These delta pointers always point to elements in the objects[] array
in packing_data struct. We can only hold maximum 4GB of those objects
because the array length, nr_objects, is uint32_t. We could use
uint32_t indexes to address these elements instead of pointers. On
64-bit architecture (8 bytes per pointer) this would save 4 bytes per
pointer.
Convert these delta pointers to indexes. Since we need to handle NULL
pointers as well, the index is shifted by one [1].
[1] This means we can only index 2^32-2 objects even though nr_objects
could contain 2^32-1 objects. It should not be a problem in
practice because when we grow objects[], nr_alloc would probably
blow up long before nr_objects hits the wall.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
builtin/pack-objects.c | 116 ++++++++++++++++++++++-------------------
pack-objects.h | 67 ++++++++++++++++++++++--
2 files changed, 124 insertions(+), 59 deletions(-)
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index ca993e55dd..cdbad57082 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -30,6 +30,12 @@
#include "packfile.h"
#define IN_PACK(obj) oe_in_pack(&to_pack, obj)
+#define DELTA(obj) oe_delta(&to_pack, obj)
+#define DELTA_CHILD(obj) oe_delta_child(&to_pack, obj)
+#define DELTA_SIBLING(obj) oe_delta_sibling(&to_pack, obj)
+#define SET_DELTA(obj, val) oe_set_delta(&to_pack, obj, val)
+#define SET_DELTA_CHILD(obj, val) oe_set_delta_child(&to_pack, obj, val)
+#define SET_DELTA_SIBLING(obj, val) oe_set_delta_sibling(&to_pack, obj, val)
static const char *pack_usage[] = {
N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
@@ -127,11 +133,11 @@ static void *get_delta(struct object_entry *entry)
buf = read_sha1_file(entry->idx.oid.hash, &type, &size);
if (!buf)
die("unable to read %s", oid_to_hex(&entry->idx.oid));
- base_buf = read_sha1_file(entry->delta->idx.oid.hash, &type,
+ base_buf = read_sha1_file(DELTA(entry)->idx.oid.hash, &type,
&base_size);
if (!base_buf)
die("unable to read %s",
- oid_to_hex(&entry->delta->idx.oid));
+ oid_to_hex(&DELTA(entry)->idx.oid));
delta_buf = diff_delta(base_buf, base_size,
buf, size, &delta_size, 0);
if (!delta_buf || delta_size != entry->delta_size)
@@ -288,12 +294,12 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
size = entry->delta_size;
buf = entry->delta_data;
entry->delta_data = NULL;
- type = (allow_ofs_delta && entry->delta->idx.offset) ?
+ type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
OBJ_OFS_DELTA : OBJ_REF_DELTA;
} else {
buf = get_delta(entry);
size = entry->delta_size;
- type = (allow_ofs_delta && entry->delta->idx.offset) ?
+ type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
OBJ_OFS_DELTA : OBJ_REF_DELTA;
}
@@ -317,7 +323,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
* encoding of the relative offset for the delta
* base from this object's position in the pack.
*/
- off_t ofs = entry->idx.offset - entry->delta->idx.offset;
+ off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
unsigned pos = sizeof(dheader) - 1;
dheader[pos] = ofs & 127;
while (ofs >>= 7)
@@ -343,7 +349,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
return 0;
}
hashwrite(f, header, hdrlen);
- hashwrite(f, entry->delta->idx.oid.hash, 20);
+ hashwrite(f, DELTA(entry)->idx.oid.hash, 20);
hdrlen += 20;
} else {
if (limit && hdrlen + datalen + 20 >= limit) {
@@ -379,8 +385,8 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
dheader[MAX_PACK_OBJECT_HEADER];
unsigned hdrlen;
- if (entry->delta)
- type = (allow_ofs_delta && entry->delta->idx.offset) ?
