Merge pull request #1799 from KennyTV/abstraction

Use FastUtil collections for frequently called code

common/pom.xml

@@ -19,5 +19,13 @@
             <version>1.18</version>
             <scope>compile</scope> <!-- Velocity doesn't have snakeyaml -->
         </dependency>
+
+        <!-- FastUtil for performance increases -->
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>8.3.1</version>
+            <scope>compile</scope>
+        </dependency>
     </dependencies>
 </project>

common/src/main/java/us/myles/ViaVersion/api/entities/Entity1_13Types.java

@@ -91,12 +91,11 @@ public class Entity1_13Types {
 
         // Fish
         ABSTRACT_FISHES(-1, ABSTRACT_CREATURE), // agb
-        COD_MOB(8, ABSTRACT_FISHES), // agf
+        COD(8, ABSTRACT_FISHES), // agf
         PUFFERFISH(52, ABSTRACT_FISHES), // agn
         SALMON(57, ABSTRACT_FISHES), // agp
         TROPICAL_FISH(72, ABSTRACT_FISHES), // agu
 
-
         // Monsters
         ABSTRACT_MONSTER(-1, ABSTRACT_CREATURE), // ajs
         BLAZE(4, ABSTRACT_MONSTER), // ajd
@@ -248,7 +247,7 @@ public class Entity1_13Types {
         ENDER_PEARL(65, EntityType.ENDER_PEARL),
         WITHER_SKULL(66, EntityType.WITHER_SKULL),
         SHULKER_BULLET(67, EntityType.SHULKER_BULLET),
-        LIAMA_SPIT(68, EntityType.LLAMA_SPIT),
+        LLAMA_SPIT(68, EntityType.LLAMA_SPIT),
         FALLING_BLOCK(70, EntityType.FALLING_BLOCK),
         ITEM_FRAME(71, EntityType.ITEM_FRAME),
         EYE_OF_ENDER(72, EntityType.EYE_OF_ENDER),

common/src/main/java/us/myles/ViaVersion/api/protocol/ProtocolRegistry.java

@@ -2,6 +2,8 @@ package us.myles.ViaVersion.api.protocol;
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Range;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import org.jetbrains.annotations.Nullable;
 import us.myles.ViaVersion.api.Pair;
 import us.myles.ViaVersion.api.Via;
@@ -52,7 +54,7 @@ public class ProtocolRegistry {
     public static final Protocol BASE_PROTOCOL = new BaseProtocol();
     public static int SERVER_PROTOCOL = -1;
     // Input Version -> Output Version & Protocol (Allows fast lookup)
-    private static final Map<Integer, Map<Integer, Protocol>> registryMap = new ConcurrentHashMap<>();
+    private static final Int2ObjectMap<Int2ObjectMap<Protocol>> registryMap = new Int2ObjectOpenHashMap<>(32);
     private static final Map<Class<? extends Protocol>, Protocol> protocols = new HashMap<>();
     private static final Map<Pair<Integer, Integer>, List<Pair<Integer, Protocol>>> pathCache = new ConcurrentHashMap<>();
     private static final Set<Integer> supportedVersions = new HashSet<>();
@@ -126,7 +128,7 @@ public class ProtocolRegistry {
      * @param supported Supported client versions.
      * @param output    The output server version it converts to.
      */
-    public static void registerProtocol(Protocol protocol, List<Integer> supported, Integer output) {
+    public static void registerProtocol(Protocol protocol, List<Integer> supported, int output) {
         // Clear cache as this may make new routes.
         if (!pathCache.isEmpty()) {
             pathCache.clear();
@@ -135,7 +137,7 @@ public class ProtocolRegistry {
         protocols.put(protocol.getClass(), protocol);
 
         for (int version : supported) {
-            Map<Integer, Protocol> protocolMap = registryMap.computeIfAbsent(version, k -> new HashMap<>());
+            Int2ObjectMap<Protocol> protocolMap = registryMap.computeIfAbsent(version, s -> new Int2ObjectOpenHashMap<>(2));
             protocolMap.put(output, protocol);
         }
 
@@ -204,8 +206,8 @@ public class ProtocolRegistry {
      * @return True if there is a useful pipe
      */
     public static boolean isWorkingPipe() {
-        for (Map<Integer, Protocol> maps : registryMap.values()) {
+        for (Int2ObjectMap<Protocol> map : registryMap.values()) {
-            if (maps.containsKey(SERVER_PROTOCOL)) return true;
+            if (map.containsKey(SERVER_PROTOCOL)) return true;
         }
         return false; // No destination for protocol
     }
@@ -234,25 +236,28 @@ public class ProtocolRegistry {
         if (current.size() > 50) return null; // Fail safe, protocol too complicated.
 
         // First check if there is any protocols for this
-        Map<Integer, Protocol> inputMap = registryMap.get(clientVersion);
+        Int2ObjectMap<Protocol> inputMap = registryMap.get(clientVersion);
         if (inputMap == null) {
             return null; // Not supported
         }
+
         // Next check there isn't an obvious path
         Protocol protocol = inputMap.get(serverVersion);
         if (protocol != null) {
             current.add(new Pair<>(serverVersion, protocol));
             return current; // Easy solution
         }
+
         // There might be a more advanced solution... So we'll see if any of the others can get us there
         List<Pair<Integer, Protocol>> shortest = null;
-
+        for (Int2ObjectMap.Entry<Protocol> entry : inputMap.int2ObjectEntrySet()) {
-        for (Map.Entry<Integer, Protocol> entry : inputMap.entrySet()) {
             // Ensure it wasn't caught by the other loop
-            if (!entry.getKey().equals(serverVersion)) {
+            if (entry.getIntKey() == (serverVersion)) continue;
-                Pair<Integer, Protocol> pair = new Pair<>(entry.getKey(), entry.getValue());
+
+            Pair<Integer, Protocol> pair = new Pair<>(entry.getIntKey(), entry.getValue());
             // Ensure no recursion
-                if (!current.contains(pair)) {
+            if (current.contains(pair)) continue;
+
             // Create a copy
             List<Pair<Integer, Protocol>> newCurrent = new ArrayList<>(current);
             newCurrent.add(pair);
@@ -265,8 +270,6 @@ public class ProtocolRegistry {
                 }
             }
         }
-            }
-        }
 
         return shortest; // null if none found
     }

common/src/main/java/us/myles/ViaVersion/api/rewriters/MetadataRewriter.java

@@ -1,5 +1,7 @@
 package us.myles.ViaVersion.api.rewriters;
 
