@neurosity/sdk/dist/esm/utils/heartbeat.js

Neurosity SDK

import { combineLatest, timer } from "rxjs";
import { map, startWith, switchMap } from "rxjs/operators";
import { withLatestFrom, distinctUntilChanged } from "rxjs/operators";
import isEqual from "fast-deep-equal";
import { STATUS } from "../types/status";
const HEARTBEAT_UPDATE_INTERVAL = 30000; // 30 seconds - set by the OS
const LOST_LOCAL_HEARTBEAT_AFTER = HEARTBEAT_UPDATE_INTERVAL * 2.5; // 75 seconds
const LOST_REMOTE_HEARTBEAT_AFTER = 8.64e7; // 24 hours
export function heartbeatAwareStatus(status$) {
    const lastLocalHeartbeat$ = status$.pipe(map(({ lastHeartbeat }) => lastHeartbeat), distinctUntilChanged(), map(() => Date.now()));
    const lostHeartbeat$ = lastLocalHeartbeat$.pipe(switchMap(() => timer(LOST_LOCAL_HEARTBEAT_AFTER)), map(() => null), startWith(null));
    return combineLatest({
        status: status$,
        lostHeartbeat: lostHeartbeat$ // @important - do not remove, adeed for state synchronization, value not used
    }).pipe(withLatestFrom(lastLocalHeartbeat$), map(([{ status }, lastLocalHeartbeat]) => {
        if (!lastLocalHeartbeat) {
            return status;
        }
        const lostHeartbeat = deviceHasLostHeartbeat(status, lastLocalHeartbeat);
        return lostHeartbeat
            ? Object.assign(Object.assign({}, status), { state: STATUS.OFFLINE }) : status;
    }), distinctUntilChanged((a, b) => isEqual(a, b)));
}
export function deviceHasLostHeartbeat(status, lastLocalHeartbeat) {
    if (!("lastHeartbeat" in status)) {
        return false;
    }
    // We are converting the heartbeat to the local time because the previous
    // implementation that used the server timestamp had bug where SDK clients
    // running on hardware with drifted/out-of-sync clocks (cough cough Android)
    // would override the state to offline when the heartbeat was active.
    const lostLocalHeartbeat = Date.now() - lastLocalHeartbeat > LOST_LOCAL_HEARTBEAT_AFTER;
    if (lostLocalHeartbeat) {
        return true;
    }
    // Addresses devices with wrongful "online" state. This rarely happens, the
    // OS would have to crash without updating the state to "offline".
    const lostRemoteHeartbeat = Date.now() - status.lastHeartbeat > LOST_REMOTE_HEARTBEAT_AFTER;
    if (lostRemoteHeartbeat) {
        return true;
    }
    return false;
}