Add download + indexOuput#write implementation to RemoteIndexBuildStrategy

Signed-off-by: Jay Deng <jayd0104@gmail.com>

Author: jed326

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased 3.0](https://github.com/opensearch-project/k-NN/compare/2.x...HEAD)
 ### Features
+* [Remote Vector Index Build] Implement data download and IndexOutput write functionality [#2554](https://github.com/opensearch-project/k-NN/pull/2554)
 ### Enhancements
 ### Bug Fixes
 ### Infrastructure

src/main/java/org/opensearch/knn/index/codec/nativeindex/remote/RemoteIndexBuildStrategy.java

@@ -5,23 +5,28 @@
 
 package org.opensearch.knn.index.codec.nativeindex.remote;
 
+import com.google.common.annotations.VisibleForTesting;
 import lombok.extern.log4j.Log4j2;
 import org.apache.commons.lang.NotImplementedException;
 import org.apache.lucene.index.SegmentWriteState;
 import org.opensearch.common.StopWatch;
 import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.common.blobstore.BlobContainer;
+import org.opensearch.common.blobstore.BlobPath;
 import org.opensearch.index.IndexSettings;
 import org.opensearch.knn.common.featureflags.KNNFeatureFlags;
 import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.codec.nativeindex.NativeIndexBuildStrategy;
 import org.opensearch.knn.index.codec.nativeindex.model.BuildIndexParams;
+import org.opensearch.knn.index.store.IndexOutputWithBuffer;
 import org.opensearch.knn.index.vectorvalues.KNNVectorValues;
 import org.opensearch.repositories.RepositoriesService;
 import org.opensearch.repositories.Repository;
 import org.opensearch.repositories.RepositoryMissingException;
 import org.opensearch.repositories.blobstore.BlobStoreRepository;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.function.Supplier;
 
 import static org.opensearch.knn.index.KNNSettings.KNN_INDEX_REMOTE_VECTOR_BUILD_SETTING;
@@ -37,6 +42,7 @@ public class RemoteIndexBuildStrategy implements NativeIndexBuildStrategy {
 
     private final Supplier<RepositoriesService> repositoriesServiceSupplier;
     private final NativeIndexBuildStrategy fallbackStrategy;
+
     private static final String VECTOR_BLOB_FILE_EXTENSION = ".knnvec";
     private static final String DOC_ID_FILE_EXTENSION = ".knndid";
 
@@ -93,12 +99,12 @@ public void buildAndWriteIndex(BuildIndexParams indexInfo) throws IOException {
             log.debug("Submit vector build took {} ms for vector field [{}]", time_in_millis, indexInfo.getFieldName());
 
             stopWatch = new StopWatch().start();
-            awaitVectorBuild();
+            BlobPath downloadPath = awaitVectorBuild();
             time_in_millis = stopWatch.stop().totalTime().millis();
             log.debug("Await vector build took {} ms for vector field [{}]", time_in_millis, indexInfo.getFieldName());
 
             stopWatch = new StopWatch().start();
-            readFromRepository();
+            readFromRepository(downloadPath, indexInfo.getIndexOutputWithBuffer());
             time_in_millis = stopWatch.stop().totalTime().millis();
             log.debug("Repository read took {} ms for vector field [{}]", time_in_millis, indexInfo.getFieldName());
         } catch (Exception e) {
@@ -155,15 +161,22 @@ private void submitVectorBuild() {
 
     /**
      * Wait on remote vector build to complete
+     * @return BlobPath     The path from which we should perform download
      */
-    private void awaitVectorBuild() {
+    private BlobPath awaitVectorBuild() throws NotImplementedException {
         throw new NotImplementedException();
     }
 
     /**
      * Read constructed vector file from remote repository and write to IndexOutput
      */
-    private void readFromRepository() {
-        throw new NotImplementedException();
+    @VisibleForTesting
+    void readFromRepository(BlobPath downloadPath, IndexOutputWithBuffer indexOutputWithBuffer) throws IOException {
+        BlobContainer blobContainer = getRepository().blobStore().blobContainer(downloadPath.parent());
+        // TODO: We are using the sequential download API as multi-part parallel download is difficult for us to implement today and
+        // requires some changes in core. For more details, see: https://github.com/opensearch-project/k-NN/issues/2464
+        String fileName = downloadPath.toArray()[downloadPath.toArray().length - 1];
+        InputStream graphStream = blobContainer.readBlob(fileName);
+        indexOutputWithBuffer.writeFromStreamWithBuffer(graphStream);
     }
 }

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

@@ -8,18 +8,25 @@
 import org.apache.lucene.store.IndexOutput;
 
 import java.io.IOException;
+import java.io.InputStream;
 
