litecoin/src/db.h

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_DB_H
#define BITCOIN_DB_H

#include "main.h"

#include <map>
#include <string>
#include <vector>

#include <db_cxx.h>

class CAddress;
class CAddrMan;
class CBlockLocator;
class CDiskBlockIndex;
class CDiskTxPos;
class CMasterKey;
class COutPoint;
class CTxIndex;
class CWallet;
class CWalletTx;

extern unsigned int nWalletDBUpdated;
extern bool fDetachDB;
extern DbEnv dbenv;

extern void DBFlush(bool fShutdown);
void ThreadFlushWalletDB(void* parg);
bool BackupWallet(const CWallet& wallet, const std::string& strDest);


/** RAII class that provides access to a Berkeley database */
class CDB
{
protected:
    Db* pdb;
    std::string strFile;
    std::vector<DbTxn*> vTxn;
    bool fReadOnly;

    explicit CDB(const char* pszFile, const char* pszMode="r+");
    ~CDB() { Close(); }
public:
    void Close();
private:
    CDB(const CDB&);
    void operator=(const CDB&);

protected:
    template<typename K, typename T>
    bool Read(const K& key, T& value)
    {
        if (!pdb)
            return false;

        // Key
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(1000);
        ssKey << key;
        Dbt datKey(&ssKey[0], ssKey.size());

        // Read
        Dbt datValue;
        datValue.set_flags(DB_DBT_MALLOC);
        int ret = pdb->get(GetTxn(), &datKey, &datValue, 0);
        memset(datKey.get_data(), 0, datKey.get_size());
        if (datValue.get_data() == NULL)
            return false;

        // Unserialize value
        CDataStream ssValue((char*)datValue.get_data(), (char*)datValue.get_data() + datValue.get_size(), SER_DISK, CLIENT_VERSION);
        ssValue >> value;

        // Clear and free memory
        memset(datValue.get_data(), 0, datValue.get_size());
        free(datValue.get_data());
        return (ret == 0);
    }

    template<typename K, typename T>
    bool Write(const K& key, const T& value, bool fOverwrite=true)
    {
        if (!pdb)
            return false;
        if (fReadOnly)
            assert(!"Write called on database in read-only mode");

        // Key
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(1000);
        ssKey << key;
        Dbt datKey(&ssKey[0], ssKey.size());

        // Value
        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
        ssValue.reserve(10000);
        ssValue << value;
        Dbt datValue(&ssValue[0], ssValue.size());

        // Write
        int ret = pdb->put(GetTxn(), &datKey, &datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));

        // Clear memory in case it was a private key
        memset(datKey.get_data(), 0, datKey.get_size());
        memset(datValue.get_data(), 0, datValue.get_size());
        return (ret == 0);
    }

    template<typename K>
    bool Erase(const K& key)
    {
        if (!pdb)
            return false;
        if (fReadOnly)
            assert(!"Erase called on database in read-only mode");

        // Key
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(1000);
        ssKey << key;
        Dbt datKey(&ssKey[0], ssKey.size());

        // Erase
        int ret = pdb->del(GetTxn(), &datKey, 0);

        // Clear memory
        memset(datKey.get_data(), 0, datKey.get_size());
        return (ret == 0 || ret == DB_NOTFOUND);
    }

    template<typename K>
    bool Exists(const K& key)
    {
        if (!pdb)
            return false;

        // Key
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(1000);
        ssKey << key;
        Dbt datKey(&ssKey[0], ssKey.size());

        // Exists
        int ret = pdb->exists(GetTxn(), &datKey, 0);

        // Clear memory
        memset(datKey.get_data(), 0, datKey.get_size());
        return (ret == 0);
    }

