GH-82: Expose @CircuitBreaker.throwLastExceptionOnExhausted()

Fixes: #82

There are some use-cases when `ExhaustedRetryException` does not fit into the logic around Circuit Breaker pattern.

The `RetryTemplate` has already a `throwLastExceptionOnExhausted` flag for stateful retries

* Expose `@CircuitBreaker.throwLastExceptionOnExhausted()` and propagate it down to the `RetryTemplate`
in the `AnnotationAwareRetryOperationsInterceptor`

src/main/java/org/springframework/retry/annotation/AnnotationAwareRetryOperationsInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2023 the original author or authors.
+ * Copyright 2006-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -252,6 +252,7 @@ public class AnnotationAwareRetryOperationsInterceptor implements IntroductionIn
 			resetTimeout(breaker, circuit);
 			template.setRetryPolicy(breaker);
 			template.setBackOffPolicy(new NoBackOffPolicy());
+			template.setThrowLastExceptionOnExhausted(circuit.throwLastExceptionOnExhausted());
 			String label = circuit.label();
 			if (!StringUtils.hasText(label)) {
 				label = method.toGenericString();

src/main/java/org/springframework/retry/annotation/CircuitBreaker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -181,4 +181,13 @@ public @interface CircuitBreaker {
 	@AliasFor(annotation = Retryable.class)
 	String exceptionExpression() default "";
 
+	/**
+	 * Set to {@code true} to not wrap last exception to the
+	 * {@link org.springframework.retry.ExhaustedRetryException} when retry is exhausted.
+	 * @return the boolean flag to whether wrap the last exception to the
+	 * {@link org.springframework.retry.ExhaustedRetryException}
+	 * @since 2.0.6
+	 */
+	boolean throwLastExceptionOnExhausted() default false;
+
 }

src/main/java/org/springframework/retry/policy/ExpressionRetryPolicy.java

@@ -115,8 +115,8 @@ public class ExpressionRetryPolicy extends SimpleRetryPolicy implements BeanFact
 			return super.canRetry(context);
 		}
 		else {
-			return super.canRetry(context)
-					&& Boolean.TRUE.equals(this.expression.getValue(this.evaluationContext, lastThrowable, Boolean.class));
+			return super.canRetry(context) && Boolean.TRUE
+				.equals(this.expression.getValue(this.evaluationContext, lastThrowable, Boolean.class));
 		}
 	}
 

src/test/java/org/springframework/retry/annotation/CircuitBreakerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2023 the original author or authors.
+ * Copyright 2006-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@ import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.retry.ExhaustedRetryException;
 import org.springframework.retry.RetryContext;
 import org.springframework.retry.policy.CircuitBreakerRetryPolicy;
 import org.springframework.retry.support.RetrySynchronizationManager;
@@ -106,15 +107,21 @@ public class CircuitBreakerTests {
 		assertThat(maxAttempts.get()).isEqualTo(10);
 		CircuitBreakerRetryPolicy policy = TestUtils.getPropertyValue(interceptor, "retryOperations.retryPolicy",
 				CircuitBreakerRetryPolicy.class);
-		Supplier openTO = TestUtils.getPropertyValue(policy, "openTimeoutSupplier", Supplier.class);
+		Supplier<?> openTO = TestUtils.getPropertyValue(policy, "openTimeoutSupplier", Supplier.class);
 		assertThat(openTO).isNotNull();
 		assertThat(openTO.get()).isEqualTo(10000L);
-		Supplier resetTO = TestUtils.getPropertyValue(policy, "resetTimeoutSupplier", Supplier.class);
+		Supplier<?> resetTO = TestUtils.getPropertyValue(policy, "resetTimeoutSupplier", Supplier.class);
 		assertThat(resetTO).isNotNull();
 		assertThat(resetTO.get()).isEqualTo(20000L);
 		RetryContext ctx = service.getContext();
 		assertThat(TestUtils.getPropertyValue(ctx, "openWindow")).isEqualTo(10000L);
 		assertThat(TestUtils.getPropertyValue(ctx, "timeout")).isEqualTo(20000L);
+
+		assertThatExceptionOfType(ExhaustedRetryException.class).isThrownBy(service::exhaustedRetryService);
+
+		assertThatExceptionOfType(RuntimeException.class).isThrownBy(service::noWrapExhaustedRetryService)
+			.withMessage("Planned");
+
 		context.close();
 	}
 
@@ -154,6 +161,10 @@ public class CircuitBreakerTests {
 
 		void expressionService3();
 
+		void exhaustedRetryService();
+
+		void noWrapExhaustedRetryService();
+
 		int getCount();
 
 		RetryContext getContext();
@@ -197,6 +208,18 @@ public class CircuitBreakerTests {
 			this.count++;
 		}
 
+		@Override
+		@CircuitBreaker
+		public void exhaustedRetryService() {
+			throw new RuntimeException("Planned");
+		}
+
+		@Override
+		@CircuitBreaker(throwLastExceptionOnExhausted = true)
+		public void noWrapExhaustedRetryService() {
+			throw new RuntimeException("Planned");
+		}
+
 		@Override
 		public RetryContext getContext() {
 			return this.context;