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Remove "refs" field from "struct object"

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This shrinks "struct object" to the absolutely minimal size possible.
It now contains /only/ the object flags and the SHA1 hash name of the
object.

The "refs" field, which is really needed only for fsck, is maintained in
a separate hashed lookup-table, allowing all normal users to totally
ignore it.

This helps memory usage, although not as much as I hoped: it looks like
the allocation overhead of malloc (and the alignment constraints in
particular) means that while the structure size shrinks, the actual
allocation overhead mostly does not.

[ That said: memory usage is actually down, but not as much as it should
  be: I suspect just one of the object types actually ended up shrinking
  its effective allocation size.

  To get to the next level, we probably need specialized allocators that
  don't pad the allocation more than necessary. ]

The separation makes for some code cleanup, though, and makes the ref
tracking that fsck wants a clearly separate thing.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Linus Torvalds
2006-06-18 11:45:02 -07:00
committed by Junio C Hamano
parent 9cd625b79b
commit 3e4339e6f9
5 changed files with 149 additions and 74 deletions
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5
fsck-objects.c
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@ -64,6 +64,7 @@ static void check_connectivity(void)
/* Look up all the requirements, warn about missing objects.. */
for (i = 0; i < obj_allocs; i++) {
const struct object_refs *refs;
struct object *obj = objs[i];
if (!obj)
@ -78,8 +79,8 @@ static void check_connectivity(void)
continue;
}
if (obj->refs) {
const struct object_refs *refs = obj->refs;
refs = lookup_object_refs(obj);
if (refs) {
unsigned j;
for (j = 0; j < refs->count; j++) {
struct object *ref = refs->ref[j];