core, eth: implement eth/65 transaction fetcher

core/tx_pool.go

@@ -864,6 +864,12 @@ func (pool *TxPool) Get(hash common.Hash) *types.Transaction {
 	return pool.all.Get(hash)
 }
 
+// Has returns an indicator whether txpool has a transaction cached with the
+// given hash.
+func (pool *TxPool) Has(hash common.Hash) bool {
+	return pool.all.Get(hash) != nil
+}
+
 // removeTx removes a single transaction from the queue, moving all subsequent
 // transactions back to the future queue.
 func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {

eth/downloader/peer.go

@@ -470,7 +470,7 @@ func (ps *peerSet) HeaderIdlePeers() ([]*peerConnection, int) {
 		defer p.lock.RUnlock()
 		return p.headerThroughput
 	}
-	return ps.idlePeers(62, 64, idle, throughput)
+	return ps.idlePeers(62, 65, idle, throughput)
 }
 
 // BodyIdlePeers retrieves a flat list of all the currently body-idle peers within
@@ -484,7 +484,7 @@ func (ps *peerSet) BodyIdlePeers() ([]*peerConnection, int) {
 		defer p.lock.RUnlock()
 		return p.blockThroughput
 	}
-	return ps.idlePeers(62, 64, idle, throughput)
+	return ps.idlePeers(62, 65, idle, throughput)
 }
 
 // ReceiptIdlePeers retrieves a flat list of all the currently receipt-idle peers
@@ -498,7 +498,7 @@ func (ps *peerSet) ReceiptIdlePeers() ([]*peerConnection, int) {
 		defer p.lock.RUnlock()
 		return p.receiptThroughput
 	}
-	return ps.idlePeers(63, 64, idle, throughput)
+	return ps.idlePeers(63, 65, idle, throughput)
 }
 
 // NodeDataIdlePeers retrieves a flat list of all the currently node-data-idle
@@ -512,7 +512,7 @@ func (ps *peerSet) NodeDataIdlePeers() ([]*peerConnection, int) {
 		defer p.lock.RUnlock()
 		return p.stateThroughput
 	}
-	return ps.idlePeers(63, 64, idle, throughput)
+	return ps.idlePeers(63, 65, idle, throughput)
 }
 
 // idlePeers retrieves a flat list of all currently idle peers satisfying the

eth/fetcher/block_fetcher.go

@@ -14,7 +14,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
-// Package fetcher contains the block announcement based synchronisation.
+// Package fetcher contains the announcement based blocks or transaction synchronisation.
 package fetcher
 
 import (
@@ -30,13 +30,16 @@ import (
 )
 
 const (
-	arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitly requested
+	arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block/transaction is explicitly requested
 	gatherSlack   = 100 * time.Millisecond // Interval used to collate almost-expired announces with fetches
-	fetchTimeout  = 5 * time.Second        // Maximum allotted time to return an explicitly requested block
+	fetchTimeout  = 5 * time.Second        // Maximum allotted time to return an explicitly requested block/transaction
-	maxUncleDist  = 7                      // Maximum allowed backward distance from the chain head
+)
-	maxQueueDist  = 32                     // Maximum allowed distance from the chain head to queue
+
-	hashLimit     = 256                    // Maximum number of unique blocks a peer may have announced
+const (
-	blockLimit    = 64                     // Maximum number of unique blocks a peer may have delivered
+	maxUncleDist = 7   // Maximum allowed backward distance from the chain head
+	maxQueueDist = 32  // Maximum allowed distance from the chain head to queue
+	hashLimit    = 256 // Maximum number of unique blocks a peer may have announced
+	blockLimit   = 64  // Maximum number of unique blocks a peer may have delivered
 )
 
 var (
@@ -67,9 +70,9 @@ type chainInsertFn func(types.Blocks) (int, error)
 // peerDropFn is a callback type for dropping a peer detected as malicious.
 type peerDropFn func(id string)
 
-// announce is the hash notification of the availability of a new block in the
+// blockAnnounce is the hash notification of the availability of a new block in the
 // network.
-type announce struct {
+type blockAnnounce struct {
 	hash   common.Hash   // Hash of the block being announced
 	number uint64        // Number of the block being announced (0 = unknown | old protocol)
 	header *types.Header // Header of the block partially reassembled (new protocol)
@@ -97,18 +100,18 @@ type bodyFilterTask struct {
 	time         time.Time              // Arrival time of the blocks' contents
 }
 
-// inject represents a schedules import operation.
+// blockInject represents a schedules import operation.
-type inject struct {
+type blockInject struct {
 	origin string
 	block  *types.Block
 }
 
-// Fetcher is responsible for accumulating block announcements from various peers
+// BlockFetcher is responsible for accumulating block announcements from various peers
 // and scheduling them for retrieval.
-type Fetcher struct {
+type BlockFetcher struct {
 	// Various event channels
-	notify chan *announce
+	notify chan *blockAnnounce
-	inject chan *inject
+	inject chan *blockInject
 
 	headerFilter chan chan *headerFilterTask
 	bodyFilter   chan chan *bodyFilterTask
@@ -117,16 +120,16 @@ type Fetcher struct {
 	quit chan struct{}
 
 	// Announce states
-	announces  map[string]int              // Per peer announce counts to prevent memory exhaustion
+	announces  map[string]int                   // Per peer blockAnnounce counts to prevent memory exhaustion
-	announced  map[common.Hash][]*announce // Announced blocks, scheduled for fetching
+	announced  map[common.Hash][]*blockAnnounce // Announced blocks, scheduled for fetching
-	fetching   map[common.Hash]*announce   // Announced blocks, currently fetching
+	fetching   map[common.Hash]*blockAnnounce   // Announced blocks, currently fetching
-	fetched    map[common.Hash][]*announce // Blocks with headers fetched, scheduled for body retrieval
+	fetched    map[common.Hash][]*blockAnnounce // Blocks with headers fetched, scheduled for body retrieval
-	completing map[common.Hash]*announce   // Blocks with headers, currently body-completing
+	completing map[common.Hash]*blockAnnounce   // Blocks with headers, currently body-completing
 
 	// Block cache
-	queue  *prque.Prque            // Queue containing the import operations (block number sorted)
+	queue  *prque.Prque                 // Queue containing the import operations (block number sorted)
-	queues map[string]int          // Per peer block counts to prevent memory exhaustion
+	queues map[string]int               // Per peer block counts to prevent memory exhaustion
-	queued map[common.Hash]*inject // Set of already queued blocks (to dedupe imports)
+	queued map[common.Hash]*blockInject // Set of already queued blocks (to dedupe imports)
 
 	// Callbacks
 	getBlock       blockRetrievalFn   // Retrieves a block from the local chain
@@ -137,30 +140,30 @@ type Fetcher struct {
 	dropPeer       peerDropFn         // Drops a peer for misbehaving
 
 	// Testing hooks
-	announceChangeHook func(common.Hash, bool) // Method to call upon adding or deleting a hash from the announce list
+	announceChangeHook func(common.Hash, bool) // Method to call upon adding or deleting a hash from the blockAnnounce list
 	queueChangeHook    func(common.Hash, bool) // Method to call upon adding or deleting a block from the import queue
 	fetchingHook       func([]common.Hash)     // Method to call upon starting a block (eth/61) or header (eth/62) fetch
 	completingHook     func([]common.Hash)     // Method to call upon starting a block body fetch (eth/62)
 	importedHook       func(*types.Block)      // Method to call upon successful block import (both eth/61 and eth/62)
 }
 
-// New creates a block fetcher to retrieve blocks based on hash announcements.
+// NewBlockFetcher creates a block fetcher to retrieve blocks based on hash announcements.
-func New(getBlock blockRetrievalFn, verifyHeader headerVerifierFn, broadcastBlock blockBroadcasterFn, chainHeight chainHeightFn, insertChain chainInsertFn, dropPeer peerDropFn) *Fetcher {
+func NewBlockFetcher(getBlock blockRetrievalFn, verifyHeader headerVerifierFn, broadcastBlock blockBroadcasterFn, chainHeight chainHeightFn, insertChain chainInsertFn, dropPeer peerDropFn) *BlockFetcher {
-	return &Fetcher{
+	return &BlockFetcher{
-		notify:         make(chan *announce),
+		notify:         make(chan *blockAnnounce),
-		inject:         make(chan *inject),
+		inject:         make(chan *blockInject),
 		headerFilter:   make(chan chan *headerFilterTask),
 		bodyFilter:     make(chan chan *bodyFilterTask),
 		done:           make(chan common.Hash),
 		quit:           make(chan struct{}),
 		announces:      make(map[string]int),
-		announced:      make(map[common.Hash][]*announce),
+		announced:      make(map[common.Hash][]*blockAnnounce),
-		fetching:       make(map[common.Hash]*announce),
+		fetching:       make(map[common.Hash]*blockAnnounce),
-		fetched:        make(map[common.Hash][]*announce),
+		fetched:        make(map[common.Hash][]*blockAnnounce),
-		completing:     make(map[common.Hash]*announce),
+		completing:     make(map[common.Hash]*blockAnnounce),
 		queue:          prque.New(nil),
 		queues:         make(map[string]int),
-		queued:         make(map[common.Hash]*inject),
+		queued:         make(map[common.Hash]*blockInject),
 		getBlock:       getBlock,
 		verifyHeader:   verifyHeader,
 		broadcastBlock: broadcastBlock,
@@ -172,21 +175,21 @@ func New(getBlock blockRetrievalFn, verifyHeader headerVerifierFn, broadcastBloc
 
 // Start boots up the announcement based synchroniser, accepting and processing
 // hash notifications and block fetches until termination requested.
-func (f *Fetcher) Start() {
+func (f *BlockFetcher) Start() {
 	go f.loop()
 }
 
 // Stop terminates the announcement based synchroniser, canceling all pending
 // operations.
-func (f *Fetcher) Stop() {
+func (f *BlockFetcher) Stop() {
 	close(f.quit)
 }
 
 // Notify announces the fetcher of the potential availability of a new block in
 // the network.
-func (f *Fetcher) Notify(peer string, hash common.Hash, number uint64, time time.Time,
+func (f *BlockFetcher) Notify(peer string, hash common.Hash, number uint64, time time.Time,
 	headerFetcher headerRequesterFn, bodyFetcher bodyRequesterFn) error {
-	block := &announce{
+	block := &blockAnnounce{
 		hash:        hash,
 		number:      number,
 		time:        time,
@@ -203,8 +206,8 @@ func (f *Fetcher) Notify(peer string, hash common.Hash, number uint64, time time
 }
 
 // Enqueue tries to fill gaps the fetcher's future import queue.
-func (f *Fetcher) Enqueue(peer string, block *types.Block) error {
+func (f *BlockFetcher) Enqueue(peer string, block *types.Block) error {
-	op := &inject{
+	op := &blockInject{
 		origin: peer,
 		block:  block,
 	}
@@ -218,7 +221,7 @@ func (f *Fetcher) Enqueue(peer string, block *types.Block) error {
 
 // FilterHeaders extracts all the headers that were explicitly requested by the fetcher,
 // returning those that should be handled differently.
-func (f *Fetcher) FilterHeaders(peer string, headers []*types.Header, time time.Time) []*types.Header {
+func (f *BlockFetcher) FilterHeaders(peer string, headers []*types.Header, time time.Time) []*types.Header {
 	log.Trace("Filtering headers", "peer", peer, "headers", len(headers))
 
 	// Send the filter channel to the fetcher
@@ -246,7 +249,7 @@ func (f *Fetcher) FilterHeaders(peer string, headers []*types.Header, time time.
 
