From 5eebe56dd1fd478618e5a09b7bef5f389eb2d11f Mon Sep 17 00:00:00 2001
From: Brett Wooldridge <brett.wooldridge@gmail.com>
Date: Sun, 6 Mar 2016 17:37:10 +0900
Subject: [PATCH] Fixes #591 Synchronise the track statement method, and
 clearing of the tracked statement list.

---
 src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java | 6 ++++--
 src/main/java/com/zaxxer/hikari/util/FastList.java        | 4 ++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java b/src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java
index b4fb824d..1ad3a404 100644
--- a/src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java
+++ b/src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java
@@ -182,7 +182,7 @@ public abstract class ProxyConnection implements Connection
       leakTask.cancel();
    }
 
-   private final <T extends Statement> T trackStatement(final T statement)
+   private final synchronized <T extends Statement> T trackStatement(final T statement)
    {
       openStatements.add(statement);
 
@@ -205,7 +205,9 @@ public abstract class ProxyConnection implements Connection
             }
          }
 
-         openStatements.clear();
+         synchronized (this) {
+            openStatements.clear();
+         }
       }
    }
 
diff --git a/src/main/java/com/zaxxer/hikari/util/FastList.java b/src/main/java/com/zaxxer/hikari/util/FastList.java
index 8eb9347f..6b6c6dd5 100644
--- a/src/main/java/com/zaxxer/hikari/util/FastList.java
+++ b/src/main/java/com/zaxxer/hikari/util/FastList.java
@@ -184,6 +184,10 @@ public final class FastList<T> extends ArrayList<T>
    @Override
    public T remove(int index)
    {
+      if (size == 0) {
+         return null;
+      }
+
       final T old = elementData[index];
 
       final int numMoved = size - index - 1;