Load war zone blocks in batches to prevent server hangs

War zone blocks are now loaded from the database at a configurable speed of blocks per tick. This prevents an entire server from hanging whenever a war zone is reset. The speed can be increased or decreased based on your server's performance.

war/src/main/java/com/tommytony/war/War.java

@@ -183,6 +183,7 @@ public class War extends JavaPlugin {
 		warConfig.put(WarConfig.MAXZONES, 12);
 		warConfig.put(WarConfig.PVPINZONESONLY, false);
 		warConfig.put(WarConfig.TNTINZONESONLY, false);
+		warConfig.put(WarConfig.RESETSPEED, 5000);
 		
 		warzoneDefaultConfig.put(WarzoneConfig.AUTOASSIGN, false);
 		warzoneDefaultConfig.put(WarzoneConfig.BLOCKHEADS, true);

war/src/main/java/com/tommytony/war/Warzone.java

@@ -1097,7 +1097,6 @@ public class Warzone {
 	public void reinitialize() {
 		this.isReinitializing = true;
 		this.getVolume().resetBlocksAsJob();
-		this.initializeZoneAsJob();
 	}
 
 	public void handlePlayerLeave(Player player, Location destination, PlayerMoveEvent event, boolean removeFromTeam) {

war/src/main/java/com/tommytony/war/config/WarConfig.java

@@ -8,7 +8,8 @@ public enum WarConfig {
 	KEEPOLDZONEVERSIONS (Boolean.class),
 	MAXZONES (Integer.class),
 	PVPINZONESONLY (Boolean.class),
-	TNTINZONESONLY (Boolean.class);
+	TNTINZONESONLY (Boolean.class),
+	RESETSPEED (Integer.class);
 	
 	private final Class<?> configType;
 

war/src/main/java/com/tommytony/war/job/PartialZoneResetJob.java

@@ -0,0 +1,85 @@
+package com.tommytony.war.job;
+
+import java.sql.SQLException;
+import java.text.MessageFormat;
+import java.util.logging.Level;
+
+import org.bukkit.entity.Player;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import com.tommytony.war.War;
+import com.tommytony.war.Warzone;
+import com.tommytony.war.structure.ZoneLobby;
+import com.tommytony.war.volume.ZoneVolume;
+
+public class PartialZoneResetJob extends BukkitRunnable implements Cloneable {
+
+	private final Warzone zone;
+	private final ZoneVolume volume;
+	private final int speed;
+	private final int total;
+	private int completed = 0;
+	private final long startTime = System.currentTimeMillis();
+	private long messageCounter = System.currentTimeMillis();
+	public static final long MESSAGE_INTERVAL = 3000;
+	// Ticks between job runs
+	public static final int JOB_INTERVAL = 1;
+
+	/**
+	 * Reset a warzone's blocks at a certain speed.
+	 * 
+	 * @param volume
+	 *            Warzone to reset.
+	 * @param speed
+	 *            Blocks to modify per #INTERVAL.
+	 */
+	public PartialZoneResetJob(Warzone zone, int speed) {
+		this.zone = zone;
+		this.volume = zone.getVolume();
+		this.speed = speed;
+		this.total = volume.size();
+	}
+
+	@Override
+	public void run() {
+		try {
+			volume.resetSection(completed, speed);
+			completed += speed;
+			if (completed < total) {
+				if (System.currentTimeMillis() - messageCounter > MESSAGE_INTERVAL) {
+					messageCounter = System.currentTimeMillis();
+					int percent = (int) (((double) completed / (double) total) * 100);
+					long seconds = (System.currentTimeMillis() - startTime) / 1000;
+					String message = MessageFormat.format(
+							War.war.getString("zone.battle.resetprogress"),
+							percent, seconds);
+					for (Player player : War.war.getServer().getOnlinePlayers()) {
+						ZoneLobby lobby = ZoneLobby.getLobbyByLocation(player);
+						if (zone.getPlayers().contains(player)
+								|| (lobby != null && lobby.getZone() == zone)) {
+							War.war.msg(player, message);
+						}
+					}
+				}
+				War.war.getServer().getScheduler()
+						.runTaskLater(War.war, this.clone(), JOB_INTERVAL);
+			} else {
+				zone.initializeZone();
+				War.war.getLogger().info(
+						"Finished reset cycle for warzone " + volume.getName());
+			}
+		} catch (SQLException e) {
+			War.war.getLogger().log(Level.WARNING,
+					"Failed to load zone during reset loop", e);
+		}
+	}
+
+	@Override
+	protected PartialZoneResetJob clone() {
+		try {
+			return (PartialZoneResetJob) super.clone();
+		} catch (CloneNotSupportedException e) {
+			throw new Error(e);
+		}
+	}
+}

