Add Coroutines support for `@Cacheable`

This commit adds Coroutines support for `@Cacheable`.

It also refines SimpleKeyGenerator to ignore Continuation
parameters (Kotlin does not allow to have the same method
signature with both suspending and non-suspending variants)
and refines
org.springframework.aop.framework.CoroutinesUtils.awaitSingleOrNull
in order to wrap plain value to Mono.

Closes gh-31412

spring-aop/src/main/java/org/springframework/aop/framework/CoroutinesUtils.java

@@ -36,10 +36,11 @@ abstract class CoroutinesUtils {
 		return ReactiveFlowKt.asFlow((Publisher<?>) publisher);
 	}
 
-	@SuppressWarnings("unchecked")
 	@Nullable
-	static Object awaitSingleOrNull(Object mono, Object continuation) {
-		return MonoKt.awaitSingleOrNull((Mono<?>) mono, (Continuation<Object>) continuation);
+	@SuppressWarnings({"unchecked", "rawtypes"})
+	static Object awaitSingleOrNull(Object value, Object continuation) {
+		return MonoKt.awaitSingleOrNull(value instanceof Mono mono ? mono : Mono.just(value),
+				(Continuation<Object>) continuation);
 	}
 
 }

spring-context/spring-context.gradle

@@ -30,6 +30,7 @@ dependencies {
 	optional("org.hibernate:hibernate-validator")
 	optional("org.jetbrains.kotlin:kotlin-reflect")
 	optional("org.jetbrains.kotlin:kotlin-stdlib")
+	optional("org.jetbrains.kotlinx:kotlinx-coroutines-core")
 	optional("org.reactivestreams:reactive-streams")
 	testFixturesApi("org.junit.jupiter:junit-jupiter-api")
 	testFixturesImplementation(testFixtures(project(":spring-beans")))

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -48,6 +48,7 @@ import org.springframework.cache.Cache;
 import org.springframework.cache.CacheManager;
 import org.springframework.context.expression.AnnotatedElementKey;
 import org.springframework.core.BridgeMethodResolver;
+import org.springframework.core.KotlinDetector;
 import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.expression.EvaluationContext;
@@ -85,6 +86,7 @@ import org.springframework.util.function.SupplierUtils;
  * @author Phillip Webb
  * @author Sam Brannen
  * @author Stephane Nicoll
+ * @author Sebastien Deleuze
  * @since 3.1
  */
 public abstract class CacheAspectSupport extends AbstractCacheInvoker
@@ -1024,6 +1026,9 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 									() -> Mono.from(adapter.toPublisher(invokeOperation(invoker))).toFuture())));
 				}
 			}
+			if (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isSuspendingFunction(method)) {
+				return Mono.fromFuture(cache.retrieve(key, () -> ((Mono<?>) invokeOperation(invoker)).toFuture()));
+			}
 			return NOT_HANDLED;
 		}
 

spring-context/src/main/java/org/springframework/cache/interceptor/CacheInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -19,9 +19,15 @@ package org.springframework.cache.interceptor;
 import java.io.Serializable;
 import java.lang.reflect.Method;
 
+import kotlin.coroutines.Continuation;
+import kotlin.coroutines.CoroutineContext;
+import kotlinx.coroutines.Job;
 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;
+import org.reactivestreams.Publisher;
 
+import org.springframework.core.CoroutinesUtils;
+import org.springframework.core.KotlinDetector;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -39,6 +45,7 @@ import org.springframework.util.Assert;
  *
  * @author Costin Leau
  * @author Juergen Hoeller
+ * @author Sebastien Deleuze
  * @since 3.1
  */
 @SuppressWarnings("serial")
@@ -51,6 +58,9 @@ public class CacheInterceptor extends CacheAspectSupport implements MethodInterc
 
 		CacheOperationInvoker aopAllianceInvoker = () -> {
 			try {
+				if (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isSuspendingFunction(method)) {
+					return KotlinDelegate.invokeSuspendingFunction(method, invocation.getThis(), invocation.getArguments());
+				}
 				return invocation.proceed();
 			}
 			catch (Throwable ex) {
@@ -68,4 +78,16 @@ public class CacheInterceptor extends CacheAspectSupport implements MethodInterc
 		}
 	}
 
+	/**
+	 * Inner class to avoid a hard dependency on Kotlin at runtime.
+	 */
+	private static class KotlinDelegate {
+
+		public static Publisher<?> invokeSuspendingFunction(Method method, Object target, Object... args) {
+			Continuation<?>  continuation = (Continuation<?>) args[args.length - 1];
+			CoroutineContext coroutineContext = continuation.getContext().minusKey(Job.Key);
+			return CoroutinesUtils.invokeSuspendingFunction(coroutineContext, method, target, args);
+		}
+	}
+
 }

spring-context/src/main/java/org/springframework/cache/interceptor/SimpleKeyGenerator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * 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.
@@ -17,6 +17,9 @@
 package org.springframework.cache.interceptor;
 
 import java.lang.reflect.Method;
+import java.util.Arrays;
+
+import org.springframework.core.KotlinDetector;
 
