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src/timeline.h 3.59 KB
01f93ffe   Steven de Ridder   licences missing
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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.                                                  *
   * ***************************************************************************/
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 */