/**

* @ClassName: HystrixCommandSemaphoreController

* @Desc: 信号量隔离, 支持 多个service 共用同一个 信号配置

* @author: lance.lan

* @date: 2020年11月15日 下午10:07:15

*

*/

@RestController

@RequestMapping(value = "/hystrix/semaphore")

public class HystrixCommandSemaphoreController {

    @Autowired

    private UserService userService;

    /**

    * @Title: getUser

    * @author: lance.lan

    * @Description:无参

    * @param httpServletResponse

    * @throws InterruptedException

    * @return Object

    */

    @RequestMapping(value = "/getUser", method = RequestMethod.GET)

    public Object getUser(HttpServletResponse httpServletResponse) throws InterruptedException {

       Thread.sleep(1000L);

       return new HystrixSemaphoreCommand(userService,"getUserName", null, null).execute();

    }

    /**

    * @Title: getUser2

    * @author: lance.lan

    * @Description: 有参数

    * @param httpServletResponse

    * @throws InterruptedException

    * @return Object

    */

    @RequestMapping(value = "/getUser2", method = RequestMethod.GET)

    public Object getUser2(HttpServletResponse httpServletResponse) throws InterruptedException {

       Thread.sleep(1000L);

       Class<?>[] paramVarArgs = {String.class};

       String[] paramValues = {"lance"};

       return new HystrixSemaphoreCommand(userService,"getUserName", paramVarArgs, paramValues).execute();

    }

}

public class HystrixSemaphoreCommand extends HystrixCommand<Object> {

    private UserService userService;

    private String methodName;

    private Class<?>[] paramVarArgs;

    private Object[] paramValue;

    /**

     * @param userService

     * @param methodName:要调用的方法名称

     * @param paramVarArgs:方法参数类型

     * @param paramValue:参数值

     */

    public HystrixSemaphoreCommand(UserService userService, String methodName, Class<?>[] paramVarArgs, Object[] paramValue) {

       super(setter());

       this.userService = userService;

       this.methodName = methodName;

       this.paramVarArgs = paramVarArgs;

       this.paramValue = paramValue;

    }

    private static Setter setter() {

       // 服务分组

       HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey("user");

       // 命令属性配置 采用信号量模式

       HystrixCommandProperties.Setter commandProperties = HystrixCommandProperties.Setter().withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE)

              // 使用一个原子计数器（或信号量）来记录当前有多少个线程在运行，当请求进来时先判断计数

              // 器的数值，若超过设置的最大线程个数则拒绝该请求，若不超过则通行，这时候计数器+1，请求返 回成功后计数器-1。

              .withExecutionIsolationSemaphoreMaxConcurrentRequests(2);

       return HystrixCommand.Setter.withGroupKey(groupKey).andCommandPropertiesDefaults(commandProperties);

    }

    @Override

    protected Object run() throws Exception {

       Thread.sleep(1000);

       //反射

       Object obj = UserService.class.getMethod(methodName, paramVarArgs).invoke(userService, paramValue);

       //String name = userService.getUserName();

       System.out.println("当前线程名称:" + Thread.currentThread().getName());

       return obj;

    }

    @Override

    protected String getFallback() {

       // 如果Hystrix发生熔断，当前服务不可用,直接执行Fallback方法

       System.out.println("系统错误！");

       return "系统错误！";

    }

}

@Service

public class UserService {

    public String getUserName() {

       return "lance.lan";

    }

    public String getUserName(String name) {

       return "return:" + name;

    }

}