was_tracked);
             }
             Ok(())
         })
     }
 
     pub fn has_tracked_dir(
         &mut self,
         directory: &HgPath,
     ) -> Result<bool, DirstateError> {
         self.with_dmap_mut(|map| {
             if let Some(node) = map.get_node(directory)? {
                 // A node without a `DirstateEntry` was created to hold child
                 // nodes, and is therefore a directory.
                 let is_dir = node.entry()?.is_none();
                 Ok(is_dir && node.tracked_descendants_count() > 0)
             } else {
                 Ok(false)
             }
         })
     }
 
     pub fn has_dir(
         &mut self,
         directory: &HgPath,
     ) -> Result<bool, DirstateError> {
         self.with_dmap_mut(|map| {
             if let Some(node) = map.get_node(directory)? {
                 // A node without a `DirstateEntry` was created to hold child
                 // nodes, and is therefore a directory.
                 let is_dir = node.entry()?.is_none();
                 Ok(is_dir && node.descendants_with_entry_count() > 0)
             } else {
                 Ok(false)
             }
         })
     }
 
     #[logging_timer::time("trace")]
     pub fn pack_v1(
         &self,
         parents: DirstateParents,
     ) -> Result<Vec<u8>, DirstateError> {
         let map = self.get_map();
         // Optizimation (to be measured?): pre-compute size to avoid `Vec`
         // reallocations
         let mut size = parents.as_bytes().len();
         for node in map.iter_nodes() {
             let node = node?;
             if node.entry()?.is_some() {
                 size += packed_entry_size(
                     node.full_path(map.on_disk)?,
                     node.copy_source(map.on_disk)?,
                 );
             }
         }
 
         let mut packed = Vec::with_capacity(size);
         packed.extend(parents.as_bytes());
 
         for node in map.iter_nodes() {
             let node = node?;
             if let Some(entry) = node.entry()? {
                 pack_entry(
                     node.full_path(map.on_disk)?,
                     &entry,
                     node.copy_source(map.on_disk)?,
                     &mut packed,
                 );
             }
         }
         Ok(packed)
     }
 
     /// Returns new data and metadata together with whether that data should be
     /// appended to the existing data file whose content is at
     /// `map.on_disk` (true), instead of written to a new data file
     /// (false), and the previous size of data on disk.
     #[logging_timer::time("trace")]
     pub fn pack_v2(
         &self,
         write_mode: DirstateMapWriteMode,
     ) -> Result<(Vec<u8>, on_disk::TreeMetadata, bool, usize), DirstateError>
     {
         let map = self.get_map();
         on_disk::write(map, write_mode)
     }
 
     /// `callback` allows the caller to process and do something with the
     /// results of the status. This is needed to do so efficiently (i.e.
     /// without cloning the `DirstateStatus` object with its paths) because
     /// we need to borrow from `Self`.
     pub fn with_status<R>(
         &mut self,
         matcher: &(dyn Matcher + Sync),
         root_dir: PathBuf,
         ignore_files: Vec<PathBuf>,
         options: StatusOptions,
         callback: impl for<'r> FnOnce(
             Result<(DirstateStatus<'r>, Vec<PatternFileWarning>), StatusError>,
         ) -> R,
     ) -> R {
         self.with_dmap_mut(|map| {
             callback(super::status::status(
                 map,
                 matcher,
                 root_dir,
                 ignore_files,
                 options,
             ))
         })
     }
 
     pub fn copy_map_len(&self) -> usize {
         let map = self.get_map();
         map.nodes_with_copy_source_count as usize
     }
 
     pub fn copy_map_iter(&self) -> CopyMapIter<'_> {
         let map = self.get_map();
         Box::new(filter_map_results(map.iter_nodes(), move |node| {
             Ok(if let Some(source) = node.copy_source(map.on_disk)? {
                 Some((node.full_path(map.on_disk)?, source))
             } else {
                 None
             })
         }))
     }
 
     pub fn copy_map_contains_key(
         &self,
         key: &HgPath,
     ) -> Result<bool, DirstateV2ParseError> {
         let map = self.get_map();
         Ok(if let Some(node) = map.get_node(key)? {
             node.has_copy_source()
         } else {
             false
         })
     }
 
     pub fn copy_map_get(
         &self,
         key: &HgPath,
     ) -> Result<Option<&HgPath>, DirstateV2ParseError> {
         let map = self.get_map();
         if let Some(node) = map.get_node(key)? {
             if let Some(source) = node.copy_source(map.on_disk)? {
                 return Ok(Some(source));
             }
         }
         Ok(None)
     }
 
     pub fn copy_map_remove(
         &mut self,
         key: &HgPath,
     ) -> Result<Option<HgPathBuf>, DirstateV2ParseError> {
         self.with_dmap_mut(|map| {
             let count = &mut map.nodes_with_copy_source_count;
             let unreachable_bytes = &mut map.unreachable_bytes;
             Ok(DirstateMap::get_node_mut_inner(
                 map.on_disk,
                 unreachable_bytes,
                 &mut map.root,
                 key,
                 |_ancestor| {},
             )?
             .and_then(|node| {
                 if let Some(source) = &node.copy_source {
                     *count = count
                         .checked_sub(1)
                         .expect("nodes_with_copy_source_count should be >= 0");
                     DirstateMap::count_dropped_path(
                         unreachable_bytes,
                         Cow::Borrowed(source),
                     );
                 }
                 node.copy_source.take().map(Cow::into_owned)
             }))
         })
     }
 
     pub fn copy_map_insert(
         &mut self,
         key: &HgPath,
         value: &HgPath,
     ) -> Result<Option<HgPathBuf>, DirstateV2ParseError> {
         self.with_dmap_mut(|map| {
             let node = map.get_or_insert_node(key, |_ancestor| {})?;
             let had_copy_source = node.copy_source.is_none();
             let old = node
                 .copy_source
                 .replace(value.to_owned().into())
                 .map(Cow::into_owned);
             if had_copy_source {
                 map.nodes_with_copy_source_count += 1
             }
             Ok(old)
         })
     }
 
     pub fn len(&self) -> usize {
         let map = self.get_map();
         map.nodes_with_entry_count as usize
     }
 
