walletdb: Introduce WalletDatabase abstract class

Make WalletDatabase actually an abstract class and not just a typedef
for BerkeleyDatabase. Have BerkeleyDatabase inherit this class.

Author: achow101

src/qt/rpcconsole.cpp

@@ -24,7 +24,6 @@
 #include <univalue.h>
 
 #ifdef ENABLE_WALLET
-#include <wallet/bdb.h>
 #include <wallet/db.h>
 #include <wallet/wallet.h>
 #endif

src/wallet/bdb.cpp

@@ -862,7 +862,7 @@ void BerkeleyDatabase::RemoveRef()
     env->m_db_in_use.notify_all();
 }
 
-std::unique_ptr<BerkeleyBatch> BerkeleyDatabase::MakeBatch(const char* mode, bool flush_on_close)
+std::unique_ptr<DatabaseBatch> BerkeleyDatabase::MakeBatch(const char* mode, bool flush_on_close)
 {
     return MakeUnique<BerkeleyBatch>(*this, mode, flush_on_close);
 }

src/wallet/bdb.h

@@ -98,64 +98,59 @@ class BerkeleyBatch;
 /** An instance of this class represents one database.
  * For BerkeleyDB this is just a (env, strFile) tuple.
  **/
-class BerkeleyDatabase
+class BerkeleyDatabase : public WalletDatabase
 {
     friend class BerkeleyBatch;
 public:
     /** Create dummy DB handle */
-    BerkeleyDatabase() : nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(nullptr)
+    BerkeleyDatabase() : WalletDatabase(), 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))
+        WalletDatabase(), env(std::move(env)), strFile(std::move(filename))
     {
         auto inserted = this->env->m_databases.emplace(strFile, std::ref(*this));
         assert(inserted.second);
     }
 
-    ~BerkeleyDatabase();
+    ~BerkeleyDatabase() override;
 
     /** Open the database if it is not already opened.
      *  Dummy function, doesn't do anything right now, but is needed for class abstraction */
-    void Open(const char* mode);
+    void Open(const char* mode) override;
 
     /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
      */
-    bool Rewrite(const char* pszSkip=nullptr);
+    bool Rewrite(const char* pszSkip=nullptr) override;
 
     /** Indicate the a new database user has began using the database. */
-    void AddRef();
+    void AddRef() override;
     /** Indicate that database user has stopped using the database and that it could be flushed or closed. */
-    void RemoveRef();
+    void RemoveRef() override;
 
     /** Back up the entire database to a file.
      */
-    bool Backup(const std::string& strDest) const;
+    bool Backup(const std::string& strDest) const override;
 
     /** Make sure all changes are flushed to database file.
      */
-    void Flush();
+    void Flush() override;
     /** Flush to the database file and close the database.
      *  Also close the environment if no other databases are open in it.
      */
-    void Close();
+    void Close() override;
     /* flush the wallet passively (TRY_LOCK)
        ideal to be called periodically */
-    bool PeriodicFlush();
+    bool PeriodicFlush() override;
 
-    void IncrementUpdateCounter();
-
-    void ReloadDbEnv();
+    void IncrementUpdateCounter() override;
 
-    std::atomic<unsigned int> nUpdateCounter;
-    unsigned int nLastSeen;
-    unsigned int nLastFlushed;
-    int64_t nLastWalletUpdate;
+    void ReloadDbEnv() override;
 
     /** Verifies the environment and database file */
-    bool Verify(bilingual_str& error);
+    bool Verify(bilingual_str& error) override;
 
     /**
      * Pointer to shared database environment.
@@ -172,7 +167,7 @@ class BerkeleyDatabase
     std::unique_ptr<Db> m_db;
 
     /** Make a BerkeleyBatch connected to this database */
-    std::unique_ptr<BerkeleyBatch> MakeBatch(const char* mode, bool flush_on_close);
+    std::unique_ptr<DatabaseBatch> MakeBatch(const char* mode = "r+", bool flush_on_close = true) override;
 
 private:
     std::string strFile;

src/wallet/db.h

@@ -10,8 +10,12 @@
 #include <fs.h>
 #include <streams.h>
 
+#include <atomic>
+#include <memory>
 #include <string>
 
+struct bilingual_str;
+
 /** Given a wallet directory path or legacy file path, return path to main data file in the wallet database. */
 fs::path WalletDataFilePath(const fs::path& wallet_path);
 void SplitWalletPath(const fs::path& wallet_path, fs::path& env_directory, std::string& database_filename);
@@ -94,4 +98,60 @@ class DatabaseBatch
     virtual bool TxnAbort() = 0;
 };
 
