twister-core/db.cpp

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

#include "headers.h"

void ThreadFlushWalletDB(void* parg);


unsigned int nWalletDBUpdated;
uint64 nAccountingEntryNumber = 0;



//
// CDB
//

static CCriticalSection cs_db;
static bool fDbEnvInit = false;
DbEnv dbenv(0);
static map<string, int> mapFileUseCount;
static map<string, Db*> mapDb;

class CDBInit
{
public:
    CDBInit()
    {
    }
    ~CDBInit()
    {
        if (fDbEnvInit)
        {
            dbenv.close(0);
            fDbEnvInit = false;
        }
    }
}
instance_of_cdbinit;


CDB::CDB(const char* pszFile, const char* pszMode) : pdb(NULL)
{
    int ret;
    if (pszFile == NULL)
        return;

    fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
    bool fCreate = strchr(pszMode, 'c');
    unsigned int nFlags = DB_THREAD;
    if (fCreate)
        nFlags |= DB_CREATE;

    CRITICAL_BLOCK(cs_db)
    {
        if (!fDbEnvInit)
        {
            if (fShutdown)
                return;
            string strDataDir = GetDataDir();
            string strLogDir = strDataDir + "/database";
            filesystem::create_directory(strLogDir.c_str());
            string strErrorFile = strDataDir + "/db.log";
            printf("dbenv.open strLogDir=%s strErrorFile=%s\n", strLogDir.c_str(), strErrorFile.c_str());

            dbenv.set_lg_dir(strLogDir.c_str());
            dbenv.set_lg_max(10000000);
            dbenv.set_lk_max_locks(10000);
            dbenv.set_lk_max_objects(10000);
            dbenv.set_errfile(fopen(strErrorFile.c_str(), "a")); /// debug
            dbenv.set_flags(DB_AUTO_COMMIT, 1);
            ret = dbenv.open(strDataDir.c_str(),
                             DB_CREATE     |
                             DB_INIT_LOCK  |
                             DB_INIT_LOG   |
                             DB_INIT_MPOOL |
                             DB_INIT_TXN   |
                             DB_THREAD     |
                             DB_RECOVER,
                             S_IRUSR | S_IWUSR);
            if (ret > 0)
                throw runtime_error(strprintf("CDB() : error %d opening database environment", ret));
            fDbEnvInit = true;
        }

        strFile = pszFile;
        ++mapFileUseCount[strFile];
        pdb = mapDb[strFile];
        if (pdb == NULL)
        {
            pdb = new Db(&dbenv, 0);

            ret = pdb->open(NULL,      // Txn pointer
                            pszFile,   // Filename
                            "main",    // Logical db name
                            DB_BTREE,  // Database type
                            nFlags,    // Flags
                            0);

            if (ret > 0)
            {
                delete pdb;
                pdb = NULL;
                CRITICAL_BLOCK(cs_db)
                    --mapFileUseCount[strFile];
                strFile = "";
                throw runtime_error(strprintf("CDB() : can't open database file %s, error %d", pszFile, ret));
            }

            if (fCreate && !Exists(string("version")))
            {
                bool fTmp = fReadOnly;
                fReadOnly = false;
                WriteVersion(VERSION);
                fReadOnly = fTmp;
            }

            mapDb[strFile] = pdb;
        }
    }
}

void CDB::Close()
{
    if (!pdb)
        return;
    if (!vTxn.empty())
        vTxn.front()->abort();
    vTxn.clear();
    pdb = NULL;

    // Flush database activity from memory pool to disk log
    unsigned int nMinutes = 0;
    if (strFile == "addr.dat")
        nMinutes = 2;
    if (strFile == "blkindex.dat" && IsInitialBlockDownload() && nBestHeight % 500 != 0)
        nMinutes = 1;
    dbenv.txn_checkpoint(0, nMinutes, 0);

