Essentials/EssentialsAntiCheat/src/com/earth2me/essentials/anticheat/LagMeasureTask.java

package com.earth2me.essentials.anticheat;

import com.earth2me.essentials.anticheat.NoCheat;
import org.bukkit.World;


/**
 * A task running in the background that measures tick time vs. real time
 *
 */
public class LagMeasureTask implements Runnable
{
	private int ingameseconds = 1;
	private long lastIngamesecondTime = System.currentTimeMillis();
	private long lastIngamesecondDuration = 2000L;
	private boolean skipCheck = false;
	private int lagMeasureTaskId = -1;
	private final NoCheat plugin;

	public LagMeasureTask(NoCheat plugin)
	{
		this.plugin = plugin;
	}

	public void start()
	{
		// start measuring with a delay of 10 seconds
		lagMeasureTaskId = plugin.getServer().getScheduler().scheduleSyncRepeatingTask(plugin, this, 20, 20);
	}

	public void run()
	{
		try
		{
			boolean oldStatus = skipCheck;
			// If the previous second took to long, skip checks during
			// this second
			skipCheck = lastIngamesecondDuration > 2000;

			if (plugin.getConfig((World)null).logging.debugmessages)
			{
				if (oldStatus != skipCheck && skipCheck)
				{
					plugin.getLogger().warning("detected server lag, some checks will not work.");
				}
				else if (oldStatus != skipCheck && !skipCheck)
				{
					plugin.getLogger().info("server lag seems to have stopped, reenabling checks.");
				}
			}

			long time = System.currentTimeMillis();
			lastIngamesecondDuration = time - lastIngamesecondTime;
			if (lastIngamesecondDuration < 1000)
			{
				lastIngamesecondDuration = 1000;
			}
			else if (lastIngamesecondDuration > 3600000)
			{
				lastIngamesecondDuration = 3600000; // top limit of 1
				// hour per "second"
			}
			lastIngamesecondTime = time;
			ingameseconds++;

			// Check if some data is outdated now and let it be removed
			if (ingameseconds % 62 == 0)
			{
				plugin.cleanDataMap();
			}
		}
		catch (Exception e)
		{
			// Just prevent this thread from dying for whatever reason
		}

	}

	public void cancel()
	{
		if (lagMeasureTaskId != -1)
		{
			try
			{
				plugin.getServer().getScheduler().cancelTask(lagMeasureTaskId);
			}
			catch (Exception e)
			{
				plugin.getLogger().warning("Couldn't cancel LagMeasureTask: " + e.getMessage());
			}
			lagMeasureTaskId = -1;
		}
	}

	public boolean skipCheck()
	{
		return skipCheck;
	}
}