Minor cleanup

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

@@ -84,7 +84,6 @@ public class HikariConfig implements HikariConfigMBean
    private boolean isIsolateInternalQueries;
    private boolean isRegisterMbeans;
    private boolean isAllowPoolSuspension;
-   private boolean isWeakThreadLocals;
    private DataSource dataSource;
    private Properties dataSourceProperties;
    private ThreadFactory threadFactory;
@@ -395,28 +394,6 @@ public class HikariConfig implements HikariConfigMBean
       this.isAllowPoolSuspension = isAllowPoolSuspension;
    }
 
-   /**
-    * Get the pool ThreadLocal behavior, weak or strong references.
-    *
-    * @return true if weak reference ThreadLocals should be used
-    */
-   public boolean isWeakThreadLocals()
-   {
-      return isWeakThreadLocals;
-   }
-
-   /**
-    * Set whether or not the pool should use weak reference ThreadLocals
-    * to avoid possible memory leaks in containers that undeploy/redeploy
-    * pool instances.
-    *
-    * @param weakThreadLocals true if weak reference ThreadLocals should be used
-    */
-   public void setWeakThreadLocals(boolean weakThreadLocals)
-   {
-      this.isWeakThreadLocals = weakThreadLocals;
-   }
-
    /**
     * Get whether or not the construction of the pool should throw an exception
     * if the minimum number of connections cannot be created.

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

@@ -29,8 +29,6 @@ import javax.sql.DataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.codahale.metrics.MetricRegistry;
-import com.codahale.metrics.health.HealthCheckRegistry;
 import com.zaxxer.hikari.pool.HikariPool;
 import com.zaxxer.hikari.proxy.IHikariConnectionProxy;
 import com.zaxxer.hikari.util.DriverDataSource;

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

@@ -59,6 +59,7 @@ import com.zaxxer.hikari.util.ClockSource;
 import com.zaxxer.hikari.util.ConcurrentBag;
 import com.zaxxer.hikari.util.DefaultThreadFactory;
 import com.zaxxer.hikari.util.IBagStateListener;
+import com.zaxxer.hikari.util.PropertyBeanSetter;
 
 /**
  * This is the primary connection pool class that provides the basic
@@ -124,7 +125,7 @@ public class HikariPool implements HikariPoolMBean, IBagStateListener
       this.poolUtils = new PoolUtilities(config);
       this.dataSource = poolUtils.initializeDataSource(config.getDataSourceClassName(), config.getDataSource(), config.getDataSourceProperties(), config.getDriverClassName(), config.getJdbcUrl(), username, password);
 
-      this.connectionBag = new ConcurrentBag<>(this, config.isWeakThreadLocals());
+      this.connectionBag = new ConcurrentBag<>(this);
       this.totalConnections = new AtomicInteger();
       this.connectionTimeout = config.getConnectionTimeout();
       this.validationTimeout = config.getValidationTimeout();
@@ -155,6 +156,9 @@ public class HikariPool implements HikariPoolMBean, IBagStateListener
 
       poolUtils.setLoginTimeout(dataSource, connectionTimeout);
       registerMBeans(config, this);
+
+      PropertyBeanSetter.flushCaches();  // prevent classloader leak
+
       initializeConnections();
    }
 

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

@@ -58,7 +58,7 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
 
    private final AbstractQueuedLongSynchronizer synchronizer;
    private final CopyOnWriteArrayList<T> sharedList;
-   private final boolean weakThreadLocal;
+   private final boolean weakThreadLocals;
 
    private final ThreadLocal<List> threadList;
    private final Sequence sequence;
@@ -71,15 +71,15 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
     *
     * @param listener the IBagStateListener to attach to this bag
     */
-   public ConcurrentBag(IBagStateListener listener, boolean weakThreadLocal)
+   public ConcurrentBag(IBagStateListener listener)
    {
       this.listener = listener;
-      this.weakThreadLocal = weakThreadLocal;
+      this.weakThreadLocals = useWeakThreadLocals();
 
