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@xxxxxxxx>
---
I tried to be really careful, and this should all be good, but I'm still
embarrassed about my hash insertion bug in object-refs.c, so people should
double- and triple-check this.
diff --git a/object.c b/object.c
index 31c77ea..37277f9 100644
--- a/object.c
+++ b/object.c
@@ -5,88 +5,97 @@ #include "tree.h"
#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);
+ return (int)(i % obj_hash_size);
}
-static int find_object(const unsigned char *sha1)
+struct object *lookup_object(const unsigned char *sha1)
{
int i;
+ struct object *obj;
- if (!objs)
- return -1;
+ if (!obj_hash)
+ return NULL;
i = hashtable_index(sha1);
- while (objs[i]) {
- if (memcmp(sha1, objs[i]->sha1, 20) == 0)
- return i;
+ while ((obj = obj_hash[i]) != NULL) {
+ if (!memcmp(sha1, obj->sha1, 20))
+ break;
i++;
- if (i == obj_allocs)
+ if (i == obj_hash_size)
i = 0;
}
- return -1 - i;
+ return obj;
}
-struct object *lookup_object(const unsigned char *sha1)
+static void grow_object_hash(void)
{
- int pos = find_object(sha1);
- if (pos >= 0)
- return objs[pos];
- return NULL;
+ 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;
- }
- }
- }
-
- pos = find_object(sha1);
- if (pos >= 0)
- die("Inserting %s twice\n", sha1_to_hex(sha1));
- pos = -pos-1;
+ if (obj_hash_size - 1 <= nr_objs * 2)
+ grow_object_hash();
- objs[pos] = obj;
+ insert_obj_hash(obj, obj_hash, obj_hash_size);
nr_objs++;
}
-
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