libminifi/include/io/DescriptorStream.h

/**
 *
 * 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.
 */
#ifndef LIBMINIFI_INCLUDE_IO_DESCRIPTORSTREAM_H_
#define LIBMINIFI_INCLUDE_IO_DESCRIPTORSTREAM_H_

#include <memory>
#include <vector>
#include <iostream>
#include <cstdint>
#include <string>
#include "EndianCheck.h"
#include "BaseStream.h"
#include "core/logging/LoggerConfiguration.h"

namespace org {
namespace apache {
namespace nifi {
namespace minifi {
namespace io {

/**
 * Purpose: File Stream Base stream extension. This is intended to be a thread safe access to
 * read/write to the local file system.
 *
 * Design: Simply extends BaseStream and overrides readData/writeData to allow a sink to the
 * fstream object.
 */
class DescriptorStream : public io::BaseStream {
 public:
  /**
   * File Stream constructor that accepts an fstream shared pointer.
   * It must already be initialized for read and write.
   */
  explicit DescriptorStream(int fd);

  /**
   * Skip to the specified offset.
   * @param offset offset to which we will skip
   */
  void seek(uint64_t offset) override;

  /**
   * Reads data and places it into buf
   * @param buf buffer in which we extract data
   * @param buflen
   */
  int read(uint8_t *buf, int buflen) override;

  /**
   * writes value to stream
   * @param value value to write
   * @param size size of value
   */
  int write(const uint8_t *value, int size) override;

 private:
  std::recursive_mutex file_lock_;
  int fd_;

  std::shared_ptr<logging::Logger> logger_;
};

}  // namespace io
}  // namespace minifi
}  // namespace nifi
}  // namespace apache
}  // namespace org

#endif  // LIBMINIFI_INCLUDE_IO_DESCRIPTORSTREAM_H_