Merge branch 'tb/enable-cruft-packs-by-default'

When "gc" needs to retain unreachable objects, packing them into
cruft packs (instead of exploding them into loose object files) has
been offered as a more efficient option for some time.  Now the use
of cruft packs has been made the default and no longer considered
an experimental feature.

* tb/enable-cruft-packs-by-default:
  repository.h: drop unused `gc_cruft_packs`
  builtin/gc.c: make `gc.cruftPacks` enabled by default
  t/t9300-fast-import.sh: prepare for `gc --cruft` by default
  t/t6500-gc.sh: add additional test cases
  t/t6500-gc.sh: refactor cruft pack tests
  t/t6501-freshen-objects.sh: prepare for `gc --cruft` by default
  t/t5304-prune.sh: prepare for `gc --cruft` by default
  builtin/gc.c: ignore cruft packs with `--keep-largest-pack`
  builtin/repack.c: fix incorrect reference to '-C'
  pack-write.c: plug a leak in stage_tmp_packfiles()

Documentation/config/feature.txt

@@ -14,9 +14,6 @@ feature.experimental::
 +
 * `fetch.negotiationAlgorithm=skipping` may improve fetch negotiation times by
 skipping more commits at a time, reducing the number of round trips.
-+
-* `gc.cruftPacks=true` reduces disk space used by unreachable objects during
-garbage collection, preventing loose object explosions.
 
 feature.manyFiles::
 	Enable config options that optimize for repos with many files in the

Documentation/config/gc.txt

@@ -43,11 +43,11 @@ gc.autoDetach::
 	if the system supports it. Default is true.
 
 gc.bigPackThreshold::
-	If non-zero, all packs larger than this limit are kept when
-	`git gc` is run. This is very similar to `--keep-largest-pack`
-	except that all packs that meet the threshold are kept, not
-	just the largest pack. Defaults to zero. Common unit suffixes of
-	'k', 'm', or 'g' are supported.
+	If non-zero, all non-cruft packs larger than this limit are kept
+	when `git gc` is run. This is very similar to
+	`--keep-largest-pack` except that all non-cruft packs that meet
+	the threshold are kept, not just the largest pack. Defaults to
+	zero. Common unit suffixes of 'k', 'm', or 'g' are supported.
 +
 Note that if the number of kept packs is more than gc.autoPackLimit,
 this configuration variable is ignored, all packs except the base pack
@@ -84,7 +84,7 @@ gc.packRefs::
 gc.cruftPacks::
 	Store unreachable objects in a cruft pack (see
 	linkgit:git-repack[1]) instead of as loose objects. The default
-	is `false`.
+	is `true`.
 
 gc.pruneExpire::
 	When 'git gc' is run, it will call 'prune --expire 2.weeks.ago'

Documentation/git-gc.txt

@@ -54,9 +54,10 @@ other housekeeping tasks (e.g. rerere, working trees, reflog...) will
 be performed as well.
 
 
---cruft::
+--[no-]cruft::
 	When expiring unreachable objects, pack them separately into a
-	cruft pack instead of storing them as loose objects.
+	cruft pack instead of storing them as loose objects. `--cruft`
+	is on by default.
 
 --prune=<date>::
 	Prune loose objects older than date (default is 2 weeks ago,
@@ -77,9 +78,10 @@ be performed as well.
 	instance running on this repository.
 
 --keep-largest-pack::
-	All packs except the largest pack and those marked with a
-	`.keep` files are consolidated into a single pack. When this
-	option is used, `gc.bigPackThreshold` is ignored.
+	All packs except the largest non-cruft pack, any packs marked
+	with a `.keep` file, and any cruft pack(s) are consolidated into
+	a single pack. When this option is used, `gc.bigPackThreshold`
+	is ignored.
 
 AGGRESSIVE
 ----------

Documentation/gitformat-pack.txt

@@ -611,8 +611,8 @@ result of repeatedly resetting the objects' mtimes to the present time.
 
 If you are GC-ing repositories in a mixed version environment, consider omitting
 the `--cruft` option when using linkgit:git-repack[1] and linkgit:git-gc[1], and
-leaving the `gc.cruftPacks` configuration unset until all writers understand
-cruft packs.
+setting the `gc.cruftPacks` configuration to "false" until all writers
+understand cruft packs.
 
