5251bf3a
 Steven de Ridder
Initial commit. d...
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#ifndef OSDEV_COMPONENTS_TIMELINE_H
#define OSDEV_COMPONENTS_TIMELINE_H
// boost
#include <boost/circular_buffer.hpp>
#include "ormbatchchange.h"
namespace osdev {
namespace components {
/**
* @brief The timeline contains the changes that where made to a specific Batch/Merge update table.
* Only a small number of changes is recorded. A change arrives that is older then the oldest recorded
* change this change will not be considered.
*/
class Timeline
{
public:
/**
* @brief Creates an empty timeline.
*/
Timeline();
// Non copyable, non movable.
Timeline(const Timeline&) = delete;
Timeline& operator=(const Timeline&) = delete;
Timeline(Timeline&&) = delete;
Timeline& operator=(Timeline&&) = delete;
/**
* @brief Evaluate an incoming change against the already registered changes.
* A previously evaluated change is discarded.
* @param desiredChange The incoming change.
* @param exclusiveUpdate Flag that indicates if this change should be evaluated in an exclusive manner.
* @return The reshaped and possibly invalidated change that is left.
* @note The evaluated change is cached so that it can be commited if the database update actually succeeds.
*/
const OrmBatchChange& evaluate(const OrmBatchChange& desiredChange, bool exclusiveUpdate);
/**
* @brief Commit an evaluated change.
* Only valid proposals are commited. This method should be called when the change
* is sucessfuly written to the database.
* @note To make this somewhat trustworthy the underlying database should support transactions.
*/
void commit();
private:
boost::circular_buffer<OrmBatchChange> m_timeline; ///< Only a small number of changes are buffered.
OrmBatchChange m_proposedChange; ///< Cache the evaluated proposed change for commiting.
};
} /* End namespace components */
} /* End namespace osdev */
#endif /* OSDEV_COMPONENTS_TIMELINE_H */
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