ModifyNewCoins saves database lookups

When processing a new transaction, in addition to spending the Coins of its txin's it creates a new Coins for its outputs.  The existing ModifyCoins function will first make sure this Coins does not already exist.  It can not exist due to BIP 30, but because of that the lookup can't be cached and always has to go to the database.  Since we are creating the coins to match the new tx anyway, there is no point in checking if they exist first anyway.  However this should not be used for coinbase tx's in order to preserve the historical behavior of overwriting the two existing duplicate tx pairs.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/coins.cpp b/src/coins.cpp
index f02949de53..96b336ce77 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -117,6 +117,15 @@ CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
     return CCoinsModifier(*this, ret.first, cachedCoinUsage);
 }
 
+CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid) {
+    assert(!hasModifier);
+    std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
+    ret.first->second.coins.Clear();
+    ret.first->second.flags = CCoinsCacheEntry::FRESH;
+    ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
+    return CCoinsModifier(*this, ret.first, 0);
+}
+
 const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
     CCoinsMap::const_iterator it = FetchCoins(txid);
     if (it == cacheCoins.end()) {