pack: introduce a delta base cache

Many delta bases are re-used. Cache them to avoid inflating the same
data repeatedly.

This version doesn't limit the amount of entries to store, so it can
end up using a considerable amound of memory.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/pack.h b/src/pack.h
index bbfcca591..0f795f6f4 100644
--- a/src/pack.h
+++ b/src/pack.h
@@ -53,6 +53,15 @@ struct git_pack_idx_header {
 	uint32_t idx_version;
 };
 
+typedef struct git_pack_cache_entry {
+	git_off_t off;
+	git_rawobj raw;
+} git_pack_cache_entry;
+
+#include "offmap.h"
+
+GIT__USE_OFFMAP;
+
 struct git_pack_file {
 	git_mwindow_file mwf;
 	git_map index_map;
@@ -68,6 +77,8 @@ struct git_pack_file {
 	git_vector cache;
 	git_oid **oids;
 
+	git_offmap *bases; /* delta base cache */
+
 	/* something like ".git/objects/pack/xxxxx.pack" */
 	char pack_name[GIT_FLEX_ARRAY]; /* more */
 };