rollbar/src/browser/replay/checkoutWatchdog.js

Effortlessly track and debug errors in your JavaScript applications with Rollbar. This package includes advanced error tracking features and an intuitive interface to help you identify and fix issues more quickly.

import logger from '../../logger.js';

/**
 * Schedules forced rrweb checkouts when the recorder has been idle too long.
 *
 * Recorder notifies the watchdog whenever rrweb performs a checkout. If
 * another checkout doesn't happen within the configured window, the watchdog
 * calls `forceCheckout` so buffers stay within max pre-duration limits.
 */
export default class CheckoutWatchdog {
  _getIntervalMs;
  _forceCheckout;
  _marginMs;
  _now;

  _timerId = null;
  _lastCheckoutAt = null;
  _running = false;

  /**
   * @param {Object} params
   * @param {() => number} params.getIntervalMs - Returns checkout interval
   * @param {() => void} params.forceCheckout - Invoked to force a checkout
   * @param {number} [params.marginMs] - Safety margin before forcing checkout, default: 1000ms
   * @param {() => number} [params.now] - Clock function (primarily for tests), default: Date.now
   */
  constructor({
    getIntervalMs,
    forceCheckout,
    marginMs = 1000,
    now = () => Date.now(),
  }) {
    this._getIntervalMs = getIntervalMs;
    this._forceCheckout = forceCheckout;
    this._marginMs = marginMs;
    this._now = now;
  }

  start() {
    if (this._running) return;

    this._running = true;
    this._lastCheckoutAt = this._now();
    this._arm();
  }

  stop() {
    if (!this._running) return;

    this._running = false;
    this._lastCheckoutAt = null;
    this._clearTimer();
  }

  /**
   * Notifies the watchdog that rrweb just performed a checkout.
   *
   * @param {number} [timestamp] - Timestamp of checkout (ms)
   */
  notify(timestamp = this._now()) {
    if (!this._running) return;

    this._lastCheckoutAt = timestamp;
    this._arm();
  }

  _arm() {
    this._clearTimer();

    if (!this._running) return;

    const delay = this._getIntervalMs() + this._marginMs;
    this._timerId = setTimeout(() => this._maybeForceCheckout(), delay);
  }

  _maybeForceCheckout() {
    if (!this._running) return;

    const interval = this._getIntervalMs();
    const lastCheckoutAt = this._lastCheckoutAt ?? this._now();
    const delta = this._now() - lastCheckoutAt;

    if (delta < interval) {
      this._arm();
      return;
    }

    try {
      this._forceCheckout();
    } catch (error) {
      logger.error('Replay: Forced checkout failed', error);
    }

    this._lastCheckoutAt = this._now();
    this._arm();
  }

  _clearTimer() {
    if (this._timerId) {
      clearTimeout(this._timerId);
      this._timerId = null;
    }
  }
}