db.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_DB_H
#define BITCOIN_DB_H
 
#include "clientversion.h"
#include "fs.h"
#include "serialize.h"
#include "streams.h"
#include "sync.h"
#include "version.h"
 
#include <map>
#include <string>
#include <vector>
 
 
#include <db_cxx.h>
 
class CDiskBlockIndex;
class COutPoint;
 
struct CBlockLocator;
 
class CDBEnv
{
private:
    bool fDbEnvInit;
    bool fMockDb;
    // Don't change into fs::path, as that can result in
    // shutdown problems/crashes caused by a static initialized internal pointer.
    std::string strPath;
 
    void EnvShutdown();
 
public:
    mutable RecursiveMutex cs_db;
    DbEnv *dbenv;
    std::map<std::string, int> mapFileUseCount;
    std::map<std::string, Db*> mapDb;
 
    CDBEnv();
    ~CDBEnv();
    void Reset();
 
    void MakeMock();
    bool IsMock() { return fMockDb; }
 
    enum VerifyResult { VERIFY_OK,
        RECOVER_OK,
        RECOVER_FAIL };
    VerifyResult Verify(std::string strFile, bool (*recoverFunc)(CDBEnv& dbenv, std::string strFile));
    bool Compact(const std::string& strFile);
    typedef std::pair<std::vector<unsigned char>, std::vector<unsigned char> > KeyValPair;
    bool Salvage(std::string strFile, bool fAggressive, std::vector<KeyValPair>& vResult);
 
    bool Open(const fs::path& path);
    void Close();
    void Flush(bool fShutdown);
    void CheckpointLSN(const std::string& strFile);
 
    void CloseDb(const std::string& strFile);
    bool RemoveDb(const std::string& strFile);
 
    DbTxn* TxnBegin(int flags = DB_TXN_WRITE_NOSYNC)
    {
        DbTxn* ptxn = NULL;
        int ret = dbenv->txn_begin(NULL, &ptxn, flags);
        if (!ptxn || ret != 0)
            return NULL;
        return ptxn;
    }
};
 
extern CDBEnv bitdb;
 
 
class CDB
{
protected:
    Db* pdb;
    std::string strFile;
    DbTxn* activeTxn;
    bool fReadOnly;
    bool fFlushOnClose;
 
    explicit CDB(const std::string& strFilename, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
    ~CDB() { Close(); }
 
public:
    void Flush();
    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(activeTxn, &datKey, &datValue, 0);
        memory_cleanse(datKey.get_data(), datKey.get_size());
        bool success = false;
        if (datValue.get_data() != NULL) {
            // Unserialize value
            try {
                CDataStream ssValue((char*)datValue.get_data(), (char*)datValue.get_data() + datValue.get_size(), SER_DISK, CLIENT_VERSION);
                ssValue >> value;
                success = true;
            } catch (const std::exception&) {
                // In this case success remains 'false'
            }
 
            // Clear and free memory
            memory_cleanse(datValue.get_data(), datValue.get_size());
            free(datValue.get_data());
        }
        return ret == 0 && success;
    }
 
    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(activeTxn, &datKey, &datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));
 
        // Clear memory in case it was a private key
        memory_cleanse(datKey.get_data(), datKey.get_size());
        memory_cleanse(datValue.get_data(), 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(activeTxn, &datKey, 0);
 
        // Clear memory
         memory_cleanse(datKey.get_data(), 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(activeTxn, &datKey, 0);
 
        // Clear memory
        memory_cleanse(datKey.get_data(), 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;
        datKey.set_data(NULL);
        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;
        datValue.set_data(NULL);
        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) {
            if (datKey.get_data() != NULL)
                free(datKey.get_data());
            if (datValue.get_data() != NULL)
                free(datValue.get_data());
 
            return ret;
        }
        else if (datKey.get_data() == NULL || datValue.get_data() == NULL) {
            if (datKey.get_data() != NULL)
                free(datKey.get_data());
            if (datValue.get_data() != NULL)
                free(datValue.get_data());
 
            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
        memory_cleanse(datKey.get_data(), datKey.get_size());
        memory_cleanse(datValue.get_data(), datValue.get_size());
        free(datKey.get_data());
        free(datValue.get_data());
        return 0;
    }
 
public:
    bool TxnBegin()
    {
        if (!pdb || activeTxn)
            return false;
        DbTxn* ptxn = bitdb.TxnBegin();
        if (!ptxn)
            return false;
        activeTxn = ptxn;
        return true;
    }
 
    bool TxnCommit()
    {
        if (!pdb || !activeTxn)
            return false;
        int ret = activeTxn->commit(0);
        activeTxn = NULL;
        return (ret == 0);
    }
 
    bool TxnAbort()
    {
        if (!pdb || !activeTxn)
            return false;
        int ret = activeTxn->abort();
        activeTxn = NULL;
        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);
};
 
#endif // BITCOIN_DB_H