 // FilterBodies extracts all the block bodies that were explicitly requested by
 // the fetcher, returning those that should be handled differently.
-func (f *Fetcher) FilterBodies(peer string, transactions [][]*types.Transaction, uncles [][]*types.Header, time time.Time) ([][]*types.Transaction, [][]*types.Header) {
+func (f *BlockFetcher) FilterBodies(peer string, transactions [][]*types.Transaction, uncles [][]*types.Header, time time.Time) ([][]*types.Transaction, [][]*types.Header) {
 	log.Trace("Filtering bodies", "peer", peer, "txs", len(transactions), "uncles", len(uncles))
 
 	// Send the filter channel to the fetcher
@@ -274,7 +277,7 @@ func (f *Fetcher) FilterBodies(peer string, transactions [][]*types.Transaction,
 
 // Loop is the main fetcher loop, checking and processing various notification
 // events.
-func (f *Fetcher) loop() {
+func (f *BlockFetcher) loop() {
 	// Iterate the block fetching until a quit is requested
 	fetchTimer := time.NewTimer(0)
 	completeTimer := time.NewTimer(0)
@@ -289,7 +292,7 @@ func (f *Fetcher) loop() {
 		// Import any queued blocks that could potentially fit
 		height := f.chainHeight()
 		for !f.queue.Empty() {
-			op := f.queue.PopItem().(*inject)
+			op := f.queue.PopItem().(*blockInject)
 			hash := op.block.Hash()
 			if f.queueChangeHook != nil {
 				f.queueChangeHook(hash, false)
@@ -313,24 +316,24 @@ func (f *Fetcher) loop() {
 		// Wait for an outside event to occur
 		select {
 		case <-f.quit:
-			// Fetcher terminating, abort all operations
+			// BlockFetcher terminating, abort all operations
 			return
 
 		case notification := <-f.notify:
 			// A block was announced, make sure the peer isn't DOSing us
-			propAnnounceInMeter.Mark(1)
+			blockAnnounceInMeter.Mark(1)
 
 			count := f.announces[notification.origin] + 1
 			if count > hashLimit {
 				log.Debug("Peer exceeded outstanding announces", "peer", notification.origin, "limit", hashLimit)
-				propAnnounceDOSMeter.Mark(1)
+				blockAnnounceDOSMeter.Mark(1)
 				break
 			}
 			// If we have a valid block number, check that it's potentially useful
 			if notification.number > 0 {
 				if dist := int64(notification.number) - int64(f.chainHeight()); dist < -maxUncleDist || dist > maxQueueDist {
 					log.Debug("Peer discarded announcement", "peer", notification.origin, "number", notification.number, "hash", notification.hash, "distance", dist)
-					propAnnounceDropMeter.Mark(1)
+					blockAnnounceDropMeter.Mark(1)
 					break
 				}
 			}
@@ -352,7 +355,7 @@ func (f *Fetcher) loop() {
 
 		case op := <-f.inject:
 			// A direct block insertion was requested, try and fill any pending gaps
-			propBroadcastInMeter.Mark(1)
+			blockBroadcastInMeter.Mark(1)
 			f.enqueue(op.origin, op.block)
 
 		case hash := <-f.done:
@@ -439,7 +442,7 @@ func (f *Fetcher) loop() {
 
 			// Split the batch of headers into unknown ones (to return to the caller),
 			// known incomplete ones (requiring body retrievals) and completed blocks.
-			unknown, incomplete, complete := []*types.Header{}, []*announce{}, []*types.Block{}
+			unknown, incomplete, complete := []*types.Header{}, []*blockAnnounce{}, []*types.Block{}
 			for _, header := range task.headers {
 				hash := header.Hash()
 
@@ -475,7 +478,7 @@ func (f *Fetcher) loop() {
 						f.forgetHash(hash)
 					}
 				} else {
-					// Fetcher doesn't know about it, add to the return list
+					// BlockFetcher doesn't know about it, add to the return list
 					unknown = append(unknown, header)
 				}
 			}
@@ -562,8 +565,8 @@ func (f *Fetcher) loop() {
 	}
 }
 
-// rescheduleFetch resets the specified fetch timer to the next announce timeout.
+// rescheduleFetch resets the specified fetch timer to the next blockAnnounce timeout.
-func (f *Fetcher) rescheduleFetch(fetch *time.Timer) {
+func (f *BlockFetcher) rescheduleFetch(fetch *time.Timer) {
 	// Short circuit if no blocks are announced
 	if len(f.announced) == 0 {
 		return
@@ -579,7 +582,7 @@ func (f *Fetcher) rescheduleFetch(fetch *time.Timer) {
 }
 
 // rescheduleComplete resets the specified completion timer to the next fetch timeout.
-func (f *Fetcher) rescheduleComplete(complete *time.Timer) {
+func (f *BlockFetcher) rescheduleComplete(complete *time.Timer) {
 	// Short circuit if no headers are fetched
 	if len(f.fetched) == 0 {
 		return
@@ -596,27 +599,27 @@ func (f *Fetcher) rescheduleComplete(complete *time.Timer) {
 
 // enqueue schedules a new future import operation, if the block to be imported
 // has not yet been seen.
-func (f *Fetcher) enqueue(peer string, block *types.Block) {
+func (f *BlockFetcher) enqueue(peer string, block *types.Block) {
 	hash := block.Hash()
 
 	// Ensure the peer isn't DOSing us
 	count := f.queues[peer] + 1
 	if count > blockLimit {
 		log.Debug("Discarded propagated block, exceeded allowance", "peer", peer, "number", block.Number(), "hash", hash, "limit", blockLimit)
-		propBroadcastDOSMeter.Mark(1)
+		blockBroadcastDOSMeter.Mark(1)
 		f.forgetHash(hash)
 		return
 	}
 	// Discard any past or too distant blocks
 	if dist := int64(block.NumberU64()) - int64(f.chainHeight()); dist < -maxUncleDist || dist > maxQueueDist {
 		log.Debug("Discarded propagated block, too far away", "peer", peer, "number", block.Number(), "hash", hash, "distance", dist)
-		propBroadcastDropMeter.Mark(1)
+		blockBroadcastDropMeter.Mark(1)
 		f.forgetHash(hash)
 		return
 	}
 	// Schedule the block for future importing
 	if _, ok := f.queued[hash]; !ok {
-		op := &inject{
+		op := &blockInject{
 			origin: peer,
 			block:  block,
 		}
@@ -633,7 +636,7 @@ func (f *Fetcher) enqueue(peer string, block *types.Block) {
 // insert spawns a new goroutine to run a block insertion into the chain. If the
 // block's number is at the same height as the current import phase, it updates
 // the phase states accordingly.
-func (f *Fetcher) insert(peer string, block *types.Block) {
+func (f *BlockFetcher) insert(peer string, block *types.Block) {
 	hash := block.Hash()
 
 	// Run the import on a new thread
@@ -651,7 +654,7 @@ func (f *Fetcher) insert(peer string, block *types.Block) {
 		switch err := f.verifyHeader(block.Header()); err {
 		case nil:
 			// All ok, quickly propagate to our peers
-			propBroadcastOutTimer.UpdateSince(block.ReceivedAt)
+			blockBroadcastOutTimer.UpdateSince(block.ReceivedAt)
 			go f.broadcastBlock(block, true)
 
 		case consensus.ErrFutureBlock:
@@ -669,7 +672,7 @@ func (f *Fetcher) insert(peer string, block *types.Block) {
 			return
 		}
 		// If import succeeded, broadcast the block
-		propAnnounceOutTimer.UpdateSince(block.ReceivedAt)
+		blockAnnounceOutTimer.UpdateSince(block.ReceivedAt)
 		go f.broadcastBlock(block, false)
 
 		// Invoke the testing hook if needed
@@ -681,7 +684,7 @@ func (f *Fetcher) insert(peer string, block *types.Block) {
 
 // forgetHash removes all traces of a block announcement from the fetcher's
 // internal state.
-func (f *Fetcher) forgetHash(hash common.Hash) {
+func (f *BlockFetcher) forgetHash(hash common.Hash) {
 	// Remove all pending announces and decrement DOS counters
 	for _, announce := range f.announced[hash] {
 		f.announces[announce.origin]--
@@ -723,7 +726,7 @@ func (f *Fetcher) forgetHash(hash common.Hash) {
 
 // forgetBlock removes all traces of a queued block from the fetcher's internal
 // state.
-func (f *Fetcher) forgetBlock(hash common.Hash) {
+func (f *BlockFetcher) forgetBlock(hash common.Hash) {
 	if insert := f.queued[hash]; insert != nil {
 		f.queues[insert.origin]--
 		if f.queues[insert.origin] == 0 {

eth/fetcher/block_fetcher_test.go

@@ -76,7 +76,7 @@ func makeChain(n int, seed byte, parent *types.Block) ([]common.Hash, map[common
 
 // fetcherTester is a test simulator for mocking out local block chain.
 type fetcherTester struct {
-	fetcher *Fetcher
+	fetcher *BlockFetcher
 
 	hashes []common.Hash                // Hash chain belonging to the tester
 	blocks map[common.Hash]*types.Block // Blocks belonging to the tester
@@ -92,7 +92,7 @@ func newTester() *fetcherTester {
 		blocks: map[common.Hash]*types.Block{genesis.Hash(): genesis},
 		drops:  make(map[string]bool),
 	}
-	tester.fetcher = New(tester.getBlock, tester.verifyHeader, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
+	tester.fetcher = NewBlockFetcher(tester.getBlock, tester.verifyHeader, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
 	tester.fetcher.Start()
 
 	return tester

eth/fetcher/metrics.go

@@ -23,15 +23,15 @@ import (
 )
 
 var (
-	propAnnounceInMeter   = metrics.NewRegisteredMeter("eth/fetcher/prop/announces/in", nil)
+	blockAnnounceInMeter   = metrics.NewRegisteredMeter("eth/fetcher/prop/block/announces/in", nil)
-	propAnnounceOutTimer  = metrics.NewRegisteredTimer("eth/fetcher/prop/announces/out", nil)
+	blockAnnounceOutTimer  = metrics.NewRegisteredTimer("eth/fetcher/prop/block/announces/out", nil)
-	propAnnounceDropMeter = metrics.NewRegisteredMeter("eth/fetcher/prop/announces/drop", nil)
+	blockAnnounceDropMeter = metrics.NewRegisteredMeter("eth/fetcher/prop/block/announces/drop", nil)
-	propAnnounceDOSMeter  = metrics.NewRegisteredMeter("eth/fetcher/prop/announces/dos", nil)
+	blockAnnounceDOSMeter  = metrics.NewRegisteredMeter("eth/fetcher/prop/block/announces/dos", nil)
 
-	propBroadcastInMeter   = metrics.NewRegisteredMeter("eth/fetcher/prop/broadcasts/in", nil)
+	blockBroadcastInMeter   = metrics.NewRegisteredMeter("eth/fetcher/prop/block/broadcasts/in", nil)
-	propBroadcastOutTimer  = metrics.NewRegisteredTimer("eth/fetcher/prop/broadcasts/out", nil)
+	blockBroadcastOutTimer  = metrics.NewRegisteredTimer("eth/fetcher/prop/block/broadcasts/out", nil)
-	propBroadcastDropMeter = metrics.NewRegisteredMeter("eth/fetcher/prop/broadcasts/drop", nil)
+	blockBroadcastDropMeter = metrics.NewRegisteredMeter("eth/fetcher/prop/block/broadcasts/drop", nil)
-	propBroadcastDOSMeter  = metrics.NewRegisteredMeter("eth/fetcher/prop/broadcasts/dos", nil)
+	blockBroadcastDOSMeter  = metrics.NewRegisteredMeter("eth/fetcher/prop/block/broadcasts/dos", nil)
 
 	headerFetchMeter = metrics.NewRegisteredMeter("eth/fetcher/fetch/headers", nil)
 	bodyFetchMeter   = metrics.NewRegisteredMeter("eth/fetcher/fetch/bodies", nil)
@@ -40,4 +40,15 @@ var (
 	headerFilterOutMeter = metrics.NewRegisteredMeter("eth/fetcher/filter/headers/out", nil)
 	bodyFilterInMeter    = metrics.NewRegisteredMeter("eth/fetcher/filter/bodies/in", nil)
 	bodyFilterOutMeter   = metrics.NewRegisteredMeter("eth/fetcher/filter/bodies/out", nil)
+
+	txAnnounceInMeter         = metrics.NewRegisteredMeter("eth/fetcher/prop/transaction/announces/in", nil)
+	txAnnounceDOSMeter        = metrics.NewRegisteredMeter("eth/fetcher/prop/transaction/announces/dos", nil)
+	txAnnounceSkipMeter       = metrics.NewRegisteredMeter("eth/fetcher/prop/transaction/announces/skip", nil)
+	txAnnounceUnderpriceMeter = metrics.NewRegisteredMeter("eth/fetcher/prop/transaction/announces/underprice", nil)
+	txBroadcastInMeter        = metrics.NewRegisteredMeter("eth/fetcher/prop/transaction/broadcasts/in", nil)
+	txFetchOutMeter           = metrics.NewRegisteredMeter("eth/fetcher/fetch/transaction/out", nil)
+	txFetchSuccessMeter       = metrics.NewRegisteredMeter("eth/fetcher/fetch/transaction/success", nil)
+	txFetchTimeoutMeter       = metrics.NewRegisteredMeter("eth/fetcher/fetch/transaction/timeout", nil)
+	txFetchInvalidMeter       = metrics.NewRegisteredMeter("eth/fetcher/fetch/transaction/invalid", nil)
+	txFetchDurationTimer      = metrics.NewRegisteredTimer("eth/fetcher/fetch/transaction/duration", nil)
 )