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import org.jetbrains.annotations.Nullable;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
@@ -23,7 +25,7 @@ import java.util.logging.Logger;
 public abstract class MetadataRewriter {
     private final Class<? extends EntityTracker> entityTrackerClass;
     private final Protocol protocol;
-    private Map<Integer, Integer> typeMapping;
+    private Int2IntMap typeMapping;
 
     protected MetadataRewriter(Protocol protocol, Class<? extends EntityTracker> entityTrackerClass) {
         this.protocol = protocol;
@@ -182,7 +184,10 @@ public abstract class MetadataRewriter {
     }
 
     public <T extends Enum<T> & EntityType> void mapTypes(EntityType[] oldTypes, Class<T> newTypeClass) {
-        if (typeMapping == null) typeMapping = new HashMap<>(oldTypes.length);
+        if (typeMapping == null) {
+            typeMapping = new Int2IntOpenHashMap(oldTypes.length, 1F);
+            typeMapping.defaultReturnValue(-1);
+        }
         for (EntityType oldType : oldTypes) {
             try {
                 T newType = Enum.valueOf(newTypeClass, oldType.name());
@@ -190,14 +195,17 @@ public abstract class MetadataRewriter {
             } catch (IllegalArgumentException notFound) {
                 if (!typeMapping.containsKey(oldType.getId())) {
                     Via.getPlatform().getLogger().warning("Could not find new entity type for " + oldType + "! " +
-                            "Old type: " + oldType.getClass().getSimpleName() + " New type: " + newTypeClass.getSimpleName());
+                            "Old type: " + oldType.getClass().getEnclosingClass().getSimpleName() + ", new type: " + newTypeClass.getEnclosingClass().getSimpleName());
                 }
             }
         }
     }
 
     public void mapType(EntityType oldType, EntityType newType) {
-        if (typeMapping == null) typeMapping = new HashMap<>();
+        if (typeMapping == null) {
+            typeMapping = new Int2IntOpenHashMap();
+            typeMapping.defaultReturnValue(-1);
+        }
         typeMapping.put(oldType.getId(), newType.getId());
     }
 

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/Protocol1_13To1_12_2.java

@@ -346,8 +346,8 @@ public class Protocol1_13To1_12_2 extends Protocol<ClientboundPackets1_12_1, Cli
                             }
                         } else {
                             for (int i = 0; i < 16; i++) {
-                                Integer newItem = MappingData.oldToNewItems.get(item << 4 | i);
+                                int newItem = MappingData.oldToNewItems.get(item << 4 | i);
-                                if (newItem != null) {
+                                if (newItem != -1) {
                                     PacketWrapper packet = wrapper.create(0x18);
                                     packet.write(Type.VAR_INT, newItem);
                                     packet.write(Type.VAR_INT, ticks);

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/blockconnections/ConnectionData.java

@@ -3,6 +3,10 @@ package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.blockconnections;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.MappingDataLoader;
@@ -17,17 +21,21 @@ import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.Protocol1_13To1_12_2;
 import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.blockconnections.providers.BlockConnectionProvider;
 import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.blockconnections.providers.PacketBlockConnectionProvider;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
 import java.util.Map.Entry;
 
 public class ConnectionData {
     private static final BlockChangeRecord[] A = new BlockChangeRecord[0];
     public static BlockConnectionProvider blockConnectionProvider;
-    static Map<Integer, String> idToKey = new HashMap<>();
+    static Int2ObjectMap<String> idToKey = new Int2ObjectOpenHashMap<>(8582, 1F);
-    static Map<String, Integer> keyToId = new HashMap<>();
+    static Map<String, Integer> keyToId = new HashMap<>(8582, 1F);
-    static Map<Integer, ConnectionHandler> connectionHandlerMap = new HashMap<>();
+    static Int2ObjectMap<ConnectionHandler> connectionHandlerMap = new Int2ObjectOpenHashMap<>(1);
-    static Map<Integer, BlockData> blockConnectionData = new HashMap<>();
+    static Int2ObjectMap<BlockData> blockConnectionData = new Int2ObjectOpenHashMap<>(1);
-    static Set<Integer> occludingStates = new HashSet<>();
+    static IntSet occludingStates = new IntOpenHashSet(377, 1F);
 
     public static void update(UserConnection user, Position position) {
         for (BlockFace face : BlockFace.values()) {
@@ -194,17 +202,21 @@ public class ConnectionData {
 
     public static void init() {
         if (!Via.getConfig().isServersideBlockConnections()) return;
+
         Via.getPlatform().getLogger().info("Loading block connection mappings ...");
         JsonObject mapping1_13 = MappingDataLoader.loadData("mapping-1.13.json", true);
         JsonObject blocks1_13 = mapping1_13.getAsJsonObject("blocks");
         for (Entry<String, JsonElement> blockState : blocks1_13.entrySet()) {
-            Integer id = Integer.parseInt(blockState.getKey());
+            int id = Integer.parseInt(blockState.getKey());
             String key = blockState.getValue().getAsString();
             idToKey.put(id, key);
             keyToId.put(key, id);
         }
 
+        connectionHandlerMap = new Int2ObjectOpenHashMap<>(3650, 1F);
+
         if (!Via.getConfig().isReduceBlockStorageMemory()) {
+            blockConnectionData = new Int2ObjectOpenHashMap<>(1146, 1F);
             JsonObject mappingBlockConnections = MappingDataLoader.loadData("blockConnections.json");
             for (Entry<String, JsonElement> entry : mappingBlockConnections.entrySet()) {
                 int id = keyToId.get(entry.getKey());
@@ -231,7 +243,7 @@ public class ConnectionData {
         JsonObject blockData = MappingDataLoader.loadData("blockData.json");
         JsonArray occluding = blockData.getAsJsonArray("occluding");
         for (JsonElement jsonElement : occluding) {
-            occludingStates.add(keyToId.get(jsonElement.getAsString()));
+            occludingStates.add(keyToId.get(jsonElement.getAsString()).intValue());
         }
 
         List<ConnectorInitAction> initActions = new ArrayList<>();

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/blockconnections/FlowerConnectionHandler.java

@@ -1,18 +1,18 @@
 package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.blockconnections;
 
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
 import us.myles.ViaVersion.api.minecraft.BlockFace;
 import us.myles.ViaVersion.api.minecraft.Position;
 
-import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Map;
 import java.util.Set;
 
 
 public class FlowerConnectionHandler extends ConnectionHandler {
-    private static final Map<Integer, Integer> flowers = new HashMap<>();
+    private static final Int2IntMap flowers = new Int2IntOpenHashMap();
 
     static ConnectionData.ConnectorInitAction init() {
         final Set<String> baseFlower = new HashSet<>();
@@ -38,8 +38,8 @@ public class FlowerConnectionHandler extends ConnectionHandler {
     @Override
     public int connect(UserConnection user, Position position, int blockState) {
         int blockBelowId = getBlockData(user, position.getRelative(BlockFace.BOTTOM));
-        Integer connectBelow = flowers.get(blockBelowId);
+        int connectBelow = flowers.get(blockBelowId);
-        if (connectBelow != null) {
+        if (connectBelow != 0) {
             int blockAboveId = getBlockData(user, position.getRelative(BlockFace.TOP));
             if (Via.getConfig().isStemWhenBlockAbove()) {
                 if (blockAboveId == 0) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/blockconnections/RedstoneConnectionHandler.java

