12 files changed, 1112 insertions, 289 deletions

diff --git a/core/rawdb/accessors_chain.go b/core/rawdb/accessors_chain.go
index fdfd6ec..cd48885 100644
--- a/core/rawdb/accessors_chain.go
+++ b/core/rawdb/accessors_chain.go
@@ -23,10 +23,11 @@ import (
 
 	"github.com/ava-labs/coreth/core/types"
 	"github.com/ava-labs/coreth/params"
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/ethdb"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 // ReadCanonicalHash retrieves the hash assigned to a canonical block number.
@@ -68,7 +69,7 @@ func ReadAllHashes(db ethdb.Iteratee, number uint64) []common.Hash {
 	prefix := headerKeyPrefix(number)
 
 	hashes := make([]common.Hash, 0, 1)
-	it := db.NewIteratorWithPrefix(prefix)
+	it := db.NewIterator(prefix, nil)
 	defer it.Release()
 
 	for it.Next() {
@@ -79,6 +80,39 @@ func ReadAllHashes(db ethdb.Iteratee, number uint64) []common.Hash {
 	return hashes
 }
 
+// ReadAllCanonicalHashes retrieves all canonical number and hash mappings at the
+// certain chain range. If the accumulated entries reaches the given threshold,
+// abort the iteration and return the semi-finish result.
+func ReadAllCanonicalHashes(db ethdb.Iteratee, from uint64, to uint64, limit int) ([]uint64, []common.Hash) {
+	// Short circuit if the limit is 0.
+	if limit == 0 {
+		return nil, nil
+	}
+	var (
+		numbers []uint64
+		hashes  []common.Hash
+	)
+	// Construct the key prefix of start point.
+	start, end := headerHashKey(from), headerHashKey(to)
+	it := db.NewIterator(nil, start)
+	defer it.Release()
+
+	for it.Next() {
+		if bytes.Compare(it.Key(), end) >= 0 {
+			break
+		}
+		if key := it.Key(); len(key) == len(headerPrefix)+8+1 && bytes.Equal(key[len(key)-1:], headerHashSuffix) {
+			numbers = append(numbers, binary.BigEndian.Uint64(key[len(headerPrefix):len(headerPrefix)+8]))
+			hashes = append(hashes, common.BytesToHash(it.Value()))
+			// If the accumulated entries reaches the limit threshold, return.
+			if len(numbers) >= limit {
+				break
+			}
+		}
+	}
+	return numbers, hashes
+}
+
 // ReadHeaderNumber returns the header number assigned to a hash.
 func ReadHeaderNumber(db ethdb.KeyValueReader, hash common.Hash) *uint64 {
 	data, _ := db.Get(headerNumberKey(hash))
@@ -153,6 +187,32 @@ func WriteHeadFastBlockHash(db ethdb.KeyValueWriter, hash common.Hash) {
 	}
 }
 
+// ReadLastPivotNumber retrieves the number of the last pivot block. If the node
+// full synced, the last pivot will always be nil.
+func ReadLastPivotNumber(db ethdb.KeyValueReader) *uint64 {
+	data, _ := db.Get(lastPivotKey)
+	if len(data) == 0 {
+		return nil
+	}
+	var pivot uint64
+	if err := rlp.DecodeBytes(data, &pivot); err != nil {
+		log.Error("Invalid pivot block number in database", "err", err)
+		return nil
+	}
+	return &pivot
+}
+
+// WriteLastPivotNumber stores the number of the last pivot block.
+func WriteLastPivotNumber(db ethdb.KeyValueWriter, pivot uint64) {
+	enc, err := rlp.EncodeToBytes(pivot)
+	if err != nil {
+		log.Crit("Failed to encode pivot block number", "err", err)
+	}
+	if err := db.Put(lastPivotKey, enc); err != nil {
+		log.Crit("Failed to store pivot block number", "err", err)
+	}
+}
+
 // ReadFastTrieProgress retrieves the number of tries nodes fast synced to allow
 // reporting correct numbers across restarts.
 func ReadFastTrieProgress(db ethdb.KeyValueReader) uint64 {
@@ -171,20 +231,66 @@ func WriteFastTrieProgress(db ethdb.KeyValueWriter, count uint64) {
 	}
 }
 