eth/fetcher/tx_fetcher.go

@@ -0,0 +1,319 @@
+// Copyright 2020 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package fetcher
+
+import (
+	"math/rand"
+	"time"
+
+	mapset "github.com/deckarep/golang-set"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+var (
+	// txAnnounceLimit is the maximum number of unique transaction a peer
+	// can announce in a short time.
+	txAnnounceLimit = 4096
+
+	// txFetchTimeout is the maximum allotted time to return an explicitly
+	// requested transaction.
+	txFetchTimeout = 5 * time.Second
+
+	// MaxTransactionFetch is the maximum transaction number can be fetched
+	// in one request. The rationale to pick this value is:
+	// In eth protocol, the softResponseLimit is 2MB. Nowdays according to
+	// Etherscan the average transaction size is around 200B, so in theory
+	// we can include lots of transaction in a single protocol packet. However
+	// the maximum size of a single transaction is raised to 128KB, so pick
+	// a middle value here to ensure we can maximize the efficiency of the
+	// retrieval and response size overflow won't happen in most cases.
+	MaxTransactionFetch = 256
+
+	// underpriceSetSize is the size of underprice set which used for maintaining
+	// the set of underprice transactions.
+	underpriceSetSize = 4096
+)
+
+// txAnnounce is the notification of the availability of a single
+// new transaction in the network.
+type txAnnounce struct {
+	origin   string              // Identifier of the peer originating the notification
+	time     time.Time           // Timestamp of the announcement
+	fetchTxs func([]common.Hash) // Callback for retrieving transaction from specified peer
+}
+
+// txsAnnounce is the notification of the availability of a batch
+// of new transactions in the network.
+type txsAnnounce struct {
+	hashes   []common.Hash       // Batch of transaction hashes being announced
+	origin   string              // Identifier of the peer originating the notification
+	time     time.Time           // Timestamp of the announcement
+	fetchTxs func([]common.Hash) // Callback for retrieving transaction from specified peer
+}
+
+// TxFetcher is responsible for retrieving new transaction based
+// on the announcement.
+type TxFetcher struct {
+	notify  chan *txsAnnounce
+	cleanup chan []common.Hash
+	quit    chan struct{}
+
+	// Announce states
+	announces   map[string]int                // Per peer transaction announce counts to prevent memory exhaustion
+	announced   map[common.Hash][]*txAnnounce // Announced transactions, scheduled for fetching
+	fetching    map[common.Hash]*txAnnounce   // Announced transactions, currently fetching
+	underpriced mapset.Set                    // Transaction set whose price is too low for accepting
+
+	// Callbacks
+	hasTx    func(common.Hash) bool             // Retrieves a tx from the local txpool
+	addTxs   func([]*types.Transaction) []error // Insert a batch of transactions into local txpool
+	dropPeer func(string)                       // Drop the specified peer
+
+	// Hooks
+	announceHook     func([]common.Hash)        // Hook which is called when a batch transactions are announced
+	importTxsHook    func([]*types.Transaction) // Hook which is called when a batch of transactions are imported.
+	dropHook         func(string)               // Hook which is called when a peer is dropped
+	cleanupHook      func([]common.Hash)        // Hook which is called when internal status is cleaned
+	rejectUnderprice func(common.Hash)          // Hook which is called when underprice transaction is rejected
+}
+
+// NewTxFetcher creates a transaction fetcher to retrieve transaction
+// based on hash announcements.
+func NewTxFetcher(hasTx func(common.Hash) bool, addTxs func([]*types.Transaction) []error, dropPeer func(string)) *TxFetcher {
+	return &TxFetcher{
+		notify:      make(chan *txsAnnounce),
+		cleanup:     make(chan []common.Hash),
+		quit:        make(chan struct{}),
+		announces:   make(map[string]int),
+		announced:   make(map[common.Hash][]*txAnnounce),
+		fetching:    make(map[common.Hash]*txAnnounce),
+		underpriced: mapset.NewSet(),
+		hasTx:       hasTx,
+		addTxs:      addTxs,
+		dropPeer:    dropPeer,
+	}
+}
+
+// Notify announces the fetcher of the potential availability of a
+// new transaction in the network.
+func (f *TxFetcher) Notify(peer string, hashes []common.Hash, time time.Time, fetchTxs func([]common.Hash)) error {
+	announce := &txsAnnounce{
+		hashes:   hashes,
+		time:     time,
+		origin:   peer,
+		fetchTxs: fetchTxs,
+	}
+	select {
+	case f.notify <- announce:
+		return nil
+	case <-f.quit:
+		return errTerminated
+	}
+}
+
+// EnqueueTxs imports a batch of received transaction into fetcher.
+func (f *TxFetcher) EnqueueTxs(peer string, txs []*types.Transaction) error {
+	var (
+		drop   bool
+		hashes []common.Hash
+	)
+	errs := f.addTxs(txs)
+	for i, err := range errs {
+		if err != nil {
+			// Drop peer if the received transaction isn't signed properly.
+			drop = (drop || err == core.ErrInvalidSender)
+			txFetchInvalidMeter.Mark(1)
+
+			// Track the transaction hash if the price is too low for us.
+			// Avoid re-request this transaction when we receive another
+			// announcement.
+			if err == core.ErrUnderpriced {
+				for f.underpriced.Cardinality() >= underpriceSetSize {
+					f.underpriced.Pop()
+				}
+				f.underpriced.Add(txs[i].Hash())
+			}
+		}
+		hashes = append(hashes, txs[i].Hash())
+	}
+	if f.importTxsHook != nil {
+		f.importTxsHook(txs)
+	}
+	// Drop the peer if some transaction failed signature verification.
+	// We can regard this peer is trying to DOS us by feeding lots of
+	// random hashes.
+	if drop {
+		f.dropPeer(peer)
+		if f.dropHook != nil {
+			f.dropHook(peer)
+		}
+	}
+	select {
+	case f.cleanup <- hashes:
+		return nil
+	case <-f.quit:
+		return errTerminated
+	}
+}
+
+// Start boots up the announcement based synchroniser, accepting and processing
+// hash notifications and block fetches until termination requested.
+func (f *TxFetcher) Start() {
+	go f.loop()
+}
+
+// Stop terminates the announcement based synchroniser, canceling all pending
+// operations.
+func (f *TxFetcher) Stop() {
+	close(f.quit)
+}
+
+func (f *TxFetcher) loop() {
+	fetchTimer := time.NewTimer(0)
+
+	for {
+		// Clean up any expired transaction fetches.
+		// There are many cases can lead to it:
+		// * We send the request to busy peer which can reply immediately
+		// * We send the request to malicious peer which doesn't reply deliberately
+		// * We send the request to normal peer for a batch of transaction, but some
+		//   transactions have been included into blocks. According to EIP these txs
+		//   won't be included.
+		// But it's fine to delete the fetching record and reschedule fetching iff we
+		// receive the annoucement again.
+		for hash, announce := range f.fetching {
+			if time.Since(announce.time) > txFetchTimeout {
+				delete(f.fetching, hash)
+				txFetchTimeoutMeter.Mark(1)
+			}
+		}
+		select {
+		case anno := <-f.notify:
+			txAnnounceInMeter.Mark(int64(len(anno.hashes)))
+
+			// Drop the new announce if there are too many accumulated.
+			count := f.announces[anno.origin] + len(anno.hashes)
+			if count > txAnnounceLimit {
+				txAnnounceDOSMeter.Mark(int64(count - txAnnounceLimit))
+				break
+			}
+			f.announces[anno.origin] = count
+
+			// All is well, schedule the announce if transaction is not yet downloading
+			empty := len(f.announced) == 0
+			for _, hash := range anno.hashes {
+				if _, ok := f.fetching[hash]; ok {
+					continue
+				}
+				if f.underpriced.Contains(hash) {
+					txAnnounceUnderpriceMeter.Mark(1)
+					if f.rejectUnderprice != nil {
+						f.rejectUnderprice(hash)
+					}
+					continue
+				}
+				f.announced[hash] = append(f.announced[hash], &txAnnounce{
+					origin:   anno.origin,
+					time:     anno.time,
+					fetchTxs: anno.fetchTxs,
+				})
+			}
+			if empty && len(f.announced) > 0 {
+				f.reschedule(fetchTimer)
+			}
+			if f.announceHook != nil {
+				f.announceHook(anno.hashes)
+			}
+		case <-fetchTimer.C:
+			// At least one tx's timer ran out, check for needing retrieval
+			request := make(map[string][]common.Hash)
+
+			for hash, announces := range f.announced {
+				if time.Since(announces[0].time) > arriveTimeout-gatherSlack {
+					// Pick a random peer to retrieve from, reset all others
+					announce := announces[rand.Intn(len(announces))]
+					f.forgetHash(hash)
+
+					// Skip fetching if we already receive the transaction.
+					if f.hasTx(hash) {
+						txAnnounceSkipMeter.Mark(1)
+						continue
+					}
+					// If the transaction still didn't arrive, queue for fetching
+					request[announce.origin] = append(request[announce.origin], hash)
+					f.fetching[hash] = announce
+				}
+			}
+			// Send out all block header requests
+			for peer, hashes := range request {
+				log.Trace("Fetching scheduled transactions", "peer", peer, "txs", hashes)
+				fetchTxs := f.fetching[hashes[0]].fetchTxs
+				fetchTxs(hashes)
+				txFetchOutMeter.Mark(int64(len(hashes)))
+			}
+			// Schedule the next fetch if blocks are still pending
+			f.reschedule(fetchTimer)
+		case hashes := <-f.cleanup:
+			for _, hash := range hashes {
+				f.forgetHash(hash)
+				anno, exist := f.fetching[hash]
+				if !exist {
+					txBroadcastInMeter.Mark(1) // Directly transaction propagation
+					continue
+				}
+				txFetchDurationTimer.UpdateSince(anno.time)
+				txFetchSuccessMeter.Mark(1)
+				delete(f.fetching, hash)
+			}
+			if f.cleanupHook != nil {
+				f.cleanupHook(hashes)
+			}
+		case <-f.quit:
+			return
+		}
+	}
+}
+
+// rescheduleFetch resets the specified fetch timer to the next blockAnnounce timeout.
+func (f *TxFetcher) reschedule(fetch *time.Timer) {
+	// Short circuit if no transactions are announced
+	if len(f.announced) == 0 {
+		return
+	}
+	// Otherwise find the earliest expiring announcement
+	earliest := time.Now()
+	for _, announces := range f.announced {
+		if earliest.After(announces[0].time) {
+			earliest = announces[0].time
+		}
+	}
+	fetch.Reset(arriveTimeout - time.Since(earliest))
+}
+
+func (f *TxFetcher) forgetHash(hash common.Hash) {
+	// Remove all pending announces and decrement DOS counters
+	for _, announce := range f.announced[hash] {
+		f.announces[announce.origin]--
+		if f.announces[announce.origin] <= 0 {
+			delete(f.announces, announce.origin)
+		}
+	}
+	delete(f.announced, hash)
+}

