feat(java): reduce metastring hashcode payload for small string(<=16 bytes)

LICENSE

@@ -267,6 +267,7 @@ The text of each license is also included in licenses/LICENSE-[project].txt.
       java/fury-core/src/main/java/org/apache/fury/collection/IdentityMap.java
       java/fury-core/src/main/java/org/apache/fury/collection/IdentityObjectIntMap.java
       java/fury-core/src/main/java/org/apache/fury/collection/LongMap.java
+      java/fury-core/src/main/java/org/apache/fury/collection/LongLongMap.java
       java/fury-core/src/main/java/org/apache/fury/collection/ObjectIntMap.java
       java/fury-core/src/main/java/org/apache/fury/type/Generics.java
       java/fury-core/src/test/java/org/apache/fury/type/GenericsTest.java

go/fury/type.go

@@ -19,6 +19,7 @@ package fury
 
 import (
 	"fmt"
+	"github.com/apache/fury/go/fury/meta"
 	"hash/fnv"
 	"reflect"
 	"regexp"
@@ -136,6 +137,7 @@ const (
 	NotSupportCrossLanguage = 0
 	useStringValue          = 0
 	useStringId             = 1
+	SMALL_STRING_THRESHOLD  = 16
 )
 
 var (
@@ -551,14 +553,19 @@ func (r *typeResolver) writeMetaString(buffer *ByteBuffer, str string) error {
 		dynamicStringId := r.dynamicStringId
 		r.dynamicStringId += 1
 		r.dynamicStringToId[str] = dynamicStringId
-		buffer.WriteVarInt32(int32(len(str) << 1))
-		// TODO this hash should be unique, since we don't compare data equality for performance
-		h := fnv.New64a()
-		if _, err := h.Write([]byte(str)); err != nil {
-			return err
+		length := len(str)
+		buffer.WriteVarInt32(int32(length << 1))
+		if length <= SMALL_STRING_THRESHOLD {
+			buffer.WriteByte_(uint8(meta.UTF_8))
+		} else {
+			// TODO this hash should be unique, since we don't compare data equality for performance
+			h := fnv.New64a()
+			if _, err := h.Write([]byte(str)); err != nil {
+				return err
+			}
+			hash := int64(h.Sum64() & 0xffffffffffffff00)
+			buffer.WriteInt64(hash)
 		}
-		hash := int64(h.Sum64() & 0xffffffffffffff00)
-		buffer.WriteInt64(hash)
 		if len(str) > MaxInt16 {
 			return fmt.Errorf("too long string: %s", str)
 		}
@@ -573,8 +580,12 @@ func (r *typeResolver) readMetaString(buffer *ByteBuffer) (string, error) {
 	header := buffer.ReadVarInt32()
 	var length = int(header >> 1)
 	if header&0b1 == 0 {
-		// TODO support use computed hash
-		buffer.ReadInt64()
+		if length <= SMALL_STRING_THRESHOLD {
+			buffer.ReadByte_()
+		} else {
+			// TODO support use computed hash
+			buffer.ReadInt64()
+		}
 		str := string(buffer.ReadBinary(length))
 		dynamicStringId := r.dynamicStringId
 		r.dynamicStringId += 1

java/fury-core/src/main/java/org/apache/fury/collection/FuryObjectMap.java

@@ -51,6 +51,7 @@
  */
 @SuppressWarnings("unchecked")
 public class FuryObjectMap<K, V> {
+  static final long MASK_NUMBER = 0x9E3779B97F4A7C15L;
   static final Object dummy = new Object();
 
   public int size;
@@ -135,7 +136,7 @@ public FuryObjectMap(int initialCapacity, float loadFactor) {
    * {@code return item.hashCode() & mask;}
    */
   protected int place(K item) {
-    return (int) (item.hashCode() * 0x9E3779B97F4A7C15L >>> shift);
+    return (int) (item.hashCode() * MASK_NUMBER >>> shift);
   }
 
