Function onHeartbeatSucceeded

src/sdam/monitor.ts:295–336

(hello: Document)

  }

  function onHeartbeatSucceeded(hello: Document) {
    if (!('isWritablePrimary' in hello)) {
      // Provide hello-style response document.
      hello.isWritablePrimary = hello[LEGACY_HELLO_COMMAND];
    }

    // NOTE: here we use the latestRtt as this measurement corresponds with the value
    // obtained for this successful heartbeat, if there is no latestRtt, then we calculate the
    // duration
    const duration =
      isAwaitable && monitor.rttPinger
        ? (monitor.rttPinger.latestRtt ?? calculateDurationInMs(start))
        : calculateDurationInMs(start);

    monitor.addRttSample(duration);

    monitor.emitAndLogHeartbeat(
      Server.SERVER_HEARTBEAT_SUCCEEDED,
      monitor.server.topology.s.id,
      hello.connectionId,
      new ServerHeartbeatSucceededEvent(monitor.address, duration, hello, isAwaitable)
    );

    if (isAwaitable) {
      // If we are using the streaming protocol then we immediately issue another 'started'
      // event, otherwise the "check" is complete and return to the main monitor loop
      monitor.emitAndLogHeartbeat(
        Server.SERVER_HEARTBEAT_STARTED,
        monitor.server.topology.s.id,
        undefined,
        new ServerHeartbeatStartedEvent(monitor.address, true)
      );
      // We have not actually sent an outgoing handshake, but when we get the next response we
      // want the duration to reflect the time since we last heard from the server
      start = processTimeMS();
    } else {
      monitor.rttPinger?.close();
      monitor.rttPinger = undefined;

      callback(undefined, hello);
    }
  }

  const { connection } = monitor;
  if (connection && !connection.closed) {