[PATCH 07/10] unpack-object: cache for non written objects

[Martin Koegler <mkoegler@auto.tuwien.ac.at>]

Preventing objects with broken links entering the repository
means, that write of some objects must be delayed.

This patch adds a cache to keep the object data in memory. The delta
resolving code must also search in the cache.

Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
---
 builtin-unpack-objects.c |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/builtin-unpack-objects.c b/builtin-unpack-objects.c
index 1e51865..f18c7e8 100644
--- a/builtin-unpack-objects.c
+++ b/builtin-unpack-objects.c
@@ -8,6 +8,7 @@
 #include "tag.h"
 #include "tree.h"
 #include "progress.h"
+#include "decorate.h"
 
 static int dry_run, quiet, recover, has_errors;
 static const char unpack_usage[] = "git-unpack-objects [-n] [-q] [-r] < pack-file";
@@ -18,6 +19,28 @@ static unsigned int offset, len;
 static off_t consumed_bytes;
 static SHA_CTX ctx;
 
+struct obj_buffer {
+	char *buffer;
+	unsigned long size;
+};
+
+static struct decoration obj_decorate;
+
+static struct obj_buffer *lookup_object_buffer(struct object *base)
+{
+	return lookup_decoration(&obj_decorate, base);
+}
+
+static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
+{
+	struct obj_buffer *obj;
+	obj = xcalloc(1, sizeof(struct obj_buffer));
+	obj->buffer = buffer;
+	obj->size = size;
+	if (add_decoration(&obj_decorate, object, obj))
+		die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
+}
+
 /*
  * Make sure at least "min" bytes are available in the buffer, and
  * return the pointer to the buffer.
@@ -252,6 +275,15 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 		}
 	}
 
+	struct object* obj = lookup_object(base_sha1);
+	if (obj) {
+		struct obj_buffer *obj_buf = lookup_object_buffer (obj);
+		if (obj_buf) {
+			resolve_delta(nr, obj->type, obj_buf->buffer, obj_buf->size, delta_data, delta_size);
+			return;
+		}
+	}
+
 	base = read_sha1_file(base_sha1, &type, &base_size);
 	if (!base) {
 		error("failed to read delta-pack base object %s",
-- 
1.5.4.3.g3c5f