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There is a newer version: 0.9.5.5_1

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); }

    public boolean equals( Object o ) { return this.getClass().equals( o.getClass() ); }
    public int hashCode() { return this.getClass().getName().hashCode(); }
}