Added loadChunk, unloadChunk and unloadChunkRequest.

src/main/java/net/minecraft/server/ChunkProviderServer.java

@@ -9,8 +9,10 @@ import java.util.Map;
 import java.util.Set;
 
 // CraftBukkit start
+import org.bukkit.Location;
 import org.bukkit.craftbukkit.CraftChunk;
 import org.bukkit.craftbukkit.CraftServer;
+import org.bukkit.entity.Player;
 import org.bukkit.event.Event.Type;
 import org.bukkit.event.world.ChunkLoadEvent;
 // CraftBukkit end
@@ -47,8 +49,94 @@ public class ChunkProviderServer implements IChunkProvider {
     public boolean a(int i, int j) {
         return this.e.containsKey(i, j);
     }
-    // CraftBukkit end
 
+    public void saveChunk(int x, int z) {
+        Chunk chunk = this.b(x, z);
+        chunk.e();
+        this.b(chunk);
+        this.a(chunk);
+    }
+
+    public boolean unloadChunk(int x, int z, boolean save, boolean safe) {
+        if (safe && isChunkInUse(x, z))
+            return false;
+        
+        Chunk chunk = this.b(x, z);
+        
+        if (save)
+            saveChunk(x, z);
+
+        this.a.remove(x, z);
+        this.e.remove(x, z);
+        this.f.remove(chunk);
+        return true;
+    }
+    
+    public boolean unloadChunkRequest(int x, int z, boolean safe) {
+        if (safe && isChunkInUse(x, z))
+            return false;
+        c(x, z);
+        return true;
+    }
+
+    public boolean isChunkInUse(int x, int z) {
+        CraftServer server = g.getServer();
+        Player[] players = server.getOnlinePlayers();
+        for (Player player : players) {
+            Location loc = player.getLocation();
+            if (loc.getWorld() != g.getWorld()) {
+                continue;
+            }
+            // If the chunk is within 256 blocks of a player, refuse to accept the unload request
+            // This is larger than the distance of loaded chunks that actually surround a player
+            // The player is the center of a 21x21 chunk grid, so the edge is 10 chunks (160 blocks) away from the player
+            if (Math.abs(loc.getBlockX() - (x << 4)) <= 256 && Math.abs(loc.getBlockZ() - (z << 4)) <= 256) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public Chunk loadChunk(int x, int z, boolean generate) {
+        if (generate) {
+            // Use the default variant of loadChunk when generate == true.
+            return d(x, z);
+        }
+
+        this.a.remove(x, z);
+        Chunk chunk = (Chunk) this.e.get(x, z);
+
+        if (chunk == null) {
+            chunk = this.e(x, z);
+
+            if (chunk != null) {
+                this.e.put(x, z, chunk);
+                this.f.add(chunk);
+
+                chunk.c();
+                chunk.d();
+
+                if (!chunk.n && this.a(x + 1, z + 1) && this.a(x, z + 1) && this.a(x + 1, z)) {
+                    this.a(this, x, z);
+                }
+
+                if (this.a(x - 1, z) && !this.b(x - 1, z).n && this.a(x - 1, z + 1) && this.a(x, z + 1) && this.a(x - 1, z)) {
+                    this.a(this, x - 1, z);
+                }
+
+                if (this.a(x, z - 1) && !this.b(x, z - 1).n && this.a(x + 1, z - 1) && this.a(x, z - 1) && this.a(x + 1, z)) {
+                    this.a(this, x, z - 1);
+                }
+
+                if (this.a(x - 1, z - 1) && !this.b(x - 1, z - 1).n && this.a(x - 1, z - 1) && this.a(x, z - 1) && this.a(x - 1, z)) {
+                    this.a(this, x - 1, z - 1);
+                }
+            }
+        }
+        return chunk;
+    }
+    // CraftBukkit end
+    
     public void c(int i, int j) {
         int k = i * 16 + 8 - this.g.spawnX;
         int l = j * 16 + 8 - this.g.spawnZ;

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -75,7 +75,31 @@ public class CraftWorld implements World {
     }
 
     public void loadChunk(int x, int z) {
-         world.A.d(x, z);
+        loadChunk(x, z, true);
+    }
+
+    public boolean loadChunk(int x, int z, boolean generate) {
+        return world.A.loadChunk(x, z, generate) != null;
+    }
+
+    public boolean unloadChunk(int x, int z) {
+        return unloadChunk(x, z, true);
+    }
+
+    public boolean unloadChunk(int x, int z, boolean save) {
+        return unloadChunk(x, z, save, false);
+    }
+
+    public boolean unloadChunk(int x, int z, boolean save, boolean safe) {
+        return world.A.unloadChunk(x, z, save, safe);
+    }
+    
+    public boolean unloadChunkRequest(int x, int z) {
+        return unloadChunkRequest(x, z, true);
+    }
+    
+    public boolean unloadChunkRequest(int x, int z, boolean safe) {
+        return world.A.unloadChunkRequest(x, z, safe);
     }
 
     public boolean isChunkLoaded(Chunk chunk) {