Merge branches 'jc/rev-list' and 'jc/pack-thin'

* jc/rev-list:
  rev-list --objects: use full pathname to help hashing.
  rev-list --objects-edge: remove duplicated edge commit output.
  rev-list --objects-edge

* jc/pack-thin:
  pack-objects: hash basename and direname a bit differently.
  pack-objects: allow "thin" packs to exceed depth limits
  pack-objects: use full pathname to help hashing with "thin" pack.
  pack-objects: thin pack micro-optimization.
  Use thin pack transfer in "git fetch".
  Add git-push --thin.
  send-pack --thin: use "thin pack" delta transfer.
  Thin pack - create packfile with missing delta base.

Conflicts:

	pack-objects.c (taking "next")
	send-pack.c (taking "next")

fetch-pack.c

@@ -8,7 +8,7 @@ static int keep_pack;
 static int quiet;
 static int verbose;
 static const char fetch_pack_usage[] =
-"git-fetch-pack [-q] [-v] [-k] [--exec=upload-pack] [host:]directory <refs>...";
+"git-fetch-pack [-q] [-v] [-k] [--thin] [--exec=upload-pack] [host:]directory <refs>...";
 static const char *exec = "git-upload-pack";
 
 #define COMPLETE	(1U << 0)
@@ -18,7 +18,7 @@ static const char *exec = "git-upload-pack";
 #define POPPED		(1U << 4)
 
 static struct commit_list *rev_list = NULL;
-static int non_common_revs = 0, multi_ack = 0;
+static int non_common_revs = 0, multi_ack = 0, use_thin_pack = 0;
 
 static void rev_list_push(struct commit *commit, int mark)
 {
@@ -156,8 +156,9 @@ static int find_common(int fd[2], unsigned char *result_sha1,
 			continue;
 		}
 
-		packet_write(fd[1], "want %s%s\n", sha1_to_hex(remote),
+		packet_write(fd[1], "want %s%s%s\n", sha1_to_hex(remote),
-			multi_ack ? " multi_ack" : "");
+			     (multi_ack ? " multi_ack" : ""),
+			     (use_thin_pack ? " thin-pack" : ""));
 		fetching++;
 	}
 	packet_flush(fd[1]);
@@ -421,6 +422,10 @@ int main(int argc, char **argv)
 				keep_pack = 1;
 				continue;
 			}
+			if (!strcmp("--thin", arg)) {
+				use_thin_pack = 1;
+				continue;
+			}
 			if (!strcmp("-v", arg)) {
 				verbose = 1;
 				continue;
@@ -434,6 +439,8 @@ int main(int argc, char **argv)
 	}
 	if (!dest)
 		usage(fetch_pack_usage);
+	if (keep_pack)
+		use_thin_pack = 0;
 	pid = git_connect(fd, dest, exec);
 	if (pid < 0)
 		return 1;

git-fetch.sh

@@ -320,7 +320,7 @@ fetch_main () {
     ( : subshell because we muck with IFS
       IFS=" 	$LF"
       (
-	  git-fetch-pack $exec $keep "$remote" $rref || echo failed "$remote"
+	  git-fetch-pack $exec $keep --thin "$remote" $rref || echo failed "$remote"
       ) |
       while read sha1 remote_name
       do

git-push.sh

@@ -8,6 +8,7 @@ USAGE='[--all] [--tags] [--force] <repository> [<refspec>...]'
 has_all=
 has_force=
 has_exec=
+has_thin=
 remote=
 do_tags=
 
@@ -22,6 +23,8 @@ do
 		has_force=--force ;;
 	--exec=*)
 		has_exec="$1" ;;
+	--thin)
+		has_thin="$1" ;;
 	-*)
                 usage ;;
         *)
@@ -72,6 +75,7 @@ set x "$remote" "$@"; shift
 test "$has_all" && set x "$has_all" "$@" && shift
 test "$has_force" && set x "$has_force" "$@" && shift
 test "$has_exec" && set x "$has_exec" "$@" && shift
+test "$has_thin" && set x "$has_thin" "$@" && shift
 
 case "$remote" in
 http://* | https://*)

pack-objects.c

@@ -3,6 +3,7 @@
 #include "delta.h"
 #include "pack.h"
 #include "csum-file.h"
+#include "diff.h"
 #include <sys/time.h>
 #include <signal.h>
 
