Char block null check (#1030)

**Add a null-check to CharBlocks FULL section layer-retrieval.**
 - It is possible to trim CharBlocks whilst it is attempting to read data due to the batching of chunks to help reduce memory
 - This is done when the number of chunks sitting loaded in memory with having been "submitted" to the queue for writing to disk becomes high
 - Seconday operations such as heightmap processing and lighting will quickly load chunks, meaning many chunks are submitted early
 - This leads to much higher chances of the chunk being submitted and subsequently trimmed given heightmap and light processing is done layer-by-layer over many chunks, rather than chunk-by-chunk - thus leading to NPEs.
 - By adding synchronisation to and around only the specific sections when loading/updating, and not blocking the whole chunk, many access can still be thread-safe without causing deadlocks
 - This allows removal of lots of the needless and very-slowing synchronisation on get**Block** methods

**Remove much of the synchronisation from ChunkHolder**
 - We shouldn't be synchronising with call() and safety should be added elsewhere. (plus it's making edits very very slow when queue target size is hit)
 - Also remove much of synchronisation because we've added the null-check and section-specific synchronisation to CharBlocks
 
**Some QOL/thread-safe data access changes**
- Replaces the Array#clone seen in the get blocks classes with System#arraycopy as deep cloning is not required, and is also slower than arraycopy
- Add System#arraycopy when accessing chunk section data via history to ensure it is not altered whilst being written
- Renaming EMPTY to empty means it is not implied to be a static variable

Fixes https://github.com/IntellectualSites/FastAsyncWorldEdit/issues/1028
Fixes https://github.com/IntellectualSites/FastAsyncWorldEdit/issues/1025
Fixes https://github.com/IntellectualSites/FastAsyncWorldEdit/issues/1089
Fixes https://github.com/IntellectualSites/FastAsyncWorldEdit/issues/1091
Fixes https://github.com/IntellectualSites/FastAsyncWorldEdit/issues/1097

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/BukkitGetBlocks_1_15_2.java

@@ -349,17 +349,20 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
         };
     }
 
-    private void updateGet(BukkitGetBlocks_1_15_2 get, Chunk nmsChunk, ChunkSection[] sections, ChunkSection section, char[] arr, int layer) {
+    private void updateGet(BukkitGetBlocks_1_15_2 get, Chunk nmsChunk, ChunkSection[] chunkSections, ChunkSection section, char[] arr, int layer) {
         synchronized (get) {
             if (this.getChunk() != nmsChunk) {
                 this.nmsChunk = nmsChunk;
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
                 this.reset();
             }
             if (this.sections == null) {
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
             }
             if (this.sections[layer] != section) {
+                // Not sure why it's funky, but it's what I did in commit fda7d00747abe97d7891b80ed8bb88d97e1c70d1 and I don't want to touch it >dords
                 this.sections[layer] = new ChunkSection[]{section}.clone()[0];
             }
             this.blocks[layer] = arr;
@@ -421,9 +424,14 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
 
                     bitMask |= 1 << layer;
 
-                    char[] setArr = set.load(layer).clone();
+                    char[] tmp = set.load(layer);
+                    char[] setArr = new char[4096];
+                    System.arraycopy(tmp, 0, setArr, 0, 4096);
                     if (createCopy) {
-                        copy.storeSection(layer, loadPrivately(layer).clone());
+                        char[] tmpLoad = loadPrivately(layer);
+                        char[] copyArr = new char[4096];
+                        System.arraycopy(tmpLoad, 0, copyArr, 0, 4096);
+                        copy.storeSection(layer, copyArr);
                     }
 
