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 gix_features::{
parallel::in_parallel_with_slice,
progress::{self, DynNestedProgress, Progress},
threading,
threading::{Mutable, OwnShared},
};
use crate::{
cache::delta::{traverse::util::ItemSliceSync, Item, Tree},
data::EntryRange,
};
mod resolve;
pub(crate) mod util;
/// Returned by [`Tree::traverse()`]
#[derive(thiserror::Error, Debug)]
#[allow(missing_docs)]
pub enum Error {
#[error("{message}")]
ZlibInflate {
source: gix_features::zlib::inflate::Error,
message: &'static str,
},
#[error("The resolver failed to obtain the pack entry bytes for the entry at {pack_offset}")]
ResolveFailed { pack_offset: u64 },
#[error(transparent)]
EntryType(#[from] crate::data::entry::decode::Error),
#[error("One of the object inspectors failed")]
Inspect(#[from] Box<dyn std::error::Error + Send + Sync>),
#[error("Interrupted")]
Interrupted,
#[error(
"The base at {base_pack_offset} was referred to by a ref-delta, but it was never added to the tree as if the pack was still thin."
)]
OutOfPackRefDelta {
/// The base's offset which was from a resolved ref-delta that didn't actually get added to the tree
base_pack_offset: crate::data::Offset,
},
#[error("Failed to spawn thread when switching to work-stealing mode")]
SpawnThread(#[from] std::io::Error),
#[error(transparent)]
Delta(#[from] crate::data::delta::apply::Error),
}
/// Additional context passed to the `inspect_object(…)` function of the [`Tree::traverse()`] method.
pub struct Context<'a> {
/// The pack entry describing the object
pub entry: &'a crate::data::Entry,
/// The offset at which `entry` ends in the pack, useful to learn about the exact range of `entry` within the pack.
pub entry_end: u64,
/// The decompressed object itself, ready to be decoded.
pub decompressed: &'a [u8],
/// The depth at which this object resides in the delta-tree. It represents the number of base objects, with 0 indicating
/// an 'undeltified' object, and higher values indicating delta objects with the given number of bases.
pub level: u16,
}
/// Options for [`Tree::traverse()`].
pub struct Options<'a, 's> {
/// is a progress instance to track progress for each object in the traversal.
pub object_progress: Box<dyn DynNestedProgress>,
/// is a progress instance to track the overall progress.
pub size_progress: &'s mut dyn Progress,
/// If `Some`, only use the given number of threads. Otherwise, the number of threads to use will be selected based on
/// the number of available logical cores.
pub thread_limit: Option<usize>,
/// Abort the operation if the value is `true`.
pub should_interrupt: &'a AtomicBool,
/// specifies what kind of hashes we expect to be stored in oid-delta entries, which is viable to decoding them
/// with the correct size.
pub object_hash: gix_hash::Kind,
}
/// The outcome of [`Tree::traverse()`]
pub struct Outcome<T> {
/// The items that have no children in the pack, i.e. base objects.
pub roots: Vec<Item<T>>,
/// The items that children to a root object, i.e. delta objects.
pub children: Vec<Item<T>>,
}
impl<T> Tree<T>
where
T: Send,
{
/// Traverse this tree of delta objects with a function `inspect_object` to process each object at will.
///
/// * `should_run_in_parallel() -> bool` returns true if the underlying pack is big enough to warrant parallel traversal at all.
/// * `resolve(EntrySlice, &mut Vec<u8>) -> Option<()>` resolves the bytes in the pack for the given `EntrySlice` and stores them in the
/// output vector. It returns `Some(())` if the object existed in the pack, or `None` to indicate a resolution error, which would abort the
/// operation as well.
/// * `pack_entries_end` marks one-past-the-last byte of the last entry in the pack, as the last entries size would otherwise
/// be unknown as it's not part of the index file.
/// * `inspect_object(node_data: &mut T, progress: Progress, context: Context<ThreadLocal State>) -> Result<(), CustomError>` is a function
/// running for each thread receiving fully decoded objects along with contextual information, which either succeeds with `Ok(())`
/// or returns a `CustomError`.
/// Note that `node_data` can be modified to allow storing maintaining computation results on a per-object basis. It should contain
/// its own mutable per-thread data as required.
///
/// This method returns a vector of all tree items, along with their potentially modified custom node data.
///
/// _Note_ that this method consumed the Tree to assure safe parallel traversal with mutation support.
pub fn traverse<F, MBFN, E, R>(
mut self,
resolve: F,
resolve_data: &R,
pack_entries_end: u64,
inspect_object: MBFN,
Options {
thread_limit,
mut object_progress,
size_progress,
should_interrupt,
object_hash,
}: Options<'_, '_>,
) -> Result<Outcome<T>, Error>
where
F: for<'r> Fn(EntryRange, &'r R) -> Option<&'r [u8]> + Send + Clone,
R: Send + Sync,
MBFN: FnMut(&mut T, &dyn Progress, Context<'_>) -> Result<(), E> + Send + Clone,
E: std::error::Error + Send + Sync + 'static,
{
self.set_pack_entries_end_and_resolve_ref_offsets(pack_entries_end)?;
let num_objects = self.num_items();
let object_counter = {
let progress = &mut object_progress;
progress.init(Some(num_objects), progress::count("objects"));
progress.counter()
};
size_progress.init(None, progress::bytes());
let size_counter = size_progress.counter();
let object_progress = OwnShared::new(Mutable::new(object_progress));
let start = std::time::Instant::now();
let (mut root_items, mut child_items_vec) = self.take_root_and_child();
let child_items = ItemSliceSync::new(&mut child_items_vec);
let child_items = &child_items;
in_parallel_with_slice(
&mut root_items,
thread_limit,
{
{
let object_progress = object_progress.clone();
move |thread_index| resolve::State {
delta_bytes: Vec::<u8>::with_capacity(4096),
fully_resolved_delta_bytes: Vec::<u8>::with_capacity(4096),
progress: Box::new(
threading::lock(&object_progress).add_child(format!("thread {thread_index}")),
),
resolve: resolve.clone(),
modify_base: inspect_object.clone(),
child_items,
}
}
},
{
move |node, state, threads_left, should_interrupt| {
// SAFETY: This invariant is upheld since `child_items` and `node` come from the same Tree.
// This means we can rely on Tree's invariant that node.children will be the only `children` array in
// for nodes in this tree that will contain any of those children.
#[allow(unsafe_code)]
unsafe {
resolve::deltas(
object_counter.clone(),
size_counter.clone(),
node,
state,
resolve_data,
object_hash.len_in_bytes(),
threads_left,
should_interrupt,
)
}
}
},
|| (!should_interrupt.load(Ordering::Relaxed)).then(|| std::time::Duration::from_millis(50)),
|_| (),
)?;
threading::lock(&object_progress).show_throughput(start);
size_progress.show_throughput(start);
Ok(Outcome {
roots: root_items,
children: child_items_vec,
})
}
}