From c444c620c62c51d65f7de0b2a3c351e61ab1e388 Mon Sep 17 00:00:00 2001
From: jtimon <jtimon@blockstream.io>
Date: Sun, 19 Oct 2014 02:57:02 +0200
Subject: [PATCH] Decouple CCoins from CTxInUndo

---
 src/coins.cpp | 22 ++++------------------
 src/coins.h   |  6 +-----
 src/main.cpp  | 17 ++++++++++++++---
 3 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/src/coins.cpp b/src/coins.cpp
index bc430c9c7..f4599ff39 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -31,29 +31,15 @@ void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) con
     nBytes += nLastUsedByte;
 }
 
-bool CCoins::Spend(const COutPoint &out, CTxInUndo &undo) {
-    if (out.n >= vout.size())
-        return false;
-    if (vout[out.n].IsNull())
+bool CCoins::Spend(uint32_t nPos) 
+{
+    if (nPos >= vout.size() || vout[nPos].IsNull())
         return false;
-    undo = CTxInUndo(vout[out.n]);
-    vout[out.n].SetNull();
+    vout[nPos].SetNull();
     Cleanup();
-    if (vout.size() == 0) {
-        undo.nHeight = nHeight;
-        undo.fCoinBase = fCoinBase;
-        undo.nVersion = this->nVersion;
-    }
     return true;
 }
 
-bool CCoins::Spend(int nPos) {
-    CTxInUndo undo;
-    COutPoint out(0, nPos);
-    return Spend(out, undo);
-}
-
-
 bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) const { return false; }
 bool CCoinsView::HaveCoins(const uint256 &txid) const { return false; }
 uint256 CCoinsView::GetBestBlock() const { return uint256(0); }
diff --git a/src/coins.h b/src/coins.h
index 9b73ae3a8..2be52ad17 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -9,7 +9,6 @@
 #include "compressor.h"
 #include "serialize.h"
 #include "uint256.h"
-#include "undo.h"
 
 #include <assert.h>
 #include <stdint.h>
@@ -237,11 +236,8 @@ public:
         Cleanup();
     }
 
-    //! mark an outpoint spent, and construct undo information
-    bool Spend(const COutPoint &out, CTxInUndo &undo);
-
     //! mark a vout spent
-    bool Spend(int nPos);
+    bool Spend(uint32_t nPos);
 
     //! check whether a particular output is still available
     bool IsAvailable(unsigned int nPos) const {
diff --git a/src/main.cpp b/src/main.cpp
index 2410230ef..3f775e3d3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1383,9 +1383,20 @@ void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCach
     if (!tx.IsCoinBase()) {
         txundo.vprevout.reserve(tx.vin.size());
         BOOST_FOREACH(const CTxIn &txin, tx.vin) {
-            txundo.vprevout.push_back(CTxInUndo());
-            bool ret = inputs.ModifyCoins(txin.prevout.hash)->Spend(txin.prevout, txundo.vprevout.back());
-            assert(ret);
+            CCoinsModifier coins = inputs.ModifyCoins(txin.prevout.hash);
+            unsigned nPos = txin.prevout.n;
+
+            if (nPos >= coins->vout.size() || coins->vout[nPos].IsNull())
+                assert(false);
+            // mark an outpoint spent, and construct undo information
+            txundo.vprevout.push_back(CTxInUndo(coins->vout[nPos]));
+            coins->Spend(nPos);
+            if (coins->vout.size() == 0) {
+                CTxInUndo& undo = txundo.vprevout.back();
+                undo.nHeight = coins->nHeight;
+                undo.fCoinBase = coins->fCoinBase;
+                undo.nVersion = coins->nVersion;
+            }
         }
     }