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CCoinsViewCache::BatchWrite lookup optimization

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In the case when parent cache does not have an entry while child cache does,
this reduces the double hash lookup (find + try_emplace) with a single
try_emplace.
This commit is contained in:
Martin Leitner-Ankerl 2025-03-22 18:24:33 +01:00
parent 104d5dd778
commit 723c49b63b
1 changed files with 25 additions and 21 deletions
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46
src/coins.cpp
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@ -186,30 +186,34 @@ bool CCoinsViewCache::BatchWrite(CoinsViewCacheCursor& cursor, const uint256 &ha
if (!it->second.IsDirty()) {
continue;
}
CCoinsMap::iterator itUs = cacheCoins.find(it->first);
if (itUs == cacheCoins.end()) {
CCoinsMap::iterator itUs;
bool isInserted = false;
if (!(it->second.IsFresh() && it->second.coin.IsSpent())) {
std::tie(itUs, isInserted) = cacheCoins.try_emplace(it->first);
} else {
itUs = cacheCoins.find(it->first);
}
if (isInserted) {
// The parent cache does not have an entry, while the child cache does.
// We can ignore it if it's both spent and FRESH in the child
if (!(it->second.IsFresh() && it->second.coin.IsSpent())) {
// Create the coin in the parent cache, move the data up
// and mark it as dirty.
itUs = cacheCoins.try_emplace(it->first).first;
CCoinsCacheEntry& entry{itUs->second};
if (cursor.WillErase(*it)) {
// Since this entry will be erased,
// we can move the coin into us instead of copying it
entry.coin = std::move(it->second.coin);
} else {
entry.coin = it->second.coin;
}
cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
CCoinsCacheEntry::SetDirty(*itUs, m_sentinel);
// We can mark it FRESH in the parent if it was FRESH in the child
// Otherwise it might have just been flushed from the parent's cache
// and already exist in the grandparent
if (it->second.IsFresh()) CCoinsCacheEntry::SetFresh(*itUs, m_sentinel);
// Create the coin in the parent cache, move the data up
// and mark it as dirty.
CCoinsCacheEntry& entry{itUs->second};
if (cursor.WillErase(*it)) {
// Since this entry will be erased,
// we can move the coin into us instead of copying it
entry.coin = std::move(it->second.coin);
} else {
entry.coin = it->second.coin;
}
} else {
cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
CCoinsCacheEntry::SetDirty(*itUs, m_sentinel);
// We can mark it FRESH in the parent if it was FRESH in the child
// Otherwise it might have just been flushed from the parent's cache
// and already exist in the grandparent
if (it->second.IsFresh()) CCoinsCacheEntry::SetFresh(*itUs, m_sentinel);
} else if (itUs != cacheCoins.end()) {
// Found the entry in the parent cache
if (it->second.IsFresh() && !itUs->second.coin.IsSpent()) {
// The coin was marked FRESH in the child cache, but the coin