framework/SpringCloud/Hystrix/SpringCloud的hystrix

2020-08-16

字数统计: 995字 | 阅读时长≈ 5分

hystrix集成到cloud

一个Observable一直包

Observable订阅是，把新进来的订阅者包成另一个订阅者床给父的Observable

然后最后的架构就是

Observable —>Observable1->…–>Observablen

Subscribern <— Subscribern-1 <– Subscriber1

最后调用 Observable n的OnSubscribe ( Subscriber1 ) ->Observable n-1的OnSubscribe ( Subscriber2 ) —>Observable 1的OnSubscribe ( Subscriber n )

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.hystrix.HystrixAutoConfiguration,\
org.springframework.cloud.netflix.hystrix.HystrixCircuitBreakerAutoConfiguration,\
org.springframework.cloud.netflix.hystrix.ReactiveHystrixCircuitBreakerAutoConfiguration,\
org.springframework.cloud.netflix.hystrix.security.HystrixSecurityAutoConfiguration

org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker=\
org.springframework.cloud.netflix.hystrix.HystrixCircuitBreakerConfiguration

HystrixAutoConfiguration

	@Bean
	@ConditionalOnEnabledHealthIndicator("hystrix")
	public HystrixHealthIndicator hystrixHealthIndicator() {
        //一个Hystrix健康指示器
		return new HystrixHealthIndicator();
	}

@Configuration(proxyBeanMethods = false)
	@ConditionalOnProperty(value = "management.metrics.binders.hystrix.enabled",
			matchIfMissing = true)
	@ConditionalOnClass({ HystrixMetricsBinder.class })
	protected static class HystrixMetricsConfiguration {

		@Bean
		public HystrixMetricsBinder hystrixMetricsBinder() {
            //指标绑定
			return new HystrixMetricsBinder();
		}

	}


@Configuration(proxyBeanMethods = false)
	@ConditionalOnWebApplication(type = SERVLET)
	@ConditionalOnBean(HystrixCommandAspect.class) // only install the stream if enabled
	@ConditionalOnClass({ HystrixMetricsStreamServlet.class })
	@EnableConfigurationProperties(HystrixProperties.class)
	protected static class HystrixServletAutoConfiguration {

        
        //提供一个servlet来供访问 服务的执行状态
		@Bean
		@ConditionalOnAvailableEndpoint
		public HystrixStreamEndpoint hystrixStreamEndpoint(HystrixProperties properties) {
			return new HystrixStreamEndpoint(properties.getConfig());
		}

		@Bean
		public HasFeatures hystrixStreamFeature() {
			return HasFeatures.namedFeature("Hystrix Stream Servlet",
					HystrixMetricsStreamServlet.class);
		}

	}

HystrixProperties

配置


@ConfigurationProperties(prefix = "management.endpoint.hystrix")
public class HystrixProperties {

	/**
	 * Hystrix settings. These are traditionally set using servlet parameters. Refer to
	 * the documentation of Hystrix for more details.
	 */
	private final Map<String, String> config = new HashMap<>();

	public Map<String, String> getConfig() {
		return this.config;
	}

}

HealthContributorAutoConfiguration


@Configuration(proxyBeanMethods = false)
public class HealthContributorAutoConfiguration {

	@Bean
	@ConditionalOnEnabledHealthIndicator("ping")
	public PingHealthIndicator pingHealthContributor() {
        
        //一个ping的健康指示器
        
		return new PingHealthIndicator();
	}

}

HystrixCircuitBreakerAutoConfiguration



@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Hystrix.class })
@ConditionalOnProperty(name = "spring.cloud.circuitbreaker.hystrix.enabled",
		matchIfMissing = true)
public class HystrixCircuitBreakerAutoConfiguration {

	@Autowired(required = false)
	private List<Customizer<HystrixCircuitBreakerFactory>> customizers = new ArrayList<>();

    
    
	@Bean
	@ConditionalOnMissingBean(CircuitBreakerFactory.class)
	public CircuitBreakerFactory hystrixCircuitBreakerFactory() {
        没有用到，不知道意义在哪
		HystrixCircuitBreakerFactory factory = new HystrixCircuitBreakerFactory();
		customizers.forEach(customizer -> customizer.customize(factory));
		return factory;
	}

}

HystrixCircuitBreaker

断路器

没有用到，不知道意义在哪

public class HystrixCircuitBreaker implements CircuitBreaker {

	private HystrixCommand.Setter setter;

	public HystrixCircuitBreaker(HystrixCommand.Setter setter) {
		this.setter = setter;
	}

	@Override
	public <T> T run(Supplier<T> toRun, Function<Throwable, T> fallback) {

        
       //注意这里好像没有什么断路功能，但是断路功能HystrixCommand包含了，只要执行就能默认有断路功能
        //而我们需要关注的是HystrixCommand.Setter，这里面有我们需要配置的东西
		HystrixCommand<T> command = new HystrixCommand<T>(setter) {
			@Override
			protected T run() throws Exception {
				return toRun.get();
			}