                     ChunkSection newSection;
@@ -457,7 +465,7 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
                             } else if (existingSection != getSections(false)[layer]) {
                                 this.sections[layer] = existingSection;
                                 this.reset();
-                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096], true), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
@@ -675,11 +683,13 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
-    private char[] loadPrivately(int layer) {
+    private synchronized char[] loadPrivately(int layer) {
-        if (super.sections[layer].isFull()) {
+        if (super.blocks[layer] != null) {
-            return super.blocks[layer];
+            char[] blocks = new char[4096];
+            System.arraycopy(super.blocks[layer], 0, blocks, 0, 4096);
+            return blocks;
         } else {
-            return BukkitGetBlocks_1_15_2.this.update(layer, null);
+            return BukkitGetBlocks_1_15_2.this.update(layer, null, true);
         }
     }
 
@@ -689,8 +699,8 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public synchronized char[] update(int layer, char[] data) {
+    public synchronized char[] update(int layer, char[] data, boolean aggressive) {
-        ChunkSection section = getSections(true)[layer];
+        ChunkSection section = getSections(aggressive)[layer];
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
@@ -807,15 +817,20 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
 
     public ChunkSection[] getSections(boolean force) {
         if (force && forceLoadSections) {
-            return sections = getChunk().getSections().clone();
+            ChunkSection[] sections = getChunk().getSections();
+            ChunkSection[] copy = new ChunkSection[sections.length];
+            System.arraycopy(sections, 0, copy, 0, sections.length);
+            return copy;
         }
         ChunkSection[] tmp = sections;
         if (tmp == null) {
             synchronized (this) {
                 tmp = sections;
                 if (tmp == null) {
-                    Chunk chunk = getChunk();
+                    ChunkSection[] chunkSections = getChunk().getSections();
-                    sections = tmp = chunk.getSections().clone();
+                    tmp = new ChunkSection[chunkSections.length];
+                    System.arraycopy(chunkSections, 0, tmp, 0, chunkSections.length);
+                    sections = tmp;
                 }
             }
         }

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_1/BukkitGetBlocks_1_16_1.java

@@ -349,17 +349,20 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
         };
     }
 
-    private void updateGet(BukkitGetBlocks_1_16_1 get, Chunk nmsChunk, ChunkSection[] sections, ChunkSection section, char[] arr, int layer) {
+    private void updateGet(BukkitGetBlocks_1_16_1 get, Chunk nmsChunk, ChunkSection[] chunkSections, ChunkSection section, char[] arr, int layer) {
         synchronized (get) {
             if (this.getChunk() != nmsChunk) {
                 this.nmsChunk = nmsChunk;
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
                 this.reset();
             }
             if (this.sections == null) {
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
             }
             if (this.sections[layer] != section) {
+                // Not sure why it's funky, but it's what I did in commit fda7d00747abe97d7891b80ed8bb88d97e1c70d1 and I don't want to touch it >dords
                 this.sections[layer] = new ChunkSection[]{section}.clone()[0];
             }
             this.blocks[layer] = arr;
@@ -421,9 +424,14 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
 
                     bitMask |= 1 << layer;
 
-                    char[] setArr = set.load(layer).clone();
+                    char[] tmp = set.load(layer);
+                    char[] setArr = new char[4096];
+                    System.arraycopy(tmp, 0, setArr, 0, 4096);
                     if (createCopy) {
-                        copy.storeSection(layer, loadPrivately(layer).clone());
+                        char[] tmpLoad = loadPrivately(layer);
+                        char[] copyArr = new char[4096];
+                        System.arraycopy(tmpLoad, 0, copyArr, 0, 4096);
+                        copy.storeSection(layer, copyArr);
                     }
 
                     ChunkSection newSection;
@@ -457,7 +465,7 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
                             } else if (existingSection != getSections(false)[layer]) {
                                 this.sections[layer] = existingSection;
                                 this.reset();
-                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096], true), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
@@ -676,11 +684,13 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
-    private char[] loadPrivately(int layer) {
+    private synchronized char[] loadPrivately(int layer) {
-        if (super.sections[layer].isFull()) {
+        if (super.blocks[layer] != null) {
-            return super.blocks[layer];
+            char[] blocks = new char[4096];
+            System.arraycopy(super.blocks[layer], 0, blocks, 0, 4096);
+            return blocks;
         } else {
-            return BukkitGetBlocks_1_16_1.this.update(layer, null);
+            return BukkitGetBlocks_1_16_1.this.update(layer, null, true);
         }
     }
 