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
 
     pub fn contains_key(
         &self,
         key: &HgPath,
     ) -> Result<bool, DirstateV2ParseError> {
         Ok(self.get(key)?.is_some())
     }
 
     pub fn get(
         &self,
         key: &HgPath,
     ) -> Result<Option<DirstateEntry>, DirstateV2ParseError> {
         let map = self.get_map();
         Ok(if let Some(node) = map.get_node(key)? {
             node.entry()?
         } else {
             None
         })
     }
 
     pub fn iter(&self) -> StateMapIter<'_> {
         let map = self.get_map();
         Box::new(filter_map_results(map.iter_nodes(), move |node| {
             Ok(if let Some(entry) = node.entry()? {
                 Some((node.full_path(map.on_disk)?, entry))
             } else {
                 None
             })
         }))
     }
 
     pub fn iter_tracked_dirs(
         &mut self,
     ) -> Result<
         Box<
             dyn Iterator<Item = Result<&HgPath, DirstateV2ParseError>>
                 + Send
                 + '_,
         >,
         DirstateError,
     > {
         let map = self.get_map();
         let on_disk = map.on_disk;
         Ok(Box::new(filter_map_results(
             map.iter_nodes(),
             move |node| {
                 Ok(if node.tracked_descendants_count() > 0 {
                     Some(node.full_path(on_disk)?)
                 } else {
                     None
                 })
             },
         )))
     }
 
     /// Only public because it needs to be exposed to the Python layer.
     /// It is not the full `setparents` logic, only the parts that mutate the
     /// entries.
     pub fn setparents_fixup(
         &mut self,
     ) -> Result<Vec<(HgPathBuf, HgPathBuf)>, DirstateV2ParseError> {
         // XXX
         // All the copying and re-querying is quite inefficient, but this is
         // still a lot better than doing it from Python.
         //
         // The better solution is to develop a mechanism for `iter_mut`,
         // which will be a lot more involved: we're dealing with a lazy,
         // append-mostly, tree-like data structure. This will do for now.
         let mut copies = vec![];
         let mut files_with_p2_info = vec![];
         for res in self.iter() {
             let (path, entry) = res?;
             if entry.p2_info() {
                 files_with_p2_info.push(path.to_owned())
             }
         }
         self.with_dmap_mut(|map| {
             for path in files_with_p2_info.iter() {
                 let node = map.get_or_insert_node(path, |_| {})?;
                 let entry =
                     node.data.as_entry_mut().expect("entry should exist");
                 entry.drop_merge_data();
                 if let Some(source) = node.copy_source.take().as_deref() {
                     copies.push((path.to_owned(), source.to_owned()));
                 }
             }
             Ok(copies)
         })
     }
 
     pub fn debug_iter(
         &self,
         all: bool,
     ) -> Box<
         dyn Iterator<Item = Result<DebugDirstateTuple, DirstateV2ParseError>>
             + Send
             + '_,
     > {
         let map = self.get_map();
         Box::new(filter_map_results(map.iter_nodes(), move |node| {
             let debug_tuple = if let Some(entry) = node.entry()? {
                 entry.debug_tuple()
             } else if !all {
                 return Ok(None);
             } else if let Some(mtime) = node.cached_directory_mtime()? {
                 (b' ', 0, -1, mtime.truncated_seconds() as i32)
             } else {
                 (b' ', 0, -1, -1)
             };
             Ok(Some((node.full_path(map.on_disk)?, debug_tuple)))
         }))
     }
 }
 #[cfg(test)]
 mod tests {
     use super::*;
 
     /// Shortcut to return tracked descendants of a path.
     /// Panics if the path does not exist.
     fn tracked_descendants(map: &OwningDirstateMap, path: &[u8]) -> u32 {
         let path = dbg!(HgPath::new(path));
         let node = map.get_map().get_node(path);
         node.unwrap().unwrap().tracked_descendants_count()
     }
 
     /// Shortcut to return descendants with an entry.
     /// Panics if the path does not exist.
     fn descendants_with_an_entry(map: &OwningDirstateMap, path: &[u8]) -> u32 {
         let path = dbg!(HgPath::new(path));
         let node = map.get_map().get_node(path);
         node.unwrap().unwrap().descendants_with_entry_count()
     }
 
     fn assert_does_not_exist(map: &OwningDirstateMap, path: &[u8]) {
         let path = dbg!(HgPath::new(path));
         let node = map.get_map().get_node(path);
         assert!(node.unwrap().is_none());
     }
 
     /// Shortcut for path creation in tests
     fn p(b: &[u8]) -> &HgPath {
         HgPath::new(b)
     }
 
     /// Test the very simple case a single tracked file
     #[test]
     fn test_tracked_descendants_simple() -> Result<(), DirstateError> {
         let mut map = OwningDirstateMap::new_empty(vec![], None);
         assert_eq!(map.len(), 0);
 
         map.set_tracked(p(b"some/nested/path"))?;
 
         assert_eq!(map.len(), 1);
         assert_eq!(tracked_descendants(&map, b"some"), 1);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/nested/path"), 0);
 
         map.set_untracked(p(b"some/nested/path"))?;
         assert_eq!(map.len(), 0);
         assert!(map.get_map().get_node(p(b"some"))?.is_none());
 
