make "git pack-redundant" a built-in

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 696 insertions, 0 deletions

diff --git a/builtin-pack-redundant.c b/builtin-pack-redundant.c
new file mode 100644
index 0000000000..41e1615a28
--- /dev/null
+++ b/builtin-pack-redundant.c
@@ -0,0 +1,696 @@
+/*
+*
+* Copyright 2005, Lukas Sandstrom <lukass@etek.chalmers.se>
+*
+* This file is licensed under the GPL v2.
+*
+*/
+
+#include "cache.h"
+#include "exec_cmd.h"
+
+#define BLKSIZE 512
+
+static const char pack_redundant_usage[] =
+"git pack-redundant [ --verbose ] [ --alt-odb ] < --all | <.pack filename> ...>";
+
+static int load_all_packs, verbose, alt_odb;
+
+struct llist_item {
+	struct llist_item *next;
+	const unsigned char *sha1;
+};
+static struct llist {
+	struct llist_item *front;
+	struct llist_item *back;
+	size_t size;
+} *all_objects; /* all objects which must be present in local packfiles */
+
+static struct pack_list {
+	struct pack_list *next;
+	struct packed_git *pack;
+	struct llist *unique_objects;
+	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)
+{
+	item->next = free_nodes;
+	free_nodes = item;
+}
+
+static inline struct llist_item *llist_item_get(void)
+{
+	struct llist_item *new;
+	if ( free_nodes ) {
+		new = free_nodes;
+		free_nodes = free_nodes->next;
+	} else {
+		int i = 1;
+		new = xmalloc(sizeof(struct llist_item) * BLKSIZE);
+		for (; i < BLKSIZE; i++)
+			llist_item_put(&new[i]);
+	}
+	return new;
+}
+
+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));
+	(*list)->front = (*list)->back = NULL;
+	(*list)->size = 0;
+}
+
+static 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 = llist_item_get();
+	new->sha1 = list->front->sha1;
+
+	old = list->front->next;
+	while (old) {
+		prev = new;
+		new = llist_item_get();
+		prev->next = new;
+		new->sha1 = old->sha1;
+		old = old->next;
+	}
+	new->next = NULL;
+	ret->back = new;
+
+	return ret;
+}
+
+static inline struct llist_item *llist_insert(struct llist *list,
+					      struct llist_item *after,
+					       const unsigned char *sha1)
+{
+	struct llist_item *new = llist_item_get();
+	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;
+}
+
+static inline struct llist_item *llist_insert_back(struct llist *list,
+						   const unsigned char *sha1)
+{
+	return llist_insert(list, list->back, sha1);
+}
+
+static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
+			const unsigned char *sha1, struct llist_item *hint)
+{
+	struct llist_item *prev = NULL, *l;
+
+	l = (hint == NULL) ? list->front : hint;
+	while (l) {
+		int cmp = hashcmp(l->sha1, sha1);
+		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);
+}
+
+/* returns a pointer to an item in front of sha1 */
+static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned 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 = hashcmp(l->sha1, sha1);
+		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;
+			llist_item_put(l);
+			list->size--;
+			return prev;
+		}
+		prev = l;
+		l = l->next;
+	}
+	return prev;
+}
+
+/* computes A\B */
+static void llist_sorted_difference_inplace(struct llist *A,
+				     struct llist *B)
+{
+	struct llist_item *hint, *b;
+
+	hint = NULL;
+	b = B->front;
+
+	while (b) {
+		hint = llist_sorted_remove(A, b->sha1, hint);
+		b = b->next;
+	}
+}
+
+static 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;
+}
+
+static inline size_t pack_list_size(struct pack_list *pl)
+{
+	size_t ret = 0;
+	while (pl) {
+		ret++;
+		pl = pl->next;
+	}
+	return ret;
+}
+
+static struct pack_list * pack_list_difference(const struct pack_list *A,
+					       const struct pack_list *B)
+{
+	struct pack_list *ret;
+	const struct pack_list *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;
+}
+
+static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
