rust-dirstatemap: cache non normal and other parent set

Performance of `hg update` was significantly worse since the introduction of
the Rust `dirstatemap`. This regression was noticed by Valentin Gatien-Baron
when working on a large repository, as it goes unnoticed for smaller
repositories like Mercurial itself.

This fix introduces the same getter/setter mechanism at `hg-core` level as
for `set/get_dirs`.

While this technique is, as previously discussed, quite suboptimal, it fixes an
important enough problem. Refactoring `hg-core` to use the typestate
pattern could be a good approach to improving code quality in a future patch.

Differential Revision: https://phab.mercurial-scm.org/D8048

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

@@ -1,436 +1,506 b''
 // 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.
 
 use crate::{
     dirstate::{parsers::PARENT_SIZE, EntryState, SIZE_FROM_OTHER_PARENT},
     pack_dirstate, parse_dirstate,
     utils::{
         files::normalize_case,
         hg_path::{HgPath, HgPathBuf},
     },
     CopyMap, DirsMultiset, DirstateEntry, DirstateError, DirstateMapError,
     DirstateParents, DirstateParseError, FastHashMap, StateMap,
 };
 use core::borrow::Borrow;
 use std::collections::HashSet;
 use std::convert::TryInto;
 use std::iter::FromIterator;
 use std::ops::Deref;
 use std::time::Duration;
 
 pub type FileFoldMap = FastHashMap<HgPathBuf, HgPathBuf>;
 
 const NULL_ID: [u8; 20] = [0; 20];
 const MTIME_UNSET: i32 = -1;
 
 #[derive(Default)]
 pub struct DirstateMap {
     state_map: StateMap,
     pub copy_map: CopyMap,
     file_fold_map: Option<FileFoldMap>,
     pub dirs: Option<DirsMultiset>,
     pub all_dirs: Option<DirsMultiset>,
-    non_normal_set: HashSet<HgPathBuf>,
-    other_parent_set: HashSet<HgPathBuf>,
+    non_normal_set: Option<HashSet<HgPathBuf>>,
+    other_parent_set: Option<HashSet<HgPathBuf>>,
     parents: Option<DirstateParents>,
     dirty_parents: bool,
 }
 
 /// Should only really be used in python interface code, for clarity
 impl Deref for DirstateMap {
     type Target = StateMap;
 
     fn deref(&self) -> &Self::Target {
         &self.state_map
     }
 }
 
 impl FromIterator<(HgPathBuf, DirstateEntry)> for DirstateMap {
     fn from_iter<I: IntoIterator<Item = (HgPathBuf, DirstateEntry)>>(
         iter: I,
     ) -> Self {
         Self {
             state_map: iter.into_iter().collect(),
             ..Self::default()
         }
     }
 }
 
 impl DirstateMap {
     pub fn new() -> Self {
         Self::default()
     }
 
     pub fn clear(&mut self) {
         self.state_map.clear();
         self.copy_map.clear();
         self.file_fold_map = None;
-        self.non_normal_set.clear();
-        self.other_parent_set.clear();
+        self.non_normal_set = None;
+        self.other_parent_set = None;
         self.set_parents(&DirstateParents {
             p1: NULL_ID,
             p2: NULL_ID,
         })
     }
 
     /// Add a tracked file to the dirstate
     pub fn add_file(
         &mut self,
         filename: &HgPath,
         old_state: EntryState,
         entry: DirstateEntry,
     ) -> Result<(), DirstateMapError> {
         if old_state == EntryState::Unknown || old_state == EntryState::Removed
         {
             if let Some(ref mut dirs) = self.dirs {
                 dirs.add_path(filename)?;
             }
         }
         if old_state == EntryState::Unknown {
             if let Some(ref mut all_dirs) = self.all_dirs {
                 all_dirs.add_path(filename)?;
             }
         }
         self.state_map.insert(filename.to_owned(), entry.to_owned());
 
         if entry.state != EntryState::Normal || entry.mtime == MTIME_UNSET {
-            self.non_normal_set.insert(filename.to_owned());
+            self.get_non_normal_other_parent_entries()
+                .0
+                .as_mut()
+                .unwrap()
+                .insert(filename.to_owned());
         }
 
         if entry.size == SIZE_FROM_OTHER_PARENT {
-            self.other_parent_set.insert(filename.to_owned());
+            self.get_non_normal_other_parent_entries()
+                .1
+                .as_mut()
+                .unwrap()
+                .insert(filename.to_owned());
         }
         Ok(())
     }
 
