@matheusbsbs / matheus-bagliano / commits / 156d79cef0

reftable/block: store block pointer in the block iterator

The block iterator requires access to a bunch of data from the underlying `reftable_block` that it is iterating over. This data is stored by copying over relevant data into a separate set of variables. This has multiple downsides: - We require more storage space than necessary. This is more of a theoretical issue as we shouldn't ever have many blocks. - We have to perform more bookkeeping, and the variable names are inconsistent across the two data structures. This can lead to some confusion. - The lifetime of the block iterator is tied to the block anyway, but we hide that a bit by only storing pointers pointing into the block. There isn't really any good reason why we rip out parts of the block instead of storing a pointer to the block itself. Refactor the code to do so. Despite being simpler, it also allows us to decouple the lifetime of the block iterator from seeking in a subsequent commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Patrick Steinhardt committed Apr 7, 2025 at 15:16 UTC 156d79cef0de565408e41f840bbda87114367977

2 files changed +9 -17

reftable/block.c

+8 -14

@@ -381,13 +381,11 @@ static uint32_t block_restart_offset(const struct reftable_block *b, size_t idx)

381 return reftable_get_be24(b->block_data.data + b->restart_off + 3 * idx);

382 }

383

384 -void block_iter_seek_start(struct block_iter *it, const struct reftable_block *b)

384 +void block_iter_seek_start(struct block_iter *it, const struct reftable_block *block)

385 {

386 - it->block = b->block_data.data;

387 - it->block_len = b->restart_off;

388 - it->hash_size = b->hash_size;

386 + it->block = block;

387 reftable_buf_reset(&it->last_key);

390 - it->next_off = b->header_off + 4;

388 + it->next_off = block->header_off + 4;

389 }

390

391 struct restart_needle_less_args {

@@ -435,14 +433,14 @@ static int restart_needle_less(size_t idx, void *_args)

433 int block_iter_next(struct block_iter *it, struct reftable_record *rec)

434 {

435 struct string_view in = {

438 - .buf = (unsigned char *) it->block + it->next_off,

439 - .len = it->block_len - it->next_off,

436 + .buf = (unsigned char *) it->block->block_data.data + it->next_off,

437 + .len = it->block->restart_off - it->next_off,

438 };

439 struct string_view start = in;

440 uint8_t extra = 0;

441 int n = 0;

442

445 - if (it->next_off >= it->block_len)

443 + if (it->next_off >= it->block->restart_off)

444 return 1;

445

446 n = reftable_decode_key(&it->last_key, &extra, in);

@@ -452,7 +450,7 @@ int block_iter_next(struct block_iter *it, struct reftable_record *rec)

450 return REFTABLE_FORMAT_ERROR;

451

452 string_view_consume(&in, n);

455 - n = reftable_record_decode(rec, it->last_key, extra, in, it->hash_size,

453 + n = reftable_record_decode(rec, it->last_key, extra, in, it->block->hash_size,

454 &it->scratch);

455 if (n < 0)

456 return -1;

@@ -467,8 +465,6 @@ void block_iter_reset(struct block_iter *it)

465 reftable_buf_reset(&it->last_key);

466 it->next_off = 0;

467 it->block = NULL;

470 - it->block_len = 0;

471 - it->hash_size = 0;

468 }

469

470 void block_iter_close(struct block_iter *it)

@@ -528,9 +524,7 @@ int block_iter_seek_key(struct block_iter *it, const struct reftable_block *bloc

524 it->next_off = block_restart_offset(block, i - 1);

525 else

526 it->next_off = block->header_off + 4;

531 - it->block = block->block_data.data;

532 - it->block_len = block->restart_off;

533 - it->hash_size = block->hash_size;

527 + it->block = block;

528

529 err = reftable_record_init(&rec, reftable_block_type(block));

530 if (err < 0)

reftable/block.h

+1 -3

@@ -67,9 +67,7 @@ void block_writer_release(struct block_writer *bw);

67 struct block_iter {

68 /* offset within the block of the next entry to read. */

69 uint32_t next_off;

70 - const unsigned char *block;

71 - size_t block_len;

72 - uint32_t hash_size;

70 + const struct reftable_block *block;

72 /* key for last entry we read. */

73 struct reftable_buf last_key;