text: // Copyright (c) 2014-2019, The Monero Project
  //
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  //
  // 2. Redistributions in binary form must reproduce the above copyright notice, this list
  //    of conditions and the following disclaimer in the documentation and/or other
  //    materials provided with the distribution.
  //
  // 3. Neither the name of the copyright holder nor the names of its contributors may be
  //    used to endorse or promote products derived from this software without specific
  //    prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
  
  #pragma once
  
  namespace cryptonote
  {
      // This class is meant to create a batch when none currently exists.
      // If a batch exists, it can't be from another thread, since we can
      // only be called with the txpool lock taken, and it is held during
      // the whole prepare/handle/cleanup incoming block sequence.
      class LockedTXN {
      public:
        LockedTXN(Blockchain &b): m_db{b.get_db()} {
          m_batch = m_db.batch_start();
        }
        LockedTXN(const LockedTXN &) = delete;
        LockedTXN &operator=(const LockedTXN &) = delete;
        LockedTXN(LockedTXN &&o) : m_db{o.m_db}, m_batch{o.m_batch} { o.m_batch = false; }
        LockedTXN &operator=(LockedTXN &&) = delete;
  
        void commit() { try { if (m_batch) { m_db.batch_stop(); m_batch = false; } } catch (const std::exception &e) { MWARNING("LockedTXN::commit filtering exception: " << e.what()); } }
        void abort() { try { if (m_batch) { m_db.batch_abort(); m_batch = false; } } catch (const std::exception &e) { MWARNING("LockedTXN::abort filtering exception: " << e.what()); } }
        ~LockedTXN() { this->abort(); }
      private:
        BlockchainDB &m_db;
        bool m_batch;
      };
  }
  