Merge branch 'nd/fetch-into-shallow'

When there is no sufficient overlap between old and new history
during a fetch into a shallow repository, we unnecessarily sent
objects the sending side knows the receiving end has.

* nd/fetch-into-shallow:
  Add testcase for needless objects during a shallow fetch
  list-objects: mark more commits as edges in mark_edges_uninteresting
  list-objects: reduce one argument in mark_edges_uninteresting
  upload-pack: delegate rev walking in shallow fetch to pack-objects
  shallow: add setup_temporary_shallow()
  shallow: only add shallow graft points to new shallow file
  move setup_alternate_shallow and write_shallow_commits to shallow.c

Author: gitster

bisect.c

@@ -624,7 +624,7 @@ static void bisect_common(struct rev_info *revs)
 	if (prepare_revision_walk(revs))
 		die("revision walk setup failed");
 	if (revs->tree_objects)
-		mark_edges_uninteresting(revs->commits, revs, NULL);
+		mark_edges_uninteresting(revs, NULL);
 }
 
 static void exit_if_skipped_commits(struct commit_list *tried,

builtin/pack-objects.c

@@ -2378,7 +2378,7 @@ static void get_object_list(int ac, const char **av)
 
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
-	mark_edges_uninteresting(revs.commits, &revs, show_edge);
+	mark_edges_uninteresting(&revs, show_edge);
 	traverse_commit_list(&revs, show_commit, show_object, NULL);
 
 	if (keep_unreachable)

builtin/rev-list.c

@@ -336,7 +336,7 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
 	if (revs.tree_objects)
-		mark_edges_uninteresting(revs.commits, &revs, show_edge);
+		mark_edges_uninteresting(&revs, show_edge);
 
 	if (bisect_list) {
 		int reaches = reaches, all = all;

commit.h

@@ -201,6 +201,10 @@ extern struct commit_list *get_shallow_commits(struct object_array *heads,
 		int depth, int shallow_flag, int not_shallow_flag);
 extern void check_shallow_file_for_update(void);
 extern void set_alternate_shallow_file(const char *path);
+extern int write_shallow_commits(struct strbuf *out, int use_pack_protocol);
+extern void setup_alternate_shallow(struct lock_file *shallow_lock,
+				    const char **alternate_shallow_file);
+extern char *setup_temporary_shallow(void);
 
 int is_descendant_of(struct commit *, struct commit_list *);
 int in_merge_bases(struct commit *, struct commit *);

fetch-pack.c

@@ -185,36 +185,6 @@ static void consume_shallow_list(struct fetch_pack_args *args, int fd)
 	}
 }
 
-struct write_shallow_data {
-	struct strbuf *out;
-	int use_pack_protocol;
-	int count;
-};
-
-static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
-{
-	struct write_shallow_data *data = cb_data;
-	const char *hex = sha1_to_hex(graft->sha1);
-	data->count++;
-	if (data->use_pack_protocol)
-		packet_buf_write(data->out, "shallow %s", hex);
-	else {
-		strbuf_addstr(data->out, hex);
-		strbuf_addch(data->out, '\n');
-	}
-	return 0;
-}
-
-static int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
-{
-	struct write_shallow_data data;
-	data.out = out;
-	data.use_pack_protocol = use_pack_protocol;
-	data.count = 0;
-	for_each_commit_graft(write_one_shallow, &data);
-	return data.count;
-}
-
 static enum ack_type get_ack(int fd, unsigned char *result_sha1)
 {
 	int len;
@@ -796,27 +766,6 @@ static int cmp_ref_by_name(const void *a_, const void *b_)
 	return strcmp(a->name, b->name);
 }
 
-static void setup_alternate_shallow(void)
-{
-	struct strbuf sb = STRBUF_INIT;
-	int fd;
-
-	check_shallow_file_for_update();
-	fd = hold_lock_file_for_update(&shallow_lock, git_path("shallow"),
-				       LOCK_DIE_ON_ERROR);
-	if (write_shallow_commits(&sb, 0)) {
-		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
-			die_errno("failed to write to %s", shallow_lock.filename);
-		alternate_shallow_file = shallow_lock.filename;
-	} else
-		/*
-		 * is_repository_shallow() sees empty string as "no
-		 * shallow file".
-		 */
-		alternate_shallow_file = "";
-	strbuf_release(&sb);
-}
-
 static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 				 int fd[2],
 				 const struct ref *orig_ref,
@@ -897,7 +846,7 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 	if (args->stateless_rpc)
 		packet_flush(fd[1]);
 	if (args->depth > 0)
-		setup_alternate_shallow();
+		setup_alternate_shallow(&shallow_lock, &alternate_shallow_file);
 	else
 		alternate_shallow_file = NULL;
 	if (get_pack(args, fd, pack_lockfile))

http-push.c

@@ -1975,7 +1975,7 @@ int main(int argc, char **argv)
 		pushing = 0;
 		if (prepare_revision_walk(&revs))
 			die("revision walk setup failed");
-		mark_edges_uninteresting(revs.commits, &revs, NULL);
+		mark_edges_uninteresting(&revs, NULL);
 		objects_to_send = get_delta(&revs, ref_lock);
 		finish_all_active_slots();
 

list-objects.c

@@ -144,19 +144,35 @@ static void mark_edge_parents_uninteresting(struct commit *commit,
 	}
 }
 
