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new 3b3f17d03 feat(java): long array serializer support varint encoding
(#3115)
3b3f17d03 is described below
commit 3b3f17d03e5133a81a82994e680e9abd3dd551f7
Author: Pigsy-Monk <[email protected]>
AuthorDate: Sat Jan 10 01:41:03 2026 +0800
feat(java): long array serializer support varint encoding (#3115)
# What does this PR do?
This PR adds variable-length encoding serializers for `long[]` arrays in
Java, which provides more space-efficient serialization for arrays
containing many small values.
## Changes:
- **Enhance `LongArraySerializer` with variable-length encoding
support**: Added `supportVarLenEncoding` parameter to
`LongArraySerializer` constructor, allowing it to optionally use
variable-length encoding when enabled.
- **Add comprehensive test cases**:
- `testVariableLengthLongArray()`: Tests serialization/deserialization
of long arrays with various value ranges (empty, small, mixed, large,
negative values)
- `testVariableLengthEncodingEfficiencyForSmallValues()`: Demonstrates
that variable-length encoding produces significantly smaller serialized
data (50%+ reduction) for arrays containing many small values
## Test Details:
- **testVariableLengthLongArray**:
- Tests empty arrays
- Tests arrays with small values (0-255)
- Tests arrays with mixed small and large values (including
`Long.MAX_VALUE` and `Long.MIN_VALUE`)
- Tests arrays with negative values
- Tests large arrays (1000 elements) with many small values
- **testVariableLengthEncodingEfficiencyForSmallValues**:
- Compares serialization size between fixed-length encoding (8 bytes per
long element) and variable-length encoding (1-2 bytes per small element)
- Tests with arrays containing values 0-127 (optimal for variable-length
encoding)
- Tests with arrays containing values 0-1023 (still benefits from
variable-length encoding)
- Verifies at least 50% size reduction for small values
- Outputs detailed efficiency metrics (bytes, bytes per element,
percentage reduction)
## Performance Benefits:
For arrays containing many small values:
- **Fixed-length encoding**: 8 bytes per `long` element + overhead
- **Variable-length encoding**: 1-2 bytes per small `long` element +
overhead
- **Space savings**: Up to 75%+ reduction for arrays with values in the
0-127 range
## Related Issues:
- Addresses the need for more efficient serialization of primitive
arrays with small values
- Enables space-optimized serialization for use cases like sparse
arrays, indices, counters, etc.
## Does this PR introduce any user-facing change?
**No**, this PR only adds new serializer classes and test cases. The
default serializers remain unchanged. Users can opt-in to
variable-length encoding by using the enhanced `LongArraySerializer`
with `supportVarLenEncoding=true`.
---
.../apache/fory/serializer/ArraySerializers.java | 45 +++++-
.../fory/serializer/ArraySerializersTest.java | 166 +++++++++++++++++++++
2 files changed, 210 insertions(+), 1 deletion(-)
diff --git
a/java/fory-core/src/main/java/org/apache/fory/serializer/ArraySerializers.java
b/java/fory-core/src/main/java/org/apache/fory/serializer/ArraySerializers.java
index 5042f8058..262798e93 100644
---
a/java/fory-core/src/main/java/org/apache/fory/serializer/ArraySerializers.java
+++
b/java/fory-core/src/main/java/org/apache/fory/serializer/ArraySerializers.java
@@ -23,6 +23,8 @@ import java.lang.reflect.Array;
import java.util.Arrays;
import org.apache.fory.Fory;
import org.apache.fory.config.CompatibleMode;
+import org.apache.fory.config.Config;
+import org.apache.fory.config.LongEncoding;
import org.apache.fory.memory.MemoryBuffer;
import org.apache.fory.memory.Platform;
import org.apache.fory.resolver.ClassInfo;
@@ -495,6 +497,10 @@ public class ArraySerializers {
@Override
public void write(MemoryBuffer buffer, long[] value) {
if (fory.getBufferCallback() == null) {
+ if (compressArray(fory.getConfig())) {
+ writeInt64s(buffer, value, fory.getConfig().longEncoding());
+ return;
+ }
int size = Math.multiplyExact(value.length, 8);
buffer.writePrimitiveArrayWithSize(value, Platform.LONG_ARRAY_OFFSET,
size);
} else {
@@ -521,7 +527,9 @@ public class ArraySerializers {
}
return values;
}
-
+ if (compressArray(fory.getConfig())) {
+ return readInt64s(buffer, fory.getConfig().longEncoding());
+ }
int size = buffer.readVarUint32Small7();
int numElements = size / 8;
