ertg

package org.yveltal.database;

import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Hashtable;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/**
 *
 * @author Sino
 *
 */
public class DatabasePool {
    /**
     *
     */
    private final ExecutorService connectionPool = Executors.newCachedThreadPool();

    /**
     *
     */
    private final Map<String, Connection> connectionsCache = new Hashtable<String, Connection>();

    /**
     *
     */
    private Connection connection;

    /**
     *
     */
    public DatabasePool() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     *
     * @return
     */
    public void establishConnection(final Database database) {
        try {
            //Throw a callback and use a Future to asynchronously establish the connection
            final Future<Connection> connectionFuture = connectionPool.submit(new Callable<Connection>() {
                @Override
                public Connection call() throws Exception {
                    return DriverManager.getConnection("", database.getUsername(), database.getPassword());
                }
            });

            //Stores this connection if successfully established into our connections cache
            connectionsCache.put(database.getDatabaseName(), connection = connectionFuture.get());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     *
     * @param runnable
     * @return
     */
    public Future<?> submit(Runnable task) {
        if (connectionsCache.isEmpty()) {
            throw new IllegalStateException("No connection ready for submission");
        }
        return connectionPool.submit(task);
    }

    /**
     *
     * @param statement
     * @return
     */
    public Future<?> prepare(final String databaseName, final DatabaseStatement statement) throws Exception {
        if (connectionsCache.containsKey(databaseName)) {
            final Future<?> prepare = connectionPool.submit(new Runnable() {
                @Override
                public void run() {
                    statement.execute(connectionsCache.get(databaseName));
                }
            });
            return prepare;
        }

        return null;
    }

    /**
     *
     * @return
     */
    public Connection getConnection() {
        return connection;
    }

    /**
     *
     * @return
     */
    public Connection getConnection(String databaseName) {
        return connectionsCache.get(databaseName);
    }

}