cff28ca94c · matheusbsbs/matheus-bagliano

@@ -37,10 +37,30 @@ static enum mmap_strategy mmap_strategy = MMAP_OK;

37

38 struct packed_ref_store;

39

40 -struct packed_ref_cache {

40 +/*

41 + * A `snapshot` represents one snapshot of a `packed-refs` file.

42 + *

43 + * Normally, this will be a mmapped view of the contents of the

44 + * `packed-refs` file at the time the snapshot was created. However,

45 + * if the `packed-refs` file was not sorted, this might point at heap

46 + * memory holding the contents of the `packed-refs` file with its

47 + * records sorted by refname.

48 + *

49 + * `snapshot` instances are reference counted (via

50 + * `acquire_snapshot()` and `release_snapshot()`). This is to prevent

51 + * an instance from disappearing while an iterator is still iterating

52 + * over it. Instances are garbage collected when their `referrers`

53 + * count goes to zero.

54 + *

55 + * The most recent `snapshot`, if available, is referenced by the

56 + * `packed_ref_store`. Its freshness is checked whenever

57 + * `get_snapshot()` is called; if the existing snapshot is obsolete, a

58 + * new snapshot is taken.

59 + */

60 +struct snapshot {

61 /*

62 * A back-pointer to the packed_ref_store with which this

43 - * cache is associated:

63 + * snapshot is associated:

64 */

65 struct packed_ref_store *refs;

66

@@ -61,26 +81,42 @@ struct packed_ref_cache {

81 size_t header_len;

82

83 /*

64 - * What is the peeled state of this cache? (This is usually

65 - * determined from the header of the "packed-refs" file.)

84 + * What is the peeled state of the `packed-refs` file that

85 + * this snapshot represents? (This is usually determined from

86 + * the file's header.)

87 */

88 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled;

89

90 /*

70 - * Count of references to the data structure in this instance,

71 - * including the pointer from files_ref_store::packed if any.

72 - * The data will not be freed as long as the reference count

73 - * is nonzero.

91 + * Count of references to this instance, including the pointer

92 + * from `packed_ref_store::snapshot`, if any. The instance

93 + * will not be freed as long as the reference count is

94 + * nonzero.

95 */

96 unsigned int referrers;

97

77 - /* The metadata from when this packed-refs cache was read */

98 + /*

99 + * The metadata of the `packed-refs` file from which this

100 + * snapshot was created, used to tell if the file has been

101 + * replaced since we read it.

102 + */

103 struct stat_validity validity;

104 };

105

106 /*

82 - * A container for `packed-refs`-related data. It is not (yet) a

83 - * `ref_store`.

107 + * A `ref_store` representing references stored in a `packed-refs`

108 + * file. It implements the `ref_store` interface, though it has some

109 + * limitations:

110 + *

111 + * - It cannot store symbolic references.

112 + *

113 + * - It cannot store reflogs.

114 + *

115 + * - It does not support reference renaming (though it could).

116 + *

117 + * On the other hand, it can be locked outside of a reference

118 + * transaction. In that case, it remains locked even after the

119 + * transaction is done and the new `packed-refs` file is activated.

120 */

121 struct packed_ref_store {

122 struct ref_store base;

@@ -91,10 +127,10 @@ struct packed_ref_store {

127 char *path;

128

129 /*

94 - * A cache of the values read from the `packed-refs` file, if

95 - * it might still be current; otherwise, NULL.

130 + * A snapshot of the values read from the `packed-refs` file,

131 + * if it might still be current; otherwise, NULL.

132 */

97 - struct packed_ref_cache *cache;

133 + struct snapshot *snapshot;

134

135 /*

136 * Lock used for the "packed-refs" file. Note that this (and

@@ -111,43 +147,42 @@ struct packed_ref_store {

147 };

148

149 /*

114 - * Increment the reference count of *packed_refs.

150 + * Increment the reference count of `*snapshot`.

151 */

116 -static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)

152 +static void acquire_snapshot(struct snapshot *snapshot)

153 {

118 - packed_refs->referrers++;

154 + snapshot->referrers++;

155 }

156

157 /*

122 - * If the buffer in `packed_refs` is active, then either munmap the

158 + * If the buffer in `snapshot` is active, then either munmap the

159 * memory and close the file, or free the memory. Then set the buffer

160 * pointers to NULL.

