oglimmer/ggo

package de.oglimmer.ggo.db;

import static de.oglimmer.ggo.util.GridGameOneProperties.PROPERTIES;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.concurrent.TimeUnit;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class ConnectionPool {
    public static final ConnectionPool INSTANCE = new ConnectionPool();

    private ComboPooledDataSource cpds;

    private ConnectionPool() {
        PROPERTIES.registerOnReload(this::init);
        init();
    }

    public synchronized void shutdown() {
        if (cpds != null) {
            log.debug("Shutdown c3p0 connection pool");
            try {
                final int WAIT_TIME = 5;
                long c = 0; // wait for max 30 sec
                while (cpds.getNumBusyConnections() > 0 && c < 30_000) {
                    TimeUnit.MILLISECONDS.sleep(WAIT_TIME);
                    c += WAIT_TIME;
                }
            } catch (SQLException | InterruptedException e) {
                // SQLException can actually never happen
                // In case of InterruptedException we just proceed
            }
            cpds.close();
            cpds = null;
        }
    }

    @SneakyThrows(value = PropertyVetoException.class)
    private synchronized void init() {
        shutdown();
        String jdbcUrl = buildUrl();
        log.debug("Open c3p0 connection pool for {}:{}", jdbcUrl, PROPERTIES.getDbUser());
        cpds = new ComboPooledDataSource();
        cpds.setDriverClass(PROPERTIES.getDbDriver());
        cpds.setJdbcUrl(jdbcUrl);
        cpds.setUser(PROPERTIES.getDbUser());
        cpds.setPassword(PROPERTIES.getDbPassword());
    }

    public synchronized Connection getCon() throws SQLException {
        return cpds.getConnection();
    }

    private String buildUrl() {
        String url = PROPERTIES.getDbServerUrl() + PROPERTIES.getDbSchema();
        if (PROPERTIES.getDbParameter() != null) {
            url += "?" + PROPERTIES.getDbParameter();
        }
        return url;
    }

}