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本文主要研究一下spring cloud的HystrixAutoConfiguration

HystrixAutoConfiguration

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixAutoConfiguration.java

/** * Auto configuration for Hystrix. * * @author Christian Dupuis * @author Dave Syer */@Configuration@ConditionalOnClass({ Hystrix.class, HealthIndicator.class })@AutoConfigureAfter({ HealthIndicatorAutoConfiguration.class })public class HystrixAutoConfiguration {	@Bean	@ConditionalOnEnabledHealthIndicator("hystrix")	public HystrixHealthIndicator hystrixHealthIndicator() {		return new HystrixHealthIndicator();	}	@Bean	@ConditionalOnProperty(value = "management.metrics.hystrix.enabled", matchIfMissing = true)	public HystrixMetricsBinder hystrixMetricsBinder() {		return new HystrixMetricsBinder();	}	/**	 * See original {@link org.springframework.boot.actuate.autoconfigure.jolokia.JolokiaEndpointAutoConfiguration}	 */	@Configuration	@ConditionalOnWebApplication(type = SERVLET)	@ConditionalOnBean(HystrixCommandAspect.class) // only install the stream if enabled	@ConditionalOnClass({ HystrixMetricsStreamServlet.class })	@EnableConfigurationProperties(HystrixProperties.class)	protected static class HystrixServletAutoConfiguration {		@Bean		@ConditionalOnEnabledEndpoint		public HystrixStreamEndpoint hystrixStreamEndpoint(HystrixProperties properties) {			return new HystrixStreamEndpoint(properties.getConfig());		}		@Bean		public HasFeatures hystrixStreamFeature() {			return HasFeatures.namedFeature("Hystrix Stream Servlet", HystrixMetricsStreamServlet.class);		}	}	@Configuration	@ConditionalOnWebApplication(type = REACTIVE)	@ConditionalOnBean(HystrixCommandAspect.class) // only install the stream if enabled	@ConditionalOnClass({ DispatcherHandler.class })	@EnableConfigurationProperties(HystrixProperties.class)	protected static class HystrixWebfluxManagementContextConfiguration {		@Bean		@ConditionalOnEnabledEndpoint		public HystrixWebfluxEndpoint hystrixWebfluxController() {			Observable
    
      serializedDashboardData = HystrixDashboardStream.getInstance().observe()					.concatMap(dashboardData -> Observable.from(SerialHystrixDashboardData.toMultipleJsonStrings(dashboardData)));			Publisher
     
       publisher = RxReactiveStreams.toPublisher(serializedDashboardData);			return new HystrixWebfluxEndpoint(publisher);		}		@Bean		public HasFeatures hystrixStreamFeature() {			return HasFeatures.namedFeature("Hystrix Stream Webflux", HystrixWebfluxEndpoint.class);		}	}}复制代码
     
    

这里有几个bean，一个是HystrixHealthIndicator，还有HystrixMetricsBinder。另外关于endpoint，区分了servlet及webflux版本。

HystrixHealthIndicator

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixHealthIndicator.java

/** * A {@link HealthIndicator} implementation for Hystrix circuit breakers. * 
 * This default implementation will not change the system state (e.g.  OK) but * includes all open circuits by name. * * @author Christian Dupuis */public class HystrixHealthIndicator extends AbstractHealthIndicator {	private static final Status CIRCUIT_OPEN = new Status("CIRCUIT_OPEN");	@Override	protected void doHealthCheck(Builder builder) throws Exception {		List
     
       openCircuitBreakers = new ArrayList<>();		// Collect all open circuit breakers from Hystrix		for (HystrixCommandMetrics metrics : HystrixCommandMetrics.getInstances()) {			HystrixCircuitBreaker circuitBreaker = HystrixCircuitBreaker.Factory					.getInstance(metrics.getCommandKey());			if (circuitBreaker != null && circuitBreaker.isOpen()) {				openCircuitBreakers.add(metrics.getCommandGroup().name() + "::"						+ metrics.getCommandKey().name());			}		}		// If there is at least one open circuit report OUT_OF_SERVICE adding the command		// group		// and key name		if (!openCircuitBreakers.isEmpty()) {			builder.status(CIRCUIT_OPEN).withDetail("openCircuitBreakers",					openCircuitBreakers);		}		else {			builder.up();		}	}}复制代码
     

检查断路器的状态

HystrixMetricsBinder

micrometer-core-1.0.5-sources.jar!/io/micrometer/core/instrument/binder/hystrix/HystrixMetricsBinder.java

@NonNullApi@NonNullFieldspublic class HystrixMetricsBinder implements MeterBinder {    @Override    public void bindTo(MeterRegistry registry) {        // Keeps references of existing Hystrix plugins.        HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();        HystrixPropertiesStrategy propertiesStrategy = HystrixPlugins.getInstance().getPropertiesStrategy();        HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance().getCommandExecutionHook();        HystrixConcurrencyStrategy concurrencyStrategy = HystrixPlugins.getInstance().getConcurrencyStrategy();        HystrixPlugins.reset();        // Registers existing plugins except the new MicroMeter Strategy plugin.        HystrixPlugins.getInstance().registerMetricsPublisher(new MicrometerMetricsPublisher(registry));        HystrixPlugins.getInstance().registerConcurrencyStrategy(concurrencyStrategy);        HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);        HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);        HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);    }}复制代码

这里导出metrics到micrometer

HystrixStreamEndpoint

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixStreamEndpoint.java

/** * {@link org.springframework.boot.actuate.endpoint.annotation.Endpoint} to expose a Jolokia {@link HystrixMetricsStreamServlet}. * * @author Phillip Webb * @since 2.0.0 */@ServletEndpoint(id = "hystrix.stream")public class HystrixStreamEndpoint implements Supplier
    
      {    private final Map
     
       initParameters;    public HystrixStreamEndpoint(Map
      
        initParameters) {        this.initParameters = initParameters;    }    @Override    public EndpointServlet get() {        return new EndpointServlet(HystrixMetricsStreamServlet.class)                .withInitParameters(this.initParameters);    }}复制代码
      
     
    

这个是基于servlet的

HystrixWebfluxEndpoint

spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixWebfluxEndpoint.java

@RestControllerEndpoint(id = "hystrix.stream")public class HystrixWebfluxEndpoint {    private final Flux
    
      stream;    public HystrixWebfluxEndpoint(Publisher
     
       dashboardData) {        stream = Flux.interval(Duration.ofMillis(500)).map(aLong -> "{\"type\":\"ping\"}")                .mergeWith(dashboardData).share();    }    // path needs to be empty, so it registers correct as /actuator/hystrix.stream    @GetMapping(path = "", produces = MediaType.TEXT_EVENT_STREAM_VALUE)    public Flux
      
        hystrixStream() {        return stream;    }}复制代码
      
     
    

这个是基于webflux的

小结

HystrixAutoConfiguration主要是配置了HystrixHealthIndicator、HystrixMetricsBinder以及HystrixEndpoint(分servlet与webflux版本)。

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