161 */

126 -static void release_packed_ref_buffer(struct packed_ref_cache *packed_refs)

162 +static void clear_snapshot_buffer(struct snapshot *snapshot)

163 {

128 - if (packed_refs->mmapped) {

129 - if (munmap(packed_refs->buf,

130 - packed_refs->eof - packed_refs->buf))

164 + if (snapshot->mmapped) {

165 + if (munmap(snapshot->buf, snapshot->eof - snapshot->buf))

166 die_errno("error ummapping packed-refs file %s",

132 - packed_refs->refs->path);

133 - packed_refs->mmapped = 0;

167 + snapshot->refs->path);

168 + snapshot->mmapped = 0;

169 } else {

135 - free(packed_refs->buf);

170 + free(snapshot->buf);

171 }

137 - packed_refs->buf = packed_refs->eof = NULL;

138 - packed_refs->header_len = 0;

172 + snapshot->buf = snapshot->eof = NULL;

173 + snapshot->header_len = 0;

174 }

175

176 /*

142 - * Decrease the reference count of *packed_refs. If it goes to zero,

143 - * free *packed_refs and return true; otherwise return false.

177 + * Decrease the reference count of `*snapshot`. If it goes to zero,

178 + * free `*snapshot` and return true; otherwise return false.

179 */

145 -static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)

180 +static int release_snapshot(struct snapshot *snapshot)

181 {

147 - if (!--packed_refs->referrers) {

148 - stat_validity_clear(&packed_refs->validity);

149 - release_packed_ref_buffer(packed_refs);

150 - free(packed_refs);

182 + if (!--snapshot->referrers) {

183 + stat_validity_clear(&snapshot->validity);

184 + clear_snapshot_buffer(snapshot);

185 + free(snapshot);

186 return 1;

187 } else {

188 return 0;

@@ -192,13 +227,13 @@ static struct packed_ref_store *packed_downcast(struct ref_store *ref_store,

227 return refs;

228 }

229

195 -static void clear_packed_ref_cache(struct packed_ref_store *refs)

230 +static void clear_snapshot(struct packed_ref_store *refs)

231 {

197 - if (refs->cache) {

198 - struct packed_ref_cache *cache = refs->cache;

232 + if (refs->snapshot) {

233 + struct snapshot *snapshot = refs->snapshot;

234

200 - refs->cache = NULL;

201 - release_packed_ref_cache(cache);

235 + refs->snapshot = NULL;

236 + release_snapshot(snapshot);

237 }

238 }

239

@@ -225,14 +260,14 @@ static NORETURN void die_invalid_line(const char *path,

260

261 }

262

228 -struct packed_ref_entry {

263 +struct snapshot_record {

264 const char *start;

265 size_t len;

266 };

267

233 -static int cmp_packed_ref_entries(const void *v1, const void *v2)

268 +static int cmp_packed_ref_records(const void *v1, const void *v2)

269 {

235 - const struct packed_ref_entry *e1 = v1, *e2 = v2;

270 + const struct snapshot_record *e1 = v1, *e2 = v2;

271 const char *r1 = e1->start + GIT_SHA1_HEXSZ + 1;

272 const char *r2 = e2->start + GIT_SHA1_HEXSZ + 1;

273

@@ -251,10 +286,10 @@ static int cmp_packed_ref_entries(const void *v1, const void *v2)

286 }

287

288 /*

254 - * Compare a packed-refs record pointed to by `rec` to the specified

255 - * NUL-terminated refname.

289 + * Compare a snapshot record at `rec` to the specified NUL-terminated

290 + * refname.

291 */

257 -static int cmp_entry_to_refname(const char *rec, const char *refname)

292 +static int cmp_record_to_refname(const char *rec, const char *refname)

293 {

294 const char *r1 = rec + GIT_SHA1_HEXSZ + 1;

295 const char *r2 = refname;

@@ -272,31 +307,30 @@ static int cmp_entry_to_refname(const char *rec, const char *refname)

307 }

308

309 /*

275 - * `packed_refs->buf` is not known to be sorted. Check whether it is,

276 - * and if not, sort it into new memory and munmap/free the old

277 - * storage.

310 + * `snapshot->buf` is not known to be sorted. Check whether it is, and

311 + * if not, sort it into new memory and munmap/free the old storage.

