Add git-pack-intersect

This patch adds the program git-pack-intersect. It is
used to find redundant packs in git repositories.

Signed-off-by: Lukas Sandström <lukass@etek.chalmers.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Makefile b/Makefile
index b202be177b48cddca20e8257a5cbf5b963ffa9b9..4c646c9e84ae37f3eaa458a601ac6d0f96f07d5e 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -122,7 +122,7 @@ PROGRAMS = \
        git-unpack-objects$X git-update-index$X git-update-server-info$X \
        git-upload-pack$X git-verify-pack$X git-write-tree$X \
        git-update-ref$X git-symbolic-ref$X git-check-ref-format$X \
-       git-name-rev$X $(SIMPLE_PROGRAMS)
+       git-name-rev$X git-pack-intersect$X $(SIMPLE_PROGRAMS)
 
 # Backward compatibility -- to be removed after 1.0
 PROGRAMS += git-ssh-pull$X git-ssh-push$X

diff --git a/pack-intersect.c b/pack-intersect.c
new file mode 100644 (file)
index 0000000..2267478
--- /dev/null
+++ b/pack-intersect.c
@@ -0,0 +1,577 @@
+/*
+*
+* Copyright 2005, Lukas Sandstrom <lukass@etek.chalmers.se>
+*
+* This file is licensed under the GPL v2.
+*
+*/
+
+#include "cache.h"
+
+static const char pack_intersect_usage[] =
+"git-pack-intersect [ -v ]  < -a | <.pack filename> ...>";
+
+int all = 0, verbose = 0;
+
+struct llist_item {
+       struct llist_item *next;
+       char *sha1;
+};
+struct llist {
+       struct llist_item *front;
+       struct llist_item *back;
+       size_t size;
+} *all_objects;
+
+struct pack_list {
+       struct pack_list *next;
+       struct packed_git *pack;
+       struct llist *unique_objects;
+       struct llist *all_objects;
+} *pack_list;
+
+struct pll {
+       struct pll *next;
+       struct pack_list *pl;
+};
+
+inline void llist_free(struct llist *list)
+{
+       while((list->back = list->front)) {
+               list->front = list->front->next;
+               free(list->back);
+       }
+       free(list);
+}
+
+inline void llist_init(struct llist **list)
+{
+       *list = xmalloc(sizeof(struct llist));
+       (*list)->front = (*list)->back = NULL;
+       (*list)->size = 0;
+}
+
+struct llist * llist_copy(struct llist *list)
+{
+       struct llist *ret;
+       struct llist_item *new, *old, *prev;
+       
+       llist_init(&ret);
+
+       if ((ret->size = list->size) == 0)
+               return ret;
+
+       new = ret->front = xmalloc(sizeof(struct llist_item));
+       new->sha1 = list->front->sha1;
+
+       old = list->front->next;
+       while (old) {
+               prev = new;
+               new = xmalloc(sizeof(struct llist_item));
+               prev->next = new;
+               new->sha1 = old->sha1;
+               old = old->next;
+       }
+       new->next = NULL;
+       ret->back = new;
+       
+       return ret;
+}
+
+inline struct llist_item * llist_insert(struct llist *list,
+                                       struct llist_item *after, char *sha1)
+{
+       struct llist_item *new = xmalloc(sizeof(struct llist_item));
+       new->sha1 = sha1;
+       new->next = NULL;
+
+       if (after != NULL) {
+               new->next = after->next;
+               after->next = new;
+               if (after == list->back)
+                       list->back = new;
+       } else {/* insert in front */
+               if (list->size == 0)
+                       list->back = new;
+               else
+                       new->next = list->front;
+               list->front = new;
+       }
+       list->size++;
+       return new;
+}
+
+inline struct llist_item * llist_insert_back(struct llist *list, char *sha1)
+{
+       return llist_insert(list, list->back, sha1);
+}
+
+inline struct llist_item * llist_insert_sorted_unique(struct llist *list,
+                                       char *sha1, struct llist_item *hint)
+{
+       struct llist_item *prev = NULL, *l;
+
+       l = (hint == NULL) ? list->front : hint;
+       while (l) {
+               int cmp = memcmp(l->sha1, sha1, 20);
+               if (cmp > 0) { /* we insert before this entry */
+                       return llist_insert(list, prev, sha1);
+               }
+               if(!cmp) { /* already exists */
+                       return l;
+               }
+               prev = l;
+               l = l->next;
+       }
+       /* insert at the end */
+       return llist_insert_back(list, sha1);
+}
+
+/* computes A\B */
+struct llist * llist_sorted_difference(struct llist_item *A,
+                                      struct llist_item *B)
+{
+       struct llist *ret;
+       llist_init(&ret);
+
+       while (A != NULL && B != NULL) {
+               int cmp = memcmp(A->sha1, B->sha1, 20);
+               if (!cmp) {
