Merge #20130: Wallet: remove db mode string

135afa749c6e835ea33b8678cdb35da9640eede8 wallet: remove db mode string (Ivan Metlushko)

Pull request description:

  This is a [follow-up](https://github.com/bitcoin/bitcoin/pull/19077#discussion_r500261927) for #19077

  This PR simplifies DB interface by removing mode string from `WalletDatabase` and `WalletBatch`.

  The mode string was used to determine two flags for the instantiation of db connection:
  1) read-only flag. Never used on connection level. And on batch level Is only used within `BerkeleyDatabase::Rewrite` where it's replaced with bool flag.
  2) create flag. Is not required as we always check `require_existing` & `require_create` flags in `MakeDatabase()` before creating actual database instance. So we can safely default to always creating database if it doesn't exist yet.

ACKs for top commit:
  achow101:
    ACK 135afa749c6e835ea33b8678cdb35da9640eede8
  laanwj:
    Code review ACK 135afa749c6e835ea33b8678cdb35da9640eede8

Tree-SHA512: f49c07c7387c02e517a58199620a678a918f8dfc20d1347d29fd6adea0bc89698c26cb8eef42b0977961c11c207c4bbe109bc31059f47c126cc600b01fd987eb

1 files changed, 4 insertions, 5 deletions

diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
index fd5a49acc3..070590872b 100644
--- a/src/wallet/bdb.h
+++ b/src/wallet/bdb.h
@@ -109,9 +109,8 @@ public:
 
     ~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) override;
+    /** Open the database if it is not already opened. */
+    void Open() override;
 
     /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
      */
@@ -164,7 +163,7 @@ public:
     std::string strFile;
 
     /** Make a BerkeleyBatch connected to this database */
-    std::unique_ptr<DatabaseBatch> MakeBatch(const char* mode = "r+", bool flush_on_close = true) override;
+    std::unique_ptr<DatabaseBatch> MakeBatch(bool flush_on_close = true) override;
 };
 
 /** RAII class that provides access to a Berkeley database */
@@ -207,7 +206,7 @@ protected:
     BerkeleyDatabase& m_database;
 
 public:
-    explicit BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
+    explicit BerkeleyBatch(BerkeleyDatabase& database, const bool fReadOnly, bool fFlushOnCloseIn=true);
     ~BerkeleyBatch() override;
 
     BerkeleyBatch(const BerkeleyBatch&) = delete;