lidavidm commented on code in PR #14151:
URL: https://github.com/apache/arrow/pull/14151#discussion_r1000600324
##########
java/dataset/src/main/cpp/jni_wrapper.cc:
##########
@@ -170,6 +172,21 @@ class DisposableScannerAdaptor {
}
};
+arrow::Result<std::shared_ptr<arrow::Schema>> SchemaFromColumnNames(
+ const std::shared_ptr<arrow::Schema>& input,
+ const std::vector<std::string>& column_names) {
+ std::vector<std::shared_ptr<arrow::Field>> columns;
+ for (arrow::FieldRef ref : column_names) {
+ auto maybe_field = ref.GetOne(*input);
+ if (maybe_field.ok()) {
+ columns.push_back(std::move(maybe_field).ValueOrDie());
+ } else {
+ return arrow::Status::Invalid("The provided column name is not in arrow
schema");
Review Comment:
```suggestion
return arrow::Status::Invalid("Partition column '", ref.ToString(), "'
is not in dataset schema");
```
##########
java/dataset/src/main/cpp/jni_wrapper.cc:
##########
@@ -510,3 +526,49 @@
Java_org_apache_arrow_dataset_file_JniWrapper_makeFileSystemDatasetFactory(
return CreateNativeRef(d);
JNI_METHOD_END(-1L)
}
+
+/*
+ * Class: org_apache_arrow_dataset_file_JniWrapper
+ * Method: writeFromScannerToFile
+ * Signature:
+ * (JJJLjava/lang/String;[Ljava/lang/String;ILjava/lang/String;)V
+ */
+JNIEXPORT void JNICALL
+Java_org_apache_arrow_dataset_file_JniWrapper_writeFromScannerToFile(
+ JNIEnv* env, jobject, jlong c_arrow_array_stream_address,
+ jlong file_format_id, jstring uri, jobjectArray partition_columns,
+ jint max_partitions, jstring base_name_template) {
+ JNI_METHOD_START
+ JavaVM* vm;
+ if (env->GetJavaVM(&vm) != JNI_OK) {
+ JniThrow("Unable to get JavaVM instance");
+ }
+
+ auto* arrow_stream =
reinterpret_cast<ArrowArrayStream*>(c_arrow_array_stream_address);
+ std::shared_ptr<arrow::RecordBatchReader> reader =
+ JniGetOrThrow(arrow::ImportRecordBatchReader(arrow_stream));
+ std::shared_ptr<arrow::dataset::ScannerBuilder> scanner_builder =
+ arrow::dataset::ScannerBuilder::FromRecordBatchReader(reader);
+ scanner_builder->Pool(arrow::default_memory_pool());
+ auto scanner = scanner_builder->Finish().ValueOrDie();
Review Comment:
We must check for error here
##########
java/dataset/src/main/cpp/jni_wrapper.cc:
##########
@@ -510,3 +526,49 @@
Java_org_apache_arrow_dataset_file_JniWrapper_makeFileSystemDatasetFactory(
return CreateNativeRef(d);
JNI_METHOD_END(-1L)
}
+
+/*
+ * Class: org_apache_arrow_dataset_file_JniWrapper
+ * Method: writeFromScannerToFile
+ * Signature:
+ * (JJJLjava/lang/String;[Ljava/lang/String;ILjava/lang/String;)V
+ */
+JNIEXPORT void JNICALL
+Java_org_apache_arrow_dataset_file_JniWrapper_writeFromScannerToFile(
+ JNIEnv* env, jobject, jlong c_arrow_array_stream_address,
+ jlong file_format_id, jstring uri, jobjectArray partition_columns,
+ jint max_partitions, jstring base_name_template) {
+ JNI_METHOD_START
+ JavaVM* vm;
+ if (env->GetJavaVM(&vm) != JNI_OK) {
+ JniThrow("Unable to get JavaVM instance");
+ }
+
+ auto* arrow_stream =
reinterpret_cast<ArrowArrayStream*>(c_arrow_array_stream_address);
+ std::shared_ptr<arrow::RecordBatchReader> reader =
+ JniGetOrThrow(arrow::ImportRecordBatchReader(arrow_stream));
+ std::shared_ptr<arrow::dataset::ScannerBuilder> scanner_builder =
+ arrow::dataset::ScannerBuilder::FromRecordBatchReader(reader);
+ scanner_builder->Pool(arrow::default_memory_pool());
Review Comment:
We must check for error here
##########
java/dataset/src/main/java/org/apache/arrow/dataset/file/DatasetFileWriter.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * 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.file;
+
+import org.apache.arrow.c.ArrowArrayStream;
+import org.apache.arrow.c.ArrowSchema;
+import org.apache.arrow.c.Data;
+import org.apache.arrow.dataset.scanner.ArrowScannerReader;
+import org.apache.arrow.dataset.scanner.ScanTask;
+import org.apache.arrow.dataset.scanner.Scanner;
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.util.AutoCloseables;
+import org.apache.arrow.vector.ipc.ArrowReader;
+import org.apache.arrow.vector.util.SchemaUtility;
+
+import java.util.Iterator;
+
+/**
+ * JNI-based utility to write datasets into files. It internally depends on
C++ static method
+ * FileSystemDataset::Write.