@@ -27,6 +28,13 @@ struct object_entry {
 	struct object_entry *delta_sibling; /* other deltified objects who
 					     * uses the same base as me
 					     */
+	int preferred_base;	/* we do not pack this, but is encouraged to
+				 * be used as the base objectto delta huge
+				 * objects against.
+				 */
+	int based_on_preferred;	/* current delta candidate is a preferred
+				 * one, or delta against a preferred one.
+				 */
 };
 
 /*
@@ -49,7 +57,7 @@ static int local = 0;
 static int incremental = 0;
 static struct object_entry **sorted_by_sha, **sorted_by_type;
 static struct object_entry *objects = NULL;
-static int nr_objects = 0, nr_alloc = 0;
+static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
 static const char *base_name;
 static unsigned char pack_file_sha1[20];
 static int progress = 1;
@@ -231,7 +239,8 @@ static int encode_header(enum object_type type, unsigned long size, unsigned cha
 	return n;
 }
 
-static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
+static unsigned long write_object(struct sha1file *f,
+				  struct object_entry *entry)
 {
 	unsigned long size;
 	char type[10];
@@ -241,6 +250,9 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry
 	enum object_type obj_type;
 	int to_reuse = 0;
 
+	if (entry->preferred_base)
+		return 0;
+
 	obj_type = entry->type;
 	if (! entry->in_pack)
 		to_reuse = 0;	/* can't reuse what we don't have */
@@ -335,20 +347,22 @@ static void write_pack_file(void)
 		do_progress = progress;
 	}
 	if (do_progress)
-		fprintf(stderr, "Writing %d objects.\n", nr_objects);
+		fprintf(stderr, "Writing %d objects.\n", nr_result);
 
 	hdr.hdr_signature = htonl(PACK_SIGNATURE);
 	hdr.hdr_version = htonl(PACK_VERSION);
-	hdr.hdr_entries = htonl(nr_objects);
+	hdr.hdr_entries = htonl(nr_result);
 	sha1write(f, &hdr, sizeof(hdr));
 	offset = sizeof(hdr);
+	if (!nr_result)
+		goto done;
 	for (i = 0; i < nr_objects; i++) {
 		offset = write_one(f, objects + i, offset);
 		if (do_progress) {
-			unsigned percent = written * 100 / nr_objects;
+			unsigned percent = written * 100 / nr_result;
 			if (progress_update || percent != last_percent) {
 				fprintf(stderr, "%4u%% (%u/%u) done\r",
-					percent, written, nr_objects);
+					percent, written, nr_result);
 				progress_update = 0;
 				last_percent = percent;
 			}
@@ -356,16 +370,17 @@ static void write_pack_file(void)
 	}
 	if (do_progress)
 		fputc('\n', stderr);
-
+ done:
 	sha1close(f, pack_file_sha1, 1);
 }
 
 static void write_index_file(void)
 {
 	int i;
-	struct sha1file *f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "idx");
+	struct sha1file *f = sha1create("%s-%s.%s", base_name,
+					sha1_to_hex(object_list_sha1), "idx");
 	struct object_entry **list = sorted_by_sha;
-	struct object_entry **last = list + nr_objects;
+	struct object_entry **last = list + nr_result;
 	unsigned int array[256];
 
 	/*
@@ -390,7 +405,7 @@ static void write_index_file(void)
 	 * Write the actual SHA1 entries..
 	 */
 	list = sorted_by_sha;
-	for (i = 0; i < nr_objects; i++) {
+	for (i = 0; i < nr_result; i++) {
 		struct object_entry *entry = *list++;
 		unsigned int offset = htonl(entry->offset);
 		sha1write(f, &offset, 4);
@@ -400,46 +415,7 @@ static void write_index_file(void)
 	sha1close(f, NULL, 1);
 }
 
-static int add_object_entry(unsigned char *sha1, unsigned int hash)
+static int locate_object_entry_hash(const unsigned char *sha1)
-{
-	unsigned int idx = nr_objects;
-	struct object_entry *entry;
-	struct packed_git *p;
-	unsigned int found_offset = 0;
-	struct packed_git *found_pack = NULL;
-
-	for (p = packed_git; p; p = p->next) {
-		struct pack_entry e;
-		if (find_pack_entry_one(sha1, &e, p)) {
-			if (incremental)
-				return 0;
-			if (local && !p->pack_local)
-				return 0;
-			if (!found_pack) {
-				found_offset = e.offset;
-				found_pack = e.p;
-			}
-		}
-	}
-
-	if (idx >= nr_alloc) {
-		unsigned int needed = (idx + 1024) * 3 / 2;
-		objects = xrealloc(objects, needed * sizeof(*entry));
-		nr_alloc = needed;
-	}
-	entry = objects + idx;
-	memset(entry, 0, sizeof(*entry));
-	memcpy(entry->sha1, sha1, 20);
-	entry->hash = hash;
-	if (found_pack) {
-		entry->in_pack = found_pack;
-		entry->in_pack_offset = found_offset;
-	}
-	nr_objects = idx+1;
-	return 1;
-}
-
-static int locate_object_entry_hash(unsigned char *sha1)
 {
 	int i;
 	unsigned int ui;
@@ -454,19 +430,219 @@ static int locate_object_entry_hash(unsigned char *sha1)
 	return -1 - i;
 }
 
