Optimize MapBuffer representation (#57361)

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -1665,7 +1665,9 @@ public abstract interface class com/facebook/react/common/mapbuffer/MapBuffer :
 	public abstract fun getBoolean (I)Z
 	public abstract fun getCount ()I
 	public abstract fun getDouble (I)D
+	public abstract fun getDoubleBuffer (I)[D
 	public abstract fun getInt (I)I
+	public abstract fun getIntBuffer (I)[I
 	public abstract fun getKeyOffset (I)I
 	public abstract fun getLong (I)J
 	public abstract fun getMapBuffer (I)Lcom/facebook/react/common/mapbuffer/MapBuffer;
@@ -1680,9 +1682,12 @@ public final class com/facebook/react/common/mapbuffer/MapBuffer$Companion {
 public final class com/facebook/react/common/mapbuffer/MapBuffer$DataType : java/lang/Enum {
 	public static final field BOOL Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static final field DOUBLE Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
+	public static final field DOUBLE_BUFFER Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static final field INT Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
+	public static final field INT_BUFFER Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static final field LONG Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static final field MAP Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
+	public static final field MAP_BUFFER_LIST Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static final field STRING Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
 	public static fun getEntries ()Lkotlin/enums/EnumEntries;
 	public static fun valueOf (Ljava/lang/String;)Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
@@ -1691,10 +1696,13 @@ public final class com/facebook/react/common/mapbuffer/MapBuffer$DataType : java
 
 public abstract interface class com/facebook/react/common/mapbuffer/MapBuffer$Entry {
 	public abstract fun getBooleanValue ()Z
+	public abstract fun getDoubleBufferValue ()[D
 	public abstract fun getDoubleValue ()D
+	public abstract fun getIntBufferValue ()[I
 	public abstract fun getIntValue ()I
 	public abstract fun getKey ()I
 	public abstract fun getLongValue ()J
+	public abstract fun getMapBufferListValue ()Ljava/util/List;
 	public abstract fun getMapBufferValue ()Lcom/facebook/react/common/mapbuffer/MapBuffer;
 	public abstract fun getStringValue ()Ljava/lang/String;
 	public abstract fun getType ()Lcom/facebook/react/common/mapbuffer/MapBuffer$DataType;
@@ -1708,7 +1716,9 @@ public final class com/facebook/react/common/mapbuffer/ReadableMapBuffer : com/f
 	public fun getBoolean (I)Z
 	public fun getCount ()I
 	public fun getDouble (I)D
+	public fun getDoubleBuffer (I)[D
 	public fun getInt (I)I
+	public fun getIntBuffer (I)[I
 	public fun getKeyOffset (I)I
 	public fun getLong (I)J
 	public synthetic fun getMapBuffer (I)Lcom/facebook/react/common/mapbuffer/MapBuffer;

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/MapBuffer.kt

@@ -46,6 +46,9 @@ public interface MapBuffer : Iterable<MapBuffer.Entry> {
     STRING,
     MAP,
     LONG,
+    INT_BUFFER,
+    DOUBLE_BUFFER,
+    MAP_BUFFER_LIST,
   }
 
   /**
@@ -151,8 +154,8 @@ public interface MapBuffer : Iterable<MapBuffer.Entry> {
   public fun getMapBuffer(key: Int): MapBuffer
 
   /**
-   * Provides parsed [List<MapBuffer>] value if the entry for given key exists with [DataType.MAP]
-   * type
+   * Provides parsed [List<MapBuffer>] value if the entry for given key exists with
+   * [DataType.MAP_BUFFER_LIST] type
    *
    * @param key key to lookup [List<MapBuffer>] value for
    * @return value associated with the requested key
@@ -161,6 +164,30 @@ public interface MapBuffer : Iterable<MapBuffer.Entry> {
    */
   public fun getMapBufferList(key: Int): List<MapBuffer>
 
