light: CHT and bloom trie indexers working in light mode (#16534)

This PR enables the indexers to work in light client mode by
downloading a part of these tries (the Merkle proofs of the last
values of the last known section) in order to be able to add new
values and recalculate subsequent hashes. It also adds CHT data to
NodeInfo.

core/chain_indexer.go

@@ -17,6 +17,7 @@
 package core
 
 import (
+	"context"
 	"encoding/binary"
 	"fmt"
 	"sync"
@@ -37,11 +38,11 @@ import (
 type ChainIndexerBackend interface {
 	// Reset initiates the processing of a new chain segment, potentially terminating
 	// any partially completed operations (in case of a reorg).
-	Reset(section uint64, prevHead common.Hash) error
+	Reset(ctx context.Context, section uint64, prevHead common.Hash) error
 
 	// Process crunches through the next header in the chain segment. The caller
 	// will ensure a sequential order of headers.
-	Process(header *types.Header)
+	Process(ctx context.Context, header *types.Header) error
 
 	// Commit finalizes the section metadata and stores it into the database.
 	Commit() error
@@ -71,9 +72,11 @@ type ChainIndexer struct {
 	backend  ChainIndexerBackend // Background processor generating the index data content
 	children []*ChainIndexer     // Child indexers to cascade chain updates to
 
-	active uint32          // Flag whether the event loop was started
+	active    uint32          // Flag whether the event loop was started
-	update chan struct{}   // Notification channel that headers should be processed
+	update    chan struct{}   // Notification channel that headers should be processed
-	quit   chan chan error // Quit channel to tear down running goroutines
+	quit      chan chan error // Quit channel to tear down running goroutines
+	ctx       context.Context
+	ctxCancel func()
 
 	sectionSize uint64 // Number of blocks in a single chain segment to process
 	confirmsReq uint64 // Number of confirmations before processing a completed segment
@@ -105,6 +108,8 @@ func NewChainIndexer(chainDb, indexDb ethdb.Database, backend ChainIndexerBacken
 	}
 	// Initialize database dependent fields and start the updater
 	c.loadValidSections()
+	c.ctx, c.ctxCancel = context.WithCancel(context.Background())
+
 	go c.updateLoop()
 
 	return c
@@ -138,6 +143,8 @@ func (c *ChainIndexer) Start(chain ChainIndexerChain) {
 func (c *ChainIndexer) Close() error {
 	var errs []error
 
+	c.ctxCancel()
+
 	// Tear down the primary update loop
 	errc := make(chan error)
 	c.quit <- errc
@@ -297,6 +304,12 @@ func (c *ChainIndexer) updateLoop() {
 				c.lock.Unlock()
 				newHead, err := c.processSection(section, oldHead)
 				if err != nil {
+					select {
+					case <-c.ctx.Done():
+						<-c.quit <- nil
+						return
+					default:
+					}
 					c.log.Error("Section processing failed", "error", err)
 				}
 				c.lock.Lock()
@@ -344,7 +357,7 @@ func (c *ChainIndexer) processSection(section uint64, lastHead common.Hash) (com
 
 	// Reset and partial processing
 
-	if err := c.backend.Reset(section, lastHead); err != nil {
+	if err := c.backend.Reset(c.ctx, section, lastHead); err != nil {
 		c.setValidSections(0)
 		return common.Hash{}, err
 	}
@@ -360,11 +373,12 @@ func (c *ChainIndexer) processSection(section uint64, lastHead common.Hash) (com
 		} else if header.ParentHash != lastHead {
 			return common.Hash{}, fmt.Errorf("chain reorged during section processing")
 		}
-		c.backend.Process(header)
+		if err := c.backend.Process(c.ctx, header); err != nil {
+			return common.Hash{}, err
+		}
 		lastHead = header.Hash()
 	}
 	if err := c.backend.Commit(); err != nil {
-		c.log.Error("Section commit failed", "error", err)
 		return common.Hash{}, err
 	}
 	return lastHead, nil

core/chain_indexer_test.go

@@ -17,6 +17,7 @@
 package core
 
 import (
+	"context"
 	"fmt"
 	"math/big"
 	"math/rand"
@@ -210,13 +211,13 @@ func (b *testChainIndexBackend) reorg(headNum uint64) uint64 {
 	return b.stored * b.indexer.sectionSize
 }
 
-func (b *testChainIndexBackend) Reset(section uint64, prevHead common.Hash) error {
+func (b *testChainIndexBackend) Reset(ctx context.Context, section uint64, prevHead common.Hash) error {
 	b.section = section
 	b.headerCnt = 0
 	return nil
 }
 
