[Savestates] Fixed world being unloaded after loadstate (#247)

The issue was that
1. The chunks, after being loaded, where marked as "ticked = false". So
when it came to sending the chunks, a check would prevent that.
2. The chunks were not sorted before sending them. Chunks are sorted
every 4 ticks and savestating will also prevent that

Changes
- Added new MixinPlayerChunkMap and PlayerChunkMapDuck to add new
methods to the chunk map
- Removed AccessorPlayerChunkmap, as it's handled via ducks
- Removed MixinWorldServer and WorldServerDuck as it's merged with the
chunkmap duck
- Updated some documentation

Author: ScribbleTAS

src/main/java/com/minecrafttas/tasmod/mixin/savestates/AccessorPlayerChunkMap.java

@@ -0,0 +1,113 @@
+package com.minecrafttas.tasmod.mixin.savestates;
+
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import com.google.common.collect.ComparisonChain;
+import com.minecrafttas.tasmod.savestates.handlers.SavestateWorldHandler;
+import com.minecrafttas.tasmod.util.Ducks.PlayerChunkMapDuck;
+
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.server.management.PlayerChunkMap;
+import net.minecraft.server.management.PlayerChunkMapEntry;
+import net.minecraft.world.WorldProvider;
+import net.minecraft.world.WorldServer;
+import net.minecraft.world.chunk.Chunk;
+
+@Mixin(PlayerChunkMap.class)
+public abstract class MixinPlayerChunkMap implements PlayerChunkMapDuck {
+
+	@Shadow
+	@Final
+	private List<EntityPlayerMP> players;
+	@Shadow
+	private boolean sortMissingChunks;
+	@Shadow
+	@Final
+	private List<PlayerChunkMapEntry> entriesWithoutChunks;
+	@Shadow
+	private boolean sortSendToPlayers;
+	@Shadow
+	@Final
+	private List<PlayerChunkMapEntry> pendingSendToPlayers;
+	@Shadow
+	@Final
+	private WorldServer world;
+
+	/**
+	 * @return The players from the specified chunk map
+	 * @see SavestateWorldHandler#addPlayerToChunkMap()
+	 */
+	@Override
+	public List<EntityPlayerMP> getPlayers() {
+		return players;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * @see SavestateWorldHandler#addPlayersToChunkMap()
+	 */
+	@Override
+	public void forceTick() {
+
+		/*
+		 * Update the chunks to make them eligible to be sent to the client
+		 * 
+		 * In the #sendToPlayers() method is a check where the chunk is not sent,
+		 * when Chunk#isPopulated() is false. This would normally happen during the WorldServer#updateBlocks() method,
+		 * but we want to send the chunks without updating the blocks, hence this is circumvented like this.
+		 */
+		for (Iterator<Chunk> iterator2 = this.getChunkIterator(); iterator2.hasNext();) {
+			Chunk chunk = (Chunk) iterator2.next();
+			chunk.enqueueRelightChecks();
+			chunk.onTick(false);
+		}
+
+		this.sortMissingChunks = false;
+		Collections.sort(this.entriesWithoutChunks, new Comparator<PlayerChunkMapEntry>() {
+			public int compare(PlayerChunkMapEntry playerChunkMapEntry, PlayerChunkMapEntry playerChunkMapEntry2) {
+				return ComparisonChain.start().compare(playerChunkMapEntry.getClosestPlayerDistance(), playerChunkMapEntry2.getClosestPlayerDistance()).result();
+			}
+		});
+
+		this.sortSendToPlayers = false;
+		Collections.sort(this.pendingSendToPlayers, new Comparator<PlayerChunkMapEntry>() {
+
+			public int compare(PlayerChunkMapEntry playerChunkMapEntry, PlayerChunkMapEntry playerChunkMapEntry2) {
+				return ComparisonChain.start().compare(playerChunkMapEntry.getClosestPlayerDistance(), playerChunkMapEntry2.getClosestPlayerDistance()).result();
+			}
+		});
+
+		if (!this.pendingSendToPlayers.isEmpty()) {
+
+			int i = 81;
+			Iterator<PlayerChunkMapEntry> iterator2 = this.pendingSendToPlayers.iterator();
+
+			while (iterator2.hasNext()) {
+				PlayerChunkMapEntry playerChunkMapEntry3 = (PlayerChunkMapEntry) iterator2.next();
+				if (playerChunkMapEntry3.sendToPlayers()) {
+					iterator2.remove();
+					if (--i < 0) {
+						break;
+					}
+				}
+			}
+		}
+
+		if (this.players.isEmpty()) {
+			WorldProvider worldProvider = this.world.provider;
+			if (!worldProvider.canRespawnHere()) {
+				this.world.getChunkProvider().queueUnloadAll();
+			}
+		}
+	}
+
+	@Shadow
+	protected abstract Iterator<Chunk> getChunkIterator();
+}

