Add RescanFromTime method and use from rpcdump

No change in behavior.

src/wallet/wallet.cpp

@@ -221,6 +221,10 @@ bool CWallet::LoadCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigne
     return CCryptoKeyStore::AddCryptedKey(vchPubKey, vchCryptedSecret);
 }
 
+/**
+ * Update wallet first key creation time. This should be called whenever keys
+ * are added to the wallet, with the oldest key creation time.
+ */
 void CWallet::UpdateTimeFirstKey(int64_t nCreateTime)
 {
     AssertLockHeld(cs_wallet);
@@ -1458,6 +1462,34 @@ void CWalletTx::GetAmounts(std::list<COutputEntry>& listReceived,
 
 }
 
+/**
+ * Scan active chain for relevant transactions after importing keys. This should
+ * be called whenever new keys are added to the wallet, with the oldest key
+ * creation time minus TIMESTAMP_WINDOW.
+ *
+ * @return Earliest timestamp that could be successfully scanned from. Timestamp
+ * returned may be higher than startTime if some blocks could not be read.
+ */
+int64_t CWallet::RescanFromTime(int64_t startTime, bool update)
+{
+    AssertLockHeld(cs_main);
+    AssertLockHeld(cs_wallet);
+
+    // Find starting block. May be null if nCreateTime is greater than the
+    // highest blockchain timestamp, in which case there is nothing that needs
+    // to be scanned.
+    CBlockIndex* const startBlock = chainActive.FindEarliestAtLeast(startTime);
+    LogPrintf("%s: Rescanning last %i blocks\n", __func__, startBlock ? chainActive.Height() - startBlock->nHeight + 1 : 0);
+
+    if (startBlock) {
+        const CBlockIndex* const failedBlock = ScanForWalletTransactions(startBlock, update);
+        if (failedBlock) {
+            return failedBlock->GetBlockTimeMax() + 1;
+        }
+    }
+    return startTime;
+}
+
 /**
  * Scan the block chain (starting in pindexStart) for transactions
  * from or to us. If fUpdate is true, found transactions that already