   /**

java/fury-core/src/main/java/org/apache/fury/collection/LongLongMap.java

@@ -0,0 +1,157 @@
+/* Copyright (c) 2008-2023, Nathan Sweet
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided with the distribution.
+ * - Neither the name of Esoteric Software nor the names of its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
+
+package org.apache.fury.collection;
+
+import static org.apache.fury.collection.FuryObjectMap.MASK_NUMBER;
+
+import org.apache.fury.annotation.Internal;
+import org.apache.fury.util.Preconditions;
+
+/**
+ * A fast linear hash probe based map whose key is two long values `(long k1, long k2)`. This map
+ * can avoid creating a java object for key to save memory/cpu cost.
+ */
+// The linear probed hash is derived from
+// https://github.com/EsotericSoftware/kryo/blob/135df69526615bb3f6b34846e58ba3fec3b631c3/src/com/esotericsoftware/kryo/util/IntMap.java.
+@SuppressWarnings("unchecked")
+@Internal
+public final class LongLongMap<V> {
+  private static final class LongLongKey {
+    private final long k1;
+
+    public LongLongKey(long k1, long k2) {
+      this.k1 = k1;
+      this.k2 = k2;
+    }
+
+    private final long k2;
+
+    @Override
+    public String toString() {
+      return "LongLongKey{" + "k1=" + k1 + ", k2=" + k2 + '}';
+    }
+  }
+
+  public int size;
+  LongLongKey[] keyTable;
+  V[] valueTable;
+  private final float loadFactor;
+  private int threshold;
+
+  private int shift;
+
+  private int mask;
+
+  /**
+   * Creates a new map with the specified initial capacity and load factor. This map will hold
+   * initialCapacity items before growing the backing table.
+   *
+   * @param initialCapacity If not a power of two, it is increased to the next nearest power of two.
+   */
+  public LongLongMap(int initialCapacity, float loadFactor) {
+    Preconditions.checkArgument(
+        0 <= loadFactor && loadFactor <= 1, "loadFactor %s must be > 0 and < 1", loadFactor);
+    this.loadFactor = loadFactor;
+    int tableSize = FuryObjectMap.tableSize(initialCapacity, loadFactor);
+    threshold = (int) (tableSize * loadFactor);
+    mask = tableSize - 1;
+    shift = Long.numberOfLeadingZeros(mask);
+    keyTable = new LongLongKey[tableSize];
+    valueTable = (V[]) new Object[tableSize];
+  }
+
+  private int place(long k1, long k2) {
+    return (int) ((k1 * 31 + k2) * MASK_NUMBER >>> shift);
+  }
+
+  /**
+   * Returns the index of the key if already present, else -(index + 1) for the next empty index.
+   * This can be overridden in this pacakge to compare for equality differently than {@link
+   * Object#equals(Object)}.
+   */
+  private int locateKey(long k1, long k2) {
+    LongLongKey[] keyTable = this.keyTable;
+    int mask = this.mask;
+    for (int i = place(k1, k2); ; i = i + 1 & mask) {
+      LongLongKey other = keyTable[i];
+      if (other == null) {
+        return -(i + 1); // Empty space is available.
+      }
+      if (other.k1 == k1 && other.k2 == k2) {
+        return i; // Same key was found.
+      }
+    }
+  }
+
+  public V put(long k1, long k2, V value) {
+    int i = locateKey(k1, k2);
+    if (i >= 0) { // Existing key was found.
+      V[] valueTable = this.valueTable;
+      V oldValue = valueTable[i];
+      valueTable[i] = value;
+      return oldValue;
+    }
+    i = -(i + 1); // Empty space was found.
+    keyTable[i] = new LongLongKey(k1, k2);
+    valueTable[i] = value;
+    if (++size >= threshold) {
+      resize(keyTable.length << 1);
+    }
+    return null;
+  }
+
+  public V get(long k1, long k2) {
+    LongLongKey[] keyTable = this.keyTable;
+    for (int i = place(k1, k2); ; i = i + 1 & mask) {
+      LongLongKey other = keyTable[i];
+      if (other == null) {
+        return null;
+      }
+      if (other.k1 == k1 && other.k2 == k2) {
+        return valueTable[i];
+      }
+    }
+  }
+
+  private void resize(int newSize) {
+    int oldCapacity = keyTable.length;
+    threshold = (int) (newSize * loadFactor);
+    mask = newSize - 1;
+    shift = Long.numberOfLeadingZeros(mask);
+    LongLongKey[] oldKeyTable = keyTable;
+    V[] oldValueTable = valueTable;
+    keyTable = new LongLongKey[newSize];
+    valueTable = (V[]) new Object[newSize];
+    if (size > 0) {
+      for (int i = 0; i < oldCapacity; i++) {
+        LongLongKey key = oldKeyTable[i];
+        if (key != null) {
+          for (int j = place(key.k1, key.k2); ; j = (j + 1) & mask) {
+            if (keyTable[j] == null) {
+              keyTable[j] = new LongLongKey(key.k1, key.k2);
+              valueTable[j] = oldValueTable[i];
+              break;
+            }
+          }
+        }
+      }
+    }
+  }
+}

java/fury-core/src/main/java/org/apache/fury/collection/LongMap.java

@@ -19,6 +19,8 @@
 
 package org.apache.fury.collection;
 
+import static org.apache.fury.collection.FuryObjectMap.MASK_NUMBER;
+
 import java.util.Arrays;
 
 // Derived from
@@ -141,7 +143,7 @@ public LongMap(LongMap<? extends V> map) {
    * {@code return item.hashCode() & mask;}
    */
   protected int place(long item) {
-    return (int) (item * 0x9E3779B97F4A7C15L >>> shift);
+    return (int) (item * MASK_NUMBER >>> shift);
   }
 
   /**

java/fury-core/src/main/java/org/apache/fury/collection/ObjectIntMap.java

@@ -19,6 +19,8 @@
 
 package org.apache.fury.collection;
 
