Slow down Forge chunk gen worker when save queue is to high.

Prevents task from completing while tons of chunks are pending save.
And add minimum notification every 60 seconds.

jsons/1.12.2.json

@@ -1,10 +1,10 @@
 {
     "assetIndex": {
         "id": "1.12",
-        "sha1": "98c430c16a705f18a58a281b27caabf3ef09d40d",
-        "size": 169253,
-        "url": "https://launchermeta.mojang.com/mc/assets/1.12/98c430c16a705f18a58a281b27caabf3ef09d40d/1.12.json",
-        "totalSize": 127453671
+        "sha1": "e75e9535754c6f2158b0b18b35660f45c4495d78",
+        "size": 169257,
+        "url": "https://launchermeta.mojang.com/mc/assets/1.12/e75e9535754c6f2158b0b18b35660f45c4495d78/1.12.json",
+        "totalSize": 127722338
     },
     "assets": "1.12",
     "downloads": {
@@ -719,6 +719,6 @@
     "minecraftArguments": "--username ${auth_player_name} --version ${version_name} --gameDir ${game_directory} --assetsDir ${assets_root} --assetIndex ${assets_index_name} --uuid ${auth_uuid} --accessToken ${auth_access_token} --userType ${user_type} --versionType ${version_type}",
     "minimumLauncherVersion": 18,
     "releaseTime": "2017-09-18T08:39:46+00:00",
-    "time": "2018-02-15T16:26:45+00:00",
+    "time": "2018-04-02T07:39:26+00:00",
     "type": "release"
 }

patches/minecraft/net/minecraft/world/chunk/storage/AnvilChunkLoader.java.patch

@@ -179,3 +179,13 @@
      }
  
      @Nullable
+@@ -563,4 +650,9 @@
+             return entity;
+         }
+     }
++
++    public int getPendingSaveCount()
++    {
++        return this.field_75828_a.size();
++    }
+ }

src/main/java/net/minecraftforge/server/command/ChunkGenWorker.java

@@ -18,6 +18,7 @@
  */
 package net.minecraftforge.server.command;
 
+import java.io.IOException;
 import java.util.ArrayDeque;
 import java.util.Queue;
 
@@ -26,8 +27,10 @@ import net.minecraft.server.management.PlayerChunkMapEntry;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.text.TextComponentBase;
 import net.minecraft.util.text.TextComponentTranslation;
+import net.minecraft.world.MinecraftException;
 import net.minecraft.world.WorldServer;
 import net.minecraft.world.chunk.Chunk;
+import net.minecraft.world.chunk.storage.AnvilChunkLoader;
 import net.minecraftforge.common.DimensionManager;
 import net.minecraftforge.common.WorldWorkerManager.IWorker;
 
@@ -40,6 +43,7 @@ public class ChunkGenWorker implements IWorker
     private final Queue<BlockPos> queue;
     private final int notificationFrequency;
     private int lastNotification = 0;
+    private long lastNotifcationTime = 0;
     private int genned = 0;
     private Boolean keepingLoaded;
 
@@ -51,6 +55,7 @@ public class ChunkGenWorker implements IWorker
         this.dim  = dim;
         this.queue = buildQueue();
         this.notificationFrequency = interval != -1 ? interval : Math.max(total / 20, 100); //Every 5% or every 100, whichever is more.
+        this.lastNotifcationTime = System.currentTimeMillis(); //We also notify at least once every 60 seconds, to show we haven't froze.
     }
 
     protected Queue<BlockPos> buildQueue()
@@ -97,11 +102,7 @@ public class ChunkGenWorker implements IWorker
     }
 
     @Override
-    public void work()
-    {
-        BlockPos next = queue.poll();
-
-        if (next != null)
+    public boolean doWork()
     {
         WorldServer world = DimensionManager.getWorld(dim);
         if (world == null)
@@ -112,19 +113,37 @@ public class ChunkGenWorker implements IWorker
             {
                 listener.sendMessage(TextComponentHelper.createComponentTranslation(listener, "commands.forge.gen.dim_fail", dim));
                 queue.clear();
-                    return;
+                return false;
             }
         }
+
+        AnvilChunkLoader loader = world.getChunkProvider().chunkLoader instanceof AnvilChunkLoader ? (AnvilChunkLoader)world.getChunkProvider().chunkLoader : null;
+        if (loader != null && loader.getPendingSaveCount() > 100)
+        {
+
+            if (lastNotifcationTime < System.currentTimeMillis() - 10*1000)
+            {
+                listener.sendMessage(TextComponentHelper.createComponentTranslation(listener, "commands.forge.gen.progress", total - queue.size(), total));
+                lastNotifcationTime = System.currentTimeMillis();
+            }
+            return false;
+        }
+
+        BlockPos next = queue.poll();
+
+        if (next != null)
+        {
             // While we work we don't want to cause world load spam so pause unloading the world.
             if (keepingLoaded == null)
             {
                 keepingLoaded = DimensionManager.keepDimensionLoaded(dim, true);
             }
 
-            if (++lastNotification >= notificationFrequency)
+            if (++lastNotification >= notificationFrequency || lastNotifcationTime < System.currentTimeMillis() - 60*1000)
             {
                 listener.sendMessage(TextComponentHelper.createComponentTranslation(listener, "commands.forge.gen.progress", total - queue.size(), total));
                 lastNotification = 0;
+                lastNotifcationTime = System.currentTimeMillis();
             }
 
             int x = next.getX();
@@ -144,6 +163,14 @@ public class ChunkGenWorker implements IWorker
                     world.getChunkFromChunkCoords(x + 1, z + 1),
                     world.getChunkFromChunkCoords(x,     z + 1),
                 };
+                try
+                {
+                    world.getChunkProvider().chunkLoader.saveChunk(world, target);
+                }
+                catch (IOException | MinecraftException e)
+                {
+                    listener.sendMessage(TextComponentHelper.createComponentTranslation(listener, "commands.forge.gen.saveerror", e.getMessage()));
+                }
                 genned++;
             }
 
@@ -162,6 +189,8 @@ public class ChunkGenWorker implements IWorker
             {
                 DimensionManager.keepDimensionLoaded(dim, false);
             }
+            return false;
         }
+        return true;
     }
 }