sql复制代码-- 查看慢查询日志是否开启
show variables like '%slow_query_log%';

sql复制代码-- 开启慢查询日志，只对当前数据库生效，并且重启数据库后失效
set global slow_query_log = 1;

sql复制代码-- 查看慢查询日志的阈值，默认10s
show variables like '%long_query_time%';

sql复制代码-- 设置阈值
set long_query_time = 3;

ini复制代码[mysqld]
slow_query_log=1
slow_query_log_file=/var/lib/mysql/atguigu-slow.log
long_query_time=3
log_output=FILE

sql复制代码select sleep(4);

sql复制代码show global status like '%Slow_queries%';

shell复制代码# 得到返回记录集最多的10 个SQL
mysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log

# 得到访问次数最多的10 个SQL
mysqldumpslow -s c -t 10 /var/lib/mysql/atguigu-slow.log

# 得到按照时间排序的前10 条里面含有左连接的查询语句
mysqldumpslow -s t -t 10 -g "left join" /var/lib/mysql/atguigu-slow.log

# 另外建议在使用这些命令时结合| 和more 使用，否则有可能出现爆屏情况
mysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log | more

csharp复制代码public interface TargetInterface {
	public void save();
	
	public void print(String str);
}

typescript复制代码public class Target implements TargetInterface{
	
	public void save() {
		System.out.println("save running...");
	}
	
	public void print(String str) {
		System.out.println(str);
	}

}

csharp复制代码public class Advice {
	public void before() {
		System.out.println("前置增强");
	}

	public void after() {
		System.out.println("后置增强");
	}
}

java复制代码import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class ProxyTest {

	public static void main(String[] args) {
		
		//目标对象
		final Target target = new Target();
		
		//增强对象
		final Advice advice = new Advice();
		
		TargetInterface proxyInstance = (TargetInterface)Proxy.newProxyInstance(
				target.getClass().getClassLoader(), 					//目标对象类加载器
				target.getClass().getInterfaces(), 						//目标对象相同的接口字节码对象数组
				new InvocationHandler() {
					//调用代理对象的任何方法，实质执行的都是invoke方法
					public Object invoke(Object proxy, Method method, Object[] args) throws Throwable{
						advice.before();								//前置增强
						Object invoke = method.invoke(target, args);	//执行目标方法
						advice.after();									//后置增强
						System.out.println();
						return invoke;
					}
				});
		
		//代理对象的方法测试
		proxyInstance.save();
		
		proxyInstance.print("JDK动态代理");
	}

}

xml复制代码<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-context</artifactId>
	<version>4.2.4.RELEASE</version>
</dependency>

csharp复制代码public class Target {
	public void save() {
		System.out.println("save running...");
	}
	
	public void print(String str) {
		System.out.println(str);
	}
}

csharp复制代码public class Advice {
	
	public void before() {
		System.out.println("前置增强");
	}

	public void after() {
		System.out.println("后置增强");
	}

}

java复制代码import java.lang.reflect.Method;

import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;

public class ProxyTest {

	public static void main(String[] args) {
		final Target target = new Target();
		final Advice advice = new Advice();
		
		//返回值就是动态生成的代理对象，基于cglib
		//创建增强器
		Enhancer enhancer = new Enhancer();
		
		//设置父类（目标）
		enhancer.setSuperclass(Target.class);
		
		//设置回调
		enhancer.setCallback(new MethodInterceptor() {
			public Object intercept(Object o, Method method, Object[] obj, MethodProxy methodProxy) throws Throwable{
				advice.before();
				Object invoke = method.invoke(target, obj);
				advice.after();
				System.out.println();
				return invoke;
			}
		});
		
		//创建代理对象
		Target proxy = (Target)enhancer.create();
		
		//测试代理方法
		proxy.save();
		proxy.print("基于cglib实现动态规划");
		
	}

}

bash复制代码proxy_ip="127.0.0.1"
proxy_port="7890"
proxy_addr="$proxy_ip:$proxy_port"
http_proxy="http://$proxy_addr"
socks5_proxy="socks5://$proxy_addr"
alias proxy='export https_proxy=$http_proxy \
http_proxy=$http_proxy \
ftp_proxy=$http_proxy \
rsync_proxy=$http_proxy \
all_proxy=$socks5_proxy \
no_proxy="127.0.0.1,localhost"'
alias unproxy='unset https_proxy http_proxy ftp_proxy rsync_proxy all_proxy no_proxy'

bash复制代码source ~/.bash_profile

bash复制代码sudo yum update && sudo yum -y install zsh

bash复制代码sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

bash复制代码export ZSH="/home/k8scat/.oh-my-zsh"
ZSH_THEME="robbyrussell"