@@ -1,18 +1,18 @@
 package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.blockconnections;
 
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import us.myles.ViaVersion.api.data.UserConnection;
 import us.myles.ViaVersion.api.minecraft.BlockFace;
 import us.myles.ViaVersion.api.minecraft.Position;
 
-import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Map;
 import java.util.Set;
 
 public class RedstoneConnectionHandler extends ConnectionHandler {
     private static final Set<Integer> redstone = new HashSet<>();
-    private static final Map<Short, Integer> connectedBlockStates = new HashMap<>();
+    private static final Int2IntMap connectedBlockStates = new Int2IntOpenHashMap(1296);
-    private static final Map<Integer, Integer> powerMappings = new HashMap<>();
+    private static final Int2IntMap powerMappings = new Int2IntOpenHashMap(1296);
 
     static ConnectionData.ConnectorInitAction init() {
         final RedstoneConnectionHandler connectionHandler = new RedstoneConnectionHandler();
@@ -22,7 +22,7 @@ public class RedstoneConnectionHandler extends ConnectionHandler {
             redstone.add(blockData.getSavedBlockStateId());
             ConnectionData.connectionHandlerMap.put(blockData.getSavedBlockStateId(), connectionHandler);
             connectedBlockStates.put(getStates(blockData), blockData.getSavedBlockStateId());
-            powerMappings.put(blockData.getSavedBlockStateId(), Integer.valueOf(blockData.getValue("power")));
+            powerMappings.put(blockData.getSavedBlockStateId(), Integer.parseInt(blockData.getValue("power")));
         };
     }
 
@@ -57,8 +57,7 @@ public class RedstoneConnectionHandler extends ConnectionHandler {
         b |= connects(user, position, BlockFace.SOUTH) << 4;
         b |= connects(user, position, BlockFace.WEST) << 6;
         b |= powerMappings.get(blockState) << 8;
-        final Integer newBlockState = connectedBlockStates.get(b);
+        return connectedBlockStates.getOrDefault(b, blockState);
-        return newBlockState == null ? blockState : newBlockState;
     }
 
     private int connects(UserConnection user, Position position, BlockFace side) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/data/BlockIdData.java

@@ -2,6 +2,8 @@ package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.data;
 
 import com.google.common.collect.ObjectArrays;
 import com.google.gson.reflect.TypeToken;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import us.myles.ViaVersion.util.GsonUtil;
 
 import java.io.IOException;
@@ -13,18 +15,18 @@ import java.util.Map;
 public class BlockIdData {
     public static Map<String, String[]> blockIdMapping;
     public static Map<String, String[]> fallbackReverseMapping;
-    public static Map<Integer, String> numberIdToString;
+    public static Int2ObjectMap<String> numberIdToString;
 
     public static void init() {
         InputStream stream = MappingData.class.getClassLoader()
                 .getResourceAsStream("assets/viaversion/data/blockIds1.12to1.13.json");
         InputStreamReader reader = new InputStreamReader(stream);
         try {
-            blockIdMapping = new HashMap<>((Map<String, String[]>) GsonUtil.getGson().fromJson(
+            blockIdMapping = new HashMap<>(GsonUtil.getGson().fromJson(
                     reader,
                     new TypeToken<Map<String, String[]>>() {
                     }.getType()
-            ));
+            ), 1F);
             fallbackReverseMapping = new HashMap<>();
             for (Map.Entry<String, String[]> entry : blockIdMapping.entrySet()) {
                 for (String val : entry.getValue()) {
@@ -45,7 +47,7 @@ public class BlockIdData {
                 .getResourceAsStream("assets/viaversion/data/blockNumberToString1.12.json");
         InputStreamReader blockR = new InputStreamReader(blockS);
         try {
-            numberIdToString = new HashMap<>((Map<Integer, String>) GsonUtil.getGson().fromJson(
+            numberIdToString = new Int2ObjectOpenHashMap<>(GsonUtil.getGson().fromJson(
                     blockR,
                     new TypeToken<Map<Integer, String>>() {
                     }.getType()

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/data/EntityTypeRewriter.java

@@ -1,14 +1,13 @@
 package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.data;
 
-
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
-import java.util.HashMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
-import java.util.Map;
-import java.util.Optional;
 
 public class EntityTypeRewriter {
-    private static final Map<Integer, Integer> entityTypes = new HashMap<>();
+    private static final Int2IntMap ENTITY_TYPES = new Int2IntOpenHashMap(83, 1F);
 
     static {
+        ENTITY_TYPES.defaultReturnValue(-1);
         registerEntity(1, 32); // item - ajl
         registerEntity(2, 22); // xp_orb - abx
         registerEntity(3, 0); // area_effect_cloud - abp
@@ -92,16 +91,13 @@ public class EntityTypeRewriter {
         registerEntity(104, 37); // llama_spit - alr
         registerEntity(105, 50); // parrot - agx
         registerEntity(120, 79); // villager - ala
-
-        // OBJECTS
-        // Couldn't find any object id change with mapped values
     }
 
     private static void registerEntity(int type1_12, int type1_13) {
-        entityTypes.put(type1_12, type1_13);
+        ENTITY_TYPES.put(type1_12, type1_13);
     }
 
-    public static Optional<Integer> getNewId(int type1_12) {
+    public static int getNewId(int type1_12) {
-        return Optional.ofNullable(entityTypes.get(type1_12));
+        return ENTITY_TYPES.getOrDefault(type1_12, type1_12);
     }
 }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/data/MappingData.java

@@ -11,6 +11,7 @@ import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.MappingDataLoader;
 import us.myles.ViaVersion.api.data.Mappings;
 import us.myles.ViaVersion.util.GsonUtil;
+import us.myles.ViaVersion.util.Int2IntBiMap;
 
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -20,7 +21,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 public class MappingData {
-    public static final BiMap<Integer, Integer> oldToNewItems = HashBiMap.create();
+    public static final Int2IntBiMap oldToNewItems = new Int2IntBiMap();
     public static final Map<String, Integer[]> blockTags = new HashMap<>();
     public static final Map<String, Integer[]> itemTags = new HashMap<>();
     public static final Map<String, Integer[]> fluidTags = new HashMap<>();
@@ -37,6 +38,7 @@ public class MappingData {
         JsonObject mapping1_12 = MappingDataLoader.loadData("mapping-1.12.json", true);
         JsonObject mapping1_13 = MappingDataLoader.loadData("mapping-1.13.json", true);
 