+/** An instance of this class represents one database.
+ **/
+class WalletDatabase
+{
+public:
+    /** Create dummy DB handle */
+    WalletDatabase() : nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0) {}
+    virtual ~WalletDatabase() {};
+
+    /** Open the database if it is not already opened. */
+    virtual void Open(const char* mode) = 0;
+
+    //! Counts the number of active database users to be sure that the database is not closed while someone is using it
+    std::atomic<int> m_refcount{0};
+    /** Indicate the a new database user has began using the database. Increments m_refcount */
+    virtual void AddRef() = 0;
+    /** Indicate that database user has stopped using the database and that it could be flushed or closed. Decrement m_refcount */
+    virtual void RemoveRef() = 0;
+
+    /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
+     */
+    virtual bool Rewrite(const char* pszSkip=nullptr) = 0;
+
+    /** Back up the entire database to a file.
+     */
+    virtual bool Backup(const std::string& strDest) const = 0;
+
+    /** Make sure all changes are flushed to database file.
+     */
+    virtual void Flush() = 0;
+    /** Flush to the database file and close the database.
+     *  Also close the environment if no other databases are open in it.
+     */
+    virtual void Close() = 0;
+    /* flush the wallet passively (TRY_LOCK)
+       ideal to be called periodically */
+    virtual bool PeriodicFlush() = 0;
+
+    virtual void IncrementUpdateCounter() = 0;
+
+    virtual void ReloadDbEnv() = 0;
+
+    std::atomic<unsigned int> nUpdateCounter;
+    unsigned int nLastSeen;
+    unsigned int nLastFlushed;
+    int64_t nLastWalletUpdate;
+
+    /** Verifies the environment and database file */
+    virtual bool Verify(bilingual_str& error) = 0;
+
+    std::string m_file_path;
+
+    /** Make a DatabaseBatch connected to this database */
+    virtual std::unique_ptr<DatabaseBatch> MakeBatch(const char* mode = "r+", bool flush_on_close = true) = 0;
+};
+
 #endif // BITCOIN_WALLET_DB_H

src/wallet/walletdb.cpp

@@ -1012,20 +1012,20 @@ bool IsWalletLoaded(const fs::path& wallet_path)
 }
 
 /** Return object for accessing database at specified path. */
-std::unique_ptr<BerkeleyDatabase> CreateWalletDatabase(const fs::path& path)
+std::unique_ptr<WalletDatabase> CreateWalletDatabase(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. */
-std::unique_ptr<BerkeleyDatabase> CreateDummyWalletDatabase()
+std::unique_ptr<WalletDatabase> CreateDummyWalletDatabase()
 {
     return MakeUnique<BerkeleyDatabase>();
 }
 
 /** Return object for accessing temporary in-memory database. */
-std::unique_ptr<BerkeleyDatabase> CreateMockWalletDatabase()
+std::unique_ptr<WalletDatabase> CreateMockWalletDatabase()
 {
     return MakeUnique<BerkeleyDatabase>(std::make_shared<BerkeleyEnvironment>(), "");
 }

src/wallet/walletdb.h

@@ -40,9 +40,6 @@ class CWalletTx;
 class uint160;
 class uint256;
 
-/** Backend-agnostic database type. */
-using WalletDatabase = BerkeleyDatabase;
-
 /** Error statuses for the wallet database */
 enum class DBErrors
 {
@@ -280,7 +277,7 @@ class WalletBatch
     //! Abort current transaction
     bool TxnAbort();
 private:
-    std::unique_ptr<BerkeleyBatch> m_batch;
+    std::unique_ptr<DatabaseBatch> m_batch;
     WalletDatabase& m_database;
 };
 
@@ -294,12 +291,12 @@ bool ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue, st
 bool IsWalletLoaded(const fs::path& wallet_path);
 
 /** Return object for accessing database at specified path. */
-std::unique_ptr<BerkeleyDatabase> CreateWalletDatabase(const fs::path& path);
+std::unique_ptr<WalletDatabase> CreateWalletDatabase(const fs::path& path);
 
 /** Return object for accessing dummy database with no read/write capabilities. */
-std::unique_ptr<BerkeleyDatabase> CreateDummyWalletDatabase();
+std::unique_ptr<WalletDatabase> CreateDummyWalletDatabase();
 
 /** Return object for accessing temporary in-memory database. */
-std::unique_ptr<BerkeleyDatabase> CreateMockWalletDatabase();
+std::unique_ptr<WalletDatabase> CreateMockWalletDatabase();
 
 #endif // BITCOIN_WALLET_WALLETDB_H