core, trie: intermediate mempool between trie and database (#15857)

This commit reduces database I/O by not writing every state trie to disk.

1 files changed, 263 insertions, 71 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index d5e139e31..8d141fddb 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -42,6 +42,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 	"github.com/hashicorp/golang-lru"
+	"gopkg.in/karalabe/cookiejar.v2/collections/prque"
 )
 
 var (
@@ -56,11 +57,20 @@ const (
 	maxFutureBlocks     = 256
 	maxTimeFutureBlocks = 30
 	badBlockLimit       = 10
+	triesInMemory       = 128
 
 	// BlockChainVersion ensures that an incompatible database forces a resync from scratch.
 	BlockChainVersion = 3
 )
 
+// CacheConfig contains the configuration values for the trie caching/pruning
+// that's resident in a blockchain.
+type CacheConfig struct {
+	Disabled      bool          // Whether to disable trie write caching (archive node)
+	TrieNodeLimit int           // Memory limit (MB) at which to flush the current in-memory trie to disk
+	TrieTimeLimit time.Duration // Time limit after which to flush the current in-memory trie to disk
+}
+
 // BlockChain represents the canonical chain given a database with a genesis
 // block. The Blockchain manages chain imports, reverts, chain reorganisations.
 //
@@ -76,10 +86,14 @@ const (
 // included in the canonical one where as GetBlockByNumber always represents the
 // canonical chain.
 type BlockChain struct {
-	config *params.ChainConfig // chain & network configuration
+	chainConfig *params.ChainConfig // Chain & network configuration
+	cacheConfig *CacheConfig        // Cache configuration for pruning
+
+	db     ethdb.Database // Low level persistent database to store final content in
+	triegc *prque.Prque   // Priority queue mapping block numbers to tries to gc
+	gcproc time.Duration  // Accumulates canonical block processing for trie dumping
 
 	hc            *HeaderChain
-	chainDb       ethdb.Database
 	rmLogsFeed    event.Feed
 	chainFeed     event.Feed
 	chainSideFeed event.Feed
@@ -119,7 +133,13 @@ type BlockChain struct {
 // NewBlockChain returns a fully initialised block chain using information
 // available in the database. It initialises the default Ethereum Validator and
 // Processor.
-func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, engine consensus.Engine, vmConfig vm.Config) (*BlockChain, error) {
+func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *params.ChainConfig, engine consensus.Engine, vmConfig vm.Config) (*BlockChain, error) {
+	if cacheConfig == nil {
+		cacheConfig = &CacheConfig{
+			TrieNodeLimit: 256 * 1024 * 1024,
+			TrieTimeLimit: 5 * time.Minute,
+		}
+	}
 	bodyCache, _ := lru.New(bodyCacheLimit)
 	bodyRLPCache, _ := lru.New(bodyCacheLimit)
 	blockCache, _ := lru.New(blockCacheLimit)
@@ -127,9 +147,11 @@ func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, engine co
 	badBlocks, _ := lru.New(badBlockLimit)
 
 	bc := &BlockChain{
-		config:       config,
-		chainDb:      chainDb,
-		stateCache:   state.NewDatabase(chainDb),
+		chainConfig:  chainConfig,
+		cacheConfig:  cacheConfig,
+		db:           db,
+		triegc:       prque.New(),
+		stateCache:   state.NewDatabase(db),
 		quit:         make(chan struct{}),
 		bodyCache:    bodyCache,
 		bodyRLPCache: bodyRLPCache,
@@ -139,11 +161,11 @@ func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, engine co
 		vmConfig:     vmConfig,
 		badBlocks:    badBlocks,
 	}
-	bc.SetValidator(NewBlockValidator(config, bc, engine))
-	bc.SetProcessor(NewStateProcessor(config, bc, engine))
+	bc.SetValidator(NewBlockValidator(chainConfig, bc, engine))
+	bc.SetProcessor(NewStateProcessor(chainConfig, bc, engine))
 
