19 files changed, 4066 insertions, 393 deletions

diff --git a/core/state/database.go b/core/state/database.go
index 8c641c3..385c25d 100644
--- a/core/state/database.go
+++ b/core/state/database.go
@@ -17,17 +17,23 @@
 package state
 
 import (
+	"errors"
 	"fmt"
 
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/ethdb"
-	"github.com/ava-labs/go-ethereum/trie"
+	"github.com/VictoriaMetrics/fastcache"
+	"github.com/ava-labs/coreth/core/rawdb"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/trie"
 	lru "github.com/hashicorp/golang-lru"
 )
 
 const (
 	// Number of codehash->size associations to keep.
 	codeSizeCacheSize = 100000
+
+	// Cache size granted for caching clean code.
+	codeCacheSize = 64 * 1024 * 1024
 )
 
 // Database wraps access to tries and contract code.
@@ -100,23 +106,25 @@ type Trie interface {
 // concurrent use, but does not retain any recent trie nodes in memory. To keep some
 // historical state in memory, use the NewDatabaseWithCache constructor.
 func NewDatabase(db ethdb.Database) Database {
-	return NewDatabaseWithCache(db, 0)
+	return NewDatabaseWithCache(db, 0, "")
 }
 
 // NewDatabaseWithCache creates a backing store for state. The returned database
 // is safe for concurrent use and retains a lot of collapsed RLP trie nodes in a
 // large memory cache.
-func NewDatabaseWithCache(db ethdb.Database, cache int) Database {
+func NewDatabaseWithCache(db ethdb.Database, cache int, journal string) Database {
 	csc, _ := lru.New(codeSizeCacheSize)
 	return &cachingDB{
-		db:            trie.NewDatabaseWithCache(db, cache),
+		db:            trie.NewDatabaseWithCache(db, cache, journal),
 		codeSizeCache: csc,
+		codeCache:     fastcache.New(codeCacheSize),
 	}
 }
 
 type cachingDB struct {
 	db            *trie.Database
 	codeSizeCache *lru.Cache
+	codeCache     *fastcache.Cache
 }
 
 // OpenTrie opens the main account trie at a specific root hash.
@@ -141,11 +149,32 @@ func (db *cachingDB) CopyTrie(t Trie) Trie {
 
 // ContractCode retrieves a particular contract's code.
 func (db *cachingDB) ContractCode(addrHash, codeHash common.Hash) ([]byte, error) {
-	code, err := db.db.Node(codeHash)
-	if err == nil {
+	if code := db.codeCache.Get(nil, codeHash.Bytes()); len(code) > 0 {
+		return code, nil
+	}
+	code := rawdb.ReadCode(db.db.DiskDB(), codeHash)
+	if len(code) > 0 {
+		db.codeCache.Set(codeHash.Bytes(), code)
+		db.codeSizeCache.Add(codeHash, len(code))
+		return code, nil
+	}
+	return nil, errors.New("not found")
+}
+
+// ContractCodeWithPrefix retrieves a particular contract's code. If the
+// code can't be found in the cache, then check the existence with **new**
+// db scheme.
+func (db *cachingDB) ContractCodeWithPrefix(addrHash, codeHash common.Hash) ([]byte, error) {
+	if code := db.codeCache.Get(nil, codeHash.Bytes()); len(code) > 0 {
+		return code, nil
+	}
+	code := rawdb.ReadCodeWithPrefix(db.db.DiskDB(), codeHash)
+	if len(code) > 0 {
+		db.codeCache.Set(codeHash.Bytes(), code)
 		db.codeSizeCache.Add(codeHash, len(code))
+		return code, nil
 	}
-	return code, err
+	return nil, errors.New("not found")
 }
 
 // ContractCodeSize retrieves a particular contracts code's size.
diff --git a/core/state/dump.go b/core/state/dump.go
index 91c7d08..6f09398 100644
--- a/core/state/dump.go
+++ b/core/state/dump.go
@@ -20,90 +20,119 @@ import (
 	"encoding/json"
 	"fmt"
 
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/common/hexutil"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/rlp"
-	"github.com/ava-labs/go-ethereum/trie"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
 )
 
