sync: fix some sync issues caused by prune-block.

core/blockchain_reader.go

@@ -511,3 +511,12 @@ func (bc *BlockChain) SubscribeBlockProcessingEvent(ch chan<- bool) event.Subscr
 func (bc *BlockChain) SubscribeFinalizedHeaderEvent(ch chan<- FinalizedHeaderEvent) event.Subscription {
 	return bc.scope.Track(bc.finalizedHeaderFeed.Subscribe(ch))
 }
+
+// AncientTail retrieves the tail the ancients blocks
+func (bc *BlockChain) AncientTail() (uint64, error) {
+	tail, err := bc.db.Tail()
+	if err != nil {
+		return 0, err
+	}
+	return tail, nil
+}

core/rawdb/freezer.go

@@ -239,7 +239,7 @@ func (f *Freezer) Ancient(kind string, number uint64) ([]byte, error) {
 //   - if maxBytes is not specified, 'count' items will be returned if they are present.
 func (f *Freezer) AncientRange(kind string, start, count, maxBytes uint64) ([][]byte, error) {
 	if table := f.tables[kind]; table != nil {
-		return table.RetrieveItems(start, count, maxBytes)
+		return table.RetrieveItems(start-f.offset, count, maxBytes)
 	}
 	return nil, errUnknownTable
 }
@@ -252,7 +252,7 @@ func (f *Freezer) Ancients() (uint64, error) {
 func (f *Freezer) TableAncients(kind string) (uint64, error) {
 	f.writeLock.RLock()
 	defer f.writeLock.RUnlock()
-	return f.tables[kind].items.Load(), nil
+	return f.tables[kind].items.Load() + f.offset, nil
 }
 
 // ItemAmountInAncient returns the actual length of current ancientDB.

eth/downloader/downloader.go

@@ -209,6 +209,9 @@ type BlockChain interface {
 
 	// UpdateChasingHead update remote best chain head, used by DA check now.
 	UpdateChasingHead(head *types.Header)
+
+	// AncientTail retrieves the tail the ancients blocks
+	AncientTail() (uint64, error)
 }
 
 type DownloadOption func(downloader *Downloader) *Downloader
@@ -797,6 +800,11 @@ func (d *Downloader) findAncestor(p *peerConnection, localHeight uint64, remoteH
 		// We're above the max reorg threshold, find the earliest fork point
 		floor = int64(localHeight - maxForkAncestry)
 	}
+	// if we have pruned too much history, reset the floor
+	if tail, err := d.blockchain.AncientTail(); err == nil && tail > uint64(floor) {
+		floor = int64(tail)
+	}
+
 	// If we're doing a light sync, ensure the floor doesn't go below the CHT, as
 	// all headers before that point will be missing.
 	if mode == LightSync {