-void mark_edges_uninteresting(struct commit_list *list,
-			      struct rev_info *revs,
-			      show_edge_fn show_edge)
+void mark_edges_uninteresting(struct rev_info *revs, show_edge_fn show_edge)
 {
-	for ( ; list; list = list->next) {
+	struct commit_list *list;
+	int i;
+
+	for (list = revs->commits; list; list = list->next) {
 		struct commit *commit = list->item;
 
 		if (commit->object.flags & UNINTERESTING) {
 			mark_tree_uninteresting(commit->tree);
+			if (revs->edge_hint && !(commit->object.flags & SHOWN)) {
+				commit->object.flags |= SHOWN;
+				show_edge(commit);
+			}
 			continue;
 		}
 		mark_edge_parents_uninteresting(commit, revs, show_edge);
 	}
+	for (i = 0; i < revs->cmdline.nr; i++) {
+		struct object *obj = revs->cmdline.rev[i].item;
+		struct commit *commit = (struct commit *)obj;
+		if (obj->type != OBJ_COMMIT || !(obj->flags & UNINTERESTING))
+			continue;
+		mark_tree_uninteresting(commit->tree);
+		if (revs->edge_hint && !(obj->flags & SHOWN)) {
+			obj->flags |= SHOWN;
+			show_edge(commit);
+		}
+	}
 }
 
 static void add_pending_tree(struct rev_info *revs, struct tree *tree)

list-objects.h

@@ -6,6 +6,6 @@ typedef void (*show_object_fn)(struct object *, const struct name_path *, const
 void traverse_commit_list(struct rev_info *, show_commit_fn, show_object_fn, void *);
 
 typedef void (*show_edge_fn)(struct commit *);
-void mark_edges_uninteresting(struct commit_list *, struct rev_info *, show_edge_fn);
+void mark_edges_uninteresting(struct rev_info *, show_edge_fn);
 
 #endif

shallow.c

@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "commit.h"
 #include "tag.h"
+#include "pkt-line.h"
 
 static int is_shallow = -1;
 static struct stat shallow_stat;
@@ -141,3 +142,81 @@ void check_shallow_file_for_update(void)
 		   )
 		die("shallow file was changed during fetch");
 }
+
+struct write_shallow_data {
+	struct strbuf *out;
+	int use_pack_protocol;
+	int count;
+};
+
+static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
+{
+	struct write_shallow_data *data = cb_data;
+	const char *hex = sha1_to_hex(graft->sha1);
+	if (graft->nr_parent != -1)
+		return 0;
+	data->count++;
+	if (data->use_pack_protocol)
+		packet_buf_write(data->out, "shallow %s", hex);
+	else {
+		strbuf_addstr(data->out, hex);
+		strbuf_addch(data->out, '\n');
+	}
+	return 0;
+}
+
+int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
+{
+	struct write_shallow_data data;
+	data.out = out;
+	data.use_pack_protocol = use_pack_protocol;
+	data.count = 0;
+	for_each_commit_graft(write_one_shallow, &data);
+	return data.count;
+}
+
+char *setup_temporary_shallow(void)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int fd;
+
+	if (write_shallow_commits(&sb, 0)) {
+		struct strbuf path = STRBUF_INIT;
+		strbuf_addstr(&path, git_path("shallow_XXXXXX"));
+		fd = xmkstemp(path.buf);
+		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
+			die_errno("failed to write to %s",
+				  path.buf);
+		close(fd);
+		strbuf_release(&sb);
+		return strbuf_detach(&path, NULL);
+	}
+	/*
+	 * is_repository_shallow() sees empty string as "no shallow
+	 * file".
+	 */
+	return xstrdup("");
+}
+
+void setup_alternate_shallow(struct lock_file *shallow_lock,
+			     const char **alternate_shallow_file)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int fd;
+
+	check_shallow_file_for_update();
+	fd = hold_lock_file_for_update(shallow_lock, git_path("shallow"),
+				       LOCK_DIE_ON_ERROR);
+	if (write_shallow_commits(&sb, 0)) {
+		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
+			die_errno("failed to write to %s",
+				  shallow_lock->filename);
+		*alternate_shallow_file = shallow_lock->filename;
+	} else
+		/*
+		 * is_repository_shallow() sees empty string as "no
+		 * shallow file".
+		 */
+		*alternate_shallow_file = "";
+	strbuf_release(&sb);
+}

t/t5500-fetch-pack.sh

@@ -393,6 +393,17 @@ test_expect_success 'fetch in shallow repo unreachable shallow objects' '
 		git fsck --no-dangling
 	)
 '
+test_expect_success 'fetch creating new shallow root' '
+	(
+		git clone "file://$(pwd)/." shallow10 &&
+		git commit --allow-empty -m empty &&
+		cd shallow10 &&
+		git fetch --depth=1 --progress 2>actual &&
+		# This should fetch only the empty commit, no tree or
+		# blob objects
+		grep "remote: Total 1" actual
+	)
+'
 
 test_expect_success 'setup tests for the --stdin parameter' '
 	for head in C D E F