spring cloud resilience4j - RateLimiter 流量控制

朱雀 2022-12-29 15:27 421阅读 0赞

# 概述 #

resilience4j-ratelimiter 可以用来控制指定时间内的请求数量，从而保证服务的可靠性。

比如，我们调用的第三方接口（如百度api，face++)通常会有流量的限制，此时，我们可以通过resilience4j控制流量。

当流量超过限制时，可以直接抛弃，也可以放入等待队列中。

RateLimiter的默认实现是`AtomicRateLimiter`，通过`AtomicReference`来管理状态， AtomicRateLimiter.State是不可修改的，它有如下属性：

*  activeCycle： 上次调用占用的周期数，活跃周期数
 *  activePermissions：剩余的令牌数，当一个调用占用多个周期时，可能为负数。
 *  nanosToWait：获取令牌等待时间

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3hndzEwMTA_size_16_color_FFFFFF_t_70]  
另外也有一个通过信号量控制流量的实现`SemaphoreBasedRateLimiter`。

# 参数说明 #

<table> 
 <thead> 
  <tr> 
   <th>属性</th> 
   <th>默认值</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>timeoutDuration</td> 
   <td>5[s]</td> 
   <td>线程等待令牌的时间</td> 
  </tr> 
  <tr> 
   <td>limitRefreshPeriod</td> 
   <td>500[ns]</td> 
   <td>令牌刷新周期，每次刷新，剩余令牌数都恢复到默认值</td> 
  </tr> 
  <tr> 
   <td>limitForPeriod</td> 
   <td>50</td> 
   <td>每个周期的初始令牌数</td> 
  </tr> 
 </tbody> 
</table>

# 通过代码配置 #

//限制每秒10次调用
    RateLimiterConfig config = RateLimiterConfig.custom()
      .limitRefreshPeriod(Duration.ofSeconds(1))
      .limitForPeriod(10)
      .timeoutDuration(Duration.ofMillis(25))
      .build();
    // Create registry
    RateLimiterRegistry rateLimiterRegistry = RateLimiterRegistry.of(config);
    
    // Use registry
    RateLimiter rateLimiterWithDefaultConfig = rateLimiterRegistry
      .rateLimiter("name1");
    // Decorate your call to BackendService.doSomething()
    CheckedRunnable restrictedCall = RateLimiter
        .decorateCheckedRunnable(rateLimiterWithDefaultConfig, backendService::doSomething);
    Try.run(restrictedCall)
        .onFailure((RequestNotPermitted throwable) -> LOG.info("Wait before call it again :)"));

除了可以封装 CheckedRunnable，还可以封装Callable、Supplier、Runnable、Consumer、CheckedSupplier、CheckedConsumer、CompletionStage类型。

# spring注解实现流控 #

**application.yml**

resilience4j.ratelimiter:
        instances:
            backendA:
                limitForPeriod: 10
                limitRefreshPeriod: 1s
                timeoutDuration: 0
                registerHealthIndicator: true
                eventConsumerBufferSize: 100
            backendB:
                limitForPeriod: 6
                limitRefreshPeriod: 500ms
                timeoutDuration: 3s

代码：

@RateLimiter(name = "backendA",fallbackMethod = "fallback" )
    public Mono<String> method(String param1) { 
        return Mono.error(new NumberFormatException());
    }
    
    private Mono<String> fallback(String param1, IllegalArgumentException e) { 
        return Mono.just("test");
    }
    
    private Mono<String> fallback(String param1, RuntimeException e) { 
        return Mono.just("test");
    }

# 与Feign集成 #

依赖：

<dependency>
                <groupId>io.github.resilience4j</groupId>
                <artifactId>resilience4j-spring-boot2</artifactId>
                <version>1.6.1</version>
            </dependency>

@FeignClient(name = "x")
    interface TestClient { 
        @GetMapping("/test1")
        @RateLimiter(name = "x", fallbackMethod = "m1")
        String test1();
    
        @GetMapping("/test2")
        @RateLimiter(name = "x", fallbackMethod = "m2")
        String test2();
    
        default String m1(Exception e){ 
            // ....
            return "x";
        }
    
        default String m2(Exception e){ 
            // ....
            return "x";
        }
    }

# 更多 #

[spring cloud resilience4j-retry 重试][spring cloud resilience4j-retry]  
[spring cloud resilience4j - Bulkhead 线程隔离 并发控制][spring cloud resilience4j - Bulkhead _]  
[spring cloud Resilience4j - 熔断器 CircuitBreaker][spring cloud Resilience4j - _ CircuitBreaker]  
[spring cloud resilience4j - RateLimiter 流控][spring cloud resilience4j - RateLimiter]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3hndzEwMTA_size_16_color_FFFFFF_t_70]: /images/20221120/b9308c427e6841a4b321138a7e51513b.png
[spring cloud resilience4j-retry]: https://blog.csdn.net/xgw1010/article/details/111464801
[spring cloud resilience4j - Bulkhead _]: https://blog.csdn.net/xgw1010/article/details/111300196
[spring cloud Resilience4j - _ CircuitBreaker]: https://blog.csdn.net/xgw1010/article/details/108675113
[spring cloud resilience4j - RateLimiter]: https://blog.csdn.net/xgw1010/article/details/111590574