mirror of https://github.com/git/git.git
pack-objects: refer to delta objects by index instead of pointer
These delta pointers always point to elements in the objects[] array
in packing_data struct. We can only hold maximum 4G of those objects
because the array size in 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@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nguyễn Thái Ngọc Duy
Junio C Hamano
parent
43fa44fa3b
commit
898eba5e63
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@ -32,6 +32,12 @@
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#include "object-store.h"
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#define IN_PACK(obj) oe_in_pack(&to_pack, obj)
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#define DELTA(obj) oe_delta(&to_pack, obj)
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#define DELTA_CHILD(obj) oe_delta_child(&to_pack, obj)
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#define DELTA_SIBLING(obj) oe_delta_sibling(&to_pack, obj)
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#define SET_DELTA(obj, val) oe_set_delta(&to_pack, obj, val)
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#define SET_DELTA_CHILD(obj, val) oe_set_delta_child(&to_pack, obj, val)
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#define SET_DELTA_SIBLING(obj, val) oe_set_delta_sibling(&to_pack, obj, val)
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static const char *pack_usage[] = {
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N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
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@ -129,10 +135,11 @@ static void *get_delta(struct object_entry *entry)
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buf = read_object_file(&entry->idx.oid, &type, &size);
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if (!buf)
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die("unable to read %s", oid_to_hex(&entry->idx.oid));
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base_buf = read_object_file(&entry->delta->idx.oid, &type, &base_size);
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base_buf = read_object_file(&DELTA(entry)->idx.oid, &type,
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&base_size);
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if (!base_buf)
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die("unable to read %s",
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oid_to_hex(&entry->delta->idx.oid));
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oid_to_hex(&DELTA(entry)->idx.oid));
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delta_buf = diff_delta(base_buf, base_size,
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buf, size, &delta_size, 0);
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if (!delta_buf || delta_size != entry->delta_size)
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@ -288,12 +295,12 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
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size = entry->delta_size;
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buf = entry->delta_data;
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entry->delta_data = NULL;
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type = (allow_ofs_delta && entry->delta->idx.offset) ?
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type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
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OBJ_OFS_DELTA : OBJ_REF_DELTA;
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} else {
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buf = get_delta(entry);
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size = entry->delta_size;
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type = (allow_ofs_delta && entry->delta->idx.offset) ?
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type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
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OBJ_OFS_DELTA : OBJ_REF_DELTA;
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}
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@ -317,7 +324,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
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* encoding of the relative offset for the delta
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* base from this object's position in the pack.
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*/
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off_t ofs = entry->idx.offset - entry->delta->idx.offset;
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off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
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unsigned pos = sizeof(dheader) - 1;
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dheader[pos] = ofs & 127;
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while (ofs >>= 7)
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@ -343,7 +350,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
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return 0;
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}
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hashwrite(f, header, hdrlen);
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hashwrite(f, entry->delta->idx.oid.hash, 20);
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hashwrite(f, DELTA(entry)->idx.oid.hash, 20);
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hdrlen += 20;
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} else {
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if (limit && hdrlen + datalen + 20 >= limit) {
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@ -379,8 +386,8 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
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dheader[MAX_PACK_OBJECT_HEADER];
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unsigned hdrlen;
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if (entry->delta)
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type = (allow_ofs_delta && entry->delta->idx.offset) ?
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if (DELTA(entry))
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type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
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OBJ_OFS_DELTA : OBJ_REF_DELTA;
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hdrlen = encode_in_pack_object_header(header, sizeof(header),
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type, entry->size);
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@ -408,7 +415,7 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
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}
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if (type == OBJ_OFS_DELTA) {
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off_t ofs = entry->idx.offset - entry->delta->idx.offset;
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off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
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unsigned pos = sizeof(dheader) - 1;
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dheader[pos] = ofs & 127;
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while (ofs >>= 7)
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@ -427,7 +434,7 @@ static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
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return 0;
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}
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hashwrite(f, header, hdrlen);
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hashwrite(f, entry->delta->idx.oid.hash, 20);
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hashwrite(f, DELTA(entry)->idx.oid.hash, 20);
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hdrlen += 20;
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reused_delta++;
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} else {
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@ -467,13 +474,13 @@ static off_t write_object(struct hashfile *f,
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else
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limit = pack_size_limit - write_offset;
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if (!entry->delta)
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if (!DELTA(entry))
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usable_delta = 0; /* no delta */
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else if (!pack_size_limit)
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usable_delta = 1; /* unlimited packfile */
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else if (entry->delta->idx.offset == (off_t)-1)
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else if (DELTA(entry)->idx.offset == (off_t)-1)
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usable_delta = 0; /* base was written to another pack */
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else if (entry->delta->idx.offset)
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else if (DELTA(entry)->idx.offset)
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usable_delta = 1; /* base already exists in this pack */
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else
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usable_delta = 0; /* base could end up in another pack */
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@ -489,7 +496,7 @@ static off_t write_object(struct hashfile *f,
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/* ... but pack split may override that */
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else if (oe_type(entry) != entry->in_pack_type)
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to_reuse = 0; /* pack has delta which is unusable */
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else if (entry->delta)
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else if (DELTA(entry))
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to_reuse = 0; /* we want to pack afresh */
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else
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to_reuse = 1; /* we have it in-pack undeltified,
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@ -541,12 +548,12 @@ static enum write_one_status write_one(struct hashfile *f,
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}
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/* if we are deltified, write out base object first. */
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if (e->delta) {
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if (DELTA(e)) {
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e->idx.offset = 1; /* now recurse */