+                       A = A->next;
+                       B = B->next;
+                       continue;
+               }
+               if(cmp > 0) { /* we'll never find this B */
+                       B = B->next;
+                       continue;
+               }
+               /* A has the object, B doesn't */
+               llist_insert_back(ret, A->sha1);
+               A = A->next;
+       }
+       while (A != NULL) {
+               llist_insert_back(ret, A->sha1);
+               A = A->next;
+       }
+       return ret;
+}
+
+/* returns a pointer to an item in front of sha1 */
+inline struct llist_item * llist_sorted_remove(struct llist *list, char *sha1,
+                                              struct llist_item *hint)
+{
+       struct llist_item *prev, *l;
+
+redo_from_start:
+       l = (hint == NULL) ? list->front : hint;
+       prev = NULL;
+       while (l) {
+               int cmp = memcmp(l->sha1, sha1, 20);
+               if (cmp > 0) /* not in list, since sorted */
+                       return prev;
+               if(!cmp) { /* found */
+                       if (prev == NULL) {
+                               if (hint != NULL && hint != list->front) {
+                                       /* we don't know the previous element */
+                                       hint = NULL;
+                                       goto redo_from_start;
+                               }
+                               list->front = l->next;
+                       } else
+                               prev->next = l->next;
+                       if (l == list->back)
+                               list->back = prev;
+                       free(l);
+                       list->size--;
+                       return prev;
+               }
+               prev = l;
+               l = l->next;
+       }
+       return prev;
+}
+
+inline struct pack_list * pack_list_insert(struct pack_list **pl,
+                                          struct pack_list *entry)
+{
+       struct pack_list *p = xmalloc(sizeof(struct pack_list));
+       memcpy(p, entry, sizeof(struct pack_list));
+       p->next = *pl;
+       *pl = p;
+       return p;
+}
+
+struct pack_list * pack_list_difference(struct pack_list *A,
+                                       struct pack_list *B)
+{
+       struct pack_list *ret, *pl;
+
+       if (A == NULL)
+               return NULL;
+
+       pl = B;
+       while (pl != NULL) {
+               if (A->pack == pl->pack)
+                       return pack_list_difference(A->next, B);
+               pl = pl->next;
+       }
+       ret = xmalloc(sizeof(struct pack_list));
+       memcpy(ret, A, sizeof(struct pack_list));
+       ret->next = pack_list_difference(A->next, B);
+       return ret;
+}
+
+void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
+{
+       int p1_off, p2_off;
+       void *p1_base, *p2_base;
+       struct llist_item *p1_hint = NULL, *p2_hint = NULL;
+       
+       p1_off = p2_off = 256 * 4 + 4;
+       p1_base = (void *)p1->pack->index_base;
+       p2_base = (void *)p2->pack->index_base;
+
+       while (p1_off <= p1->pack->index_size - 3 * 20 &&
+              p2_off <= p2->pack->index_size - 3 * 20)
+       {
+               int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
+               /* cmp ~ p1 - p2 */
+               if (cmp == 0) {
+                       p1_hint = llist_sorted_remove(p1->unique_objects,
+                                       p1_base + p1_off, p1_hint);
+                       p2_hint = llist_sorted_remove(p2->unique_objects,
+                                       p1_base + p1_off, p2_hint);
+                       p1_off+=24;
+                       p2_off+=24;
+                       continue;
+               }
+               if (cmp < 0) { /* p1 has the object, p2 doesn't */
+                       p1_off+=24;
+               } else { /* p2 has the object, p1 doesn't */
+                       p2_off+=24;
+               }
+       }
+}
+
+/* all the permutations have to be free()d at the same time,
+ * since they refer to each other
+ */
+struct pll * get_all_permutations(struct pack_list *list)
+{
+       struct pll *subset, *pll, *new_pll = NULL; /*silence warning*/
+
+       if (list == NULL)
+               return NULL;
+
+       if (list->next == NULL) {
+               new_pll = xmalloc(sizeof(struct pll));
+               new_pll->next = NULL;
+               new_pll->pl = list;
+               return new_pll;
+       }
+
+       pll = subset = get_all_permutations(list->next);
+       while (pll) {
+               new_pll = xmalloc(sizeof(struct pll));
