Replace ByteBuffer use with Buffer and SingleBuffer

Author: silvanocerza

src/main/java/com/maxmind/db/BufferHolder.java

@@ -6,29 +6,27 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.RandomAccessFile;
-import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
-import java.nio.channels.FileChannel.MapMode;
 
 final class BufferHolder {
     // DO NOT PASS OUTSIDE THIS CLASS. Doing so will remove thread safety.
-    private final ByteBuffer buffer;
+    private final Buffer buffer;
 
     BufferHolder(File database, FileMode mode) throws IOException {
         try (
             final RandomAccessFile file = new RandomAccessFile(database, "r");
             final FileChannel channel = file.getChannel()
         ) {
             if (mode == FileMode.MEMORY) {
-                final ByteBuffer buf = ByteBuffer.wrap(new byte[(int) channel.size()]);
-                if (channel.read(buf) != buf.capacity()) {
+                final SingleBuffer buf = SingleBuffer.wrap(new byte[(int) channel.size()]);
+                if (buf.readFrom(channel) != buf.capacity()) {
                     throw new IOException("Unable to read "
                         + database.getName()
                         + " into memory. Unexpected end of stream.");
                 }
                 this.buffer = buf.asReadOnlyBuffer();
             } else {
-                this.buffer = channel.map(MapMode.READ_ONLY, 0, channel.size()).asReadOnlyBuffer();
+                this.buffer = SingleBuffer.mapFromChannel(channel);
             }
         }
     }
@@ -50,14 +48,14 @@ final class BufferHolder {
         while (-1 != (br = stream.read(bytes))) {
             baos.write(bytes, 0, br);
         }
-        this.buffer = ByteBuffer.wrap(baos.toByteArray()).asReadOnlyBuffer();
+        this.buffer = SingleBuffer.wrap(baos.toByteArray()).asReadOnlyBuffer();
     }
 
     /*
-     * Returns a duplicate of the underlying ByteBuffer. The returned ByteBuffer
+     * Returns a duplicate of the underlying Buffer. The returned Buffer
      * should not be shared between threads.
      */
-    ByteBuffer get() {
+    Buffer get() {
         // The Java API docs for buffer state:
         //
         //     Buffers are not safe for use by multiple concurrent threads. If a buffer is to be
@@ -70,7 +68,7 @@ ByteBuffer get() {
         // * https://github.com/maxmind/MaxMind-DB-Reader-java/issues/65
         // * https://github.com/maxmind/MaxMind-DB-Reader-java/pull/69
         //
-        // Given that we are not modifying the original ByteBuffer in any way and all currently
+        // Given that we are not modifying the original Buffer in any way and all currently
         // known and most reasonably imaginable implementations of duplicate() only do read
         // operations on the original buffer object, the risk of not synchronizing this call seems
         // relatively low and worth taking for the performance benefit when lookups are being done

src/main/java/com/maxmind/db/CacheKey.java

@@ -10,5 +10,5 @@
  * @param cls the class of the value
  * @param type the type of the value
  */
-public record CacheKey<T>(int offset, Class<T> cls, java.lang.reflect.Type type) {
+public record CacheKey<T>(long offset, Class<T> cls, java.lang.reflect.Type type) {
 }

src/main/java/com/maxmind/db/CtrlData.java

@@ -1,4 +1,4 @@
 package com.maxmind.db;
 
-record CtrlData(Type type, int ctrlByte, int offset, int size) {
+record CtrlData(Type type, int ctrlByte, long offset, int size) {
 }

src/main/java/com/maxmind/db/Decoder.java

@@ -34,11 +34,11 @@ class Decoder {
 
     private final CharsetDecoder utfDecoder = UTF_8.newDecoder();
 
-    private final ByteBuffer buffer;
+    private final Buffer buffer;
 
     private final ConcurrentHashMap<Class<?>, CachedConstructor<?>> constructors;
 
-    Decoder(NodeCache cache, ByteBuffer buffer, long pointerBase) {
+    Decoder(NodeCache cache, Buffer buffer, long pointerBase) {
         this(
             cache,
             buffer,
@@ -49,7 +49,7 @@ class Decoder {
 
     Decoder(
         NodeCache cache,
-        ByteBuffer buffer,
+        Buffer buffer,
         long pointerBase,
         ConcurrentHashMap<Class<?>, CachedConstructor<?>> constructors
     ) {
@@ -61,7 +61,7 @@ class Decoder {
 
     private final NodeCache.Loader cacheLoader = this::decode;
 