-// DumpAccount represents an account in the state
+// DumpCollector interface which the state trie calls during iteration
+type DumpCollector interface {
+	// OnRoot is called with the state root
+	OnRoot(common.Hash)
+	// OnAccount is called once for each account in the trie
+	OnAccount(common.Address, DumpAccount)
+}
+
+// DumpAccount represents an account in the state.
 type DumpAccount struct {
-	Balance   string                 `json:"balance"`
-	Nonce     uint64                 `json:"nonce"`
-	Root      string                 `json:"root"`
-	CodeHash  string                 `json:"codeHash"`
-	Code      string                 `json:"code,omitempty"`
-	Storage   map[common.Hash]string `json:"storage,omitempty"`
-	Address   *common.Address        `json:"address,omitempty"` // Address only present in iterative (line-by-line) mode
-	SecureKey hexutil.Bytes          `json:"key,omitempty"`     // If we don't have address, we can output the key
+	Balance     string                 `json:"balance"`
+	Nonce       uint64                 `json:"nonce"`
+	Root        string                 `json:"root"`
+	CodeHash    string                 `json:"codeHash"`
+	IsMultiCoin bool                   `json:"isMultiCoin"`
+	Code        string                 `json:"code,omitempty"`
+	Storage     map[common.Hash]string `json:"storage,omitempty"`
+	Address     *common.Address        `json:"address,omitempty"` // Address only present in iterative (line-by-line) mode
+	SecureKey   hexutil.Bytes          `json:"key,omitempty"`     // If we don't have address, we can output the key
 
 }
 
-// Dump represents the full dump in a collected format, as one large map
+// Dump represents the full dump in a collected format, as one large map.
 type Dump struct {
 	Root     string                         `json:"root"`
 	Accounts map[common.Address]DumpAccount `json:"accounts"`
 }
 
-// iterativeDump is a 'collector'-implementation which dump output line-by-line iteratively
-type iterativeDump json.Encoder
+// OnRoot implements DumpCollector interface
+func (d *Dump) OnRoot(root common.Hash) {
+	d.Root = fmt.Sprintf("%x", root)
+}
+
+// OnAccount implements DumpCollector interface
+func (d *Dump) OnAccount(addr common.Address, account DumpAccount) {
+	d.Accounts[addr] = account
+}
+
+// IteratorDump is an implementation for iterating over data.
+type IteratorDump struct {
+	Root     string                         `json:"root"`
+	Accounts map[common.Address]DumpAccount `json:"accounts"`
+	Next     []byte                         `json:"next,omitempty"` // nil if no more accounts
+}
 
-// Collector interface which the state trie calls during iteration
-type collector interface {
-	onRoot(common.Hash)
-	onAccount(common.Address, DumpAccount)
+// OnRoot implements DumpCollector interface
+func (d *IteratorDump) OnRoot(root common.Hash) {
+	d.Root = fmt.Sprintf("%x", root)
 }
 
-func (self *Dump) onRoot(root common.Hash) {
-	self.Root = fmt.Sprintf("%x", root)
+// OnAccount implements DumpCollector interface
+func (d *IteratorDump) OnAccount(addr common.Address, account DumpAccount) {
+	d.Accounts[addr] = account
 }
 
-func (self *Dump) onAccount(addr common.Address, account DumpAccount) {
-	self.Accounts[addr] = account
+// iterativeDump is a DumpCollector-implementation which dumps output line-by-line iteratively.
+type iterativeDump struct {
+	*json.Encoder
 }
 
-func (self iterativeDump) onAccount(addr common.Address, account DumpAccount) {
+// OnAccount implements DumpCollector interface
+func (d iterativeDump) OnAccount(addr common.Address, account DumpAccount) {
 	dumpAccount := &DumpAccount{
-		Balance:   account.Balance,
-		Nonce:     account.Nonce,
-		Root:      account.Root,
-		CodeHash:  account.CodeHash,
-		Code:      account.Code,
-		Storage:   account.Storage,
-		SecureKey: account.SecureKey,
-		Address:   nil,
+		Balance:     account.Balance,
+		Nonce:       account.Nonce,
+		Root:        account.Root,
+		CodeHash:    account.CodeHash,
+		IsMultiCoin: account.IsMultiCoin,
+		Code:        account.Code,
+		Storage:     account.Storage,
+		SecureKey:   account.SecureKey,
+		Address:     nil,
 	}
 	if addr != (common.Address{}) {
 		dumpAccount.Address = &addr
 	}
-	(*json.Encoder)(&self).Encode(dumpAccount)
+	d.Encode(dumpAccount)
 }
-func (self iterativeDump) onRoot(root common.Hash) {
-	(*json.Encoder)(&self).Encode(struct {
+
+// OnRoot implements DumpCollector interface
+func (d iterativeDump) OnRoot(root common.Hash) {
+	d.Encode(struct {
 		Root common.Hash `json:"root"`
 	}{root})
 }
 
