rust-parsers: switch to parse/pack_dirstate to mutate-on-loop

Both `parse_dirstate` and `pack_dirstate` can operate directly on the data
they're passed, which prevents the creation of intermediate data structures,
simplifies the function signatures and reduces boilerplate. They are exposed
directly to the Python for now, but a later patch will make use of them inside
`hg-core`.

Differential Revision: https://phab.mercurial-scm.org/D6628

rust/hg-core/src/dirstate.rs

@@ -1,16 +1,25 b''
+// dirstate module
+//
+// 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 std::collections::HashMap;
+
 pub mod dirs_multiset;
 pub mod parsers;
 
-#[derive(Debug, PartialEq, Copy, Clone)]
-pub struct DirstateParents<'a> {
-    pub p1: &'a [u8],
-    pub p2: &'a [u8],
+#[derive(Debug, PartialEq, Clone)]
+pub struct DirstateParents {
+    pub p1: [u8; 20],
+    pub p2: [u8; 20],
 }
 
 /// The C implementation uses all signed types. This will be an issue
 /// either when 4GB+ source files are commonplace or in 2038, whichever
 /// comes first.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Copy, Clone)]
 pub struct DirstateEntry {
     pub state: i8,
     pub mode: i32,
@@ -18,19 +27,12 b' pub struct DirstateEntry {'
     pub size: i32,
 }
 
-pub type DirstateVec = Vec<(Vec<u8>, DirstateEntry)>;
-
-#[derive(Debug, PartialEq)]
-pub struct CopyVecEntry<'a> {
-    pub path: &'a [u8],
-    pub copy_path: &'a [u8],
-}
-
-pub type CopyVec<'a> = Vec<CopyVecEntry<'a>>;
+pub type StateMap = HashMap<Vec<u8>, DirstateEntry>;
+pub type CopyMap = HashMap<Vec<u8>, Vec<u8>>;
 
 /// The Python implementation passes either a mapping (dirstate) or a flat
 /// iterable (manifest)
-pub enum DirsIterable {
-    Dirstate(DirstateVec),
-    Manifest(Vec<Vec<u8>>),
+pub enum DirsIterable<'a> {
+    Dirstate(&'a HashMap<Vec<u8>, DirstateEntry>),
+    Manifest(&'a Vec<Vec<u8>>),
 }

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

@@ -28,10 +28,10 b' impl DirsMultiset {'
 
         match iterable {
             DirsIterable::Dirstate(vec) => {
-                for (ref filename, DirstateEntry { state, .. }) in vec {
+                for (filename, DirstateEntry { state, .. }) in vec {
                     // This `if` is optimized out of the loop
                     if let Some(skip) = skip_state {
-                        if skip != state {
+                        if skip != *state {
                             multiset.add_path(filename);
                         }
                     } else {
@@ -40,7 +40,7 b' impl DirsMultiset {'
                 }
             }
             DirsIterable::Manifest(vec) => {
-                for ref filename in vec {
+                for filename in vec {
                     multiset.add_path(filename);
                 }
             }
@@ -108,10 +108,11 b' impl DirsMultiset {'
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::collections::HashMap;
 
     #[test]
     fn test_delete_path_path_not_found() {
-        let mut map = DirsMultiset::new(DirsIterable::Manifest(vec![]), None);
+        let mut map = DirsMultiset::new(DirsIterable::Manifest(&vec![]), None);
         let path = b"doesnotexist/";
         assert_eq!(
             Err(DirstateMapError::PathNotFound(path.to_vec())),
@@ -122,7 +123,7 b' mod tests {'
     #[test]
     fn test_delete_path_empty_path() {
         let mut map =
-            DirsMultiset::new(DirsIterable::Manifest(vec![vec![]]), None);
+            DirsMultiset::new(DirsIterable::Manifest(&vec![vec![]]), None);
         let path = b"";
         assert_eq!(Ok(()), map.delete_path(path));
         assert_eq!(
@@ -162,7 +163,7 b' mod tests {'
 