+ if (DELTA(entry))
+ type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
OBJ_OFS_DELTA : OBJ_REF_DELTA;
hdrlen = encode_in_pack_object_header(header, sizeof(header),
type, entry->size);
@@ -408,7 +414,7 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
}
if (type == OBJ_OFS_DELTA) {
- off_t ofs = entry->idx.offset - entry->delta->idx.offset;
+ off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
unsigned pos = sizeof(dheader) - 1;
dheader[pos] = ofs & 127;
while (ofs >>= 7)
@@ -427,7 +433,7 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
return 0;
}
hashwrite(f, header, hdrlen);
- hashwrite(f, entry->delta->idx.oid.hash, 20);
+ hashwrite(f, DELTA(entry)->idx.oid.hash, 20);
hdrlen += 20;
reused_delta++;
} else {
@@ -467,13 +473,13 @@ static off_t write_object(struct hashfile *f,
else
limit = pack_size_limit - write_offset;
- if (!entry->delta)
+ if (!DELTA(entry))
usable_delta = 0; /* no delta */
else if (!pack_size_limit)
usable_delta = 1; /* unlimited packfile */
- else if (entry->delta->idx.offset == (off_t)-1)
+ else if (DELTA(entry)->idx.offset == (off_t)-1)
usable_delta = 0; /* base was written to another pack */
- else if (entry->delta->idx.offset)
+ else if (DELTA(entry)->idx.offset)
usable_delta = 1; /* base already exists in this pack */
else
usable_delta = 0; /* base could end up in another pack */
@@ -489,7 +495,7 @@ static off_t write_object(struct hashfile *f,
/* ... but pack split may override that */
else if (oe_type(entry) != entry->in_pack_type)
to_reuse = 0; /* pack has delta which is unusable */
- else if (entry->delta)
+ else if (DELTA(entry))
to_reuse = 0; /* we want to pack afresh */
else
to_reuse = 1; /* we have it in-pack undeltified,
@@ -541,12 +547,12 @@ static enum write_one_status write_one(struct hashfile *f,
}
/* if we are deltified, write out base object first. */
- if (e->delta) {
+ if (DELTA(e)) {
e->idx.offset = 1; /* now recurse */
- switch (write_one(f, e->delta, offset)) {
+ switch (write_one(f, DELTA(e), offset)) {
case WRITE_ONE_RECURSIVE:
/* we cannot depend on this one */
- e->delta = NULL;
+ SET_DELTA(e, NULL);
break;
default:
break;
@@ -608,34 +614,34 @@ static void add_descendants_to_write_order(struct object_entry **wo,
/* add this node... */
add_to_write_order(wo, endp, e);
/* all its siblings... */
- for (s = e->delta_sibling; s; s = s->delta_sibling) {
+ for (s = DELTA_SIBLING(e); s; s = DELTA_SIBLING(s)) {
add_to_write_order(wo, endp, s);
}
}
/* drop down a level to add left subtree nodes if possible */
- if (e->delta_child) {
+ if (DELTA_CHILD(e)) {
add_to_order = 1;
- e = e->delta_child;
+ e = DELTA_CHILD(e);
} else {
add_to_order = 0;
/* our sibling might have some children, it is next */
- if (e->delta_sibling) {
- e = e->delta_sibling;
+ if (DELTA_SIBLING(e)) {
+ e = DELTA_SIBLING(e);
continue;
}
/* go back to our parent node */
- e = e->delta;
- while (e && !e->delta_sibling) {
+ e = DELTA(e);
+ while (e && !DELTA_SIBLING(e)) {
/* we're on the right side of a subtree, keep
* going up until we can go right again */
- e = e->delta;
+ e = DELTA(e);
}
if (!e) {
/* done- we hit our original root node */
return;
}
/* pass it off to sibling at this level */
- e = e->delta_sibling;
+ e = DELTA_SIBLING(e);
}
};
}
@@ -646,7 +652,7 @@ static void add_family_to_write_order(struct object_entry **wo,
{
struct object_entry *root;
- for (root = e; root->delta; root = root->delta)
+ for (root = e; DELTA(root); root = DELTA(root))
; /* nothing */
add_descendants_to_write_order(wo, endp, root);
}
@@ -661,8 +667,8 @@ static struct object_entry **compute_write_order(void)
for (i = 0; i < to_pack.nr_objects; i++) {
objects[i].tagged = 0;
objects[i].filled = 0;
- objects[i].delta_child = NULL;
- objects[i].delta_sibling = NULL;
+ SET_DELTA_CHILD(&objects[i], NULL);
+ SET_DELTA_SIBLING(&objects[i], NULL);
}
/*
@@ -672,11 +678,11 @@ static struct object_entry **compute_write_order(void)
*/
for (i = to_pack.nr_objects; i > 0;) {
struct object_entry *e = &objects[--i];
- if (!e->delta)
+ if (!DELTA(e))
continue;
/* Mark me as the first child */
- e->delta_sibling = e->delta->delta_child;
- e->delta->delta_child = e;
+ e->delta_sibling_idx = DELTA(e)->delta_child_idx;
+ SET_DELTA_CHILD(DELTA(e), e);
}
/*
@@ -1498,10 +1504,10 @@ static void check_object(struct object_entry *entry)
* circular deltas.