-static struct object_entry *locate_object_entry(unsigned char *sha1)
+static struct object_entry *locate_object_entry(const unsigned char *sha1)
 {
-	int i = locate_object_entry_hash(sha1);
+	int i;
+
+	if (!object_ix_hashsz)
+		return NULL;
+
+	i = locate_object_entry_hash(sha1);
 	if (0 <= i)
 		return &objects[object_ix[i]-1];
 	return NULL;
 }
 
+static void rehash_objects(void)
+{
+	int i;
+	struct object_entry *oe;
+
+	object_ix_hashsz = nr_objects * 3;
+	if (object_ix_hashsz < 1024)
+		object_ix_hashsz = 1024;
+	object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
+	object_ix = memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
+	for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
+		int ix = locate_object_entry_hash(oe->sha1);
+		if (0 <= ix)
+			continue;
+		ix = -1 - ix;
+		object_ix[ix] = i + 1;
+	}
+}
+
+struct name_path {
+	struct name_path *up;
+	const char *elem;
+	int len;
+};
+
+#define DIRBITS 12
+
+static unsigned name_hash(struct name_path *path, const char *name)
+{
+	struct name_path *p = path;
+	const char *n = name + strlen(name);
+	unsigned hash = 0, name_hash = 0, name_done = 0;
+
+	if (n != name && n[-1] == '\n')
+		n--;
+	while (name <= --n) {
+		unsigned char c = *n;
+		if (c == '/' && !name_done) {
+			name_hash = hash;
+			name_done = 1;
+			hash = 0;
+		}
+		hash = hash * 11 + c;
+	}
+	if (!name_done) {
+		name_hash = hash;
+		hash = 0;
+	}
+	for (p = path; p; p = p->up) {
+		hash = hash * 11 + '/';
+		n = p->elem + p->len;
+		while (p->elem <= --n) {
+			unsigned char c = *n;
+			hash = hash * 11 + c;
+		}
+	}
+	/*
+	 * Make sure "Makefile" and "t/Makefile" are hashed separately
+	 * but close enough.
+	 */
+	hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
+
+	if (0) { /* debug */
+		n = name + strlen(name);
+		if (n != name && n[-1] == '\n')
+			n--;
+		while (name <= --n)
+			fputc(*n, stderr);
+		for (p = path; p; p = p->up) {
+			fputc('/', stderr);
+			n = p->elem + p->len;
+			while (p->elem <= --n)
+				fputc(*n, stderr);
+		}
+		fprintf(stderr, "\t%08x\n", hash);
+	}
+	return hash;
+}
+
+static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
+{
+	unsigned int idx = nr_objects;
+	struct object_entry *entry;
+	struct packed_git *p;
+	unsigned int found_offset = 0;
+	struct packed_git *found_pack = NULL;
+	int ix, status = 0;
+
+	if (!exclude) {
+		for (p = packed_git; p; p = p->next) {
+			struct pack_entry e;
+			if (find_pack_entry_one(sha1, &e, p)) {
+				if (incremental)
+					return 0;
+				if (local && !p->pack_local)
+					return 0;
+				if (!found_pack) {
+					found_offset = e.offset;
+					found_pack = e.p;
+				}
+			}
+		}
+	}
+	if ((entry = locate_object_entry(sha1)) != NULL)
+		goto already_added;
+
+	if (idx >= nr_alloc) {
+		unsigned int needed = (idx + 1024) * 3 / 2;
+		objects = xrealloc(objects, needed * sizeof(*entry));
+		nr_alloc = needed;
+	}
+	entry = objects + idx;
+	nr_objects = idx + 1;
+	memset(entry, 0, sizeof(*entry));
+	memcpy(entry->sha1, sha1, 20);
+	entry->hash = hash;
+
+	if (object_ix_hashsz * 3 <= nr_objects * 4)
+		rehash_objects();
+	else {
+		ix = locate_object_entry_hash(entry->sha1);
+		if (0 <= ix)
+			die("internal error in object hashing.");
+		object_ix[-1 - ix] = idx + 1;
+	}
+	status = 1;
+
+ already_added:
+	if (progress_update) {
+		fprintf(stderr, "Counting objects...%d\r", nr_objects);
+		progress_update = 0;
+	}
+	if (exclude)
+		entry->preferred_base = 1;
+	else {
+		if (found_pack) {
+			entry->in_pack = found_pack;
+			entry->in_pack_offset = found_offset;
+		}
+	}
+	return status;
+}
+
+static void add_pbase_tree(struct tree_desc *tree, struct name_path *up)
+{
+	while (tree->size) {
+		const unsigned char *sha1;
+		const char *name;
+		unsigned mode, hash;
+		unsigned long size;
+		char type[20];
+
+		sha1 = tree_entry_extract(tree, &name, &mode);
+		update_tree_entry(tree);
+		if (!has_sha1_file(sha1))
+			continue;
+		if (sha1_object_info(sha1, type, &size))
+			continue;
+
+		hash = name_hash(up, name);
+		if (!add_object_entry(sha1, hash, 1))
+			continue;
+
+		if (!strcmp(type, "tree")) {
+			struct tree_desc sub;
+			void *elem;
+			struct name_path me;
+
+			elem = read_sha1_file(sha1, type, &sub.size);
+			sub.buf = elem;
+			if (sub.buf) {
+				me.up = up;
+				me.elem = name;
+				me.len = strlen(name);
+				add_pbase_tree(&sub, &me);
+				free(elem);
+			}
+		}
+	}
+}
+
+static void add_preferred_base(unsigned char *sha1)
+{
+	struct tree_desc tree;
+	void *elem;
+
+	elem = read_object_with_reference(sha1, "tree", &tree.size, NULL);
+	tree.buf = elem;
+	if (!tree.buf)
+		return;
+	if (add_object_entry(sha1, name_hash(NULL, ""), 1))
+		add_pbase_tree(&tree, NULL);
+	free(elem);
+}
+
 static void check_object(struct object_entry *entry)
 {
 	char type[20];
 