     #[test]
     fn test_add_path_empty_path() {
-        let mut map = DirsMultiset::new(DirsIterable::Manifest(vec![]), None);
+        let mut map = DirsMultiset::new(DirsIterable::Manifest(&vec![]), None);
         let path = b"";
         map.add_path(path);
 
@@ -171,7 +172,7 b' mod tests {'
 
     #[test]
     fn test_add_path_successful() {
-        let mut map = DirsMultiset::new(DirsIterable::Manifest(vec![]), None);
+        let mut map = DirsMultiset::new(DirsIterable::Manifest(&vec![]), None);
 
         map.add_path(b"a/");
         assert_eq!(1, *map.inner.get(&b"a".to_vec()).unwrap());
@@ -218,13 +219,13 b' mod tests {'
     fn test_dirsmultiset_new_empty() {
         use DirsIterable::{Dirstate, Manifest};
 
-        let new = DirsMultiset::new(Manifest(vec![]), None);
+        let new = DirsMultiset::new(Manifest(&vec![]), None);
         let expected = DirsMultiset {
             inner: HashMap::new(),
         };
         assert_eq!(expected, new);
 
-        let new = DirsMultiset::new(Dirstate(vec![]), None);
+        let new = DirsMultiset::new(Dirstate(&HashMap::new()), None);
         let expected = DirsMultiset {
             inner: HashMap::new(),
         };
@@ -244,7 +245,7 b' mod tests {'
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
-        let new = DirsMultiset::new(Manifest(input_vec), None);
+        let new = DirsMultiset::new(Manifest(&input_vec), None);
         let expected = DirsMultiset {
             inner: expected_inner,
         };
@@ -269,7 +270,7 b' mod tests {'
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
-        let new = DirsMultiset::new(Dirstate(input_map), None);
+        let new = DirsMultiset::new(Dirstate(&input_map), None);
         let expected = DirsMultiset {
             inner: expected_inner,
         };
@@ -289,7 +290,7 b' mod tests {'
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
-        let new = DirsMultiset::new(Manifest(input_vec), Some('n' as i8));
+        let new = DirsMultiset::new(Manifest(&input_vec), Some('n' as i8));
         let expected = DirsMultiset {
             inner: expected_inner,
         };
@@ -318,11 +319,10 b' mod tests {'
             .map(|(k, v)| (k.as_bytes().to_vec(), *v))
             .collect();
 
-        let new = DirsMultiset::new(Dirstate(input_map), Some('n' as i8));
+        let new = DirsMultiset::new(Dirstate(&input_map), Some('n' as i8));
         let expected = DirsMultiset {
             inner: expected_inner,
         };
         assert_eq!(expected, new);
     }
-
 }

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

@@ -4,31 +4,35 b''
 // GNU General Public License version 2 or any later version.
 
 use crate::{
-    CopyVec, CopyVecEntry, DirstateEntry, DirstatePackError, DirstateParents,
-    DirstateParseError, DirstateVec,
+    dirstate::{CopyMap, StateMap},
+    utils::copy_into_array,
+    DirstateEntry, DirstatePackError, DirstateParents, DirstateParseError,
 };
 use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
-use std::collections::HashMap;
+use std::convert::TryInto;
 use std::io::Cursor;
+use std::time::Duration;
 
 /// Parents are stored in the dirstate as byte hashes.
-const PARENT_SIZE: usize = 20;
+pub const PARENT_SIZE: usize = 20;
 /// Dirstate entries have a static part of 8 + 32 + 32 + 32 + 32 bits.
 const MIN_ENTRY_SIZE: usize = 17;
 