    CRITICAL_BLOCK(cs_db)
        --mapFileUseCount[strFile];
}

void CloseDb(const string& strFile)
{
    CRITICAL_BLOCK(cs_db)
    {
        if (mapDb[strFile] != NULL)
        {
            // Close the database handle
            Db* pdb = mapDb[strFile];
            pdb->close(0);
            delete pdb;
            mapDb[strFile] = NULL;
        }
    }
}

void DBFlush(bool fShutdown)
{
    // Flush log data to the actual data file
    //  on all files that are not in use
    printf("DBFlush(%s)%s\n", fShutdown ? "true" : "false", fDbEnvInit ? "" : " db not started");
    if (!fDbEnvInit)
        return;
    CRITICAL_BLOCK(cs_db)
    {
        map<string, int>::iterator mi = mapFileUseCount.begin();
        while (mi != mapFileUseCount.end())
        {
            string strFile = (*mi).first;
            int nRefCount = (*mi).second;
            printf("%s refcount=%d\n", strFile.c_str(), nRefCount);
            if (nRefCount == 0)
            {
                // Move log data to the dat file
                CloseDb(strFile);
                dbenv.txn_checkpoint(0, 0, 0);
                printf("%s flush\n", strFile.c_str());
                dbenv.lsn_reset(strFile.c_str(), 0);
                mapFileUseCount.erase(mi++);
            }
            else
                mi++;
        }
        if (fShutdown)
        {
            char** listp;
            if (mapFileUseCount.empty())
                dbenv.log_archive(&listp, DB_ARCH_REMOVE);
            dbenv.close(0);
            fDbEnvInit = false;
        }
    }
}






//
// CTxDB
//

bool CTxDB::ReadTxIndex(uint256 hash, CTxIndex& txindex)
{
    assert(!fClient);
    txindex.SetNull();
    return Read(make_pair(string("tx"), hash), txindex);
}

bool CTxDB::UpdateTxIndex(uint256 hash, const CTxIndex& txindex)
{
    assert(!fClient);
    return Write(make_pair(string("tx"), hash), txindex);
}

bool CTxDB::AddTxIndex(const CTransaction& tx, const CDiskTxPos& pos, int nHeight)
{
    assert(!fClient);

    // Add to tx index
    uint256 hash = tx.GetHash();
    CTxIndex txindex(pos, tx.vout.size());
    return Write(make_pair(string("tx"), hash), txindex);
}

bool CTxDB::EraseTxIndex(const CTransaction& tx)
{
    assert(!fClient);
    uint256 hash = tx.GetHash();

    return Erase(make_pair(string("tx"), hash));
}

bool CTxDB::ContainsTx(uint256 hash)
{
    assert(!fClient);
    return Exists(make_pair(string("tx"), hash));
}

bool CTxDB::ReadOwnerTxes(uint160 hash160, int nMinHeight, vector<CTransaction>& vtx)
{
    assert(!fClient);
    vtx.clear();

    // Get cursor
    Dbc* pcursor = GetCursor();
    if (!pcursor)
        return false;

    unsigned int fFlags = DB_SET_RANGE;
    loop
    {
        // Read next record
        CDataStream ssKey;
        if (fFlags == DB_SET_RANGE)
            ssKey << string("owner") << hash160 << CDiskTxPos(0, 0, 0);
        CDataStream ssValue;
        int ret = ReadAtCursor(pcursor, ssKey, ssValue, fFlags);
        fFlags = DB_NEXT;
        if (ret == DB_NOTFOUND)
            break;
        else if (ret != 0)
        {
            pcursor->close();
            return false;
        }

        // Unserialize
        string strType;
        uint160 hashItem;
        CDiskTxPos pos;
        ssKey >> strType >> hashItem >> pos;
        int nItemHeight;
        ssValue >> nItemHeight;

        // Read transaction
        if (strType != "owner" || hashItem != hash160)
            break;
        if (nItemHeight >= nMinHeight)
        {
            vtx.resize(vtx.size()+1);
            if (!vtx.back().ReadFromDisk(pos))
            {
                pcursor->close();
                return false;
            }
        }
    }

    pcursor->close();
    return true;
}

bool CTxDB::ReadDiskTx(uint256 hash, CTransaction& tx, CTxIndex& txindex)
{
    assert(!fClient);
    tx.SetNull();
    if (!ReadTxIndex(hash, txindex))
        return false;
    return (tx.ReadFromDisk(txindex.pos));
}

bool CTxDB::ReadDiskTx(uint256 hash, CTransaction& tx)
{
    CTxIndex txindex;
    return ReadDiskTx(hash, tx, txindex);
}

bool CTxDB::ReadDiskTx(COutPoint outpoint, CTransaction& tx, CTxIndex& txindex)
{
    return ReadDiskTx(outpoint.hash, tx, txindex);
}

bool CTxDB::ReadDiskTx(COutPoint outpoint, CTransaction& tx)
{
    CTxIndex txindex;
    return ReadDiskTx(outpoint.hash, tx, txindex);
}