+// ReadTxIndexTail retrieves the number of oldest indexed block
+// whose transaction indices has been indexed. If the corresponding entry
+// is non-existent in database it means the indexing has been finished.
+func ReadTxIndexTail(db ethdb.KeyValueReader) *uint64 {
+	data, _ := db.Get(txIndexTailKey)
+	if len(data) != 8 {
+		return nil
+	}
+	number := binary.BigEndian.Uint64(data)
+	return &number
+}
+
+// WriteTxIndexTail stores the number of oldest indexed block
+// into database.
+func WriteTxIndexTail(db ethdb.KeyValueWriter, number uint64) {
+	if err := db.Put(txIndexTailKey, encodeBlockNumber(number)); err != nil {
+		log.Crit("Failed to store the transaction index tail", "err", err)
+	}
+}
+
+// ReadFastTxLookupLimit retrieves the tx lookup limit used in fast sync.
+func ReadFastTxLookupLimit(db ethdb.KeyValueReader) *uint64 {
+	data, _ := db.Get(fastTxLookupLimitKey)
+	if len(data) != 8 {
+		return nil
+	}
+	number := binary.BigEndian.Uint64(data)
+	return &number
+}
+
+// WriteFastTxLookupLimit stores the txlookup limit used in fast sync into database.
+func WriteFastTxLookupLimit(db ethdb.KeyValueWriter, number uint64) {
+	if err := db.Put(fastTxLookupLimitKey, encodeBlockNumber(number)); err != nil {
+		log.Crit("Failed to store transaction lookup limit for fast sync", "err", err)
+	}
+}
+
 // ReadHeaderRLP retrieves a block header in its raw RLP database encoding.
 func ReadHeaderRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
+	// First try to look up the data in ancient database. Extra hash
+	// comparison is necessary since ancient database only maintains
+	// the canonical data.
 	data, _ := db.Ancient(freezerHeaderTable, number)
-	if len(data) == 0 {
-		data, _ = db.Get(headerKey(number, hash))
-		// In the background freezer is moving data from leveldb to flatten files.
-		// So during the first check for ancient db, the data is not yet in there,
-		// but when we reach into leveldb, the data was already moved. That would
-		// result in a not found error.
-		if len(data) == 0 {
-			data, _ = db.Ancient(freezerHeaderTable, number)
-		}
+	if len(data) > 0 && crypto.Keccak256Hash(data) == hash {
+		return data
 	}
-	return data
+	// Then try to look up the data in leveldb.
+	data, _ = db.Get(headerKey(number, hash))
+	if len(data) > 0 {
+		return data
+	}
+	// In the background freezer is moving data from leveldb to flatten files.
+	// So during the first check for ancient db, the data is not yet in there,
+	// but when we reach into leveldb, the data was already moved. That would
+	// result in a not found error.
+	data, _ = db.Ancient(freezerHeaderTable, number)
+	if len(data) > 0 && crypto.Keccak256Hash(data) == hash {
+		return data
+	}
+	return nil // Can't find the data anywhere.
 }
 
 // HasHeader verifies the existence of a block header corresponding to the hash.
@@ -251,9 +357,43 @@ func deleteHeaderWithoutNumber(db ethdb.KeyValueWriter, hash common.Hash, number
 
 // ReadBodyRLP retrieves the block body (transactions and uncles) in RLP encoding.
 func ReadBodyRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
+	// First try to look up the data in ancient database. Extra hash
+	// comparison is necessary since ancient database only maintains
+	// the canonical data.
+	data, _ := db.Ancient(freezerBodiesTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
+		}
+	}
+	// Then try to look up the data in leveldb.
+	data, _ = db.Get(blockBodyKey(number, hash))
+	if len(data) > 0 {
+		return data
+	}
+	// In the background freezer is moving data from leveldb to flatten files.
+	// So during the first check for ancient db, the data is not yet in there,
+	// but when we reach into leveldb, the data was already moved. That would
+	// result in a not found error.
+	data, _ = db.Ancient(freezerBodiesTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
+		}
+	}
+	return nil // Can't find the data anywhere.
+}
+
+// ReadCanonicalBodyRLP retrieves the block body (transactions and uncles) for the canonical
+// block at number, in RLP encoding.
+func ReadCanonicalBodyRLP(db ethdb.Reader, number uint64) rlp.RawValue {
+	// If it's an ancient one, we don't need the canonical hash
 	data, _ := db.Ancient(freezerBodiesTable, number)
 	if len(data) == 0 {
-		data, _ = db.Get(blockBodyKey(number, hash))
+		// Need to get the hash
+		data, _ = db.Get(blockBodyKey(number, ReadCanonicalHash(db, number)))
 		// In the background freezer is moving data from leveldb to flatten files.
 		// So during the first check for ancient db, the data is not yet in there,
 		// but when we reach into leveldb, the data was already moved. That would
@@ -315,18 +455,33 @@ func DeleteBody(db ethdb.KeyValueWriter, hash common.Hash, number uint64) {
 