+// TODO parse/pack: is mutate-on-loop better for performance?
+
 pub fn parse_dirstate(
+    state_map: &mut StateMap,
+    copy_map: &mut CopyMap,
     contents: &[u8],
-) -> Result<(DirstateParents, DirstateVec, CopyVec), DirstateParseError> {
+) -> Result<DirstateParents, DirstateParseError> {
     if contents.len() < PARENT_SIZE * 2 {
         return Err(DirstateParseError::TooLittleData);
     }
 
-    let mut dirstate_vec = vec![];
-    let mut copies = vec![];
     let mut curr_pos = PARENT_SIZE * 2;
     let parents = DirstateParents {
-        p1: &contents[..PARENT_SIZE],
-        p2: &contents[PARENT_SIZE..curr_pos],
+        p1: copy_into_array(&contents[..PARENT_SIZE]),
+        p2: copy_into_array(&contents[PARENT_SIZE..curr_pos]),
     };
 
     while curr_pos < contents.len() {
@@ -57,9 +61,9 b' pub fn parse_dirstate('
         };
 
         if let Some(copy_path) = copy {
-            copies.push(CopyVecEntry { path, copy_path });
+            copy_map.insert(path.to_owned(), copy_path.to_owned());
         };
-        dirstate_vec.push((
+        state_map.insert(
             path.to_owned(),
             DirstateEntry {
                 state,
@@ -67,28 +71,28 b' pub fn parse_dirstate('
                 size,
                 mtime,
             },
-        ));
+        );
         curr_pos = curr_pos + MIN_ENTRY_SIZE + (path_len);
     }
 
-    Ok((parents, dirstate_vec, copies))
+    Ok(parents)
 }
 
+/// `now` is the duration in seconds since the Unix epoch
 pub fn pack_dirstate(
-    dirstate_vec: &DirstateVec,
-    copymap: &HashMap<Vec<u8>, Vec<u8>>,
+    state_map: &mut StateMap,
+    copy_map: &CopyMap,
     parents: DirstateParents,
-    now: i32,
-) -> Result<(Vec<u8>, DirstateVec), DirstatePackError> {
-    if parents.p1.len() != PARENT_SIZE || parents.p2.len() != PARENT_SIZE {
-        return Err(DirstatePackError::CorruptedParent);
-    }
+    now: Duration,
+) -> Result<Vec<u8>, DirstatePackError> {
+    // TODO move away from i32 before 2038.
+    let now: i32 = now.as_secs().try_into().expect("time overflow");
 
-    let expected_size: usize = dirstate_vec
+    let expected_size: usize = state_map
         .iter()
-        .map(|(ref filename, _)| {
+        .map(|(filename, _)| {
             let mut length = MIN_ENTRY_SIZE + filename.len();
-            if let Some(ref copy) = copymap.get(filename) {
+            if let Some(ref copy) = copy_map.get(filename) {
                 length += copy.len() + 1;
             }
             length
@@ -97,13 +101,13 b' pub fn pack_dirstate('
     let expected_size = expected_size + PARENT_SIZE * 2;
 
     let mut packed = Vec::with_capacity(expected_size);
-    let mut new_dirstate_vec = vec![];
+    let mut new_state_map = vec![];
 
-    packed.extend(parents.p1);
-    packed.extend(parents.p2);
+    packed.extend(&parents.p1);
+    packed.extend(&parents.p2);
 
-    for (ref filename, entry) in dirstate_vec {
-        let mut new_filename: Vec<u8> = filename.to_owned();
+    for (ref filename, entry) in state_map.iter() {
+        let mut new_filename: Vec<u8> = filename.to_vec();
         let mut new_mtime: i32 = entry.mtime;
         if entry.state == 'n' as i8 && entry.mtime == now.into() {
             // The file was last modified "simultaneously" with the current
@@ -116,8 +120,8 b' pub fn pack_dirstate('
             // contents of the file if the size is the same. This prevents
             // mistakenly treating such files as clean.
             new_mtime = -1;
-            new_dirstate_vec.push((
-                filename.to_owned(),
+            new_state_map.push((
+                filename.to_owned().to_vec(),
                 DirstateEntry {
                     mtime: new_mtime,
                     ..*entry
@@ -125,7 +129,7 b' pub fn pack_dirstate('
             ));
         }
 