+        oldToNewItems.defaultReturnValue(-1);
         blockMappings = new BlockMappingsShortArray(mapping1_12.getAsJsonObject("blocks"), mapping1_13.getAsJsonObject("blocks"));
         MappingDataLoader.mapIdentifiers(oldToNewItems, mapping1_12.getAsJsonObject("items"), mapping1_13.getAsJsonObject("items"));
         loadTags(blockTags, mapping1_13.getAsJsonObject("block_tags"));

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/metadata/MetadataRewriter1_13To1_12_2.java

@@ -102,7 +102,7 @@ public class MetadataRewriter1_13To1_12_2 extends MetadataRewriter {
 
     @Override
     public int getNewEntityId(final int oldId) {
-        return EntityTypeRewriter.getNewId(oldId).orElse(oldId);
+        return EntityTypeRewriter.getNewId(oldId);
     }
 
     @Override

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/packets/InventoryPackets.java

@@ -435,7 +435,7 @@ public class InventoryPackets {
             }
         }
 
-        item.setIdentifier(MappingData.oldToNewItems.get(rawId).shortValue());
+        item.setIdentifier(MappingData.oldToNewItems.get(rawId));
         item.setData((short) 0);
     }
 
@@ -487,8 +487,8 @@ public class InventoryPackets {
         }
 
         if (rawId == null) {
-            Integer oldId = MappingData.oldToNewItems.inverse().get(item.getIdentifier());
+            int oldId = MappingData.oldToNewItems.inverse().get(item.getIdentifier());
-            if (oldId != null) {
+            if (oldId != -1) {
                 // Handle spawn eggs
                 Optional<String> eggEntityId = SpawnEggRewriter.getEntityId(oldId);
                 if (eggEntityId.isPresent()) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/packets/WorldPackets.java

@@ -1,6 +1,8 @@
 package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.packets;
 
 import com.github.steveice10.opennbt.tag.builtin.CompoundTag;
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
@@ -27,31 +29,29 @@ import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.types.Chunk1_13Type;
 import us.myles.ViaVersion.protocols.protocol1_9_1_2to1_9_3_4.types.Chunk1_9_3_4Type;
 import us.myles.ViaVersion.protocols.protocol1_9_3to1_9_1_2.storage.ClientWorld;
 
-import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
-import java.util.Set;
 
 public class WorldPackets {
-    private static final Set<Integer> validBiomes = new HashSet<>();
+    private static final IntSet VALID_BIOMES = new IntOpenHashSet(70, 1F);
 
     static {
         // Client will crash if it receives a invalid biome id
         for (int i = 0; i < 50; i++) {
-            validBiomes.add(i);
+            VALID_BIOMES.add(i);
         }
-        validBiomes.add(127);
+        VALID_BIOMES.add(127);
         for (int i = 129; i <= 134; i++) {
-            validBiomes.add(i);
+            VALID_BIOMES.add(i);
         }
-        validBiomes.add(140);
+        VALID_BIOMES.add(140);
-        validBiomes.add(149);
+        VALID_BIOMES.add(149);
-        validBiomes.add(151);
+        VALID_BIOMES.add(151);
         for (int i = 155; i <= 158; i++) {
-            validBiomes.add(i);
+            VALID_BIOMES.add(i);
         }
         for (int i = 160; i <= 167; i++) {
-            validBiomes.add(i);
+            VALID_BIOMES.add(i);
         }
     }
 
@@ -407,7 +407,7 @@ public class WorldPackets {
                             int latestBiomeWarn = Integer.MIN_VALUE;
                             for (int i = 0; i < 256; i++) {
                                 int biome = chunk.getBiomeData()[i];
-                                if (!validBiomes.contains(biome)) {
+                                if (!VALID_BIOMES.contains(biome)) {
                                     if (biome != 255 // is it generated naturally? *shrug*
                                             && latestBiomeWarn != biome) {
                                         if (!Via.getConfig().isSuppressConversionWarnings() || Via.getManager().isDebug()) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/storage/BlockConnectionStorage.java

@@ -11,25 +11,29 @@ import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.packets.WorldPackets;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
 public class BlockConnectionStorage extends StoredObject {
-    private final Map<Long, Pair<byte[], NibbleArray>> blockStorage = createLongObjectMap();
+    private static final short[] REVERSE_BLOCK_MAPPINGS = new short[8582];
-
-    private static final Map<Short, Short> reverseBlockMappings;
     private static Constructor<?> fastUtilLongObjectHashMap;
 
+    private final Map<Long, Pair<byte[], NibbleArray>> blockStorage = createLongObjectMap();
+
     static {
         try {
             fastUtilLongObjectHashMap = Class.forName("it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap").getConstructor();
             Via.getPlatform().getLogger().info("Using FastUtil Long2ObjectOpenHashMap for block connections");
         } catch (ClassNotFoundException | NoSuchMethodException ignored) {
         }
-        reverseBlockMappings = new HashMap<>();
+
+        Arrays.fill(REVERSE_BLOCK_MAPPINGS, (short) -1);
         for (int i = 0; i < 4096; i++) {
             int newBlock = MappingData.blockMappings.getNewId(i);
-            if (newBlock != -1) reverseBlockMappings.put((short) newBlock, (short) i);
+            if (newBlock != -1) {
+                REVERSE_BLOCK_MAPPINGS[newBlock] = (short) i;
+            }
         }
     }
 
@@ -38,15 +42,18 @@ public class BlockConnectionStorage extends StoredObject {
     }
 
     public void store(int x, int y, int z, int blockState) {
-        Short mapping = reverseBlockMappings.get((short) blockState);
+        short mapping = REVERSE_BLOCK_MAPPINGS[blockState];
-        if (mapping == null) return;
+        if (mapping == -1) return;
+
         blockState = mapping;
         long pair = getChunkSectionIndex(x, y, z);
         Pair<byte[], NibbleArray> map = getChunkSection(pair, (blockState & 0xF) != 0);
         int blockIndex = encodeBlockPos(x, y, z);
         map.getKey()[blockIndex] = (byte) (blockState >> 4);
         NibbleArray nibbleArray = map.getValue();
-        if (nibbleArray != null) nibbleArray.set(blockIndex, blockState);
+        if (nibbleArray != null) {
+            nibbleArray.set(blockIndex, blockState);
+        }
     }
 
     public int get(int x, int y, int z) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/storage/BlockStorage.java

