Storage: added a dedicated store for predecessors under /block/

src/lib_storage/store.ml

@@ -176,6 +176,14 @@ module Block = struct
         end
     end
 
+  module Predecessors =
+    Store_helpers.Make_map
+      (Store_helpers.Make_substore
+         (Indexed_store.Store)
+         (struct let name = ["predecessors"] end))
+      (Store_helpers.Integer_index)
+      (Store_helpers.Make_value(Block_hash))
+
 end
 
 

src/lib_storage/store.mli

@@ -121,6 +121,16 @@ module Block : sig
      and type key = Block_hash.t
      and type value = invalid_block
 
+  (**
+     Block predecessors under
+     [/blocks/<block_id>/predecessors/<distance>/<block_id>].
+     Used to compute block predecessors in [lib_node_shell/state.ml].
+  *)
+  module Predecessors : MAP_STORE
+    with type t = store * Block_hash.t
+     and type key = int
+     and type value = Block_hash.t
+
 end