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; } } }