git-pack-redundant: speed and memory usage improvements

Slab allocation of llist entries gives some speed improvements.

Not computing the pack_list permutaions all at once reduces memory
usage greatly on repositories with many packs.

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

diff --git a/pack-redundant.c b/pack-redundant.c
index 0a43278..1869b38 100644 (file)
--- a/pack-redundant.c
+++ b/pack-redundant.c
@@ -8,6 +8,8 @@
 
 #include "cache.h"
 
+#define BLKSIZE 512
+
 static const char pack_redundant_usage[] =
 "git-pack-redundant [ --verbose ] [ --alt-odb ] < --all | <.pack filename> ...>";
 
@@ -33,29 +35,32 @@ static struct pack_list {
 struct pll {
        struct pll *next;
        struct pack_list *pl;
-       size_t pl_size;
 };
 
 static struct llist_item *free_nodes = NULL;
 
+static inline void llist_item_put(struct llist_item *item)
+{
+       item->next = free_nodes;
+       free_nodes = item;
+}
+
 static inline struct llist_item *llist_item_get()
 {
        struct llist_item *new;
        if ( free_nodes ) {
                new = free_nodes;
                free_nodes = free_nodes->next;
-       } else
-               new = xmalloc(sizeof(struct llist_item));
-
+       } else {
+               int i = 1;
+               new = xmalloc(sizeof(struct llist_item) * BLKSIZE);
+               for(;i < BLKSIZE; i++) {
+                       llist_item_put(&new[i]);
+               }
+       }
        return new;
 }
 
-static inline void llist_item_put(struct llist_item *item)
-{
-       item->next = free_nodes;
-       free_nodes = item;
-}
-
 static void llist_free(struct llist *list)
 {
        while((list->back = list->front)) {
@@ -270,77 +275,58 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
        }
 }
 
-static void pll_insert(struct pll **pll, struct pll **hint_table)
+void pll_free(struct pll *l)
 {
-       struct pll *prev;
-       int i = (*pll)->pl_size - 1;
-
-       if (hint_table[i] == NULL) {
-               hint_table[i--] = *pll;
-               for (; i >= 0; --i) {
-                       if (hint_table[i] != NULL)
-                               break;
+       struct pll *old;
+       struct pack_list *opl;
+
+       while (l) {
+               old = l;
+               while (l->pl) {
+                       opl = l->pl;
+                       l->pl = opl->next;
+                       free(opl);
                }
-               if (hint_table[i] == NULL) /* no elements in list */
-                       die("Why did this happen?");
+               l = l->next;
+               free(old);
        }
-
-       prev = hint_table[i];
-       while (prev->next && prev->next->pl_size < (*pll)->pl_size)
-               prev = prev->next;
-
-       (*pll)->next = prev->next;
-       prev->next = *pll;
 }
 
 /* all the permutations have to be free()d at the same time,
  * since they refer to each other
  */
-static struct pll * get_all_permutations(struct pack_list *list)
+static struct pll * get_permutations(struct pack_list *list, int n)
 {
-       struct pll *subset, *pll, *new_pll = NULL; /*silence warning*/
-       static struct pll **hint = NULL;
-       if (hint == NULL)
-               hint = xcalloc(pack_list_size(list), sizeof(struct pll *));
-               
-       if (list == NULL)
+       struct pll *subset, *ret = NULL, *new_pll = NULL, *pll;
+
+       if (list == NULL || pack_list_size(list) < n || n == 0)
                return NULL;
 
-       if (list->next == NULL) {
-               new_pll = xmalloc(sizeof(struct pll));
-               hint[0] = new_pll;
-               new_pll->next = NULL;
-               new_pll->pl = list;
-               new_pll->pl_size = 1;
-               return new_pll;
+       if (n == 1) {
+               while (list) {
+                       new_pll = xmalloc(sizeof(pll));
+                       new_pll->pl = NULL;
+                       pack_list_insert(&new_pll->pl, list);
+                       new_pll->next = ret;
+                       ret = new_pll;
+                       list = list->next;
+               }
+               return ret;
        }
 
-       pll = subset = get_all_permutations(list->next);
-       while (pll) {
-               if (pll->pl->pack == list->pack) {
-                       pll = pll->next;
-                       continue;
+       while (list->next) {
+               subset = get_permutations(list->next, n - 1);
+               while (subset) {
+                       new_pll = xmalloc(sizeof(pll));
+                       new_pll->pl = subset->pl;
+                       pack_list_insert(&new_pll->pl, list);
+                       new_pll->next = ret;
+                       ret = new_pll;
+                       subset = subset->next;
                }
-               new_pll = xmalloc(sizeof(struct pll));
-
-               new_pll->pl = xmalloc(sizeof(struct pack_list));
-               memcpy(new_pll->pl, list, sizeof(struct pack_list));
-               new_pll->pl->next = pll->pl;
-               new_pll->pl_size = pll->pl_size + 1;
-               
-               pll_insert(&new_pll, hint);
-
-               pll = pll->next;
-       }
-       /* add ourself */
-       new_pll = xmalloc(sizeof(struct pll));
-       new_pll->pl = xmalloc(sizeof(struct pack_list));
-       memcpy(new_pll->pl, list, sizeof(struct pack_list));
-       new_pll->pl->next = NULL;
-       new_pll->pl_size = 1;
-       pll_insert(&new_pll, hint);
-
-       return hint[0];
+               list = list->next;
+       }
+       return ret;
 }
 
 static int is_superset(struct pack_list *pl, struct llist *list)
@@ -428,6 +414,7 @@ static void minimize(struct pack_list **min)
        struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
        struct llist *missing;
        size_t min_perm_size = (size_t)-1, perm_size;
+       int n;
 
        pl = local_packs;
        while (pl) {
@@ -441,8 +428,7 @@ static void minimize(struct pack_list **min)
        missing = llist_copy(all_objects);
        pl = unique;
        while (pl) {
-               llist_sorted_difference_inplace(missing,
-                                               pl->all_objects);
+               llist_sorted_difference_inplace(missing, pl->all_objects);
                pl = pl->next;
        }
 
@@ -453,19 +439,21 @@ static void minimize(struct pack_list **min)
        }
 
        /* find the permutations which contain all missing objects */
-       perm_all = perm = get_all_permutations(non_unique);
-       while (perm) {
-               if (perm_ok && perm->pl_size > perm_ok->pl_size)
-                       break; /* ignore all larger permutations */
-               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;
+       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;
                }
-               perm = perm->next;
+               if (perm_ok)
+                       break;
+               pll_free(perm_all);
        }
-       
        if (perm_ok == NULL)
                die("Internal error: No complete sets found!\n");
 
@@ -537,6 +525,7 @@ static void scan_alt_odb_packs(void)
                                                        alt->all_objects);
                        local = local->next;
                }
+               llist_sorted_difference_inplace(all_objects, alt->all_objects);
                alt = alt->next;
        }
 }