<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[arkblue的专栏]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/arkblue</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; arkblue]]></copyright><item><title><![CDATA[mysql 时间字段加减一秒]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/131888555</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/131888555</guid><author>arkblue</author><pubDate>Mon, 24 Jul 2023 09:08:39 +0800</pubDate><description><![CDATA[update i_customer set updated_time = DATE_SUB(updated_time, INTERVAL 1 SECOND) where id  < 1000;Mysql时间加减函数为date_add（）、date_sub（）set @dt = now();
select date_add(@dt, interval 1 day);   - 加1天
select date_add(@dt, interval 1 hour);   -加1小时
select date_add(@]]></description><category></category></item><item><title><![CDATA[最近的图书]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/115302448</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/115302448</guid><author>arkblue</author><pubDate>Mon, 29 Mar 2021 15:22:16 +0800</pubDate><description><![CDATA[one billion customers

城市大脑 -- 到底能不能 十分之一的资源 养活城市

2016年诞生 城市大脑
]]></description><category></category></item><item><title><![CDATA[find xargs]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/108473806</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/108473806</guid><author>arkblue</author><pubDate>Tue, 08 Sep 2020 17:50:23 +0800</pubDate><description><![CDATA[find /etc -name "*"| xargs grep "hello abcserver"
]]></description><category></category></item><item><title><![CDATA[[转]eclipse libraries 不存在maven的依赖包时]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/98481361</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/98481361</guid><author>arkblue</author><pubDate>Mon, 05 Aug 2019 11:31:02 +0800</pubDate><description><![CDATA[eclipse libraries 不存在maven的依赖包时，照着下面一步步来

1.项目右键-》Build Path -》 Java Build Path -》Libraries -》Add Library -》Maven Managed Dependences-》点击Next -》点击‘Maven Project settings’ ， 在‘Active Maven Profiles (co...]]></description><category></category></item><item><title><![CDATA[Plugin execution not covered by lifecycle configuration]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/78779300</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/78779300</guid><author>arkblue</author><pubDate>Tue, 12 Dec 2017 10:13:02 +0800</pubDate><description><![CDATA[Plugin execution not covered by lifecycle configuration: org.apache.maven.plugins:maven-compiler-plugin: 2.5.1:compile (execution: default-compile, phase: compile) 




        
            
     ]]></description><category></category></item><item><title><![CDATA[Can not find the tag library descriptor for “http://java.sun.com/jsp/jstl/core”]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/78772769</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/78772769</guid><author>arkblue</author><pubDate>Mon, 11 Dec 2017 15:00:06 +0800</pubDate><description><![CDATA[dependencies>
    dependency>
        groupId>javax.servletgroupId>
        artifactId>servlet-apiartifactId>
        version>2.5version>
    dependency>
    dependency>
        groupId>javax.servlet.]]></description><category></category></item><item><title><![CDATA[redis 源码--跳表]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/78045207</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/78045207</guid><author>arkblue</author><pubDate>Wed, 20 Sep 2017 20:39:54 +0800</pubDate><description><![CDATA[1 先参考这个文章，跳表原理 http://blog.youkuaiyun.com/u014427196/article/details/52454462]]></description><category></category></item><item><title><![CDATA[回车换行的起源 \d\a]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77946361</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77946361</guid><author>arkblue</author><pubDate>Tue, 12 Sep 2017 16:07:42 +0800</pubDate><description><![CDATA[一、”回车”（Carriage Return）和“换行”（Line Feed）起源

首先，弄清两个概念：

回车CR-将光标移动到当前行的开头。
换行LF-将光标“垂直”移动到下一行，而并不移动到下一行的开头，即不改变光标水平位置。


在计算机还没有出现之前，有一种叫做电传打字机（Teletype Model 33，Linux/Unix下的tty概念也来自于此）的玩意，每秒钟可]]></description><category></category></item><item><title><![CDATA[redis源码 -ziplist]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77841166</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77841166</guid><author>arkblue</author><pubDate>Mon, 04 Sep 2017 19:59:52 +0800</pubDate><description><![CDATA[注释的翻译:
/* The ziplist is a specially encoded dually linked list that is designed
 * to be very memory efficient. It stores both strings and integer values,
 * where integers are encoded as actual int]]></description><category></category></item><item><title><![CDATA[redis 源码 -- intset]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77592306</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77592306</guid><author>arkblue</author><pubDate>Sat, 26 Aug 2017 10:07:09 +0800</pubDate><description><![CDATA[1 数据结构
     （1）content是已经排序
     （2）是数组类型，紧凑
     （3）encoding描述16字节、32字节、64字节
typedef struct intset {
    uint32_t encoding;
    uint32_t length;
    int8_t contents[];
} intset;        ecoding的取值]]></description><category></category></item><item><title><![CDATA[redis - 源码 endianconv 大端、小端与网络字节序]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77531856</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77531856</guid><author>arkblue</author><pubDate>Thu, 24 Aug 2017 23:42:02 +0800</pubDate><description><![CDATA[1. 什么是大端,什么是小端:

       所谓的大端模式，是指数据的低位保存在内存的高地址中，而数据的高位，保存在内存的低地址中；
       所谓的小端模式，是指数据的低位保存在内存的低地址中，而数据的高位保存在内存的高地址中。

