Method runTask

packages/zone.js/lib/zone-impl.ts:920–978

(task: Task, applyThis?: any, applyArgs?: any)

    }

    runTask(task: Task, applyThis?: any, applyArgs?: any): any {
      if (task.zone != this) {
        throw new Error(
          'A task can only be run in the zone of creation! (Creation: ' +
            (task.zone || NO_ZONE).name +
            '; Execution: ' +
            this.name +
            ')',
        );
      }

      const zoneTask = task as ZoneTask<any>;
      // https://github.com/angular/zone.js/issues/778, sometimes eventTask
      // will run in notScheduled(canceled) state, we should not try to
      // run such kind of task but just return
      const {type, data: {isPeriodic = false, isRefreshable = false} = {}} = task;

      if (task.state === notScheduled && (type === eventTask || type === macroTask)) {
        return;
      }

      const reEntryGuard = task.state != running;
      reEntryGuard && zoneTask._transitionTo(running, scheduled);
      const previousTask = _currentTask;
      _currentTask = zoneTask;
      _currentZoneFrame = {parent: _currentZoneFrame, zone: this};

      try {
        if (type == macroTask && task.data && !isPeriodic && !isRefreshable) {
          task.cancelFn = undefined;
        }
        try {
          return this._zoneDelegate.invokeTask(this, zoneTask, applyThis, applyArgs);
        } catch (error) {
          if (this._zoneDelegate.handleError(this, error)) {
            throw error;
          }
        }
      } finally {
        // if the task's state is notScheduled or unknown, then it has already been cancelled
        // we should not reset the state to scheduled
        const state = task.state;
        if (state !== notScheduled && state !== unknown) {
          if (type == eventTask || isPeriodic || (isRefreshable && state === scheduling)) {
            reEntryGuard && zoneTask._transitionTo(scheduled, running, scheduling);
          } else {
            const zoneDelegates = zoneTask._zoneDelegates;
            this._updateTaskCount(zoneTask, -1);
            reEntryGuard && zoneTask._transitionTo(notScheduled, running, notScheduled);

            if (isRefreshable) {
              zoneTask._zoneDelegates = zoneDelegates;
            }
          }
        }
        _currentZoneFrame = _currentZoneFrame.parent!;
        _currentTask = previousTask;
      }