mcMMO/src/main/java/com/gmail/nossr50/util/Database.java

package com.gmail.nossr50.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Properties;

import com.gmail.nossr50.mcMMO;
import com.gmail.nossr50.config.Config;
import com.gmail.nossr50.datatypes.DatabaseUpdate;
import com.gmail.nossr50.runnables.SQLReconnect;

public class Database {

    private static Config configInstance = Config.getInstance();

    private static String connectionString = "jdbc:mysql://" + configInstance.getMySQLServerName() + ":" + configInstance.getMySQLServerPort() + "/" + configInstance.getMySQLDatabaseName() + "?user=" + configInstance.getMySQLUserName() + "&password=" + configInstance.getMySQLUserPassword();
    private static String tablePrefix = configInstance.getMySQLTablePrefix();
    private static Connection connection = null;
    private static mcMMO plugin = null;

    // Scale waiting time by this much per failed attempt
    private static final double SCALING_FACTOR = 5;
    
    // Minimum wait in nanoseconds (default 500ms)
    private static final long MIN_WAIT = 500*100000L;

    // Maximum time to wait between reconnects (default 5 minutes)
    private static final long MAX_WAIT = 5*60000000000L;

    // How long to wait when checking if connection is valid (default 3 seconds)
    private static final int VALID_TIMEOUT = 3;

    // When next to try connecting to Database in nanoseconds
    private static long nextReconnectTimestamp = 0L;
    
    // How many connection attemtps have failed
    private static int reconnectAttempt = 0;

    public Database(mcMMO instance) {
        plugin = instance;
        checkConnected(); //Connect to MySQL
    }

    /**
     * Attempt to connect to the mySQL database.
     */
    public static void connect() {
        try {
            System.out.println("[mcMMO] Attempting connection to MySQL...");

            // Force driver to load if not yet loaded
            Class.forName("com.mysql.jdbc.Driver");
            Properties connectionProperties = new Properties();
            connectionProperties.put("autoReconnect", "false");
            connectionProperties.put("maxReconnects", "0");
            connection = DriverManager.getConnection(connectionString, connectionProperties);

            System.out.println("[mcMMO] Connection to MySQL was a success!");
        }
        catch (SQLException ex) {
        	connection = null;
            System.out.println("[mcMMO] Connection to MySQL failed!");
            ex.printStackTrace();
            printErrors(ex);
        } catch (ClassNotFoundException ex) {
        	connection = null;
            System.out.println("[mcMMO] MySQL database driver not found!");
            ex.printStackTrace();
		}
    }

    /**
     * Attempt to create the database structure.
     */
    public void createStructure() {
        write("CREATE TABLE IF NOT EXISTS `" + tablePrefix + "huds` (`user_id` int(10) unsigned NOT NULL,"
                + "`hudtype` varchar(50) NOT NULL DEFAULT 'STANDARD',"
                + "PRIMARY KEY (`user_id`)) ENGINE=MyISAM DEFAULT CHARSET=latin1;");
        write("CREATE TABLE IF NOT EXISTS `" + tablePrefix + "users` (`id` int(10) unsigned NOT NULL AUTO_INCREMENT,"
                + "`user` varchar(40) NOT NULL,"
                + "`lastlogin` int(32) unsigned NOT NULL,"
                + "PRIMARY KEY (`id`),"
                + "UNIQUE KEY `user` (`user`)) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1;");
        write("CREATE TABLE IF NOT EXISTS `" + tablePrefix + "cooldowns` (`user_id` int(10) unsigned NOT NULL,"
                + "`taming` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`mining` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`woodcutting` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`repair` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`unarmed` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`herbalism` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`excavation` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`archery` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`swords` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`axes` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`acrobatics` int(32) unsigned NOT NULL DEFAULT '0',"
                + "`blast_mining` int(32) unsigned NOT NULL DEFAULT '0',"
                + "PRIMARY KEY (`user_id`)) ENGINE=MyISAM DEFAULT CHARSET=latin1;");
        write("CREATE TABLE IF NOT EXISTS `" + tablePrefix + "skills` (`user_id` int(10) unsigned NOT NULL,"
                + "`taming` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`mining` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`woodcutting` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`repair` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`unarmed` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`herbalism` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`excavation` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`archery` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`swords` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`axes` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`acrobatics` int(10) unsigned NOT NULL DEFAULT '0',"
                + "PRIMARY KEY (`user_id`)) ENGINE=MyISAM DEFAULT CHARSET=latin1;");
        write("CREATE TABLE IF NOT EXISTS `" + tablePrefix + "experience` (`user_id` int(10) unsigned NOT NULL,"
                + "`taming` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`mining` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`woodcutting` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`repair` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`unarmed` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`herbalism` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`excavation` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`archery` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`swords` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`axes` int(10) unsigned NOT NULL DEFAULT '0',"
                + "`acrobatics` int(10) unsigned NOT NULL DEFAULT '0',"
                + "PRIMARY KEY (`user_id`)) ENGINE=MyISAM DEFAULT CHARSET=latin1;");