         Ok(())
     }
 
     /// Test the simple case of all tracked, but multiple files
     #[test]
     fn test_tracked_descendants_multiple() -> Result<(), DirstateError> {
         let mut map = OwningDirstateMap::new_empty(vec![], None);
 
         map.set_tracked(p(b"some/nested/path"))?;
         map.set_tracked(p(b"some/nested/file"))?;
         // one layer without any files to test deletion cascade
         map.set_tracked(p(b"some/other/nested/path"))?;
         map.set_tracked(p(b"root_file"))?;
         map.set_tracked(p(b"some/file"))?;
         map.set_tracked(p(b"some/file2"))?;
         map.set_tracked(p(b"some/file3"))?;
 
         assert_eq!(map.len(), 7);
         assert_eq!(tracked_descendants(&map, b"some"), 6);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 2);
         assert_eq!(tracked_descendants(&map, b"some/other"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/nested/path"), 0);
 
         map.set_untracked(p(b"some/nested/path"))?;
         assert_eq!(map.len(), 6);
         assert_eq!(tracked_descendants(&map, b"some"), 5);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other/nested"), 1);
 
         map.set_untracked(p(b"some/nested/file"))?;
         assert_eq!(map.len(), 5);
         assert_eq!(tracked_descendants(&map, b"some"), 4);
         assert_eq!(tracked_descendants(&map, b"some/other"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other/nested"), 1);
         assert_does_not_exist(&map, b"some_nested");
 
         map.set_untracked(p(b"some/other/nested/path"))?;
         assert_eq!(map.len(), 4);
         assert_eq!(tracked_descendants(&map, b"some"), 3);
         assert_does_not_exist(&map, b"some/other");
 
         map.set_untracked(p(b"root_file"))?;
         assert_eq!(map.len(), 3);
         assert_eq!(tracked_descendants(&map, b"some"), 3);
         assert_does_not_exist(&map, b"root_file");
 
         map.set_untracked(p(b"some/file"))?;
         assert_eq!(map.len(), 2);
         assert_eq!(tracked_descendants(&map, b"some"), 2);
         assert_does_not_exist(&map, b"some/file");
 
         map.set_untracked(p(b"some/file2"))?;
         assert_eq!(map.len(), 1);
         assert_eq!(tracked_descendants(&map, b"some"), 1);
         assert_does_not_exist(&map, b"some/file2");
 
         map.set_untracked(p(b"some/file3"))?;
         assert_eq!(map.len(), 0);
         assert_does_not_exist(&map, b"some/file3");
 
         Ok(())
     }
 
     /// Check with a mix of tracked and non-tracked items
     #[test]
     fn test_tracked_descendants_different() -> Result<(), DirstateError> {
         let mut map = OwningDirstateMap::new_empty(vec![], None);
 
         // A file that was just added
         map.set_tracked(p(b"some/nested/path"))?;
         // This has no information, the dirstate should ignore it
-        map.reset_state(p(b"some/file"), false, false, false, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/file"),
+            wc_tracked: false,
+            p1_tracked: false,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert_does_not_exist(&map, b"some/file");
 
         // A file that was removed
-        map.reset_state(
-            p(b"some/nested/file"),
-            false,
-            true,
-            false,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/nested/file"),
+            wc_tracked: false,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert!(!map.get(p(b"some/nested/file"))?.unwrap().tracked());
         // Only present in p2
-        map.reset_state(p(b"some/file3"), false, false, true, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/file3"),
+            wc_tracked: false,
+            p1_tracked: false,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert!(!map.get(p(b"some/file3"))?.unwrap().tracked());
         // A file that was merged
-        map.reset_state(p(b"root_file"), true, true, true, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"root_file"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert!(map.get(p(b"root_file"))?.unwrap().tracked());
         // A file that is added, with info from p2
         // XXX is that actually possible?
-        map.reset_state(p(b"some/file2"), true, false, true, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/file2"),
+            wc_tracked: true,
+            p1_tracked: false,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert!(map.get(p(b"some/file2"))?.unwrap().tracked());
         // A clean file
         // One layer without any files to test deletion cascade
-        map.reset_state(
-            p(b"some/other/nested/path"),
-            true,
-            true,
-            false,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/other/nested/path"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         assert!(map.get(p(b"some/other/nested/path"))?.unwrap().tracked());
 
         assert_eq!(map.len(), 6);
         assert_eq!(tracked_descendants(&map, b"some"), 3);
         assert_eq!(descendants_with_an_entry(&map, b"some"), 5);
         assert_eq!(tracked_descendants(&map, b"some/other/nested"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/other/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other/nested/path"), 0);
         assert_eq!(
             descendants_with_an_entry(&map, b"some/other/nested/path"),
             0
         );
         assert_eq!(tracked_descendants(&map, b"some/nested"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/nested"), 2);
 
         // might as well check this
         map.set_untracked(p(b"path/does/not/exist"))?;
         assert_eq!(map.len(), 6);
 
         map.set_untracked(p(b"some/other/nested/path"))?;
         // It is set untracked but not deleted since it held other information
         assert_eq!(map.len(), 6);
         assert_eq!(tracked_descendants(&map, b"some"), 2);
         assert_eq!(descendants_with_an_entry(&map, b"some"), 5);
         assert_eq!(descendants_with_an_entry(&map, b"some/other"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/other/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/nested"), 2);
 
         map.set_untracked(p(b"some/nested/path"))?;
         // It is set untracked *and* deleted since it was only added
         assert_eq!(map.len(), 5);
         assert_eq!(tracked_descendants(&map, b"some"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some"), 4);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 0);
         assert_eq!(descendants_with_an_entry(&map, b"some/nested"), 1);
         assert_does_not_exist(&map, b"some/nested/path");
 
         map.set_untracked(p(b"root_file"))?;
         // Untracked but not deleted
         assert_eq!(map.len(), 5);
         assert!(map.get(p(b"root_file"))?.is_some());
 
         map.set_untracked(p(b"some/file2"))?;
         assert_eq!(map.len(), 5);
         assert_eq!(tracked_descendants(&map, b"some"), 0);
         assert!(map.get(p(b"some/file2"))?.is_some());
 
         map.set_untracked(p(b"some/file3"))?;
         assert_eq!(map.len(), 5);
         assert_eq!(tracked_descendants(&map, b"some"), 0);
         assert!(map.get(p(b"some/file3"))?.is_some());
 
