file_writer.h

/*
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 * 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
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 * 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
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 */

#pragma once

/// \file iceberg/file_writer.h
/// Writer interface for file formats like Parquet, Avro and ORC.

#include <functional>
#include <memory>
#include <optional>

#include "iceberg/arrow_c_data.h"
#include "iceberg/file_format.h"
#include "iceberg/metrics.h"
#include "iceberg/result.h"
#include "iceberg/type_fwd.h"
#include "iceberg/util/config.h"

namespace iceberg {

class ICEBERG_EXPORT WriterProperties : public ConfigBase<WriterProperties> {
 public:
  template <typename T>
  using Entry = const ConfigBase<WriterProperties>::Entry<T>;

  /// \brief The name of the Avro root node schema to write.
  inline static Entry<std::string> kAvroSchemaName{"write.avro.schema-name", ""};

  /// \brief The buffer size used by Avro output stream.
  inline static Entry<int64_t> kAvroBufferSize{"write.avro.buffer-size", 1024 * 1024};

  /// \brief The sync interval used by Avro writer.
  inline static Entry<int64_t> kAvroSyncInterval{"write.avro.sync-interval", 16 * 1024};

  /// TODO(gangwu): add more properties, like compression codec, compression level, etc.

  /// \brief Create a default WriterProperties instance.
  static std::unique_ptr<WriterProperties> default_properties();

  /// \brief Create a WriterProperties instance from a map of key-value pairs.
  static std::unique_ptr<WriterProperties> FromMap(
      const std::unordered_map<std::string, std::string>& properties);
};

/// \brief Options for creating a writer.
struct ICEBERG_EXPORT WriterOptions {
  /// \brief The path to the file to write.
  std::string path;
  /// \brief The schema of the data to write.
  std::shared_ptr<Schema> schema;
  /// \brief FileIO instance to open the file. Writer implementations should down cast it
  /// to the specific FileIO implementation. By default, the `iceberg-bundle` library uses
  /// `ArrowFileSystemFileIO` as the default implementation.
  std::shared_ptr<class FileIO> io;
  /// \brief Metadata to write to the file.
  std::unordered_map<std::string, std::string> metadata;
  /// \brief Format-specific or implementation-specific properties.
  std::shared_ptr<WriterProperties> properties = WriterProperties::default_properties();
};

/// \brief Base writer class to write data from different file formats.
class ICEBERG_EXPORT Writer {
 public:
  virtual ~Writer() = default;
  Writer() = default;
  Writer(const Writer&) = delete;
  Writer& operator=(const Writer&) = delete;

  /// \brief Open the writer.
  virtual Status Open(const WriterOptions& options) = 0;

  /// \brief Close the writer.
  virtual Status Close() = 0;

  /// \brief Write arrow data to the file.
  ///
  /// \return Status of write results.
  /// \note Ownership of the data is transferred to the writer.
  virtual Status Write(ArrowArray* data) = 0;

  /// \brief Get the file statistics.
  /// Only valid after the file is closed.
  virtual std::optional<Metrics> metrics() = 0;

  /// \brief Get the file length.
  /// Only valid after the file is closed.
  virtual std::optional<int64_t> length() = 0;

  /// \brief Returns a list of recommended split locations, if applicable, empty
  /// otherwise. When available, this information is used for planning scan tasks whose
  /// boundaries are determined by these offsets. The returned list must be sorted in
  /// ascending order. Only valid after the file is closed.
  virtual std::vector<int64_t> split_offsets() = 0;
};

/// \brief Factory function to create a writer of a specific file format.
using WriterFactory = std::function<Result<std::unique_ptr<Writer>>()>;

/// \brief Registry of writer factories for different file formats.
struct ICEBERG_EXPORT WriterFactoryRegistry {
  /// \brief Register a factory function for a specific file format.
  WriterFactoryRegistry(FileFormatType format_type, WriterFactory factory);

  /// \brief Get the factory function for a specific file format.
  static WriterFactory& GetFactory(FileFormatType format_type);

  /// \brief Open a writer for a specific file format.
  static Result<std::unique_ptr<Writer>> Open(FileFormatType format_type,
                                              const WriterOptions& options);
};

}  // namespace iceberg