eth/fetcher/tx_fetcher_test.go

@@ -0,0 +1,318 @@
+// Copyright 2020 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package fetcher
+
+import (
+	"crypto/ecdsa"
+	"math/big"
+	"math/rand"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+func init() {
+	rand.Seed(int64(time.Now().Nanosecond()))
+
+	txAnnounceLimit = 64
+	MaxTransactionFetch = 16
+}
+
+func makeTransactions(key *ecdsa.PrivateKey, target int) []*types.Transaction {
+	var txs []*types.Transaction
+
+	for i := 0; i < target; i++ {
+		random := rand.Uint32()
+		tx := types.NewTransaction(uint64(random), common.Address{0x1, 0x2, 0x3}, big.NewInt(int64(random)), 100, big.NewInt(int64(random)), nil)
+		tx, _ = types.SignTx(tx, types.NewEIP155Signer(big.NewInt(1)), key)
+		txs = append(txs, tx)
+	}
+	return txs
+}
+
+func makeUnsignedTransactions(key *ecdsa.PrivateKey, target int) []*types.Transaction {
+	var txs []*types.Transaction
+
+	for i := 0; i < target; i++ {
+		random := rand.Uint32()
+		tx := types.NewTransaction(uint64(random), common.Address{0x1, 0x2, 0x3}, big.NewInt(int64(random)), 100, big.NewInt(int64(random)), nil)
+		txs = append(txs, tx)
+	}
+	return txs
+}
+
+type txfetcherTester struct {
+	fetcher *TxFetcher
+
+	priceLimit *big.Int
+	sender     *ecdsa.PrivateKey
+	senderAddr common.Address
+	signer     types.Signer
+	txs        map[common.Hash]*types.Transaction
+	dropped    map[string]struct{}
+	lock       sync.RWMutex
+}
+
+func newTxFetcherTester() *txfetcherTester {
+	key, _ := crypto.GenerateKey()
+	addr := crypto.PubkeyToAddress(key.PublicKey)
+	t := &txfetcherTester{
+		sender:     key,
+		senderAddr: addr,
+		signer:     types.NewEIP155Signer(big.NewInt(1)),
+		txs:        make(map[common.Hash]*types.Transaction),
+		dropped:    make(map[string]struct{}),
+	}
+	t.fetcher = NewTxFetcher(t.hasTx, t.addTxs, t.dropPeer)
+	t.fetcher.Start()
+	return t
+}
+
+func (t *txfetcherTester) hasTx(hash common.Hash) bool {
+	t.lock.RLock()
+	defer t.lock.RUnlock()
+
+	return t.txs[hash] != nil
+}
+
+func (t *txfetcherTester) addTxs(txs []*types.Transaction) []error {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+
+	var errors []error
+	for _, tx := range txs {
+		// Make sure the transaction is signed properly
+		_, err := types.Sender(t.signer, tx)
+		if err != nil {
+			errors = append(errors, core.ErrInvalidSender)
+			continue
+		}
+		// Make sure the price is high enough to accpet
+		if t.priceLimit != nil && tx.GasPrice().Cmp(t.priceLimit) < 0 {
+			errors = append(errors, core.ErrUnderpriced)
+			continue
+		}
+		t.txs[tx.Hash()] = tx
+		errors = append(errors, nil)
+	}
+	return errors
+}
+
+func (t *txfetcherTester) dropPeer(id string) {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+
+	t.dropped[id] = struct{}{}
+}
+
+// makeTxFetcher retrieves a batch of transaction associated with a simulated peer.
+func (t *txfetcherTester) makeTxFetcher(peer string, txs []*types.Transaction) func(hashes []common.Hash) {
+	closure := make(map[common.Hash]*types.Transaction)
+	for _, tx := range txs {
+		closure[tx.Hash()] = tx
+	}
+	return func(hashes []common.Hash) {
+		var txs []*types.Transaction
+		for _, hash := range hashes {
+			tx := closure[hash]
+			if tx == nil {
+				continue
+			}
+			txs = append(txs, tx)
+		}
+		// Return on a new thread
+		go t.fetcher.EnqueueTxs(peer, txs)
+	}
+}
+
+func TestSequentialTxAnnouncements(t *testing.T) {
+	tester := newTxFetcherTester()
+	txs := makeTransactions(tester.sender, txAnnounceLimit)
+
+	retrieveTxs := tester.makeTxFetcher("peer", txs)
+
+	newTxsCh := make(chan struct{})
+	tester.fetcher.importTxsHook = func(transactions []*types.Transaction) {
+		newTxsCh <- struct{}{}
+	}
+	for _, tx := range txs {
+		tester.fetcher.Notify("peer", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout), retrieveTxs)
+		select {
+		case <-newTxsCh:
+		case <-time.NewTimer(time.Second).C:
+			t.Fatalf("timeout")
+		}
+	}
+	if len(tester.txs) != len(txs) {
+		t.Fatalf("Imported transaction number mismatch, want %d, got %d", len(txs), len(tester.txs))
+	}
+}
+
+func TestConcurrentAnnouncements(t *testing.T) {
+	tester := newTxFetcherTester()
+	txs := makeTransactions(tester.sender, txAnnounceLimit)
+
+	txFetcherFn1 := tester.makeTxFetcher("peer1", txs)
+	txFetcherFn2 := tester.makeTxFetcher("peer2", txs)
+
+	var (
+		count uint32
+		done  = make(chan struct{})
+	)
+	tester.fetcher.importTxsHook = func(transactions []*types.Transaction) {
+		atomic.AddUint32(&count, uint32(len(transactions)))
+		if atomic.LoadUint32(&count) >= uint32(txAnnounceLimit) {
+			done <- struct{}{}
+		}
+	}
+	for _, tx := range txs {
+		tester.fetcher.Notify("peer1", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout), txFetcherFn1)
+		tester.fetcher.Notify("peer2", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout+time.Millisecond), txFetcherFn2)
+		tester.fetcher.Notify("peer2", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout-time.Millisecond), txFetcherFn2)
+	}
+	select {
+	case <-done:
+	case <-time.NewTimer(time.Second).C:
+		t.Fatalf("timeout")
+	}
+}
+
+func TestBatchAnnouncements(t *testing.T) {
+	tester := newTxFetcherTester()
+	txs := makeTransactions(tester.sender, txAnnounceLimit)
+
+	retrieveTxs := tester.makeTxFetcher("peer", txs)
+
+	var count uint32
+	var done = make(chan struct{})
+	tester.fetcher.importTxsHook = func(txs []*types.Transaction) {
+		atomic.AddUint32(&count, uint32(len(txs)))
+
+		if atomic.LoadUint32(&count) >= uint32(txAnnounceLimit) {
+			done <- struct{}{}
+		}
+	}
+	// Send all announces which exceeds the limit.
+	var hashes []common.Hash
+	for _, tx := range txs {
+		hashes = append(hashes, tx.Hash())
+	}
+	tester.fetcher.Notify("peer", hashes, time.Now(), retrieveTxs)
+
+	select {
+	case <-done:
+	case <-time.NewTimer(time.Second).C:
+		t.Fatalf("timeout")
+	}
+}
+
+func TestPropagationAfterAnnounce(t *testing.T) {
+	tester := newTxFetcherTester()
+	txs := makeTransactions(tester.sender, txAnnounceLimit)
+
+	var cleaned = make(chan struct{})
+	tester.fetcher.cleanupHook = func(hashes []common.Hash) {
+		cleaned <- struct{}{}
+	}
+	retrieveTxs := tester.makeTxFetcher("peer", txs)
+	for _, tx := range txs {
+		tester.fetcher.Notify("peer", []common.Hash{tx.Hash()}, time.Now(), retrieveTxs)
+		tester.fetcher.EnqueueTxs("peer", []*types.Transaction{tx})
+
+		// It's ok to read the map directly since no write
+		// will happen in the same time.
+		<-cleaned
+		if len(tester.fetcher.announced) != 0 {
+			t.Fatalf("Announcement should be cleaned, got %d", len(tester.fetcher.announced))
+		}
+	}
+}
+
+func TestEnqueueTransactions(t *testing.T) {
+	tester := newTxFetcherTester()
+	txs := makeTransactions(tester.sender, txAnnounceLimit)
+
+	done := make(chan struct{})
+	tester.fetcher.importTxsHook = func(transactions []*types.Transaction) {
+		if len(transactions) == txAnnounceLimit {
+			done <- struct{}{}
+		}
+	}
+	go tester.fetcher.EnqueueTxs("peer", txs)
+	select {
+	case <-done:
+	case <-time.NewTimer(time.Second).C:
+		t.Fatalf("timeout")
+	}
+}
+
+func TestInvalidTxAnnounces(t *testing.T) {
+	tester := newTxFetcherTester()
+
+	var txs []*types.Transaction
+	txs = append(txs, makeUnsignedTransactions(tester.sender, 1)...)
+	txs = append(txs, makeTransactions(tester.sender, 1)...)
+
+	txFetcherFn := tester.makeTxFetcher("peer", txs)
+
+	dropped := make(chan string, 1)
+	tester.fetcher.dropHook = func(s string) { dropped <- s }
+
+	for _, tx := range txs {
+		tester.fetcher.Notify("peer", []common.Hash{tx.Hash()}, time.Now(), txFetcherFn)
+	}
+	select {
+	case s := <-dropped:
+		if s != "peer" {
+			t.Fatalf("invalid dropped peer")
+		}
+	case <-time.NewTimer(time.Second).C:
+		t.Fatalf("timeout")
+	}
+}
+
+func TestRejectUnderpriced(t *testing.T) {
+	tester := newTxFetcherTester()
+	tester.priceLimit = big.NewInt(10000)
+
+	done := make(chan struct{})
+	tester.fetcher.importTxsHook = func([]*types.Transaction) { done <- struct{}{} }
+	reject := make(chan struct{})
+	tester.fetcher.rejectUnderprice = func(common.Hash) { reject <- struct{}{} }
+
+	tx := types.NewTransaction(0, common.Address{0x1, 0x2, 0x3}, big.NewInt(int64(100)), 100, big.NewInt(int64(100)), nil)
+	tx, _ = types.SignTx(tx, types.NewEIP155Signer(big.NewInt(1)), tester.sender)
+	txFetcherFn := tester.makeTxFetcher("peer", []*types.Transaction{tx})
+
+	// Send the announcement first time
+	tester.fetcher.Notify("peer", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout), txFetcherFn)
+	<-done
+
+	// Resend the announcement, shouldn't schedule fetching this time
+	tester.fetcher.Notify("peer", []common.Hash{tx.Hash()}, time.Now().Add(-arriveTimeout), txFetcherFn)
+	select {
+	case <-reject:
+	case <-time.NewTimer(time.Second).C:
+		t.Fatalf("timeout")
+	}
+}

eth/handler.go

@@ -77,9 +77,10 @@ type ProtocolManager struct {
 	blockchain *core.BlockChain
 	maxPeers   int
 
-	downloader *downloader.Downloader
+	downloader   *downloader.Downloader
-	fetcher    *fetcher.Fetcher
+	blockFetcher *fetcher.BlockFetcher
-	peers      *peerSet
+	txFetcher    *fetcher.TxFetcher
+	peers        *peerSet
 
 	eventMux      *event.TypeMux
 	txsCh         chan core.NewTxsEvent
@@ -97,6 +98,9 @@ type ProtocolManager struct {
 	// wait group is used for graceful shutdowns during downloading
 	// and processing
 	wg sync.WaitGroup
+
+	// Test fields or hooks
+	broadcastTxAnnouncesOnly bool // Testing field, disable transaction propagation
 }
 
 // NewProtocolManager returns a new Ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
@@ -187,7 +191,8 @@ func NewProtocolManager(config *params.ChainConfig, checkpoint *params.TrustedCh
 		}
 		return n, err
 	}
-	manager.fetcher = fetcher.New(blockchain.GetBlockByHash, validator, manager.BroadcastBlock, heighter, inserter, manager.removePeer)
+	manager.blockFetcher = fetcher.NewBlockFetcher(blockchain.GetBlockByHash, validator, manager.BroadcastBlock, heighter, inserter, manager.removePeer)
+	manager.txFetcher = fetcher.NewTxFetcher(txpool.Has, txpool.AddRemotes, manager.removePeer)
 
 	return manager, nil
 }
@@ -203,7 +208,7 @@ func (pm *ProtocolManager) makeProtocol(version uint) p2p.Protocol {
 		Version: version,
 		Length:  length,
 		Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
-			peer := pm.newPeer(int(version), p, rw)
+			peer := pm.newPeer(int(version), p, rw, pm.txpool.Get)
 			select {
 			case pm.newPeerCh <- peer:
 				pm.wg.Add(1)
@@ -286,8 +291,8 @@ func (pm *ProtocolManager) Stop() {
 	log.Info("Ethereum protocol stopped")
 }
 
-func (pm *ProtocolManager) newPeer(pv int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
+func (pm *ProtocolManager) newPeer(pv int, p *p2p.Peer, rw p2p.MsgReadWriter, getPooledTx func(hash common.Hash) *types.Transaction) *peer {
-	return newPeer(pv, p, newMeteredMsgWriter(rw))
+	return newPeer(pv, p, newMeteredMsgWriter(rw), getPooledTx)
 }
 