+/**
+ * Wrapper around {@link IndexOutput} to perform writes in a buffered manner. This class is created per flush/merge, and may be used twice if
+ * {@link org.opensearch.knn.index.codec.nativeindex.remote.RemoteIndexBuildStrategy} needs to fall back to a different build strategy.
+ */
 public class IndexOutputWithBuffer {
     // Underlying `IndexOutput` obtained from Lucene's Directory.
     private IndexOutput indexOutput;
     // Write buffer. Native engine will copy bytes into this buffer.
     // Allocating 64KB here since it show better performance in NMSLIB with the size. (We had slightly improvement in FAISS than having 4KB)
     // NMSLIB writes an adjacent list size first, then followed by serializing the list. Since we usually have more adjacent lists, having
     // 64KB to accumulate bytes as possible to reduce the times of calling `writeBytes`.
-    private byte[] buffer = new byte[64 * 1024];
+    private static final int CHUNK_SIZE = 64 * 1024;
+    private final byte[] buffer;
 
     public IndexOutputWithBuffer(IndexOutput indexOutput) {
         this.indexOutput = indexOutput;
+        this.buffer = new byte[CHUNK_SIZE];
     }
 
     // This method will be called in JNI layer which precisely knows
@@ -33,6 +40,43 @@ public void writeBytes(int length) {
         }
     }
 
+    /**
+     * Writes to the {@link IndexOutput} by buffering bytes into the existing buffer in this class.
+     *
+     * @param inputStream       The stream from which we are reading bytes to write
+     * @throws IOException
+     * @see IndexOutputWithBuffer#writeFromStreamWithBuffer(InputStream, byte[])
+     */
+    public void writeFromStreamWithBuffer(InputStream inputStream) throws IOException {
+        writeFromStreamWithBuffer(inputStream, this.buffer);
+    }
+
+    /**
+     * Writes to the {@link IndexOutput} by buffering bytes with @param outputBuffer. This method allows
+     * {@link org.opensearch.knn.index.codec.nativeindex.remote.RemoteIndexBuildStrategy} to provide a separate, larger buffer as that buffer is for buffering
+     * bytes downloaded from the repository, so it may be more performant to use a larger buffer.
+     * We do not change the size of the existing buffer in case a fallback to the existing build strategy is needed.
+     * TODO: Tune the size of the buffer used by RemoteIndexBuildStrategy based on benchmarking
+     *
+     * @param inputStream       The stream from which we are reading bytes to write
+     * @param outputBuffer      The buffer used to buffer bytes
+     * @throws IOException
+     * @see IndexOutputWithBuffer#writeFromStreamWithBuffer(InputStream)
+     */
+    public void writeFromStreamWithBuffer(InputStream inputStream, byte[] outputBuffer) throws IOException {
+        int bytesRead = 0;
+        // InputStream uses -1 indicates there are no more bytes to be read
+        while (bytesRead != -1) {
+            // Try to read CHUNK_SIZE into the buffer. The actual amount read may be less.
+            bytesRead = inputStream.read(outputBuffer, 0, CHUNK_SIZE);
+            assert bytesRead <= CHUNK_SIZE;
+            // However many bytes we read, write it to the IndexOutput if != -1
+            if (bytesRead != -1) {
+                indexOutput.writeBytes(outputBuffer, 0, bytesRead);
+            }
+        }
+    }
+
     @Override
     public String toString() {
         return "{indexOutput=" + indexOutput + ", len(buffer)=" + buffer.length + "}";

src/test/java/org/opensearch/knn/index/codec/nativeindex/remote/RemoteIndexBuildStrategyTests.java

@@ -5,7 +5,18 @@
 
 package org.opensearch.knn.index.codec.nativeindex.remote;
 
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.IOContext;
+import org.apache.lucene.store.IndexInput;
+import org.apache.lucene.store.IndexOutput;
+import org.junit.Before;
 import org.mockito.Mockito;
+import org.opensearch.common.blobstore.AsyncMultiStreamBlobContainer;
+import org.opensearch.common.blobstore.BlobPath;
+import org.opensearch.common.blobstore.BlobStore;
+import org.opensearch.common.settings.ClusterSettings;
+import org.opensearch.knn.KNNTestCase;
+import org.opensearch.knn.index.KNNSettings;
 import org.opensearch.knn.index.VectorDataType;
 import org.opensearch.knn.index.codec.nativeindex.NativeIndexBuildStrategy;
 import org.opensearch.knn.index.codec.nativeindex.model.BuildIndexParams;
@@ -16,17 +27,21 @@
 import org.opensearch.knn.index.vectorvalues.TestVectorValues;
 import org.opensearch.repositories.RepositoriesService;
 import org.opensearch.repositories.RepositoryMissingException;
-import org.opensearch.test.OpenSearchTestCase;
+import org.opensearch.repositories.blobstore.BlobStoreRepository;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.List;
 import java.util.Map;
+import java.util.Random;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
+import static org.opensearch.knn.index.KNNSettings.KNN_REMOTE_VECTOR_REPO_SETTING;
 
