~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008-2009 Sun Microsystems, Inc.

 *  Copyright (C) 2009-2010 Jay Pipes <jaypipes@gmail.com>

 *

 *  Authors:

 *

 *    Jay Pipes <jaypipes@gmail.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

 */

#pragma once

#include <drizzled/atomics.h>

#include <drizzled/plugin/replication.h>

#include <string>

#include <vector>

#include <utility>

#include <drizzled/visibility.h>

namespace drizzled {

/**

 * This is a class which manages transforming internal 

 * transactional events into GPB messages and sending those

 * events out through registered replicators and appliers.

 */

class DRIZZLED_API ReplicationServices

{

public:

  typedef uint64_t GlobalTransactionId;

  /**

   * Types of messages that can go in the transaction

   * log file.  Every time something is written into the

   * transaction log, it is preceded by a header containing

   * the type of message which follows.

   */

  enum MessageType

  {

    TRANSACTION= 1, /* A GPB Transaction Message */

    BLOB= 2 /* A BLOB value */

  };

  typedef std::pair<plugin::TransactionReplicator *, plugin::TransactionApplier *> ReplicationPair;

  typedef std::vector<ReplicationPair> ReplicationStreams;

  /**

   * Method which is called after plugins have been loaded but

   * before the first client connects.  It determines if the registration

   * of applier and replicator plugins is proper and pairs

   * the applier and requested replicator plugins into the replication

   * streams.

   *

   * @todo

   *

   * This is only necessary because we don't yet have plugin dependency

   * tracking...

   */

  bool evaluateRegisteredPlugins();

  /** 

   * Helper method which pushes a constructed message out to the registered

   * replicator and applier plugins.

   *

   * @param Session descriptor

   * @param Message to push out

   */

  plugin::ReplicationReturnCode pushTransactionMessage(Session &in_session,

                                                       message::Transaction &to_push);

  /**

   * Constructor

   */

  ReplicationServices();

  /**

   * Singleton method

   * Returns the singleton instance of ReplicationServices

   */

  static inline ReplicationServices &singleton()

  {

    static ReplicationServices replication_services;

    return replication_services;

  }

  /**

   * Returns whether the ReplicationServices object

   * is active.  In other words, does it have both

   * a replicator and an applier that are *active*?

   */

  bool isActive() const;

  /**

   * Returns the list of replication streams

   */

  ReplicationStreams &getReplicationStreams();

  /**

   * Attaches a replicator to our internal collection of

   * replicators.

   *

   * @param Pointer to a replicator to attach/register

   */

  void attachReplicator(plugin::TransactionReplicator *in_replicator);

  /**

   * Detaches/unregisters a replicator with our internal

   * collection of replicators.

   *

   * @param Pointer to the replicator to detach

   */

  void detachReplicator(plugin::TransactionReplicator *in_replicator);

  /**

   * Attaches a applier to our internal collection of

   * appliers.

   *

   * @param Pointer to a applier to attach/register

   * @param The name of the replicator to pair with

   */

  void attachApplier(plugin::TransactionApplier *in_applier, const std::string &requested_replicator);

  /**

   * Detaches/unregisters a applier with our internal

   * collection of appliers.

   *

   * @param Pointer to the applier to detach

   */

  void detachApplier(plugin::TransactionApplier *in_applier);

  /** 

   * Returns the timestamp of the last Transaction which was sent to an

   * applier.

   */

  uint64_t getLastAppliedTimestamp() const;

private:

  typedef std::vector<plugin::TransactionReplicator *> Replicators;

  typedef std::vector<std::pair<std::string, plugin::TransactionApplier *> > Appliers;

  /** 

   * Atomic boolean set to true if any *active* replicators

   * or appliers are actually registered.

   */

  bool is_active;

  /**

   * The timestamp of the last time a Transaction message was successfully

   * applied (sent to an Applier)

   */

  atomic<uint64_t> last_applied_timestamp;

  /** Our collection of registered replicator plugins */

  Replicators replicators;

  /** Our collection of registered applier plugins and their requested replicator plugin names */

  Appliers appliers;

  /** Our replication streams */

  ReplicationStreams replication_streams;

  /**

   * Strips underscores and lowercases supplied replicator name

   * or requested name, and appends the suffix "replicator" if missing...

   */

  void normalizeReplicatorName(std::string &name);

};

} /* namespace drizzled */