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annotate rust/hg-core/src/vfs.rs @ 48069:3d0a9c6e614d

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dirstate: Remove the Rust abstraction DirstateMapMethods This Rust trait used to exist in order to allow the DirstateMap class exposed to Python to be backed by either of two implementations: one similar to the Python implementation based on a "flat" `HashMap<HgPathBuf, DirstateEntry>`, and the newer one based on a tree of nodes matching the directory structure of tracked files. A boxed trait object was used with dynamic dispatch. With the flat implementation removed and only the tree one remaining, this abstraction is not useful anymore and the concrete type can be stored directly. It remains that the trait was implemented separately for `DirstateMap<'_>` (which takes a lifetime parameter) and `OwningDirstateMap` (whose job is to wrap the former and hide the lifetime parameter), with the latter impl only forwarding calls. This changeset also removes this forwarding. Instead, the methods formerly of the `DirstateMapMethods` trait are now inherent methods implemented for `OwningDirstateMap` (where they will actually be used) but in the module that defines `DirstateMap`. This unusual setup gives access to the private fields of `DirstateMap` from those methods. Differential Revision: https://phab.mercurial-scm.org/D11517
author Simon Sapin <simon.sapin@octobus.net>
date Mon, 27 Sep 2021 13:52:49 +0200
parents e834b79def74
children 9d0e5629cfbf
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1 use crate::errors::{HgError, IoErrorContext, IoResultExt};
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2 use memmap2::{Mmap, MmapOptions};
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3 use std::io::ErrorKind;
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4 use std::path::{Path, PathBuf};
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5
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6 /// Filesystem access abstraction for the contents of a given "base" diretory
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7 #[derive(Clone, Copy)]
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8 pub struct Vfs<'a> {
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9 pub(crate) base: &'a Path,
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10 }
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11
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12 impl Vfs<'_> {
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13 pub fn join(&self, relative_path: impl AsRef<Path>) -> PathBuf {
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14 self.base.join(relative_path)
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15 }
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16
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17 pub fn read(
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18 &self,
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19 relative_path: impl AsRef<Path>,
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20 ) -> Result<Vec<u8>, HgError> {
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21 let path = self.join(relative_path);
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22 std::fs::read(&path).when_reading_file(&path)
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23 }
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24
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25 pub fn mmap_open(
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26 &self,
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27 relative_path: impl AsRef<Path>,
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28 ) -> Result<Mmap, HgError> {
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29 let path = self.base.join(relative_path);
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30 let file = std::fs::File::open(&path).when_reading_file(&path)?;
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31 // TODO: what are the safety requirements here?
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32 let mmap = unsafe { MmapOptions::new().map(&file) }
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33 .when_reading_file(&path)?;
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34 Ok(mmap)
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35 }
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36
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37 pub fn rename(
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38 &self,
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39 relative_from: impl AsRef<Path>,
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40 relative_to: impl AsRef<Path>,
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41 ) -> Result<(), HgError> {
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42 let from = self.join(relative_from);
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43 let to = self.join(relative_to);
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44 std::fs::rename(&from, &to)
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45 .with_context(|| IoErrorContext::RenamingFile { from, to })
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46 }
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47 }
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48
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49 fn fs_metadata(
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50 path: impl AsRef<Path>,
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51 ) -> Result<Option<std::fs::Metadata>, HgError> {
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52 let path = path.as_ref();
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53 match std::fs::metadata(path) {
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54 Ok(meta) => Ok(Some(meta)),
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55 Err(error) => match error.kind() {
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56 // TODO: when we require a Rust version where `NotADirectory` is
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57 // stable, invert this logic and return None for it and `NotFound`
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58 // and propagate any other error.
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59 ErrorKind::PermissionDenied => Err(error).with_context(|| {
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60 IoErrorContext::ReadingMetadata(path.to_owned())
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61 }),
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62 _ => Ok(None),
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63 },
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64 }
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65 }
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66
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67 pub(crate) fn is_dir(path: impl AsRef<Path>) -> Result<bool, HgError> {
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68 Ok(fs_metadata(path)?.map_or(false, |meta| meta.is_dir()))
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69 }
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70
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71 pub(crate) fn is_file(path: impl AsRef<Path>) -> Result<bool, HgError> {
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72 Ok(fs_metadata(path)?.map_or(false, |meta| meta.is_file()))
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73 }