feat: Introduce writeBatchFfi in Java JNI to avoid IPC serialization overhead

java/vortex-jni/src/main/java/dev/vortex/api/VortexWriter.java

@@ -42,6 +42,18 @@ static VortexWriter create(String uri, DType dtype, Map<String, String> options)
      */
     void writeBatch(byte[] arrowData) throws IOException;
 
+    /**
+     * Writes a batch of Arrow data directly from Arrow C Data Interface pointers.
+     * <p>
+     * This avoids the IPC serialization overhead by accepting raw memory addresses
+     * of ArrowArray and ArrowSchema structs.
+     *
+     * @param arrowArrayAddr  memory address of the ArrowArray struct
+     * @param arrowSchemaAddr memory address of the ArrowSchema struct
+     * @throws IOException if writing fails
+     */
+    void writeBatchFfi(long arrowArrayAddr, long arrowSchemaAddr) throws IOException;
+
     /**
      * Closes the writer and finalizes the Vortex file.
      * <p>

java/vortex-jni/src/main/java/dev/vortex/jni/JNIWriter.java

@@ -48,6 +48,24 @@ public void writeBatch(byte[] arrowData) throws IOException {
         }
     }
 
+    /**
+     * Writes a batch of Arrow data directly from Arrow C Data Interface pointers.
+     *
+     * @param arrowArrayAddr  memory address of the ArrowArray struct
+     * @param arrowSchemaAddr memory address of the ArrowSchema struct
+     * @throws IOException if writing fails
+     */
+    @Override
+    public void writeBatchFfi(long arrowArrayAddr, long arrowSchemaAddr) throws IOException {
+        logger.trace("Writing batch via FFI (arrayAddr={}, schemaAddr={})", arrowArrayAddr, arrowSchemaAddr);
+
+        boolean success = NativeWriterMethods.writeBatchFfi(ptr.getAsLong(), arrowArrayAddr, arrowSchemaAddr);
+        if (!success) {
+            logger.error("Failed to write FFI batch to Vortex file");
+            throw new IOException("Failed to write FFI batch to Vortex file");
+        }
+    }
+
     /**
      * Closes the writer and finalizes the Vortex file.
      *

java/vortex-jni/src/main/java/dev/vortex/jni/NativeWriterMethods.java

@@ -35,6 +35,16 @@ private NativeWriterMethods() {}
      */
     public static native boolean writeBatch(long writerPtr, byte[] arrowData);
 
+    /**
+     * Writes a batch of Arrow data to the Vortex file directly from Arrow C Data Interface pointers.
+     *
+     * @param writerPtr       the native writer pointer
+     * @param arrowArrayAddr  memory address of the ArrowArray struct
+     * @param arrowSchemaAddr memory address of the ArrowSchema struct
+     * @return true if successful, false otherwise
+     */
+    public static native boolean writeBatchFfi(long writerPtr, long arrowArrayAddr, long arrowSchemaAddr);
+
     /**
      * Close and flush the writer, finalizing it to the storage system.
      *

