Add back statically-set reserved IDs for air blocks only, make it clear they're "reserved" (#1502)

* Add back statically-set reserved IDs for air blocks only, make it clear they're "reserved"
Also:
 - Ensure that reserved is never returned in GET block operations
 - "empty" thus doesn't exist in the GET update methods; remove the needless checks
 - Allow GET/SET chunks to determine their own default values for non-present blocks/sections

* Add comments

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

@@ -425,7 +425,7 @@ public final class PaperweightFaweAdapter extends CachedBukkitAdapter implements
                 LOGGER.error("Attempted to convert {} with ID {} to char. ibdToStateOrdinal length: {}. Defaulting to air!",
                         blockState.getBlock(), Block.BLOCK_STATE_REGISTRY.getId(blockState), ibdToStateOrdinal.length, e1
                 );
-                return 0;
+                return BlockTypesCache.ReservedIDs.AIR;
             }
         }
     }

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

@@ -25,6 +25,7 @@ import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 import io.papermc.lib.PaperLib;
 import io.papermc.paper.event.block.BeaconDeactivatedEvent;
 import net.minecraft.core.BlockPos;
@@ -844,16 +845,16 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
             return data;
         }
         if (data != null && data.length != 4096) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
         }
         if (data == null || data == FaweCache.INSTANCE.EMPTY_CHAR_4096) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
         }
         DelegateSemaphore lock = PaperweightPlatformAdapter.applyLock(section);
         synchronized (lock) {
@@ -878,8 +879,7 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                     for (int i = 0; i < 4096; i++) {
                         char paletteVal = data[i];
                         char ordinal = adapter.ibdIDToOrdinal(paletteVal);
-                        // Don't read "empty".
+                        data[i] = ordinal;
-                        data[i] = ordinal == 0 ? 1 : ordinal;
                     }
                     return data;
                 }
@@ -898,18 +898,10 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                                 val = ordinal(palette.valueFor(i), adapter);
                                 paletteToOrdinal[i] = val;
                             }
-                            // Don't read "empty".
-                            if (val == 0) {
-                                val = 1;
-                            }
                             data[i] = val;
                         }
                     } else {
                         char ordinal = ordinal(palette.valueFor(0), adapter);
-                        // Don't read "empty".
-                        if (ordinal == 0) {
-                            ordinal = 1;
-                        }
                         Arrays.fill(data, ordinal);
                     }
                 } finally {
@@ -929,7 +921,7 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
 
     private char ordinal(net.minecraft.world.level.block.state.BlockState ibd, PaperweightFaweAdapter adapter) {
         if (ibd == null) {
-            return 1;
+            return BlockTypesCache.ReservedIDs.AIR;
         } else {
             return adapter.adaptToChar(ibd);
         }

worldedit-bukkit/adapters/adapter-1_18/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_18_R1/PaperweightFaweAdapter.java

@@ -420,7 +420,7 @@ public final class PaperweightFaweAdapter extends CachedBukkitAdapter implements
                 LOGGER.error("Attempted to convert {} with ID {} to char. ibdToStateOrdinal length: {}. Defaulting to air!",
                         blockState.getBlock(), Block.BLOCK_STATE_REGISTRY.getId(blockState), ibdToStateOrdinal.length, e1
                 );
-                return 0;
+                return BlockTypesCache.ReservedIDs.AIR;
             }
         }
     }

worldedit-bukkit/adapters/adapter-1_18/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_18_R1/PaperweightGetBlocks.java

@@ -25,6 +25,7 @@ import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 import io.papermc.lib.PaperLib;
 import io.papermc.paper.event.block.BeaconDeactivatedEvent;
 import net.minecraft.core.BlockPos;
@@ -874,16 +875,16 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
         // Section is null, return empty array
         if (section == null) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
             return data;
         }
         if (data != null && data.length != 4096) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
         }
         if (data == null || data == FaweCache.INSTANCE.EMPTY_CHAR_4096) {
             data = new char[4096];
-            Arrays.fill(data, (char) 1);
+            Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
         }
         DelegateSemaphore lock = PaperweightPlatformAdapter.applyLock(section);
         synchronized (lock) {
@@ -915,8 +916,7 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                     for (int i = 0; i < 4096; i++) {
                         char paletteVal = data[i];
                         char ordinal = adapter.ibdIDToOrdinal(paletteVal);
-                        // Don't read "empty".
+                        data[i] = ordinal;
-                        data[i] = ordinal == 0 ? 1 : ordinal;
                     }
                     return data;
                 }
@@ -935,18 +935,10 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                                 val = ordinal(palette.valueFor(i), adapter);
                                 paletteToOrdinal[i] = val;
                             }
-                            // Don't read "empty".
-                            if (val == 0) {
-                                val = 1;
-                            }
                             data[i] = val;
                         }
                     } else {
                         char ordinal = ordinal(palette.valueFor(0), adapter);
-                        // Don't read "empty".
-                        if (ordinal == 0) {
-                            ordinal = 1;
-                        }
                         Arrays.fill(data, ordinal);
                     }
                 } finally {
@@ -966,7 +958,7 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
 
     private char ordinal(net.minecraft.world.level.block.state.BlockState ibd, PaperweightFaweAdapter adapter) {
         if (ibd == null) {
-            return 1;
+            return BlockTypesCache.ReservedIDs.AIR;
         } else {
             return adapter.adaptToChar(ibd);
         }

