Hystrix实现Request Cache减压

Dear 丶 2023-01-01 04:52 95阅读 0赞

本篇配置类及其他代码可参考[《Hystrix使用fallback完成消费降级》][Hystrix_fallback]

我们在Hystrix下新建一个CacheService

@Slf4j
    @Service
    public class RequestCacheService { 
    
        @Autowired
        private MyService service;
    
        @CacheResult
        @HystrixCommand(commandKey = "cacheKey")
        public Friend requestCache(@CacheKey String name) { 
            log.info("request cache " + name);
            Friend friend = new Friend();
            friend.setName(name);
            friend = service.sayHiPost(friend);
            log.info("after requesting cache " + name);
            return friend;
        }
    }

建立一个测试Controller，在这里我们尝试调用两次`requestCache()`

@GetMapping("/cache")
    publicFriend cache(String name) { 
        @Cleanup HystrixRequestContext context = HystrixRequestContext.initializeContext();
    
        Friend friend = requestCacheService.requestCache(name);
        friend = requestCacheService.requestCache(name);
        return friend;
    }

启动项目，我们调用`localhost:50000/cache?name=王老五`  
可以看到Feign的日志中，只触发了一次调用  
![在这里插入图片描述][2020123115142034.png]  
我们对`cache()`函数稍微做一点修改

@GetMapping("/cache")
    publicFriend cache(String name) { 
        @Cleanup HystrixRequestContext context =  HystrixRequestContext.initializeContext();
    
        Friend friend = requestCacheService.requestCache(name);
        name += "!";
        friend = requestCacheService.requestCache(name);
        return friend;
    }

重启项目，再次请求，这时候能看到Feign中触发了两次调用  
![在这里插入图片描述][20201231151942451.png]  
说明`@CacheKey`已经生效了，在传入相同key时，触发了Hystrix的缓存!

[Hystrix_fallback]: https://jiandansuifeng.blog.csdn.net/article/details/112003533
[2020123115142034.png]: /images/20221120/3c73c219a9f242aaae31b4eb21c43db4.png
[20201231151942451.png]: /images/20221120/dcee93a4ff974a4ba3005ab44d64c874.png