-        if let Some(copy) = copymap.get(filename) {
+        if let Some(copy) = copy_map.get(*filename) {
             new_filename.push('\0' as u8);
             new_filename.extend(copy);
         }
@@ -142,66 +146,36 b' pub fn pack_dirstate('
         return Err(DirstatePackError::BadSize(expected_size, packed.len()));
     }
 
-    Ok((packed, new_dirstate_vec))
+    state_map.extend(new_state_map);
+
+    Ok(packed)
 }
-
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::collections::HashMap;
 
     #[test]
     fn test_pack_dirstate_empty() {
-        let dirstate_vec: DirstateVec = vec![];
+        let mut state_map: StateMap = HashMap::new();
         let copymap = HashMap::new();
         let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
         };
-        let now: i32 = 15000000;
-        let expected =
-            (b"1234567891011121314100000000000000000000".to_vec(), vec![]);
+        let now = Duration::new(15000000, 0);
+        let expected = b"1234567891011121314100000000000000000000".to_vec();
 
         assert_eq!(
             expected,
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap()
+            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
         );
+
+        assert!(state_map.is_empty())
     }
     #[test]
     fn test_pack_dirstate_one_entry() {
-        let dirstate_vec: DirstateVec = vec![(
-            vec!['f' as u8, '1' as u8],
-            DirstateEntry {
-                state: 'n' as i8,
-                mode: 0o644,
-                size: 0,
-                mtime: 791231220,
-            },
-        )];
-        let copymap = HashMap::new();
-        let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
-        };
-        let now: i32 = 15000000;
-        let expected = (
-            [
-                49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50,
-                49, 51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
-                48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0,
-                0, 0, 0, 47, 41, 58, 244, 0, 0, 0, 2, 102, 49,
-            ]
-            .to_vec(),
-            vec![],
-        );
-
-        assert_eq!(
-            expected,
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap()
-        );
-    }
-    #[test]
-    fn test_pack_dirstate_one_entry_with_copy() {
-        let dirstate_vec: DirstateVec = vec![(
+        let expected_state_map: StateMap = [(
             b"f1".to_vec(),
             DirstateEntry {
                 state: 'n' as i8,
@@ -209,35 +183,36 b' mod tests {'
                 size: 0,
                 mtime: 791231220,
             },
-        )];
-        let mut copymap = HashMap::new();
-        copymap.insert(b"f1".to_vec(), b"copyname".to_vec());
+        )]
+        .iter()
+        .cloned()
+        .collect();
+        let mut state_map = expected_state_map.clone();
+
+        let copymap = HashMap::new();
         let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
         };
-        let now: i32 = 15000000;
-        let expected = (
-            [
-                49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50,
-                49, 51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
-                48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0,
-                0, 0, 0, 47, 41, 58, 244, 0, 0, 0, 11, 102, 49, 0, 99, 111,
-                112, 121, 110, 97, 109, 101,
-            ]
-            .to_vec(),
-            vec![],
-        );
+        let now = Duration::new(15000000, 0);
+        let expected = [
+            49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50, 49,
+            51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
+            48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0, 0, 0, 0, 47,
+            41, 58, 244, 0, 0, 0, 2, 102, 49,
+        ]
+        .to_vec();
 
         assert_eq!(
             expected,
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap()
+            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
         );
-    }
 