-    <T> T decode(int offset, Class<T> cls) throws IOException {
+    <T> T decode(long offset, Class<T> cls) throws IOException {
         if (offset >= this.buffer.capacity()) {
             throw new InvalidDatabaseException(
                 "The MaxMind DB file's data section contains bad data: "
@@ -73,7 +73,7 @@ <T> T decode(int offset, Class<T> cls) throws IOException {
     }
 
     private <T> DecodedValue decode(CacheKey<T> key) throws IOException {
-        int offset = key.offset();
+        long offset = key.offset();
         if (offset >= this.buffer.capacity()) {
             throw new InvalidDatabaseException(
                 "The MaxMind DB file's data section contains bad data: "
@@ -132,8 +132,8 @@ private <T> DecodedValue decode(Class<T> cls, java.lang.reflect.Type genericType
 
     DecodedValue decodePointer(long pointer, Class<?> cls, java.lang.reflect.Type genericType)
             throws IOException {
-        int targetOffset = (int) pointer;
-        int position = buffer.position();
+        long targetOffset = pointer;
+        long position = buffer.position();
 
         CacheKey<?> key = new CacheKey<>(targetOffset, cls, genericType);
         DecodedValue o = cache.get(key, cacheLoader);
@@ -185,10 +185,10 @@ private <T> Object decodeByType(
         }
     }
 
-    private String decodeString(int size) throws CharacterCodingException {
-        int oldLimit = buffer.limit();
+    private String decodeString(long size) throws CharacterCodingException {
+        long oldLimit = buffer.limit();
         buffer.limit(buffer.position() + size);
-        String s = utfDecoder.decode(buffer).toString();
+        String s = buffer.decode(utfDecoder);
         buffer.limit(oldLimit);
         return s;
     }
@@ -221,7 +221,7 @@ private int decodeInteger(int base, int size) {
         return Decoder.decodeInteger(this.buffer, base, size);
     }
 
-    static int decodeInteger(ByteBuffer buffer, int base, int size) {
+    static int decodeInteger(Buffer buffer, int base, int size) {
         int integer = base;
         for (int i = 0; i < size; i++) {
             integer = (integer << 8) | (buffer.get() & 0xFF);
@@ -412,7 +412,7 @@ private <T> Object decodeMapIntoObject(int size, Class<T> cls)
 
             Integer parameterIndex = parameterIndexes.get(key);
             if (parameterIndex == null) {
-                int offset = this.nextValueOffset(this.buffer.position(), 1);
+                long offset = this.nextValueOffset(this.buffer.position(), 1);
                 this.buffer.position(offset);
                 continue;
             }
@@ -485,7 +485,7 @@ private static <T> String getParameterName(
                 + " is not annotated with MaxMindDbParameter.");
     }
 
-    private int nextValueOffset(int offset, int numberToSkip)
+    private long nextValueOffset(long offset, int numberToSkip)
         throws InvalidDatabaseException {
         if (numberToSkip == 0) {
             return offset;
@@ -518,7 +518,7 @@ private int nextValueOffset(int offset, int numberToSkip)
         return nextValueOffset(offset, numberToSkip - 1);
     }
 
-    private CtrlData getCtrlData(int offset)
+    private CtrlData getCtrlData(long offset)
         throws InvalidDatabaseException {
         if (offset >= this.buffer.capacity()) {
             throw new InvalidDatabaseException(
@@ -566,7 +566,7 @@ private byte[] getByteArray(int length) {
         return Decoder.getByteArray(this.buffer, length);
     }
 
-    private static byte[] getByteArray(ByteBuffer buffer, int length) {
+    private static byte[] getByteArray(Buffer buffer, int length) {
         byte[] bytes = new byte[length];
         buffer.get(bytes);
         return bytes;

src/main/java/com/maxmind/db/Networks.java

@@ -19,7 +19,7 @@ public final class Networks<T> implements Iterator<DatabaseRecord<T>> {
     private final Stack<NetworkNode> nodes;
     private NetworkNode lastNode;
     private final boolean includeAliasedNetworks;
-    private final ByteBuffer buffer; /* Stores the buffer for Next() calls */
+    private final Buffer buffer; /* Stores the buffer for Next() calls */
     private final Class<T> typeParameterClass;
 
     /**

src/main/java/com/maxmind/db/Reader.java

@@ -128,8 +128,8 @@ private Reader(BufferHolder bufferHolder, String name, NodeCache cache) throws I
         }
         this.cache = cache;
 
