src/parquet/file/reader.cc

// 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.

#include "parquet/file/reader.h"

#include <cstdio>
#include <memory>
#include <sstream>
#include <string>
#include <utility>

#include "arrow/io/file.h"

#include "parquet/column_page.h"
#include "parquet/column_reader.h"
#include "parquet/column_scanner.h"
#include "parquet/exception.h"
#include "parquet/file/reader-internal.h"
#include "parquet/types.h"
#include "parquet/util/logging.h"
#include "parquet/util/memory.h"

using std::string;

namespace parquet {

// ----------------------------------------------------------------------
// RowGroupReader public API

RowGroupReader::RowGroupReader(std::unique_ptr<Contents> contents)
    : contents_(std::move(contents)) {}

std::shared_ptr<ColumnReader> RowGroupReader::Column(int i) {
  DCHECK(i < metadata()->num_columns()) << "The RowGroup only has "
                                        << metadata()->num_columns()
                                        << "columns, requested column: " << i;
  const ColumnDescriptor* descr = metadata()->schema()->Column(i);

  std::unique_ptr<PageReader> page_reader = contents_->GetColumnPageReader(i);
  return ColumnReader::Make(descr, std::move(page_reader),
      const_cast<ReaderProperties*>(contents_->properties())->memory_pool());
}

// Returns the rowgroup metadata
const RowGroupMetaData* RowGroupReader::metadata() const {
  return contents_->metadata();
}

// ----------------------------------------------------------------------
// ParquetFileReader public API

ParquetFileReader::ParquetFileReader() {}
ParquetFileReader::~ParquetFileReader() {
  try {
    Close();
  } catch (...) {}
}

std::unique_ptr<ParquetFileReader> ParquetFileReader::Open(
    const std::shared_ptr<::arrow::io::ReadableFileInterface>& source,
    const ReaderProperties& props, const std::shared_ptr<FileMetaData>& metadata) {
  std::unique_ptr<RandomAccessSource> io_wrapper(new ArrowInputFile(source));
  return Open(std::move(io_wrapper), props, metadata);
}

std::unique_ptr<ParquetFileReader> ParquetFileReader::Open(
    std::unique_ptr<RandomAccessSource> source, const ReaderProperties& props,
    const std::shared_ptr<FileMetaData>& metadata) {
  auto contents = SerializedFile::Open(std::move(source), props, metadata);
  std::unique_ptr<ParquetFileReader> result(new ParquetFileReader());
  result->Open(std::move(contents));
  return result;
}

std::unique_ptr<ParquetFileReader> ParquetFileReader::OpenFile(const std::string& path,
    bool memory_map, const ReaderProperties& props,
    const std::shared_ptr<FileMetaData>& metadata) {
  std::shared_ptr<::arrow::io::ReadableFileInterface> source;
  if (memory_map) {
    std::shared_ptr<::arrow::io::ReadableFile> handle;
    PARQUET_THROW_NOT_OK(
        ::arrow::io::ReadableFile::Open(path, props.memory_pool(), &handle));
    source = handle;
  } else {
    std::shared_ptr<::arrow::io::MemoryMappedFile> handle;
    PARQUET_THROW_NOT_OK(
        ::arrow::io::MemoryMappedFile::Open(path, ::arrow::io::FileMode::READ, &handle));
    source = handle;
  }

  return Open(source, props, metadata);
}

void ParquetFileReader::Open(std::unique_ptr<ParquetFileReader::Contents> contents) {
  contents_ = std::move(contents);
}

void ParquetFileReader::Close() {
  if (contents_) { contents_->Close(); }
}

std::shared_ptr<FileMetaData> ParquetFileReader::metadata() const {
  return contents_->metadata();
}

std::shared_ptr<RowGroupReader> ParquetFileReader::RowGroup(int i) {
  DCHECK(i < metadata()->num_row_groups()) << "The file only has "
                                           << metadata()->num_row_groups()
                                           << "row groups, requested reader for: " << i;
  return contents_->GetRowGroup(i);
}

// ----------------------------------------------------------------------
// File metadata helpers

std::shared_ptr<FileMetaData> ReadMetaData(
    const std::shared_ptr<::arrow::io::ReadableFileInterface>& source) {
  return ParquetFileReader::Open(source)->metadata();
}

}  // namespace parquet