code: private void cancelAllInQueue() {
          if (Config.DEBUG) {
              Log.v(TAG, "cancelAllInQueue()");
          }
          long start = SystemClock.elapsedRealtime();
          final Collection<ITaskRunnable> tasks = mTasks.values();
          for (ITaskRunnable task : tasks) {
              if (task != null) {
                  task.cancel();
              }
          }
          synchronized (mLock) {
              mTasks.clear();
              mGroups.clear();
          }
          if (Config.DEBUG) {
              final long time = SystemClock.elapsedRealtime() - start;
              Log.v(TAG, "cancelAllInQueue() using " + time + "ms");
          }
      }
docs: 取消所有的Runnable对应的任务