From 2ec349bc420d7f4541bf91acf8b830377a1421f3 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <sipa@ulyssis.org>
Date: Tue, 21 May 2013 02:36:48 +0200
Subject: [PATCH] CreateNewBlock performance improvements

---
 src/main.cpp | 28 +++++++++-------------------
 src/main.h   |  2 +-
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index e2bed527..2d22541b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1342,7 +1342,7 @@ unsigned int CTransaction::GetP2SHSigOpCount(CCoinsViewCache& inputs) const
     return nSigOps;
 }
 
-bool CTransaction::UpdateCoins(CValidationState &state, CCoinsViewCache &inputs, CTxUndo &txundo, int nHeight, const uint256 &txhash) const
+void CTransaction::UpdateCoins(CValidationState &state, CCoinsViewCache &inputs, CTxUndo &txundo, int nHeight, const uint256 &txhash) const
 {
     // mark inputs spent
     if (!IsCoinBase()) {
@@ -1356,8 +1356,6 @@ bool CTransaction::UpdateCoins(CValidationState &state, CCoinsViewCache &inputs,
 
     // add outputs
     assert(inputs.SetCoins(txhash, CCoins(*this, nHeight)));
-
-    return true;
 }
 
 bool CTransaction::HaveInputs(CCoinsViewCache &inputs) const
@@ -1683,8 +1681,7 @@ bool CBlock::ConnectBlock(CValidationState &state, CBlockIndex* pindex, CCoinsVi
         }
 
         CTxUndo txundo;
-        if (!tx.UpdateCoins(state, view, txundo, pindex->nHeight, GetTxHash(i)))
-            return error("ConnectBlock() : UpdateInputs failed");
+        tx.UpdateCoins(state, view, txundo, pindex->nHeight, GetTxHash(i));
         if (!tx.IsCoinBase())
             blockundo.vtxundo.push_back(txundo);
 
@@ -4233,8 +4230,7 @@ CBlockTemplate* CreateNewBlock(CReserveKey& reservekey)
             BOOST_FOREACH(const CTxIn& txin, tx.vin)
             {
                 // Read prev transaction
-                CCoins coins;
-                if (!view.GetCoins(txin.prevout.hash, coins))
+                if (!view.HaveCoins(txin.prevout.hash))
                 {
                     // This should never happen; all transactions in the memory
                     // pool should connect to either transactions in the chain
@@ -4261,6 +4257,7 @@ CBlockTemplate* CreateNewBlock(CReserveKey& reservekey)
                     nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
                     continue;
                 }
+                const CCoins &coins = view.GetCoins(txin.prevout.hash);
 
                 int64 nValueIn = coins.vout[txin.prevout.n].nValue;
                 nTotalIn += nValueIn;
@@ -4308,9 +4305,6 @@ CBlockTemplate* CreateNewBlock(CReserveKey& reservekey)
             std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
             vecPriority.pop_back();
 
-            // second layer cached modifications just for this transaction
-            CCoinsViewCache viewTemp(view, true);
-
             // Size limits
             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
             if (nBlockSize + nTxSize >= nBlockMaxSize)
@@ -4335,26 +4329,22 @@ CBlockTemplate* CreateNewBlock(CReserveKey& reservekey)
                 std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
             }
 
-            if (!tx.HaveInputs(viewTemp))
+            if (!tx.HaveInputs(view))
                 continue;
 
-            int64 nTxFees = tx.GetValueIn(viewTemp)-tx.GetValueOut();
+            int64 nTxFees = tx.GetValueIn(view)-tx.GetValueOut();
 
-            nTxSigOps += tx.GetP2SHSigOpCount(viewTemp);
+            nTxSigOps += tx.GetP2SHSigOpCount(view);
             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                 continue;
 
             CValidationState state;
-            if (!tx.CheckInputs(state, viewTemp, true, SCRIPT_VERIFY_P2SH))
+            if (!tx.CheckInputs(state, view, true, SCRIPT_VERIFY_P2SH))
                 continue;
 
             CTxUndo txundo;
             uint256 hash = tx.GetHash();
-            if (!tx.UpdateCoins(state, viewTemp, txundo, pindexPrev->nHeight+1, hash))
-                continue;
-
-            // push changes from the second layer cache to the first one
-            viewTemp.Flush();
+            tx.UpdateCoins(state, view, txundo, pindexPrev->nHeight+1, hash);
 
             // Added
             pblock->vtx.push_back(tx);
diff --git a/src/main.h b/src/main.h
index cba8421c..8e71e66c 100644
--- a/src/main.h
+++ b/src/main.h
@@ -659,7 +659,7 @@ public:
                      std::vector<CScriptCheck> *pvChecks = NULL) const;
 
     // Apply the effects of this transaction on the UTXO set represented by view
-    bool UpdateCoins(CValidationState &state, CCoinsViewCache &view, CTxUndo &txundo, int nHeight, const uint256 &txhash) const;
+    void UpdateCoins(CValidationState &state, CCoinsViewCache &view, CTxUndo &txundo, int nHeight, const uint256 &txhash) const;
 
     // Context-independent validity checks
     bool CheckTransaction(CValidationState &state) const;