Add core.agreementEvent

1 files changed, 127 insertions, 0 deletions

diff --git a/core/agreement-event.go b/core/agreement-event.go
new file mode 100644
index 0000000..de4d808
--- /dev/null
+++ b/core/agreement-event.go
@@ -0,0 +1,127 @@
+// 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 core
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	"github.com/dexon-foundation/dexon-consensus/common"
+	"github.com/dexon-foundation/dexon-consensus/core/types"
+)
+
+// agreementEventType is the type of agreemnt event.
+type agreementEventType byte
+
+// agreementEventType enum.
+const (
+	// agreementEventInvalid is just a type guard, not intend to be used.
+	agreementEventInvalid agreementEventType = iota
+	// agreementEventLock is triggered when receiving more than 2t+1 pre-commit
+	// votes for one value.
+	agreementEventLock
+	// agreementEventForward is triggered when receiving more than 2t+1 commit
+	// votes for different values.
+	agreementEventForward
+	// agreementEventDecide is triggered when receiving more than 2t+1 commit
+	// votes for one value.
+	agreementEventDecide
+	// agreementEventFork is triggered when detecting a fork vote.
+	agreementEventFork
+	// Do not add any type below maxAgreementEventType.
+	maxAgreementEventType
+)
+
+func (t agreementEventType) String() string {
+	switch t {
+	case agreementEventLock:
+		return "Lock"
+	case agreementEventForward:
+		return "Forward"
+	case agreementEventDecide:
+		return "Decide"
+	case agreementEventFork:
+		return "Fork"
+	default:
+		return fmt.Sprintf("Unknown-%d", t)
+	}
+}
+
+// agreementEvent represents an agreement event, ex. fast forward, decide,
+// fork, ..., which would trigger state change of agreement module.
+type agreementEvent struct {
+	types.AgreementResult
+
+	period   uint64
+	evtType  agreementEventType
+	voteType types.VoteType
+}
+
+func (e agreementEvent) toAgreementResult() types.AgreementResult {
+	if e.evtType != agreementEventDecide {
+		panic(fmt.Errorf("invalid event to extract agreement result: %s", e))
+	}
+	return e.AgreementResult
+}
+
+func (e agreementEvent) String() string {
+	if len(e.Randomness) > 0 {
+		return fmt.Sprintf(
+			"agreementEvent{[%s:%s:%s:%d],Empty:%t,Hash:%s,Rand:%s}",
+			e.evtType, e.voteType, e.Position, e.period, e.IsEmptyBlock,
+			e.BlockHash.String()[:6], hex.EncodeToString(e.Randomness)[:6])
+	}
+	return fmt.Sprintf(
+		"agreementEvent{[%s:%s:%s:%d],Empty:%t,Hash:%s}",
+		e.evtType, e.voteType, e.Position, e.period, e.IsEmptyBlock,
+		e.BlockHash.String()[:6])
+}
+
+// newAgreementEvent constructs an agreementEvent instance.
+func newAgreementEvent(
+	t agreementEventType, votes []types.Vote) *agreementEvent {
+	return &agreementEvent{
+		AgreementResult: types.AgreementResult{
+			Position:     votes[0].Position,
+			Votes:        votes,
+			IsEmptyBlock: votes[0].BlockHash == types.NullBlockHash,
+			BlockHash:    votes[0].BlockHash,
+		},
+		period:   votes[0].Period,
+		evtType:  t,
+		voteType: votes[0].Type,
+	}
+}
+
+func newAgreementEventFromTSIG(
+	position types.Position,
+	hash common.Hash,
+	tSig []byte,
+	isEmpty bool) *agreementEvent {
+	return &agreementEvent{
+		AgreementResult: types.AgreementResult{
+			Position:     position,
+			BlockHash:    hash,
+			IsEmptyBlock: isEmpty,
+			Randomness:   tSig,
+		},
+		period:   0,
+		evtType:  agreementEventDecide,
+		voteType: types.MaxVoteType,
+	}
+}