wallet: Save wallet scan progress

Currently, the wallet scan progress is not saved.
If it is interrupted,  it will be necessary to start from
scratch on the next load.
With this change, progress is saved every 60 seconds.

Co-authored-by: furszy <matiasfurszyfer@protonmail.com>
Co-authored-by: Jon Atack <jon@atack.com>
Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

5 files changed, 24 insertions, 12 deletions

diff --git a/src/wallet/rpc/transactions.cpp b/src/wallet/rpc/transactions.cpp
index fae9bf3ea5..f4e46a5982 100644
--- a/src/wallet/rpc/transactions.cpp
+++ b/src/wallet/rpc/transactions.cpp
@@ -908,7 +908,7 @@ RPCHelpMan rescanblockchain()
     }
 
     CWallet::ScanResult result =
-        pwallet->ScanForWalletTransactions(start_block, start_height, stop_height, reserver, true /* fUpdate */);
+        pwallet->ScanForWalletTransactions(start_block, start_height, stop_height, reserver, /*fUpdate=*/true, /*save_progress=*/false);
     switch (result.status) {
     case CWallet::ScanResult::SUCCESS:
         break;
diff --git a/src/wallet/test/util.cpp b/src/wallet/test/util.cpp
index aa3121511d..ab72721f9d 100644
--- a/src/wallet/test/util.cpp
+++ b/src/wallet/test/util.cpp
@@ -38,7 +38,7 @@ std::unique_ptr<CWallet> CreateSyncedWallet(interfaces::Chain& chain, CChain& cc
     }
     WalletRescanReserver reserver(*wallet);
     reserver.reserve();
-    CWallet::ScanResult result = wallet->ScanForWalletTransactions(cchain.Genesis()->GetBlockHash(), 0 /* start_height */, {} /* max_height */, reserver, false /* update */);
+    CWallet::ScanResult result = wallet->ScanForWalletTransactions(cchain.Genesis()->GetBlockHash(), /*start_height=*/0, /*max_height=*/{}, reserver, /*fUpdate=*/false, /*save_progress=*/false);
     BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::SUCCESS);
     BOOST_CHECK_EQUAL(result.last_scanned_block, cchain.Tip()->GetBlockHash());
     BOOST_CHECK_EQUAL(*result.last_scanned_height, cchain.Height());
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 70863f5464..4fbce7fc47 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -112,7 +112,7 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(wallet);
         reserver.reserve();
-        CWallet::ScanResult result = wallet.ScanForWalletTransactions({} /* start_block */, 0 /* start_height */, {} /* max_height */, reserver, false /* update */);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(/*start_block=*/{}, /*start_height=*/0, /*max_height=*/{}, reserver, /*fUpdate=*/false, /*save_progress=*/false);
         BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::FAILURE);
         BOOST_CHECK(result.last_failed_block.IsNull());
         BOOST_CHECK(result.last_scanned_block.IsNull());
@@ -132,7 +132,7 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(wallet);
         reserver.reserve();
-        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), oldTip->nHeight, {} /* max_height */, reserver, false /* update */);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(/*start_block=*/oldTip->GetBlockHash(), /*start_height=*/oldTip->nHeight, /*max_height=*/{}, reserver, /*fUpdate=*/false, /*save_progress=*/false);
         BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::SUCCESS);
         BOOST_CHECK(result.last_failed_block.IsNull());
         BOOST_CHECK_EQUAL(result.last_scanned_block, newTip->GetBlockHash());
@@ -161,7 +161,7 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(wallet);
         reserver.reserve();
-        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), oldTip->nHeight, {} /* max_height */, reserver, false /* update */);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(/*start_block=*/oldTip->GetBlockHash(), /*start_height=*/oldTip->nHeight, /*max_height=*/{}, reserver, /*fUpdate=*/false, /*save_progress=*/false);
         BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::FAILURE);
         BOOST_CHECK_EQUAL(result.last_failed_block, oldTip->GetBlockHash());
         BOOST_CHECK_EQUAL(result.last_scanned_block, newTip->GetBlockHash());
@@ -188,7 +188,7 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(wallet);
         reserver.reserve();
-        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), oldTip->nHeight, {} /* max_height */, reserver, false /* update */);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(/*start_block=*/oldTip->GetBlockHash(), /*start_height=*/oldTip->nHeight, /*max_height=*/{}, reserver, /*fUpdate=*/false, /*save_progress=*/false);
         BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::FAILURE);
         BOOST_CHECK_EQUAL(result.last_failed_block, newTip->GetBlockHash());
         BOOST_CHECK(result.last_scanned_block.IsNull());
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 6c333c709b..56fa3eb1b0 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1674,7 +1674,7 @@ int64_t CWallet::RescanFromTime(int64_t startTime, const WalletRescanReserver& r
 
