Avoid Unsafe usage where possible (#2403)

worldedit-bukkit/adapters/adapter-1_17_1/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_17_R1_2/PaperweightPlatformAdapter.java

@@ -85,11 +85,7 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
     private static final MethodHandle methodGetVisibleChunk;
 
-    private static final int CHUNKSECTION_BASE;
-    private static final int CHUNKSECTION_SHIFT;
-
     private static final Field fieldLock;
-    private static final long fieldLockOffset;
 
     private static final Field fieldGameEventDispatcherSections;
     private static final MethodHandle methodremoveBlockEntityTicker;
@@ -127,15 +123,12 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             getVisibleChunkIfPresent.setAccessible(true);
             methodGetVisibleChunk = MethodHandles.lookup().unreflect(getVisibleChunkIfPresent);
 
-            Unsafe unsafe = ReflectionUtils.getUnsafe();
             if (!PaperLib.isPaper()) {
-
                 fieldLock = PalettedContainer.class.getDeclaredField(Refraction.pickName("lock", "m"));
-                fieldLockOffset = unsafe.objectFieldOffset(fieldLock);
+                fieldLock.setAccessible(true);
             } else {
                 // in paper, the used methods are synchronized properly
                 fieldLock = null;
-                fieldLockOffset = -1;
             }
 
             fieldGameEventDispatcherSections = LevelChunk.class.getDeclaredField(Refraction.pickName(
@@ -152,13 +145,6 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
             fieldRemove = BlockEntity.class.getDeclaredField(Refraction.pickName("remove", "p"));
             fieldRemove.setAccessible(true);
-
-            CHUNKSECTION_BASE = unsafe.arrayBaseOffset(LevelChunkSection[].class);
-            int scale = unsafe.arrayIndexScale(LevelChunkSection[].class);
-            if ((scale & (scale - 1)) != 0) {
-                throw new Error("data type scale not a power of two");
-            }
-            CHUNKSECTION_SHIFT = 31 - Integer.numberOfLeadingZeros(scale);
         } catch (RuntimeException e) {
             throw e;
         } catch (Throwable rethrow) {
@@ -173,9 +159,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             LevelChunkSection value,
             int layer
     ) {
-        long offset = ((long) layer << CHUNKSECTION_SHIFT) + CHUNKSECTION_BASE;
         if (layer >= 0 && layer < sections.length) {
-            return ReflectionUtils.getUnsafe().compareAndSwapObject(sections, offset, expected, value);
+            return ReflectionUtils.compareAndSet(sections, expected, value, layer);
         }
         return false;
     }
@@ -190,14 +175,13 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
         }
         try {
             synchronized (section) {
-                Unsafe unsafe = ReflectionUtils.getUnsafe();
                 PalettedContainer<net.minecraft.world.level.block.state.BlockState> blocks = section.getStates();
-                Semaphore currentLock = (Semaphore) unsafe.getObject(blocks, fieldLockOffset);
+                Semaphore currentLock = (Semaphore) fieldLock.get(blocks);
                 if (currentLock instanceof DelegateSemaphore delegateSemaphore) {
                     return delegateSemaphore;
                 }
                 DelegateSemaphore newLock = new DelegateSemaphore(1, currentLock);
-                unsafe.putObject(blocks, fieldLockOffset, newLock);
+                fieldLock.set(blocks, newLock);
                 return newLock;
             }
         } catch (Throwable e) {

worldedit-bukkit/adapters/adapter-1_17_1/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_17_R1_2/regen/PaperweightRegen.java

@@ -329,7 +329,7 @@ public class PaperweightRegen extends Regenerator<ChunkAccess, ProtoChunk, Level
             }
         };
 
-        ReflectionUtils.unsafeSet(chunkSourceField, freshWorld, freshChunkProvider);
+        chunkSourceField.set(freshWorld, freshChunkProvider);
         //let's start then
         structureManager = server.getStructureManager();
         threadedLevelLightEngine = freshChunkProvider.getLightEngine();

worldedit-bukkit/adapters/adapter-1_18_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_18_R2/PaperweightPlatformAdapter.java