-func (self *StateDB) dump(c collector, excludeCode, excludeStorage, excludeMissingPreimages bool) {
-	emptyAddress := (common.Address{})
+func (s *StateDB) DumpToCollector(c DumpCollector, excludeCode, excludeStorage, excludeMissingPreimages bool, start []byte, maxResults int) (nextKey []byte) {
 	missingPreimages := 0
-	c.onRoot(self.trie.Hash())
-	it := trie.NewIterator(self.trie.NodeIterator(nil))
+	c.OnRoot(s.trie.Hash())
+
+	var count int
+	it := trie.NewIterator(s.trie.NodeIterator(start))
 	for it.Next() {
 		var data Account
 		if err := rlp.DecodeBytes(it.Value, &data); err != nil {
 			panic(err)
 		}
-		addr := common.BytesToAddress(self.trie.GetKey(it.Key))
-		obj := newObject(nil, addr, data)
 		account := DumpAccount{
-			Balance:  data.Balance.String(),
-			Nonce:    data.Nonce,
-			Root:     common.Bytes2Hex(data.Root[:]),
-			CodeHash: common.Bytes2Hex(data.CodeHash),
+			Balance:     data.Balance.String(),
+			Nonce:       data.Nonce,
+			Root:        common.Bytes2Hex(data.Root[:]),
+			CodeHash:    common.Bytes2Hex(data.CodeHash),
+			IsMultiCoin: data.IsMultiCoin,
 		}
-		if emptyAddress == addr {
+		addrBytes := s.trie.GetKey(it.Key)
+		if addrBytes == nil {
 			// Preimage missing
 			missingPreimages++
 			if excludeMissingPreimages {
@@ -111,48 +140,68 @@ func (self *StateDB) dump(c collector, excludeCode, excludeStorage, excludeMissi
 			}
 			account.SecureKey = it.Key
 		}
+		addr := common.BytesToAddress(addrBytes)
+		obj := newObject(nil, addr, data)
 		if !excludeCode {
-			account.Code = common.Bytes2Hex(obj.Code(self.db))
+			account.Code = common.Bytes2Hex(obj.Code(s.db))
 		}
 		if !excludeStorage {
 			account.Storage = make(map[common.Hash]string)
-			storageIt := trie.NewIterator(obj.getTrie(self.db).NodeIterator(nil))
+			storageIt := trie.NewIterator(obj.getTrie(s.db).NodeIterator(nil))
 			for storageIt.Next() {
 				_, content, _, err := rlp.Split(storageIt.Value)
 				if err != nil {
 					log.Error("Failed to decode the value returned by iterator", "error", err)
 					continue
 				}
-				account.Storage[common.BytesToHash(self.trie.GetKey(storageIt.Key))] = common.Bytes2Hex(content)
+				account.Storage[common.BytesToHash(s.trie.GetKey(storageIt.Key))] = common.Bytes2Hex(content)
+			}
+		}
+		c.OnAccount(addr, account)
+		count++
+		if maxResults > 0 && count >= maxResults {
+			if it.Next() {
+				nextKey = it.Key
 			}
+			break
 		}
-		c.onAccount(addr, account)
 	}
 	if missingPreimages > 0 {
 		log.Warn("Dump incomplete due to missing preimages", "missing", missingPreimages)
 	}
+
+	return nextKey
 }
 
 // RawDump returns the entire state an a single large object
-func (self *StateDB) RawDump(excludeCode, excludeStorage, excludeMissingPreimages bool) Dump {
+func (s *StateDB) RawDump(excludeCode, excludeStorage, excludeMissingPreimages bool) Dump {
 	dump := &Dump{
 		Accounts: make(map[common.Address]DumpAccount),
 	}
-	self.dump(dump, excludeCode, excludeStorage, excludeMissingPreimages)
+	s.DumpToCollector(dump, excludeCode, excludeStorage, excludeMissingPreimages, nil, 0)
 	return *dump
 }
 