     if (start) {
         // TODO: this should take into account failure by ScanResult::USER_ABORT
-        ScanResult result = ScanForWalletTransactions(start_block, start_height, {} /* max_height */, reserver, update);
+        ScanResult result = ScanForWalletTransactions(start_block, start_height, /*max_height=*/{}, reserver, /*fUpdate=*/update, /*save_progress=*/false);
         if (result.status == ScanResult::FAILURE) {
             int64_t time_max;
             CHECK_NONFATAL(chain().findBlock(result.last_failed_block, FoundBlock().maxTime(time_max)));
@@ -1705,10 +1705,10 @@ int64_t CWallet::RescanFromTime(int64_t startTime, const WalletRescanReserver& r
  * the main chain after to the addition of any new keys you want to detect
  * transactions for.
  */
-CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_block, int start_height, std::optional<int> max_height, const WalletRescanReserver& reserver, bool fUpdate)
+CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_block, int start_height, std::optional<int> max_height, const WalletRescanReserver& reserver, bool fUpdate, const bool save_progress)
 {
     using Clock = std::chrono::steady_clock;
-    constexpr auto LOG_INTERVAL{60s};
+    constexpr auto INTERVAL_TIME{60s};
     auto current_time{Clock::now()};
     auto start_time{Clock::now()};
 
@@ -1737,7 +1737,9 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
         if (block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
             ShowProgress(strprintf("%s " + _("Rescanning…").translated, GetDisplayName()), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
         }
-        if (Clock::now() >= current_time + LOG_INTERVAL) {
+
+        bool next_interval = Clock::now() >= current_time + INTERVAL_TIME;
+        if (next_interval) {
             current_time = Clock::now();
             WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n", block_height, progress_current);
         }
@@ -1768,6 +1770,16 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
             // scan succeeded, record block as most recent successfully scanned
             result.last_scanned_block = block_hash;
             result.last_scanned_height = block_height;
+
+            if (save_progress && next_interval) {
+                CBlockLocator loc = m_chain->getActiveChainLocator(block_hash);
+
+                if (!loc.IsNull()) {
+                    WalletLogPrintf("Saving scan progress %d.\n", block_height);
+                    WalletBatch batch(GetDatabase());
+                    batch.WriteBestBlock(loc);
+                }
+            }
         } else {
             // could not scan block, keep scanning but record this block as the most recent failure
             result.last_failed_block = block_hash;
@@ -3026,7 +3038,7 @@ bool CWallet::AttachChain(const std::shared_ptr<CWallet>& walletInstance, interf
 
         {
             WalletRescanReserver reserver(*walletInstance);
-            if (!reserver.reserve() || (ScanResult::SUCCESS != walletInstance->ScanForWalletTransactions(chain.getBlockHash(rescan_height), rescan_height, {} /* max height */, reserver, true /* update */).status)) {
+            if (!reserver.reserve() || (ScanResult::SUCCESS != walletInstance->ScanForWalletTransactions(chain.getBlockHash(rescan_height), rescan_height, /*max_height=*/{}, reserver, /*fUpdate=*/true, /*save_progress=*/true).status)) {
                 error = _("Failed to rescan the wallet during initialization");
                 return false;
             }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 7da601c3b7..206a4417a7 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -528,7 +528,7 @@ public:
         //! USER_ABORT.
         uint256 last_failed_block;
     };
-    ScanResult ScanForWalletTransactions(const uint256& start_block, int start_height, std::optional<int> max_height, const WalletRescanReserver& reserver, bool fUpdate);
+    ScanResult ScanForWalletTransactions(const uint256& start_block, int start_height, std::optional<int> max_height, const WalletRescanReserver& reserver, bool fUpdate, const bool save_progress);
     void transactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason, uint64_t mempool_sequence) override;
     void ReacceptWalletTransactions() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void ResendWalletTransactions();