Merge pull request #249 from biconou/biconou_develop_PR_metrics

Performance metrics

documentation/developer/Performance-Metrics.md

@@ -0,0 +1,18 @@
+
+The Libresonic framework contains a convenient class (called MetricsManager) to add inner metrics that constructs in real time some performance indicators.
+
+The use of MetricsManager is illustrated in the org.libresonic.player.filter.MetricsFilter class. 
+
+The MetricsFilter adds a metric based on the time spent by each /main.view HTTP request. This is interesting as the main.view request is invoqued when something is displayed in the main Libresonic web frame.
+
+By default, the MetricsManager is deactivated; it does nothing. 
+It can be activated only by adding the following line inside the livresonic.properties configuration file :
+
+```
+Metrics=
+```
+
+Once the MetricsManager as been activated this way, each metric can be inspected using a jmx console like VisualVM.
+Each metric is registered as a MBean as shown below.
+
+![](metrics-visualvm-screenshot.png)

libresonic-main/pom.xml

@@ -38,7 +38,6 @@
             <groupId>io.dropwizard.metrics</groupId>
             <artifactId>metrics-core</artifactId>
             <version>${metrics.version}</version>
-            <scope>test</scope>
         </dependency>
         <!-- END Metrics -->
 

libresonic-main/src/main/java/org/libresonic/player/boot/Application.java

@@ -153,6 +153,20 @@ public class Application extends SpringBootServletInitializer implements Embedde
         return registration;
     }
 
+    @Bean
+    public Filter metricsFilter() {
+        return new MetricsFilter();
+    }
+
+    @Bean
+    public FilterRegistrationBean metricsFilterRegistration() {
+        FilterRegistrationBean registration = new FilterRegistrationBean();
+        registration.setFilter(metricsFilter());
+        registration.setOrder(7);
+        return registration;
+    }
+
+
     @Bean
     public Filter noCacheFilter() {
         return new ResponseHeaderFilter();

libresonic-main/src/main/java/org/libresonic/player/filter/MetricsFilter.java

@@ -0,0 +1,37 @@
+package org.libresonic.player.filter;
+
+import org.libresonic.player.monitor.MetricsManager;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import javax.servlet.*;
+import javax.servlet.http.HttpServletRequest;
+
+import java.io.IOException;
+
+/**
+ * Created by remi on 12/01/17.
+ */
+public class MetricsFilter implements Filter {
+
+    @Autowired
+    private MetricsManager metricsManager;
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
+        HttpServletRequest httpServletRequest = (HttpServletRequest)request;
+
+        String timerName = httpServletRequest.getRequestURI();
+        // Add a metric that measures the time spent for each http request for the /main.view url.
+        try (MetricsManager.Timer t = metricsManager.condition(timerName.contains("main.view")).timer(this,timerName)) {
+            chain.doFilter(request, response);
+        }
+    }
+
+    @Override
+    public void destroy() {
+    }
+}