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/adapter/NMSAdapter.java

@@ -23,8 +23,8 @@ public class NMSAdapter implements FAWEPlatformAdapterImpl {
         int num_palette = 0;
         for (int i = 0; i < 4096; i++) {
             char ordinal = set[i];
-            if (ordinal == 0) {
+            if (ordinal == BlockTypesCache.ReservedIDs.__RESERVED__) {
-                ordinal = 1;
+                ordinal = BlockTypesCache.ReservedIDs.AIR;
             }
             int palette = blockToPalette[ordinal];
             if (palette == Integer.MAX_VALUE) {
@@ -48,11 +48,11 @@ public class NMSAdapter implements FAWEPlatformAdapterImpl {
         for (int i = 0; i < 4096; i++) {
             char ordinal = set[i];
             switch (ordinal) {
-                case 0:
+                case BlockTypesCache.ReservedIDs.__RESERVED__:
-                    ordinal = 1;
+                    ordinal = BlockTypesCache.ReservedIDs.AIR;
-                case 1:
+                case BlockTypesCache.ReservedIDs.AIR:
-                case 2:
+                case BlockTypesCache.ReservedIDs.CAVE_AIR:
-                case 3:
+                case BlockTypesCache.ReservedIDs.VOID_AIR:
                     air++;
                     break;
                 default:
@@ -94,13 +94,13 @@ public class NMSAdapter implements FAWEPlatformAdapterImpl {
         char[] getArr = null;
         for (int i = 0; i < 4096; i++) {
             char ordinal = set[i];
-            if (ordinal == 0) {
+            if (ordinal == BlockTypesCache.ReservedIDs.__RESERVED__) {
                 if (getArr == null) {
                     getArr = get.apply(layer);
                 }
                 ordinal = getArr[i];
-                if (ordinal == 0) {
+                if (ordinal == BlockTypesCache.ReservedIDs.__RESERVED__) {
-                    ordinal = 1;
+                    ordinal = BlockTypesCache.ReservedIDs.AIR;
                 }
             }
             int palette = blockToPalette[ordinal];
@@ -119,24 +119,24 @@ public class NMSAdapter implements FAWEPlatformAdapterImpl {
             }
             System.arraycopy(adapter.getOrdinalToIbdID(), 0, blockToPalette, 0, adapter.getOrdinalToIbdID().length);
         }
-        char lastOrdinal = 0;
+        char lastOrdinal = BlockTypesCache.ReservedIDs.__RESERVED__;
         boolean lastticking = false;
         boolean tick_placed = Settings.settings().EXPERIMENTAL.ALLOW_TICK_PLACED;
         boolean tick_existing = Settings.settings().EXPERIMENTAL.ALLOW_TICK_EXISTING;
         for (int i = 0; i < 4096; i++) {
             char ordinal = set[i];
             switch (ordinal) {
-                case 0: {
+                case BlockTypesCache.ReservedIDs.__RESERVED__ -> {
                     if (getArr == null) {
                         getArr = get.apply(layer);
                     }
                     ordinal = getArr[i];
                     switch (ordinal) {
-                        case 0:
+                        case BlockTypesCache.ReservedIDs.__RESERVED__:
-                            ordinal = 1;
+                            ordinal = BlockTypesCache.ReservedIDs.AIR;
-                        case 1:
+                        case BlockTypesCache.ReservedIDs.AIR:
-                        case 2:
+                        case BlockTypesCache.ReservedIDs.CAVE_AIR:
-                        case 3:
+                        case BlockTypesCache.ReservedIDs.VOID_AIR:
                             air++;
                             break;
                         default:
@@ -151,23 +151,19 @@ public class NMSAdapter implements FAWEPlatformAdapterImpl {
                                 }
                                 if (ticking) {
                                     BlockState state = BlockState.getFromOrdinal(ordinal);
-                                    ticking_blocks
+                                    ticking_blocks.put(BlockVector3.at(i & 15, (i >> 8) & 15, (i >> 4) & 15),
-                                            .put(
+                                            WorldEditPlugin
-                                                    BlockVector3.at(i & 15, (i >> 8) & 15, (i >> 4) & 15),
+                                                    .getInstance()
-                                                    WorldEditPlugin.getInstance().getBukkitImplAdapter()
+                                                    .getBukkitImplAdapter()
-                                                            .getInternalBlockStateId(state).orElse(0)
+                                                    .getInternalBlockStateId(state)
+                                                    .orElse(0)
                                     );
                                 }
                             }
                     }
                     set[i] = ordinal;
-                    break;
                 }
-                case 1:
+                case BlockTypesCache.ReservedIDs.AIR, BlockTypesCache.ReservedIDs.CAVE_AIR, BlockTypesCache.ReservedIDs.VOID_AIR -> air++;
-                case 2:
-                case 3:
-                    air++;
-                    break;
             }
             if (!fastmode && tick_placed) {
                 boolean ticking;