-func (b *testChainIndexBackend) Process(header *types.Header) {
+func (b *testChainIndexBackend) Process(ctx context.Context, header *types.Header) error {
 	b.headerCnt++
 	if b.headerCnt > b.indexer.sectionSize {
 		b.t.Error("Processing too many headers")
@@ -227,6 +228,7 @@ func (b *testChainIndexBackend) Process(header *types.Header) {
 		b.t.Fatal("Unexpected call to Process")
 	case b.processCh <- header.Number.Uint64():
 	}
+	return nil
 }
 
 func (b *testChainIndexBackend) Commit() error {

eth/backend.go

@@ -130,7 +130,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		gasPrice:       config.GasPrice,
 		etherbase:      config.Etherbase,
 		bloomRequests:  make(chan chan *bloombits.Retrieval),
-		bloomIndexer:   NewBloomIndexer(chainDb, params.BloomBitsBlocks),
+		bloomIndexer:   NewBloomIndexer(chainDb, params.BloomBitsBlocks, bloomConfirms),
 	}
 
 	log.Info("Initialising Ethereum protocol", "versions", ProtocolVersions, "network", config.NetworkId)

eth/bloombits.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"context"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -92,30 +93,28 @@ const (
 // BloomIndexer implements a core.ChainIndexer, building up a rotated bloom bits index
 // for the Ethereum header bloom filters, permitting blazing fast filtering.
 type BloomIndexer struct {
-	size uint64 // section size to generate bloombits for
+	size    uint64               // section size to generate bloombits for
-
+	db      ethdb.Database       // database instance to write index data and metadata into
-	db  ethdb.Database       // database instance to write index data and metadata into
+	gen     *bloombits.Generator // generator to rotate the bloom bits crating the bloom index
-	gen *bloombits.Generator // generator to rotate the bloom bits crating the bloom index
+	section uint64               // Section is the section number being processed currently
-
+	head    common.Hash          // Head is the hash of the last header processed
-	section uint64      // Section is the section number being processed currently
-	head    common.Hash // Head is the hash of the last header processed
 }
 
 // NewBloomIndexer returns a chain indexer that generates bloom bits data for the
 // canonical chain for fast logs filtering.
-func NewBloomIndexer(db ethdb.Database, size uint64) *core.ChainIndexer {
+func NewBloomIndexer(db ethdb.Database, size, confReq uint64) *core.ChainIndexer {
 	backend := &BloomIndexer{
 		db:   db,
 		size: size,
 	}
 	table := ethdb.NewTable(db, string(rawdb.BloomBitsIndexPrefix))
 
-	return core.NewChainIndexer(db, table, backend, size, bloomConfirms, bloomThrottling, "bloombits")
+	return core.NewChainIndexer(db, table, backend, size, confReq, bloomThrottling, "bloombits")
 }
 
 // Reset implements core.ChainIndexerBackend, starting a new bloombits index
 // section.
-func (b *BloomIndexer) Reset(section uint64, lastSectionHead common.Hash) error {
+func (b *BloomIndexer) Reset(ctx context.Context, section uint64, lastSectionHead common.Hash) error {
 	gen, err := bloombits.NewGenerator(uint(b.size))
 	b.gen, b.section, b.head = gen, section, common.Hash{}
 	return err
@@ -123,16 +122,16 @@ func (b *BloomIndexer) Reset(section uint64, lastSectionHead common.Hash) error
 
 // Process implements core.ChainIndexerBackend, adding a new header's bloom into
 // the index.
-func (b *BloomIndexer) Process(header *types.Header) {
+func (b *BloomIndexer) Process(ctx context.Context, header *types.Header) error {
 	b.gen.AddBloom(uint(header.Number.Uint64()-b.section*b.size), header.Bloom)
 	b.head = header.Hash()
+	return nil
 }
 
 // Commit implements core.ChainIndexerBackend, finalizing the bloom section and
 // writing it out into the database.
 func (b *BloomIndexer) Commit() error {
 	batch := b.db.NewBatch()
-
 	for i := 0; i < types.BloomBitLength; i++ {
 		bits, err := b.gen.Bitset(uint(i))
 		if err != nil {

les/backend.go

@@ -95,29 +95,35 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	quitSync := make(chan struct{})
 
 	leth := &LightEthereum{
-		config:           config,
+		config:         config,
-		chainConfig:      chainConfig,
+		chainConfig:    chainConfig,
-		chainDb:          chainDb,
+		chainDb:        chainDb,
-		eventMux:         ctx.EventMux,
+		eventMux:       ctx.EventMux,
-		peers:            peers,
+		peers:          peers,
-		reqDist:          newRequestDistributor(peers, quitSync),
+		reqDist:        newRequestDistributor(peers, quitSync),
-		accountManager:   ctx.AccountManager,
+		accountManager: ctx.AccountManager,
-		engine:           eth.CreateConsensusEngine(ctx, chainConfig, &config.Ethash, nil, chainDb),
+		engine:         eth.CreateConsensusEngine(ctx, chainConfig, &config.Ethash, nil, chainDb),
-		shutdownChan:     make(chan bool),
+		shutdownChan:   make(chan bool),
-		networkId:        config.NetworkId,
+		networkId:      config.NetworkId,
-		bloomRequests:    make(chan chan *bloombits.Retrieval),
+		bloomRequests:  make(chan chan *bloombits.Retrieval),
-		bloomIndexer:     eth.NewBloomIndexer(chainDb, light.BloomTrieFrequency),
+		bloomIndexer:   eth.NewBloomIndexer(chainDb, light.BloomTrieFrequency, light.HelperTrieConfirmations),
-		chtIndexer:       light.NewChtIndexer(chainDb, true),
-		bloomTrieIndexer: light.NewBloomTrieIndexer(chainDb, true),
 	}
 
