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src/dbconnectionwatchdog.h 3.89 KB
fe12aa6a   Steven de Ridder   Initial commit. d...
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  /* ****************************************************************************
   * Copyright 2019 Open Systems Development BV                                 *
   *                                                                            *
   * Permission is hereby granted, free of charge, to any person obtaining a    *
   * copy of this software and associated documentation files (the "Software"), *
   * to deal in the Software without restriction, including without limitation  *
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,   *
   * and/or sell copies of the Software, and to permit persons to whom the      *
   * Software is furnished to do so, subject to the following conditions:       *
   *                                                                            *
   * The above copyright notice and this permission notice shall be included in *
   * all copies or substantial portions of the Software.                        *
   *                                                                            *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   *
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    *
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING    *
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER        *
   * DEALINGS IN THE SOFTWARE.                                                  *
   * ***************************************************************************/
  
  
  #ifndef OSDEV_COMPONENTS_DBCONNECTIONWATCHDOG_H
  #define OSDEV_COMPONENTS_DBCONNECTIONWATCHDOG_H
  
  #include <QObject>
  #include <QTimer>
  #include <QPointer>
  
  namespace osdev {
  namespace components {
  /*!
   * \brief   The DbConnectionWatchDog class checks on intervals if all registered database
   *          connections are still active. By using the simplest query form like fetching
   *          all tablenames on the connectionlevel, we trigger an error.
   *          Connection is checked every (check_interval) seconds. If an error is detected,
   *          check_interval is set to 1 seconds, reverting back to <check_interval> if the
   *          connection checks out again.
   */
  class DbConnectionWatchDog : public QObject
  {
      Q_OBJECT
  
  public:
      /*!
       * \brief The constructor
       * \param check_interval in seconds.
       * \param parent    - The object that owns this connection guard.
       */
      explicit DbConnectionWatchDog( int check_interval = 5, QObject *_parent = 0 );
  
      ~DbConnectionWatchDog() {}
  
      /// Deleted Copy Constructor
      DbConnectionWatchDog( const DbConnectionWatchDog& source ) = delete;
      /// Deleted Assignment Operator
      DbConnectionWatchDog& operator=( const DbConnectionWatchDog& ) = delete;
      /// Deleted Move Constructor
      DbConnectionWatchDog( DbConnectionWatchDog&& ) = delete;
      /// Deleted Move Operator
      DbConnectionWatchDog& operator=( DbConnectionWatchDog&& ) = delete;
  
      void    start();
  
  private:
      QPointer<QTimer>    m_pTimer;               ///< The timer object this guard is based on.
      int                 m_check_interval;       ///< The current check_interval the connections are checked.
      int                 m_original_interval;    ///< The check_interval the connections are checked if present.
      bool                m_dbc_valid;            ///< Private member reflecting the state. True for no problems, false for problems.
  
  signals:
      void    signalDbConnected( const QString& db_name, bool is_open );
  
  private slots:
      /*!
       * \brief Slot being called if the timer reaches its timeout value, starting the connectioncheck.
       */
      void    slotStartConnectionCheck();
  };
  
  }       /* End namespace components */
  }       /* End namespace osdev      */
  
  #endif  /* OSDEV_COMPONENTS_DBCONNECTIONWATCHDOG_H */