     /// Mark a file as removed in the dirstate.
     ///
     /// The `size` parameter is used to store sentinel values that indicate
     /// the file's previous state.  In the future, we should refactor this
     /// to be more explicit about what that state is.
     pub fn remove_file(
         &mut self,
         filename: &HgPath,
         old_state: EntryState,
         size: i32,
     ) -> Result<(), DirstateMapError> {
         if old_state != EntryState::Unknown && old_state != EntryState::Removed
         {
             if let Some(ref mut dirs) = self.dirs {
                 dirs.delete_path(filename)?;
             }
         }
         if old_state == EntryState::Unknown {
             if let Some(ref mut all_dirs) = self.all_dirs {
                 all_dirs.add_path(filename)?;
             }
         }
 
         if let Some(ref mut file_fold_map) = self.file_fold_map {
             file_fold_map.remove(&normalize_case(filename));
         }
         self.state_map.insert(
             filename.to_owned(),
             DirstateEntry {
                 state: EntryState::Removed,
                 mode: 0,
                 size,
                 mtime: 0,
             },
         );
-        self.non_normal_set.insert(filename.to_owned());
+        self.get_non_normal_other_parent_entries()
+            .0
+            .as_mut()
+            .unwrap()
+            .insert(filename.to_owned());
         Ok(())
     }
 
     /// Remove a file from the dirstate.
     /// Returns `true` if the file was previously recorded.
     pub fn drop_file(
         &mut self,
         filename: &HgPath,
         old_state: EntryState,
     ) -> Result<bool, DirstateMapError> {
         let exists = self.state_map.remove(filename).is_some();
 
         if exists {
             if old_state != EntryState::Removed {
                 if let Some(ref mut dirs) = self.dirs {
                     dirs.delete_path(filename)?;
                 }
             }
             if let Some(ref mut all_dirs) = self.all_dirs {
                 all_dirs.delete_path(filename)?;
             }
         }
         if let Some(ref mut file_fold_map) = self.file_fold_map {
             file_fold_map.remove(&normalize_case(filename));
         }
-        self.non_normal_set.remove(filename);
+        self.get_non_normal_other_parent_entries()
+            .0
+            .as_mut()
+            .unwrap()
+            .remove(filename);
 
         Ok(exists)
     }
 
     pub fn clear_ambiguous_times(
         &mut self,
         filenames: Vec<HgPathBuf>,
         now: i32,
     ) {
         for filename in filenames {
             let mut changed = false;
             self.state_map
                 .entry(filename.to_owned())
                 .and_modify(|entry| {
                     if entry.state == EntryState::Normal && entry.mtime == now
                     {
                         changed = true;
                         *entry = DirstateEntry {
                             mtime: MTIME_UNSET,
                             ..*entry
                         };
                     }
                 });
             if changed {
-                self.non_normal_set.insert(filename.to_owned());
+                self.get_non_normal_other_parent_entries()
+                    .0
+                    .as_mut()
+                    .unwrap()
+                    .insert(filename.to_owned());
             }
         }
     }
 
-    pub fn non_normal_other_parent_entries(
-        &self,
-    ) -> (HashSet<HgPathBuf>, HashSet<HgPathBuf>) {
+    pub fn non_normal_entries_remove(
+        &mut self,
+        key: impl AsRef<HgPath>,
+    ) -> bool {
+        self.get_non_normal_other_parent_entries()
+            .0
+            .as_mut()
+            .unwrap()
+            .remove(key.as_ref())
+    }
+    pub fn non_normal_entries_union(
+        &mut self,
+        other: HashSet<HgPathBuf>,
+    ) -> Vec<HgPathBuf> {
+        self.get_non_normal_other_parent_entries()
+            .0
+            .as_mut()
+            .unwrap()
+            .union(&other)
+            .map(|e| e.to_owned())
+            .collect()
+    }
+
+    pub fn get_non_normal_other_parent_entries(
+        &mut self,
+    ) -> (
+        &mut Option<HashSet<HgPathBuf>>,
+        &mut Option<HashSet<HgPathBuf>>,
+    ) {
+        self.set_non_normal_other_parent_entries(false);
+        (&mut self.non_normal_set, &mut self.other_parent_set)
+    }
+
+    pub fn set_non_normal_other_parent_entries(&mut self, force: bool) {
+        if !force
+            && self.non_normal_set.is_some()
+            && self.other_parent_set.is_some()
+        {
+            return;
+        }
         let mut non_normal = HashSet::new();
         let mut other_parent = HashSet::new();
 