 === Alternatives
 

builtin/gc.c

@@ -50,7 +50,7 @@ static const char * const builtin_gc_usage[] = {
 
 static int pack_refs = 1;
 static int prune_reflogs = 1;
-static int cruft_packs = -1;
+static int cruft_packs = 1;
 static int aggressive_depth = 50;
 static int aggressive_window = 250;
 static int gc_auto_threshold = 6700;
@@ -221,7 +221,7 @@ static struct packed_git *find_base_packs(struct string_list *packs,
 	struct packed_git *p, *base = NULL;
 
 	for (p = get_all_packs(the_repository); p; p = p->next) {
-		if (!p->pack_local)
+		if (!p->pack_local || p->is_cruft)
 			continue;
 		if (limit) {
 			if (p->pack_size >= limit)
@@ -610,10 +610,6 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (prune_expire && parse_expiry_date(prune_expire, &dummy))
 		die(_("failed to parse prune expiry value %s"), prune_expire);
 
-	prepare_repo_settings(the_repository);
-	if (cruft_packs < 0)
-		cruft_packs = the_repository->settings.gc_cruft_packs;
-
 	if (aggressive) {
 		strvec_push(&repack, "-f");
 		if (aggressive_depth > 0)

builtin/repack.c

@@ -810,7 +810,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				N_("same as -a, pack unreachable cruft objects separately"),
 				   PACK_CRUFT),
 		OPT_STRING(0, "cruft-expiration", &cruft_expiration, N_("approxidate"),
-				N_("with -C, expire objects older than this")),
+				N_("with --cruft, expire objects older than this")),
 		OPT_BOOL('d', NULL, &delete_redundant,
 				N_("remove redundant packs, and run git-prune-packed")),
 		OPT_BOOL('f', NULL, &po_args.no_reuse_delta,

pack-write.c

@@ -314,13 +314,13 @@ static void write_mtimes_trailer(struct hashfile *f, const unsigned char *hash)
 	hashwrite(f, hash, the_hash_algo->rawsz);
 }
 
-static const char *write_mtimes_file(struct packing_data *to_pack,
-				     struct pack_idx_entry **objects,
-				     uint32_t nr_objects,
-				     const unsigned char *hash)
+static char *write_mtimes_file(struct packing_data *to_pack,
+			       struct pack_idx_entry **objects,
+			       uint32_t nr_objects,
+			       const unsigned char *hash)
 {
 	struct strbuf tmp_file = STRBUF_INIT;
-	const char *mtimes_name;
+	char *mtimes_name;
 	struct hashfile *f;
 	int fd;
 
@@ -546,7 +546,7 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
 			 char **idx_tmp_name)
 {
 	const char *rev_tmp_name = NULL;
-	const char *mtimes_tmp_name = NULL;
+	char *mtimes_tmp_name = NULL;
 
 	if (adjust_shared_perm(pack_tmp_name))
 		die_errno("unable to make temporary pack file readable");
@@ -572,6 +572,7 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
 		rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
 
 	free((char *)rev_tmp_name);
+	free(mtimes_tmp_name);
 }
 
 void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)

repo-settings.c

@@ -41,10 +41,8 @@ void prepare_repo_settings(struct repository *r)
 	repo_cfg_bool(r, "feature.experimental", &experimental, 0);
 
 	/* Defaults modified by feature.* */
-	if (experimental) {
+	if (experimental)
 		r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
-		r->settings.gc_cruft_packs = 1;
-	}
 	if (manyfiles) {
 		r->settings.index_version = 4;
 		r->settings.index_skip_hash = 1;

repository.h

@@ -33,7 +33,6 @@ struct repo_settings {
 	int commit_graph_generation_version;
 	int commit_graph_read_changed_paths;
 	int gc_write_commit_graph;
-	int gc_cruft_packs;
 	int fetch_write_commit_graph;
 	int command_requires_full_index;
 	int sparse_index;

