Add getWorldUUID to SaveChunkEvent.

src/main/java/org/spongepowered/common/mixin/core/world/chunk/storage/AnvilChunkLoaderMixin.java

@@ -33,6 +33,7 @@
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.math.ChunkPos;
 import net.minecraft.world.World;
+import net.minecraft.world.chunk.Chunk;
 import net.minecraft.world.chunk.storage.AnvilChunkLoader;
 import net.minecraft.world.chunk.storage.RegionFileCache;
 import net.minecraft.world.storage.ThreadedFileIOBase;
@@ -59,6 +60,7 @@
 import org.spongepowered.asm.mixin.injection.callback.LocalCapture;
 import org.spongepowered.common.SpongeImpl;
 import org.spongepowered.common.SpongeImplHooks;
+import org.spongepowered.common.bridge.world.WorldBridge;
 import org.spongepowered.common.bridge.world.chunk.ChunkBridge;
 import org.spongepowered.common.bridge.world.chunk.storage.AnvilChunkLoaderBridge;
 import org.spongepowered.common.entity.PlayerTracker;
@@ -67,12 +69,15 @@
 import org.spongepowered.common.util.Constants;
 import org.spongepowered.common.util.QueuedChunk;
 import org.spongepowered.common.util.VecHelper;
+import org.spongepowered.common.util.WorldChunkPos;
 
 import java.io.File;
 import java.nio.file.Path;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentLinkedQueue;
 
 @Mixin(AnvilChunkLoader.class)
@@ -268,14 +273,14 @@ public boolean writeNextIO() {
                             this.writeChunkData(chunkpos, nbttagcompound);
                             laste = null;
                             break;
-                        } catch (Exception exception) {
+                        } catch (final Exception exception) {
                             // LOGGER.error((String)"Failed to save chunk",
                             // (Throwable)exception);
                             laste = exception;
                         }
                         try {
                             Thread.sleep(10);
-                        } catch (InterruptedException e) {
+                        } catch (final InterruptedException e) {
                             e.printStackTrace();
                         }
                     }
@@ -305,11 +310,24 @@ public boolean writeNextIO() {
         return this.chunkSaveLocation.toPath();
     }
 
+    @Redirect(method = "saveChunk", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/chunk/storage/AnvilChunkLoader.addChunkToPending"
+            + "(Lnet/minecraft/util/math/ChunkPos;Lnet/minecraft/nbt/NBTTagCompound;)V"))
+    private void impl$useWorldChunkPosWhenQueuing(final AnvilChunkLoader anvilChunkLoader, final ChunkPos pos, final NBTTagCompound compound,
+            final World worldIn, final Chunk chunkIn) {
+        this.addChunkToPending(new WorldChunkPos(((org.spongepowered.api.world.World) worldIn).getUniqueId(), pos.x, pos.z), compound);
+    }
+
     @Inject(method = "writeChunkData", at = @At("RETURN"))
-    private void impl$callSaveChunkEventPost(ChunkPos pos, NBTTagCompound compound, CallbackInfo ci) {
+    private void impl$callSaveChunkEventPost(final ChunkPos pos, final NBTTagCompound compound, final CallbackInfo ci) {
         if (ShouldFire.SAVE_CHUNK_EVENT_POST) {
             final Cause cause = Cause.of(EventContext.empty(), Collections.singleton(SpongeImpl.getServer()));
-            SpongeImpl.postEvent(SpongeEventFactory.createSaveChunkEventPost(cause, VecHelper.toVec3i(pos)));
+            final Optional<UUID> worldUUID;
+            if (pos instanceof WorldChunkPos) {
+                worldUUID = Optional.of(((WorldChunkPos) pos).getWorldUUID());
+            } else {
+                worldUUID = Optional.empty();
+            }
+            SpongeImpl.postEvent(SpongeEventFactory.createSaveChunkEventPost(cause, VecHelper.toVec3i(pos), worldUUID));
         }
     }
 }

src/main/java/org/spongepowered/common/mixin/core/world/gen/ChunkProviderServerMixin.java

@@ -71,6 +71,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.PrintStream;
 import java.util.Iterator;
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 import javax.annotation.Nullable;
@@ -358,7 +359,7 @@ public boolean tick()
         if (ShouldFire.SAVE_CHUNK_EVENT_PRE) {
             final org.spongepowered.api.world.Chunk apiChunk = (org.spongepowered.api.world.Chunk) chunkIn;
             if (SpongeImpl.postEvent(SpongeEventFactory.createSaveChunkEventPre(SpongeImpl.getCauseStackManager().getCurrentCause(),
-                apiChunk.getPosition(), apiChunk))) {
+                apiChunk.getPosition(), Optional.of(apiChunk.getWorld().getUniqueId()), apiChunk))) {
                 ci.cancel();
             }
         }

src/main/java/org/spongepowered/common/util/WorldChunkPos.java

@@ -0,0 +1,45 @@
+/*
+ * This file is part of Sponge, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) SpongePowered <https://www.spongepowered.org>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package org.spongepowered.common.util;
+
+import net.minecraft.util.math.ChunkPos;
+
+import java.util.UUID;
+
+// Used in AnvilChunkLoaderMixin
+public final class WorldChunkPos extends ChunkPos {
+
+    private final UUID uuid;
+
+    public WorldChunkPos(final UUID uuid, final int x, final int z) {
+        super(x, z);
+        this.uuid = uuid;
+    }
+
+    public UUID getWorldUUID() {
+        return this.uuid;
+    }
+
+}