Reduce unnecessary hashing in signrawtransaction

Author: jonasnick

src/rpc/rawtransaction.cpp

@@ -743,6 +743,9 @@ UniValue signrawtransaction(const UniValue& params, bool fHelp)
     // Script verification errors
     UniValue vErrors(UniValue::VARR);
 
+    // Use CTransaction for the constant parts of the
+    // transaction to avoid rehashing.
+    const CTransaction txConst(mergedTx);
     // Sign what we can:
     for (unsigned int i = 0; i < mergedTx.vin.size(); i++) {
         CTxIn& txin = mergedTx.vin[i];
@@ -760,10 +763,10 @@ UniValue signrawtransaction(const UniValue& params, bool fHelp)
 
         // ... and merge in other signatures:
         BOOST_FOREACH(const CMutableTransaction& txv, txVariants) {
-            txin.scriptSig = CombineSignatures(prevPubKey, mergedTx, i, txin.scriptSig, txv.vin[i].scriptSig);
+            txin.scriptSig = CombineSignatures(prevPubKey, txConst, i, txin.scriptSig, txv.vin[i].scriptSig);
         }
         ScriptError serror = SCRIPT_ERR_OK;
-        if (!VerifyScript(txin.scriptSig, prevPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, MutableTransactionSignatureChecker(&mergedTx, i), &serror)) {
+        if (!VerifyScript(txin.scriptSig, prevPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, TransactionSignatureChecker(&txConst, i), &serror)) {
             TxInErrorToJSON(txin, vErrors, ScriptErrorString(serror));
         }
     }