        checkDatabaseStructure(DatabaseUpdate.FISHING);
        checkDatabaseStructure(DatabaseUpdate.BLAST_MINING);
    }

    /**
     * Check database structure for missing values.
     *
     * @param update Type of data to check updates for
     */
    public void checkDatabaseStructure(DatabaseUpdate update) {
        String sql = null;
        ResultSet resultSet;
        HashMap<Integer, ArrayList<String>> rows = new HashMap<Integer, ArrayList<String>>();

        switch (update) {
        case BLAST_MINING:
            sql = "SELECT * FROM  `" + tablePrefix + "cooldowns` ORDER BY  `" + tablePrefix + "cooldowns`.`blast_mining` ASC LIMIT 0 , 30";
            break;

        case FISHING:
            sql = "SELECT * FROM  `" + tablePrefix + "experience` ORDER BY  `" + tablePrefix + "experience`.`fishing` ASC LIMIT 0 , 30";
            break;

        default:
            break;
        }

        try {
            PreparedStatement statement = connection.prepareStatement(sql);
            resultSet = statement.executeQuery();

            while (resultSet.next()) {
                ArrayList<String> column = new ArrayList<String>();

                for (int i = 1; i <= resultSet.getMetaData().getColumnCount(); i++) {
                    column.add(resultSet.getString(i));
                }

                rows.put(resultSet.getRow(), column);
            }

            statement.close();
        }
        catch (SQLException ex) {
            switch (update) {
            case BLAST_MINING:
                System.out.println("Updating mcMMO MySQL tables for Blast Mining...");
                write("ALTER TABLE `"+tablePrefix + "cooldowns` ADD `blast_mining` int(32) NOT NULL DEFAULT '0' ;");
                break;

            case FISHING:
                System.out.println("Updating mcMMO MySQL tables for Fishing...");
                write("ALTER TABLE `"+tablePrefix + "skills` ADD `fishing` int(10) NOT NULL DEFAULT '0' ;");
                write("ALTER TABLE `"+tablePrefix + "experience` ADD `fishing` int(10) NOT NULL DEFAULT '0' ;");
                break;

            default:
                break;
            }
        }
    }

    /**
     * Attempt to write the SQL query.
     *
     * @param sql Query to write.
     * @return true if the query was successfully written, false otherwise.
     */
    public boolean write(String sql) {
        if (checkConnected()) {
            try {
                PreparedStatement statement = connection.prepareStatement(sql);
                statement.executeUpdate();
                statement.close();
                return true;
            }
            catch (SQLException ex) {
                printErrors(ex);
                return false;
            }
        }

        return false;
    }

    /**
     * Get the Integer. Only return first row / first field.
     *
     * @param sql SQL query to execute
     * @return the value in the first row / first field
     */
    public int getInt(String sql) {
        ResultSet resultSet;
        int result = 0;

        if (checkConnected()) {
            try {
                PreparedStatement statement = connection.prepareStatement(sql);
                resultSet = statement.executeQuery();

