From 7e52f5660e542cf801e8fc6902a30cc572c13736 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Sat, 7 Apr 2012 06:30:09 -0400
Subject: [PATCH 1/4] gc: do not explode objects which will be immediately
 pruned

When we pack everything into one big pack with "git repack
-Ad", any unreferenced objects in to-be-deleted packs are
exploded into loose objects, with the intent that they will
be examined and possibly cleaned up by the next run of "git
prune".

Since the exploded objects will receive the mtime of the
pack from which they come, if the source pack is old, those
loose objects will end up pruned immediately. In that case,
it is much more efficient to skip the exploding step
entirely for these objects.

This patch teaches pack-objects to receive the expiration
information and avoid writing these objects out. It also
teaches "git gc" to pass the value of gc.pruneexpire to
repack (which in turn learns to pass it along to
pack-objects) so that this optimization happens
automatically during "git gc" and "git gc --auto".

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/gc.c                         | 23 +++++++++++++++--------
 builtin/pack-objects.c               | 25 +++++++++++++++++++++++--
 git-repack.sh                        | 10 +++++++++-
 t/t7701-repack-unpack-unreachable.sh | 14 ++++++++++++++
 4 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 271376d82b..1bc2fe336e 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -144,6 +144,19 @@ static int too_many_packs(void)
 	return gc_auto_pack_limit <= cnt;
 }
 
+static void add_repack_all_option(void)
+{
+	if (prune_expire && !strcmp(prune_expire, "now"))
+		append_option(argv_repack, "-a", MAX_ADD);
+	else {
+		append_option(argv_repack, "-A", MAX_ADD);
+		if (prune_expire) {
+			append_option(argv_repack, "--unpack-unreachable", MAX_ADD);
+			append_option(argv_repack, prune_expire, MAX_ADD);
+		}
+	}
+}
+
 static int need_to_gc(void)
 {
 	/*
@@ -160,10 +173,7 @@ static int need_to_gc(void)
 	 * there is no need.
 	 */
 	if (too_many_packs())
-		append_option(argv_repack,
-			      prune_expire && !strcmp(prune_expire, "now") ?
-			      "-a" : "-A",
-			      MAX_ADD);
+		add_repack_all_option();
 	else if (!too_many_loose_objects())
 		return 0;
 
@@ -227,10 +237,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 					"run \"git gc\" manually. See "
 					"\"git help gc\" for more information.\n"));
 	} else
-		append_option(argv_repack,
-			      prune_expire && !strcmp(prune_expire, "now")
-			      ? "-a" : "-A",
-			      MAX_ADD);
+		add_repack_all_option();
 
 	if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
 		return error(FAILED_RUN, argv_pack_refs[0]);
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 7b07c092cc..1861093e9d 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -63,6 +63,7 @@ static uint32_t nr_objects, nr_alloc, nr_result, nr_written;
 static int non_empty;
 static int reuse_delta = 1, reuse_object = 1;
 static int keep_unreachable, unpack_unreachable, include_tag;
+static unsigned long unpack_unreachable_expiration;
 static int local;
 static int incremental;
 static int ignore_packed_keep;
@@ -2249,6 +2250,10 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
 		if (!p->pack_local || p->pack_keep)
 			continue;
 
+		if (unpack_unreachable_expiration &&
+		    p->mtime < unpack_unreachable_expiration)
+			continue;
+
 		if (open_pack_index(p))
 			die("cannot open pack index");
 
@@ -2315,6 +2320,21 @@ static int option_parse_index_version(const struct option *opt,
 	return 0;
 }
 
