Merge #9827: Improve ScanForWalletTransactions return value

30abce7 Improve ScanForWalletTransactions return value (Russell Yanofsky)

Tree-SHA512: 195028553b103052a842b6a37e67410118a20c32475b80f7fd22d6d8622f92eca1c2d84f291d1092bef2161d3187d91052799b533e1e265b7613d51955490b8d

src/wallet/test/wallet_tests.cpp

@@ -424,6 +424,17 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
         BOOST_CHECK_EQUAL(response.write(), strprintf("[{\"success\":false,\"error\":{\"code\":-1,\"message\":\"Failed to rescan before time %d, transactions may be missing.\"}},{\"success\":true}]", newTip->GetBlockTimeMax()));
         ::pwalletMain = backup;
     }
+
+    // Verify ScanForWalletTransactions does not return null when the scan is
+    // elided due to the nTimeFirstKey optimization.
+    {
+        CWallet wallet;
+        {
+            LOCK(wallet.cs_wallet);
+            wallet.UpdateTimeFirstKey(newTip->GetBlockTime() + 7200 + 1);
+        }
+        BOOST_CHECK_EQUAL(newTip, wallet.ScanForWalletTransactions(newTip));
+    }
 }
 
 // Check that GetImmatureCredit() returns a newly calculated value instead of

src/wallet/wallet.cpp

@@ -1515,16 +1515,17 @@ void CWalletTx::GetAccountAmounts(const std::string& strAccount, CAmount& nRecei
  * exist in the wallet will be updated.
  *
  * Returns pointer to the first block in the last contiguous range that was
- * successfully scanned.
- *
+ * successfully scanned or elided (elided if pIndexStart points at a block
+ * before CWallet::nTimeFirstKey). Returns null if there is no such range, or
+ * the range doesn't include chainActive.Tip().
  */
 CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate)
 {
-    CBlockIndex* ret = nullptr;
     int64_t nNow = GetTime();
     const CChainParams& chainParams = Params();
 
     CBlockIndex* pindex = pindexStart;
+    CBlockIndex* ret = pindexStart;
     {
         LOCK2(cs_main, cs_wallet);
         fAbortRescan = false;