dirstate-tree: Add has_dir and has_tracked_dir

A node without a `DirstateMap` entry represents a directory.

Only some values of `EntryState` represent tracked files.
A directory is considered "tracked" if it contains any descendant file that
is tracked. To avoid a sub-tree traversal in `has_tracked_dir` we add a
counter for this. A boolean flag would become insufficent when we implement
remove_file and drop_file.

`add_file_node` is more general than needed here, in anticipation of adding
the `add_file` and `remove_file` methods.

Differential Revision: https://phab.mercurial-scm.org/D10490

rust/hg-core/src/dirstate.rs

@@ -1,97 +1,107 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 crate::errors::HgError;
 use crate::revlog::Node;
 use crate::{utils::hg_path::HgPathBuf, FastHashMap};
 use bytes_cast::{unaligned, BytesCast};
 use std::convert::TryFrom;
 
 pub mod dirs_multiset;
 pub mod dirstate_map;
 pub mod parsers;
 pub mod status;
 
 #[derive(Debug, PartialEq, Clone, BytesCast)]
 #[repr(C)]
 pub struct DirstateParents {
     pub p1: Node,
     pub p2: Node,
 }
 
 /// 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, Copy, Clone)]
 pub struct DirstateEntry {
     pub state: EntryState,
     pub mode: i32,
     pub mtime: i32,
     pub size: i32,
 }
 
 #[derive(BytesCast)]
 #[repr(C)]
 struct RawEntry {
     state: u8,
     mode: unaligned::I32Be,
     size: unaligned::I32Be,
     mtime: unaligned::I32Be,
     length: unaligned::I32Be,
 }
 
 /// A `DirstateEntry` with a size of `-2` means that it was merged from the
 /// other parent. This allows revert to pick the right status back during a
 /// merge.
 pub const SIZE_FROM_OTHER_PARENT: i32 = -2;
 
 pub type StateMap = FastHashMap<HgPathBuf, DirstateEntry>;
 pub type StateMapIter<'a> =
     Box<dyn Iterator<Item = (&'a HgPathBuf, &'a DirstateEntry)> + Send + 'a>;
 
 pub type CopyMap = FastHashMap<HgPathBuf, HgPathBuf>;
 pub type CopyMapIter<'a> =
     Box<dyn Iterator<Item = (&'a HgPathBuf, &'a HgPathBuf)> + Send + 'a>;
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum EntryState {
     Normal,
     Added,
     Removed,
     Merged,
     Unknown,
 }
 
+impl EntryState {
+    pub fn is_tracked(self) -> bool {
+        use EntryState::*;
+        match self {
+            Normal | Added | Merged => true,
+            Removed | Unknown => false,
+        }
+    }
+}
+
 impl TryFrom<u8> for EntryState {
     type Error = HgError;
 
     fn try_from(value: u8) -> Result<Self, Self::Error> {
         match value {
             b'n' => Ok(EntryState::Normal),
             b'a' => Ok(EntryState::Added),
             b'r' => Ok(EntryState::Removed),
             b'm' => Ok(EntryState::Merged),
             b'?' => Ok(EntryState::Unknown),
             _ => Err(HgError::CorruptedRepository(format!(
                 "Incorrect dirstate entry state {}",
                 value
             ))),
         }
     }
 }
 
 impl Into<u8> for EntryState {
     fn into(self) -> u8 {
         match self {
             EntryState::Normal => b'n',
             EntryState::Added => b'a',
             EntryState::Removed => b'r',
             EntryState::Merged => b'm',
             EntryState::Unknown => b'?',
         }
     }
 }

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

@@ -1,526 +1,609 b''
 use bytes_cast::BytesCast;
 use std::path::PathBuf;
 use std::{collections::BTreeMap, convert::TryInto};
 
 use super::path_with_basename::WithBasename;
 use crate::dirstate::parsers::clear_ambiguous_mtime;
 use crate::dirstate::parsers::pack_entry;
 use crate::dirstate::parsers::packed_entry_size;
 use crate::dirstate::parsers::parse_dirstate_entries;
 use crate::dirstate::parsers::parse_dirstate_parents;
 use crate::dirstate::parsers::Timestamp;
 use crate::matchers::Matcher;
 use crate::revlog::node::NULL_NODE;
 use crate::utils::hg_path::{HgPath, HgPathBuf};
 use crate::CopyMapIter;
 use crate::DirstateEntry;
 use crate::DirstateError;
 use crate::DirstateMapError;
 use crate::DirstateParents;
 use crate::DirstateStatus;
 use crate::EntryState;
 use crate::FastHashMap;
 use crate::HgPathCow;
 use crate::PatternFileWarning;
 use crate::StateMapIter;
 use crate::StatusError;
 use crate::StatusOptions;
 
 pub struct DirstateMap {
     parents: Option<DirstateParents>,
     dirty_parents: bool,
     root: ChildNodes,
 
