BlockHoundIntegration for spring-core

build.gradle

@@ -64,6 +64,8 @@ configure(allprojects) { project ->
 			dependency "io.reactivex:rxjava-reactive-streams:1.2.1"
 			dependency "io.reactivex.rxjava2:rxjava:2.2.17"
 
+			dependency "io.projectreactor.tools:blockhound:1.0.2.RELEASE"
+
 			dependency "com.caucho:hessian:4.0.62"
 			dependency "com.fasterxml:aalto-xml:1.2.2"
 			dependency("com.fasterxml.woodstox:woodstox-core:6.0.3") {

spring-core/spring-core.gradle

@@ -43,6 +43,7 @@ dependencies {
 	compile(files(objenesisRepackJar))
 	compile(project(":spring-jcl"))
 	compileOnly(project(":kotlin-coroutines"))
+	compileOnly("io.projectreactor.tools:blockhound")
 	optional("net.sf.jopt-simple:jopt-simple")
 	optional("org.aspectj:aspectjweaver")
 	optional("org.jetbrains.kotlin:kotlin-reflect")
@@ -60,6 +61,7 @@ dependencies {
 	testCompile("javax.xml.bind:jaxb-api")
 	testCompile("com.fasterxml.woodstox:woodstox-core")
 	testCompile(project(":kotlin-coroutines"))
+	testCompile("io.projectreactor.tools:blockhound")
 	testFixturesImplementation("com.google.code.findbugs:jsr305")
 	testFixturesImplementation("io.projectreactor:reactor-test")
 	testFixturesImplementation("org.assertj:assertj-core")

spring-core/src/main/java/org/springframework/core/ReactiveAdapterRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -29,12 +29,15 @@ import io.reactivex.Flowable;
 import kotlinx.coroutines.CompletableDeferredKt;
 import kotlinx.coroutines.Deferred;
 import org.reactivestreams.Publisher;
+import reactor.blockhound.BlockHound;
+import reactor.blockhound.integration.BlockHoundIntegration;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import rx.RxReactiveStreams;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -354,4 +357,32 @@ public class ReactiveAdapterRegistry {
 			);
 		}
 	}
+
+
+	/**
+	 * {@code BlockHoundIntegration} for spring-core classes.
+	 * <p>Whitelists the following:
+	 * <ul>
+	 * <li>Reading class info via {@link LocalVariableTableParameterNameDiscoverer}.
+	 * <li>Locking within {@link ConcurrentReferenceHashMap}.
+	 * </ul>
+	 * @since 5.2.4
+	 */
+	public static class SpringCoreBlockHoundIntegration implements BlockHoundIntegration {
+
+		@Override
+		public void applyTo(BlockHound.Builder builder) {
+
+			// Avoid hard references potentially anywhere in spring-core (no need for structural dependency)
+
+			builder.allowBlockingCallsInside(
+					"org.springframework.core.LocalVariableTableParameterNameDiscoverer", "inspectClass");
+
+			String className = "org.springframework.util.ConcurrentReferenceHashMap$Segment";
+			builder.allowBlockingCallsInside(className, "doTask");
+			builder.allowBlockingCallsInside(className, "clear");
+			builder.allowBlockingCallsInside(className, "restructure");
+		}
+	}
+
 }

spring-core/src/main/resources/META-INF/services/reactor.blockhound.integration.BlockHoundIntegration

@@ -0,0 +1,15 @@
+# Copyright 2002-2020 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.
+
+org.springframework.core.ReactiveAdapterRegistry$SpringCoreBlockHoundIntegration

spring-core/src/test/java/org/springframework/core/SpringCoreBlockHoundIntegrationTests.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2002-2020 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.core;
+
+import java.lang.reflect.Method;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import reactor.blockhound.BlockHound;
+import reactor.core.scheduler.Schedulers;
+
+import org.springframework.tests.sample.objects.TestObject;
+import org.springframework.util.ConcurrentReferenceHashMap;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * Tests to verify the spring-core BlockHound integration rules.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.2.4
+ */
+public class SpringCoreBlockHoundIntegrationTests {
+
+
+	@BeforeAll
+	static void setUp() {
+		BlockHound.install();
+	}
+
+
+	@Test
+	void blockHoundIsInstalled() {
+		assertThatThrownBy(() -> testNonBlockingTask(() -> Thread.sleep(10)))
+				.hasMessageContaining("Blocking call!");
+	}
+
+	@Test
+	void localVariableTableParameterNameDiscoverer() {
+		testNonBlockingTask(() -> {
+			Method setName = TestObject.class.getMethod("setName", String.class);
+			String[] names = new LocalVariableTableParameterNameDiscoverer().getParameterNames(setName);
+			assertThat(names).isEqualTo(new String[] {"name"});
+		});
+	}
+
+	@Test
+	void concurrentReferenceHashMap() {
+		int size = 10000;
+		Map<String, String> map = new ConcurrentReferenceHashMap<>(size);
+
+		CompletableFuture<Object> future1 = new CompletableFuture<>();
+		testNonBlockingTask(() -> {
+			for (int i = 0; i < size / 2; i++) {
+				map.put("a" + i, "bar");
+			}
+		}, future1);
+
+		CompletableFuture<Object> future2 = new CompletableFuture<>();
+		testNonBlockingTask(() -> {
+			for (int i = 0; i < size / 2; i++) {
+				map.put("b" + i, "bar");
+			}
+		}, future2);
+
+		CompletableFuture.allOf(future1, future2).join();
+		assertThat(map).hasSize(size);
+	}
+
+	private void testNonBlockingTask(NonBlockingTask task) {
+		CompletableFuture<Object> future = new CompletableFuture<>();
+		testNonBlockingTask(task, future);
+		future.join();
+	}
+
+	private void testNonBlockingTask(NonBlockingTask task, CompletableFuture<Object> future) {
+		Schedulers.parallel().schedule(() -> {
+			try {
+				task.run();
+				future.complete(null);
+			}
+			catch (Throwable ex) {
+				future.completeExceptionally(ex);
+			}
+		});
+	}
+
+
+	@FunctionalInterface
+	private interface NonBlockingTask {
+
+		void run() throws Exception;
+	}
+
+}