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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (c) 2010 David Shrewsbury <shrewsbury.dave@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
*/
/**
* @file
* Declaration of a class used to manage Transaction messages so that they
* can be retrieved as a collection.
*/
#ifndef DRIZZLED_MESSAGE_TRANSACTION_MANAGER_H
#define DRIZZLED_MESSAGE_TRANSACTION_MANAGER_H
#include "drizzled/message/transaction.pb.h"
#include <string>
#include <vector>
#include <boost/unordered_map.hpp>
typedef std::vector<std::string> MsgBufferType;
namespace drizzled
{
namespace message
{
/**
* Simple (example) Transaction message buffer and content manager.
*
* @details
* This class groups Transaction messages together by transaction ID and
* buffers them together in memory. Obviously, this could eat up a lot of
* memory if you have very large transactions. A more robust implementation
* would buffer larger transactions to disk rather than memory.
*
* @note
* Once you have a complete transaction and have processed it, you should
* call remove() to remove the cache contents for that transaction from memory.
*/
class TransactionManager
{
public:
/**
* Store the given Transaction message in a buffer.
*
* @param[in] transaction Pointer to the Transaction message to store.
*
* @retval true Success
* @retval false Failure
*/
bool store(const drizzled::message::Transaction &transaction);
/**
* Clear the buffer contents for a given transaction ID.
*
* @param[in] trx_id The transaction ID for the transaction to remove
*
* @retval true Success
* @retval false Failure
*/
bool remove(uint64_t trx_id);
/**
* Check to see if any Transaction messages exist for a given transaction.
*
* @param[in] trx_id The transaction ID to check for.
*
* @retval true Transaction messages exist
* @retval false No Transaction messages found
*/
bool contains(uint64_t trx_id);
/**
* Return number of cached elements for the given transaction ID.
*
* @param[in] trx_id Transaction ID
*
* @returns The number of cached elements associated with trx_id.
*/
uint32_t getTransactionBufferSize(uint64_t trx_id);
/**
* Retrieve a Transaction message from the managed cache.
*
* Caller must supply a Transaction message to populate. The Transaction
* message to retrieve is indexed by a combination of transaction ID and
* position.
*
* @param[out] transaction Transaction message to populate
* @param[in] trx_id Transaction ID
* @param[in] position Index into the buffer associated with trx_id
*
* @retval true Success
* @retval false Failure
*/
bool getTransactionMessage(drizzled::message::Transaction &transaction,
uint64_t trx_id,
uint32_t position);
private:
/**
* Our message buffer cache, mapped by the transaction ID.
*
* We organize Transactions messages by grouping them by transaction ID,
* then storing the messages in std::vectors in std::string format. The
* string format is convenient because it can be easily copied around
* (GPB messages do not provide deep copying).
*/
boost::unordered_map<uint64_t,MsgBufferType> cache;
};
} /* namespace message */
} /* namespace drizzled */
#endif /* DRIZZLED_MESSAGE_TRANSACTION_MANAGER_H */
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