 	var err error
-	bc.hc, err = NewHeaderChain(chainDb, config, engine, bc.getProcInterrupt)
+	bc.hc, err = NewHeaderChain(db, chainConfig, engine, bc.getProcInterrupt)
 	if err != nil {
 		return nil, err
 	}
@@ -180,7 +202,7 @@ func (bc *BlockChain) getProcInterrupt() bool {
 // assumes that the chain manager mutex is held.
 func (bc *BlockChain) loadLastState() error {
 	// Restore the last known head block
-	head := GetHeadBlockHash(bc.chainDb)
+	head := GetHeadBlockHash(bc.db)
 	if head == (common.Hash{}) {
 		// Corrupt or empty database, init from scratch
 		log.Warn("Empty database, resetting chain")
@@ -196,15 +218,17 @@ func (bc *BlockChain) loadLastState() error {
 	// Make sure the state associated with the block is available
 	if _, err := state.New(currentBlock.Root(), bc.stateCache); err != nil {
 		// Dangling block without a state associated, init from scratch
-		log.Warn("Head state missing, resetting chain", "number", currentBlock.Number(), "hash", currentBlock.Hash())
-		return bc.Reset()
+		log.Warn("Head state missing, repairing chain", "number", currentBlock.Number(), "hash", currentBlock.Hash())
+		if err := bc.repair(&currentBlock); err != nil {
+			return err
+		}
 	}
 	// Everything seems to be fine, set as the head block
 	bc.currentBlock = currentBlock
 
 	// Restore the last known head header
 	currentHeader := bc.currentBlock.Header()
-	if head := GetHeadHeaderHash(bc.chainDb); head != (common.Hash{}) {
+	if head := GetHeadHeaderHash(bc.db); head != (common.Hash{}) {
 		if header := bc.GetHeaderByHash(head); header != nil {
 			currentHeader = header
 		}
@@ -213,7 +237,7 @@ func (bc *BlockChain) loadLastState() error {
 
 	// Restore the last known head fast block
 	bc.currentFastBlock = bc.currentBlock
-	if head := GetHeadFastBlockHash(bc.chainDb); head != (common.Hash{}) {
+	if head := GetHeadFastBlockHash(bc.db); head != (common.Hash{}) {
 		if block := bc.GetBlockByHash(head); block != nil {
 			bc.currentFastBlock = block
 		}
@@ -243,7 +267,7 @@ func (bc *BlockChain) SetHead(head uint64) error {
 
 	// Rewind the header chain, deleting all block bodies until then
 	delFn := func(hash common.Hash, num uint64) {
-		DeleteBody(bc.chainDb, hash, num)
+		DeleteBody(bc.db, hash, num)
 	}
 	bc.hc.SetHead(head, delFn)
 	currentHeader := bc.hc.CurrentHeader()
@@ -275,10 +299,10 @@ func (bc *BlockChain) SetHead(head uint64) error {
 	if bc.currentFastBlock == nil {
 		bc.currentFastBlock = bc.genesisBlock
 	}
-	if err := WriteHeadBlockHash(bc.chainDb, bc.currentBlock.Hash()); err != nil {
+	if err := WriteHeadBlockHash(bc.db, bc.currentBlock.Hash()); err != nil {
 		log.Crit("Failed to reset head full block", "err", err)
 	}
-	if err := WriteHeadFastBlockHash(bc.chainDb, bc.currentFastBlock.Hash()); err != nil {
+	if err := WriteHeadFastBlockHash(bc.db, bc.currentFastBlock.Hash()); err != nil {
 		log.Crit("Failed to reset head fast block", "err", err)
 	}
 	return bc.loadLastState()
@@ -292,7 +316,7 @@ func (bc *BlockChain) FastSyncCommitHead(hash common.Hash) error {
 	if block == nil {
 		return fmt.Errorf("non existent block [%x…]", hash[:4])
 	}
-	if _, err := trie.NewSecure(block.Root(), bc.chainDb, 0); err != nil {
+	if _, err := trie.NewSecure(block.Root(), bc.stateCache.TrieDB(), 0); err != nil {
 		return err
 	}
 	// If all checks out, manually set the head block
@@ -387,7 +411,7 @@ func (bc *BlockChain) ResetWithGenesisBlock(genesis *types.Block) error {
 	if err := bc.hc.WriteTd(genesis.Hash(), genesis.NumberU64(), genesis.Difficulty()); err != nil {
 		log.Crit("Failed to write genesis block TD", "err", err)
 	}
-	if err := WriteBlock(bc.chainDb, genesis); err != nil {
+	if err := WriteBlock(bc.db, genesis); err != nil {
 		log.Crit("Failed to write genesis block", "err", err)
 	}
 	bc.genesisBlock = genesis
@@ -400,6 +424,24 @@ func (bc *BlockChain) ResetWithGenesisBlock(genesis *types.Block) error {
 	return nil
 }
 