src/main/java/com/minecrafttas/tasmod/mixin/savestates/MixinPlayerChunkMap.java

@@ -39,12 +39,6 @@ public enum TASmodKeybinds {
 	TEST1("Various Testing", "TASmod", Keyboard.KEY_F12, () -> {
 	}, VirtualKeybindings::isKeyDown),
 	TEST2("Various Testing2", "TASmod", Keyboard.KEY_F7, () -> {
-		//			try {
-		//				TASmodClient.client = new Client("localhost", TASmod.networkingport - 1, TASmodPackets.values(), mc.getSession().getProfile().getName(), true);
-		//			} catch (Exception e) {
-		//				e.printStackTrace();
-		//			}
-//		TASmodClient.controller.setTASState(TASstate.PLAYBACK);
 	}, VirtualKeybindings::isKeyDown);
 
 	private Keybind keybind;

src/main/java/com/minecrafttas/tasmod/mixin/savestates/MixinWorldServer.java

@@ -394,9 +394,7 @@ public void loadState(int savestateIndex, boolean tickrate0, boolean changeIndex
 		server.getPlayerList().sendMessage(new TextComponentString(TextFormatting.GREEN + "Savestate " + indexToLoad + " loaded"));
 
 		// Add players to the chunk
-		server.getPlayerList().getPlayers().forEach(player -> {
-			worldHandler.addPlayerToServerChunk(player);
-		});
+		worldHandler.addPlayersToServerChunks();
 
 		worldHandler.sendChunksToClient();
 

src/main/java/com/minecrafttas/tasmod/registries/TASmodKeybinds.java

@@ -4,11 +4,10 @@
 
 import java.util.List;
 
-import com.minecrafttas.tasmod.mixin.savestates.AccessorPlayerChunkMap;
 import com.minecrafttas.tasmod.mixin.savestates.MixinChunkProviderServer;
 import com.minecrafttas.tasmod.savestates.SavestateHandlerClient;
 import com.minecrafttas.tasmod.util.Ducks.ChunkProviderDuck;
-import com.minecrafttas.tasmod.util.Ducks.WorldServerDuck;
+import com.minecrafttas.tasmod.util.Ducks.PlayerChunkMapDuck;
 import com.minecrafttas.tasmod.util.LoggerMarkers;
 
 import net.minecraft.client.Minecraft;
@@ -55,6 +54,15 @@ public void enableLevelSaving() {
 		}
 	}
 
+	/**
+	 * Add players to their respective chunks
+	 */
+	public void addPlayersToServerChunks() {
+		server.getPlayerList().getPlayers().forEach(player -> {
+			addPlayerToServerChunk(player);
+		});
+	}
+
 	/**
 	 * Just like {@link SavestateHandlerClient#addPlayerToClientChunk(EntityPlayer)}, adds the player to the chunk on the server.
 	 * This prevents the player from being able to place block inside of him
@@ -150,15 +158,14 @@ private void addPlayerToChunkMap(WorldServer world, EntityPlayerMP player) {
 		int playerChunkPosY = (int) player.posZ >> 4;
 		PlayerChunkMap playerChunkMap = world.getPlayerChunkMap();
 