 	leth.relay = NewLesTxRelay(peers, leth.reqDist)
 	leth.serverPool = newServerPool(chainDb, quitSync, &leth.wg)
 	leth.retriever = newRetrieveManager(peers, leth.reqDist, leth.serverPool)
-	leth.odr = NewLesOdr(chainDb, leth.chtIndexer, leth.bloomTrieIndexer, leth.bloomIndexer, leth.retriever)
+	leth.odr = NewLesOdr(chainDb, leth.retriever)
+	leth.chtIndexer = light.NewChtIndexer(chainDb, true, leth.odr)
+	leth.bloomTrieIndexer = light.NewBloomTrieIndexer(chainDb, true, leth.odr)
+	leth.odr.SetIndexers(leth.chtIndexer, leth.bloomTrieIndexer, leth.bloomIndexer)
+	// Note: NewLightChain adds the trusted checkpoint so it needs an ODR with
+	// indexers already set but not started yet
 	if leth.blockchain, err = light.NewLightChain(leth.odr, leth.chainConfig, leth.engine); err != nil {
 		return nil, err
 	}
+	// Note: AddChildIndexer starts the update process for the child
+	leth.bloomIndexer.AddChildIndexer(leth.bloomTrieIndexer)
+	leth.chtIndexer.Start(leth.blockchain)
 	leth.bloomIndexer.Start(leth.blockchain)
 	// Rewind the chain in case of an incompatible config upgrade.
 	if compat, ok := genesisErr.(*params.ConfigCompatError); ok {
@@ -242,9 +248,6 @@ func (s *LightEthereum) Stop() error {
 	if s.chtIndexer != nil {
 		s.chtIndexer.Close()
 	}
-	if s.bloomTrieIndexer != nil {
-		s.bloomTrieIndexer.Close()
-	}
 	s.blockchain.Stop()
 	s.protocolManager.Stop()
 	s.txPool.Stop()

les/distributor.go

@@ -20,14 +20,10 @@ package les
 
 import (
 	"container/list"
-	"errors"
 	"sync"
 	"time"
 )
 
-// ErrNoPeers is returned if no peers capable of serving a queued request are available
-var ErrNoPeers = errors.New("no suitable peers available")
-
 // requestDistributor implements a mechanism that distributes requests to
 // suitable peers, obeying flow control rules and prioritizing them in creation
 // order (even when a resend is necessary).

les/handler.go

@@ -1206,11 +1206,12 @@ func (pm *ProtocolManager) txStatus(hashes []common.Hash) []txStatus {
 // NodeInfo represents a short summary of the Ethereum sub-protocol metadata
 // known about the host peer.
 type NodeInfo struct {
-	Network    uint64              `json:"network"`    // Ethereum network ID (1=Frontier, 2=Morden, Ropsten=3, Rinkeby=4)
+	Network    uint64                  `json:"network"`    // Ethereum network ID (1=Frontier, 2=Morden, Ropsten=3, Rinkeby=4)
-	Difficulty *big.Int            `json:"difficulty"` // Total difficulty of the host's blockchain
+	Difficulty *big.Int                `json:"difficulty"` // Total difficulty of the host's blockchain
-	Genesis    common.Hash         `json:"genesis"`    // SHA3 hash of the host's genesis block
+	Genesis    common.Hash             `json:"genesis"`    // SHA3 hash of the host's genesis block
-	Config     *params.ChainConfig `json:"config"`     // Chain configuration for the fork rules
+	Config     *params.ChainConfig     `json:"config"`     // Chain configuration for the fork rules
-	Head       common.Hash         `json:"head"`       // SHA3 hash of the host's best owned block
+	Head       common.Hash             `json:"head"`       // SHA3 hash of the host's best owned block
+	CHT        light.TrustedCheckpoint `json:"cht"`        // Trused CHT checkpoint for fast catchup
 }
 
 // NodeInfo retrieves some protocol metadata about the running host node.
@@ -1218,12 +1219,31 @@ func (self *ProtocolManager) NodeInfo() *NodeInfo {
 	head := self.blockchain.CurrentHeader()
 	hash := head.Hash()
 