312 */

279 -static void sort_packed_refs(struct packed_ref_cache *packed_refs)

313 +static void sort_snapshot(struct snapshot *snapshot)

314 {

281 - struct packed_ref_entry *entries = NULL;

315 + struct snapshot_record *records = NULL;

316 size_t alloc = 0, nr = 0;

317 int sorted = 1;

318 const char *pos, *eof, *eol;

319 size_t len, i;

320 char *new_buffer, *dst;

321

288 - pos = packed_refs->buf + packed_refs->header_len;

289 - eof = packed_refs->eof;

322 + pos = snapshot->buf + snapshot->header_len;

323 + eof = snapshot->eof;

324 len = eof - pos;

325

326 if (!len)

327 return;

328

329 /*

296 - * Initialize entries based on a crude estimate of the number

330 + * Initialize records based on a crude estimate of the number

331 * of references in the file (we'll grow it below if needed):

332 */

299 - ALLOC_GROW(entries, len / 80 + 20, alloc);

333 + ALLOC_GROW(records, len / 80 + 20, alloc);

334

335 while (pos < eof) {

336 eol = memchr(pos, '\n', eof - pos);

@@ -304,7 +338,7 @@ static void sort_packed_refs(struct packed_ref_cache *packed_refs)

338 /* The safety check should prevent this. */

339 BUG("unterminated line found in packed-refs");

340 if (eol - pos < GIT_SHA1_HEXSZ + 2)

307 - die_invalid_line(packed_refs->refs->path,

341 + die_invalid_line(snapshot->refs->path,

342 pos, eof - pos);

343 eol++;

344 if (eol < eof && *eol == '^') {

@@ -321,15 +355,15 @@ static void sort_packed_refs(struct packed_ref_cache *packed_refs)

355 eol++;

356 }

357

324 - ALLOC_GROW(entries, nr + 1, alloc);

325 - entries[nr].start = pos;

326 - entries[nr].len = eol - pos;

358 + ALLOC_GROW(records, nr + 1, alloc);

359 + records[nr].start = pos;

360 + records[nr].len = eol - pos;

361 nr++;

362

363 if (sorted &&

364 nr > 1 &&

331 - cmp_packed_ref_entries(&entries[nr - 2],

332 - &entries[nr - 1]) >= 0)

365 + cmp_packed_ref_records(&records[nr - 2],

366 + &records[nr - 1]) >= 0)

367 sorted = 0;

368

369 pos = eol;

@@ -338,31 +372,31 @@ static void sort_packed_refs(struct packed_ref_cache *packed_refs)

372 if (sorted)

373 goto cleanup;

374

341 - /* We need to sort the memory. First we sort the entries array: */

342 - QSORT(entries, nr, cmp_packed_ref_entries);

375 + /* We need to sort the memory. First we sort the records array: */

376 + QSORT(records, nr, cmp_packed_ref_records);

377

378 /*

379 * Allocate a new chunk of memory, and copy the old memory to

346 - * the new in the order indicated by `entries` (not bothering

380 + * the new in the order indicated by `records` (not bothering

381 * with the header line):

382 */

383 new_buffer = xmalloc(len);

384 for (dst = new_buffer, i = 0; i < nr; i++) {

351 - memcpy(dst, entries[i].start, entries[i].len);

352 - dst += entries[i].len;

385 + memcpy(dst, records[i].start, records[i].len);

386 + dst += records[i].len;

387 }

388

389 /*

390 * Now munmap the old buffer and use the sorted buffer in its

391 * place:

392 */

359 - release_packed_ref_buffer(packed_refs);

360 - packed_refs->buf = new_buffer;

361 - packed_refs->eof = new_buffer + len;

362 - packed_refs->header_len = 0;

393 + clear_snapshot_buffer(snapshot);

394 + snapshot->buf = new_buffer;

395 + snapshot->eof = new_buffer + len;

396 + snapshot->header_len = 0;

397

398 cleanup:

365 - free(entries);

399 + free(records);

400 }

401

402 /*

@@ -406,10 +440,10 @@ static const char *find_end_of_record(const char *p, const char *end)

440 * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of

441 * these checks fails.

442 */

409 -static void verify_buffer_safe(struct packed_ref_cache *packed_refs)

443 +static void verify_buffer_safe(struct snapshot *snapshot)

444 {

411 - const char *buf = packed_refs->buf + packed_refs->header_len;

412 - const char *eof = packed_refs->eof;

445 + const char *buf = snapshot->buf + snapshot->header_len;

446 + const char *eof = snapshot->eof;

447 const char *last_line;

448

449 if (buf == eof)

@@ -417,24 +451,23 @@ static void verify_buffer_safe(struct packed_ref_cache *packed_refs)

451

452 last_line = find_start_of_record(buf, eof - 1);

453 if (*(eof - 1) != '\n' || eof - last_line < GIT_SHA1_HEXSZ + 2)

420 - die_invalid_line(packed_refs->refs->path,

454 + die_invalid_line(snapshot->refs->path,

455 last_line, eof - last_line);

456 }

457

458 /*

459 * Depending on `mmap_strategy`, either mmap or read the contents of

426 - * the `packed-refs` file into the `packed_refs` instance. Return 1 if

427 - * the file existed and was read, or 0 if the file was absent. Die on

428 - * errors.