@@ -690,8 +700,8 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public synchronized char[] update(int layer, char[] data) {
+    public synchronized char[] update(int layer, char[] data, boolean aggressive) {
-        ChunkSection section = getSections(true)[layer];
+        ChunkSection section = getSections(aggressive)[layer];
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
@@ -808,15 +818,20 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
 
     public ChunkSection[] getSections(boolean force) {
         if (force && forceLoadSections) {
-            return sections = getChunk().getSections().clone();
+            ChunkSection[] sections = getChunk().getSections();
+            ChunkSection[] copy = new ChunkSection[sections.length];
+            System.arraycopy(sections, 0, copy, 0, sections.length);
+            return copy;
         }
         ChunkSection[] tmp = sections;
         if (tmp == null) {
             synchronized (this) {
                 tmp = sections;
                 if (tmp == null) {
-                    Chunk chunk = getChunk();
+                    ChunkSection[] chunkSections = getChunk().getSections();
-                    sections = tmp = chunk.getSections().clone();
+                    tmp = new ChunkSection[chunkSections.length];
+                    System.arraycopy(chunkSections, 0, tmp, 0, chunkSections.length);
+                    sections = tmp;
                 }
             }
         }

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_2/BukkitGetBlocks_1_16_2.java

@@ -352,17 +352,20 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
         };
     }
 
-    private void updateGet(BukkitGetBlocks_1_16_2 get, Chunk nmsChunk, ChunkSection[] sections, ChunkSection section, char[] arr, int layer) {
+    private void updateGet(BukkitGetBlocks_1_16_2 get, Chunk nmsChunk, ChunkSection[] chunkSections, ChunkSection section, char[] arr, int layer) {
         synchronized (get) {
             if (this.getChunk() != nmsChunk) {
                 this.nmsChunk = nmsChunk;
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
                 this.reset();
             }
             if (this.sections == null) {
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
             }
             if (this.sections[layer] != section) {
+                // Not sure why it's funky, but it's what I did in commit fda7d00747abe97d7891b80ed8bb88d97e1c70d1 and I don't want to touch it >dords
                 this.sections[layer] = new ChunkSection[]{section}.clone()[0];
             }
             this.blocks[layer] = arr;
@@ -424,9 +427,14 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
 
                     bitMask |= 1 << layer;
 
-                    char[] setArr = set.load(layer).clone();
+                    char[] tmp = set.load(layer);
+                    char[] setArr = new char[4096];
+                    System.arraycopy(tmp, 0, setArr, 0, 4096);
                     if (createCopy) {
-                        copy.storeSection(layer, loadPrivately(layer).clone());
+                        char[] tmpLoad = loadPrivately(layer);
+                        char[] copyArr = new char[4096];
+                        System.arraycopy(tmpLoad, 0, copyArr, 0, 4096);
+                        copy.storeSection(layer, copyArr);
                     }
 
                     ChunkSection newSection;
@@ -460,7 +468,7 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
                             } else if (existingSection != getSections(false)[layer]) {
                                 this.sections[layer] = existingSection;
                                 this.reset();
-                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096], true), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
@@ -679,11 +687,13 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
-    private char[] loadPrivately(int layer) {
+    private synchronized char[] loadPrivately(int layer) {
-        if (super.sections[layer].isFull()) {
+        if (super.blocks[layer] != null) {
-            return super.blocks[layer];
+            char[] blocks = new char[4096];
+            System.arraycopy(super.blocks[layer], 0, blocks, 0, 4096);
+            return blocks;
         } else {
-            return BukkitGetBlocks_1_16_2.this.update(layer, null);
+            return BukkitGetBlocks_1_16_2.this.update(layer, null, true);
         }
     }
 