*/
oe_set_type(entry, entry->in_pack_type);
- entry->delta = base_entry;
+ SET_DELTA(entry, base_entry);
entry->delta_size = entry->size;
- entry->delta_sibling = base_entry->delta_child;
- base_entry->delta_child = entry;
+ entry->delta_sibling_idx = base_entry->delta_child_idx;
+ SET_DELTA_CHILD(base_entry, entry);
unuse_pack(&w_curs);
return;
}
@@ -1572,17 +1578,19 @@ static int pack_offset_sort(const void *_a, const void *_b)
*/
static void drop_reused_delta(struct object_entry *entry)
{
- struct object_entry **p = &entry->delta->delta_child;
+ unsigned *idx = &to_pack.objects[entry->delta_idx - 1].delta_child_idx;
struct object_info oi = OBJECT_INFO_INIT;
enum object_type type;
- while (*p) {
- if (*p == entry)
- *p = (*p)->delta_sibling;
+ while (*idx) {
+ struct object_entry *oe = &to_pack.objects[*idx - 1];
+
+ if (oe == entry)
+ *idx = oe->delta_sibling_idx;
else
- p = &(*p)->delta_sibling;
+ idx = &oe->delta_sibling_idx;
}
- entry->delta = NULL;
+ SET_DELTA(entry, NULL);
entry->depth = 0;
oi.sizep = &entry->size;
@@ -1622,7 +1630,7 @@ static void break_delta_chains(struct object_entry *entry)
for (cur = entry, total_depth = 0;
cur;
- cur = cur->delta, total_depth++) {
+ cur = DELTA(cur), total_depth++) {
if (cur->dfs_state == DFS_DONE) {
/*
* We've already seen this object and know it isn't
@@ -1647,7 +1655,7 @@ static void break_delta_chains(struct object_entry *entry)
* it's not a delta, we're done traversing, but we'll mark it
* done to save time on future traversals.
*/
- if (!cur->delta) {
+ if (!DELTA(cur)) {
cur->dfs_state = DFS_DONE;
break;
}
@@ -1670,7 +1678,7 @@ static void break_delta_chains(struct object_entry *entry)
* We keep all commits in the chain that we examined.
*/
cur->dfs_state = DFS_ACTIVE;
- if (cur->delta->dfs_state == DFS_ACTIVE) {
+ if (DELTA(cur)->dfs_state == DFS_ACTIVE) {
drop_reused_delta(cur);
cur->dfs_state = DFS_DONE;
break;
@@ -1685,7 +1693,7 @@ static void break_delta_chains(struct object_entry *entry)
* an extra "next" pointer to keep going after we reset cur->delta.
*/
for (cur = entry; cur; cur = next) {
- next = cur->delta;
+ next = DELTA(cur);
/*
* We should have a chain of zero or more ACTIVE states down to
@@ -1870,7 +1878,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
/* Now some size filtering heuristics. */
trg_size = trg_entry->size;
- if (!trg_entry->delta) {
+ if (!DELTA(trg_entry)) {
max_size = trg_size/2 - 20;
ref_depth = 1;
} else {
@@ -1946,7 +1954,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
if (!delta_buf)
return 0;
- if (trg_entry->delta) {
+ if (DELTA(trg_entry)) {
/* Prefer only shallower same-sized deltas. */
if (delta_size == trg_entry->delta_size &&
src->depth + 1 >= trg->depth) {
@@ -1975,7 +1983,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
free(delta_buf);
}
- trg_entry->delta = src_entry;
+ SET_DELTA(trg_entry, src_entry);
trg_entry->delta_size = delta_size;
trg->depth = src->depth + 1;
@@ -1984,13 +1992,13 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
{
- struct object_entry *child = me->delta_child;
+ struct object_entry *child = DELTA_CHILD(me);
unsigned int m = n;
while (child) {
unsigned int c = check_delta_limit(child, n + 1);
if (m < c)
m = c;
- child = child->delta_sibling;
+ child = DELTA_SIBLING(child);
}
return m;
}
@@ -2059,7 +2067,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
* otherwise they would become too deep.
