diff options
author | Sun Chao <sunchao9@huawei.com> | 2019-02-02 16:30:15 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2019-02-05 01:18:24 +0300 |
commit | 3084a01e5efefc57d8f52562c82fd41799379697 (patch) | |
tree | 83e7f3d8fab5aa824a312fa0f68a332f4231c36e /builtin/pack-redundant.c | |
parent | 8822859363a86ade287c7deb07224af345a699f4 (diff) |
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.c | 194 |
1 files changed, 67 insertions, 127 deletions
diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c index 4a06f057dd..d6d9a66e46 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 */ |