+// repair tries to repair the current blockchain by rolling back the current block
+// until one with associated state is found. This is needed to fix incomplete db
+// writes caused either by crashes/power outages, or simply non-committed tries.
+//
+// This method only rolls back the current block. The current header and current
+// fast block are left intact.
+func (bc *BlockChain) repair(head **types.Block) error {
+	for {
+		// Abort if we've rewound to a head block that does have associated state
+		if _, err := state.New((*head).Root(), bc.stateCache); err == nil {
+			log.Info("Rewound blockchain to past state", "number", (*head).Number(), "hash", (*head).Hash())
+			return nil
+		}
+		// Otherwise rewind one block and recheck state availability there
+		(*head) = bc.GetBlock((*head).ParentHash(), (*head).NumberU64()-1)
+	}
+}
+
 // Export writes the active chain to the given writer.
 func (bc *BlockChain) Export(w io.Writer) error {
 	return bc.ExportN(w, uint64(0), bc.currentBlock.NumberU64())
@@ -437,13 +479,13 @@ func (bc *BlockChain) ExportN(w io.Writer, first uint64, last uint64) error {
 // Note, this function assumes that the `mu` mutex is held!
 func (bc *BlockChain) insert(block *types.Block) {
 	// If the block is on a side chain or an unknown one, force other heads onto it too
-	updateHeads := GetCanonicalHash(bc.chainDb, block.NumberU64()) != block.Hash()
+	updateHeads := GetCanonicalHash(bc.db, block.NumberU64()) != block.Hash()
 
 	// Add the block to the canonical chain number scheme and mark as the head
-	if err := WriteCanonicalHash(bc.chainDb, block.Hash(), block.NumberU64()); err != nil {
+	if err := WriteCanonicalHash(bc.db, block.Hash(), block.NumberU64()); err != nil {
 		log.Crit("Failed to insert block number", "err", err)
 	}
-	if err := WriteHeadBlockHash(bc.chainDb, block.Hash()); err != nil {
+	if err := WriteHeadBlockHash(bc.db, block.Hash()); err != nil {
 		log.Crit("Failed to insert head block hash", "err", err)
 	}
 	bc.currentBlock = block
@@ -452,7 +494,7 @@ func (bc *BlockChain) insert(block *types.Block) {
 	if updateHeads {
 		bc.hc.SetCurrentHeader(block.Header())
 
-		if err := WriteHeadFastBlockHash(bc.chainDb, block.Hash()); err != nil {
+		if err := WriteHeadFastBlockHash(bc.db, block.Hash()); err != nil {
 			log.Crit("Failed to insert head fast block hash", "err", err)
 		}
 		bc.currentFastBlock = block
@@ -472,7 +514,7 @@ func (bc *BlockChain) GetBody(hash common.Hash) *types.Body {
 		body := cached.(*types.Body)
 		return body
 	}
-	body := GetBody(bc.chainDb, hash, bc.hc.GetBlockNumber(hash))
+	body := GetBody(bc.db, hash, bc.hc.GetBlockNumber(hash))
 	if body == nil {
 		return nil
 	}
@@ -488,7 +530,7 @@ func (bc *BlockChain) GetBodyRLP(hash common.Hash) rlp.RawValue {
 	if cached, ok := bc.bodyRLPCache.Get(hash); ok {
 		return cached.(rlp.RawValue)
 	}
-	body := GetBodyRLP(bc.chainDb, hash, bc.hc.GetBlockNumber(hash))
+	body := GetBodyRLP(bc.db, hash, bc.hc.GetBlockNumber(hash))
 	if len(body) == 0 {
 		return nil
 	}
@@ -502,21 +544,25 @@ func (bc *BlockChain) HasBlock(hash common.Hash, number uint64) bool {
 	if bc.blockCache.Contains(hash) {
 		return true
 	}
-	ok, _ := bc.chainDb.Has(blockBodyKey(hash, number))
+	ok, _ := bc.db.Has(blockBodyKey(hash, number))
 	return ok
 }
 