+  /**
+   * Provides parsed [IntArray] value if the entry for given key exists with [DataType.INT_BUFFER]
+   * type. This is a compact representation of a homogeneous list of ints with no per-element
+   * key/type overhead.
+   *
+   * @param key key to lookup the [IntArray] value for
+   * @return value associated with the requested key
+   * @throws IllegalArgumentException if the key doesn't exist
+   * @throws IllegalStateException if the data type doesn't match
+   */
+  public fun getIntBuffer(key: Int): IntArray
+
+  /**
+   * Provides parsed [DoubleArray] value if the entry for given key exists with
+   * [DataType.DOUBLE_BUFFER] type. This is a compact representation of a homogeneous list of
+   * doubles with no per-element key/type overhead.
+   *
+   * @param key key to lookup the [DoubleArray] value for
+   * @return value associated with the requested key
+   * @throws IllegalArgumentException if the key doesn't exist
+   * @throws IllegalStateException if the data type doesn't match
+   */
+  public fun getDoubleBuffer(key: Int): DoubleArray
+
   /** Iterable entry representing parsed MapBuffer values */
   public interface Entry {
     /**
@@ -213,5 +240,26 @@ public interface MapBuffer : Iterable<MapBuffer.Entry> {
      * @throws IllegalStateException if the data type doesn't match [DataType.MAP]
      */
     public val mapBufferValue: MapBuffer
+
+    /**
+     * Entry value represented as [IntArray]
+     *
+     * @throws IllegalStateException if the data type doesn't match [DataType.INT_BUFFER]
+     */
+    public val intBufferValue: IntArray
+
+    /**
+     * Entry value represented as [DoubleArray]
+     *
+     * @throws IllegalStateException if the data type doesn't match [DataType.DOUBLE_BUFFER]
+     */
+    public val doubleBufferValue: DoubleArray
+
+    /**
+     * Entry value represented as [List<MapBuffer>]
+     *
+     * @throws IllegalStateException if the data type doesn't match [DataType.MAP_BUFFER_LIST]
+     */
+    public val mapBufferListValue: List<MapBuffer>
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/ReadableMapBuffer.kt

@@ -51,13 +51,11 @@ private constructor(
       ReadableMapBuffer(buffer.duplicate().apply { position(offset) }, offset)
 
   private fun readHeader() {
-    // byte order
-    val storedAlignment = buffer.short
-    if (storedAlignment.toInt() != ALIGNMENT) {
-      buffer.order(ByteOrder.LITTLE_ENDIAN)
-    }
-    // count
-    count = readUnsignedShort(buffer.position()).toInt()
+    // The C++ writer always serializes in little-endian byte order. ByteBuffer
+    // defaults to big-endian and duplicate() resets the order, so set it
+    // explicitly on every instance, including nested clones.
+    buffer.order(ByteOrder.LITTLE_ENDIAN)
+    count = readUnsignedShort(offsetToMapBuffer).toInt()
   }
 
   /**
@@ -122,26 +120,27 @@ private constructor(
     return readIntValue(bufferPosition) == 1
   }
 
+  // Dynamic-data entries store [offset][byteLength] in the bucket's 8-byte
+  // value: getInt(bufferPosition) is the offset, getInt(bufferPosition + 4) is
+  // the byte length. The dynamic data section itself carries no length prefix.
   private fun readStringValue(bufferPosition: Int): String {
     val offset = offsetForDynamicData + buffer.getInt(bufferPosition)
-    val sizeOfString = buffer.getInt(offset)
+    val sizeOfString = buffer.getInt(bufferPosition + Int.SIZE_BYTES)
     val result = ByteArray(sizeOfString)
-    val stringOffset = offset + Int.SIZE_BYTES
-    buffer.position(stringOffset)
-    buffer[result, 0, sizeOfString]
+    buffer.position(offset)
+    buffer.get(result, 0, sizeOfString)
     return String(result)
   }
 
   private fun readMapBufferValue(position: Int): ReadableMapBuffer {
     val offset = offsetForDynamicData + buffer.getInt(position)
-    return cloneWithOffset(offset + Int.SIZE_BYTES)
+    return cloneWithOffset(offset)
   }
 
   private fun readMapBufferListValue(position: Int): List<ReadableMapBuffer> {
     val readMapBufferList = arrayListOf<ReadableMapBuffer>()
-    var offset = offsetForDynamicData + buffer.getInt(position)
-    val sizeMapBufferList = buffer.getInt(offset)
-    offset += Int.SIZE_BYTES
+    val offset = offsetForDynamicData + buffer.getInt(position)
+    val sizeMapBufferList = buffer.getInt(position + Int.SIZE_BYTES)
     var curLen = 0
     while (curLen < sizeMapBufferList) {
       val sizeMapBuffer = buffer.getInt(offset + curLen)
@@ -152,6 +151,20 @@ private constructor(
     return readMapBufferList
   }
 