libresonic-main/src/main/java/org/libresonic/player/monitor/MetricsManager.java

@@ -0,0 +1,163 @@
+package org.libresonic.player.monitor;
+
+import com.codahale.metrics.JmxReporter;
+import com.codahale.metrics.MetricRegistry;
+import org.libresonic.player.service.ApacheCommonsConfigurationService;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Created by remi on 17/01/17.
+ */
+public class MetricsManager {
+
+    private ApacheCommonsConfigurationService configurationService;
+
+    // Main metrics registry
+    private static final MetricRegistry metrics = new MetricRegistry();
+
+    private static Boolean metricsActivatedByConfiguration = null;
+    private static Object _lock = new Object();
+
+    // Potential metrics reporters
+    private static JmxReporter reporter;
+
+    private void configureMetricsActivation() {
+        if (configurationService.containsKey("Metrics")) {
+            metricsActivatedByConfiguration = Boolean.TRUE;
+
+            // Start a Metrics JMX reporter
+            reporter = JmxReporter.forRegistry(metrics)
+                    .convertRatesTo(TimeUnit.SECONDS.SECONDS)
+                    .convertDurationsTo(TimeUnit.MILLISECONDS)
+                    .build();
+            reporter.start();
+        } else {
+            metricsActivatedByConfiguration = Boolean.FALSE;
+        }
+    }
+
+    private boolean metricsActivatedByConfiguration() {
+        if (metricsActivatedByConfiguration == null) {
+            synchronized (_lock) {
+                if (metricsActivatedByConfiguration == null) {
+                    configureMetricsActivation();
+                }
+            }
+        }
+        return metricsActivatedByConfiguration.booleanValue();
+    }
+
+    /**
+     * Creates a {@link Timer} whose name is based on a class name and a
+     * qualified name.
+     * @param clazz
+     * @param name
+     * @return
+     */
+    public Timer timer(Class clazz, String name) {
+        if (metricsActivatedByConfiguration()) {
+            return new TimerBuilder().timer(clazz, name);
+        } else {
+            return nullTimerSingleton;
+        }
+    }
+
+    /**
+     * Creates a {@link Timer} whose name is based on an object's class name and a
+     * qualified name.
+     * @param ref
+     * @param name
+     * @return
+     */
+    public Timer timer(Object ref, String name) {
+        return timer(ref.getClass(),name);
+    }
+
+    /**
+     * Initiate a {@link TimerBuilder} using a condition.
+     * If the condition is false, a void {@link Timer} will finally be built thus
+     * no timer will be registered in the Metrics registry.
+     *
+     * @param ifTrue
+     * @return
+     */
+    public TimerBuilder condition(boolean ifTrue) {
+        if (metricsActivatedByConfiguration()) {
+            if (ifTrue == false) {
+                return conditionFalseTimerBuilderSingleton;
+            }
+            return new TimerBuilder();
+        } else {
+            return nullTimerBuilderSingleton;
+        }
+    }
+
+    public void setConfigurationService(ApacheCommonsConfigurationService configurationService) {
+        this.configurationService = configurationService;
+    }
+
+    /**
+     * A class that builds a {@link Timer}
+     */
+    public static class TimerBuilder {
+
+        public Timer timer(Class clazz, String name) {
+            com.codahale.metrics.Timer t = metrics.timer(MetricRegistry.name(clazz,name));
+            com.codahale.metrics.Timer.Context tContext =  t.time();
+            return new Timer(tContext);
+        }
+
+        public Timer timer(Object ref, String name) {
+            return timer(ref.getClass(),name);
+        }
+
+    }
+
+    /**
+     * A class that holds a Metrics timer context implementing {@link AutoCloseable}
+     * thus it can be used in a try-with-resources statement.
+     */
+    public static class Timer implements AutoCloseable {
+
+        private com.codahale.metrics.Timer.Context timerContext;
+
+        protected Timer(com.codahale.metrics.Timer.Context timerContext) {
+            this.timerContext = timerContext;
+        }
+
+        @Override
+        public void close() {
+            timerContext.stop();
+        }
+
+    }
+
+
+    // -----------------------------------------------------------------
+    // Convenient singletons to avoid creating useless objects instances
+    // -----------------------------------------------------------------
+    private static final NullTimer nullTimerSingleton = new NullTimer(null);
+    private static final NullTimerBuilder conditionFalseTimerBuilderSingleton = new NullTimerBuilder();
+    private static final NullTimerBuilder nullTimerBuilderSingleton = new NullTimerBuilder();
+
+    private static class NullTimer extends Timer {
+
+        protected NullTimer(com.codahale.metrics.Timer.Context timerContext) {
+            super(timerContext);
+        }
+
+        @Override
+        public void close()  {
+            // Does nothing
+        }
+    }
+
+    private static class NullTimerBuilder extends TimerBuilder {
+        @Override
+        public Timer timer(Class clazz, String name) {
+            return nullTimerSingleton;
+        }
+    }
+
+}

libresonic-main/src/main/resources/applicationContext-service.xml

@@ -92,6 +92,10 @@
 
     <bean id="configurationService" class="org.libresonic.player.service.ApacheCommonsConfigurationService" />
 
+    <bean id="metricsManager" class="org.libresonic.player.monitor.MetricsManager">
+        <property name="configurationService" ref="configurationService" />
+    </bean>
+
     <bean id="settingsService" class="org.libresonic.player.service.SettingsService" init-method="init">
         <property name="internetRadioDao" ref="internetRadioDao"/>
         <property name="musicFolderDao" ref="musicFolderDao"/>