@@ -1,38 +1,41 @@
 package us.myles.ViaVersion.protocols.protocol1_13to1_12_2.storage;
 
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
 import us.myles.ViaVersion.api.data.StoredObject;
 import us.myles.ViaVersion.api.data.UserConnection;
 import us.myles.ViaVersion.api.minecraft.Position;
 
-import java.util.HashSet;
 import java.util.Map;
-import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
 public class BlockStorage extends StoredObject {
-    private static final Set<Integer> whitelist = new HashSet<>();
+    private static final IntSet WHITELIST = new IntOpenHashSet(46, 1F);
     private final Map<Position, ReplacementData> blocks = new ConcurrentHashMap<>();
 
     static {
         // Flower pots
-        whitelist.add(5266);
+        WHITELIST.add(5266);
 
         // Add those red beds
-        for (int i = 0; i < 16; i++)
+        for (int i = 0; i < 16; i++) {
-            whitelist.add(972 + i);
+            WHITELIST.add(972 + i);
+        }
 
         // Add the white banners
-        for (int i = 0; i < 20; i++)
+        for (int i = 0; i < 20; i++) {
-            whitelist.add(6854 + i);
+            WHITELIST.add(6854 + i);
+        }
 
         // Add the white wall banners
         for (int i = 0; i < 4; i++) {
-            whitelist.add(7110 + i);
+            WHITELIST.add(7110 + i);
         }
 
         // Skeleton skulls
-        for (int i = 0; i < 5; i++)
+        for (int i = 0; i < 5; i++) {
-            whitelist.add(5447 + i);
+            WHITELIST.add(5447 + i);
+        }
     }
 
     public BlockStorage(UserConnection user) {
@@ -44,14 +47,14 @@ public class BlockStorage extends StoredObject {
     }
 
     public void store(Position position, int block, int replacementId) {
-        if (!whitelist.contains(block))
+        if (!WHITELIST.contains(block))
             return;
 
         blocks.put(position, new ReplacementData(block, replacementId));
     }
 
     public boolean isWelcome(int block) {
-        return whitelist.contains(block);
+        return WHITELIST.contains(block);
     }
 
     public boolean contains(Position position) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_14to1_13_2/data/EntityTypeRewriter.java

@@ -1,109 +0,0 @@
-package us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
-public class EntityTypeRewriter {
-    private static final Map<Integer, Integer> entityTypes = new HashMap<>();
-
-    static {
-        regEnt(6, 7);  // cave_spider
-        regEnt(7, 8); // chicken
-        regEnt(8, 9); // cod
-        regEnt(9, 10); // cow
-        regEnt(10, 11); // creeper
-        regEnt(11, 12); // donkey
-        regEnt(12, 13); // dolphin
-        regEnt(13, 14); // dragon_fireball
-        regEnt(14, 15); // drowned
-        regEnt(15, 16); // elder_guardian
-        regEnt(16, 17); // end_crystal
-        regEnt(17, 18); // ender_dragon
-        regEnt(18, 19); // enderman
-        regEnt(19, 20); // endermite
-        regEnt(20, 21); // evoker_fangs
-        regEnt(21, 22); // evoker
-        regEnt(22, 23); // experience_orb
-        regEnt(23, 24); // eye_of_ender
-        regEnt(24, 25); // falling_block
-        regEnt(25, 26); // firework_rocket
-        regEnt(26, 28); // ghast
-        regEnt(27, 29); // giant
-        regEnt(28, 30); // guardian
-        regEnt(29, 31); // horse
-        regEnt(30, 32); // husk
-        regEnt(31, 33); // illusioner
-        regEnt(32, 34); // item
-        regEnt(33, 35); // item_frame
-        regEnt(34, 36); // fireball
-        regEnt(35, 37); // leash_knot
-        regEnt(36, 38); // llama
-        regEnt(37, 39); // llama_spit
-        regEnt(38, 40); // magma_cube
-        regEnt(39, 41); // minecart
-        regEnt(40, 42); // chest_minecart
-        regEnt(41, 43); // command_block_minecart
-        regEnt(42, 44); // furnace_minecart
-        regEnt(43, 45); // hopper_minecart
-        regEnt(44, 46); // spawner_minecart
-        regEnt(45, 47); // tnt_minecart
-        regEnt(46, 48); // mule
-        regEnt(47, 49); // mooshroom
-        regEnt(48, 6); // ocelot -> cat TODO Remap untamed ocelot to ocelot?
-        regEnt(49, 51); // painting
-        regEnt(50, 53); // parrot
-        regEnt(51, 54); // pig
-        regEnt(52, 55); // pufferfish
-        regEnt(53, 56); // zombie_pigman
-        regEnt(54, 57); // polar_bear
-        regEnt(55, 58); // tnt
-        regEnt(56, 59); // rabbit
-        regEnt(57, 60); // salmon
-        regEnt(58, 61); // sheep
-        regEnt(59, 62); // shulker
-        regEnt(60, 63); // shulker_bullet
-        regEnt(61, 64); // silverfish
-        regEnt(62, 65); // skeleton
-        regEnt(63, 66); // skeleton_horse
-        regEnt(64, 67); // slime
-        regEnt(65, 68); // small_fireball
-        regEnt(66, 69); // snowgolem
-        regEnt(67, 70); // snowball
-        regEnt(68, 71); // spectral_arrow
-        regEnt(69, 72); // spider
-        regEnt(70, 73); // squid
-        regEnt(71, 74); // stray
-        regEnt(72, 76); // tropical_fish
-        regEnt(73, 77); // turtle
-        regEnt(74, 78); // egg
-        regEnt(75, 79); // ender_pearl
-        regEnt(76, 80); // experience_bottle
-        regEnt(77, 81); // potion
-        regEnt(78, 83); // vex
-        regEnt(79, 84); // villager
-        regEnt(80, 85); // iron_golem
-        regEnt(81, 86); // vindicator
-        regEnt(82, 89); // witch
-        regEnt(83, 90); // wither
-        regEnt(84, 91); // wither_skeleton
-        regEnt(85, 92); // wither_skull
-        regEnt(86, 93); // wolf
-        regEnt(87, 94); // zombie
-        regEnt(88, 95); // zombie_horse
-        regEnt(89, 96); // zombie_villager
-        regEnt(90, 97); // phantom
-        regEnt(91, 99); // lightning_bolt
-        regEnt(92, 100); // player
-        regEnt(93, 101); // fishing_bobber
-        regEnt(94, 82); // trident
-    }
-
-    private static void regEnt(int type1_13, int type1_14) {
-        entityTypes.put(type1_13, type1_14);
-    }
-
-    public static Optional<Integer> getNewId(int type1_13) {
-        return Optional.ofNullable(entityTypes.get(type1_13));
-    }
-}