			@Override
			protected T getFallback() {
				return fallback.apply(getExecutionException());
			}
		};
		return command.execute();
	}

}

HystrixCircuitBreakerConfiguration


@Configuration(proxyBeanMethods = false)
public class HystrixCircuitBreakerConfiguration {

	@Bean
	public HystrixCommandAspect hystrixCommandAspect() {
		return new HystrixCommandAspect();
	}

	@Bean
	public HystrixShutdownHook hystrixShutdownHook() {
		return new HystrixShutdownHook();
	}

	@Bean
	public HasFeatures hystrixFeature() {
		return HasFeatures
				.namedFeatures(new NamedFeature("Hystrix", HystrixCommandAspect.class));
	}

	/**
	 * {@link DisposableBean} that makes sure that Hystrix internal state is cleared when
	 * {@link ApplicationContext} shuts down.
	 */
	private class HystrixShutdownHook implements DisposableBean {

		@Override
		public void destroy() throws Exception {
			// Just call Hystrix to reset thread pool etc.
			Hystrix.reset();
		}

	}

}

前面都是对其他框架的辅助，没卵用

重点执行

HystrixCommandAspect

切面


@RequestMapping(value = "/testHystrix")
@HystrixCommand(fallbackMethod = "helloFallback",commandKey = "queryAllKey")//熔断器指定操作的方法
public Object queryAll(){
    System.out.println("==========进入访问方法============");
    String url="aaa";
    List forObject = restTemplate.getForObject(url+"/queryAll", List.class);
    return forObject;
}

private Object helloFallback(){
    return null;
}


   ----切点 @Pointcut("@annotation(com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand)")

    public void hystrixCommandAnnotationPointcut() {
    }

    @Pointcut("@annotation(com.netflix.hystrix.contrib.javanica.annotation.HystrixCollapser)")
    public void hystrixCollapserAnnotationPointcut() {
    }


切点会找到queryAll方法
    所以
    
    
 @Around("hystrixCommandAnnotationPointcut() || hystrixCollapserAnnotationPointcut()")
    public Object methodsAnnotatedWithHystrixCommand(final ProceedingJoinPoint joinPoint) throws Throwable {
    
    //获取执行的方法
        Method method = getMethodFromTarget(joinPoint);
        Validate.notNull(method, "failed to get method from joinPoint: %s", joinPoint);
        if (method.isAnnotationPresent(HystrixCommand.class) && method.isAnnotationPresent(HystrixCollapser.class)) {
            throw new IllegalStateException("method cannot be annotated with HystrixCommand and HystrixCollapser " +
                    "annotations at the same time");
        }
    
    //获取元数据持有者的工厂
    //只有两种
        MetaHolderFactory metaHolderFactory = META_HOLDER_FACTORY_MAP.get(HystrixPointcutType.of(method));
    
    //通过joinPoint来创建元数据持有者
        MetaHolder metaHolder = metaHolderFactory.create(joinPoint);
    
    //然后获取 持有调用器的对象
        HystrixInvokable invokable = HystrixCommandFactory.getInstance().create(metaHolder);
    //获取执行的类型
    //一般是没有Observable
        ExecutionType executionType = metaHolder.isCollapserAnnotationPresent() ?
                metaHolder.getCollapserExecutionType() : metaHolder.getExecutionType();

        Object result;
        try {
            if (!metaHolder.isObservable()) {
                
                //最后执行
                result = CommandExecutor.execute(invokable, executionType, metaHolder);
            } else {
                result = executeObservable(invokable, executionType, metaHolder);
            }
        } catch (HystrixBadRequestException e) {
            throw e.getCause();
        } catch (HystrixRuntimeException e) {
            throw hystrixRuntimeExceptionToThrowable(metaHolder, e);
        }
        return result;
    }

配置


private GenericSetterBuilder createGenericSetterBuilder(MetaHolder metaHolder) {
    GenericSetterBuilder.Builder setterBuilder = GenericSetterBuilder.builder()
            .groupKey(metaHolder.getCommandGroupKey())
            .threadPoolKey(metaHolder.getThreadPoolKey())
            .commandKey(metaHolder.getCommandKey())
            .collapserKey(metaHolder.getCollapserKey())
            .commandProperties(metaHolder.getCommandProperties())
            .threadPoolProperties(metaHolder.getThreadPoolProperties())
            .collapserProperties(metaHolder.getCollapserProperties());
    if (metaHolder.isCollapserAnnotationPresent()) {
        setterBuilder.scope(metaHolder.getHystrixCollapser().scope());
    }
    return setterBuilder.build();
}

本文作者： 忘忧症
本文链接： https://NepenthesZGW.github.io/2020/08/16/framework/SpringCloud/Hystrix/SpringCloud的hystrix/
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