Current find_unresolved_deltas() links all bases together in a form of
tree, using struct base_data, with prev_base pointer to point to
parent node. Then it traverses down from parent to children in
recursive manner with all base_data allocated on stack.
To eliminate recursion, we simply need to put all on heap
(parse_pack_objects and fix_unresolved_deltas). After that, it's
simple non-recursive depth-first traversal loop. Each node also
maintains its own state (ofs and ref indices) to iterate over all
children nodes.
So we process one node:
- if it returns a new (child) node (a parent base), we link it to our
tree, then process the new node.
- if it returns nothing, the node is done, free it. We go back to
parent node and resume whatever it's doing.
and do it until we have no nodes to process.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
builtin/index-pack.c | 111 +++++++++++++++++++++++++++++++------------------
1 files changed, 70 insertions(+), 41 deletions(-)
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index af7dc37..38ff03a 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -34,6 +34,8 @@ struct base_data {
struct object_entry *obj;
void *data;
unsigned long size;
+ int ref_first, ref_last;
+ int ofs_first, ofs_last;
};
/*
@@ -221,6 +223,15 @@ static NORETURN void bad_object(unsigned long offset, const char *format, ...)
die("pack has bad object at offset %lu: %s", offset, buf);
}
+static struct base_data *alloc_base_data(void)
+{
+ struct base_data *base = xmalloc(sizeof(struct base_data));
+ memset(base, 0, sizeof(*base));
+ base->ref_last = -1;
+ base->ofs_last = -1;
+ return base;
+}
+
static void free_base_data(struct base_data *c)
{
if (c->data) {
@@ -553,58 +564,76 @@ static void resolve_delta(struct object_entry *delta_obj,
nr_resolved_deltas++;
}
-static void find_unresolved_deltas(struct base_data *base,
- struct base_data *prev_base)
+static struct base_data *find_unresolved_deltas_1(struct base_data *base,
+ struct base_data *prev_base)
{
- int i, ref_first, ref_last, ofs_first, ofs_last;
-
- /*
- * This is a recursive function. Those brackets should help reducing
- * stack usage by limiting the scope of the delta_base union.
- */
- {
+ if (base->ref_last == -1 && base->ofs_last == -1) {
union delta_base base_spec;
hashcpy(base_spec.sha1, base->obj->idx.sha1);
find_delta_children(&base_spec,
- &ref_first, &ref_last, OBJ_REF_DELTA);
+ &base->ref_first, &base->ref_last, OBJ_REF_DELTA);
memset(&base_spec, 0, sizeof(base_spec));
base_spec.offset = base->obj->idx.offset;
find_delta_children(&base_spec,
- &ofs_first, &ofs_last, OBJ_OFS_DELTA);
- }
+ &base->ofs_first, &base->ofs_last, OBJ_OFS_DELTA);
- if (ref_last == -1 && ofs_last == -1) {
- free(base->data);
- return;
- }
+ if (base->ref_last == -1 && base->ofs_last == -1) {
+ free(base->data);
+ return NULL;
+ }
- link_base_data(prev_base, base);
+ link_base_data(prev_base, base);
+ }
- for (i = ref_first; i <= ref_last; i++) {
- struct object_entry *child = objects + deltas[i].obj_no;
- struct base_data result;
+ if (base->ref_first <= base->ref_last) {
+ struct object_entry *child = objects + deltas[base->ref_first].obj_no;
+ struct base_data *result = alloc_base_data();
assert(child->real_type == OBJ_REF_DELTA);
- resolve_delta(child, base, &result);
- if (i == ref_last && ofs_last == -1)
+ resolve_delta(child, base, result);
+ if (base->ref_first == base->ref_last && base->ofs_last == -1)
free_base_data(base);
- find_unresolved_deltas(&result, base);
+
+ base->ref_first++;
+ return result;
}
- for (i = ofs_first; i <= ofs_last; i++) {
- struct object_entry *child = objects + deltas[i].obj_no;
- struct base_data result;
+ if (base->ofs_first <= base->ofs_last) {
+ struct object_entry *child = objects + deltas[base->ofs_first].obj_no;
+ struct base_data *result = alloc_base_data();
assert(child->real_type == OBJ_OFS_DELTA);
- resolve_delta(child, base, &result);
- if (i == ofs_last)
+ resolve_delta(child, base, result);
+ if (base->ofs_first == base->ofs_last)
free_base_data(base);
- find_unresolved_deltas(&result, base);
+
+ base->ofs_first++;
+ return result;
}
unlink_base_data(base);
+ return NULL;
+}
+
+static void find_unresolved_deltas(struct base_data *base)
+{
+ struct base_data *new_base, *prev_base = NULL;
+ for (;;) {
+ new_base = find_unresolved_deltas_1(base, prev_base);
+
+ if (new_base) {
+ prev_base = base;
+ base = new_base;
+ } else {
+ free(base);
+ base = prev_base;
+ if (!base)
+ return;
+ prev_base = base->base;
+ }
+ }
}
static int compare_delta_entry(const void *a, const void *b)
@@ -684,13 +713,13 @@ static void parse_pack_objects(unsigned char *sha1)
progress = start_progress("Resolving deltas", nr_deltas);
for (i = 0; i < nr_objects; i++) {
struct object_entry *obj = &objects[i];
- struct base_data base_obj;
+ struct base_data *base_obj = alloc_base_data();
if (is_delta_type(obj->type))
continue;
- base_obj.obj = obj;
- base_obj.data = NULL;
- find_unresolved_deltas(&base_obj, NULL);
+ base_obj->obj = obj;
+ base_obj->data = NULL;
+ find_unresolved_deltas(base_obj);
display_progress(progress, nr_resolved_deltas);
}
}
@@ -783,20 +812,20 @@ static void fix_unresolved_deltas(struct sha1file *f, int nr_unresolved)
for (i = 0; i < n; i++) {
struct delta_entry *d = sorted_by_pos[i];
enum object_type type;
- struct base_data base_obj;
+ struct base_data *base_obj = alloc_base_data();
if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
continue;
- base_obj.data = read_sha1_file(d->base.sha1, &type, &base_obj.size);
- if (!base_obj.data)
+ base_obj->data = read_sha1_file(d->base.sha1, &type, &base_obj->size);
+ if (!base_obj->data)
continue;
- if (check_sha1_signature(d->base.sha1, base_obj.data,
- base_obj.size, typename(type)))
+ if (check_sha1_signature(d->base.sha1, base_obj->data,
+ base_obj->size, typename(type)))
die("local object %s is corrupt", sha1_to_hex(d->base.sha1));
- base_obj.obj = append_obj_to_pack(f, d->base.sha1,
- base_obj.data, base_obj.size, type);
- find_unresolved_deltas(&base_obj, NULL);
+ base_obj->obj = append_obj_to_pack(f, d->base.sha1,
+ base_obj->data, base_obj->size, type);
+ find_unresolved_deltas(base_obj);
display_progress(progress, nr_resolved_deltas);
}
free(sorted_by_pos);
--
1.7.8.36.g69ee2
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