From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Wed, 29 May 2019 04:01:22 +0100
Subject: [PATCH] ChunkMapDistance CME


diff --git a/src/main/java/net/minecraft/server/level/ChunkHolder.java b/src/main/java/net/minecraft/server/level/ChunkHolder.java
index 0b8cbf75ff01b9825141be00d63679f7bcc58a9f..89e90806b78d94d5c1d781113da420dafa47930a 100644
--- a/src/main/java/net/minecraft/server/level/ChunkHolder.java
+++ b/src/main/java/net/minecraft/server/level/ChunkHolder.java
@@ -44,6 +44,7 @@ public class ChunkHolder {
     private static final CompletableFuture<Either<LevelChunk, ChunkHolder.ChunkLoadingFailure>> UNLOADED_LEVEL_CHUNK_FUTURE = CompletableFuture.completedFuture(ChunkHolder.UNLOADED_LEVEL_CHUNK);
     private static final List<ChunkStatus> CHUNK_STATUSES = ChunkStatus.getStatusList();
     private static final ChunkHolder.FullChunkStatus[] FULL_CHUNK_STATUSES = ChunkHolder.FullChunkStatus.values();
+    boolean isUpdateQueued = false; // Paper
     private final AtomicReferenceArray<CompletableFuture<Either<ChunkAccess, ChunkHolder.ChunkLoadingFailure>>> futures;
     private volatile CompletableFuture<Either<LevelChunk, ChunkHolder.ChunkLoadingFailure>> fullChunkFuture; private int fullChunkCreateCount; private volatile boolean isFullChunkReady; // Paper - cache chunk ticking stage
     private volatile CompletableFuture<Either<LevelChunk, ChunkHolder.ChunkLoadingFailure>> tickingChunkFuture; private volatile boolean isTickingReady; // Paper - cache chunk ticking stage
diff --git a/src/main/java/net/minecraft/server/level/DistanceManager.java b/src/main/java/net/minecraft/server/level/DistanceManager.java
index 8f993f15ae02c2e4af9cc732cd1b040cce0a67e8..71a51cc99e26579e765f88340588e23956888929 100644
--- a/src/main/java/net/minecraft/server/level/DistanceManager.java
+++ b/src/main/java/net/minecraft/server/level/DistanceManager.java
@@ -39,7 +39,16 @@ public abstract class DistanceManager {
     private final DistanceManager.ChunkTicketTracker ticketTracker = new DistanceManager.ChunkTicketTracker();
     private final DistanceManager.FixedPlayerDistanceChunkTracker naturalSpawnChunkCounter = new DistanceManager.FixedPlayerDistanceChunkTracker(8);
     private final DistanceManager.PlayerTicketTracker playerTicketManager = new DistanceManager.PlayerTicketTracker(33);
-    private final Set<ChunkHolder> chunksToUpdateFutures = Sets.newHashSet();
+    // Paper start use a queue, but still keep unique requirement
+    public final java.util.Queue<ChunkHolder> pendingChunkUpdates = new java.util.ArrayDeque<ChunkHolder>() {
+        @Override
+        public boolean add(ChunkHolder o) {
+            if (o.isUpdateQueued) return true;
+            o.isUpdateQueued = true;
+            return super.add(o);
+        }
+    };
+    // Paper end
     private final ChunkTaskPriorityQueueSorter ticketThrottler;
     private final ProcessorHandle<ChunkTaskPriorityQueueSorter.Message<Runnable>> ticketThrottlerInput;
     private final ProcessorHandle<ChunkTaskPriorityQueueSorter.Release> ticketThrottlerReleaser;
@@ -100,26 +109,14 @@ public abstract class DistanceManager {
             ;
         }
 
-        if (!this.chunksToUpdateFutures.isEmpty()) {
-            // CraftBukkit start
-            // Iterate pending chunk updates with protection against concurrent modification exceptions
-            java.util.Iterator<ChunkHolder> iter = this.chunksToUpdateFutures.iterator();
-            int expectedSize = this.chunksToUpdateFutures.size();
-            do {
-                ChunkHolder playerchunk = iter.next();
-                iter.remove();
-                expectedSize--;
-
-                playerchunk.updateFutures(chunkStorage);
-
-                // Reset iterator if set was modified using add()
-                if (this.chunksToUpdateFutures.size() != expectedSize) {
-                    expectedSize = this.chunksToUpdateFutures.size();
-                    iter = this.chunksToUpdateFutures.iterator();
-                }
-            } while (iter.hasNext());
-            // CraftBukkit end
-
+        // Paper start
+        if (!this.pendingChunkUpdates.isEmpty()) {
+            while(!this.pendingChunkUpdates.isEmpty()) {
+                ChunkHolder remove = this.pendingChunkUpdates.remove();
+                remove.isUpdateQueued = false;
+                remove.updateFutures(chunkStorage);
+            }
+            // Paper end
             return true;
         } else {
             if (!this.ticketsToRelease.isEmpty()) {
@@ -342,7 +339,7 @@ public abstract class DistanceManager {
             if (k != level) {
                 playerchunk = DistanceManager.this.updateChunkScheduling(id, level, playerchunk, k);
                 if (playerchunk != null) {
-                    DistanceManager.this.chunksToUpdateFutures.add(playerchunk);
+                    DistanceManager.this.pendingChunkUpdates.add(playerchunk);
                 }
 
             }
@@ -373,7 +370,7 @@ public abstract class DistanceManager {
             ObjectIterator objectiterator = this.chunks.long2ByteEntrySet().iterator();
 
             while (objectiterator.hasNext()) {
-                it.unimi.dsi.fastutil.longs.Long2ByteMap.Entry it_unimi_dsi_fastutil_longs_long2bytemap_entry = (it.unimi.dsi.fastutil.longs.Long2ByteMap.Entry) objectiterator.next();
+                Long2ByteMap.Entry it_unimi_dsi_fastutil_longs_long2bytemap_entry = (Long2ByteMap.Entry) objectiterator.next(); // Paper - decompile fix
                 byte b0 = it_unimi_dsi_fastutil_longs_long2bytemap_entry.getByteValue();
                 long j = it_unimi_dsi_fastutil_longs_long2bytemap_entry.getLongKey();