                if (resultSet.next()) {
                    result = resultSet.getInt(1);
                }
                else {
                    result = 0;
                }

                statement.close();
            }
            catch (SQLException ex) {
                printErrors(ex);
            }
        }

        return result;
    }

    /**
     * Check connection status and re-establish if dead or stale.
     *
     * If the very first immediate attempt fails, further attempts 
     * will be made in progressively larger intervals up to MAX_WAIT 
     * intervals. 
     *
     * This allows for MySQL to time out idle connections as needed by 
     * server operator, without affecting McMMO, while still providing 
     * protection against a database outage taking down Bukkit's tick  
     * processing loop due to attemping a database connection each
     * time McMMO needs the database.
     *
     * @return the boolean value for whether or not we are connected
     */
    public static boolean checkConnected() {
    	boolean isClosed = true;
    	boolean isValid = false;
    	boolean exists = (connection != null);

    	// Initialized as needed later
    	long timestamp=0;
    	
    	// If we're waiting for server to recover then leave early
    	if (nextReconnectTimestamp > 0 && nextReconnectTimestamp > System.nanoTime()) {
    		return false;
    	}
    	
    	if (exists) {
            try {
            	isClosed = connection.isClosed();
    		} catch (SQLException e) {
    			isClosed = true;
    			e.printStackTrace();
    			printErrors(e);
    		}
            
            if (!isClosed) {
                try {
                	isValid = connection.isValid(VALID_TIMEOUT);
        		} catch (SQLException e) {
        			// Don't print stack trace because it's valid to lose idle connections 
        			// to the server and have to restart them.
        			isValid = false;
        		}
            }
    	}

    	// Leave if all ok
    	if (exists && !isClosed && isValid) {
    		// Housekeeping
    		nextReconnectTimestamp = 0;
			reconnectAttempt = 0;
    		return true;
    	}
 
    	// Cleanup after ourselves for GC and MySQL's sake
    	if (exists && !isClosed) {
    		try { 
    			connection.close();
    		} catch (SQLException ex) {
    			// This is a housekeeping exercise, ignore errors
    		}
    	}

    	// Try to connect again
    	connect();

    	// Leave if connection is good
    	try {
			if (connection != null && !connection.isClosed()) {
				// Schedule a database save if we really had an outage
				if (reconnectAttempt > 1) {
		            plugin.getServer().getScheduler().scheduleSyncDelayedTask(plugin, new SQLReconnect(plugin), 5);
				}
				nextReconnectTimestamp = 0;
				reconnectAttempt = 0;
				return true;
			}
		} catch (SQLException e) {
			// Failed to check isClosed, so presume connection is bad and attempt later
			e.printStackTrace();
			printErrors(e);
		}

    	reconnectAttempt++;
    		
   		nextReconnectTimestamp = (long)(System.nanoTime() + Math.min(MAX_WAIT, (reconnectAttempt*SCALING_FACTOR*MIN_WAIT)));
   		
   		return false;
    }

    /**
     * Read SQL query.
     *
     * @param sql SQL query to read
     * @return the rows in this SQL query
     */
    public HashMap<Integer, ArrayList<String>> read(String sql) {
        ResultSet resultSet;
        HashMap<Integer, ArrayList<String>> rows = new HashMap<Integer, ArrayList<String>>();

        if (checkConnected()) {
            try {
                PreparedStatement statement = connection.prepareStatement(sql);
                resultSet = statement.executeQuery();

                while (resultSet.next()) {
                    ArrayList<String> column = new ArrayList<String>();

                    for (int i = 1; i <= resultSet.getMetaData().getColumnCount(); i++) {
                        column.add(resultSet.getString(i));
                    }

                    rows.put(resultSet.getRow(), column);
                }

                statement.close();
            }
            catch (SQLException ex) {
                printErrors(ex);
            }
        }

        return rows;
    }

    private static void printErrors(SQLException ex) {
        System.out.println("SQLException: " + ex.getMessage());
        System.out.println("SQLState: " + ex.getSQLState());
        System.out.println("VendorError: " + ex.getErrorCode());
    }
}