Support for late-determined cache misses from retrieve(key)

Closes gh-31637

spring-context-support/src/test/java/org/springframework/cache/caffeine/CaffeineReactiveCachingTests.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2002-2023 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cache.caffeine;
+
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import org.springframework.cache.CacheManager;
+import org.springframework.cache.annotation.CacheConfig;
+import org.springframework.cache.annotation.Cacheable;
+import org.springframework.cache.annotation.EnableCaching;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for annotation-based caching methods that use reactive operators.
+ *
+ * @author Juergen Hoeller
+ * @since 6.1
+ */
+public class CaffeineReactiveCachingTests {
+
+	@Test
+	void withCaffeineAsyncCache() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class, ReactiveCacheableService.class);
+		ReactiveCacheableService service = ctx.getBean(ReactiveCacheableService.class);
+
+		Object key = new Object();
+
+		Long r1 = service.cacheFuture(key).join();
+		Long r2 = service.cacheFuture(key).join();
+		Long r3 = service.cacheFuture(key).join();
+
+		assertThat(r1).isNotNull();
+		assertThat(r1).isSameAs(r2).isSameAs(r3);
+
+		key = new Object();
+
+		r1 = service.cacheMono(key).block();
+		r2 = service.cacheMono(key).block();
+		r3 = service.cacheMono(key).block();
+
+		assertThat(r1).isNotNull();
+		assertThat(r1).isSameAs(r2).isSameAs(r3);
+
+		key = new Object();
+
+		r1 = service.cacheFlux(key).blockFirst();
+		r2 = service.cacheFlux(key).blockFirst();
+		r3 = service.cacheFlux(key).blockFirst();
+
+		assertThat(r1).isNotNull();
+		assertThat(r1).isSameAs(r2).isSameAs(r3);
+
+		key = new Object();
+
+		List<Long> l1 = service.cacheFlux(key).collectList().block();
+		List<Long> l2 = service.cacheFlux(key).collectList().block();
+		List<Long> l3 = service.cacheFlux(key).collectList().block();
+
+		assertThat(l1).isNotNull();
+		assertThat(l1).isEqualTo(l2).isEqualTo(l3);
+
+		key = new Object();
+
+		r1 = service.cacheMono(key).block();
+		r2 = service.cacheMono(key).block();
+		r3 = service.cacheMono(key).block();
+
+		assertThat(r1).isNotNull();
+		assertThat(r1).isSameAs(r2).isSameAs(r3);
+
+		// Same key as for Mono, reusing its cached value
+
+		r1 = service.cacheFlux(key).blockFirst();
+		r2 = service.cacheFlux(key).blockFirst();
+		r3 = service.cacheFlux(key).blockFirst();
+
+		assertThat(r1).isNotNull();
+		assertThat(r1).isSameAs(r2).isSameAs(r3);
+	}
+
+
+	@CacheConfig(cacheNames = "first")
+	static class ReactiveCacheableService {
+
+		private final AtomicLong counter = new AtomicLong();
+
+		@Cacheable
+		CompletableFuture<Long> cacheFuture(Object arg) {
+			return CompletableFuture.completedFuture(this.counter.getAndIncrement());
+		}
+
+		@Cacheable
+		Mono<Long> cacheMono(Object arg) {
+			return Mono.just(this.counter.getAndIncrement());
+		}
+
+		@Cacheable
+		Flux<Long> cacheFlux(Object arg) {
+			return Flux.just(this.counter.getAndIncrement(), 0L);
+		}
+	}
+
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableCaching
+	static class Config {
+
+		@Bean
+		CacheManager cacheManager() {
+			CaffeineCacheManager ccm = new CaffeineCacheManager("first");
+			ccm.setAsyncCacheMode(true);
+			return ccm;
+		}
+	}
+
+}