-public class RemoteIndexBuildStrategyTests extends OpenSearchTestCase {
+public class RemoteIndexBuildStrategyTests extends KNNTestCase {
 
     static int fallbackCounter = 0;
 
@@ -38,6 +53,16 @@ public void buildAndWriteIndex(BuildIndexParams indexInfo) throws IOException {
         }
     }
 
+    @Before
+    @Override
+    public void setUp() throws Exception {
+        super.setUp();
+        ClusterSettings clusterSettings = mock(ClusterSettings.class);
+        when(clusterSettings.get(KNN_REMOTE_VECTOR_REPO_SETTING)).thenReturn("test-repo-name");
+        when(clusterService.getClusterSettings()).thenReturn(clusterSettings);
+        KNNSettings.state().setClusterService(clusterService);
+    }
+
     public void testFallback() throws IOException {
         List<float[]> vectorValues = List.of(new float[] { 1, 2 }, new float[] { 2, 3 }, new float[] { 3, 4 });
         final TestVectorValues.PreDefinedFloatVectorValues randomVectorValues = new TestVectorValues.PreDefinedFloatVectorValues(
@@ -64,4 +89,55 @@ public void testFallback() throws IOException {
         objectUnderTest.buildAndWriteIndex(buildIndexParams);
         assertEquals(1, fallbackCounter);
     }
+
+    /**
+     * Verify the buffered read method in {@link RemoteIndexBuildStrategy#readFromRepository} produces the correct result
+     */
+    public void testRepositoryRead() throws IOException {
+        // Create an InputStream with random values
+        int TEST_ARRAY_SIZE = 64 * 1024 * 10;
+        byte[] byteArray = new byte[TEST_ARRAY_SIZE];
+        Random random = new Random();
+        random.nextBytes(byteArray);
+        InputStream randomStream = new ByteArrayInputStream(byteArray);
+
+        // Create a test segment that we will read/write from
+        Directory directory;
+        directory = newFSDirectory(createTempDir());
+        String TEST_SEGMENT_NAME = "test-segment-name";
+        IndexOutput testIndexOutput = directory.createOutput(TEST_SEGMENT_NAME, IOContext.DEFAULT);
+        IndexOutputWithBuffer testIndexOutputWithBuffer = new IndexOutputWithBuffer(testIndexOutput);
+
+        // Set up RemoteIndexBuildStrategy and write to IndexOutput
+        RepositoriesService repositoriesService = mock(RepositoriesService.class);
+        BlobStoreRepository mockRepository = mock(BlobStoreRepository.class);
+        BlobPath testBasePath = new BlobPath().add("testBasePath");
+        BlobStore mockBlobStore = mock(BlobStore.class);
+        AsyncMultiStreamBlobContainer mockBlobContainer = mock(AsyncMultiStreamBlobContainer.class);
+
+        when(repositoriesService.repository(any())).thenReturn(mockRepository);
+        when(mockRepository.basePath()).thenReturn(testBasePath);
+        when(mockRepository.blobStore()).thenReturn(mockBlobStore);
+        when(mockBlobStore.blobContainer(any())).thenReturn(mockBlobContainer);
+        when(mockBlobContainer.readBlob("testFile")).thenReturn(randomStream);
+
+        RemoteIndexBuildStrategy objectUnderTest = new RemoteIndexBuildStrategy(
+            () -> repositoriesService,
+            mock(NativeIndexBuildStrategy.class)
+        );
+        // This should read from randomStream into testIndexOutput
+        BlobPath testPath = new BlobPath().add("testBasePath").add("testDirectory").add("testFile");
+        objectUnderTest.readFromRepository(testPath, testIndexOutputWithBuffer);
+        testIndexOutput.close();
+
+        // Now try to read from the IndexOutput
+        IndexInput testIndexInput = directory.openInput(TEST_SEGMENT_NAME, IOContext.DEFAULT);
+        byte[] resultByteArray = new byte[TEST_ARRAY_SIZE];
+        testIndexInput.readBytes(resultByteArray, 0, TEST_ARRAY_SIZE);
+        assertArrayEquals(byteArray, resultByteArray);
+
+        // Test Cleanup
+        testIndexInput.close();
+        directory.close();
+    }
 }