t/t5304-prune.sh

@@ -62,11 +62,11 @@ test_expect_success 'prune --expire' '
 test_expect_success 'gc: implicit prune --expire' '
 	add_blob &&
 	test-tool chmtime =-$((2*$week-30)) $BLOB_FILE &&
-	git gc &&
+	git gc --no-cruft &&
 	verbose test $((1 + $before)) = $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE &&
 	test-tool chmtime =-$((2*$week+1)) $BLOB_FILE &&
-	git gc &&
+	git gc --no-cruft &&
 	verbose test $before = $(git count-objects | sed "s/ .*//") &&
 	test_path_is_missing $BLOB_FILE
 '
@@ -86,7 +86,7 @@ test_expect_success 'gc: refuse to start with invalid gc.pruneExpire' '
 
 test_expect_success 'gc: start with ok gc.pruneExpire' '
 	git config gc.pruneExpire 2.days.ago &&
-	git gc
+	git gc --no-cruft
 '
 
 test_expect_success 'prune: prune nonsense parameters' '
@@ -137,44 +137,44 @@ test_expect_success 'gc --no-prune' '
 	add_blob &&
 	test-tool chmtime =-$((5001*$day)) $BLOB_FILE &&
 	git config gc.pruneExpire 2.days.ago &&
-	git gc --no-prune &&
+	git gc --no-prune --no-cruft &&
 	verbose test 1 = $(git count-objects | sed "s/ .*//") &&
 	test_path_is_file $BLOB_FILE
 '
 
 test_expect_success 'gc respects gc.pruneExpire' '
 	git config gc.pruneExpire 5002.days.ago &&
-	git gc &&
+	git gc --no-cruft &&
 	test_path_is_file $BLOB_FILE &&
 	git config gc.pruneExpire 5000.days.ago &&
-	git gc &&
+	git gc --no-cruft &&
 	test_path_is_missing $BLOB_FILE
 '
 
 test_expect_success 'gc --prune=<date>' '
 	add_blob &&
 	test-tool chmtime =-$((5001*$day)) $BLOB_FILE &&
-	git gc --prune=5002.days.ago &&
+	git gc --prune=5002.days.ago --no-cruft &&
 	test_path_is_file $BLOB_FILE &&
-	git gc --prune=5000.days.ago &&
+	git gc --prune=5000.days.ago --no-cruft &&
 	test_path_is_missing $BLOB_FILE
 '
 
 test_expect_success 'gc --prune=never' '
 	add_blob &&
-	git gc --prune=never &&
+	git gc --prune=never --no-cruft &&
 	test_path_is_file $BLOB_FILE &&
-	git gc --prune=now &&
+	git gc --prune=now --no-cruft &&
 	test_path_is_missing $BLOB_FILE
 '
 
 test_expect_success 'gc respects gc.pruneExpire=never' '
 	git config gc.pruneExpire never &&
 	add_blob &&
-	git gc &&
+	git gc --no-cruft &&
 	test_path_is_file $BLOB_FILE &&
 	git config gc.pruneExpire now &&
-	git gc &&
+	git gc --no-cruft &&
 	test_path_is_missing $BLOB_FILE
 '
 
@@ -194,7 +194,7 @@ test_expect_success 'gc: prune old objects after local clone' '
 		cd aclone &&
 		verbose test 1 = $(git count-objects | sed "s/ .*//") &&
 		test_path_is_file $BLOB_FILE &&
-		git gc --prune &&
+		git gc --prune --no-cruft &&
 		verbose test 0 = $(git count-objects | sed "s/ .*//") &&
 		test_path_is_missing $BLOB_FILE
 	)
@@ -237,7 +237,7 @@ test_expect_success 'clean pack garbage with gc' '
 	>.git/objects/pack/fake2.keep &&
 	>.git/objects/pack/fake2.idx &&
 	>.git/objects/pack/fake3.keep &&
-	git gc &&
+	git gc --no-cruft &&
 	git count-objects -v 2>stderr &&
 	grep "^warning:" stderr | sort >actual &&
 	cat >expected <<\EOF &&

t/t6500-gc.sh

@@ -210,90 +210,95 @@ prepare_cruft_history () {
 	git reset HEAD^^
 }
 
-assert_cruft_packs () {
-	find .git/objects/pack -name "*.mtimes" >mtimes &&
-	sed -e 's/\.mtimes$/\.pack/g' mtimes >packs &&
-
-	test_file_not_empty packs &&
-	while read pack
-	do
-		test_path_is_file "$pack" || return 1
-	done <packs
-}
-
 assert_no_cruft_packs () {
 	find .git/objects/pack -name "*.mtimes" >mtimes &&
 	test_must_be_empty mtimes
 }
 
