Eliminated file seeking and removed bytebuffers instead using raw memory under the assumption the system is always little endian

src/main/java/me/cortex/voxy/common/util/MemoryBuffer.java

@@ -40,6 +40,12 @@ public class MemoryBuffer extends TrackedObject {
         UnsafeUtil.memcpy(this.address, dst, this.size);
     }
 
+    public MemoryBuffer cpyFrom(long src) {
+        super.assertNotFreed();
+        UnsafeUtil.memcpy(src, this.address, this.size);
+        return this;
+    }
+
     @Override
     public void free() {
         super.free0();

src/main/java/me/cortex/voxy/commonImpl/importers/WorldImporter.java

@@ -3,6 +3,8 @@ package me.cortex.voxy.commonImpl.importers;
 import com.mojang.serialization.Codec;
 import me.cortex.voxy.common.util.ByteBufferBackedInputStream;
 import me.cortex.voxy.common.Logger;
+import me.cortex.voxy.common.util.MemoryBuffer;
+import me.cortex.voxy.common.util.UnsafeUtil;
 import me.cortex.voxy.common.voxelization.VoxelizedSection;
 import me.cortex.voxy.common.voxelization.WorldConversionFactory;
 import me.cortex.voxy.common.world.WorldEngine;
@@ -192,32 +194,39 @@ public class WorldImporter {
     }
 
     private void importRegionFile(Path file, int x, int z) throws IOException {
-        //if (true) return;
         try (var fileStream = FileChannel.open(file, StandardOpenOption.READ)) {
-            var sectorsSavesBB = MemoryUtil.memAlloc(8192);
+            var fileData = new MemoryBuffer(fileStream.size());
-            if (fileStream.read(sectorsSavesBB, 0) != 8192) {
+            if (fileStream.read(fileData.asByteBuffer(), 0) < 8192) {
+                fileData.free();
                 System.err.println("Header of region file invalid");
                 return;
             }
-            sectorsSavesBB.rewind();
+            this.importRegionFile(fileData, x, z);
-            var sectorsSaves = sectorsSavesBB.order(ByteOrder.BIG_ENDIAN).asIntBuffer();
+            fileData.free();
+        }
+    }
+
+
+    private void importRegionFile(MemoryBuffer regionFile, int x, int z) throws IOException {
+        //if (true) return;
 
         //Find and load all saved chunks
         for (int idx = 0; idx < 1024; idx++) {
-                int sectorMeta = sectorsSaves.get(idx);
+            int sectorMeta = Integer.reverseBytes(MemoryUtil.memGetInt(regionFile.address+idx*4));//Assumes little endian
             if (sectorMeta == 0) {
                 //Empty chunk
                 continue;
             }
             int sectorStart = sectorMeta>>>8;
             int sectorCount = sectorMeta&((1<<8)-1);
-                var data = MemoryUtil.memAlloc(sectorCount*4096).order(ByteOrder.BIG_ENDIAN);
+
-                fileStream.read(data, sectorStart*4096L);
+            //TODO: create memory copy for each section
-                data.flip();
+            var data = new MemoryBuffer(sectorCount*4096).cpyFrom(regionFile.address+sectorStart*4096L);
+
             boolean addedToQueue = false;
             {
-                    int m = data.getInt();
+                int m = Integer.reverseBytes(MemoryUtil.memGetInt(data.address));
-                    byte b = data.get();
+                byte b = MemoryUtil.memGetByte(data.address+4L);
                 if (m == 0) {
                     System.err.println("Chunk is allocated, but stream is missing");
                 } else {
@@ -227,8 +236,8 @@ public class WorldImporter {
                             System.err.println("Chunk has both internal and external streams");
                         }
                         System.err.println("Chunk has external stream which is not supported");
-                        } else if (n > data.remaining()) {
+                    } else if (n > data.size-5) {
-                            System.err.println("Chunk stream is truncated: expected "+n+" but read " + data.remaining());
+                        System.err.println("Chunk stream is truncated: expected "+n+" but read " + (data.size-5));
                     } else if (n < 0) {
                         System.err.println("Declared size of chunk is negative");
                     } else {
@@ -238,9 +247,30 @@ public class WorldImporter {
                                 return;
                             }
                             try {
-                                    try (var decompressedData = this.decompress(b, new ByteBufferBackedInputStream(data))) {
+                                try (var decompressedData = this.decompress(b, new InputStream() {
+                                    private long offset = 5;//For the initial 5 offset
+                                    @Override
+                                    public int read() {
+                                        return MemoryUtil.memGetByte(data.address + (this.offset++)) & 0xFF;
+                                    }
+
+                                    @Override
+                                    public int read(byte[] b, int off, int len) {
+                                        len = Math.min(len, this.available());
+                                        if (len == 0) {
+                                            return -1;
+                                        }
+                                        UnsafeUtil.memcpy(data.address+this.offset, len, b, off); this.offset+=len;
+                                        return len;
+                                    }
+
+                                    @Override
+                                    public int available() {
+                                        return (int) (data.size-this.offset);
+                                    }
+                                })) {
                                     if (decompressedData == null) {
-                                            System.err.println("Error decompressing chunk data");
+                                        Logger.error("Error decompressing chunk data");
                                     } else {
                                         var nbt = NbtIo.readCompound(decompressedData);
                                         this.importChunkNBT(nbt, x, z);
@@ -249,7 +279,7 @@ public class WorldImporter {
                             } catch (Exception e) {
                                 throw new RuntimeException(e);
                             } finally {
-                                    MemoryUtil.memFree(data);
+                                data.free();
                             }
                         });
                         this.totalChunks.incrementAndGet();
@@ -259,12 +289,9 @@ public class WorldImporter {
                 }
             }
             if (!addedToQueue) {
-                    MemoryUtil.memFree(data);
+                data.free();
             }
         }
-
-            MemoryUtil.memFree(sectorsSavesBB);
-        }
     }
 
     private DataInputStream decompress(byte flags, InputStream stream) throws IOException {
@@ -363,5 +390,4 @@ public class WorldImporter {
 
         this.world.insertUpdate(csec);
     }
-
 }