eth, les, light: Refactor downloader to use blockchain interface

6 files changed, 134 insertions, 146 deletions

diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index e4d1392d0..a5d03d17e 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -114,21 +114,11 @@ type Downloader struct {
 	syncStatsState       stateSyncStats
 	syncStatsLock        sync.RWMutex // Lock protecting the sync stats fields
 
+	lightchain LightChain
+	chain      BlockChain
+
 	// Callbacks
-	hasHeader        headerCheckFn            // Checks if a header is present in the chain
-	hasBlockAndState blockAndStateCheckFn     // Checks if a block and associated state is present in the chain
-	getHeader        headerRetrievalFn        // Retrieves a header from the chain
-	getBlock         blockRetrievalFn         // Retrieves a block from the chain
-	headHeader       headHeaderRetrievalFn    // Retrieves the head header from the chain
-	headBlock        headBlockRetrievalFn     // Retrieves the head block from the chain
-	headFastBlock    headFastBlockRetrievalFn // Retrieves the head fast-sync block from the chain
-	commitHeadBlock  headBlockCommitterFn     // Commits a manually assembled block as the chain head
-	getTd            tdRetrievalFn            // Retrieves the TD of a block from the chain
-	insertHeaders    headerChainInsertFn      // Injects a batch of headers into the chain
-	insertBlocks     blockChainInsertFn       // Injects a batch of blocks into the chain
-	insertReceipts   receiptChainInsertFn     // Injects a batch of blocks and their receipts into the chain
-	rollback         chainRollbackFn          // Removes a batch of recently added chain links
-	dropPeer         peerDropFn               // Drops a peer for misbehaving
+	dropPeer peerDropFn // Drops a peer for misbehaving
 
 	// Status
 	synchroniseMock func(id string, hash common.Hash) error // Replacement for synchronise during testing
@@ -163,11 +153,56 @@ type Downloader struct {
 	chainInsertHook  func([]*fetchResult)  // Method to call upon inserting a chain of blocks (possibly in multiple invocations)
 }
 
+type LightChain interface {
+	// HasHeader verifies a header's presence in the local chain.
+	HasHeader(common.Hash) bool
+
+	// GetHeaderByHash retrieves a header from the local chain.
+	GetHeaderByHash(common.Hash) *types.Header
+
+	// CurrentHeader retrieves the head header from the local chain.
+	CurrentHeader() *types.Header
+
+	// GetTdByHash returns the total difficulty of a local block.
+	GetTdByHash(common.Hash) *big.Int
+
+	// InsertHeaderChain inserts a batch of headers into the local chain.
+	InsertHeaderChain([]*types.Header, int) (int, error)
+
+	// Rollback removes a few recently added elements from the local chain.
+	Rollback([]common.Hash)
+}
+
+type BlockChain interface {
+	LightChain
+
+	// HasBlockAndState verifies block and associated states' presence in the local chain.
+	HasBlockAndState(common.Hash) bool
+
+	// GetBlockByHash retrieves a block from the local chain.
+	GetBlockByHash(common.Hash) *types.Block
+
+	// CurrentBlock retrieves the head block from the local chain.
+	CurrentBlock() *types.Block
+
+	// CurrentFastBlock retrieves the head fast block from the local chain.
+	CurrentFastBlock() *types.Block
+
+	// FastSyncCommitHead directly commits the head block to a certain entity.
+	FastSyncCommitHead(common.Hash) error
+
+	// InsertChain inserts a batch of blocks into the local chain.
+	InsertChain(types.Blocks) (int, error)
+
+	// InsertReceiptChain inserts a batch of receipts into the local chain.
+	InsertReceiptChain(types.Blocks, []types.Receipts) (int, error)
+}
+
 // New creates a new downloader to fetch hashes and blocks from remote peers.
-func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, hasBlockAndState blockAndStateCheckFn,
-	getHeader headerRetrievalFn, getBlock blockRetrievalFn, headHeader headHeaderRetrievalFn, headBlock headBlockRetrievalFn,
-	headFastBlock headFastBlockRetrievalFn, commitHeadBlock headBlockCommitterFn, getTd tdRetrievalFn, insertHeaders headerChainInsertFn,
-	insertBlocks blockChainInsertFn, insertReceipts receiptChainInsertFn, rollback chainRollbackFn, dropPeer peerDropFn) *Downloader {
+func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, chain BlockChain, lightchain LightChain, dropPeer peerDropFn) *Downloader {
+	if lightchain == nil {
+		lightchain = chain
+	}
 