     /// Number of nodes anywhere in the tree that have `.entry.is_some()`.
     nodes_with_entry_count: usize,
 
     /// Number of nodes anywhere in the tree that have
     /// `.copy_source.is_some()`.
     nodes_with_copy_source_count: usize,
 }
 
 /// 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 `BTreeMap` would waste time always re-comparing the same
 /// string prefix.
 type ChildNodes = BTreeMap<WithBasename<HgPathBuf>, Node>;
 
+/// Represents a file or a directory
 #[derive(Default)]
 struct Node {
+    /// `None` for directories
     entry: Option<DirstateEntry>,
+
     copy_source: Option<HgPathBuf>,
+
     children: ChildNodes,
+
+    /// How many (non-inclusive) descendants of this node are tracked files
+    tracked_descendants_count: usize,
+}
+
+impl Node {
+    /// Whether this node has a `DirstateEntry` with `.state.is_tracked()`
+    fn is_tracked_file(&self) -> bool {
+        if let Some(entry) = &self.entry {
+            entry.state.is_tracked()
+        } else {
+            false
+        }
+    }
 }
 
 /// `(full_path, entry, copy_source)`
 type NodeDataMut<'a> = (
     &'a WithBasename<HgPathBuf>,
     &'a mut Option<DirstateEntry>,
     &'a mut Option<HgPathBuf>,
 );
 
 impl DirstateMap {
     pub fn new() -> Self {
         Self {
             parents: None,
             dirty_parents: false,
             root: ChildNodes::new(),
             nodes_with_entry_count: 0,
             nodes_with_copy_source_count: 0,
         }
     }
 
     fn get_node(&self, path: &HgPath) -> Option<&Node> {
         let mut children = &self.root;
         let mut components = path.components();
         let mut component =
             components.next().expect("expected at least one components");
         loop {
             let child = children.get(component)?;
             if let Some(next_component) = components.next() {
                 component = next_component;
                 children = &child.children;
             } else {
                 return Some(child);
             }
         }
     }
 
+    /// Returns a mutable reference to the node at `path` if it exists
+    ///
     /// This takes `root` instead of `&mut self` so that callers can mutate
     /// other fields while the returned borrow is still valid
     fn get_node_mut<'tree>(
         root: &'tree mut ChildNodes,
         path: &HgPath,
     ) -> Option<&'tree mut Node> {
+        Self::each_and_get(root, path, |_| {})
+    }
+
+    /// Call `each` for each ancestor node of the one at `path` (not including
+    /// that node itself), starting from nearest the root.
+    ///
+    /// Panics (possibly after some calls to `each`) if there is no node at
+    /// `path`.
+    fn for_each_ancestor_node<'tree>(
+        &mut self,
+        path: &HgPath,
+        each: impl FnMut(&mut Node),
+    ) {
+        let parent = path.parent();
+        if !parent.is_empty() {
+            Self::each_and_get(&mut self.root, parent, each)
+                .expect("missing dirstate node");
+        }
+    }
+
+    /// Common implementation detail of `get_node_mut` and
+    /// `for_each_ancestor_node`
+    fn each_and_get<'tree>(
+        root: &'tree mut ChildNodes,
+        path: &HgPath,
+        mut each: impl FnMut(&mut Node),
+    ) -> Option<&'tree mut Node> {
         let mut children = root;
         let mut components = path.components();
         let mut component =
             components.next().expect("expected at least one components");
         loop {
             let child = children.get_mut(component)?;
+            each(child);
             if let Some(next_component) = components.next() {
                 component = next_component;
                 children = &mut child.children;
             } else {
                 return Some(child);
             }
         }
     }
 