+// HasState checks if state trie is fully present in the database or not.
+func (bc *BlockChain) HasState(hash common.Hash) bool {
+	_, err := bc.stateCache.OpenTrie(hash)
+	return err == nil
+}
+
 // HasBlockAndState checks if a block and associated state trie is fully present
 // in the database or not, caching it if present.
-func (bc *BlockChain) HasBlockAndState(hash common.Hash) bool {
+func (bc *BlockChain) HasBlockAndState(hash common.Hash, number uint64) bool {
 	// Check first that the block itself is known
-	block := bc.GetBlockByHash(hash)
+	block := bc.GetBlock(hash, number)
 	if block == nil {
 		return false
 	}
-	// Ensure the associated state is also present
-	_, err := bc.stateCache.OpenTrie(block.Root())
-	return err == nil
+	return bc.HasState(block.Root())
 }
 
 // GetBlock retrieves a block from the database by hash and number,
@@ -526,7 +572,7 @@ func (bc *BlockChain) GetBlock(hash common.Hash, number uint64) *types.Block {
 	if block, ok := bc.blockCache.Get(hash); ok {
 		return block.(*types.Block)
 	}
-	block := GetBlock(bc.chainDb, hash, number)
+	block := GetBlock(bc.db, hash, number)
 	if block == nil {
 		return nil
 	}
@@ -543,13 +589,18 @@ func (bc *BlockChain) GetBlockByHash(hash common.Hash) *types.Block {
 // GetBlockByNumber retrieves a block from the database by number, caching it
 // (associated with its hash) if found.
 func (bc *BlockChain) GetBlockByNumber(number uint64) *types.Block {
-	hash := GetCanonicalHash(bc.chainDb, number)
+	hash := GetCanonicalHash(bc.db, number)
 	if hash == (common.Hash{}) {
 		return nil
 	}
 	return bc.GetBlock(hash, number)
 }
 
+// GetReceiptsByHash retrieves the receipts for all transactions in a given block.
+func (bc *BlockChain) GetReceiptsByHash(hash common.Hash) types.Receipts {
+	return GetBlockReceipts(bc.db, hash, GetBlockNumber(bc.db, hash))
+}
+
 // GetBlocksFromHash returns the block corresponding to hash and up to n-1 ancestors.
 // [deprecated by eth/62]
 func (bc *BlockChain) GetBlocksFromHash(hash common.Hash, n int) (blocks []*types.Block) {
@@ -577,6 +628,12 @@ func (bc *BlockChain) GetUnclesInChain(block *types.Block, length int) []*types.
 	return uncles
 }
 
+// TrieNode retrieves a blob of data associated with a trie node (or code hash)
+// either from ephemeral in-memory cache, or from persistent storage.
+func (bc *BlockChain) TrieNode(hash common.Hash) ([]byte, error) {
+	return bc.stateCache.TrieDB().Node(hash)
+}
+
 // Stop stops the blockchain service. If any imports are currently in progress
 // it will abort them using the procInterrupt.
 func (bc *BlockChain) Stop() {
@@ -589,6 +646,33 @@ func (bc *BlockChain) Stop() {
 	atomic.StoreInt32(&bc.procInterrupt, 1)
 
