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dagsync.go
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dagsync.go
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package meerdag
import (
"container/list"
"github.com/Qitmeer/qng/common/hash"
"sync"
)
// This parameter can be set according to the size of TCP package(1500) to ensure the transmission stability of the network
const MaxMainLocatorNum = 32
// Synchronization mode
type SyncMode byte
const (
DirectMode SyncMode = 0
SubDAGMode SyncMode = 1
)
type DAGSync struct {
bd *MeerDAG
// The following fields are used to track the graph state being synced to from
// peers.
gsMtx sync.Mutex
gs *GraphState
}
// CalcSyncBlocks
func (ds *DAGSync) CalcSyncBlocks(gs *GraphState, locator []*hash.Hash, mode SyncMode, maxHashes uint) ([]*hash.Hash, *hash.Hash) {
ds.bd.stateLock.Lock()
defer ds.bd.stateLock.Unlock()
if mode == DirectMode {
result := []*hash.Hash{}
if len(locator) == 0 {
return result, nil
}
return ds.bd.sortBlock(locator), nil
}
var point IBlock
for i := len(locator) - 1; i >= 0; i-- {
mainBlock := ds.bd.getBlock(locator[i])
if mainBlock == nil {
continue
}
if !ds.bd.isOnMainChain(mainBlock.GetID()) {
continue
}
point = mainBlock
break
}
if point == nil && len(locator) > 0 {
point = ds.bd.getBlock(locator[0])
if point != nil {
for !ds.bd.isOnMainChain(point.GetID()) {
if point.GetMainParent() == MaxId {
break
}
point = ds.bd.getBlockById(point.GetMainParent())
if point == nil {
break
}
}
}
}
if point == nil {
point = ds.bd.getGenesis()
}
//
isSubDAG := false
for _, k := range gs.tips {
gst := ds.bd.getBlock(&k)
if gst == nil || !gst.IsOrdered() {
continue
}
isSubDAG = true
break
}
if isSubDAG {
return ds.bd.locateBlocks(gs, maxHashes), point.GetHash()
}
return ds.getBlockChainFromMain(point, maxHashes), point.GetHash()
}
// GetMainLocator
func (ds *DAGSync) GetMainLocator(point *hash.Hash) []*hash.Hash {
ds.bd.stateLock.Lock()
defer ds.bd.stateLock.Unlock()
var endBlock IBlock
if point != nil {
endBlock = ds.bd.getBlock(point)
}
if endBlock != nil {
for !ds.bd.isOnMainChain(endBlock.GetID()) {
if endBlock.GetMainParent() == MaxId {
break
}
endBlock = ds.bd.getBlockById(endBlock.GetMainParent())
if endBlock == nil {
break
}
}
}
if endBlock == nil {
endBlock = ds.bd.getGenesis()
}
startBlock := ds.bd.getMainChainTip()
locator := list.New()
cur := startBlock
const DefaultMainLocatorNum = 10
for i := 0; i < DefaultMainLocatorNum; i++ {
if cur.GetID() == 0 ||
cur.GetMainParent() == MaxId ||
cur.GetID() <= endBlock.GetID() {
break
}
locator.PushFront(cur.GetHash())
cur = ds.bd.getBlockById(cur.GetMainParent())
if cur == nil {
break
}
}
if cur.GetID() > endBlock.GetID() {
halfStart := cur.GetID()
halfEnd := endBlock.GetID()
hlocator := []*hash.Hash{}
for locator.Len()+len(hlocator)+1 < MaxMainLocatorNum {
//for {
nextID := (halfStart - halfEnd) / 2
if nextID <= 0 {
break
}
nextID += halfEnd
if nextID == halfStart ||
nextID == halfEnd {
break
}
if !ds.bd.isOnMainChain(nextID) {
halfEnd++
continue
}
ib := ds.bd.getBlockById(nextID)
if ib == nil {
halfEnd++
continue
}
hlocator = append(hlocator, ib.GetHash())
halfEnd = nextID
}
if len(hlocator) > 0 {
for i := len(hlocator) - 1; i >= 0; i-- {
locator.PushFront(hlocator[i])
}
}
}
result := []*hash.Hash{endBlock.GetHash()}
for i := locator.Front(); i != nil; i = i.Next() {
result = append(result, i.Value.(*hash.Hash))
}
return result
}
func (ds *DAGSync) getBlockChainFromMain(point IBlock, maxHashes uint) []*hash.Hash {
mainTip := ds.bd.getMainChainTip()
result := []*hash.Hash{}
for i := point.GetOrder() + 1; i <= mainTip.GetOrder(); i++ {
block := ds.bd.getBlockByOrder(i)
if block == nil {
continue
}
result = append(result, block.GetHash())
if uint(len(result)) >= maxHashes {
break
}
}
return result
}
func (ds *DAGSync) SetGraphState(gs *GraphState) {
ds.gsMtx.Lock()
defer ds.gsMtx.Unlock()
ds.gs = gs
}
// NewDAGSync
func NewDAGSync(bd *MeerDAG) *DAGSync {
return &DAGSync{bd: bd}
}