Saver.java

/**
 * BetonQuest - advanced quests for Bukkit
 * Copyright (C) 2016  Jakub "Co0sh" Sapalski
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package pl.betoncraft.betonquest.database;

import java.util.concurrent.ConcurrentLinkedQueue;

import org.bukkit.Bukkit;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;

import pl.betoncraft.betonquest.BetonQuest;
import pl.betoncraft.betonquest.api.QuestDataUpdateEvent;
import pl.betoncraft.betonquest.database.Connector.UpdateType;

/**
 * Saves the data to the database asynchronously
 * 
 * @author Jakub Sapalski
 */
public class Saver extends Thread implements Listener {

	Connector con;
	ConcurrentLinkedQueue<Record> queue;
	boolean run;
	boolean active;

	/**
	 * Creates new database saver thread
	 */
	public Saver() {
		this.con = new Connector();
		this.queue = new ConcurrentLinkedQueue<>();
		this.run = true;
		Bukkit.getPluginManager().registerEvents(this, BetonQuest.getInstance());
	}

	public void run() {
		while (true) {
			while (queue.isEmpty()) {
				if (!run) {
					return;
				}
				synchronized (this) {
					try {
						active = false;
						wait();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
			if (!active) {
				con.refresh();
				active = true;
			}
			Record rec = queue.poll();
			con.updateSQL(rec.getType(), rec.getArgs());
		}
	}

	/**
	 * Adds new record to the queue, where it will be saved to the database.
	 * 
	 * @param rec
	 *            Record to save
	 */
	public synchronized void add(Record rec) {
		queue.add(rec);
		notify();
	}

	/**
	 * Ends this saver's job, letting it save all remaining data.
	 */
	public synchronized void end() {
		run = false;
		notify();
	}

	@EventHandler
	public void onDataUpdate(QuestDataUpdateEvent e) {
		add(new Record(UpdateType.REMOVE_OBJECTIVES, new String[] { e.getPlayerID(), e.getObjID() }));
		add(new Record(UpdateType.ADD_OBJECTIVES, new String[] { e.getPlayerID(), e.getObjID(), e.getData() }));
	}

	/**
	 * Holds the data and the method of saving them to the database
	 * 
	 * @author Jakub Sapalski
	 */
	public static class Record {

		private UpdateType type;
		private String[] args;

		/**
		 * Creates new Record, which can be saved to the database using
		 * Saver.add()
		 * 
		 * @param type
		 *            method used for saving the data
		 * @param args
		 *            list of Strings which will be saved to the database
		 */
		public Record(UpdateType type, String[] args) {
			this.type = type;
			this.args = args;
		}

		private UpdateType getType() {
			return type;
		}

		private String[] getArgs() {
			return args;
		}
	}

}