bool CTxDB::WriteBlockIndex(const CDiskBlockIndex& blockindex)
{
    return Write(make_pair(string("blockindex"), blockindex.GetBlockHash()), blockindex);
}

bool CTxDB::EraseBlockIndex(uint256 hash)
{
    return Erase(make_pair(string("blockindex"), hash));
}

bool CTxDB::ReadHashBestChain(uint256& hashBestChain)
{
    return Read(string("hashBestChain"), hashBestChain);
}

bool CTxDB::WriteHashBestChain(uint256 hashBestChain)
{
    return Write(string("hashBestChain"), hashBestChain);
}

bool CTxDB::ReadBestInvalidWork(CBigNum& bnBestInvalidWork)
{
    return Read(string("bnBestInvalidWork"), bnBestInvalidWork);
}

bool CTxDB::WriteBestInvalidWork(CBigNum bnBestInvalidWork)
{
    return Write(string("bnBestInvalidWork"), bnBestInvalidWork);
}

CBlockIndex* InsertBlockIndex(uint256 hash)
{
    if (hash == 0)
        return NULL;

    // Return existing
    map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hash);
    if (mi != mapBlockIndex.end())
        return (*mi).second;

    // Create new
    CBlockIndex* pindexNew = new CBlockIndex();
    if (!pindexNew)
        throw runtime_error("LoadBlockIndex() : new CBlockIndex failed");
    mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
    pindexNew->phashBlock = &((*mi).first);

    return pindexNew;
}

bool CTxDB::LoadBlockIndex()
{
    // Get database cursor
    Dbc* pcursor = GetCursor();
    if (!pcursor)
        return false;

    // Load mapBlockIndex
    unsigned int fFlags = DB_SET_RANGE;
    loop
    {
        // Read next record
        CDataStream ssKey;
        if (fFlags == DB_SET_RANGE)
            ssKey << make_pair(string("blockindex"), uint256(0));
        CDataStream ssValue;
        int ret = ReadAtCursor(pcursor, ssKey, ssValue, fFlags);
        fFlags = DB_NEXT;
        if (ret == DB_NOTFOUND)
            break;
        else if (ret != 0)
            return false;

        // Unserialize
        string strType;
        ssKey >> strType;
        if (strType == "blockindex")
        {
            CDiskBlockIndex diskindex;
            ssValue >> diskindex;

            // Construct block index object
            CBlockIndex* pindexNew = InsertBlockIndex(diskindex.GetBlockHash());
            pindexNew->pprev          = InsertBlockIndex(diskindex.hashPrev);
            pindexNew->pnext          = InsertBlockIndex(diskindex.hashNext);
            pindexNew->nFile          = diskindex.nFile;
            pindexNew->nBlockPos      = diskindex.nBlockPos;
            pindexNew->nHeight        = diskindex.nHeight;
            pindexNew->nVersion       = diskindex.nVersion;
            pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
            pindexNew->nTime          = diskindex.nTime;
            pindexNew->nBits          = diskindex.nBits;
            pindexNew->nNonce         = diskindex.nNonce;

            // Watch for genesis block
            if (pindexGenesisBlock == NULL && diskindex.GetBlockHash() == hashGenesisBlock)
                pindexGenesisBlock = pindexNew;

            if (!pindexNew->CheckIndex())
                return error("LoadBlockIndex() : CheckIndex failed at %d", pindexNew->nHeight);
        }
        else
        {
            break;
        }
    }
    pcursor->close();

    // Calculate bnChainWork
    vector<pair<int, CBlockIndex*> > vSortedByHeight;
    vSortedByHeight.reserve(mapBlockIndex.size());
    foreach(const PAIRTYPE(uint256, CBlockIndex*)& item, mapBlockIndex)
    {
        CBlockIndex* pindex = item.second;
        vSortedByHeight.push_back(make_pair(pindex->nHeight, pindex));
    }
    sort(vSortedByHeight.begin(), vSortedByHeight.end());
    foreach(const PAIRTYPE(int, CBlockIndex*)& item, vSortedByHeight)
    {
        CBlockIndex* pindex = item.second;
        pindex->bnChainWork = (pindex->pprev ? pindex->pprev->bnChainWork : 0) + pindex->GetBlockWork();
    }

