HandlerMapping is now asynchronous

spring-web-reactive/src/main/java/org/springframework/web/reactive/DispatcherHandler.java

@@ -98,41 +98,33 @@ public class DispatcherHandler implements ReactiveHttpHandler, ApplicationContex
 			logger.debug("Processing " + request.getMethod() + " request for [" + request.getURI() + "]");
 		}
 
-		Object handler = getHandler(request);
-		if (handler == null) {
+		Publisher<Object> handlerPublisher = getHandler(request);
+		if (handlerPublisher == null) {
 			// No exception handling mechanism yet
 			response.setStatusCode(HttpStatus.NOT_FOUND);
 			response.writeHeaders();
 			return Publishers.empty();
 		}
 
-		HandlerAdapter handlerAdapter = getHandlerAdapter(handler);
-		if (handlerAdapter == null) {
-			return Publishers.error(new IllegalStateException("No HandlerAdapter for " + handler));
-		}
-
-		Publisher<HandlerResult> resultPublisher = handlerAdapter.handle(request, response, handler);
+		Publisher<HandlerResult> resultPublisher = Publishers.concatMap(handlerPublisher, handler -> {
+			HandlerAdapter handlerAdapter = getHandlerAdapter(handler);
+			return handlerAdapter.handle(request, response, handler);
+		});
 
 		return Publishers.concatMap(resultPublisher, result -> {
-			for (HandlerResultHandler resultHandler : resultHandlers) {
-				if (resultHandler.supports(result)) {
-					return resultHandler.handleResult(request, response, result);
-				}
-			}
-			return Publishers.error(new IllegalStateException(
-					"No HandlerResultHandler for " + result.getValue()));
+			HandlerResultHandler handler = getResultHandler(result);
+			return handler.handleResult(request, response, result);
 		});
 	}
 
-	protected Object getHandler(ReactiveServerHttpRequest request) {
-		Object handler = null;
+	protected Publisher<Object> getHandler(ReactiveServerHttpRequest request) {
 		for (HandlerMapping handlerMapping : this.handlerMappings) {
-			handler = handlerMapping.getHandler(request);
-			if (handler != null) {
-				break;
+			Publisher<Object> handlerPublisher = handlerMapping.getHandler(request);
+			if (handlerPublisher != null) {
+				return handlerPublisher;
 			}
 		}
-		return handler;
+		return null;
 	}
 
 	protected HandlerAdapter getHandlerAdapter(Object handler) {
@@ -141,7 +133,16 @@ public class DispatcherHandler implements ReactiveHttpHandler, ApplicationContex
 				return handlerAdapter;
 			}
 		}
-		return null;
+		throw new IllegalStateException("No HandlerAdapter: " + handler);
+	}
+
+	protected HandlerResultHandler getResultHandler(HandlerResult handlerResult) {
+		for (HandlerResultHandler resultHandler : resultHandlers) {
+			if (resultHandler.supports(handlerResult)) {
+				return resultHandler;
+			}
+		}
+		throw new IllegalStateException("No HandlerResultHandler: " + handlerResult.getValue());
 	}
 
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/HandlerMapping.java

@@ -16,6 +16,8 @@
 
 package org.springframework.web.reactive;
 
+import org.reactivestreams.Publisher;
+
 import org.springframework.http.server.ReactiveServerHttpRequest;
 
 /**
@@ -23,6 +25,6 @@ import org.springframework.http.server.ReactiveServerHttpRequest;
  */
 public interface HandlerMapping {
 
-	Object getHandler(ReactiveServerHttpRequest request);
+	Publisher<Object> getHandler(ReactiveServerHttpRequest request);
 
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/handler/SimpleUrlHandlerMapping.java

@@ -19,6 +19,9 @@ package org.springframework.web.reactive.handler;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.reactivestreams.Publisher;
+import reactor.Publishers;
+
 import org.springframework.http.server.ReactiveServerHttpRequest;
 import org.springframework.web.reactive.HandlerMapping;
 
@@ -39,8 +42,10 @@ public class SimpleUrlHandlerMapping implements HandlerMapping {
 
