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authorSun Chao <sunchao9@huawei.com>2019-02-02 13:30:15 (GMT)
committerJunio C Hamano <gitster@pobox.com>2019-02-04 22:18:24 (GMT)
commit3084a01e5efefc57d8f52562c82fd41799379697 (patch)
tree83e7f3d8fab5aa824a312fa0f68a332f4231c36e /builtin/pack-redundant.c
parent8822859363a86ade287c7deb07224af345a699f4 (diff)
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pack-redundant: new algorithm to find min packs
When calling `git pack-redundant --all`, if there are too many local packs and too many redundant objects within them, the too deep iteration of `get_permutations` will exhaust all the resources, and the process of `git pack-redundant` will be killed. The following script could create a repository with too many redundant packs, and running `git pack-redundant --all` in the `test.git` repo will die soon. #!/bin/sh repo="$(pwd)/test.git" work="$(pwd)/test" i=1 max=199 if test -d "$repo" || test -d "$work"; then echo >&2 "ERROR: '$repo' or '$work' already exist" exit 1 fi git init -q --bare "$repo" git --git-dir="$repo" config gc.auto 0 git --git-dir="$repo" config transfer.unpackLimit 0 git clone -q "$repo" "$work" 2>/dev/null while :; do cd "$work" echo "loop $i: $(date +%s)" >$i git add $i git commit -q -sm "loop $i" git push -q origin HEAD:master printf "\rCreate pack %4d/%d\t" $i $max if test $i -ge $max; then break; fi cd "$repo" git repack -q if test $(($i % 2)) -eq 0; then git repack -aq pack=$(ls -t $repo/objects/pack/*.pack | head -1) touch "${pack%.pack}.keep" fi i=$((i+1)) done printf "\ndone\n" To get the `min` unique pack list, we can replace the iteration in `minimize` function with a new algorithm, and this could solve this issue: 1. Get the unique and non_uniqe packs, add the unique packs to the `min` list. 2. Remove the objects of unique packs from non_unique packs, then each object left in the non_unique packs will have at least two copies. 3. Sort the non_unique packs by the objects' size, more objects first, and add the first non_unique pack to `min` list. 4. Drop the duplicated objects from other packs in the ordered non_unique pack list, and repeat step 3. Some test cases will fail on Mac OS X. Mark them and will resolve in later commit. Original PR and discussions: https://github.com/jiangxin/git/pull/25 Signed-off-by: Sun Chao <sunchao9@huawei.com> Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/pack-redundant.c')
-rw-r--r--builtin/pack-redundant.c194
1 files changed, 67 insertions, 127 deletions
diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c
index 4a06f05..d6d9a66 100644
--- a/builtin/pack-redundant.c
+++ b/builtin/pack-redundant.c
@@ -35,11 +35,6 @@ static struct pack_list {
struct llist *all_objects;
} *local_packs = NULL, *altodb_packs = NULL;
-struct pll {
- struct pll *next;
- struct pack_list *pl;
-};
-
static struct llist_item *free_nodes;
static inline void llist_item_put(struct llist_item *item)
@@ -63,15 +58,6 @@ static inline struct llist_item *llist_item_get(void)
return new_item;
}
-static void llist_free(struct llist *list)
-{
- while ((list->back = list->front)) {
- list->front = list->front->next;
- llist_item_put(list->back);
- }
- free(list);
-}
-
static inline void llist_init(struct llist **list)
{
*list = xmalloc(sizeof(struct llist));
@@ -290,78 +276,6 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
}
}
-static void pll_free(struct pll *l)
-{
- struct pll *old;
- struct pack_list *opl;
-
- while (l) {
- old = l;
- while (l->pl) {
- opl = l->pl;
- l->pl = opl->next;
- free(opl);
- }
- l = l->next;
- free(old);
- }
-}
-
-/* all the permutations have to be free()d at the same time,
- * since they refer to each other
- */
-static struct pll * get_permutations(struct pack_list *list, int n)
-{
- struct pll *subset, *ret = NULL, *new_pll = NULL;
-
- if (list == NULL || pack_list_size(list) < n || n == 0)
- return NULL;
-
- if (n == 1) {
- while (list) {
- new_pll = xmalloc(sizeof(*new_pll));
- new_pll->pl = NULL;
- pack_list_insert(&new_pll->pl, list);
- new_pll->next = ret;
- ret = new_pll;
- list = list->next;
- }
- return ret;
- }
-
- while (list->next) {
- subset = get_permutations(list->next, n - 1);
- while (subset) {