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switch (write_one(f, e->delta, offset)) {
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switch (write_one(f, DELTA(e), offset)) {
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case WRITE_ONE_RECURSIVE:
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/* we cannot depend on this one */
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e->delta = NULL;
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SET_DELTA(e, NULL);
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break;
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default:
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break;
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@ -608,34 +615,34 @@ static void add_descendants_to_write_order(struct object_entry **wo,
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/* add this node... */
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add_to_write_order(wo, endp, e);
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/* all its siblings... */
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for (s = e->delta_sibling; s; s = s->delta_sibling) {
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for (s = DELTA_SIBLING(e); s; s = DELTA_SIBLING(s)) {
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add_to_write_order(wo, endp, s);
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}
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}
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/* drop down a level to add left subtree nodes if possible */
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if (e->delta_child) {
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if (DELTA_CHILD(e)) {
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add_to_order = 1;
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e = e->delta_child;
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e = DELTA_CHILD(e);
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} else {
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add_to_order = 0;
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/* our sibling might have some children, it is next */
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if (e->delta_sibling) {
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e = e->delta_sibling;
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if (DELTA_SIBLING(e)) {
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e = DELTA_SIBLING(e);
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continue;
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}
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/* go back to our parent node */
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e = e->delta;
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while (e && !e->delta_sibling) {
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e = DELTA(e);
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while (e && !DELTA_SIBLING(e)) {
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/* we're on the right side of a subtree, keep
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* going up until we can go right again */
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e = e->delta;
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e = DELTA(e);
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}
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if (!e) {
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/* done- we hit our original root node */
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return;
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}
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/* pass it off to sibling at this level */
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e = e->delta_sibling;
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e = DELTA_SIBLING(e);
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}
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};
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}
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@ -646,7 +653,7 @@ static void add_family_to_write_order(struct object_entry **wo,
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{
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struct object_entry *root;
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for (root = e; root->delta; root = root->delta)
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for (root = e; DELTA(root); root = DELTA(root))
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; /* nothing */
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add_descendants_to_write_order(wo, endp, root);
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}
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@ -661,8 +668,8 @@ static struct object_entry **compute_write_order(void)
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for (i = 0; i < to_pack.nr_objects; i++) {
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objects[i].tagged = 0;
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objects[i].filled = 0;
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objects[i].delta_child = NULL;
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objects[i].delta_sibling = NULL;
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SET_DELTA_CHILD(&objects[i], NULL);
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SET_DELTA_SIBLING(&objects[i], NULL);
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}
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/*
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@ -672,11 +679,11 @@ static struct object_entry **compute_write_order(void)
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*/
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for (i = to_pack.nr_objects; i > 0;) {
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struct object_entry *e = &objects[--i];
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if (!e->delta)
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if (!DELTA(e))
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continue;
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/* Mark me as the first child */
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e->delta_sibling = e->delta->delta_child;
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e->delta->delta_child = e;
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e->delta_sibling_idx = DELTA(e)->delta_child_idx;
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SET_DELTA_CHILD(DELTA(e), e);
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}
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/*
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@ -1493,10 +1500,10 @@ static void check_object(struct object_entry *entry)
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* circular deltas.
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*/
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oe_set_type(entry, entry->in_pack_type);
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entry->delta = base_entry;
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SET_DELTA(entry, base_entry);
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entry->delta_size = entry->size;
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entry->delta_sibling = base_entry->delta_child;
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base_entry->delta_child = entry;
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entry->delta_sibling_idx = base_entry->delta_child_idx;
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SET_DELTA_CHILD(base_entry, entry);
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unuse_pack(&w_curs);
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return;
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}
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@ -1567,17 +1574,19 @@ static int pack_offset_sort(const void *_a, const void *_b)
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*/
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static void drop_reused_delta(struct object_entry *entry)
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{
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struct object_entry **p = &entry->delta->delta_child;
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unsigned *idx = &to_pack.objects[entry->delta_idx - 1].delta_child_idx;
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struct object_info oi = OBJECT_INFO_INIT;
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enum object_type type;
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while (*p) {
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if (*p == entry)
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*p = (*p)->delta_sibling;
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while (*idx) {
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struct object_entry *oe = &to_pack.objects[*idx - 1];
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if (oe == entry)
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*idx = oe->delta_sibling_idx;
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else
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p = &(*p)->delta_sibling;
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idx = &oe->delta_sibling_idx;
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}
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entry->delta = NULL;
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SET_DELTA(entry, NULL);
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entry->depth = 0;
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oi.sizep = &entry->size;
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@ -1617,7 +1626,7 @@ static void break_delta_chains(struct object_entry *entry)
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for (cur = entry, total_depth = 0;
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cur;
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cur = cur->delta, total_depth++) {
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cur = DELTA(cur), total_depth++) {
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if (cur->dfs_state == DFS_DONE) {
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/*
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* We've already seen this object and know it isn't
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@ -1642,7 +1651,7 @@ static void break_delta_chains(struct object_entry *entry)
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* it's not a delta, we're done traversing, but we'll mark it
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* done to save time on future traversals.