-        ByteBuffer buffer = bufferHolder.get();
-        int start = this.findMetadataStart(buffer, name);
+        Buffer buffer = bufferHolder.get();
+        long start = this.findMetadataStart(buffer, name);
 
         Decoder metadataDecoder = new Decoder(this.cache, buffer, start);
         this.metadata = metadataDecoder.decode(start, Metadata.class);
@@ -177,7 +177,7 @@ public <T> DatabaseRecord<T> getRecord(InetAddress ipAddress, Class<T> cls)
         int record = traverseResult[0];
 
         int nodeCount = this.metadata.getNodeCount();
-        ByteBuffer buffer = this.getBufferHolder().get();
+        Buffer buffer = this.getBufferHolder().get();
         T dataRecord = null;
         if (record > nodeCount) {
             // record is a data pointer
@@ -264,7 +264,7 @@ private int startNode(int bitLength) {
         return 0;
     }
 
-    private int findIpV4StartNode(ByteBuffer buffer)
+    private int findIpV4StartNode(Buffer buffer)
         throws InvalidDatabaseException {
         if (this.metadata.getIpVersion() == 4) {
             return 0;
@@ -337,7 +337,7 @@ public <T> Networks<T> networksWithin(
      */
     private int[] traverseTree(byte[] ip, int bitCount)
         throws ClosedDatabaseException, InvalidDatabaseException {
-        ByteBuffer buffer = this.getBufferHolder().get();
+        Buffer buffer = this.getBufferHolder().get();
         int bitLength = ip.length * 8;
         int record = this.startNode(bitLength);
         int nodeCount = this.metadata.getNodeCount();
@@ -355,7 +355,7 @@ record = this.readNode(buffer, record, bit);
         return new int[]{record, i};
     }
 
-    int readNode(ByteBuffer buffer, int nodeNumber, int index)
+    int readNode(Buffer buffer, int nodeNumber, int index)
             throws InvalidDatabaseException {
         // index is the index of the record within the node, which
         // can either be 0 or 1.
@@ -389,7 +389,7 @@ int readNode(ByteBuffer buffer, int nodeNumber, int index)
     }
 
     <T> T resolveDataPointer(
-        ByteBuffer buffer,
+        Buffer buffer,
         int pointer,
         Class<T> cls
     ) throws IOException {
@@ -421,12 +421,12 @@ <T> T resolveDataPointer(
      * are much faster algorithms (e.g., Boyer-Moore) for this if speed is ever
      * an issue, but I suspect it won't be.
      */
-    private int findMetadataStart(ByteBuffer buffer, String databaseName)
+    private long findMetadataStart(Buffer buffer, String databaseName)
         throws InvalidDatabaseException {
-        int fileSize = buffer.capacity();
+        long fileSize = buffer.capacity();
 
         FILE:
-        for (int i = 0; i < fileSize - METADATA_START_MARKER.length + 1; i++) {
+        for (long i = 0; i < fileSize - METADATA_START_MARKER.length + 1; i++) {
             for (int j = 0; j < METADATA_START_MARKER.length; j++) {
                 byte b = buffer.get(fileSize - i - j - 1);
                 if (b != METADATA_START_MARKER[METADATA_START_MARKER.length - j

src/test/java/com/maxmind/db/DecoderTest.java

@@ -399,7 +399,7 @@ public void testArrays() throws IOException {
 
     @Test
     public void testInvalidControlByte() {
-        ByteBuffer buffer = ByteBuffer.wrap(new byte[] {0x0, 0xF});
+        SingleBuffer buffer = SingleBuffer.wrap(new byte[] {0x0, 0xF});
 
         Decoder decoder = new Decoder(new CHMCache(), buffer, 0);
         InvalidDatabaseException ex = assertThrows(
@@ -418,7 +418,7 @@ private static <T> void testTypeDecoding(Type type, Map<T, byte[]> tests)
             byte[] input = entry.getValue();
 
             String desc = "decoded " + type.name() + " - " + expect;
-            ByteBuffer buffer = ByteBuffer.wrap(input);
+            SingleBuffer buffer = SingleBuffer.wrap(input);
 
             Decoder decoder = new TestDecoder(cache, buffer, 0);
 

src/test/java/com/maxmind/db/TestDecoder.java

@@ -5,7 +5,7 @@
 
 final class TestDecoder extends Decoder {
 
-    TestDecoder(NodeCache cache, ByteBuffer buffer, long pointerBase) {
+    TestDecoder(NodeCache cache, SingleBuffer buffer, long pointerBase) {
         super(cache, buffer, pointerBase);
     }