Cache identifiers files

api/src/main/java/com/viaversion/viaversion/api/data/Int2IntMapBiMappings.java

@@ -74,6 +74,7 @@ public class Int2IntMapBiMappings implements BiMappings {
     @Override
     public Mappings createInverse() {
         final Int2IntBiMap inverseCopy = new Int2IntBiHashMap(inverse.mappings.size());
+        inverseCopy.defaultReturnValue(-1);
         for (final Int2IntMap.Entry entry : inverse.mappings.int2IntEntrySet()) {
             inverseCopy.put(entry.getIntKey(), entry.getIntValue());
         }

api/src/main/java/com/viaversion/viaversion/api/data/Int2IntMapMappings.java

@@ -66,6 +66,7 @@ public class Int2IntMapMappings implements Mappings {
     @Override
     public Mappings createInverse() {
         final Int2IntMap inverse = new Int2IntOpenHashMap();
+        inverse.defaultReturnValue(-1);
         for (final Int2IntMap.Entry entry : mappings.int2IntEntrySet()) {
             inverse.put(entry.getIntValue(), entry.getIntKey());
         }

api/src/main/java/com/viaversion/viaversion/api/data/IntArrayMappings.java

@@ -67,8 +67,10 @@ public class IntArrayMappings implements Mappings {
         Arrays.fill(inverse, -1);
         for (int id = 0; id < mappings.length; id++) {
             final int mappedId = mappings[id];
+            if (mappedId != -1) {
                 inverse[mappedId] = id;
             }
+        }
         return of(inverse, mappings.length);
     }
 

api/src/main/java/com/viaversion/viaversion/api/data/MappingDataBase.java

@@ -75,9 +75,8 @@ public class MappingDataBase implements MappingData {
         paintingMappings = loadMappings(data, "paintings");
         itemMappings = loadBiMappings(data, "items");
 
-        // TODO Don't load one file multiple times
+        final CompoundTag unmappedIdentifierData = MappingDataLoader.loadNBT("identifiers-" + unmappedVersion + ".nbt", true);
-        final CompoundTag unmappedIdentifierData = MappingDataLoader.loadNBT("identifiers-" + unmappedVersion + ".nbt");
+        final CompoundTag mappedIdentifierData = MappingDataLoader.loadNBT("identifiers-" + mappedVersion + ".nbt", true);
-        final CompoundTag mappedIdentifierData = MappingDataLoader.loadNBT("identifiers-" + mappedVersion + ".nbt");
         if (unmappedIdentifierData != null && mappedIdentifierData != null) {
             entityMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "entities");
             argumentTypeMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "argumenttypes");

api/src/main/java/com/viaversion/viaversion/api/data/MappingDataLoader.java

@@ -44,6 +44,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.stream.Collectors;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -54,9 +55,17 @@ public final class MappingDataLoader {
     private static final byte SHIFTS_ID = 1;
     private static final byte CHANGES_ID = 2;
     private static final byte IDENTITY_ID = 3;
+    private static final Map<String, CompoundTag> MAPPINGS_CACHE = new HashMap<>();
+    private static boolean cacheValid = true;
 
+    @Deprecated/*(forRemoval = true)*/
     public static void enableMappingsCache() {
-        //TODO
+        // Always enabled
+    }
+
+    public static void clearCache() {
+        MAPPINGS_CACHE.clear();
+        cacheValid = false;
     }
 
     /**
@@ -100,7 +109,29 @@ public final class MappingDataLoader {
         }
     }
 
+    public static @Nullable CompoundTag loadNBT(final String name, final boolean cache) {
+        if (!cacheValid) {
+            return loadNBTFromFile(name);
+        }
+
+        CompoundTag data = MAPPINGS_CACHE.get(name);
+        if (data != null) {
+            return data;
+        }
+
+        data = loadNBTFromFile(name);
+
+        if (cache && data != null) {
+            MAPPINGS_CACHE.put(name, data);
+        }
+        return data;
+    }
+
     public static @Nullable CompoundTag loadNBT(final String name) {
+        return loadNBT(name, false);
+    }
+
+    private static @Nullable CompoundTag loadNBTFromFile(final String name) {
         final InputStream resource = getResource(name);
         if (resource == null) {
             return null;

common/src/main/java/com/viaversion/viaversion/protocol/ProtocolManagerImpl.java

@@ -23,6 +23,7 @@ import com.google.common.collect.Range;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.data.MappingDataLoader;
 import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.protocol.ProtocolManager;
 import com.viaversion.viaversion.api.protocol.ProtocolPathEntry;
@@ -517,6 +518,9 @@ public class ProtocolManagerImpl implements ProtocolManager {
         mappingLoaderExecutor = null;
         mappingLoaderFutures.clear();
         mappingLoaderFutures = null;
+
+        // Clear cached mapping files
+        MappingDataLoader.clearCache();
     }
 
     private Function<Throwable, Void> mappingLoaderThrowable(Class<? extends Protocol> protocolClass) {