Add metric for recording count and rate of connection timeouts

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

@@ -35,6 +35,10 @@ public class MetricsTracker implements AutoCloseable
    {
    }
 
+   public void recordConnectionTimeout()
+   {
+   }
+
    @Override
    public void close()
    {

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

@@ -18,8 +18,10 @@ package com.zaxxer.hikari.metrics.dropwizard;
 
 import java.util.concurrent.TimeUnit;
 
+import com.codahale.metrics.Counter;
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.Histogram;
+import com.codahale.metrics.Meter;
 import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.Timer;
 import com.zaxxer.hikari.metrics.MetricsTracker;
@@ -30,6 +32,8 @@ public final class CodaHaleMetricsTracker extends MetricsTracker
    private final String poolName;
    private final Timer connectionObtainTimer;
    private final Histogram connectionUsage;
+   private final Counter connectionTimeouts;
+   private final Meter connectionTimeoutMeter;
    private final MetricRegistry registry;
 
    public CodaHaleMetricsTracker(final String poolName, final PoolStats poolStats, final MetricRegistry registry)
@@ -38,6 +42,8 @@ public final class CodaHaleMetricsTracker extends MetricsTracker
       this.registry = registry;
       this.connectionObtainTimer = registry.timer(MetricRegistry.name(poolName, "pool", "Wait"));
       this.connectionUsage = registry.histogram(MetricRegistry.name(poolName, "pool", "Usage"));
+      this.connectionTimeouts = registry.counter(MetricRegistry.name(poolName, "pool", "ConnectionTimeouts"));
+      this.connectionTimeoutMeter = registry.meter(MetricRegistry.name(poolName, "pool", "ConnectionTimeoutRate"));
 
       registry.register(MetricRegistry.name(poolName, "pool", "TotalConnections"),
                         new Gauge<Integer>() {
@@ -98,6 +104,13 @@ public final class CodaHaleMetricsTracker extends MetricsTracker
       connectionUsage.update(elapsedBorrowedMillis);
    }
 
+   @Override
+   public void recordConnectionTimeout()
+   {
+      connectionTimeouts.inc();
+      connectionTimeoutMeter.mark();
+   }
+
    public Timer getConnectionAcquisitionTimer()
    {
       return connectionObtainTimer;

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

@@ -184,6 +184,7 @@ public class HikariPool extends PoolBase implements HikariPoolMXBean, IBagStateL
       }
 
       logPoolState("Timeout failure ");
+      metricsTracker.recordConnectionTimeout();
 
       String sqlState = null;
       final Throwable originalException = getLastConnectionFailure();

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

@@ -584,6 +584,10 @@ abstract class PoolBase
          poolEntry.lastBorrowed = now;
          tracker.recordConnectionAcquiredNanos(ClockSource.INSTANCE.elapsedNanos(startTime, now));
       }
+
+      void recordConnectionTimeout() {
+         tracker.recordConnectionTimeout();
+      }
    }
 
    static final class NopMetricsTrackerDelegate extends MetricsTrackerDelegate
@@ -605,5 +609,11 @@ abstract class PoolBase
       {
          // no-op
       }
+
+      @Override
+      void recordConnectionTimeout()
+      {
+         // no-op
+      }
    }
 }