-test_expect_success 'gc --cruft generates a cruft pack' '
-	test_when_finished "rm -fr crufts" &&
-	git init crufts &&
-	(
-		cd crufts &&
+for argv in \
+	"gc" \
+	"-c gc.cruftPacks=true gc" \
+	"-c gc.cruftPacks=false gc --cruft"
+do
+	test_expect_success "git $argv generates a cruft pack" '
+		test_when_finished "rm -fr repo" &&
+		git init repo &&
+		(
+			cd repo &&
 
+			prepare_cruft_history &&
+			git $argv &&
+
+			find .git/objects/pack -name "*.mtimes" >mtimes &&
+			sed -e 's/\.mtimes$/\.pack/g' mtimes >packs &&
+
+			test_file_not_empty packs &&
+			while read pack
+			do
+				test_path_is_file "$pack" || return 1
+			done <packs
+		)
+	'
+done
+
+for argv in \
+	"gc --no-cruft" \
+	"-c gc.cruftPacks=false gc" \
+	"-c gc.cruftPacks=true gc --no-cruft"
+do
+	test_expect_success "git $argv does not generate a cruft pack" '
+		test_when_finished "rm -fr repo" &&
+		git init repo &&
+		(
+			cd repo &&
+
+			prepare_cruft_history &&
+			git $argv &&
+
+			assert_no_cruft_packs
+		)
+	'
+done
+
+test_expect_success '--keep-largest-pack ignores cruft packs' '
+	test_when_finished "rm -fr repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		# Generate a pack for reachable objects (of which there
+		# are 3), and one for unreachable objects (of which
+		# there are 6).
 		prepare_cruft_history &&
 		git gc --cruft &&
-		assert_cruft_packs
-	)
-'
 
-test_expect_success 'gc.cruftPacks=true generates a cruft pack' '
-	test_when_finished "rm -fr crufts" &&
-	git init crufts &&
-	(
-		cd crufts &&
+		mtimes="$(find .git/objects/pack -type f -name "pack-*.mtimes")" &&
+		sz="$(test_file_size "${mtimes%.mtimes}.pack")" &&
 
-		prepare_cruft_history &&
-		git -c gc.cruftPacks=true gc &&
-		assert_cruft_packs
-	)
-'
+		# Ensure that the cruft pack gets removed (due to
+		# `--prune=now`) despite it being the largest pack.
+		git -c gc.bigPackThreshold=$sz gc --cruft --prune=now &&
 
-test_expect_success 'feature.experimental=true generates a cruft pack' '
-	git init crufts &&
-	test_when_finished "rm -fr crufts" &&
-	(
-		cd crufts &&
-
-		prepare_cruft_history &&
-		git -c feature.experimental=true gc &&
-		assert_cruft_packs
-	)
-'
-
-test_expect_success 'feature.experimental=false allows explicit cruft packs' '
-	git init crufts &&
-	test_when_finished "rm -fr crufts" &&
-	(
-		cd crufts &&
-
-		prepare_cruft_history &&
-		git -c gc.cruftPacks=true -c feature.experimental=false gc &&
-		assert_cruft_packs
-	)
-'
-
-test_expect_success 'feature.experimental=true can be overridden' '
-	git init crufts &&
-	test_when_finished "rm -fr crufts" &&
-	(
-		cd crufts &&
-
-		prepare_cruft_history &&
-		git -c feature.expiremental=true -c gc.cruftPacks=false gc &&
 		assert_no_cruft_packs
 	)
 '
 
-test_expect_success 'feature.experimental=false avoids cruft packs by default' '
-	git init crufts &&
-	test_when_finished "rm -fr crufts" &&
+test_expect_success 'gc.bigPackThreshold ignores cruft packs' '
+	test_when_finished "rm -fr repo" &&
+	git init repo &&
 	(
-		cd crufts &&
+		cd repo &&
 
