Mercurial > hg
view rust/hg-core/src/repo.rs @ 47958:fc208d6faed3
rust: Move lazy initialization of `Repo::dirstate_map` into a generic struct
More components of `Repo` will be added following the same pattern.
Differential Revision: https://phab.mercurial-scm.org/D11405
author | Simon Sapin <simon.sapin@octobus.net> |
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date | Mon, 13 Sep 2021 13:16:10 +0200 |
parents | 81aedf1fc897 |
children | 21d25e9ee58e |
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use crate::config::{Config, ConfigError, ConfigParseError}; use crate::dirstate::DirstateParents; use crate::dirstate_tree::dirstate_map::DirstateMap; use crate::dirstate_tree::owning::OwningDirstateMap; use crate::errors::HgError; use crate::errors::HgResultExt; use crate::exit_codes; use crate::requirements; use crate::utils::files::get_path_from_bytes; use crate::utils::SliceExt; use crate::vfs::{is_dir, is_file, Vfs}; use crate::DirstateError; use std::cell::{Cell, Ref, RefCell, RefMut}; use std::collections::HashSet; use std::path::{Path, PathBuf}; /// A repository on disk pub struct Repo { working_directory: PathBuf, dot_hg: PathBuf, store: PathBuf, requirements: HashSet<String>, config: Config, // None means not known/initialized yet dirstate_parents: Cell<Option<DirstateParents>>, dirstate_map: LazyCell<OwningDirstateMap, DirstateError>, } #[derive(Debug, derive_more::From)] pub enum RepoError { NotFound { at: PathBuf, }, #[from] ConfigParseError(ConfigParseError), #[from] Other(HgError), } impl From<ConfigError> for RepoError { fn from(error: ConfigError) -> Self { match error { ConfigError::Parse(error) => error.into(), ConfigError::Other(error) => error.into(), } } } impl Repo { /// tries to find nearest repository root in current working directory or /// its ancestors pub fn find_repo_root() -> Result<PathBuf, RepoError> { let current_directory = crate::utils::current_dir()?; // ancestors() is inclusive: it first yields `current_directory` // as-is. for ancestor in current_directory.ancestors() { if is_dir(ancestor.join(".hg"))? { return Ok(ancestor.to_path_buf()); } } return Err(RepoError::NotFound { at: current_directory, }); } /// Find a repository, either at the given path (which must contain a `.hg` /// sub-directory) or by searching the current directory and its /// ancestors. /// /// A method with two very different "modes" like this usually a code smell /// to make two methods instead, but in this case an `Option` is what rhg /// sub-commands get from Clap for the `-R` / `--repository` CLI argument. /// Having two methods would just move that `if` to almost all callers. pub fn find( config: &Config, explicit_path: Option<PathBuf>, ) -> Result<Self, RepoError> { if let Some(root) = explicit_path { if is_dir(root.join(".hg"))? { Self::new_at_path(root.to_owned(), config) } else if is_file(&root)? { Err(HgError::unsupported("bundle repository").into()) } else { Err(RepoError::NotFound { at: root.to_owned(), }) } } else { let root = Self::find_repo_root()?; Self::new_at_path(root, config) } } /// To be called after checking that `.hg` is a sub-directory fn new_at_path( working_directory: PathBuf, config: &Config, ) -> Result<Self, RepoError> { let dot_hg = working_directory.join(".hg"); let mut repo_config_files = Vec::new(); repo_config_files.push(dot_hg.join("hgrc")); repo_config_files.push(dot_hg.join("hgrc-not-shared")); let hg_vfs = Vfs { base: &dot_hg }; let mut reqs = requirements::load_if_exists(hg_vfs)?; let relative = reqs.contains(requirements::RELATIVE_SHARED_REQUIREMENT); let shared = reqs.contains(requirements::SHARED_REQUIREMENT) || relative; // From `mercurial/localrepo.py`: // // if .hg/requires contains the sharesafe requirement, it means // there exists a `.hg/store/requires` too and we should read it // NOTE: presence of SHARESAFE_REQUIREMENT imply that store requirement // is present. We never write SHARESAFE_REQUIREMENT for a repo if store // is not present, refer checkrequirementscompat() for that // // However, if SHARESAFE_REQUIREMENT is not present, it means that the // repository was shared the old way. We check the share source // .hg/requires for SHARESAFE_REQUIREMENT to detect whether the // current repository needs to be reshared let share_safe = reqs.contains(requirements::SHARESAFE_REQUIREMENT); let store_path; if !shared { store_path = dot_hg.join("store"); } else { let bytes = hg_vfs.read("sharedpath")?; let mut shared_path = get_path_from_bytes(bytes.trim_end_matches(|b| b == b'\n')) .to_owned(); if relative { shared_path = dot_hg.join(shared_path) } if !is_dir(&shared_path)? { return Err(HgError::corrupted(format!