+	var cht light.TrustedCheckpoint
+
+	sections, _, sectionHead := self.odr.ChtIndexer().Sections()
+	sections2, _, sectionHead2 := self.odr.BloomTrieIndexer().Sections()
+	if sections2 < sections {
+		sections = sections2
+		sectionHead = sectionHead2
+	}
+	if sections > 0 {
+		sectionIndex := sections - 1
+		cht = light.TrustedCheckpoint{
+			SectionIdx:  sectionIndex,
+			SectionHead: sectionHead,
+			CHTRoot:     light.GetChtRoot(self.chainDb, sectionIndex, sectionHead),
+			BloomRoot:   light.GetBloomTrieRoot(self.chainDb, sectionIndex, sectionHead),
+		}
+	}
+
 	return &NodeInfo{
 		Network:    self.networkId,
 		Difficulty: self.blockchain.GetTd(hash, head.Number.Uint64()),
 		Genesis:    self.blockchain.Genesis().Hash(),
 		Config:     self.blockchain.Config(),
 		Head:       hash,
+		CHT:        cht,
 	}
 }
 
@@ -1258,7 +1278,7 @@ func (pc *peerConnection) RequestHeadersByHash(origin common.Hash, amount int, s
 	}
 	_, ok := <-pc.manager.reqDist.queue(rq)
 	if !ok {
-		return ErrNoPeers
+		return light.ErrNoPeers
 	}
 	return nil
 }
@@ -1282,7 +1302,7 @@ func (pc *peerConnection) RequestHeadersByNumber(origin uint64, amount int, skip
 	}
 	_, ok := <-pc.manager.reqDist.queue(rq)
 	if !ok {
-		return ErrNoPeers
+		return light.ErrNoPeers
 	}
 	return nil
 }

les/helper_test.go

@@ -156,12 +156,12 @@ func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *cor
 	} else {
 		blockchain, _ := core.NewBlockChain(db, nil, gspec.Config, engine, vm.Config{})
 
-		chtIndexer := light.NewChtIndexer(db, false)
+		chtIndexer := light.NewChtIndexer(db, false, nil)
 		chtIndexer.Start(blockchain)
 
-		bbtIndexer := light.NewBloomTrieIndexer(db, false)
+		bbtIndexer := light.NewBloomTrieIndexer(db, false, nil)
 
-		bloomIndexer := eth.NewBloomIndexer(db, params.BloomBitsBlocks)
+		bloomIndexer := eth.NewBloomIndexer(db, params.BloomBitsBlocks, light.HelperTrieProcessConfirmations)
 		bloomIndexer.AddChildIndexer(bbtIndexer)
 		bloomIndexer.Start(blockchain)
 

les/odr.go

@@ -33,14 +33,11 @@ type LesOdr struct {
 	stop                                       chan struct{}
 }
 
-func NewLesOdr(db ethdb.Database, chtIndexer, bloomTrieIndexer, bloomIndexer *core.ChainIndexer, retriever *retrieveManager) *LesOdr {
+func NewLesOdr(db ethdb.Database, retriever *retrieveManager) *LesOdr {
 	return &LesOdr{
-		db:               db,
+		db:        db,
-		chtIndexer:       chtIndexer,
+		retriever: retriever,
-		bloomTrieIndexer: bloomTrieIndexer,
+		stop:      make(chan struct{}),
-		bloomIndexer:     bloomIndexer,
-		retriever:        retriever,
-		stop:             make(chan struct{}),
 	}
 }
 
@@ -54,6 +51,13 @@ func (odr *LesOdr) Database() ethdb.Database {
 	return odr.db
 }
 
+// SetIndexers adds the necessary chain indexers to the ODR backend
+func (odr *LesOdr) SetIndexers(chtIndexer, bloomTrieIndexer, bloomIndexer *core.ChainIndexer) {
+	odr.chtIndexer = chtIndexer
+	odr.bloomTrieIndexer = bloomTrieIndexer
+	odr.bloomIndexer = bloomIndexer
+}
+
 // ChtIndexer returns the CHT chain indexer
 func (odr *LesOdr) ChtIndexer() *core.ChainIndexer {
 	return odr.chtIndexer

les/odr_test.go

@@ -167,7 +167,8 @@ func testOdr(t *testing.T, protocol int, expFail uint64, fn odrTestFn) {
 	rm := newRetrieveManager(peers, dist, nil)
 	db := ethdb.NewMemDatabase()
 	ldb := ethdb.NewMemDatabase()
-	odr := NewLesOdr(ldb, light.NewChtIndexer(db, true), light.NewBloomTrieIndexer(db, true), eth.NewBloomIndexer(db, light.BloomTrieFrequency), rm)
+	odr := NewLesOdr(ldb, rm)
+	odr.SetIndexers(light.NewChtIndexer(db, true, nil), light.NewBloomTrieIndexer(db, true, nil), eth.NewBloomIndexer(db, light.BloomTrieFrequency, light.HelperTrieConfirmations))
 	pm := newTestProtocolManagerMust(t, false, 4, testChainGen, nil, nil, db)
 	lpm := newTestProtocolManagerMust(t, true, 0, nil, peers, odr, ldb)
 	_, err1, lpeer, err2 := newTestPeerPair("peer", protocol, pm, lpm)

