зеркало из https://github.com/microsoft/git.git
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:
Родитель
6631c73685
Коммит
0556a11a0d
115
object.c
115
object.c
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@ -5,88 +5,97 @@
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#include "commit.h"
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#include "tag.h"
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static struct object **objs;
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static int nr_objs, obj_allocs;
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static struct object **obj_hash;
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static int nr_objs, obj_hash_size;
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unsigned int get_max_object_index(void)
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{
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return obj_allocs;
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return obj_hash_size;
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}
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struct object *get_indexed_object(unsigned int idx)
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{
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return objs[idx];
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return obj_hash[idx];
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}
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const char *type_names[] = {
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"none", "blob", "tree", "commit", "bad"
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};
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static unsigned int hash_obj(struct object *obj, unsigned int n)
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{
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unsigned int hash = *(unsigned int *)obj->sha1;
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return hash % n;
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}
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static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
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{
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int j = hash_obj(obj, size);
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while (hash[j]) {
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j++;
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if (j >= size)
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j = 0;
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}
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hash[j] = obj;
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}
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static int hashtable_index(const unsigned char *sha1)
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{
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unsigned int i;
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memcpy(&i, sha1, sizeof(unsigned int));
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return (int)(i % obj_allocs);
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}
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static int find_object(const unsigned char *sha1)
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{
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int i;
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if (!objs)
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return -1;
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i = hashtable_index(sha1);
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while (objs[i]) {
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if (memcmp(sha1, objs[i]->sha1, 20) == 0)
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return i;
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i++;
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if (i == obj_allocs)
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i = 0;
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}
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return -1 - i;
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return (int)(i % obj_hash_size);
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}
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struct object *lookup_object(const unsigned char *sha1)
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{
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int pos = find_object(sha1);
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if (pos >= 0)
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return objs[pos];
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return NULL;
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int i;
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struct object *obj;
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if (!obj_hash)
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return NULL;
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i = hashtable_index(sha1);
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while ((obj = obj_hash[i]) != NULL) {
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if (!memcmp(sha1, obj->sha1, 20))
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break;
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i++;
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if (i == obj_hash_size)
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i = 0;
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}
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return obj;
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}
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static void grow_object_hash(void)
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{
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int i;
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int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
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struct object **new_hash;
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new_hash = calloc(new_hash_size, sizeof(struct object *));
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for (i = 0; i < obj_hash_size; i++) {
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struct object *obj = obj_hash[i];
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if (!obj)
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continue;
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insert_obj_hash(obj, new_hash, new_hash_size);
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}
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free(obj_hash);
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obj_hash = new_hash;
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obj_hash_size = new_hash_size;
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}
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void created_object(const unsigned char *sha1, struct object *obj)
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{
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int pos;
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obj->parsed = 0;
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memcpy(obj->sha1, sha1, 20);
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obj->type = TYPE_NONE;
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obj->used = 0;
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obj->type = TYPE_NONE;
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obj->flags = 0;
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memcpy(obj->sha1, sha1, 20);
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if (obj_allocs - 1 <= nr_objs * 2) {
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int i, count = obj_allocs;
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obj_allocs = (obj_allocs < 32 ? 32 : 2 * obj_allocs);
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objs = xrealloc(objs, obj_allocs * sizeof(struct object *));
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memset(objs + count, 0, (obj_allocs - count)
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* sizeof(struct object *));
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for (i = 0; i < obj_allocs; i++)
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if (objs[i]) {
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int j = find_object(objs[i]->sha1);
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if (j != i) {
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j = -1 - j;
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objs[j] = objs[i];
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objs[i] = NULL;
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}
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}
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}
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if (obj_hash_size - 1 <= nr_objs * 2)
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grow_object_hash();
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pos = find_object(sha1);
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if (pos >= 0)
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die("Inserting %s twice\n", sha1_to_hex(sha1));
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pos = -pos-1;
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objs[pos] = obj;
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insert_obj_hash(obj, obj_hash, obj_hash_size);
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nr_objs++;
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}
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