     fn get_or_insert_node<'tree>(
         root: &'tree mut ChildNodes,
         path: &HgPath,
     ) -> &'tree mut Node {
         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 {
             // TODO: can we avoid double lookup in all cases without allocating
             // an owned key in cases where the map already contains that key?
             let child_node =
                 if child_nodes.contains_key(ancestor_path.base_name()) {
                     child_nodes.get_mut(ancestor_path.base_name()).unwrap()
                 } else {
                     // This is always a vacant entry, using `.entry()` lets us
                     // return a `&mut Node` of the newly-inserted node without
                     // yet another lookup. `BTreeMap::insert` doesn’t do this.
                     child_nodes.entry(ancestor_path.to_owned()).or_default()
                 };
             if let Some(next) = inclusive_ancestor_paths.next() {
                 ancestor_path = next;
                 child_nodes = &mut child_node.children;
             } else {
                 return child_node;
             }
         }
     }
 
     /// The meaning of `new_copy_source` is:
     ///
     /// * `Some(Some(x))`: set `Node::copy_source` to `Some(x)`
     /// * `Some(None)`: set `Node::copy_source` to `None`
     /// * `None`: leave `Node::copy_source` unchanged
     fn add_file_node(
         &mut self,
         path: &HgPath,
         new_entry: DirstateEntry,
         new_copy_source: Option<Option<HgPathBuf>>,
     ) {
         let node = Self::get_or_insert_node(&mut self.root, path);
         if node.entry.is_none() {
             self.nodes_with_entry_count += 1
         }
         if let Some(source) = &new_copy_source {
             if node.copy_source.is_none() && source.is_some() {
                 self.nodes_with_copy_source_count += 1
             }
             if node.copy_source.is_some() && source.is_none() {
                 self.nodes_with_copy_source_count -= 1
             }
         }
+        let tracked_count_increment =
+            match (node.is_tracked_file(), new_entry.state.is_tracked()) {
+                (false, true) => 1,
+                (true, false) => -1,
+                _ => 0,
+            };
+
         node.entry = Some(new_entry);
         if let Some(source) = new_copy_source {
             node.copy_source = source
         }
+        // Borrow of `self.root` through `node` ends here
+
+        match tracked_count_increment {
+            1 => self.for_each_ancestor_node(path, |node| {
+                node.tracked_descendants_count += 1
+            }),
+            // We can’t use `+= -1` because the counter is unsigned
+            -1 => self.for_each_ancestor_node(path, |node| {
+                node.tracked_descendants_count -= 1
+            }),
+            _ => {}
+        }
     }
 
     fn iter_nodes<'a>(
         &'a self,
     ) -> impl Iterator<Item = (&'a WithBasename<HgPathBuf>, &'a Node)> + 'a
     {
         // 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.iter();
         std::iter::from_fn(move || {
             while let Some((key, child_node)) = iter.next() {
                 // Pseudo-recursion
                 let new_iter = child_node.children.iter();
                 let old_iter = std::mem::replace(&mut iter, new_iter);
                 stack.push((key, child_node, old_iter));
             }
             // Found the end of a `children.iter()` iterator.
             if let Some((key, child_node, next_iter)) = stack.pop() {
                 // "Return" from pseudo-recursion by restoring state from the
                 // explicit stack
                 iter = next_iter;
 
                 Some((key, child_node))
             } else {
                 // Reached the bottom of the stack, we’re done
                 None
             }
         })
     }
 
     /// Mutable iterator for the `(entry, copy source)` of each node.
     ///
     /// It would not be safe to yield mutable references to nodes themeselves
     /// with `-> impl Iterator<Item = &mut Node>` since child nodes are
     /// reachable from their ancestor nodes, potentially creating multiple
     /// `&mut` references to a given node.
     fn iter_node_data_mut<'a>(
         &'a mut self,
     ) -> impl Iterator<Item = NodeDataMut<'a>> + 'a {
         // Explict stack for pseudo-recursion, see `iter_nodes` above.
         let mut stack = Vec::new();
         let mut iter = self.root.iter_mut();
         std::iter::from_fn(move || {
             while let Some((key, child_node)) = iter.next() {
                 // Pseudo-recursion
                 let data =
                     (key, &mut child_node.entry, &mut child_node.copy_source);
                 let new_iter = child_node.children.iter_mut();
                 let old_iter = std::mem::replace(&mut iter, new_iter);
                 stack.push((data, old_iter));
             }
             // Found the end of a `children.values_mut()` iterator.
             if let Some((data, next_iter)) = stack.pop() {
                 // "Return" from pseudo-recursion by restoring state from the
                 // explicit stack
                 iter = next_iter;
 
