pack-bitmap-write: fill bitmap with commit history

The current implementation of bitmap_writer_build() creates a
reachability bitmap for every walked commit. After computing a bitmap
for a commit, those bits are pushed to an in-progress bitmap for its

fill_bitmap_commit() assumes the bits corresponding to objects
reachable from the parents of a commit are already set. This means that
when visiting a new commit, we only have to walk the objects reachable
between it and any of its parents.

A future change to bitmap_writer_build() will relax this condition so
not all parents have their bits set. Prepare for that by having
'fill_bitmap_commit()' walk parents until reaching commits whose bits
are already set. Then, walk the trees for these commits as well.

This has no functional change with the current implementation of

Signed-off-by: Derrick Stolee <>
Signed-off-by: Taylor Blau <>
Signed-off-by: Junio C Hamano <>
Derrick Stolee 2 years ago committed by Junio C Hamano
parent 010e5eacfb
commit 6dc5ef759f
  1. 30

@ -12,6 +12,7 @@
#include "sha1-lookup.h"
#include "pack-objects.h"
#include "commit-reach.h"
#include "prio-queue.h"
struct bitmapped_commit {
struct commit *commit;
@ -279,17 +280,30 @@ static void fill_bitmap_tree(struct bitmap *bitmap,
static void fill_bitmap_commit(struct bb_commit *ent,
struct commit *commit)
struct commit *commit,
struct prio_queue *queue)
if (!ent->bitmap)
ent->bitmap = bitmap_new();
* mark ourselves, but do not bother with parents; their values
* will already have been propagated to us
bitmap_set(ent->bitmap, find_object_pos(&commit->object.oid));
fill_bitmap_tree(ent->bitmap, get_commit_tree(commit));
prio_queue_put(queue, commit);
while (queue->nr) {
struct commit_list *p;
struct commit *c = prio_queue_get(queue);
bitmap_set(ent->bitmap, find_object_pos(&c->object.oid));
fill_bitmap_tree(ent->bitmap, get_commit_tree(c));
for (p = c->parents; p; p = p->next) {
int pos = find_object_pos(&p->item->object.oid);
if (!bitmap_get(ent->bitmap, pos)) {
bitmap_set(ent->bitmap, pos);
prio_queue_put(queue, p->item);
static void store_selected(struct bb_commit *ent, struct commit *commit)
@ -319,6 +333,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
struct bitmap_builder bb;
size_t i;
int nr_stored = 0; /* for progress */
struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
writer.bitmaps = kh_init_oid_map();
writer.to_pack = to_pack;
@ -335,7 +350,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
struct commit *child;
int reused = 0;
fill_bitmap_commit(ent, commit);
fill_bitmap_commit(ent, commit, &queue);
if (ent->selected) {
store_selected(ent, commit);
@ -360,6 +375,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
ent->bitmap = NULL;
trace2_region_leave("pack-bitmap-write", "building_bitmaps_total",