SpringCloud-Hystrix-配置讀取機制

基於註解

    @HystrixCommand(commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")
    })

    // com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect.CommandMetaHolderFactory
    private static class CommandMetaHolderFactory extends MetaHolderFactory {
        @Override
        public MetaHolder create(Object proxy, Method method, Object obj, Object[] args, final ProceedingJoinPoint joinPoint) {
            // 獲取註解
            HystrixCommand hystrixCommand = method.getAnnotation(HystrixCommand.class);
            ExecutionType executionType = ExecutionType.getExecutionType(method.getReturnType());
            /
            MetaHolder.Builder builder = metaHolderBuilder(proxy, method, obj, args, joinPoint);
            if (isCompileWeaving()) {
                builder.ajcMethod(getAjcMethodFromTarget(joinPoint));
            }
            return builder.defaultCommandKey(method.getName())
                            .hystrixCommand(hystrixCommand)　// init hystrixCommand
                            .observableExecutionMode(hystrixCommand.observableExecutionMode())
                            .executionType(executionType)
                            .observable(ExecutionType.OBSERVABLE == executionType)
                            .build();
        }
    }

基於MetaHolder創建Command

    @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);
        // 創建commond
        HystrixInvokable invokable = HystrixCommandFactory.getInstance().create(metaHolder);
        ExecutionType executionType = metaHolder.isCollapserAnnotationPresent() ?
                metaHolder.getCollapserExecutionType() : metaHolder.getExecutionType();

        Object result;
        try {
            if (!metaHolder.isObservable()) {
               // 執行
                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;
    }

  //com.netflix.hystrix.contrib.javanica.command.HystrixCommandFactory#create
  //初始化的同時將配置傳遞給父類com.netflix.hystrix.AbstractCommand
    public HystrixInvokable create(MetaHolder metaHolder) {
        HystrixInvokable executable;
        if (metaHolder.isCollapserAnnotationPresent()) {
            executable = new CommandCollapser(metaHolder);
        } else if (metaHolder.isObservable()) {
            executable = new GenericObservableCommand(HystrixCommandBuilderFactory.getInstance().create(metaHolder));
        } else {
            executable = new GenericCommand(HystrixCommandBuilderFactory.getInstance().create(metaHolder));
        }
        return executable;
    }

配置信息讀取

    public HystrixCommandBuilder create(MetaHolder metaHolder) {
        return create(metaHolder, Collections.<HystrixCollapser.CollapsedRequest<Object, Object>>emptyList());
    }

    public <ResponseType> HystrixCommandBuilder create(MetaHolder metaHolder, Collection<HystrixCollapser.CollapsedRequest<ResponseType, Object>> collapsedRequests) {
        validateMetaHolder(metaHolder);

        return HystrixCommandBuilder.builder()
                .setterBuilder(createGenericSetterBuilder(metaHolder))
                .commandActions(createCommandActions(metaHolder))
                .collapsedRequests(collapsedRequests)
                .cacheResultInvocationContext(createCacheResultInvocationContext(metaHolder))
                .cacheRemoveInvocationContext(createCacheRemoveInvocationContext(metaHolder))
                .ignoreExceptions(metaHolder.getCommandIgnoreExceptions())
                .executionType(metaHolder.getExecutionType())
                .build();
    }
    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();
    }

基於配置文件

// com.netflix.hystrix.HystrixCommandProperties
this.executionTimeoutInMilliseconds = getProperty(propertyPrefix, key, "execution.isolation.thread.timeoutInMilliseconds", builder.getExecutionIsolationThreadTimeoutInMilliseconds(), default_executionTimeoutInMilliseconds);

    private static HystrixProperty<Integer> getProperty(String propertyPrefix, HystrixCommandKey key, String instanceProperty, Integer builderOverrideValue, Integer defaultValue) {
        return forInteger()
                .add(propertyPrefix + ".command." + key.name() + "." + instanceProperty, builderOverrideValue)
                .add(propertyPrefix + ".command.default." + instanceProperty, defaultValue)
                .build();
    }

    //com.netflix.hystrix.strategy.properties.HystrixPropertiesChainedProperty#getDynamicProperty
    private static <T> HystrixDynamicProperty<T> 
        getDynamicProperty(String propName, T defaultValue, Class<T> type) {
        HystrixDynamicProperties properties = HystrixPlugins.getInstance().getDynamicProperties();
        HystrixDynamicProperty<T> p = 
                HystrixDynamicProperties.Util.getProperty(properties, propName, defaultValue, type);
        return p;
    }

基於archaius的屬性讀取

    public static DynamicPropertyFactory getInstance() {
        if (config == null) {
            synchronized (ConfigurationManager.class) {
                if (config == null) {
                　// ConfigurationManager中有spring配置文件中的屬性信息
                    AbstractConfiguration configFromManager = ConfigurationManager.getConfigInstance();
                    if (configFromManager != null) {
                        initWithConfigurationSource(configFromManager);
                        initializedWithDefaultConfig = !ConfigurationManager.isConfigurationInstalled();
                        logger.info("DynamicPropertyFactory is initialized with configuration sources: " + configFromManager);
                    }
                }
            }
        }
        return instance;
    }