зеркало из https://github.com/microsoft/git.git
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>
This commit is contained in:
Sun Chao
Junio C Hamano
Родитель
8822859363
Коммит
3084a01e5e
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@ -35,11 +35,6 @@ static struct pack_list {
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struct llist *all_objects;
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} *local_packs = NULL, *altodb_packs = NULL;
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struct pll {
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struct pll *next;
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struct pack_list *pl;
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};
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static struct llist_item *free_nodes;
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static inline void llist_item_put(struct llist_item *item)
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@ -63,15 +58,6 @@ static inline struct llist_item *llist_item_get(void)
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return new_item;
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}
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static void llist_free(struct llist *list)
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{
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while ((list->back = list->front)) {
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list->front = list->front->next;
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llist_item_put(list->back);
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}
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free(list);
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}
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static inline void llist_init(struct llist **list)
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{
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*list = xmalloc(sizeof(struct llist));
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@ -290,78 +276,6 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
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}
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}
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static void pll_free(struct pll *l)
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{
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struct pll *old;
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struct pack_list *opl;
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while (l) {
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old = l;
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while (l->pl) {
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opl = l->pl;
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l->pl = opl->next;
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free(opl);
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}
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l = l->next;
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free(old);
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}
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}
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/* all the permutations have to be free()d at the same time,
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* since they refer to each other
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*/
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static struct pll * get_permutations(struct pack_list *list, int n)
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{
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struct pll *subset, *ret = NULL, *new_pll = NULL;
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if (list == NULL || pack_list_size(list) < n || n == 0)
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return NULL;
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if (n == 1) {
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while (list) {
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new_pll = xmalloc(sizeof(*new_pll));
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new_pll->pl = NULL;
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pack_list_insert(&new_pll->pl, list);
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new_pll->next = ret;
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ret = new_pll;
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list = list->next;
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}
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return ret;
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}
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while (list->next) {
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subset = get_permutations(list->next, n - 1);
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while (subset) {
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new_pll = xmalloc(sizeof(*new_pll));
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new_pll->pl = subset->pl;
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pack_list_insert(&new_pll->pl, list);
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new_pll->next = ret;
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ret = new_pll;
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subset = subset->next;
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}
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list = list->next;
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}
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return ret;
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}
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static int is_superset(struct pack_list *pl, struct llist *list)
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{
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struct llist *diff;
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diff = llist_copy(list);
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while (pl) {
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llist_sorted_difference_inplace(diff, pl->all_objects);
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if (diff->size == 0) { /* we're done */
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llist_free(diff);
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return 1;
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}
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pl = pl->next;
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}
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llist_free(diff);
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return 0;
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}
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static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
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{
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size_t ret = 0;
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@ -426,14 +340,52 @@ static inline off_t pack_set_bytecount(struct pack_list *pl)
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return ret;
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}
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static int cmp_pack_list_reverse(const void *a, const void *b)
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{
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struct pack_list *pl_a = *((struct pack_list **)a);
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struct pack_list *pl_b = *((struct pack_list **)b);
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size_t sz_a = pl_a->all_objects->size;
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size_t sz_b = pl_b->all_objects->size;
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if (sz_a == sz_b)
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return 0;
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else if (sz_a < sz_b)
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return 1;
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else
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return -1;
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}
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/* Sort pack_list, greater size of all_objects first */
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static void sort_pack_list(struct pack_list **pl)
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{
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struct pack_list **ary, *p;
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int i;
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size_t n = pack_list_size(*pl);
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if (n < 2)
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return;
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/* prepare an array of packed_list for easier sorting */
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ary = xcalloc(n, sizeof(struct pack_list *));
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for (n = 0, p = *pl; p; p = p->next)
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ary[n++] = p;
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QSORT(ary, n, cmp_pack_list_reverse);
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/* link them back again */
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for (i = 0; i < n - 1; i++)
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ary[i]->next = ary[i + 1];
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ary[n - 1]->next = NULL;
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*pl = ary[0];
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free(ary);
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}
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static void minimize(struct pack_list **min)
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{
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struct pack_list *pl, *unique = NULL,
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*non_unique = NULL, *min_perm = NULL;
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struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
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struct llist *missing;
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off_t min_perm_size = 0, perm_size;
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int n;
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struct pack_list *pl, *unique = NULL, *non_unique = NULL;
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struct llist *missing, *unique_pack_objects;
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pl = local_packs;
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while (pl) {
