// 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"
"sync"
"time"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/crypto"
"github.com/dexon-foundation/dexon-consensus/core/types"
)
// Errors for compaction chain module.
var (
ErrBlockNotRegistered = fmt.Errorf(
"block not registered")
ErrNotInitiazlied = fmt.Errorf(
"not initialized")
ErrTSigNotReady = fmt.Errorf(
"tsig not ready")
ErrIncorrectBlockRandomnessResult = fmt.Errorf(
"incorrect block randomness result")
)
const maxPendingPeriod = 3 * time.Second
type pendingRandomnessResult struct {
receivedTime time.Time
randResult *types.BlockRandomnessResult
}
type finalizedBlockHeap = types.ByFinalizationHeight
type compactionChain struct {
gov Governance
chainUnsynced uint32
tsigVerifier *TSigVerifierCache
blocks map[common.Hash]*types.Block
blockRandomness map[common.Hash][]byte
pendingRandomness map[common.Hash]pendingRandomnessResult
pendingBlocks []*types.Block
lock sync.RWMutex
prevBlock *types.Block
}
func newCompactionChain(gov Governance) *compactionChain {
return &compactionChain{
gov: gov,
tsigVerifier: NewTSigVerifierCache(gov, 7),
blocks: make(map[common.Hash]*types.Block),
blockRandomness: make(map[common.Hash][]byte),
pendingRandomness: make(map[common.Hash]pendingRandomnessResult),
}
}
// init the compaction chain module with a finalized block, or just an empty
// block for bootstrap case.
func (cc *compactionChain) init(initBlock *types.Block) {
cc.lock.Lock()
defer cc.lock.Unlock()
cc.prevBlock = initBlock
cc.pendingBlocks = []*types.Block{}
// It's the bootstrap case, compactionChain would only deliver blocks until
// tips of all chains are received.
if initBlock.Finalization.Height == 0 {
cc.chainUnsynced = cc.gov.Configuration(uint64(0)).NumChains
}
}
func (cc *compactionChain) registerBlock(block *types.Block) {
if cc.blockRegistered(block.Hash) {
return
}
cc.lock.Lock()
defer cc.lock.Unlock()
cc.blocks[block.Hash] = block
if rand, exist := cc.pendingRandomness[block.Hash]; exist {
cc.blockRandomness[rand.randResult.BlockHash] = rand.randResult.Randomness
delete(cc.pendingRandomness, block.Hash)
}
}
func (cc *compactionChain) blockRegistered(hash common.Hash) bool {
cc.lock.RLock()
defer cc.lock.RUnlock()
return cc.blockRegisteredNoLock(hash)
}
func (cc *compactionChain) blockRegisteredNoLock(
hash common.Hash) (exist bool) {
_, exist = cc.blocks[hash]
return
}
func (cc *compactionChain) processBlock(block *types.Block) error {
prevBlock := cc.lastDeliveredBlock()
if prevBlock == nil {
return ErrNotInitiazlied
}
cc.lock.Lock()
defer cc.lock.Unlock()
if prevBlock.Finalization.Height == 0 && block.Position.Height == 0 {
cc.chainUnsynced--
}
cc.pendingBlocks = append(cc.pendingBlocks, block)
return nil
}
func (cc *compactionChain) extractBlocks() []*types.Block {
prevBlock := cc.lastDeliveredBlock()
// Check if we're synced.
if !func() bool {
cc.lock.RLock()
defer cc.lock.RUnlock()
if len(cc.pendingBlocks) == 0 {
return false
}
// Finalization.Height == 0 is syncing from bootstrap.
if prevBlock.Finalization.Height == 0 {
return cc.chainUnsynced == 0
}
return true
}() {
return []*types.Block{}
}
deliveringBlocks := make([]*types.Block, 0)
cc.lock.Lock()
defer cc.lock.Unlock()
var block *types.Block
for len(cc.pendingBlocks) > 0 &&
(len(cc.blockRandomness[cc.pendingBlocks[0].Hash]) != 0 ||
cc.pendingBlocks[0].Position.Round == 0) {
delete(cc.blocks, cc.pendingBlocks[0].Hash)
block, cc.pendingBlocks = cc.pendingBlocks[0], cc.pendingBlocks[1:]
block.Finalization.ParentHash = prevBlock.Hash
block.Finalization.Height = prevBlock.Finalization.Height + 1
if block.Position.Round != 0 {
block.Finalization.Randomness = cc.blockRandomness[block.Hash]
delete(cc.blockRandomness, block.Hash)
}
deliveringBlocks = append(deliveringBlocks, block)
prevBlock = block
}
cc.prevBlock = prevBlock
return deliveringBlocks
}
func (cc *compactionChain) verifyRandomness(
blockHash common.Hash, round uint64, randomness []byte) (bool, error) {
if round == 0 {
return len(randomness) == 0, nil
}
// Randomness is not available at round 0.
v, ok, err := cc.tsigVerifier.UpdateAndGet(round)
if err != nil {
return false, err
}
if !ok {
return false, ErrTSigNotReady
}
return v.VerifySignature(blockHash, crypto.Signature{
Type: "bls",
Signature: randomness}), nil
}
func (cc *compactionChain) processFinalizedBlock(block *types.Block) error {
if block.Finalization.Height <= cc.lastDeliveredBlock().Finalization.Height {
return nil
}
// Block of round 0 should not have randomness.
if block.Position.Round == 0 && len(block.Finalization.Randomness) != 0 {
return nil
}
cc.lock.Lock()
defer cc.lock.Unlock()
// The randomness result is missed previously.
if cc.blockRegisteredNoLock(block.Hash) {
ok, err := cc.verifyRandomness(
block.Hash, block.Position.Round, block.Finalization.Randomness)
if err != nil {
return err
}
if ok {
cc.blockRandomness[block.Hash] = block.Finalization.Randomness
}
}
return nil
}
func (cc *compactionChain) processBlockRandomnessResult(
rand *types.BlockRandomnessResult) error {
ok, err := cc.verifyRandomness(
rand.BlockHash, rand.Position.Round, rand.Randomness)
if err != nil {
return err
}
if !ok {
return ErrIncorrectBlockRandomnessResult
}
cc.lock.Lock()
defer cc.lock.Unlock()
if !cc.blockRegisteredNoLock(rand.BlockHash) {
cc.purgePending()
cc.pendingRandomness[rand.BlockHash] = pendingRandomnessResult{
receivedTime: time.Now(),
randResult: rand,
}
return ErrBlockNotRegistered
}
cc.blockRandomness[rand.BlockHash] = rand.Randomness
return nil
}
func (cc *compactionChain) purgePending() {
now := time.Now()
for key, rand := range cc.pendingRandomness {
if now.After(rand.receivedTime.Add(maxPendingPeriod)) {
delete(cc.pendingRandomness, key)
}
}
}
// lastDeliveredBlock returns the last delivered block, or the one used to
// initialize this module.
func (cc *compactionChain) lastDeliveredBlock() *types.Block {
cc.lock.RLock()
defer cc.lock.RUnlock()
return cc.prevBlock
}
// lastPendingBlock returns the last pending block.
func (cc *compactionChain) lastPendingBlock() *types.Block {
cc.lock.RLock()
defer cc.lock.RUnlock()
if len(cc.pendingBlocks) > 0 {
return cc.pendingBlocks[0]
}
return nil
}
