walletdb: Move BDB specific things into bdb.{cpp/h}

Leave wallet/db.{cpp/h} for generic WalletDatabase stuff. The BDB
specific stuff goes into bdb.{cpp/h}

1 files changed, 337 insertions, 0 deletions

diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
new file mode 100644
index 0000000000..5ed364344b
--- /dev/null
+++ b/src/wallet/bdb.h
@@ -0,0 +1,337 @@
+// 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, int> mapFileUseCount;
+    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 Verify(const std::string& strFile);
+
+    bool Open(bool retry);
+    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;
+    }
+};
+
+/** Get BerkeleyEnvironment and database filename given a wallet path. */
+std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
+
+/** Return wheter a BDB wallet database is currently loaded. */
+bool IsBDBWalletLoaded(const fs::path& wallet_path);
+
+/** An instance of this class represents one database.
+ * For BerkeleyDB this is just a (env, strFile) tuple.
+ **/
+class BerkeleyDatabase
+{
+    friend class BerkeleyBatch;
+public:
+    /** Create dummy DB handle */
+    BerkeleyDatabase() : nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(nullptr)
+    {
+    }
+
+    /** Create DB handle to real database */
+    BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> env, std::string filename) :
+        nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(std::move(env)), strFile(std::move(filename))
+    {
+        auto inserted = this->env->m_databases.emplace(strFile, std::ref(*this));
+        assert(inserted.second);
+    }
+
+    ~BerkeleyDatabase() {
+        if (env) {
+            size_t erased = env->m_databases.erase(strFile);
+            assert(erased == 1);
+        }
+    }
+
+    /** Return object for accessing database at specified path. */
+    static std::unique_ptr<BerkeleyDatabase> Create(const fs::path& path)
+    {
+        std::string filename;
+        return MakeUnique<BerkeleyDatabase>(GetWalletEnv(path, filename), std::move(filename));
+    }
+
+    /** Return object for accessing dummy database with no read/write capabilities. */
+    static std::unique_ptr<BerkeleyDatabase> CreateDummy()
+    {
+        return MakeUnique<BerkeleyDatabase>();
+    }
+
+    /** Return object for accessing temporary in-memory database. */
+    static std::unique_ptr<BerkeleyDatabase> CreateMock()
+    {
+        return MakeUnique<BerkeleyDatabase>(std::make_shared<BerkeleyEnvironment>(), "");
+    }
+
+    /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
+     */
+    bool Rewrite(const char* pszSkip=nullptr);
+
+    /** Back up the entire database to a file.
+     */
+    bool Backup(const std::string& strDest) const;
+
+    /** Make sure all changes are flushed to disk.
+     */
+    void Flush(bool shutdown);
+
+    void IncrementUpdateCounter();
+
+    void ReloadDbEnv();
+
+    std::atomic<unsigned int> nUpdateCounter;
+    unsigned int nLastSeen;
+    unsigned int nLastFlushed;
+    int64_t nLastWalletUpdate;
+
+    /**
+     * Pointer to shared database environment.
+     *
+     * Normally there is only one BerkeleyDatabase object per
+     * BerkeleyEnvivonment, but in the special, backwards compatible case where
+     * multiple wallet BDB data files are loaded from the same directory, this
+     * will point to a shared instance that gets freed when the last data file
+     * is closed.
+     */
+    std::shared_ptr<BerkeleyEnvironment> env;
+
+    /** Database pointer. This is initialized lazily and reset during flushes, so it can be null. */
+    std::unique_ptr<Db> m_db;
+
+private:
+    std::string strFile;
+
+    /** Return whether this database handle is a dummy for testing.
+     * Only to be used at a low level, application should ideally not care
+     * about this.
+     */
+    bool IsDummy() const { return env == nullptr; }
+};
+
+/** RAII class that provides access to a Berkeley database */
+class BerkeleyBatch
+{
+    /** RAII class that automatically cleanses its data on destruction */
+    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*();
+    };
+
+protected:
+    Db* pdb;
+    std::string strFile;
+    DbTxn* activeTxn;
+    bool fReadOnly;
+    bool fFlushOnClose;
+    BerkeleyEnvironment *env;
+
+public:
+    explicit BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
+    ~BerkeleyBatch() { Close(); }
+
+    BerkeleyBatch(const BerkeleyBatch&) = delete;
+    BerkeleyBatch& operator=(const BerkeleyBatch&) = delete;
+
+    void Flush();
+    void Close();
+
+    /* flush the wallet passively (TRY_LOCK)
+       ideal to be called periodically */
+    static bool PeriodicFlush(BerkeleyDatabase& database);
+    /* verifies the database environment */
+    static bool VerifyEnvironment(const fs::path& file_path, bilingual_str& errorStr);
+    /* verifies the database file */
+    static bool VerifyDatabaseFile(const fs::path& file_path, bilingual_str& errorStr);
+
+    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;
+        SafeDbt datKey(ssKey.data(), ssKey.size());
+
+        // Read
+        SafeDbt datValue;
+        int ret = pdb->get(activeTxn, datKey, datValue, 0);
+        bool success = false;
+        if (datValue.get_data() != nullptr) {
+            // 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'
+            }
+        }
+        return ret == 0 && success;
+    }
+
+    template <typename K, typename T>
+    bool Write(const K& key, const T& value, bool fOverwrite = true)
+    {
+        if (!pdb)
+            return true;
+        if (fReadOnly)
+            assert(!"Write called on database in read-only mode");
+
+        // Key
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(1000);
+        ssKey << key;
+        SafeDbt datKey(ssKey.data(), ssKey.size());
+
+        // Value
+        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+        ssValue.reserve(10000);
+        ssValue << value;
+        SafeDbt datValue(ssValue.data(), ssValue.size());
+
+        // Write
+        int ret = pdb->put(activeTxn, datKey, datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));
+        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;
+        SafeDbt datKey(ssKey.data(), ssKey.size());
+
+        // Erase
+        int ret = pdb->del(activeTxn, datKey, 0);
+        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;
+        SafeDbt datKey(ssKey.data(), ssKey.size());
+
+        // Exists
+        int ret = pdb->exists(activeTxn, datKey, 0);
+        return (ret == 0);
+    }
+
+    Dbc* GetCursor();
+    int ReadAtCursor(Dbc* pcursor, CDataStream& ssKey, CDataStream& ssValue);
+    bool TxnBegin();
+    bool TxnCommit();
+    bool TxnAbort();
+
+    bool static Rewrite(BerkeleyDatabase& database, const char* pszSkip = nullptr);
+};
+
+std::string BerkeleyDatabaseVersion();
+
+#endif // BITCOIN_WALLET_BDB_H