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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
use std::{
borrow::Cow,
fmt::{Display, Formatter},
};
use bstr::BStr;
use gix_hashtable::HashMap;
#[derive(Debug, Clone)]
pub struct Outcome<'name> {
pub name: Option<Cow<'name, BStr>>,
pub id: gix_hash::ObjectId,
pub depth: u32,
pub name_by_oid: HashMap<gix_hash::ObjectId, Cow<'name, BStr>>,
pub commits_seen: u32,
}
impl<'a> Outcome<'a> {
pub fn into_format(self, hex_len: usize) -> Format<'a> {
Format {
name: self.name,
id: self.id,
hex_len,
depth: self.depth,
long: false,
dirty_suffix: None,
}
}
}
#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone)]
pub struct Format<'a> {
pub name: Option<Cow<'a, BStr>>,
pub id: gix_hash::ObjectId,
pub hex_len: usize,
pub depth: u32,
pub long: bool,
pub dirty_suffix: Option<String>,
}
impl<'a> Format<'a> {
pub fn is_exact_match(&self) -> bool {
self.depth == 0
}
pub fn long(&mut self, long: bool) -> &mut Self {
self.long = long;
self
}
}
impl<'a> Display for Format<'a> {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
if let Some(name) = self.name.as_deref() {
if !self.long && self.is_exact_match() {
name.fmt(f)?;
} else {
write!(f, "{}-{}-g{}", name, self.depth, self.id.to_hex_with_len(self.hex_len))?;
}
} else {
self.id.to_hex_with_len(self.hex_len).fmt(f)?;
}
if let Some(suffix) = &self.dirty_suffix {
write!(f, "-{suffix}")?;
}
Ok(())
}
}
type Flags = u32;
const MAX_CANDIDATES: usize = std::mem::size_of::<Flags>() * 8;
#[derive(Clone, Debug)]
pub struct Options<'name> {
pub name_by_oid: HashMap<gix_hash::ObjectId, Cow<'name, BStr>>,
pub max_candidates: usize,
pub fallback_to_oid: bool,
pub first_parent: bool,
}
impl<'name> Default for Options<'name> {
fn default() -> Self {
Options {
max_candidates: 10, name_by_oid: Default::default(),
fallback_to_oid: false,
first_parent: false,
}
}
}
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error<E>
where
E: std::error::Error + Send + Sync + 'static,
{
#[error("Commit {} could not be found during graph traversal", .oid.to_hex())]
Find {
#[source]
err: Option<E>,
oid: gix_hash::ObjectId,
},
#[error("A commit could not be decoded during traversal")]
Decode(#[from] gix_object::decode::Error),
}
pub(crate) mod function {
use std::{borrow::Cow, cmp::Ordering, collections::VecDeque, iter::FromIterator};
use bstr::BStr;
use gix_hash::oid;
use gix_hashtable::{hash_map, HashMap};
use gix_object::CommitRefIter;
use super::{Error, Outcome};
use crate::describe::{Flags, Options, MAX_CANDIDATES};
pub fn describe<'name, Find, E>(
commit: &oid,
mut find: Find,
Options {
name_by_oid,
mut max_candidates,
fallback_to_oid,
first_parent,
}: Options<'name>,
) -> Result<Option<Outcome<'name>>, Error<E>>
where
Find: for<'b> FnMut(&oid, &'b mut Vec<u8>) -> Result<Option<CommitRefIter<'b>>, E>,
E: std::error::Error + Send + Sync + 'static,
{
max_candidates = max_candidates.min(MAX_CANDIDATES);
if let Some(name) = name_by_oid.get(commit) {
return Ok(Some(Outcome {
name: name.clone().into(),
id: commit.to_owned(),
depth: 0,
name_by_oid,
commits_seen: 0,
}));
}
if max_candidates == 0 || name_by_oid.is_empty() {
return if fallback_to_oid {
Ok(Some(Outcome {
id: commit.to_owned(),
name: None,
name_by_oid,
depth: 0,
commits_seen: 0,
}))
} else {
Ok(None)
};
}
let mut buf = Vec::new();
let mut parent_buf = Vec::new();
let mut queue = VecDeque::from_iter(Some((commit.to_owned(), u32::MAX)));
let mut candidates = Vec::new();
let mut commits_seen = 0;
let mut gave_up_on_commit = None;
let mut seen = HashMap::<gix_hash::ObjectId, Flags>::default();
seen.insert(commit.to_owned(), 0u32);
while let Some((commit, _commit_time)) = queue.pop_front() {
commits_seen += 1;
if let Some(name) = name_by_oid.get(&commit) {
if candidates.len() < max_candidates {
let identity_bit = 1 << candidates.len();
candidates.push(Candidate {
name: name.clone(),
commits_in_its_future: commits_seen - 1,
identity_bit,
order: candidates.len(),
});
*seen.get_mut(&commit).expect("inserted") |= identity_bit;
} else {
gave_up_on_commit = Some(commit);
break;
}
}
let flags = seen[&commit];
for candidate in candidates
.iter_mut()
.filter(|c| (flags & c.identity_bit) != c.identity_bit)
