Added IndexOutputWithBuffer. Removed print logging.

jni/include/stream_support.h

@@ -132,7 +132,6 @@ class NativeEngineIndexOutputMediator {
 
   void writeBytes(uint8_t* data, size_t nbytes) {
       auto left = (int32_t) nbytes;
-      std::cout << "@@@ [KDY] write " << nbytes << std::endl;
       while (left > 0) {
           const auto copyBytes = std::min(left, bufferSize - offset);
           std::memcpy(buffer.get() + offset, data, copyBytes);
@@ -165,7 +164,6 @@ class NativeEngineIndexOutputMediator {
   }
 
   void flush() {
-      std::cout << "@@@ [KDY] flush " << offset << std::endl;
       // `writeBytes` method defined.
       jmethodID writeBytesMethod = getWriteBytesMethod(env);
 

src/main/java/org/opensearch/knn/index/util/IndexOutputWithBuffer.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.knn.index.util;
+
+import org.apache.lucene.store.IndexOutput;
+
+import java.io.IOException;
+
+public class IndexOutputWithBuffer {
+    public IndexOutputWithBuffer(IndexOutput indexOutput) {
+        this.indexOutput = indexOutput;
+    }
+
+    public byte[] getBuffer() {
+        return buffer;
+    }
+
+    public void writeBytes(int length) {
+        try {
+            indexOutput.writeBytes(buffer, 0, length);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "{indexOutput=" + indexOutput + ", len(buffer)=" + buffer.length + "}";
+    }
+
+    private IndexOutput indexOutput;
+    private byte[] buffer = new byte[4 * 1024];
+}