WebSession creation does not block

Closes gh-24027

Author: rstoyanchev

spring-web/src/main/java/org/springframework/web/server/session/InMemoryWebSessionStore.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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 java.util.concurrent.locks.ReentrantLock;
 
 import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Schedulers;
 
 import org.springframework.util.Assert;
 import org.springframework.util.IdGenerator;
@@ -111,9 +112,14 @@ public Map<String, WebSession> getSessions() {
 
 	@Override
 	public Mono<WebSession> createWebSession() {
+
+		// Opportunity to clean expired sessions
 		Instant now = this.clock.instant();
 		this.expiredSessionChecker.checkIfNecessary(now);
-		return Mono.fromSupplier(() -> new InMemoryWebSession(now));
+
+		return Mono.fromSupplier(() -> new InMemoryWebSession(now))
+				.subscribeOn(Schedulers.boundedElastic())
+				.cast(WebSession.class);
 	}
 
 	@Override

spring-web/src/test/java/org/springframework/web/server/session/InMemoryWebSessionStoreTests.java

@@ -22,7 +22,10 @@
 import java.util.Map;
 import java.util.stream.IntStream;
 
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Schedulers;
 
 import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.web.server.WebSession;
@@ -56,6 +59,14 @@ public void startsSessionImplicitly() {
 		assertThat(session.isStarted()).isTrue();
 	}
 
+	@Disabled // TODO: remove if/when Blockhound is enabled
+	@Test // gh-24027
+	public void createSessionDoesNotBlock() {
+		Mono.defer(() -> this.store.createWebSession())
+				.subscribeOn(Schedulers.parallel())
+				.block();
+	}
+
 	@Test
 	public void retrieveExpiredSession() {
 		WebSession session = this.store.createWebSession().block();

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ModelInitializerTests.java

@@ -64,6 +64,9 @@
  */
 public class ModelInitializerTests {
 
+	private static final Duration TIMEOUT = Duration.ofMillis(5000);
+
+
 	private ModelInitializer modelInitializer;
 
 	private final ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/path"));
@@ -93,7 +96,7 @@ public void initBinderMethod() {
 
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(GetMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
-		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000));
+		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT);
 
 		WebExchangeDataBinder binder = context.createDataBinder(this.exchange, "name");
 		assertThat(binder.getValidators()).isEqualTo(Collections.singletonList(validator));
@@ -107,7 +110,7 @@ public void modelAttributeMethods() {
 
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(GetMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
-		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000));
+		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT);
 
 		Map<String, Object> model = context.getModel().asMap();
 		assertThat(model.size()).isEqualTo(5);
@@ -116,7 +119,7 @@ public void modelAttributeMethods() {
 		assertThat(((TestBean) value).getName()).isEqualTo("Bean");
 
 		value = model.get("monoBean");
-		assertThat(((Mono<TestBean>) value).block(Duration.ofMillis(5000)).getName()).isEqualTo("Mono Bean");
+		assertThat(((Mono<TestBean>) value).block(TIMEOUT).getName()).isEqualTo("Mono Bean");
 
 		value = model.get("singleBean");
 		assertThat(((Single<TestBean>) value).toBlocking().value().getName()).isEqualTo("Single Bean");
@@ -135,7 +138,7 @@ public void saveModelAttributeToSession() {
 
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(GetMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
-		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000));
+		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT);
 
 		WebSession session = this.exchange.getSession().block(Duration.ZERO);
 		assertThat(session).isNotNull();
@@ -148,7 +151,7 @@ public void saveModelAttributeToSession() {
 
 	@Test
 	public void retrieveModelAttributeFromSession() {
-		WebSession session = this.exchange.getSession().block(Duration.ZERO);
+		WebSession session = this.exchange.getSession().block(TIMEOUT);
 		assertThat(session).isNotNull();
 
 		TestBean testBean = new TestBean("Session Bean");
@@ -159,7 +162,7 @@ public void retrieveModelAttributeFromSession() {
 
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(GetMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
-		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000));
+		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT);
 
 		context.saveModel();
 		assertThat(session.getAttributes().size()).isEqualTo(1);
@@ -174,13 +177,13 @@ public void requiredSessionAttributeMissing() {
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(PostMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000)))
+				this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT))
 			.withMessage("Required attribute 'missing-bean' is missing.");
 	}
 
 	@Test
 	public void clearModelAttributeFromSession() {
-		WebSession session = this.exchange.getSession().block(Duration.ZERO);
+		WebSession session = this.exchange.getSession().block(TIMEOUT);
 		assertThat(session).isNotNull();
 
 		TestBean testBean = new TestBean("Session Bean");
@@ -191,7 +194,7 @@ public void clearModelAttributeFromSession() {
 
 		Method method = ResolvableMethod.on(TestController.class).annotPresent(GetMapping.class).resolveMethod();
 		HandlerMethod handlerMethod = new HandlerMethod(controller, method);
-		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(Duration.ofMillis(5000));
+		this.modelInitializer.initModel(handlerMethod, context, this.exchange).block(TIMEOUT);
 
 		context.getSessionStatus().setComplete();
 		context.saveModel();