pack-refs: teach pack-refs --include option

Allow users to be more selective over which refs to pack by adding an
--include option to git-pack-refs.

The existing options allow some measure of selectivity. By default
git-pack-refs packs all tags. --all can be used to include all refs,
and the previous commit added the ability to exclude certain refs with
--exclude.

While these knobs give the user some selection over which refs to pack,
it could be useful to give more control. For instance, a repository may
have a set of branches that are rarely updated and would benefit from
being packed. --include would allow the user to easily include a set of
branches to be packed while leaving everything else unpacked.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 67 insertions, 12 deletions

diff --git a/Documentation/git-pack-refs.txt b/Documentation/git-pack-refs.txt
index 546aa122df..284956acb3 100644
--- a/Documentation/git-pack-refs.txt
+++ b/Documentation/git-pack-refs.txt
@@ -8,7 +8,7 @@ git-pack-refs - Pack heads and tags for efficient repository access
 SYNOPSIS
 --------
 [verse]
-'git pack-refs' [--all] [--no-prune] [--exclude <pattern>]
+'git pack-refs' [--all] [--no-prune] [--include <pattern>] [--exclude <pattern>]
 
 DESCRIPTION
 -----------
@@ -60,6 +60,15 @@ with many branches of historical interests.
 The command usually removes loose refs under `$GIT_DIR/refs`
 hierarchy after packing them.  This option tells it not to.
 
+--include <pattern>::
+
+Pack refs based on a `glob(7)` pattern. Repetitions of this option
+accumulate inclusion patterns. If a ref is both included in `--include` and
+`--exclude`, `--exclude` takes precedence. Using `--include` will preclude all
+tags from being included by default. Symbolic refs and broken refs will never
+be packed. When used with `--all`, it will be a noop. Use `--no-include` to clear
+and reset the list of patterns.
+
 --exclude <pattern>::
 
 Do not pack refs matching the given `glob(7)` pattern. Repetitions of this option
@@ -70,6 +79,9 @@ unpack it.
 When used with `--all`, pack only loose refs which do not match any of
 the provided `--exclude` patterns.
 
+When used with `--include`, refs provided to `--include`, minus refs that are
+provided to `--exclude` will be packed.
+
 
 BUGS
 ----
diff --git a/builtin/pack-refs.c b/builtin/pack-refs.c
index 1d1a64fe38..bcf383cac9 100644
--- a/builtin/pack-refs.c
+++ b/builtin/pack-refs.c
@@ -7,7 +7,7 @@
 #include "revision.h"
 
 static char const * const pack_refs_usage[] = {
-	N_("git pack-refs [--all] [--no-prune] [--exclude <pattern>]"),
+	N_("git pack-refs [--all] [--no-prune] [--include <pattern>] [--exclude <pattern>]"),
 	NULL
 };
 
@@ -15,13 +15,18 @@ int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 {
 	unsigned int flags = PACK_REFS_PRUNE;
 	static struct ref_exclusions excludes = REF_EXCLUSIONS_INIT;
-	struct pack_refs_opts pack_refs_opts = {.exclusions = &excludes, .flags = flags};
+	static struct string_list included_refs = STRING_LIST_INIT_NODUP;
+	struct pack_refs_opts pack_refs_opts = { .exclusions = &excludes,
+						 .includes = &included_refs,
+						 .flags = flags };
 	static struct string_list option_excluded_refs = STRING_LIST_INIT_NODUP;
 	struct string_list_item *item;
 
 	struct option opts[] = {
 		OPT_BIT(0, "all",   &pack_refs_opts.flags, N_("pack everything"), PACK_REFS_ALL),
 		OPT_BIT(0, "prune", &pack_refs_opts.flags, N_("prune loose refs (default)"), PACK_REFS_PRUNE),
+		OPT_STRING_LIST(0, "include", pack_refs_opts.includes, N_("pattern"),
+			N_("references to include")),
 		OPT_STRING_LIST(0, "exclude", &option_excluded_refs, N_("pattern"),
 			N_("references to exclude")),
 		OPT_END(),
@@ -33,5 +38,11 @@ int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 	for_each_string_list_item(item, &option_excluded_refs)
 		add_ref_exclusion(pack_refs_opts.exclusions, item->string);
 
