dbconnectionwatchdog.h
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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 */