+{
+	unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
+	const unsigned char *p1_base, *p2_base;
+	struct llist_item *p1_hint = NULL, *p2_hint = NULL;
+
+	p1_base = p1->pack->index_data;
+	p2_base = p2->pack->index_data;
+	p1_base += 256 * 4 + ((p1->pack->index_version < 2) ? 4 : 8);
+	p2_base += 256 * 4 + ((p2->pack->index_version < 2) ? 4 : 8);
+	p1_step = (p1->pack->index_version < 2) ? 24 : 20;
+	p2_step = (p2->pack->index_version < 2) ? 24 : 20;
+
+	while (p1_off < p1->pack->num_objects * p1_step &&
+	       p2_off < p2->pack->num_objects * p2_step)
+	{
+		int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
+		/* 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 += p1_step;
+			p2_off += p2_step;
+			continue;
+		}
+		if (cmp < 0) { /* p1 has the object, p2 doesn't */
+			p1_off += p1_step;
+		} else { /* p2 has the object, p1 doesn't */
+			p2_off += p2_step;
+		}
+	}
+}
+
+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, *pll;
+
+	if (list == NULL || pack_list_size(list) < n || n == 0)
+		return NULL;
+
+	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;
+	}
+
+	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;
+		}
+		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;
+	unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
+	const unsigned char *p1_base, *p2_base;
+
+	p1_base = p1->index_data;
+	p2_base = p2->index_data;
+	p1_base += 256 * 4 + ((p1->index_version < 2) ? 4 : 8);
+	p2_base += 256 * 4 + ((p2->index_version < 2) ? 4 : 8);
+	p1_step = (p1->index_version < 2) ? 24 : 20;
+	p2_step = (p2->index_version < 2) ? 24 : 20;
+
+	while (p1_off < p1->num_objects * p1_step &&
+	       p2_off < p2->num_objects * p2_step)
+	{
+		int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
+		/* cmp ~ p1 - p2 */
+		if (cmp == 0) {
+			ret++;
+			p1_off += p1_step;
+			p2_off += p2_step;
+			continue;
+		}
+		if (cmp < 0) { /* p1 has the object, p2 doesn't */
+			p1_off += p1_step;
+		} else { /* p2 has the object, p1 doesn't */
+			p2_off += p2_step;
+		}
+	}
+	return ret;
+}
+
+/* another O(n^2) function ... */
+static size_t get_pack_redundancy(struct pack_list *pl)
+{
+	struct pack_list *subset;
+	size_t ret = 0;
+
+	if (pl == NULL)
+		return 0;
+
+	while ((subset = pl->next)) {
+		while (subset) {
+			ret += sizeof_union(pl->pack, subset->pack);
+			subset = subset->next;
+		}
+		pl = pl->next;
+	}
+	return ret;
+}
+
+static inline off_t pack_set_bytecount(struct pack_list *pl)
+{
+	off_t ret = 0;
+	while (pl) {
+		ret += pl->pack->pack_size;
+		ret += pl->pack->index_size;
+		pl = pl->next;
+	}
+	return ret;
+}
+
+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;
+
+	pl = local_packs;
+	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) {
+		llist_sorted_difference_inplace(missing, pl->all_objects);
+		pl = pl->next;
+	}
+
+	/* return if there are no objects missing from the unique set */
+	if (missing->size == 0) {
+		*min = unique;
+		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;
+	while (pl) {
+		pack_list_insert(min, pl);
+		pl = pl->next;
+	}
+}
+
+static void load_all_objects(void)
+{
+	struct pack_list *pl = local_packs;
+	struct llist_item *hint, *l;
+
+	llist_init(&all_objects);
+
+	while (pl) {
+		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;
+	}
+	/* remove objects present in remote packs */
+	pl = altodb_packs;
+	while (pl) {
+		llist_sorted_difference_inplace(all_objects, pl->all_objects);
+		pl = pl->next;
+	}
+}
+
+/* this scales like O(n^2) */
+static void cmp_local_packs(void)
+{
+	struct pack_list *subset, *pl = local_packs;
+
+	while ((subset = pl)) {
+		while ((subset = subset->next))
+			cmp_two_packs(pl, subset);
+		pl = pl->next;
+	}
+}
+
+static void scan_alt_odb_packs(void)
+{