plugins_folder="${ZSH_CUSTOM:-$HOME/.oh-my-zsh/custom}/plugins"
syntax_highlight_plugin="${plugins_folder}/zsh-syntax-highlighting"
[[ ! -d "$syntax_highlight_plugin" ]] && git clone https://github.com/zsh-users/zsh-syntax-highlighting.git $syntax_highlight_plugin
autosuggestions_plugin="${plugins_folder}/zsh-autosuggestions"
[[ ! -d "$autosuggestions_plugin" ]] && git clone https://github.com/zsh-users/zsh-autosuggestions $autosuggestions_plugin
[[ -z $(pip list | grep -E "^wakatime ") ]] && pip install --user wakatime
wakatime_plugin="${plugins_folder}/wakatime"
[[ ! -d "$wakatime_plugin" ]] && git clone https://github.com/sobolevn/wakatime-zsh-plugin.git $wakatime_plugin
[[ ! -s "$HOME/.wakatime.cfg" ]] && cat > $HOME/.wakatime.cfg <<EOF
[settings]
api_key = xxx
EOF
plugins=(git zsh-syntax-highlighting zsh-autosuggestions wakatime docker docker-compose)

source $ZSH/oh-my-zsh.sh

export GOPRIVATE="github.com/private"
export GO111MODULE="auto"
export GOPROXY="https://goproxy.io,direct"
export GOROOT="/usr/local/go"
export GOPATH="$HOME/go"
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

proxy_ip="127.0.0.1"
proxy_port="7890"
proxy_addr="$proxy_ip:$proxy_port"
http_proxy="http://$proxy_addr"
socks5_proxy="socks5://$proxy_addr"
alias proxy='export https_proxy=$http_proxy \
http_proxy=$http_proxy \
ftp_proxy=$http_proxy \
rsync_proxy=$http_proxy \
all_proxy=$socks5_proxy \
no_proxy="127.0.0.1,localhost,192.168.8.152,192.168.8.154,192.168.8.155"'
alias unproxy='unset https_proxy http_proxy ftp_proxy rsync_proxy all_proxy no_proxy'
proxy

export PATH=$PATH:$HOME/.local/bin

bash复制代码curl -LO https://golang.org/dl/go1.16.5.linux-amd64.tar.gz
tar -C /usr/local -xzf go1.16.5.linux-amd64.tar.gz

bash复制代码export GOPRIVATE="github.com/private"
export GO111MODULE="auto"
export GOPROXY="https://goproxy.io,direct"
export GOROOT="/usr/local/go"
export GOPATH="$HOME/go"
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

bash复制代码docker run -d -p 3306:3306 mysql:8

bash复制代码sudo yum install -y yum-utils
sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install docker-ce docker-ce-cli containerd.io

# 让 Docker 服务开机自启动
sudo systemctl enable docker
# 启动 Docker
sudo systemctl start docker

# 验证
sudo docker run hello-world

bash复制代码sudo yum install -y git

bash复制代码# 安装依赖
sudo yum install -y gcc openssl-devel expat-devel curl-devel

# 下载源码
curl -LO https://github.com/git/git/archive/v2.29.2.tar.gz
tar zxf v2.29.2.tar.gz
cd git-2.29.2
make prefix=/usr
sudo make prefix=/usr install

config复制代码Host dev-server
    HostName 40.18.95.22
    User k8scat
    Port 9232
    IdentityFile ~/.ssh/id_rsa

xml复制代码<dependency>
    <groupId>com.google.code.kaptcha</groupId>
    <artifactId>kaptcha</artifactId>
    <version>2.3</version>
</dependency>

arduino复制代码@GetMapping("getCaptchaCode")
public void getCaptchaCode(HttpServletResponse response, HttpServletRequest request) throws ServletException, IOException {
	response.setHeader("Cache-Control", "no-store, no-cache");
	response.setContentType("image/jpeg");

	// 生成文字验证码
	String text = producer.createText();
	// 生成图片验证码
	BufferedImage image = producer.createImage(text);
	// 保存到验证码到 session
	request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY,     text);//Constants.KAPTCHA_SESSION_KEY为自己定义的存储常量

