/* Copyright (C) 2009 J.F.Dockes
* 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_
/**
* 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 (the UDI).
*
* Inside the file. the UDIs are stored inside the entry dictionary
* under the key "udi".
*
* It is assumed that the dictionary are small (they are routinely read/parsed)
*
*/
#include <sys/types.h>
#include <string>
#ifndef NO_NAMESPACES
using std::string;
#endif
class ConfSimple;
class CirCacheInternal;
class CirCache {
public:
CirCache(const string& dir);
virtual ~CirCache();
virtual string getReason();
enum CreateFlags {CC_CRNONE=0,
// Unique entries: erase older instances when same udi
// is stored.
CC_CRUNIQUE=1,
// Truncate file (restart from scratch).
CC_CRTRUNCATE = 2};
virtual bool create(off_t maxsize, int flags);
enum OpMode {CC_OPREAD, CC_OPWRITE};
virtual bool open(OpMode mode);
virtual std::string getpath();
virtual bool get(const string& udi, string& dic, string& data,
int instance = -1);
// Note: the dicp MUST have an udi entry
enum PutFlags {NoCompHint = 1};
virtual bool put(const string& udi, const ConfSimple *dicp,
const string& data, unsigned int flags = 0);
virtual bool erase(const string& udi);
/** Walk the archive.
*
* Maybe we'll have separate iterators one day, but this is good
* enough for now. No put() operations should be performed while
* using these.
*/
/** Back to oldest */
virtual bool rewind(bool& eof);
/** Get entry under cursor */
virtual bool getCurrent(string& udi, string& dic, string& data);
/** Get current entry udi only. Udi can be empty (erased empty), caller
* should call again */
virtual bool getCurrentUdi(string& udi);
/** Skip to next. (false && !eof) -> error, (false&&eof)->EOF. */
virtual bool next(bool& eof);
/* Debug. This writes the entry headers to stdout */
virtual bool dump();
protected:
CirCacheInternal *m_d;
string m_dir;
private:
CirCache(const CirCache&) {}
CirCache& operator=(const CirCache&) {return *this;}
};
#endif /* _circache_h_included_ */