Refactor ServerLauncher

1 files changed, 90 insertions, 44 deletions

diff --git a/language-web/src/main/java/org/eclipse/viatra/solver/language/web/ServerLauncher.java b/language-web/src/main/java/org/eclipse/viatra/solver/language/web/ServerLauncher.java
index 63088511..d92c7735 100644
--- a/language-web/src/main/java/org/eclipse/viatra/solver/language/web/ServerLauncher.java
+++ b/language-web/src/main/java/org/eclipse/viatra/solver/language/web/ServerLauncher.java
@@ -8,26 +8,62 @@ import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.util.Set;
+
+import javax.servlet.SessionTrackingMode;
 
 import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.session.SessionHandler;
+import org.eclipse.jetty.servlet.DefaultServlet;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
 import org.eclipse.jetty.util.log.Slf4jLog;
 import org.eclipse.jetty.util.resource.Resource;
-import org.eclipse.jetty.webapp.WebAppContext;
 
 public class ServerLauncher {
+        public static final String DEFAULT_LISTEN_ADDRESS = "localhost";
+
+        public static final int DEFAULT_LISTEN_PORT = 1312;
+
+        // Use this cookie name for load balancing.
+        public static final String SESSION_COOKIE_NAME = "JSESSIONID";
+
         private static final Slf4jLog LOG = new Slf4jLog(ServerLauncher.class.getName());
 
         private final Server server;
 
         public ServerLauncher(InetSocketAddress bindAddress, Resource baseResource) {
                 server = new Server(bindAddress);
-                var ctx = new WebAppContext();
-                ctx.setBaseResource(baseResource);
-                ctx.setWelcomeFiles(new String[] { "index.html" });
-                ctx.setContextPath("/");
-                ctx.addServlet(ProblemServlet.class, "/xtext-service/*");
-                ctx.setInitParameter("org.eclipse.jetty.servlet.Default.useFileMappedBuffer", "false");
-                server.setHandler(ctx);
+                var handler = new ServletContextHandler();
+                addSessionHandler(handler);
+                addProblemServlet(handler);
+                if (baseResource != null) {
+                        handler.setBaseResource(baseResource);
+                        handler.setWelcomeFiles(new String[] { "index.html" });
+                        addDefaultServlet(handler);
+                }
+                server.setHandler(handler);
+        }
+
+        private void addSessionHandler(ServletContextHandler handler) {
+                var sessionHandler = new SessionHandler();
+                sessionHandler.setSessionTrackingModes(Set.of(SessionTrackingMode.COOKIE));
+                sessionHandler.setSessionCookie(SESSION_COOKIE_NAME);
+                handler.setSessionHandler(sessionHandler);
+        }
+
+        private void addProblemServlet(ServletContextHandler handler) {
+                handler.addServlet(ProblemServlet.class, "/xtext-service/*");
+        }
+
+        private void addDefaultServlet(ServletContextHandler handler) {
+                var defaultServletHolder = new ServletHolder(DefaultServlet.class);
+                var isWindows = System.getProperty("os.name").toLowerCase().contains("win");
+                // Avoid file locking on Windows: https://stackoverflow.com/a/4985717
+                // See also the related Jetty ticket:
+                // https://github.com/eclipse/jetty.project/issues/2925
+                defaultServletHolder.setInitParameter("useFileMappedBuffer", isWindows ? "false" : "true");
+                handler.addServlet(defaultServletHolder, "/");
         }
 
         public void start() throws Exception {
@@ -38,55 +74,65 @@ public class ServerLauncher {
                 if (key != -1) {
                         server.stop();
                 } else {
-                        LOG.warn(
-                                        "Console input is not available. In order to stop the server, you need to cancel process manually.");
+                        LOG.warn("Console input is not available. "
+                                        + "In order to stop the server, you need to cancel process manually.");
                 }
         }
 
-        private static InetSocketAddress getBindAddress(String listenAddress, int port) {
-                if (listenAddress == null) {
-                        return new InetSocketAddress(port);
-                }
-                return new InetSocketAddress(listenAddress, port);
-        }
-
-        private static Resource getBaseResource(String baseResourceOverride) throws IOException, URISyntaxException {
-                if (baseResourceOverride != null) {
-                        return Resource.newResource(baseResourceOverride);
-                }
-                var indexUrlInJar = ServerLauncher.class.getResource("/webapp/index.html");
-                if (indexUrlInJar == null) {
-                        var workingPath = new String[] { System.getProperty("user.dir"), "build", "webpack", "development", };
-                        return Resource.newResource(new File(String.join(File.separator, workingPath)));
+        public static void main(String[] args) {
+                try {
+                        var bindAddress = getBindAddress();
+                        var baseResource = getBaseResource();
+                        var serverLauncher = new ServerLauncher(bindAddress, baseResource);
+                        serverLauncher.start();
+                } catch (Exception exception) {
+                        LOG.warn(exception);
+                        System.exit(1);
                 }
-                var webRootUri = URI.create(indexUrlInJar.toURI().toASCIIString().replaceFirst("/index.html$", "/"));
-                return Resource.newResource(webRootUri);
         }
 
-        public static void main(String[] args) {
+        private static String getListenAddress() {
                 var listenAddress = System.getenv("LISTEN_ADDRESS");
                 if (listenAddress == null) {
-                        listenAddress = "localhost";
+                        return DEFAULT_LISTEN_ADDRESS;
                 }
-                var port = 1312;
+                return listenAddress;
+        }
+
+        private static int getListenPort() {
                 var portStr = System.getenv("LISTEN_PORT");
                 if (portStr != null) {
-                        try {
-                                port = Integer.parseInt(portStr);
-                        } catch (NumberFormatException e) {
-                                LOG.warn(e);
-                                System.exit(1);
-                        }
+                        return Integer.parseInt(portStr);
                 }
+                return DEFAULT_LISTEN_PORT;
+        }
+
+        private static InetSocketAddress getBindAddress() {
+                var listenAddress = getListenAddress();
+                var listenPort = getListenPort();
+                return new InetSocketAddress(listenAddress, listenPort);
+        }
+
+        private static Resource getBaseResource() throws IOException, URISyntaxException {
                 var baseResourceOverride = System.getenv("BASE_RESOURCE");
-                try {
-                        var bindAddress = getBindAddress(listenAddress, port);
-                        var baseResource = getBaseResource(baseResourceOverride);
-                        var serverLauncher = new ServerLauncher(bindAddress, baseResource);
-                        serverLauncher.start();
-                } catch (Exception exception) {
-                        LOG.warn(exception);
-                        System.exit(1);
+                if (baseResourceOverride != null) {
+                        // If a user override is provided, use it.
+                        return Resource.newResource(baseResourceOverride);
+                }
+                var indexUrlInJar = ServerLauncher.class.getResource("/webapp/index.html");
+                if (indexUrlInJar != null) {
+                        // If the app is packaged in the jar, serve it.
+                        var webRootUri = URI.create(indexUrlInJar.toURI().toASCIIString().replaceFirst("/index.html$", "/"));
+                        return Resource.newResource(webRootUri);
+                }
+                // Look for unpacked production artifacts (convenience for running from IDE).
+                var unpackedResourcePathComponents = new String[] { System.getProperty("user.dir"), "build", "webpack",
+                                "production" };
+                var unpackedResourceDir = new File(String.join(File.separator, unpackedResourcePathComponents));
+                if (unpackedResourceDir.isDirectory()) {
+                        return Resource.newResource(unpackedResourceDir);
                 }
+                // Fall back to just serving a 404.
+                return null;
         }
 }