 // handle is the callback invoked to manage the life cycle of an eth peer. When
@@ -514,7 +519,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 				p.Log().Debug("Whitelist block verified", "number", headers[0].Number.Uint64(), "hash", want)
 			}
 			// Irrelevant of the fork checks, send the header to the fetcher just in case
-			headers = pm.fetcher.FilterHeaders(p.id, headers, time.Now())
+			headers = pm.blockFetcher.FilterHeaders(p.id, headers, time.Now())
 		}
 		if len(headers) > 0 || !filter {
 			err := pm.downloader.DeliverHeaders(p.id, headers)
@@ -567,7 +572,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 		// Filter out any explicitly requested bodies, deliver the rest to the downloader
 		filter := len(transactions) > 0 || len(uncles) > 0
 		if filter {
-			transactions, uncles = pm.fetcher.FilterBodies(p.id, transactions, uncles, time.Now())
+			transactions, uncles = pm.blockFetcher.FilterBodies(p.id, transactions, uncles, time.Now())
 		}
 		if len(transactions) > 0 || len(uncles) > 0 || !filter {
 			err := pm.downloader.DeliverBodies(p.id, transactions, uncles)
@@ -678,7 +683,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 		}
 		for _, block := range unknown {
-			pm.fetcher.Notify(p.id, block.Hash, block.Number, time.Now(), p.RequestOneHeader, p.RequestBodies)
+			pm.blockFetcher.Notify(p.id, block.Hash, block.Number, time.Now(), p.RequestOneHeader, p.RequestBodies)
 		}
 
 	case msg.Code == NewBlockMsg:
@@ -703,7 +708,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 
 		// Mark the peer as owning the block and schedule it for import
 		p.MarkBlock(request.Block.Hash())
-		pm.fetcher.Enqueue(p.id, request.Block)
+		pm.blockFetcher.Enqueue(p.id, request.Block)
 
 		// Assuming the block is importable by the peer, but possibly not yet done so,
 		// calculate the head hash and TD that the peer truly must have.
@@ -724,6 +729,66 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 		}
 
+	case msg.Code == NewPooledTransactionHashesMsg && p.version >= eth65:
+		// New transaction announcement arrived, make sure we have
+		// a valid and fresh chain to handle them
+		if atomic.LoadUint32(&pm.acceptTxs) == 0 {
+			break
+		}
+		var hashes []common.Hash
+		if err := msg.Decode(&hashes); err != nil {
+			return errResp(ErrDecode, "msg %v: %v", msg, err)
+		}
+		// Schedule all the unknown hashes for retrieval
+		var unknown []common.Hash
+		for _, hash := range hashes {
+			// Mark the hashes as present at the remote node
+			p.MarkTransaction(hash)
+
+			// Filter duplicated transaction announcement.
+			// Notably we only dedupliate announcement in txpool, check the rationale
+			// behind in EIP https://github.com/ethereum/EIPs/pull/2464.
+			if pm.txpool.Has(hash) {
+				continue
+			}
+			unknown = append(unknown, hash)
+		}
+		pm.txFetcher.Notify(p.id, unknown, time.Now(), p.AsyncRequestTxs)
+
+	case msg.Code == GetPooledTransactionsMsg && p.version >= eth65:
+		// Decode the retrieval message
+		msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
+		if _, err := msgStream.List(); err != nil {
+			return err
+		}
+		// Gather transactions until the fetch or network limits is reached
+		var (
+			hash  common.Hash
+			bytes int
+			txs   []rlp.RawValue
+		)
+		for bytes < softResponseLimit {
+			// Retrieve the hash of the next block
+			if err := msgStream.Decode(&hash); err == rlp.EOL {
+				break
+			} else if err != nil {
+				return errResp(ErrDecode, "msg %v: %v", msg, err)
+			}
+			// Retrieve the requested transaction, skipping if unknown to us
+			tx := pm.txpool.Get(hash)
+			if tx == nil {
+				continue
+			}
+			// If known, encode and queue for response packet
+			if encoded, err := rlp.EncodeToBytes(tx); err != nil {
+				log.Error("Failed to encode transaction", "err", err)
+			} else {
+				txs = append(txs, encoded)
+				bytes += len(encoded)
+			}
+		}
+		return p.SendTransactionRLP(txs)
+
 	case msg.Code == TxMsg:
 		// Transactions arrived, make sure we have a valid and fresh chain to handle them
 		if atomic.LoadUint32(&pm.acceptTxs) == 0 {
@@ -741,7 +806,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 			p.MarkTransaction(tx.Hash())
 		}
-		pm.txpool.AddRemotes(txs)
+		pm.txFetcher.EnqueueTxs(p.id, txs)
 
 	default:
 		return errResp(ErrInvalidMsgCode, "%v", msg.Code)
@@ -791,20 +856,48 @@ func (pm *ProtocolManager) BroadcastBlock(block *types.Block, propagate bool) {
 
 // BroadcastTxs will propagate a batch of transactions to all peers which are not known to
 // already have the given transaction.
-func (pm *ProtocolManager) BroadcastTxs(txs types.Transactions) {
+func (pm *ProtocolManager) BroadcastTxs(txs types.Transactions, propagate bool) {
-	var txset = make(map[*peer]types.Transactions)
+	var (
-
+		txset = make(map[*peer][]common.Hash)
+		annos = make(map[*peer][]common.Hash)
+	)
 	// Broadcast transactions to a batch of peers not knowing about it
+	if propagate {
+		for _, tx := range txs {
+			peers := pm.peers.PeersWithoutTx(tx.Hash())
+
+			// Send the block to a subset of our peers
+			transferLen := int(math.Sqrt(float64(len(peers))))
+			if transferLen < minBroadcastPeers {
+				transferLen = minBroadcastPeers
+			}
+			if transferLen > len(peers) {
+				transferLen = len(peers)
+			}
+			transfer := peers[:transferLen]
+			for _, peer := range transfer {
+				txset[peer] = append(txset[peer], tx.Hash())
+			}
+			log.Trace("Broadcast transaction", "hash", tx.Hash(), "recipients", len(peers))
+		}
+		for peer, hashes := range txset {
+			peer.AsyncSendTransactions(hashes)
+		}
+		return
+	}
+	// Otherwise only broadcast the announcement to peers
 	for _, tx := range txs {
 		peers := pm.peers.PeersWithoutTx(tx.Hash())
 		for _, peer := range peers {
-			txset[peer] = append(txset[peer], tx)
+			annos[peer] = append(annos[peer], tx.Hash())
 		}
-		log.Trace("Broadcast transaction", "hash", tx.Hash(), "recipients", len(peers))
 	}
-	// FIXME include this again: peers = peers[:int(math.Sqrt(float64(len(peers))))]
+	for peer, hashes := range annos {
-	for peer, txs := range txset {
+		if peer.version >= eth65 {
-		peer.AsyncSendTransactions(txs)
+			peer.AsyncSendTransactionHashes(hashes)
+		} else {
+			peer.AsyncSendTransactions(hashes)
+		}
 	}
 }
 
@@ -823,7 +916,13 @@ func (pm *ProtocolManager) txBroadcastLoop() {
 	for {
 		select {
 		case event := <-pm.txsCh:
-			pm.BroadcastTxs(event.Txs)
+			// For testing purpose only, disable propagation
+			if pm.broadcastTxAnnouncesOnly {
+				pm.BroadcastTxs(event.Txs, false)
+				continue
+			}
+			pm.BroadcastTxs(event.Txs, true)  // First propagate transactions to peers
+			pm.BroadcastTxs(event.Txs, false) // Only then announce to the rest
 
 		// Err() channel will be closed when unsubscribing.
 		case <-pm.txsSub.Err():

eth/handler_test.go

@@ -495,7 +495,7 @@ func testCheckpointChallenge(t *testing.T, syncmode downloader.SyncMode, checkpo
 	if err != nil {
 		t.Fatalf("failed to create new blockchain: %v", err)
 	}
-	pm, err := NewProtocolManager(config, cht, syncmode, DefaultConfig.NetworkId, new(event.TypeMux), new(testTxPool), ethash.NewFaker(), blockchain, db, 1, nil)
+	pm, err := NewProtocolManager(config, cht, syncmode, DefaultConfig.NetworkId, new(event.TypeMux), &testTxPool{pool: make(map[common.Hash]*types.Transaction)}, ethash.NewFaker(), blockchain, db, 1, nil)
 	if err != nil {
 		t.Fatalf("failed to start test protocol manager: %v", err)
 	}
@@ -582,7 +582,7 @@ func testBroadcastBlock(t *testing.T, totalPeers, broadcastExpected int) {
 	if err != nil {
 		t.Fatalf("failed to create new blockchain: %v", err)
 	}
-	pm, err := NewProtocolManager(config, nil, downloader.FullSync, DefaultConfig.NetworkId, evmux, new(testTxPool), pow, blockchain, db, 1, nil)
+	pm, err := NewProtocolManager(config, nil, downloader.FullSync, DefaultConfig.NetworkId, evmux, &testTxPool{pool: make(map[common.Hash]*types.Transaction)}, pow, blockchain, db, 1, nil)
 	if err != nil {
 		t.Fatalf("failed to start test protocol manager: %v", err)
 	}

eth/helper_test.go

@@ -68,7 +68,7 @@ func newTestProtocolManager(mode downloader.SyncMode, blocks int, generator func
 	if _, err := blockchain.InsertChain(chain); err != nil {
 		panic(err)
 	}
-	pm, err := NewProtocolManager(gspec.Config, nil, mode, DefaultConfig.NetworkId, evmux, &testTxPool{added: newtx}, engine, blockchain, db, 1, nil)
+	pm, err := NewProtocolManager(gspec.Config, nil, mode, DefaultConfig.NetworkId, evmux, &testTxPool{added: newtx, pool: make(map[common.Hash]*types.Transaction)}, engine, blockchain, db, 1, nil)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -91,22 +91,43 @@ func newTestProtocolManagerMust(t *testing.T, mode downloader.SyncMode, blocks i
 // testTxPool is a fake, helper transaction pool for testing purposes
 type testTxPool struct {
 	txFeed event.Feed
-	pool   []*types.Transaction        // Collection of all transactions
+	pool   map[common.Hash]*types.Transaction // Hash map of collected transactions
-	added  chan<- []*types.Transaction // Notification channel for new transactions
+	added  chan<- []*types.Transaction        // Notification channel for new transactions
 
 	lock sync.RWMutex // Protects the transaction pool
 }
 
+// Has returns an indicator whether txpool has a transaction
+// cached with the given hash.
+func (p *testTxPool) Has(hash common.Hash) bool {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	return p.pool[hash] != nil
+}
+
+// Get retrieves the transaction from local txpool with given
+// tx hash.
+func (p *testTxPool) Get(hash common.Hash) *types.Transaction {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	return p.pool[hash]
+}
+
 // AddRemotes appends a batch of transactions to the pool, and notifies any
 // listeners if the addition channel is non nil
 func (p *testTxPool) AddRemotes(txs []*types.Transaction) []error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
 
-	p.pool = append(p.pool, txs...)
+	for _, tx := range txs {
+		p.pool[tx.Hash()] = tx
+	}
 	if p.added != nil {
 		p.added <- txs
 	}
+	p.txFeed.Send(core.NewTxsEvent{Txs: txs})
 	return make([]error, len(txs))
 }
 
@@ -153,7 +174,7 @@ func newTestPeer(name string, version int, pm *ProtocolManager, shake bool) (*te
 	var id enode.ID
 	rand.Read(id[:])
 
-	peer := pm.newPeer(version, p2p.NewPeer(id, name, nil), net)
+	peer := pm.newPeer(version, p2p.NewPeer(id, name, nil), net, pm.txpool.Get)
 
 	// Start the peer on a new thread
 	errc := make(chan error, 1)
@@ -191,7 +212,7 @@ func (p *testPeer) handshake(t *testing.T, td *big.Int, head common.Hash, genesi
 			CurrentBlock:    head,
 			GenesisBlock:    genesis,
 		}
-	case p.version == eth64:
+	case p.version >= eth64:
 		msg = &statusData{
 			ProtocolVersion: uint32(p.version),
 			NetworkID:       DefaultConfig.NetworkId,

eth/peer.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/forkid"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/eth/fetcher"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -41,24 +42,39 @@ const (
 	maxKnownTxs    = 32768 // Maximum transactions hashes to keep in the known list (prevent DOS)
 	maxKnownBlocks = 1024  // Maximum block hashes to keep in the known list (prevent DOS)
 
