Hystrix的Command的简单认识

爱被打了一巴掌 2022-04-04 06:48 660阅读 0赞

<dependency>
        <groupId>com.netflix.hystrix</groupId>
        <artifactId>hystrix-core</artifactId>
        <version>1.5.12</version>
    </dependency>

package com.roncoo.eshop.cache.ha.hystrix.command;
    
    import org.springframework.boot.context.embedded.FilterRegistrationBean;
    import org.springframework.context.annotation.Bean;
    
    import com.netflix.hystrix.HystrixCommand;
    import com.netflix.hystrix.HystrixCommandGroupKey;
    import com.netflix.hystrix.HystrixCommandKey;
    import com.netflix.hystrix.HystrixCommandProperties;
    import com.netflix.hystrix.HystrixRequestCache;
    import com.netflix.hystrix.HystrixThreadPoolKey;
    import com.netflix.hystrix.HystrixThreadPoolProperties;
    import com.netflix.hystrix.HystrixCommandProperties.ExecutionIsolationStrategy;
    import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault;
    import com.roncoo.eshop.cache.ha.filter.HystrixRequestContextFilter;
    
    /** 
     * @ClassName: HystrixCommandDemo 
     * @date 2018年12月15日 下午2:17:51 
     */
    public class HystrixCommandDemo extends HystrixCommand<String> {
    
    	private String key;
    	private static final HystrixCommandKey COMMAND_KEY = HystrixCommandKey.Factory.asKey("key");
    
    	public HystrixCommandDemo(String key) {
    		super(Setter
    				.withGroupKey(HystrixCommandGroupKey.Factory.asKey("groupKeyName"))
    				.andCommandKey(COMMAND_KEY)
    				.andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("threadPoolKey"))
    				.andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter().withCoreSize(10).withQueueSizeRejectionThreshold(10))
    				.andCommandPropertiesDefaults(
    						HystrixCommandProperties.Setter().withFallbackIsolationSemaphoreMaxConcurrentRequests(20).withExecutionTimeoutEnabled(true)
    								.withExecutionTimeoutInMilliseconds(1000).withExecutionIsolationStrategy(ExecutionIsolationStrategy.SEMAPHORE)
    								.withExecutionIsolationSemaphoreMaxConcurrentRequests(15).withCircuitBreakerEnabled(true)
    								.withCircuitBreakerRequestVolumeThreshold(20).withCircuitBreakerRequestVolumeThreshold(50)
    								.withCircuitBreakerSleepWindowInMilliseconds(5000).withCircuitBreakerErrorThresholdPercentage(50)
    								.withCircuitBreakerForceOpen(false).withCircuitBreakerForceClosed(false)));
    		// 组名，统一管理命令，比如报告、警报、仪表盘和。默认情况下，HystrixCommandGroupKey的名字即为线程池的名字，除非自定义线程池
    		Setter setter = Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("groupKeyName"));
    		// 命令的名称
    		setter.andCommandKey(COMMAND_KEY);
    		// 不指定线程池时，hystrix会默认以HystrixCommandGroupKey创建一个，一个HystrixCommand与一个HystrixThreadPoolKey相关联
    		setter.andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("threadPoolKey"));
    		// 线程池核心线程数及队列容量
    		setter.andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter().withCoreSize(10).withQueueSizeRejectionThreshold(10));
    		// fallback降级信号量数
    		setter.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withFallbackIsolationSemaphoreMaxConcurrentRequests(20));
    		// 是否开启command超时，默认为true
    		// 设置command执行超时时间，如果超时，将调用fallback降级
    		setter.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withExecutionTimeoutEnabled(true).withExecutionTimeoutInMilliseconds(1000));
    		// 信号量资源隔离与限流
    		setter.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withExecutionIsolationStrategy(ExecutionIsolationStrategy.SEMAPHORE)
    				.withExecutionIsolationSemaphoreMaxConcurrentRequests(15));
    		// 是否允许断路器工作，包括跟踪服务调用的健康状况、异常请求过多是否允许开启断路器，默认为true
    		// 最少要有多少个请求才触发断路器，默认值为20；
    		// 短路之后，在多少毫秒之内对请求直接reject，然后在这段时间之后，引导断路器half-open，尝试自动恢复，默认值5000毫秒；
    		// 设置异常请求量百分比，当异常请求达到这个百分比，开启断路器，默认50%；
    		// 是否手动打开断路器，默认false；
    		// 是否手动关闭断路器，默认false；
    		setter.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withCircuitBreakerEnabled(true).withCircuitBreakerRequestVolumeThreshold(20)
    				.withCircuitBreakerSleepWindowInMilliseconds(5000).withCircuitBreakerErrorThresholdPercentage(50).withCircuitBreakerForceOpen(false)
    				.withCircuitBreakerForceClosed(false));
    		this.key = key;
    
    	}
    
    	@Override
    	protected String run() throws Exception {
    		return null;
    	}
    
    	/**
    	 * request cache，对每一次请求，都初始化一个hystrix的请求上下文，java web通常用filter来实现
    	 * public class HystrixRequestContextFilter implements Filter {
    			public void init(FilterConfig config) throws ServletException {
    			}
    			public void doFilter(ServletRequest request, ServletResponse response,
    					FilterChain chain) throws IOException, ServletException {
    				HystrixRequestContext context = HystrixRequestContext.initializeContext();
    				try {
    					chain.doFilter(request, response); 
    				} catch (Exception e) {
    					e.printStackTrace();
    				} finally {
    					context.shutdown();
    				}
    			}
    			public void destroy() {
    			}
    		}
    		@Bean
    	    public FilterRegistrationBean filterRegistrationBean() {
    	    	FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(
    	    			new HystrixRequestContextFilter());
    	    	filterRegistrationBean.addUrlPatterns("/*");
    	    	return filterRegistrationBean;
    	    }
    	 * @Title: getCacheKey 
    	 * @see com.netflix.hystrix.AbstractCommand#getCacheKey() 
    	 * @return  
    	 */
    	@Override
    	protected String getCacheKey() {
    		return "key:" + key;
    	}
    
    	/**
    	 * 手动删除hystrix的request cache
    	 * @Title: flushCacheKey 
    	 * @param key  
    	 */
    	public static void flushCacheKey(String key) {
    		HystrixRequestCache.getInstance(COMMAND_KEY, HystrixConcurrencyStrategyDefault.getInstance()).clear(key);
    	}
    
    	/**
    	 * 通过信号量控制并发请求的降级，默认是10，如果超过了10，则会reject
    	 * 可以通过.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withFallbackIsolationSemaphoreMaxConcurrentRequests(20))配置
    	 * @Title: getFallback 
    	 * @see com.netflix.hystrix.HystrixCommand#getFallback() 
    	 * @return  
    	 */
    	@Override
    	protected String getFallback() {
    		return null;
    	}
    }