     
大端（Big-Endian），小端（Little-Endian）以及网络字节序的概念在编程中经常会遇到，其中网络字节序(Network]]></description><category></category></item><item><title><![CDATA[redis --持久化rio]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77430104</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77430104</guid><author>arkblue</author><pubDate>Sun, 20 Aug 2017 16:44:30 +0800</pubDate><description><![CDATA[rio是对流式IO的抽象，提供读写接口，消费/生产具体不同的I/O设备。rdb.c就是使用抽象封装RDB的内存读写和文件读写。rio对象提供以下方法：
        read：从流读数据
        write：向流写数据
        tell ：获取当前的偏移量
        checksum：检查读写的checksum
/* rio.c is a simple strea]]></description><category></category></item><item><title><![CDATA[redis - sds 长整型转字符串--字符串逆序]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77394793</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77394793</guid><author>arkblue</author><pubDate>Sat, 19 Aug 2017 09:11:34 +0800</pubDate><description><![CDATA[有两个方法，一个转换有符号整数，另一个转换无符号整数。其中字符串逆序的算法，时间复杂度O(N)，空间复杂度O(1)，类似快速排序，使用两个游标，交换位于两端的字符。
/* Helper for sdscatlonglong() doing the actual number -> string
 * conversion. 's' must point to a string with room]]></description><category></category></item><item><title><![CDATA[redis 内存管理zmalloc]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77150873</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77150873</guid><author>arkblue</author><pubDate>Sun, 13 Aug 2017 23:37:01 +0800</pubDate><description><![CDATA[redis的zmalloc函数
// 已经使用的内存，malloc函数增加，free减少这个值
static size_t used_memory = 0;
// 线程安全，其实没用；redis是单线程模型
static int zmalloc_thread_safe = 0;
// used_memory变量作为临界区，做同步
pthread_mutex_t used_memory_mutex]]></description><category></category></item><item><title><![CDATA[redis - 简单动态字符串 sds]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/77148998</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/77148998</guid><author>arkblue</author><pubDate>Sun, 13 Aug 2017 19:43:28 +0800</pubDate><description><![CDATA[数据结构，源码：
// 最大预分配长度
#define SDS_MAX_PREALLOC (1024*1024)

#include 
#include 

// Redis没有直接使用sdshdr结构，而是定义了sds类型来操作sdshdr结构
typedef char *sds;

// redis 自定义字符串结构
struct sdshdr {
	// 当前字符串长度
    unsig]]></description><category></category></item><item><title><![CDATA[redis- 持久化-rdb]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/76946563</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/76946563</guid><author>arkblue</author><pubDate>Wed, 09 Aug 2017 09:07:41 +0800</pubDate><description><![CDATA[http://blog.youkuaiyun.com/xiejingfa/article/details/51553370


REDIS 数据存储模式有2种：cache-only,persistence;



cache-only即只做为“缓存”服务，不持久数据，数据在服务终止后将消失，此模式下也将不存在“数据恢复”的手段，是一种安全性低/效率高/容易扩展的方式；

persistenc]]></description><category></category></item><item><title><![CDATA[jar 包冲突解决办法]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/76911295</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/76911295</guid><author>arkblue</author><pubDate>Tue, 08 Aug 2017 15:39:25 +0800</pubDate><description><![CDATA[jar包冲突常见的异常为找不到类（java.lang.ClassNotFoundException）、
找不到具体方法（java.lang.NoSuchMethodError）、
字段错误（ java.lang.NoSuchFieldError）
或者类错误（java.lang.LinkageError）；



1 通过mvn dependency:tree  >  tree.tx]]></description><category></category></item><item><title><![CDATA[Linux 查看CPU信息，机器型号，内存等信息]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/76861126</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/76861126</guid><author>arkblue</author><pubDate>Mon, 07 Aug 2017 20:41:30 +0800</pubDate><description><![CDATA[https://my.oschina.net/hunterli/blog/140783

系统
# uname -a               # 查看内核/操作系统/CPU信息
# head -n 1 /etc/issue   # 查看操作系统版本
# cat /proc/cpuinfo      # 查看CPU信息
# hostname               # 查看计算机名
#]]></description><category></category></item><item><title><![CDATA[redis - shard]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/76851258</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/76851258</guid><author>arkblue</author><pubDate>Mon, 07 Aug 2017 16:52:05 +0800</pubDate><description><![CDATA[redis cluster在设计的时候，就考虑到了去中心化，去中间件，也就是说，集群中的每个节点都是平等的关系，都是对等的，每个节点都保存各自的数据和整个集群的状态。每个节点都和其他所有节点连接，而且这些连接保持活跃，这样就保证了我们只需要连接集群中的任意一个节点，就可以获取到其他节点的数据。

那么redis 是如何合理分配这些节点和数据的呢？

Redis 集群没有并使用传统的一致性哈]]></description><category></category></item><item><title><![CDATA[一条 sql group by]]></title><link>https://blog.youkuaiyun.com/arkblue/article/details/76473336</link><guid>https://blog.youkuaiyun.com/arkblue/article/details/76473336</guid><author>arkblue</author><pubDate>Mon, 31 Jul 2017 22:15:41 +0800</pubDate><description><![CDATA[查询一条记录出现的次数不等一
SELECT order_id,count(1) from table_xxx WHERE user_id = 4398048279448 and type = 2  GROUP BY order_id HAVING count(1)]]></description><category></category></item></channel></rss>