worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/ExpressionPattern.java

@@ -1,6 +1,7 @@
 package com.fastasyncworldedit.core.function.pattern;
 
 import com.sk89q.worldedit.function.pattern.AbstractPattern;
+import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.internal.expression.EvaluationException;
 import com.sk89q.worldedit.internal.expression.Expression;
 import com.sk89q.worldedit.internal.expression.ExpressionException;
@@ -57,4 +58,9 @@ public class ExpressionPattern extends AbstractPattern {
         }
     }
 
+    @Override
+    public Pattern fork() {
+        return new ExpressionPattern(this.expression.clone());
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/Linear2DBlockPattern.java

@@ -7,6 +7,8 @@ import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.block.BaseBlock;
 
+import java.util.Arrays;
+
 import static java.lang.Math.floorDiv;
 
 /**
@@ -52,4 +54,10 @@ public class Linear2DBlockPattern extends AbstractPattern {
         return patternsArray[index].apply(extent, get, set);
     }
 
+    @Override
+    public Pattern fork() {
+        final Pattern[] forked = Arrays.stream(this.patternsArray).map(Pattern::fork).toArray(Pattern[]::new);
+        return new Linear2DBlockPattern(forked, this.xScale, this.zScale);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/Linear3DBlockPattern.java

@@ -7,6 +7,8 @@ import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.block.BaseBlock;
 
+import java.util.Arrays;
+
 import static java.lang.Math.floorDiv;
 
 /**
@@ -56,4 +58,10 @@ public class Linear3DBlockPattern extends AbstractPattern {
         return patternsArray[index].apply(extent, get, set);
     }
 
+    @Override
+    public Pattern fork() {
+        final Pattern[] forked = Arrays.stream(this.patternsArray).map(Pattern::fork).toArray(Pattern[]::new);
+        return new Linear3DBlockPattern(forked, this.xScale, this.yScale, this.zScale);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/LinearBlockPattern.java

@@ -47,4 +47,10 @@ public class LinearBlockPattern extends AbstractPattern implements ResettablePat
         index = 0;
     }
 
+    @Override
+    public Pattern fork() {
+        final Pattern[] forked = Arrays.stream(this.patternsArray).map(Pattern::fork).toArray(Pattern[]::new);
+        return new LinearBlockPattern(forked);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/MaskedPattern.java

@@ -43,4 +43,9 @@ public class MaskedPattern extends AbstractPattern {
         return secondary.apply(extent, get, set);
     }
 
+    @Override
+    public Pattern fork() {
+        return new MaskedPattern(this.mask.copy(), this.primary.fork(), this.secondary.fork());
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/NoXPattern.java

@@ -36,4 +36,9 @@ public class NoXPattern extends AbstractPattern {
         return pattern.apply(extent, mutable, set);
     }
 
+    @Override
+    public Pattern fork() {
+        return new NoXPattern(this.pattern.fork());
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/NoYPattern.java

@@ -36,4 +36,9 @@ public class NoYPattern extends AbstractPattern {
         return pattern.apply(extent, mutable, set);
     }
 
+    @Override
+    public Pattern fork() {
+        return new NoYPattern(this.pattern.fork());
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/NoZPattern.java

@@ -1,6 +1,7 @@
 package com.fastasyncworldedit.core.function.pattern;
 
 import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.fastasyncworldedit.core.queue.Filter;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.function.pattern.AbstractPattern;
@@ -36,4 +37,9 @@ public class NoZPattern extends AbstractPattern {
         return pattern.apply(extent, mutable, set);
     }
 
+    @Override
+    public Pattern fork() {
+        return new NoZPattern(this.pattern.fork());
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/OffsetPattern.java

@@ -60,4 +60,9 @@ public class OffsetPattern extends AbstractPattern {
         return pattern.apply(extent, get, mutable);
     }
 
+    @Override
+    public Pattern fork() {
+        return new OffsetPattern(this.pattern.fork(), this.dx, this.dy, this.dz, this.minY, this.maxY);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/RandomOffsetPattern.java

@@ -72,4 +72,9 @@ public class RandomOffsetPattern extends AbstractPattern {
         return pattern.apply(extent, get, mutable);
     }
 
+    @Override
+    public Pattern fork() {
+        return new RandomOffsetPattern(this.pattern.fork(), this.dx, this.dy, this.dz, this.minY, this.maxY);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/RelativePattern.java

@@ -63,4 +63,11 @@ public class RelativePattern extends AbstractPattern implements ResettablePatter
         origin = null;
     }
 