@@ -92,14 +92,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
     private static final MethodHandle methodGetVisibleChunk;
 
-    private static final int CHUNKSECTION_BASE;
-    private static final int CHUNKSECTION_SHIFT;
-
     private static final Field fieldThreadingDetector;
-    private static final long fieldThreadingDetectorOffset;
-
     private static final Field fieldLock;
-    private static final long fieldLockOffset;
 
     private static final MethodHandle methodRemoveGameEventListener;
     private static final MethodHandle methodremoveTickingBlockEntity;
@@ -136,20 +130,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             getVisibleChunkIfPresent.setAccessible(true);
             methodGetVisibleChunk = MethodHandles.lookup().unreflect(getVisibleChunkIfPresent);
 
-            Unsafe unsafe = ReflectionUtils.getUnsafe();
             if (!PaperLib.isPaper()) {
                 fieldThreadingDetector = PalettedContainer.class.getDeclaredField(Refraction.pickName("threadingDetector", "f"));
-                fieldThreadingDetectorOffset = unsafe.objectFieldOffset(fieldThreadingDetector);
+                fieldThreadingDetector.setAccessible(true);
-
                 fieldLock = ThreadingDetector.class.getDeclaredField(Refraction.pickName("lock", "c"));
-                fieldLockOffset = unsafe.objectFieldOffset(fieldLock);
+                fieldLock.setAccessible(true);
             } else {
                 // in paper, the used methods are synchronized properly
                 fieldThreadingDetector = null;
-                fieldThreadingDetectorOffset = -1;
-
                 fieldLock = null;
-                fieldLockOffset = -1;
             }
 
             Method removeGameEventListener = LevelChunk.class.getDeclaredMethod(
@@ -169,13 +158,6 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
             fieldRemove = BlockEntity.class.getDeclaredField(Refraction.pickName("remove", "p"));
             fieldRemove.setAccessible(true);
-
-            CHUNKSECTION_BASE = unsafe.arrayBaseOffset(LevelChunkSection[].class);
-            int scale = unsafe.arrayIndexScale(LevelChunkSection[].class);
-            if ((scale & (scale - 1)) != 0) {
-                throw new Error("data type scale not a power of two");
-            }
-            CHUNKSECTION_SHIFT = 31 - Integer.numberOfLeadingZeros(scale);
         } catch (RuntimeException e) {
             throw e;
         } catch (Throwable rethrow) {
@@ -190,9 +172,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             LevelChunkSection value,
             int layer
     ) {
-        long offset = ((long) layer << CHUNKSECTION_SHIFT) + CHUNKSECTION_BASE;
         if (layer >= 0 && layer < sections.length) {
-            return ReflectionUtils.getUnsafe().compareAndSwapObject(sections, offset, expected, value);
+            return ReflectionUtils.compareAndSet(sections, expected, value, layer);
         }
         return false;
     }
@@ -207,19 +188,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
         }
         try {
             synchronized (section) {
-                Unsafe unsafe = ReflectionUtils.getUnsafe();
                 PalettedContainer<net.minecraft.world.level.block.state.BlockState> blocks = section.getStates();
-                ThreadingDetector currentThreadingDetector = (ThreadingDetector) unsafe.getObject(
+                ThreadingDetector currentThreadingDetector = (ThreadingDetector) fieldThreadingDetector.get(blocks);
-                        blocks,
-                        fieldThreadingDetectorOffset
-                );
                 synchronized (currentThreadingDetector) {
-                    Semaphore currentLock = (Semaphore) unsafe.getObject(currentThreadingDetector, fieldLockOffset);
+                    Semaphore currentLock = (Semaphore) fieldLock.get(currentThreadingDetector);
                     if (currentLock instanceof DelegateSemaphore delegateSemaphore) {
                         return delegateSemaphore;
                     }
                     DelegateSemaphore newLock = new DelegateSemaphore(1, currentLock);
-                    unsafe.putObject(currentThreadingDetector, fieldLockOffset, newLock);
+                    fieldLock.set(currentThreadingDetector, newLock);
                     return newLock;
                 }
             }

worldedit-bukkit/adapters/adapter-1_18_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_18_R2/regen/PaperweightRegen.java