- new_pll = xmalloc(sizeof(*new_pll));
- new_pll->pl = subset->pl;
- pack_list_insert(&new_pll->pl, list);
- new_pll->next = ret;
- ret = new_pll;
- subset = subset->next;
- }
- list = list->next;
- }
- return ret;
-}
-
-static int is_superset(struct pack_list *pl, struct llist *list)
-{
- struct llist *diff;
-
- diff = llist_copy(list);
-
- while (pl) {
- llist_sorted_difference_inplace(diff, pl->all_objects);
- if (diff->size == 0) { /* we're done */
- llist_free(diff);
- return 1;
- }
- pl = pl->next;
- }
- llist_free(diff);
- return 0;
-}
-
static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
{
size_t ret = 0;
@@ -426,14 +340,52 @@ static inline off_t pack_set_bytecount(struct pack_list *pl)
return ret;
}
+static int cmp_pack_list_reverse(const void *a, const void *b)
+{
+ struct pack_list *pl_a = *((struct pack_list **)a);
+ struct pack_list *pl_b = *((struct pack_list **)b);
+ size_t sz_a = pl_a->all_objects->size;
+ size_t sz_b = pl_b->all_objects->size;
+
+ if (sz_a == sz_b)
+ return 0;
+ else if (sz_a < sz_b)
+ return 1;
+ else
+ return -1;
+}
+
+/* Sort pack_list, greater size of all_objects first */
+static void sort_pack_list(struct pack_list **pl)
+{
+ struct pack_list **ary, *p;
+ int i;
+ size_t n = pack_list_size(*pl);
+
+ if (n < 2)
+ return;
+
+ /* prepare an array of packed_list for easier sorting */
+ ary = xcalloc(n, sizeof(struct pack_list *));
+ for (n = 0, p = *pl; p; p = p->next)
+ ary[n++] = p;
+
+ QSORT(ary, n, cmp_pack_list_reverse);
+
+ /* link them back again */
+ for (i = 0; i < n - 1; i++)
+ ary[i]->next = ary[i + 1];
+ ary[n - 1]->next = NULL;
+ *pl = ary[0];
+
+ free(ary);
+}
+
+
static void minimize(struct pack_list **min)
{
- struct pack_list *pl, *unique = NULL,
- *non_unique = NULL, *min_perm = NULL;
- struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
- struct llist *missing;
- off_t min_perm_size = 0, perm_size;
- int n;
+ struct pack_list *pl, *unique = NULL, *non_unique = NULL;
+ struct llist *missing, *unique_pack_objects;
pl = local_packs;
while (pl) {
@@ -451,49 +403,37 @@ static void minimize(struct pack_list **min)
pl = pl->next;
}
+ *min = unique;
+
/* return if there are no objects missing from the unique set */
if (missing->size == 0) {
- *min = unique;
free(missing);
return;
}
- /* find the permutations which contain all missing objects */
- for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
- perm_all = perm = get_permutations(non_unique, n);
- while (perm) {
- if (is_superset(perm->pl, missing)) {
- new_perm = xmalloc(sizeof(struct pll));
- memcpy(new_perm, perm, sizeof(struct pll));
- new_perm->next = perm_ok;
- perm_ok = new_perm;
- }
- perm = perm->next;
- }
- if (perm_ok)
- break;
- pll_free(perm_all);
- }
- if (perm_ok == NULL)
- die("Internal error: No complete sets found!");
-
- /* find the permutation with the smallest size */
- perm = perm_ok;
- while (perm) {
- perm_size = pack_set_bytecount(perm->pl);
- if (!min_perm_size || min_perm_size > perm_size) {
- min_perm_size = perm_size;
- min_perm = perm->pl;
- }
- perm = perm->next;
- }
- *min = min_perm;
- /* add the unique packs to the list */
- pl = unique;
+ unique_pack_objects = llist_copy(all_objects);
+ llist_sorted_difference_inplace(unique_pack_objects, missing);
+
+ /* remove unique pack objects from the non_unique packs */
+ pl = non_unique;
while (pl) {
- pack_list_insert(min, pl);
+ llist_sorted_difference_inplace(pl->all_objects, unique_pack_objects);
pl = pl->next;
}
+
+ while (non_unique) {
+ /* sort the non_unique packs, greater size of all_objects first */
+ sort_pack_list(&non_unique);
+ if (non_unique->all_objects->size == 0)
+ break;
+
+ pack_list_insert(min, non_unique);
+
+ for (pl = non_unique->next; pl && pl->all_objects->size > 0; pl = pl->next)
+ llist_sorted_difference_inplace(pl->all_objects, non_unique->all_objects);
+
+ non_unique = non_unique->next;
+ }
}
static void load_all_objects(void)
@@ -606,7 +546,7 @@ static void load_all(void)
int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
{
int i;
- struct pack_list *min, *red, *pl;
+ struct pack_list *min = NULL, *red, *pl;
struct llist *ignore;
struct object_id *oid;
char buf[GIT_MAX_HEXSZ + 2]; /* hex hash + \n + \0 */