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_14to1_13_2/data/MappingData.java

@@ -1,32 +1,32 @@
 package us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data;
 
-import com.google.common.collect.BiMap;
-import com.google.common.collect.HashBiMap;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSet;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.MappingDataLoader;
 import us.myles.ViaVersion.api.data.Mappings;
+import us.myles.ViaVersion.util.Int2IntBiMap;
 
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
-import java.util.Set;
 
 public class MappingData {
-    public static final BiMap<Integer, Integer> oldToNewItems = HashBiMap.create();
+    public static final Int2IntBiMap oldToNewItems = new Int2IntBiMap();
     public static Mappings blockStateMappings;
     public static Mappings blockMappings;
     public static Mappings soundMappings;
-    public static Set<Integer> motionBlocking;
+    public static IntSet motionBlocking;
-    public static Set<Integer> nonFullBlocks;
+    public static IntSet nonFullBlocks;
 
     public static void init() {
         Via.getPlatform().getLogger().info("Loading 1.13.2 -> 1.14 mappings...");
         JsonObject mapping1_13_2 = MappingDataLoader.loadData("mapping-1.13.2.json", true);
         JsonObject mapping1_14 = MappingDataLoader.loadData("mapping-1.14.json", true);
 
+        oldToNewItems.defaultReturnValue(-1);
         blockStateMappings = new Mappings(mapping1_13_2.getAsJsonObject("blockstates"), mapping1_14.getAsJsonObject("blockstates"));
         blockMappings = new Mappings(mapping1_13_2.getAsJsonObject("blocks"), mapping1_14.getAsJsonObject("blocks"));
         MappingDataLoader.mapIdentifiers(oldToNewItems, mapping1_13_2.getAsJsonObject("items"), mapping1_14.getAsJsonObject("items"));
@@ -40,19 +40,19 @@ public class MappingData {
 
         JsonObject heightMapData = MappingDataLoader.loadData("heightMapData-1.14.json");
         JsonArray motionBlocking = heightMapData.getAsJsonArray("MOTION_BLOCKING");
-        us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data.MappingData.motionBlocking = new HashSet<>(motionBlocking.size());
+        MappingData.motionBlocking = new IntOpenHashSet(motionBlocking.size(), 1F);
         for (JsonElement blockState : motionBlocking) {
             String key = blockState.getAsString();
             Integer id = blockStateMap.get(key);
             if (id == null) {
                 Via.getPlatform().getLogger().warning("Unknown blockstate " + key + " :(");
             } else {
-                us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data.MappingData.motionBlocking.add(id);
+                MappingData.motionBlocking.add(id.intValue());
             }
         }
 
         if (Via.getConfig().isNonFullBlockLightFix()) {
-            nonFullBlocks = new HashSet<>();
+            nonFullBlocks = new IntOpenHashSet(1611, 1F);
             for (Map.Entry<String, JsonElement> blockstates : mapping1_13_2.getAsJsonObject("blockstates").entrySet()) {
                 final String state = blockstates.getValue().getAsString();
                 if (state.contains("_slab") || state.contains("_stairs") || state.contains("_wall["))

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_14to1_13_2/metadata/MetadataRewriter1_14To1_13_2.java

@@ -3,6 +3,7 @@ package us.myles.ViaVersion.protocols.protocol1_14to1_13_2.metadata;
 import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
+import us.myles.ViaVersion.api.entities.Entity1_13Types;
 import us.myles.ViaVersion.api.entities.Entity1_14Types;
 import us.myles.ViaVersion.api.entities.EntityType;
 import us.myles.ViaVersion.api.minecraft.VillagerData;
@@ -13,7 +14,6 @@ import us.myles.ViaVersion.api.rewriters.MetadataRewriter;
 import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.api.type.types.Particle;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.Protocol1_14To1_13_2;
-import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data.EntityTypeRewriter;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.packets.InventoryPackets;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.storage.EntityTracker1_14;
 
@@ -23,6 +23,7 @@ public class MetadataRewriter1_14To1_13_2 extends MetadataRewriter {
 
     public MetadataRewriter1_14To1_13_2(Protocol1_14To1_13_2 protocol) {
         super(protocol, EntityTracker1_14.class);
+        mapTypes(Entity1_13Types.EntityType.values(), Entity1_14Types.EntityType.class);
     }
 
     @Override
@@ -168,11 +169,6 @@ public class MetadataRewriter1_14To1_13_2 extends MetadataRewriter {
         }
     }
 
-    @Override
-    public int getNewEntityId(final int oldId) {
-        return EntityTypeRewriter.getNewId(oldId).orElse(oldId);
-    }
-
     @Override
     protected EntityType getTypeFromId(int type) {
         return Entity1_14Types.getTypeFromId(type);

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_14to1_13_2/packets/EntityPackets.java

@@ -14,7 +14,6 @@ import us.myles.ViaVersion.api.type.types.version.Types1_14;
 import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.ClientboundPackets1_13;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.ClientboundPackets1_14;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.Protocol1_14To1_13_2;
-import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.data.EntityTypeRewriter;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.metadata.MetadataRewriter1_14To1_13_2;
 import us.myles.ViaVersion.protocols.protocol1_14to1_13_2.storage.EntityTracker1_14;
 
@@ -50,7 +49,7 @@ public class EntityPackets {
                         int typeId = wrapper.get(Type.VAR_INT, 1);
 
                         Entity1_13Types.EntityType type1_13 = Entity1_13Types.getTypeFromId(typeId, true);
-                        typeId = EntityTypeRewriter.getNewId(type1_13.getId()).orElse(type1_13.getId());
+                        typeId = metadataRewriter.getNewEntityId(type1_13.getId());
                         Entity1_14Types.EntityType type1_14 = Entity1_14Types.getTypeFromId(typeId);
 
                         if (type1_14 != null) {

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_14to1_13_2/packets/InventoryPackets.java

@@ -271,8 +271,8 @@ public class InventoryPackets {
     }
 
     public static int getNewItemId(int id) {
-        Integer newId = MappingData.oldToNewItems.get(id);
+        int newId = MappingData.oldToNewItems.get(id);
-        if (newId == null) {
+        if (newId == -1) {
             Via.getPlatform().getLogger().warning("Missing 1.14 item for 1.13.2 item " + id);
             return 1;
         }
@@ -313,7 +313,7 @@ public class InventoryPackets {
     }
 
     public static int getOldItemId(int id) {
-        Integer oldId = MappingData.oldToNewItems.inverse().get(id);
+        int oldId = MappingData.oldToNewItems.inverse().get(id);
-        return oldId != null ? oldId : 1;
+        return oldId != -1 ? oldId : 1;
     }
 }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_15to1_14_4/data/MappingData.java