+        assert_eq!(expected_state_map, state_map);
+    }
     #[test]
-    fn test_parse_pack_one_entry_with_copy() {
-        let dirstate_vec: DirstateVec = vec![(
+    fn test_pack_dirstate_one_entry_with_copy() {
+        let expected_state_map: StateMap = [(
             b"f1".to_vec(),
             DirstateEntry {
                 state: 'n' as i8,
@@ -245,36 +220,76 b' mod tests {'
                 size: 0,
                 mtime: 791231220,
             },
-        )];
+        )]
+        .iter()
+        .cloned()
+        .collect();
+        let mut state_map = expected_state_map.clone();
         let mut copymap = HashMap::new();
         copymap.insert(b"f1".to_vec(), b"copyname".to_vec());
         let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
         };
-        let now: i32 = 15000000;
-        let result =
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap();
+        let now = Duration::new(15000000, 0);
+        let expected = [
+            49, 50, 51, 52, 53, 54, 55, 56, 57, 49, 48, 49, 49, 49, 50, 49,
+            51, 49, 52, 49, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
+            48, 48, 48, 48, 48, 48, 48, 48, 110, 0, 0, 1, 164, 0, 0, 0, 0, 47,
+            41, 58, 244, 0, 0, 0, 11, 102, 49, 0, 99, 111, 112, 121, 110, 97,
+            109, 101,
+        ]
+        .to_vec();
 
         assert_eq!(
-            (
-                parents,
-                dirstate_vec,
-                copymap
-                    .iter()
-                    .map(|(k, v)| CopyVecEntry {
-                        path: k.as_slice(),
-                        copy_path: v.as_slice()
-                    })
-                    .collect()
-            ),
-            parse_dirstate(result.0.as_slice()).unwrap()
+            expected,
+            pack_dirstate(&mut state_map, &copymap, parents, now).unwrap()
+        );
+        assert_eq!(expected_state_map, state_map);
+    }
+
+    #[test]
+    fn test_parse_pack_one_entry_with_copy() {
+        let mut state_map: StateMap = [(
+            b"f1".to_vec(),
+            DirstateEntry {
+                state: 'n' as i8,
+                mode: 0o644,
+                size: 0,
+                mtime: 791231220,
+            },
+        )]
+        .iter()
+        .cloned()
+        .collect();
+        let mut copymap = HashMap::new();
+        copymap.insert(b"f1".to_vec(), b"copyname".to_vec());
+        let parents = DirstateParents {
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
+        };
+        let now = Duration::new(15000000, 0);
+        let result =
+            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
+                .unwrap();
+
+        let mut new_state_map: StateMap = HashMap::new();
+        let mut new_copy_map: CopyMap = HashMap::new();
+        let new_parents = parse_dirstate(
+            &mut new_state_map,
+            &mut new_copy_map,
+            result.as_slice(),
+        )
+        .unwrap();
+        assert_eq!(
+            (parents, state_map, copymap),
+            (new_parents, new_state_map, new_copy_map)
         )
     }
 
     #[test]
     fn test_parse_pack_multiple_entries_with_copy() {
-        let dirstate_vec: DirstateVec = vec![
+        let mut state_map: StateMap = [
             (
                 b"f1".to_vec(),
                 DirstateEntry {
@@ -311,39 +326,40 b' mod tests {'
                     mtime: -1,
                 },
             ),
-        ];
+        ]
+        .iter()
+        .cloned()
+        .collect();
         let mut copymap = HashMap::new();
         copymap.insert(b"f1".to_vec(), b"copyname".to_vec());
         copymap.insert(b"f4\xF6".to_vec(), b"copyname2".to_vec());
         let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
         };
-        let now: i32 = 15000000;
+        let now = Duration::new(15000000, 0);
         let result =
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap();
+            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
+                .unwrap();
 