460 + * the `packed-refs` file into the snapshot. Return 1 if the file

461 + * existed and was read, or 0 if the file was absent. Die on errors.

462 */

430 -static int load_contents(struct packed_ref_cache *packed_refs)

463 +static int load_contents(struct snapshot *snapshot)

464 {

465 int fd;

466 struct stat st;

467 size_t size;

468 ssize_t bytes_read;

469

437 - fd = open(packed_refs->refs->path, O_RDONLY);

470 + fd = open(snapshot->refs->path, O_RDONLY);

471 if (fd < 0) {

472 if (errno == ENOENT) {

473 /*

@@ -446,30 +479,30 @@ static int load_contents(struct packed_ref_cache *packed_refs)

479 */

480 return 0;

481 } else {

449 - die_errno("couldn't read %s", packed_refs->refs->path);

482 + die_errno("couldn't read %s", snapshot->refs->path);

483 }

484 }

485

453 - stat_validity_update(&packed_refs->validity, fd);

486 + stat_validity_update(&snapshot->validity, fd);

487

488 if (fstat(fd, &st) < 0)

456 - die_errno("couldn't stat %s", packed_refs->refs->path);

489 + die_errno("couldn't stat %s", snapshot->refs->path);

490 size = xsize_t(st.st_size);

491

492 switch (mmap_strategy) {

493 case MMAP_NONE:

461 - packed_refs->buf = xmalloc(size);

462 - bytes_read = read_in_full(fd, packed_refs->buf, size);

494 + snapshot->buf = xmalloc(size);

495 + bytes_read = read_in_full(fd, snapshot->buf, size);

496 if (bytes_read < 0 || bytes_read != size)

464 - die_errno("couldn't read %s", packed_refs->refs->path);

465 - packed_refs->eof = packed_refs->buf + size;

466 - packed_refs->mmapped = 0;

497 + die_errno("couldn't read %s", snapshot->refs->path);

498 + snapshot->eof = snapshot->buf + size;

499 + snapshot->mmapped = 0;

500 break;

501 case MMAP_TEMPORARY:

502 case MMAP_OK:

470 - packed_refs->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);

471 - packed_refs->eof = packed_refs->buf + size;

472 - packed_refs->mmapped = 1;

503 + snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);

504 + snapshot->eof = snapshot->buf + size;

505 + snapshot->mmapped = 1;

506 break;

507 }

508 close(fd);

@@ -478,7 +511,7 @@ static int load_contents(struct packed_ref_cache *packed_refs)

511 }

512

513 /*

481 - * Find the place in `cache->buf` where the start of the record for

514 + * Find the place in `snapshot->buf` where the start of the record for

515 * `refname` starts. If `mustexist` is true and the reference doesn't

516 * exist, then return NULL. If `mustexist` is false and the reference

517 * doesn't exist, then return the point where that reference would be

@@ -486,10 +519,10 @@ static int load_contents(struct packed_ref_cache *packed_refs)

519 * reference name; for example, one could search for "refs/replace/"

520 * to find the start of any replace references.

521 *

489 - * The record is sought using a binary search, so `cache->buf` must be

490 - * sorted.

522 + * The record is sought using a binary search, so `snapshot->buf` must

523 + * be sorted.

524 */

492 -static const char *find_reference_location(struct packed_ref_cache *cache,

525 +static const char *find_reference_location(struct snapshot *snapshot,

526 const char *refname, int mustexist)

527 {

528 /*

@@ -506,13 +539,13 @@ static const char *find_reference_location(struct packed_ref_cache *cache,

539 * preceding records all have reference names that come

540 * *before* `refname`.

541 */

509 - const char *lo = cache->buf + cache->header_len;

542 + const char *lo = snapshot->buf + snapshot->header_len;

543

544 /*

545 * A pointer to a the first character of a record whose

546 * reference name comes *after* `refname`.