	ServletOutputStream out = response.getOutputStream();
	ImageIO.write(image, "jpg", out);
	IOUtils.closeQuietly(out);
}

scss复制代码// 从session中获取之前保存的验证码跟前台传来的验证码进行匹配
Object kaptcha = request.getSession().getAttribute(Constants.KAPTCHA_SESSION_KEY);
if(kaptcha == null){
return HttpResult.error(“验证码已失效”);
}
if(!captcha.equals(kaptcha)){
return HttpResult.error(“验证码不正确”);
}

typescript复制代码public static void closeQuietly(Closeable closeable) {
    try {
        if(closeable != null) {
            closeable.close();
        }
    } catch (IOException var2) {
        ;
    }
}

go复制代码type hchan struct {
	qcount   uint           // total data in the queue
	dataqsiz uint           // size of the circular queue
	buf      unsafe.Pointer // points to an array of dataqsiz elements
	elemsize uint16
	closed   uint32
	elemtype *_type // element type
	sendx    uint   // send index
	recvx    uint   // receive index
	recvq    waitq  // list of recv waiters
	sendq    waitq  // list of send waiters

	// lock protects all fields in hchan, as well as several
	// fields in sudogs blocked on this channel.
	//
	// Do not change another G's status while holding this lock
	// (in particular, do not ready a G), as this can deadlock
	// with stack shrinking.
	lock mutex
}

go复制代码package main

import (
	"fmt"
	"testing"
	"time"
)


func OnlyRead(testCh <-chan string) {
	result, ok := <-testCh
	fmt.Println(result, ok) // 这里会输出：msg1 true
}

func TestChannel(t *testing.T) {

	testCh := make(chan string, 5)
	testCh <- "msg1"
	close(testCh)
	go OnlyRead(testCh)
	time.Sleep(time.Second)

}

go复制代码package main

import (
	"fmt"
	"testing"
	"time"
)

func OnlyWrite(testCh chan<- string) {

	testCh <- "msg2"
}

func OnlyRead(testCh <-chan string) {
	for result := range testCh {
		fmt.Println(result, "====")
	}
}

func TestChannel(t *testing.T) {

	testCh := make(chan string, 2)
	testCh <- "msg1"
	go OnlyRead(testCh)
	go OnlyWrite(testCh)
	time.Sleep(time.Second * 1)
	close(testCh)

}

sql复制代码[函数名] OVER ([分组 PARTITION BY] 
              [排列顺序 ORDER BY] 
              [窗口框架])

sql复制代码SELECT product_id, product_name, product_type, sale_price,
    	SUM(sale_price) OVER (PARTITION BY product_type
                            	ORDER BY product_id DESC
                            	ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) sum
FROM Product;

sql复制代码RANGE|ROWS BETWEEN 上限 AND 下限

sql复制代码[CURRENT ROW] | [<num>|UNBOUNDED PRECEDING|FOLLOWING]

sql复制代码SELECT s_id, s_score,
		SUM(s_score) OVER (ORDER BY s_score 
                                   ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) row_,
		SUM(s_score) OVER (ORDER BY s_score 
                                   RANGE BETWEEN 9 PRECEDING AND CURRENT ROW) range_9,    
		SUM(s_score) OVER (ORDER BY s_score 
                                   RANGE BETWEEN 10 PRECEDING AND CURRENT ROW) range_10
FROM Student;

sql复制代码SELECT s_id, s_score,
       RANK() OVER (ORDER BY s_score) rank_ ,
       DENSE_RANK() OVER (ORDER BY s_score) dense_rank_  ,
       ROW_NUMBER() OVER (ORDER BY s_score) row_num_
FROM Student;

diff复制代码单Go程的情形：
-- w0 ---- r1 -- w1 ---- w2 ----  r2 ---- r3 ------>

这里不仅是个偏序关系，还是一个良序关系：所有 r/w 的先后顺序都是可比较的。

双Go程的情形：
-- w0 -- r1 -- r2 ---- w3 ----  w4 ---- r5 -------->
-- w1 ----- w2 -- r3 ----  r4 ---- w5 -------->

单Go程上的事件都有先后顺序；而对于两条Go程，情况又有所不同。即便在时间上 r1 先于 w2 发生，
但由于每条Go程的执行时长都像皮筋一样伸缩不定，因此二者在逻辑上并无先后次序。换言之，即二者并发。
对于并发的 r/w，r3 读取的结果可能是前面的 w2，也可能是上面的 w3，甚至 w4 的值；
而 r5 读取的结果，可能是 w4 的值，也能是 w1、w2、w5 的值，但不可能是 w3 的值。


双Go程交叉同步的情形：
-- r0 -- r1 ---|------ r2 ------------|-- w5 ------>
-- w1 --- w2 --|-- r3 ---- r4 -- w4 --|------->

