refactor: be more conservative w/preview features

Also test with virtual threads in we are using them in production.

4 files changed, 26 insertions, 2 deletions

diff --git a/subprojects/language-web/build.gradle b/subprojects/language-web/build.gradle
index 9c1d93f3..8d277a5b 100644
--- a/subprojects/language-web/build.gradle
+++ b/subprojects/language-web/build.gradle
@@ -40,6 +40,18 @@ for (taskName in ['compileJava', 'processResources']) {
 
 mainClassName = 'tools.refinery.language.web.ServerLauncher'
 
+// Enable JDK 19 preview features for virtual thread support.
+application {
+        applicationDefaultJvmArgs += '--enable-preview'
+}
+tasks.withType(JavaCompile) {
+        options.release = 19
+        options.compilerArgs += '--enable-preview'
+}
+tasks.withType(Test) {
+        jvmArgs += '--enable-preview'
+}
+
 tasks.named('jar') {
         dependsOn project.configurations.webapp
         from(project.configurations.webapp) {
@@ -65,6 +77,8 @@ tasks.register('serveBackend', JavaExec) {
         dependsOn sourceSets.main.runtimeClasspath
         classpath = sourceSets.main.runtimeClasspath
         mainClass = mainClassName
+        // Enable JDK 19 preview features for virtual thread support.
+        jvmArgs += '--enable-preview'
         standardInput = System.in
         def baseResource = project.configurations.webapp.incoming.artifacts.artifactFiles.first()
         environment BASE_RESOURCE: baseResource
diff --git a/subprojects/language-web/src/main/java/tools/refinery/language/web/ServerLauncher.java b/subprojects/language-web/src/main/java/tools/refinery/language/web/ServerLauncher.java
index 5da16850..960eef71 100644
--- a/subprojects/language-web/src/main/java/tools/refinery/language/web/ServerLauncher.java
+++ b/subprojects/language-web/src/main/java/tools/refinery/language/web/ServerLauncher.java
@@ -45,6 +45,7 @@ public class ServerLauncher {
 
         public ServerLauncher(InetSocketAddress bindAddress, String[] allowedOrigins, String webSocketUrl) {
                 server = new Server(bindAddress);
+                enableVirtualThreads(server);
                 if (server.getThreadPool() instanceof VirtualThreads.Configurable virtualThreadsConfigurable) {
                         // Change this to setVirtualThreadsExecutor once
                         // https://github.com/eclipse/jetty.project/commit/83154b4ffe4767ef44981598d6c26e6a5d32e57c gets released.
@@ -149,6 +150,14 @@ public class ServerLauncher {
                 }
         }
 
+        public static void enableVirtualThreads(Server server) {
+                if (server.getThreadPool() instanceof VirtualThreads.Configurable virtualThreadsConfigurable) {
+                        // Change this to setVirtualThreadsExecutor once
+                        // https://github.com/eclipse/jetty.project/commit/83154b4ffe4767ef44981598d6c26e6a5d32e57c gets released.
+                        virtualThreadsConfigurable.setUseVirtualThreads(VirtualThreads.areSupported());
+                }
+        }
+
         private static String getListenAddress() {
                 var listenAddress = System.getenv("LISTEN_ADDRESS");
                 if (listenAddress == null) {
diff --git a/subprojects/language-web/src/test/java/tools/refinery/language/web/ProblemWebSocketServletIntegrationTest.java b/subprojects/language-web/src/test/java/tools/refinery/language/web/ProblemWebSocketServletIntegrationTest.java
index 6dfce780..24fab4e3 100644
--- a/subprojects/language-web/src/test/java/tools/refinery/language/web/ProblemWebSocketServletIntegrationTest.java
+++ b/subprojects/language-web/src/test/java/tools/refinery/language/web/ProblemWebSocketServletIntegrationTest.java
@@ -177,6 +177,7 @@ class ProblemWebSocketServletIntegrationTest {
 
         private void startServer(String allowedOrigins) {
                 server = new Server(new InetSocketAddress(SERVER_PORT));
+                ServerLauncher.enableVirtualThreads(server);
                 var handler = new ServletContextHandler();
                 var holder = new ServletHolder(ProblemWebSocketServlet.class);
                 if (allowedOrigins != null) {
diff --git a/subprojects/language-web/src/test/java/tools/refinery/language/web/tests/AwaitTerminationExecutorServiceProvider.java b/subprojects/language-web/src/test/java/tools/refinery/language/web/tests/AwaitTerminationExecutorServiceProvider.java
index ebf36f13..25343109 100644
--- a/subprojects/language-web/src/test/java/tools/refinery/language/web/tests/AwaitTerminationExecutorServiceProvider.java
+++ b/subprojects/language-web/src/test/java/tools/refinery/language/web/tests/AwaitTerminationExecutorServiceProvider.java
@@ -1,14 +1,14 @@
 package tools.refinery.language.web.tests;
 
 import com.google.inject.Singleton;
-import org.eclipse.xtext.ide.ExecutorServiceProvider;
+import tools.refinery.language.web.xtext.VirtualThreadExecutorServiceProvider;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.ExecutorService;
 
 @Singleton
-public class AwaitTerminationExecutorServiceProvider extends ExecutorServiceProvider {
+public class AwaitTerminationExecutorServiceProvider extends VirtualThreadExecutorServiceProvider {
         private final List<RestartableCachedThreadPool> servicesToShutDown = new ArrayList<>();
 
         @Override