 // ReadTdRLP retrieves a block's total difficulty corresponding to the hash in RLP encoding.
 func ReadTdRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
+	// First try to look up the data in ancient database. Extra hash
+	// comparison is necessary since ancient database only maintains
+	// the canonical data.
 	data, _ := db.Ancient(freezerDifficultyTable, number)
-	if len(data) == 0 {
-		data, _ = db.Get(headerTDKey(number, hash))
-		// In the background freezer is moving data from leveldb to flatten files.
-		// So during the first check for ancient db, the data is not yet in there,
-		// but when we reach into leveldb, the data was already moved. That would
-		// result in a not found error.
-		if len(data) == 0 {
-			data, _ = db.Ancient(freezerDifficultyTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
 		}
 	}
-	return data
+	// Then try to look up the data in leveldb.
+	data, _ = db.Get(headerTDKey(number, hash))
+	if len(data) > 0 {
+		return data
+	}
+	// In the background freezer is moving data from leveldb to flatten files.
+	// So during the first check for ancient db, the data is not yet in there,
+	// but when we reach into leveldb, the data was already moved. That would
+	// result in a not found error.
+	data, _ = db.Ancient(freezerDifficultyTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
+		}
+	}
+	return nil // Can't find the data anywhere.
 }
 
 // ReadTd retrieves a block's total difficulty corresponding to the hash.
@@ -375,18 +530,33 @@ func HasReceipts(db ethdb.Reader, hash common.Hash, number uint64) bool {
 
 // ReadReceiptsRLP retrieves all the transaction receipts belonging to a block in RLP encoding.
 func ReadReceiptsRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
+	// First try to look up the data in ancient database. Extra hash
+	// comparison is necessary since ancient database only maintains
+	// the canonical data.
 	data, _ := db.Ancient(freezerReceiptTable, number)
-	if len(data) == 0 {
-		data, _ = db.Get(blockReceiptsKey(number, hash))
-		// In the background freezer is moving data from leveldb to flatten files.
-		// So during the first check for ancient db, the data is not yet in there,
-		// but when we reach into leveldb, the data was already moved. That would
-		// result in a not found error.
-		if len(data) == 0 {
-			data, _ = db.Ancient(freezerReceiptTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
 		}
 	}
-	return data
+	// Then try to look up the data in leveldb.
+	data, _ = db.Get(blockReceiptsKey(number, hash))
+	if len(data) > 0 {
+		return data
+	}
+	// In the background freezer is moving data from leveldb to flatten files.
+	// So during the first check for ancient db, the data is not yet in there,
+	// but when we reach into leveldb, the data was already moved. That would
+	// result in a not found error.
+	data, _ = db.Ancient(freezerReceiptTable, number)
+	if len(data) > 0 {
+		h, _ := db.Ancient(freezerHashTable, number)
+		if common.BytesToHash(h) == hash {
+			return data
+		}
+	}
+	return nil // Can't find the data anywhere.
 }
 
 // ReadRawReceipts retrieves all the transaction receipts belonging to a block.
diff --git a/core/rawdb/accessors_indexes.go b/core/rawdb/accessors_indexes.go
index 1dd478a..bf3ba07 100644
--- a/core/rawdb/accessors_indexes.go
+++ b/core/rawdb/accessors_indexes.go
@@ -17,14 +17,15 @@
 package rawdb
 
 import (
+	"bytes"
 	"math/big"
 
 	"github.com/ava-labs/coreth/core/types"
 	"github.com/ava-labs/coreth/params"
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/ethdb"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 // ReadTxLookupEntry retrieves the positional metadata associated with a transaction
@@ -52,20 +53,44 @@ func ReadTxLookupEntry(db ethdb.Reader, hash common.Hash) *uint64 {
 	return &entry.BlockIndex
 }
 