                 Some(data)
             } else {
                 // Reached the bottom of the stack, we’re done
                 None
             }
         })
     }
 }
 
 impl super::dispatch::DirstateMapMethods for DirstateMap {
     fn clear(&mut self) {
         self.set_parents(&DirstateParents {
             p1: NULL_NODE,
             p2: NULL_NODE,
         });
         self.root.clear();
         self.nodes_with_entry_count = 0;
         self.nodes_with_copy_source_count = 0;
     }
 
     fn add_file(
         &mut self,
         _filename: &HgPath,
         _old_state: EntryState,
         _entry: DirstateEntry,
     ) -> Result<(), DirstateMapError> {
         todo!()
     }
 
     fn remove_file(
         &mut self,
         _filename: &HgPath,
         _old_state: EntryState,
         _size: i32,
     ) -> Result<(), DirstateMapError> {
         todo!()
     }
 
     fn drop_file(
         &mut self,
         _filename: &HgPath,
         _old_state: EntryState,
     ) -> Result<bool, DirstateMapError> {
         todo!()
     }
 
     fn clear_ambiguous_times(&mut self, filenames: Vec<HgPathBuf>, now: i32) {
         for filename in filenames {
             if let Some(node) = Self::get_node_mut(&mut self.root, &filename) {
                 if let Some(entry) = node.entry.as_mut() {
                     clear_ambiguous_mtime(entry, now);
                 }
             }
         }
     }
 
     fn non_normal_entries_contains(&mut self, _key: &HgPath) -> bool {
         todo!()
     }
 
     fn non_normal_entries_remove(&mut self, _key: &HgPath) -> bool {
         todo!()
     }
 
     fn non_normal_or_other_parent_paths(
         &mut self,
     ) -> Box<dyn Iterator<Item = &HgPathBuf> + '_> {
         todo!()
     }
 
     fn set_non_normal_other_parent_entries(&mut self, _force: bool) {
         todo!()
     }
 
     fn iter_non_normal_paths(
         &mut self,
     ) -> Box<dyn Iterator<Item = &HgPathBuf> + Send + '_> {
         todo!()
     }
 
     fn iter_non_normal_paths_panic(
         &self,
     ) -> Box<dyn Iterator<Item = &HgPathBuf> + Send + '_> {
         todo!()
     }
 
     fn iter_other_parent_paths(
         &mut self,
     ) -> Box<dyn Iterator<Item = &HgPathBuf> + Send + '_> {
         todo!()
     }
 
     fn has_tracked_dir(
         &mut self,
-        _directory: &HgPath,
+        directory: &HgPath,
     ) -> Result<bool, DirstateMapError> {
-        todo!()
+        if let Some(node) = self.get_node(directory) {
+            // A node without a `DirstateEntry` was created to hold child
+            // nodes, and is therefore a directory.
+            Ok(node.entry.is_none() && node.tracked_descendants_count > 0)
+        } else {
+            Ok(false)
+        }
     }
 
     fn has_dir(
         &mut self,
-        _directory: &HgPath,
+        directory: &HgPath,
     ) -> Result<bool, DirstateMapError> {
-        todo!()
+        if let Some(node) = self.get_node(directory) {
+            // A node without a `DirstateEntry` was created to hold child
+            // nodes, and is therefore a directory.
+            Ok(node.entry.is_none())
+        } else {
+            Ok(false)
+        }
     }
 
     fn parents(
         &mut self,
         file_contents: &[u8],
     ) -> Result<&DirstateParents, DirstateError> {
         if self.parents.is_none() {
             let parents = if !file_contents.is_empty() {
                 parse_dirstate_parents(file_contents)?.clone()
             } else {
                 DirstateParents {
                     p1: NULL_NODE,
                     p2: NULL_NODE,
                 }
             };
             self.parents = Some(parents);
         }
         Ok(self.parents.as_ref().unwrap())
     }
 
     fn set_parents(&mut self, parents: &DirstateParents) {
         self.parents = Some(parents.clone());
         self.dirty_parents = true;
     }
 
     fn read<'a>(
         &mut self,
         file_contents: &'a [u8],
     ) -> Result<Option<&'a DirstateParents>, DirstateError> {
         if file_contents.is_empty() {
             return Ok(None);
         }
 
