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
use crate::{
pack,
pack::data::EntryRange,
pack::tree::{Item, Tree},
};
use git_features::{
interrupt::is_triggered,
parallel,
parallel::in_parallel_if,
progress::{self, Progress},
};
mod resolve;
/// Returned by [`Tree::traverse()`]
#[derive(thiserror::Error, Debug)]
#[allow(missing_docs)]
pub enum Error {
#[error("{message}")]
ZlibInflate {
source: crate::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("One of the object inspectors failed")]
Inspect(#[from] Box<dyn std::error::Error + Send + Sync>),
#[error("Interrupted")]
Interrupted,
}
/// Additional context passed to the `inspect_object(…)` function of the [`Tree::traverse()`] method.
pub struct Context<'a, S> {
/// The pack entry describing the object
pub entry: &'a pack::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],
/// Custom state known to the function
pub state: &'a mut S,
/// The depth at which this object resides in the delta-tree. It represents the amount of base objects, with 0 indicating
/// an 'undeltified' object, and higher values indicating delta objects with the given amount of bases.
pub level: u16,
}
impl<T> Tree<T>
where
T: Default + 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.
/// * `object_progress` is a progress instance to track progress for each object in the traversal.
/// * `size_progress` is a progress instance to track the overall progress.
/// * `tread_limit` is limits the amount of threads used if `Some` or otherwise defaults to all available logical cores.
/// * `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.
/// * `new_thread_state() -> State` is a function to create state to be used in each thread, invoked once per thread.
/// * `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 succceeds with `Ok(())`
/// or returns a `CustomError`.
/// Note that `node_data` can be modified to allow storing maintaining computation results on a per-object basis.
///
/// 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.
#[allow(clippy::too_many_arguments)]
pub fn traverse<F, P, MBFN, S, E>(
mut self,
should_run_in_parallel: impl FnOnce() -> bool,
resolve: F,
object_progress: P,
size_progress: P,
thread_limit: Option<usize>,
pack_entries_end: u64,
new_thread_state: impl Fn() -> S + Send + Sync,
inspect_object: MBFN,
) -> Result<Vec<Item<T>>, Error>
where
F: for<'r> Fn(EntryRange, &'r mut Vec<u8>) -> Option<()> + Send + Sync,
P: Progress + Send,
MBFN: Fn(&mut T, &mut <P as Progress>::SubProgress, Context<'_, S>) -> Result<(), E> + Send + Sync,
E: std::error::Error + Send + Sync + 'static,
{
self.pack_entries_end = Some(pack_entries_end);
let (chunk_size, thread_limit, _) = parallel::optimize_chunk_size_and_thread_limit(1, None, thread_limit, None);
let object_progress = parking_lot::Mutex::new(object_progress);
// SAFETY: We are owning 'self', and it's the UnsafeCell which we are supposed to use requiring unsafe on every access now.
#[allow(unsafe_code)]
let num_objects = unsafe { (*self.items.get()).len() } as u32;
in_parallel_if(
should_run_in_parallel,
self.iter_root_chunks(chunk_size),
thread_limit,
|thread_index| {
(
Vec::<u8>::with_capacity(4096),
object_progress.lock().add_child(format!("thread {}", thread_index)),
new_thread_state(),
)
},
|root_nodes, state| resolve::deltas(root_nodes, state, &resolve, &inspect_object),
Reducer::new(num_objects, &object_progress, size_progress),
)?;
Ok(self.into_items())
}
}
pub(crate) struct Reducer<'a, P> {
item_count: usize,
progress: &'a parking_lot::Mutex<P>,
start: std::time::Instant,
size_progress: P,
}
impl<'a, P> Reducer<'a, P>
where
P: Progress,
{
pub fn new(num_objects: u32, progress: &'a parking_lot::Mutex<P>, mut size_progress: P) -> Self {
progress
.lock()
.init(Some(num_objects as usize), progress::count("objects"));
size_progress.init(None, progress::bytes());
Reducer {
item_count: 0,
progress,
start: std::time::Instant::now(),
size_progress,
}
}
}
impl<'a, P> parallel::Reduce for Reducer<'a, P>
where
P: Progress,
{
type Input = Result<(usize, u64), Error>;
type FeedProduce = ();
type Output = ();
type Error = Error;
fn feed(&mut self, input: Self::Input) -> Result<(), Self::Error> {
let (num_objects, decompressed_size) = input?;
self.item_count += num_objects;
self.size_progress.inc_by(decompressed_size as usize);
self.progress.lock().set(self.item_count);
if is_triggered() {
return Err(Error::Interrupted);
}
Ok(())
}
fn finalize(mut self) -> Result<Self::Output, Self::Error> {
self.progress.lock().show_throughput(self.start);
self.size_progress.show_throughput(self.start);
Ok(())
}
}