refactor: Use Jetty 12 APIs

Author: sladkoff

src/main/java/de/sldk/mc/MetricsController.java

@@ -2,17 +2,19 @@
 
 import io.prometheus.client.CollectorRegistry;
 import io.prometheus.client.exporter.common.TextFormat;
-import jakarta.servlet.http.HttpServletRequest;
-import jakarta.servlet.http.HttpServletResponse;
+import org.eclipse.jetty.http.HttpFields;
+import org.eclipse.jetty.http.HttpHeader;
 import org.eclipse.jetty.http.HttpStatus;
+import org.eclipse.jetty.server.Handler;
 import org.eclipse.jetty.server.Request;
-import org.eclipse.jetty.server.handler.AbstractHandler;
+import org.eclipse.jetty.server.Response;
+import org.eclipse.jetty.util.Callback;
 
-import java.io.IOException;
-import java.util.concurrent.ExecutionException;
+import java.io.OutputStreamWriter;
+import java.nio.charset.StandardCharsets;
 import java.util.logging.Level;
 
-public class MetricsController extends AbstractHandler {
+public class MetricsController extends Handler.Abstract {
 
     private final MetricRegistry metricRegistry = MetricRegistry.getInstance();
     private final PrometheusExporter exporter;
@@ -21,28 +23,32 @@ public MetricsController(PrometheusExporter exporter) {
         this.exporter = exporter;
     }
 
-    @Override
-    public void handle(String target, Request request, HttpServletRequest httpServletRequest,
-            HttpServletResponse response) throws IOException {
-
-        if (!target.equals("/metrics")) {
-            response.sendError(HttpServletResponse.SC_NOT_FOUND);
-            return;
-        }
 
+    @Override
+    public boolean handle(Request request, Response response, Callback callback) throws Exception {
         try {
             metricRegistry.collectMetrics().get();
 
             response.setStatus(HttpStatus.OK_200);
-            response.setContentType(TextFormat.CONTENT_TYPE_004);
 
-            TextFormat.write004(response.getWriter(), CollectorRegistry.defaultRegistry.metricFamilySamples());
+            HttpFields.Mutable responseHeaders = response.getHeaders();
+            responseHeaders.put(HttpHeader.CONTENT_TYPE, TextFormat.CONTENT_TYPE_004);
 
-            request.setHandled(true);
-        } catch (InterruptedException | ExecutionException e) {
+            writeMetricsToResponse(request, response);
+        } catch (Exception e) {
             exporter.getLogger().log(Level.WARNING, "Failed to read server statistic: " + e.getMessage());
             exporter.getLogger().log(Level.FINE, "Failed to read server statistic: ", e);
-            response.sendError(HttpStatus.INTERNAL_SERVER_ERROR_500);
+            Response.writeError(request, response, callback, HttpStatus.INTERNAL_SERVER_ERROR_500, "Failed to read server statistics");
+        }
+        callback.succeeded();
+        return true;
+    }
+
+    private void writeMetricsToResponse(Request request, Response response) throws Exception {
+        try (var out = Response.asBufferedOutputStream(request, response);
+             var writer = new OutputStreamWriter(out, StandardCharsets.UTF_8)) {
+            TextFormat.write004(writer, CollectorRegistry.defaultRegistry.metricFamilySamples());
+            writer.flush();
         }
     }
 }

src/main/java/de/sldk/mc/MetricsServer.java

@@ -1,40 +1,46 @@
 package de.sldk.mc;
 
+import org.eclipse.jetty.http.pathmap.PathSpec;
 import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.handler.PathMappingsHandler;
 import org.eclipse.jetty.server.handler.gzip.GzipHandler;
 
 import java.net.InetSocketAddress;
 
 public class MetricsServer {
 
-	private final String host;
-	private final int port;
-	private final PrometheusExporter prometheusExporter;
+    private final String host;
+    private final int port;
+    private final PrometheusExporter prometheusExporter;
 
-	private Server server;
+    private Server server;
 
-	public MetricsServer(String host, int port, PrometheusExporter prometheusExporter) {
-		this.host = host;
-		this.port = port;
-		this.prometheusExporter = prometheusExporter;
-	}
+    public MetricsServer(String host, int port, PrometheusExporter prometheusExporter) {
+        this.host = host;
+        this.port = port;
+        this.prometheusExporter = prometheusExporter;
+    }
 
-	public void start() throws Exception {
-		GzipHandler gzipHandler = new GzipHandler();
-		gzipHandler.setHandler(new MetricsController(prometheusExporter));
+    public void start() throws Exception {
+        GzipHandler gzipHandler = new GzipHandler();
 
-		InetSocketAddress address = new InetSocketAddress(host, port);
-		server = new Server(address);
-		server.setHandler(gzipHandler);
+        var pathMappings = new PathMappingsHandler();
+        pathMappings.addMapping(PathSpec.from("/metrics"), new MetricsController(prometheusExporter));
 
-		server.start();
-	}
+        gzipHandler.setHandler(pathMappings);
 
-	public void stop() throws Exception {
-		if (server == null) {
-			return;
-		}
+        InetSocketAddress address = new InetSocketAddress(host, port);
+        server = new Server(address);
+        server.setHandler(gzipHandler);
 
-		server.stop();
-	}
+        server.start();
+    }
+
+    public void stop() throws Exception {
+        if (server == null) {
+            return;
+        }
+
+        server.stop();
+    }
 }