         Ok(())
     }
 
     /// Check that copies counter is correctly updated
     #[test]
     fn test_copy_source() -> Result<(), DirstateError> {
         let mut map = OwningDirstateMap::new_empty(vec![], None);
 
         // Clean file
-        map.reset_state(p(b"files/clean"), true, true, false, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"files/clean"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // Merged file
-        map.reset_state(p(b"files/from_p2"), true, true, true, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"files/from_p2"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // Removed file
-        map.reset_state(p(b"removed"), false, true, false, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"removed"),
+            wc_tracked: false,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // Added file
-        map.reset_state(p(b"files/added"), true, false, false, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"files/added"),
+            wc_tracked: true,
+            p1_tracked: false,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // Add copy
         map.copy_map_insert(p(b"files/clean"), p(b"clean_copy_source"))?;
         assert_eq!(map.copy_map_len(), 1);
 
         // Copy override
         map.copy_map_insert(p(b"files/clean"), p(b"other_clean_copy_source"))?;
         assert_eq!(map.copy_map_len(), 1);
 
         // Multiple copies
         map.copy_map_insert(p(b"removed"), p(b"removed_copy_source"))?;
         assert_eq!(map.copy_map_len(), 2);
 
         map.copy_map_insert(p(b"files/added"), p(b"added_copy_source"))?;
         assert_eq!(map.copy_map_len(), 3);
 
         // Added, so the entry is completely removed
         map.set_untracked(p(b"files/added"))?;
         assert_does_not_exist(&map, b"files/added");
         assert_eq!(map.copy_map_len(), 2);
 
         // Removed, so the entry is kept around, so is its copy
         map.set_untracked(p(b"removed"))?;
         assert!(map.get(p(b"removed"))?.is_some());
         assert_eq!(map.copy_map_len(), 2);
 
         // Clean, so the entry is kept around, but not its copy
         map.set_untracked(p(b"files/clean"))?;
         assert!(map.get(p(b"files/clean"))?.is_some());
         assert_eq!(map.copy_map_len(), 1);
 
         map.copy_map_insert(p(b"files/from_p2"), p(b"from_p2_copy_source"))?;
         assert_eq!(map.copy_map_len(), 2);
 
         // Info from p2, so its copy source info is kept around
         map.set_untracked(p(b"files/from_p2"))?;
         assert!(map.get(p(b"files/from_p2"))?.is_some());
         assert_eq!(map.copy_map_len(), 2);
 
         Ok(())
     }
 
     /// Test with "on disk" data. For the sake of this test, the "on disk" data
     /// does not actually come from the disk, but it's opaque to the code being
     /// tested.
     #[test]
     fn test_on_disk() -> Result<(), DirstateError> {
         // First let's create some data to put "on disk"
         let mut map = OwningDirstateMap::new_empty(vec![], None);
 
         // A file that was just added
         map.set_tracked(p(b"some/nested/added"))?;
         map.copy_map_insert(p(b"some/nested/added"), p(b"added_copy_source"))?;
 
         // A file that was removed
-        map.reset_state(
-            p(b"some/nested/removed"),
-            false,
-            true,
-            false,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/nested/removed"),
+            wc_tracked: false,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // Only present in p2
-        map.reset_state(
-            p(b"other/p2_info_only"),
-            false,
-            false,
-            true,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"other/p2_info_only"),
+            wc_tracked: false,
+            p1_tracked: false,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         map.copy_map_insert(
             p(b"other/p2_info_only"),
             p(b"other/p2_info_copy_source"),
         )?;
         // A file that was merged
-        map.reset_state(p(b"merged"), true, true, true, false, None)?;
+        let reset = DirstateEntryReset {
+            filename: p(b"merged"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // A file that is added, with info from p2
         // XXX is that actually possible?
-        map.reset_state(
-            p(b"other/added_with_p2"),
-            true,
-            false,
-            true,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"other/added_with_p2"),
+            wc_tracked: true,
+            p1_tracked: false,
+            p2_info: true,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
         // One layer without any files to test deletion cascade
         // A clean file
-        map.reset_state(
-            p(b"some/other/nested/clean"),
-            true,
-            true,
-            false,
-            false,
-            None,
-        )?;
+        let reset = DirstateEntryReset {
+            filename: p(b"some/other/nested/clean"),
+            wc_tracked: true,
+            p1_tracked: true,
+            p2_info: false,
+            has_meaningful_mtime: false,
+            parent_file_data_opt: None,
+            from_empty: false,
+        };
+        map.reset_state(reset)?;
 
         let (packed, metadata, _should_append, _old_data_size) =
             map.pack_v2(DirstateMapWriteMode::ForceNewDataFile)?;
         let packed_len = packed.len();
         assert!(packed_len > 0);
 
         // Recreate "from disk"
         let mut map = OwningDirstateMap::new_v2(
             packed,
             packed_len,
             metadata.as_bytes(),
             vec![],
             None,
         )?;
 