+        let mut new_state_map: StateMap = HashMap::new();
+        let mut new_copy_map: CopyMap = HashMap::new();
+        let new_parents = parse_dirstate(
+            &mut new_state_map,
+            &mut new_copy_map,
+            result.as_slice(),
+        )
+        .unwrap();
         assert_eq!(
-            (parents, dirstate_vec, copymap),
-            parse_dirstate(result.0.as_slice())
-                .and_then(|(p, dvec, cvec)| Ok((
-                    p,
-                    dvec,
-                    cvec.iter()
-                        .map(|entry| (
-                            entry.path.to_vec(),
-                            entry.copy_path.to_vec()
-                        ))
-                        .collect()
-                )))
-                .unwrap()
+            (parents, state_map, copymap),
+            (new_parents, new_state_map, new_copy_map)
         )
     }
 
     #[test]
     /// https://www.mercurial-scm.org/repo/hg/rev/af3f26b6bba4
     fn test_parse_pack_one_entry_with_copy_and_time_conflict() {
-        let dirstate_vec: DirstateVec = vec![(
+        let mut state_map: StateMap = [(
             b"f1".to_vec(),
             DirstateEntry {
                 state: 'n' as i8,
@@ -351,21 +367,34 b' mod tests {'
                 size: 0,
                 mtime: 15000000,
             },
-        )];
+        )]
+        .iter()
+        .cloned()
+        .collect();
         let mut copymap = HashMap::new();
         copymap.insert(b"f1".to_vec(), b"copyname".to_vec());
         let parents = DirstateParents {
-            p1: b"12345678910111213141",
-            p2: b"00000000000000000000",
+            p1: *b"12345678910111213141",
+            p2: *b"00000000000000000000",
         };
-        let now: i32 = 15000000;
+        let now = Duration::new(15000000, 0);
         let result =
-            pack_dirstate(&dirstate_vec, &copymap, parents, now).unwrap();
+            pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
+                .unwrap();
+
+        let mut new_state_map: StateMap = HashMap::new();
+        let mut new_copy_map: CopyMap = HashMap::new();
+        let new_parents = parse_dirstate(
+            &mut new_state_map,
+            &mut new_copy_map,
+            result.as_slice(),
+        )
+        .unwrap();
 
         assert_eq!(
             (
                 parents,
-                vec![(
+                [(
                     b"f1".to_vec(),
                     DirstateEntry {
                         state: 'n' as i8,
@@ -373,16 +402,13 b' mod tests {'
                         size: 0,
                         mtime: -1
                     }
-                )],
-                copymap
-                    .iter()
-                    .map(|(k, v)| CopyVecEntry {
-                        path: k.as_slice(),
-                        copy_path: v.as_slice()
-                    })
-                    .collect()
+                )]
+                .iter()
+                .cloned()
+                .collect::<StateMap>(),
+                copymap,
             ),
-            parse_dirstate(result.0.as_slice()).unwrap()
+            (new_parents, new_state_map, new_copy_map)
         )
     }
 }

rust/hg-core/src/lib.rs

@@ -10,9 +10,8 b' pub mod discovery;'
 pub mod testing; // unconditionally built, for use from integration tests
 pub use dirstate::{
     dirs_multiset::DirsMultiset,
-    parsers::{pack_dirstate, parse_dirstate},
-    CopyVec, CopyVecEntry, DirsIterable, DirstateEntry, DirstateParents,
-    DirstateVec,
+    parsers::{pack_dirstate, parse_dirstate, PARENT_SIZE},
+    CopyMap, DirsIterable, DirstateEntry, DirstateParents, StateMap,
 };
 mod filepatterns;
 pub mod utils;
@@ -60,6 +59,7 b' pub enum DirstateParseError {'
     TooLittleData,
     Overflow,
     CorruptedEntry(String),
+    Damaged,
 }
 
 #[derive(Debug, PartialEq)]

rust/hg-core/src/utils.rs

@@ -1,5 +1,22 b''
 pub mod files;
 
