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Shell/block_locator: count 'head' as a locator step

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This commit is contained in:
Grégoire Henry 2018-03-12 17:11:30 +01:00
parent ee3f81b6e3
commit 487fce8be1
1 changed files with 13 additions and 14 deletions
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27
src/lib_base/block_locator.ml
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@ -44,14 +44,14 @@ let encoding =
(req "current_head" (dynamic_size Block_header.encoding))
(req "history" (dynamic_size (list Block_hash.encoding))))
(**
Computes a locator for block [b] picking 10 times the immediate
predecessors of [b], then 10 times one predecessor every 2, then
10 times one predecessor every 4, ..., until genesis or it reaches
the desired size.
*)
(** Computes a locator for block [b] picking 10 times the immediate
predecessors of [b], then 10 times one predecessor every 2, then
10 times one predecessor every 4, ..., until genesis or it reaches
the desired size. *)
let compute ~predecessor ~genesis b header size =
if size < 0 then invalid_arg "compute: negative size" else
if size < 0 then
invalid_arg "Block_locator.compute: negative size"
else
let repeats = 10 in (* number of repetitions for each power of 2 *)
let rec loop acc size step cnt b =
if size = 0 then
@ -65,17 +65,16 @@ let compute ~predecessor ~genesis b header size =
Lwt.return (List.rev (genesis :: acc))
| Some pred ->
if cnt = 1 then
loop (pred :: acc) (size - 1)
(step * 2) repeats pred
loop (pred :: acc) (size - 1) (step * 2) repeats pred
else
loop (pred :: acc) (size - 1)
step (cnt - 1) pred
in
if size = 0 then Lwt.return (header, []) else
loop (pred :: acc) (size - 1) step (cnt - 1) pred in
if size = 0 then
Lwt.return (header, [])
else
predecessor b 1 >>= function
| None -> Lwt.return (header, [])
| Some p ->
loop [p] (size-1) 1 repeats p >>= fun hist ->
loop [p] (size-1) 1 (repeats-1) p >>= fun hist ->
Lwt.return (header, hist)
type validity =