         // Check that everything is accounted for
         assert!(map.contains_key(p(b"some/nested/added"))?);
         assert!(map.contains_key(p(b"some/nested/removed"))?);
         assert!(map.contains_key(p(b"merged"))?);
         assert!(map.contains_key(p(b"other/p2_info_only"))?);
         assert!(map.contains_key(p(b"other/added_with_p2"))?);
         assert!(map.contains_key(p(b"some/other/nested/clean"))?);
         assert_eq!(
             map.copy_map_get(p(b"some/nested/added"))?,
             Some(p(b"added_copy_source"))
         );
         assert_eq!(
             map.copy_map_get(p(b"other/p2_info_only"))?,
             Some(p(b"other/p2_info_copy_source"))
         );
         assert_eq!(tracked_descendants(&map, b"some"), 2);
         assert_eq!(descendants_with_an_entry(&map, b"some"), 3);
         assert_eq!(tracked_descendants(&map, b"other"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"other"), 2);
         assert_eq!(tracked_descendants(&map, b"some/other"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/other"), 1);
         assert_eq!(tracked_descendants(&map, b"some/other/nested"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/other/nested"), 1);
         assert_eq!(tracked_descendants(&map, b"some/nested"), 1);
         assert_eq!(descendants_with_an_entry(&map, b"some/nested"), 2);
         assert_eq!(map.len(), 6);
         assert_eq!(map.get_map().unreachable_bytes, 0);
         assert_eq!(map.copy_map_len(), 2);
 
         // Shouldn't change anything since it's already not tracked
         map.set_untracked(p(b"some/nested/removed"))?;
         assert_eq!(map.get_map().unreachable_bytes, 0);
 
         if let ChildNodes::InMemory(_) = map.get_map().root {
             panic!("root should not have been mutated")
         }
         // We haven't mutated enough (nothing, actually), we should still be in
         // the append strategy
         assert!(map.get_map().write_should_append());
 
         // But this mutates the structure, so there should be unreachable_bytes
         assert!(map.set_untracked(p(b"some/nested/added"))?);
         let unreachable_bytes = map.get_map().unreachable_bytes;
         assert!(unreachable_bytes > 0);
 
         if let ChildNodes::OnDisk(_) = map.get_map().root {
             panic!("root should have been mutated")
         }
 
         // This should not mutate the structure either, since `root` has
         // already been mutated along with its direct children.
         map.set_untracked(p(b"merged"))?;
         assert_eq!(map.get_map().unreachable_bytes, unreachable_bytes);
 
         if let NodeRef::InMemory(_, _) =
             map.get_map().get_node(p(b"other/added_with_p2"))?.unwrap()
         {
             panic!("'other/added_with_p2' should not have been mutated")
         }
         // But this should, since it's in a different path
         // than `<root>some/nested/add`
         map.set_untracked(p(b"other/added_with_p2"))?;
         assert!(map.get_map().unreachable_bytes > unreachable_bytes);
 
         if let NodeRef::OnDisk(_) =
             map.get_map().get_node(p(b"other/added_with_p2"))?.unwrap()
         {
             panic!("'other/added_with_p2' should have been mutated")
         }
 
         // We have rewritten most of the tree, we should create a new file
         assert!(!map.get_map().write_should_append());
 
         Ok(())
     }
 }

rust/hg-cpython/src/dirstate/dirstate_map.rs

@@ -1,556 +1,561
 // dirstate_map.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.
 
 //! Bindings for the `hg::dirstate::dirstate_map` file provided by the
 //! `hg-core` package.
 
 use std::cell::{RefCell, RefMut};
 
 use cpython::{
     exc, PyBool, PyBytes, PyClone, PyDict, PyErr, PyList, PyNone, PyObject,
     PyResult, Python, PythonObject, ToPyObject, UnsafePyLeaked,
 };
-use hg::dirstate::{ParentFileData, TruncatedTimestamp};
+use hg::{
+    dirstate::{ParentFileData, TruncatedTimestamp},
+    dirstate_tree::dirstate_map::DirstateEntryReset,
+};
 
 use crate::{
     dirstate::copymap::{CopyMap, CopyMapItemsIterator, CopyMapKeysIterator},
     dirstate::item::DirstateItem,
     pybytes_deref::PyBytesDeref,
 };
 use hg::{
     dirstate::StateMapIter, dirstate_tree::dirstate_map::DirstateMapWriteMode,
     dirstate_tree::on_disk::DirstateV2ParseError,
     dirstate_tree::owning::OwningDirstateMap, revlog::Node,
     utils::files::normalize_case, utils::hg_path::HgPath, DirstateEntry,
     DirstateError, DirstateParents,
 };
 
 // TODO
 //     This object needs to share references to multiple members of its Rust
 //     inner struct, namely `copy_map`, `dirs` and `all_dirs`.
 //     Right now `CopyMap` is done, but it needs to have an explicit reference
 //     to `RustDirstateMap` which itself needs to have an encapsulation for
 //     every method in `CopyMap` (copymapcopy, etc.).
 //     This is ugly and hard to maintain.
 //     The same logic applies to `dirs` and `all_dirs`, however the `Dirs`
 //     `py_class!` is already implemented and does not mention
 //     `RustDirstateMap`, rightfully so.
 //     All attributes also have to have a separate refcount data attribute for
 //     leaks, with all methods that go along for reference sharing.
 py_class!(pub class DirstateMap |py| {
     @shared data inner: OwningDirstateMap;
 
     /// Returns a `(dirstate_map, parents)` tuple
     @staticmethod
     def new_v1(
         on_disk: PyBytes,
         identity: Option<u64>,
     ) -> PyResult<PyObject> {
         let on_disk = PyBytesDeref::new(py, on_disk);
         let (map, parents) = OwningDirstateMap::new_v1(on_disk, identity)
             .map_err(|e| dirstate_error(py, e))?;
         let map = Self::create_instance(py, map)?;
         let p1 = PyBytes::new(py, parents.p1.as_bytes());
         let p2 = PyBytes::new(py, parents.p2.as_bytes());
         let parents = (p1, p2);
         Ok((map, parents).to_py_object(py).into_object())
     }
 