@@ -1,14 +1,13 @@
 package us.myles.ViaVersion.protocols.protocol1_15to1_14_4.data;
 
-import com.google.common.collect.BiMap;
-import com.google.common.collect.HashBiMap;
 import com.google.gson.JsonObject;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.MappingDataLoader;
 import us.myles.ViaVersion.api.data.Mappings;
+import us.myles.ViaVersion.util.Int2IntBiMap;
 
 public class MappingData {
-    public static BiMap<Integer, Integer> oldToNewItems = HashBiMap.create();
+    public static Int2IntBiMap oldToNewItems = new Int2IntBiMap();
     public static Mappings blockMappings;
     public static Mappings blockStateMappings;
     public static Mappings soundMappings;
@@ -19,6 +18,7 @@ public class MappingData {
         JsonObject mapping1_14 = MappingDataLoader.loadData("mapping-1.14.json", true);
         JsonObject mapping1_15 = MappingDataLoader.loadData("mapping-1.15.json", true);
 
+        oldToNewItems.defaultReturnValue(-1);
         blockStateMappings = new Mappings(mapping1_14.getAsJsonObject("blockstates"), mapping1_15.getAsJsonObject("blockstates"), diffmapping.getAsJsonObject("blockstates"));
         blockMappings = new Mappings(mapping1_14.getAsJsonObject("blocks"), mapping1_15.getAsJsonObject("blocks"));
         MappingDataLoader.mapIdentifiers(oldToNewItems, mapping1_14.getAsJsonObject("items"), mapping1_15.getAsJsonObject("items"));

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_15to1_14_4/packets/InventoryPackets.java

@@ -143,8 +143,8 @@ public class InventoryPackets {
     }
 
     public static int getNewItemId(int id) {
-        Integer newId = MappingData.oldToNewItems.get(id);
+        int newId = MappingData.oldToNewItems.get(id);
-        if (newId == null) {
+        if (newId == -1) {
             Via.getPlatform().getLogger().warning("Missing 1.15 item for 1.14 item " + id);
             return 1;
         }
@@ -152,7 +152,7 @@ public class InventoryPackets {
     }
 
     public static int getOldItemId(int id) {
-        Integer oldId = MappingData.oldToNewItems.inverse().get(id);
+        int oldId = MappingData.oldToNewItems.inverse().get(id);
-        return oldId != null ? oldId : 1;
+        return oldId != -1 ? oldId : 1;
     }
 }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_16to1_15_2/data/MappingData.java

@@ -1,17 +1,16 @@
 package us.myles.ViaVersion.protocols.protocol1_16to1_15_2.data;
 
-import com.google.common.collect.BiMap;
-import com.google.common.collect.HashBiMap;
 import com.google.gson.JsonObject;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.MappingDataLoader;
 import us.myles.ViaVersion.api.data.Mappings;
+import us.myles.ViaVersion.util.Int2IntBiMap;
 
 import java.util.HashMap;
 import java.util.Map;
 
 public class MappingData {
-    public static BiMap<Integer, Integer> oldToNewItems = HashBiMap.create();
+    public static Int2IntBiMap oldToNewItems = new Int2IntBiMap();
     public static Map<String, String> attributeMappings = new HashMap<>();
     public static Mappings blockMappings;
     public static Mappings blockStateMappings;
@@ -23,6 +22,7 @@ public class MappingData {
         JsonObject mapping1_15 = MappingDataLoader.loadData("mapping-1.15.json", true);
         JsonObject mapping1_16 = MappingDataLoader.loadData("mapping-1.16.json", true);
 
+        oldToNewItems.defaultReturnValue(-1);
         blockStateMappings = new Mappings(mapping1_15.getAsJsonObject("blockstates"), mapping1_16.getAsJsonObject("blockstates"), diffmapping.getAsJsonObject("blockstates"));
         blockMappings = new Mappings(mapping1_15.getAsJsonObject("blocks"), mapping1_16.getAsJsonObject("blocks"));
         MappingDataLoader.mapIdentifiers(oldToNewItems, mapping1_15.getAsJsonObject("items"), mapping1_16.getAsJsonObject("items"), diffmapping.getAsJsonObject("items"));

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_16to1_15_2/packets/InventoryPackets.java

@@ -206,8 +206,8 @@ public class InventoryPackets {
     }
 
     public static int getNewItemId(int id) {
-        Integer newId = MappingData.oldToNewItems.get(id);
+        int newId = MappingData.oldToNewItems.get(id);
-        if (newId == null) {
+        if (newId == -1) {
             Via.getPlatform().getLogger().warning("Missing 1.16 item for 1.15.2 item " + id);
             return 1;
         }
@@ -215,7 +215,7 @@ public class InventoryPackets {
     }
 
     public static int getOldItemId(int id) {
-        Integer oldId = MappingData.oldToNewItems.inverse().get(id);
+        int oldId = MappingData.oldToNewItems.inverse().get(id);
-        return oldId != null ? oldId : 1;
+        return oldId != -1 ? oldId : 1;
     }
 }

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/ItemRewriter.java

@@ -4,6 +4,8 @@ import com.github.steveice10.opennbt.tag.builtin.CompoundTag;
 import com.github.steveice10.opennbt.tag.builtin.ListTag;
 import com.github.steveice10.opennbt.tag.builtin.StringTag;
 import com.github.steveice10.opennbt.tag.builtin.Tag;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import us.myles.ViaVersion.api.minecraft.item.Item;
 
 import java.util.Collections;
@@ -17,7 +19,7 @@ public class ItemRewriter {
     private static final Map<String, Integer> POTION_NAME_TO_ID = new HashMap<>();
     private static final Map<Integer, String> POTION_ID_TO_NAME = new HashMap<>();
 
-    private static final Map<Integer, Integer> POTION_INDEX = new HashMap<>();
+    private static final Int2IntMap POTION_INDEX = new Int2IntOpenHashMap(36, 1F);
 
     static {
         /* Entities */
@@ -218,7 +220,7 @@ public class ItemRewriter {
             return str;
         }
         // hacky but it works :)
-        str = "\u00A7r" + str;
+        str = "§r" + str;
         return str;
     }
 
@@ -381,21 +383,21 @@ public class ItemRewriter {
             oldID -= 8192;
         }
 
-        Integer index = POTION_INDEX.get(oldID);
+        int index = POTION_INDEX.get(oldID);
-        if (index != null) {
+        if (index != -1) {
             return index;
         }
 
         oldID = POTION_NAME_TO_ID.get(potionNameFromDamage((short) oldID));
-        return (index = POTION_INDEX.get(oldID)) != null ? index : 0;
+        return (index = POTION_INDEX.get(oldID)) != -1 ? index : 0;
     }
 
