wallet: batch and simplify ZapSelectTx process

The goal of the function is to erase the wallet transactions that
match the inputted hashes. There is no need to traverse the database,
reading record by record, to then perform single entry removals for
each of them.

To ensure consistency and improve performance, this change-set removes
all tx records within a single atomic db batch operation, as well as
it cleans up code, improves error handling and simplifies the
transactions removal process entirely.

This optimizes the removal of watch-only transactions during the wallet
migration process and the 'removeprunedfunds' RPC command.

1 files changed, 0 insertions, 84 deletions

diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index 96999de97b..6f99da7aea 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -1230,90 +1230,6 @@ DBErrors WalletBatch::LoadWallet(CWallet* pwallet)
     return result;
 }
 
-DBErrors WalletBatch::FindWalletTxHashes(std::vector<uint256>& tx_hashes)
-{
-    DBErrors result = DBErrors::LOAD_OK;
-
-    try {
-        int nMinVersion = 0;
-        if (m_batch->Read(DBKeys::MINVERSION, nMinVersion)) {
-            if (nMinVersion > FEATURE_LATEST)
-                return DBErrors::TOO_NEW;
-        }
-
-        // Get cursor
-        std::unique_ptr<DatabaseCursor> cursor = m_batch->GetNewCursor();
-        if (!cursor)
-        {
-            LogPrintf("Error getting wallet database cursor\n");
-            return DBErrors::CORRUPT;
-        }
-
-        while (true)
-        {
-            // Read next record
-            DataStream ssKey{};
-            DataStream ssValue{};
-            DatabaseCursor::Status status = cursor->Next(ssKey, ssValue);
-            if (status == DatabaseCursor::Status::DONE) {
-                break;
-            } else if (status == DatabaseCursor::Status::FAIL) {
-                LogPrintf("Error reading next record from wallet database\n");
-                return DBErrors::CORRUPT;
-            }
-
-            std::string strType;
-            ssKey >> strType;
-            if (strType == DBKeys::TX) {
-                uint256 hash;
-                ssKey >> hash;
-                tx_hashes.push_back(hash);
-            }
-        }
-    } catch (...) {
-        result = DBErrors::CORRUPT;
-    }
-
-    return result;
-}
-
-DBErrors WalletBatch::ZapSelectTx(std::vector<uint256>& vTxHashIn, std::vector<uint256>& vTxHashOut)
-{
-    // build list of wallet TX hashes
-    std::vector<uint256> vTxHash;
-    DBErrors err = FindWalletTxHashes(vTxHash);
-    if (err != DBErrors::LOAD_OK) {
-        return err;
-    }
-
-    std::sort(vTxHash.begin(), vTxHash.end());
-    std::sort(vTxHashIn.begin(), vTxHashIn.end());
-
-    // erase each matching wallet TX
-    bool delerror = false;
-    std::vector<uint256>::iterator it = vTxHashIn.begin();
-    for (const uint256& hash : vTxHash) {
-        while (it < vTxHashIn.end() && (*it) < hash) {
-            it++;
-        }
-        if (it == vTxHashIn.end()) {
-            break;
-        }
-        else if ((*it) == hash) {
-            if(!EraseTx(hash)) {
-                LogPrint(BCLog::WALLETDB, "Transaction was found for deletion but returned database error: %s\n", hash.GetHex());
-                delerror = true;
-            }
-            vTxHashOut.push_back(hash);
-        }
-    }
-
-    if (delerror) {
-        return DBErrors::CORRUPT;
-    }
-    return DBErrors::LOAD_OK;
-}
-
 void MaybeCompactWalletDB(WalletContext& context)
 {
     static std::atomic<bool> fOneThread(false);