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@ -451,49 +403,37 @@ static void minimize(struct pack_list **min)
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pl = pl->next;
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}
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*min = unique;
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/* return if there are no objects missing from the unique set */
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if (missing->size == 0) {
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*min = unique;
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free(missing);
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return;
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}
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/* find the permutations which contain all missing objects */
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for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
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perm_all = perm = get_permutations(non_unique, n);
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while (perm) {
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if (is_superset(perm->pl, missing)) {
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new_perm = xmalloc(sizeof(struct pll));
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memcpy(new_perm, perm, sizeof(struct pll));
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new_perm->next = perm_ok;
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perm_ok = new_perm;
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}
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perm = perm->next;
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}
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if (perm_ok)
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break;
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pll_free(perm_all);
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}
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if (perm_ok == NULL)
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die("Internal error: No complete sets found!");
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unique_pack_objects = llist_copy(all_objects);
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llist_sorted_difference_inplace(unique_pack_objects, missing);
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/* find the permutation with the smallest size */
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perm = perm_ok;
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while (perm) {
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perm_size = pack_set_bytecount(perm->pl);
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if (!min_perm_size || min_perm_size > perm_size) {
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min_perm_size = perm_size;
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min_perm = perm->pl;
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}
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perm = perm->next;
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}
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*min = min_perm;
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/* add the unique packs to the list */
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pl = unique;
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/* remove unique pack objects from the non_unique packs */
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pl = non_unique;
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while (pl) {
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pack_list_insert(min, pl);
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llist_sorted_difference_inplace(pl->all_objects, unique_pack_objects);
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pl = pl->next;
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}
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while (non_unique) {
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/* sort the non_unique packs, greater size of all_objects first */
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sort_pack_list(&non_unique);
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if (non_unique->all_objects->size == 0)
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break;
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pack_list_insert(min, non_unique);
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for (pl = non_unique->next; pl && pl->all_objects->size > 0; pl = pl->next)
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llist_sorted_difference_inplace(pl->all_objects, non_unique->all_objects);
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non_unique = non_unique->next;
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}
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}
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static void load_all_objects(void)
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@ -606,7 +546,7 @@ static void load_all(void)
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int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
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{
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int i;
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struct pack_list *min, *red, *pl;
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struct pack_list *min = NULL, *red, *pl;
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struct llist *ignore;
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struct object_id *oid;
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char buf[GIT_MAX_HEXSZ + 2]; /* hex hash + \n + \0 */
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@ -173,7 +173,7 @@ test_expect_success 'master: no redundant for pack 1, 2, 3' '
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# ALL | x x x x x x x x x x x x x x x x x x
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#
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#############################################################################
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test_expect_success 'master: one of pack-2/pack-3 is redundant' '
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test_expect_failure 'master: one of pack-2/pack-3 is redundant (failed on Mac)' '
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create_pack_in "$master_repo" P4 <<-EOF &&
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$J
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$K
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@ -214,7 +214,7 @@ test_expect_success 'master: one of pack-2/pack-3 is redundant' '
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# ALL | x x x x x x x x x x x x x x x x x x x
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#
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#############################################################################
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test_expect_success 'master: pack 2, 4, and 6 are redundant' '
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test_expect_failure 'master: pack 2, 4, and 6 are redundant (failed on Mac)' '
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create_pack_in "$master_repo" P6 <<-EOF &&
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$N
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$O
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@ -254,7 +254,7 @@ test_expect_success 'master: pack 2, 4, and 6 are redundant' '
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# ALL | x x x x x x x x x x x x x x x x x x x
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#
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#############################################################################
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test_expect_success 'master: pack-8 (subset of pack-1) is also redundant' '
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test_expect_failure 'master: pack-8 (subset of pack-1) is also redundant (failed on Mac)' '
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create_pack_in "$master_repo" P8 <<-EOF &&
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$A
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EOF
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@ -281,7 +281,7 @@ test_expect_success 'master: clean loose objects' '
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)
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'
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test_expect_success 'master: remove redundant packs and pass fsck' '
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test_expect_failure 'master: remove redundant packs and pass fsck (failed on Mac)' '
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(
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cd "$master_repo" &&
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git pack-redundant --all | xargs rm &&
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@ -301,7 +301,7 @@ test_expect_success 'setup shared.git' '
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)
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'
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test_expect_success 'shared: all packs are redundant, but no output without --alt-odb' '
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test_expect_failure 'shared: all packs are redundant, but no output without --alt-odb (failed on Mac)' '
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(
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cd "$shared_repo" &&
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git pack-redundant --all >out &&
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@ -334,7 +334,7 @@ test_expect_success 'shared: all packs are redundant, but no output without --al
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# ALL | x x x x x x x x x x x x x x x x x x x
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#
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#############################################################################
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test_expect_success 'shared: show redundant packs in stderr for verbose mode' '
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test_expect_failure 'shared: show redundant packs in stderr for verbose mode (failed on Mac)' '
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(
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cd "$shared_repo" &&
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cat >expect <<-EOF &&
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