 	bc.wg.Wait()
+
+	// Ensure the state of a recent block is also stored to disk before exiting.
+	// It is fine if this state does not exist (fast start/stop cycle), but it is
+	// advisable to leave an N block gap from the head so 1) a restart loads up
+	// the last N blocks as sync assistance to remote nodes; 2) a restart during
+	// a (small) reorg doesn't require deep reprocesses; 3) chain "repair" from
+	// missing states are constantly tested.
+	//
+	// This may be tuned a bit on mainnet if its too annoying to reprocess the last
+	// N blocks.
+	if !bc.cacheConfig.Disabled {
+		triedb := bc.stateCache.TrieDB()
+		if number := bc.CurrentBlock().NumberU64(); number >= triesInMemory {
+			recent := bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - triesInMemory + 1)
+
+			log.Info("Writing cached state to disk", "block", recent.Number(), "hash", recent.Hash(), "root", recent.Root())
+			if err := triedb.Commit(recent.Root(), true); err != nil {
+				log.Error("Failed to commit recent state trie", "err", err)
+			}
+		}
+		for !bc.triegc.Empty() {
+			triedb.Dereference(bc.triegc.PopItem().(common.Hash), common.Hash{})
+		}
+		if size := triedb.Size(); size != 0 {
+			log.Error("Dangling trie nodes after full cleanup")
+		}
+	}
 	log.Info("Blockchain manager stopped")
 }
 
@@ -633,11 +717,11 @@ func (bc *BlockChain) Rollback(chain []common.Hash) {
 		}
 		if bc.currentFastBlock.Hash() == hash {
 			bc.currentFastBlock = bc.GetBlock(bc.currentFastBlock.ParentHash(), bc.currentFastBlock.NumberU64()-1)
-			WriteHeadFastBlockHash(bc.chainDb, bc.currentFastBlock.Hash())
+			WriteHeadFastBlockHash(bc.db, bc.currentFastBlock.Hash())
 		}
 		if bc.currentBlock.Hash() == hash {
 			bc.currentBlock = bc.GetBlock(bc.currentBlock.ParentHash(), bc.currentBlock.NumberU64()-1)
-			WriteHeadBlockHash(bc.chainDb, bc.currentBlock.Hash())
+			WriteHeadBlockHash(bc.db, bc.currentBlock.Hash())
 		}
 	}
 }
@@ -696,7 +780,7 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 		stats = struct{ processed, ignored int32 }{}
 		start = time.Now()
 		bytes = 0
-		batch = bc.chainDb.NewBatch()
+		batch = bc.db.NewBatch()
 	)
 	for i, block := range blockChain {
 		receipts := receiptChain[i]
@@ -714,7 +798,7 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 			continue
 		}
 		// Compute all the non-consensus fields of the receipts
-		SetReceiptsData(bc.config, block, receipts)
+		SetReceiptsData(bc.chainConfig, block, receipts)
 		// Write all the data out into the database
 		if err := WriteBody(batch, block.Hash(), block.NumberU64(), block.Body()); err != nil {
 			return i, fmt.Errorf("failed to write block body: %v", err)
@@ -747,7 +831,7 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 	head := blockChain[len(blockChain)-1]
 	if td := bc.GetTd(head.Hash(), head.NumberU64()); td != nil { // Rewind may have occurred, skip in that case
 		if bc.GetTd(bc.currentFastBlock.Hash(), bc.currentFastBlock.NumberU64()).Cmp(td) < 0 {
-			if err := WriteHeadFastBlockHash(bc.chainDb, head.Hash()); err != nil {
+			if err := WriteHeadFastBlockHash(bc.db, head.Hash()); err != nil {
 				log.Crit("Failed to update head fast block hash", "err", err)
 			}
 			bc.currentFastBlock = head
@@ -758,15 +842,33 @@ func (bc *BlockChain) InsertReceiptChain(blockChain types.Blocks, receiptChain [
 	log.Info("Imported new block receipts",
 		"count", stats.processed,
 		"elapsed", common.PrettyDuration(time.Since(start)),
-		"bytes", bytes,
 		"number", head.Number(),
 		"hash", head.Hash(),
+		"size", common.StorageSize(bytes),
 		"ignored", stats.ignored)
 	return 0, nil
 }
 
