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kvdb.h
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kvdb.h
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// Copyright (c) 2016 The LoMoCoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef LOMOCOIN_KVDB_H
#define LOMOCOIN_KVDB_H
#include "util.h"
#include <boost/thread.hpp>
class CKVDBEngine
{
public:
virtual ~CKVDBEngine() {}
virtual bool Open() = 0;
virtual void Close() = 0;
virtual bool Get(const CDataStream& ssKey,CDataStream& ssValue) = 0;
virtual bool Put(const CDataStream& ssKey,const CDataStream& ssValue, bool fOverwrite) = 0;
virtual bool Remove(const CDataStream& ssKey) = 0;
virtual bool MoveFirst() = 0;
virtual bool MoveNext(CDataStream& ssKey,CDataStream& ssValue) = 0;
};
class CKVDBWalker
{
public:
virtual bool Handle(CDataStream& ssKey, CDataStream& ssValue) = 0;
};
class CKVDB
{
public:
CKVDB(CKVDBEngine * engine = NULL) : dbEngine(engine)
{
LOCK(cs);
if (dbEngine != NULL)
{
if (!dbEngine->Open())
{
delete dbEngine;
dbEngine = NULL;
}
}
}
virtual ~CKVDB()
{
LOCK(cs);
if (dbEngine != NULL)
{
dbEngine->Close();
delete dbEngine;
}
}
bool IsValid() const
{
return (dbEngine != NULL);
}
bool Import(const CDataStream& ssKey,const CDataStream& ssValue)
{
try
{
LOCK(cs);
if (dbEngine == NULL)
return false;
return dbEngine->Put(ssKey,ssValue,true);
}
catch (...)
{
}
return false;
}
protected:
template<typename K, typename T>
bool Read(const K& key, T& value)
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(ssKey.GetSerializeSize(key));
ssKey << key;
CDataStream ssValue(SER_DISK, CLIENT_VERSION);
try
{
LOCK(cs);
if (dbEngine == NULL)
return false;
if (dbEngine->Get(ssKey,ssValue))
{
ssValue >> value;
return true;
}
}
catch (const boost::thread_interrupted&)
{
throw;
}
catch (...)
{
}
return false;
}
template<typename K, typename T>
bool Write(const K& key, const T& value, bool fOverwrite=true)
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(ssKey.GetSerializeSize(key));
ssKey << key;
CDataStream ssValue(SER_DISK, CLIENT_VERSION);
ssValue.reserve(ssValue.GetSerializeSize(value));
ssValue << value;
try
{
LOCK(cs);
if (dbEngine == NULL)
return false;
return dbEngine->Put(ssKey,ssValue,fOverwrite);
}
catch (const boost::thread_interrupted&)
{
throw;
}
catch (...)
{
}
return false;
}
template<typename K>
bool Erase(const K& key)
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(ssKey.GetSerializeSize(key));
ssKey << key;
try
{
LOCK(cs);
if (dbEngine == NULL)
return false;
return dbEngine->Remove(ssKey);
}
catch (const boost::thread_interrupted&)
{
throw;
}
catch (...)
{
}
return false;
}
bool WalkThrough(CKVDBWalker& Walker)
{
try
{
LOCK(cs);
if (dbEngine == NULL)
return false;
if (!dbEngine->MoveFirst())
return false;
for (;;)
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
CDataStream ssValue(SER_DISK, CLIENT_VERSION);
if (!dbEngine->MoveNext(ssKey,ssValue))
break;
if (!Walker.Handle(ssKey,ssValue))
break;
}
return true;
}
catch (const boost::thread_interrupted&)
{
throw;
}
catch (...)
{
}
return false;
}
protected:
CCriticalSection cs;
CKVDBEngine * dbEngine;
};
#endif //LOMOCOIN_KVDB_H