1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192

use std::sync::atomic::{AtomicBool, Ordering};

use git_features::{parallel, progress::Progress};

use super::Error;
use crate::{
    cache::delta::traverse,
    index::{self, traverse::Outcome, util::index_entries_sorted_by_offset_ascending},
};

/// Traversal options for [`traverse_with_index()`][index::File::traverse_with_index()]
#[derive(Default)]
pub struct Options {
    /// If `Some`, only use the given amount of threads. Otherwise, the amount of threads to use will be selected based on
    /// the amount of available logical cores.
    pub thread_limit: Option<usize>,
    /// The kinds of safety checks to perform.
    pub check: crate::index::traverse::SafetyCheck,
}

/// Traversal with index
impl index::File {
    /// Iterate through all _decoded objects_ in the given `pack` and handle them with a `Processor`, using an index to reduce waste
    /// at the cost of memory.
    ///
    /// For more details, see the documentation on the [`traverse()`][index::File::traverse()] method.
    pub fn traverse_with_index<P, Processor, E>(
        &self,
        pack: &crate::data::File,
        new_processor: impl Fn() -> Processor + Send + Clone,
        mut progress: P,
        should_interrupt: &AtomicBool,
        Options { check, thread_limit }: Options,
    ) -> Result<Outcome<P>, Error<E>>
    where
        P: Progress,
        Processor: FnMut(
            git_object::Kind,
            &[u8],
            &index::Entry,
            &mut <<P as Progress>::SubProgress as Progress>::SubProgress,
        ) -> Result<(), E>,
        E: std::error::Error + Send + Sync + 'static,
    {
        let (verify_result, traversal_result) = parallel::join(
            {
                let pack_progress = progress.add_child(format!(
                    "Hash of pack '{}'",
                    pack.path().file_name().expect("pack has filename").to_string_lossy()
                ));
                let index_progress = progress.add_child(format!(
                    "Hash of index '{}'",
                    self.path.file_name().expect("index has filename").to_string_lossy()
                ));
                move || {
                    let res = self.possibly_verify(pack, check, pack_progress, index_progress, should_interrupt);
                    if res.is_err() {
                        should_interrupt.store(true, Ordering::SeqCst);
                    }
                    res
                }
            },
            || -> Result<_, Error<_>> {
                let sorted_entries =
                    index_entries_sorted_by_offset_ascending(self, progress.add_child("collecting sorted index"));
                let tree = crate::cache::delta::Tree::from_offsets_in_pack(
                    pack.path(),
                    sorted_entries.into_iter().map(Entry::from),
                    |e| e.index_entry.pack_offset,
                    |id| self.lookup(id).map(|idx| self.pack_offset_at_index(idx)),
                    progress.add_child("indexing"),
                    should_interrupt,
                    self.object_hash,
                )?;
                let there_are_enough_objects = || self.num_objects > 10_000;
                let mut outcome = digest_statistics(tree.traverse(
                    there_are_enough_objects,
                    |slice, out| pack.entry_slice(slice).map(|entry| out.copy_from_slice(entry)),
                    pack.pack_end() as u64,
                    new_processor,
                    |data,
                     progress,
                     traverse::Context {
                         entry: pack_entry,
                         entry_end,
                         decompressed: bytes,
                         state: ref mut processor,
                         level,
                     }| {
                        let object_kind = pack_entry.header.as_kind().expect("non-delta object");
                        data.level = level;
                        data.decompressed_size = pack_entry.decompressed_size;
                        data.object_kind = object_kind;
                        data.compressed_size = entry_end - pack_entry.data_offset;
                        data.object_size = bytes.len() as u64;
                        let result = crate::index::traverse::process_entry(
                            check,
                            object_kind,
                            bytes,
                            progress,
                            &data.index_entry,
                            || {
                                // TODO: Fix this - we overwrite the header of 'data' which also changes the computed entry size,
                                // causing index and pack to seemingly mismatch. This is surprising, and should be done differently.
                                // debug_assert_eq!(&data.index_entry.pack_offset, &pack_entry.pack_offset());
                                git_features::hash::crc32(
                                    pack.entry_slice(data.index_entry.pack_offset..entry_end)
                                        .expect("slice pointing into the pack (by now data is verified)"),
                                )
                            },
                            processor,
                        );
                        match result {
                            Err(err @ Error::PackDecode { .. }) if !check.fatal_decode_error() => {
                                progress.info(format!("Ignoring decode error: {}", err));
                                Ok(())
                            }
                            res => res,
                        }
                    },
                    crate::cache::delta::traverse::Options {
                        object_progress: progress.add_child("Resolving"),
                        size_progress: progress.add_child("Decoding"),
                        thread_limit,
                        should_interrupt,
                        object_hash: self.object_hash,
                    },
                )?);
                outcome.pack_size = pack.data_len() as u64;
                Ok(outcome)
            },
        );
        Ok(Outcome {
            actual_index_checksum: verify_result?,
            statistics: traversal_result?,
            progress,
        })
    }
}

struct Entry {
    index_entry: crate::index::Entry,
    object_kind: git_object::Kind,
    object_size: u64,
    decompressed_size: u64,
    compressed_size: u64,
    level: u16,
}

impl From<crate::index::Entry> for Entry {
    fn from(index_entry: crate::index::Entry) -> Self {
        Entry {
            index_entry,
            level: 0,
            object_kind: git_object::Kind::Tree,
            object_size: 0,
            decompressed_size: 0,
            compressed_size: 0,
        }
    }
}

fn digest_statistics(traverse::Outcome { roots, children }: traverse::Outcome<Entry>) -> index::traverse::Statistics {
    let mut res = index::traverse::Statistics::default();
    let average = &mut res.average;
    for item in roots.iter().chain(children.iter()) {
        res.total_compressed_entries_size += item.data.compressed_size;
        res.total_decompressed_entries_size += item.data.decompressed_size;
        res.total_object_size += item.data.object_size;
        *res.objects_per_chain_length.entry(item.data.level as u32).or_insert(0) += 1;

        average.decompressed_size += item.data.decompressed_size;
        average.compressed_size += item.data.compressed_size as usize;
        average.object_size += item.data.object_size;
        average.num_deltas += item.data.level as u32;
        use git_object::Kind::*;
        match item.data.object_kind {
            Blob => res.num_blobs += 1,
            Tree => res.num_trees += 1,
            Tag => res.num_tags += 1,
            Commit => res.num_commits += 1,
        };
    }

    let num_nodes = roots.len() + children.len();
    average.decompressed_size /= num_nodes as u64;
    average.compressed_size /= num_nodes;
    average.object_size /= num_nodes as u64;
    average.num_deltas /= num_nodes as u32;

    res
}