/*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _circache_h_included_
#define _circache_h_included_
/* @(#$Id: $ (C) 2009 J.F.Dockes */
/**
* A data cache implemented as a circularly managed file
*
* A single file is used to stored objects. The file grows to a
* specified maximum size, then is rewritten from the start,
* overwriting older entries.
*
* Data objects inside the cache each have two parts: a data segment and an
* attribute (metadata) dictionary.
* They are named using the same identifiers that are used inside the Recoll
* index, but any unique identifier scheme would work.
*
* The names are stored in an auxiliary index for fast access. This index can
* be rebuilt from the main file.
*/
#include <sys/types.h>
#include <string>
#ifndef NO_NAMESPACES
using std::string;
#endif
class CirCacheInternal;
class CirCache {
public:
CirCache(const string& dir);
virtual ~CirCache();
virtual string getReason();
virtual bool create(off_t maxsize, bool onlyifnotexists = true);
enum OpMode {CC_OPREAD, CC_OPWRITE};
virtual bool open(OpMode mode);
virtual bool get(const string& udi, string& dic, string& data,
int instance = -1);
virtual bool put(const string& udi, const string& dic, const string& data);
/* Maybe we'll have separate iterators one day, but this is good enough for
* now. No put() operations should be performed while using these.
*/
virtual bool rewind(bool& eof);
virtual bool next(bool& eof);
virtual bool getcurrent(string& udi, string& dic, string& data);
virtual bool getcurrentdict(string& dict);
/* Debug */
virtual bool dump();
protected:
CirCacheInternal *m_d;
string m_dir;
private:
CirCache(const CirCache&) {}
CirCache& operator=(const CirCache&) {return *this;}
};
#endif /* _circache_h_included_ */