worldedit-core/src/main/java/com/fastasyncworldedit/core/history/changeset/AbstractChangeSet.java

@@ -30,6 +30,7 @@ import com.sk89q.worldedit.world.World;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 import org.apache.logging.log4j.Logger;
 
 import java.io.IOException;
@@ -185,8 +186,8 @@ public abstract class AbstractChangeSet implements ChangeSet, IBatchProcessor {
                     for (int x = 0; x < 16; x++, index++) {
                         int xx = bx + x;
                         int from = blocksGet[index];
-                        if (from == 0) {
+                        if (from == BlockTypesCache.ReservedIDs.__RESERVED__) {
-                            from = 1;
+                            from = BlockTypesCache.ReservedIDs.AIR;
                         }
                         final int combinedFrom = from;
                         final int combinedTo = blocksSet[index];

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IBlocks.java

@@ -9,6 +9,7 @@ import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 import com.sk89q.worldedit.world.registry.BlockRegistry;
 
 import javax.annotation.Nullable;
@@ -115,11 +116,11 @@ public interface IBlocks extends Trimable {
                 for (int i = 0; i < ids.length; i++) {
                     char ordinal = ids[i];
                     switch (ordinal) {
-                        case 0:
+                        case BlockTypesCache.ReservedIDs.__RESERVED__:
-                        case 2:
+                        case BlockTypesCache.ReservedIDs.CAVE_AIR:
-                        case 3:
+                        case BlockTypesCache.ReservedIDs.VOID_AIR:
-                            ids[i] = 1;
+                            ids[i] = BlockTypesCache.ReservedIDs.AIR;
-                        case 1:
+                        case BlockTypesCache.ReservedIDs.AIR:
                             continue;
                         default:
                             nonEmpty++;
@@ -139,10 +140,10 @@ public interface IBlocks extends Trimable {
                 for (int i = 0; i < palette.paletteToBlockLength; i++) {
                     int ordinal = palette.paletteToBlock[i];
                     switch (ordinal) {
-                        case 0:
+                        case BlockTypesCache.ReservedIDs.__RESERVED__:
-                        case 2:
+                        case BlockTypesCache.ReservedIDs.AIR:
-                        case 3:
+                        case BlockTypesCache.ReservedIDs.CAVE_AIR:
-                        case 1:
+                        case BlockTypesCache.ReservedIDs.VOID_AIR:
                             sectionWriter.write(0);
                             break;
                         default:

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/BitSetBlocks.java

@@ -9,6 +9,7 @@ import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockState;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 
 import javax.annotation.Nullable;
 import java.util.Arrays;
@@ -59,7 +60,7 @@ public class BitSetBlocks implements IChunkSet {
         for (int y = 0, index = 0; y < 16; y++) {
             for (int z = 0; z < 16; z++) {
                 for (int x = 0; x < 16; x++, index++) {
-                    if (data[index] != 0) {
+                    if (data[index] != BlockTypesCache.ReservedIDs.__RESERVED__) {
                         row.set(null, x, by + y, z, minSectionPosition, maxSectionPosition);
                     }
                 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/CharBlocks.java

@@ -134,7 +134,7 @@ public abstract class CharBlocks implements IBlocks {
             return new char[4096];
         }
         for (int i = 0; i < 4096; i++) {
-            data[i] = 0;
+            data[i] = defaultOrdinal();
         }
         return data;
     }
@@ -188,11 +188,16 @@ public abstract class CharBlocks implements IBlocks {
         int layer = y >> 4;
         final int index = (y & 15) << 8 | z << 4 | x;
         if (layer > maxSectionPosition || layer < minSectionPosition) {
-            return 0;
+            return defaultOrdinal();
         }
         return get(layer, index);
     }
 
+    /**
+     * Default char value to be used when "updating"/resetting data arrays
+     */
+    protected abstract char defaultOrdinal();
+
     // Not synchronized as it refers to a synchronized method and includes nothing that requires synchronization
     public void set(int x, int y, int z, char value) {
         final int layer = y >> 4;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/CharGetBlocks.java