( ".hg/sharedpath points to nonexistent directory {}", shared_path.display() )) .into()); } store_path = shared_path.join("store"); let source_is_share_safe = requirements::load(Vfs { base: &shared_path })? .contains(requirements::SHARESAFE_REQUIREMENT); if share_safe && !source_is_share_safe { return Err(match config .get(b"share", b"safe-mismatch.source-not-safe") { Some(b"abort") | None => HgError::abort( "abort: share source does not support share-safe requirement\n\ (see `hg help config.format.use-share-safe` for more information)", exit_codes::ABORT, ), _ => HgError::unsupported("share-safe downgrade"), } .into()); } else if source_is_share_safe && !share_safe { return Err( match config.get(b"share", b"safe-mismatch.source-safe") { Some(b"abort") | None => HgError::abort( "abort: version mismatch: source uses share-safe \ functionality while the current share does not\n\ (see `hg help config.format.use-share-safe` for more information)", exit_codes::ABORT, ), _ => HgError::unsupported("share-safe upgrade"), } .into(), ); } if share_safe { repo_config_files.insert(0, shared_path.join("hgrc")) } } if share_safe { reqs.extend(requirements::load(Vfs { base: &store_path })?); } let repo_config = if std::env::var_os("HGRCSKIPREPO").is_none() { config.combine_with_repo(&repo_config_files)? } else { config.clone() }; let repo = Self { requirements: reqs, working_directory, store: store_path, dot_hg, config: repo_config, dirstate_parents: Cell::new(None), dirstate_map: LazyCell::new(Self::new_dirstate_map), }; requirements::check(&repo)?; Ok(repo) } pub fn working_directory_path(&self) -> &Path { &self.working_directory } pub fn requirements(&self) -> &HashSet<String> { &self.requirements } pub fn config(&self) -> &Config { &self.config } /// For accessing repository files (in `.hg`), except for the store /// (`.hg/store`). pub fn hg_vfs(&self) -> Vfs<'_> { Vfs { base: &self.dot_hg } } /// For accessing repository store files (in `.hg/store`) pub fn store_vfs(&self) -> Vfs<'_> { Vfs { base: &self.store } } /// For accessing the working copy pub fn working_directory_vfs(&self) -> Vfs<'_> { Vfs { base: &self.working_directory, } } pub fn has_dirstate_v2(&self) -> bool { self.requirements .contains(requirements::DIRSTATE_V2_REQUIREMENT) } fn dirstate_file_contents(&self) -> Result<Vec<u8>, HgError> { Ok(self .hg_vfs() .read("dirstate") .io_not_found_as_none()? .unwrap_or(Vec::new())) } pub fn dirstate_parents(&self) -> Result<DirstateParents, HgError> { if let Some(parents) = self.dirstate_parents.get() { return Ok(parents); } let dirstate = self.dirstate_file_contents()?; let parents = if dirstate.is_empty() { DirstateParents::NULL } else if self.has_dirstate_v2() { crate::dirstate_tree::on_disk::read_docket(&dirstate)?.parents() } else { crate::dirstate::parsers::parse_dirstate_parents(&dirstate)? .clone() }; self.dirstate_parents.set(Some(parents)); Ok(parents) } fn new_dirstate_map(&self) -> Result<OwningDirstateMap, DirstateError> { let dirstate_file_contents = self.dirstate_file_contents()?; if dirstate_file_contents.is_empty() { self.dirstate_parents.set(Some(DirstateParents::NULL)); Ok(OwningDirstateMap::new_empty(Vec::new())) } else if self.has_dirstate_v2() { let docket = crate::dirstate_tree::on_disk::read_docket( &dirstate_file_contents, )?; self.dirstate_parents.set(Some(docket.parents())); let data_size = docket.data_size(); let metadata = docket.tree_metadata(); let mut map = if let Some(data_mmap) = self .hg_vfs() .mmap_open(docket.data_filename()) .io_not_found_as_none()? { OwningDirstateMap::new_empty(MmapWrapper(data_mmap)) } else { OwningDirstateMap::new_empty(Vec::new()) }; let (on_disk, placeholder) = map.get_mut_pair(); *placeholder = DirstateMap::new_v2(on_disk, data_size, metadata)?; Ok(map) } else { let mut map = OwningDirstateMap::new_empty(dirstate_file_contents); let (on_disk, placeholder) = map.get_mut_pair(); let (inner, parents) = DirstateMap::new_v1(on_disk)?; self.dirstate_parents .set(Some(parents.unwrap_or(DirstateParents::NULL))); *placeholder = inner; Ok(map) } } pub fn dirstate_map( &self, ) -> Result<Ref<OwningDirstateMap>, DirstateError> { self.dirstate_map.get_or_init(self) } pub fn dirstate_map_mut( &self, ) -> Result<RefMut<OwningDirstateMap>, DirstateError> { self.dirstate_map.get_mut_or_init(self) } } /// Lazily-initialized component of `Repo` with interior mutability /// /// This differs from `OnceCell` in that the value can still be "deinitialized" /// later by setting its inner `Option` to `None`. struct LazyCell<T, E> { value: RefCell<Option<T>>, // `Fn`s that don’t capture environment are zero-size, so this box does // not allocate: init: Box<dyn Fn(&Repo) -> Result<T, E>>, } impl<T, E> LazyCell<T, E> { fn new(init: impl Fn(&Repo) -> Result<T, E> + 'static) -> Self { Self { value: RefCell::new(None), init: Box::new(init), } } fn get_or_init(&self, repo: &Repo) -> Result<Ref<T>, E> { let mut borrowed = self.value.borrow(); if borrowed.is_none() { drop(borrowed); // Only use `borrow_mut` if it is really needed to avoid panic in // case there is another outstanding borrow but mutation is not // needed. *self.value.borrow_mut() = Some((self.init)(repo)?); borrowed = self.value.borrow() } Ok(Ref::map(borrowed, |option| option.as_ref().unwrap())) } pub fn get_mut_or_init(&self, repo: &Repo) -> Result<RefMut<T>, E> { let mut borrowed = self.value.borrow_mut(); if borrowed.is_none() { *borrowed = Some((self.init)(repo)?); } Ok(RefMut::map(borrowed, |option| option.as_mut().unwrap())) } } // TODO: remove this when https://github.com/RazrFalcon/memmap2-rs/pull/22 is on crates.io struct MmapWrapper(memmap2::Mmap); impl std::ops::Deref for MmapWrapper { type Target = [u8]; fn deref(&self) -> &[u8] { self.0.deref() } } unsafe impl stable_deref_trait::StableDeref for MmapWrapper {}