-	if (entry->in_pack) {
+	if (entry->in_pack && !entry->preferred_base) {
 		unsigned char base[20];
 		unsigned long size;
 		struct object_entry *base_entry;
@@ -485,7 +661,8 @@ static void check_object(struct object_entry *entry)
 		 */
 		if (!no_reuse_delta &&
 		    entry->in_pack_type == OBJ_DELTA &&
-		    (base_entry = locate_object_entry(base))) {
+		    (base_entry = locate_object_entry(base)) &&
+		    (!base_entry->preferred_base)) {
 
 			/* Depth value does not matter - find_deltas()
 			 * will never consider reused delta as the
@@ -523,25 +700,6 @@ static void check_object(struct object_entry *entry)
 		    sha1_to_hex(entry->sha1), type);
 }
 
-static void hash_objects(void)
-{
-	int i;
-	struct object_entry *oe;
-
-	object_ix_hashsz = nr_objects * 2;
-	object_ix = xcalloc(sizeof(int), object_ix_hashsz);
-	for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
-		int ix = locate_object_entry_hash(oe->sha1);
-		if (0 <= ix) {
-			error("the same object '%s' added twice",
-			      sha1_to_hex(oe->sha1));
-			continue;
-		}
-		ix = -1 - ix;
-		object_ix[ix] = i + 1;
-	}
-}
-
 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 {
 	struct object_entry *child = me->delta_child;
@@ -560,14 +718,26 @@ static void get_object_details(void)
 	int i;
 	struct object_entry *entry;
 
-	hash_objects();
 	prepare_pack_ix();
 	for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 		check_object(entry);
-	for (i = 0, entry = objects; i < nr_objects; i++, entry++)
+
-		if (!entry->delta && entry->delta_child)
+	if (nr_objects == nr_result) {
-			entry->delta_limit =
+		/*
-				check_delta_limit(entry, 1);
+		 * Depth of objects that depend on the entry -- this
+		 * is subtracted from depth-max to break too deep
+		 * delta chain because of delta data reusing.
+		 * However, we loosen this restriction when we know we
+		 * are creating a thin pack -- it will have to be
+		 * expanded on the other end anyway, so do not
+		 * artificially cut the delta chain and let it go as
+		 * deep as it wants.
+		 */
+		for (i = 0, entry = objects; i < nr_objects; i++, entry++)
+			if (!entry->delta && entry->delta_child)
+				entry->delta_limit =
+					check_delta_limit(entry, 1);
+	}
 }
 
