EmptyDriveProbe.hpp

/*
 * @project        The CERN Tape Archive (CTA)
 * @copyright      Copyright(C) 2003-2021 CERN
 * @license        This program is free software: you can redistribute it and/or modify
 *                 it under the terms of the GNU General Public License as published by
 *                 the Free Software Foundation, either version 3 of the License, or
 *                 (at your option) any later version.
 *
 *                 This program is distributed in the hope that it will be useful,
 *                 but WITHOUT ANY WARRANTY; without even the implied warranty of
 *                 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *                 GNU General Public License for more details.
 *
 *                 You should have received a copy of the GNU General Public License
 *                 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "common/log/LogContext.hpp"
#include "common/log/Logger.hpp"
#include "castor/tape/tapeserver/drive/DriveInterface.hpp"
#include "castor/tape/tapeserver/file/Structures.hpp"
#include "castor/tape/tapeserver/SCSI/Device.hpp"
#include "castor/tape/tapeserver/system/Wrapper.hpp"
#include "mediachanger/MediaChangerFacade.hpp"
#include "common/optional.hpp"

#include <memory>

namespace castor {
namespace tape {
namespace tapeserver {
namespace daemon {
  /**
   * Class responsible for probing a tape drive to see if it empty and
   * accessible.
   */
  class EmptyDriveProbe {
  public:

    /**
     * Constructor
     * 
     * @param log Object representing the API to the CASTOR logging system.
     * @param driveConfig Configuration of the tape drive to be probed.
     * @param sysWrapper Object representing the operating system.
     */
    EmptyDriveProbe(
      cta::log::Logger &log,
      const cta::tape::daemon::TpconfigLine &driveConfig,
      System::virtualWrapper &sysWrapper);
    
    /** 
     * Probes the tape drive to determine whether it is empty and accessible.
     *
     * @return True if the drive is empty and accessible.
     */
    bool driveIsEmpty() throw();
    
    /**
     * Returns the eventual probe error message
     */
    cta::optional<std::string> getProbeErrorMsg();
    
  private:

    /**
     * The logging object     
     */
    cta::log::Logger &m_log;
    
    /**
     * The configuration of the tape drive to be probed.
     */
    const cta::tape::daemon::TpconfigLine m_driveConfig;
    
    /**
     * The system wrapper used to find the device and instantiate the drive object
     */
    System::virtualWrapper &m_sysWrapper;

    /** 
     * Probes the tape drive to determine whether it is empty and accessible.
     *
     * @return True if the drive is empty and accessible.
     */
    bool exceptionThrowingDriveIsEmpty();

    /**
     * Creates and returns the object that represents the tape drive to be
     * probed.
     *
     * @return The tape drive.
     */
    std::unique_ptr<drive::DriveInterface> createDrive();
    
    /**
     * Eventual error message if we could not check whether the drive is empty or not
     */
    cta::optional<std::string> m_probeErrorMsg;
    
  }; // class EmptyDriveProbe

} // namespace daemon
} // namespace tapeserver
} // namespace tape
} // namespace castor