@@ -693,8 +703,8 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public synchronized char[] update(int layer, char[] data) {
+    public synchronized char[] update(int layer, char[] data, boolean aggressive) {
-        ChunkSection section = getSections(true)[layer];
+        ChunkSection section = getSections(aggressive)[layer];
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
@@ -811,15 +821,20 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
 
     public ChunkSection[] getSections(boolean force) {
         if (force && forceLoadSections) {
-            return sections = getChunk().getSections().clone();
+            ChunkSection[] sections = getChunk().getSections();
+            ChunkSection[] copy = new ChunkSection[sections.length];
+            System.arraycopy(sections, 0, copy, 0, sections.length);
+            return copy;
         }
         ChunkSection[] tmp = sections;
         if (tmp == null) {
             synchronized (this) {
                 tmp = sections;
                 if (tmp == null) {
-                    Chunk chunk = getChunk();
+                    ChunkSection[] chunkSections = getChunk().getSections();
-                    sections = tmp = chunk.getSections().clone();
+                    tmp = new ChunkSection[chunkSections.length];
+                    System.arraycopy(chunkSections, 0, tmp, 0, chunkSections.length);
+                    sections = tmp;
                 }
             }
         }

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_5/BukkitGetBlocks_1_16_5.java

@@ -352,17 +352,20 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
         };
     }
 
-    private void updateGet(BukkitGetBlocks_1_16_5 get, Chunk nmsChunk, ChunkSection[] sections, ChunkSection section, char[] arr, int layer) {
+    private void updateGet(BukkitGetBlocks_1_16_5 get, Chunk nmsChunk, ChunkSection[] chunkSections, ChunkSection section, char[] arr, int layer) {
         synchronized (get) {
             if (this.getChunk() != nmsChunk) {
                 this.nmsChunk = nmsChunk;
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
                 this.reset();
             }
             if (this.sections == null) {
-                this.sections = sections.clone();
+                this.sections = new ChunkSection[chunkSections.length];
+                System.arraycopy(chunkSections, 0, this.sections, 0, chunkSections.length);
             }
             if (this.sections[layer] != section) {
+                // Not sure why it's funky, but it's what I did in commit fda7d00747abe97d7891b80ed8bb88d97e1c70d1 and I don't want to touch it >dords
                 this.sections[layer] = new ChunkSection[]{section}.clone()[0];
             }
             this.blocks[layer] = arr;
@@ -424,9 +427,14 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
 
                     bitMask |= 1 << layer;
 
-                    char[] setArr = set.load(layer).clone();
+                    char[] tmp = set.load(layer);
+                    char[] setArr = new char[4096];
+                    System.arraycopy(tmp, 0, setArr, 0, 4096);
                     if (createCopy) {
-                        copy.storeSection(layer, loadPrivately(layer).clone());
+                        char[] tmpLoad = loadPrivately(layer);
+                        char[] copyArr = new char[4096];
+                        System.arraycopy(tmpLoad, 0, copyArr, 0, 4096);
+                        copy.storeSection(layer, copyArr);
                     }
 
                     ChunkSection newSection;
@@ -460,7 +468,7 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
                             } else if (existingSection != getSections(false)[layer]) {
                                 this.sections[layer] = existingSection;
                                 this.reset();
-                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096], true), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
@@ -679,11 +687,13 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
-    private char[] loadPrivately(int layer) {
+    private synchronized char[] loadPrivately(int layer) {
-        if (super.sections[layer].isFull()) {
+        if (super.blocks[layer] != null) {
-            return super.blocks[layer];
+            char[] blocks = new char[4096];
+            System.arraycopy(super.blocks[layer], 0, blocks, 0, 4096);
+            return blocks;
         } else {
-            return BukkitGetBlocks_1_16_5.this.update(layer, null);
+            return BukkitGetBlocks_1_16_5.this.update(layer, null, false);
         }
     }
 