-	// maxQueuedTxs is the maximum number of transaction lists to queue up before
+	// maxQueuedTxs is the maximum number of transactions to queue up before dropping
-	// dropping broadcasts. This is a sensitive number as a transaction list might
+	// broadcasts.
-	// contain a single transaction, or thousands.
+	maxQueuedTxs = 4096
-	maxQueuedTxs = 128
 
-	// maxQueuedProps is the maximum number of block propagations to queue up before
+	// maxQueuedTxAnns is the maximum number of transaction announcements to queue up
+	// before dropping broadcasts.
+	maxQueuedTxAnns = 4096
+
+	// maxQueuedTxRetrieval is the maximum number of tx retrieval requests to queue up
+	// before dropping requests.
+	maxQueuedTxRetrieval = 4096
+
+	// maxQueuedBlocks is the maximum number of block propagations to queue up before
 	// dropping broadcasts. There's not much point in queueing stale blocks, so a few
 	// that might cover uncles should be enough.
-	maxQueuedProps = 4
+	maxQueuedBlocks = 4
 
-	// maxQueuedAnns is the maximum number of block announcements to queue up before
+	// maxQueuedBlockAnns is the maximum number of block announcements to queue up before
 	// dropping broadcasts. Similarly to block propagations, there's no point to queue
 	// above some healthy uncle limit, so use that.
-	maxQueuedAnns = 4
+	maxQueuedBlockAnns = 4
 
 	handshakeTimeout = 5 * time.Second
 )
 
+// max is a helper function which returns the larger of the two given integers.
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
 // PeerInfo represents a short summary of the Ethereum sub-protocol metadata known
 // about a connected peer.
 type PeerInfo struct {
@@ -86,48 +102,48 @@ type peer struct {
 	td   *big.Int
 	lock sync.RWMutex
 
-	knownTxs    mapset.Set                // Set of transaction hashes known to be known by this peer
+	knownTxs        mapset.Set                           // Set of transaction hashes known to be known by this peer
-	knownBlocks mapset.Set                // Set of block hashes known to be known by this peer
+	knownBlocks     mapset.Set                           // Set of block hashes known to be known by this peer
-	queuedTxs   chan []*types.Transaction // Queue of transactions to broadcast to the peer
+	queuedBlocks    chan *propEvent                      // Queue of blocks to broadcast to the peer
-	queuedProps chan *propEvent           // Queue of blocks to broadcast to the peer
+	queuedBlockAnns chan *types.Block                    // Queue of blocks to announce to the peer
-	queuedAnns  chan *types.Block         // Queue of blocks to announce to the peer
+	txPropagation   chan []common.Hash                   // Channel used to queue transaction propagation requests
-	term        chan struct{}             // Termination channel to stop the broadcaster
+	txAnnounce      chan []common.Hash                   // Channel used to queue transaction announcement requests
+	txRetrieval     chan []common.Hash                   // Channel used to queue transaction retrieval requests
+	getPooledTx     func(common.Hash) *types.Transaction // Callback used to retrieve transaction from txpool
+	term            chan struct{}                        // Termination channel to stop the broadcaster
 }
 
-func newPeer(version int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
+func newPeer(version int, p *p2p.Peer, rw p2p.MsgReadWriter, getPooledTx func(hash common.Hash) *types.Transaction) *peer {
 	return &peer{
-		Peer:        p,
+		Peer:            p,
-		rw:          rw,
+		rw:              rw,
-		version:     version,
+		version:         version,
-		id:          fmt.Sprintf("%x", p.ID().Bytes()[:8]),
+		id:              fmt.Sprintf("%x", p.ID().Bytes()[:8]),
-		knownTxs:    mapset.NewSet(),
+		knownTxs:        mapset.NewSet(),
-		knownBlocks: mapset.NewSet(),
+		knownBlocks:     mapset.NewSet(),
-		queuedTxs:   make(chan []*types.Transaction, maxQueuedTxs),
+		queuedBlocks:    make(chan *propEvent, maxQueuedBlocks),
-		queuedProps: make(chan *propEvent, maxQueuedProps),
+		queuedBlockAnns: make(chan *types.Block, maxQueuedBlockAnns),
-		queuedAnns:  make(chan *types.Block, maxQueuedAnns),
+		txPropagation:   make(chan []common.Hash),
-		term:        make(chan struct{}),
+		txAnnounce:      make(chan []common.Hash),
+		txRetrieval:     make(chan []common.Hash),
+		getPooledTx:     getPooledTx,
+		term:            make(chan struct{}),
 	}
 }
 
-// broadcast is a write loop that multiplexes block propagations, announcements
+// broadcastBlocks is a write loop that multiplexes block propagations,
-// and transaction broadcasts into the remote peer. The goal is to have an async
+// announcements into the remote peer. The goal is to have an async writer
-// writer that does not lock up node internals.
+// that does not lock up node internals.
-func (p *peer) broadcast() {
+func (p *peer) broadcastBlocks() {
 	for {
 		select {
-		case txs := <-p.queuedTxs:
+		case prop := <-p.queuedBlocks:
-			if err := p.SendTransactions(txs); err != nil {
-				return
-			}
-			p.Log().Trace("Broadcast transactions", "count", len(txs))
-
-		case prop := <-p.queuedProps:
 			if err := p.SendNewBlock(prop.block, prop.td); err != nil {
 				return
 			}
 			p.Log().Trace("Propagated block", "number", prop.block.Number(), "hash", prop.block.Hash(), "td", prop.td)
 
-		case block := <-p.queuedAnns:
+		case block := <-p.queuedBlockAnns:
 			if err := p.SendNewBlockHashes([]common.Hash{block.Hash()}, []uint64{block.NumberU64()}); err != nil {
 				return
 			}
@@ -139,6 +155,175 @@ func (p *peer) broadcast() {
 	}
 }
 
+// broadcastTxs is a write loop that multiplexes transaction propagations,
+// announcements into the remote peer. The goal is to have an async writer
+// that does not lock up node internals.
+func (p *peer) broadcastTxs() {
+	var (
+		txProps []common.Hash      // Queue of transaction propagations to the peer
+		txAnnos []common.Hash      // Queue of transaction announcements to the peer
+		done    chan struct{}      // Non-nil if background network sender routine is active.
+		errch   = make(chan error) // Channel used to receive network error
+	)
+	scheduleTask := func() {
+		// Short circuit if there already has a inflight task.
+		if done != nil {
+			return
+		}
+		// Spin up transaction propagation task if there is any
+		// queued hashes.
+		if len(txProps) > 0 {
+			var (
+				hashes []common.Hash
+				txs    []*types.Transaction
+				size   common.StorageSize
+			)
+			for i := 0; i < len(txProps) && size < txsyncPackSize; i++ {
+				if tx := p.getPooledTx(txProps[i]); tx != nil {
+					txs = append(txs, tx)
+					size += tx.Size()
+				}
+				hashes = append(hashes, txProps[i])
+			}
+			txProps = txProps[:copy(txProps, txProps[len(hashes):])]
+			if len(txs) > 0 {
+				done = make(chan struct{})
+				go func() {
+					if err := p.SendNewTransactions(txs); err != nil {
+						errch <- err
+						return
+					}
+					close(done)
+					p.Log().Trace("Sent transactions", "count", len(txs))
+				}()
+				return
+			}
+		}
+		// Spin up transaction announcement task if there is any
+		// queued hashes.
+		if len(txAnnos) > 0 {
+			var (
+				hashes  []common.Hash
+				pending []common.Hash
+				size    common.StorageSize
+			)
+			for i := 0; i < len(txAnnos) && size < txsyncPackSize; i++ {
+				if tx := p.getPooledTx(txAnnos[i]); tx != nil {
+					pending = append(pending, txAnnos[i])
+					size += common.HashLength
+				}
+				hashes = append(hashes, txAnnos[i])
+			}
+			txAnnos = txAnnos[:copy(txAnnos, txAnnos[len(hashes):])]
+			if len(pending) > 0 {
+				done = make(chan struct{})
+				go func() {
+					if err := p.SendNewTransactionHashes(pending); err != nil {
+						errch <- err
+						return
+					}
+					close(done)
+					p.Log().Trace("Sent transaction announcements", "count", len(pending))
+				}()
+			}
+		}
+	}
+
+	for {
+		scheduleTask()
+		select {
+		case hashes := <-p.txPropagation:
+			if len(txProps) == maxQueuedTxs {
+				continue
+			}
+			if len(txProps)+len(hashes) > maxQueuedTxs {
+				hashes = hashes[:maxQueuedTxs-len(txProps)]
+			}
+			txProps = append(txProps, hashes...)
+
+		case hashes := <-p.txAnnounce:
+			if len(txAnnos) == maxQueuedTxAnns {
+				continue
+			}
+			if len(txAnnos)+len(hashes) > maxQueuedTxAnns {
+				hashes = hashes[:maxQueuedTxAnns-len(txAnnos)]
+			}
+			txAnnos = append(txAnnos, hashes...)
+
+		case <-done:
+			done = nil
+
+		case <-errch:
+			return
+
+		case <-p.term:
+			return
+		}
+	}
+}
+
+// retrievalTxs is a write loop which is responsible for retrieving transaction
+// from the remote peer. The goal is to have an async writer that does not lock
+// up node internals. If there are too many requests queued, then new arrival
+// requests will be dropped silently so that we can ensure the memory assumption
+// is fixed for each peer.
+func (p *peer) retrievalTxs() {
+	var (
+		requests []common.Hash      // Queue of transaction requests to the peer
+		done     chan struct{}      // Non-nil if background network sender routine is active.
+		errch    = make(chan error) // Channel used to receive network error
+	)
+	// pick chooses a reasonble number of transaction hashes for retrieval.
+	pick := func() []common.Hash {
+		var ret []common.Hash
+		if len(requests) > fetcher.MaxTransactionFetch {
+			ret = requests[:fetcher.MaxTransactionFetch]
+		} else {
+			ret = requests[:]
+		}
+		requests = requests[:copy(requests, requests[len(ret):])]
+		return ret
+	}
+	// send sends transactions retrieval request.
+	send := func(hashes []common.Hash, done chan struct{}) {
+		if err := p.RequestTxs(hashes); err != nil {
+			errch <- err
+			return
+		}
+		close(done)
+		p.Log().Trace("Sent transaction retrieval request", "count", len(hashes))
+	}
+	for {
+		select {
+		case hashes := <-p.txRetrieval:
+			if len(requests) == maxQueuedTxRetrieval {
+				continue
+			}
+			if len(requests)+len(hashes) > maxQueuedTxRetrieval {
+				hashes = hashes[:maxQueuedTxRetrieval-len(requests)]
+			}
+			requests = append(requests, hashes...)
+			if done == nil {
+				done = make(chan struct{})
+				go send(pick(), done)
+			}
+
+		case <-done:
+			done = nil
+			if pending := pick(); len(pending) > 0 {
+				done = make(chan struct{})
+				go send(pending, done)
+			}
+
+		case <- errch:
+			return
+
+		case <-p.term:
+			return
+		}
+	}
+}
+
 // close signals the broadcast goroutine to terminate.
 func (p *peer) close() {
 	close(p.term)
@@ -194,33 +379,67 @@ func (p *peer) MarkTransaction(hash common.Hash) {
 	p.knownTxs.Add(hash)
 }
 
-// SendTransactions sends transactions to the peer and includes the hashes
+// SendNewTransactionHashes sends a batch of transaction hashes to the peer and
-// in its transaction hash set for future reference.
+// includes the hashes in its transaction hash set for future reference.
-func (p *peer) SendTransactions(txs types.Transactions) error {
+func (p *peer) SendNewTransactionHashes(hashes []common.Hash) error {
 	// Mark all the transactions as known, but ensure we don't overflow our limits
+	for p.knownTxs.Cardinality() > max(0, maxKnownTxs-len(hashes)) {
+		p.knownTxs.Pop()
+	}
+	for _, hash := range hashes {
+		p.knownTxs.Add(hash)
+	}
+	return p2p.Send(p.rw, NewPooledTransactionHashesMsg, hashes)
+}
+
+// SendNewTransactions sends transactions to the peer and includes the hashes
+// in its transaction hash set for future reference.
+func (p *peer) SendNewTransactions(txs types.Transactions) error {
+	// Mark all the transactions as known, but ensure we don't overflow our limits
+	for p.knownTxs.Cardinality() > max(0, maxKnownTxs-len(txs)) {
+		p.knownTxs.Pop()
+	}
 	for _, tx := range txs {
 		p.knownTxs.Add(tx.Hash())
 	}
-	for p.knownTxs.Cardinality() >= maxKnownTxs {
+	return p2p.Send(p.rw, TxMsg, txs)
-		p.knownTxs.Pop()
+}
-	}
+
+func (p *peer) SendTransactionRLP(txs []rlp.RawValue) error {
 	return p2p.Send(p.rw, TxMsg, txs)
 }
 