+import static org.apache.fury.collection.FuryObjectMap.MASK_NUMBER;
+
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.BiConsumer;
@@ -59,7 +61,7 @@ public ObjectIntMap(int initialCapacity, float loadFactor) {
   }
 
   protected int place(K item) {
-    return (int) (item.hashCode() * 0x9E3779B97F4A7C15L >>> shift);
+    return (int) (item.hashCode() * MASK_NUMBER >>> shift);
   }
 
   int locateKey(K key) {

java/fury-core/src/main/java/org/apache/fury/io/BlockedStreamUtils.java

@@ -96,6 +96,7 @@ private static Object readFromChannel(
       Fury fury, ReadableByteChannel channel, Function<MemoryBuffer, Object> action) {
     try {
       MemoryBuffer buf = fury.getBuffer();
+      buf.readerIndex(0);
       ByteBuffer byteBuffer = ByteBuffer.allocate(4);
       byteBuffer.order(ByteOrder.LITTLE_ENDIAN);
       readByteBuffer(channel, byteBuffer, 4);

java/fury-core/src/main/java/org/apache/fury/memory/LittleEndian.java

@@ -72,6 +72,13 @@ public static long getInt64(Object o, long pos) {
     return Platform.IS_LITTLE_ENDIAN ? v : Long.reverseBytes(v);
   }
 
+  public static void putInt64(byte[] o, int index, long value) {
+    if (!Platform.IS_LITTLE_ENDIAN) {
+      value = Long.reverseBytes(value);
+    }
+    Platform.putLong(o, Platform.BYTE_ARRAY_OFFSET + index, value);
+  }
+
   public static void putFloat32(Object o, long pos, float value) {
     int v = Float.floatToRawIntBits(value);
     if (!Platform.IS_LITTLE_ENDIAN) {

java/fury-core/src/main/java/org/apache/fury/memory/MemoryBuffer.java

@@ -2174,6 +2174,42 @@ public void readBytes(byte[] dst) {
     readBytes(dst, 0, dst.length);
   }
 
+  /** Read {@code len} bytes into a long using little-endian order. */
+  public long readBytesAsInt64(int len) {
+    int readerIdx = readerIndex;
+    // use subtract to avoid overflow
+    int remaining = size - readerIdx;
+    if (remaining >= 8) {
+      readerIndex = readerIdx + len;
+      long v =
+          UNSAFE.getLong(heapMemory, address + readerIdx)
+              & (0xffffffffffffffffL >>> ((8 - len) * 8));
+      return LITTLE_ENDIAN ? v : Long.reverseBytes(v);
+    }
+    return slowReadBytesAsInt64(remaining, len);
+  }
+
+  private long slowReadBytesAsInt64(int remaining, int len) {
+    if (remaining < len) {
+      streamReader.fillBuffer(len - remaining);
+    }
+    int readerIdx = readerIndex;
+    readerIndex = readerIdx + len;
+    long result = 0;
+    byte[] heapMemory = this.heapMemory;
+    if (heapMemory != null) {
+      for (int i = 0, start = heapOffset + readerIdx; i < len; i++) {
+        result |= (((long) heapMemory[start + i]) & 0xff) << (i * 8);
+      }
+    } else {
+      long start = address + readerIdx;
+      for (int i = 0; i < len; i++) {
+        result |= ((long) UNSAFE.getByte(null, start + i) & 0xff) << (i * 8);
+      }
+    }
+    return result;
+  }
+
   public int read(ByteBuffer dst) {
     int readerIdx = readerIndex;
     int len = dst.remaining();

java/fury-core/src/main/java/org/apache/fury/resolver/ClassResolver.java

@@ -1619,6 +1619,8 @@ public void writeClassInternal(MemoryBuffer buffer, ClassInfo classInfo) {
     if (classInfo.classId != NO_CLASS_ID) {
       buffer.writeVarUint32(classInfo.classId << 1);
     } else {
+      // let the lowermost bit of next byte be set, so the deserialization can know
+      // whether need to read class by name in advance
       metaStringResolver.writeMetaStringBytesWithFlag(buffer, classInfo.packageNameBytes);
       metaStringResolver.writeMetaStringBytes(buffer, classInfo.classNameBytes);
     }
@@ -1634,6 +1636,8 @@ public Class<?> readClassInternal(MemoryBuffer buffer) {
     int header = buffer.readVarUint32Small14();
     final ClassInfo classInfo;
     if ((header & 0b1) != 0) {
+      // let the lowermost bit of next byte be set, so the deserialization can know
+      // whether need to read class by name in advance
       MetaStringBytes packageBytes = metaStringResolver.readMetaStringBytesWithFlag(buffer, header);
       MetaStringBytes simpleClassNameBytes = metaStringResolver.readMetaStringBytes(buffer);
       classInfo = loadBytesToClassInfo(packageBytes, simpleClassNameBytes);