547 */

515 - const char *hi = cache->eof;

548 + const char *hi = snapshot->eof;

549

550 while (lo < hi) {

551 const char *mid, *rec;

@@ -520,7 +553,7 @@ static const char *find_reference_location(struct packed_ref_cache *cache,

553

554 mid = lo + (hi - lo) / 2;

555 rec = find_start_of_record(lo, mid);

523 - cmp = cmp_entry_to_refname(rec, refname);

556 + cmp = cmp_record_to_refname(rec, refname);

557 if (cmp < 0) {

558 lo = find_end_of_record(mid, hi);

559 } else if (cmp > 0) {

@@ -537,9 +570,9 @@ static const char *find_reference_location(struct packed_ref_cache *cache,

570 }

571

572 /*

540 - * Read from the `packed-refs` file into a newly-allocated

541 - * `packed_ref_cache` and return it. The return value will already

542 - * have its reference count incremented.

573 + * Create a newly-allocated `snapshot` of the `packed-refs` file in

574 + * its current state and return it. The return value will already have

575 + * its reference count incremented.

576 *

577 * A comment line of the form "# pack-refs with: " may contain zero or

578 * more traits. We interpret the traits as follows:

@@ -569,116 +602,117 @@ static const char *find_reference_location(struct packed_ref_cache *cache,

602 *

603 * The references in this file are known to be sorted by refname.

604 */

572 -static struct packed_ref_cache *read_packed_refs(struct packed_ref_store *refs)

605 +static struct snapshot *create_snapshot(struct packed_ref_store *refs)

606 {

574 - struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));

607 + struct snapshot *snapshot = xcalloc(1, sizeof(*snapshot));

608 int sorted = 0;

609

577 - packed_refs->refs = refs;

578 - acquire_packed_ref_cache(packed_refs);

579 - packed_refs->peeled = PEELED_NONE;

610 + snapshot->refs = refs;

611 + acquire_snapshot(snapshot);

612 + snapshot->peeled = PEELED_NONE;

613

581 - if (!load_contents(packed_refs))

582 - return packed_refs;

614 + if (!load_contents(snapshot))

615 + return snapshot;

616

617 /* If the file has a header line, process it: */

585 - if (packed_refs->buf < packed_refs->eof && *packed_refs->buf == '#') {

618 + if (snapshot->buf < snapshot->eof && *snapshot->buf == '#') {

619 struct strbuf tmp = STRBUF_INIT;

620 char *p;

621 const char *eol;

622 struct string_list traits = STRING_LIST_INIT_NODUP;

623

591 - eol = memchr(packed_refs->buf, '\n',

592 - packed_refs->eof - packed_refs->buf);

624 + eol = memchr(snapshot->buf, '\n',

625 + snapshot->eof - snapshot->buf);

626 if (!eol)

627 die_unterminated_line(refs->path,

595 - packed_refs->buf,

596 - packed_refs->eof - packed_refs->buf);

628 + snapshot->buf,

629 + snapshot->eof - snapshot->buf);

630

598 - strbuf_add(&tmp, packed_refs->buf, eol - packed_refs->buf);

631 + strbuf_add(&tmp, snapshot->buf, eol - snapshot->buf);

632

633 if (!skip_prefix(tmp.buf, "# pack-refs with:", (const char **)&p))

634 die_invalid_line(refs->path,

602 - packed_refs->buf,

603 - packed_refs->eof - packed_refs->buf);

635 + snapshot->buf,

636 + snapshot->eof - snapshot->buf);

637

638 string_list_split_in_place(&traits, p, ' ', -1);

639

640 if (unsorted_string_list_has_string(&traits, "fully-peeled"))

608 - packed_refs->peeled = PEELED_FULLY;

641 + snapshot->peeled = PEELED_FULLY;

642 else if (unsorted_string_list_has_string(&traits, "peeled"))

610 - packed_refs->peeled = PEELED_TAGS;

643 + snapshot->peeled = PEELED_TAGS;

644

645 sorted = unsorted_string_list_has_string(&traits, "sorted");

646

647 /* perhaps other traits later as well */

648

649 /* The "+ 1" is for the LF character. */

617 - packed_refs->header_len = eol + 1 - packed_refs->buf;

650 + snapshot->header_len = eol + 1 - snapshot->buf;

651

652 string_list_clear(&traits, 0);

653 strbuf_release(&tmp);

654 }

655

623 - verify_buffer_safe(packed_refs);

656 + verify_buffer_safe(snapshot);

657

658 if (!sorted) {

626 - sort_packed_refs(packed_refs);

659 + sort_snapshot(snapshot);

660

661 /*

662 * Reordering the records might have moved a short one

663 * to the end of the buffer, so verify the buffer's

664 * safety again:

