// Copyright 2018 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 (
"fmt"
"github.com/dexon-foundation/dexon-consensus/core/types"
)
// Errors for agreement state module.
var (
ErrNoEnoughVoteInPrepareState = fmt.Errorf("no enough vote in prepare state")
ErrNoEnoughVoteInAckState = fmt.Errorf("no enough vote in ack state")
)
// agreementStateType is the state of agreement
type agreementStateType int
// agreementStateType enum.
const (
stateFast agreementStateType = iota
stateFastVote
stateInitial
statePreCommit
stateCommit
stateForward
statePullVote
stateSleep
)
type agreementState interface {
state() agreementStateType
nextState() (agreementState, error)
clocks() int
}
//----- FastState -----
type fastState struct {
a *agreementData
}
func newFastState(a *agreementData) *fastState {
return &fastState{a: a}
}
func (s *fastState) state() agreementStateType { return stateFast }
func (s *fastState) clocks() int { return 0 }
func (s *fastState) nextState() (agreementState, error) {
if func() bool {
s.a.lock.Lock()
defer s.a.lock.Unlock()
return s.a.isLeader
}() {
hash := s.a.recv.ProposeBlock()
if hash != types.NullBlockHash {
s.a.lock.Lock()
defer s.a.lock.Unlock()
s.a.recv.ProposeVote(types.NewVote(types.VoteFast, hash, s.a.period))
}
}
return newFastVoteState(s.a), nil
}
//----- FastVoteState -----
type fastVoteState struct {
a *agreementData
}
func newFastVoteState(a *agreementData) *fastVoteState {
return &fastVoteState{a: a}
}
func (s *fastVoteState) state() agreementStateType { return stateFastVote }
func (s *fastVoteState) clocks() int { return 3 }
func (s *fastVoteState) nextState() (agreementState, error) {
return newInitialState(s.a), nil
}
//----- InitialState -----
type initialState struct {
a *agreementData
}
func newInitialState(a *agreementData) *initialState {
return &initialState{a: a}
}
func (s *initialState) state() agreementStateType { return stateInitial }
func (s *initialState) clocks() int { return 0 }
func (s *initialState) nextState() (agreementState, error) {
if func() bool {
s.a.lock.Lock()
defer s.a.lock.Unlock()
return !s.a.isLeader
}() {
// Leader already proposed block in fastState.
hash := s.a.recv.ProposeBlock()
s.a.lock.Lock()
defer s.a.lock.Unlock()
s.a.recv.ProposeVote(types.NewVote(types.VoteInit, hash, s.a.period))
}
return newPreCommitState(s.a), nil
}
//----- PreCommitState -----
type preCommitState struct {
a *agreementData
}
func newPreCommitState(a *agreementData) *preCommitState {
return &preCommitState{a: a}
}
func (s *preCommitState) state() agreementStateType { return statePreCommit }
func (s *preCommitState) clocks() int { return 2 }
func (s *preCommitState) nextState() (agreementState, error) {
s.a.lock.RLock()
defer s.a.lock.RUnlock()
if s.a.lockValue == types.SkipBlockHash ||
s.a.lockValue == types.NullBlockHash {
hash := s.a.leader.leaderBlockHash()
s.a.recv.ProposeVote(types.NewVote(types.VotePreCom, hash, s.a.period))
} else {
s.a.recv.ProposeVote(types.NewVote(
types.VotePreCom, s.a.lockValue, s.a.period))
}
return newCommitState(s.a), nil
}
//----- CommitState -----
type commitState struct {
a *agreementData
}
func newCommitState(a *agreementData) *commitState {
return &commitState{a: a}
}
func (s *commitState) state() agreementStateType { return stateCommit }
func (s *commitState) clocks() int { return 2 }
func (s *commitState) nextState() (agreementState, error) {
s.a.lock.Lock()
defer s.a.lock.Unlock()
s.a.recv.ProposeVote(types.NewVote(types.VoteCom, s.a.lockValue, s.a.period))
return newForwardState(s.a), nil
}
// ----- ForwardState -----
type forwardState struct {
a *agreementData
}
func newForwardState(a *agreementData) *forwardState {
return &forwardState{a: a}
}
func (s *forwardState) state() agreementStateType { return stateForward }
func (s *forwardState) clocks() int { return 4 }
func (s *forwardState) nextState() (agreementState, error) {
return newPullVoteState(s.a), nil
}
// ----- PullVoteState -----
// pullVoteState is a special state to ensure the assumption in the consensus
// algorithm that every vote will eventually arrive for all nodes.
type pullVoteState struct {
a *agreementData
}
func newPullVoteState(a *agreementData) *pullVoteState {
return &pullVoteState{a: a}
}
func (s *pullVoteState) state() agreementStateType { return statePullVote }
func (s *pullVoteState) clocks() int { return 4 }
func (s *pullVoteState) nextState() (agreementState, error) {
return s, nil
}
// ----- SleepState -----
// sleepState is a special state after BA has output and waits for restart.
type sleepState struct {
a *agreementData
}
func newSleepState(a *agreementData) *sleepState {
return &sleepState{a: a}
}
func (s *sleepState) state() agreementStateType { return stateSleep }
func (s *sleepState) clocks() int { return 65536 }
func (s *sleepState) nextState() (agreementState, error) {
return s, nil
}