 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
@@ -598,6 +768,24 @@ static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 	return memcmp(a->sha1, b->sha1, 20);
 }
 
+static struct object_entry **create_final_object_list()
+{
+	struct object_entry **list;
+	int i, j;
+
+	for (i = nr_result = 0; i < nr_objects; i++)
+		if (!objects[i].preferred_base)
+			nr_result++;
+	list = xmalloc(nr_result * sizeof(struct object_entry *));
+	for (i = j = 0; i < nr_objects; i++) {
+		if (!objects[i].preferred_base)
+			list[j++] = objects + i;
+	}
+	current_sort = sha1_sort;
+	qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
+	return list;
+}
+
 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 {
 	if (a->type < b->type)
@@ -608,6 +796,10 @@ static int type_size_sort(const struct object_entry *a, const struct object_entr
 		return -1;
 	if (a->hash > b->hash)
 		return 1;
+	if (a->preferred_base < b->preferred_base)
+		return -1;
+	if (a->preferred_base > b->preferred_base)
+		return 1;
 	if (a->size < b->size)
 		return -1;
 	if (a->size > b->size)
@@ -632,6 +824,8 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
 {
 	struct object_entry *cur_entry = cur->entry;
 	struct object_entry *old_entry = old->entry;
+	int old_preferred = (old_entry->preferred_base ||
+			     old_entry->based_on_preferred);
 	unsigned long size, oldsize, delta_size, sizediff;
 	long max_size;
 	void *delta_buf;
@@ -640,9 +834,15 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
 	if (cur_entry->type != old_entry->type)
 		return -1;
 
-	/* If the current object is at edge, take the depth the objects
+	/* We do not compute delta to *create* objects we are not
-	 * that depend on the current object into account -- otherwise
+	 * going to pack.
-	 * they would become too deep.
+	 */
+	if (cur_entry->preferred_base)
+		return -1;
+
+	/* If the current object is at pack edge, take the depth the
+	 * objects that depend on the current object into account --
+	 * otherwise they would become too deep.
 	 */
 	if (cur_entry->delta_child) {
 		if (max_depth <= cur_entry->delta_limit)
@@ -651,11 +851,10 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
 	}
 
 	size = cur_entry->size;
-	if (size < 50)
-		return -1;
 	oldsize = old_entry->size;
 	sizediff = oldsize > size ? oldsize - size : size - oldsize;
-	if (sizediff > size / 8)
+
+	if (size < 50)
 		return -1;
 	if (old_entry->depth >= max_depth)
 		return 0;
@@ -668,8 +867,27 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
 	 * delete).
 	 */
 	max_size = size / 2 - 20;
-	if (cur_entry->delta)
+	if (cur_entry->delta) {
-		max_size = cur_entry->delta_size-1;
+		if (cur_entry->based_on_preferred) {
+			if (old_preferred)
+				max_size = cur_entry->delta_size-1;
+			else
+				/* trying with non-preferred one when we
+				 * already have a delta based on preferred
+				 * one is pointless.
+				 */
+				return -1;
+		}
+		else if (!old_preferred)
+			max_size = cur_entry->delta_size-1;
+		else
+			/* otherwise...  even if delta with a
+			 * preferred one produces a bigger result than
+			 * what we currently have, which is based on a
+			 * non-preferred one, it is OK.
+			 */
+			;
+	}
 	if (sizediff >= max_size)
 		return -1;
 	delta_buf = diff_delta(old->data, oldsize,
@@ -679,6 +897,7 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
 	cur_entry->delta = old_entry;
 	cur_entry->delta_size = delta_size;
 	cur_entry->depth = old_entry->depth + 1;
+	cur_entry->based_on_preferred = old_preferred;
 	free(delta_buf);
 	return 0;
 }
@@ -701,7 +920,7 @@ static void find_deltas(struct object_entry **list, int window, int depth)
 	i = nr_objects;
 	idx = 0;
 	if (progress)
-		fprintf(stderr, "Deltifying %d objects.\n", nr_objects);
+		fprintf(stderr, "Deltifying %d objects.\n", nr_result);
 
 	while (--i >= 0) {
 		struct object_entry *entry = list[i];
@@ -710,12 +929,14 @@ static void find_deltas(struct object_entry **list, int window, int depth)
 		char type[10];
 		int j;
 