+use std::convert::AsMut;
+
+/// Takes a slice and copies it into an array.
+///
+/// # Panics
+///
+/// Will panic if the slice and target array don't have the same length.
+pub fn copy_into_array<A, T>(slice: &[T]) -> A
+where
+    A: Sized + Default + AsMut<[T]>,
+    T: Copy,
+{
+    let mut a = Default::default();
+    <A as AsMut<[T]>>::as_mut(&mut a).copy_from_slice(slice);
+    a
+}
+
 /// Replaces the `from` slice with the `to` slice inside the `buf` slice.
 ///
 /// # Examples

rust/hg-cpython/src/dirstate.rs

@@ -14,7 +14,7 b' use crate::dirstate::dirs_multiset::Dirs'
 use cpython::{
     PyBytes, PyDict, PyErr, PyModule, PyObject, PyResult, PySequence, Python,
 };
-use hg::{DirstateEntry, DirstateVec};
+use hg::{DirstateEntry, StateMap};
 use libc::{c_char, c_int};
 #[cfg(feature = "python27")]
 use python27_sys::PyCapsule_Import;
@@ -54,10 +54,7 b' pub fn decapsule_make_dirstate_tuple('
     }
 }
 
-pub fn extract_dirstate_vec(
-    py: Python,
-    dmap: &PyDict,
-) -> Result<DirstateVec, PyErr> {
+pub fn extract_dirstate(py: Python, dmap: &PyDict) -> Result<StateMap, PyErr> {
     dmap.items(py)
         .iter()
         .map(|(filename, stats)| {

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

@@ -15,7 +15,7 b' use cpython::{'
     ToPyObject,
 };
 
-use crate::dirstate::extract_dirstate_vec;
+use crate::dirstate::extract_dirstate;
 use hg::{DirsIterable, DirsMultiset, DirstateMapError};
 
 py_class!(pub class Dirs |py| {
@@ -32,12 +32,10 b' py_class!(pub class Dirs |py| {'
         if let Some(skip) = skip {
             skip_state = Some(skip.extract::<PyBytes>(py)?.data(py)[0] as i8);
         }
-        let dirs_map;
-
-        if let Ok(map) = map.cast_as::<PyDict>(py) {
-            let dirstate_vec = extract_dirstate_vec(py, &map)?;
-            dirs_map = DirsMultiset::new(
-                DirsIterable::Dirstate(dirstate_vec),
+        let inner = if let Ok(map) = map.cast_as::<PyDict>(py) {
+            let dirstate = extract_dirstate(py, &map)?;
+            DirsMultiset::new(
+                DirsIterable::Dirstate(&dirstate),
                 skip_state,
             )
         } else {
@@ -45,13 +43,13 b' py_class!(pub class Dirs |py| {'
                 .iter(py)?
                 .map(|o| Ok(o?.extract::<PyBytes>(py)?.data(py).to_owned()))
                 .collect();
-            dirs_map = DirsMultiset::new(
-                DirsIterable::Manifest(map?),
+            DirsMultiset::new(
+                DirsIterable::Manifest(&map?),
                 skip_state,
             )
-        }
+        };
 
-        Self::create_instance(py, RefCell::new(dirs_map))
+        Self::create_instance(py, RefCell::new(inner))
     }
 
     def addpath(&self, path: PyObject) -> PyResult<PyObject> {

rust/hg-cpython/src/parsers.rs

@@ -12,17 +12,18 b''
 //!
 use cpython::{
     exc, PyBytes, PyDict, PyErr, PyInt, PyModule, PyResult, PyTuple, Python,
-    PythonObject, ToPyObject,
+    ToPyObject,
 };
 use hg::{
-    pack_dirstate, parse_dirstate, CopyVecEntry, DirstateEntry,
-    DirstatePackError, DirstateParents, DirstateParseError,
+    pack_dirstate, parse_dirstate, utils::copy_into_array, DirstateEntry,
+    DirstatePackError, DirstateParents, DirstateParseError, PARENT_SIZE,
 };
 use std::collections::HashMap;
 
 use libc::c_char;
 