java/vortex-jni/src/test/java/dev/vortex/jni/JNIWriterTest.java

@@ -3,16 +3,32 @@
 
 package dev.vortex.jni;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import dev.vortex.api.DType;
+import dev.vortex.api.ScanOptions;
 import dev.vortex.api.VortexWriter;
+import dev.vortex.arrow.ArrowAllocation;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.HashMap;
 import java.util.Map;
+import org.apache.arrow.c.ArrowArray;
+import org.apache.arrow.c.ArrowSchema;
+import org.apache.arrow.c.Data;
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.vector.IntVector;
+import org.apache.arrow.vector.VarCharVector;
+import org.apache.arrow.vector.VectorSchemaRoot;
+import org.apache.arrow.vector.types.pojo.ArrowType;
+import org.apache.arrow.vector.types.pojo.Field;
+import org.apache.arrow.vector.types.pojo.FieldType;
+import org.apache.arrow.vector.types.pojo.Schema;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
@@ -58,4 +74,68 @@ public void testCreateWriter() throws IOException {
         assertTrue(Files.exists(outputPath), "Output file should exist");
         System.err.println("File created at: " + outputPath);
     }
+
+    @Test
+    public void testWriteBatchFfi() throws IOException {
+        Path outputPath = tempDir.resolve("test_ffi.vortex");
+        String writePath = outputPath.toAbsolutePath().toUri().toString();
+
+        var writeSchema = DType.newStruct(
+                new String[] {"name", "age"},
+                new DType[] {DType.newUtf8(false), DType.newInt(false)},
+                false);
+
+        BufferAllocator allocator = ArrowAllocation.rootAllocator();
+
+        Schema arrowSchema = new Schema(java.util.List.of(
+                new Field("name", FieldType.notNullable(new ArrowType.Utf8()), null),
+                new Field("age", FieldType.notNullable(new ArrowType.Int(32, true)), null)));
+
+        try (VortexWriter writer = VortexWriter.create(writePath, writeSchema, new HashMap<>())) {
+            // Build a batch with Arrow Java
+            try (VectorSchemaRoot root = VectorSchemaRoot.create(arrowSchema, allocator)) {
+                VarCharVector nameVec = (VarCharVector) root.getVector("name");
+                IntVector ageVec = (IntVector) root.getVector("age");
+
+                nameVec.allocateNew(3);
+                ageVec.allocateNew(3);
+
+                nameVec.setSafe(0, "Alice".getBytes(UTF_8));
+                nameVec.setSafe(1, "Bob".getBytes(UTF_8));
+                nameVec.setSafe(2, "Carol".getBytes(UTF_8));
+                ageVec.setSafe(0, 30);
+                ageVec.setSafe(1, 25);
+                ageVec.setSafe(2, 40);
+
+                root.setRowCount(3);
+
+                // Export to C Data Interface
+                try (ArrowArray arrowArray = ArrowArray.allocateNew(allocator);
+                        ArrowSchema arrowSchemaFfi = ArrowSchema.allocateNew(allocator)) {
+                    Data.exportVectorSchemaRoot(allocator, root, null, arrowArray, arrowSchemaFfi);
+
+                    writer.writeBatchFfi(arrowArray.memoryAddress(), arrowSchemaFfi.memoryAddress());
+                }
+            }
+        }
+
+        assertTrue(Files.exists(outputPath), "Output file should exist");
+
+        // Read back and verify
+        try (var file = dev.vortex.api.Files.open(outputPath.toAbsolutePath().toString());
+                var scan = file.newScan(ScanOptions.of())) {
+            assertEquals(3, file.rowCount());
+
+            var batch = scan.next();
+            var nameField = batch.getField(0);
+            var ageField = batch.getField(1);
+
+            assertEquals("Alice", nameField.getUTF8(0));
+            assertEquals("Bob", nameField.getUTF8(1));
+            assertEquals("Carol", nameField.getUTF8(2));
+            assertEquals(30, ageField.getInt(0));
+            assertEquals(25, ageField.getInt(1));
+            assertEquals(40, ageField.getInt(2));
+        }
+    }
 }

vortex-jni/src/writer.rs

@@ -4,6 +4,9 @@
 use std::io::Cursor;
 
 use arrow_array::RecordBatch;
+use arrow_array::StructArray;
+use arrow_array::ffi::FFI_ArrowArray;
+use arrow_array::ffi::FFI_ArrowSchema;
 use arrow_ipc::reader::StreamReader;
 use futures::SinkExt;
 use futures::channel::mpsc;
@@ -226,6 +229,40 @@ pub extern "system" fn Java_dev_vortex_jni_NativeWriterMethods_writeBatch<'local
     })
 }
 
+/// Writes a batch to the Vortex file directly from Arrow C Data Interface pointers.
+///
+/// This avoids the IPC serialization/deserialization overhead of `writeBatch` by accepting
+/// raw Arrow FFI pointers directly.
+#[unsafe(no_mangle)]
+pub extern "system" fn Java_dev_vortex_jni_NativeWriterMethods_writeBatchFfi<'local>(
+    mut env: JNIEnv<'local>,
+    _class: JClass<'local>,
+    writer_ptr: jlong,
+    arrow_array_addr: jlong,
+    arrow_schema_addr: jlong,
+) -> jboolean {
+    if writer_ptr <= 0 {
+        return JNI_FALSE;
+    }
+
+    try_or_throw(&mut env, |_env| {
+        let writer = unsafe { NativeWriter::from_ptr(writer_ptr) };
+
+        // Reconstruct FFI structs from the raw pointers provided by Java.
+        let ffi_array =
+            unsafe { FFI_ArrowArray::from_raw(arrow_array_addr as *mut FFI_ArrowArray) };
+        let ffi_schema = unsafe { &*(arrow_schema_addr as *const FFI_ArrowSchema) };
+
+        let array_data = unsafe { arrow_array::ffi::from_ffi(ffi_array, ffi_schema) }
+            .map_err(|e| JNIError::Vortex(vortex_err!("Failed to import Arrow FFI data: {}", e)))?;
+
+        let batch = RecordBatch::from(StructArray::from(array_data));
+        writer.write_record_batch(batch)?;
+
+        Ok(JNI_TRUE)
+    })
+}
+
 /// Closes the writer
 #[unsafe(no_mangle)]
 pub extern "system" fn Java_dev_vortex_jni_NativeWriterMethods_close<'local>(