-		processed++;
+		if (!entry->preferred_base)
+			processed++;
+
 		if (progress) {
-			unsigned percent = processed * 100 / nr_objects;
+			unsigned percent = processed * 100 / nr_result;
 			if (percent != last_percent || progress_update) {
 				fprintf(stderr, "%4u%% (%u/%u) done\r",
-					percent, processed, nr_objects);
+					percent, processed, nr_result);
 				progress_update = 0;
 				last_percent = percent;
 			}
@@ -895,44 +1116,40 @@ int main(int argc, char **argv)
 	}
 
 	while (fgets(line, sizeof(line), stdin) != NULL) {
-		unsigned int hash;
-		char *p;
 		unsigned char sha1[20];
 
-		if (progress_update) {
+		if (line[0] == '-') {
-			fprintf(stderr, "Counting objects...%d\r", nr_objects);
+			if (get_sha1_hex(line+1, sha1))
-			progress_update = 0;
+				die("expected edge sha1, got garbage:\n %s",
+				    line+1);
+			add_preferred_base(sha1);
+			continue;
 		}
 		if (get_sha1_hex(line, sha1))
 			die("expected sha1, got garbage:\n %s", line);
-		hash = 0;
+		add_object_entry(sha1, name_hash(NULL, line+41), 0);
-		p = line+40;
-		while (*p) {
-			unsigned char c = *p++;
-			if (isspace(c))
-				continue;
-			hash = hash * 11 + c;
-		}
-		add_object_entry(sha1, hash);
 	}
 	if (progress)
 		fprintf(stderr, "Done counting %d objects.\n", nr_objects);
-	if (non_empty && !nr_objects)
+	sorted_by_sha = create_final_object_list();
+	if (non_empty && !nr_result)
 		return 0;
 
-	sorted_by_sha = create_sorted_list(sha1_sort);
 	SHA1_Init(&ctx);
 	list = sorted_by_sha;
-	for (i = 0; i < nr_objects; i++) {
+	for (i = 0; i < nr_result; i++) {
 		struct object_entry *entry = *list++;
 		SHA1_Update(&ctx, entry->sha1, 20);
 	}
 	SHA1_Final(object_list_sha1, &ctx);
+	if (progress && (nr_objects != nr_result))
+		fprintf(stderr, "Result has %d objects.\n", nr_result);
 
 	if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
 		;
 	else {
-		prepare_pack(window, depth);
+		if (nr_result)
+			prepare_pack(window, depth);
 		if (progress && pack_to_stdout) {
 			/* the other end usually displays progress itself */
 			struct itimerval v = {{0,},};
@@ -948,6 +1165,6 @@ int main(int argc, char **argv)
 	}
 	if (progress)
 		fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
-			nr_objects, written, written_delta, reused, reused_delta);
+			nr_result, written, written_delta, reused, reused_delta);
 	return 0;
 }

rev-list.c

@@ -30,7 +30,7 @@ static const char rev_list_usage[] =
 "    --date-order\n"
 "  formatting output:\n"
 "    --parents\n"
-"    --objects\n"
+"    --objects | --objects-edge\n"
 "    --unpacked\n"
 "    --header | --pretty\n"
 "    --abbrev=nr | --no-abbrev\n"
@@ -44,6 +44,7 @@ static int bisect_list = 0;
 static int tag_objects = 0;
 static int tree_objects = 0;
 static int blob_objects = 0;
+static int edge_hint = 0;
 static int verbose_header = 0;
 static int abbrev = DEFAULT_ABBREV;
 static int show_parents = 0;
@@ -62,6 +63,36 @@ static int no_merges = 0;
 static const char **paths = NULL;
 static int remove_empty_trees = 0;
 
+struct name_path {
+	struct name_path *up;
+	int elem_len;
+	const char *elem;
+};
+
+static char *path_name(struct name_path *path, const char *name)
+{
+	struct name_path *p;
+	char *n, *m;
+	int nlen = strlen(name);
+	int len = nlen + 1;
+
+	for (p = path; p; p = p->up) {
+		if (p->elem_len)
+			len += p->elem_len + 1;
+	}
+	n = xmalloc(len);
+	m = n + len - (nlen + 1);
+	strcpy(m, name);
+	for (p = path; p; p = p->up) {
+		if (p->elem_len) {
+			m -= p->elem_len + 1;
+			memcpy(m, p->elem, p->elem_len);
+			m[p->elem_len] = '/';
+		}
+	}
+	return n;
+}
+
 static void show_commit(struct commit *commit)
 {
 	commit->object.flags |= SHOWN;
@@ -173,17 +204,23 @@ static int process_commit(struct commit * commit)
 	return CONTINUE;
 }
 
