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Merge #11353: Small refactor of CCoinsViewCache::BatchWrite()

5b9748f97 Small refactor of CCoinsViewCache::BatchWrite() (Dan Raviv)

Pull request description:

  `std::unordered_map::erase( const_iterator pos )` returns an iterator to the element following the removed one. Use that to optimize (probably minor-performance-wise, and definitely code-structure-wise) the implementation of `CCoinsViewCache::BatchWrite()`.

Tree-SHA512: 00abc838ad91771cfcddd45688841c9414869b75289d09b483a7f0ba835614fe189e9c8aca8a80e3de78ee397ec14083ae52e2e92b7863b3b6eb0d0cb892c9dd
0.16
MarcoFalke 7 years ago
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  1. 94
      src/coins.cpp

94
src/coins.cpp

@ -146,56 +146,58 @@ void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
} }
bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) { bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) { for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end(); it = mapCoins.erase(it)) {
if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization). // Ignore non-dirty entries (optimization).
CCoinsMap::iterator itUs = cacheCoins.find(it->first); if (!(it->second.flags & CCoinsCacheEntry::DIRTY)) {
if (itUs == cacheCoins.end()) { continue;
// The parent cache does not have an entry, while the child does }
// We can ignore it if it's both FRESH and pruned in the child CCoinsMap::iterator itUs = cacheCoins.find(it->first);
if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) { if (itUs == cacheCoins.end()) {
// Otherwise we will need to create it in the parent // The parent cache does not have an entry, while the child does
// and move the data up and mark it as dirty // We can ignore it if it's both FRESH and pruned in the child
CCoinsCacheEntry& entry = cacheCoins[it->first]; if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) {
entry.coin = std::move(it->second.coin); // Otherwise we will need to create it in the parent
cachedCoinsUsage += entry.coin.DynamicMemoryUsage(); // and move the data up and mark it as dirty
entry.flags = CCoinsCacheEntry::DIRTY; CCoinsCacheEntry& entry = cacheCoins[it->first];
// We can mark it FRESH in the parent if it was FRESH in the child entry.coin = std::move(it->second.coin);
// Otherwise it might have just been flushed from the parent's cache cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
// and already exist in the grandparent entry.flags = CCoinsCacheEntry::DIRTY;
if (it->second.flags & CCoinsCacheEntry::FRESH) // We can mark it FRESH in the parent if it was FRESH in the child
entry.flags |= CCoinsCacheEntry::FRESH; // Otherwise it might have just been flushed from the parent's cache
// and already exist in the grandparent
if (it->second.flags & CCoinsCacheEntry::FRESH) {
entry.flags |= CCoinsCacheEntry::FRESH;
} }
} else { }
// Assert that the child cache entry was not marked FRESH if the } else {
// parent cache entry has unspent outputs. If this ever happens, // Assert that the child cache entry was not marked FRESH if the
// it means the FRESH flag was misapplied and there is a logic // parent cache entry has unspent outputs. If this ever happens,
// error in the calling code. // it means the FRESH flag was misapplied and there is a logic
if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsSpent()) // error in the calling code.
throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs"); if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsSpent()) {
throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
}
// Found the entry in the parent cache // Found the entry in the parent cache
if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) { if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) {
// The grandparent does not have an entry, and the child is // The grandparent does not have an entry, and the child is
// modified and being pruned. This means we can just delete // modified and being pruned. This means we can just delete
// it from the parent. // it from the parent.
cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage(); cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
cacheCoins.erase(itUs); cacheCoins.erase(itUs);
} else { } else {
// A normal modification. // A normal modification.
cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage(); cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
itUs->second.coin = std::move(it->second.coin); itUs->second.coin = std::move(it->second.coin);
cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage(); cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
itUs->second.flags |= CCoinsCacheEntry::DIRTY; itUs->second.flags |= CCoinsCacheEntry::DIRTY;
// NOTE: It is possible the child has a FRESH flag here in // NOTE: It is possible the child has a FRESH flag here in
// the event the entry we found in the parent is pruned. But // the event the entry we found in the parent is pruned. But
// we must not copy that FRESH flag to the parent as that // we must not copy that FRESH flag to the parent as that
// pruned state likely still needs to be communicated to the // pruned state likely still needs to be communicated to the
// grandparent. // grandparent.
}
} }
} }
CCoinsMap::iterator itOld = it++;
mapCoins.erase(itOld);
} }
hashBlock = hashBlockIn; hashBlock = hashBlockIn;
return true; return true;

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