Merge branch 'jt/repack-local-promisor'

"git gc" discards any objects that are outside promisor packs that
are referred to by an object in a promisor pack, and we do not
refetch them from the promisor at runtime, resulting an unusable
repository.  Work it around by including these objects in the
referring promisor pack at the receiving end of the fetch.

* jt/repack-local-promisor:
  index-pack: repack local links into promisor packs
  t5300: move --window clamp test next to unclamped
  t0410: use from-scratch server
  t0410: make test description clearer

Documentation/git-index-pack.txt

@@ -139,6 +139,11 @@ include::object-format-disclaimer.txt[]
 	written. If a `<message>` is provided, then that content will be
 	written to the .promisor file for future reference. See
 	link:technical/partial-clone.html[partial clone] for more information.
++
+Also, if there are objects in the given pack that references non-promisor
+objects (in the repo), repacks those non-promisor objects into a promisor
+pack. This avoids a situation in which a repo has non-promisor objects that are
+accessible through promisor objects.
 
 NOTES
 -----

builtin/index-pack.c

@@ -9,6 +9,7 @@
 #include "csum-file.h"
 #include "blob.h"
 #include "commit.h"
+#include "tag.h"
 #include "tree.h"
 #include "progress.h"
 #include "fsck.h"
@@ -20,9 +21,14 @@
 #include "object-file.h"
 #include "object-store-ll.h"
 #include "oid-array.h"
+#include "oidset.h"
+#include "path.h"
 #include "replace-object.h"
+#include "tree-walk.h"
 #include "promisor-remote.h"
+#include "run-command.h"
 #include "setup.h"
+#include "strvec.h"
 
 static const char index_pack_usage[] =
 "git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--[no-]rev-index] [--verify] [--strict[=<msg-id>=<severity>...]] [--fsck-objects[=<msg-id>=<severity>...]] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";
@@ -148,6 +154,13 @@ static uint32_t input_crc32;
 static int input_fd, output_fd;
 static const char *curr_pack;
 
+/*
+ * local_links is guarded by read_mutex, and record_local_links is read-only in
+ * a thread.
+ */
+static struct oidset local_links = OIDSET_INIT;
+static int record_local_links;
+
 static struct thread_local *thread_data;
 static int nr_dispatched;
 static int threads_active;
@@ -799,6 +812,44 @@ static int check_collison(struct object_entry *entry)
 	return 0;
 }
 
+static void record_if_local_object(const struct object_id *oid)
+{
+	struct object_info info = OBJECT_INFO_INIT;
+	if (oid_object_info_extended(the_repository, oid, &info, 0))
+		/* Missing; assume it is a promisor object */
+		return;
+	if (info.whence == OI_PACKED && info.u.packed.pack->pack_promisor)
+		return;
+	oidset_insert(&local_links, oid);
+}
+
+static void do_record_local_links(struct object *obj)
+{
+	if (obj->type == OBJ_TREE) {
+		struct tree *tree = (struct tree *)obj;
+		struct tree_desc desc;
+		struct name_entry entry;
+		if (init_tree_desc_gently(&desc, &tree->object.oid,
+					  tree->buffer, tree->size, 0))
+			/*
+			 * Error messages are given when packs are
+			 * verified, so do not print any here.
+			 */
+			return;
+		while (tree_entry_gently(&desc, &entry))
+			record_if_local_object(&entry.oid);
+	} else if (obj->type == OBJ_COMMIT) {
+		struct commit *commit = (struct commit *) obj;
+		struct commit_list *parents = commit->parents;
+
+		for (; parents; parents = parents->next)
+			record_if_local_object(&parents->item->object.oid);
+	} else if (obj->type == OBJ_TAG) {
+		struct tag *tag = (struct tag *) obj;
+		record_if_local_object(get_tagged_oid(tag));
+	}
+}
+
 static void sha1_object(const void *data, struct object_entry *obj_entry,
 			unsigned long size, enum object_type type,
 			const struct object_id *oid)
@@ -845,7 +896,7 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 		free(has_data);
 	}
 
-	if (strict || do_fsck_object) {
+	if (strict || do_fsck_object || record_local_links) {
 		read_lock();
 		if (type == OBJ_BLOB) {
 			struct blob *blob = lookup_blob(the_repository, oid);
@@ -877,6 +928,8 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 				die(_("fsck error in packed object"));
 			if (strict && fsck_walk(obj, NULL, &fsck_options))
 				die(_("Not all child objects of %s are reachable"), oid_to_hex(&obj->oid));
+			if (record_local_links)
+				do_record_local_links(obj);
 
 			if (obj->type == OBJ_TREE) {
 				struct tree *item = (struct tree *) obj;
@@ -1719,6 +1772,58 @@ static void show_pack_info(int stat_only)
 	free(chain_histogram);
 }
 