 // AsyncSendTransactions queues list of transactions propagation to a remote
 // peer. If the peer's broadcast queue is full, the event is silently dropped.
-func (p *peer) AsyncSendTransactions(txs []*types.Transaction) {
+func (p *peer) AsyncSendTransactions(hashes []common.Hash) {
 	select {
-	case p.queuedTxs <- txs:
+	case p.txPropagation <- hashes:
 		// Mark all the transactions as known, but ensure we don't overflow our limits
-		for _, tx := range txs {
+		for p.knownTxs.Cardinality() > max(0, maxKnownTxs-len(hashes)) {
-			p.knownTxs.Add(tx.Hash())
-		}
-		for p.knownTxs.Cardinality() >= maxKnownTxs {
 			p.knownTxs.Pop()
 		}
-	default:
+		for _, hash := range hashes {
-		p.Log().Debug("Dropping transaction propagation", "count", len(txs))
+			p.knownTxs.Add(hash)
+		}
+	case <-p.term:
+		p.Log().Debug("Dropping transaction propagation", "count", len(hashes))
+	}
+}
+
+// AsyncSendTransactions queues list of transactions propagation to a remote
+// peer. If the peer's broadcast queue is full, the event is silently dropped.
+func (p *peer) AsyncSendTransactionHashes(hashes []common.Hash) {
+	select {
+	case p.txAnnounce <- hashes:
+		// Mark all the transactions as known, but ensure we don't overflow our limits
+		for p.knownTxs.Cardinality() > max(0, maxKnownTxs-len(hashes)) {
+			p.knownTxs.Pop()
+		}
+		for _, hash := range hashes {
+			p.knownTxs.Add(hash)
+		}
+	case <-p.term:
+		p.Log().Debug("Dropping transaction announcement", "count", len(hashes))
 	}
 }
 
@@ -228,12 +447,12 @@ func (p *peer) AsyncSendTransactions(txs []*types.Transaction) {
 // a hash notification.
 func (p *peer) SendNewBlockHashes(hashes []common.Hash, numbers []uint64) error {
 	// Mark all the block hashes as known, but ensure we don't overflow our limits
+	for p.knownBlocks.Cardinality() > max(0, maxKnownBlocks-len(hashes)) {
+		p.knownBlocks.Pop()
+	}
 	for _, hash := range hashes {
 		p.knownBlocks.Add(hash)
 	}
-	for p.knownBlocks.Cardinality() >= maxKnownBlocks {
-		p.knownBlocks.Pop()
-	}
 	request := make(newBlockHashesData, len(hashes))
 	for i := 0; i < len(hashes); i++ {
 		request[i].Hash = hashes[i]
@@ -247,12 +466,12 @@ func (p *peer) SendNewBlockHashes(hashes []common.Hash, numbers []uint64) error
 // dropped.
 func (p *peer) AsyncSendNewBlockHash(block *types.Block) {
 	select {
-	case p.queuedAnns <- block:
+	case p.queuedBlockAnns <- block:
 		// Mark all the block hash as known, but ensure we don't overflow our limits
-		p.knownBlocks.Add(block.Hash())
 		for p.knownBlocks.Cardinality() >= maxKnownBlocks {
 			p.knownBlocks.Pop()
 		}
+		p.knownBlocks.Add(block.Hash())
 	default:
 		p.Log().Debug("Dropping block announcement", "number", block.NumberU64(), "hash", block.Hash())
 	}
@@ -261,10 +480,10 @@ func (p *peer) AsyncSendNewBlockHash(block *types.Block) {
 // SendNewBlock propagates an entire block to a remote peer.
 func (p *peer) SendNewBlock(block *types.Block, td *big.Int) error {
 	// Mark all the block hash as known, but ensure we don't overflow our limits
-	p.knownBlocks.Add(block.Hash())
 	for p.knownBlocks.Cardinality() >= maxKnownBlocks {
 		p.knownBlocks.Pop()
 	}
+	p.knownBlocks.Add(block.Hash())
 	return p2p.Send(p.rw, NewBlockMsg, []interface{}{block, td})
 }
 
@@ -272,12 +491,12 @@ func (p *peer) SendNewBlock(block *types.Block, td *big.Int) error {
 // the peer's broadcast queue is full, the event is silently dropped.
 func (p *peer) AsyncSendNewBlock(block *types.Block, td *big.Int) {
 	select {
-	case p.queuedProps <- &propEvent{block: block, td: td}:
+	case p.queuedBlocks <- &propEvent{block: block, td: td}:
 		// Mark all the block hash as known, but ensure we don't overflow our limits
-		p.knownBlocks.Add(block.Hash())
 		for p.knownBlocks.Cardinality() >= maxKnownBlocks {
 			p.knownBlocks.Pop()
 		}
+		p.knownBlocks.Add(block.Hash())
 	default:
 		p.Log().Debug("Dropping block propagation", "number", block.NumberU64(), "hash", block.Hash())
 	}
@@ -352,6 +571,22 @@ func (p *peer) RequestReceipts(hashes []common.Hash) error {
 	return p2p.Send(p.rw, GetReceiptsMsg, hashes)
 }
 
+// RequestTxs fetches a batch of transactions from a remote node.
+func (p *peer) RequestTxs(hashes []common.Hash) error {
+	p.Log().Debug("Fetching batch of transactions", "count", len(hashes))
+	return p2p.Send(p.rw, GetPooledTransactionsMsg, hashes)
+}
+
+// AsyncRequestTxs queues a tx retrieval request to a remote peer. If
+// the peer's retrieval queue is full, the event is silently dropped.
+func (p *peer) AsyncRequestTxs(hashes []common.Hash) {
+	select {
+	case p.txRetrieval <- hashes:
+	case <-p.term:
+		p.Log().Debug("Dropping transaction retrieval request", "count", len(hashes))
+	}
+}
+
 // Handshake executes the eth protocol handshake, negotiating version number,
 // network IDs, difficulties, head and genesis blocks.
 func (p *peer) Handshake(network uint64, td *big.Int, head common.Hash, genesis common.Hash, forkID forkid.ID, forkFilter forkid.Filter) error {
@@ -372,7 +607,7 @@ func (p *peer) Handshake(network uint64, td *big.Int, head common.Hash, genesis
 				CurrentBlock:    head,
 				GenesisBlock:    genesis,
 			})
-		case p.version == eth64:
+		case p.version >= eth64:
 			errc <- p2p.Send(p.rw, StatusMsg, &statusData{
 				ProtocolVersion: uint32(p.version),
 				NetworkID:       network,
@@ -389,7 +624,7 @@ func (p *peer) Handshake(network uint64, td *big.Int, head common.Hash, genesis
 		switch {
 		case p.version == eth63:
 			errc <- p.readStatusLegacy(network, &status63, genesis)
-		case p.version == eth64:
+		case p.version >= eth64:
 			errc <- p.readStatus(network, &status, genesis, forkFilter)
 		default:
 			panic(fmt.Sprintf("unsupported eth protocol version: %d", p.version))
@@ -410,7 +645,7 @@ func (p *peer) Handshake(network uint64, td *big.Int, head common.Hash, genesis
 	switch {
 	case p.version == eth63:
 		p.td, p.head = status63.TD, status63.CurrentBlock
-	case p.version == eth64:
+	case p.version >= eth64:
 		p.td, p.head = status.TD, status.Head
 	default:
 		panic(fmt.Sprintf("unsupported eth protocol version: %d", p.version))
@@ -511,7 +746,9 @@ func (ps *peerSet) Register(p *peer) error {
 		return errAlreadyRegistered
 	}
 	ps.peers[p.id] = p
-	go p.broadcast()
+	go p.broadcastBlocks()
+	go p.broadcastTxs()
+	go p.retrievalTxs()
 
 	return nil
 }

eth/protocol.go

@@ -33,16 +33,17 @@ import (
 const (
 	eth63 = 63
 	eth64 = 64
+	eth65 = 65
 )
 
 // protocolName is the official short name of the protocol used during capability negotiation.
 const protocolName = "eth"
 
 // ProtocolVersions are the supported versions of the eth protocol (first is primary).
-var ProtocolVersions = []uint{eth64, eth63}
+var ProtocolVersions = []uint{eth65, eth64, eth63}
 
 // protocolLengths are the number of implemented message corresponding to different protocol versions.
-var protocolLengths = map[uint]uint64{eth64: 17, eth63: 17}
+var protocolLengths = map[uint]uint64{eth65: 17, eth64: 17, eth63: 17}
 
 const protocolMaxMsgSize = 10 * 1024 * 1024 // Maximum cap on the size of a protocol message
 
@@ -60,6 +61,13 @@ const (
 	NodeDataMsg        = 0x0e
 	GetReceiptsMsg     = 0x0f
 	ReceiptsMsg        = 0x10
+
+	// New protocol message codes introduced in eth65
+	//
+	// Previously these message ids(0x08, 0x09) were used by some
+	// legacy and unsupported eth protocols, reown them here.
+	NewPooledTransactionHashesMsg = 0x08
+	GetPooledTransactionsMsg      = 0x09
 )
 
 type errCode int
@@ -94,6 +102,14 @@ var errorToString = map[int]string{
 }
 
 type txPool interface {
+	// Has returns an indicator whether txpool has a transaction
+	// cached with the given hash.
+	Has(hash common.Hash) bool
+
+	// Get retrieves the transaction from local txpool with given
+	// tx hash.
+	Get(hash common.Hash) *types.Transaction
+
 	// AddRemotes should add the given transactions to the pool.
 	AddRemotes([]*types.Transaction) []error
 

eth/protocol_test.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"math/big"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -180,16 +181,16 @@ func TestForkIDSplit(t *testing.T) {
 		blocksNoFork, _  = core.GenerateChain(configNoFork, genesisNoFork, engine, dbNoFork, 2, nil)
 		blocksProFork, _ = core.GenerateChain(configProFork, genesisProFork, engine, dbProFork, 2, nil)
 
-		ethNoFork, _  = NewProtocolManager(configNoFork, nil, downloader.FullSync, 1, new(event.TypeMux), new(testTxPool), engine, chainNoFork, dbNoFork, 1, nil)
+		ethNoFork, _  = NewProtocolManager(configNoFork, nil, downloader.FullSync, 1, new(event.TypeMux), &testTxPool{pool: make(map[common.Hash]*types.Transaction)}, engine, chainNoFork, dbNoFork, 1, nil)
-		ethProFork, _ = NewProtocolManager(configProFork, nil, downloader.FullSync, 1, new(event.TypeMux), new(testTxPool), engine, chainProFork, dbProFork, 1, nil)
+		ethProFork, _ = NewProtocolManager(configProFork, nil, downloader.FullSync, 1, new(event.TypeMux), &testTxPool{pool: make(map[common.Hash]*types.Transaction)}, engine, chainProFork, dbProFork, 1, nil)
 	)
 	ethNoFork.Start(1000)
 	ethProFork.Start(1000)
 
