From 049f5b357200406c01f7bf2d2e2936d1d28a319b Mon Sep 17 00:00:00 2001
From: Felföldi Zsolt <zsfelfoldi@gmail.com>
Date: Tue, 12 Jun 2018 15:52:54 +0200
Subject: core, eth, les: more efficient hash-based header chain retrieval
 (#16946)

---
 les/handler.go | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

(limited to 'les')

diff --git a/les/handler.go b/les/handler.go
index 38f810d72..a1c16cb87 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -83,7 +83,7 @@ type BlockChain interface {
 	InsertHeaderChain(chain []*types.Header, checkFreq int) (int, error)
 	Rollback(chain []common.Hash)
 	GetHeaderByNumber(number uint64) *types.Header
-	GetBlockHashesFromHash(hash common.Hash, max uint64) []common.Hash
+	GetAncestor(hash common.Hash, number, ancestor uint64, maxNonCanonical *uint64) (common.Hash, uint64)
 	Genesis() *types.Block
 	SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription
 }
@@ -419,6 +419,8 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 		}
 
 		hashMode := query.Origin.Hash != (common.Hash{})
+		first := true
+		maxNonCanonical := uint64(100)
 
 		// Gather headers until the fetch or network limits is reached
 		var (
@@ -430,14 +432,21 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			// Retrieve the next header satisfying the query
 			var origin *types.Header
 			if hashMode {
-				origin = pm.blockchain.GetHeaderByHash(query.Origin.Hash)
+				if first {
+					first = false
+					origin = pm.blockchain.GetHeaderByHash(query.Origin.Hash)
+					if origin != nil {
+						query.Origin.Number = origin.Number.Uint64()
+					}
+				} else {
+					origin = pm.blockchain.GetHeader(query.Origin.Hash, query.Origin.Number)
+				}
 			} else {
 				origin = pm.blockchain.GetHeaderByNumber(query.Origin.Number)
 			}
 			if origin == nil {
 				break
 			}
-			number := origin.Number.Uint64()
 			headers = append(headers, origin)
 			bytes += estHeaderRlpSize
 
@@ -445,14 +454,12 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			switch {
 			case hashMode && query.Reverse:
 				// Hash based traversal towards the genesis block
-				for i := 0; i < int(query.Skip)+1; i++ {
-					if header := pm.blockchain.GetHeader(query.Origin.Hash, number); header != nil {
-						query.Origin.Hash = header.ParentHash
-						number--
-					} else {
-						unknown = true
-						break
-					}
+				ancestor := query.Skip + 1
+				if ancestor == 0 {
+					unknown = true
+				} else {
+					query.Origin.Hash, query.Origin.Number = pm.blockchain.GetAncestor(query.Origin.Hash, query.Origin.Number, ancestor, &maxNonCanonical)
+					unknown = (query.Origin.Hash == common.Hash{})
 				}
 			case hashMode && !query.Reverse:
 				// Hash based traversal towards the leaf block
@@ -466,8 +473,10 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 					unknown = true
 				} else {
 					if header := pm.blockchain.GetHeaderByNumber(next); header != nil {
-						if pm.blockchain.GetBlockHashesFromHash(header.Hash(), query.Skip+1)[query.Skip] == query.Origin.Hash {
-							query.Origin.Hash = header.Hash()
+						nextHash := header.Hash()
+						expOldHash, _ := pm.blockchain.GetAncestor(nextHash, next, query.Skip+1, &maxNonCanonical)
+						if expOldHash == query.Origin.Hash {
+							query.Origin.Hash, query.Origin.Number = nextHash, next
 						} else {
 							unknown = true
 						}
-- 
cgit