@@ -342,7 +342,7 @@ public class PaperweightRegen extends Regenerator<ChunkAccess, ProtoChunk, Level
             }
         };
 
-        ReflectionUtils.unsafeSet(chunkSourceField, freshWorld, freshChunkProvider);
+        chunkSourceField.set(freshWorld, freshChunkProvider);
         //let's start then
         structureManager = server.getStructureManager();
         threadedLevelLightEngine = freshChunkProvider.getLightEngine();

worldedit-bukkit/adapters/adapter-1_19_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_19_R3/PaperweightPlatformAdapter.java

@@ -99,14 +99,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
     private static final MethodHandle methodGetVisibleChunk;
 
-    private static final int CHUNKSECTION_BASE;
-    private static final int CHUNKSECTION_SHIFT;
-
     private static final Field fieldThreadingDetector;
-    private static final long fieldThreadingDetectorOffset;
-
     private static final Field fieldLock;
-    private static final long fieldLockOffset;
 
     private static final MethodHandle methodRemoveGameEventListener;
     private static final MethodHandle methodremoveTickingBlockEntity;
@@ -149,20 +143,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             getVisibleChunkIfPresent.setAccessible(true);
             methodGetVisibleChunk = lookup.unreflect(getVisibleChunkIfPresent);
 
-            Unsafe unsafe = ReflectionUtils.getUnsafe();
             if (!PaperLib.isPaper()) {
                 fieldThreadingDetector = PalettedContainer.class.getDeclaredField(Refraction.pickName("threadingDetector", "f"));
-                fieldThreadingDetectorOffset = unsafe.objectFieldOffset(fieldThreadingDetector);
+                fieldThreadingDetector.setAccessible(true);
-
                 fieldLock = ThreadingDetector.class.getDeclaredField(Refraction.pickName("lock", "c"));
-                fieldLockOffset = unsafe.objectFieldOffset(fieldLock);
+                fieldLock.setAccessible(true);
             } else {
                 // in paper, the used methods are synchronized properly
                 fieldThreadingDetector = null;
-                fieldThreadingDetectorOffset = -1;
-
                 fieldLock = null;
-                fieldLockOffset = -1;
             }
 
             Method removeGameEventListener = LevelChunk.class.getDeclaredMethod(
@@ -185,12 +174,6 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             fieldRemove = BlockEntity.class.getDeclaredField(Refraction.pickName("remove", "q"));
             fieldRemove.setAccessible(true);
 
-            CHUNKSECTION_BASE = unsafe.arrayBaseOffset(LevelChunkSection[].class);
-            int scale = unsafe.arrayIndexScale(LevelChunkSection[].class);
-            if ((scale & (scale - 1)) != 0) {
-                throw new Error("data type scale not a power of two");
-            }
-            CHUNKSECTION_SHIFT = 31 - Integer.numberOfLeadingZeros(scale);
             boolean chunkRewrite;
             try {
                 ServerLevel.class.getDeclaredMethod("getEntityLookup");
@@ -226,9 +209,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             LevelChunkSection value,
             int layer
     ) {
-        long offset = ((long) layer << CHUNKSECTION_SHIFT) + CHUNKSECTION_BASE;
         if (layer >= 0 && layer < sections.length) {
-            return ReflectionUtils.getUnsafe().compareAndSwapObject(sections, offset, expected, value);
+            return ReflectionUtils.compareAndSet(sections, expected, value, layer);
         }
         return false;
     }
@@ -243,19 +225,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
         }
         try {
             synchronized (section) {
-                Unsafe unsafe = ReflectionUtils.getUnsafe();
                 PalettedContainer<net.minecraft.world.level.block.state.BlockState> blocks = section.getStates();
-                ThreadingDetector currentThreadingDetector = (ThreadingDetector) unsafe.getObject(
+                ThreadingDetector currentThreadingDetector = (ThreadingDetector) fieldThreadingDetector.get(blocks);
-                        blocks,
-                        fieldThreadingDetectorOffset
-                );
                 synchronized (currentThreadingDetector) {
-                    Semaphore currentLock = (Semaphore) unsafe.getObject(currentThreadingDetector, fieldLockOffset);
+                    Semaphore currentLock = (Semaphore) fieldLock.get(currentThreadingDetector);
                     if (currentLock instanceof DelegateSemaphore delegateSemaphore) {
                         return delegateSemaphore;
                     }
                     DelegateSemaphore newLock = new DelegateSemaphore(1, currentLock);
-                    unsafe.putObject(currentThreadingDetector, fieldLockOffset, newLock);
+                    fieldLock.set(currentThreadingDetector, newLock);
                     return newLock;
                 }
             }