@@ -693,8 +703,8 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public synchronized char[] update(int layer, char[] data) {
+    public synchronized char[] update(int layer, char[] data, boolean aggressive) {
-        ChunkSection section = getSections(true)[layer];
+        ChunkSection section = getSections(aggressive)[layer];
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
@@ -811,15 +821,20 @@ public class BukkitGetBlocks_1_16_5 extends CharGetBlocks implements BukkitGetBl
 
     public ChunkSection[] getSections(boolean force) {
         if (force && forceLoadSections) {
-            return sections = getChunk().getSections().clone();
+            ChunkSection[] sections = getChunk().getSections();
+            ChunkSection[] copy = new ChunkSection[sections.length];
+            System.arraycopy(sections, 0, copy, 0, sections.length);
+            return copy;
         }
         ChunkSection[] tmp = sections;
         if (tmp == null) {
             synchronized (this) {
                 tmp = sections;
                 if (tmp == null) {
-                    Chunk chunk = getChunk();
+                    ChunkSection[] chunkSections = getChunk().getSections();
-                    sections = tmp = chunk.getSections().clone();
+                    tmp = new ChunkSection[chunkSections.length];
+                    System.arraycopy(chunkSections, 0, tmp, 0, chunkSections.length);
+                    sections = tmp;
                 }
             }
         }

worldedit-core/src/main/java/com/boydti/fawe/beta/implementation/blocks/CharBlocks.java

@@ -19,22 +19,34 @@ public abstract class CharBlocks implements IBlocks {
             return blocks.blocks[layer];
         }
 
+        // Ignore aggressive switch here.
+        @Override
+        public char[] get(CharBlocks blocks, @Range(from = 0, to = 15) int layer, boolean aggressive) {
+            return blocks.blocks[layer];
+        }
+
         @Override
         public final boolean isFull() {
             return true;
         }
     };
-    protected final Section EMPTY = new Section() {
+    protected final Section empty = new Section() {
         @Override
         public final synchronized char[] get(CharBlocks blocks, int layer) {
+            // Defaults to aggressive as it should only be avoided where we know we've reset a chunk during an edit
+            return get(blocks, layer, true);
+        }
+
+        @Override
+        public synchronized char[] get(CharBlocks blocks, @Range(from = 0, to = 15) int layer, boolean aggressive) {
             char[] arr = blocks.blocks[layer];
             if (arr == null) {
-                arr = blocks.blocks[layer] = blocks.update(layer, null);
+                arr = blocks.blocks[layer] = blocks.update(layer, null, aggressive);
                 if (arr == null) {
                     throw new IllegalStateException("Array cannot be null: " + blocks.getClass());
                 }
             } else {
-                blocks.blocks[layer] = blocks.update(layer, arr);
+                blocks.blocks[layer] = blocks.update(layer, arr, aggressive);
                 if (blocks.blocks[layer] == null) {
                     throw new IllegalStateException("Array cannot be null (update): " + blocks.getClass());
                 }
@@ -57,7 +69,7 @@ public abstract class CharBlocks implements IBlocks {
         blocks = new char[16][];
         sections = new Section[16];
         for (int i = 0; i < 16; i++) {
-            sections[i] = EMPTY;
+            sections[i] = empty;
         }
     }
 
@@ -88,16 +100,16 @@ public abstract class CharBlocks implements IBlocks {
     @Override
     public synchronized IChunkSet reset() {
         for (int i = 0; i < 16; i++) {
-            sections[i] = EMPTY;
+            sections[i] = empty;
         }
         return null;
     }
 
     public synchronized void reset(@Range(from = 0, to = 15) int layer) {
-        sections[layer] = EMPTY;
+        sections[layer] = empty;
     }
 
-    public synchronized char[] update(int layer, char[] data) {
+    public synchronized char[] update(int layer, char[] data, boolean aggressive) {
         if (data == null) {
             return new char[4096];
         }
@@ -114,16 +126,18 @@ public abstract class CharBlocks implements IBlocks {
     }
 
