de.mhus.db.karaf.datasource.DataSourceFailOver Maven / Gradle / Ivy

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abstract db commands
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/**
 * Copyright 2018 Mike Hummel
 *
 * 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 de.mhus.db.karaf.datasource;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.LinkedList;
import java.util.logging.Logger;

import javax.sql.DataSource;

public class DataSourceFailOver implements DataSource, DelegatedDataSource {

    private LinkedList list;

    public DataSource getCurrentDataSource() {
        if (list.isEmpty()) return null;
        return list.get(0); // implement fallback
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return getCurrentDataSource().getLogWriter();
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
        getCurrentDataSource().setLogWriter(out);
    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
        getCurrentDataSource().setLoginTimeout(seconds);
    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return getCurrentDataSource().getLoginTimeout();
    }

    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return getCurrentDataSource().getParentLogger();
    }

    @Override
    public  T unwrap(Class iface) throws SQLException {
        return getCurrentDataSource().unwrap(iface);
    }

    @Override
    public boolean isWrapperFor(Class iface) throws SQLException {
        return getCurrentDataSource().isWrapperFor(iface);
    }

    @Override
    public Connection getConnection() throws SQLException {
        return getCurrentDataSource().getConnection();
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        SQLException lastException = null;
        for (int i = 0; i < list.size(); i++) {
            try {
                return getCurrentDataSource().getConnection(username, password);
            } catch (SQLException e) {
                if (list.isEmpty()) throw e;
                // move first connection to the end
                DataSource ds = list.removeFirst();
                list.addLast(ds);
                lastException = e;
            }
        }
        if (lastException != null) throw lastException;
        throw new SQLException("no DataSource found");
    }

    public void setDestinations(LinkedList list) {
        this.list = list;
    }

    @Override
    public String getDelegateURL() {
        try {
            return "failover:" + getCurrentDataSource().getConnection().getMetaData().getURL();
        } catch (Throwable e) {
            return "failover:" + e;
        }
    }
}