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Enables C3P0 with Hibernate connections in the GuicedPersistence provider Requires JDK 8 and up
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/*
 * Distributed as part of c3p0 v.0.9.5.3
 *
 * Copyright (C) 2018 Machinery For Change, Inc.
 *
 * Author: Steve Waldman 
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of EITHER:
 *
 *     1) The GNU Lesser General Public License (LGPL), version 2.1, as 
 *        published by the Free Software Foundation
 *
 * OR
 *
 *     2) The Eclipse Public License (EPL), version 1.0
 *
 * You may choose which license to accept if you wish to redistribute
 * or modify this work. You may offer derivatives of this work
 * under the license you have chosen, or you may provide the same
 * choice of license which you have been offered here.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * You should have received copies of both LGPL v2.1 and EPL v1.0
 * along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
 * If not, the text of these licenses are currently available at
 *
 * LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 *  EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php 
 * 
 */

package com.mchange.v2.c3p0;

import java.sql.Connection;

/**
 *  Having expanded the once-simple ConnectionTester interface to support both
 *  user-specified queries and return of root cause Exceptions (via an out-param),
 *  this interface has grown unnecessarily complex.
 *  
 *  If you wish to implement a custom Connection tester, here is the simple
 *  way to do it
 *  
 *  
 *    Extend {@link com.mchange.v2.c3p0.AbstractConnectionTester}
 *    Override only the two abstract methods
 *    
 *       public int activeCheckConnection(Connection c, String preferredTestQuery, Throwable[] rootCauseOutParamHolder)
 *       public int statusOnException(Connection c, Throwable t, String preferredTestQuery, Throwable[] rootCauseOutParamHolder)
 *    
 *    Take care to ensure that your methods are defined to allow preferredTestQuery and 
 *    rootCauseOutParamHolder to be null.
 *  
 *  
 *  Parameter rootCauseOutParamHolder is an optional parameter, which if supplied, will be a Throwable array whose size
 *  it at least one. If a Connection test fails because of some Exception, the Connection tester may set this Exception as the
 *  zero-th element of the array to provide information about why and how the test failed. 
 */
public abstract class AbstractConnectionTester implements UnifiedConnectionTester
{
    /**
     *  Override, but remember that preferredTestQuery and rootCauseOutParamHolder
     *  can be null.
     */
    public abstract int activeCheckConnection(Connection c, String preferredTestQuery, Throwable[] rootCauseOutParamHolder);

    /**
     *  Override, but remember that preferredTestQuery and rootCauseOutParamHolder
     *  can be null.
     */
    public abstract int statusOnException(Connection c, Throwable t, String preferredTestQuery, Throwable[] rootCauseOutParamHolder);

    //usually just leave the rest of these as-is
    public int activeCheckConnection(Connection c)
    { return activeCheckConnection( c, null, null); }

    public int activeCheckConnection(Connection c, Throwable[] rootCauseOutParamHolder)
    { return activeCheckConnection( c, null, rootCauseOutParamHolder); }

    public int activeCheckConnection(Connection c, String preferredTestQuery)
    { return activeCheckConnection( c, preferredTestQuery, null); }

    public int statusOnException(Connection c, Throwable t)
    { return statusOnException( c, t, null, null); }

    public int statusOnException(Connection c, Throwable t, Throwable[] rootCauseOutParamHolder)
    { return statusOnException( c, t, null, rootCauseOutParamHolder); }

    public int statusOnException(Connection c, Throwable t, String preferredTestQuery)
    { return statusOnException( c, t, preferredTestQuery, null); }
}