deprecate the new loose object header format

Now that we encourage and actively preserve objects in a packed form
more agressively than we did at the time the new loose object format and
core.legacyheaders were introduced, that extra loose object format
doesn't appear to be worth it anymore.

Because the packing of loose objects has to go through the delta match
loop anyway, and since most of them should end up being deltified in
most cases, there is really little advantage to have this parallel loose
object format as the CPU savings it might provide is rather lost in the
noise in the end.

This patch gets rid of core.legacyheaders, preserve the legacy format as
the only writable loose object format and deprecate the other one to
keep things simpler.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 11 insertions, 36 deletions

diff --git a/sha1_file.c b/sha1_file.c
index 32244d704e..e71552795a 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -972,7 +972,7 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 	return map;
 }
 
-int legacy_loose_object(unsigned char *map)
+static int legacy_loose_object(unsigned char *map)
 {
 	unsigned int word;
 
@@ -1034,6 +1034,14 @@ static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned lon
 		return inflate(stream, 0);
 	}
 
+
+	/*
+	 * There used to be a second loose object header format which
+	 * was meant to mimic the in-pack format, allowing for direct
+	 * copy of the object data.  This format turned up not to be
+	 * really worth it and we don't write it any longer.  But we
+	 * can still read it.
+	 */
 	used = unpack_object_header_gently(map, mapsize, &type, &size);
 	if (!used || !valid_loose_object_type[type])
 		return -1;
@@ -1962,40 +1970,6 @@ static int write_buffer(int fd, const void *buf, size_t len)
 	return 0;
 }
 
-static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
-{
-	int hdr_len;
-	unsigned char c;
-
-	c = (type << 4) | (len & 15);
-	len >>= 4;
-	hdr_len = 1;
-	while (len) {
-		*hdr++ = c | 0x80;
-		hdr_len++;
-		c = (len & 0x7f);
-		len >>= 7;
-	}
-	*hdr = c;
-	return hdr_len;
-}
-
-static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
-{
-	int obj_type, hdrlen;
-
-	if (use_legacy_headers) {
-		while (deflate(stream, 0) == Z_OK)
-			/* nothing */;
-		return;
-	}
-	obj_type = type_from_string(type);
-	hdrlen = write_binary_header(stream->next_out, obj_type, len);
-	stream->total_out = hdrlen;
-	stream->next_out += hdrlen;
-	stream->avail_out -= hdrlen;
-}
-
 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
                    unsigned char *sha1)
 {
@@ -2062,7 +2036,8 @@ int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned cha
 	/* First header.. */
 	stream.next_in = (unsigned char *)hdr;
 	stream.avail_in = hdrlen;
-	setup_object_header(&stream, type, len);
+	while (deflate(&stream, 0) == Z_OK)
+		/* nothing */;
 
 	/* Then the data itself.. */
 	stream.next_in = buf;