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git/object.c
Sergey Vlasov 4a4e6fd74f Rework object refs tracking to reduce memory usage
Store pointers to referenced objects in a variable sized array instead
of linked list.  This cuts down memory usage of utilities which use
object references; e.g., git-fsck-objects --full on the git.git
repository consumes about 2 MB of memory tracked by Massif instead of
7 MB before the change.  Object refs are still the biggest consumer of
memory (57%), but the malloc overhead for a single block instead of a
linked list is substantially smaller.

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-11-15 11:42:29 -08:00

249 lines
5.6 KiB
C

#include "object.h"
#include "blob.h"
#include "tree.h"
#include "commit.h"
#include "cache.h"
#include "tag.h"
struct object **objs;
int nr_objs;
static int obj_allocs;
int track_object_refs = 1;
static int find_object(const unsigned char *sha1)
{
int first = 0, last = nr_objs;
while (first < last) {
int next = (first + last) / 2;
struct object *obj = objs[next];
int cmp;
cmp = memcmp(sha1, obj->sha1, 20);
if (!cmp)
return next;
if (cmp < 0) {
last = next;
continue;
}
first = next+1;
}
return -first-1;
}
struct object *lookup_object(const unsigned char *sha1)
{
int pos = find_object(sha1);
if (pos >= 0)
return objs[pos];
return NULL;
}
void created_object(const unsigned char *sha1, struct object *obj)
{
int pos = find_object(sha1);
obj->parsed = 0;
memcpy(obj->sha1, sha1, 20);
obj->type = NULL;
obj->refs = NULL;
obj->used = 0;
if (pos >= 0)
die("Inserting %s twice\n", sha1_to_hex(sha1));
pos = -pos-1;
if (obj_allocs == nr_objs) {
obj_allocs = alloc_nr(obj_allocs);
objs = xrealloc(objs, obj_allocs * sizeof(struct object *));
}
/* Insert it into the right place */
memmove(objs + pos + 1, objs + pos, (nr_objs - pos) *
sizeof(struct object *));
objs[pos] = obj;
nr_objs++;
}
struct object_refs *alloc_object_refs(unsigned count)
{
struct object_refs *refs;
size_t size = sizeof(*refs) + count*sizeof(struct object *);
refs = xmalloc(size);
memset(refs, 0, size);
refs->count = count;
return refs;
}
static int compare_object_pointers(const void *a, const void *b)
{
const struct object * const *pa = a;
const struct object * const *pb = b;
return *pa - *pb;
}
void set_object_refs(struct object *obj, struct object_refs *refs)
{
unsigned int i, j;
/* Do not install empty list of references */
if (refs->count < 1) {
free(refs);
return;
}
/* Sort the list and filter out duplicates */
qsort(refs->ref, refs->count, sizeof(refs->ref[0]),
compare_object_pointers);
for (i = j = 1; i < refs->count; i++) {
if (refs->ref[i] != refs->ref[i - 1])
refs->ref[j++] = refs->ref[i];
}
if (j < refs->count) {
/* Duplicates were found - reallocate list */
size_t size = sizeof(*refs) + j*sizeof(struct object *);
refs->count = j;
refs = xrealloc(refs, size);
}
for (i = 0; i < refs->count; i++)
refs->ref[i]->used = 1;
obj->refs = refs;
}
void mark_reachable(struct object *obj, unsigned int mask)
{
if (!track_object_refs)
die("cannot do reachability with object refs turned off");
/* If we've been here already, don't bother */
if (obj->flags & mask)
return;
obj->flags |= mask;
if (obj->refs) {
const struct object_refs *refs = obj->refs;
unsigned i;
for (i = 0; i < refs->count; i++)
mark_reachable(refs->ref[i], mask);
}
}
struct object *lookup_object_type(const unsigned char *sha1, const char *type)
{
if (!type) {
return lookup_unknown_object(sha1);
} else if (!strcmp(type, blob_type)) {
return &lookup_blob(sha1)->object;
} else if (!strcmp(type, tree_type)) {
return &lookup_tree(sha1)->object;
} else if (!strcmp(type, commit_type)) {
return &lookup_commit(sha1)->object;
} else if (!strcmp(type, tag_type)) {
return &lookup_tag(sha1)->object;
} else {
error("Unknown type %s", type);
return NULL;
}
}
union any_object {
struct object object;
struct commit commit;
struct tree tree;
struct blob blob;
struct tag tag;
};
struct object *lookup_unknown_object(const unsigned char *sha1)
{
struct object *obj = lookup_object(sha1);
if (!obj) {
union any_object *ret = xmalloc(sizeof(*ret));
memset(ret, 0, sizeof(*ret));
created_object(sha1, &ret->object);
ret->object.type = NULL;
return &ret->object;
}
return obj;
}
struct object *parse_object(const unsigned char *sha1)
{
unsigned long size;
char type[20];
void *buffer = read_sha1_file(sha1, type, &size);
if (buffer) {
struct object *obj;
if (check_sha1_signature(sha1, buffer, size, type) < 0)
printf("sha1 mismatch %s\n", sha1_to_hex(sha1));
if (!strcmp(type, "blob")) {
struct blob *blob = lookup_blob(sha1);
parse_blob_buffer(blob, buffer, size);
obj = &blob->object;
} else if (!strcmp(type, "tree")) {
struct tree *tree = lookup_tree(sha1);
parse_tree_buffer(tree, buffer, size);
obj = &tree->object;
} else if (!strcmp(type, "commit")) {
struct commit *commit = lookup_commit(sha1);
parse_commit_buffer(commit, buffer, size);
if (!commit->buffer) {
commit->buffer = buffer;
buffer = NULL;
}
obj = &commit->object;
} else if (!strcmp(type, "tag")) {
struct tag *tag = lookup_tag(sha1);
parse_tag_buffer(tag, buffer, size);
obj = &tag->object;
} else {
obj = NULL;
}
free(buffer);
return obj;
}
return NULL;
}
struct object_list *object_list_insert(struct object *item,
struct object_list **list_p)
{
struct object_list *new_list = xmalloc(sizeof(struct object_list));
new_list->item = item;
new_list->next = *list_p;
*list_p = new_list;
return new_list;
}
void object_list_append(struct object *item,
struct object_list **list_p)
{
while (*list_p) {
list_p = &((*list_p)->next);
}
*list_p = xmalloc(sizeof(struct object_list));
(*list_p)->next = NULL;
(*list_p)->item = item;
}
unsigned object_list_length(struct object_list *list)
{
unsigned ret = 0;
while (list) {
list = list->next;
ret++;
}
return ret;
}
int object_list_contains(struct object_list *list, struct object *obj)
{
while (list) {
if (list->item == obj)
return 1;
list = list->next;
}
return 0;
}