*/
max_depth = depth;
- if (entry->delta_child) {
+ if (DELTA_CHILD(entry)) {
max_depth -= check_delta_limit(entry, 0);
if (max_depth <= 0)
goto next;
@@ -2109,7 +2117,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
* depth, leaving it in the window is pointless. we
* should evict it first.
*/
- if (entry->delta && max_depth <= n->depth)
+ if (DELTA(entry) && max_depth <= n->depth)
continue;
/*
@@ -2117,7 +2125,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
* currently deltified object, to keep it longer. It will
* be the first base object to be attempted next.
*/
- if (entry->delta) {
+ if (DELTA(entry)) {
struct unpacked swap = array[best_base];
int dist = (window + idx - best_base) % window;
int dst = best_base;
@@ -2438,7 +2446,7 @@ static void prepare_pack(int window, int depth)
for (i = 0; i < to_pack.nr_objects; i++) {
struct object_entry *entry = to_pack.objects + i;
- if (entry->delta)
+ if (DELTA(entry))
/* This happens if we decided to reuse existing
* delta from a pack. "reuse_delta &&" is implied.
*/
diff --git a/pack-objects.h b/pack-objects.h
index 9bcb5946e5..7f32de2a35 100644
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -71,11 +71,11 @@ struct object_entry {
unsigned long size; /* uncompressed size */
unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
off_t in_pack_offset;
- struct object_entry *delta; /* delta base object */
- struct object_entry *delta_child; /* deltified objects who bases me */
- struct object_entry *delta_sibling; /* other deltified objects who
- * uses the same base as me
- */
+ uint32_t delta_idx; /* delta base object */
+ uint32_t delta_child_idx; /* deltified objects who bases me */
+ uint32_t delta_sibling_idx; /* other deltified objects who
+ * uses the same base as me
+ */
void *delta_data; /* cached delta (uncompressed) */
unsigned long delta_size; /* delta data size (uncompressed) */
unsigned long z_delta_size; /* delta data size (compressed) */
@@ -199,4 +199,61 @@ static inline void oe_set_in_pack(struct object_entry *e,
}
+static inline struct object_entry *oe_delta(
+ const struct packing_data *pack,
+ const struct object_entry *e)
+{
+ if (e->delta_idx)
+ return &pack->objects[e->delta_idx - 1];
+ return NULL;
+}
+
+static inline void oe_set_delta(struct packing_data *pack,
+ struct object_entry *e,
+ struct object_entry *delta)
+{
+ if (delta)
+ e->delta_idx = (delta - pack->objects) + 1;
+ else
+ e->delta_idx = 0;
+}
+
+static inline struct object_entry *oe_delta_child(
+ const struct packing_data *pack,
+ const struct object_entry *e)
+{
+ if (e->delta_child_idx)
+ return &pack->objects[e->delta_child_idx - 1];
+ return NULL;
+}
+
+static inline void oe_set_delta_child(struct packing_data *pack,
+ struct object_entry *e,
+ struct object_entry *delta)
+{
+ if (delta)
+ e->delta_child_idx = (delta - pack->objects) + 1;
+ else
+ e->delta_child_idx = 0;
+}
+
+static inline struct object_entry *oe_delta_sibling(
+ const struct packing_data *pack,
+ const struct object_entry *e)
+{
+ if (e->delta_sibling_idx)
+ return &pack->objects[e->delta_sibling_idx - 1];
+ return NULL;
+}
+
+static inline void oe_set_delta_sibling(struct packing_data *pack,
+ struct object_entry *e,
+ struct object_entry *delta)
+{
+ if (delta)
+ e->delta_sibling_idx = (delta - pack->objects) + 1;
+ else
+ e->delta_sibling_idx = 0;
+}
+
#endif
--
2.16.2.903.gd04caf5039