 	dl := &Downloader{
 		mode:             mode,
@@ -177,19 +212,8 @@ func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, hasHeader he
 		stateDB:          stateDb,
 		rttEstimate:      uint64(rttMaxEstimate),
 		rttConfidence:    uint64(1000000),
-		hasHeader:        hasHeader,
-		hasBlockAndState: hasBlockAndState,
-		getHeader:        getHeader,
-		getBlock:         getBlock,
-		headHeader:       headHeader,
-		headBlock:        headBlock,
-		headFastBlock:    headFastBlock,
-		commitHeadBlock:  commitHeadBlock,
-		getTd:            getTd,
-		insertHeaders:    insertHeaders,
-		insertBlocks:     insertBlocks,
-		insertReceipts:   insertReceipts,
-		rollback:         rollback,
+		chain:            chain,
+		lightchain:       lightchain,
 		dropPeer:         dropPeer,
 		headerCh:         make(chan dataPack, 1),
 		bodyCh:           make(chan dataPack, 1),
@@ -223,11 +247,11 @@ func (d *Downloader) Progress() ethereum.SyncProgress {
 	current := uint64(0)
 	switch d.mode {
 	case FullSync:
-		current = d.headBlock().NumberU64()
+		current = d.chain.CurrentBlock().NumberU64()
 	case FastSync:
-		current = d.headFastBlock().NumberU64()
+		current = d.chain.CurrentFastBlock().NumberU64()
 	case LightSync:
-		current = d.headHeader().Number.Uint64()
+		current = d.lightchain.CurrentHeader().Number.Uint64()
 	}
 	return ethereum.SyncProgress{
 		StartingBlock: d.syncStatsChainOrigin,
@@ -572,13 +596,13 @@ func (d *Downloader) fetchHeight(p *peer) (*types.Header, error) {
 // the head links match), we do a binary search to find the common ancestor.
 func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
 	// Figure out the valid ancestor range to prevent rewrite attacks
-	floor, ceil := int64(-1), d.headHeader().Number.Uint64()
+	floor, ceil := int64(-1), d.lightchain.CurrentHeader().Number.Uint64()
 
 	p.log.Debug("Looking for common ancestor", "local", ceil, "remote", height)
 	if d.mode == FullSync {
-		ceil = d.headBlock().NumberU64()
+		ceil = d.chain.CurrentBlock().NumberU64()
 	} else if d.mode == FastSync {
-		ceil = d.headFastBlock().NumberU64()
+		ceil = d.chain.CurrentFastBlock().NumberU64()
 	}
 	if ceil >= MaxForkAncestry {
 		floor = int64(ceil - MaxForkAncestry)
@@ -638,7 +662,7 @@ func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
 					continue
 				}
 				// Otherwise check if we already know the header or not
-				if (d.mode == FullSync && d.hasBlockAndState(headers[i].Hash())) || (d.mode != FullSync && d.hasHeader(headers[i].Hash())) {
+				if (d.mode == FullSync && d.chain.HasBlockAndState(headers[i].Hash())) || (d.mode != FullSync && d.lightchain.HasHeader(headers[i].Hash())) {
 					number, hash = headers[i].Number.Uint64(), headers[i].Hash()
 
 					// If every header is known, even future ones, the peer straight out lied about its head
@@ -703,11 +727,11 @@ func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
 				arrived = true
 
