Source file wasm_pvm_state.ml

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(* Copyright (c) 2022 Marigold <contact@marigold.dev>                        *)
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type version = V0 | V1 | V2 | V3

let versions =
  [("2.0.0", V0); ("2.0.0-r1", V1); ("2.0.0-r2", V2); ("2.0.0-r3", V3)]

let versions_flip = List.map (fun (x, y) -> (y, x)) versions

let version_encoding =
  (* This encoding is directly used by the protocol. As a consequence,
     any change done to it needs to be backward compatible!

     We cannot use [string_enum] here because [string_enum] will
     append the size of the string at the beginning of the encoded
     bytes. *)
  Data_encoding.(
    conv_with_guard
      (fun v -> Stdlib.List.assoc v versions_flip)
      (fun str ->
        match List.assoc_opt ~equal:Compare.String.equal str versions with
        | Some v -> Ok v
        | None -> Error "not a valid version")
      Variable.string)

(** Represents the location of an input message. *)
type input_info = {
  inbox_level : Tezos_base.Bounded.Non_negative_int32.t;
      (** The inbox level at which the message exists.*)
  message_counter : Z.t;  (** The index of the message in the inbox. *)
}

(** Represents the location of an output message. *)
type output_info = {
  outbox_level : Tezos_base.Bounded.Non_negative_int32.t;
      (** The outbox level at which the message exists.*)
  message_index : Z.t;  (** The index of the message in the outbox. *)
}

type reveal = Tezos_webassembly_interpreter.Host_funcs.reveal =
  | Reveal_raw of string

let reveal_raw_data_tag = '\x00'
(* Should match the tag used for [Reveal_raw_data] in the definition of
   [Sc_rollup_reveal_hash.encoding] *)

let reveal_raw_data hash =
  Reveal_raw Format.(sprintf "%c%s" reveal_raw_data_tag hash)

let reveal_metadata_payload = "\x01"
(* Should match the tag used for [Reveal_metadata] in the definition of
   [Sc_rollup_reveal_hash.encoding] *)

let reveal_metadata = Reveal_raw reveal_metadata_payload

module Compatibility = struct
  type reveal_hash = string

  (* Reveal type used in Environment 10 and before. *)
  type reveal = Reveal_raw_data of reveal_hash | Reveal_metadata

  let of_current_opt (Reveal_raw payload) =
    if 1 <= String.length payload && String.get payload 0 = reveal_raw_data_tag
    then
      Some (Reveal_raw_data (String.sub payload 1 (String.length payload - 1)))
    else if payload = reveal_metadata_payload then Some Reveal_metadata
    else None
end

(** Represents the state of input requests. *)
type input_request =
  | No_input_required  (** The VM does not expect any input. *)
  | Input_required  (** The VM needs input in order to progress. *)
  | Reveal_required of reveal

(** Represents the state of the VM. *)
type info = {
  current_tick : Z.t;
      (** The number of ticks processed by the VM, zero for the initial state.
          [current_tick] must be incremented for each call to [step] *)
  last_input_read : input_info option;
      (** The last message to be read by the VM, if any. *)
  input_request : input_request;  (** The current VM input request. *)
}

(** This module type defines the state for the PVM.
    For use in lib_scoru_wasm only. *)
module Internal_state = struct
  (** General state of the PVM

    The following describes the general state transitions.

    {[
      stateDiagram
      Collect --> Padding
      Snapshot --> Evaluation
      state Evaluation {
        Decode --> Link
        Link --> Init
        Init --> Eval
      }
      Evaluation --> Padding : evaluation succeeded
      Padding --> Snapshot : reboot flag is set
      Padding --> Collect : reboot flag is not set
      Evaluation --> Stuck : something went wrong
    ]}
  *)
  type tick_state =
    | Snapshot
    | Decode of Tezos_webassembly_interpreter.Decode.decode_kont
    | Link of {
        ast_module : Tezos_webassembly_interpreter.Ast.module_;
        externs :
          Tezos_webassembly_interpreter.Instance.extern
          Tezos_webassembly_interpreter.Instance.Vector.t;
        imports_offset : int32;
      }
    | Init of {
        self : Tezos_webassembly_interpreter.Instance.module_key;
        ast_module : Tezos_webassembly_interpreter.Ast.module_;
        init_kont : Tezos_webassembly_interpreter.Eval.init_kont;
        module_reg : Tezos_webassembly_interpreter.Instance.module_reg;
      }
    | Eval of {
        config : Tezos_webassembly_interpreter.Eval.config;
        module_reg : Tezos_webassembly_interpreter.Instance.module_reg;
      }
    | Collect
    | Stuck of Wasm_pvm_errors.t
    | Padding

  type output_buffer_parameters = {
    validity_period : int32;
        (** Number of levels an outbox is kept before being cleaned-up. *)
    message_limit : Z.t;  (** Maximum number of messages per inbox *)
  }

  type pvm_state = {
    last_input_info : input_info option;  (** Info about last read input. *)
    current_tick : Z.t;  (** Current tick of the PVM. *)
    reboot_counter : Z.t;  (** Number of reboots for the current input. *)
    durable : Durable.t;  (** The durable storage of the PVM. *)
    buffers : Tezos_webassembly_interpreter.Eval.buffers;
        (** Input and outut buffers used by the PVM host functions. *)
    tick_state : tick_state;  (** The current tick state. *)
    last_top_level_call : Z.t;
        (** Last tick corresponding to a top-level call. *)
    max_nb_ticks : Z.t;  (** Number of ticks between top level call. *)
    maximum_reboots_per_input : Z.t;
        (** Number of reboots between two inputs. *)
    output_buffer_parameters : output_buffer_parameters;
        (** Outbox paramaters defined by the protocol. *)
  }

  type computation_status =
    | Yielding
    | Forcing_yield
    | Running
    | Failing
    | Reboot
end