Function workLoop

packages/scheduler/src/forks/Scheduler.js:188–258

(initialTime: number)

}

function workLoop(initialTime: number) {
  let currentTime = initialTime;
  advanceTimers(currentTime);
  currentTask = peek(taskQueue);
  while (currentTask !== null) {
    if (!enableAlwaysYieldScheduler) {
      if (currentTask.expirationTime > currentTime && shouldYieldToHost()) {
        // This currentTask hasn't expired, and we've reached the deadline.
        break;
      }
    }
    // $FlowFixMe[incompatible-use] found when upgrading Flow
    const callback = currentTask.callback;
    if (typeof callback === 'function') {
      // $FlowFixMe[incompatible-use] found when upgrading Flow
      currentTask.callback = null;
      // $FlowFixMe[incompatible-use] found when upgrading Flow
      currentPriorityLevel = currentTask.priorityLevel;
      // $FlowFixMe[incompatible-use] found when upgrading Flow
      const didUserCallbackTimeout = currentTask.expirationTime <= currentTime;
      if (enableProfiling) {
        // $FlowFixMe[incompatible-call] found when upgrading Flow
        markTaskRun(currentTask, currentTime);
      }
      const continuationCallback = callback(didUserCallbackTimeout);
      currentTime = getCurrentTime();
      if (typeof continuationCallback === 'function') {
        // If a continuation is returned, immediately yield to the main thread
        // regardless of how much time is left in the current time slice.
        // $FlowFixMe[incompatible-use] found when upgrading Flow
        currentTask.callback = continuationCallback;
        if (enableProfiling) {
          // $FlowFixMe[incompatible-call] found when upgrading Flow
          markTaskYield(currentTask, currentTime);
        }
        advanceTimers(currentTime);
        return true;
      } else {
        if (enableProfiling) {
          // $FlowFixMe[incompatible-call] found when upgrading Flow
          markTaskCompleted(currentTask, currentTime);
          // $FlowFixMe[incompatible-use] found when upgrading Flow
          currentTask.isQueued = false;
        }
        if (currentTask === peek(taskQueue)) {
          pop(taskQueue);
        }
        advanceTimers(currentTime);
      }
    } else {
      pop(taskQueue);
    }
    currentTask = peek(taskQueue);
    if (enableAlwaysYieldScheduler) {
      if (currentTask === null || currentTask.expirationTime > currentTime) {
        // This currentTask hasn't expired we yield to the browser task.
        break;
      }