-// WriteBlock writes the block to the chain.
-func (bc *BlockChain) WriteBlockAndState(block *types.Block, receipts []*types.Receipt, state *state.StateDB) (status WriteStatus, err error) {
+var lastWrite uint64
+
+// WriteBlockWithoutState writes only the block and its metadata to the database,
+// but does not write any state. This is used to construct competing side forks
+// up to the point where they exceed the canonical total difficulty.
+func (bc *BlockChain) WriteBlockWithoutState(block *types.Block, td *big.Int) (err error) {
+	bc.wg.Add(1)
+	defer bc.wg.Done()
+
+	if err := bc.hc.WriteTd(block.Hash(), block.NumberU64(), td); err != nil {
+		return err
+	}
+	if err := WriteBlock(bc.db, block); err != nil {
+		return err
+	}
+	return nil
+}
+
+// WriteBlockWithState writes the block and all associated state to the database.
+func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.Receipt, state *state.StateDB) (status WriteStatus, err error) {
 	bc.wg.Add(1)
 	defer bc.wg.Done()
 
@@ -787,17 +889,73 @@ func (bc *BlockChain) WriteBlockAndState(block *types.Block, receipts []*types.R
 		return NonStatTy, err
 	}
 	// Write other block data using a batch.
-	batch := bc.chainDb.NewBatch()
+	batch := bc.db.NewBatch()
 	if err := WriteBlock(batch, block); err != nil {
 		return NonStatTy, err
 	}
-	if _, err := state.CommitTo(batch, bc.config.IsEIP158(block.Number())); err != nil {
+	root, err := state.Commit(bc.chainConfig.IsEIP158(block.Number()))
+	if err != nil {
 		return NonStatTy, err
 	}
+	triedb := bc.stateCache.TrieDB()
+
+	// If we're running an archive node, always flush
+	if bc.cacheConfig.Disabled {
+		if err := triedb.Commit(root, false); err != nil {
+			return NonStatTy, err
+		}
+	} else {
+		// Full but not archive node, do proper garbage collection
+		triedb.Reference(root, common.Hash{}) // metadata reference to keep trie alive
+		bc.triegc.Push(root, -float32(block.NumberU64()))
+
+		if current := block.NumberU64(); current > triesInMemory {
+			// Find the next state trie we need to commit
+			header := bc.GetHeaderByNumber(current - triesInMemory)
+			chosen := header.Number.Uint64()
+
+			// Only write to disk if we exceeded our memory allowance *and* also have at
+			// least a given number of tries gapped.
+			var (
+				size  = triedb.Size()
+				limit = common.StorageSize(bc.cacheConfig.TrieNodeLimit) * 1024 * 1024
+			)
+			if size > limit || bc.gcproc > bc.cacheConfig.TrieTimeLimit {
+				// If we're exceeding limits but haven't reached a large enough memory gap,
+				// warn the user that the system is becoming unstable.
+				if chosen < lastWrite+triesInMemory {
+					switch {
+					case size >= 2*limit:
+						log.Error("Trie memory critical, forcing to disk", "size", size, "limit", limit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+					case bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit:
+						log.Error("Trie timing critical, forcing to disk", "time", bc.gcproc, "allowance", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+					case size > limit:
+						log.Warn("Trie memory at dangerous levels", "size", size, "limit", limit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+					case bc.gcproc > bc.cacheConfig.TrieTimeLimit:
+						log.Warn("Trie timing at dangerous levels", "time", bc.gcproc, "limit", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/triesInMemory)
+					}
+				}
+				// If optimum or critical limits reached, write to disk
+				if chosen >= lastWrite+triesInMemory || size >= 2*limit || bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit {
+					triedb.Commit(header.Root, true)
+					lastWrite = chosen
+					bc.gcproc = 0
+				}
+			}
+			// Garbage collect anything below our required write retention
+			for !bc.triegc.Empty() {
+				root, number := bc.triegc.Pop()
+				if uint64(-number) > chosen {
+					bc.triegc.Push(root, number)
+					break
+				}
+				triedb.Dereference(root.(common.Hash), common.Hash{})
+			}
+		}
+	}
 	if err := WriteBlockReceipts(batch, block.Hash(), block.NumberU64(), receipts); err != nil {
 		return NonStatTy, err
 	}
-
 	// If the total difficulty is higher than our known, add it to the canonical chain
 	// Second clause in the if statement reduces the vulnerability to selfish mining.
 	// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
@@ -818,7 +976,7 @@ func (bc *BlockChain) WriteBlockAndState(block *types.Block, receipts []*types.R
 			return NonStatTy, err
 		}
 		// Write hash preimages
-		if err := WritePreimages(bc.chainDb, block.NumberU64(), state.Preimages()); err != nil {
+		if err := WritePreimages(bc.db, block.NumberU64(), state.Preimages()); err != nil {
 			return NonStatTy, err
 		}
 		status = CanonStatTy
@@ -910,31 +1068,60 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 		if err == nil {
 			err = bc.Validator().ValidateBody(block)
 		}
-		if err != nil {
-			if err == ErrKnownBlock {
-				stats.ignored++
-				continue
+		switch {
+		case err == ErrKnownBlock:
+			stats.ignored++
+			continue
+
+		case err == consensus.ErrFutureBlock:
+			// Allow up to MaxFuture second in the future blocks. If this limit is exceeded
+			// the chain is discarded and processed at a later time if given.
+			max := big.NewInt(time.Now().Unix() + maxTimeFutureBlocks)
+			if block.Time().Cmp(max) > 0 {
+				return i, events, coalescedLogs, fmt.Errorf("future block: %v > %v", block.Time(), max)
 			}
+			bc.futureBlocks.Add(block.Hash(), block)
+			stats.queued++
+			continue
+
+		case err == consensus.ErrUnknownAncestor && bc.futureBlocks.Contains(block.ParentHash()):
+			bc.futureBlocks.Add(block.Hash(), block)
+			stats.queued++
+			continue
 