 /**
  * Simple key generator. Returns the parameter itself if a single non-null
@@ -30,6 +33,7 @@ import java.lang.reflect.Method;
  *
  * @author Phillip Webb
  * @author Juergen Hoeller
+ * @author Sebastien Deleuze
  * @since 4.0
  * @see SimpleKey
  * @see org.springframework.cache.annotation.CachingConfigurer
@@ -38,7 +42,8 @@ public class SimpleKeyGenerator implements KeyGenerator {
 
 	@Override
 	public Object generate(Object target, Method method, Object... params) {
-		return generateKey(params);
+		return generateKey((KotlinDetector.isSuspendingFunction(method) ?
+				Arrays.copyOf(params, params.length - 1) : params));
 	}
 
 	/**

spring-context/src/main/java/org/springframework/context/expression/MethodBasedEvaluationContext.java

@@ -19,6 +19,7 @@ package org.springframework.context.expression;
 import java.lang.reflect.Method;
 import java.util.Arrays;
 
+import org.springframework.core.KotlinDetector;
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.lang.Nullable;
@@ -37,6 +38,7 @@ import org.springframework.util.ObjectUtils;
  *
  * @author Stephane Nicoll
  * @author Juergen Hoeller
+ * @author Sebastien Deleuze
  * @since 4.2
  */
 public class MethodBasedEvaluationContext extends StandardEvaluationContext {
@@ -55,7 +57,8 @@ public class MethodBasedEvaluationContext extends StandardEvaluationContext {
 
 		super(rootObject);
 		this.method = method;
-		this.arguments = arguments;
+		this.arguments = (KotlinDetector.isSuspendingFunction(method) ?
+				Arrays.copyOf(arguments, arguments.length - 1) : arguments);
 		this.parameterNameDiscoverer = parameterNameDiscoverer;
 	}
 

spring-context/src/test/java/org/springframework/cache/interceptor/SimpleKeyGeneratorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * 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.
@@ -16,9 +16,12 @@
 
 package org.springframework.cache.interceptor;
 
+import java.lang.reflect.Method;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.testfixture.io.SerializationTestUtils;
+import org.springframework.util.ReflectionUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -28,6 +31,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Phillip Webb
  * @author Stephane Nicoll
  * @author Juergen Hoeller
+ * @author Sebastien Deleuze
  */
 public class SimpleKeyGeneratorTests {
 
@@ -126,7 +130,8 @@ public class SimpleKeyGeneratorTests {
 
 
 	private Object generateKey(Object[] arguments) {
-		return this.generator.generate(null, null, arguments);
+		Method method = ReflectionUtils.findMethod(this.getClass(), "generateKey", Object[].class);
+		return this.generator.generate(this, method, arguments);
 	}
 
 }

spring-context/src/test/kotlin/org/springframework/cache/KotlinCacheReproTests.kt