 				// Modify the search interval based on the response
-				if (d.mode == FullSync && !d.hasBlockAndState(headers[0].Hash())) || (d.mode != FullSync && !d.hasHeader(headers[0].Hash())) {
+				if (d.mode == FullSync && !d.chain.HasBlockAndState(headers[0].Hash())) || (d.mode != FullSync && !d.lightchain.HasHeader(headers[0].Hash())) {
 					end = check
 					break
 				}
-				header := d.getHeader(headers[0].Hash()) // Independent of sync mode, header surely exists
+				header := d.lightchain.GetHeaderByHash(headers[0].Hash()) // Independent of sync mode, header surely exists
 				if header.Number.Uint64() != check {
 					p.log.Debug("Received non requested header", "number", header.Number, "hash", header.Hash(), "request", check)
 					return 0, errBadPeer
@@ -1124,23 +1148,19 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 			for i, header := range rollback {
 				hashes[i] = header.Hash()
 			}
-			lastHeader, lastFastBlock, lastBlock := d.headHeader().Number, common.Big0, common.Big0
-			if d.headFastBlock != nil {
-				lastFastBlock = d.headFastBlock().Number()
-			}
-			if d.headBlock != nil {
-				lastBlock = d.headBlock().Number()
+			lastHeader, lastFastBlock, lastBlock := d.lightchain.CurrentHeader().Number, common.Big0, common.Big0
+			if d.mode != LightSync {
+				lastFastBlock = d.chain.CurrentFastBlock().Number()
+				lastBlock = d.chain.CurrentBlock().Number()
 			}
-			d.rollback(hashes)
+			d.lightchain.Rollback(hashes)
 			curFastBlock, curBlock := common.Big0, common.Big0
-			if d.headFastBlock != nil {
-				curFastBlock = d.headFastBlock().Number()
-			}
-			if d.headBlock != nil {
-				curBlock = d.headBlock().Number()
+			if d.mode != LightSync {
+				curFastBlock = d.chain.CurrentFastBlock().Number()
+				curBlock = d.chain.CurrentBlock().Number()
 			}
 			log.Warn("Rolled back headers", "count", len(hashes),
-				"header", fmt.Sprintf("%d->%d", lastHeader, d.headHeader().Number),
+				"header", fmt.Sprintf("%d->%d", lastHeader, d.lightchain.CurrentHeader().Number),
 				"fast", fmt.Sprintf("%d->%d", lastFastBlock, curFastBlock),
 				"block", fmt.Sprintf("%d->%d", lastBlock, curBlock))
 
