// 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 (
"sync"
"time"
"github.com/dexon-foundation/dexon-consensus-core/blockdb"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
)
// Consensus implements DEXON Consensus algorithm.
type Consensus struct {
app Application
gov Governance
rbModule *reliableBroadcast
toModule *totalOrdering
ctModule *consensusTimestamp
db blockdb.BlockDatabase
lock sync.RWMutex
}
// NewConsensus construct an Consensus instance.
func NewConsensus(
app Application,
gov Governance,
db blockdb.BlockDatabase) *Consensus {
validatorSet := gov.GetValidatorSet()
// Setup acking by information returned from Governace.
rb := newReliableBroadcast()
for vID := range validatorSet {
rb.addValidator(vID)
}
// Setup sequencer by information returned from Governace.
// TODO(mission): the value of 'K' should be in governace.
// TODO(mission): the ratio of 'phi' should be in governance.
to := newTotalOrdering(
0,
uint64(2*(len(validatorSet)-1)/3+1),
uint64(len(validatorSet)))
return &Consensus{
rbModule: rb,
toModule: to,
ctModule: newConsensusTimestamp(),
app: app,
gov: gov,
db: db,
}
}
// ProcessBlock is the entry point to submit one block to a Consensus instance.
func (con *Consensus) ProcessBlock(b *types.Block) (err error) {
var (
deliveredBlocks []*types.Block
earlyDelivered bool
)
// To avoid application layer modify the content of block during
// processing, we should always operate based on the cloned one.
b = b.Clone()
con.lock.Lock()
defer con.lock.Unlock()
// Perform reliable broadcast checking.
if err = con.rbModule.processBlock(b); err != nil {
return err
}
for _, b := range con.rbModule.extractBlocks() {
// Notify application layer that some block is strongly acked.
con.app.StronglyAcked(b.Hash)
// Perform total ordering.
deliveredBlocks, earlyDelivered, err = con.toModule.processBlock(b)
if err != nil {
return
}
if len(deliveredBlocks) == 0 {
continue
}
for _, b := range deliveredBlocks {
if err = con.db.Put(*b); err != nil {
return
}
}
// TODO(mission): handle membership events here.
// TODO(mission): return block hash instead of whole block here.
con.app.TotalOrderingDeliver(deliveredBlocks, earlyDelivered)
// Perform timestamp generation.
deliveredBlocks, _, err = con.ctModule.processBlocks(
deliveredBlocks)
if err != nil {
return
}
for _, b := range deliveredBlocks {
if err = con.db.Update(*b); err != nil {
return
}
con.app.DeliverBlock(b.Hash, b.ConsensusInfo.Timestamp)
}
}
return
}
// PrepareBlock would setup header fields of block based on its ProposerID.
func (con *Consensus) PrepareBlock(b *types.Block) (err error) {
con.lock.RLock()
defer con.lock.RUnlock()
con.rbModule.prepareBlock(b)
b.Timestamps[b.ProposerID] = time.Now().UTC()
return
}