~drizzle-trunk/drizzle/development

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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
 *
 *  Copyright (C) 2008-2009 Sun Microsystems
 *
 *  Authors:
 *
 *    Jay Pipes <joinfu@sun.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  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 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
 */

#ifndef DRIZZLED_PLUGIN_TRANSACTION_APPLIER_H
#define DRIZZLED_PLUGIN_TRANSACTION_APPLIER_H

/**
 * @file Defines the API for a TransactionApplier
 *
 * A TransactionApplier applies an event it has received from a TransactionReplicator (via 
 * a replicator's replicate() call, or it has read using a TransactionReader's read()
 * call.
 */

#include "drizzled/plugin/plugin.h"
#include "drizzled/atomics.h"

namespace drizzled
{

namespace message { class Transaction; }

namespace plugin
{

/**
 * Base class for appliers of Transaction messages
 */
class TransactionApplier : public Plugin
{
  TransactionApplier();
  TransactionApplier(const TransactionApplier &);
  TransactionApplier& operator=(const TransactionApplier &);
  atomic<bool> is_enabled;
public:
  explicit TransactionApplier(std::string name_arg)
    : Plugin(name_arg, "TransactionApplier")
  {
    is_enabled= true;
  }
  virtual ~TransactionApplier() {}
  /**
   * Apply something to a target.
   *
   * @note
   *
   * It is important to note that memory allocation for the 
   * supplied pointer is not guaranteed after the completion 
   * of this function -- meaning the caller can dispose of the
   * supplied message.  Therefore, appliers which are
   * implementing an asynchronous replication system must copy
   * the supplied message to their own controlled memory storage
   * area.
   *
   * @param Transaction message to be replicated
   */
  virtual void apply(const message::Transaction &to_apply)= 0;

  static bool addPlugin(TransactionApplier *applier);
  static void removePlugin(TransactionApplier *applier);
  virtual bool isEnabled() const
  {
    return is_enabled;
  }

  virtual void enable()
  {
    is_enabled= true;
  }

  virtual void disable()
  {
    is_enabled= false;
  }
};

} /* namespace plugin */
} /* namespace drizzled */

#endif /* DRIZZLED_PLUGIN_TRANSACTION_APPLIER_H */