+    @Override
+    public Pattern fork() {
+        RelativePattern forked = new RelativePattern(this.pattern.fork(), this.minY, this.maxY);
+        forked.origin = this.origin; // maintain origin for forks
+        return forked;
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/SolidRandomOffsetPattern.java

@@ -94,4 +94,9 @@ public class SolidRandomOffsetPattern extends AbstractPattern {
         return pattern.apply(extent, get, set);
     }
 
+    @Override
+    public Pattern fork() {
+        return new SolidRandomOffsetPattern(this.pattern.fork(), this.dx, this.dy, this.dz, this.minY, this.maxY);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/SurfaceRandomOffsetPattern.java

@@ -129,4 +129,9 @@ public class SurfaceRandomOffsetPattern extends AbstractPattern {
         return !block.getBlockType().getMaterial().isMovementBlocker();
     }
 
+    @Override
+    public Pattern fork() {
+        return new SurfaceRandomOffsetPattern(this.pattern.fork(), this.moves, this.minY, this.maxY);
+    }
+
 }

worldedit-core/src/main/java/com/sk89q/worldedit/extent/buffer/ForgetfulExtentBuffer.java

@@ -235,4 +235,11 @@ public class ForgetfulExtentBuffer extends AbstractDelegateExtent implements Pat
         };
     }
 
+    //FAWE - stateful pattern
+    @Override
+    public Pattern fork() {
+        return new ForgetfulExtentBuffer(extent, mask.copy());
+    }
+    //FAWE end
+
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/pattern/ExtentBufferedCompositePattern.java

@@ -25,6 +25,8 @@ import com.sk89q.worldedit.extent.buffer.ExtentBuffer;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.block.BaseBlock;
 
+import java.util.Arrays;
+
 import static com.google.common.base.Preconditions.checkArgument;
 
 /**
@@ -64,4 +66,12 @@ public class ExtentBufferedCompositePattern extends AbstractExtentPattern {
         return lastBlock;
     }
 
+    //FAWE - stateful pattern
+    @Override
+    public Pattern fork() {
+        final Pattern[] forkedPatterns = Arrays.stream(patterns).map(Pattern::fork).toArray(Pattern[]::new);
+        return new ExtentBufferedCompositePattern(getExtent(), forkedPatterns);
+    }
+    //FAWE end
+
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/pattern/Pattern.java

@@ -59,6 +59,11 @@ public interface Pattern extends Filter {
         apply(block, block, block);
     }
 
+    @Override
+    default Pattern fork() { // covariant return type
+        return this;
+    }
+
     //FAWE end
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/function/pattern/RandomPattern.java

@@ -67,6 +67,13 @@ public class RandomPattern extends AbstractPattern {
         this.collection = RandomCollection.of(weights, random);
         this.patterns = parent.patterns;
     }
+
+    private RandomPattern(SimpleRandom random, Map<Pattern, Double> weights) {
+        this.random = random;
+        this.weights = weights;
+        this.collection = RandomCollection.of(weights, random);
+        this.patterns = new LinkedHashSet<>(weights.keySet());
+    }
     //FAWE end
 
     /**
@@ -107,6 +114,14 @@ public class RandomPattern extends AbstractPattern {
     public boolean apply(Extent extent, BlockVector3 get, BlockVector3 set) throws WorldEditException {
         return collection.next(get.getBlockX(), get.getBlockY(), get.getBlockZ()).apply(extent, get, set);
     }
+
+    @Override
+    public Pattern fork() {
+        final LinkedHashMap<Pattern, Double> newWeights = new LinkedHashMap<>();
+        this.weights.forEach((p, w) -> newWeights.put(p.fork(), w));
+        return new RandomPattern(this.random, newWeights);
+    }
+
     //FAWE end
 
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/pattern/StateApplyingPattern.java

@@ -29,13 +29,16 @@ import com.sk89q.worldedit.world.block.BlockType;
 
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
 
 import static com.sk89q.worldedit.blocks.Blocks.resolveProperties;
 
 public class StateApplyingPattern extends AbstractExtentPattern {
 
     private final Map<String, String> states;
-    private final Map<BlockType, Map<Property<Object>, Object>> cache = Maps.newHashMap();
+    //FAWE - avoid race conditions
+    private final Map<BlockType, Map<Property<Object>, Object>> cache = new ConcurrentHashMap<>();
+    //FAWE end
 
     public StateApplyingPattern(Extent extent, Map<String, String> statesToSet) {
         super(extent);