+static int option_parse_unpack_unreachable(const struct option *opt,
+					   const char *arg, int unset)
+{
+	if (unset) {
+		unpack_unreachable = 0;
+		unpack_unreachable_expiration = 0;
+	}
+	else {
+		unpack_unreachable = 1;
+		if (arg)
+			unpack_unreachable_expiration = approxidate(arg);
+	}
+	return 0;
+}
+
 static int option_parse_ulong(const struct option *opt,
 			      const char *arg, int unset)
 {
@@ -2392,8 +2412,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			 "include tag objects that refer to objects to be packed"),
 		OPT_BOOL(0, "keep-unreachable", &keep_unreachable,
 			 "keep unreachable objects"),
-		OPT_BOOL(0, "unpack-unreachable", &unpack_unreachable,
-			 "unpack unreachable objects"),
+		{ OPTION_CALLBACK, 0, "unpack-unreachable", NULL, "time",
+		  "unpack unreachable objects newer than <time>",
+		  PARSE_OPT_OPTARG, option_parse_unpack_unreachable },
 		OPT_BOOL(0, "thin", &thin,
 			 "create thin packs"),
 		OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep,
diff --git a/git-repack.sh b/git-repack.sh
index 624feec26f..757933174e 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -15,6 +15,7 @@ F               pass --no-reuse-object to git-pack-objects
 n               do not run git-update-server-info
 q,quiet         be quiet
 l               pass --local to git-pack-objects
+unpack-unreachable=  with -A, do not loosen objects older than this
  Packing constraints
 window=         size of the window used for delta compression
 window-memory=  same as the above, but limit memory size instead of entries count
@@ -33,6 +34,8 @@ do
 	-a)	all_into_one=t ;;
 	-A)	all_into_one=t
 		unpack_unreachable=--unpack-unreachable ;;
+	--unpack-unreachable)
+		unpack_unreachable="--unpack-unreachable=$2"; shift ;;
 	-d)	remove_redundant=t ;;
 	-q)	GIT_QUIET=t ;;
 	-f)	no_reuse=--no-reuse-delta ;;
@@ -76,7 +79,12 @@ case ",$all_into_one," in
 		if test -n "$existing" -a -n "$unpack_unreachable" -a \
 			-n "$remove_redundant"
 		then
-			args="$args $unpack_unreachable"
+			# This may have arbitrary user arguments, so we
+			# have to protect it against whitespace splitting
+			# when it gets run as "pack-objects $args" later.
+			# Fortunately, we know it's an approxidate, so we
+			# can just use dots instead.
+			args="$args $(echo "$unpack_unreachable" | tr ' ' .)"
 		fi
 	fi
 	;;
diff --git a/t/t7701-repack-unpack-unreachable.sh b/t/t7701-repack-unpack-unreachable.sh
index 200ab61278..b8d4cdea8c 100755
--- a/t/t7701-repack-unpack-unreachable.sh
+++ b/t/t7701-repack-unpack-unreachable.sh
@@ -95,4 +95,18 @@ test_expect_success 'unpacked objects receive timestamp of pack file' '
 	compare_mtimes < mtimes
 '
 
+test_expect_success 'do not bother loosening old objects' '
+	obj1=$(echo one | git hash-object -w --stdin) &&
+	obj2=$(echo two | git hash-object -w --stdin) &&
+	pack1=$(echo $obj1 | git pack-objects .git/objects/pack/pack) &&
+	pack2=$(echo $obj2 | git pack-objects .git/objects/pack/pack) &&
+	git prune-packed &&
+	git cat-file -p $obj1 &&
+	git cat-file -p $obj2 &&
+	test-chmtime =-86400 .git/objects/pack/pack-$pack2.pack &&
+	git repack -A -d --unpack-unreachable=1.hour.ago &&
+	git cat-file -p $obj1 &&
+	test_must_fail git cat-file -p $obj2
+'
+
 test_done

From fd93d2e60ea66fc3796904ff53ead3ef4755b137 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Wed, 18 Apr 2012 14:08:49 -0700
Subject: [PATCH 2/4] argv-array: refactor empty_argv initialization

An empty argv-array is initialized to point to a static
empty NULL-terminated array.  The original implementation
separates the actual storage of the NULL-terminator from the
pointer to the list.  This makes the exposed type a "const
char **", which nicely matches the type stored by the
argv-array.

However, this indirection means that one cannot use
empty_argv to initialize a static variable, since it is
not a constant.

Instead, we can expose empty_argv directly, as an array of
pointers. The only place we use it is in the ARGV_ARRAY_INIT
initializer, and it decays to a pointer appropriately there.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 argv-array.c | 3 +--
 argv-array.h | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/argv-array.c b/argv-array.c
index a4e04201e6..110a61b93a 100644
--- a/argv-array.c
+++ b/argv-array.c
@@ -2,8 +2,7 @@
 #include "argv-array.h"
 #include "strbuf.h"
 
-static const char *empty_argv_storage = NULL;
-const char **empty_argv = &empty_argv_storage;
+const char *empty_argv[] = { NULL };
 
 void argv_array_init(struct argv_array *array)
 {
diff --git a/argv-array.h b/argv-array.h
index 74dd2b1bc0..c45c698d53 100644
--- a/argv-array.h
+++ b/argv-array.h
@@ -1,7 +1,7 @@
 #ifndef ARGV_ARRAY_H
 #define ARGV_ARRAY_H
 
-extern const char **empty_argv;
+extern const char *empty_argv[];
 
 struct argv_array {
 	const char **argv;

