6Hystrix 清除缓存 · SpringCloud微服务实战 · 看云

6. Hystrix 清除缓存

导航

有缓存设置就必然会有缓存清除，当代数据发生变动的时候，需要清除缓存，不让会造成脏数据。

本节代码地址

GitHub: https://github.com/xuyisu/fw-sping-cloud/tree/master/fw-cloud-hystrix/fw-cloud-hystrix-without-springcloud

6.1 新建FwHystrixCommondFlushCache类

方法里面设置了HystrixCommandKey 用来指明删除缓存的Key。通过手动执行
FwHystrixCommondFlushCache.flushCache("test");可以实现将缓存删除。


@Slf4j
public class FwHystrixCommondFlushCache extends HystrixCommand<String> {

    public static final HystrixCommandKey TEST_KEY = HystrixCommandKey.Factory.asKey("TestKey");
    private final String name;

    protected FwHystrixCommondFlushCache(String name) {
        super(HystrixCommand.Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("myGroup"))
                .andCommandKey(TEST_KEY));
        this.name = name;
    }

    @Override
    protected String run() {
        log.info("get data，{}", this.name);
        return this.name + ":" + Thread.currentThread().getName();
    }

    
    private static void flushCache(String name) {
        HystrixRequestCache.getInstance(TEST_KEY,
                HystrixConcurrencyStrategyDefault.getInstance()).clear(name);
    }

    @Override
    protected String getCacheKey() {
        return this.name;
    }


    public static void main(String[] args) throws ExecutionException, InterruptedException {
        HystrixRequestContext context = HystrixRequestContext.initializeContext();
        for (int i = 0; i <5 ; i++) {
            FwHystrixCommondFlushCache test = new FwHystrixCommondFlushCache("test");
            log.info(test.execute());
            FwHystrixCommondFlushCache.flushCache("test");
        }
        context.shutdown();
    }
}

6.2 执行main方法

14:24:12.662 [hystrix-myGroup-1] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:24:12.670 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1
14:24:12.673 [hystrix-myGroup-2] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:24:12.674 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-2
14:24:12.675 [hystrix-myGroup-3] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:24:12.676 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-3
14:24:12.678 [hystrix-myGroup-4] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:24:12.679 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-4
14:24:12.680 [hystrix-myGroup-5] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:24:12.681 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-5

如果我们在将方法FwHystrixCommondFlushCache.flushCache("test");注释掉，可以看到run()方法仍然被执行一次，因此清缓存OK

14:30:24.144 [hystrix-myGroup-1] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - get data，test
14:30:24.151 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1
14:30:24.154 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1
14:30:24.154 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1
14:30:24.154 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1
14:30:24.154 [main] INFO com.yisu.hystrix.without.FwHystrixCommondFlushCache - test:hystrix-myGroup-1