les/request_test.go

@@ -89,7 +89,8 @@ func testAccess(t *testing.T, protocol int, fn accessTestFn) {
 	rm := newRetrieveManager(peers, dist, nil)
 	db := ethdb.NewMemDatabase()
 	ldb := ethdb.NewMemDatabase()
-	odr := NewLesOdr(ldb, light.NewChtIndexer(db, true), light.NewBloomTrieIndexer(db, true), eth.NewBloomIndexer(db, light.BloomTrieFrequency), rm)
+	odr := NewLesOdr(ldb, rm)
+	odr.SetIndexers(light.NewChtIndexer(db, true, nil), light.NewBloomTrieIndexer(db, true, nil), eth.NewBloomIndexer(db, light.BloomTrieFrequency, light.HelperTrieConfirmations))
 
 	pm := newTestProtocolManagerMust(t, false, 4, testChainGen, nil, nil, db)
 	lpm := newTestProtocolManagerMust(t, true, 0, nil, peers, odr, ldb)

les/retrieve.go

@@ -27,6 +27,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
+	"github.com/ethereum/go-ethereum/light"
 )
 
 var (
@@ -207,7 +208,7 @@ func (r *sentReq) stateRequesting() reqStateFn {
 					return r.stateNoMorePeers
 				}
 				// nothing to wait for, no more peers to ask, return with error
-				r.stop(ErrNoPeers)
+				r.stop(light.ErrNoPeers)
 				// no need to go to stopped state because waiting() already returned false
 				return nil
 			}

les/server.go

@@ -67,8 +67,8 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 		protocolManager:  pm,
 		quitSync:         quitSync,
 		lesTopics:        lesTopics,
-		chtIndexer:       light.NewChtIndexer(eth.ChainDb(), false),
+		chtIndexer:       light.NewChtIndexer(eth.ChainDb(), false, nil),
-		bloomTrieIndexer: light.NewBloomTrieIndexer(eth.ChainDb(), false),
+		bloomTrieIndexer: light.NewBloomTrieIndexer(eth.ChainDb(), false, nil),
 	}
 	logger := log.New()
 

light/lightchain.go

@@ -116,19 +116,19 @@ func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.
 }
 
 // addTrustedCheckpoint adds a trusted checkpoint to the blockchain
-func (self *LightChain) addTrustedCheckpoint(cp trustedCheckpoint) {
+func (self *LightChain) addTrustedCheckpoint(cp TrustedCheckpoint) {
 	if self.odr.ChtIndexer() != nil {
-		StoreChtRoot(self.chainDb, cp.sectionIdx, cp.sectionHead, cp.chtRoot)
+		StoreChtRoot(self.chainDb, cp.SectionIdx, cp.SectionHead, cp.CHTRoot)
-		self.odr.ChtIndexer().AddKnownSectionHead(cp.sectionIdx, cp.sectionHead)
+		self.odr.ChtIndexer().AddKnownSectionHead(cp.SectionIdx, cp.SectionHead)
 	}
 	if self.odr.BloomTrieIndexer() != nil {
-		StoreBloomTrieRoot(self.chainDb, cp.sectionIdx, cp.sectionHead, cp.bloomTrieRoot)
+		StoreBloomTrieRoot(self.chainDb, cp.SectionIdx, cp.SectionHead, cp.BloomRoot)
-		self.odr.BloomTrieIndexer().AddKnownSectionHead(cp.sectionIdx, cp.sectionHead)
+		self.odr.BloomTrieIndexer().AddKnownSectionHead(cp.SectionIdx, cp.SectionHead)
 	}
 	if self.odr.BloomIndexer() != nil {
-		self.odr.BloomIndexer().AddKnownSectionHead(cp.sectionIdx, cp.sectionHead)
+		self.odr.BloomIndexer().AddKnownSectionHead(cp.SectionIdx, cp.SectionHead)
 	}
-	log.Info("Added trusted checkpoint", "chain", cp.name, "block", (cp.sectionIdx+1)*CHTFrequencyClient-1, "hash", cp.sectionHead)
+	log.Info("Added trusted checkpoint", "chain", cp.name, "block", (cp.SectionIdx+1)*CHTFrequencyClient-1, "hash", cp.SectionHead)
 }
 
 func (self *LightChain) getProcInterrupt() bool {

light/odr.go

@@ -20,6 +20,7 @@ package light
 
 import (
 	"context"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -33,6 +34,9 @@ import (
 // service is not required.
 var NoOdr = context.Background()
 
+// ErrNoPeers is returned if no peers capable of serving a queued request are available
+var ErrNoPeers = errors.New("no suitable peers available")
+
 // OdrBackend is an interface to a backend service that handles ODR retrievals type
 type OdrBackend interface {
 	Database() ethdb.Database

light/postprocess.go

@@ -17,8 +17,10 @@
 package light
 
 import (
+	"context"
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"math/big"
 	"time"
 