long[] values = new long[numElements];
@@ -530,6 +538,41 @@ public class ArraySerializers {
}
return values;
}
+
+ private boolean compressArray(Config config) {
+ return config.compressLongArray() && config.longEncoding() !=
LongEncoding.LE_RAW_BYTES;
+ }
+
+ private void writeInt64s(MemoryBuffer buffer, long[] value, LongEncoding
longEncoding) {
+ int length = value.length;
+ buffer.writeVarUint32Small7(length);
+
+ if (longEncoding == LongEncoding.SLI) {
+ for (int i = 0; i < length; i++) {
+ buffer.writeSliInt64(value[i]);
+ }
+ return;
+ }
+ for (int i = 0; i < length; i++) {
+ buffer.writeVarInt64(value[i]);
+ }
+ }
+
+ public long[] readInt64s(MemoryBuffer buffer, LongEncoding longEncoding) {
+ int numElements = buffer.readVarUint32Small7();
+ long[] values = new long[numElements];
+
+ if (longEncoding == LongEncoding.SLI) {
+ for (int i = 0; i < numElements; i++) {
+ values[i] = buffer.readSliInt64();
+ }
+ } else {
+ for (int i = 0; i < numElements; i++) {
+ values[i] = buffer.readVarInt64();
+ }
+ }
+ return values;
+ }
}
public static final class FloatArraySerializer extends
PrimitiveArraySerializer<float[]> {
diff --git
a/java/fory-core/src/test/java/org/apache/fory/serializer/ArraySerializersTest.java
b/java/fory-core/src/test/java/org/apache/fory/serializer/ArraySerializersTest.java
index f2e53c8e1..542e56829 100644
---
a/java/fory-core/src/test/java/org/apache/fory/serializer/ArraySerializersTest.java
+++
b/java/fory-core/src/test/java/org/apache/fory/serializer/ArraySerializersTest.java
@@ -35,6 +35,7 @@ import org.apache.fory.Fory;
import org.apache.fory.ForyTestBase;
import org.apache.fory.config.ForyBuilder;
import org.apache.fory.config.Language;
+import org.apache.fory.config.LongEncoding;
import org.apache.fory.reflect.ReflectionUtils;
import org.apache.fory.test.bean.ArraysData;
import org.apache.fory.type.Descriptor;
@@ -363,4 +364,169 @@ public class ArraySerializersTest extends ForyTestBase {
Assert.assertNotSame(copy.array, wrapper.array);
Assert.assertNotSame(copy, wrapper);
}
+
+ /**
+ * Test variable-length encoding for long arrays. This test verifies that
long arrays can be
+ * serialized and deserialized using variable-length encoding when
compressLongArray is enabled.
+ */
+ @Test
+ public void testVariableLengthLongArray() {
+ // Create Fory instance with variable-length encoding enabled for long
arrays
+ Fory fory =
+ Fory.builder()
+ .requireClassRegistration(false)
+ .withLongArrayCompressed(true)
+ .withLongCompressed(LongEncoding.PVL)
+ .build();
+
+ // Test empty array
+ long[] emptyArray = new long[0];
+ long[] deserializedEmpty = (long[]) serDe(fory, fory, emptyArray);
+ assertEquals(deserializedEmpty.length, 0);
+
+ // Test array with small values (benefits from variable-length encoding)
+ long[] smallValues = {1L, 2L, 3L, 127L, 128L, 255L};
+ long[] deserializedSmall = (long[]) serDe(fory, fory, smallValues);
+ assertTrue(Arrays.equals(deserializedSmall, smallValues));
+
+ // Test array with mixed small and large values
+ long[] mixedValues = {0L, 1L, -1L, 100L, -100L, Long.MAX_VALUE,
Long.MIN_VALUE, 1000L};
+ long[] deserializedMixed = (long[]) serDe(fory, fory, mixedValues);
+ assertTrue(Arrays.equals(deserializedMixed, mixedValues));
+
+ // Test array with large values
+ long[] largeValues = {Long.MAX_VALUE, Long.MIN_VALUE, Long.MAX_VALUE / 2,
Long.MIN_VALUE / 2};
+ long[] deserializedLarge = (long[]) serDe(fory, fory, largeValues);
+ assertTrue(Arrays.equals(deserializedLarge, largeValues));
+
+ // Test array with negative values
+ long[] negativeValues = {-1L, -100L, -1000L, -1000000L};
+ long[] deserializedNegative = (long[]) serDe(fory, fory, negativeValues);
+ assertTrue(Arrays.equals(deserializedNegative, negativeValues));
+
+ // Test large array with many small values
+ long[] largeArray = new long[1000];
+ for (int i = 0; i < largeArray.length; i++) {
+ largeArray[i] = i % 100; // Small values benefit from variable-length
encoding
+ }
+ long[] deserializedLargeArray = (long[]) serDe(fory, fory, largeArray);
+ assertTrue(Arrays.equals(deserializedLargeArray, largeArray));
+ }
+
+ /**
+ * Test that variable-length encoding is more efficient (smaller size) than
fixed-length encoding
+ * when the long array contains many small values. This demonstrates the
space efficiency benefit
+ * of variable-length encoding for arrays with predominantly small values.
