Add CCoinsViewCache::HaveCoinsInCache to check if a tx is cached

src/coins.cpp

@@ -144,6 +144,11 @@ bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
     return (it != cacheCoins.end() && !it->second.coins.vout.empty());
 }
 
+bool CCoinsViewCache::HaveCoinsInCache(const uint256 &txid) const {
+    CCoinsMap::const_iterator it = cacheCoins.find(txid);
+    return it != cacheCoins.end();
+}
+
 uint256 CCoinsViewCache::GetBestBlock() const {
     if (hashBlock.IsNull())
         hashBlock = base->GetBestBlock();

src/coins.h

@@ -405,6 +405,13 @@ public:
     void SetBestBlock(const uint256 &hashBlock);
     bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
 
+    /**
+     * Check if we have the given tx already loaded in this cache.
+     * The semantics are the same as HaveCoins(), but no calls to
+     * the backing CCoinsView are made.
+     */
+    bool HaveCoinsInCache(const uint256 &txid) const;
+
     /**
      * Return a pointer to CCoins in the cache, or NULL if not found. This is
      * more efficient than GetCoins. Modifications to other cache entries are