StatementCache.hh

//********************************************************************
//*** ResourcePool/oracle/StatementCache.hh
//*** Copyright (c) 2003-2009 by Markus Winand <mws@fatalmind.com>
//*** $Id: StatementCache.hh,v 1.13 2009-03-02 14:16:46 mws Exp $
//********************************************************************
/*
This file is part of ResourcePool.

ResourcePool 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; either version 2 of 
the License, or (at your option) any later version.

ResourcePool 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 ResourcePool; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307  USA */

#ifndef RESOURCEPOOL_ORACLE_STATEMENTCACHE_HH
#define RESOURCEPOOL_ORACLE_STATEMENTCACHE_HH

#ifndef RESOURCEPOOL_ORACLE_OCIHANDLEFWD_HH
#include "OCIHandleFwd.hh"
#endif

#ifndef INCLUDED_GC_PTR_HH
#include "mm/gc_ptr.hh"
#endif

#ifndef RESOURCEPOOL_ORACLE_ORACLESTATEMENT_HH
#include "oracleStatement.hh"
#endif

#include <map>
#include <string>

namespace fatalmind {
namespace oracle {

class StatementCache {
    public:
        typedef gc_ptr<OCIStatementHandle> handle_t;

        StatementCache(unsigned int maxsz = 65535, StatementCache* parent = 0);
        ~StatementCache();

        // to ensure the handle is not deleted (expired from the cache)
        // while it is still used by the client, the client has to
        // assign it to a oracle::StatementCache::handle_t
        // the return is passed as reference to avoid an additional temporary
        // TODO: hide so that only oracleHandles can use it!
        handle_t& open(const oracleStatement& sql, bool parentcache = false);
    private:
        handle_t* check(const oracleStatement& sql);

        void expire();
        void chksize();

        unsigned int _maxsz;
        StatementCache* _parent;

        typedef std::pair<oracleStatement, handle_t> element_t;
        typedef std::map<oracleStatement, handle_t> map_t;
        map_t _map;
    // hidden stuff
        StatementCache(const StatementCache&);
        StatementCache* operator=(const StatementCache&);
};

}
}
#endif

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