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git object hash cleanups 

This IMNSHO cleans up the object hashing.

The hash expansion is separated out into a function of its own, the hash
array (and size) names are made more obvious, and the code is generally
made to look a bit more like the object-ref hashing.

It also gets rid of "find_object()" returning an index (or negative
position if no object is found), since that is made redundant by the
simplified object rehashing. The basic operation is now "lookup_object()"
which just returns the object itself.

There's an almost unmeasurable speed increase, but more importantly, I
think the end result is more readable.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Linus Torvalds 2006-06-30 11:20:33 -07:00 committed by Junio C Hamano
parent 6631c73685
commit 0556a11a0d
1 changed files with 62 additions and 53 deletions
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115
object.c
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@ -5,88 +5,97 @@
#include "commit.h"
#include "tag.h"
static struct object **objs;
static int nr_objs, obj_allocs;
static struct object **obj_hash;
static int nr_objs, obj_hash_size;
unsigned int get_max_object_index(void)
{
return obj_allocs;
return obj_hash_size;
}
struct object *get_indexed_object(unsigned int idx)
{
return objs[idx];
return obj_hash[idx];
}
const char *type_names[] = {
"none", "blob", "tree", "commit", "bad"
};
static unsigned int hash_obj(struct object *obj, unsigned int n)
{
unsigned int hash = *(unsigned int *)obj->sha1;
return hash % n;
}
static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
{
int j = hash_obj(obj, size);
while (hash[j]) {
j++;
if (j >= size)
j = 0;
}
hash[j] = obj;
}
static int hashtable_index(const unsigned char *sha1)
{
unsigned int i;
memcpy(&i, sha1, sizeof(unsigned int));
return (int)(i % obj_allocs);
}
static int find_object(const unsigned char *sha1)
{
int i;
if (!objs)
return -1;
i = hashtable_index(sha1);
while (objs[i]) {
if (memcmp(sha1, objs[i]->sha1, 20) == 0)
return i;
i++;
if (i == obj_allocs)
i = 0;
}
return -1 - i;
return (int)(i % obj_hash_size);
}
struct object *lookup_object(const unsigned char *sha1)
{
int pos = find_object(sha1);
if (pos >= 0)
return objs[pos];
return NULL;
int i;
struct object *obj;
if (!obj_hash)
return NULL;
i = hashtable_index(sha1);
while ((obj = obj_hash[i]) != NULL) {
if (!memcmp(sha1, obj->sha1, 20))
break;
i++;
if (i == obj_hash_size)
i = 0;
}
return obj;
}
static void grow_object_hash(void)
{
int i;
int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
struct object **new_hash;
new_hash = calloc(new_hash_size, sizeof(struct object *));
for (i = 0; i < obj_hash_size; i++) {
struct object *obj = obj_hash[i];
if (!obj)
continue;
insert_obj_hash(obj, new_hash, new_hash_size);
}
free(obj_hash);
obj_hash = new_hash;
obj_hash_size = new_hash_size;
}
void created_object(const unsigned char *sha1, struct object *obj)
{
int pos;
obj->parsed = 0;
memcpy(obj->sha1, sha1, 20);
obj->type = TYPE_NONE;
obj->used = 0;
obj->type = TYPE_NONE;
obj->flags = 0;
memcpy(obj->sha1, sha1, 20);
if (obj_allocs - 1 <= nr_objs * 2) {
int i, count = obj_allocs;
obj_allocs = (obj_allocs < 32 ? 32 : 2 * obj_allocs);
objs = xrealloc(objs, obj_allocs * sizeof(struct object *));
memset(objs + count, 0, (obj_allocs - count)
* sizeof(struct object *));
for (i = 0; i < obj_allocs; i++)
if (objs[i]) {
int j = find_object(objs[i]->sha1);
if (j != i) {
j = -1 - j;
objs[j] = objs[i];
objs[i] = NULL;
}
}
}
if (obj_hash_size - 1 <= nr_objs * 2)
grow_object_hash();
pos = find_object(sha1);
if (pos >= 0)
die("Inserting %s twice\n", sha1_to_hex(sha1));
pos = -pos-1;
objs[pos] = obj;
insert_obj_hash(obj, obj_hash, obj_hash_size);
nr_objs++;
}