rust/hg-core/src/repo.rs
author Simon Sapin <simon.sapin@octobus.net>
Mon, 14 Dec 2020 16:33:15 +0100
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child 46442 02d3bb972121
permissions -rw-r--r--
rust: introduce Repo and Vfs types for filesystem abstraction This is similar to the corresponding Python classes. Repo represents a repository and knows the path to the `.hg` directory, the `store` directory, and the working directory. Separating these will enable supporting the share extension. A Vfs is created from a Repo for one of these three directories. It has filesystem access APIs that take a relative std::path::Path as a parameter. Differential Revision: https://phab.mercurial-scm.org/D9596
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use crate::operations::{find_root, FindRootError};
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use crate::requirements;
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use memmap::{Mmap, MmapOptions};
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use std::path::{Path, PathBuf};
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/// A repository on disk
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pub struct Repo {
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    working_directory: PathBuf,
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    dot_hg: PathBuf,
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    store: PathBuf,
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}
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/// Filesystem access abstraction for the contents of a given "base" diretory
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#[derive(Clone, Copy)]
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pub(crate) struct Vfs<'a> {
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    base: &'a Path,
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}
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impl Repo {
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    /// Returns `None` if the given path doesn’t look like a repository
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    /// (doesn’t contain a `.hg` sub-directory).
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    pub fn for_path(root: impl Into<PathBuf>) -> Self {
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        let working_directory = root.into();
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        let dot_hg = working_directory.join(".hg");
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        Self {
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            store: dot_hg.join("store"),
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            dot_hg,
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            working_directory,
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        }
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    }
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    pub fn find() -> Result<Self, FindRootError> {
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        find_root().map(Self::for_path)
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    }
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    pub fn check_requirements(
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        &self,
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    ) -> Result<(), requirements::RequirementsError> {
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        requirements::check(self)
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    }
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    pub fn working_directory_path(&self) -> &Path {
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        &self.working_directory
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    }
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    /// For accessing repository files (in `.hg`), except for the store
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    /// (`.hg/store`).
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    pub(crate) fn hg_vfs(&self) -> Vfs<'_> {
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        Vfs { base: &self.dot_hg }
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    }
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    /// For accessing repository store files (in `.hg/store`)
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    pub(crate) fn store_vfs(&self) -> Vfs<'_> {
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        Vfs { base: &self.store }
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    }
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    /// For accessing the working copy
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    // The undescore prefix silences the "never used" warning. Remove before
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    // using.
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    pub(crate) fn _working_directory_vfs(&self) -> Vfs<'_> {
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        Vfs {
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            base: &self.working_directory,
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        }
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    }
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}
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impl Vfs<'_> {
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    pub(crate) fn read(
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        &self,
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        relative_path: impl AsRef<Path>,
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    ) -> std::io::Result<Vec<u8>> {
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        std::fs::read(self.base.join(relative_path))
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    }
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    pub(crate) fn open(
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        &self,
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        relative_path: impl AsRef<Path>,
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    ) -> std::io::Result<std::fs::File> {
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        std::fs::File::open(self.base.join(relative_path))
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    }
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    pub(crate) fn mmap_open(
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        &self,
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        relative_path: impl AsRef<Path>,
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    ) -> std::io::Result<Mmap> {
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        let file = self.open(relative_path)?;
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        // TODO: what are the safety requirements here?
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        let mmap = unsafe { MmapOptions::new().map(&file) }?;
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        Ok(mmap)
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    }
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}