 
 	@Override
-	public Object getHandler(ReactiveServerHttpRequest request) {
-		return this.handlerMap.get(request.getURI().getPath());
+	public Publisher<Object> getHandler(ReactiveServerHttpRequest request) {
+		String path = request.getURI().getPath();
+		Object handler = this.handlerMap.get(path);
+		return (handler != null ? Publishers.just(handler) : null);
 	}
 
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/method/annotation/RequestMappingHandlerMapping.java

@@ -27,6 +27,8 @@ import java.util.TreeSet;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.reactivestreams.Publisher;
+import reactor.Publishers;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
@@ -92,15 +94,16 @@ public class RequestMappingHandlerMapping implements HandlerMapping,
 	}
 
 	@Override
-	public Object getHandler(ReactiveServerHttpRequest request) {
+	public Publisher<Object> getHandler(ReactiveServerHttpRequest request) {
 		for (Map.Entry<RequestMappingInfo, HandlerMethod> entry : this.methodMap.entrySet()) {
 			RequestMappingInfo info = entry.getKey();
 			if (info.matchesRequest(request)) {
+				HandlerMethod handlerMethod = entry.getValue();
 				if (logger.isDebugEnabled()) {
 					logger.debug("Mapped " + request.getMethod() + " " +
-							request.getURI().getPath() + " to [" + entry.getValue() + "]");
+							request.getURI().getPath() + " to [" + handlerMethod + "]");
 				}
-				return entry.getValue();
+				return Publishers.just(handlerMethod);
 			}
 		}
 		return null;

spring-web-reactive/src/test/java/org/springframework/web/reactive/method/annotation/RequestMappingHandlerMappingTests.java

@@ -19,10 +19,13 @@ package org.springframework.web.reactive.method.annotation;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
 
 import org.junit.Before;
 import org.junit.Test;
 import org.reactivestreams.Publisher;
+import reactor.rx.Streams;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -34,6 +37,7 @@ import org.springframework.web.context.support.StaticWebApplicationContext;
 import org.springframework.web.method.HandlerMethod;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 
 /**
  * @author Sebastien Deleuze
@@ -56,19 +60,29 @@ public class RequestMappingHandlerMappingTests {
 	@Test
 	public void path() throws Exception {
 		ReactiveServerHttpRequest request = new MockServerHttpRequest(HttpMethod.GET, "boo");
-		HandlerMethod handler = (HandlerMethod) this.mapping.getHandler(request);
-		assertEquals(TestController.class.getMethod("boo"), handler.getMethod());
+		Publisher<?> handlerPublisher = this.mapping.getHandler(request);
+		HandlerMethod handlerMethod = toHandlerMethod(handlerPublisher);
+		assertEquals(TestController.class.getMethod("boo"), handlerMethod.getMethod());
 	}
 
 	@Test
 	public void method() throws Exception {
 		ReactiveServerHttpRequest request = new MockServerHttpRequest(HttpMethod.POST, "foo");
-		HandlerMethod handler = (HandlerMethod) this.mapping.getHandler(request);
-		assertEquals(TestController.class.getMethod("postFoo"), handler.getMethod());
+		Publisher<?> handlerPublisher = this.mapping.getHandler(request);
+		HandlerMethod handlerMethod = toHandlerMethod(handlerPublisher);
+		assertEquals(TestController.class.getMethod("postFoo"), handlerMethod.getMethod());
 
 		request = new MockServerHttpRequest(HttpMethod.GET, "foo");
-		handler = (HandlerMethod) this.mapping.getHandler(request);
-		assertEquals(TestController.class.getMethod("getFoo"), handler.getMethod());
+		handlerPublisher = this.mapping.getHandler(request);
+		handlerMethod = toHandlerMethod(handlerPublisher);
+		assertEquals(TestController.class.getMethod("getFoo"), handlerMethod.getMethod());
+	}
+
+	private HandlerMethod toHandlerMethod(Publisher<?> handlerPublisher) throws InterruptedException {
+		assertNotNull(handlerPublisher);
+		List<?> handlerList = Streams.wrap(handlerPublisher).toList().await(5, TimeUnit.SECONDS);
+		assertEquals(1, handlerList.size());
+		return (HandlerMethod) handlerList.get(0);
 	}