SpringCloud：服务保护——通过Future机制自定义服务保护

一，上一篇通过Hystrix对服务保护进行了分析；这一篇基于Future，分版本由浅入深对服务降级和服务隔离机制进行说明

二，服务端代码，线程随机沉睡200MS以内，客户端调用100MS超时，制造可能超时场景

package com.gupao.member.service.impl;

import com.gupao.api.service.IMemberServier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author pj_zhang
 * @create 2019-01-09 23:48
 **/
@RestController
public class MemberService implements IMemberServier {

    @Value("${server.port}")
    private Integer serverPort;

   @Override
    @RequestMapping("/getMember_1")
    public String getMember_1() throws InterruptedException {
        int sleepTime = new Random().nextInt(200);
        System.out.println("getMember_1, thread sleep : " + sleepTime);
        Thread.sleep(sleepTime);
        System.out.println("getMember_1 Thread Name : " + Thread.currentThread().getName());
        return "MemberService.getMember_1, serverPort : " + serverPort;
    }
}

三，客户端自定义接口处理

1，初级版本——容错实现

    * 代码实现

package com.gupao.order.self;

import com.gupao.order.feign.IMemberServiceFeign;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.*;

/**
 * @author pj_zhang
 * @create 2019-01-22 22:55
 **/
@RestController
public class SelfCircuitBreaker {

    // 创建一个线程池
    private final ExecutorService executorService = Executors.newSingleThreadExecutor();

    @Autowired
    private IMemberServiceFeign memberServiceFeign;

    @RequestMapping("/low")
    public String getMember() {
        // 通过Callable发起异步线程, 获取回调结果
        long startTime = System.currentTimeMillis();
        Future<String> future = executorService.submit(new Callable<String>() {
            @Override
            public String call() throws Exception {
                return memberServiceFeign.getMember_1();
            }
        });

        // future阻塞获取回调结果
        String returnValue = null;
        long endTime = 0L;
        try {
            returnValue = future.get(100, TimeUnit.MILLISECONDS);
        } catch (Exception e) {
            // 报错后取消执行服务
            future.cancel(true);
            returnValue = "服务调用超时...";
        }
        System.out.println("returnValue : " + returnValue + ", costTime : " + (System.currentTimeMillis() - startTime));
        return returnValue;
    }

}

    * 服务端控制台输出

    * 客户端控制台输出

2，中级版本——拦截器实现

    * Rest接口

    @RequestMapping("/middle")
    public String middle() throws InterruptedException {
        return memberServiceFeign.getMember_1();
    }

    * 拦截器实现

package com.gupao.order.interceptor;

import com.alibaba.fastjson.JSONObject;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

import javax.annotation.PreDestroy;
import java.util.concurrent.*;

/**
 * @author pj_zhang
 * @create 2019-01-22 23:11
 **/
@Aspect
@Component
public class SelfServerInterceptor {

    private ExecutorService executorService = Executors.newSingleThreadExecutor();

    @Around("execution(public * com.gupao.order.self.SelfCircuitBreaker.middle(..))")
    public String getMember(final ProceedingJoinPoint proceedingJoinPoint) {
        return doServer(proceedingJoinPoint, 100L);
    }

    private String doServer(final ProceedingJoinPoint proceedingJoinPoint, Long timeOut) {
        long startTime = System.currentTimeMillis();
        // 通过Callable发起异步线程, 获取回调结果
        Future<String> future = executorService.submit(new Callable<String>() {
            @Override
            public String call() throws Exception {
                try {
                    // 执行目标方法
                    return JSONObject.toJSONString(proceedingJoinPoint.proceed());
                } catch (Throwable throwable) {
                    return "服务调用失败";
                }
            }
        });

        // 阻塞等待方法执行完成
        String returnValue = null;
        try {
            returnValue = future.get(100, TimeUnit.MILLISECONDS);
        } catch (Exception e) {
            future.cancel(true);
            returnValue = "服务请求超时...";
        }

        System.out.println("returnValue : " + returnValue + ", costTime : " + (System.currentTimeMillis() - startTime));
        return returnValue;
    }


    @PreDestroy
    public void destory() {
        executorService.shutdown();
    }

}

    * 运行结果

3，高级版本——拦截器+注解实现

    * 添加注解

package com.gupao.order.annotation;

import java.lang.annotation.*;