    // Load hashBestChain pointer to end of best chain
    if (!ReadHashBestChain(hashBestChain))
    {
        if (pindexGenesisBlock == NULL)
            return true;
        return error("CTxDB::LoadBlockIndex() : hashBestChain not loaded");
    }
    if (!mapBlockIndex.count(hashBestChain))
        return error("CTxDB::LoadBlockIndex() : hashBestChain not found in the block index");
    pindexBest = mapBlockIndex[hashBestChain];
    nBestHeight = pindexBest->nHeight;
    bnBestChainWork = pindexBest->bnChainWork;
    printf("LoadBlockIndex(): hashBestChain=%s  height=%d\n", hashBestChain.ToString().substr(0,20).c_str(), nBestHeight);

    // Load bnBestInvalidWork, OK if it doesn't exist
    ReadBestInvalidWork(bnBestInvalidWork);

    // Verify blocks in the best chain
    CBlockIndex* pindexFork = NULL;
    for (CBlockIndex* pindex = pindexBest; pindex && pindex->pprev; pindex = pindex->pprev)
    {
        if (pindex->nHeight < nBestHeight-2500 && !mapArgs.count("-checkblocks"))
            break;
        CBlock block;
        if (!block.ReadFromDisk(pindex))
            return error("LoadBlockIndex() : block.ReadFromDisk failed");
        if (!block.CheckBlock())
        {
            printf("LoadBlockIndex() : *** found bad block at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString().c_str());
            pindexFork = pindex->pprev;
        }
    }
    if (pindexFork)
    {
        // Reorg back to the fork
        printf("LoadBlockIndex() : *** moving best chain pointer back to block %d\n", pindexFork->nHeight);
        CBlock block;
        if (!block.ReadFromDisk(pindexFork))
            return error("LoadBlockIndex() : block.ReadFromDisk failed");
        CTxDB txdb;
        block.SetBestChain(txdb, pindexFork);
    }

    return true;
}





//
// CAddrDB
//

bool CAddrDB::WriteAddress(const CAddress& addr)
{
    return Write(make_pair(string("addr"), addr.GetKey()), addr);
}

bool CAddrDB::EraseAddress(const CAddress& addr)
{
    return Erase(make_pair(string("addr"), addr.GetKey()));
}

bool CAddrDB::LoadAddresses()
{
    CRITICAL_BLOCK(cs_mapAddresses)
    {
        // Load user provided addresses
        CAutoFile filein = fopen((GetDataDir() + "/addr.txt").c_str(), "rt");
        if (filein)
        {
            try
            {
                char psz[1000];
                while (fgets(psz, sizeof(psz), filein))
                {
                    CAddress addr(psz, NODE_NETWORK);
                    addr.nTime = 0; // so it won't relay unless successfully connected
                    if (addr.IsValid())
                        AddAddress(addr);
                }
            }
            catch (...) { }
        }

        // Get cursor
        Dbc* pcursor = GetCursor();
        if (!pcursor)
            return false;

        loop
        {
            // Read next record
            CDataStream ssKey;
            CDataStream ssValue;
            int ret = ReadAtCursor(pcursor, ssKey, ssValue);
            if (ret == DB_NOTFOUND)
                break;
            else if (ret != 0)
                return false;

            // Unserialize
            string strType;
            ssKey >> strType;
            if (strType == "addr")
            {
                CAddress addr;
                ssValue >> addr;
                mapAddresses.insert(make_pair(addr.GetKey(), addr));
            }
        }
        pcursor->close();

        printf("Loaded %d addresses\n", mapAddresses.size());
    }

    return true;
}

bool LoadAddresses()
{
    return CAddrDB("cr+").LoadAddresses();
}




//
// CWalletDB
//

static set<int64> setKeyPool;
static CCriticalSection cs_setKeyPool;

bool CWalletDB::ReadAccount(const string& strAccount, CAccount& account)
{
    account.SetNull();
    return Read(make_pair(string("acc"), strAccount), account);
}

bool CWalletDB::WriteAccount(const string& strAccount, const CAccount& account)
{
    return Write(make_pair(string("acc"), strAccount), account);
}

bool CWalletDB::WriteAccountingEntry(const string& strAccount, const CAccountingEntry& acentry)
{
    return Write(make_tuple(string("acentry"), strAccount, ++nAccountingEntryNumber), acentry);
}

int64 CWalletDB::GetAccountCreditDebit(const string& strAccount)
{
    list<CAccountingEntry> entries;
    ListAccountCreditDebit(strAccount, entries);

    int64 nCreditDebit = 0;
    foreach (const CAccountingEntry& entry, entries)
        nCreditDebit += entry.nCreditDebit;

    return nCreditDebit;
}

void CWalletDB::ListAccountCreditDebit(const string& strAccount, list<CAccountingEntry>& entries)
{
    int64 nCreditDebit = 0;

