From 57507cc3afb701dbbb13960f61a746f8f7328273 Mon Sep 17 00:00:00 2001
From: asahi <mikiyashiki@outlook.com>
Date: Thu, 4 Sep 2025 11:10:04 +0800
Subject: [PATCH] =?UTF-8?q?doc:=20=E9=98=85=E8=AF=BBspring=20cloud=20circu?=
 =?UTF-8?q?itBreaker=E6=96=87=E6=A1=A3?=
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---
 .../CircuitBreaker/CircuitBreaker.md          | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/spring/Spring Cloud/CircuitBreaker/CircuitBreaker.md b/spring/Spring Cloud/CircuitBreaker/CircuitBreaker.md
index 05d4296..2f93fc5 100644
--- a/spring/Spring Cloud/CircuitBreaker/CircuitBreaker.md	
+++ b/spring/Spring Cloud/CircuitBreaker/CircuitBreaker.md	
@@ -42,6 +42,9 @@
     - [Create a TimeLimiterRegistry](#create-a-timelimiterregistry)
     - [Create and configure TimeLimiter](#create-and-configure-timelimiter)
     - [decorate and execute a functional interface](#decorate-and-execute-a-functional-interface-4)
+  - [Spring Cloud CircuitBreaker](#spring-cloud-circuitbreaker)
+    - [core concepts](#core-concepts)
+    - [Configuration](#configuration)
 
 
 # CircuitBreaker
@@ -928,3 +931,45 @@ String result = timeLimiter.executeFutureSupplier(
 
 当发生等待超时时，将会根据`shouldCancelRunningFuture`参数的配置来决定`是否针对尚未执行完成的future调用cancel`。
 
+## Spring Cloud CircuitBreaker 
+Spring Cloud Circuit Breaker提供了circuit breaker的抽象，可以让开发者自由选择circuit breaker的实现。目前，spring cloud支持如下circuit breaker的实现：
+- Resilience4j
+- Sentinel
+- spring retry
+
+### core concepts
+可以通过`CircuitBreakerFactory` api来创建circuit breaker。在classpath中包含spring cloud circuit breaker starter时，将会自动创建实现了`CircuitBreakerFactory`的bean。如下示例展示了如何使用该api：
+```java
+@Service
+public static class DemoControllerService {
+    private RestTemplate rest;
+    private CircuitBreakerFactory cbFactory;
+
+    public DemoControllerService(RestTemplate rest, CircuitBreakerFactory cbFactory) {
+        this.rest = rest;
+        this.cbFactory = cbFactory;
+    }
+
+    public String slow() {
+        return cbFactory.create("slow").run(() -> rest.getForObject("/slow", String.class), throwable -> "fallback");
+    }
+
+}
+```
+`CircuitBreakerFactory.create`方法将会创建一个`CircuitBreaker`的实例，run方法将会接收一个Supplier和一个Function：
+- supplier是实际被封装在circuitbreaker中的方法
+- function是circuit breaker被触发之后的fallback
+  - function接收一个Throwable，throwable为导致该fallback被触发的异常
+
+### Configuration
+可以通过创建`Customizer`类型的bean来配置circuit breaker。
+
+在`Resilience4JCircuitBreaker`的实现中，每次调用`circuitbreaker#run`时，都会调用`Customizer#customize`方法，该行为可能会存在效率问题。故而，可以使用`Customizer#once`方法来创建Customizer，其会保证customizer中的逻辑最多只会被调用一次。
+
+示例如下所示：
+```java
+Customizer.once(circuitBreaker -> {
+  circuitBreaker.getEventPublisher()
+    .onStateTransition(event -> log.info("{}: {}", event.getCircuitBreakerName(), event.getStateTransition()));
+}, CircuitBreaker::getName)
+```