bdb.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_WALLET_BDB_H
#define BITCOIN_WALLET_BDB_H

#include <clientversion.h>
#include <fs.h>
#include <serialize.h>
#include <streams.h>
#include <util/system.h>
#include <wallet/db.h>

#include <atomic>
#include <map>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>

#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsuggest-override"
#endif
#include <db_cxx.h>
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic pop
#endif

struct bilingual_str;

static const unsigned int DEFAULT_WALLET_DBLOGSIZE = 100;
static const bool DEFAULT_WALLET_PRIVDB = true;

struct WalletDatabaseFileId {
    u_int8_t value[DB_FILE_ID_LEN];
    bool operator==(const WalletDatabaseFileId& rhs) const;
};

class BerkeleyDatabase;

class BerkeleyEnvironment
{
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;

public:
    std::unique_ptr<DbEnv> dbenv;
    std::map<std::string, std::reference_wrapper<BerkeleyDatabase>> m_databases;
    std::unordered_map<std::string, WalletDatabaseFileId> m_fileids;
    std::condition_variable_any m_db_in_use;

    BerkeleyEnvironment(const fs::path& env_directory);
    BerkeleyEnvironment();
    ~BerkeleyEnvironment();
    void Reset();

    bool IsMock() const { return fMockDb; }
    bool IsInitialized() const { return fDbEnvInit; }
    bool IsDatabaseLoaded(const std::string& db_filename) const { return m_databases.find(db_filename) != m_databases.end(); }
    fs::path Directory() const { return strPath; }

    bool Open(bilingual_str& error);
    void Close();
    void Flush(bool fShutdown);
    void CheckpointLSN(const std::string& strFile);

    void CloseDb(const std::string& strFile);
    void ReloadDbEnv();

    DbTxn* TxnBegin(int flags = DB_TXN_WRITE_NOSYNC)
    {
        DbTxn* ptxn = nullptr;
        int ret = dbenv->txn_begin(nullptr, &ptxn, flags);
        if (!ptxn || ret != 0)
            return nullptr;
        return ptxn;
    }
};

std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);

bool IsBDBWalletLoaded(const fs::path& wallet_path);

class BerkeleyBatch;

class BerkeleyDatabase : public WalletDatabase
{
public:
    BerkeleyDatabase() = delete;

    BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> env, std::string filename) :
        WalletDatabase(), env(std::move(env)), strFile(std::move(filename))
    {
        auto inserted = this->env->m_databases.emplace(strFile, std::ref(*this));
        assert(inserted.second);
    }

    ~BerkeleyDatabase() override;

    void Open(const char* mode) override;

    bool Rewrite(const char* pszSkip=nullptr) override;

    void AddRef() override;
    void RemoveRef() override;

    bool Backup(const std::string& strDest) const override;

    void Flush() override;
    void Close() override;
    /* flush the wallet passively (TRY_LOCK)
       ideal to be called periodically */
    bool PeriodicFlush() override;

    void IncrementUpdateCounter() override;

    void ReloadDbEnv() override;

    bool Verify(bilingual_str& error) override;

    std::shared_ptr<BerkeleyEnvironment> env;

    std::unique_ptr<Db> m_db;

    std::string strFile;

    std::unique_ptr<DatabaseBatch> MakeBatch(const char* mode = "r+", bool flush_on_close = true) override;
};

class BerkeleyBatch : public DatabaseBatch
{
    class SafeDbt final
    {
        Dbt m_dbt;

    public:
        // construct Dbt with internally-managed data
        SafeDbt();
        // construct Dbt with provided data
        SafeDbt(void* data, size_t size);
        ~SafeDbt();

        // delegate to Dbt
        const void* get_data() const;
        u_int32_t get_size() const;

        // conversion operator to access the underlying Dbt
        operator Dbt*();
    };

private:
    bool ReadKey(CDataStream&& key, CDataStream& value) override;
    bool WriteKey(CDataStream&& key, CDataStream&& value, bool overwrite = true) override;
    bool EraseKey(CDataStream&& key) override;
    bool HasKey(CDataStream&& key) override;

protected:
    Db* pdb;
    std::string strFile;
    DbTxn* activeTxn;
    Dbc* m_cursor;
    bool fReadOnly;
    bool fFlushOnClose;
    BerkeleyEnvironment *env;
    BerkeleyDatabase& m_database;

public:
    explicit BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
    ~BerkeleyBatch() override;

    BerkeleyBatch(const BerkeleyBatch&) = delete;
    BerkeleyBatch& operator=(const BerkeleyBatch&) = delete;

    void Flush() override;
    void Close() override;

    bool StartCursor() override;
    bool ReadAtCursor(CDataStream& ssKey, CDataStream& ssValue, bool& complete) override;
    void CloseCursor() override;
    bool TxnBegin() override;
    bool TxnCommit() override;
    bool TxnAbort() override;
};

std::string BerkeleyDatabaseVersion();

#endif // BITCOIN_WALLET_BDB_H