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(* Modules that are implemented in the protocol *)

(** Module encapsulating the protocol-dependent functions:

    [do_rpc] performs
    the call to /chains/<chain_id>/blocks/<block>/context/raw/bytes/

    [split_key] potentially rewrites requests to retrieve
    a parent key of the actual key. This heuristic is also protocol-dependent.
  *)
module type PROTO_RPC = sig
  (** When about to do a RPC request, how to modify the request;
    to possibly request a parent tree of the key, to batch
    successive requests into one.

    For example when requesting baking_rights, there's the following
    sequence of requests (for carthage):

    v1;constants
    v1;first_level

    To speed things up, this function returns "v1" on any of these keys,
    to do a single request instead of two. This list is arbitrary. It was
    built by initial input from \@klakplok and by experimenting. When
    the proxy server was introduced, this function was generalized
    to split differently according to the mode.

    This function guarantees that if it returns Some(prefix, suffix) then
    [prefix @@ suffix = key].
  *)
  val split_key :
    Proxy.mode ->
    Tezos_protocol_environment.Proxy_context.M.key ->
    (Tezos_protocol_environment.Proxy_context.M.key
    * Tezos_protocol_environment.Proxy_context.M.key)
    option

  (** [failure_is_permanent key] means that, if the request 
      [rpc get /chains/<chain_id>/blocks/<block_id>/context/raw/bytes/key]
      fails once, then it should not be retried; because this key is known
      to be missing all the time. It is safe to return always [false].
      Returning [true] for some keys will reduce the number of RPC calls. *)
  val failure_is_permanent :
    Tezos_protocol_environment.Proxy_context.M.key -> bool

  val do_rpc :
    Proxy.proxy_getter_input ->
    Tezos_protocol_environment.Proxy_context.M.key ->
    Tezos_context_sigs.Context.Proof_types.raw_context tzresult Lwt.t
end

type proto_rpc = (module PROTO_RPC)