type node_id = Node_id of string [@@unboxed]

val node_id_to_string : node_id -> string
val node_id_of_string : string -> node_id
val equal_node_id : node_id -> node_id -> bool
val compare_node_id : node_id -> node_id -> int

type incarnation = Incarnation of int [@@unboxed]

val incarnation_to_int : incarnation -> int
val incarnation_of_int : int -> incarnation
val zero_incarnation : incarnation
val compare_incarnation : incarnation -> incarnation -> int
val incr_incarnation : incarnation -> incarnation

type addr = Eio.Net.Sockaddr.datagram
type node_info = { id : node_id; addr : addr; meta : string }

val make_node_info : id:node_id -> addr:addr -> meta:string -> node_info

type member_state = Alive | Suspect | Dead

val member_state_to_string : member_state -> string

type member_snapshot = {
  node : node_info;
  state : member_state;
  incarnation : incarnation;
  state_change : Mtime.span;
}

type protocol_msg =
  | Ping of { seq : int; sender : node_info }
  | Ping_req of { seq : int; target : node_id; sender : node_info }
  | Ack of { seq : int; responder : node_info; payload : string option }
  | Alive of { node : node_info; incarnation : incarnation }
  | Suspect of {
      node : node_id;
      incarnation : incarnation;
      suspector : node_id;
    }
  | Dead of { node : node_id; incarnation : incarnation; declarator : node_id }
  | User_msg of { topic : string; payload : string; origin : node_id }

type packet = {
  cluster : string;
  primary : protocol_msg;
  piggyback : protocol_msg list;
}

type decode_error =
  | Invalid_magic
  | Unsupported_version of int
  | Truncated_message
  | Invalid_tag of int
  | Decryption_failed

val decode_error_to_string : decode_error -> string

type send_error = Node_unreachable | Timeout | Connection_reset

val send_error_to_string : send_error -> string

type node_event =
  | Join of node_info
  | Leave of node_info
  | Update of node_info
  | Suspect_event of node_info
  | Alive_event of node_info

type config = {
  bind_addr : string;
  bind_port : int;
  node_name : string option;
  protocol_interval : float;
  probe_timeout : float;
  indirect_checks : int;
  suspicion_mult : int;
  suspicion_max_timeout : float;
  retransmit_mult : int;
  udp_buffer_size : int;
  tcp_timeout : float;
  send_buffer_count : int;
  recv_buffer_count : int;
  secret_key : string;
  cluster_name : string;
}

val default_config : config

type 'a env = {
  stdenv : 'a;
  sw : Eio.Switch.t;
}
  constraint
    'a =
    < clock : _ Eio.Time.clock
    ; mono_clock : _ Eio.Time.Mono.t
    ; net : _ Eio.Net.t
    ; secure_random : _ Eio.Flow.source
    ; .. >

type stats = {
  nodes_alive : int;
  nodes_suspect : int;
  nodes_dead : int;
  msgs_sent : int;
  msgs_received : int;
  msgs_dropped : int;
  queue_depth : int;
  buffers_available : int;
  buffers_total : int;
}

val empty_stats : stats