@@ -1190,7 +1210,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 				// L: Request new headers up from 11 (R's TD was higher, it must have something)
 				// R: Nothing to give
 				if d.mode != LightSync {
-					if !gotHeaders && td.Cmp(d.getTd(d.headBlock().Hash())) > 0 {
+					if !gotHeaders && td.Cmp(d.chain.GetTdByHash(d.chain.CurrentBlock().Hash())) > 0 {
 						return errStallingPeer
 					}
 				}
@@ -1202,7 +1222,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 				// queued for processing when the header download completes. However, as long as the
 				// peer gave us something useful, we're already happy/progressed (above check).
 				if d.mode == FastSync || d.mode == LightSync {
-					if td.Cmp(d.getTd(d.headHeader().Hash())) > 0 {
+					if td.Cmp(d.lightchain.GetTdByHash(d.lightchain.CurrentHeader().Hash())) > 0 {
 						return errStallingPeer
 					}
 				}
@@ -1232,7 +1252,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 					// Collect the yet unknown headers to mark them as uncertain
 					unknown := make([]*types.Header, 0, len(headers))
 					for _, header := range chunk {
-						if !d.hasHeader(header.Hash()) {
+						if !d.lightchain.HasHeader(header.Hash()) {
 							unknown = append(unknown, header)
 						}
 					}
@@ -1241,7 +1261,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 					if chunk[len(chunk)-1].Number.Uint64()+uint64(fsHeaderForceVerify) > pivot {
 						frequency = 1
 					}
-					if n, err := d.insertHeaders(chunk, frequency); err != nil {
+					if n, err := d.chain.InsertHeaderChain(chunk, frequency); err != nil {
 						// If some headers were inserted, add them too to the rollback list
 						if n > 0 {
 							rollback = append(rollback, chunk[:n]...)
@@ -1328,7 +1348,7 @@ func (d *Downloader) importBlockResults(results []*fetchResult) error {
 		for i, result := range results[:items] {
 			blocks[i] = types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles)
 		}
-		if index, err := d.insertBlocks(blocks); err != nil {
+		if index, err := d.chain.InsertChain(blocks); err != nil {
 			log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
 			return errInvalidChain
 		}
@@ -1368,6 +1388,7 @@ func (d *Downloader) processFastSyncContent(latest *types.Header) error {
 			stateSync.Cancel()
 			if err := d.commitPivotBlock(P); err != nil {
 				return err
+
 			}
 		}
 		if err := d.importBlockResults(afterP); err != nil {
@@ -1416,7 +1437,7 @@ func (d *Downloader) commitFastSyncData(results []*fetchResult, stateSync *state
 			blocks[i] = types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles)
 			receipts[i] = result.Receipts
 		}
-		if index, err := d.insertReceipts(blocks, receipts); err != nil {
+		if index, err := d.chain.InsertReceiptChain(blocks, receipts); err != nil {
 			log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
 			return errInvalidChain
 		}
@@ -1434,10 +1455,10 @@ func (d *Downloader) commitPivotBlock(result *fetchResult) error {
 		return err
 	}
 	log.Debug("Committing fast sync pivot as new head", "number", b.Number(), "hash", b.Hash())
-	if _, err := d.insertReceipts([]*types.Block{b}, []types.Receipts{result.Receipts}); err != nil {
+	if _, err := d.chain.InsertReceiptChain([]*types.Block{b}, []types.Receipts{result.Receipts}); err != nil {
 		return err
 	}
-	return d.commitHeadBlock(b.Hash())
+	return d.chain.FastSyncCommitHead(b.Hash())
 }
 
 // DeliverHeaders injects a new batch of block headers received from a remote
diff --git a/eth/downloader/downloader_test.go b/eth/downloader/downloader_test.go
index 1fb5a0910..5852127ea 100644
--- a/eth/downloader/downloader_test.go
+++ b/eth/downloader/downloader_test.go
@@ -96,9 +96,7 @@ func newTester() *downloadTester {
 	tester.stateDb, _ = ethdb.NewMemDatabase()
 	tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})
 
-	tester.downloader = New(FullSync, tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
-		tester.getBlock, tester.headHeader, tester.headBlock, tester.headFastBlock, tester.commitHeadBlock, tester.getTd,
-		tester.insertHeaders, tester.insertBlocks, tester.insertReceipts, tester.rollback, tester.dropPeer)
+	tester.downloader = New(FullSync, tester.stateDb, new(event.TypeMux), tester, nil, tester.dropPeer)
 
 	return tester
 }
@@ -218,14 +216,14 @@ func (dl *downloadTester) sync(id string, td *big.Int, mode SyncMode) error {
 	return err
 }
 
-// hasHeader checks if a header is present in the testers canonical chain.
-func (dl *downloadTester) hasHeader(hash common.Hash) bool {
-	return dl.getHeader(hash) != nil
+// HasHeader checks if a header is present in the testers canonical chain.
+func (dl *downloadTester) HasHeader(hash common.Hash) bool {
+	return dl.GetHeaderByHash(hash) != nil
 }
 
-// hasBlock checks if a block and associated state is present in the testers canonical chain.
-func (dl *downloadTester) hasBlock(hash common.Hash) bool {
-	block := dl.getBlock(hash)
+// HasBlockAndState checks if a block and associated state is present in the testers canonical chain.
+func (dl *downloadTester) HasBlockAndState(hash common.Hash) bool {
+	block := dl.GetBlockByHash(hash)
 	if block == nil {
 		return false
 	}
@@ -233,24 +231,24 @@ func (dl *downloadTester) hasBlock(hash common.Hash) bool {
 	return err == nil
 }
 
