Mercurial > hg
view rust/hg-core/src/dirstate_tree/dirstate_map.rs @ 47332:4ee9f419c52e
rust: Return owned instead of borrowed DirstateEntry in DirstateMap APIs
This will enable the tree-based DirstateMap to not always have an actual
DirstateEntry in memory for all nodes, but construct it on demand.
Differential Revision: https://phab.mercurial-scm.org/D10746
author | Simon Sapin <simon.sapin@octobus.net> |
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date | Wed, 19 May 2021 13:15:00 +0200 |
parents | 0252600fd1cf |
children | 69530e5d4fe5 |
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use bytes_cast::BytesCast; use micro_timer::timed; use std::borrow::Cow; use std::convert::TryInto; use std::path::PathBuf; use super::on_disk; 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::parsers::Timestamp; use crate::matchers::Matcher; 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::PatternFileWarning; use crate::StateMapIter; use crate::StatusError; use crate::StatusOptions; 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, } /// 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>>; pub(super) type ChildNodes<'on_disk> = FastHashMap<NodeKey<'on_disk>, Node<'on_disk>>; /// Represents a file or a directory #[derive(Default)] pub(super) struct Node<'on_disk> { /// `None` for directories pub(super) entry: Option<DirstateEntry>, pub(super) copy_source: Option<Cow<'on_disk, HgPath>>, pub(super) children: ChildNodes<'on_disk>, /// How many (non-inclusive) descendants of this node are tracked files pub(super) tracked_descendants_count: u32, } impl<'on_disk> Node<'on_disk> { pub(super) fn state(&self) -> Option<EntryState> { self.entry.as_ref().map(|entry| entry.state) } pub(super) fn sorted<'tree>( nodes: &'tree ChildNodes<'on_disk>, ) -> Vec<(&'tree NodeKey<'on_disk>, &'tree Self)> { let mut vec: Vec<_> = nodes.iter().collect(); // `sort_unstable_by_key` doesn’t allow keys borrowing from the value: // https://github.com/rust-lang/rust/issues/34162 vec.sort_unstable_by(|(path1, _), (path2, _)| path1.cmp(path2)); vec } } 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, } } #[timed] pub fn new_v2( on_disk: &'on_disk [u8], ) -> Result<(Self, Option<DirstateParents>), DirstateError> { on_disk::read(on_disk) } #[timed] pub fn new_v1( on_disk: &'on_disk [u8], ) -> Result<(Self, Option<DirstateParents>), DirstateError> { let mut map = Self::empty(on_disk); 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.state.is_tracked(); let node = Self::get_or_insert_node( &mut map.root, path, WithBasename::to_cow_borrowed, |ancestor| { if tracked { ancestor.tracked_descendants_count += 1 } }, ); assert!( node.entry.is_none(), "duplicate dirstate entry in read" ); assert!( node.copy_source.is_none(), "duplicate dirstate entry in read" ); node.entry = Some(*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 } }, )?; let parents = Some(parents.clone()); Ok((map, parents)) } 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<'on_disk>, path: &HgPath, ) -> Option<&'tree mut Node<'on_disk>> { 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)?; if let Some(next_component) = components.next() { component = next_component; children = &mut child.children; } else { return Some(child); } } } fn get_or_insert_node<'tree, 'path>( 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), ) -> &'tree mut Node<'on_disk> { 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 allocating an owned key in cases where the // map already contains that key, without introducing double // lookup? let child_node = child_nodes.entry(to_cow(ancestor_path)).or_default(); if let Some(next) = inclusive_ancestor_paths.next() { each_ancestor(child_node); ancestor_path = next; child_nodes = &mut child_node.children; } else { return child_node; } } } fn add_or_remove_file( &mut self, path: &HgPath, old_state: EntryState, new_entry: DirstateEntry, ) { let tracked_count_increment = match (old_state.is_tracked(), new_entry.state.is_tracked()) { (false, true) => 1, (true, false) => -1, _ => 0, }; let node = Self::get_or_insert_node( &mut self.root, path, WithBasename::to_cow_owned, |ancestor| { // We can’t use `+= increment` because the counter is unsigned, // and we want debug builds to detect accidental underflow // through zero match tracked_count_increment { 1 => ancestor.tracked_descendants_count += 1, -1 => ancestor.tracked_descendants_count -= 1, _ => {} } }, ); if node.entry.is_none() { self.nodes_with_entry_count += 1 } node.entry = Some(new_entry) } fn iter_nodes<'a>( &'a self, ) -> impl Iterator<Item = (&'a Cow<'on_disk, HgPath>, &'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); let key = key.full_path(); 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 } }) } fn clear_known_ambiguous_mtimes(&mut self, paths: &[impl AsRef<HgPath>]) { for path in paths { if let Some(node) = Self::get_node_mut(&mut self.root, path.as_ref()) { if let Some(entry) = node.entry.as_mut() { entry.clear_mtime(); } } } } } impl<'on_disk> super::dispatch::DirstateMapMethods for DirstateMap<'on_disk> { fn clear(&mut self) { 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> { self.add_or_remove_file(filename, old_state, entry); Ok(()) } fn remove_file( &mut self, filename: &HgPath, old_state: EntryState, size: i32, ) -> Result<(), DirstateMapError> { let entry = DirstateEntry { state: EntryState::Removed, mode: 0, size, mtime: 0, }; self.add_or_remove_file(filename, old_state, entry); Ok(()) } fn drop_file( &mut self, filename: &HgPath, old_state: EntryState, ) -> Result<bool, DirstateMapError> { struct Dropped { was_tracked: bool, had_entry: bool, had_copy_source: bool, } fn recur(nodes: &mut ChildNodes, path: &HgPath) -> Option<Dropped> { let (first_path_component, rest_of_path) = path.split_first_component(); let node = nodes.get_mut(first_path_component)?; let dropped; if let Some(rest) = rest_of_path { dropped = recur(&mut node.children, rest)?; if dropped.was_tracked { node.tracked_descendants_count -= 1; } } else { dropped = Dropped { was_tracked: node .entry .as_ref() .map_or(false, |entry| entry.state.is_tracked()), had_entry: node.entry.take().is_some(), had_copy_source: node.copy_source.take().is_some(), }; } // After recursion, for both leaf (rest_of_path is None) nodes and // parent nodes, remove a node if it just became empty. if node.entry.is_none() && node.copy_source.is_none() && node.children.is_empty() { nodes.remove(first_path_component); } Some(dropped) } if let Some(dropped) = recur(&mut self.root, filename) { if dropped.had_entry { self.nodes_with_entry_count -= 1 } if dropped.had_copy_source { self.nodes_with_copy_source_count -= 1 } Ok(dropped.had_entry) } else { debug_assert!(!old_state.is_tracked()); Ok(false) } } 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() { entry.clear_ambiguous_mtime(now); } } } } fn non_normal_entries_contains(&mut self, key: &HgPath) -> bool { self.get_node(key) .and_then(|node| node.entry.as_ref()) .map_or(false, DirstateEntry::is_non_normal) } fn non_normal_entries_remove(&mut self, _key: &HgPath) { // Do nothing, this `DirstateMap` does not have a separate "non normal // entries" set that need to be kept up to date } fn non_normal_or_other_parent_paths( &mut self, ) -> Box<dyn Iterator<Item = &HgPath> + '_> { Box::new(self.iter_nodes().filter_map(|(path, node)| { node.entry .as_ref() .filter(|entry| { entry.is_non_normal() || entry.is_from_other_parent() }) .map(|_| &**path) })) } fn set_non_normal_other_parent_entries(&mut self, _force: bool) { // Do nothing, this `DirstateMap` does not have a separate "non normal // entries" and "from other parent" sets that need to be recomputed } fn