     /// Returns a DirstateMap
     @staticmethod
     def new_v2(
         on_disk: PyBytes,
         data_size: usize,
         tree_metadata: PyBytes,
         uuid: PyBytes,
         identity: Option<u64>,
     ) -> PyResult<PyObject> {
         let dirstate_error = |e: DirstateError| {
             PyErr::new::<exc::OSError, _>(py, format!("Dirstate error: {:?}", e))
         };
         let on_disk = PyBytesDeref::new(py, on_disk);
         let uuid = uuid.data(py);
         let map = OwningDirstateMap::new_v2(
             on_disk,
             data_size,
             tree_metadata.data(py),
             uuid.to_owned(),
             identity,
         ).map_err(dirstate_error)?;
         let map = Self::create_instance(py, map)?;
         Ok(map.into_object())
     }
 
     /// Returns an empty DirstateMap. Only used for a new dirstate.
     @staticmethod
     def new_empty() -> PyResult<PyObject> {
         let map = OwningDirstateMap::new_empty(vec![], None);
         let map = Self::create_instance(py, map)?;
         Ok(map.into_object())
     }
 
     def clear(&self) -> PyResult<PyObject> {
         self.inner(py).borrow_mut().clear();
         Ok(py.None())
     }
 
     def get(
         &self,
         key: PyObject,
         default: Option<PyObject> = None
     ) -> PyResult<Option<PyObject>> {
         let key = key.extract::<PyBytes>(py)?;
         match self
             .inner(py)
             .borrow()
             .get(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))?
         {
             Some(entry) => {
                 Ok(Some(DirstateItem::new_as_pyobject(py, entry)?))
             },
             None => Ok(default)
         }
     }
 
     def set_tracked(&self, f: PyObject) -> PyResult<PyBool> {
         let bytes = f.extract::<PyBytes>(py)?;
         let path = HgPath::new(bytes.data(py));
         let res = self.inner(py).borrow_mut().set_tracked(path);
         let was_tracked = res.map_err(|_| PyErr::new::<exc::OSError, _>(py, "Dirstate error".to_string()))?;
         Ok(was_tracked.to_py_object(py))
     }
 
     def set_untracked(&self, f: PyObject) -> PyResult<PyBool> {
         let bytes = f.extract::<PyBytes>(py)?;
         let path = HgPath::new(bytes.data(py));
         let res = self.inner(py).borrow_mut().set_untracked(path);
         let was_tracked = res.map_err(|_| PyErr::new::<exc::OSError, _>(py, "Dirstate error".to_string()))?;
         Ok(was_tracked.to_py_object(py))
     }
 
     def set_clean(
         &self,
         f: PyObject,
         mode: u32,
         size: u32,
         mtime: (i64, u32, bool)
     ) -> PyResult<PyNone> {
         let (mtime_s, mtime_ns, second_ambiguous) = mtime;
         let timestamp = TruncatedTimestamp::new_truncate(
             mtime_s, mtime_ns, second_ambiguous
         );
         let bytes = f.extract::<PyBytes>(py)?;
         let path = HgPath::new(bytes.data(py));
         let res = self.inner(py).borrow_mut().set_clean(
             path, mode, size, timestamp,
         );
         res.map_err(|_| PyErr::new::<exc::OSError, _>(py, "Dirstate error".to_string()))?;
         Ok(PyNone)
     }
 
     def set_possibly_dirty(&self, f: PyObject) -> PyResult<PyNone> {
         let bytes = f.extract::<PyBytes>(py)?;
         let path = HgPath::new(bytes.data(py));
         let res = self.inner(py).borrow_mut().set_possibly_dirty(path);
         res.map_err(|_| PyErr::new::<exc::OSError, _>(py, "Dirstate error".to_string()))?;
         Ok(PyNone)
     }
 
     def reset_state(
         &self,
         f: PyObject,
         wc_tracked: bool,
         p1_tracked: bool,
         p2_info: bool,
         has_meaningful_mtime: bool,
         parentfiledata: Option<(u32, u32, Option<(i64, u32, bool)>)>,
     ) -> PyResult<PyNone> {
         let mut has_meaningful_mtime = has_meaningful_mtime;
         let parent_file_data = match parentfiledata {
             None => {
                 has_meaningful_mtime = false;
                 None
             },
             Some(data) => {
                 let (mode, size, mtime_info) = data;
                 let mtime = if let Some(mtime_info) = mtime_info {
                     let (mtime_s, mtime_ns, second_ambiguous) = mtime_info;
                     let timestamp = TruncatedTimestamp::new_truncate(
                         mtime_s, mtime_ns, second_ambiguous
                     );
                     Some(timestamp)
                 } else {
                     has_meaningful_mtime = false;
                     None
                 };
                 Some(ParentFileData {
                     mode_size: Some((mode, size)),
                     mtime,
                 })
             }
         };
         let bytes = f.extract::<PyBytes>(py)?;
         let path = HgPath::new(bytes.data(py));
-        let res = self.inner(py).borrow_mut().reset_state(
-            path,
+        let reset = DirstateEntryReset {
+            filename: path,
             wc_tracked,
             p1_tracked,
             p2_info,
             has_meaningful_mtime,
-            parent_file_data,
-        );
+            parent_file_data_opt: parent_file_data,
+            from_empty: false
+        };
+        let res = self.inner(py).borrow_mut().reset_state(reset);
         res.map_err(|_| PyErr::new::<exc::OSError, _>(py, "Dirstate error".to_string()))?;
         Ok(PyNone)
     }
 
     def hastrackeddir(&self, d: PyObject) -> PyResult<PyBool> {
         let d = d.extract::<PyBytes>(py)?;
         Ok(self.inner(py).borrow_mut()
             .has_tracked_dir(HgPath::new(d.data(py)))
             .map_err(|e| {
                 PyErr::new::<exc::ValueError, _>(py, e.to_string())
             })?
             .to_py_object(py))
     }
 
