highperfocused/bitcoin
1
0
Fork 0
mirror of https://github.com/bitcoin/bitcoin.git synced 2025-11-11 22:50:59 +01:00
Code Issues Packages Projects Releases Wiki Activity

[docs] Improve commenting in coins.cpp|h

Browse Source 
Remove references to 'pruned' coins, which don't exist since the move
to per-txout coins db.
This commit is contained in:
John Newbery
2020-01-30 15:52:36 -05:00
parent 646f0ada02
commit c205979031
2 changed files with 65 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

49
src/coins.cpp
View File

@@ -77,8 +77,21 @@ void CCoinsViewCache::AddCoin(const COutPoint &outpoint, Coin&& coin, bool possi
}
if (!possible_overwrite) {
if (!it->second.coin.IsSpent()) {
throw std::logic_error("Adding new coin that replaces non-pruned entry");
throw std::logic_error("Attempted to overwrite an unspent coin (when possible_overwrite is false)");
}
// If the coin exists in this cache as a spent coin and is DIRTY, then
// its spentness hasn't been flushed to the parent cache. We're
// re-adding the coin to this cache now but we can't mark it as FRESH.
// If we mark it FRESH and then spend it before the cache is flushed
// we would remove it from this cache and would never flush spentness
// to the parent cache.
//
// Re-adding a spent coin can happen in the case of a re-org (the coin
// is 'spent' when the block adding it is disconnected and then
// re-added when it is also added in a newly connected block).
//
// If the coin doesn't exist in the current cache, or is spent but not
// DIRTY, then it can be marked FRESH.
fresh = !(it->second.flags & CCoinsCacheEntry::DIRTY);
}
it->second.coin = std::move(coin);
@@ -152,11 +165,11 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
}
CCoinsMap::iterator itUs = cacheCoins.find(it->first);
if (itUs == cacheCoins.end()) {
// 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
// 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.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) {
// Otherwise we will need to create it in the parent
// and move the data up and mark it as dirty
// Create the coin in the parent cache, move the data up
// and mark it as dirty.
CCoinsCacheEntry& entry = cacheCoins[it->first];
entry.coin = std::move(it->second.coin);
cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
@@ -169,19 +182,18 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
}
}
} else {
// Assert that the child cache entry was not marked FRESH if the
// parent cache entry has unspent outputs. If this ever happens,
// it means the FRESH flag was misapplied and there is a logic
// error in the calling code.
// Found the entry in the parent cache
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");
// The coin was marked FRESH in the child cache, but the coin
// exists in the parent cache. If this ever happens, it means
// the FRESH flag was misapplied and there is a logic error in
// the calling code.
throw std::logic_error("FRESH flag misapplied to coin that exists in parent cache");
}
// Found the entry in the parent cache
if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) {
// The grandparent does not have an entry, and the child is
// modified and being pruned. This means we can just delete
// it from the parent.
// The grandparent cache does not have an entry, and the coin
// has been spent. We can just delete it from the parent cache.
cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
cacheCoins.erase(itUs);
} else {
@@ -190,11 +202,10 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
itUs->second.coin = std::move(it->second.coin);
cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
itUs->second.flags |= CCoinsCacheEntry::DIRTY;
// NOTE: It is possible the child has a FRESH flag here in
// the event the entry we found in the parent is pruned. But
// we must not copy that FRESH flag to the parent as that
// pruned state likely still needs to be communicated to the
// grandparent.
// NOTE: It isn't safe to mark the coin as FRESH in the parent
// cache. If it already existed and was spent in the parent
// cache then marking it FRESH would prevent that spentness
// from being flushed to the grandparent.
}
}
}