From d15bbe1379a12e2d9a5f18f7dc96b38afafc6c5d Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Wed, 18 Apr 2012 14:10:05 -0700
Subject: [PATCH 3/4] argv-array: add a new "pushl" method

It can be convenient to push many strings in a single line
(e.g., if you are initializing an array with defaults). This
patch provides a convenience wrapper to allow this.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/technical/api-argv-array.txt |  5 +++++
 argv-array.c                               | 11 +++++++++++
 argv-array.h                               |  1 +
 3 files changed, 17 insertions(+)

diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt
index 49b3d52952..1b7d8f140c 100644
--- a/Documentation/technical/api-argv-array.txt
+++ b/Documentation/technical/api-argv-array.txt
@@ -37,6 +37,11 @@ Functions
 `argv_array_push`::
 	Push a copy of a string onto the end of the array.
 
+`argv_array_pushl`::
+	Push a list of strings onto the end of the array. The arguments
+	should be a list of `const char *` strings, terminated by a NULL
+	argument.
+
 `argv_array_pushf`::
 	Format a string and push it onto the end of the array. This is a
 	convenience wrapper combining `strbuf_addf` and `argv_array_push`.
diff --git a/argv-array.c b/argv-array.c
index 110a61b93a..0b5f8898a1 100644
--- a/argv-array.c
+++ b/argv-array.c
@@ -38,6 +38,17 @@ void argv_array_pushf(struct argv_array *array, const char *fmt, ...)
 	argv_array_push_nodup(array, strbuf_detach(&v, NULL));
 }
 
+void argv_array_pushl(struct argv_array *array, ...)
+{
+	va_list ap;
+	const char *arg;
+
+	va_start(ap, array);
+	while((arg = va_arg(ap, const char *)))
+		argv_array_push(array, arg);
+	va_end(ap);
+}
+
 void argv_array_clear(struct argv_array *array)
 {
 	if (array->argv != empty_argv) {
diff --git a/argv-array.h b/argv-array.h
index c45c698d53..b93a69c36c 100644
--- a/argv-array.h
+++ b/argv-array.h
@@ -15,6 +15,7 @@ void argv_array_init(struct argv_array *);
 void argv_array_push(struct argv_array *, const char *);
 __attribute__((format (printf,2,3)))
 void argv_array_pushf(struct argv_array *, const char *fmt, ...);
+void argv_array_pushl(struct argv_array *, ...);
 void argv_array_clear(struct argv_array *);
 
 #endif /* ARGV_ARRAY_H */

From 234587fc87b156dc20461fc61353beeb904b43bc Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Wed, 18 Apr 2012 14:10:19 -0700
Subject: [PATCH 4/4] gc: use argv-array for sub-commands

git-gc executes many sub-commands. The argument list for
some of these is constant, but for others we add more
arguments at runtime. The latter is implemented by allocating
a constant extra number of NULLs, and either using a custom
append function, or just referencing unused slots by number.

As of commit 7e52f56, which added two new arguments, it is
possible to exceed the constant number of slots for "repack"
by running "git gc --aggressive", causing "git gc" to die.

This patch converts all of the static argv lists to use
argv-array. In addition to fixing the overflow caused by
7e52f56, it has a few advantages:

  1. We can drop the custom append function (which,
     incidentally, had an off-by-one error exacerbating the
     static limit).

  2. We can drop the ugly magic numbers used when adding
     arguments to "prune".

  3. Adding further arguments will be easier; you can just
     add new "push" calls without worrying about increasing
     any static limits.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/gc.c | 78 ++++++++++++++++++++++------------------------------
 1 file changed, 33 insertions(+), 45 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 1bc2fe336e..9b4232c8f3 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -14,6 +14,7 @@
 #include "cache.h"
 #include "parse-options.h"
 #include "run-command.h"
+#include "argv-array.h"
 
 #define FAILED_RUN "failed to run %s"
 
@@ -28,12 +29,11 @@ static int gc_auto_threshold = 6700;
 static int gc_auto_pack_limit = 50;
 static const char *prune_expire = "2.weeks.ago";
 
-#define MAX_ADD 10
-static const char *argv_pack_refs[] = {"pack-refs", "--all", "--prune", NULL};
-static const char *argv_reflog[] = {"reflog", "expire", "--all", NULL};
-static const char *argv_repack[MAX_ADD] = {"repack", "-d", "-l", NULL};
-static const char *argv_prune[] = {"prune", "--expire", NULL, NULL, NULL};
-static const char *argv_rerere[] = {"rerere", "gc", NULL};
+static struct argv_array pack_refs_cmd = ARGV_ARRAY_INIT;
+static struct argv_array reflog = ARGV_ARRAY_INIT;
+static struct argv_array repack = ARGV_ARRAY_INIT;
+static struct argv_array prune = ARGV_ARRAY_INIT;
+static struct argv_array rerere = ARGV_ARRAY_INIT;
 
 static int gc_config(const char *var, const char *value, void *cb)
 {
@@ -67,19 +67,6 @@ static int gc_config(const char *var, const char *value, void *cb)
 	return git_default_config(var, value, cb);
 }
 