-    private static void registerEntity(Integer id, String name) {
+    private static void registerEntity(int id, String name) {
         ENTTIY_ID_TO_NAME.put(id, name);
         ENTTIY_NAME_TO_ID.put(name, id);
     }
 
-    private static void registerPotion(Integer id, String name) {
+    private static void registerPotion(int id, String name) {
         POTION_INDEX.put(id, POTION_ID_TO_NAME.size());
         POTION_ID_TO_NAME.put(id, name);
         POTION_NAME_TO_ID.put(name, id);

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/metadata/MetaIndex.java

@@ -211,4 +211,3 @@ public enum MetaIndex {
     }
 
 }
-

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/sounds/Effect.java

@@ -1,14 +1,13 @@
 package us.myles.ViaVersion.protocols.protocol1_9to1_8.sounds;
 
-import java.util.HashMap;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
-import java.util.Map;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 
 public class Effect {
 
-    private static final Map<Integer, Integer> effects;
+    private static final Int2IntMap EFFECTS = new Int2IntOpenHashMap(17, 1F);
 
     static {
-        effects = new HashMap<>();
         addRewrite(1005, 1010); //Play music disc
         addRewrite(1003, 1005); //Iron door open
         addRewrite(1006, 1011); //Iron door close
@@ -26,19 +25,17 @@ public class Effect {
         addRewrite(1020, 1029); //Anvil break
         addRewrite(1021, 1030); //Anvil use
         addRewrite(1022, 1031); //Anvil land
-
     }
 
     public static int getNewId(int id) {
-        Integer newId = effects.get(id);
+        return EFFECTS.getOrDefault(id, id);
-        return newId != null ? newId : id;
     }
 
     public static boolean contains(int oldId) {
-        return effects.containsKey(oldId);
+        return EFFECTS.containsKey(oldId);
     }
 
     private static void addRewrite(int oldId, int newId) {
-        effects.put(oldId, newId);
+        EFFECTS.put(oldId, newId);
     }
 }

common/src/main/java/us/myles/ViaVersion/util/Int2IntBiMap.java

@@ -0,0 +1,128 @@
+package us.myles.ViaVersion.util;
+
+import com.google.common.base.Preconditions;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
+import it.unimi.dsi.fastutil.ints.IntSet;
+import it.unimi.dsi.fastutil.objects.ObjectSet;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+
+/**
+ * Simple wrapper class for two {@link Int2IntMap}s.
+ *
+ * @see #inverse() to get the inversed map
+ */
+public class Int2IntBiMap implements Int2IntMap {
+
+    private final Int2IntMap map;
+    private final Int2IntBiMap inverse;
+
+    public Int2IntBiMap() {
+        this.map = new Int2IntOpenHashMap();
+        this.inverse = new Int2IntBiMap(this);
+    }
+
+    private Int2IntBiMap(Int2IntBiMap inverse) {
+        this.map = new Int2IntOpenHashMap();
+        this.inverse = inverse;
+    }
+
+    /**
+     * @return the inverse of this bimap
+     */
+    public Int2IntBiMap inverse() {
+        return inverse;
+    }
+
+    /**
+     * Puts the key and value into the maps.
+     *
+     * @param key   key
+     * @param value value
+     * @return old value if present
+     * @throws IllegalArgumentException if the value already exists in the map
+     */
+    @Override
+    public int put(int key, int value) {
+        if (containsKey(key) && value == get(key)) return value;
+
+        Preconditions.checkArgument(!containsValue(value), "value already present: %s", value);
+        map.put(key, value);
+        inverse.map.put(value, key);
+        return defaultReturnValue();
+    }
+
+    @Override
+    public boolean remove(int key, int value) {
+        map.remove(key, value);
+        return inverse.map.remove(key, value);
+    }
+
+    @Override
+    public int get(int key) {
+        return map.get(key);
+    }
+
+    @Override
+    public void clear() {
+        map.clear();
+        inverse.map.clear();
+    }
+
+    @Override
+    public int size() {
+        return map.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return map.isEmpty();
+    }
+
+    @Override
+    @Deprecated
+    public void putAll(@NotNull Map<? extends Integer, ? extends Integer> m) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void defaultReturnValue(int rv) {
+        map.defaultReturnValue(rv);
+        inverse.map.defaultReturnValue(rv);
+    }
+
+    @Override
+    public int defaultReturnValue() {
+        return map.defaultReturnValue();
+    }
+
+    @Override
+    public ObjectSet<Entry> int2IntEntrySet() {
+        return map.int2IntEntrySet();
+    }
+
+    @Override
+    @NotNull
+    public IntSet keySet() {
+        return map.keySet();
+    }
+
+    @Override
+    @NotNull
+    public IntSet values() {
+        return inverse.map.keySet();
+    }
+
+    @Override
+    public boolean containsKey(int key) {
+        return map.containsKey(key);
+    }
+
+    @Override
+    public boolean containsValue(int value) {
+        return inverse.map.containsKey(value);
+    }
+}

jar/pom.xml

@@ -73,7 +73,44 @@
                 <configuration>
                     <createDependencyReducedPom>false</createDependencyReducedPom>
                     <minimizeJar>false</minimizeJar>
+                    <filters>
+                        <filter>
+                            <artifact>it.unimi.dsi:fastutil</artifact>
+                            <includes>
+                                <!-- We only want int and Object maps -->
+                                <include>it/unimi/dsi/fastutil/ints/*</include>
+                                <include>it/unimi/dsi/fastutil/objects/*</include>
+                                <include>it/unimi/dsi/fastutil/*.class</include>
+                            </includes>
+                            <excludes>
+                                <!-- Object types -->
+                                <exclude>it/unimi/dsi/fastutil/*/*Reference*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Boolean*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Byte*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Short*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Float*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Double*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Long*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Char*</exclude>
+                                <!-- Map types -->
+                                <exclude>it/unimi/dsi/fastutil/*/*Custom*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Linked*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Sorted*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Tree*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Heap*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Queue*</exclude>
+                                <!-- Crossing fingers -->
+                                <exclude>it/unimi/dsi/fastutil/*/*Big*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Synchronized*</exclude>
+                                <exclude>it/unimi/dsi/fastutil/*/*Unmodifiable*</exclude>
+                            </excludes>
+                        </filter>
+                    </filters>
                     <relocations>
+                        <relocation>
+                            <pattern>it.unimi.dsi.fastutil</pattern>
+                            <shadedPattern>us.myles.viaversion.libs.fastutil</shadedPattern>
+                        </relocation>
                         <relocation>
                             <pattern>com.github.steveice10.opennbt</pattern>
                             <shadedPattern>us.myles.viaversion.libs.opennbt</shadedPattern>