///*****************************************************************************
//
//Copyright (c) 1997, 2018, Oracle and/or its affiliates. All Rights Reserved.
//
//This program is free software; you can redistribute it and/or modify it under
//the terms of the GNU General Public License, version 2.0, as published by the
//Free Software Foundation.
//
//This program is also distributed with certain software (including but not
//limited to OpenSSL) that is licensed under separate terms, as designated in a
//particular file or component or in included license documentation. The authors
//of MySQL hereby grant you an additional permission to link the program and
//your derivative works with the separately licensed software that they have
//included with MySQL.
//
//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, version 2.0,
//for more details.
//
//You should have received a copy of the GNU General Public License along with
//this program; if not, write to the Free Software Foundation, Inc.,
//51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
//
//*****************************************************************************/
//
///** @file include/read0read.h
// Cursor read
//
// Created 2/16/1997 Heikki Tuuri
// *******************************************************/
//
//#ifndef read0read_h
//#define read0read_h
//
//#include <stddef.h>
//#include <algorithm>
//
//#include "read0types.h"
//#include "univ.i"
//
///** The MVCC read view manager */
//class MVCC {
// public:
//  /** Constructor
//  @param size		Number of views to pre-allocate */
//  explicit MVCC(ulint size);
//
//  /** Destructor.
//  Free all the views in the m_free list */
//  ~MVCC();
//
//  /**
//  Allocate and create a view.
//  @param view		view owned by this class created for the
//                          caller. Must be freed by calling close()
//  @param trx		transaction creating the view */
//  void view_open(ReadView *&view, trx_t *trx);
//
//  /**
//  Close a view created by the above function.
//  @param view		view allocated by trx_open.
//  @param own_mutex	true if caller owns trx_sys_t::mutex */
//  void view_close(ReadView *&view, bool own_mutex);
//
//  /**
//  Release a view that is inactive but not closed. Caller must own
//  the trx_sys_t::mutex.
//  @param view		View to release */
//  void view_release(ReadView *&view);
//
//  /** Clones the oldest view and stores it in view. No need to
//  call view_close(). The caller owns the view that is passed in.
//  It will also move the closed views from the m_views list to the
//  m_free list. This function is called by Purge to create it view.
//  @param view		Preallocated view, owned by the caller */
//  void clone_oldest_view(ReadView *view);
//
//  /**
//  @return the number of active views */
//  ulint size() const;
//
//  /**
//  @return true if the view is active and valid */
//  static bool is_view_active(ReadView *view) {
//    ut_a(view != reinterpret_cast<ReadView *>(0x1));
//
//    return (view != NULL && !(intptr_t(view) & 0x1));
//  }
//
//  /**
//  Set the view creator transaction id. Note: This shouldbe set only
//  for views created by RW transactions. */
//  static void set_view_creator_trx_id(ReadView *view, trx_id_t id);
//
// private:
//  /**
//  Validates a read view list. */
//  bool validate() const;
//
//  /**
//  Find a free view from the active list, if none found then allocate
//  a new view. This function will also attempt to move delete marked
//  views from the active list to the freed list.
//  @return a view to use */
//  inline ReadView *get_view();
//
//  /**
//  Get the oldest view in the system. It will also move the delete
//  marked read views from the views list to the freed list.
//  @return oldest view if found or NULL */
//  inline ReadView *get_oldest_view() const;
//  ReadView *get_view_created_by_trx_id(trx_id_t trx_id) const;
//
// private:
//  // Prevent copying
//  MVCC(const MVCC &);
//  MVCC &operator=(const MVCC &);
//
// private:
//  typedef UT_LIST_BASE_NODE_T(ReadView) view_list_t;
//
//  /** Free views ready for reuse. */
//  view_list_t m_free;
//
//  /** Active and closed views, the closed views will have the
//  creator trx id set to TRX_ID_MAX */
//  view_list_t m_views;
//};
//
//#endif /* read0read_h */