Subject: [PATCH] index-pack: remove fetch_if_missing=0

From: Kousik Sanagavarapu <[email-masked]>
Date: Sat, 25 Feb 2023 10:54:39 +0530

A collision test is triggered in sha1_object(), whenever there is an
object file in our repo. If our repo is a partial clone, then checking
for this file existence has the behavior of lazy-fetching the object
because we have one or more promisor remotes.

This behavior is controlled by setting fetch_if_missing to 0, but this
global was added in the first place as a temporary measure to suppress
the fetching of missing objects and can be removed once the commands
have been taught to handle these cases.

Hence, use has_object() to check for the existence of an object, which
has the default behavior of not lazy-fetching in a partial clone.

Signed-off-by: Kousik Sanagavarapu <[email-masked]>
---
 builtin/index-pack.c     | 11 +----------
 t/t5616-partial-clone.sh | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 6648f2daef..8c0f36a49e 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -800,8 +800,7 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 
 	if (startup_info->have_repository) {
 		read_lock();
-		collision_test_needed =
-			has_object_file_with_flags(oid, OBJECT_INFO_QUICK);
+		collision_test_needed = has_object(the_repository, oid, 0);
 		read_unlock();
 	}
 
@@ -1728,14 +1727,6 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 	int report_end_of_input = 0;
 	int hash_algo = 0;
 
-	/*
-	 * index-pack never needs to fetch missing objects except when
-	 * REF_DELTA bases are missing (which are explicitly handled). It only
-	 * accesses the repo to do hash collision checks and to check which
-	 * REF_DELTA bases need to be fetched.
-	 */
-	fetch_if_missing = 0;
-
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(index_pack_usage);
 
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 037941b95d..4658ce0866 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -644,6 +644,34 @@ test_expect_success 'repack does not loosen promisor objects' '
 	grep "loosen_unused_packed_objects/loosened:0" trace
 '
 
+test_expect_success 'index-pack does not lazy-fetch when checking for sha1 collisions' '
+	rm -rf server promisor-remote client &&
+	rm -rf object-count &&
+
+	git init server &&
+	for i in 1 2 3 4
+	do
+		echo $i >$(pwd)/server/file$i &&
+		git -C server add file$i &&
+		git -C server commit -am "Commit $i" || return 1
+	done &&
+	git -C server config --local uploadpack.allowFilter 1 &&
+	git -C server config --local uploadpack.allowAnySha1InWant 1 &&
+	HASH=$(git -C server hash-object file3) &&
+
+	git init promisor-remote &&
+	git -C promisor-remote fetch --keep "file://$(pwd)/server" $HASH &&
+
+	git clone --no-checkout --filter=blob:none "file://$(pwd)/server" client &&
+	git -C client remote set-url origin "file://$(pwd)/promisor-remote" &&
+	git -C client config extensions.partialClone 1 &&
+	git -C client config remote.origin.promisor 1 &&
+
+	# make sure that index-pack is run from within the repository
+	git -C client index-pack $(pwd)/client/.git/objects/pack/*.pack &&
+	test_path_is_missing $(pwd)/client/file3
+'
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
-- 
2.25.1