From de273d53004f48e4c8c965f7ce0bd375fd8d0d69 Mon Sep 17 00:00:00 2001 From: glozow Date: Tue, 9 Jul 2024 13:47:30 +0100 Subject: MiniMiner: use FeeFrac in AncestorFeerateComparator Comparing using FeeFracs is more precise, allows us to simply the code since FeeFrac comparison internally does cross-multiplication, and avoids potential overflow in the multiplication. Previously, we were only comparing feerates up to 0.001sat/vB precision, since CFeeRate comparison just looks at their respective nSatoshisPerK. This could lead to MiniMiner selecting packages in the wrong order (i.e. by txid) if their feerates were less than 0.001sat/vB different. --- src/node/mini_miner.cpp | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) (limited to 'src/node') diff --git a/src/node/mini_miner.cpp b/src/node/mini_miner.cpp index 58422c4439..d7d15554b3 100644 --- a/src/node/mini_miner.cpp +++ b/src/node/mini_miner.cpp @@ -174,7 +174,7 @@ MiniMiner::MiniMiner(const std::vector& manual_entries, SanityCheck(); } -// Compare by min(ancestor feerate, individual feerate), then iterator +// Compare by min(ancestor feerate, individual feerate), then txid // // Under the ancestor-based mining approach, high-feerate children can pay for parents, but high-feerate // parents do not incentive inclusion of their children. Therefore the mining algorithm only considers @@ -183,21 +183,13 @@ struct AncestorFeerateComparator { template bool operator()(const I& a, const I& b) const { - auto min_feerate = [](const MiniMinerMempoolEntry& e) -> CFeeRate { - const CAmount ancestor_fee{e.GetModFeesWithAncestors()}; - const int64_t ancestor_size{e.GetSizeWithAncestors()}; - const CAmount tx_fee{e.GetModifiedFee()}; - const int64_t tx_size{e.GetTxSize()}; - // Comparing ancestor feerate with individual feerate: - // ancestor_fee / ancestor_size <= tx_fee / tx_size - // Avoid division and possible loss of precision by - // multiplying both sides by the sizes: - return ancestor_fee * tx_size < tx_fee * ancestor_size ? - CFeeRate(ancestor_fee, ancestor_size) : - CFeeRate(tx_fee, tx_size); + auto min_feerate = [](const MiniMinerMempoolEntry& e) -> FeeFrac { + FeeFrac self_feerate(e.GetModifiedFee(), e.GetTxSize()); + FeeFrac ancestor_feerate(e.GetModFeesWithAncestors(), e.GetSizeWithAncestors()); + return std::min(ancestor_feerate, self_feerate); }; - CFeeRate a_feerate{min_feerate(a->second)}; - CFeeRate b_feerate{min_feerate(b->second)}; + FeeFrac a_feerate{min_feerate(a->second)}; + FeeFrac b_feerate{min_feerate(b->second)}; if (a_feerate != b_feerate) { return a_feerate > b_feerate; } -- cgit v1.2.3