-static void append_option(const char **cmd, const char *opt, int max_length)
-{
-	int i;
-
-	for (i = 0; cmd[i]; i++)
-		;
-
-	if (i + 2 >= max_length)
-		die(_("Too many options specified"));
-	cmd[i++] = opt;
-	cmd[i] = NULL;
-}
-
 static int too_many_loose_objects(void)
 {
 	/*
@@ -147,13 +134,11 @@ static int too_many_packs(void)
 static void add_repack_all_option(void)
 {
 	if (prune_expire && !strcmp(prune_expire, "now"))
-		append_option(argv_repack, "-a", MAX_ADD);
+		argv_array_push(&repack, "-a");
 	else {
-		append_option(argv_repack, "-A", MAX_ADD);
-		if (prune_expire) {
-			append_option(argv_repack, "--unpack-unreachable", MAX_ADD);
-			append_option(argv_repack, prune_expire, MAX_ADD);
-		}
+		argv_array_push(&repack, "-A");
+		if (prune_expire)
+			argv_array_pushf(&repack, "--unpack-unreachable=%s", prune_expire);
 	}
 }
 
@@ -187,7 +172,6 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	int aggressive = 0;
 	int auto_gc = 0;
 	int quiet = 0;
-	char buf[80];
 
 	struct option builtin_gc_options[] = {
 		OPT__QUIET(&quiet, "suppress progress reporting"),
@@ -202,6 +186,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(builtin_gc_usage, builtin_gc_options);
 
+	argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
+	argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
+	argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
+	argv_array_pushl(&prune, "prune", "--expire", NULL );
+	argv_array_pushl(&rerere, "rerere", "gc", NULL);
+
 	git_config(gc_config, NULL);
 
 	if (pack_refs < 0)
@@ -213,15 +203,13 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		usage_with_options(builtin_gc_usage, builtin_gc_options);
 
 	if (aggressive) {
-		append_option(argv_repack, "-f", MAX_ADD);
-		append_option(argv_repack, "--depth=250", MAX_ADD);
-		if (aggressive_window > 0) {
-			sprintf(buf, "--window=%d", aggressive_window);
-			append_option(argv_repack, buf, MAX_ADD);
-		}
+		argv_array_push(&repack, "-f");
+		argv_array_push(&repack, "--depth=250");
+		if (aggressive_window > 0)
+			argv_array_pushf(&repack, "--window=%d", aggressive_window);
 	}
 	if (quiet)
-		append_option(argv_repack, "-q", MAX_ADD);
+		argv_array_push(&repack, "-q");
 
 	if (auto_gc) {
 		/*
@@ -239,25 +227,25 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	} else
 		add_repack_all_option();
 
-	if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
-		return error(FAILED_RUN, argv_pack_refs[0]);
+	if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
+		return error(FAILED_RUN, pack_refs_cmd.argv[0]);
 
-	if (run_command_v_opt(argv_reflog, RUN_GIT_CMD))
-		return error(FAILED_RUN, argv_reflog[0]);
+	if (run_command_v_opt(reflog.argv, RUN_GIT_CMD))
+		return error(FAILED_RUN, reflog.argv[0]);
 
-	if (run_command_v_opt(argv_repack, RUN_GIT_CMD))
-		return error(FAILED_RUN, argv_repack[0]);
+	if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
+		return error(FAILED_RUN, repack.argv[0]);
 
 	if (prune_expire) {
-		argv_prune[2] = prune_expire;
+		argv_array_push(&prune, prune_expire);
 		if (quiet)
-			argv_prune[3] = "--no-progress";
-		if (run_command_v_opt(argv_prune, RUN_GIT_CMD))
-			return error(FAILED_RUN, argv_prune[0]);
+			argv_array_push(&prune, "--no-progress");
+		if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
+			return error(FAILED_RUN, prune.argv[0]);
 	}
 
-	if (run_command_v_opt(argv_rerere, RUN_GIT_CMD))
-		return error(FAILED_RUN, argv_rerere[0]);
+	if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
+		return error(FAILED_RUN, rerere.argv[0]);
 
 	if (auto_gc && too_many_loose_objects())
 		warning(_("There are too many unreachable loose objects; "