Add support for Jakarta Servlet 6.x (#2652)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

metrics-bom/pom.xml

@@ -75,6 +75,11 @@
                 <artifactId>metrics-jakarta-servlet</artifactId>
                 <version>${project.version}</version>
             </dependency>
+            <dependency>
+                <groupId>io.dropwizard.metrics</groupId>
+                <artifactId>metrics-jakarta-servlet6</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                 <groupId>io.dropwizard.metrics</groupId>
                 <artifactId>metrics-jakarta-servlets</artifactId>

metrics-jakarta-servlet6/pom.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.dropwizard.metrics</groupId>
+        <artifactId>metrics-parent</artifactId>
+        <version>4.2.20-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>metrics-jakarta-servlet6</artifactId>
+    <name>Metrics Integration for Jakarta Servlets 6.x</name>
+    <packaging>bundle</packaging>
+    <description>
+        An instrumented filter for servlet 6.x environments.
+    </description>
+
+    <properties>
+        <javaModuleName>io.dropwizard.metrics.servlet</javaModuleName>
+        <servlet6.version>6.0.0</servlet6.version>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>io.dropwizard.metrics</groupId>
+                <artifactId>metrics-bom</artifactId>
+                <version>${project.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.servlet</groupId>
+            <artifactId>jakarta.servlet-api</artifactId>
+            <version>${servlet6.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${mockito.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

metrics-jakarta-servlet6/src/main/java/io/dropwizard/metrics/servlet6/AbstractInstrumentedFilter.java

