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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008 Sun Microsystems
*
* 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_RESOURCE_CONTEXT_H
#define DRIZZLED_RESOURCE_CONTEXT_H
#include <cstddef>
namespace drizzled
{
namespace plugin
{
class StorageEngine;
}
/**
* Either statement transaction or normal transaction - related
* session-specific storage engine data.
*
* If a storage engine participates in a statement/transaction,
* an instance of this class is present in
* session->transaction.{stmt|all}.resource_contexts.
*
* When it's time to commit or rollback, each element of ha_list
* is used to access resource manager's prepare()/commit()/rollback()
* methods, and also to evaluate if a full two phase commit is
* necessary.
*
* @sa General description of transaction handling in drizzled/transaction_services.cc.
*/
class ResourceContext
{
public:
ResourceContext() :
resource(NULL),
modified_data(false)
{}
/** Clear, prepare for reuse. */
void reset();
/**
* Marks that the underlying resource manager
* has modified data state.
*/
void markModifiedData();
/**
* Returns true if the underlying resource manager
* has modified data state.
*/
bool hasModifiedData() const;
/**
* Returns true if the underlying resource
* manager has registered with the transaction
* manager for this transaction.
*/
bool isStarted() const;
/**
* Mark this context as modifying data if the argument has also modified data
*/
void coalesceWith(const ResourceContext *stmt_trx);
/**
* Returns the underlying resource manager
* this context tracks.
*/
drizzled::plugin::StorageEngine *getResource() const
{
return resource;
}
/**
* Sets the underlying resource
*/
void setResource(drizzled::plugin::StorageEngine *in_engine)
{
resource= in_engine;
}
private:
/**
Although a given ResourceContext instance is always used
for the same resource manager, 'resource' is not-NULL only when the
corresponding resource manager is a part of a transaction.
*/
drizzled::plugin::StorageEngine *resource;
/**
* Whether the underlying resource manager has changed
* some data state.
*/
bool modified_data;
};
} /* namespace drizzled */
#endif /* DRIZZLED_RESOURCE_CONTEXT_H */
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