@@ -47,35 +49,35 @@ const (
 	HelperTrieProcessConfirmations = 256  // number of confirmations before a HelperTrie is generated
 )
 
-// trustedCheckpoint represents a set of post-processed trie roots (CHT and BloomTrie) associated with
+// TrustedCheckpoint represents a set of post-processed trie roots (CHT and BloomTrie) associated with
 // the appropriate section index and head hash. It is used to start light syncing from this checkpoint
 // and avoid downloading the entire header chain while still being able to securely access old headers/logs.
-type trustedCheckpoint struct {
+type TrustedCheckpoint struct {
-	name                                string
+	name                            string
-	sectionIdx                          uint64
+	SectionIdx                      uint64
-	sectionHead, chtRoot, bloomTrieRoot common.Hash
+	SectionHead, CHTRoot, BloomRoot common.Hash
 }
 
 var (
-	mainnetCheckpoint = trustedCheckpoint{
+	mainnetCheckpoint = TrustedCheckpoint{
-		name:          "mainnet",
+		name:        "mainnet",
-		sectionIdx:    179,
+		SectionIdx:  179,
-		sectionHead:   common.HexToHash("ae778e455492db1183e566fa0c67f954d256fdd08618f6d5a393b0e24576d0ea"),
+		SectionHead: common.HexToHash("ae778e455492db1183e566fa0c67f954d256fdd08618f6d5a393b0e24576d0ea"),
-		chtRoot:       common.HexToHash("646b338f9ca74d936225338916be53710ec84020b89946004a8605f04c817f16"),
+		CHTRoot:     common.HexToHash("646b338f9ca74d936225338916be53710ec84020b89946004a8605f04c817f16"),
-		bloomTrieRoot: common.HexToHash("d0f978f5dbc86e5bf931d8dd5b2ecbebbda6dc78f8896af6a27b46a3ced0ac25"),
+		BloomRoot:   common.HexToHash("d0f978f5dbc86e5bf931d8dd5b2ecbebbda6dc78f8896af6a27b46a3ced0ac25"),
 	}
 
-	ropstenCheckpoint = trustedCheckpoint{
+	ropstenCheckpoint = TrustedCheckpoint{
-		name:          "ropsten",
+		name:        "ropsten",
-		sectionIdx:    107,
+		SectionIdx:  107,
-		sectionHead:   common.HexToHash("e1988f95399debf45b873e065e5cd61b416ef2e2e5deec5a6f87c3127086e1ce"),
+		SectionHead: common.HexToHash("e1988f95399debf45b873e065e5cd61b416ef2e2e5deec5a6f87c3127086e1ce"),
-		chtRoot:       common.HexToHash("15cba18e4de0ab1e95e202625199ba30147aec8b0b70384b66ebea31ba6a18e0"),
+		CHTRoot:     common.HexToHash("15cba18e4de0ab1e95e202625199ba30147aec8b0b70384b66ebea31ba6a18e0"),
-		bloomTrieRoot: common.HexToHash("e00fa6389b2e597d9df52172cd8e936879eed0fca4fa59db99e2c8ed682562f2"),
+		BloomRoot:   common.HexToHash("e00fa6389b2e597d9df52172cd8e936879eed0fca4fa59db99e2c8ed682562f2"),
 	}
 )
 
 // trustedCheckpoints associates each known checkpoint with the genesis hash of the chain it belongs to
-var trustedCheckpoints = map[common.Hash]trustedCheckpoint{
+var trustedCheckpoints = map[common.Hash]TrustedCheckpoint{
 	params.MainnetGenesisHash: mainnetCheckpoint,
 	params.TestnetGenesisHash: ropstenCheckpoint,
 }
@@ -119,7 +121,8 @@ func StoreChtRoot(db ethdb.Database, sectionIdx uint64, sectionHead, root common
 
 // ChtIndexerBackend implements core.ChainIndexerBackend
 type ChtIndexerBackend struct {
-	diskdb               ethdb.Database
+	diskdb, trieTable    ethdb.Database
+	odr                  OdrBackend
 	triedb               *trie.Database
 	section, sectionSize uint64
 	lastHash             common.Hash
@@ -127,7 +130,7 @@ type ChtIndexerBackend struct {
 }
 