665 */

633 - verify_buffer_safe(packed_refs);

666 + verify_buffer_safe(snapshot);

667 }

668

636 - if (mmap_strategy != MMAP_OK && packed_refs->mmapped) {

669 + if (mmap_strategy != MMAP_OK && snapshot->mmapped) {

670 /*

671 * We don't want to leave the file mmapped, so we are

672 * forced to make a copy now:

673 */

641 - size_t size = packed_refs->eof -

642 - (packed_refs->buf + packed_refs->header_len);

674 + size_t size = snapshot->eof -

675 + (snapshot->buf + snapshot->header_len);

676 char *buf_copy = xmalloc(size);

677

645 - memcpy(buf_copy, packed_refs->buf + packed_refs->header_len, size);

646 - release_packed_ref_buffer(packed_refs);

647 - packed_refs->buf = buf_copy;

648 - packed_refs->eof = buf_copy + size;

678 + memcpy(buf_copy, snapshot->buf + snapshot->header_len, size);

679 + clear_snapshot_buffer(snapshot);

680 + snapshot->buf = buf_copy;

681 + snapshot->eof = buf_copy + size;

682 }

683

651 - return packed_refs;

684 + return snapshot;

685 }

686

687 /*

655 - * Check that the packed refs cache (if any) still reflects the

656 - * contents of the file. If not, clear the cache.

688 + * Check that `refs->snapshot` (if present) still reflects the

689 + * contents of the `packed-refs` file. If not, clear the snapshot.

690 */

658 -static void validate_packed_ref_cache(struct packed_ref_store *refs)

691 +static void validate_snapshot(struct packed_ref_store *refs)

692 {

660 - if (refs->cache &&

661 - !stat_validity_check(&refs->cache->validity, refs->path))

662 - clear_packed_ref_cache(refs);

693 + if (refs->snapshot &&

694 + !stat_validity_check(&refs->snapshot->validity, refs->path))

695 + clear_snapshot(refs);

696 }

697

698 /*

666 - * Get the packed_ref_cache for the specified packed_ref_store,

667 - * creating and populating it if it hasn't been read before or if the

668 - * file has been changed (according to its `validity` field) since it

669 - * was last read. On the other hand, if we hold the lock, then assume

670 - * that the file hasn't been changed out from under us, so skip the

671 - * extra `stat()` call in `stat_validity_check()`.

699 + * Get the `snapshot` for the specified packed_ref_store, creating and

700 + * populating it if it hasn't been read before or if the file has been

701 + * changed (according to its `validity` field) since it was last read.

702 + * On the other hand, if we hold the lock, then assume that the file

703 + * hasn't been changed out from under us, so skip the extra `stat()`

704 + * call in `stat_validity_check()`. This function does *not* increase

705 + * the snapshot's reference count on behalf of the caller.

706 */

673 -static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *refs)

707 +static struct snapshot *get_snapshot(struct packed_ref_store *refs)

708 {

709 if (!is_lock_file_locked(&refs->lock))

676 - validate_packed_ref_cache(refs);

710 + validate_snapshot(refs);

711

678 - if (!refs->cache)

679 - refs->cache = read_packed_refs(refs);

712 + if (!refs->snapshot)

713 + refs->snapshot = create_snapshot(refs);

714

681 - return refs->cache;

715 + return refs->snapshot;

716 }

717

718 static int packed_read_raw_ref(struct ref_store *ref_store,

@@ -687,12 +721,12 @@ static int packed_read_raw_ref(struct ref_store *ref_store,

721 {

722 struct packed_ref_store *refs =

723 packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");

690 - struct packed_ref_cache *packed_refs = get_packed_ref_cache(refs);

724 + struct snapshot *snapshot = get_snapshot(refs);

725 const char *rec;

726

727 *type = 0;

728

695 - rec = find_reference_location(packed_refs, refname, 1);

729 + rec = find_reference_location(snapshot, refname, 1);

730

731 if (!rec) {

732 /* refname is not a packed reference. */

@@ -701,7 +735,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store,

735 }

736

737 if (get_sha1_hex(rec, sha1))

704 - die_invalid_line(refs->path, rec, packed_refs->eof - rec);

738 + die_invalid_line(refs->path, rec, snapshot->eof - rec);

739

740 *type = REF_ISPACKED;

741 return 0;

@@ -716,26 +750,33 @@ static int packed_read_raw_ref(struct ref_store *ref_store,

750 #define REF_KNOWS_PEELED 0x40

751

752 /*

719 - * An iterator over a packed-refs file that is currently mmapped.

