Implement MigrateToSQLite

Author: achow101

src/wallet/wallet.cpp

@@ -3654,4 +3654,76 @@ ScriptPubKeyMan* CWallet::AddWalletDescriptor(WalletDescriptor& desc, const Flat
 
     return spk_man;
 }
+
+bool CWallet::MigrateToSQLite(bilingual_str& error)
+{
+    AssertLockHeld(cs_wallet);
+
+    WalletLogPrintf("Migrating wallet storage database from BerkeleyDB to SQLite.\n");
+
+    if (m_database->Format() == "sqlite") {
+        error = _("Error: This wallet already uses SQLite");
+        return false;
+    }
+
+    // Get all of the records for DB type migration
+    std::unique_ptr<DatabaseBatch> batch = m_database->MakeBatch();
+    std::vector<std::pair<SerializeData, SerializeData>> records;
+    if (!batch->StartCursor()) {
+        error = _("Error: Unable to begin reading all records in the database");
+        return false;
+    }
+    bool complete = false;
+    while (true) {
+        CDataStream ss_key(SER_DISK, CLIENT_VERSION);
+        CDataStream ss_value(SER_DISK, CLIENT_VERSION);
+        bool ret = batch->ReadAtCursor(ss_key, ss_value, complete);
+        if (!ret) {
+            break;
+        }
+        SerializeData key(ss_key.begin(), ss_key.end());
+        SerializeData value(ss_value.begin(), ss_value.end());
+        records.emplace_back(key, value);
+    }
+    batch->CloseCursor();
+    batch.reset();
+    if (!complete) {
+        error = _("Error: Unable to read all records in the database");
+        return false;
+    }
+
+    // Close this database and delete the file
+    fs::path db_path = fs::PathFromString(m_database->Filename());
+    fs::path db_dir = db_path.parent_path();
+    m_database->Close();
+    fs::remove(db_path);
+
+    // Make new DB
+    DatabaseOptions opts;
+    opts.require_create = true;
+    opts.require_format = DatabaseFormat::SQLITE;
+    DatabaseStatus db_status;
+    std::unique_ptr<WalletDatabase> new_db = MakeDatabase(db_dir, opts, db_status, error);
+    assert(new_db); // This is to prevent doing anything further with this wallet. The original file was deleted, but a backup exists.
+    m_database.reset();
+    m_database = std::move(new_db);
+
+    // Write existing records into the new DB
+    batch = m_database->MakeBatch();
+    bool began = batch->TxnBegin();
+    assert(began); // This is a critical error, the new db could not be written to. The original db exists as a backup, but we should not continue execution.
+    for (const auto& [key, value] : records) {
+        CDataStream ss_key(key, SER_DISK, CLIENT_VERSION);
+        CDataStream ss_value(value, SER_DISK, CLIENT_VERSION);
+        if (!batch->Write(ss_key, ss_value)) {
+            batch->TxnAbort();
+            m_database->Close();
+            fs::remove(m_database->Filename());
+            assert(false); // This is a critical error, the new db could not be written to. The original db exists as a backup, but we should not continue execution.
+        }
+    }
+    bool committed = batch->TxnCommit();
+    assert(committed); // This is a critical error, the new db could not be written to. The original db exists as a backup, but we should not continue execution.
+    return true;
+}
 } // namespace wallet

src/wallet/wallet.h

@@ -316,7 +316,7 @@ class CWallet final : public WalletStorage, public interfaces::Chain::Notificati
     std::string m_name;
 
     /** Internal database handle. */
-    std::unique_ptr<WalletDatabase> const m_database;
+    std::unique_ptr<WalletDatabase> m_database;
 
     /**
      * The following is used to keep track of how far behind the wallet is
@@ -920,6 +920,13 @@ class CWallet final : public WalletStorage, public interfaces::Chain::Notificati
 
     //! Add a descriptor to the wallet, return a ScriptPubKeyMan & associated output type
     ScriptPubKeyMan* AddWalletDescriptor(WalletDescriptor& desc, const FlatSigningProvider& signing_provider, const std::string& label, bool internal) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+
+    /** Move all records from the BDB database to a new SQLite database for storage.
+     * The original BDB file will be deleted and replaced with a new SQLite file.
+     * A backup is not created.
+     * May crash if something unexpected happens in the filesystem.
+     */
+    bool MigrateToSQLite(bilingual_str& error) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 };
 
 /**