     def hasdir(&self, d: PyObject) -> PyResult<PyBool> {
         let d = d.extract::<PyBytes>(py)?;
         Ok(self.inner(py).borrow_mut()
             .has_dir(HgPath::new(d.data(py)))
             .map_err(|e| {
                 PyErr::new::<exc::ValueError, _>(py, e.to_string())
             })?
             .to_py_object(py))
     }
 
     def write_v1(
         &self,
         p1: PyObject,
         p2: PyObject,
     ) -> PyResult<PyBytes> {
         let inner = self.inner(py).borrow();
         let parents = DirstateParents {
             p1: extract_node_id(py, &p1)?,
             p2: extract_node_id(py, &p2)?,
         };
         let result = inner.pack_v1(parents);
         match result {
             Ok(packed) => Ok(PyBytes::new(py, &packed)),
             Err(_) => Err(PyErr::new::<exc::OSError, _>(
                 py,
                 "Dirstate error".to_string(),
             )),
         }
     }
 
     /// Returns new data together with whether that data should be appended to
     /// the existing data file whose content is at `self.on_disk` (True),
     /// instead of written to a new data file (False).
     def write_v2(
         &self,
         write_mode: usize,
     ) -> PyResult<PyObject> {
         let inner = self.inner(py).borrow();
         let rust_write_mode = match write_mode {
             0 => DirstateMapWriteMode::Auto,
             1 => DirstateMapWriteMode::ForceNewDataFile,
             2 => DirstateMapWriteMode::ForceAppend,
             _ => DirstateMapWriteMode::Auto, // XXX should we error out?
         };
         let result = inner.pack_v2(rust_write_mode);
         match result {
             Ok((packed, tree_metadata, append, _old_data_size)) => {
                 let packed = PyBytes::new(py, &packed);
                 let tree_metadata = PyBytes::new(py, tree_metadata.as_bytes());
                 let tuple = (packed, tree_metadata, append);
                 Ok(tuple.to_py_object(py).into_object())
             },
             Err(e) => Err(PyErr::new::<exc::OSError, _>(
                 py,
                 e.to_string(),
             )),
         }
     }
 
     def filefoldmapasdict(&self) -> PyResult<PyDict> {
         let dict = PyDict::new(py);
         for item in self.inner(py).borrow_mut().iter() {
             let (path, entry) = item.map_err(|e| v2_error(py, e))?;
             if !entry.removed() {
                 let key = normalize_case(path);
                 let value = path;
                 dict.set_item(
                     py,
                     PyBytes::new(py, key.as_bytes()).into_object(),
                     PyBytes::new(py, value.as_bytes()).into_object(),
                 )?;
             }
         }
         Ok(dict)
     }
 
     def __len__(&self) -> PyResult<usize> {
         Ok(self.inner(py).borrow().len())
     }
 
     def __contains__(&self, key: PyObject) -> PyResult<bool> {
         let key = key.extract::<PyBytes>(py)?;
         self.inner(py)
             .borrow()
             .contains_key(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))
     }
 
     def __getitem__(&self, key: PyObject) -> PyResult<PyObject> {
         let key = key.extract::<PyBytes>(py)?;
         let key = HgPath::new(key.data(py));
         match self
             .inner(py)
             .borrow()
             .get(key)
             .map_err(|e| v2_error(py, e))?
         {
             Some(entry) => {
                 Ok(DirstateItem::new_as_pyobject(py, entry)?)
             },
             None => Err(PyErr::new::<exc::KeyError, _>(
                 py,
                 String::from_utf8_lossy(key.as_bytes()),
             )),
         }
     }
 
     def keys(&self) -> PyResult<DirstateMapKeysIterator> {
         let leaked_ref = self.inner(py).leak_immutable();
         DirstateMapKeysIterator::from_inner(
             py,
             unsafe { leaked_ref.map(py, |o| o.iter()) },
         )
     }
 
     def items(&self) -> PyResult<DirstateMapItemsIterator> {
         let leaked_ref = self.inner(py).leak_immutable();
         DirstateMapItemsIterator::from_inner(
             py,
             unsafe { leaked_ref.map(py, |o| o.iter()) },
         )
     }
 
     def __iter__(&self) -> PyResult<DirstateMapKeysIterator> {
         let leaked_ref = self.inner(py).leak_immutable();
         DirstateMapKeysIterator::from_inner(
             py,
             unsafe { leaked_ref.map(py, |o| o.iter()) },
         )
     }
 
     // TODO all copymap* methods, see docstring above
     def copymapcopy(&self) -> PyResult<PyDict> {
         let dict = PyDict::new(py);
         for item in self.inner(py).borrow().copy_map_iter() {
             let (key, value) = item.map_err(|e| v2_error(py, e))?;
             dict.set_item(
                 py,
                 PyBytes::new(py, key.as_bytes()),
                 PyBytes::new(py, value.as_bytes()),
             )?;
         }
         Ok(dict)
     }
 
     def copymapgetitem(&self, key: PyObject) -> PyResult<PyBytes> {
         let key = key.extract::<PyBytes>(py)?;
         match self
             .inner(py)
             .borrow()
             .copy_map_get(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))?
         {
             Some(copy) => Ok(PyBytes::new(py, copy.as_bytes())),
             None => Err(PyErr::new::<exc::KeyError, _>(
                 py,
                 String::from_utf8_lossy(key.data(py)),
             )),
         }
     }
     def copymap(&self) -> PyResult<CopyMap> {
         CopyMap::from_inner(py, self.clone_ref(py))
     }
 