    Dbc* GetCursor()
    {
        if (!pdb)
            return NULL;
        Dbc* pcursor = NULL;
        int ret = pdb->cursor(NULL, &pcursor, 0);
        if (ret != 0)
            return NULL;
        return pcursor;
    }

    int ReadAtCursor(Dbc* pcursor, CDataStream& ssKey, CDataStream& ssValue, unsigned int fFlags=DB_NEXT)
    {
        // Read at cursor
        Dbt datKey;
        if (fFlags == DB_SET || fFlags == DB_SET_RANGE || fFlags == DB_GET_BOTH || fFlags == DB_GET_BOTH_RANGE)
        {
            datKey.set_data(&ssKey[0]);
            datKey.set_size(ssKey.size());
        }
        Dbt datValue;
        if (fFlags == DB_GET_BOTH || fFlags == DB_GET_BOTH_RANGE)
        {
            datValue.set_data(&ssValue[0]);
            datValue.set_size(ssValue.size());
        }
        datKey.set_flags(DB_DBT_MALLOC);
        datValue.set_flags(DB_DBT_MALLOC);
        int ret = pcursor->get(&datKey, &datValue, fFlags);
        if (ret != 0)
            return ret;
        else if (datKey.get_data() == NULL || datValue.get_data() == NULL)
            return 99999;

        // Convert to streams
        ssKey.SetType(SER_DISK);
        ssKey.clear();
        ssKey.write((char*)datKey.get_data(), datKey.get_size());
        ssValue.SetType(SER_DISK);
        ssValue.clear();
        ssValue.write((char*)datValue.get_data(), datValue.get_size());

        // Clear and free memory
        memset(datKey.get_data(), 0, datKey.get_size());
        memset(datValue.get_data(), 0, datValue.get_size());
        free(datKey.get_data());
        free(datValue.get_data());
        return 0;
    }

    DbTxn* GetTxn()
    {
        if (!vTxn.empty())
            return vTxn.back();
        else
            return NULL;
    }

public:
    bool TxnBegin()
    {
        if (!pdb)
            return false;
        DbTxn* ptxn = NULL;
        int ret = dbenv.txn_begin(GetTxn(), &ptxn, DB_TXN_WRITE_NOSYNC);
        if (!ptxn || ret != 0)
            return false;
        vTxn.push_back(ptxn);
        return true;
    }

    bool TxnCommit()
    {
        if (!pdb)
            return false;
        if (vTxn.empty())
            return false;
        int ret = vTxn.back()->commit(0);
        vTxn.pop_back();
        return (ret == 0);
    }

    bool TxnAbort()
    {
        if (!pdb)
            return false;
        if (vTxn.empty())
            return false;
        int ret = vTxn.back()->abort();
        vTxn.pop_back();
        return (ret == 0);
    }

    bool ReadVersion(int& nVersion)
    {
        nVersion = 0;
        return Read(std::string("version"), nVersion);
    }

    bool WriteVersion(int nVersion)
    {
        return Write(std::string("version"), nVersion);
    }

    bool static Rewrite(const std::string& strFile, const char* pszSkip = NULL);
};







/** Access to the transaction database (blkindex.dat) */
class CTxDB : public CDB
{
public:
    CTxDB(const char* pszMode="r+") : CDB("blkindex.dat", pszMode) { }
private:
    CTxDB(const CTxDB&);
    void operator=(const CTxDB&);
public:
    bool ReadTxIndex(uint256 hash, CTxIndex& txindex);
    bool UpdateTxIndex(uint256 hash, const CTxIndex& txindex);
    bool AddTxIndex(const CTransaction& tx, const CDiskTxPos& pos, int nHeight);
    bool EraseTxIndex(const CTransaction& tx);
    bool ContainsTx(uint256 hash);
    bool ReadOwnerTxes(uint160 hash160, int nHeight, std::vector<CTransaction>& vtx);
    bool ReadDiskTx(uint256 hash, CTransaction& tx, CTxIndex& txindex);
    bool ReadDiskTx(uint256 hash, CTransaction& tx);
    bool ReadDiskTx(COutPoint outpoint, CTransaction& tx, CTxIndex& txindex);
    bool ReadDiskTx(COutPoint outpoint, CTransaction& tx);
    bool WriteBlockIndex(const CDiskBlockIndex& blockindex);
    bool ReadHashBestChain(uint256& hashBestChain);
    bool WriteHashBestChain(uint256 hashBestChain);
    bool ReadBestInvalidWork(CBigNum& bnBestInvalidWork);
    bool WriteBestInvalidWork(CBigNum bnBestInvalidWork);
    bool LoadBlockIndex();
};




/** Access to the (IP) address database (peers.dat) */
class CAddrDB
{
private:
    boost::filesystem::path pathAddr;
public:
    CAddrDB();
    bool Write(const CAddrMan& addr);
    bool Read(CAddrMan& addr);
};

#endif // BITCOIN_DB_H