Clean up async execution logic in ProxyMVC

Author: olegz

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ProxyHttpServletRequest.java

@@ -634,6 +634,7 @@ public AsyncContext startAsync() {
 	@Override
 	public AsyncContext startAsync(ServletRequest request, @Nullable ServletResponse response) {
 		Assert.state(this.asyncSupported, "Async not supported");
+		this.dispatcherType = DispatcherType.ASYNC;
 		this.asyncStarted = true;
 		this.asyncContext = this.asyncContext == null ? new ProxyAsyncContext(request, response) : this.asyncContext;
 		return this.asyncContext;

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ProxyMvc.java

@@ -25,6 +25,7 @@
 import java.util.List;
 import java.util.concurrent.CountDownLatch;
 
+import jakarta.servlet.AsyncContext;
 import jakarta.servlet.Filter;
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.FilterConfig;
@@ -49,8 +50,6 @@
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
-import org.springframework.web.context.request.async.WebAsyncManager;
-import org.springframework.web.context.request.async.WebAsyncUtils;
 import org.springframework.web.servlet.DispatcherServlet;
 
 /**
@@ -143,15 +142,25 @@ public void service(HttpServletRequest request, HttpServletResponse response) th
 
 
 	public void service(HttpServletRequest request, HttpServletResponse response, CountDownLatch latch) throws Exception {
+		((ProxyHttpServletRequest) request).setAsyncStarted(true);
+
 		ProxyFilterChain filterChain = new ProxyFilterChain(this.dispatcher);
 		filterChain.doFilter(request, response);
 
-		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
-		if (asyncManager.isConcurrentHandlingStarted()) {
-			this.dispatcher.service(request, response);
+		AsyncContext asyncContext = request.getAsyncContext();
+		if (asyncContext != null) {
+			filterChain = new ProxyFilterChain(this.dispatcher);
+			((ProxyAsyncContext) asyncContext).addDispatchHandler(() -> {
+				try {
+					new ProxyFilterChain(this.dispatcher).doFilter(request, response);
+					asyncContext.complete();
+				}
+				catch (Exception e) {
+					throw new IllegalStateException(e);
+				}
+			});
 		}
 
-
 		if (latch != null) {
 			latch.countDown();
 		}