+static void repack_local_links(void)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	FILE *out;
+	struct strbuf line = STRBUF_INIT;
+	struct oidset_iter iter;
+	struct object_id *oid;
+	char *base_name;
+
+	if (!oidset_size(&local_links))
+		return;
+
+	base_name = mkpathdup("%s/pack/pack", repo_get_object_directory(the_repository));
+
+	strvec_push(&cmd.args, "pack-objects");
+	strvec_push(&cmd.args, "--exclude-promisor-objects-best-effort");
+	strvec_push(&cmd.args, base_name);
+	cmd.git_cmd = 1;
+	cmd.in = -1;
+	cmd.out = -1;
+	if (start_command(&cmd))
+		die(_("could not start pack-objects to repack local links"));
+
+	oidset_iter_init(&local_links, &iter);
+	while ((oid = oidset_iter_next(&iter))) {
+		if (write_in_full(cmd.in, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
+		    write_in_full(cmd.in, "\n", 1) < 0)
+			die(_("failed to feed local object to pack-objects"));
+	}
+	close(cmd.in);
+
+	out = xfdopen(cmd.out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		unsigned char binary[GIT_MAX_RAWSZ];
+		if (line.len != the_hash_algo->hexsz ||
+		    !hex_to_bytes(binary, line.buf, line.len))
+			die(_("index-pack: Expecting full hex object ID lines only from pack-objects."));
+
+		/*
+		 * pack-objects creates the .pack and .idx files, but not the
+		 * .promisor file. Create the .promisor file, which is empty.
+		 */
+		write_special_file("promisor", "", NULL, binary, NULL);
+	}
+
+	fclose(out);
+	if (finish_command(&cmd))
+		die(_("could not finish pack-objects to repack local links"));
+	strbuf_release(&line);
+	free(base_name);
+}
+
 int cmd_index_pack(int argc,
 		   const char **argv,
 		   const char *prefix,
@@ -1794,7 +1899,7 @@ int cmd_index_pack(int argc,
 			} else if (skip_to_optional_arg(arg, "--keep", &keep_msg)) {
 				; /* nothing to do */
 			} else if (skip_to_optional_arg(arg, "--promisor", &promisor_msg)) {
-				; /* already parsed */
+				record_local_links = 1;
 			} else if (starts_with(arg, "--threads=")) {
 				char *end;
 				nr_threads = strtoul(arg+10, &end, 0);
@@ -1970,6 +2075,8 @@ int cmd_index_pack(int argc,
 		free((void *) curr_index);
 	free(curr_rev_index);
 
+	repack_local_links();
+
 	/*
 	 * Let the caller know this pack is not self contained
 	 */

builtin/pack-objects.c

@@ -239,6 +239,7 @@ static enum {
 static uint16_t write_bitmap_options = BITMAP_OPT_HASH_CACHE;
 
 static int exclude_promisor_objects;
+static int exclude_promisor_objects_best_effort;
 
 static int use_delta_islands;
 
@@ -4312,6 +4313,18 @@ static int option_parse_cruft_expiration(const struct option *opt UNUSED,
 	return 0;
 }
 
+static int is_not_in_promisor_pack_obj(struct object *obj, void *data UNUSED)
+{
+	struct object_info info = OBJECT_INFO_INIT;
+	if (oid_object_info_extended(the_repository, &obj->oid, &info, 0))
+		BUG("should_include_obj should only be called on existing objects");
+	return info.whence != OI_PACKED || !info.u.packed.pack->pack_promisor;
+}
+
+static int is_not_in_promisor_pack(struct commit *commit, void *data) {
+	return is_not_in_promisor_pack_obj((struct object *) commit, data);
+}
+
 int cmd_pack_objects(int argc,
 		     const char **argv,
 		     const char *prefix,
@@ -4424,6 +4437,9 @@ int cmd_pack_objects(int argc,
 		  option_parse_missing_action),
 		OPT_BOOL(0, "exclude-promisor-objects", &exclude_promisor_objects,
 			 N_("do not pack objects in promisor packfiles")),
+		OPT_BOOL(0, "exclude-promisor-objects-best-effort",
+			 &exclude_promisor_objects_best_effort,
+			 N_("implies --missing=allow-any")),
 		OPT_BOOL(0, "delta-islands", &use_delta_islands,
 			 N_("respect islands during delta compression")),
 		OPT_STRING_LIST(0, "uri-protocol", &uri_protocols,
@@ -4504,10 +4520,18 @@ int cmd_pack_objects(int argc,
 		strvec_push(&rp, "--unpacked");
 	}
 
