// currentTimerSalvaged的作用是标记当前这个定时器是否已经失效，在设置失效的时候我们对定时器增加过一次引用记数，这里调用release来减少那次引用记数，这样释放很安全，这里用到了这个小技巧，延迟释放，这样后面的程序不会出现非法引用定时器指针而出现错误
                    elt->currentTimer->release();
                }
 // currentTimer指针使用完了，设置成空指针
                elt->currentTimer = nullptr;
            }
        }

         elt,at this moment,is still valid
         so it is safe to ask this here (issue #490)

        // 因为下面有可能要清除这个对象currentTarget为了循环进行下去，这里先在currentTarget对象还存活的状态下找到链表的下一个指针。
        elt = (tHashTimerEntry *)elt->hh.next;

         only delete currentTarget if no actions were scheduled during the cycle (issue #481)

 如果_currentTartetSalvaged 为 true 且这个对象里面的定时器列表为空那么这个对象就没有计时任务了我们要把它从__hashForTimers列表里面删除。
        if (_currentTargetSalvaged && _currentTarget->timers->num == 0)
        {
            removeHashElement(_currentTarget);
        }
    }

     下面这三个循环也是清理工作
     updates with priority < 0
    DL_FOREACH_SAFE(_updatesNegList,255); line-height:1.5!important">if (entry->markedForDeletion)
        {
            this->removeUpdateFromHash(entry);
        }
    }

     updates with priority == 0
    DL_FOREACH_SAFE(_updates0List,0); line-height:1.5!important"> updates with priority > 0
    DL_FOREACH_SAFE(_updatesPosList,255); line-height:1.5!important">this->removeUpdateFromHash(entry);
        }
    }

    _updateHashLocked = false;
    _currentTarget = nullptr;

#if CC_ENABLE_SCRIPT_BINDING
     Script callbacks
     Iterate over all the script callbacks
    if (!_scriptHandlerEntries.empty())
    {
        for (auto i = _scriptHandlerEntries.size() - 1; i >= 0; i--)
        {
            SchedulerScriptHandlerEntry* eachEntry = _scriptHandlerEntries.at(i);
            if (eachEntry->isMarkedForDeletion())
            {
                _scriptHandlerEntries.erase(i);
            }
            else if (!eachEntry->isPaused())
            {
                eachEntry->getTimer()->update(dt);
            }
        }
    }
#endif
     上面都是对象的定时任务,这里是多线程处理函数的定时任务。
     Testing size is faster than locking / unlocking.
     And almost never there will be functions scheduled to be called. 这块作者已经说明了，函数的定时任务不常用。我们简单了解一下就可了。
    if( !_functionsToPerform.empty() ) {
        _performMutex.lock();
         fixed #4123: Save the callback functions,they must be invoked after '_performMutex.unlock()',otherwise if new functions are added in callback,it will cause thread deadlock.
        auto temp = _functionsToPerform;
        _functionsToPerform.clear();
        _performMutex.unlock();
        for( const auto &function : temp ) {
            function();
        }
        
    }
}