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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);        }    }}
     
    

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();        }    }}
     

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);    }}

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);    }}
      
     
    

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;    }}
      
     
    

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)。

doc