     @Override
-    public synchronized char[] load(@Range(from = 0, to = 15) int layer) {
+    public char[] load(@Range(from = 0, to = 15) int layer) {
-        return sections[layer].get(this, layer);
+        synchronized (sections[layer]) {
+            return sections[layer].get(this, layer);
+        }
     }
 
     @Override
-    public synchronized BlockState getBlock(int x, int y, int z) {
+    public BlockState getBlock(int x, int y, int z) {
         return BlockTypesCache.states[get(x, y, z)];
     }
 
-    public synchronized char get(int x, @Range(from = 0, to = 255) int y, int z) {
+    public char get(int x, @Range(from = 0, to = 255) int y, int z) {
         final int layer = y >> 4;
         final int index = (y & 15) << 8 | z << 4 | x;
         if (layer >= sections.length || layer < 0) {
@@ -149,7 +163,7 @@ public abstract class CharBlocks implements IBlocks {
         Section
      */
 
-    public synchronized final char get(@Range(from = 0, to = 15) int layer, int index) {
+    public final char get(@Range(from = 0, to = 15) int layer, int index) {
         return sections[layer].get(this, layer, index);
     }
 
@@ -161,10 +175,17 @@ public abstract class CharBlocks implements IBlocks {
 
         public abstract char[] get(CharBlocks blocks, @Range(from = 0, to = 15) int layer);
 
+        public abstract char[] get(CharBlocks blocks, @Range(from = 0, to = 15) int layer, boolean aggressive);
+
         public abstract boolean isFull();
 
         public final char get(CharBlocks blocks, @Range(from = 0, to = 15) int layer, int index) {
-            return get(blocks, layer)[index];
+            char[] section = get(blocks, layer);
+            if (section == null) {
+                blocks.reset(layer);
+                section = blocks.empty.get(blocks, layer, false);
+            }
+            return section[index];
         }
 
         public final void set(CharBlocks blocks, @Range(from = 0, to = 15) int layer, int index, char value) {

worldedit-core/src/main/java/com/boydti/fawe/beta/implementation/blocks/CharGetBlocks.java

@@ -19,13 +19,14 @@ public abstract class CharGetBlocks extends CharBlocks implements IChunkGet {
     @Override
     public boolean trim(boolean aggressive) {
         for (int i = 0; i < 16; i++) {
-            sections[i] = EMPTY;
+            sections[i] = empty;
             blocks[i] = null;
         }
         return true;
     }
 
-    public char[] update(int layer, char[] data) {
+    @Override
+    public char[] update(int layer, char[] data, boolean aggressive) {
         if (data == null) {
             data = new char[4096];
         }
@@ -34,8 +35,8 @@ public abstract class CharGetBlocks extends CharBlocks implements IChunkGet {
     }
 
     @Override
-    public boolean trim(boolean aggressive, int layer) {
+    public synchronized boolean trim(boolean aggressive, int layer) {
-        sections[layer] = EMPTY;
+        sections[layer] = empty;
         blocks[layer] = null;
         return true;
     }

worldedit-core/src/main/java/com/boydti/fawe/beta/implementation/blocks/CharSetBlocks.java

@@ -43,7 +43,7 @@ public class CharSetBlocks extends CharBlocks implements IChunkSet {
     }
 
     @Override
-    public void recycle() {
+    public synchronized void recycle() {
         POOL.offer(this);
     }
 
@@ -104,7 +104,7 @@ public class CharSetBlocks extends CharBlocks implements IChunkSet {
     @Override
     public void setBlocks(int layer, char[] data) {
         this.blocks[layer] = data;
-        this.sections[layer] = data == null ? EMPTY : FULL;
+        this.sections[layer] = data == null ? empty : FULL;
     }
 
     @Override

worldedit-core/src/main/java/com/boydti/fawe/beta/implementation/chunk/ChunkHolder.java