@@ -0,0 +1,148 @@
+/*
+ * 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
+
+import kotlinx.coroutines.runBlocking
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.springframework.beans.testfixture.beans.TestBean
+import org.springframework.cache.CacheReproTests.*
+import org.springframework.cache.annotation.CacheEvict
+import org.springframework.cache.annotation.CachePut
+import org.springframework.cache.annotation.Cacheable
+import org.springframework.cache.annotation.EnableCaching
+import org.springframework.cache.concurrent.ConcurrentMapCacheManager
+import org.springframework.context.annotation.AnnotationConfigApplicationContext
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+
+class KotlinCacheReproTests {
+
+	@Test
+	fun spr14235AdaptsToSuspendingFunction() {
+		runBlocking {
+			val context = AnnotationConfigApplicationContext(
+				Spr14235Config::class.java,
+				Spr14235SuspendingService::class.java
+			)
+			val bean = context.getBean(Spr14235SuspendingService::class.java)
+			val cache = context.getBean(CacheManager::class.java).getCache("itemCache")!!
+			val tb: TestBean = bean.findById("tb1")
+			assertThat(bean.findById("tb1")).isSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+			bean.clear()
+			val tb2: TestBean = bean.findById("tb1")
+			assertThat(tb2).isNotSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb2)
+			bean.clear()
+			bean.insertItem(tb)
+			assertThat(bean.findById("tb1")).isSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+			context.close()
+		}
+	}
+
+	@Test
+	fun spr14235AdaptsToSuspendingFunctionWithSync() {
+		runBlocking {
+			val context = AnnotationConfigApplicationContext(
+				Spr14235Config::class.java,
+				Spr14235SuspendingServiceSync::class.java
+			)
+			val bean = context.getBean(Spr14235SuspendingServiceSync::class.java)
+			val cache = context.getBean(CacheManager::class.java).getCache("itemCache")!!
+			val tb = bean.findById("tb1")
+			assertThat(bean.findById("tb1")).isSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+			cache.clear()
+			val tb2 = bean.findById("tb1")
+			assertThat(tb2).isNotSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb2)
+			cache.clear()
+			bean.insertItem(tb)
+			assertThat(bean.findById("tb1")).isSameAs(tb)
+			assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+			context.close()
+		}
+	}
+
+	@Test
+	fun spr15271FindsOnInterfaceWithInterfaceProxy() {
+		val context = AnnotationConfigApplicationContext(Spr15271ConfigA::class.java)
+		val bean = context.getBean(Spr15271Interface::class.java)
+		val cache = context.getBean(CacheManager::class.java).getCache("itemCache")!!
+		val tb = TestBean("tb1")
+		bean.insertItem(tb)
+		assertThat(bean.findById("tb1").get()).isSameAs(tb)
+		assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+		context.close()
+	}
+
+	@Test
+	fun spr15271FindsOnInterfaceWithCglibProxy() {
+		val context = AnnotationConfigApplicationContext(Spr15271ConfigB::class.java)
+		val bean = context.getBean(Spr15271Interface::class.java)
+		val cache = context.getBean(CacheManager::class.java).getCache("itemCache")!!
+		val tb = TestBean("tb1")
+		bean.insertItem(tb)
+		assertThat(bean.findById("tb1").get()).isSameAs(tb)
+		assertThat(cache["tb1"]!!.get()).isSameAs(tb)
+		context.close()
+	}
+
+
+	open class Spr14235SuspendingService {
+
+		@Cacheable(value = ["itemCache"])
+		open suspend fun findById(id: String): TestBean {
+			return TestBean(id)
+		}
+
+		@CachePut(cacheNames = ["itemCache"], key = "#item.name")
+		open suspend fun insertItem(item: TestBean): TestBean {
+			return item
+		}
+
+		@CacheEvict(cacheNames = ["itemCache"], allEntries = true)
+		open suspend fun clear() {
+		}
+	}
+
+
+	open class Spr14235SuspendingServiceSync {
+		@Cacheable(value = ["itemCache"], sync = true)
+		open suspend fun findById(id: String): TestBean {
+			return TestBean(id)
+		}
+
+		@CachePut(cacheNames = ["itemCache"], key = "#item.name")
+		open suspend fun insertItem(item: TestBean): TestBean {
+			return item
+		}
+	}
+
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableCaching
+	class Spr14235Config {
+		@Bean
+		fun cacheManager(): CacheManager {
+			return ConcurrentMapCacheManager()
+		}
+	}
+
+}

spring-context/src/test/kotlin/org/springframework/cache/interceptor/KotlinSimpleKeyGeneratorTests.kt

@@ -0,0 +1,71 @@
+/*
+ * 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.interceptor
+
+import io.mockk.mockk
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.springframework.util.ReflectionUtils
+import kotlin.coroutines.Continuation
+
+/**
+ * Tests for [SimpleKeyGenerator] and [SimpleKey].
+ *
+ * @author Sebastien Deleuze
+ */
+class KotlinSimpleKeyGeneratorTests {
+
+	private val generator = SimpleKeyGenerator()
+
+	@Test
+	fun ignoreContinuationArgumentWithNoParameter() {
+		val method = ReflectionUtils.findMethod(javaClass, "suspendingMethod", Continuation::class.java)!!
+		val continuation = mockk<Continuation<Any>>()
+		val key = generator.generate(this, method, continuation)
+		assertThat(key).isEqualTo(SimpleKey.EMPTY)
+	}
+
+	@Test
+	fun ignoreContinuationArgumentWithOneParameter() {
+		val method = ReflectionUtils.findMethod(javaClass, "suspendingMethod", String::class.java, Continuation::class.java)!!
+		val continuation = mockk<Continuation<Any>>()
+		val key = generator.generate(this, method, "arg", continuation)
+		assertThat(key).isEqualTo("arg")
+	}
+
+	@Test
+	fun ignoreContinuationArgumentWithMultipleParameters() {
+		val method = ReflectionUtils.findMethod(javaClass, "suspendingMethod", String::class.java, String::class.java, Continuation::class.java)!!
+		val continuation = mockk<Continuation<Any>>()
+		val key = generator.generate(this, method, "arg1", "arg2", continuation)
+		assertThat(key).isEqualTo(SimpleKey("arg1", "arg2"))
+	}
+
+
+	@Suppress("unused", "RedundantSuspendModifier")
+	suspend fun suspendingMethod() {
+	}
+
+	@Suppress("unused", "UNUSED_PARAMETER", "RedundantSuspendModifier")
+	suspend fun suspendingMethod(param: String) {
+	}
+
+	@Suppress("unused", "UNUSED_PARAMETER", "RedundantSuspendModifier")
+	suspend fun suspendingMethod(param1: String, param2: String) {
+	}
+
+}