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本文主要研究一下spring cloud的HystrixCircuitBreakerConfiguration
HystrixCircuitBreakerConfiguration
spring-cloud-netflix-core-2.0.0.RELEASE-sources.jar!/org/springframework/cloud/netflix/hystrix/HystrixCircuitBreakerConfiguration.java
@Configuration
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));
}
//FIXME: 2.0.0
/*@Configuration
@ConditionalOnProperty(value = "hystrix.metrics.enabled", matchIfMissing = true)
@ConditionalOnClass({ HystrixMetricsPoller.class, GaugeService.class })
@EnableConfigurationProperties(HystrixMetricsProperties.class)
protected static class HystrixMetricsPollerConfiguration implements SmartLifecycle {
private static Log logger = LogFactory
.getLog(HystrixMetricsPollerConfiguration.class);
@Autowired(required = false)
private GaugeService gauges;
@Autowired
private HystrixMetricsProperties metricsProperties;
private ObjectMapper mapper = new ObjectMapper();
private HystrixMetricsPoller poller;
private Set<String> reserved = new HashSet<String>(Arrays.asList("group", "name",
"type", "currentTime"));
@Override
public void start() {
if (this.gauges == null) {
return;
}
MetricsAsJsonPollerListener listener = new MetricsAsJsonPollerListener() {
@Override
public void handleJsonMetric(String json) {
try {
@SuppressWarnings("unchecked")
Map<String, Object> map = HystrixMetricsPollerConfiguration.this.mapper
.readValue(json, Map.class);
if (map != null && map.containsKey("type")) {
addMetrics(map, "hystrix.");
}
}
catch (IOException ex) {
// ignore
}
}
};
this.poller = new HystrixMetricsPoller(listener,
metricsProperties.getPollingIntervalMs());
// start polling and it will write directly to the listener
this.poller.start();
logger.info("Starting poller");
}
private void addMetrics(Map<String, Object> map, String root) {
StringBuilder prefixBuilder = new StringBuilder(root);
if (map.containsKey("type")) {
prefixBuilder.append((String) map.get("type"));
if (map.containsKey("group")) {
prefixBuilder.append(".").append(map.get("group"));
}
prefixBuilder.append(".").append(map.get("name"));
}
String prefix = prefixBuilder.toString();
for (String key : map.keySet()) {
Object value = map.get(key);
if (!this.reserved.contains(key)) {
if (value instanceof Number) {
String name = prefix + "." + key;
this.gauges.submit(name, ((Number) value).doubleValue());
}
else if (value instanceof Map) {
@SuppressWarnings("unchecked")
Map<String, Object> sub = (Map<String, Object>) value;
addMetrics(sub, prefix);
}
}
}
}
@Override
public void stop() {
if (this.poller != null) {
this.poller.shutdown();
}
}
@Override
public boolean isRunning() {
return this.poller != null ? this.poller.isRunning() : false;
}
@Override
public int getPhase() {
return Ordered.LOWEST_PRECEDENCE;
}
@Override
public boolean isAutoStartup() {
return true;
}
@Override
public void stop(Runnable callback) {
if (this.poller != null) {
this.poller.shutdown();
}
callback.run();
}
}*/
/**
* {@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();
}
}
}
这里主要是创建了HystrixCommandAspect以及HystrixShutdownHook
HystrixCommandAspect
hystrix-javanica-1.5.12-sources.jar!/com/netflix/hystrix/contrib/javanica/aop/aspectj/HystrixCommandAspect.java
/**
* AspectJ aspect to process methods which annotated with {@link HystrixCommand} annotation.
*/
@Aspect
public class HystrixCommandAspect {
private static final Map<HystrixPointcutType, MetaHolderFactory> META_HOLDER_FACTORY_MAP;
static {
META_HOLDER_FACTORY_MAP = ImmutableMap.<HystrixPointcutType, MetaHolderFactory>builder()
.put(HystrixPointcutType.COMMAND, new CommandMetaHolderFactory())
.put(HystrixPointcutType.COLLAPSER, new CollapserMetaHolderFactory())
.build();
}
@Pointcut("@annotation(com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand)")
public void hystrixCommandAnnotationPointcut() {
}
@Pointcut("@annotation(com.netflix.hystrix.contrib.javanica.annotation.HystrixCollapser)")
public void hystrixCollapserAnnotationPointcut() {
}
@Around("hystrixCommandAnnotationPointcut() || hystrixCollapserAnnotationPointcut()")
public Object methodsAnnotatedWithHystrixCommand(final ProceedingJoinPoint joinPoint) throws Throwable {
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");
}
MetaHolderFactory metaHolderFactory = META_HOLDER_FACTORY_MAP.get(HystrixPointcutType.of(method));
MetaHolder metaHolder = metaHolderFactory.create(joinPoint);
HystrixInvokable invokable = HystrixCommandFactory.getInstance().create(metaHolder);
ExecutionType executionType = metaHolder.isCollapserAnnotationPresent() ?
metaHolder.getCollapserExecutionType() : metaHolder.getExecutionType();
Object result;
try {
if (!metaHolder.isObservable()) {
result = CommandExecutor.execute(invokable, executionType, metaHolder);
} else {
result = executeObservable(invokable, executionType, metaHolder);
}
} catch (HystrixBadRequestException e) {
throw e.getCause() != null ? e.getCause() : e;
} catch (HystrixRuntimeException e) {
throw hystrixRuntimeExceptionToThrowable(metaHolder, e);
}
return result;
}
//......
}
支持@HystrixCommand及@HystrixCollapser注解
HystrixShutdownHook
/**
* {@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();
}
}
主要是调用了reset方法
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/Hystrix.java
/**
* Reset state and release resources in use (such as thread-pools).
* <p>
* NOTE: This can result in race conditions if HystrixCommands are concurrently being executed.
* </p>
*/
public static void reset() {
// shutdown thread-pools
HystrixThreadPool.Factory.shutdown();
_reset();
}
/**
* Reset state and release resources in use (such as threadpools) and wait for completion.
* <p>
* NOTE: This can result in race conditions if HystrixCommands are concurrently being executed.
* </p>
*
* @param time
* time to wait for thread-pools to shutdown
* @param unit
* {@link TimeUnit} for <pre>time</pre> to wait for thread-pools to shutdown
*/
public static void reset(long time, TimeUnit unit) {
// shutdown thread-pools
HystrixThreadPool.Factory.shutdown(time, unit);
_reset();
}
/**
* Reset logic that doesn't have time/TimeUnit arguments.
*/
private static void _reset() {
// clear metrics
HystrixCommandMetrics.reset();
HystrixThreadPoolMetrics.reset();
HystrixCollapserMetrics.reset();
// clear collapsers
HystrixCollapser.reset();
// clear circuit breakers
HystrixCircuitBreaker.Factory.reset();
HystrixPlugins.reset();
HystrixPropertiesFactory.reset();
currentCommand.set(new ConcurrentStack<HystrixCommandKey>());
}
小结
HystrixCircuitBreakerConfiguration主要是注入了HystrixCommandAspect以及HystrixShutdownHook。前者用于支持支持@HystrixCommand及@HystrixCollapser注解，后者用于shudown的时候进行一些清理工作。