+ */
+public class DatasetFileWriter {
+
+ /**
+ * Write a ArrowReader accepting Scanner into files.
Review Comment:
The docstring is still incorrect
##########
java/dataset/src/main/java/org/apache/arrow/dataset/scanner/ArrowScannerReader.java:
##########
@@ -0,0 +1,106 @@
+/*
+ * 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.scanner;
+
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.vector.VectorLoader;
+import org.apache.arrow.vector.VectorUnloader;
+import org.apache.arrow.vector.ipc.ArrowReader;
+import org.apache.arrow.vector.ipc.message.ArrowDictionaryBatch;
+import org.apache.arrow.vector.ipc.message.ArrowRecordBatch;
+import org.apache.arrow.vector.types.pojo.Schema;
+
+import java.io.IOException;
+import java.util.Iterator;
+
+public class ArrowScannerReader extends ArrowReader {
+ private final Scanner scanner;
+
+ private Iterator<? extends ScanTask> taskIterator;
+
+ private ScanTask currentTask = null;
+ private ArrowReader currentReader = null;
+
+ public ArrowScannerReader(Scanner scanner, BufferAllocator allocator) {
+ super(allocator);
+ this.scanner = scanner;
+ this.taskIterator = scanner.scan().iterator();
+ if (taskIterator.hasNext()) {
+ currentTask = taskIterator.next();
+ currentReader = currentTask.execute();
+ }
+ }
+
+ @Override
+ protected void loadRecordBatch(ArrowRecordBatch batch) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ protected void loadDictionary(ArrowDictionaryBatch dictionaryBatch) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public boolean loadNextBatch() throws IOException {
+ if (currentReader == null) return false;
+ boolean result = currentReader.loadNextBatch();
+
+ if (!result) {
+ try {
+ currentTask.close();
+ currentReader.close();
+ } catch (Exception e) {
+ throw new IOException(e);
+ }
+
+ while (!result) {
+ if (!taskIterator.hasNext()) {
+ return false;
+ } else {
+ currentTask = taskIterator.next();
+ currentReader = currentTask.execute();
+ result = currentReader.loadNextBatch();
+ }
+ }
+ }
+
+ VectorLoader loader = new VectorLoader(this.getVectorSchemaRoot());
+ VectorUnloader unloader =
+ new VectorUnloader(currentReader.getVectorSchemaRoot());
+ try(ArrowRecordBatch recordBatch = unloader.getRecordBatch()) {
+ loader.load(recordBatch);
+ }
+ return true;
+ }
+
+ @Override
+ public long bytesRead() {
+ return 0L;
+ }
+
+ @Override
+ protected void closeReadSource() throws IOException {
+ // no-op
Review Comment:
We need to close resources here
##########
java/dataset/src/main/java/org/apache/arrow/dataset/file/DatasetFileWriter.java:
##########
@@ -0,0 +1,69 @@
+/*
+ * 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.file;
+
+import org.apache.arrow.c.ArrowArrayStream;
+import org.apache.arrow.c.ArrowSchema;
+import org.apache.arrow.c.Data;
+import org.apache.arrow.dataset.scanner.ArrowScannerReader;
+import org.apache.arrow.dataset.scanner.ScanTask;
+import org.apache.arrow.dataset.scanner.Scanner;
+import org.apache.arrow.memory.BufferAllocator;
+import org.apache.arrow.util.AutoCloseables;
+import org.apache.arrow.vector.ipc.ArrowReader;
+import org.apache.arrow.vector.util.SchemaUtility;
+
+import java.util.Iterator;
+
+/**
+ * JNI-based utility to write datasets into files. It internally depends on
C++ static method
+ * FileSystemDataset::Write.
+ */
+public class DatasetFileWriter {
+
+ /**
+ * Write a ArrowReader accepting Scanner into files.
Review Comment:
```suggestion
* Write the contents of an ArrowReader as a dataset.
```
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