diff mbox series

[v3,4/5] unpack-objects.c: add dry_run mode for get_data()

Message ID 20211122033220.32883-5-chiyutianyi@gmail.com (mailing list archive)
State New, archived
Headers show
Series None | expand

Commit Message

Han Xin Nov. 22, 2021, 3:32 a.m. UTC 
From: Han Xin <hanxin.hx@alibaba-inc.com>

In dry_run mode, "get_data()" is used to verify the inflation of data,
and the returned buffer will not be used at all and will be freed
immediately. Even in dry_run mode, it is dangerous to allocate a
full-size buffer for a large blob object. Therefore, only allocate a
low memory footprint when calling "get_data()" in dry_run mode.

Suggested-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Han Xin <hanxin.hx@alibaba-inc.com>
---
 builtin/unpack-objects.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 4a9466295b..8d68acd662 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -96,15 +96,16 @@  static void use(int bytes)
 	display_throughput(progress, consumed_bytes);
 }
 
-static void *get_data(unsigned long size)
+static void *get_data(unsigned long size, int dry_run)
 {
 	git_zstream stream;
-	void *buf = xmallocz(size);
+	unsigned long bufsize = dry_run ? 4096 : size;
+	void *buf = xmallocz(bufsize);
 
 	memset(&stream, 0, sizeof(stream));
 
 	stream.next_out = buf;
-	stream.avail_out = size;
+	stream.avail_out = bufsize;
 	stream.next_in = fill(1);
 	stream.avail_in = len;
 	git_inflate_init(&stream);
@@ -124,6 +125,11 @@  static void *get_data(unsigned long size)
 		}
 		stream.next_in = fill(1);
 		stream.avail_in = len;
+		if (dry_run) {
+			/* reuse the buffer in dry_run mode */
+			stream.next_out = buf;
+			stream.avail_out = bufsize;
+		}
 	}
 	git_inflate_end(&stream);
 	return buf;
@@ -323,7 +329,7 @@  static void added_object(unsigned nr, enum object_type type,
 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 				   unsigned nr)
 {
-	void *buf = get_data(size);
+	void *buf = get_data(size, dry_run);
 
 	if (!dry_run && buf)
 		write_object(nr, type, buf, size);
@@ -357,7 +363,7 @@  static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 	if (type == OBJ_REF_DELTA) {
 		oidread(&base_oid, fill(the_hash_algo->rawsz));
 		use(the_hash_algo->rawsz);
-		delta_data = get_data(delta_size);
+		delta_data = get_data(delta_size, dry_run);
 		if (dry_run || !delta_data) {
 			free(delta_data);
 			return;
@@ -396,7 +402,7 @@  static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 		if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 			die("offset value out of bound for delta base object");
 
-		delta_data = get_data(delta_size);
+		delta_data = get_data(delta_size, dry_run);
 		if (dry_run || !delta_data) {
 			free(delta_data);
 			return;