    Dbc* pcursor = GetCursor();
    if (!pcursor)
        throw runtime_error("CWalletDB::ListAccountCreditDebit() : cannot create DB cursor");
    unsigned int fFlags = DB_SET_RANGE;
    loop
    {
        // Read next record
        CDataStream ssKey;
        if (fFlags == DB_SET_RANGE)
            ssKey << make_tuple(string("acentry"), strAccount, uint64(0));
        CDataStream ssValue;
        int ret = ReadAtCursor(pcursor, ssKey, ssValue, fFlags);
        fFlags = DB_NEXT;
        if (ret == DB_NOTFOUND)
            break;
        else if (ret != 0)
        {
            pcursor->close();
            throw runtime_error("CWalletDB::ListAccountCreditDebit() : error scanning DB");
        }

        // Unserialize
        string strType;
        ssKey >> strType;
        if (strType != "acentry")
            break;
        string strAccountName;
        ssKey >> strAccountName;
        if (strAccountName != strAccount)
            break;

        CAccountingEntry acentry;
        ssValue >> acentry;
        entries.push_back(acentry);
    }

    pcursor->close();
}

bool CWalletDB::LoadWallet()
{
    vchDefaultKey.clear();
    int nFileVersion = 0;

    // Modify defaults
#ifndef __WXMSW__
    // Tray icon sometimes disappears on 9.10 karmic koala 64-bit, leaving no way to access the program
    fMinimizeToTray = false;
    fMinimizeOnClose = false;
#endif

    //// todo: shouldn't we catch exceptions and try to recover and continue?
    CRITICAL_BLOCK(cs_mapKeys)
    CRITICAL_BLOCK(cs_mapWallet)
    {
        // Get cursor
        Dbc* pcursor = GetCursor();
        if (!pcursor)
            return false;

        loop
        {
            // Read next record
            CDataStream ssKey;
            CDataStream ssValue;
            int ret = ReadAtCursor(pcursor, ssKey, ssValue);
            if (ret == DB_NOTFOUND)
                break;
            else if (ret != 0)
                return false;

            // Unserialize
            // Taking advantage of the fact that pair serialization
            // is just the two items serialized one after the other
            string strType;
            ssKey >> strType;
            if (strType == "name")
            {
                string strAddress;
                ssKey >> strAddress;
                ssValue >> mapAddressBook[strAddress];
            }
            else if (strType == "tx")
            {
                uint256 hash;
                ssKey >> hash;
                CWalletTx& wtx = mapWallet[hash];
                ssValue >> wtx;

                if (wtx.GetHash() != hash)
                    printf("Error in wallet.dat, hash mismatch\n");

                //// debug print
                //printf("LoadWallet  %s\n", wtx.GetHash().ToString().c_str());
                //printf(" %12I64d  %s  %s  %s\n",
                //    wtx.vout[0].nValue,
                //    DateTimeStrFormat("%x %H:%M:%S", wtx.GetBlockTime()).c_str(),
                //    wtx.hashBlock.ToString().substr(0,20).c_str(),
                //    wtx.mapValue["message"].c_str());
            }
            else if (strType == "acentry")
            {
                string strAccount;
                ssKey >> strAccount;
                uint64 nNumber;
                ssKey >> nNumber;
                if (nNumber > nAccountingEntryNumber)
                    nAccountingEntryNumber = nNumber;
            }
            else if (strType == "key" || strType == "wkey")
            {
                vector<unsigned char> vchPubKey;
                ssKey >> vchPubKey;
                CWalletKey wkey;
                if (strType == "key")
                    ssValue >> wkey.vchPrivKey;
                else
                    ssValue >> wkey;

                mapKeys[vchPubKey] = wkey.vchPrivKey;
                mapPubKeys[Hash160(vchPubKey)] = vchPubKey;
            }
            else if (strType == "defaultkey")
            {
                ssValue >> vchDefaultKey;
            }
            else if (strType == "pool")
            {
                int64 nIndex;
                ssKey >> nIndex;
                setKeyPool.insert(nIndex);
            }
            else if (strType == "version")
            {
                ssValue >> nFileVersion;
                if (nFileVersion == 10300)
                    nFileVersion = 300;
            }
            else if (strType == "setting")
            {
                string strKey;
                ssKey >> strKey;