现在上面添加了两个同步点，即 | 处。这样的话，r3 就是后于 r1 ，先于 w5 发生的。
r2 之前的写入为 w2，但与其并发的有 w4，因此 r2 的值是不确定的：可以是 w2，也可以是 w4。
而 r4 之前的写入的是 w2，与它并发的并没有写入，因此 r4 读取的值为 w2。

go复制代码var a string

func hello() {
	go func() { a = "hello" }()
	print(a)
}

go复制代码var c = make(chan int, 10)
var a string

func f() {
	a = "hello, world"
	c <- 0
}

func main() {
	go f()
	<-c
	print(a)
}

go复制代码var c = make(chan int)
var a string

func f() {
	a = "hello, world"
	<-c
}
func main() {
	go f()
	c <- 0
	print(a)
}

go复制代码var limit = make(chan int, 3)

func main() {
	for _, w := range work {
		go func(w func()) {
			limit <- 1
			w()
			<-limit
		}(w)
	}
	select{}
}

csharp复制代码var l sync.Mutex
var a string

func f() {
	a = "hello, world"
	l.Unlock()
}

func main() {
	l.Lock()
	go f()
	l.Lock()
	print(a)
}

go复制代码var a string
var once sync.Once

func setup() {
	a = "hello, world"
}

func doprint() {
	once.Do(setup)
	print(a)
}

func twoprint() {
	go doprint()
	go doprint()
}
调用 twoprint 会打印两次 "hello, world" 。 第一次对 twoprint 的调用会运行一次 setup。

bash复制代码127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> set name dingyongjun  #添加数据
QUEUED
127.0.0.1:6379> set age 26  #添加数据
QUEUED
127.0.0.1:6379> set high 172  #添加数据
QUEUED
127.0.0.1:6379> exec  执行事务
1) OK
2) OK
3) OK
127.0.0.1:6379> get name  #获取数据成功，证明事务执行成功
"dingyongjun"
127.0.0.1:6379> get age
"26"

bash复制代码127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> set name dingyongjun  #添加数据
QUEUED
127.0.0.1:6379> set age 26  #添加数据
QUEUED
127.0.0.1:6379> discard  #放弃事务
OK
127.0.0.1:6379> get name  #不会执行事务里面的添加操作
(nil)

bash复制代码127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> set name dingyongjun  #添加数据
QUEUED
127.0.0.1:6379> set age 23  #添加数据
QUEUED
127.0.0.1:6379> getset name  #输入一个错误的命令，这时候已经报错了，但是这个还是进入了事务的队列当中
(error) ERR wrong number of arguments for 'getset' command
127.0.0.1:6379> set high 173  #添加数据
QUEUED
127.0.0.1:6379> exec  #执行事务，报错，并且所有的命令都不会执行
(error) EXECABORT Transaction discarded because of previous errors.
127.0.0.1:6379> get name  #获取数据为空，证明没有执行
(nil)

bash复制代码127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> set name dingyongjun  #添加字符串数据
QUEUED
127.0.0.1:6379> incr name  #对字符串数据进行自增操作
QUEUED
127.0.0.1:6379> set age 23  #添加数据
QUEUED
127.0.0.1:6379> get age  #获取数据
QUEUED 
127.0.0.1:6379> exec  #执行事务。虽然对字符串数据进行自增操作报错了，但是其他的命令还是可以正常执行的
1) OK
2) (error) ERR value is not an integer or out of range
3) OK
4) "23"
127.0.0.1:6379> get age  #获取数据成功
"23"

bash复制代码127.0.0.1:6379> set money 100  #添加金钱100
OK
127.0.0.1:6379> set cost 0  #添加花费0
OK
127.0.0.1:6379> watch money  #监控金钱
OK
127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> DECRBY money 30  #金钱-30
QUEUED
127.0.0.1:6379> incrby cost 30  #花费+30
QUEUED
127.0.0.1:6379> exec  #执行事务，成功！这时候数据没有发生变动才可以成功
1) (integer) 70
2) (integer) 30

bash复制代码#线程1
127.0.0.1:6379> set money 100  #添加金钱100
OK
127.0.0.1:6379> set cost 0  #添加花费0
OK
127.0.0.1:6379> watch money  #开启监视（乐观锁）
OK 
127.0.0.1:6379> multi  #开启事务
OK
127.0.0.1:6379> DECRBY money 20  #金钱-20
QUEUED
127.0.0.1:6379> INCRBY cost 20   #花费+20
QUEUED
#这里先不要执行，先执行线程2来修改被监视的值
127.0.0.1:6379> exec  #执行报错，因为我们监视了money这个值，如果事务要对这个值进行操作前
#监视器会判断这个值是否正常，如果发生改变，事务执行失败！
(nil)

bash复制代码#线程2，这个在事务执行前操作执行
127.0.0.1:6379> INCRBY money 20  #金钱+20
(integer) 120

java复制代码@XStreamAlias("CloudComputer")
public class CloudComputer extends AbstractPersistable implements Labeled {

