pack-objects: reuse on-disk deltas for thin "have" objects

diff --git a/pack-objects.h b/pack-objects.h
index edf74dabddfdb2b67bad803d1c898e93a3af4d8b..3fd10b15c95c6c04c12671674f9f609b341c8cc5 100644 (file)
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -2,6 +2,7 @@
 #define PACK_OBJECTS_H
 
 #include "object-store.h"
+#include "pack.h"
 
 #define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
 
@@ -110,6 +111,7 @@ struct object_entry {
        unsigned dfs_state:OE_DFS_STATE_BITS;
        unsigned char in_pack_header_size;
        unsigned depth:OE_DEPTH_BITS;
+       unsigned ext_base:1; /* delta_idx points outside packlist */
 
        /*
         * pahole results on 64-bit linux (gcc and clang)
@@ -140,6 +142,14 @@ struct packing_data {
        struct packed_git **in_pack_by_idx;
        struct packed_git **in_pack;
 
+       /*
+        * This list contains entries for bases which we know the other side
+        * has (e.g., via reachability bitmaps), but which aren't in our
+        * "objects" list.
+        */
+       struct object_entry *ext_bases;
+       uint32_t nr_ext, alloc_ext;
+
        uintmax_t oe_size_limit;
 };
 
@@ -227,9 +237,12 @@ static inline struct object_entry *oe_delta(
                const struct packing_data *pack,
                const struct object_entry *e)
 {
-       if (e->delta_idx)
+       if (!e->delta_idx)
+               return NULL;
+       if (e->ext_base)
+               return &pack->ext_bases[e->delta_idx - 1];
+       else
                return &pack->objects[e->delta_idx - 1];
-       return NULL;
 }
 
 static inline void oe_set_delta(struct packing_data *pack,
@@ -242,6 +255,10 @@ static inline void oe_set_delta(struct packing_data *pack,
                e->delta_idx = 0;
 }
 
+void oe_set_delta_ext(struct packing_data *pack,
+                     struct object_entry *e,
+                     const unsigned char *sha1);
+
 static inline struct object_entry *oe_delta_child(
                const struct packing_data *pack,
                const struct object_entry *e)