-// WriteTxLookupEntries stores a positional metadata for every transaction from
+// writeTxLookupEntry stores a positional metadata for a transaction,
+// enabling hash based transaction and receipt lookups.
+func writeTxLookupEntry(db ethdb.KeyValueWriter, hash common.Hash, numberBytes []byte) {
+	if err := db.Put(txLookupKey(hash), numberBytes); err != nil {
+		log.Crit("Failed to store transaction lookup entry", "err", err)
+	}
+}
+
+// WriteTxLookupEntries is identical to WriteTxLookupEntry, but it works on
+// a list of hashes
+func WriteTxLookupEntries(db ethdb.KeyValueWriter, number uint64, hashes []common.Hash) {
+	numberBytes := new(big.Int).SetUint64(number).Bytes()
+	for _, hash := range hashes {
+		writeTxLookupEntry(db, hash, numberBytes)
+	}
+}
+
+// WriteTxLookupEntriesByBlock stores a positional metadata for every transaction from
 // a block, enabling hash based transaction and receipt lookups.
-func WriteTxLookupEntries(db ethdb.KeyValueWriter, block *types.Block) {
-	number := block.Number().Bytes()
+func WriteTxLookupEntriesByBlock(db ethdb.KeyValueWriter, block *types.Block) {
+	numberBytes := block.Number().Bytes()
 	for _, tx := range block.Transactions() {
-		if err := db.Put(txLookupKey(tx.Hash()), number); err != nil {
-			log.Crit("Failed to store transaction lookup entry", "err", err)
-		}
+		writeTxLookupEntry(db, tx.Hash(), numberBytes)
 	}
 }
 
 // DeleteTxLookupEntry removes all transaction data associated with a hash.
 func DeleteTxLookupEntry(db ethdb.KeyValueWriter, hash common.Hash) {
-	db.Delete(txLookupKey(hash))
+	if err := db.Delete(txLookupKey(hash)); err != nil {
+		log.Crit("Failed to delete transaction lookup entry", "err", err)
+	}
+}
+
+// DeleteTxLookupEntries removes all transaction lookups for a given block.
+func DeleteTxLookupEntries(db ethdb.KeyValueWriter, hashes []common.Hash) {
+	for _, hash := range hashes {
+		DeleteTxLookupEntry(db, hash)
+	}
 }
 
 // ReadTransaction retrieves a specific transaction from the database, along with
@@ -129,3 +154,24 @@ func WriteBloomBits(db ethdb.KeyValueWriter, bit uint, section uint64, head comm
 		log.Crit("Failed to store bloom bits", "err", err)
 	}
 }
+
+// DeleteBloombits removes all compressed bloom bits vector belonging to the
+// given section range and bit index.
+func DeleteBloombits(db ethdb.Database, bit uint, from uint64, to uint64) {
+	start, end := bloomBitsKey(bit, from, common.Hash{}), bloomBitsKey(bit, to, common.Hash{})
+	it := db.NewIterator(nil, start)
+	defer it.Release()
+
+	for it.Next() {
+		if bytes.Compare(it.Key(), end) >= 0 {
+			break
+		}
+		if len(it.Key()) != len(bloomBitsPrefix)+2+8+32 {
+			continue
+		}
+		db.Delete(it.Key())
+	}
+	if it.Error() != nil {
+		log.Crit("Failed to delete bloom bits", "err", it.Error())
+	}
+}
diff --git a/core/rawdb/accessors_metadata.go b/core/rawdb/accessors_metadata.go
index 7a17123..c5e5655 100644
--- a/core/rawdb/accessors_metadata.go
+++ b/core/rawdb/accessors_metadata.go
@@ -20,10 +20,10 @@ import (
 	"encoding/json"
 
