net.fender.sql.LoadBalancingDataSource.java Source code

Introduction

Here is the source code for net.fender.sql.LoadBalancingDataSource.java

Source

/* 
 * Copyright 2008 - 2009 Eric Fenderbosch
 * 
 * Licensed 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.
 */
package net.fender.sql;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collection;

import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * @author Eric Fenderbosch
 */
public abstract class LoadBalancingDataSource extends ManagedConnectionDataSource {

    private static final Log log = LogFactory.getLog(LoadBalancingDataSource.class);

    protected int timesToRetry = 0;

    /**
     * @param dataSources
     */
    public abstract void setDataSources(Collection<DataSource> dataSources);

    @Override
    protected ManagedConnection getManagedConnection() throws SQLException {
        ManagedConnection managedConnection = null;
        SQLException exceptionToThrow = new SQLException();
        int tries = 0;
        while (managedConnection == null && tries <= timesToRetry) {
            DataSource dataSource = getNextDataSource();
            try {
                Connection connection = dataSource.getConnection();
                managedConnection = new ManagedConnection(connection, this);
                if (validateConnectionOnAquire) {
                    validateConnection(managedConnection);
                }
            } catch (SQLException e) {
                log.warn("connection failure " + e.getMessage());
                exceptionToThrow.setNextException(e);
                tries++;
            }
        }
        if (managedConnection == null) {
            throw exceptionToThrow;
        }
        return managedConnection;
    }

    @Override
    protected void close(ManagedConnection managedConnection) throws SQLException {
        JdbcUtils.close(managedConnection.getConnection());
    }

    /**
     * sub-classes may implement round robin, FIFO, LIFO, etc.
     * 
     * @return
     */
    protected abstract DataSource getNextDataSource();

    /**
     * @param timesToRetry
     */
    protected void setTimesToRetry(int timesToRetry) {
        this.timesToRetry = timesToRetry;
    }

}