-static struct object_list **add_object(struct object *obj, struct object_list **p, const char *name)
+static struct object_list **add_object(struct object *obj,
+				       struct object_list **p,
+				       struct name_path *path,
+				       const char *name)
 {
 	struct object_list *entry = xmalloc(sizeof(*entry));
 	entry->item = obj;
 	entry->next = *p;
-	entry->name = name;
+	entry->name = path_name(path, name);
 	*p = entry;
 	return &entry->next;
 }
 
-static struct object_list **process_blob(struct blob *blob, struct object_list **p, const char *name)
+static struct object_list **process_blob(struct blob *blob,
+					 struct object_list **p,
+					 struct name_path *path,
+					 const char *name)
 {
 	struct object *obj = &blob->object;
 
@@ -192,13 +229,17 @@ static struct object_list **process_blob(struct blob *blob, struct object_list *
 	if (obj->flags & (UNINTERESTING | SEEN))
 		return p;
 	obj->flags |= SEEN;
-	return add_object(obj, p, name);
+	return add_object(obj, p, path, name);
 }
 
-static struct object_list **process_tree(struct tree *tree, struct object_list **p, const char *name)
+static struct object_list **process_tree(struct tree *tree,
+					 struct object_list **p,
+					 struct name_path *path,
+					 const char *name)
 {
 	struct object *obj = &tree->object;
 	struct tree_entry_list *entry;
+	struct name_path me;
 
 	if (!tree_objects)
 		return p;
@@ -207,15 +248,18 @@ static struct object_list **process_tree(struct tree *tree, struct object_list *
 	if (parse_tree(tree) < 0)
 		die("bad tree object %s", sha1_to_hex(obj->sha1));
 	obj->flags |= SEEN;
-	p = add_object(obj, p, name);
+	p = add_object(obj, p, path, name);
+	me.up = path;
+	me.elem = name;
+	me.elem_len = strlen(name);
 	entry = tree->entries;
 	tree->entries = NULL;
 	while (entry) {
 		struct tree_entry_list *next = entry->next;
 		if (entry->directory)
-			p = process_tree(entry->item.tree, p, entry->name);
+			p = process_tree(entry->item.tree, p, &me, entry->name);
 		else
-			p = process_blob(entry->item.blob, p, entry->name);
+			p = process_blob(entry->item.blob, p, &me, entry->name);
 		free(entry);
 		entry = next;
 	}
@@ -230,7 +274,7 @@ static void show_commit_list(struct commit_list *list)
 	while (list) {
 		struct commit *commit = pop_most_recent_commit(&list, SEEN);
 
-		p = process_tree(commit->tree, p, "");
+		p = process_tree(commit->tree, p, NULL, "");
 		if (process_commit(commit) == STOP)
 			break;
 	}
@@ -241,15 +285,15 @@ static void show_commit_list(struct commit_list *list)
 			continue;
 		if (obj->type == tag_type) {
 			obj->flags |= SEEN;
-			p = add_object(obj, p, name);
+			p = add_object(obj, p, NULL, name);
 			continue;
 		}
 		if (obj->type == tree_type) {
-			p = process_tree((struct tree *)obj, p, name);
+			p = process_tree((struct tree *)obj, p, NULL, name);
 			continue;
 		}
 		if (obj->type == blob_type) {
-			p = process_blob((struct blob *)obj, p, name);
+			p = process_blob((struct blob *)obj, p, NULL, name);
 			continue;
 		}
 		die("unknown pending object %s (%s)", sha1_to_hex(obj->sha1), name);
@@ -430,16 +474,32 @@ static struct commit_list *find_bisection(struct commit_list *list)
 	return best;
 }
 
+static void mark_edge_parents_uninteresting(struct commit *commit)
+{
+	struct commit_list *parents;
+
+	for (parents = commit->parents; parents; parents = parents->next) {
+		struct commit *parent = parents->item;
+		if (!(parent->object.flags & UNINTERESTING))
+			continue;
+		mark_tree_uninteresting(parent->tree);
+		if (edge_hint && !(parent->object.flags & SHOWN)) {
+			parent->object.flags |= SHOWN;
+			printf("-%s\n", sha1_to_hex(parent->object.sha1));
+		}
+	}
+}
+
 static void mark_edges_uninteresting(struct commit_list *list)
 {
 	for ( ; list; list = list->next) {
-		struct commit_list *parents = list->item->parents;
+		struct commit *commit = list->item;
 
