Optimization: Minimize the number of times it is checked that no money is created

by individual transactions to 2 places (but call only once in each):

- ConnectBlock ( before calculated fees per txs twice )
- AcceptToMemoryPoolWorker ( before called CheckTxInputs 4 times and calculated
   fees per tx one extra time )

Also call tx.GetValueOut() only once per call of CheckTxInputs (instead of 2)

1 files changed, 11 insertions, 13 deletions

diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp
index 25647ba6af..f2f85edad9 100644
--- a/src/consensus/tx_verify.cpp
+++ b/src/consensus/tx_verify.cpp
@@ -205,16 +205,15 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fChe
     return true;
 }
 
-bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight)
+bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee)
 {
-    // This doesn't trigger the DoS code on purpose; if it did, it would make it easier
-    // for an attacker to attempt to split the network.
+    // are the actual inputs available?
     if (!inputs.HaveInputs(tx)) {
-        return state.Invalid(false, 0, "", "Inputs unavailable");
+        return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-missingorspent", false,
+                         strprintf("%s: inputs missing/spent", __func__));
     }
 
     CAmount nValueIn = 0;
-    CAmount nFees = 0;
     for (unsigned int i = 0; i < tx.vin.size(); ++i) {
         const COutPoint &prevout = tx.vin[i].prevout;
         const Coin& coin = inputs.AccessCoin(prevout);
@@ -234,19 +233,18 @@ bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, c
         }
     }
 
-    if (nValueIn < tx.GetValueOut()) {
+    const CAmount value_out = tx.GetValueOut();
+    if (nValueIn < value_out) {
         return state.DoS(100, false, REJECT_INVALID, "bad-txns-in-belowout", false,
-            strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(tx.GetValueOut())));
+            strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(value_out)));
     }
 
     // Tally transaction fees
-    CAmount nTxFee = nValueIn - tx.GetValueOut();
-    if (nTxFee < 0) {
-        return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-negative");
-    }
-    nFees += nTxFee;
-    if (!MoneyRange(nFees)) {
+    const CAmount txfee_aux = nValueIn - value_out;
+    if (!MoneyRange(txfee_aux)) {
         return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-outofrange");
     }
+
+    txfee = txfee_aux;
     return true;
 }