+	if (pack_refs_opts.flags & PACK_REFS_ALL)
+		string_list_append(pack_refs_opts.includes, "*");
+
+	if (!pack_refs_opts.includes->nr)
+		string_list_append(pack_refs_opts.includes, "refs/tags/*");
+
 	return refs_pack_refs(get_main_ref_store(the_repository), &pack_refs_opts);
 }
diff --git a/refs.h b/refs.h
index 46020bd335..933fdebe58 100644
--- a/refs.h
+++ b/refs.h
@@ -66,6 +66,7 @@ struct worktree;
 struct pack_refs_opts {
 	unsigned int flags;
 	struct ref_exclusions *exclusions;
+	struct string_list *includes;
 };
 
 const char *refs_resolve_ref_unsafe(struct ref_store *refs,
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 8620e01362..fcaf842ed4 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1176,18 +1176,13 @@ static int should_pack_ref(const char *refname,
 			   const struct object_id *oid, unsigned int ref_flags,
 			   struct pack_refs_opts *opts)
 {
+	struct string_list_item *item;
+
 	/* Do not pack per-worktree refs: */
 	if (parse_worktree_ref(refname, NULL, NULL, NULL) !=
 	    REF_WORKTREE_SHARED)
 		return 0;
 
-	if (ref_excluded(opts->exclusions, refname))
-		return 0;
-
-	/* Do not pack non-tags unless PACK_REFS_ALL is set: */
-	if (!(opts->flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
-		return 0;
-
 	/* Do not pack symbolic refs: */
 	if (ref_flags & REF_ISSYMREF)
 		return 0;
@@ -1196,7 +1191,14 @@ static int should_pack_ref(const char *refname,
 	if (!ref_resolves_to_object(refname, the_repository, oid, ref_flags))
 		return 0;
 
-	return 1;
+	if (ref_excluded(opts->exclusions, refname))
+		return 0;
+
+	for_each_string_list_item(item, opts->includes)
+		if (!wildmatch(item->string, refname, 0))
+			return 1;
+
+	return 0;
 }
 
 static int files_pack_refs(struct ref_store *ref_store,
diff --git a/t/helper/test-ref-store.c b/t/helper/test-ref-store.c
index de4197708d..a6977b5e83 100644
--- a/t/helper/test-ref-store.c
+++ b/t/helper/test-ref-store.c
@@ -5,6 +5,7 @@
 #include "worktree.h"
 #include "object-store.h"
 #include "repository.h"
+#include "revision.h"
 
 struct flag_definition {
 	const char *name;
@@ -116,7 +117,14 @@ static struct flag_definition pack_flags[] = { FLAG_DEF(PACK_REFS_PRUNE),
 static int cmd_pack_refs(struct ref_store *refs, const char **argv)
 {
 	unsigned int flags = arg_flags(*argv++, "flags", pack_flags);
-	struct pack_refs_opts pack_opts = { .flags = flags };
+	static struct ref_exclusions exclusions = REF_EXCLUSIONS_INIT;
+	static struct string_list included_refs = STRING_LIST_INIT_NODUP;
+	struct pack_refs_opts pack_opts = { .flags = flags,
+					    .exclusions = &exclusions,
+					    .includes = &included_refs };
+
+	if (pack_opts.flags & PACK_REFS_ALL)
+		string_list_append(pack_opts.includes, "*");
 
 	return refs_pack_refs(refs, &pack_opts);
 }
diff --git a/t/t3210-pack-refs.sh b/t/t3210-pack-refs.sh
index 925b90cd3b..9f399d2f75 100755
--- a/t/t3210-pack-refs.sh
+++ b/t/t3210-pack-refs.sh
@@ -124,6 +124,27 @@ test_expect_success 'test --no-exclude refs clears excluded refs' '
 	! test -f .git/refs/heads/dont_pack3 &&
 	! test -f .git/refs/heads/dont_pack4'
 
+test_expect_success 'test only included refs are packed' '
+	git branch pack_this1 &&
+	git branch pack_this2 &&
+	git tag dont_pack5 &&
+	git pack-refs --include "refs/heads/pack_this*" &&
+	test -f .git/refs/tags/dont_pack5 &&
+	! test -f .git/refs/heads/pack_this1 &&
+	! test -f .git/refs/heads/pack_this2'
+
+test_expect_success 'test --no-include refs clears included refs' '
+	git branch pack1 &&
+	git branch pack2 &&
+	git pack-refs --include "refs/heads/pack*" --no-include &&
+	test -f .git/refs/heads/pack1 &&
+	test -f .git/refs/heads/pack2'
+
+test_expect_success 'test --exclude takes precedence over --include' '
+	git branch dont_pack5 &&
+	git pack-refs --include "refs/heads/pack*" --exclude "refs/heads/pack*" &&
+	test -f .git/refs/heads/dont_pack5'
+
 test_expect_success \
 	'see if up-to-date packed refs are preserved' \
 	'git branch q &&