 // Dump returns a JSON string representing the entire state as a single json-object
-func (self *StateDB) Dump(excludeCode, excludeStorage, excludeMissingPreimages bool) []byte {
-	dump := self.RawDump(excludeCode, excludeStorage, excludeMissingPreimages)
+func (s *StateDB) Dump(excludeCode, excludeStorage, excludeMissingPreimages bool) []byte {
+	dump := s.RawDump(excludeCode, excludeStorage, excludeMissingPreimages)
 	json, err := json.MarshalIndent(dump, "", "    ")
 	if err != nil {
-		fmt.Println("dump err", err)
+		fmt.Println("Dump err", err)
 	}
 	return json
 }
 
 // IterativeDump dumps out accounts as json-objects, delimited by linebreaks on stdout
-func (self *StateDB) IterativeDump(excludeCode, excludeStorage, excludeMissingPreimages bool, output *json.Encoder) {
-	self.dump(iterativeDump(*output), excludeCode, excludeStorage, excludeMissingPreimages)
+func (s *StateDB) IterativeDump(excludeCode, excludeStorage, excludeMissingPreimages bool, output *json.Encoder) {
+	s.DumpToCollector(iterativeDump{output}, excludeCode, excludeStorage, excludeMissingPreimages, nil, 0)
+}
+
+// IteratorDump dumps out a batch of accounts starts with the given start key
+func (s *StateDB) IteratorDump(excludeCode, excludeStorage, excludeMissingPreimages bool, start []byte, maxResults int) IteratorDump {
+	iterator := &IteratorDump{
+		Accounts: make(map[common.Address]DumpAccount),
+	}
+	iterator.Next = s.DumpToCollector(iterator, excludeCode, excludeStorage, excludeMissingPreimages, start, maxResults)
+	return *iterator
 }
diff --git a/core/state/iterator.go b/core/state/iterator.go
index c6d2a48..6a5c73d 100644
--- a/core/state/iterator.go
+++ b/core/state/iterator.go
@@ -20,9 +20,9 @@ import (
 	"bytes"
 	"fmt"
 
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/rlp"
-	"github.com/ava-labs/go-ethereum/trie"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
 )
 
 // NodeIterator is an iterator to traverse the entire state trie post-order,
diff --git a/core/state/journal.go b/core/state/journal.go
index 6e85173..0cc556b 100644
--- a/core/state/journal.go
+++ b/core/state/journal.go
@@ -19,7 +19,7 @@ package state
 import (
 	"math/big"
 
-	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common"
 )
 
 // journalEntry is a modification entry in the state change journal that can be
@@ -90,7 +90,8 @@ type (
 		account *common.Address
 	}
 	resetObjectChange struct {
-		prev *stateObject
+		prev         *stateObject
+		prevdestruct bool
 	}
 	suicideChange struct {
 		account     *common.Address
@@ -130,9 +131,7 @@ type (
 		hash common.Hash
 	}
 	touchChange struct {
-		account   *common.Address
-		prev      bool
-		prevDirty bool
+		account *common.Address
 	}
 )
 
@@ -147,6 +146,9 @@ func (ch createObjectChange) dirtied() *common.Address {
 
 func (ch resetObjectChange) revert(s *StateDB) {
 	s.setStateObject(ch.prev)
+	if !ch.prevdestruct && s.snap != nil {
+		delete(s.snapDestructs, ch.prev.addrHash)
+	}
 }
 