-			if err == consensus.ErrFutureBlock {
-				// Allow up to MaxFuture second in the future blocks. If this limit
-				// is exceeded the chain is discarded and processed at a later time
-				// if given.
-				max := big.NewInt(time.Now().Unix() + maxTimeFutureBlocks)
-				if block.Time().Cmp(max) > 0 {
-					return i, events, coalescedLogs, fmt.Errorf("future block: %v > %v", block.Time(), max)
+		case err == consensus.ErrPrunedAncestor:
+			// Block competing with the canonical chain, store in the db, but don't process
+			// until the competitor TD goes above the canonical TD
+			localTd := bc.GetTd(bc.currentBlock.Hash(), bc.currentBlock.NumberU64())
+			externTd := new(big.Int).Add(bc.GetTd(block.ParentHash(), block.NumberU64()-1), block.Difficulty())
+			if localTd.Cmp(externTd) > 0 {
+				if err = bc.WriteBlockWithoutState(block, externTd); err != nil {
+					return i, events, coalescedLogs, err
 				}
-				bc.futureBlocks.Add(block.Hash(), block)
-				stats.queued++
 				continue
 			}
+			// Competitor chain beat canonical, gather all blocks from the common ancestor
+			var winner []*types.Block
 
-			if err == consensus.ErrUnknownAncestor && bc.futureBlocks.Contains(block.ParentHash()) {
-				bc.futureBlocks.Add(block.Hash(), block)
-				stats.queued++
-				continue
+			parent := bc.GetBlock(block.ParentHash(), block.NumberU64()-1)
+			for !bc.HasState(parent.Root()) {
+				winner = append(winner, parent)
+				parent = bc.GetBlock(parent.ParentHash(), parent.NumberU64()-1)
+			}
+			for j := 0; j < len(winner)/2; j++ {
+				winner[j], winner[len(winner)-1-j] = winner[len(winner)-1-j], winner[j]
+			}
+			// Import all the pruned blocks to make the state available
+			bc.chainmu.Unlock()
+			_, evs, logs, err := bc.insertChain(winner)
+			bc.chainmu.Lock()
+			events, coalescedLogs = evs, logs
+
+			if err != nil {
+				return i, events, coalescedLogs, err
 			}
 
+		case err != nil:
 			bc.reportBlock(block, nil, err)
 			return i, events, coalescedLogs, err
 		}
@@ -962,8 +1149,10 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 			bc.reportBlock(block, receipts, err)
 			return i, events, coalescedLogs, err
 		}
+		proctime := time.Since(bstart)
+
 		// Write the block to the chain and get the status.
-		status, err := bc.WriteBlockAndState(block, receipts, state)
+		status, err := bc.WriteBlockWithState(block, receipts, state)
 		if err != nil {
 			return i, events, coalescedLogs, err
 		}
@@ -977,6 +1166,9 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 			events = append(events, ChainEvent{block, block.Hash(), logs})
 			lastCanon = block
 