 // NewBloomTrieIndexer creates a BloomTrie chain indexer
-func NewChtIndexer(db ethdb.Database, clientMode bool) *core.ChainIndexer {
+func NewChtIndexer(db ethdb.Database, clientMode bool, odr OdrBackend) *core.ChainIndexer {
 	var sectionSize, confirmReq uint64
 	if clientMode {
 		sectionSize = CHTFrequencyClient
@@ -137,28 +140,64 @@ func NewChtIndexer(db ethdb.Database, clientMode bool) *core.ChainIndexer {
 		confirmReq = HelperTrieProcessConfirmations
 	}
 	idb := ethdb.NewTable(db, "chtIndex-")
+	trieTable := ethdb.NewTable(db, ChtTablePrefix)
 	backend := &ChtIndexerBackend{
 		diskdb:      db,
-		triedb:      trie.NewDatabase(ethdb.NewTable(db, ChtTablePrefix)),
+		odr:         odr,
+		trieTable:   trieTable,
+		triedb:      trie.NewDatabase(trieTable),
 		sectionSize: sectionSize,
 	}
 	return core.NewChainIndexer(db, idb, backend, sectionSize, confirmReq, time.Millisecond*100, "cht")
 }
 
+// fetchMissingNodes tries to retrieve the last entry of the latest trusted CHT from the
+// ODR backend in order to be able to add new entries and calculate subsequent root hashes
+func (c *ChtIndexerBackend) fetchMissingNodes(ctx context.Context, section uint64, root common.Hash) error {
+	batch := c.trieTable.NewBatch()
+	r := &ChtRequest{ChtRoot: root, ChtNum: section - 1, BlockNum: section*c.sectionSize - 1}
+	for {
+		err := c.odr.Retrieve(ctx, r)
+		switch err {
+		case nil:
+			r.Proof.Store(batch)
+			return batch.Write()
+		case ErrNoPeers:
+			// if there are no peers to serve, retry later
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-time.After(time.Second * 10):
+				// stay in the loop and try again
+			}
+		default:
+			return err
+		}
+	}
+}
+
 // Reset implements core.ChainIndexerBackend
-func (c *ChtIndexerBackend) Reset(section uint64, lastSectionHead common.Hash) error {
+func (c *ChtIndexerBackend) Reset(ctx context.Context, section uint64, lastSectionHead common.Hash) error {
 	var root common.Hash
 	if section > 0 {
 		root = GetChtRoot(c.diskdb, section-1, lastSectionHead)
 	}
 	var err error
 	c.trie, err = trie.New(root, c.triedb)
+
+	if err != nil && c.odr != nil {
+		err = c.fetchMissingNodes(ctx, section, root)
+		if err == nil {
+			c.trie, err = trie.New(root, c.triedb)
+		}
+	}
+
 	c.section = section
 	return err
 }
 
 // Process implements core.ChainIndexerBackend
-func (c *ChtIndexerBackend) Process(header *types.Header) {
+func (c *ChtIndexerBackend) Process(ctx context.Context, header *types.Header) error {
 	hash, num := header.Hash(), header.Number.Uint64()
 	c.lastHash = hash
 
@@ -170,6 +209,7 @@ func (c *ChtIndexerBackend) Process(header *types.Header) {
 	binary.BigEndian.PutUint64(encNumber[:], num)
 	data, _ := rlp.EncodeToBytes(ChtNode{hash, td})
 	c.trie.Update(encNumber[:], data)
+	return nil
 }
 
 // Commit implements core.ChainIndexerBackend
@@ -181,16 +221,15 @@ func (c *ChtIndexerBackend) Commit() error {
 	c.triedb.Commit(root, false)
 
 	if ((c.section+1)*c.sectionSize)%CHTFrequencyClient == 0 {
-		log.Info("Storing CHT", "section", c.section*c.sectionSize/CHTFrequencyClient, "head", c.lastHash, "root", root)
+		log.Info("Storing CHT", "section", c.section*c.sectionSize/CHTFrequencyClient, "head", fmt.Sprintf("%064x", c.lastHash), "root", fmt.Sprintf("%064x", root))
 	}
 	StoreChtRoot(c.diskdb, c.section, c.lastHash, root)
 	return nil
 }
 
 const (
-	BloomTrieFrequency        = 32768
+	BloomTrieFrequency  = 32768
-	ethBloomBitsSection       = 4096
+	ethBloomBitsSection = 4096
-	ethBloomBitsConfirmations = 256
 )
 
 var (
@@ -215,7 +254,8 @@ func StoreBloomTrieRoot(db ethdb.Database, sectionIdx uint64, sectionHead, root
 
 // BloomTrieIndexerBackend implements core.ChainIndexerBackend
 type BloomTrieIndexerBackend struct {
-	diskdb                                     ethdb.Database
+	diskdb, trieTable                          ethdb.Database
+	odr                                        OdrBackend
 	triedb                                     *trie.Database
 	section, parentSectionSize, bloomTrieRatio uint64
 	trie                                       *trie.Trie
@@ -223,44 +263,98 @@ type BloomTrieIndexerBackend struct {
 }
 