 func (ch resetObjectChange) dirtied() *common.Address {
diff --git a/core/state/snapshot/account.go b/core/state/snapshot/account.go
new file mode 100644
index 0000000..303c2fc
--- /dev/null
+++ b/core/state/snapshot/account.go
@@ -0,0 +1,88 @@
+// Copyright 2019 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 snapshot
+
+import (
+	"bytes"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+// Account is a modified version of a state.Account, where the root is replaced
+// with a byte slice. This format can be used to represent full-consensus format
+// or slim-snapshot format which replaces the empty root and code hash as nil
+// byte slice.
+type Account struct {
+	Nonce       uint64
+	Balance     *big.Int
+	Root        []byte
+	CodeHash    []byte
+	IsMultiCoin bool
+}
+
+// SlimAccount converts a state.Account content into a slim snapshot account
+func SlimAccount(nonce uint64, balance *big.Int, root common.Hash, codehash []byte, isMultiCoin bool) Account {
+	slim := Account{
+		Nonce:       nonce,
+		Balance:     balance,
+		IsMultiCoin: isMultiCoin,
+	}
+	if root != emptyRoot {
+		slim.Root = root[:]
+	}
+	if !bytes.Equal(codehash, emptyCode[:]) {
+		slim.CodeHash = codehash
+	}
+	return slim
+}
+
+// SlimAccountRLP converts a state.Account content into a slim snapshot
+// version RLP encoded.
+func SlimAccountRLP(nonce uint64, balance *big.Int, root common.Hash, codehash []byte, isMultiCoin bool) []byte {
+	data, err := rlp.EncodeToBytes(SlimAccount(nonce, balance, root, codehash, isMultiCoin))
+	if err != nil {
+		panic(err)
+	}
+	return data
+}
+
+// FullAccount decodes the data on the 'slim RLP' format and return
+// the consensus format account.
+func FullAccount(data []byte) (Account, error) {
+	var account Account
+	if err := rlp.DecodeBytes(data, &account); err != nil {
+		return Account{}, err
+	}
+	if len(account.Root) == 0 {
+		account.Root = emptyRoot[:]
+	}
+	if len(account.CodeHash) == 0 {
+		account.CodeHash = emptyCode[:]
+	}
+	return account, nil
+}
+
+// FullAccountRLP converts data on the 'slim RLP' format into the full RLP-format.
+func FullAccountRLP(data []byte) ([]byte, error) {
+	account, err := FullAccount(data)
+	if err != nil {
+		return nil, err
+	}
+	return rlp.EncodeToBytes(account)
+}
diff --git a/core/state/snapshot/conversion.go b/core/state/snapshot/conversion.go
new file mode 100644
index 0000000..dee9ff0
--- /dev/null
+++ b/core/state/snapshot/conversion.go
@@ -0,0 +1,275 @@
+// 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 snapshot
+
+import (
+	"bytes"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb/memorydb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
+)
+
+// trieKV represents a trie key-value pair
+type trieKV struct {
+	key   common.Hash
+	value []byte
+}
+
+type (
+	// trieGeneratorFn is the interface of trie generation which can
+	// be implemented by different trie algorithm.
+	trieGeneratorFn func(in chan (trieKV), out chan (common.Hash))
+
+	// leafCallbackFn is the callback invoked at the leaves of the trie,
+	// returns the subtrie root with the specified subtrie identifier.
+	leafCallbackFn func(hash common.Hash, stat *generateStats) common.Hash
+)
+
+// GenerateAccountTrieRoot takes an account iterator and reproduces the root hash.
+func GenerateAccountTrieRoot(it AccountIterator) (common.Hash, error) {
+	return generateTrieRoot(it, common.Hash{}, stdGenerate, nil, &generateStats{start: time.Now()}, true)
+}
+
+// GenerateStorageTrieRoot takes a storage iterator and reproduces the root hash.
+func GenerateStorageTrieRoot(account common.Hash, it StorageIterator) (common.Hash, error) {
+	return generateTrieRoot(it, account, stdGenerate, nil, &generateStats{start: time.Now()}, true)
+}
+
+// VerifyState takes the whole snapshot tree as the input, traverses all the accounts
+// as well as the corresponding storages and compares the re-computed hash with the
+// original one(state root and the storage root).
+func VerifyState(snaptree *Tree, root common.Hash) error {
+	acctIt, err := snaptree.AccountIterator(root, common.Hash{})
+	if err != nil {
+		return err
+	}
+	defer acctIt.Release()
+
+	got, err := generateTrieRoot(acctIt, common.Hash{}, stdGenerate, func(account common.Hash, stat *generateStats) common.Hash {
+		storageIt, err := snaptree.StorageIterator(root, account, common.Hash{})