+               new_pll->next = pll->next;
+               pll->next = new_pll;
+
+               new_pll->pl = xmalloc(sizeof(struct pack_list));
+               memcpy(new_pll->pl, list, sizeof(struct pack_list));
+               new_pll->pl->next = pll->pl;
+
+               pll = new_pll->next;
+       }
+       /* add ourself to the end */
+       new_pll->next = xmalloc(sizeof(struct pll));
+       new_pll->next->pl = xmalloc(sizeof(struct pack_list));
+       new_pll->next->next = NULL;
+       memcpy(new_pll->next->pl, list, sizeof(struct pack_list));
+       new_pll->next->pl->next = NULL;
+
+       return subset;
+}
+
+int is_superset(struct pack_list *pl, struct llist *list)
+{
+       struct llist *diff, *old;
+
+       diff = llist_copy(list);
+
+       while (pl) {
+               old = diff;
+               diff = llist_sorted_difference(diff->front,
+                                              pl->all_objects->front);
+               llist_free(old);
+               if (diff->size == 0) { /* we're done */
+                       llist_free(diff);
+                       return 1;
+               }
+               pl = pl->next;
+       }
+       llist_free(diff);
+       return 0;
+}
+
+size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
+{
+       size_t ret = 0;
+       int p1_off, p2_off;
+       void *p1_base, *p2_base;
+
+       p1_off = p2_off = 256 * 4 + 4;
+       p1_base = (void *)p1->index_base;
+       p2_base = (void *)p2->index_base;
+
+       while (p1_off <= p1->index_size - 3 * 20 &&
+              p2_off <= p2->index_size - 3 * 20)
+       {
+               int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
+               /* cmp ~ p1 - p2 */
+               if (cmp == 0) {
+                       ret++;
+                       p1_off+=24;
+                       p2_off+=24;
+                       continue;
+               }
+               if (cmp < 0) { /* p1 has the object, p2 doesn't */
+                       p1_off+=24;
+               } else { /* p2 has the object, p1 doesn't */
+                       p2_off+=24;
+               }
+       }
+       return ret;
+}
+
+/* another O(n^2) function ... */
+size_t get_pack_redundancy(struct pack_list *pl)
+{
+       struct pack_list *subset;
+       size_t ret = 0;
+       while ((subset = pl->next)) {
+               while(subset) {
+                       ret += sizeof_union(pl->pack, subset->pack);
+                       subset = subset->next;
+               }
+               pl = pl->next;
+       }
+       return ret;
+}
+
+inline size_t pack_set_bytecount(struct pack_list *pl)
+{
+       size_t ret = 0;
+       while (pl) {
+               ret += pl->pack->pack_size;
+               ret += pl->pack->index_size;
+               pl = pl->next;
+       }
+       return ret;
+}
+
+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, *old;
+       size_t min_perm_size = (size_t)-1, perm_size;
+
+       pl = pack_list;
+       while (pl) {
+               if(pl->unique_objects->size)
+                       pack_list_insert(&unique, pl);
+               else
+                       pack_list_insert(&non_unique, pl);
+               pl = pl->next;
+       }
+       /* find out which objects are missing from the set of unique packs */
+       missing = llist_copy(all_objects);
+       pl = unique;
+       while (pl) {
+               old = missing;
+               missing = llist_sorted_difference(missing->front,
+                                                 pl->all_objects->front);
+               llist_free(old);
+               pl = pl->next;
+       }
+
+       if (missing->size == 0) {
+               *min = unique;
+               return;
+       }
+
+       /* find the permutations which contain all missing objects */
+       perm_all = perm = get_all_permutations(non_unique);
+       while (perm) {
+               if (is_superset(perm->pl, missing)) {
+                       new_perm = xmalloc(sizeof(struct pll));
+                       new_perm->pl = perm->pl;
+                       new_perm->next = perm_ok;
+                       perm_ok = new_perm;
+               }
+               perm = perm->next;
+       }
+       
+       if (perm_ok == NULL)
+               die("Internal error: No complete sets found!\n");
+
+       /* find the permutation with the smallest size */
+       perm = perm_ok;
+       while (perm) {
+               perm_size = pack_set_bytecount(perm->pl);
+               if (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;
+       while(pl) {
+               pack_list_insert(min, pl);
+               pl = pl->next;
+       }
+}
+
+void load_all_objects()
+{
