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 <common/system.h>
#include <serialize.h>
#include <streams.h>
#include <util/fs.h>
#include <wallet/db.h>
 
#include <db_cxx.h>
 
#include <atomic>
#include <condition_variable>
#include <map>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>
 
struct bilingual_str;
 
static const unsigned int DEFAULT_WALLET_DBLOGSIZE = 100;
static const bool DEFAULT_WALLET_PRIVDB = true;
 
struct WalletDatabaseFileId {
    uint8_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;
 
    explicit BerkeleyEnvironment(const fs::path &env_directory);
    BerkeleyEnvironment();
    ~BerkeleyEnvironment();
    void Reset();
 
    void MakeMock();
    bool IsMock() const { return fMockDb; }
    bool IsInitialized() const { return fDbEnvInit; }
    fs::path Directory() const { return fs::PathFromString(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 IsBerkeleyBtree(const fs::path &path);
 
class BerkeleyBatch;
 
class BerkeleyDatabase : public WalletDatabase {
public:
    BerkeleyDatabase() = delete;
 
    BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> envIn,
                     std::string filename)
        : WalletDatabase(), env(std::move(envIn)),
          strFile(std::move(filename)) {
        auto inserted =
            this->env->m_databases.emplace(strFile, std::ref(*this));
        assert(inserted.second);
    }
 
    ~BerkeleyDatabase() override;
 
    void Open() 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;
 
    bool PeriodicFlush() override;
 
    void IncrementUpdateCounter() override;
 
    void ReloadDbEnv() override;
 
    bool Verify(bilingual_str &error);
 
    std::string Filename() override {
        return fs::PathToString(env->Directory() / strFile);
    }
 
    std::shared_ptr<BerkeleyEnvironment> env;
 
    std::unique_ptr<Db> m_db;
 
    std::string strFile;
 
    std::unique_ptr<DatabaseBatch>
    MakeBatch(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;
        uint32_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 bool fReadOnly,
                           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();
 
bool ExistsBerkeleyDatabase(const fs::path &path);
 
std::unique_ptr<BerkeleyDatabase>
MakeBerkeleyDatabase(const fs::path &path, const DatabaseOptions &options,
                     DatabaseStatus &status, bilingual_str &error);
 
#endif // BITCOIN_WALLET_BDB_H