@@ -141,7 +141,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     }
 
     @Override
-    public synchronized CompoundTag getEntity(UUID uuid) {
+    public CompoundTag getEntity(UUID uuid) {
         return delegate.get(this).getEntity(uuid);
     }
 
@@ -156,21 +156,21 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     }
 
     @Override
-    public synchronized void setLightingToGet(char[][] lighting) {
+    public void setLightingToGet(char[][] lighting) {
         delegate.setLightingToGet(this, lighting);
     }
 
     @Override
-    public synchronized void setSkyLightingToGet(char[][] lighting) {
+    public void setSkyLightingToGet(char[][] lighting) {
         delegate.setSkyLightingToGet(this, lighting);
     }
 
     @Override
-    public synchronized void setHeightmapToGet(HeightMapType type, int[] data) {
+    public void setHeightmapToGet(HeightMapType type, int[] data) {
         delegate.setHeightmapToGet(this, type, data);
     }
 
-    public synchronized void flushLightToGet(boolean heightmaps) {
+    public void flushLightToGet(boolean heightmaps) {
         delegate.flushLightToGet(this, heightmaps);
     }
 
@@ -800,22 +800,22 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     };
 
     @Override
-    public synchronized Map<BlockVector3, CompoundTag> getTiles() {
+    public Map<BlockVector3, CompoundTag> getTiles() {
         return delegate.get(this).getTiles();
     }
 
     @Override
-    public synchronized Set<CompoundTag> getEntities() {
+    public Set<CompoundTag> getEntities() {
         return delegate.get(this).getEntities();
     }
 
     @Override
-    public synchronized boolean hasSection(int layer) {
+    public boolean hasSection(int layer) {
         return chunkExisting != null && chunkExisting.hasSection(layer);
     }
 
     @Override
-    public synchronized void filterBlocks(Filter filter, ChunkFilterBlock block, @Nullable Region region, boolean full) {
+    public void filterBlocks(Filter filter, ChunkFilterBlock block, @Nullable Region region, boolean full) {
         final IChunkGet get = getOrCreateGet();
         final IChunkSet set = getOrCreateSet();
         set.setFastMode(fastmode);
@@ -863,7 +863,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     /**
      * Get or create the existing part of this chunk.
      */
-    public synchronized final IChunkGet getOrCreateGet() {
+    public final IChunkGet getOrCreateGet() {
         if (chunkExisting == null) {
             chunkExisting = newWrappedGet();
         }
@@ -873,7 +873,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     /**
      * Get or create the settable part of this chunk.
      */
-    public synchronized final IChunkSet getOrCreateSet() {
+    public final IChunkSet getOrCreateSet() {
         if (chunkSet == null) {
             chunkSet = newWrappedSet();
         }
@@ -885,7 +885,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
      *  - The purpose of wrapping is to allow different extents to intercept / alter behavior
      *  - e.g., caching, optimizations, filtering
      */
-    private synchronized IChunkSet newWrappedSet() {
+    private IChunkSet newWrappedSet() {
         return extent.getCachedSet(chunkX, chunkZ);
     }
 
@@ -917,11 +917,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     public synchronized T call() {
         if (chunkSet != null) {
             chunkSet.setBitMask(bitMask);
-            return this.call(chunkSet, () -> {
+            return this.call(chunkSet, this::recycle);
-                synchronized (this) {
-                    this.recycle();
-                }
-            });
         }
         return null;
     }
@@ -963,82 +959,82 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     }
 
     @Override
-    public synchronized boolean setBiome(int x, int y, int z, BiomeType biome) {
+    public boolean setBiome(int x, int y, int z, BiomeType biome) {
         return delegate.setBiome(this, x, y, z, biome);
     }
 
     @Override
-    public synchronized <B extends BlockStateHolder<B>> boolean setBlock(int x, int y, int z, B block) {
+    public <B extends BlockStateHolder<B>> boolean setBlock(int x, int y, int z, B block) {
         return delegate.setBlock(this, x, y, z, block);
     }
 
