nim-raft/raft/protocol.nim

# nim-raft
# Copyright (c) 2023 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.

                        #                                       #
                        #   Raft Messages Protocol definition   #
                        #                                       #
import types
import options

type
    # Raft Node Messages OPs
    RaftMessageOps* = enum
      rmoRequestVote = 0,
      rmoAppendLogEntry = 1,
      rmoInstallSnapshot = 2                    # For dynamic adding of new Raft Nodes

    RaftMessagePayloadChecksum* = object        # Checksum probably will be a SHA3 hash not sure about this at this point
    RaftMessagePayload*[LogEntryDataType] = ref object
      data*: RaftNodeLogEntry[LogEntryDataType]
      checksum*: RaftMessagePayloadChecksum

    RaftMessage*[LogEntryDataType] = ref object of RaftMessageBase
      op*: RaftMessageOps                       # Message Op - Ask For Votes, Append Entry(ies), Install Snapshot etc.
      payload*: Option[seq[RaftMessagePayload[LogEntryDataType]]]       # Optional Message Payload(s) - e.g. log entry(ies). Will be empty for a Heart-Beat                                            # Heart-Beat will be a message with Append Entry(ies) Op and empty payload

    RaftMessageResponse*[SmStateType] = ref object of RaftMessageBase
      success*: bool                          # Indicates success/failure
      state*: Option[SmStateType]             # Raft Abstract State Machine State

    # Raft Node Client Request/Response definitions
    RaftNodeClientRequestOps = enum
      rncroRequestState = 0,
      rncroAppendNewEntry = 1

    RaftNodeClientRequest*[LogEntryDataType] = ref object
      op*: RaftNodeClientRequestOps
      payload*: Option[RaftMessagePayload[LogEntryDataType]]  # Optional RaftMessagePayload carrying a Log Entry

    RaftNodeClientResponse*[SmStateType] = ref object
      success*: bool                                      # Indicate succcess
      state*: Option[SmStateType]                         # Optional Raft Abstract State Machine State
      raftNodeRedirectId*: Option[RaftNodeId]             # Optional Raft Node ID to redirect the request to in case of failure