+			// Only count canonical blocks for GC processing time
+			bc.gcproc += proctime
+
 		case SideStatTy:
 			log.Debug("Inserted forked block", "number", block.Number(), "hash", block.Hash(), "diff", block.Difficulty(), "elapsed",
 				common.PrettyDuration(time.Since(bstart)), "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()))
@@ -986,7 +1178,7 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 		}
 		stats.processed++
 		stats.usedGas += usedGas
-		stats.report(chain, i)
+		stats.report(chain, i, bc.stateCache.TrieDB().Size())
 	}
 	// Append a single chain head event if we've progressed the chain
 	if lastCanon != nil && bc.CurrentBlock().Hash() == lastCanon.Hash() {
@@ -1009,7 +1201,7 @@ const statsReportLimit = 8 * time.Second
 
 // report prints statistics if some number of blocks have been processed
 // or more than a few seconds have passed since the last message.
-func (st *insertStats) report(chain []*types.Block, index int) {
+func (st *insertStats) report(chain []*types.Block, index int, cache common.StorageSize) {
 	// Fetch the timings for the batch
 	var (
 		now     = mclock.Now()
@@ -1024,7 +1216,7 @@ func (st *insertStats) report(chain []*types.Block, index int) {
 		context := []interface{}{
 			"blocks", st.processed, "txs", txs, "mgas", float64(st.usedGas) / 1000000,
 			"elapsed", common.PrettyDuration(elapsed), "mgasps", float64(st.usedGas) * 1000 / float64(elapsed),
-			"number", end.Number(), "hash", end.Hash(),
+			"number", end.Number(), "hash", end.Hash(), "cache", cache,
 		}
 		if st.queued > 0 {
 			context = append(context, []interface{}{"queued", st.queued}...)
@@ -1060,7 +1252,7 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 		// These logs are later announced as deleted.
 		collectLogs = func(h common.Hash) {
 			// Coalesce logs and set 'Removed'.
-			receipts := GetBlockReceipts(bc.chainDb, h, bc.hc.GetBlockNumber(h))
+			receipts := GetBlockReceipts(bc.db, h, bc.hc.GetBlockNumber(h))
 			for _, receipt := range receipts {
 				for _, log := range receipt.Logs {
 					del := *log
@@ -1129,7 +1321,7 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 		// insert the block in the canonical way, re-writing history
 		bc.insert(newChain[i])
 		// write lookup entries for hash based transaction/receipt searches
-		if err := WriteTxLookupEntries(bc.chainDb, newChain[i]); err != nil {
+		if err := WriteTxLookupEntries(bc.db, newChain[i]); err != nil {
 			return err
 		}
 		addedTxs = append(addedTxs, newChain[i].Transactions()...)
@@ -1139,7 +1331,7 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 	// When transactions get deleted from the database that means the
 	// receipts that were created in the fork must also be deleted
 	for _, tx := range diff {
-		DeleteTxLookupEntry(bc.chainDb, tx.Hash())
+		DeleteTxLookupEntry(bc.db, tx.Hash())
 	}
 	if len(deletedLogs) > 0 {
 		go bc.rmLogsFeed.Send(RemovedLogsEvent{deletedLogs})
@@ -1231,7 +1423,7 @@ Hash: 0x%x
 
 Error: %v
 ##############################
-`, bc.config, block.Number(), block.Hash(), receiptString, err))
+`, bc.chainConfig, block.Number(), block.Hash(), receiptString, err))
 }
 
 // InsertHeaderChain attempts to insert the given header chain in to the local
@@ -1338,7 +1530,7 @@ func (bc *BlockChain) GetHeaderByNumber(number uint64) *types.Header {
 }
 
 // Config retrieves the blockchain's chain configuration.
-func (bc *BlockChain) Config() *params.ChainConfig { return bc.config }
+func (bc *BlockChain) Config() *params.ChainConfig { return bc.chainConfig }
 
 // Engine retrieves the blockchain's consensus engine.
 func (bc *BlockChain) Engine() consensus.Engine { return bc.engine }