+		if err != nil {
+			return common.Hash{}
+		}
+		defer storageIt.Release()
+
+		hash, err := generateTrieRoot(storageIt, account, stdGenerate, nil, stat, false)
+		if err != nil {
+			return common.Hash{}
+		}
+		return hash
+	}, &generateStats{start: time.Now()}, true)
+
+	if err != nil {
+		return err
+	}
+	if got != root {
+		return fmt.Errorf("state root hash mismatch: got %x, want %x", got, root)
+	}
+	return nil
+}
+
+// generateStats is a collection of statistics gathered by the trie generator
+// for logging purposes.
+type generateStats struct {
+	accounts   uint64
+	slots      uint64
+	curAccount common.Hash
+	curSlot    common.Hash
+	start      time.Time
+	lock       sync.RWMutex
+}
+
+// progress records the progress trie generator made recently.
+func (stat *generateStats) progress(accounts, slots uint64, curAccount common.Hash, curSlot common.Hash) {
+	stat.lock.Lock()
+	defer stat.lock.Unlock()
+
+	stat.accounts += accounts
+	stat.slots += slots
+	stat.curAccount = curAccount
+	stat.curSlot = curSlot
+}
+
+// report prints the cumulative progress statistic smartly.
+func (stat *generateStats) report() {
+	stat.lock.RLock()
+	defer stat.lock.RUnlock()
+
+	var ctx []interface{}
+	if stat.curSlot != (common.Hash{}) {
+		ctx = append(ctx, []interface{}{
+			"in", stat.curAccount,
+			"at", stat.curSlot,
+		}...)
+	} else {
+		ctx = append(ctx, []interface{}{"at", stat.curAccount}...)
+	}
+	// Add the usual measurements
+	ctx = append(ctx, []interface{}{"accounts", stat.accounts}...)
+	if stat.slots != 0 {
+		ctx = append(ctx, []interface{}{"slots", stat.slots}...)
+	}
+	ctx = append(ctx, []interface{}{"elapsed", common.PrettyDuration(time.Since(stat.start))}...)
+	log.Info("Generating trie hash from snapshot", ctx...)
+}
+
+// reportDone prints the last log when the whole generation is finished.
+func (stat *generateStats) reportDone() {
+	stat.lock.RLock()
+	defer stat.lock.RUnlock()
+
+	var ctx []interface{}
+	ctx = append(ctx, []interface{}{"accounts", stat.accounts}...)
+	if stat.slots != 0 {
+		ctx = append(ctx, []interface{}{"slots", stat.slots}...)
+	}
+	ctx = append(ctx, []interface{}{"elapsed", common.PrettyDuration(time.Since(stat.start))}...)
+	log.Info("Generated trie hash from snapshot", ctx...)
+}
+
+// generateTrieRoot generates the trie hash based on the snapshot iterator.
+// It can be used for generating account trie, storage trie or even the
+// whole state which connects the accounts and the corresponding storages.
+func generateTrieRoot(it Iterator, account common.Hash, generatorFn trieGeneratorFn, leafCallback leafCallbackFn, stats *generateStats, report bool) (common.Hash, error) {
+	var (
+		in      = make(chan trieKV)         // chan to pass leaves
+		out     = make(chan common.Hash, 1) // chan to collect result
+		stoplog = make(chan bool, 1)        // 1-size buffer, works when logging is not enabled
+		wg      sync.WaitGroup
+	)
+	// Spin up a go-routine for trie hash re-generation
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		generatorFn(in, out)
+	}()
+
+	// Spin up a go-routine for progress logging
+	if report && stats != nil {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+
+			timer := time.NewTimer(0)
+			defer timer.Stop()
+
+			for {
+				select {
+				case <-timer.C:
+					stats.report()
+					timer.Reset(time.Second * 8)
+				case success := <-stoplog:
+					if success {
+						stats.reportDone()
+					}
+					return
+				}
+			}
+		}()
+	}
+	// stop is a helper function to shutdown the background threads
+	// and return the re-generated trie hash.
+	stop := func(success bool) common.Hash {
+		close(in)
+		result := <-out
+		stoplog <- success
+		wg.Wait()
+		return result
+	}
+	var (
+		logged    = time.Now()
+		processed = uint64(0)
+		leaf      trieKV
+		last      common.Hash
+	)
+	// Start to feed leaves
+	for it.Next() {
+		if account == (common.Hash{}) {
+			var (
+				err      error
+				fullData []byte
+			)
+			if leafCallback == nil {
+				fullData, err = FullAccountRLP(it.(AccountIterator).Account())
+				if err != nil {
+					stop(false)
+					return common.Hash{}, err
+				}
+			} else {
+				account, err := FullAccount(it.(AccountIterator).Account())
+				if err != nil {
+					stop(false)
+					return common.Hash{}, err
+				}
+				// Apply the leaf callback. Normally the callback is used to traverse