iter_non_normal_paths( &mut self, ) -> Box<dyn Iterator<Item = &HgPath> + Send + '_> { self.iter_non_normal_paths_panic() } fn iter_non_normal_paths_panic( &self, ) -> Box<dyn Iterator<Item = &HgPath> + Send + '_> { Box::new(self.iter_nodes().filter_map(|(path, node)| { node.entry .as_ref() .filter(|entry| entry.is_non_normal()) .map(|_| &**path) })) } fn iter_other_parent_paths( &mut self, ) -> Box<dyn Iterator<Item = &HgPath> + Send + '_> { Box::new(self.iter_nodes().filter_map(|(path, node)| { node.entry .as_ref() .filter(|entry| entry.is_from_other_parent()) .map(|_| &**path) })) } fn has_tracked_dir( &mut self, directory: &HgPath, ) -> Result<bool, DirstateMapError> { 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, ) -> Result<bool, DirstateMapError> { 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) } } #[timed] fn pack_v1( &mut self, parents: DirstateParents, now: Timestamp, ) -> Result<Vec<u8>, DirstateError> { let now: i32 = now.0.try_into().expect("time overflow"); let mut ambiguous_mtimes = Vec::new(); // 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 let Some(entry) = &node.entry { size += packed_entry_size( path, node.copy_source.as_ref().map(|p| &**p), ); if entry.mtime_is_ambiguous(now) { ambiguous_mtimes.push(path.clone()) } } } self.clear_known_ambiguous_mtimes(&ambiguous_mtimes); let mut packed = Vec::with_capacity(size); packed.extend(parents.as_bytes()); for (path, node) in self.iter_nodes() { if let Some(entry) = &node.entry { pack_entry( path, entry, node.copy_source.as_ref().map(|p| &**p), &mut packed, ); } } Ok(packed) } #[timed] fn pack_v2( &mut self, parents: DirstateParents, now: Timestamp, ) -> Result<Vec<u8>, DirstateError> { // TODO: how do we want to handle this in 2038? let now: i32 = now.0.try_into().expect("time overflow"); let mut paths = Vec::new(); for (path, node) in self.iter_nodes() { if let Some(entry) = &node.entry { if entry.mtime_is_ambiguous(now) { paths.push(path.clone()) } } } // Borrow of `self` ends here since we collect cloned paths self.clear_known_ambiguous_mtimes(&paths); on_disk::write(self, parents) } fn set_all_dirs(&mut self) -> Result<(), DirstateMapError> { // Do nothing, this `DirstateMap` does not a separate `all_dirs` that // needs to be recomputed Ok(()) } fn set_dirs(&mut self) -> Result<(), DirstateMapError> { // Do nothing, this `DirstateMap` does not a separate `dirs` that needs // to be recomputed Ok(()) } fn status<'a>( &'a mut self, matcher: &'a (dyn Matcher + Sync), root_dir: PathBuf, ignore_files: Vec<PathBuf>, options: StatusOptions, ) -> Result<(DirstateStatus<'a>, Vec<PatternFileWarning>), StatusError> { super::status::status(self, matcher, root_dir, ignore_files, options) } fn copy_map_len(&self) -> usize { self.nodes_with_copy_source_count as usize } fn copy_map_iter(&self) -> CopyMapIter<'_> { Box::new(self.iter_nodes().filter_map(|(path, node)| { node.copy_source .as_ref() .map(|copy_source| (&**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<&HgPath> { self.get_node(key)?.copy_source.as_ref().map(|p| &**p) } 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().map(Cow::into_owned) }) } fn copy_map_insert( &mut self, key: HgPathBuf, value: HgPathBuf, ) -> Option<HgPathBuf> { let node = Self::get_or_insert_node( &mut self.root, &key, WithBasename::to_cow_owned, |_ancestor| {}, ); if node.copy_source.is_none() { self.nodes_with_copy_source_count += 1 } node.copy_source.replace(value.into()).map(Cow::into_owned) } fn len(&self) -> usize { self.nodes_with_entry_count as usize } fn contains_key(&self, key: &HgPath) -> bool { self.get(key).is_some() } fn get(&self, key: &HgPath) -> Option<DirstateEntry> { self.get_node(key)?.entry } fn iter(&self) -> StateMapIter<'_> { Box::new(self.iter_nodes().filter_map(|(path, node)| { node.entry.map(|entry| (&**path, entry)) })) } }