753 + * An iterator over a snapshot of a `packed-refs` file.

754 */

755 struct packed_ref_iterator {

756 struct ref_iterator base;

757

724 - struct packed_ref_cache *packed_refs;

758 + struct snapshot *snapshot;

759

726 - /* The current position in the mmapped file: */

760 + /* The current position in the snapshot's buffer: */

761 const char *pos;

762

729 - /* The end of the mmapped file: */

763 + /* The end of the part of the buffer that will be iterated over: */

764 const char *eof;

765

766 + /* Scratch space for current values: */

767 struct object_id oid, peeled;

733 -

768 struct strbuf refname_buf;

769

770 unsigned int flags;

771 };

772

773 +/*

774 + * Move the iterator to the next record in the snapshot, without

775 + * respect for whether the record is actually required by the current

776 + * iteration. Adjust the fields in `iter` and return `ITER_OK` or

777 + * `ITER_DONE`. This function does not free the iterator in the case

778 + * of `ITER_DONE`.

779 + */

780 static int next_record(struct packed_ref_iterator *iter)

781 {

782 const char *p = iter->pos, *eol;

@@ -750,12 +791,12 @@ static int next_record(struct packed_ref_iterator *iter)

791 if (iter->eof - p < GIT_SHA1_HEXSZ + 2 ||

792 parse_oid_hex(p, &iter->oid, &p) ||

793 !isspace(*p++))

753 - die_invalid_line(iter->packed_refs->refs->path,

794 + die_invalid_line(iter->snapshot->refs->path,

795 iter->pos, iter->eof - iter->pos);

796

797 eol = memchr(p, '\n', iter->eof - p);

798 if (!eol)

758 - die_unterminated_line(iter->packed_refs->refs->path,

799 + die_unterminated_line(iter->snapshot->refs->path,

800 iter->pos, iter->eof - iter->pos);

801

802 strbuf_add(&iter->refname_buf, p, eol - p);

@@ -768,8 +809,8 @@ static int next_record(struct packed_ref_iterator *iter)

809 oidclr(&iter->oid);

810 iter->base.flags |= REF_BAD_NAME | REF_ISBROKEN;

811 }

771 - if (iter->packed_refs->peeled == PEELED_FULLY ||

772 - (iter->packed_refs->peeled == PEELED_TAGS &&

812 + if (iter->snapshot->peeled == PEELED_FULLY ||

813 + (iter->snapshot->peeled == PEELED_TAGS &&

814 starts_with(iter->base.refname, "refs/tags/")))

815 iter->base.flags |= REF_KNOWS_PEELED;

816

@@ -780,7 +821,7 @@ static int next_record(struct packed_ref_iterator *iter)

821 if (iter->eof - p < GIT_SHA1_HEXSZ + 1 ||

822 parse_oid_hex(p, &iter->peeled, &p) ||

823 *p++ != '\n')

783 - die_invalid_line(iter->packed_refs->refs->path,

824 + die_invalid_line(iter->snapshot->refs->path,

825 iter->pos, iter->eof - iter->pos);

826 iter->pos = p;

827

@@ -850,7 +891,7 @@ static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)

891 int ok = ITER_DONE;

892

893 strbuf_release(&iter->refname_buf);

853 - release_packed_ref_cache(iter->packed_refs);

894 + release_snapshot(iter->snapshot);

895 base_ref_iterator_free(ref_iterator);

896 return ok;

897 }

@@ -866,7 +907,7 @@ static struct ref_iterator *packed_ref_iterator_begin(

907 const char *prefix, unsigned int flags)

908 {

909 struct packed_ref_store *refs;

869 - struct packed_ref_cache *packed_refs;

910 + struct snapshot *snapshot;

911 const char *start;

912 struct packed_ref_iterator *iter;

913 struct ref_iterator *ref_iterator;

@@ -876,30 +917,30 @@ static struct ref_iterator *packed_ref_iterator_begin(

917 required_flags |= REF_STORE_ODB;

918 refs = packed_downcast(ref_store, required_flags, "ref_iterator_begin");

919

879 - packed_refs = get_packed_ref_cache(refs);

920 + /*

921 + * Note that `get_snapshot()` internally checks whether the

922 + * snapshot is up to date with what is on disk, and re-reads

923 + * it if not.