+  private fun readIntBufferValue(bufferPosition: Int): IntArray {
+    val offset = offsetForDynamicData + buffer.getInt(bufferPosition)
+    val byteLength = buffer.getInt(bufferPosition + Int.SIZE_BYTES)
+    val count = byteLength / Int.SIZE_BYTES
+    return IntArray(count) { i -> buffer.getInt(offset + i * Int.SIZE_BYTES) }
+  }
+
+  private fun readDoubleBufferValue(bufferPosition: Int): DoubleArray {
+    val offset = offsetForDynamicData + buffer.getInt(bufferPosition)
+    val byteLength = buffer.getInt(bufferPosition + Int.SIZE_BYTES)
+    val count = byteLength / Double.SIZE_BYTES
+    return DoubleArray(count) { i -> buffer.getDouble(offset + i * Double.SIZE_BYTES) }
+  }
+
   private fun getKeyOffsetForBucketIndex(bucketIndex: Int): Int {
     return offsetToMapBuffer + HEADER_SIZE + BUCKET_SIZE * bucketIndex
   }
@@ -191,7 +204,13 @@ private constructor(
       readMapBufferValue(getTypedValueOffsetForKey(key, MapBuffer.DataType.MAP))
 
   override fun getMapBufferList(key: Int): List<ReadableMapBuffer> =
-      readMapBufferListValue(getTypedValueOffsetForKey(key, MapBuffer.DataType.MAP))
+      readMapBufferListValue(getTypedValueOffsetForKey(key, MapBuffer.DataType.MAP_BUFFER_LIST))
+
+  override fun getIntBuffer(key: Int): IntArray =
+      readIntBufferValue(getTypedValueOffsetForKey(key, MapBuffer.DataType.INT_BUFFER))
+
+  override fun getDoubleBuffer(key: Int): DoubleArray =
+      readDoubleBufferValue(getTypedValueOffsetForKey(key, MapBuffer.DataType.DOUBLE_BUFFER))
 
   override fun hashCode(): Int {
     buffer.rewind()
@@ -229,6 +248,9 @@ private constructor(
             append('"')
           }
           MapBuffer.DataType.MAP -> append(entry.mapBufferValue.toString())
+          MapBuffer.DataType.INT_BUFFER -> append(entry.intBufferValue.contentToString())
+          MapBuffer.DataType.DOUBLE_BUFFER -> append(entry.doubleBufferValue.contentToString())
+          MapBuffer.DataType.MAP_BUFFER_LIST -> append(entry.mapBufferListValue.toString())
         }
       }
     }
@@ -311,16 +333,31 @@ private constructor(
         assertType(MapBuffer.DataType.MAP)
         return readMapBufferValue(bucketOffset + VALUE_OFFSET)
       }
+
+    override val intBufferValue: IntArray
+      get() {
+        assertType(MapBuffer.DataType.INT_BUFFER)
+        return readIntBufferValue(bucketOffset + VALUE_OFFSET)
+      }
+
+    override val doubleBufferValue: DoubleArray
+      get() {
+        assertType(MapBuffer.DataType.DOUBLE_BUFFER)
+        return readDoubleBufferValue(bucketOffset + VALUE_OFFSET)
+      }
+
+    override val mapBufferListValue: List<MapBuffer>
+      get() {
+        assertType(MapBuffer.DataType.MAP_BUFFER_LIST)
+        return readMapBufferListValue(bucketOffset + VALUE_OFFSET)
+      }
   }
 
   public companion object {
-    // Value used to verify if the data is serialized with LittleEndian order.
-    private const val ALIGNMENT = 0xFE
-
-    // 8 bytes = 2 (alignment) + 2 (count) + 4 (size)
-    private const val HEADER_SIZE = 8
+    // 2 bytes = 2 (count)
+    private const val HEADER_SIZE = 2
 
-    // 10 bytes = 2 (key) + 2 (type) + 8 (value)
+    // 12 bytes = 2 (key) + 2 (type) + 8 (value)
     private const val BUCKET_SIZE = 12
 
     // 2 bytes = 2 (key)

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/WritableMapBuffer.kt

@@ -126,6 +126,10 @@ internal class WritableMapBuffer : MapBuffer {
 
   override fun getMapBufferList(key: Int): List<MapBuffer> = verifyValue(key, values.get(key))
 
+  override fun getIntBuffer(key: Int): IntArray = verifyValue(key, values.get(key))
+
+  override fun getDoubleBuffer(key: Int): DoubleArray = verifyValue(key, values.get(key))
+
   /** Generalizes verification of the value types based on the requested type. */
   private inline fun <reified T> verifyValue(key: Int, value: Any?): T {
     require(value != null) { "Key not found: $key" }
@@ -176,6 +180,15 @@ internal class WritableMapBuffer : MapBuffer {
 
     override val mapBufferValue: MapBuffer
       get() = verifyValue(key, values.valueAt(index))
+
+    override val intBufferValue: IntArray
+      get() = verifyValue(key, values.valueAt(index))
+
+    override val doubleBufferValue: DoubleArray
+      get() = verifyValue(key, values.valueAt(index))
+
+    override val mapBufferListValue: List<MapBuffer>
+      get() = verifyValue(key, values.valueAt(index))
   }
 
   /*