More refactors to isolate metrics from internal pool classes

src/main/java/com/zaxxer/hikari/metrics/MetricsTracker.java

@@ -23,18 +23,15 @@ package com.zaxxer.hikari.metrics;
  */
 public class MetricsTracker implements AutoCloseable
 {
-   public static final MetricsTimerContext NO_CONTEXT = new MetricsTimerContext();
-
    public MetricsTracker()
    {
    }
 
-   public MetricsTimerContext recordConnectionRequest()
+   public void recordConnectionAcquireNanos(final long elapsedAcquireNano)
    {
-      return NO_CONTEXT;
    }
 
-   public void recordConnectionUsage(final long elapsedLastBorrowed)
+   public void recordConnectionUsageMillis(final long elapsedLastBorrowed)
    {
    }
 
@@ -42,19 +39,4 @@ public class MetricsTracker implements AutoCloseable
    public void close()
    {
    }
-
-   /**
-    * A base instance of a MetricsContext.  Classes extending this class should exhibit the
-    * behavior of "starting" a timer upon construction, and "stopping" the timer when the
-    * {@link MetricsTimerContext#stop()} method is called.
-    *
-    * @author Brett Wooldridge
-    */
-   public static class MetricsTimerContext
-   {
-      public void stop()
-      {
-         // do nothing
-      }
-   }
 }

src/main/java/com/zaxxer/hikari/metrics/dropwizard/CodaHaleMetricsTracker.java

@@ -16,6 +16,8 @@
 
 package com.zaxxer.hikari.metrics.dropwizard;
 
+import java.util.concurrent.TimeUnit;
+
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.Histogram;
 import com.codahale.metrics.MetricRegistry;
@@ -84,16 +86,16 @@ public final class CodaHaleMetricsTracker extends MetricsTracker
 
    /** {@inheritDoc} */
    @Override
-   public Context recordConnectionRequest()
+   public void recordConnectionAcquireNanos(final long elapsedAcquireNanos)
    {
-      return new Context(connectionObtainTimer);
+      connectionObtainTimer.update(elapsedAcquireNanos, TimeUnit.NANOSECONDS);
    }
 
    /** {@inheritDoc} */
    @Override
-   public void recordConnectionUsage(final long elapsedLastBorrowed)
+   public void recordConnectionUsageMillis(final long elapsedBorrowedMilli)
    {
-      connectionUsage.update(elapsedLastBorrowed);
+      connectionUsage.update(elapsedBorrowedMilli);
    }
 
    public Timer getConnectionAcquisitionTimer()
@@ -105,20 +107,4 @@ public final class CodaHaleMetricsTracker extends MetricsTracker
    {
       return connectionUsage;
    }
-
-   public static final class Context extends MetricsTimerContext
-   {
-      final Timer.Context innerContext;
-
-      Context(Timer timer) {
-         innerContext = timer.time();
-      }
-
-      /** {@inheritDoc} */
-      @Override
-      public void stop()
-      {
-         innerContext.stop();
-      }
-   }
 }

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

@@ -43,8 +43,6 @@ 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.MetricsTracker;
-import com.zaxxer.hikari.metrics.MetricsTracker.MetricsTimerContext;
 import com.zaxxer.hikari.metrics.MetricsTrackerFactory;
 import com.zaxxer.hikari.metrics.PoolStats;
 import com.zaxxer.hikari.metrics.dropwizard.CodahaleHealthChecker;
@@ -158,7 +156,6 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
 
       try {
          long timeout = hardTimeout;
-         final MetricsTimerContext metricsContext = (isRecordMetrics ? metricsTracker.recordConnectionRequest() : MetricsTracker.NO_CONTEXT);
          do {
             final PoolEntry poolEntry = connectionBag.borrow(timeout, TimeUnit.MILLISECONDS);
             if (poolEntry == null) {
@@ -171,8 +168,7 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
                timeout = hardTimeout - clockSource.elapsedMillis(startTime, now);
             }
             else {
-               metricsTracker.recordLastBurrowed(poolEntry, now);
-               metricsContext.stop();
+               metricsTracker.recordBorrowStats(poolEntry, startTime);
                return poolEntry.createProxyConnection(leakTask.start(poolEntry), now);
             }
          }

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

@@ -23,7 +23,7 @@ import org.slf4j.LoggerFactory;
 
 import com.zaxxer.hikari.HikariConfig;
 import com.zaxxer.hikari.metrics.MetricsTracker;
-import com.zaxxer.hikari.metrics.MetricsTracker.MetricsTimerContext;
+import com.zaxxer.hikari.util.ClockSource;
 import com.zaxxer.hikari.util.DefaultThreadFactory;
 import com.zaxxer.hikari.util.DriverDataSource;
 import com.zaxxer.hikari.util.PropertyElf;
@@ -564,33 +564,26 @@ abstract class PoolBase
          tracker.close();
       }
 
-      MetricsTimerContext recordConnectionRequest()
-      {
-         return tracker.recordConnectionRequest();
-      }
-
       void recordConnectionUsage(final PoolEntry poolEntry)
       {
-         tracker.recordConnectionUsage(poolEntry.getElapsedLastBorrowed());
+         tracker.recordConnectionUsageMillis(poolEntry.getElapsedLastBorrowed());
       }
 