924 + */

925 + snapshot = get_snapshot(refs);

926

881 - if (!packed_refs->buf)

927 + if (!snapshot->buf)

928 return empty_ref_iterator_begin();

929

930 iter = xcalloc(1, sizeof(*iter));

931 ref_iterator = &iter->base;

932 base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable, 1);

933

888 - /*

889 - * Note that get_packed_ref_cache() internally checks whether

890 - * the packed-ref cache is up to date with what is on disk,

891 - * and re-reads it if not.

892 - */

893 - iter->packed_refs = packed_refs;

894 - acquire_packed_ref_cache(packed_refs);

934 + iter->snapshot = snapshot;

935 + acquire_snapshot(snapshot);

936

937 if (prefix && *prefix)

897 - start = find_reference_location(packed_refs, prefix, 0);

938 + start = find_reference_location(snapshot, prefix, 0);

939 else

899 - start = packed_refs->buf + packed_refs->header_len;

940 + start = snapshot->buf + snapshot->header_len;

941

942 iter->pos = start;

902 - iter->eof = packed_refs->eof;

943 + iter->eof = snapshot->eof;

944 strbuf_init(&iter->refname_buf, 0);

945

946 iter->base.oid = &iter->oid;

@@ -963,19 +1004,19 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)

1004

1005 /*

1006 * Now that we hold the `packed-refs` lock, make sure that our

966 - * cache matches the current version of the file. Normally

967 - * `get_packed_ref_cache()` does that for us, but that

968 - * function assumes that when the file is locked, any existing

969 - * cache is still valid. We've just locked the file, but it

970 - * might have changed the moment *before* we locked it.

1007 + * snapshot matches the current version of the file. Normally

1008 + * `get_snapshot()` does that for us, but that function

1009 + * assumes that when the file is locked, any existing snapshot

1010 + * is still valid. We've just locked the file, but it might

1011 + * have changed the moment *before* we locked it.

1012 */

972 - validate_packed_ref_cache(refs);

1013 + validate_snapshot(refs);

1014

1015 /*

1016 * Now make sure that the packed-refs file as it exists in the

976 - * locked state is loaded into the cache:

1017 + * locked state is loaded into the snapshot:

1018 */

978 - get_packed_ref_cache(refs);

1019 + get_snapshot(refs);

1020 return 0;

1021 }

1022

@@ -1002,8 +1043,8 @@ int packed_refs_is_locked(struct ref_store *ref_store)

1043 }

1044

1045 /*

1005 - * The packed-refs header line that we write out. Perhaps other

1006 - * traits will be added later.

1046 + * The packed-refs header line that we write out. Perhaps other traits

1047 + * will be added later.

1048 *

1049 * Note that earlier versions of Git used to parse these traits by

1050 * looking for " trait " in the line. For this reason, the space after

@@ -1019,9 +1060,9 @@ static int packed_init_db(struct ref_store *ref_store, struct strbuf *err)

1060 }

1061

1062 /*

1022 - * Write the packed-refs from the cache to the packed-refs tempfile,

1023 - * incorporating any changes from `updates`. `updates` must be a

1024 - * sorted string list whose keys are the refnames and whose util

1063 + * Write the packed refs from the current snapshot to the packed-refs

1064 + * tempfile, incorporating any changes from `updates`. `updates` must

1065 + * be a sorted string list whose keys are the refnames and whose util

1066 * values are `struct ref_update *`. On error, rollback the tempfile,

1067 * write an error message to `err`, and return a nonzero value.

1068 *

@@ -1262,9 +1303,10 @@ static int packed_transaction_prepare(struct ref_store *ref_store,

1303 /*

1304 * Note that we *don't* skip transactions with zero updates,

1305 * because such a transaction might be executed for the side

1265 - * effect of ensuring that all of the references are peeled.

1266 - * If the caller wants to optimize away empty transactions, it

1267 - * should do so itself.

1306 + * effect of ensuring that all of the references are peeled or

1307 + * ensuring that the `packed-refs` file is sorted. If the

1308 + * caller wants to optimize away empty transactions, it should

1309 + * do so itself.

1310 */

1311

1312 data = xcalloc(1, sizeof(*data));

@@ -1330,7 +1372,7 @@ static int packed_transaction_finish(struct ref_store *ref_store,

1372 int ret = TRANSACTION_GENERIC_ERROR;

1373 char *packed_refs_path;

1374

1333 - clear_packed_ref_cache(refs);

1375 + clear_snapshot(refs);

1376

1377 packed_refs_path = get_locked_file_path(&refs->lock);

1378 if (rename_tempfile(&refs->tempfile, packed_refs_path)) {

packed-backend.c: rename a bunch of things and update comments