Remove runtime dependencies on Codahale and generally make things a bit cleaner.

src/main/java/com/zaxxer/hikari/HikariConfig.java

@@ -40,10 +40,9 @@ import org.slf4j.LoggerFactory;
 
 import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.health.HealthCheckRegistry;
+import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
 import com.zaxxer.hikari.pool.PoolElf;
 import com.zaxxer.hikari.util.PropertyElf;
-import com.zaxxer.hikari.metrics.CodahaleMetricsTrackerFactory;
-import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
 
 public class HikariConfig implements HikariConfigMXBean
 {
@@ -91,6 +90,7 @@ public class HikariConfig implements HikariConfigMXBean
    private ThreadFactory threadFactory;
    private ScheduledThreadPoolExecutor scheduledExecutor;
    private MetricsTrackerFactory metricsTrackerFactory;
+   private Object metricRegistry;
    private Object healthCheckRegistry;
    private Properties healthCheckProperties;
 
@@ -451,6 +451,10 @@ public class HikariConfig implements HikariConfigMXBean
 
    public void setMetricsTrackerFactory(MetricsTrackerFactory metricsTrackerFactory)
    {
+      if (metricRegistry != null) {
+         throw new IllegalStateException("setMetricsTrackerFactory() cannot used in combination with setMetricRegistry()");
+      }
+
       this.metricsTrackerFactory = metricsTrackerFactory;
    }
 
@@ -461,12 +465,7 @@ public class HikariConfig implements HikariConfigMXBean
     */
    public Object getMetricRegistry()
    {
-      if (metricsTrackerFactory instanceof CodahaleMetricsTrackerFactory) {
-         return ((CodahaleMetricsTrackerFactory) metricsTrackerFactory).getRegistry();
-      }
-      else {
-         return null;
-      }
+      return metricRegistry;
    }
 
    /**
@@ -476,7 +475,10 @@ public class HikariConfig implements HikariConfigMXBean
     */
    public void setMetricRegistry(Object metricRegistry)
    {
-      MetricsTrackerFactory metricsTrackerFactory;
+      if (metricsTrackerFactory != null) {
+         throw new IllegalStateException("setMetricRegistry() cannot used in combination with setMetricsTrackerFactory()");
+      }
+
       if (metricRegistry != null) {
          if (metricRegistry instanceof String) {
             try {
@@ -491,13 +493,9 @@ public class HikariConfig implements HikariConfigMXBean
          if (!(metricRegistry instanceof MetricRegistry)) {
             throw new IllegalArgumentException("Class must be an instance of com.codahale.metrics.MetricRegistry");
          }
-         metricsTrackerFactory = new CodahaleMetricsTrackerFactory((MetricRegistry) metricRegistry);
       }
-      else {
-         metricsTrackerFactory = null;
-      }
-      // use setter to allow HikariDataSource to alter the behavior of both setters in a single override
-      setMetricsTrackerFactory(metricsTrackerFactory);
+
+      this.metricRegistry = metricRegistry;
    }
 
    /**

src/main/java/com/zaxxer/hikari/HikariDataSource.java

@@ -191,6 +191,23 @@ public class HikariDataSource extends HikariConfig implements DataSource, Closea
       return false;
    }
 
+   /** {@inheritDoc} */
+   @Override
+   public void setMetricRegistry(Object metricRegistry)
+   {
+      boolean isAlreadySet = getMetricRegistry() != null;
+      super.setMetricRegistry(metricRegistry);
+
+      if (pool != null) {
+         if (isAlreadySet) {
+            throw new IllegalStateException("MetricRegistry can only be set one time");
+         }
+         else {
+            pool.setMetricRegistry(super.getMetricRegistry());
+         }
+      }
+   }
+
    /** {@inheritDoc} */
    @Override
    public void setMetricsTrackerFactory(MetricsTrackerFactory metricsTrackerFactory)