worldedit-bukkit/adapters/adapter-1_19_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_19_R3/regen/PaperweightRegen.java

@@ -369,7 +369,7 @@ public class PaperweightRegen extends Regenerator<ChunkAccess, ProtoChunk, Level
         }
 
 
-        ReflectionUtils.unsafeSet(chunkSourceField, freshWorld, freshChunkProvider);
+        chunkSourceField.set(freshWorld, freshChunkProvider);
         //let's start then
         structureTemplateManager = server.getStructureManager();
         threadedLevelLightEngine = new NoOpLightEngine(freshChunkProvider);

worldedit-bukkit/adapters/adapter-1_20/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R1/PaperweightPlatformAdapter.java

@@ -102,14 +102,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
 
     private static final MethodHandle methodGetVisibleChunk;
 
-    private static final int CHUNKSECTION_BASE;
-    private static final int CHUNKSECTION_SHIFT;
-
     private static final Field fieldThreadingDetector;
-    private static final long fieldThreadingDetectorOffset;
-
     private static final Field fieldLock;
-    private static final long fieldLockOffset;
 
     private static final MethodHandle methodRemoveGameEventListener;
     private static final MethodHandle methodremoveTickingBlockEntity;
@@ -158,20 +152,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             getVisibleChunkIfPresent.setAccessible(true);
             methodGetVisibleChunk = lookup.unreflect(getVisibleChunkIfPresent);
 
-            Unsafe unsafe = ReflectionUtils.getUnsafe();
             if (!PaperLib.isPaper()) {
                 fieldThreadingDetector = PalettedContainer.class.getDeclaredField(Refraction.pickName("threadingDetector", "f"));
-                fieldThreadingDetectorOffset = unsafe.objectFieldOffset(fieldThreadingDetector);
+                fieldThreadingDetector.setAccessible(true);
-
                 fieldLock = ThreadingDetector.class.getDeclaredField(Refraction.pickName("lock", "c"));
-                fieldLockOffset = unsafe.objectFieldOffset(fieldLock);
+                fieldLock.setAccessible(true);
             } else {
                 // in paper, the used methods are synchronized properly
                 fieldThreadingDetector = null;
-                fieldThreadingDetectorOffset = -1;
-
                 fieldLock = null;
-                fieldLockOffset = -1;
             }
 
             Method removeGameEventListener = LevelChunk.class.getDeclaredMethod(
@@ -194,12 +183,6 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             fieldRemove = BlockEntity.class.getDeclaredField(Refraction.pickName("remove", "q"));
             fieldRemove.setAccessible(true);
 