         let parents = parse_dirstate_entries(
             file_contents,
             |path, entry, copy_source| {
                 self.add_file_node(
                     path,
                     *entry,
                     Some(copy_source.map(HgPath::to_owned)),
                 )
             },
         )?;
 
         if !self.dirty_parents {
             self.set_parents(parents);
         }
 
         Ok(Some(parents))
     }
 
     fn pack(
         &mut self,
         parents: DirstateParents,
         now: Timestamp,
     ) -> Result<Vec<u8>, DirstateError> {
         // Optizimation (to be measured?): pre-compute size to avoid `Vec`
         // reallocations
         let mut size = parents.as_bytes().len();
         for (path, node) in self.iter_nodes() {
             if node.entry.is_some() {
                 size += packed_entry_size(
                     path.full_path(),
                     node.copy_source.as_ref(),
                 )
             }
         }
 
         let mut packed = Vec::with_capacity(size);
         packed.extend(parents.as_bytes());
 
         let now: i32 = now.0.try_into().expect("time overflow");
         for (path, opt_entry, copy_source) in self.iter_node_data_mut() {
             if let Some(entry) = opt_entry {
                 clear_ambiguous_mtime(entry, now);
                 pack_entry(
                     path.full_path(),
                     entry,
                     copy_source.as_ref(),
                     &mut packed,
                 );
             }
         }
         self.dirty_parents = false;
         Ok(packed)
     }
 
     fn build_file_fold_map(&mut self) -> &FastHashMap<HgPathBuf, HgPathBuf> {
         todo!()
     }
 
     fn set_all_dirs(&mut self) -> Result<(), DirstateMapError> {
-        todo!()
+        // Do nothing, this `DirstateMap` does not a separate `all_dirs` that
+        // needs to be recomputed
+        Ok(())
     }
 
     fn set_dirs(&mut self) -> Result<(), DirstateMapError> {
-        todo!()
+        // Do nothing, this `DirstateMap` does not a separate `dirs` that needs
+        // to be recomputed
+        Ok(())
     }
 
     fn status<'a>(
         &'a self,
         _matcher: &'a (dyn Matcher + Sync),
         _root_dir: PathBuf,
         _ignore_files: Vec<PathBuf>,
         _options: StatusOptions,
     ) -> Result<
         (
             (Vec<HgPathCow<'a>>, DirstateStatus<'a>),
             Vec<PatternFileWarning>,
         ),
         StatusError,
     > {
         todo!()
     }
 
     fn copy_map_len(&self) -> usize {
         self.nodes_with_copy_source_count
     }
 
     fn copy_map_iter(&self) -> CopyMapIter<'_> {
         Box::new(self.iter_nodes().filter_map(|(path, node)| {
             node.copy_source
                 .as_ref()
                 .map(|copy_source| (path.full_path(), copy_source))
         }))
     }
 
     fn copy_map_contains_key(&self, key: &HgPath) -> bool {
         if let Some(node) = self.get_node(key) {
             node.copy_source.is_some()
         } else {
             false
         }
     }
 
     fn copy_map_get(&self, key: &HgPath) -> Option<&HgPathBuf> {
         self.get_node(key)?.copy_source.as_ref()
     }
 
     fn copy_map_remove(&mut self, key: &HgPath) -> Option<HgPathBuf> {
         let count = &mut self.nodes_with_copy_source_count;
         Self::get_node_mut(&mut self.root, key).and_then(|node| {
             if node.copy_source.is_some() {
                 *count -= 1
             }
             node.copy_source.take()
         })
     }
 
     fn copy_map_insert(
         &mut self,
         key: HgPathBuf,
         value: HgPathBuf,
     ) -> Option<HgPathBuf> {
         let node = Self::get_or_insert_node(&mut self.root, &key);
         if node.copy_source.is_none() {
             self.nodes_with_copy_source_count += 1
         }
         node.copy_source.replace(value)
     }
 
     fn len(&self) -> usize {
         self.nodes_with_entry_count
     }
 
     fn contains_key(&self, key: &HgPath) -> bool {
         self.get(key).is_some()
     }
 
     fn get(&self, key: &HgPath) -> Option<&DirstateEntry> {
         self.get_node(key)?.entry.as_ref()
     }
 
     fn iter(&self) -> StateMapIter<'_> {
         Box::new(self.iter_nodes().filter_map(|(path, node)| {
             node.entry.as_ref().map(|entry| (path.full_path(), entry))
         }))
     }
 }