-		for ( ; parents; parents = parents->next) {
+		if (commit->object.flags & UNINTERESTING) {
-			struct commit *commit = parents->item;
+			mark_tree_uninteresting(commit->tree);
-			if (commit->object.flags & UNINTERESTING)
+			continue;
-				mark_tree_uninteresting(commit->tree);
 		}
+		mark_edge_parents_uninteresting(commit);
 	}
 }
 
@@ -657,7 +717,7 @@ static struct commit_list *limit_list(struct commit_list *list)
 
 static void add_pending_object(struct object *obj, const char *name)
 {
-	add_object(obj, &pending_objects, name);
+	add_object(obj, &pending_objects, NULL, name);
 }
 
 static struct commit *get_commit_reference(const char *name, const unsigned char *sha1, unsigned int flags)
@@ -843,6 +903,13 @@ int main(int argc, const char **argv)
 			blob_objects = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--objects-edge")) {
+			tag_objects = 1;
+			tree_objects = 1;
+			blob_objects = 1;
+			edge_hint = 1;
+			continue;
+		}
 		if (!strcmp(arg, "--unpacked")) {
 			unpacked = 1;
 			limited = 1;

rev-parse.c

@@ -43,6 +43,7 @@ static int is_rev_argument(const char *arg)
 		"--min-age=",
 		"--no-merges",
 		"--objects",
+		"--objects-edge",
 		"--parents",
 		"--pretty",
 		"--show-breaks",

send-pack.c

@@ -12,6 +12,7 @@ static const char *exec = "git-receive-pack";
 static int verbose = 0;
 static int send_all = 0;
 static int force_update = 0;
+static int use_thin_pack = 0;
 
 static int is_zero_sha1(const unsigned char *sha1)
 {
@@ -42,7 +43,10 @@ static void exec_rev_list(struct ref *refs)
 	int i = 0, j;
 
 	args[i++] = "rev-list";	/* 0 */
-	args[i++] = "--objects";	/* 1 */
+	if (use_thin_pack)	/* 1 */
+		args[i++] = "--objects-edge";
+	else
+		args[i++] = "--objects";
 
 	/* First send the ones we care about most */
 	for (ref = refs; ref; ref = ref->next) {
@@ -379,6 +383,10 @@ int main(int argc, char **argv)
 				verbose = 1;
 				continue;
 			}
+			if (!strcmp(arg, "--thin")) {
+				use_thin_pack = 1;
+				continue;
+			}
 			usage(send_pack_usage);
 		}
 		if (!dest) {

upload-pack.c

@@ -14,6 +14,7 @@ static const char upload_pack_usage[] = "git-upload-pack [--strict] [--timeout=n
 #define MAX_HAS 256
 #define MAX_NEEDS 256
 static int nr_has = 0, nr_needs = 0, multi_ack = 0, nr_our_refs = 0;
+static int use_thin_pack = 0;
 static unsigned char has_sha1[MAX_HAS][20];
 static unsigned char needs_sha1[MAX_NEEDS][20];
 static unsigned int timeout = 0;
@@ -49,8 +50,10 @@ static void create_pack_file(void)
 		char *buf;
 		char **p;
 
-		if (create_full_pack)
+		if (create_full_pack) {
 			args = 10;
+			use_thin_pack = 0; /* no point doing it */
+		}
 		else
 			args = nr_has + nr_needs + 5;
 		argv = xmalloc(args * sizeof(char *));
@@ -62,7 +65,7 @@ static void create_pack_file(void)
 		close(fd[0]);
 		close(fd[1]);
 		*p++ = "rev-list";
-		*p++ = "--objects";
+		*p++ = use_thin_pack ? "--objects-edge" : "--objects";
 		if (create_full_pack || MAX_NEEDS <= nr_needs)
 			*p++ = "--all";
 		else {
@@ -192,6 +195,8 @@ static int receive_needs(void)
 			    "expected to get sha, not '%s'", line);
 		if (strstr(line+45, "multi_ack"))
 			multi_ack = 1;
+		if (strstr(line+45, "thin-pack"))
+			use_thin_pack = 1;
 
 		/* We have sent all our refs already, and the other end
 		 * should have chosen out of them; otherwise they are
@@ -213,7 +218,7 @@ static int receive_needs(void)
 
 static int send_ref(const char *refname, const unsigned char *sha1)
 {
-	static char *capabilities = "multi_ack";
+	static char *capabilities = "multi_ack thin-pack";
 	struct object *o = parse_object(sha1);
 
 	if (!o)