+ */
+ @Test
+ public void testVariableLengthEncodingEfficiencyForSmallValues() {
+ // Create a Fory instance with fixed-length encoding (compressLongArray
disabled)
+ Fory foryFixed =
+
Fory.builder().requireClassRegistration(false).withLongArrayCompressed(false).build();
+
+ // Create a Fory instance with variable-length encoding (compressLongArray
enabled)
+ Fory foryVariable =
+ Fory.builder()
+ .requireClassRegistration(false)
+ .withLongArrayCompressed(true)
+ .withLongCompressed(LongEncoding.PVL)
+ .build();
+
+ // Create an array with many small values (0-127, which can be encoded in
1-2 bytes with varint)
+ int arraySize = 10000;
+ long[] smallValuesArray = new long[arraySize];
+ for (int i = 0; i < arraySize; i++) {
+ // Use values from 0 to 127, which benefit most from variable-length
encoding
+ smallValuesArray[i] = i % 128;
+ }
+
+ // Serialize with fixed-length encoding (8 bytes per element)
+ byte[] fixedBytes = foryFixed.serialize(smallValuesArray);
+ int fixedSize = fixedBytes.length;
+
+ // Serialize with variable-length encoding (1-2 bytes per small element)
+ byte[] variableBytes = foryVariable.serialize(smallValuesArray);
+ int variableSize = variableBytes.length;
+
+ // Verify both can be deserialized correctly
+ long[] deserializedFixed = (long[]) foryFixed.deserialize(fixedBytes);
+ long[] deserializedVariable = (long[])
foryVariable.deserialize(variableBytes);
+ assertTrue(Arrays.equals(deserializedFixed, smallValuesArray));
+ assertTrue(Arrays.equals(deserializedVariable, smallValuesArray));
+
+ // Calculate efficiency metrics
+ int sizeDifference = fixedSize - variableSize;
+ double percentageReduction = 100.0 * sizeDifference / fixedSize;
+
+ System.out.printf(
+ "Array size: %d elements (values 0-127)%n"
+ + "Fixed-length encoding: %d bytes (%.2f bytes/element)%n"
+ + "Variable-length encoding: %d bytes (%.2f bytes/element)%n"
+ + "Space savings: %d bytes (%.2f%% reduction)%n",
+ arraySize,
+ fixedSize,
+ (double) fixedSize / arraySize,
+ variableSize,
+ (double) variableSize / arraySize,
+ sizeDifference,
+ percentageReduction);
+
+ // Verify that variable-length encoding produces smaller or equal size
+ // For arrays with many small values, variable-length should be
significantly smaller
+ assertTrue(
+ variableSize < fixedSize,
+ String.format(
+ "Expected variable-length encoding (%d bytes) to be smaller than
fixed-length (%d bytes) "
+ + "for array with many small values",
+ variableSize, fixedSize));
+
+ // Verify significant space savings (at least 50% reduction for small
values)
+ // Fixed-length: 8 bytes per element + overhead
+ // Variable-length: 1-2 bytes per small element + overhead
+ // For values 0-127, we expect at least 50% reduction
+ assertTrue(
+ percentageReduction >= 50.0,
+ String.format(
+ "Expected at least 50%% size reduction for small values, but got
%.2f%%",
+ percentageReduction));
+
+ // Test with slightly larger values (0-1023) to show variable-length still
helps
+ long[] mediumValuesArray = new long[arraySize];
+ for (int i = 0; i < arraySize; i++) {
+ mediumValuesArray[i] = i % 1024;
+ }
+
+ byte[] fixedBytesMedium = foryFixed.serialize(mediumValuesArray);
+ byte[] variableBytesMedium = foryVariable.serialize(mediumValuesArray);
+ int fixedSizeMedium = fixedBytesMedium.length;
+ int variableSizeMedium = variableBytesMedium.length;
+
+ // Verify deserialization
+ long[] deserializedFixedMedium = (long[])
foryFixed.deserialize(fixedBytesMedium);
+ long[] deserializedVariableMedium = (long[])
foryVariable.deserialize(variableBytesMedium);
+ assertTrue(Arrays.equals(deserializedFixedMedium, mediumValuesArray));
+ assertTrue(Arrays.equals(deserializedVariableMedium, mediumValuesArray));
+
+ int sizeDifferenceMedium = fixedSizeMedium - variableSizeMedium;
+ double percentageReductionMedium = 100.0 * sizeDifferenceMedium /
fixedSizeMedium;
+
+ System.out.printf(
+ "Array size: %d elements (values 0-1023)%n"
+ + "Fixed-length encoding: %d bytes%n"
+ + "Variable-length encoding: %d bytes%n"
+ + "Space savings: %d bytes (%.2f%% reduction)%n",
+ arraySize,
+ fixedSizeMedium,
+ variableSizeMedium,
+ sizeDifferenceMedium,
+ percentageReductionMedium);
+
+ // For medium values (0-1023), variable-length should still be smaller
+ assertTrue(
+ variableSizeMedium < fixedSizeMedium,
+ String.format(
+ "Expected variable-length encoding (%d bytes) to be smaller than
fixed-length (%d bytes) "
+ + "for array with medium values",
+ variableSizeMedium, fixedSizeMedium));
+ }
}
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