@@ -0,0 +1,211 @@
+package io.dropwizard.metrics.servlet6;
+
+import com.codahale.metrics.Counter;
+import com.codahale.metrics.Meter;
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.Timer;
+import jakarta.servlet.AsyncEvent;
+import jakarta.servlet.AsyncListener;
+import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.FilterConfig;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+import jakarta.servlet.http.HttpServletResponse;
+import jakarta.servlet.http.HttpServletResponseWrapper;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import static com.codahale.metrics.MetricRegistry.name;
+
+/**
+ * {@link Filter} implementation which captures request information and a breakdown of the response
+ * codes being returned.
+ */
+public abstract class AbstractInstrumentedFilter implements Filter {
+    static final String METRIC_PREFIX = "name-prefix";
+
+    private final String otherMetricName;
+    private final Map<Integer, String> meterNamesByStatusCode;
+    private final String registryAttribute;
+
+    // initialized after call of init method
+    private ConcurrentMap<Integer, Meter> metersByStatusCode;
+    private Meter otherMeter;
+    private Meter timeoutsMeter;
+    private Meter errorsMeter;
+    private Counter activeRequests;
+    private Timer requestTimer;
+
+
+    /**
+     * Creates a new instance of the filter.
+     *
+     * @param registryAttribute      the attribute used to look up the metrics registry in the
+     *                               servlet context
+     * @param meterNamesByStatusCode A map, keyed by status code, of meter names that we are
+     *                               interested in.
+     * @param otherMetricName        The name used for the catch-all meter.
+     */
+    protected AbstractInstrumentedFilter(String registryAttribute,
+                                         Map<Integer, String> meterNamesByStatusCode,
+                                         String otherMetricName) {
+        this.registryAttribute = registryAttribute;
+        this.otherMetricName = otherMetricName;
+        this.meterNamesByStatusCode = meterNamesByStatusCode;
+    }
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+        final MetricRegistry metricsRegistry = getMetricsFactory(filterConfig);
+
+        String metricName = filterConfig.getInitParameter(METRIC_PREFIX);
+        if (metricName == null || metricName.isEmpty()) {
+            metricName = getClass().getName();
+        }
+
+        this.metersByStatusCode = new ConcurrentHashMap<>(meterNamesByStatusCode.size());
+        for (Entry<Integer, String> entry : meterNamesByStatusCode.entrySet()) {
+            metersByStatusCode.put(entry.getKey(),
+                    metricsRegistry.meter(name(metricName, entry.getValue())));
+        }
+        this.otherMeter = metricsRegistry.meter(name(metricName, otherMetricName));
+        this.timeoutsMeter = metricsRegistry.meter(name(metricName, "timeouts"));
+        this.errorsMeter = metricsRegistry.meter(name(metricName, "errors"));
+        this.activeRequests = metricsRegistry.counter(name(metricName, "activeRequests"));
+        this.requestTimer = metricsRegistry.timer(name(metricName, "requests"));
+
+    }
+
+    private MetricRegistry getMetricsFactory(FilterConfig filterConfig) {
+        final MetricRegistry metricsRegistry;
+
+        final Object o = filterConfig.getServletContext().getAttribute(this.registryAttribute);
+        if (o instanceof MetricRegistry) {
+            metricsRegistry = (MetricRegistry) o;
+        } else {
+            metricsRegistry = new MetricRegistry();
+        }
+        return metricsRegistry;
+    }
+
+    @Override
+    public void destroy() {
+
+    }
+
+    @Override
+    public void doFilter(ServletRequest request,
+                         ServletResponse response,
+                         FilterChain chain) throws IOException, ServletException {
+        final StatusExposingServletResponse wrappedResponse =
+                new StatusExposingServletResponse((HttpServletResponse) response);
+        activeRequests.inc();
+        final Timer.Context context = requestTimer.time();
+        boolean error = false;
+        try {
+            chain.doFilter(request, wrappedResponse);
+        } catch (IOException | RuntimeException | ServletException e) {
+            error = true;
+            throw e;
+        } finally {
+            if (!error && request.isAsyncStarted()) {
+                request.getAsyncContext().addListener(new AsyncResultListener(context));
+            } else {
+                context.stop();
+                activeRequests.dec();
+                if (error) {
+                    errorsMeter.mark();
+                } else {
+                    markMeterForStatusCode(wrappedResponse.getStatus());
+                }
+            }
+        }
+    }
+
+    private void markMeterForStatusCode(int status) {
+        final Meter metric = metersByStatusCode.get(status);
+        if (metric != null) {
+            metric.mark();
+        } else {
+            otherMeter.mark();
+        }
+    }
+
+    private static class StatusExposingServletResponse extends HttpServletResponseWrapper {
+        // The Servlet spec says: calling setStatus is optional, if no status is set, the default is 200.
+        private int httpStatus = 200;
+
+        public StatusExposingServletResponse(HttpServletResponse response) {
+            super(response);
+        }
+
+        @Override
+        public void sendError(int sc) throws IOException {
+            httpStatus = sc;
+            super.sendError(sc);
+        }
+
+        @Override
+        public void sendError(int sc, String msg) throws IOException {
+            httpStatus = sc;
+            super.sendError(sc, msg);
+        }
+
+        @Override
+        public void setStatus(int sc) {
+            httpStatus = sc;
+            super.setStatus(sc);
+        }
+
+        @Override
+        public int getStatus() {
+            return httpStatus;
+        }
+    }
+
+    private class AsyncResultListener implements AsyncListener {
+        private final Timer.Context context;
+        private boolean done = false;
+
+        public AsyncResultListener(Timer.Context context) {
+            this.context = context;
+        }
+
+        @Override
+        public void onComplete(AsyncEvent event) throws IOException {
+            if (!done) {
+                HttpServletResponse suppliedResponse = (HttpServletResponse) event.getSuppliedResponse();
+                context.stop();
+                activeRequests.dec();
+                markMeterForStatusCode(suppliedResponse.getStatus());
+            }
+        }
+
+        @Override
+        public void onTimeout(AsyncEvent event) throws IOException {
+            context.stop();
+            activeRequests.dec();
+            timeoutsMeter.mark();
+            done = true;
+        }
+
+        @Override
+        public void onError(AsyncEvent event) throws IOException {
+            context.stop();
+            activeRequests.dec();
+            errorsMeter.mark();
+            done = true;
+        }
+
+        @Override
+        public void onStartAsync(AsyncEvent event) throws IOException {
+
+        }
+    }
+}

metrics-jakarta-servlet6/src/main/java/io/dropwizard/metrics/servlet6/InstrumentedFilter.java

