Allowing anonymous subclasses of MetricRegistry. Also changing checks for metrics libraries from classname contains to assignableFrom the metrics class (#1089)

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

@@ -42,6 +42,7 @@ import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ThreadLocalRandom;
 
 import static com.zaxxer.hikari.util.UtilityElf.getNullIfEmpty;
+import static com.zaxxer.hikari.util.UtilityElf.safeIsAssignableFrom;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
@@ -758,8 +759,8 @@ public class HikariConfig implements HikariConfigMXBean
       if (metricRegistry != null) {
          metricRegistry = getObjectOrPerformJndiLookup(metricRegistry);
 
-         if (!(metricRegistry.getClass().getName().contains("MetricRegistry"))
-             && !(metricRegistry.getClass().getName().contains("MeterRegistry"))) {
+         if (!safeIsAssignableFrom(metricRegistry, "com.codahale.metrics.MetricRegistry")
+             && !(safeIsAssignableFrom(metricRegistry, "io.micrometer.core.instrument.MeterRegistry"))) {
             throw new IllegalArgumentException("Class must be instance of com.codahale.metrics.MetricRegistry or io.micrometer.core.instrument.MeterRegistry");
          }
       }

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

@@ -57,6 +57,7 @@ import static com.zaxxer.hikari.util.ConcurrentBag.IConcurrentBagEntry.STATE_IN_
 import static com.zaxxer.hikari.util.ConcurrentBag.IConcurrentBagEntry.STATE_NOT_IN_USE;
 import static com.zaxxer.hikari.util.UtilityElf.createThreadPoolExecutor;
 import static com.zaxxer.hikari.util.UtilityElf.quietlySleep;
+import static com.zaxxer.hikari.util.UtilityElf.safeIsAssignableFrom;
 import static java.util.Collections.unmodifiableCollection;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
@@ -272,10 +273,10 @@ public final class HikariPool extends PoolBase implements HikariPoolMXBean, IBag
     */
    public void setMetricRegistry(Object metricRegistry)
    {
-      if (metricRegistry != null && metricRegistry.getClass().getName().contains("MetricRegistry")) {
+      if (metricRegistry != null && safeIsAssignableFrom(metricRegistry, "com.codahale.metrics.MetricRegistry")) {
          setMetricsTrackerFactory(new CodahaleMetricsTrackerFactory((MetricRegistry) metricRegistry));
       }
-      else if (metricRegistry != null && metricRegistry.getClass().getName().contains("MeterRegistry")) {
+      else if (metricRegistry != null && safeIsAssignableFrom(metricRegistry, "io.micrometer.core.instrument.MeterRegistry")) {
          setMetricsTrackerFactory(new MicrometerMetricsTrackerFactory((MeterRegistry) metricRegistry));
       }
       else {

src/main/java/com/zaxxer/hikari/util/UtilityElf.java

@@ -65,6 +65,21 @@ public final class UtilityElf
       }
    }
 
+   /**
+    * Checks whether an object is an instance of given type without throwing exception when the class is not loaded.
+    * @param obj the object to check
+    * @param className String class
+    * @return true if object is assignable from the type, false otherwise or when the class cannot be loaded
+    */
+   public static boolean safeIsAssignableFrom(Object obj, String className) {
+      try {
+         Class<?> clazz = Class.forName(className);
+         return clazz.isAssignableFrom(obj.getClass());
+      } catch (ClassNotFoundException ignored) {
+         return false;
+      }
+   }
+
    /**
     * Create and instance of the specified class using the constructor matching the specified
     * arguments.

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

@@ -298,4 +298,35 @@ public class TestMetrics
          }
       }
    }
+
+   @Test(expected = IllegalArgumentException.class)
+   public void testFakeMetricRegistryThrowsIllegalArgumentException()
+   {
+      try (HikariDataSource ds = newHikariDataSource()) {
+         ds.setMaximumPoolSize(1);
+         ds.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
+
+         FakeMetricRegistry metricRegistry = new FakeMetricRegistry();
+
+         ds.setMetricRegistry(metricRegistry);
+      }
+   }
+
+   private static class FakeMetricRegistry {}
+
+   @Test
+   public void testMetricRegistrySubclassIsAllowed()
+   {
+      try (HikariDataSource ds = newHikariDataSource()) {
+         ds.setMaximumPoolSize(1);
+         ds.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
+
+         ds.setMetricRegistry(new MetricRegistry() {
+            @Override
+            public Timer timer(String name) {
+               return super.timer(name);
+            }
+         });
+      }
+   }
 }