     def copymaplen(&self) -> PyResult<usize> {
         Ok(self.inner(py).borrow().copy_map_len())
     }
     def copymapcontains(&self, key: PyObject) -> PyResult<bool> {
         let key = key.extract::<PyBytes>(py)?;
         self.inner(py)
             .borrow()
             .copy_map_contains_key(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))
     }
     def copymapget(
         &self,
         key: PyObject,
         default: Option<PyObject>
     ) -> PyResult<Option<PyObject>> {
         let key = key.extract::<PyBytes>(py)?;
         match self
             .inner(py)
             .borrow()
             .copy_map_get(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))?
         {
             Some(copy) => Ok(Some(
                 PyBytes::new(py, copy.as_bytes()).into_object(),
             )),
             None => Ok(default),
         }
     }
     def copymapsetitem(
         &self,
         key: PyObject,
         value: PyObject
     ) -> PyResult<PyObject> {
         let key = key.extract::<PyBytes>(py)?;
         let value = value.extract::<PyBytes>(py)?;
         self.inner(py)
             .borrow_mut()
             .copy_map_insert(
                 HgPath::new(key.data(py)),
                 HgPath::new(value.data(py)),
             )
             .map_err(|e| v2_error(py, e))?;
         Ok(py.None())
     }
     def copymappop(
         &self,
         key: PyObject,
         default: Option<PyObject>
     ) -> PyResult<Option<PyObject>> {
         let key = key.extract::<PyBytes>(py)?;
         match self
             .inner(py)
             .borrow_mut()
             .copy_map_remove(HgPath::new(key.data(py)))
             .map_err(|e| v2_error(py, e))?
         {
             Some(copy) => Ok(Some(
                 PyBytes::new(py, copy.as_bytes()).into_object(),
             )),
             None => Ok(default),
         }
     }
 
     def copymapiter(&self) -> PyResult<CopyMapKeysIterator> {
         let leaked_ref = self.inner(py).leak_immutable();
         CopyMapKeysIterator::from_inner(
             py,
             unsafe { leaked_ref.map(py, |o| o.copy_map_iter()) },
         )
     }
 
     def copymapitemsiter(&self) -> PyResult<CopyMapItemsIterator> {
         let leaked_ref = self.inner(py).leak_immutable();
         CopyMapItemsIterator::from_inner(
             py,
             unsafe { leaked_ref.map(py, |o| o.copy_map_iter()) },
         )
     }
 
     def tracked_dirs(&self) -> PyResult<PyList> {
         let dirs = PyList::new(py, &[]);
         for path in self.inner(py).borrow_mut().iter_tracked_dirs()
             .map_err(|e |dirstate_error(py, e))?
         {
             let path = path.map_err(|e| v2_error(py, e))?;
             let path = PyBytes::new(py, path.as_bytes());
             dirs.append(py, path.into_object())
         }
         Ok(dirs)
     }
 
     def setparents_fixup(&self) -> PyResult<PyDict> {
         let dict = PyDict::new(py);
         let copies = self.inner(py).borrow_mut().setparents_fixup();
         for (key, value) in copies.map_err(|e| v2_error(py, e))? {
             dict.set_item(
                 py,
                 PyBytes::new(py, key.as_bytes()),
                 PyBytes::new(py, value.as_bytes()),
             )?;
         }
         Ok(dict)
     }
 
     def debug_iter(&self, all: bool) -> PyResult<PyList> {
         let dirs = PyList::new(py, &[]);
         for item in self.inner(py).borrow().debug_iter(all) {
             let (path, (state, mode, size, mtime)) =
                 item.map_err(|e| v2_error(py, e))?;
             let path = PyBytes::new(py, path.as_bytes());
             let item = (path, state, mode, size, mtime);
             dirs.append(py, item.to_py_object(py).into_object())
         }
         Ok(dirs)
     }
 });
 
 impl DirstateMap {
     pub fn get_inner_mut<'a>(
         &'a self,
         py: Python<'a>,
     ) -> RefMut<'a, OwningDirstateMap> {
         self.inner(py).borrow_mut()
     }
     fn translate_key(
         py: Python,
         res: Result<(&HgPath, DirstateEntry), DirstateV2ParseError>,
     ) -> PyResult<Option<PyBytes>> {
         let (f, _entry) = res.map_err(|e| v2_error(py, e))?;
         Ok(Some(PyBytes::new(py, f.as_bytes())))
     }
     fn translate_key_value(
         py: Python,
         res: Result<(&HgPath, DirstateEntry), DirstateV2ParseError>,
     ) -> PyResult<Option<(PyBytes, PyObject)>> {
         let (f, entry) = res.map_err(|e| v2_error(py, e))?;
         Ok(Some((
             PyBytes::new(py, f.as_bytes()),
             DirstateItem::new_as_pyobject(py, entry)?,
         )))
     }
 }
 
 py_shared_iterator!(
     DirstateMapKeysIterator,
     UnsafePyLeaked<StateMapIter<'static>>,
     DirstateMap::translate_key,
     Option<PyBytes>
 );
 
 py_shared_iterator!(
     DirstateMapItemsIterator,
     UnsafePyLeaked<StateMapIter<'static>>,
     DirstateMap::translate_key_value,
     Option<(PyBytes, PyObject)>
 );
 
 fn extract_node_id(py: Python, obj: &PyObject) -> PyResult<Node> {
     let bytes = obj.extract::<PyBytes>(py)?;
     match bytes.data(py).try_into() {
         Ok(s) => Ok(s),
         Err(e) => Err(PyErr::new::<exc::ValueError, _>(py, e.to_string())),
     }
 }
 
 pub(super) fn v2_error(py: Python<'_>, _: DirstateV2ParseError) -> PyErr {
     PyErr::new::<exc::ValueError, _>(py, "corrupted dirstate-v2")
 }
 
 fn dirstate_error(py: Python<'_>, e: DirstateError) -> PyErr {
     PyErr::new::<exc::OSError, _>(py, format!("Dirstate error: {:?}", e))
 }