     @Override
-    public synchronized BiomeType getBiomeType(int x, int y, int z) {
+    public BiomeType getBiomeType(int x, int y, int z) {
         return delegate.getBiome(this, x, y, z);
     }
 
     @Override
-    public synchronized BlockState getBlock(int x, int y, int z) {
+    public BlockState getBlock(int x, int y, int z) {
         return delegate.getBlock(this, x, y, z);
     }
 
     @Override
-    public synchronized BaseBlock getFullBlock(int x, int y, int z) {
+    public BaseBlock getFullBlock(int x, int y, int z) {
         return delegate.getFullBlock(this, x, y, z);
     }
 
     @Override
-    public synchronized void setSkyLight(int x, int y, int z, int value) {
+    public void setSkyLight(int x, int y, int z, int value) {
         delegate.setSkyLight(this, x, y, z, value);
     }
 
     @Override
-    public synchronized void setHeightMap(HeightMapType type, int[] heightMap) {
+    public void setHeightMap(HeightMapType type, int[] heightMap) {
         delegate.setHeightMap(this, type, heightMap);
     }
 
     @Override
-    public synchronized void removeSectionLighting(int layer, boolean sky) {
+    public void removeSectionLighting(int layer, boolean sky) {
         delegate.removeSectionLighting(this, layer, sky);
     }
 
     @Override
-    public synchronized void setFullBright(int layer) {
+    public void setFullBright(int layer) {
         delegate.setFullBright(this, layer);
     }
 
     @Override
-    public synchronized void setBlockLight(int x, int y, int z, int value) {
+    public void setBlockLight(int x, int y, int z, int value) {
         delegate.setBlockLight(this, x, y, z, value);
     }
 
     @Override
-    public synchronized void setLightLayer(int layer, char[] toSet) {
+    public void setLightLayer(int layer, char[] toSet) {
         delegate.setLightLayer(this, layer, toSet);
     }
 
     @Override
-    public synchronized void setSkyLightLayer(int layer, char[] toSet) {
+    public void setSkyLightLayer(int layer, char[] toSet) {
         delegate.setSkyLightLayer(this, layer, toSet);
     }
 
     @Override
-    public synchronized int getSkyLight(int x, int y, int z) {
+    public int getSkyLight(int x, int y, int z) {
         return delegate.getSkyLight(this, x, y, z);
     }
 
     @Override
-    public synchronized int getEmmittedLight(int x, int y, int z) {
+    public int getEmmittedLight(int x, int y, int z) {
         return delegate.getEmmittedLight(this, x, y, z);
     }
 
     @Override
-    public synchronized int getBrightness(int x, int y, int z) {
+    public int getBrightness(int x, int y, int z) {
         return delegate.getBrightness(this, x, y, z);
     }
 
     @Override
-    public synchronized int getOpacity(int x, int y, int z) {
+    public int getOpacity(int x, int y, int z) {
         return delegate.getOpacity(this, x, y, z);
     }
 

worldedit-core/src/main/java/com/boydti/fawe/object/changeset/AbstractChangeSet.java

@@ -162,11 +162,15 @@ public abstract class AbstractChangeSet implements ChangeSet, IBatchProcessor {
                 continue;
             }
             // add each block and tile
-            char[] blocksGet = get.load(layer);
+            char[] blocksGet;
-            if (blocksGet == null) {
+            char[] tmp = get.load(layer);
+            if (tmp == null) {
                 blocksGet = FaweCache.IMP.EMPTY_CHAR_4096;
+            } else {
+                System.arraycopy(tmp, 0, (blocksGet = new char[4096]), 0, 4096);
             }
-            char[] blocksSet = set.load(layer);
+            char[] blocksSet;
+            System.arraycopy(set.load(layer), 0, (blocksSet = new char[4096]), 0, 4096);
 
             int by = layer << 4;
             for (int y = 0, index = 0; y < 16; y++) {