    private int cpuPower; // in gigahertz
    private int memory; // in gigabyte RAM
    private int networkBandwidth; // in gigabyte per hour
    private int cost; // in euro per month

    public CloudComputer() {
    }

    public CloudComputer(long id, int cpuPower, int memory, int networkBandwidth, int cost) {
        super(id);
        this.cpuPower = cpuPower;
        this.memory = memory;
        this.networkBandwidth = networkBandwidth;
        this.cost = cost;
    }

    public int getCpuPower() {
        return cpuPower;
    }

    public void setCpuPower(int cpuPower) {
        this.cpuPower = cpuPower;
    }

    public int getMemory() {
        return memory;
    }

    public void setMemory(int memory) {
        this.memory = memory;
    }

    public int getNetworkBandwidth() {
        return networkBandwidth;
    }

    public void setNetworkBandwidth(int networkBandwidth) {
        this.networkBandwidth = networkBandwidth;
    }

    public int getCost() {
        return cost;
    }

    public void setCost(int cost) {
        this.cost = cost;
    }

    // ************************************************************************
    // Complex methods
    // ************************************************************************

    public int getMultiplicand() {
        return cpuPower * memory * networkBandwidth;
    }

    @Override
    public String getLabel() {
        return "Computer " + id;
    }

}

java复制代码public class Course {

    private String code;

    private Teacher teacher; // Other problem fact
    private int lectureSize;
    private int minWorkingDaySize;

    private List<Curriculum> curriculumList; // Other problem facts
    private int studentSize;

    // ... getters
}

java复制代码@PlanningEntity(difficultyComparatorClass = CloudProcessDifficultyComparator.class)
@XStreamAlias("CloudProcess")
public class CloudProcess extends AbstractPersistable {

    private int requiredCpuPower; // in gigahertz
    private int requiredMemory; // in gigabyte RAM
    private int requiredNetworkBandwidth; // in gigabyte per hour

    // Planning variables: 规划变量：规划期间的变化，分数计算之间的变化。
    private CloudComputer computer;
    ......
}

java复制代码@PlanningEntity
public class Lesson {

    private Long id;

    private String subject;
    private String teacher;
    private String studentGroup;

    @PlanningVariable(valueRangeProviderRefs = "timeslotRange")
    private Timeslot timeslot;

    @PlanningVariable(valueRangeProviderRefs = "roomRange")
    private Room room;
    ....
}

xml复制代码<solver xmlns="https://www.optaplanner.org/xsd/solver" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://www.optaplanner.org/xsd/solver https://www.optaplanner.org/xsd/solver/solver.xsd">
  ...
  <entityClass>org.optaplanner.examples.cloudbalancing.domain.CloudProcess</entityClass>
  ...
</solver>

java复制代码@PlanningEntity(difficultyComparatorClass = CloudProcessDifficultyComparator.class)
public class CloudProcess {
    // ...
}

java复制代码public class CloudProcessDifficultyComparator implements Comparator<CloudProcess> {

    public int compare(CloudProcess a, CloudProcess b) {
        return new CompareToBuilder()
                .append(a.getRequiredMultiplicand(), b.getRequiredMultiplicand())
                .append(a.getId(), b.getId())
                .toComparison();
    }

}

java复制代码@PlanningEntity(difficultyComparatorClass = CloudProcessDifficultyComparator.class)
@XStreamAlias("CloudProcess")
public class CloudProcess extends AbstractPersistable {

    private int requiredCpuPower; // in gigahertz
    private int requiredMemory; // in gigabyte RAM
    private int requiredNetworkBandwidth; // in gigabyte per hour

    // Planning variables: changes during planning, between score calculations.
    private CloudComputer computer;

    ......

    @PlanningVariable(valueRangeProviderRefs = {
            "computerRange" }, strengthComparatorClass = CloudComputerStrengthComparator.class)
    public CloudComputer getComputer() {
        return computer;
    }

    public void setComputer(CloudComputer computer) {
        this.computer = computer;
    }
    ......

}

java复制代码@PlanningEntity
public class Queen {
    ...

    @PlanningVariable(valueRangeProviderRefs = {"rowRange"})
    private Row row;

}

java复制代码@PlanningVariable(..., nullable = true)
    public Worker getWorker() {
        return worker;
    }

java复制代码private UniConstraintStream<RockShow> getShowWithoutDate(ConstraintFactory constraintFactory) {
    return constraintFactory.fromUnfiltered(RockShow.class)
            .filter(rockShow -> rockShow.getDate() == null);
}