CircuitBreakerConfig(熔断器配置)

CircuitBreakerConfig类中封装了与熔断器相关的配置属性,属性包括:请求调用失败的阈值、熔断器在打开状态时的持续时间、熔断器在半开状态下的Ring Buffer大小、熔断器在关闭状态下的Ring Buffer大小、是否记录请求调用失败的断言。Ring Buffer的原理在后面研究CircuitBreakerMetrics部分时再详细讲解,现在只需要了解,它是一个存储每次请求调用成功与否的环形缓存区。

 

另外CircuitBreakerConfig类通过Builder模式构造CircuitBreakerConfig实例及流式的设置配置属性值。

需主要关注的源码如下:

public class CircuitBreakerConfig \{

//请求调用失败的阈值,百分比。默认是50%

public static final int DEFAULT\_MAX\_FAILURE\_THRESHOLD = 50; // Percentage

//熔断器在打开状态时的持续时间。默认是60秒

public static final int DEFAULT\_WAIT\_DURATION\_IN\_OPEN\_STATE = 60; // Seconds

//熔断器在半开状态下的ring buffer大小。默认10

public static final int DEFAULT\_RING\_BUFFER\_SIZE\_IN\_HALF\_OPEN\_STATE = 10;

//熔断器在关闭状态下的ring buffer大小。默认100

public static final int DEFAULT\_RING\_BUFFER\_SIZE\_IN\_CLOSED\_STATE = 100;

//是否记录请求调用失败的断言,默认所有异常都记录。

public static final Predicate<Throwable> DEFAULT\_RECORD\_FAILURE\_PREDICATE = (throwable) -> true;

......

/\*\* 构造者模式 \*/

public static class Builder \{

private Predicate<Throwable> recordFailurePredicate;

private Predicate<Throwable> errorRecordingPredicate;

//请求调用失败,存储异常记录的集合

private Class<? extends Throwable>\[\] recordExceptions = new Class\[0\];

//请求调用失败,忽略异常记录的集合

private Class<? extends Throwable>\[\] ignoreExceptions = new Class\[0\];

private float failureRateThreshold = DEFAULT\_MAX\_FAILURE\_THRESHOLD;

private int ringBufferSizeInHalfOpenState = DEFAULT\_RING\_BUFFER\_SIZE\_IN\_HALF\_OPEN\_STATE;

private int ringBufferSizeInClosedState = DEFAULT\_RING\_BUFFER\_SIZE\_IN\_CLOSED\_STATE;

private Duration waitDurationInOpenState = Duration.ofSeconds(DEFAULT\_WAIT\_DURATION\_IN\_OPEN\_STATE);

private boolean automaticTransitionFromOpenToHalfOpenEnabled = false;

/\*\* 构造CircuitBreakerConfig实例 \*/

public CircuitBreakerConfig build() \{

buildErrorRecordingPredicate();

CircuitBreakerConfig config = new CircuitBreakerConfig();

config.waitDurationInOpenState = waitDurationInOpenState;

config.failureRateThreshold = failureRateThreshold;

config.ringBufferSizeInClosedState = ringBufferSizeInClosedState;

config.ringBufferSizeInHalfOpenState = ringBufferSizeInHalfOpenState;

config.recordFailurePredicate = errorRecordingPredicate;

config.automaticTransitionFromOpenToHalfOpenEnabled = automaticTransitionFromOpenToHalfOpenEnabled;

return config;

\}

/\*\* 异常记录集合与异常忽略集合取交集,如果有值则为false,否则为true。\*/

private void buildErrorRecordingPredicate() \{

this.errorRecordingPredicate =

getRecordingPredicate()

.and(buildIgnoreExceptionsPredicate()

.orElse(DEFAULT\_RECORD\_FAILURE\_PREDICATE));

\}

......

\}

......

\}

下一篇文章《Resilience4j源码解析-2.3 CircuitBreaker模块之有限状态机》讲解熔断器的核心理念-有限状态机,及状态转换部分。

源码的中文注释地址:

https://github.com/Justin02180218/resilience4j