src/main/java/com/zaxxer/hikari/pool/HikariPool.java

@@ -44,12 +44,11 @@ import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.health.HealthCheckRegistry;
 import com.zaxxer.hikari.HikariConfig;
 import com.zaxxer.hikari.HikariPoolMXBean;
-import com.zaxxer.hikari.metrics.CodaHaleMetricsTracker;
 import com.zaxxer.hikari.metrics.CodahaleHealthChecker;
 import com.zaxxer.hikari.metrics.CodahaleMetricsTrackerFactory;
 import com.zaxxer.hikari.metrics.MetricsTracker;
-import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
 import com.zaxxer.hikari.metrics.MetricsTracker.MetricsContext;
+import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
 import com.zaxxer.hikari.metrics.PoolStats;
 import com.zaxxer.hikari.proxy.ConnectionProxy;
 import com.zaxxer.hikari.proxy.IHikariConnectionProxy;
@@ -135,7 +134,13 @@ public class HikariPool implements HikariPoolMXBean, IBagStateListener
 
       this.leakTask = new LeakTask(config.getLeakDetectionThreshold(), houseKeepingExecutorService);
       
-      setMetricRegistry(config.getMetricRegistry());
+      if (config.getMetricsTrackerFactory() != null) {
+         setMetricsTrackerFactory(config.getMetricsTrackerFactory());
+      }
+      else {
+         setMetricRegistry(config.getMetricRegistry());
+      }
+
       setHealthCheckRegistry(config.getHealthCheckRegistry());
 
       poolElf.registerMBeans(this);
@@ -287,7 +292,7 @@ public class HikariPool implements HikariPoolMXBean, IBagStateListener
 
    public void setMetricRegistry(Object metricRegistry)
    {
-      if (metricRegistry != null) {
+      if (isRecordMetrics) {
          setMetricsTrackerFactory(new CodahaleMetricsTrackerFactory((MetricRegistry) metricRegistry));
       }
       else {

src/test/java/com/zaxxer/hikari/TestMetrics.java

@@ -266,11 +266,11 @@ public class TestMetrics
       ds.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
 
       MetricRegistry metricRegistry = new MetricRegistry();
-      MetricsTrackerFactory metricsTrackerFactory = new CodahaleMetricsTrackerFactory(metricRegistry);
 
       // before the pool is started, we can set it any number of times using either setter
       ds.setMetricRegistry(metricRegistry);
-      ds.setMetricsTrackerFactory(metricsTrackerFactory);
+      ds.setMetricRegistry(metricRegistry);
+      ds.setMetricRegistry(metricRegistry);
 
       try {
          Connection connection = ds.getConnection();
@@ -282,14 +282,37 @@ public class TestMetrics
       }
       catch (IllegalStateException ise) {
          // pass
-         try {
-            // after the pool is started, we cannot set it any more
-            ds.setMetricsTrackerFactory(metricsTrackerFactory);
-            Assert.fail("Should not have been allowed to set metricsTrackerFactory after pool started");
-         }
-         catch (IllegalStateException ise2) {
-            // pass
-         }
+      }
+      finally {
+         ds.close();
+      }
+   }
+
+   @Test
+   public void testSetters5() throws Exception
+   {
+      HikariDataSource ds = new HikariDataSource();
+      ds.setMaximumPoolSize(1);
+      ds.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
+
+      MetricRegistry metricRegistry = new MetricRegistry();
+      MetricsTrackerFactory metricsTrackerFactory = new CodahaleMetricsTrackerFactory(metricRegistry);
+
+      // before the pool is started, we can set it any number of times using either setter
+      ds.setMetricsTrackerFactory(metricsTrackerFactory);
+      ds.setMetricsTrackerFactory(metricsTrackerFactory);
+      ds.setMetricsTrackerFactory(metricsTrackerFactory);
+
+      try {
+         Connection connection = ds.getConnection();
+         connection.close();
+
+         // after the pool is started, we cannot set it any more
+         ds.setMetricsTrackerFactory(metricsTrackerFactory);
+         Assert.fail("Should not have been allowed to set registry factory after pool started");
+      }
+      catch (IllegalStateException ise) {
+         // pass
       }
       finally {
          ds.close();