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annotate rust/hg-core/examples/nodemap/index.rs @ 51467:406b413e3cf2 stable

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rust-filepatterns: export glob_to_re function Making this function public should not risk freezing the internal API, and it can be useful for all downstream code that needs to perform glob matching against byte strings, such as RHGitaly where it will be useful to match on branches and tags.
author Georges Racinet <georges.racinet@octobus.net>
date Mon, 11 Mar 2024 13:23:18 +0100
parents 4c5f6e95df84
children bd8081e9fd62
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1 // Copyright 2019-2020 Georges Racinet <georges.racinet@octobus.net>
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2 //
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3 // This software may be used and distributed according to the terms of the
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4 // GNU General Public License version 2 or any later version.
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5
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6 //! Minimal `RevlogIndex`, readable from standard Mercurial file format
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7 use hg::*;
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8 use memmap2::*;
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9 use std::fs::File;
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10 use std::ops::Deref;
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11 use std::path::Path;
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12 use std::slice;
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13
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14 pub struct Index {
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15 data: Box<dyn Deref<Target = [IndexEntry]> + Send>,
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16 }
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17
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18 /// A fixed sized index entry. All numbers are big endian
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19 #[repr(C)]
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20 pub struct IndexEntry {
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21 not_used_yet: [u8; 24],
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22 p1: Revision,
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23 p2: Revision,
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24 node: Node,
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25 unused_node: [u8; 12],
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26 }
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27
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28 pub const INDEX_ENTRY_SIZE: usize = 64;
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29
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30 impl IndexEntry {
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31 fn parents(&self) -> [Revision; 2] {
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32 [self.p1, self.p2]
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33 }
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34 }
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35
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36 impl RevlogIndex for Index {
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37 fn len(&self) -> usize {
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38 self.data.len()
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39 }
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40
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41 fn node(&self, rev: Revision) -> Option<&Node> {
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42 if rev == NULL_REVISION {
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43 return None;
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44 }
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45 Some(&self.data[rev.0 as usize].node)
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46 }
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47 }
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48
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49 impl Graph for &Index {
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50 fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> {
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51 let [p1, p2] = self.data[rev.0 as usize].parents();
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52 let len = (*self).len();
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53 if p1 < NULL_REVISION
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54 || p2 < NULL_REVISION
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55 || p1.0 as usize >= len
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56 || p2.0 as usize >= len
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57 {
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58 return Err(GraphError::ParentOutOfRange(rev));
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59 }
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60 Ok([p1, p2])
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61 }
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62 }
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63
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64 struct IndexMmap(Mmap);
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65
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66 impl Deref for IndexMmap {
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67 type Target = [IndexEntry];
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68
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69 fn deref(&self) -> &[IndexEntry] {
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70 let ptr = self.0.as_ptr() as *const IndexEntry;
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71 // Any misaligned data will be ignored.
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72 debug_assert_eq!(
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73 self.0.len() % std::mem::align_of::<IndexEntry>(),
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74 0,
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75 "Misaligned data in mmap"
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76 );
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77 unsafe { slice::from_raw_parts(ptr, self.0.len() / INDEX_ENTRY_SIZE) }
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78 }
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79 }
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80
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81 impl Index {
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82 pub fn load_mmap(path: impl AsRef<Path>) -> Self {
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83 let file = File::open(path).unwrap();
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84 let msg = "Index file is missing, or missing permission";
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85 let mmap = unsafe { MmapOptions::new().map(&file) }.expect(msg);
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86 Self {
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87 data: Box::new(IndexMmap(mmap)),
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88 }
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89 }
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90 }