-// getHeader retrieves a header from the testers canonical chain.
-func (dl *downloadTester) getHeader(hash common.Hash) *types.Header {
+// GetHeader retrieves a header from the testers canonical chain.
+func (dl *downloadTester) GetHeaderByHash(hash common.Hash) *types.Header {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
 	return dl.ownHeaders[hash]
 }
 
-// getBlock retrieves a block from the testers canonical chain.
-func (dl *downloadTester) getBlock(hash common.Hash) *types.Block {
+// GetBlock retrieves a block from the testers canonical chain.
+func (dl *downloadTester) GetBlockByHash(hash common.Hash) *types.Block {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
 	return dl.ownBlocks[hash]
 }
 
-// headHeader retrieves the current head header from the canonical chain.
-func (dl *downloadTester) headHeader() *types.Header {
+// CurrentHeader retrieves the current head header from the canonical chain.
+func (dl *downloadTester) CurrentHeader() *types.Header {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
@@ -262,8 +260,8 @@ func (dl *downloadTester) headHeader() *types.Header {
 	return dl.genesis.Header()
 }
 
-// headBlock retrieves the current head block from the canonical chain.
-func (dl *downloadTester) headBlock() *types.Block {
+// CurrentBlock retrieves the current head block from the canonical chain.
+func (dl *downloadTester) CurrentBlock() *types.Block {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
@@ -277,8 +275,8 @@ func (dl *downloadTester) headBlock() *types.Block {
 	return dl.genesis
 }
 
-// headFastBlock retrieves the current head fast-sync block from the canonical chain.
-func (dl *downloadTester) headFastBlock() *types.Block {
+// CurrentFastBlock retrieves the current head fast-sync block from the canonical chain.
+func (dl *downloadTester) CurrentFastBlock() *types.Block {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
@@ -290,26 +288,26 @@ func (dl *downloadTester) headFastBlock() *types.Block {
 	return dl.genesis
 }
 
-// commitHeadBlock manually sets the head block to a given hash.
-func (dl *downloadTester) commitHeadBlock(hash common.Hash) error {
+// FastSynccommitHead manually sets the head block to a given hash.
+func (dl *downloadTester) FastSyncCommitHead(hash common.Hash) error {
 	// For now only check that the state trie is correct
-	if block := dl.getBlock(hash); block != nil {
+	if block := dl.GetBlockByHash(hash); block != nil {
 		_, err := trie.NewSecure(block.Root(), dl.stateDb, 0)
 		return err
 	}
 	return fmt.Errorf("non existent block: %x", hash[:4])
 }
 
-// getTd retrieves the block's total difficulty from the canonical chain.
-func (dl *downloadTester) getTd(hash common.Hash) *big.Int {
+// GetTdByHash retrieves the block's total difficulty from the canonical chain.
+func (dl *downloadTester) GetTdByHash(hash common.Hash) *big.Int {
 	dl.lock.RLock()
 	defer dl.lock.RUnlock()
 
 	return dl.ownChainTd[hash]
 }
 
-// insertHeaders injects a new batch of headers into the simulated chain.
-func (dl *downloadTester) insertHeaders(headers []*types.Header, checkFreq int) (int, error) {
+// InsertHeaderChain injects a new batch of headers into the simulated chain.
+func (dl *downloadTester) InsertHeaderChain(headers []*types.Header, checkFreq int) (int, error) {
 	dl.lock.Lock()
 	defer dl.lock.Unlock()
 
@@ -337,8 +335,8 @@ func (dl *downloadTester) insertHeaders(headers []*types.Header, checkFreq int)
 	return len(headers), nil
 }
 
-// insertBlocks injects a new batch of blocks into the simulated chain.
-func (dl *downloadTester) insertBlocks(blocks types.Blocks) (int, error) {
+// InsertChain injects a new batch of blocks into the simulated chain.
+func (dl *downloadTester) InsertChain(blocks types.Blocks) (int, error) {
 	dl.lock.Lock()
 	defer dl.lock.Unlock()
 
@@ -359,8 +357,8 @@ func (dl *downloadTester) insertBlocks(blocks types.Blocks) (int, error) {
 	return len(blocks), nil
 }
 
