zhztheplayer commented on a change in pull request #7030: URL: https://github.com/apache/arrow/pull/7030#discussion_r426376401
########## File path: java/dataset/src/main/java/org/apache/arrow/dataset/jni/NativeDataset.java ########## @@ -0,0 +1,48 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.arrow.dataset.jni; + +import org.apache.arrow.dataset.scanner.ScanOptions; +import org.apache.arrow.dataset.scanner.Scanner; +import org.apache.arrow.dataset.source.Dataset; + +/** + * Native implementation of {@link Dataset}. + */ +public class NativeDataset implements Dataset, AutoCloseable { + + private final NativeContext context; + private final long datasetId; + + public NativeDataset(NativeContext context, long datasetId) { + this.context = context; + this.datasetId = datasetId; + } + + @Override + public Scanner newScan(ScanOptions options) { + long scannerId = JniWrapper.get().createScanner(datasetId, options.getColumns(), + options.getFilter().toByteArray(), options.getBatchSize()); + return new NativeScanner(context, scannerId); + } + + @Override + public void close() throws Exception { Review comment: done ########## File path: java/dataset/src/main/java/org/apache/arrow/dataset/jni/NativeScanTask.java ########## @@ -0,0 +1,110 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.arrow.dataset.jni; + +import java.util.ArrayList; +import java.util.NoSuchElementException; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.stream.Collectors; + +import org.apache.arrow.dataset.scanner.ScanTask; +import org.apache.arrow.memory.ArrowBuf; +import org.apache.arrow.memory.BaseAllocator; +import org.apache.arrow.memory.BufferLedger; +import org.apache.arrow.memory.NativeUnderlingMemory; +import org.apache.arrow.memory.Ownerships; +import org.apache.arrow.vector.ipc.message.ArrowFieldNode; +import org.apache.arrow.vector.ipc.message.ArrowRecordBatch; + +/** + * Native implementation of {@link ScanTask}. Currently RecordBatches are iterated directly by the scanner + * id via {@link JniWrapper}, thus we allow only one-time execution of method {@link #scan()}. If a re-scan + * operation is expected, call {@link NativeDataset#newScan} to create a new scanner instance. + */ +public class NativeScanTask implements ScanTask, AutoCloseable { + private final NativeScanner scanner; + private final AtomicBoolean executed = new AtomicBoolean(false); + + /** + * Constructor. + */ + public NativeScanTask(NativeScanner scanner) { + this.scanner = scanner; + } + + @Override + public BatchIterator scan() { + if (!executed.compareAndSet(false, true)) { + throw new UnsupportedOperationException("Method scan() cannot be executed more than once if it is a " + + "native scan task"); + } + return new BatchIterator() { + private ArrowRecordBatch peek = null; + + @Override + public void close() throws Exception { + scanner.close(); + } + + @Override + public boolean hasNext() { + if (peek != null) { + return true; + } + NativeRecordBatchHandle handle = JniWrapper.get().nextRecordBatch(scanner.getId()); + if (handle == null) { + return false; + } + final ArrayList<ArrowBuf> buffers = new ArrayList<>(); + for (NativeRecordBatchHandle.Buffer buffer : handle.getBuffers()) { + final BaseAllocator allocator = scanner.getContext().getAllocator(); + final NativeUnderlingMemory am = new NativeUnderlingMemory(allocator, + (int) buffer.size, buffer.nativeInstanceId, buffer.memoryAddress); + final BufferLedger ledger = Ownerships.get().takeOwnership(allocator, am); + ArrowBuf buf = new ArrowBuf(ledger, null, (int) buffer.size, buffer.memoryAddress, false); + buffers.add(buf); + } + try { + peek = new ArrowRecordBatch((int) handle.getNumRows(), handle.getFields().stream() + .map(field -> new ArrowFieldNode((int) field.length, (int) field.nullCount)) + .collect(Collectors.toList()), buffers); + return true; + } finally { + buffers.forEach(buffer -> buffer.getReferenceManager().release()); + } + } + + @Override + public ArrowRecordBatch next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + try { Review comment: done, thanks ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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