Fix a lot of FAWE-freezing properly

- Add a "loadPrivately" method to be used when GetChunks are called to avoid synchronocity issues with super classes being used on different threads
 - Synchronise the call method so we're not attempting to call whilst also loading/updating

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

@@ -376,7 +376,7 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
+    public synchronized <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
         forceLoadSections = false;
         copy = createCopy ? new BukkitGetBlocks_1_15_2_Copy(world) : null;
         try {
@@ -424,7 +424,7 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
 
                     char[] setArr = set.load(layer).clone();
                     if (createCopy) {
-                        copy.storeSection(layer, load(layer).clone());
+                        copy.storeSection(layer, loadPrivately(layer).clone());
                     }
 
                     ChunkSection newSection;
@@ -458,12 +458,12 @@ 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]), load(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
                             }
-                            newSection = BukkitAdapter_1_15_2.newChunkSection(layer, this::load, setArr, fastmode);
+                            newSection = BukkitAdapter_1_15_2.newChunkSection(layer, this::loadPrivately, setArr, fastmode);
                             if (!BukkitAdapter_1_15_2.setSectionAtomic(sections, existingSection, newSection, layer)) {
                                 log.error("Failed to set chunk section:" + chunkX + "," + chunkZ + " layer: " + layer);
                             } else {
@@ -676,6 +676,14 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
+    private char[] loadPrivately(int layer) {
+        if (super.sections[layer].isFull()) {
+            return super.blocks[layer];
+        } else {
+            return BukkitGetBlocks_1_15_2.this.update(layer, null);
+        }
+    }
+
     @Override
     public synchronized void send(int mask, boolean lighting) {
         BukkitAdapter_1_15_2.sendChunk(world, chunkX, chunkZ, mask, lighting);

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

@@ -376,7 +376,7 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
+    public synchronized <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
         forceLoadSections = false;
         copy = createCopy ? new BukkitGetBlocks_1_16_1_Copy(world) : null;
         try {
@@ -424,7 +424,7 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
 
                     char[] setArr = set.load(layer).clone();
                     if (createCopy) {
-                        copy.storeSection(layer, load(layer).clone());
+                        copy.storeSection(layer, loadPrivately(layer).clone());
                     }
 
                     ChunkSection newSection;
@@ -458,13 +458,13 @@ 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]), load(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
                             }
                             newSection = BukkitAdapter_1_16_1
-                                    .newChunkSection(layer, this::load, setArr, fastmode);
+                                    .newChunkSection(layer, this::loadPrivately, setArr, fastmode);
                             if (!BukkitAdapter_1_16_1
                                     .setSectionAtomic(sections, existingSection, newSection, layer)) {
                                 log.error("Failed to set chunk section:" + chunkX + "," + chunkZ + " layer: " + layer);
@@ -678,6 +678,14 @@ public class BukkitGetBlocks_1_16_1 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
+    private char[] loadPrivately(int layer) {
+        if (super.sections[layer].isFull()) {
+            return super.blocks[layer];
+        } else {
+            return BukkitGetBlocks_1_16_1.this.update(layer, null);
+        }
+    }
+
     @Override
     public synchronized void send(int mask, boolean lighting) {
         BukkitAdapter_1_16_1.sendChunk(world, chunkX, chunkZ, mask, lighting);

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

@@ -379,7 +379,7 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
+    public synchronized <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
         forceLoadSections = false;
         copy = createCopy ? new BukkitGetBlocks_1_16_2_Copy(world) : null;
         try {
@@ -427,7 +427,7 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
 
                     char[] setArr = set.load(layer).clone();
                     if (createCopy) {
-                        copy.storeSection(layer, load(layer).clone());
+                        copy.storeSection(layer, loadPrivately(layer).clone());
                     }
 