-// insertReceipts injects a new batch of receipts into the simulated chain.
-func (dl *downloadTester) insertReceipts(blocks types.Blocks, receipts []types.Receipts) (int, error) {
+// InsertReceiptChain injects a new batch of receipts into the simulated chain.
+func (dl *downloadTester) InsertReceiptChain(blocks types.Blocks, receipts []types.Receipts) (int, error) {
 	dl.lock.Lock()
 	defer dl.lock.Unlock()
 
@@ -377,8 +375,8 @@ func (dl *downloadTester) insertReceipts(blocks types.Blocks, receipts []types.R
 	return len(blocks), nil
 }
 
-// rollback removes some recently added elements from the chain.
-func (dl *downloadTester) rollback(hashes []common.Hash) {
+// Rollback removes some recently added elements from the chain.
+func (dl *downloadTester) Rollback(hashes []common.Hash) {
 	dl.lock.Lock()
 	defer dl.lock.Unlock()
 
@@ -1212,7 +1210,7 @@ func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
 	if err := tester.sync("fast-attack", nil, mode); err == nil {
 		t.Fatalf("succeeded fast attacker synchronisation")
 	}
-	if head := tester.headHeader().Number.Int64(); int(head) > MaxHeaderFetch {
+	if head := tester.CurrentHeader().Number.Int64(); int(head) > MaxHeaderFetch {
 		t.Errorf("rollback head mismatch: have %v, want at most %v", head, MaxHeaderFetch)
 	}
 	// Attempt to sync with an attacker that feeds junk during the block import phase.
@@ -1226,11 +1224,11 @@ func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
 	if err := tester.sync("block-attack", nil, mode); err == nil {
 		t.Fatalf("succeeded block attacker synchronisation")
 	}
-	if head := tester.headHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
+	if head := tester.CurrentHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
 		t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
 	}
 	if mode == FastSync {
-		if head := tester.headBlock().NumberU64(); head != 0 {
+		if head := tester.CurrentBlock().NumberU64(); head != 0 {
 			t.Errorf("fast sync pivot block #%d not rolled back", head)
 		}
 	}
@@ -1251,11 +1249,11 @@ func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
 	if err := tester.sync("withhold-attack", nil, mode); err == nil {
 		t.Fatalf("succeeded withholding attacker synchronisation")
 	}
-	if head := tester.headHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
+	if head := tester.CurrentHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
 		t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
 	}
 	if mode == FastSync {
-		if head := tester.headBlock().NumberU64(); head != 0 {
+		if head := tester.CurrentBlock().NumberU64(); head != 0 {
 			t.Errorf("fast sync pivot block #%d not rolled back", head)
 		}
 	}
diff --git a/eth/downloader/types.go b/eth/downloader/types.go
index e10510486..3f30ea9dd 100644
--- a/eth/downloader/types.go
+++ b/eth/downloader/types.go
@@ -18,51 +18,10 @@ package downloader
 
 import (
 	"fmt"
-	"math/big"
 
-	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 )
 
-// headerCheckFn is a callback type for verifying a header's presence in the local chain.
-type headerCheckFn func(common.Hash) bool
-
-// blockAndStateCheckFn is a callback type for verifying block and associated states' presence in the local chain.
-type blockAndStateCheckFn func(common.Hash) bool
-
-// headerRetrievalFn is a callback type for retrieving a header from the local chain.
-type headerRetrievalFn func(common.Hash) *types.Header
-
-// blockRetrievalFn is a callback type for retrieving a block from the local chain.
-type blockRetrievalFn func(common.Hash) *types.Block
-
-// headHeaderRetrievalFn is a callback type for retrieving the head header from the local chain.
-type headHeaderRetrievalFn func() *types.Header
-
-// headBlockRetrievalFn is a callback type for retrieving the head block from the local chain.
-type headBlockRetrievalFn func() *types.Block
-
-// headFastBlockRetrievalFn is a callback type for retrieving the head fast block from the local chain.
-type headFastBlockRetrievalFn func() *types.Block
-
-// headBlockCommitterFn is a callback for directly committing the head block to a certain entity.
-type headBlockCommitterFn func(common.Hash) error
-
-// tdRetrievalFn is a callback type for retrieving the total difficulty of a local block.
-type tdRetrievalFn func(common.Hash) *big.Int
-
-// headerChainInsertFn is a callback type to insert a batch of headers into the local chain.
-type headerChainInsertFn func([]*types.Header, int) (int, error)
-
-// blockChainInsertFn is a callback type to insert a batch of blocks into the local chain.
-type blockChainInsertFn func(types.Blocks) (int, error)
-
-// receiptChainInsertFn is a callback type to insert a batch of receipts into the local chain.
-type receiptChainInsertFn func(types.Blocks, []types.Receipts) (int, error)
-
-// chainRollbackFn is a callback type to remove a few recently added elements from the local chain.
-type chainRollbackFn func([]common.Hash)
-
 // peerDropFn is a callback type for dropping a peer detected as malicious.
 type peerDropFn func(id string)
 