@@ -37,10 +37,15 @@ public abstract class CharGetBlocks extends CharBlocks implements IChunkGet {
         if (data == null) {
             data = new char[4096];
         }
-        Arrays.fill(data, (char) 1);
+        Arrays.fill(data, (char) BlockTypesCache.ReservedIDs.AIR);
         return data;
     }
 
+    @Override
+    protected char defaultOrdinal() {
+        return BlockTypesCache.ReservedIDs.AIR;
+    }
+
     @Override
     public synchronized boolean trim(boolean aggressive, int layer) {
         layer -= minSectionPosition;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/CharSetBlocks.java

@@ -11,6 +11,7 @@ import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
 
 import java.util.Arrays;
 import java.util.Collections;
@@ -326,6 +327,11 @@ public class CharSetBlocks extends CharBlocks implements IChunkSet {
         return super.load(layer);
     }
 
+    @Override
+    protected char defaultOrdinal() {
+        return BlockTypesCache.ReservedIDs.__RESERVED__;
+    }
+
     // Checks and updates the various section arrays against the new layer index
     private void updateSectionIndexRange(int layer) {
         if (layer >= minSectionPosition && layer <= maxSectionPosition) {

worldedit-core/src/main/java/com/sk89q/worldedit/world/block/BlockTypesCache.java

@@ -13,6 +13,7 @@ import com.sk89q.worldedit.world.registry.BlockMaterial;
 import com.sk89q.worldedit.world.registry.BlockRegistry;
 import com.sk89q.worldedit.world.registry.Registries;
 
+import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -220,55 +221,30 @@ public class BlockTypesCache {
             BIT_MASK = ((1 << BIT_OFFSET) - 1);
             values = new BlockType[size];
 
-            /*Field[] idFields = BlockID.class.getDeclaredFields();
+            // Register reserved IDs. Ensure air/reserved are 0/1/2/3
-            for (Field field : idFields) {
+            {
-                size = Math.max(field.getInt(null) + 1, size);
+                for (Field field : ReservedIDs.class.getDeclaredFields()) {
-            }
-
-            // Register the statically declared ones first
-            for (Field field : idFields) {
                     if (field.getType() == int.class) {
                         int internalId = field.getInt(null);
                         String id = "minecraft:" + field.getName().toLowerCase(Locale.ROOT);
                         String defaultState = blockMap.remove(id);
                         if (defaultState == null) {
-                        if (internalId != 0) {
-                            continue;
-                        }
                             defaultState = id;
                         }
                         if (values[internalId] != null) {
-                        throw new IllegalStateException("Invalid duplicate id for " + field.getName());
+                            throw new IllegalStateException(String.format(
+                                    "Invalid duplicate id for %s! Something has gone very wrong. Are " +
+                                            "any plugins shading FAWE?!", id));
                         }
                         BlockType type = register(defaultState, internalId, stateList, tickList);
                         // Note: Throws IndexOutOfBoundsError if nothing is registered and blocksMap is empty
                         values[internalId] = type;
                     }
-            }*/
-
-            // Register "Reserved". Ensure air/reserved and 0/1/2/3
-            {
-                int internalId = 0;
-                for (String id : new String[]{"minecraft:__reserved__", "minecraft:air", "minecraft:cave_air",
-                        "minecraft:void_air"}) {
-                    String defaultState = blockMap.remove(id);
-                    if (defaultState == null) {
-                        defaultState = id;
-                    }
-                    if (values[internalId] != null) {
-                        throw new IllegalStateException(
-                                "Invalid duplicate id for __reserved__! Something has gone very wrong. Are " +
-                                        "any plugins shading FAWE?!");
-                    }
-                    BlockType type = register(defaultState, internalId, stateList, tickList);
-                    // Note: Throws IndexOutOfBoundsError if nothing is registered and blocksMap is empty
-                    values[internalId] = type;
-                    internalId++;
                 }
             }
 
             { // Register real blocks
-                int internalId = 1;
+                int internalId = 0;
                 for (Map.Entry<String, String> entry : blockMap.entrySet()) {
                     String defaultState = entry.getValue();
                     // Skip already registered ids
@@ -328,4 +304,15 @@ public class BlockTypesCache {
         }
     }
 
+    /**
+     * Statically-set reserved IDs. Should be used as minimally as possible, and for IDs that will see frequent use
+     */
+    public static class ReservedIDs {
+        public static final int __RESERVED__ = 0;
+        public static final int AIR = 1;
+        public static final int CAVE_AIR = 2;
+        public static final int VOID_AIR = 3;
+
+    }
+
 }

worldedit-core/src/main/java/com/sk89q/worldedit/world/block/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * The following classes are FAWE additions:
+ *
+ * @see com.sk89q.worldedit.world.block.BlockTypesCache
+ */
+package com.sk89q.worldedit.world.block;