syntax = "proto3";
package raftpb;

enum EntryType {
    EntryNormal     = 0;
    EntryConfChange = 1;
}

message Entry {
	uint64     term        = 1; // must be 64-bit aligned for atomic operations
	uint64     index       = 2; // must be 64-bit aligned for atomic operations
	EntryType  entry_type  = 3;
	bytes      data        = 4;
}

message SnapshotMetadata {
    ConfState conf_state = 1;
    uint64    index      = 2;
    uint64    term       = 3;
}

message Snapshot {
    bytes            data     = 1;
    SnapshotMetadata metadata = 2;
}

message ConfState {
	repeated uint64 nodes    = 1;
	repeated uint64 learners = 2;
}

enum MessageType {
	MsgHup             = 0;
	MsgBeat            = 1;
	MsgProp            = 2;
	MsgApp             = 3;
	MsgAppResp         = 4;
	MsgVote            = 5;
	MsgVoteResp        = 6;
	MsgSnap            = 7;
	MsgHeartbeat       = 8;
	MsgHeartbeatResp   = 9;
	MsgUnreachable     = 10;
	MsgSnapStatus      = 11;
	MsgCheckQuorum     = 12;
	MsgTransferLeader  = 13;
	MsgTimeoutNow      = 14;
	MsgReadIndex       = 15;
	MsgReadIndexResp   = 16;
	MsgPreVote         = 17;
	MsgPreVoteResp     = 18;
}

message HardState {
    uint64 term   = 1;
    uint64 vote   = 2;
    uint64 commit = 3;
}

enum ConfChangeType {
	ConfChangeAddNode        = 0;
	ConfChangeRemoveNode     = 1;
	ConfChangeUpdateNode     = 2;
	ConfChangeAddLearnerNode = 3;
}

message Message {
    MessageType msg_type    = 1;
    uint64 to               = 2;
    uint64 from             = 3;
    uint64 term             = 4; // leader’s term
    uint64 log_term         = 5; // term of prevLogIndex entry
    uint64 index            = 6; // index of log entry immediately preceding new ones
    repeated Entry entries  = 7; // log entries to store (empty for heartbeat; may send more than one for efficiency)
    uint64 commit           = 8; // leader’s commitIndex
    Snapshot snapshot       = 9;
    bool reject             = 10;
    uint64 reject_hint      = 11;
    bytes context           = 12;
}

message ConfChange {
	uint64          id          = 1;
	ConfChangeType  change_type = 2;
	uint64          node_id     = 3;
	bytes           context     = 4;
}