       this.sharedList = new CopyOnWriteArrayList<>();
       this.synchronizer = new Synchronizer();
       this.sequence = Sequence.Factory.create();
-      if (weakThreadLocal) {
+      if (weakThreadLocals) {
          this.threadList = new ThreadLocal<>(); 
       }
       else {
@@ -108,24 +108,14 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
       // Try the thread-local list first, if there are no blocked threads waiting already
       if (!synchronizer.hasQueuedThreads()) {
          List<?> list = threadList.get();
-         if (weakThreadLocal && list == null) {
+         if (weakThreadLocals && list == null) {
             list = new ArrayList<>(16);
             threadList.set(list);
          }
 
          for (int i = list.size() - 1; i >= 0; i--) {
-            final T bagEntry;
-            if (weakThreadLocal) {
-               bagEntry = (T) ((WeakReference) list.remove(i)).get(); 
-               if (bagEntry == null) {
-                  continue;
-               }
-            }
-            else {
-               bagEntry = (T) list.remove(i);
-            }
-
-            if (bagEntry.state().compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
+            final T bagEntry = (T) (weakThreadLocals ? ((WeakReference) list.remove(i)).get() : list.remove(i));
+            if (bagEntry != null & bagEntry.state().compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
                return bagEntry;
             }
          }
@@ -177,7 +167,7 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
       if (bagEntry.state().compareAndSet(STATE_IN_USE, STATE_NOT_IN_USE)) {
          final List threadLocalList = threadList.get();
          if (threadLocalList != null) {
-            threadLocalList.add((weakThreadLocal ? new WeakReference<>(bagEntry) : bagEntry));
+            threadLocalList.add((weakThreadLocals ? new WeakReference<>(bagEntry) : bagEntry));
          }
 
          sequence.increment();
@@ -338,6 +328,23 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
       }
    }
 
+   /**
+    * Determine whether to use WeakReferences based on whether there is a
+    * custom ClassLoader implementation sitting between this class and the
+    * System ClassLoader.
+    *
+    * @return true if we should use WeakReferences in our ThreadLocals, false otherwise
+    */
+   private boolean useWeakThreadLocals()
+   {
+      try {
+         return !(this.getClass().getClassLoader().toString().startsWith("sun.misc") || ClassLoader.getSystemClassLoader() == this.getClass().getClassLoader());
+      }
+      catch (SecurityException se) {
+         return true;
+      }
+   }
+
    /**
     * Our private synchronizer that handles notify/wait type semantics.
     */

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

@@ -118,6 +118,11 @@ public final class PropertyBeanSetter
       return copy;
    }
 
+   public static void flushCaches()
+   {
+      Introspector.flushCaches();
+   }
+
    private static void setProperty(Object target, String propName, Object propValue)
    {
       String capitalized = "set" + propName.substring(0, 1).toUpperCase() + propName.substring(1);

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

@@ -56,7 +56,6 @@ public final class UtilityElf
     * @param args arguments to a constructor
     * @return an instance of the specified class
     */
-   @SuppressWarnings("unchecked")
    public static <T> T createInstance(final String className, final Class<T> clazz, final Object... args)
    {
       if (className == null) {

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

@@ -14,7 +14,6 @@ public class RampUpDown
         HikariConfig config = new HikariConfig();
         config.setMinimumIdle(5);
         config.setMaximumPoolSize(60);
-        config.setWeakThreadLocals(true);
         config.setInitializationFailFast(true);
         config.setConnectionTestQuery("VALUES 1");
         config.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");

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

@@ -50,7 +50,6 @@ public class TestConcurrentBag
       config.setInitializationFailFast(true);
       config.setConnectionTestQuery("VALUES 1");
       config.setDataSourceClassName("com.zaxxer.hikari.mocks.StubDataSource");
-      config.setWeakThreadLocals(true);
 
       ds = new HikariDataSource(config);      
    }
@@ -100,7 +99,7 @@ public class TestConcurrentBag
                }
             };
          }
-      }, false);
+      });
       Assert.assertEquals(0, bag.values(8).size());
 
       HikariPool pool = TestElf.getPool(ds);