syntax = "proto2";

package cockroach.proto;

option go_package = "proto";

// RemoteOffset keeps track of this client's estimate of its offset from a
//  remote server. Error is the maximum error in the reading of this offset, so
//  that the real offset should be in the interval [Offset - Error, Offset
//  + Error]. If the last heartbeat timed out, Offset = InfiniteOffset.
//  Offset and error are measured using the remote clock reading technique
//  described in http://se.inf.tu-dresden.de/pubs/papers/SRDS1994.pdf, page 6.
message RemoteOffset {
  // The estimated offset from the remote server, in nanoseconds.
  optional int64 offset = 1;
  // The maximum error of the measured offset, in nanoseconds.
  optional int64 error = 2;
  // Measurement time, in nanoseconds from unix epoch.
  optional int64 measured_at = 3;
}

// A PingRequest specifies the string to echo in response.
//  Fields are exported so that they will be serialized in the rpc call.
message PingRequest {
  // Echo this string with PingResponse.
  optional string ping = 1;
  // The last offset the client measured with the server.
  optional .cockroach.proto.RemoteOffset offset = 2;
  // The address of the client.
  optional string addr = 3;
}

// A PingResponse contains the echoed ping request string.
message PingResponse {
  // An echo of value sent with PingRequest.
  optional string pong = 1;
  optional int64 server_time = 2;
}