-use crate::dirstate::{decapsule_make_dirstate_tuple, extract_dirstate_vec};
+use crate::dirstate::{decapsule_make_dirstate_tuple, extract_dirstate};
+use std::time::Duration;
 
 fn parse_dirstate_wrapper(
     py: Python,
@@ -30,12 +31,15 b' fn parse_dirstate_wrapper('
     copymap: PyDict,
     st: PyBytes,
 ) -> PyResult<PyTuple> {
-    match parse_dirstate(st.data(py)) {
-        Ok((parents, dirstate_vec, copies)) => {
-            for (filename, entry) in dirstate_vec {
+    let mut dirstate_map = HashMap::new();
+    let mut copies = HashMap::new();
+
+    match parse_dirstate(&mut dirstate_map, &mut copies, st.data(py)) {
+        Ok(parents) => {
+            for (filename, entry) in dirstate_map {
                 dmap.set_item(
                     py,
-                    PyBytes::new(py, &filename[..]),
+                    PyBytes::new(py, &filename),
                     decapsule_make_dirstate_tuple(py)?(
                         entry.state as c_char,
                         entry.mode,
@@ -44,15 +48,17 b' fn parse_dirstate_wrapper('
                     ),
                 )?;
             }
-            for CopyVecEntry { path, copy_path } in copies {
+            for (path, copy_path) in copies {
                 copymap.set_item(
                     py,
-                    PyBytes::new(py, path),
-                    PyBytes::new(py, copy_path),
+                    PyBytes::new(py, &path),
+                    PyBytes::new(py, &copy_path),
                 )?;
             }
-            Ok((PyBytes::new(py, parents.p1), PyBytes::new(py, parents.p2))
-                .to_py_object(py))
+            Ok(
+                (PyBytes::new(py, &parents.p1), PyBytes::new(py, &parents.p2))
+                    .to_py_object(py),
+            )
         }
         Err(e) => Err(PyErr::new::<exc::ValueError, _>(
             py,
@@ -64,6 +70,9 b' fn parse_dirstate_wrapper('
                     "overflow in dirstate".to_string()
                 }
                 DirstateParseError::CorruptedEntry(e) => e,
+                DirstateParseError::Damaged => {
+                    "dirstate appears to be damaged".to_string()
+                }
             },
         )),
     }
@@ -81,7 +90,7 b' fn pack_dirstate_wrapper('
     let p2 = pl.get_item(py, 1).extract::<PyBytes>(py)?;
     let p2: &[u8] = p2.data(py);
 
-    let dirstate_vec = extract_dirstate_vec(py, &dmap)?;
+    let mut dirstate_map = extract_dirstate(py, &dmap)?;
 
     let copies: Result<HashMap<Vec<u8>, Vec<u8>>, PyErr> = copymap
         .items(py)
@@ -94,13 +103,23 b' fn pack_dirstate_wrapper('
         })
         .collect();
 
+    if p1.len() != PARENT_SIZE || p2.len() != PARENT_SIZE {
+        return Err(PyErr::new::<exc::ValueError, _>(
+            py,
+            "expected a 20-byte hash".to_string(),
+        ));
+    }
+
     match pack_dirstate(
-        &dirstate_vec,
+        &mut dirstate_map,
         &copies?,
-        DirstateParents { p1, p2 },
-        now.as_object().extract::<i32>(py)?,
+        DirstateParents {
+            p1: copy_into_array(&p1),
+            p2: copy_into_array(&p2),
+        },
+        Duration::from_secs(now.value(py) as u64),
     ) {
-        Ok((packed, new_dirstate_vec)) => {
+        Ok(packed) => {
             for (
                 filename,
                 DirstateEntry {
@@ -109,7 +128,7 b' fn pack_dirstate_wrapper('
                     size,
                     mtime,
                 },
-            ) in new_dirstate_vec
+            ) in dirstate_map
             {
                 dmap.set_item(
                     py,