war/src/main/java/com/tommytony/war/mapper/ZoneVolumeMapper.java

@@ -56,10 +56,12 @@ public class ZoneVolumeMapper {
 	 * @param String zoneName Zone to load the volume from
 	 * @param World world The world the zone is located
 	 * @param boolean onlyLoadCorners Should only the corners be loaded
+	 * @param start Starting position to load blocks at
+	 * @param total Amount of blocks to read
 	 * @return integer Changed blocks
 	 * @throws SQLException Error communicating with SQLite3 database
 	 */
-	public static int load(ZoneVolume volume, String zoneName, World world, boolean onlyLoadCorners) throws SQLException {
+	public static int load(ZoneVolume volume, String zoneName, World world, boolean onlyLoadCorners, int start, int total) throws SQLException {
 		int changed = 0;
 		File databaseFile = new File(War.war.getDataFolder(), String.format("/dat/warzone-%s/volume-%s.sl3", zoneName, volume.getName()));
 		if (!databaseFile.exists()) {
@@ -99,7 +101,7 @@ public class ZoneVolumeMapper {
 			databaseConnection.close();
 			return 0;
 		}
-		ResultSet query = stmt.executeQuery("SELECT * FROM blocks");
+		ResultSet query = stmt.executeQuery("SELECT * FROM blocks ORDER BY rowid LIMIT " + start + ", " + total);
 		while (query.next()) {
 			int x = query.getInt("x"), y = query.getInt("y"), z = query.getInt("z");
 			BlockState modify = corner1.getRelative(x, y, z).getState();

war/src/main/java/com/tommytony/war/volume/ZoneVolume.java

@@ -10,6 +10,8 @@ import org.bukkit.block.Block;
 import com.tommytony.war.Team;
 import com.tommytony.war.War;
 import com.tommytony.war.Warzone;
+import com.tommytony.war.config.WarConfig;
+import com.tommytony.war.job.PartialZoneResetJob;
 import com.tommytony.war.mapper.ZoneVolumeMapper;
 import com.tommytony.war.structure.Monument;
 
@@ -48,7 +50,7 @@ public class ZoneVolume extends Volume {
 	}
 
 	public void loadCorners() throws SQLException {
-		ZoneVolumeMapper.load(this, this.zone.getName(), this.getWorld(), true);
+		ZoneVolumeMapper.load(this, this.zone.getName(), this.getWorld(), true, 0, 0);
 		this.isSaved = true;
 	}
 
@@ -57,7 +59,7 @@ public class ZoneVolume extends Volume {
 		// Load blocks directly from disk and onto the map (i.e. no more in-memory warzone blocks)
 		int reset = 0;
 		try {
-			reset = ZoneVolumeMapper.load(this, this.zone.getName(), this.getWorld(), false);
+			reset = ZoneVolumeMapper.load(this, this.zone.getName(), this.getWorld(), false, 0, Integer.MAX_VALUE);
 		} catch (SQLException ex) {
 			War.war.log("Failed to load warzone " + zone.getName() + ": " + ex.getMessage(), Level.WARNING);
 			ex.printStackTrace();
@@ -66,6 +68,30 @@ public class ZoneVolume extends Volume {
 		this.isSaved = true;
 	}
 
+	/**
+	 * Reset a section of blocks in the warzone.
+	 * 
+	 * @param start
+	 *            Starting position for reset.
+	 * @param total
+	 *            Amount of blocks to reset.
+	 * @throws SQLException
+	 */
+	public void resetSection(int start, int total) throws SQLException {
+		ZoneVolumeMapper.load(this, this.zone.getName(), this.getWorld(), false, start, total);
+	}
+
+	@Override
+	/**
+	 * Reset the blocks in this warzone at the speed defined in WarConfig#RESETSPEED.
+	 * The job will automatically spawn new instances of itself to run every tick until it is done resetting all blocks.
+	 */
+	public void resetBlocksAsJob() {
+		PartialZoneResetJob job = new PartialZoneResetJob(zone, War.war
+				.getWarConfig().getInt(WarConfig.RESETSPEED));
+		War.war.getServer().getScheduler().runTask(War.war, job);
+	}
+
 	public void setNorthwest(Location block) throws NotNorthwestException, TooSmallException, TooBigException {
 		// northwest defaults to top block
 		Location topBlock = new Location(block.getWorld(), block.getX(), block.getWorld().getMaxHeight(), block.getZ());

war/src/main/resources/messages.properties

@@ -92,6 +92,7 @@ zone.battle.end            = The battle is over. Team {0} lost: {1} died and the
 zone.battle.newscores      = New scores - {0}
 zone.battle.next           = The battle was interrupted. Resetting warzone {0}...
 zone.battle.reset          = A new battle begins. Resetting warzone...
+zone.battle.resetprogress  = Reset progress: {0}%, {1} seconds
 zone.bomb.broadcast        = {0} blew up team {1}''s spawn. Team {2} scores one point.
 zone.cake.broadcast        = {0} captured cake {1}. Team {2} scores one point and gets a full lifepool.
 zone.flagcapture.broadcast = {0} captured team {1}''s flag. Team {2} scores one point.