         for (
             filename,
             DirstateEntry {
                 state, size, mtime, ..
             },
         ) in self.state_map.iter()
         {
             if *state != EntryState::Normal || *mtime == MTIME_UNSET {
                 non_normal.insert(filename.to_owned());
             }
             if *state == EntryState::Normal && *size == SIZE_FROM_OTHER_PARENT
             {
                 other_parent.insert(filename.to_owned());
             }
         }
-
-        (non_normal, other_parent)
+        self.non_normal_set = Some(non_normal);
+        self.other_parent_set = Some(other_parent);
     }
 
     /// Both of these setters and their uses appear to be the simplest way to
     /// emulate a Python lazy property, but it is ugly and unidiomatic.
     /// TODO One day, rewriting this struct using the typestate might be a
     /// good idea.
     pub fn set_all_dirs(&mut self) -> Result<(), DirstateMapError> {
         if self.all_dirs.is_none() {
             self.all_dirs =
                 Some(DirsMultiset::from_dirstate(&self.state_map, None)?);
         }
         Ok(())
     }
 
     pub fn set_dirs(&mut self) -> Result<(), DirstateMapError> {
         if self.dirs.is_none() {
             self.dirs = Some(DirsMultiset::from_dirstate(
                 &self.state_map,
                 Some(EntryState::Removed),
             )?);
         }
         Ok(())
     }
 
     pub fn has_tracked_dir(
         &mut self,
         directory: &HgPath,
     ) -> Result<bool, DirstateMapError> {
         self.set_dirs()?;
         Ok(self.dirs.as_ref().unwrap().contains(directory))
     }
 
     pub fn has_dir(
         &mut self,
         directory: &HgPath,
     ) -> Result<bool, DirstateMapError> {
         self.set_all_dirs()?;
         Ok(self.all_dirs.as_ref().unwrap().contains(directory))
     }
 
     pub fn parents(
         &mut self,
         file_contents: &[u8],
     ) -> Result<&DirstateParents, DirstateError> {
         if let Some(ref parents) = self.parents {
             return Ok(parents);
         }
         let parents;
         if file_contents.len() == PARENT_SIZE * 2 {
             parents = DirstateParents {
                 p1: file_contents[..PARENT_SIZE].try_into().unwrap(),
                 p2: file_contents[PARENT_SIZE..PARENT_SIZE * 2]
                     .try_into()
                     .unwrap(),
             };
         } else if file_contents.is_empty() {
             parents = DirstateParents {
                 p1: NULL_ID,
                 p2: NULL_ID,
             };
         } else {
             return Err(DirstateError::Parse(DirstateParseError::Damaged));
         }
 
         self.parents = Some(parents);
         Ok(self.parents.as_ref().unwrap())
     }
 
     pub fn set_parents(&mut self, parents: &DirstateParents) {
         self.parents = Some(parents.clone());
         self.dirty_parents = true;
     }
 
     pub fn read(
         &mut self,
         file_contents: &[u8],
     ) -> Result<Option<DirstateParents>, DirstateError> {
         if file_contents.is_empty() {
             return Ok(None);
         }
 
         let parents = parse_dirstate(
             &mut self.state_map,
             &mut self.copy_map,
             file_contents,
         )?;
 
         if !self.dirty_parents {
             self.set_parents(&parents);
         }
 
         Ok(Some(parents))
     }
 
     pub fn pack(
         &mut self,
         parents: DirstateParents,
         now: Duration,
     ) -> Result<Vec<u8>, DirstateError> {
         let packed =
             pack_dirstate(&mut self.state_map, &self.copy_map, parents, now)?;
 
         self.dirty_parents = false;
 
