syntax = "proto3";

package greptime.v1.meta;

option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1/meta";

import "greptime/v1/meta/common.proto";

service Heartbeat {
  // Heartbeat, there may be many contents of the heartbeat, such as:
  // 1. Metadata to be registered to meta server and discoverable by other nodes.
  // 2. Some performance metrics, such as Load, CPU usage, etc.
  // 3. The number of computing tasks being executed.
  rpc Heartbeat(stream HeartbeatRequest) returns (stream HeartbeatResponse) {}

  // Ask leader's endpoint.
  rpc AskLeader(AskLeaderRequest) returns (AskLeaderResponse) {}
}

message HeartbeatRequest {
  RequestHeader header = 1;

  // Self peer
  Peer peer = 2;
  // Leader node
  bool is_leader = 3;
  // Actually reported time interval
  TimeInterval report_interval = 4;
  // Node stat
  NodeStat node_stat = 5;
  // Region stats on this node
  repeated RegionStat region_stats = 6;
  // Follower nodes and stats, empty on follower nodes
  repeated ReplicaStat replica_stats = 7;
  repeated MailboxMessage mailbox_messages = 8;
}

message NodeStat {
  // The read capacity units during this period
  int64 rcus = 1;
  // The write capacity units during this period
  int64 wcus = 2;
  // How many tables on this node
  int64 table_num = 3;
  // How many regions on this node
  int64 region_num = 4;

  double cpu_usage = 5;
  double load = 6;
  // Read disk IO on this node
  double read_io_rate = 7;
  // Write disk IO on this node
  double write_io_rate = 8;

  // Others
  map<string, string> attrs = 100;
}

message RegionStat {
  uint64 region_id = 1;
  TableName table_name = 2;
  // The read capacity units during this period
  int64 rcus = 3;
  // The write capacity units during this period
  int64 wcus = 4;
  // Approximate bytes of this region
  int64 approximate_bytes = 5;
  // Approximate number of rows in this region
  int64 approximate_rows = 6;

  // Others
  map<string, string> attrs = 100;
}

message ReplicaStat {
  Peer peer = 1;
  bool in_sync = 2;
  bool is_learner = 3;
}

message HeartbeatResponse {
  ResponseHeader header = 1;

  repeated MailboxMessage mailbox_messages = 2;
}

message AskLeaderRequest {
  RequestHeader header = 1;
}

message AskLeaderResponse {
  ResponseHeader header = 1;

  Peer leader = 2;
}

message MailboxMessage {
  // The id is used to associate request and response.
  uint64 id = 1;
  // The following information plays a bigger role in making messages traceable and facilitating debugging.
  string subject = 2;
  string from = 3;
  string to = 4;
  // The unix timestamp in milliseconds.
  int64 timestamp_millis = 5;

  // The message body.
  oneof payload {
    string json = 6;
  }
}