 // NewBloomTrieIndexer creates a BloomTrie chain indexer
-func NewBloomTrieIndexer(db ethdb.Database, clientMode bool) *core.ChainIndexer {
+func NewBloomTrieIndexer(db ethdb.Database, clientMode bool, odr OdrBackend) *core.ChainIndexer {
+	trieTable := ethdb.NewTable(db, BloomTrieTablePrefix)
 	backend := &BloomTrieIndexerBackend{
-		diskdb: db,
+		diskdb:    db,
-		triedb: trie.NewDatabase(ethdb.NewTable(db, BloomTrieTablePrefix)),
+		odr:       odr,
+		trieTable: trieTable,
+		triedb:    trie.NewDatabase(trieTable),
 	}
 	idb := ethdb.NewTable(db, "bltIndex-")
 
-	var confirmReq uint64
 	if clientMode {
 		backend.parentSectionSize = BloomTrieFrequency
-		confirmReq = HelperTrieConfirmations
 	} else {
 		backend.parentSectionSize = ethBloomBitsSection
-		confirmReq = HelperTrieProcessConfirmations
 	}
 	backend.bloomTrieRatio = BloomTrieFrequency / backend.parentSectionSize
 	backend.sectionHeads = make([]common.Hash, backend.bloomTrieRatio)
-	return core.NewChainIndexer(db, idb, backend, BloomTrieFrequency, confirmReq-ethBloomBitsConfirmations, time.Millisecond*100, "bloomtrie")
+	return core.NewChainIndexer(db, idb, backend, BloomTrieFrequency, 0, time.Millisecond*100, "bloomtrie")
+}
+
+// fetchMissingNodes tries to retrieve the last entries of the latest trusted bloom trie from the
+// ODR backend in order to be able to add new entries and calculate subsequent root hashes
+func (b *BloomTrieIndexerBackend) fetchMissingNodes(ctx context.Context, section uint64, root common.Hash) error {
+	indexCh := make(chan uint, types.BloomBitLength)
+	type res struct {
+		nodes *NodeSet
+		err   error
+	}
+	resCh := make(chan res, types.BloomBitLength)
+	for i := 0; i < 20; i++ {
+		go func() {
+			for bitIndex := range indexCh {
+				r := &BloomRequest{BloomTrieRoot: root, BloomTrieNum: section - 1, BitIdx: bitIndex, SectionIdxList: []uint64{section - 1}}
+				for {
+					if err := b.odr.Retrieve(ctx, r); err == ErrNoPeers {
+						// if there are no peers to serve, retry later
+						select {
+						case <-ctx.Done():
+							resCh <- res{nil, ctx.Err()}
+							return
+						case <-time.After(time.Second * 10):
+							// stay in the loop and try again
+						}
+					} else {
+						resCh <- res{r.Proofs, err}
+						break
+					}
+				}
+			}
+		}()
+	}
+
+	for i := uint(0); i < types.BloomBitLength; i++ {
+		indexCh <- i
+	}
+	close(indexCh)
+	batch := b.trieTable.NewBatch()
+	for i := uint(0); i < types.BloomBitLength; i++ {
+		res := <-resCh
+		if res.err != nil {
+			return res.err
+		}
+		res.nodes.Store(batch)
+	}
+	return batch.Write()
 }
 
 // Reset implements core.ChainIndexerBackend
-func (b *BloomTrieIndexerBackend) Reset(section uint64, lastSectionHead common.Hash) error {
+func (b *BloomTrieIndexerBackend) Reset(ctx context.Context, section uint64, lastSectionHead common.Hash) error {
 	var root common.Hash
 	if section > 0 {
 		root = GetBloomTrieRoot(b.diskdb, section-1, lastSectionHead)
 	}
 	var err error
 	b.trie, err = trie.New(root, b.triedb)
+	if err != nil && b.odr != nil {
+		err = b.fetchMissingNodes(ctx, section, root)
+		if err == nil {
+			b.trie, err = trie.New(root, b.triedb)
+		}
+	}
 	b.section = section
 	return err
 }
 
 // Process implements core.ChainIndexerBackend
-func (b *BloomTrieIndexerBackend) Process(header *types.Header) {
+func (b *BloomTrieIndexerBackend) Process(ctx context.Context, header *types.Header) error {
 	num := header.Number.Uint64() - b.section*BloomTrieFrequency
 	if (num+1)%b.parentSectionSize == 0 {
 		b.sectionHeads[num/b.parentSectionSize] = header.Hash()
 	}
+	return nil
 }
 
 // Commit implements core.ChainIndexerBackend
@@ -300,7 +394,7 @@ func (b *BloomTrieIndexerBackend) Commit() error {
 	b.triedb.Commit(root, false)
 
 	sectionHead := b.sectionHeads[b.bloomTrieRatio-1]
-	log.Info("Storing bloom trie", "section", b.section, "head", sectionHead, "root", root, "compression", float64(compSize)/float64(decompSize))
+	log.Info("Storing bloom trie", "section", b.section, "head", fmt.Sprintf("%064x", sectionHead), "root", fmt.Sprintf("%064x", root), "compression", float64(compSize)/float64(decompSize))
 	StoreBloomTrieRoot(b.diskdb, b.section, sectionHead, root)
 
 	return nil