Simplify return values of GetCoin/HaveCoin(InCache)

This removes the possibility for GetCoin/HaveCoin/HaveCoinInCache to return
true while the respective coin is spent. By doing it across all calls, some
extra checks can be eliminated.

coins_tests is modified to call HaveCoin sometimes before and sometimes
after AccessCoin. A further change is needed because the semantics for
GetCoin slightly changed, causing a pruned entry in the parent cache to not
be pulled into the child in FetchCoin.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/coins.cpp b/src/coins.cpp
index f8df835e9f..3113b7755d 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -11,11 +11,15 @@
 #include <assert.h>
 
 bool CCoinsView::GetCoin(const COutPoint &outpoint, Coin &coin) const { return false; }
-bool CCoinsView::HaveCoin(const COutPoint &outpoint) const { return false; }
 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
 CCoinsViewCursor *CCoinsView::Cursor() const { return 0; }
 
+bool CCoinsView::HaveCoin(const COutPoint &outpoint) const
+{
+    Coin coin;
+    return GetCoin(outpoint, coin);
+}
 
 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
 bool CCoinsViewBacked::GetCoin(const COutPoint &outpoint, Coin &coin) const { return base->GetCoin(outpoint, coin); }
@@ -55,7 +59,7 @@ bool CCoinsViewCache::GetCoin(const COutPoint &outpoint, Coin &coin) const {
     CCoinsMap::const_iterator it = FetchCoin(outpoint);
     if (it != cacheCoins.end()) {
         coin = it->second.coin;
-        return true;
+        return !coin.IsSpent();
     }
     return false;
 }