       /**
        * @param poolEntry
        * @param now
        */
-      void recordLastBurrowed(final PoolEntry poolEntry, final long now)
+      void recordBorrowStats(final PoolEntry poolEntry, final long startTime)
       {
+         final long now = ClockSource.INSTANCE.currentTime();
          poolEntry.lastBorrowed = now;
+         tracker.recordConnectionAcquireNanos(ClockSource.INSTANCE.elapsedNanos(startTime, now));
       }
    }
 
    static final class NopMetricsTrackerDelegate extends MetricsTrackerDelegate
    {
-      MetricsTimerContext recordConnectionRequest()
-      {
-         return MetricsTracker.NO_CONTEXT;
-      }
-
+      @Override
       void recordConnectionUsage(final PoolEntry poolEntry)
       {
          // no-op
@@ -603,7 +596,7 @@ abstract class PoolBase
       }
 
       @Override
-      void recordLastBurrowed(final PoolEntry poolEntry, final long now)
+      void recordBorrowStats(final PoolEntry poolEntry, final long startTime)
       {
          // no-op
       }

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

@@ -63,6 +63,25 @@ public interface ClockSource
     */
    long elapsedMillis(long startTime, long endTime);
 
+   /**
+    * Convert an opaque time-stamp returned by currentTime() into an
+    * elapsed time in milliseconds, based on the current instant in time.
+    *
+    * @param startTime an opaque time-stamp returned by an instance of this class
+    * @return the elapsed time between startTime and now in milliseconds
+    */
+   long elapsedNanos(long startTime);
+
+   /**
+    * Get the difference in nanoseconds between two opaque time-stamps returned
+    * by currentTime().
+    *
+    * @param startTime an opaque time-stamp returned by an instance of this class
+    * @param endTime an opaque time-stamp returned by an instance of this class
+    * @return the elapsed time between startTime and endTime in nanoseconds
+    */
+   long elapsedNanos(long startTime, long endTime);
+
    /**
     * Return the specified opaque time-stamp plus the specified number of milliseconds.
     *
@@ -72,6 +91,12 @@ public interface ClockSource
     */
    long plusMillis(long time, long millis);
 
+   /**
+    * Get the TimeUnit the ClockSource is denominated in.
+    * @return
+    */
+   TimeUnit getSourceTimeUnit();
+
    /**
     * Factory class used to create a platform-specific ClockSource. 
     */
@@ -113,17 +138,38 @@ public interface ClockSource
 
       /** {@inheritDoc} */
       @Override
-      public long toMillis(long time)
+      public long elapsedNanos(final long startTime)
+      {
+         return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis() - startTime);
+      }
+
+      /** {@inheritDoc} */
+      @Override
+      public long elapsedNanos(final long startTime, final long endTime)
+      {
+         return TimeUnit.MILLISECONDS.toNanos(endTime - startTime);
+      }
+
+      /** {@inheritDoc} */
+      @Override
+      public long toMillis(final long time)
       {
          return time;
       }
 
       /** {@inheritDoc} */
       @Override
-      public long plusMillis(long time, long millis)
+      public long plusMillis(final long time, final long millis)
       {
          return time + millis;
       }
+
+      /** {@inheritDoc} */
+      @Override
+      public TimeUnit getSourceTimeUnit()
+      {
+         return TimeUnit.MILLISECONDS;
+      }
    }
 
    final class NanosecondClockSource implements ClockSource
@@ -156,11 +202,32 @@ public interface ClockSource
          return TimeUnit.NANOSECONDS.toMillis(endTime - startTime);
       }
 
+      /** {@inheritDoc} */
+      @Override
+      public long elapsedNanos(final long startTime)
+      {
+         return System.nanoTime() - startTime;
+      }
+
+      /** {@inheritDoc} */
+      @Override
+      public long elapsedNanos(final long startTime, final long endTime)
+      {
+         return endTime - startTime;
+      }
+
       /** {@inheritDoc} */
       @Override
       public long plusMillis(final long time, final long millis)
       {
          return time + TimeUnit.MILLISECONDS.toNanos(millis);
       }
+
+      /** {@inheritDoc} */
+      @Override
+      public TimeUnit getSourceTimeUnit()
+      {
+         return TimeUnit.NANOSECONDS;
+      }
    }
 }

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

@@ -121,18 +121,16 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
    public T borrow(long timeout, final TimeUnit timeUnit) throws InterruptedException
    {
       // Try the thread-local list first, if there are no blocked threads waiting already
-      if (!synchronizer.hasQueuedThreads()) {
-         List<?> list = threadList.get();
-         if (weakThreadLocals && list == null) {
-            list = new ArrayList<>(16);
-            threadList.set(list);
-         }
+      List<?> list = threadList.get();
+      if (weakThreadLocals && list == null) {
+         list = new ArrayList<>(16);
+         threadList.set(list);
+      }
 
-         for (int i = list.size() - 1; i >= 0; i--) {
-            final T bagEntry = (T) (weakThreadLocals ? ((WeakReference) list.remove(i)).get() : list.remove(i));
-            if (bagEntry != null && bagEntry.compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
-               return bagEntry;
-            }
+      for (int i = list.size() - 1; i >= 0; i--) {
+         final T bagEntry = (T) (weakThreadLocals ? ((WeakReference) list.remove(i)).get() : list.remove(i));
+         if (bagEntry != null && bagEntry.compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
+            return bagEntry;
          }
       }