once

一. 前言 Golang sync包提供了基础的异步操作方法，包括互斥锁Mutex，执行一次Once和并发等待组WaitGroup。 本文主要介绍sync包提供的这些功能的基本使用方法。 Mutex: 互斥锁 RWMutex：读写锁 WaitGroup：并发等待组 Once：执行一次 Cond：信号量 Pool：临时对象池 Map：自带锁的map 全部： https://blog.csdn.net/chenguolinblog/article/details/90691127 来源： CSDN 作者： dengbiao1212 链接： https://blog.csdn.net/deng624796905/article/details/95318787

include():会执行括号内文件的程序； include_once():只能执行一个不重复的文件，就是说括号内的文件在页面里只能执行一次， require():会将括号内的内容读入，并将自己本身替换成这些读入的内容； require_once():区别与include和include_once的区别一样,号内的文件在页面里只能执行一次， include与require的区别：include执行的时候，如果括号内的文件不存在，但下方还有其他代码，会报错并且继续往下执行。 反之require,当她没有检测到包含文件的时候会直接停止运行 include和require还有一个区别是如果一串代码有十个include（XX.php）,那么他就会查询十次，而require写100次，也只查询一次，所以require比include的执行速度快. 来源： https://www.cnblogs.com/-lilin/p/11868082.html

简介 Kafka是基于发布订阅的消息系统。最初起源于LinkedIn，于2011年成为开源Apache项目，然后于2012年成为Apache顶级项目。Kafka用Scala和Java编写，因其分布式可扩展架构及可持久化、高吞吐率特征而被广泛使用。 消息队列 通常在项目中，我们会因为如下需求而引入消息队列模块： 1.解耦：消息系统相当于在处理过程中间插入了一个隐含的、基于数据的接口层。无需预先定义不同的接口地址和请求应答规范，这允许数据上下游独立决定双方的处理过程，只需要约定数据格式即可任意扩展服务类型和业务需求。 2.缓冲：消息系统作为一个缓冲池，应对常见的访问量不均衡情形。比如特殊节假日的流量剧增和每日不同时段的访问量差异。以及处理不同数据类型所需的不同实时性。使整个业务处理架构以较低成本获得一定灵活性。 3. 异步：很多时候，用户不想也不需要立即处理消息。消息队列提供了异步处理机制，允许用户把一个消息放入队列，但并不立即处理它。想向队列中放入多少消息就放多少，然后在需要的时候再去处理它们。 Kafka的特点 作为一种分布式的，基于发布/订阅的消息系统。Kafka的主要设计目标如下： 1.以时间复杂度为O(1)的方式提供消息持久化能力，即使对TB级以上数据也能保证常数时间复杂度的访问性能。 2.高吞吐率。即使在非常廉价的商用机器上也能做到单机支持每秒100K条以上消息的传输。 3

1.$on 在构造器外部添加事件 $on接收2个参数，第一个参数是调用时的事件名称，第二个参数是匿名方法 1 app.$on('reduce',function(){ 2 console.log('执行了reduce()'); 3 this.count--; 4 }) 2.$once执行一次的事件 1 app.$once('reduceOnce',function(){ 2 console.log('只执行一次的方法'); 3 this.count--; 4 }); 3.$off关闭事件 1 function off(){ 2 console.log('关闭事件'); 3 app.$off('reduce'); 4 } 4.$emit事件调用 1 function reduce() { 2 // 事件调用 3 console.log('emit事件调用'); 4 app.$emit('reduce'); 5 } 来源： https://www.cnblogs.com/zhuangxiaobin/p/11812035.html

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: Continuing some helpful StackOverflow debugging , I have a zombie I need to track down: 2010 - 08 - 22 10 : 18 : 51.111 AppName [ 106 : 307 ] *** -[ CFString release ]: message sent to deallocated instance 0x19f3b0 How would one find the variable name or whathaveyou for the 0x19f3b0 Zombie? 回答1: Run the Allocations instrument, and enable "NSZombie Detection" and also turn on "track release/retain". Then as you are running, when the zombie is encountered, it pops up an alert and lets you drill down to explore what code released and

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I am working on a multi website system which uses Cassandra to handle all of its data needs. When I first install a website, it adds 3918 pages (and growing) with many fields, attachments such as JS files, links between pages, etc. At some point, my test "cluster" (one node) decides that the data is coming to fast and it times out or worst, Cassandra "crashes" because of an out of memory (OOM). More or less, from what I can see the 2Gb of RAM allocated by Cassandra fills up and then, more often than not, Cassandra does not control

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm currently trying to fetch the medoo framework so that I can begin easily retrieving data from my MySQL database... and for some reason it doesn't work! here's the code of my signin.php file <?php function loginUserAccount($loginname, $password){ // Include Medoo (configured) require_once 'medoo.min.php'; // Initialize $database = new medoo(); $email = $database->get('MM_Users', 'Email', [ 'ID' => 1 ]); return $email; } ?> And the error: Parse error: syntax error, unexpected 'require_once' (T_REQUIRE_ONCE), expecting function (T_FUNCTION)

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Am binding my Facebox requests just how the documentation says on the Facebox website. But after I click one of the div.comment's the Facebox request doesn't work again. The code I am using is just below and further down is my error. $(document).ready(function() { $('.comment').bind('click', function() { $.facebox({ajax: '/project/cake_app/comment/tweets/' + $(this).attr('id')}); }); }); Error: Uncaught TypeError: Object function (a,b){return new d.fn.init(a,b,g)} has no method 'facebox' 回答1: The reason Kim's suggestion to replace the bind()

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: This question is built off my previous 2. I've been working to get a rank-ordered list for my turtles, ranked by an owned factor. They're then required to move in ranked order. That part works perfectly fine, and the code can be found at: Assigning turtles a ranked number in netlogo The problem: using that code, they're moving in the correct order but instead of moving once, the program seems to be continuously re-running it for every turtle in the list so the first turtle in a world of 10 ends up moving 10 times, the second moves 9 times,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I want to run some task (i.e. get my web site news page) periodically (once a week/ a day), even if my application is closed. Is it possible? 回答1: Yes it is, you need to look at the AlarmManager to setup a reoccurring "Alarm". This is better for battery life on the device, as unlike a service it does not run constantly in the background. The Alarm triggers a broadcast receiver which will execute your custom code. As a final note - there are enum values for the timing of the Alarm including daily, half daily and many more although you can