@matheusbsbs / matheus-bagliano / commits / 94830fcacc

pack-bitmap-write.c: move commit_positions into commit_pos fields

In 7cc8f971085 (pack-objects: implement bitmap writing, 2013-12-21), the bitmapped_commit struct was introduced, including the 'commit_pos' field, which has been unused ever since its introduction more than a decade ago. Instead, we have used the nearby `commit_positions` array leaving the bitmapped_commit struct with an unused 4-byte field. We could drop the `commit_pos` field as unused, and continue to store the values in the auxiliary array. But we could also drop the array and store the data for each bitmapped_commit struct inside of the structure itself, which is what this patch does. In any spot that we previously read `commit_positions[i]`, we can now instead read `writer.selected[i].commit_pos`. There are a few spots that need changing as a result: - write_selected_commits_v1() is a simple transformation, since we're just reading the field. As a result, the function no longer needs an explicit argument to pass the commit_positions array. - write_lookup_table() also no longer needs the explicit commit_positions array passed in as an argument. But it still needs to sort an array of indices into the writer.selected array to read them in commit_pos order, so table_cmp() is adjusted accordingly. - bitmap_writer_finish() no longer needs to allocate, populate, and free the commit_positions table. Instead, we can just write the data directly into each struct bitmapped_commit. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Taylor Blau committed May 14, 2024 at 15:56 UTC 94830fcaccebbe48916c22a1a773e5b25a366c61

1 file changed +16 -25

pack-bitmap-write.c

+16 -25

@@ -670,9 +670,7 @@ static const struct object_id *oid_access(size_t pos, const void *table)

670 return &index[pos]->oid;

671 }

672

673 -static void write_selected_commits_v1(struct hashfile *f,

674 - uint32_t *commit_positions,

675 - off_t *offsets)

673 +static void write_selected_commits_v1(struct hashfile *f, off_t *offsets)

674 {

675 int i;

676

@@ -682,7 +680,7 @@ static void write_selected_commits_v1(struct hashfile *f,

680 if (offsets)

681 offsets[i] = hashfile_total(f);

682

685 - hashwrite_be32(f, commit_positions[i]);

683 + hashwrite_be32(f, stored->commit_pos);

684 hashwrite_u8(f, stored->xor_offset);

685 hashwrite_u8(f, stored->flags);

686

@@ -690,23 +688,20 @@ static void write_selected_commits_v1(struct hashfile *f,

688 }

689 }

690

693 -static int table_cmp(const void *_va, const void *_vb, void *_data)

691 +static int table_cmp(const void *_va, const void *_vb)

692 {

695 - uint32_t *commit_positions = _data;

696 - uint32_t a = commit_positions[*(uint32_t *)_va];

697 - uint32_t b = commit_positions[*(uint32_t *)_vb];

693 + struct bitmapped_commit *a = &writer.selected[*(uint32_t *)_va];

694 + struct bitmapped_commit *b = &writer.selected[*(uint32_t *)_vb];

695

699 - if (a > b)

700 - return 1;

701 - else if (a < b)

696 + if (a->commit_pos < b->commit_pos)

697 return -1;

698 + else if (a->commit_pos > b->commit_pos)

699 + return 1;

700

701 return 0;

702 }

703

707 -static void write_lookup_table(struct hashfile *f,

708 - uint32_t *commit_positions,

709 - off_t *offsets)

704 +static void write_lookup_table(struct hashfile *f, off_t *offsets)

705 {

706 uint32_t i;

707 uint32_t *table, *table_inv;

@@ -722,7 +717,7 @@ static void write_lookup_table(struct hashfile *f,

717 * bitmap corresponds to j'th bitmapped commit (among the selected

718 * commits) in lex order of OIDs.

719 */

725 - QSORT_S(table, writer.selected_nr, table_cmp, commit_positions);

720 + QSORT(table, writer.selected_nr, table_cmp);

721

722 /* table_inv helps us discover that relationship (i'th bitmap

723 * to j'th commit by j = table_inv[i])

@@ -753,7 +748,7 @@ static void write_lookup_table(struct hashfile *f,

748 xor_row = 0xffffffff;

749 }

750

756 - hashwrite_be32(f, commit_positions[table[i]]);

751 + hashwrite_be32(f, writer.selected[table[i]].commit_pos);

752 hashwrite_be64(f, (uint64_t)offsets[table[i]]);

753 hashwrite_be32(f, xor_row);

754 }

@@ -789,7 +784,6 @@ void bitmap_writer_finish(struct pack_idx_entry **index,

784 static uint16_t flags = BITMAP_OPT_FULL_DAG;

785 struct strbuf tmp_file = STRBUF_INIT;

786 struct hashfile *f;

792 - uint32_t *commit_positions = NULL;

787 off_t *offsets = NULL;

788 uint32_t i;

789

@@ -814,22 +808,20 @@ void bitmap_writer_finish(struct pack_idx_entry **index,

808 if (options & BITMAP_OPT_LOOKUP_TABLE)

809 CALLOC_ARRAY(offsets, index_nr);

810

817 - ALLOC_ARRAY(commit_positions, writer.selected_nr);

818 -

811 for (i = 0; i < writer.selected_nr; i++) {

812 struct bitmapped_commit *stored = &writer.selected[i];

821 - int commit_pos = oid_pos(&stored->commit->object.oid, index, index_nr, oid_access);

813 + int commit_pos = oid_pos(&stored->commit->object.oid, index,

814 + index_nr, oid_access);

815

816 if (commit_pos < 0)

817 BUG(_("trying to write commit not in index"));

825 -

826 - commit_positions[i] = commit_pos;

818 + stored->commit_pos = commit_pos;

819 }

820

829 - write_selected_commits_v1(f, commit_positions, offsets);

821 + write_selected_commits_v1(f, offsets);

822

823 if (options & BITMAP_OPT_LOOKUP_TABLE)

832 - write_lookup_table(f, commit_positions, offsets);

824 + write_lookup_table(f, offsets);

825

826 if (options & BITMAP_OPT_HASH_CACHE)

827 write_hash_cache(f, index, index_nr);

@@ -844,6 +836,5 @@ void bitmap_writer_finish(struct pack_idx_entry **index,

836 die_errno("unable to rename temporary bitmap file to '%s'", filename);

837

838 strbuf_release(&tmp_file);

847 - free(commit_positions);

839 free(offsets);

840 }