-            CHUNKSECTION_BASE = unsafe.arrayBaseOffset(LevelChunkSection[].class);
-            int scale = unsafe.arrayIndexScale(LevelChunkSection[].class);
-            if ((scale & (scale - 1)) != 0) {
-                throw new Error("data type scale not a power of two");
-            }
-            CHUNKSECTION_SHIFT = 31 - Integer.numberOfLeadingZeros(scale);
             boolean chunkRewrite;
             try {
                 ServerLevel.class.getDeclaredMethod("getEntityLookup");
@@ -249,9 +232,8 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
             LevelChunkSection value,
             int layer
     ) {
-        long offset = ((long) layer << CHUNKSECTION_SHIFT) + CHUNKSECTION_BASE;
         if (layer >= 0 && layer < sections.length) {
-            return ReflectionUtils.getUnsafe().compareAndSwapObject(sections, offset, expected, value);
+            return ReflectionUtils.compareAndSet(sections, expected, value, layer);
         }
         return false;
     }
@@ -266,19 +248,15 @@ public final class PaperweightPlatformAdapter extends NMSAdapter {
         }
         try {
             synchronized (section) {
-                Unsafe unsafe = ReflectionUtils.getUnsafe();
                 PalettedContainer<net.minecraft.world.level.block.state.BlockState> blocks = section.getStates();
-                ThreadingDetector currentThreadingDetector = (ThreadingDetector) unsafe.getObject(
+                ThreadingDetector currentThreadingDetector = (ThreadingDetector) fieldThreadingDetector.get(blocks);
-                        blocks,
-                        fieldThreadingDetectorOffset
-                );
                 synchronized (currentThreadingDetector) {
-                    Semaphore currentLock = (Semaphore) unsafe.getObject(currentThreadingDetector, fieldLockOffset);
+                    Semaphore currentLock = (Semaphore) fieldLock.get(currentThreadingDetector);
                     if (currentLock instanceof DelegateSemaphore delegateSemaphore) {
                         return delegateSemaphore;
                     }
                     DelegateSemaphore newLock = new DelegateSemaphore(1, currentLock);
-                    unsafe.putObject(currentThreadingDetector, fieldLockOffset, newLock);
+                    fieldLock.set(currentThreadingDetector, newLock);
                     return newLock;
                 }
             }

worldedit-bukkit/adapters/adapter-1_20/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R1/regen/PaperweightRegen.java

@@ -370,7 +370,7 @@ public class PaperweightRegen extends Regenerator<ChunkAccess, ProtoChunk, Level
         }
 
 
-        ReflectionUtils.unsafeSet(chunkSourceField, freshWorld, freshChunkProvider);
+        chunkSourceField.set(freshWorld, freshChunkProvider);
         //let's start then
         structureTemplateManager = server.getStructureManager();
         threadedLevelLightEngine = new NoOpLightEngine(freshChunkProvider);

worldedit-core/src/main/java/com/fastasyncworldedit/core/util/ReflectionUtils.java

@@ -4,19 +4,19 @@ import sun.misc.Unsafe;
 
 import javax.annotation.Nonnull;
 import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
 import java.lang.reflect.AccessibleObject;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
-import java.util.Arrays;
-import java.util.Comparator;
 
 /**
  * This is an internal class not meant to be used outside the FAWE internals.
  */
 public class ReflectionUtils {
 
+    private static final VarHandle REFERENCE_ARRAY_HANDLE = MethodHandles.arrayElementVarHandle(Object[].class);
     private static Unsafe UNSAFE;
 
     static {
@@ -33,6 +33,21 @@ public class ReflectionUtils {
         return t.isInstance(o) ? t.cast(o) : null;
     }
 
+    /**
+     * Performs CAS on the array element at the given index.
+     *
+     * @param array         the array in which to compare and set the value
+     * @param expectedValue the value expected to be at the index
+     * @param newValue      the new value to be set at the index if the expected value matches
+     * @param index         the index at which to compare and set the value
+     * @param <T>           the type of elements in the array
+     * @return true if the value at the index was successfully updated to the new value, false otherwise
+     * @see VarHandle#compareAndSet(Object...)
+     */
+    public static <T> boolean compareAndSet(T[] array, T expectedValue, T newValue, int index) {
+        return REFERENCE_ARRAY_HANDLE.compareAndSet(array, index, expectedValue, newValue);
+    }
+
     public static void setAccessibleNonFinal(Field field) {
         // let's make the field accessible
         field.setAccessible(true);