                // Menu state
                if (strKey == "fGenerateBitcoins")  ssValue >> fGenerateBitcoins;

                // Options
                if (strKey == "nTransactionFee")    ssValue >> nTransactionFee;
                if (strKey == "addrIncoming")       ssValue >> addrIncoming;
                if (strKey == "fLimitProcessors")   ssValue >> fLimitProcessors;
                if (strKey == "nLimitProcessors")   ssValue >> nLimitProcessors;
                if (strKey == "fMinimizeToTray")    ssValue >> fMinimizeToTray;
                if (strKey == "fMinimizeOnClose")   ssValue >> fMinimizeOnClose;
                if (strKey == "fUseProxy")          ssValue >> fUseProxy;
                if (strKey == "addrProxy")          ssValue >> addrProxy;

            }
        }
        pcursor->close();
    }

    printf("nFileVersion = %d\n", nFileVersion);
    printf("fGenerateBitcoins = %d\n", fGenerateBitcoins);
    printf("nTransactionFee = %"PRI64d"\n", nTransactionFee);
    printf("addrIncoming = %s\n", addrIncoming.ToString().c_str());
    printf("fMinimizeToTray = %d\n", fMinimizeToTray);
    printf("fMinimizeOnClose = %d\n", fMinimizeOnClose);
    printf("fUseProxy = %d\n", fUseProxy);
    printf("addrProxy = %s\n", addrProxy.ToString().c_str());


    // Upgrade
    if (nFileVersion < VERSION)
    {
        // Get rid of old debug.log file in current directory
        if (nFileVersion <= 105 && !pszSetDataDir[0])
            unlink("debug.log");

        WriteVersion(VERSION);
    }

    return true;
}

bool LoadWallet(bool& fFirstRunRet)
{
    fFirstRunRet = false;
    if (!CWalletDB("cr+").LoadWallet())
        return false;
    fFirstRunRet = vchDefaultKey.empty();

    if (mapKeys.count(vchDefaultKey))
    {
        // Set keyUser
        keyUser.SetPubKey(vchDefaultKey);
        keyUser.SetPrivKey(mapKeys[vchDefaultKey]);
    }
    else
    {
        // Create new keyUser and set as default key
        RandAddSeedPerfmon();
        keyUser.MakeNewKey();
        if (!AddKey(keyUser))
            return false;
        if (!SetAddressBookName(PubKeyToAddress(keyUser.GetPubKey()), "Your Address"))
            return false;
        CWalletDB().WriteDefaultKey(keyUser.GetPubKey());
    }

    CreateThread(ThreadFlushWalletDB, NULL);
    return true;
}

void ThreadFlushWalletDB(void* parg)
{
    static bool fOneThread;
    if (fOneThread)
        return;
    fOneThread = true;
    if (mapArgs.count("-noflushwallet"))
        return;

    unsigned int nLastSeen = nWalletDBUpdated;
    unsigned int nLastFlushed = nWalletDBUpdated;
    int64 nLastWalletUpdate = GetTime();
    while (!fShutdown)
    {
        Sleep(500);

        if (nLastSeen != nWalletDBUpdated)
        {
            nLastSeen = nWalletDBUpdated;
            nLastWalletUpdate = GetTime();
        }

        if (nLastFlushed != nWalletDBUpdated && GetTime() - nLastWalletUpdate >= 2)
        {
            TRY_CRITICAL_BLOCK(cs_db)
            {
                // Don't do this if any databases are in use
                int nRefCount = 0;
                map<string, int>::iterator mi = mapFileUseCount.begin();
                while (mi != mapFileUseCount.end())
                {
                    nRefCount += (*mi).second;
                    mi++;
                }

                if (nRefCount == 0 && !fShutdown)
                {
                    string strFile = "wallet.dat";
                    map<string, int>::iterator mi = mapFileUseCount.find(strFile);
                    if (mi != mapFileUseCount.end())
                    {
                        printf("%s ", DateTimeStrFormat("%x %H:%M:%S", GetTime()).c_str());
                        printf("Flushing wallet.dat\n");
                        nLastFlushed = nWalletDBUpdated;
                        int64 nStart = GetTimeMillis();

