From 44405bd1a0c98382943af52cd1ef8b4ec3240fc4 Mon Sep 17 00:00:00 2001 From: Aayush Rajasekaran Date: Wed, 22 Sep 2021 16:22:25 -0400 Subject: [PATCH] ChainStore: Add a tiebreaker rule for tipsets of equal weight --- chain/store/store.go | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/chain/store/store.go b/chain/store/store.go index 4436c121778..733f25c3209 100644 --- a/chain/store/store.go +++ b/chain/store/store.go @@ -424,7 +424,13 @@ func (cs *ChainStore) MaybeTakeHeavierTipSet(ctx context.Context, ts *types.TipS return err } - if w.GreaterThan(heaviestW) { + heavier := w.GreaterThan(heaviestW) + if w.Equals(heaviestW) && !ts.Equals(cs.heaviest) { + log.Errorw("weight draw", "currTs", cs.heaviest, "ts", ts) + heavier = breakWeightTie(ts, cs.heaviest) + } + + if heavier { // TODO: don't do this for initial sync. Now that we don't have a // difference between 'bootstrap sync' and 'caught up' sync, we need // some other heuristic. @@ -438,9 +444,8 @@ func (cs *ChainStore) MaybeTakeHeavierTipSet(ctx context.Context, ts *types.TipS } return cs.takeHeaviestTipSet(ctx, ts) - } else if w.Equals(heaviestW) && !ts.Equals(cs.heaviest) { - log.Errorw("weight draw", "currTs", cs.heaviest, "ts", ts) } + return nil } @@ -1165,3 +1170,22 @@ func (cs *ChainStore) GetTipsetByHeight(ctx context.Context, h abi.ChainEpoch, t func (cs *ChainStore) Weight(ctx context.Context, hts *types.TipSet) (types.BigInt, error) { // todo remove return cs.weight(ctx, cs.StateBlockstore(), hts) } + +// true if ts1 wins according to the filecoin tie-break rule +func breakWeightTie(ts1, ts2 *types.TipSet) bool { + s := len(ts1.Blocks()) + if s > len(ts2.Blocks()) { + s = len(ts2.Blocks()) + } + + // blocks are already sorted by ticket + for i := 0; i < s; i++ { + if ts1.Blocks()[i].Ticket.Less(ts2.Blocks()[i].Ticket) { + log.Infof("weight tie broken in favour of %s", ts1.Key()) + return true + } + } + + log.Infof("weight tie left unbroken, default to %s", ts2.Key()) + return false +}