-		List<EntityPlayerMP> players = ((AccessorPlayerChunkMap) playerChunkMap).getPlayers();
+		List<EntityPlayerMP> players = ((PlayerChunkMapDuck) playerChunkMap).getPlayers();
 
 		if (players.contains(player)) {
 			LOGGER.debug(LoggerMarkers.Savestate, "Not adding player {} to chunkmap, player already exists", player.getName());
 		} else {
 			playerChunkMap.addPlayer(player);
 		}
-		Chunk chunk = world.getChunkProvider().provideChunk(playerChunkPosX, playerChunkPosY);
-		chunk.addEntity(player);
+		world.getChunkProvider().provideChunk(playerChunkPosX, playerChunkPosY);
 
 		world.spawnEntity(player);
 	}
@@ -205,8 +212,8 @@ public void sendChunksToClient() {
 		WorldServer[] worlds = server.worlds;
 
 		for (WorldServer world : worlds) {
-			WorldServerDuck worldTick = (WorldServerDuck) world;
-			worldTick.sendChunksToClient();
+			PlayerChunkMapDuck chunkMap = (PlayerChunkMapDuck) world.getPlayerChunkMap();
+			chunkMap.forceTick();
 		}
 	}
 

src/main/java/com/minecrafttas/tasmod/savestates/SavestateHandlerServer.java

@@ -1,5 +1,11 @@
 package com.minecrafttas.tasmod.util;
 
+import java.util.List;
+
+import com.minecrafttas.tasmod.mixin.savestates.MixinPlayerChunkMap;
+
+import net.minecraft.entity.player.EntityPlayerMP;
+
 /**
  * Oh boy, ducks! I can't help but quack up when they waddle their way into the code. :duck:
  * But let me tell you a little secret: I have a love-hate relationship with ducks. Not the adorable feathered creatures, mind you, but those sneaky little programming devils that swim in the deep waters of out-of-scope variables.
@@ -32,20 +38,6 @@ public static interface ChunkProviderDuck {
 		public void unloadAllChunks();
 	}
 
-	/**
-	 * Quacks the worldserver to implement custom chunk ticking behavior
-	 * 
-	 * @author Scribble
-	 */
-	public static interface WorldServerDuck {
-
-		/**
-		 * Sends the chunks to the client
-		 * @see com.minecrafttas.tasmod.mixin.savestates.MixinWorldServer#sendChunksToClient() MixinWorldServer#sendChunksToClient()
-		 */
-		public void sendChunksToClient();
-	}
-
 	/**
 	 * Quacks the gui screen to spit out mouse positions independent of the display size
 	 */
@@ -129,4 +121,25 @@ public static interface WorldClientDuck {
 		 */
 		public void clearEntityList();
 	}
+
+	/**
+	 * Quacks the {@link MixinPlayerChunkMap}
+	 */
+	public static interface PlayerChunkMapDuck {
+		/**
+		 * @return The list of players of this chunk map
+		 */
+		public List<EntityPlayerMP> getPlayers();
+
+		/**
+		 * <p>Forces a tick in the chunk map without being dependent on the world time.
+		 * <p>The chunk map is responsible for sending the necessary chunks to the client.<br>
+		 * However, to properly do that, the chunks have to be sorted first, which happens every few world ticks.
+		 * <p>Under normal circumstances, WorldServer#tick() would update the world time to make this happen,
+		 * but our goal with savestates is to load the chunks without advancing the world time.
+		 * Hence why this method sorts and ticks the chunk map, without waiting for the world time
+		 * @see MixinPlayerChunkMap#forceTick()
+		 */
+		public void forceTick();
+	}
 }

src/main/java/com/minecrafttas/tasmod/savestates/handlers/SavestateWorldHandler.java

@@ -12,11 +12,10 @@
 		"savestates.AccessorAnvilChunkLoader",
 		"savestates.AccessorChunkLoader",
 		"savestates.AccessorEntityLivingBase",
-		"savestates.AccessorPlayerChunkMap",
+		"savestates.MixinPlayerChunkMap",
 		"savestates.MixinChunkProviderServer",
 		"savestates.MixinNetHandlerPlayServer",
 		"savestates.MixinScoreboard",
-		"savestates.MixinWorldServer",
 
 		// Events
 		"events.MixinEntityPlayerMP",