@@ -0,0 +1,48 @@
+package io.dropwizard.metrics.servlet6;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Implementation of the {@link AbstractInstrumentedFilter} which provides a default set of response codes
+ * to capture information about. <p>Use it in your servlet.xml like this:<p>
+ * <pre>{@code
+ * <filter>
+ *     <filter-name>instrumentedFilter</filter-name>
+ *     <filter-class>io.dropwizard.metrics.servlet.InstrumentedFilter</filter-class>
+ * </filter>
+ * <filter-mapping>
+ *     <filter-name>instrumentedFilter</filter-name>
+ *     <url-pattern>/*</url-pattern>
+ * </filter-mapping>
+ * }</pre>
+ */
+public class InstrumentedFilter extends AbstractInstrumentedFilter {
+    public static final String REGISTRY_ATTRIBUTE = InstrumentedFilter.class.getName() + ".registry";
+
+    private static final String NAME_PREFIX = "responseCodes.";
+    private static final int OK = 200;
+    private static final int CREATED = 201;
+    private static final int NO_CONTENT = 204;
+    private static final int BAD_REQUEST = 400;
+    private static final int NOT_FOUND = 404;
+    private static final int SERVER_ERROR = 500;
+
+    /**
+     * Creates a new instance of the filter.
+     */
+    public InstrumentedFilter() {
+        super(REGISTRY_ATTRIBUTE, createMeterNamesByStatusCode(), NAME_PREFIX + "other");
+    }
+
+    private static Map<Integer, String> createMeterNamesByStatusCode() {
+        final Map<Integer, String> meterNamesByStatusCode = new HashMap<>(6);
+        meterNamesByStatusCode.put(OK, NAME_PREFIX + "ok");
+        meterNamesByStatusCode.put(CREATED, NAME_PREFIX + "created");
+        meterNamesByStatusCode.put(NO_CONTENT, NAME_PREFIX + "noContent");
+        meterNamesByStatusCode.put(BAD_REQUEST, NAME_PREFIX + "badRequest");
+        meterNamesByStatusCode.put(NOT_FOUND, NAME_PREFIX + "notFound");
+        meterNamesByStatusCode.put(SERVER_ERROR, NAME_PREFIX + "serverError");
+        return meterNamesByStatusCode;
+    }
+}

metrics-jakarta-servlet6/src/main/java/io/dropwizard/metrics/servlet6/InstrumentedFilterContextListener.java

@@ -0,0 +1,26 @@
+package io.dropwizard.metrics.servlet6;
+
+import com.codahale.metrics.MetricRegistry;
+import jakarta.servlet.ServletContextEvent;
+import jakarta.servlet.ServletContextListener;
+
+/**
+ * A listener implementation which injects a {@link MetricRegistry} instance into the servlet
+ * context. Implement {@link #getMetricRegistry()} to return the {@link MetricRegistry} for your
+ * application.
+ */
+public abstract class InstrumentedFilterContextListener implements ServletContextListener {
+    /**
+     * @return the {@link MetricRegistry} to inject into the servlet context.
+     */
+    protected abstract MetricRegistry getMetricRegistry();
+
+    @Override
+    public void contextInitialized(ServletContextEvent sce) {
+        sce.getServletContext().setAttribute(InstrumentedFilter.REGISTRY_ATTRIBUTE, getMetricRegistry());
+    }
+
+    @Override
+    public void contextDestroyed(ServletContextEvent sce) {
+    }
+}

metrics-jakarta-servlet6/src/test/java/io/dropwizard/metrics/servlet6/InstrumentedFilterContextListenerTest.java

@@ -0,0 +1,32 @@
+package io.dropwizard.metrics.servlet6;
+
+import com.codahale.metrics.MetricRegistry;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletContextEvent;
+import org.junit.Test;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class InstrumentedFilterContextListenerTest {
+    private final MetricRegistry registry = mock(MetricRegistry.class);
+    private final InstrumentedFilterContextListener listener = new InstrumentedFilterContextListener() {
+        @Override
+        protected MetricRegistry getMetricRegistry() {
+            return registry;
+        }
+    };
+
+    @Test
+    public void injectsTheMetricRegistryIntoTheServletContext() {
+        final ServletContext context = mock(ServletContext.class);
+
+        final ServletContextEvent event = mock(ServletContextEvent.class);
+        when(event.getServletContext()).thenReturn(context);
+
+        listener.contextInitialized(event);
+
+        verify(context).setAttribute("io.dropwizard.metrics.servlet6.InstrumentedFilter.registry", registry);
+    }
+}