                        // Flush wallet.dat so it's self contained
                        CloseDb(strFile);
                        dbenv.txn_checkpoint(0, 0, 0);
                        dbenv.lsn_reset(strFile.c_str(), 0);

                        mapFileUseCount.erase(mi++);
                        printf("Flushed wallet.dat %"PRI64d"ms\n", GetTimeMillis() - nStart);
                    }
                }
            }
        }
    }
}

void BackupWallet(const string& strDest)
{
    while (!fShutdown)
    {
        CRITICAL_BLOCK(cs_db)
        {
            const string strFile = "wallet.dat";
            if (!mapFileUseCount.count(strFile) || mapFileUseCount[strFile] == 0)
            {
                // Flush log data to the dat file
                CloseDb(strFile);
                dbenv.txn_checkpoint(0, 0, 0);
                dbenv.lsn_reset(strFile.c_str(), 0);
                mapFileUseCount.erase(strFile);

                // Copy wallet.dat
                filesystem::path pathSrc(GetDataDir() + "/" + strFile);
                filesystem::path pathDest(strDest);
                if (filesystem::is_directory(pathDest))
                    pathDest = pathDest / strFile;
#if BOOST_VERSION >= 104000
                filesystem::copy_file(pathSrc, pathDest, filesystem::copy_option::overwrite_if_exists);
#else
                filesystem::copy_file(pathSrc, pathDest);
#endif
                printf("copied wallet.dat to %s\n", pathDest.string().c_str());

                return;
            }
        }
        Sleep(100);
    }
}


void CWalletDB::ReserveKeyFromKeyPool(int64& nIndex, CKeyPool& keypool)
{
    nIndex = -1;
    keypool.vchPubKey.clear();
    CRITICAL_BLOCK(cs_main)
    CRITICAL_BLOCK(cs_mapWallet)
    CRITICAL_BLOCK(cs_setKeyPool)
    {
        // Top up key pool
        int64 nTargetSize = max(GetArg("-keypool", 100), (int64)0);
        while (setKeyPool.size() < nTargetSize+1)
        {
            int64 nEnd = 1;
            if (!setKeyPool.empty())
                nEnd = *(--setKeyPool.end()) + 1;
            if (!Write(make_pair(string("pool"), nEnd), CKeyPool(GenerateNewKey())))
                throw runtime_error("ReserveKeyFromKeyPool() : writing generated key failed");
            setKeyPool.insert(nEnd);
            printf("keypool added key %"PRI64d", size=%d\n", nEnd, setKeyPool.size());
        }

        // Get the oldest key
        assert(!setKeyPool.empty());
        nIndex = *(setKeyPool.begin());
        setKeyPool.erase(setKeyPool.begin());
        if (!Read(make_pair(string("pool"), nIndex), keypool))
            throw runtime_error("ReserveKeyFromKeyPool() : read failed");
        if (!mapKeys.count(keypool.vchPubKey))
            throw runtime_error("ReserveKeyFromKeyPool() : unknown key in key pool");
        assert(!keypool.vchPubKey.empty());
        printf("keypool reserve %"PRI64d"\n", nIndex);
    }
}

void CWalletDB::KeepKey(int64 nIndex)
{
    // Remove from key pool
    CRITICAL_BLOCK(cs_main)
    CRITICAL_BLOCK(cs_mapWallet)
    {
        Erase(make_pair(string("pool"), nIndex));
    }
    printf("keypool keep %"PRI64d"\n", nIndex);
}

void CWalletDB::ReturnKey(int64 nIndex)
{
    // Return to key pool
    CRITICAL_BLOCK(cs_setKeyPool)
        setKeyPool.insert(nIndex);
    printf("keypool return %"PRI64d"\n", nIndex);
}

vector<unsigned char> GetKeyFromKeyPool()
{
    CWalletDB walletdb;
    int64 nIndex = 0;
    CKeyPool keypool;
    walletdb.ReserveKeyFromKeyPool(nIndex, keypool);
    walletdb.KeepKey(nIndex);
    return keypool.vchPubKey;
}

int64 GetOldestKeyPoolTime()
{
    CWalletDB walletdb;
    int64 nIndex = 0;
    CKeyPool keypool;
    walletdb.ReserveKeyFromKeyPool(nIndex, keypool);
    walletdb.ReturnKey(nIndex);
    return keypool.nTime;
}