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*/
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if (!cur->delta) {
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if (!DELTA(cur)) {
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cur->dfs_state = DFS_DONE;
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break;
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}
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@ -1665,7 +1674,7 @@ static void break_delta_chains(struct object_entry *entry)
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* We keep all commits in the chain that we examined.
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*/
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cur->dfs_state = DFS_ACTIVE;
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if (cur->delta->dfs_state == DFS_ACTIVE) {
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if (DELTA(cur)->dfs_state == DFS_ACTIVE) {
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drop_reused_delta(cur);
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cur->dfs_state = DFS_DONE;
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break;
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@ -1680,7 +1689,7 @@ static void break_delta_chains(struct object_entry *entry)
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* an extra "next" pointer to keep going after we reset cur->delta.
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*/
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for (cur = entry; cur; cur = next) {
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next = cur->delta;
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next = DELTA(cur);
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/*
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* We should have a chain of zero or more ACTIVE states down to
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@ -1865,7 +1874,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
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/* Now some size filtering heuristics. */
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trg_size = trg_entry->size;
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if (!trg_entry->delta) {
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if (!DELTA(trg_entry)) {
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max_size = trg_size/2 - 20;
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ref_depth = 1;
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} else {
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@ -1939,7 +1948,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
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if (!delta_buf)
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return 0;
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if (trg_entry->delta) {
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if (DELTA(trg_entry)) {
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/* Prefer only shallower same-sized deltas. */
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if (delta_size == trg_entry->delta_size &&
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src->depth + 1 >= trg->depth) {
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@ -1968,7 +1977,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
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free(delta_buf);
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}
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trg_entry->delta = src_entry;
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SET_DELTA(trg_entry, src_entry);
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trg_entry->delta_size = delta_size;
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trg->depth = src->depth + 1;
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@ -1977,13 +1986,13 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
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static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
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{
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struct object_entry *child = me->delta_child;
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struct object_entry *child = DELTA_CHILD(me);
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unsigned int m = n;
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while (child) {
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unsigned int c = check_delta_limit(child, n + 1);
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if (m < c)
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m = c;
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child = child->delta_sibling;
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child = DELTA_SIBLING(child);
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}
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return m;
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}
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@ -2052,7 +2061,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
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* otherwise they would become too deep.
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*/
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max_depth = depth;
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if (entry->delta_child) {
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if (DELTA_CHILD(entry)) {
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max_depth -= check_delta_limit(entry, 0);
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if (max_depth <= 0)
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goto next;
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@ -2102,7 +2111,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
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* depth, leaving it in the window is pointless. we
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* should evict it first.
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*/
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if (entry->delta && max_depth <= n->depth)
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if (DELTA(entry) && max_depth <= n->depth)
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continue;
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/*
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@ -2110,7 +2119,7 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
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* currently deltified object, to keep it longer. It will
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* be the first base object to be attempted next.
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*/
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if (entry->delta) {
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if (DELTA(entry)) {
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struct unpacked swap = array[best_base];
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int dist = (window + idx - best_base) % window;
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int dst = best_base;
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@ -2431,7 +2440,7 @@ static void prepare_pack(int window, int depth)
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for (i = 0; i < to_pack.nr_objects; i++) {
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struct object_entry *entry = to_pack.objects + i;
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if (entry->delta)
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if (DELTA(entry))
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/* This happens if we decided to reuse existing
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* delta from a pack. "reuse_delta &&" is implied.
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*/
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@ -70,11 +70,11 @@ struct object_entry {
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unsigned long size; /* uncompressed size */
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unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
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off_t in_pack_offset;
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struct object_entry *delta; /* delta base object */
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struct object_entry *delta_child; /* deltified objects who bases me */
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struct object_entry *delta_sibling; /* other deltified objects who
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* uses the same base as me
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*/
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uint32_t delta_idx; /* delta base object */
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uint32_t delta_child_idx; /* deltified objects who bases me */
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uint32_t delta_sibling_idx; /* other deltified objects who
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* uses the same base as me
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*/
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void *delta_data; /* cached delta (uncompressed) */
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unsigned long delta_size; /* delta data size (uncompressed) */
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unsigned long z_delta_size; /* delta data size (compressed) */
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@ -194,4 +194,61 @@ static inline void oe_set_in_pack(struct packing_data *pack,
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pack->in_pack[e - pack->objects] = p;
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}
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||||
|
||||
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
|
||||
|
|
|
|||
Loading…
Reference in New Issue