1 files changed, 101 insertions, 0 deletions
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 76668f8dc2..0afaba5fd1 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -9,9 +9,14 @@
 #include <clientversion.h>
 #include <fs.h>
 #include <streams.h>
+#include <util/memory.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 +99,100 @@ public:
     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;
+};
+
+/** RAII class that provides access to a DummyDatabase. Never fails. */
+class DummyBatch : public DatabaseBatch
+{
+private:
+    bool ReadKey(CDataStream&& key, CDataStream& value) override { return true; }
+    bool WriteKey(CDataStream&& key, CDataStream&& value, bool overwrite=true) override { return true; }
+    bool EraseKey(CDataStream&& key) override { return true; }
+    bool HasKey(CDataStream&& key) override { return true; }
+
+public:
+    void Flush() override {}
+    void Close() override {}
+
+    bool StartCursor() override { return true; }
+    bool ReadAtCursor(CDataStream& ssKey, CDataStream& ssValue, bool& complete) override { return true; }
+    void CloseCursor() override {}
+    bool TxnBegin() override { return true; }
+    bool TxnCommit() override { return true; }
+    bool TxnAbort() override { return true; }
+};
+
+/** A dummy WalletDatabase that does nothing and never fails. Only used by unit tests.
+ **/
+class DummyDatabase : public WalletDatabase
+{
+public:
+    void Open(const char* mode) override {};
+    void AddRef() override {}
+    void RemoveRef() override {}
+    bool Rewrite(const char* pszSkip=nullptr) override { return true; }
+    bool Backup(const std::string& strDest) const override { return true; }
+    void Close() override {}
+    void Flush() override {}
+    bool PeriodicFlush() override { return true; }
+    void IncrementUpdateCounter() override { ++nUpdateCounter; }
+    void ReloadDbEnv() override {}
+    bool Verify(bilingual_str& errorStr) override { return true; }
+    std::unique_ptr<DatabaseBatch> MakeBatch(const char* mode = "r+", bool flush_on_close = true) override { return MakeUnique<DummyBatch>(); }
+};
+
 #endif // BITCOIN_WALLET_DB_H