                     ChunkSection newSection;
@@ -461,13 +461,13 @@ 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]), load(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
                             }
                             newSection = BukkitAdapter_1_16_2
-                                .newChunkSection(layer, this::load, setArr, fastmode);
+                                .newChunkSection(layer, this::loadPrivately, setArr, fastmode);
                             if (!BukkitAdapter_1_16_2
                                 .setSectionAtomic(sections, existingSection, newSection, layer)) {
                                 log.error("Failed to set chunk section:" + chunkX + "," + chunkZ + " layer: " + layer);
@@ -681,6 +681,14 @@ public class BukkitGetBlocks_1_16_2 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
+    private char[] loadPrivately(int layer) {
+        if (super.sections[layer].isFull()) {
+            return super.blocks[layer];
+        } else {
+            return BukkitGetBlocks_1_16_2.this.update(layer, null);
+        }
+    }
+
     @Override
     public synchronized void send(int mask, boolean lighting) {
         BukkitAdapter_1_16_2.sendChunk(world, chunkX, chunkZ, mask, lighting);

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_16_4/BukkitGetBlocks_1_16_4.java

@@ -379,7 +379,7 @@ public class BukkitGetBlocks_1_16_4 extends CharGetBlocks implements BukkitGetBl
     }
 
     @Override
-    public <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
+    public synchronized <T extends Future<T>> T call(IChunkSet set, Runnable finalizer) {
         forceLoadSections = false;
         copy = createCopy ? new BukkitGetBlocks_1_16_4_Copy(world) : null;
         try {
@@ -427,7 +427,7 @@ public class BukkitGetBlocks_1_16_4 extends CharGetBlocks implements BukkitGetBl
 
                     char[] setArr = set.load(layer).clone();
                     if (createCopy) {
-                        copy.storeSection(layer, load(layer).clone());
+                        copy.storeSection(layer, loadPrivately(layer).clone());
                     }
 
                     ChunkSection newSection;
@@ -461,13 +461,13 @@ public class BukkitGetBlocks_1_16_4 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]), load(layer))) {
+                            } else if (!Arrays.equals(update(layer, new char[4096]), loadPrivately(layer))) {
                                 this.reset(layer);
                             } else if (lock.isModified()) {
                                 this.reset(layer);
                             }
                             newSection = BukkitAdapter_1_16_4
-                                .newChunkSection(layer, this::load, setArr, fastmode);
+                                .newChunkSection(layer, this::loadPrivately, setArr, fastmode);
                             if (!BukkitAdapter_1_16_4
                                 .setSectionAtomic(sections, existingSection, newSection, layer)) {
                                 log.error("Failed to set chunk section:" + chunkX + "," + chunkZ + " layer: " + layer);
@@ -681,6 +681,14 @@ public class BukkitGetBlocks_1_16_4 extends CharGetBlocks implements BukkitGetBl
         }
     }
 
+    private char[] loadPrivately(int layer) {
+        if (super.sections[layer].isFull()) {
+            return super.blocks[layer];
+        } else {
+            return BukkitGetBlocks_1_16_4.this.update(layer, null);
+        }
+    }
+
     @Override
     public synchronized void send(int mask, boolean lighting) {
         BukkitAdapter_1_16_4.sendChunk(world, chunkX, chunkZ, mask, lighting);

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

@@ -9,8 +9,6 @@ import org.jetbrains.annotations.Range;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.concurrent.locks.ReentrantLock;
-
 public abstract class CharBlocks implements IBlocks {
 
     public static final Logger logger = LoggerFactory.getLogger(CharBlocks.class);

worldedit-core/src/main/java/com/boydti/fawe/beta/implementation/queue/SingleThreadQueueExtent.java

@@ -250,19 +250,8 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
             //  - memory is low & queue size > num threads + 8
             //  - queue size > target size and primary queue has less than num threads submissions
             if (enabledQueue && ((lowMem && size > Settings.IMP.QUEUE.PARALLEL_THREADS + 8) || (size > Settings.IMP.QUEUE.TARGET_SIZE && Fawe.get().getQueueHandler().isUnderutilized()))) {
-                int i = 0;
+                chunk = chunks.removeFirst();
-                boolean found = false;
+                final Future future = submitUnchecked(chunk);
-                while (i < chunks.size() && (chunk = chunks.get(i)) != null) {
-                    if (Thread.holdsLock(chunk)) {
-                        found = true;
-                        break;
-                    }
-                    i++;
-                }
-                Future future = null;
-                if (found) {
-                    future = submitUnchecked(chunk);
-                }
                 if (future != null && !future.isDone()) {
                     final int targetSize;
                     if (lowMem) {