+	if (exclude_promisor_objects && exclude_promisor_objects_best_effort)
+		die(_("options '%s' and '%s' cannot be used together"),
+		    "--exclude-promisor-objects", "--exclude-promisor-objects-best-effort");
 	if (exclude_promisor_objects) {
 		use_internal_rev_list = 1;
 		fetch_if_missing = 0;
 		strvec_push(&rp, "--exclude-promisor-objects");
+	} else if (exclude_promisor_objects_best_effort) {
+		use_internal_rev_list = 1;
+		fetch_if_missing = 0;
+		option_parse_missing_action(NULL, "allow-any", 0);
+		/* revs configured below */
 	}
 	if (unpack_unreachable || keep_unreachable || pack_loose_unreachable)
 		use_internal_rev_list = 1;
@@ -4627,6 +4651,10 @@ int cmd_pack_objects(int argc,
 
 		repo_init_revisions(the_repository, &revs, NULL);
 		list_objects_filter_copy(&revs.filter, &filter_options);
+		if (exclude_promisor_objects_best_effort) {
+			revs.include_check = is_not_in_promisor_pack;
+			revs.include_check_obj = is_not_in_promisor_pack_obj;
+		}
 		get_object_list(&revs, rp.nr, rp.v);
 		release_revisions(&revs);
 	}

t/t0410-partial-clone.sh

@@ -241,7 +241,7 @@ test_expect_success 'fetching of missing objects works with ref-in-want enabled'
 	grep "fetch< fetch=.*ref-in-want" trace
 '
 
-test_expect_success 'fetching of missing objects from another promisor remote' '
+test_expect_success 'fetching from another promisor remote' '
 	git clone "file://$(pwd)/server" server2 &&
 	test_commit -C server2 bar &&
 	git -C server2 repack -a -d --write-bitmap-index &&
@@ -264,8 +264,8 @@ test_expect_success 'fetching of missing objects from another promisor remote' '
 	grep "$HASH2" out
 '
 
-test_expect_success 'fetching of missing objects configures a promisor remote' '
+test_expect_success 'fetching with --filter configures a promisor remote' '
-	git clone "file://$(pwd)/server" server3 &&
+	test_create_repo server3 &&
 	test_commit -C server3 baz &&
 	git -C server3 repack -a -d --write-bitmap-index &&
 	HASH3=$(git -C server3 rev-parse baz) &&

t/t5300-pack-object.sh

@@ -156,6 +156,11 @@ test_expect_success 'pack without delta' '
 	check_deltas stderr = 0
 '
 
+test_expect_success 'negative window clamps to 0' '
+	git pack-objects --progress --window=-1 neg-window <obj-list 2>stderr &&
+	check_deltas stderr = 0
+'
+
 test_expect_success 'pack-objects with bogus arguments' '
 	test_must_fail git pack-objects --window=0 test-1 blah blah <obj-list
 '
@@ -630,11 +635,6 @@ test_expect_success 'prefetch objects' '
 	test_line_count = 1 donelines
 '
 
-test_expect_success 'negative window clamps to 0' '
-	git pack-objects --progress --window=-1 neg-window <obj-list 2>stderr &&
-	check_deltas stderr = 0
-'
-
 for hash in sha1 sha256
 do
 	test_expect_success "verify-pack with $hash packfile" '

t/t5616-partial-clone.sh

@@ -694,6 +694,36 @@ test_expect_success 'lazy-fetch in submodule succeeds' '
 	git -C client restore --recurse-submodules --source=HEAD^ :/
 '
 
+test_expect_success 'after fetching descendants of non-promisor commits, gc works' '
+	# Setup
+	git init full &&
+	git -C full config uploadpack.allowfilter 1 &&
+	git -C full config uploadpack.allowanysha1inwant 1 &&
+	touch full/foo &&
+	git -C full add foo &&
+	git -C full commit -m "commit 1" &&
+	git -C full checkout --detach &&
+
+	# Partial clone and push commit to remote
+	git clone "file://$(pwd)/full" --filter=blob:none partial &&
+	echo "hello" > partial/foo &&
+	git -C partial commit -a -m "commit 2" &&
+	git -C partial push &&
+
+	# gc in partial repo
+	git -C partial gc --prune=now &&
+
+	# Create another commit in normal repo
+	git -C full checkout main &&
+	echo " world" >> full/foo &&
+	git -C full commit -a -m "commit 3" &&
+
+	# Pull from remote in partial repo, and run gc again
+	git -C partial pull &&
+	git -C partial gc --prune=now
+'
+
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd