Merge branch 'jc/autogc'

* jc/autogc:
  git-gc --auto: run "repack -A -d -l" as necessary.
  git-gc --auto: restructure the way "repack" command line is built.
  git-gc --auto: protect ourselves from accumulated cruft
  git-gc --auto: add documentation.
  git-gc --auto: move threshold check to need_to_gc() function.
  repack -A -d: use --keep-unreachable when repacking
  pack-objects --keep-unreachable
  Export matches_pack_name() and fix its return value
  Invoke "git gc --auto" from commit, merge, am and rebase.
  Implement git gc --auto

11 files changed, 276 insertions, 14 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index f59fbb3024..eebb0b6ba2 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -439,6 +439,19 @@ gc.aggressiveWindow::
 	algorithm used by 'git gc --aggressive'.  This defaults
 	to 10.
 
+gc.auto::
+	When there are approximately more than this many loose
+	objects in the repository, `git gc --auto` will pack them.
+	Some Porcelain commands use this command to perform a
+	light-weight garbage collection from time to time.  Setting
+	this to 0 disables it.
+
+gc.autopacklimit::
+	When there are more than this many packs that are not
+	marked with `*.keep` file in the repository, `git gc
+	--auto` consolidates them into one larger pack.  Setting
+	this to 0 disables this.
+
 gc.packrefs::
 	`git gc` does not run `git pack-refs` in a bare repository by
 	default so that older dumb-transport clients can still fetch
diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index c7742ca963..b9d5660eac 100644
--- a/Documentation/git-gc.txt
+++ b/Documentation/git-gc.txt
@@ -8,7 +8,7 @@ git-gc - Cleanup unnecessary files and optimize the local repository
 
 SYNOPSIS
 --------
-'git-gc' [--prune] [--aggressive]
+'git-gc' [--prune] [--aggressive] [--auto]
 
 DESCRIPTION
 -----------
@@ -43,6 +43,20 @@ OPTIONS
 	persistent, so this option only needs to be used occasionally; every
 	few hundred changesets or so.
 
+--auto::
+	With this option, `git gc` checks if there are too many
+	loose objects in the repository and runs
+	gitlink:git-repack[1] with `-d -l` option to pack them.
+	The threshold for loose objects is set with `gc.auto` configuration
+	variable, and can be disabled by setting it to 0.  Some
+	Porcelain commands use this after they perform operation
+	that could create many loose objects automatically.
+	Additionally, when there are too many packs are present,
+	they are consolidated into one larger pack by running
+	the `git-repack` command with `-A` option.  The
+	threshold for number of packs is set with
+	`gc.autopacklimit` configuration variable.
+
 Configuration
 -------------
 
diff --git a/builtin-gc.c b/builtin-gc.c
index 9397482610..23ad2b6a21 100644
--- a/builtin-gc.c
+++ b/builtin-gc.c
@@ -20,6 +20,8 @@ static const char builtin_gc_usage[] = "git-gc [--prune] [--aggressive]";
 
 static int pack_refs = 1;
 static int aggressive_window = -1;
+static int gc_auto_threshold = 6700;
+static int gc_auto_pack_limit = 20;
 
 #define MAX_ADD 10
 static const char *argv_pack_refs[] = {"pack-refs", "--all", "--prune", NULL};
@@ -41,6 +43,14 @@ static int gc_config(const char *var, const char *value)
 		aggressive_window = git_config_int(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "gc.auto")) {
+		gc_auto_threshold = git_config_int(var, value);
+		return 0;
+	}
+	if (!strcmp(var, "gc.autopacklimit")) {
+		gc_auto_pack_limit = git_config_int(var, value);
+		return 0;
+	}
 	return git_default_config(var, value);
 }
 
@@ -57,10 +67,113 @@ static void append_option(const char **cmd, const char *opt, int max_length)
 	cmd[i] = NULL;
 }
 
+static int too_many_loose_objects(void)
+{
+	/*
+	 * Quickly check if a "gc" is needed, by estimating how
+	 * many loose objects there are.  Because SHA-1 is evenly
+	 * distributed, we can check only one and get a reasonable
+	 * estimate.
+	 */
+	char path[PATH_MAX];
+	const char *objdir = get_object_directory();
+	DIR *dir;
+	struct dirent *ent;
+	int auto_threshold;
+	int num_loose = 0;
+	int needed = 0;
+
+	if (gc_auto_threshold <= 0)
+		return 0;
+
+	if (sizeof(path) <= snprintf(path, sizeof(path), "%s/17", objdir)) {
+		warning("insanely long object directory %.*s", 50, objdir);
+		return 0;
+	}
+	dir = opendir(path);
+	if (!dir)
+		return 0;
+
+	auto_threshold = (gc_auto_threshold + 255) / 256;
+	while ((ent = readdir(dir)) != NULL) {
+		if (strspn(ent->d_name, "0123456789abcdef") != 38 ||
+		    ent->d_name[38] != '\0')
+			continue;
+		if (++num_loose > auto_threshold) {
+			needed = 1;
+			break;
+		}
+	}
+	closedir(dir);
+	return needed;
+}
+
+static int too_many_packs(void)
+{
+	struct packed_git *p;
+	int cnt;
+
+	if (gc_auto_pack_limit <= 0)
+		return 0;
+
+	prepare_packed_git();
+	for (cnt = 0, p = packed_git; p; p = p->next) {
+		char path[PATH_MAX];
+		size_t len;
+		int keep;
+
+		if (!p->pack_local)
+			continue;
+		len = strlen(p->pack_name);
+		if (PATH_MAX <= len + 1)
+			continue; /* oops, give up */
+		memcpy(path, p->pack_name, len-5);
+		memcpy(path + len - 5, ".keep", 6);
+		keep = access(p->pack_name, F_OK) && (errno == ENOENT);
+		if (keep)
+			continue;
+		/*
+		 * Perhaps check the size of the pack and count only
+		 * very small ones here?
+		 */
+		cnt++;
+	}
+	return gc_auto_pack_limit <= cnt;
+}
+
+static int need_to_gc(void)
+{
+	int ac = 0;
+
+	/*
+	 * Setting gc.auto and gc.autopacklimit to 0 or negative can
+	 * disable the automatic gc.
+	 */
+	if (gc_auto_threshold <= 0 && gc_auto_pack_limit <= 0)
+		return 0;
+
+	/*
+	 * If there are too many loose objects, but not too many
+	 * packs, we run "repack -d -l".  If there are too many packs,
+	 * we run "repack -A -d -l".  Otherwise we tell the caller
+	 * there is no need.
+	 */
+	argv_repack[ac++] = "repack";
+	if (too_many_packs())
+		argv_repack[ac++] = "-A";
+	else if (!too_many_loose_objects())
+		return 0;
+	argv_repack[ac++] = "-d";
+	argv_repack[ac++] = "-l";
+	argv_repack[ac++] = NULL;
+	return 1;
+}
+
 int cmd_gc(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	int prune = 0;
+	int auto_gc = 0;
 	char buf[80];
 
 	git_config(gc_config);
@@ -82,12 +195,24 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			}
 			continue;
 		}
-		/* perhaps other parameters later... */
+		if (!strcmp(arg, "--auto")) {
+			auto_gc = 1;
+			continue;
+		}
 		break;
 	}
 	if (i != argc)
 		usage(builtin_gc_usage);
 
+	if (auto_gc) {
+		/*
+		 * Auto-gc should be least intrusive as possible.
+		 */
+		prune = 0;
+		if (!need_to_gc())
+			return 0;
+	}
+
 	if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
 		return error(FAILED_RUN, argv_pack_refs[0]);
 
@@ -103,5 +228,9 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (run_command_v_opt(argv_rerere, RUN_GIT_CMD))
 		return error(FAILED_RUN, argv_rerere[0]);
 
+	if (auto_gc && too_many_loose_objects())
+		warning("There are too many unreachable loose objects; "
+			"run 'git prune' to remove them.");
+
 	return 0;
 }
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index a15906bdb2..0be539ed7f 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -25,7 +25,7 @@ git-pack-objects [{ -q | --progress | --all-progress }] \n\
 	[--window=N] [--window-memory=N] [--depth=N] \n\
 	[--no-reuse-delta] [--no-reuse-object] [--delta-base-offset] \n\
 	[--threads=N] [--non-empty] [--revs [--unpacked | --all]*] [--reflog] \n\
-	[--stdout | base-name] [<ref-list | <object-list]";
+	[--stdout | base-name] [--keep-unreachable] [<ref-list | <object-list]";
 
 struct object_entry {
 	struct pack_idx_entry idx;
@@ -61,7 +61,7 @@ static struct object_entry **written_list;
 static uint32_t nr_objects, nr_alloc, nr_result, nr_written;
 
 static int non_empty;
-static int no_reuse_delta, no_reuse_object;
+static int no_reuse_delta, no_reuse_object, keep_unreachable;
 static int local;
 static int incremental;
 static int allow_ofs_delta;
@@ -1807,15 +1807,19 @@ static void read_object_list_from_stdin(void)
 	}
 }
 
+#define OBJECT_ADDED (1u<<20)
+
 static void show_commit(struct commit *commit)
 {
 	add_object_entry(commit->object.sha1, OBJ_COMMIT, NULL, 0);
+	commit->object.flags |= OBJECT_ADDED;
 }
 
 static void show_object(struct object_array_entry *p)
 {
 	add_preferred_base_object(p->name);
 	add_object_entry(p->item->sha1, p->item->type, p->name, 0);
+	p->item->flags |= OBJECT_ADDED;
 }
 
 static void show_edge(struct commit *commit)
@@ -1823,6 +1827,86 @@ static void show_edge(struct commit *commit)
 	add_preferred_base(commit->object.sha1);
 }
 
+struct in_pack_object {
+	off_t offset;
+	struct object *object;
+};
+
+struct in_pack {
+	int alloc;
+	int nr;
+	struct in_pack_object *array;
+};
+
+static void mark_in_pack_object(struct object *object, struct packed_git *p, struct in_pack *in_pack)
+{
+	in_pack->array[in_pack->nr].offset = find_pack_entry_one(object->sha1, p);
+	in_pack->array[in_pack->nr].object = object;
+	in_pack->nr++;
+}
+
+/*
+ * Compare the objects in the offset order, in order to emulate the
+ * "git-rev-list --objects" output that produced the pack originally.
+ */
+static int ofscmp(const void *a_, const void *b_)
+{
+	struct in_pack_object *a = (struct in_pack_object *)a_;
+	struct in_pack_object *b = (struct in_pack_object *)b_;
+
+	if (a->offset < b->offset)
+		return -1;
+	else if (a->offset > b->offset)
+		return 1;
+	else
+		return hashcmp(a->object->sha1, b->object->sha1);
+}
+
+static void add_objects_in_unpacked_packs(struct rev_info *revs)
+{
+	struct packed_git *p;
+	struct in_pack in_pack;
+	uint32_t i;
+
+	memset(&in_pack, 0, sizeof(in_pack));
+
+	for (p = packed_git; p; p = p->next) {
+		const unsigned char *sha1;
+		struct object *o;
+
+		for (i = 0; i < revs->num_ignore_packed; i++) {
+			if (matches_pack_name(p, revs->ignore_packed[i]))
+				break;
+		}
+		if (revs->num_ignore_packed <= i)
+			continue;
+		if (open_pack_index(p))
+			die("cannot open pack index");
+
+		ALLOC_GROW(in_pack.array,
+			   in_pack.nr + p->num_objects,
+			   in_pack.alloc);
+
+		for (i = 0; i < p->num_objects; i++) {
+			sha1 = nth_packed_object_sha1(p, i);
+			o = lookup_unknown_object(sha1);
+			if (!(o->flags & OBJECT_ADDED))
+				mark_in_pack_object(o, p, &in_pack);
+			o->flags |= OBJECT_ADDED;
+		}
+	}
+
+	if (in_pack.nr) {
+		qsort(in_pack.array, in_pack.nr, sizeof(in_pack.array[0]),
+		      ofscmp);
+		for (i = 0; i < in_pack.nr; i++) {
+			struct object *o = in_pack.array[i].object;
+			add_object_entry(o->sha1, o->type, "", 0);
+		}
+	}
+	free(in_pack.array);
+}
+
 static void get_object_list(int ac, const char **av)
 {
 	struct rev_info revs;
@@ -1854,6 +1938,9 @@ static void get_object_list(int ac, const char **av)
 	prepare_revision_walk(&revs);
 	mark_edges_uninteresting(revs.commits, &revs, show_edge);
 	traverse_commit_list(&revs, show_commit, show_object);
+
+	if (keep_unreachable)
+		add_objects_in_unpacked_packs(&revs);
 }
 
 static int adjust_perm(const char *path, mode_t mode)
@@ -1983,6 +2070,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			use_internal_rev_list = 1;
 			continue;
 		}
+		if (!strcmp("--keep-unreachable", arg)) {
+			keep_unreachable = 1;
+			continue;
+		}
 		if (!strcmp("--unpacked", arg) ||
 		    !prefixcmp(arg, "--unpacked=") ||
 		    !strcmp("--reflog", arg) ||
diff --git a/cache.h b/cache.h
index 5587f7ebc7..6a49e3049b 100644
--- a/cache.h
+++ b/cache.h
@@ -531,6 +531,7 @@ extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsign
 extern unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
 extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
 extern const char *packed_object_info_detail(struct packed_git *, off_t, unsigned long *, unsigned long *, unsigned int *, unsigned char *);
+extern int matches_pack_name(struct packed_git *p, const char *name);
 
 /* Dumb servers support */
 extern int update_server_info(int);
diff --git a/git-am.sh b/git-am.sh
index 32c46d7ed4..b02ae6a76f 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -464,6 +464,8 @@ do
 		"$GIT_DIR"/hooks/post-applypatch
 	fi
 
+	git gc --auto
+
 	go_next
 done
 
diff --git a/git-commit.sh b/git-commit.sh
index c3b881bfad..fcb8443bdf 100755
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -612,6 +612,7 @@ git rerere
 
 if test "$ret" = 0
 then
+	git gc --auto
 	if test -x "$GIT_DIR"/hooks/post-commit
 	then
 		"$GIT_DIR"/hooks/post-commit
diff --git a/git-merge.sh b/git-merge.sh
index 6c513dcbdf..bf18f582da 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -82,6 +82,7 @@ finish () {
 			;;
 		*)
 			git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
+			git gc --auto
 			;;
 		esac
 		;;
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 8568a4fd42..96d8b6f8db 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -326,6 +326,8 @@ do_next () {
 	rm -rf "$DOTEST" &&
 	warn "Successfully rebased and updated $HEADNAME."
 
+	git gc --auto
+
 	exit
 }
 
diff --git a/git-repack.sh b/git-repack.sh
index 0aae1a3ed5..e72adc4d91 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -3,17 +3,19 @@
 # Copyright (c) 2005 Linus Torvalds
 #
 
-USAGE='[-a] [-d] [-f] [-l] [-n] [-q] [--max-pack-size=N] [--window=N] [--window-memory=N] [--depth=N]'
+USAGE='[-a|-A] [-d] [-f] [-l] [-n] [-q] [--max-pack-size=N] [--window=N] [--window-memory=N] [--depth=N]'
 SUBDIRECTORY_OK='Yes'
 . git-sh-setup
 
-no_update_info= all_into_one= remove_redundant=
+no_update_info= all_into_one= remove_redundant= keep_unreachable=
 local= quiet= no_reuse= extra=
 while test $# != 0
 do
 	case "$1" in
 	-n)	no_update_info=t ;;
 	-a)	all_into_one=t ;;
+	-A)	all_into_one=t
+		keep_unreachable=--keep-unreachable ;;
 	-d)	remove_redundant=t ;;
 	-q)	quiet=-q ;;
 	-f)	no_reuse=--no-reuse-object ;;
@@ -59,7 +61,13 @@ case ",$all_into_one," in
 			fi
 		done
 	fi
-	[ -z "$args" ] && args='--unpacked --incremental'
+	if test -z "$args"
+	then
+		args='--unpacked --incremental'
+	elif test -n "$keep_unreachable"
+	then
+		args="$args $keep_unreachable"
+	fi
 	;;
 esac
 
diff --git a/sha1_file.c b/sha1_file.c
index 9978a58da6..5801c3e71b 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1684,22 +1684,22 @@ off_t find_pack_entry_one(const unsigned char *sha1,
 	return 0;
 }
 
-static int matches_pack_name(struct packed_git *p, const char *ig)
+int matches_pack_name(struct packed_git *p, const char *name)
 {
 	const char *last_c, *c;
 
-	if (!strcmp(p->pack_name, ig))
-		return 0;
+	if (!strcmp(p->pack_name, name))
+		return 1;
 
 	for (c = p->pack_name, last_c = c; *c;)
 		if (*c == '/')
 			last_c = ++c;
 		else
 			++c;
-	if (!strcmp(last_c, ig))
-		return 0;
+	if (!strcmp(last_c, name))
+		return 1;
 
-	return 1;
+	return 0;
 }
 
 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
@@ -1717,7 +1717,7 @@ static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, cons
 		if (ignore_packed) {
 			const char **ig;
 			for (ig = ignore_packed; *ig; ig++)
-				if (!matches_pack_name(p, *ig))
+				if (matches_pack_name(p, *ig))
 					break;
 			if (*ig)
 				goto next;