+				// the storage trie and re-generate the subtrie root.
+				subroot := leafCallback(it.Hash(), stats)
+				if !bytes.Equal(account.Root, subroot.Bytes()) {
+					stop(false)
+					return common.Hash{}, fmt.Errorf("invalid subroot(%x), want %x, got %x", it.Hash(), account.Root, subroot)
+				}
+				fullData, err = rlp.EncodeToBytes(account)
+				if err != nil {
+					stop(false)
+					return common.Hash{}, err
+				}
+			}
+			leaf = trieKV{it.Hash(), fullData}
+		} else {
+			leaf = trieKV{it.Hash(), common.CopyBytes(it.(StorageIterator).Slot())}
+		}
+		in <- leaf
+
+		// Accumulate the generaation statistic if it's required.
+		processed++
+		if time.Since(logged) > 3*time.Second && stats != nil {
+			if account == (common.Hash{}) {
+				stats.progress(processed, 0, it.Hash(), common.Hash{})
+			} else {
+				stats.progress(0, processed, account, it.Hash())
+			}
+			logged, processed = time.Now(), 0
+		}
+		last = it.Hash()
+	}
+	// Commit the last part statistic.
+	if processed > 0 && stats != nil {
+		if account == (common.Hash{}) {
+			stats.progress(processed, 0, last, common.Hash{})
+		} else {
+			stats.progress(0, processed, account, last)
+		}
+	}
+	result := stop(true)
+	return result, nil
+}
+
+// stdGenerate is a very basic hexary trie builder which uses the same Trie
+// as the rest of geth, with no enhancements or optimizations
+func stdGenerate(in chan (trieKV), out chan (common.Hash)) {
+	t, _ := trie.New(common.Hash{}, trie.NewDatabase(memorydb.New()))
+	for leaf := range in {
+		t.TryUpdate(leaf.key[:], leaf.value)
+	}
+	out <- t.Hash()
+}
diff --git a/core/state/snapshot/difflayer.go b/core/state/snapshot/difflayer.go
new file mode 100644
index 0000000..0aef6cf
--- /dev/null
+++ b/core/state/snapshot/difflayer.go
@@ -0,0 +1,553 @@
+// Copyright 2019 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 snapshot
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math"
+	"math/rand"
+	"sort"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/steakknife/bloomfilter"
+)
+
+var (
+	// aggregatorMemoryLimit is the maximum size of the bottom-most diff layer
+	// that aggregates the writes from above until it's flushed into the disk
+	// layer.
+	//
+	// Note, bumping this up might drastically increase the size of the bloom
+	// filters that's stored in every diff layer. Don't do that without fully
+	// understanding all the implications.
+	aggregatorMemoryLimit = uint64(4 * 1024 * 1024)
+
+	// aggregatorItemLimit is an approximate number of items that will end up
+	// in the agregator layer before it's flushed out to disk. A plain account
+	// weighs around 14B (+hash), a storage slot 32B (+hash), a deleted slot
+	// 0B (+hash). Slots are mostly set/unset in lockstep, so thet average at
+	// 16B (+hash). All in all, the average entry seems to be 15+32=47B. Use a
+	// smaller number to be on the safe side.
+	aggregatorItemLimit = aggregatorMemoryLimit / 42
+
+	// bloomTargetError is the target false positive rate when the aggregator
+	// layer is at its fullest. The actual value will probably move around up
+	// and down from this number, it's mostly a ballpark figure.
+	//
+	// Note, dropping this down might drastically increase the size of the bloom
+	// filters that's stored in every diff layer. Don't do that without fully
+	// understanding all the implications.
+	bloomTargetError = 0.02
+
+	// bloomSize is the ideal bloom filter size given the maximum number of items
+	// it's expected to hold and the target false positive error rate.
+	bloomSize = math.Ceil(float64(aggregatorItemLimit) * math.Log(bloomTargetError) / math.Log(1/math.Pow(2, math.Log(2))))
+
+	// bloomFuncs is the ideal number of bits a single entry should set in the
+	// bloom filter to keep its size to a minimum (given it's size and maximum
+	// entry count).
+	bloomFuncs = math.Round((bloomSize / float64(aggregatorItemLimit)) * math.Log(2))
+
+	// the bloom offsets are runtime constants which determines which part of the
+	// the account/storage hash the hasher functions looks at, to determine the
+	// bloom key for an account/slot. This is randomized at init(), so that the
+	// global population of nodes do not all display the exact same behaviour with
+	// regards to bloom content
+	bloomDestructHasherOffset = 0
+	bloomAccountHasherOffset  = 0
+	bloomStorageHasherOffset  = 0
+)
+
+func i