[wallet] Add support for aborting wallet transaction rescans.

src/wallet/wallet.cpp

@@ -1527,6 +1527,8 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
     CBlockIndex* pindex = pindexStart;
     {
         LOCK2(cs_main, cs_wallet);
+        fAbortRescan = false;
+        fScanningWallet = true;
 
         // no need to read and scan block, if block was created before
         // our wallet birthday (as adjusted for block time variability)
@@ -1536,7 +1538,7 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
         ShowProgress(_("Rescanning..."), 0); // show rescan progress in GUI as dialog or on splashscreen, if -rescan on startup
         double dProgressStart = GuessVerificationProgress(chainParams.TxData(), pindex);
         double dProgressTip = GuessVerificationProgress(chainParams.TxData(), chainActive.Tip());
-        while (pindex)
+        while (pindex && !fAbortRescan)
         {
             if (pindex->nHeight % 100 == 0 && dProgressTip - dProgressStart > 0.0)
                 ShowProgress(_("Rescanning..."), std::max(1, std::min(99, (int)((GuessVerificationProgress(chainParams.TxData(), pindex) - dProgressStart) / (dProgressTip - dProgressStart) * 100))));
@@ -1558,7 +1560,12 @@ CBlockIndex* CWallet::ScanForWalletTransactions(CBlockIndex* pindexStart, bool f
                 LogPrintf("Still rescanning. At block %d. Progress=%f\n", pindex->nHeight, GuessVerificationProgress(chainParams.TxData(), pindex));
             }
         }
+        if (pindex && fAbortRescan) {
+            LogPrintf("Rescan aborted at block %d. Progress=%f\n", pindex->nHeight, GuessVerificationProgress(chainParams.TxData(), pindex));
+        }
         ShowProgress(_("Rescanning..."), 100); // hide progress dialog in GUI
+
+        fScanningWallet = false;
     }
     return ret;
 }

src/wallet/wallet.h

@@ -651,6 +651,8 @@ class CWallet : public CCryptoKeyStore, public CValidationInterface
 {
 private:
     static std::atomic<bool> fFlushScheduled;
+    std::atomic<bool> fAbortRescan;
+    std::atomic<bool> fScanningWallet;
 
     /**
      * Select a set of coins such that nValueRet >= nTargetValue and at least
@@ -775,6 +777,8 @@ public:
         nTimeFirstKey = 0;
         fBroadcastTransactions = false;
         nRelockTime = 0;
+        fAbortRescan = false;
+        fScanningWallet = false;
     }
 
     std::map<uint256, CWalletTx> mapWallet;
@@ -819,6 +823,13 @@ public:
     void UnlockAllCoins();
     void ListLockedCoins(std::vector<COutPoint>& vOutpts);
 
+    /*
+     * Rescan abort properties
+     */
+    void AbortRescan() { fAbortRescan = true; }
+    bool IsAbortingRescan() { return fAbortRescan; }
+    bool IsScanning() { return fScanningWallet; }
+
     /**
      * keystore implementation
      * Generate a new key