Session.hpp 2.53 KB
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/*
 * @project        The CERN Tape Archive (CTA)
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 * @copyright      Copyright(C) 2003-2021 CERN
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 * @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.
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 *
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 *                 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.
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 *
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 *                 You should have received a copy of the GNU General Public License
 *                 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
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#pragma once

namespace castor {
namespace tape {
namespace tapeserver {
namespace daemon {

/**
 * Abstract class responsible for defining the interface to a tapeserverd
 * child-process session.
 */
class Session {
public:

  /**
   * Destructor.
   */
  virtual ~Session() = 0;

  /**
   * Enumeration of actions that can be performed after a session has been
   * completed.
   *
   * Please note that this enumeration will be used to set the integer
   * termination/return values of child-process sessions.
   */
  enum EndOfSessionAction {
    MARK_DRIVE_AS_UP   = 0,
    MARK_DRIVE_AS_DOWN = 1,
    CLEAN_DRIVE        = 2 // Unload and dismount tape if present
  };
  
  /**
   * Execute the session and return the type of action to be performed
   * immediately after the session has completed.
   *
   * The session is responsible for mounting a tape into the tape drive, working
   * with that tape, unloading the tape from the drive and then dismounting the
   * tape from the drive and storing it back in its home slot within the tape
   * library.
   *
   * If this method throws an exception and the session is not a cleaner
   * session then it assumed that the post session action is
   * EndOfSessionAction::CLEAN_DRIVE.
   *
   * If this method throws an exception and the session is a cleaner
   * session then it assumed that the post session action is
   * EndOfSessionAction::MARK_DRIVE_AS_DOWN.
   *
   * @return Returns the type of action to be performed after the session has
   * completed.
   */
  virtual EndOfSessionAction execute() = 0;
    
}; // class Session

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