{
candidate.commits_in_its_future += 1;
}
if queue.is_empty() && !candidates.is_empty() {
let mut shortest_depth = Flags::MAX;
let mut best_candidates_at_same_depth = 0_u32;
for candidate in &candidates {
match candidate.commits_in_its_future.cmp(&shortest_depth) {
Ordering::Less => {
shortest_depth = candidate.commits_in_its_future;
best_candidates_at_same_depth = candidate.identity_bit;
}
Ordering::Equal => {
best_candidates_at_same_depth |= candidate.identity_bit;
}
Ordering::Greater => {}
}
}
if (flags & best_candidates_at_same_depth) == best_candidates_at_same_depth {
break;
}
}
parents_by_date_onto_queue_and_track_names(
&mut find,
&mut buf,
&mut parent_buf,
&mut queue,
&mut seen,
&commit,
flags,
first_parent,
)?;
}
if candidates.is_empty() {
return if fallback_to_oid {
Ok(Some(Outcome {
id: commit.to_owned(),
name: None,
name_by_oid,
depth: 0,
commits_seen,
}))
} else {
Ok(None)
};
}
candidates.sort_by(|a, b| {
a.commits_in_its_future
.cmp(&b.commits_in_its_future)
.then_with(|| a.order.cmp(&b.order))
});
if let Some(commit_id) = gave_up_on_commit {
queue.push_front((commit_id, u32::MAX));
commits_seen -= 1;
}
commits_seen += finish_depth_computation(
queue,
find,
candidates.first_mut().expect("at least one candidate"),
seen,
buf,
parent_buf,
first_parent,
)?;
Ok(candidates.into_iter().next().map(|c| Outcome {
name: c.name.into(),
id: commit.to_owned(),
depth: c.commits_in_its_future,
name_by_oid,
commits_seen,
}))
}
#[allow(clippy::too_many_arguments)]
fn parents_by_date_onto_queue_and_track_names<Find, E>(
find: &mut Find,
buf: &mut Vec<u8>,
parent_buf: &mut Vec<u8>,
queue: &mut VecDeque<(gix_hash::ObjectId, u32)>,
seen: &mut HashMap<gix_hash::ObjectId, Flags>,
commit: &gix_hash::oid,
commit_flags: Flags,
first_parent: bool,
) -> Result<(), Error<E>>
where
Find: for<'b> FnMut(&oid, &'b mut Vec<u8>) -> Result<Option<CommitRefIter<'b>>, E>,
E: std::error::Error + Send + Sync + 'static,
{
let commit_iter = find(commit, buf)
.map_err(|err| Error::Find {
err: Some(err),
oid: commit.to_owned(),
})?
.ok_or_else(|| Error::Find {
err: None,
oid: commit.to_owned(),
})?;
for token in commit_iter {
match token {
Ok(gix_object::commit::ref_iter::Token::Tree { .. }) => continue,
Ok(gix_object::commit::ref_iter::Token::Parent { id: parent_id }) => match seen.entry(parent_id) {
hash_map::Entry::Vacant(entry) => {
let parent = match find(&parent_id, parent_buf).map_err(|err| Error::Find {
err: Some(err),
oid: commit.to_owned(),
})? {
Some(p) => p,
None => continue, };
let parent_commit_date = parent
.committer()
.map(|committer| committer.time.seconds_since_unix_epoch)
.unwrap_or_default();
entry.insert(commit_flags);
match queue.binary_search_by(|c| c.1.cmp(&parent_commit_date).reverse()) {
Ok(_) => queue.push_back((parent_id, parent_commit_date)),
Err(pos) => queue.insert(pos, (parent_id, parent_commit_date)),
};
}
hash_map::Entry::Occupied(mut entry) => {
*entry.get_mut() |= commit_flags;
}
},
Ok(_unused_token) => break,
Err(err) => return Err(err.into()),
}
if first_parent {
break;
}
}
Ok(())
}
#[allow(clippy::too_many_arguments)]
fn finish_depth_computation<'name, Find, E>(
mut queue: VecDeque<(gix_hash::ObjectId, u32)>,
mut find: Find,
best_candidate: &mut Candidate<'name>,
mut seen: HashMap<gix_hash::ObjectId, Flags>,
mut buf: Vec<u8>,
mut parent_buf: Vec<u8>,
first_parent: bool,
) -> Result<u32, Error<E>>
where
Find: for<'b> FnMut(&oid, &'b mut Vec<u8>) -> Result<Option<CommitRefIter<'b>>, E>,
E: std::error::Error + Send + Sync + 'static,
{
let mut commits_seen = 0;
while let Some((commit, _commit_time)) = queue.pop_front() {
commits_seen += 1;
let flags = seen[&commit];
if (flags & best_candidate.identity_bit) == best_candidate.identity_bit {
if queue
.iter()
.all(|(id, _)| (seen[id] & best_candidate.identity_bit) == best_candidate.identity_bit)
{
break;
}
} else {
best_candidate.commits_in_its_future += 1;
}
parents_by_date_onto_queue_and_track_names(
&mut find,
&mut buf,
&mut parent_buf,
&mut queue,
&mut seen,
&commit,
flags,
first_parent,
)?;
}
Ok(commits_seen)
}
#[derive(Debug)]
struct Candidate<'a> {
name: Cow<'a, BStr>,
commits_in_its_future: Flags,
identity_bit: Flags,
order: usize,
}
}