/**
 * @author pj_zhang
 * @create 2019-01-22 23:24
 **/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CircuitBreakder {

    long outTime() default 100;
}

    * 服务调用接口

    @RequestMapping("/high")
    @CircuitBreakder(outTime = 100L)
    public String high() throws InterruptedException {
        return memberServiceFeign.getMember_1();
    }

    * 拦截器实现

    @Around("execution(public * com.gupao.order.self.SelfCircuitBreaker.high(..))")
    public String getMemberByHigh(final ProceedingJoinPoint proceedingJoinPoint) {
        // 通过注解获取超时时间
        long outTime = 100L;
        if (proceedingJoinPoint instanceof MethodInvocationProceedingJoinPoint) {
            MethodInvocationProceedingJoinPoint methodPoint = (MethodInvocationProceedingJoinPoint) proceedingJoinPoint;
            MethodSignature signature = (MethodSignature) methodPoint.getSignature();
            Method method = signature.getMethod();
            CircuitBreakder circuitBreaker = method.getAnnotation(CircuitBreakder.class);
            outTime = circuitBreaker.outTime();
        }
        return doServer(proceedingJoinPoint, outTime);
    }

    * 运行结果

4，通过信号灯实现单机版限流方案

    * 注意暂时去掉Feign客户端的Hystrix服务保护，此处在原项目上实现，受超时时间影响

@FeignClient(name = "app-itmayiedu-member")
public interface IMemberServiceFeign extends IMemberServier {
}

    * Hystrix超时时间默认1S，进行修改

###服务启动端口号
server:
  port: 8100
###服务名称(服务注册到eureka名称)
spring:
    application:
        name: app-itmayiedu-order
###服务注册到eureka地址
eureka:
  client:
    service-url:
           defaultZone: http://localhost:8000/eureka

    ###因为该应用为注册中心，不会注册自己
    register-with-eureka: true
    ###是否需要从eureka上获取注册信息
    fetch-registry: true
###设置feign客户端超时时间
ribbon:
###指的是建立连接所用的时间，适用于网络状况正常的情况下，两端连接所用的时间。
  ReadTimeout: 50000
###指的是建立连接后从服务器读取到可用资源所用的时间。
  ConnectTimeout: 50000

### 开启hystrix断路器
feign:
  hystrix:
    enabled: true

### hystrix超时时间
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds : 100000

    * 修改服务端睡眠时间，睡眠5S

@Override
    @RequestMapping("/getMember_1")
    public String getMember_1() throws InterruptedException {
        Thread.sleep(5000);
        System.out.println("getMember_1 Thread Name : " + Thread.currentThread().getName());
        return "MemberService.getMember_1, serverPort : " + serverPort;
    }

    * 自定义注解添加限流属性

package com.gupao.order.annotation;

        import java.lang.annotation.*;

/**
 * @author pj_zhang
 * @create 2019-01-22 23:24
 **/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CircuitBreakder {

    long outTime() default 100;

    int value() default 5;
}

    * 定义REST接口

    @RequestMapping("/limit")
    public String limit() throws InterruptedException {
        return memberServiceFeign.getMember_1();
    }

    * 拦截器实现

 @Around("execution(public * com.gupao.order.self.SelfCircuitBreaker.limit(..))")
    public String limit(final ProceedingJoinPoint proceedingJoinPoint) {
        // 通过注解获取超时时间
        Integer limitValue = 5;
        if (proceedingJoinPoint instanceof MethodInvocationProceedingJoinPoint) {
            MethodInvocationProceedingJoinPoint methodPoint = (MethodInvocationProceedingJoinPoint) proceedingJoinPoint;
            MethodSignature signature = (MethodSignature) methodPoint.getSignature();
            Method method = signature.getMethod();
            CircuitBreakder circuitBreaker = method.getAnnotation(CircuitBreakder.class);
            limitValue = circuitBreaker.value();
        }
        // 初始化信号量
        if (semaphore == null) {
            semaphore = new Semaphore(limitValue);
        }
        String returnValue = null;
        try {
            // 获取到可用信号, 执行方法
            if (semaphore.tryAcquire()) {
                returnValue = JSONObject.toJSONString(proceedingJoinPoint.proceed());
            // 未获取到可用信号, 返回错误提示
            } else {
                returnValue = "Semaphore 限流...";
            }
        } catch (Throwable throwable) {
            returnValue = "执行异常";
        } finally {
            semaphore.release();
        }
        System.out.println("returnValue : " + returnValue);
        return returnValue;
    }

    * 频繁刷新页面数次，直到刷新出预期结果