diff options
Diffstat (limited to 'vendor/github.com/dexon-foundation/dexon-consensus-core/core/consensus-timestamp.go')
-rw-r--r-- | vendor/github.com/dexon-foundation/dexon-consensus-core/core/consensus-timestamp.go | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus-core/core/consensus-timestamp.go b/vendor/github.com/dexon-foundation/dexon-consensus-core/core/consensus-timestamp.go new file mode 100644 index 000000000..49270d491 --- /dev/null +++ b/vendor/github.com/dexon-foundation/dexon-consensus-core/core/consensus-timestamp.go @@ -0,0 +1,129 @@ +// Copyright 2018 The dexon-consensus-core Authors +// This file is part of the dexon-consensus-core library. +// +// The dexon-consensus-core 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-core 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-core library. If not, see +// <http://www.gnu.org/licenses/>. + +package core + +import ( + "errors" + "time" + + "github.com/dexon-foundation/dexon-consensus-core/core/types" +) + +// consensusTimestamp is for Concensus Timestamp Algorithm. +type consensusTimestamp struct { + chainTimestamps []time.Time + + // This part keeps configs for each round. + numChainsOfRounds []uint32 + numChainsBase uint64 + + // dMoment represents the genesis time. + dMoment time.Time +} + +var ( + // ErrTimestampNotIncrease would be reported if the timestamp is not strickly + // increasing on the same chain. + ErrTimestampNotIncrease = errors.New("timestamp is not increasing") + // ErrNoRoundConfig for no round config found. + ErrNoRoundConfig = errors.New("no round config found") +) + +// newConsensusTimestamp creates timestamper object. +func newConsensusTimestamp( + dMoment time.Time, round uint64, numChains uint32) *consensusTimestamp { + ts := make([]time.Time, 0, numChains) + for i := uint32(0); i < numChains; i++ { + ts = append(ts, dMoment) + } + return &consensusTimestamp{ + numChainsOfRounds: []uint32{numChains}, + numChainsBase: round, + dMoment: dMoment, + chainTimestamps: ts, + } +} + +// appendConfig appends a configuration for upcoming round. When you append +// a config for round R, next time you can only append the config for round R+1. +func (ct *consensusTimestamp) appendConfig( + round uint64, config *types.Config) error { + + if round != uint64(len(ct.numChainsOfRounds))+ct.numChainsBase { + return ErrRoundNotIncreasing + } + ct.numChainsOfRounds = append(ct.numChainsOfRounds, config.NumChains) + return nil +} + +func (ct *consensusTimestamp) resizeChainTimetamps(numChain uint32) { + l := uint32(len(ct.chainTimestamps)) + if numChain > l { + for i := l; i < numChain; i++ { + ct.chainTimestamps = append(ct.chainTimestamps, ct.dMoment) + } + } else if numChain < l { + ct.chainTimestamps = ct.chainTimestamps[:numChain] + } +} + +// ProcessBlocks is the entry function. +func (ct *consensusTimestamp) processBlocks(blocks []*types.Block) (err error) { + for _, block := range blocks { + // Rounds might interleave within rounds if no configuration change + // occurs. And it is limited to one round, that is, round r can only + // interleave with r-1 and r+1. + round := block.Position.Round + if ct.numChainsBase == round || ct.numChainsBase+1 == round { + // Normal case, no need to modify chainTimestamps. + } else if ct.numChainsBase+2 == round { + if len(ct.numChainsOfRounds) < 2 { + return ErrNoRoundConfig + } + if ct.numChainsOfRounds[0] > ct.numChainsOfRounds[1] { + ct.resizeChainTimetamps(ct.numChainsOfRounds[0]) + } else { + ct.resizeChainTimetamps(ct.numChainsOfRounds[1]) + } + ct.numChainsBase++ + ct.numChainsOfRounds = ct.numChainsOfRounds[1:] + } else { + // Error if round < base or round > base + 2. + return ErrInvalidRoundID + } + ts := ct.chainTimestamps[:ct.numChainsOfRounds[round-ct.numChainsBase]] + if block.Finalization.Timestamp, err = getMedianTime(ts); err != nil { + return + } + if block.Timestamp.Before(ct.chainTimestamps[block.Position.ChainID]) { + return ErrTimestampNotIncrease + } + ct.chainTimestamps[block.Position.ChainID] = block.Timestamp + } + return +} + +func (ct *consensusTimestamp) isSynced() bool { + numChain := ct.numChainsOfRounds[0] + for i := uint32(0); i < numChain; i++ { + if ct.chainTimestamps[i].Equal(ct.dMoment) { + return false + } + } + return true +} |