 	// Both nodes should allow the other to connect (same genesis, next fork is the same)
 	p2pNoFork, p2pProFork := p2p.MsgPipe()
-	peerNoFork := newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork)
+	peerNoFork := newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork, nil)
-	peerProFork := newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork)
+	peerProFork := newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork, nil)
 
 	errc := make(chan error, 2)
 	go func() { errc <- ethNoFork.handle(peerProFork) }()
@@ -207,8 +208,8 @@ func TestForkIDSplit(t *testing.T) {
 	chainProFork.InsertChain(blocksProFork[:1])
 
 	p2pNoFork, p2pProFork = p2p.MsgPipe()
-	peerNoFork = newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork)
+	peerNoFork = newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork, nil)
-	peerProFork = newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork)
+	peerProFork = newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork, nil)
 
 	errc = make(chan error, 2)
 	go func() { errc <- ethNoFork.handle(peerProFork) }()
@@ -226,8 +227,8 @@ func TestForkIDSplit(t *testing.T) {
 	chainProFork.InsertChain(blocksProFork[1:2])
 
 	p2pNoFork, p2pProFork = p2p.MsgPipe()
-	peerNoFork = newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork)
+	peerNoFork = newPeer(64, p2p.NewPeer(enode.ID{1}, "", nil), p2pNoFork, nil)
-	peerProFork = newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork)
+	peerProFork = newPeer(64, p2p.NewPeer(enode.ID{2}, "", nil), p2pProFork, nil)
 
 	errc = make(chan error, 2)
 	go func() { errc <- ethNoFork.handle(peerProFork) }()
@@ -246,6 +247,7 @@ func TestForkIDSplit(t *testing.T) {
 // This test checks that received transactions are added to the local pool.
 func TestRecvTransactions63(t *testing.T) { testRecvTransactions(t, 63) }
 func TestRecvTransactions64(t *testing.T) { testRecvTransactions(t, 64) }
+func TestRecvTransactions65(t *testing.T) { testRecvTransactions(t, 65) }
 
 func testRecvTransactions(t *testing.T, protocol int) {
 	txAdded := make(chan []*types.Transaction)
@@ -274,6 +276,7 @@ func testRecvTransactions(t *testing.T, protocol int) {
 // This test checks that pending transactions are sent.
 func TestSendTransactions63(t *testing.T) { testSendTransactions(t, 63) }
 func TestSendTransactions64(t *testing.T) { testSendTransactions(t, 64) }
+func TestSendTransactions65(t *testing.T) { testSendTransactions(t, 65) }
 
 func testSendTransactions(t *testing.T, protocol int) {
 	pm, _ := newTestProtocolManagerMust(t, downloader.FullSync, 0, nil, nil)
@@ -298,17 +301,43 @@ func testSendTransactions(t *testing.T, protocol int) {
 		}
 		for n := 0; n < len(alltxs) && !t.Failed(); {
 			var txs []*types.Transaction
-			msg, err := p.app.ReadMsg()
+			var hashes []common.Hash
-			if err != nil {
+			var forAllHashes func(callback func(hash common.Hash))
-				t.Errorf("%v: read error: %v", p.Peer, err)
+			switch protocol {
-			} else if msg.Code != TxMsg {
+			case 63:
-				t.Errorf("%v: got code %d, want TxMsg", p.Peer, msg.Code)
+				fallthrough
+			case 64:
+				msg, err := p.app.ReadMsg()
+				if err != nil {
+					t.Errorf("%v: read error: %v", p.Peer, err)
+				} else if msg.Code != TxMsg {
+					t.Errorf("%v: got code %d, want TxMsg", p.Peer, msg.Code)
+				}
+				if err := msg.Decode(&txs); err != nil {
+					t.Errorf("%v: %v", p.Peer, err)
+				}
+				forAllHashes = func(callback func(hash common.Hash)) {
+					for _, tx := range txs {
+						callback(tx.Hash())
+					}
+				}
+			case 65:
+				msg, err := p.app.ReadMsg()
+				if err != nil {
+					t.Errorf("%v: read error: %v", p.Peer, err)
+				} else if msg.Code != NewPooledTransactionHashesMsg {
+					t.Errorf("%v: got code %d, want TxMsg", p.Peer, msg.Code)
+				}
+				if err := msg.Decode(&hashes); err != nil {
+					t.Errorf("%v: %v", p.Peer, err)
+				}
+				forAllHashes = func(callback func(hash common.Hash)) {
+					for _, h := range hashes {
+						callback(h)
+					}
+				}
 			}
-			if err := msg.Decode(&txs); err != nil {
+			forAllHashes(func(hash common.Hash) {
-				t.Errorf("%v: %v", p.Peer, err)
-			}
-			for _, tx := range txs {
-				hash := tx.Hash()
 				seentx, want := seen[hash]
 				if seentx {
 					t.Errorf("%v: got tx more than once: %x", p.Peer, hash)
@@ -318,7 +347,7 @@ func testSendTransactions(t *testing.T, protocol int) {
 				}
 				seen[hash] = true
 				n++
-			}
+			})
 		}
 	}
 	for i := 0; i < 3; i++ {
@@ -329,6 +358,53 @@ func testSendTransactions(t *testing.T, protocol int) {
 	wg.Wait()
 }
 
+func TestTransactionPropagation(t *testing.T)  { testSyncTransaction(t, true) }
+func TestTransactionAnnouncement(t *testing.T) { testSyncTransaction(t, false) }
+
+func testSyncTransaction(t *testing.T, propagtion bool) {
+	// Create a protocol manager for transaction fetcher and sender
+	pmFetcher, _ := newTestProtocolManagerMust(t, downloader.FastSync, 0, nil, nil)
+	defer pmFetcher.Stop()
+	pmSender, _ := newTestProtocolManagerMust(t, downloader.FastSync, 1024, nil, nil)
+	pmSender.broadcastTxAnnouncesOnly = !propagtion
+	defer pmSender.Stop()
+
+	// Sync up the two peers
+	io1, io2 := p2p.MsgPipe()
+
+	go pmSender.handle(pmSender.newPeer(65, p2p.NewPeer(enode.ID{}, "sender", nil), io2, pmSender.txpool.Get))
+	go pmFetcher.handle(pmFetcher.newPeer(65, p2p.NewPeer(enode.ID{}, "fetcher", nil), io1, pmFetcher.txpool.Get))
+
+	time.Sleep(250 * time.Millisecond)
+	pmFetcher.synchronise(pmFetcher.peers.BestPeer())
+	atomic.StoreUint32(&pmFetcher.acceptTxs, 1)
+
+	newTxs := make(chan core.NewTxsEvent, 1024)
+	sub := pmFetcher.txpool.SubscribeNewTxsEvent(newTxs)
+	defer sub.Unsubscribe()
+
+	// Fill the pool with new transactions
+	alltxs := make([]*types.Transaction, 1024)
+	for nonce := range alltxs {
+		alltxs[nonce] = newTestTransaction(testAccount, uint64(nonce), 0)
+	}
+	pmSender.txpool.AddRemotes(alltxs)
+
+	var got int
+loop:
+	for {
+		select {
+		case ev := <-newTxs:
+			got += len(ev.Txs)
+			if got == 1024 {
+				break loop
+			}
+		case <-time.NewTimer(time.Second).C:
+			t.Fatal("Failed to retrieve all transaction")
+		}
+	}
+}
+
 // Tests that the custom union field encoder and decoder works correctly.
 func TestGetBlockHeadersDataEncodeDecode(t *testing.T) {
 	// Create a "random" hash for testing

eth/sync.go

@@ -38,8 +38,9 @@ const (
 )
 
 type txsync struct {
-	p   *peer
+	p      *peer
-	txs []*types.Transaction
+	hashes []common.Hash
+	txs    []*types.Transaction
 }
 
 // syncTransactions starts sending all currently pending transactions to the given peer.
@@ -53,7 +54,7 @@ func (pm *ProtocolManager) syncTransactions(p *peer) {
 		return
 	}
 	select {
-	case pm.txsyncCh <- &txsync{p, txs}:
+	case pm.txsyncCh <- &txsync{p: p, txs: txs}:
 	case <-pm.quitSync:
 	}
 }
@@ -69,26 +70,46 @@ func (pm *ProtocolManager) txsyncLoop() {
 		pack    = new(txsync)         // the pack that is being sent
 		done    = make(chan error, 1) // result of the send
 	)
-
 	// send starts a sending a pack of transactions from the sync.
 	send := func(s *txsync) {
 		// Fill pack with transactions up to the target size.
 		size := common.StorageSize(0)
 		pack.p = s.p
+		pack.hashes = pack.hashes[:0]
 		pack.txs = pack.txs[:0]
-		for i := 0; i < len(s.txs) && size < txsyncPackSize; i++ {
+		if s.p.version >= eth65 {
-			pack.txs = append(pack.txs, s.txs[i])
+			// Eth65 introduces transaction announcement https://github.com/ethereum/EIPs/pull/2464,
-			size += s.txs[i].Size()
+			// only txhashes are transferred here.
+			for i := 0; i < len(s.txs) && size < txsyncPackSize; i++ {
+				pack.hashes = append(pack.hashes, s.txs[i].Hash())
+				size += common.HashLength
+			}
+			// Remove the transactions that will be sent.
+			s.txs = s.txs[:copy(s.txs, s.txs[len(pack.hashes):])]
+			if len(s.txs) == 0 {
+				delete(pending, s.p.ID())
+			}
+			// Send the pack in the background.
+			s.p.Log().Trace("Sending batch of transaction announcements", "count", len(pack.hashes), "bytes", size)
+			sending = true
+			go func() { done <- pack.p.SendNewTransactionHashes(pack.hashes) }()
+		} else {
+			// Legacy eth protocol doesn't have transaction announcement protocol
+			// message, transfer the whole pending transaction slice.
+			for i := 0; i < len(s.txs) && size < txsyncPackSize; i++ {
+				pack.txs = append(pack.txs, s.txs[i])
+				size += s.txs[i].Size()
+			}
+			// Remove the transactions that will be sent.
+			s.txs = s.txs[:copy(s.txs, s.txs[len(pack.txs):])]
+			if len(s.txs) == 0 {
+				delete(pending, s.p.ID())
+			}
+			// Send the pack in the background.
+			s.p.Log().Trace("Sending batch of transactions", "count", len(pack.txs), "bytes", size)
+			sending = true
+			go func() { done <- pack.p.SendNewTransactions(pack.txs) }()
 		}
-		// Remove the transactions that will be sent.
-		s.txs = s.txs[:copy(s.txs, s.txs[len(pack.txs):])]
-		if len(s.txs) == 0 {
-			delete(pending, s.p.ID())
-		}
-		// Send the pack in the background.
-		s.p.Log().Trace("Sending batch of transactions", "count", len(pack.txs), "bytes", size)
-		sending = true
-		go func() { done <- pack.p.SendTransactions(pack.txs) }()
 	}
 
 	// pick chooses the next pending sync.
@@ -133,8 +154,10 @@ func (pm *ProtocolManager) txsyncLoop() {
 // downloading hashes and blocks as well as handling the announcement handler.
 func (pm *ProtocolManager) syncer() {
 	// Start and ensure cleanup of sync mechanisms
-	pm.fetcher.Start()
+	pm.blockFetcher.Start()
-	defer pm.fetcher.Stop()
+	pm.txFetcher.Start()
+	defer pm.blockFetcher.Stop()
+	defer pm.txFetcher.Stop()
 	defer pm.downloader.Terminate()
 
 	// Wait for different events to fire synchronisation operations

eth/sync_test.go

@@ -26,9 +26,13 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/enode"
 )
 
+func TestFastSyncDisabling63(t *testing.T) { testFastSyncDisabling(t, 63) }
+func TestFastSyncDisabling64(t *testing.T) { testFastSyncDisabling(t, 64) }
+func TestFastSyncDisabling65(t *testing.T) { testFastSyncDisabling(t, 65) }
+
 // Tests that fast sync gets disabled as soon as a real block is successfully
 // imported into the blockchain.
-func TestFastSyncDisabling(t *testing.T) {
+func testFastSyncDisabling(t *testing.T, protocol int) {
 	// Create a pristine protocol manager, check that fast sync is left enabled
 	pmEmpty, _ := newTestProtocolManagerMust(t, downloader.FastSync, 0, nil, nil)
 	if atomic.LoadUint32(&pmEmpty.fastSync) == 0 {
@@ -42,8 +46,8 @@ func TestFastSyncDisabling(t *testing.T) {
 	// Sync up the two peers
 	io1, io2 := p2p.MsgPipe()
 
-	go pmFull.handle(pmFull.newPeer(63, p2p.NewPeer(enode.ID{}, "empty", nil), io2))
+	go pmFull.handle(pmFull.newPeer(protocol, p2p.NewPeer(enode.ID{}, "empty", nil), io2, pmFull.txpool.Get))
-	go pmEmpty.handle(pmEmpty.newPeer(63, p2p.NewPeer(enode.ID{}, "full", nil), io1))
+	go pmEmpty.handle(pmEmpty.newPeer(protocol, p2p.NewPeer(enode.ID{}, "full", nil), io1, pmEmpty.txpool.Get))
 
 	time.Sleep(250 * time.Millisecond)
 	pmEmpty.synchronise(pmEmpty.peers.BestPeer())