-        let result = self.non_normal_other_parent_entries();
-        self.non_normal_set = result.0;
-        self.other_parent_set = result.1;
+        self.set_non_normal_other_parent_entries(true);
         Ok(packed)
     }
 
     pub fn build_file_fold_map(&mut self) -> &FileFoldMap {
         if let Some(ref file_fold_map) = self.file_fold_map {
             return file_fold_map;
         }
         let mut new_file_fold_map = FileFoldMap::default();
         for (filename, DirstateEntry { state, .. }) in self.state_map.borrow()
         {
             if *state == EntryState::Removed {
                 new_file_fold_map
                     .insert(normalize_case(filename), filename.to_owned());
             }
         }
         self.file_fold_map = Some(new_file_fold_map);
         self.file_fold_map.as_ref().unwrap()
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
     fn test_dirs_multiset() {
         let mut map = DirstateMap::new();
         assert!(map.dirs.is_none());
         assert!(map.all_dirs.is_none());
 
         assert_eq!(map.has_dir(HgPath::new(b"nope")).unwrap(), false);
         assert!(map.all_dirs.is_some());
         assert!(map.dirs.is_none());
 
         assert_eq!(map.has_tracked_dir(HgPath::new(b"nope")).unwrap(), false);
         assert!(map.dirs.is_some());
     }
 
     #[test]
     fn test_add_file() {
         let mut map = DirstateMap::new();
 
         assert_eq!(0, map.len());
 
         map.add_file(
             HgPath::new(b"meh"),
             EntryState::Normal,
             DirstateEntry {
                 state: EntryState::Normal,
                 mode: 1337,
                 mtime: 1337,
                 size: 1337,
             },
         )
         .unwrap();
 
         assert_eq!(1, map.len());
-        assert_eq!(0, map.non_normal_set.len());
-        assert_eq!(0, map.other_parent_set.len());
+        assert_eq!(
+            0,
+            map.get_non_normal_other_parent_entries()
+                .0
+                .as_ref()
+                .unwrap()
+                .len()
+        );
+        assert_eq!(
+            0,
+            map.get_non_normal_other_parent_entries()
+                .1
+                .as_ref()
+                .unwrap()
+                .len()
+        );
     }
 
     #[test]
     fn test_non_normal_other_parent_entries() {
-        let map: DirstateMap = [
+        let mut map: DirstateMap = [
             (b"f1", (EntryState::Removed, 1337, 1337, 1337)),
             (b"f2", (EntryState::Normal, 1337, 1337, -1)),
             (b"f3", (EntryState::Normal, 1337, 1337, 1337)),
             (b"f4", (EntryState::Normal, 1337, -2, 1337)),
             (b"f5", (EntryState::Added, 1337, 1337, 1337)),
             (b"f6", (EntryState::Added, 1337, 1337, -1)),
             (b"f7", (EntryState::Merged, 1337, 1337, -1)),
             (b"f8", (EntryState::Merged, 1337, 1337, 1337)),
             (b"f9", (EntryState::Merged, 1337, -2, 1337)),
             (b"fa", (EntryState::Added, 1337, -2, 1337)),
             (b"fb", (EntryState::Removed, 1337, -2, 1337)),
         ]
         .iter()
         .map(|(fname, (state, mode, size, mtime))| {
             (
                 HgPathBuf::from_bytes(fname.as_ref()),
                 DirstateEntry {
                     state: *state,
                     mode: *mode,
                     size: *size,
                     mtime: *mtime,
                 },
             )
         })
         .collect();
 
         let non_normal = [
             b"f1", b"f2", b"f5", b"f6", b"f7", b"f8", b"f9", b"fa", b"fb",
         ]
         .iter()
         .map(|x| HgPathBuf::from_bytes(x.as_ref()))
         .collect();
 
         let mut other_parent = HashSet::new();
         other_parent.insert(HgPathBuf::from_bytes(b"f4"));
+        let entries = map.get_non_normal_other_parent_entries();
 
         assert_eq!(
-            (non_normal, other_parent),
-            map.non_normal_other_parent_entries()
+            (Some(non_normal), Some(other_parent)),
+            (entries.0.to_owned(), entries.1.to_owned())
         );
     }
 }