+		# Generate a pack for reachable objects (of which there
+		# are 3), and one for unreachable objects (of which
+		# there are 6).
 		prepare_cruft_history &&
-		git -c feature.experimental=false gc &&
+		git gc --cruft &&
+
+		# Ensure that the cruft pack gets removed (due to
+		# `--prune=now`) despite it being the largest pack.
+		git gc --cruft --prune=now --keep-largest-pack &&
+
 		assert_no_cruft_packs
 	)
 '

t/t6501-freshen-objects.sh

@@ -101,7 +101,7 @@ do
 	'
 
 	test_expect_success "simultaneous gc ($title)" '
-		git gc --prune=12.hours.ago
+		git gc --no-cruft --prune=12.hours.ago
 	'
 
 	test_expect_success "finish writing out commit ($title)" '
@@ -131,7 +131,7 @@ do
 	'
 
 	test_expect_success "simultaneous gc ($title)" '
-		git gc --prune=12.hours.ago
+		git gc --no-cruft --prune=12.hours.ago
 	'
 
 	# tree should have been refreshed by write-tree
@@ -151,7 +151,7 @@ test_expect_success 'do not complain about existing broken links (commit)' '
 	some message
 	EOF
 	commit=$(git hash-object -t commit -w broken-commit) &&
-	git gc -q 2>stderr &&
+	git gc --no-cruft -q 2>stderr &&
 	verbose git cat-file -e $commit &&
 	test_must_be_empty stderr
 '
@@ -161,7 +161,7 @@ test_expect_success 'do not complain about existing broken links (tree)' '
 	100644 blob $(test_oid 003)	foo
 	EOF
 	tree=$(git mktree --missing <broken-tree) &&
-	git gc -q 2>stderr &&
+	git gc --no-cruft -q 2>stderr &&
 	git cat-file -e $tree &&
 	test_must_be_empty stderr
 '
@@ -176,7 +176,7 @@ test_expect_success 'do not complain about existing broken links (tag)' '
 	this is a broken tag
 	EOF
 	tag=$(git hash-object -t tag -w broken-tag) &&
-	git gc -q 2>stderr &&
+	git gc --no-cruft -q 2>stderr &&
 	git cat-file -e $tag &&
 	test_must_be_empty stderr
 '

t/t9300-fast-import.sh

@@ -388,9 +388,7 @@ test_expect_success 'B: accept branch name "TEMP_TAG"' '
 
 	INPUT_END
 
-	test_when_finished "rm -f .git/TEMP_TAG
-		git gc
-		git prune" &&
+	test_when_finished "rm -f .git/TEMP_TAG && git gc --prune=now" &&
 	git fast-import <input &&
 	test $(test-tool ref-store main resolve-ref TEMP_TAG 0 | cut -f1 -d " " ) != "$ZERO_OID" &&
 	test $(git rev-parse main) = $(git rev-parse TEMP_TAG^)
@@ -406,8 +404,7 @@ test_expect_success 'B: accept empty committer' '
 	INPUT_END
 
 	test_when_finished "git update-ref -d refs/heads/empty-committer-1
-		git gc
-		git prune" &&
+		git gc --prune=now" &&
 	git fast-import <input &&
 	out=$(git fsck) &&
 	echo "$out" &&
@@ -452,8 +449,7 @@ test_expect_success 'B: accept and fixup committer with no name' '
 	INPUT_END
 
 	test_when_finished "git update-ref -d refs/heads/empty-committer-2
-		git gc
-		git prune" &&
+		git gc --prune=now" &&
 	git fast-import <input &&
 	out=$(git fsck) &&
 	echo "$out" &&
@@ -1778,8 +1774,7 @@ test_expect_success 'P: verbatim SHA gitlinks' '
 	INPUT_END
 
 	git branch -D sub &&
-	git gc &&
-	git prune &&
+	git gc --prune=now &&
 	git fast-import <input &&
 	test $(git rev-parse --verify subuse2) = $(git rev-parse --verify subuse1)
 '