nrdata-damon/src/org/leolo/rail/DatabaseManager.java

package org.leolo.rail;


import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.XAConnection;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.mariadb.jdbc.MariaDbPoolDataSource;

public class DatabaseManager {
	
	private static Logger log = LogManager.getLogger(DatabaseManager.class);
	
	private static DatabaseManager instance;

	private MariaDbPoolDataSource ds;
	
	public synchronized static DatabaseManager getInstance() {
		if(instance==null) {
			instance = new DatabaseManager();
		}
		return instance;
	}
	
	private DatabaseManager() {
		ConfigurationManager cm = ConfigurationManager.getInstance();
		if(
				!cm.containsKey("db.host")||
				!cm.containsKey("db.user")||
				!cm.containsKey("db.pwd")||
				!cm.containsKey("db.name")
		) {
			log.fatal("Missing required property");
			System.exit(1);
		}
		String url = "jdbc:mariadb://"+cm.getProperty("db.host")+
				":"+cm.getProperty("db.port", "3306")+
				"/"+cm.getProperty("db.name");
		log.info("Connecting to DB {} as {}", url, cm.get("db.user"));
		try {
			ds = new MariaDbPoolDataSource(url);
			ds.setMinPoolSize(1);
			ds.setMaxPoolSize(Integer.parseInt(cm.getOrDefault("db.poolsize", "20").toString()));
			ds.setUser(cm.getProperty("db.user").toString());
			ds.setPassword(cm.getProperty("db.pwd").toString());
		} catch (SQLException e) {
			log.fatal("Cannot connect to DB",e);
			System.exit(-2);
		}
	}
	
	public boolean testPool() {
		try(Connection conn = ds.getConnection()){
			try(Statement stmt = conn.createStatement()){
				try (ResultSet rs = stmt.executeQuery("SELECT CONNECTION_ID()")){
					if(rs.next()) {
						log.debug("Connection ID: {}", rs.getString(1));
					}
				}
			}
		} catch (SQLException e) {
			log.warn("Exception when testing the connection., e");
			return false;
		}
		return true;
	}

	public Connection getConnection() throws SQLException {
		Connection conn =  ds.getConnection();
		conn.setAutoCommit(false);
		return conn;
	}

	public XAConnection getXAConnection() throws SQLException {
		XAConnection conn = ds.getXAConnection();
		return conn;
	}
	
	public void shutdown() {
		ds.close();
	}
}