1 files changed, 72 insertions, 0 deletions
diff --git a/vendor/github.com/byzantine-lab/dexon-consensus/core/utils/vote-filter.go b/vendor/github.com/byzantine-lab/dexon-consensus/core/utils/vote-filter.go
new file mode 100644
index 000000000..556c2489a
--- /dev/null
+++ b/vendor/github.com/byzantine-lab/dexon-consensus/core/utils/vote-filter.go
@@ -0,0 +1,72 @@
+// Copyright 2019 The dexon-consensus Authors
+// This file is part of the dexon-consensus library.
+//
+// The dexon-consensus library is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The dexon-consensus library is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the dexon-consensus library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package utils
+
+import (
+	"github.com/byzantine-lab/dexon-consensus/core/types"
+)
+
+// VoteFilter filters votes that are useless for now.
+// To maximize performance, this structure is not thread-safe and will never be.
+type VoteFilter struct {
+	Voted    map[types.VoteHeader]struct{}
+	Position types.Position
+	LockIter uint64
+	Period   uint64
+	Confirm  bool
+}
+
+// NewVoteFilter creates a new vote filter instance.
+func NewVoteFilter() *VoteFilter {
+	return &VoteFilter{
+		Voted: make(map[types.VoteHeader]struct{}),
+	}
+}
+
+// Filter checks if the vote should be filtered out.
+func (vf *VoteFilter) Filter(vote *types.Vote) bool {
+	if vote.Type == types.VoteInit {
+		return true
+	}
+	if vote.Position.Older(vf.Position) {
+		return true
+	} else if vote.Position.Newer(vf.Position) {
+		// It's impossible to check the vote of other height.
+		return false
+	}
+	if vf.Confirm {
+		return true
+	}
+	if vote.Type == types.VotePreCom && vote.Period < vf.LockIter {
+		return true
+	}
+	if vote.Type == types.VoteCom &&
+		vote.Period < vf.Period &&
+		vote.BlockHash == types.SkipBlockHash {
+		return true
+	}
+	if _, exist := vf.Voted[vote.VoteHeader]; exist {
+		return true
+	}
+	return false
+}
+
+// AddVote to the filter so the same vote will be filtered.
+func (vf *VoteFilter) AddVote(vote *types.Vote) {
+	vf.Voted[vote.VoteHeader] = struct{}{}
+}