+	struct pack_list *local, *alt;
+
+	alt = altodb_packs;
+	while (alt) {
+		local = local_packs;
+		while (local) {
+			llist_sorted_difference_inplace(local->unique_objects,
+							alt->all_objects);
+			local = local->next;
+		}
+		llist_sorted_difference_inplace(all_objects, alt->all_objects);
+		alt = alt->next;
+	}
+}
+
+static struct pack_list * add_pack(struct packed_git *p)
+{
+	struct pack_list l;
+	unsigned long off = 0, step;
+	const unsigned char *base;
+
+	if (!p->pack_local && !(alt_odb || verbose))
+		return NULL;
+
+	l.pack = p;
+	llist_init(&l.all_objects);
+
+	if (open_pack_index(p))
+		return NULL;
+
+	base = p->index_data;
+	base += 256 * 4 + ((p->index_version < 2) ? 4 : 8);
+	step = (p->index_version < 2) ? 24 : 20;
+	while (off < p->num_objects * step) {
+		llist_insert_back(l.all_objects, base + off);
+		off += step;
+	}
+	/* this list will be pruned in cmp_two_packs later */
+	l.unique_objects = llist_copy(l.all_objects);
+	if (p->pack_local)
+		return pack_list_insert(&local_packs, &l);
+	else
+		return pack_list_insert(&altodb_packs, &l);
+}
+
+static struct pack_list * add_pack_file(const char *filename)
+{
+	struct packed_git *p = packed_git;
+
+	if (strlen(filename) < 40)
+		die("Bad pack filename: %s", filename);
+
+	while (p) {
+		if (strstr(p->pack_name, filename))
+			return add_pack(p);
+		p = p->next;
+	}
+	die("Filename %s not found in packed_git", filename);
+}
+
+static void load_all(void)
+{
+	struct packed_git *p = packed_git;
+
+	while (p) {
+		add_pack(p);
+		p = p->next;
+	}
+}
+
+int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	struct pack_list *min, *red, *pl;
+	struct llist *ignore;
+	unsigned char *sha1;
+	char buf[42]; /* 40 byte sha1 + \n + \0 */
+
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage(pack_redundant_usage);
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		if (!strcmp(arg, "--all")) {
+			load_all_packs = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--verbose")) {
+			verbose = 1;
+			continue;
+		}
+		if (!strcmp(arg, "--alt-odb")) {
+			alt_odb = 1;
+			continue;
+		}
+		if (*arg == '-')
+			usage(pack_redundant_usage);
+		else
+			break;
+	}
+
+	prepare_packed_git();
+
+	if (load_all_packs)
+		load_all();
+	else
+		while (*(argv + i) != NULL)
+			add_pack_file(*(argv + i++));
+
+	if (local_packs == NULL)
+		die("Zero packs found!");
+
+	load_all_objects();
+
+	cmp_local_packs();
+	if (alt_odb)
+		scan_alt_odb_packs();
+
+	/* ignore objects given on stdin */
+	llist_init(&ignore);
+	if (!isatty(0)) {
+		while (fgets(buf, sizeof(buf), stdin)) {
+			sha1 = xmalloc(20);
+			if (get_sha1_hex(buf, sha1))
+				die("Bad sha1 on stdin: %s", buf);
+			llist_insert_sorted_unique(ignore, sha1, NULL);
+		}
+	}
+	llist_sorted_difference_inplace(all_objects, ignore);
+	pl = local_packs;
+	while (pl) {
+		llist_sorted_difference_inplace(pl->unique_objects, ignore);
+		pl = pl->next;
+	}
+
+	minimize(&min);
+
+	if (verbose) {
+		fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
+			(unsigned long)pack_list_size(altodb_packs));
+		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 %lu duplicate objects "
+				"with a total size of %lukb.\n",
+			(unsigned long)get_pack_redundancy(min),
+			(unsigned long)pack_set_bytecount(min)/1024);
+		fprintf(stderr, "A total of %lu unique objects were considered.\n",
+			(unsigned long)all_objects->size);
+		fprintf(stderr, "Redundant packs (with indexes):\n");
+	}
+	pl = red = pack_list_difference(local_packs, min);
+	while (pl) {
+		printf("%s\n%s\n",
+		       sha1_pack_index_name(pl->pack->sha1),
+		       pl->pack->pack_name);
+		pl = pl->next;
+	}
+	if (verbose)
+		fprintf(stderr, "%luMB of redundant packs in total.\n",
+			(unsigned long)pack_set_bytecount(red)/(1024*1024));
+
+	return 0;
+}