fix: make IdMask thread-safe (#2361)

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/mask/IdMask.java

@@ -5,9 +5,11 @@ import com.sk89q.worldedit.function.mask.AbstractExtentMask;
 import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.math.BlockVector3;
 
+import java.util.concurrent.atomic.AtomicInteger;
+
 public class IdMask extends AbstractExtentMask implements ResettableMask {
 
-    private transient int id = -1;
+    private final AtomicInteger id = new AtomicInteger(-1);
 
     public IdMask(Extent extent) {
         super(extent);
@@ -15,12 +17,9 @@ public class IdMask extends AbstractExtentMask implements ResettableMask {
 
     @Override
     public boolean test(Extent extent, BlockVector3 vector) {
-        if (id != -1) {
-            return extent.getBlock(vector).getInternalBlockTypeId() == id;
-        } else {
-            id = extent.getBlock(vector).getInternalBlockTypeId();
-            return true;
-        }
+        int blockID = extent.getBlock(vector).getInternalBlockTypeId();
+        int testId = id.compareAndExchange(-1, blockID);
+        return blockID == testId || testId == -1;
     }
 
     @Override
@@ -30,12 +29,12 @@ public class IdMask extends AbstractExtentMask implements ResettableMask {
 
     @Override
     public void reset() {
-        this.id = -1;
+        this.id.set(-1);
     }
 
     @Override
     public Mask copy() {
-        return new IdMask(getExtent());
+        return this;
     }
 
     @Override