VELOCITY-989 Fixed multiple connection leaks in DataSourceResourceLoader.

velocity-engine-core/pom.xml

@@ -251,6 +251,24 @@
             <scope>test</scope>
             <classifier>${test.jdbc.driver.classifier}</classifier>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-dbcp2</artifactId>
+            <version>2.13.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.tomcat</groupId>
+            <artifactId>tomcat-jdbc</artifactId>
+            <version>9.0.104</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.zaxxer</groupId>
+            <artifactId>HikariCP</artifactId>
+            <version>4.0.3</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>

velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/loader/DataSourceResourceLoader.java

@@ -165,8 +165,14 @@ public void close() throws IOException
             super.close();
             try
             {
-                resultSet.close();
-                factory.releaseStatement(templateSQL, (PreparedStatement)resultSet.getStatement());
+                PreparedStatement statement = (PreparedStatement) resultSet.getStatement();
+                try {
+                    if (!resultSet.isClosed()) {
+                        resultSet.close();
+                    }
+                } finally {
+                    factory.releaseStatement(templateSQL, statement);
+                }
             }
             catch (RuntimeException re)
             {
@@ -295,7 +301,7 @@ public synchronized Reader getResourceReader(final String name, String encoding)
             throw new ResourceNotFoundException("DataSourceResourceLoader: Template name was empty or null");
         }
 
-        ResultSet rs = null;
+        ResultSet rs;
         try
         {
             PreparedStatement statement = factory.prepareStatement(templateSQL);
@@ -314,6 +320,11 @@ public synchronized Reader getResourceReader(final String name, String encoding)
             }
             else
             {
+                try {
+                    closeResultSet(rs);
+                } finally {
+                    factory.releaseStatement(templateSQL, statement);
+                }
                 throw new ResourceNotFoundException("DataSourceResourceLoader: "
                         + "could not find resource '"
                         + name + "'");
@@ -408,7 +419,9 @@ private void closeResultSet(final ResultSet rs)
         {
             try
             {
-                rs.close();
+                if (!rs.isClosed()) {
+                    rs.close();
+                }
             }
             catch (RuntimeException re)
             {

velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/loader/DefaultDatabaseObjectsFactory.java

@@ -35,7 +35,7 @@ public void init(DataSource dataSource, ExtProperties properties)
     public PreparedStatement prepareStatement(String sql) throws SQLException
     {
         Connection connection = dataSource.getConnection();
-        return connection.prepareStatement(sql);
+        return PreparedStatementProxy.newInstance(connection.prepareStatement(sql), connection);
     }
 
     /**
@@ -49,11 +49,15 @@ public void releaseStatement(String sql, PreparedStatement stmt) throws SQLExcep
         Connection connection = stmt.getConnection();
         try
         {
-            stmt.close();
+            if (!stmt.isClosed()) {
+                stmt.close();
+            }
         }
         finally
         {
-            connection.close();
+            if (!connection.isClosed()) {
+                connection.close();
+            }
         }
     }
 }

velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/loader/PreparedStatementProxy.java

@@ -0,0 +1,69 @@
+package org.apache.velocity.runtime.resource.loader;
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+/**
+ * Proxy for {@link java.sql.PreparedStatement} that guarantees getConnection will always return the DataSource
+ * provided wrapped {@link java.sql.Connection} and not the underlying database specific connection.
+ * Also overrides executeQuery to return a proxy for {@link java.sql.ResultSet} see {@link ResultSetProxy}
+ */
+public class PreparedStatementProxy implements InvocationHandler {
+    private final PreparedStatement wrappedPreparedStatement;
+    private PreparedStatement proxyPreparedStatement;
+    private final Connection wrappedConnection;
+
+    public PreparedStatementProxy(PreparedStatement wrappedPreparedStatement, Connection wrappedConnection) {
+        this.wrappedPreparedStatement = wrappedPreparedStatement;
+        this.wrappedConnection = wrappedConnection;
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        Object result;
+        if (method.getName().equals("getConnection")) {
+            result = wrappedConnection;
+        } else if (method.getName().equals("executeQuery")) {
+            return ResultSetProxy.newInstance((ResultSet) method.invoke(wrappedPreparedStatement, args), proxyPreparedStatement);
+        } else {
+            result = method.invoke(wrappedPreparedStatement, args);
+        }
+        return result;
+    }
+
+    public static PreparedStatement newInstance(PreparedStatement ps, Connection con) throws SQLException {
+        PreparedStatementProxy invocationHandler = new PreparedStatementProxy(ps, con);
+        PreparedStatement proxyPreparedStatement = (PreparedStatement) Proxy.newProxyInstance(ps.getClass().getClassLoader(),
+                ps.getClass().getInterfaces(),
+                invocationHandler);
+        invocationHandler.setProxyPreparedStatement(proxyPreparedStatement);
+        return proxyPreparedStatement;
+    }
+
+    public void setProxyPreparedStatement(PreparedStatement proxyPreparedStatement) {
+        this.proxyPreparedStatement = proxyPreparedStatement;
+    }
+}

velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/loader/ResultSetProxy.java

@@ -0,0 +1,58 @@
+package org.apache.velocity.runtime.resource.loader;
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+/**
+ * Proxy for {@link java.sql.ResultSet} that guarantees getStatement will return the original wrapped {@link java.sql.Statement}
+ * and will not throw an exception or return null if the ResultSet is closed.
+ */
+public class ResultSetProxy implements InvocationHandler {
+    private final ResultSet wrappedResultSet;
+    private final Statement wrappedStatement;
+
+    public ResultSetProxy(ResultSet wrappedResultSet, Statement wrappedStatement) {
+        this.wrappedResultSet = wrappedResultSet;
+        this.wrappedStatement = wrappedStatement;
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        Object result;
+        if (method.getName().equals("getStatement")) {
+            result = wrappedStatement;
+        } else {
+            result = method.invoke(wrappedResultSet, args);
+        }
+        return result;
+    }
+
+    public static ResultSet newInstance(ResultSet rs, Statement ps) throws SQLException {
+        return (ResultSet) Proxy.newProxyInstance(rs.getClass().getClassLoader(),
+                rs.getClass().getInterfaces(),
+                new ResultSetProxy(rs, ps));
+    }
+
+}