+       struct pack_list *pl = pack_list;
+       struct llist_item *hint, *l;
+       int i;
+
+       llist_init(&all_objects);
+
+       while (pl) {
+               i = 0;
+               hint = NULL;
+               l = pl->all_objects->front;
+               while (l) {
+                       hint = llist_insert_sorted_unique(all_objects,
+                                                         l->sha1, hint);
+                       l = l->next;
+               }
+               pl = pl->next;
+       }
+}
+
+/* this scales like O(n^2) */
+void cmp_packs()
+{
+       struct pack_list *subset, *curr = pack_list;
+
+       while ((subset = curr)) {
+               while((subset = subset->next))
+                       cmp_two_packs(curr, subset);
+               curr = curr->next;
+       }
+}
+
+struct pack_list * add_pack(struct packed_git *p)
+{
+       struct pack_list l;
+       size_t off;
+       void *base;
+
+       l.pack = p;
+       llist_init(&l.all_objects);
+
+       off = 256 * 4 + 4;
+       base = (void *)p->index_base;
+       while (off <= p->index_size - 3 * 20) {
+               llist_insert_back(l.all_objects, base + off);
+               off+=24;
+       }
+       /* this list will be pruned in cmp_two_packs later */
+       l.unique_objects = llist_copy(l.all_objects);
+       return pack_list_insert(&pack_list, &l);
+}
+
+struct pack_list * add_pack_file(char *filename)
+{
+       struct packed_git *p = packed_git;
+
+       if (strlen(filename) < 40)
+               die("Bad pack filename: %s\n", filename);
+
+       while (p) {
+               if (strstr(p->pack_name, filename))
+                       /* this will silently ignore packs in alt-odb */
+                       return add_pack(p);
+               p = p->next;
+       }
+       die("Filename %s not found in packed_git\n", filename);
+}
+
+void load_all()
+{
+       struct packed_git *p = packed_git;
+
+       while (p) {
+               if (p->pack_local) /* ignore alt-odb for now */
+                       add_pack(p);
+               p = p->next;
+       }
+}
+
+int main(int argc, char **argv)
+{
+       int i;
+       struct pack_list *min, *red, *pl;
+
+       for (i = 1; i < argc; i++) {
+               const char *arg = argv[i];
+               if(!strcmp(arg, "--"))
+                       break;
+               if(!strcmp(arg, "-a")) {
+                       all = 1;
+                       continue;
+               }
+               if(!strcmp(arg, "-v")) {
+                       verbose = 1;
+                       continue;
+               }
+               if(*arg == '-')
+                       usage(pack_intersect_usage);
+               else
+                       break;
+       }
+
+       prepare_packed_git();
+
+       if(all)
+               load_all();
+       else
+               while (*(argv + i) != NULL)
+                       add_pack_file(*(argv + i++));
+
+       if (pack_list == NULL)
+               die("Zero packs found!\n");
+
+       cmp_packs();
+
+       load_all_objects();
+
+       minimize(&min);
+       if (verbose) {
+               fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
+               pl = min;
+               while (pl) {
+                       fprintf(stderr, "\t%s\n", pl->pack->pack_name);
+                       pl = pl->next;
+               }
+               fprintf(stderr, "containing %ld duplicate objects "
+                               "with a total size of %ldkb.\n",
+                       get_pack_redundancy(min), pack_set_bytecount(min)/1024);
+               fprintf(stderr, "Redundant packs (with indexes):\n");
+       }
+       pl = red = pack_list_difference(pack_list, min);
+       while (pl) {
+               printf("%s\n%s\n",
+                      sha1_pack_index_name(pl->pack->sha1), pl->pack->pack_name);
+               pl = pl->next;
+       }
+
+       return 0;
+}

diff --git a/sha1_file.c b/sha1_file.c
index 946a35346bdaf21432b7f463712f5bf8881fee39..cd814d7233028952f14c149e330a36a5a0b517f3 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -424,6 +424,7 @@ struct packed_git *add_packed_git(char *path, int path_len, int local)
        struct packed_git *p;
        unsigned long idx_size;
        void *idx_map;
+       char sha1[20];
 
        if (check_packed_git_idx(path, &idx_size, &idx_map))
                return NULL;
@@ -447,6 +448,8 @@ struct packed_git *add_packed_git(char *path, int path_len, int local)
        p->pack_last_used = 0;
        p->pack_use_cnt = 0;
        p->pack_local = local;
+       if (!get_sha1_hex(path + path_len - 40 - 4, sha1))
+               memcpy(p->sha1, sha1, 20);
        return p;
 }