diff --git a/eth/handler.go b/eth/handler.go
index 1af9e755b..8d026c775 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -157,10 +157,7 @@ func NewProtocolManager(config *params.ChainConfig, mode downloader.SyncMode, ne
 		return nil, errIncompatibleConfig
 	}
 	// Construct the different synchronisation mechanisms
-	manager.downloader = downloader.New(mode, chaindb, manager.eventMux, blockchain.HasHeader, blockchain.HasBlockAndState, blockchain.GetHeaderByHash,
-		blockchain.GetBlockByHash, blockchain.CurrentHeader, blockchain.CurrentBlock, blockchain.CurrentFastBlock, blockchain.FastSyncCommitHead,
-		blockchain.GetTdByHash, blockchain.InsertHeaderChain, manager.blockchain.InsertChain, blockchain.InsertReceiptChain, blockchain.Rollback,
-		manager.removePeer)
+	manager.downloader = downloader.New(mode, chaindb, manager.eventMux, blockchain, nil, manager.removePeer)
 
 	validator := func(header *types.Header) error {
 		return engine.VerifyHeader(blockchain, header, true)
diff --git a/les/handler.go b/les/handler.go
index 77bc077a2..afd4356ef 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -206,9 +206,7 @@ func NewProtocolManager(chainConfig *params.ChainConfig, lightSync bool, network
 	}
 
 	if lightSync {
-		manager.downloader = downloader.New(downloader.LightSync, chainDb, manager.eventMux, blockchain.HasHeader, nil, blockchain.GetHeaderByHash,
-			nil, blockchain.CurrentHeader, nil, nil, nil, blockchain.GetTdByHash,
-			blockchain.InsertHeaderChain, nil, nil, blockchain.Rollback, removePeer)
+		manager.downloader = downloader.New(downloader.LightSync, chainDb, manager.eventMux, nil, blockchain, removePeer)
 		manager.peers.notify((*downloaderPeerNotify)(manager))
 		manager.fetcher = newLightFetcher(manager)
 	}
diff --git a/light/lightchain.go b/light/lightchain.go
index 87436f4a5..ec7ca3a0c 100644
--- a/light/lightchain.go
+++ b/light/lightchain.go
@@ -389,6 +389,21 @@ func (self *LightChain) CurrentHeader() *types.Header {
 	return self.hc.CurrentHeader()
 }
 
+// CurrentBlock exists for interface compatibility and always returns nil
+func (self *LightChain) CurrentBlock() *types.Block {
+	return nil
+}
+
+// CurrentFastBlock exists for interface compatibility and always returns nil
+func (self *LightChain) CurrentFastBlock() *types.Block {
+	return nil
+}
+
+// FastSyncCommitHead exists for interface compatibility and does nothing
+func (self *LightChain) FastSyncCommitHead(h common.Hash) error {
+	return nil
+}
+
 // GetTd retrieves a block's total difficulty in the canonical chain from the
 // database by hash and number, caching it if found.
 func (self *LightChain) GetTd(hash common.Hash, number uint64) *big.Int {