 	"github.com/ava-labs/coreth/params"
-	"github.com/ava-labs/go-ethereum/common"
-	"github.com/ava-labs/go-ethereum/ethdb"
-	"github.com/ava-labs/go-ethereum/log"
-	"github.com/ava-labs/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 // ReadDatabaseVersion retrieves the version number of the database.
@@ -79,20 +79,3 @@ func WriteChainConfig(db ethdb.KeyValueWriter, hash common.Hash, cfg *params.Cha
 		log.Crit("Failed to store chain config", "err", err)
 	}
 }
-
-// ReadPreimage retrieves a single preimage of the provided hash.
-func ReadPreimage(db ethdb.KeyValueReader, hash common.Hash) []byte {
-	data, _ := db.Get(preimageKey(hash))
-	return data
-}
-
-// WritePreimages writes the provided set of preimages to the database.
-func WritePreimages(db ethdb.KeyValueWriter, preimages map[common.Hash][]byte) {
-	for hash, preimage := range preimages {
-		if err := db.Put(preimageKey(hash), preimage); err != nil {
-			log.Crit("Failed to store trie preimage", "err", err)
-		}
-	}
-	preimageCounter.Inc(int64(len(preimages)))
-	preimageHitCounter.Inc(int64(len(preimages)))
-}
diff --git a/core/rawdb/accessors_snapshot.go b/core/rawdb/accessors_snapshot.go
new file mode 100644
index 0000000..ecd4e65
--- /dev/null
+++ b/core/rawdb/accessors_snapshot.go
@@ -0,0 +1,120 @@
+// 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 rawdb
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+// ReadSnapshotRoot retrieves the root of the block whose state is contained in
+// the persisted snapshot.
+func ReadSnapshotRoot(db ethdb.KeyValueReader) common.Hash {
+	data, _ := db.Get(snapshotRootKey)
+	if len(data) != common.HashLength {
+		return common.Hash{}
+	}
+	return common.BytesToHash(data)
+}
+
+// WriteSnapshotRoot stores the root of the block whose state is contained in
+// the persisted snapshot.
+func WriteSnapshotRoot(db ethdb.KeyValueWriter, root common.Hash) {
+	if err := db.Put(snapshotRootKey, root[:]); err != nil {
+		log.Crit("Failed to store snapshot root", "err", err)
+	}
+}
+
+// DeleteSnapshotRoot deletes the hash of the block whose state is contained in
+// the persisted snapshot. Since snapshots are not immutable, this  method can
+// be used during updates, so a crash or failure will mark the entire snapshot
+// invalid.
+func DeleteSnapshotRoot(db ethdb.KeyValueWriter) {
+	if err := db.Delete(snapshotRootKey); err != nil {
+		log.Crit("Failed to remove snapshot root", "err", err)
+	}
+}
+
+// ReadAccountSnapshot retrieves the snapshot entry of an account trie leaf.
+func ReadAccountSnapshot(db ethdb.KeyValueReader, hash common.Hash) []byte {
+	data, _ := db.Get(accountSnapshotKey(hash))
+	return data
+}
+
+// WriteAccountSnapshot stores the snapshot entry of an account trie leaf.
+func WriteAccountSnapshot(db ethdb.KeyValueWriter, hash common.Hash, entry []byte) {
+	if err := db.Put(accountSnapshotKey(hash), entry); err != nil {
+		log.Crit("Failed to store account snapshot", "err", err)
+	}
+}
+
+// DeleteAccountSnapshot removes the snapshot entry of an account trie leaf.
+func DeleteAccountSnapshot(db ethdb.KeyValueWriter, hash common.Hash) {
+	if err := db.Delete(accountSnapshotKey(hash)); err != nil {
+		log.Crit("Failed to delete account snapshot", "err", err)
+	}
+}
+
+// ReadStorageSnapshot retrieves the snapshot entry of an storage trie leaf.
+func ReadStorageSnapshot(db ethdb.KeyValueReader, accountHash, storageHash common.Hash) []byte {
+	data, _ := db.Get(storageSnapshotKey(accountHash, storageHash))
+	return data
+}
+
+// WriteStorageSnapshot stores the snapshot entry of an storage trie leaf.
+func WriteStorageSnapshot(db ethdb.KeyValueWriter, accountHash, storageHash common.Hash, entry []byte) {
+	if err := db.Put(storageSnapshotKey(accountHash, storageHash), entry); err != nil {
+		log.Crit("Failed to store storage snapshot", "err", err)
+	}
+}
+
+// DeleteStorageSnapshot removes the snapshot entry of an storage trie leaf.
+func DeleteStorageSnapshot(db ethdb.KeyValueWriter, accountHash, storageHash common.Hash) {
+	if err := db.Delete(storageSnapshotKey(accountHash, storageHash)); err != nil {
+		log.Crit("Failed to delete storage snapshot", "err", err)
+	}
+}
+
+// IterateStorageSnapshots returns an iterator for walking the entire storage
+// space of a specific account.
+func IterateStorageSnapshots(db ethdb.Iteratee, accountHash common.Hash) ethdb.Iterator {
+	return db.NewIterator(storageSnapshotsKey(accountHash), nil)
+}
+
+// ReadSnapshotJournal retrieves the serialized in-memory diff layers saved at
+// the last shutdown. The blob is expected to be max a few 10s of megabytes.
+func ReadSnapshotJournal(db ethdb.KeyValueReader) []byte {
+	data, _ := db.Get(snapshotJournalKey)
+	return data
+}
+
+// WriteSnapshotJournal stores the serialized in-memory diff layers to save at
+// shutdown. The blob is expected to be max a few 10s of megabytes.
+func WriteSnapshotJournal(db ethdb.KeyValueWriter, journal []byte) {
+	if err := db.Put(snapshotJournalKey, journal); err != nil {
+		log.Crit("Failed to store snapshot journal", "err", err)
+	}
+}
+
+// DeleteSnapshotJournal deletes the serialized in-memory diff layers saved at
+// the last shutdown
+func DeleteSnapshotJournal(db ethdb.KeyValueWriter) {
+	if err := db.Delete(snapshotJournalKey); err != nil {
+		log.Crit("Failed to remove snapshot journal", "err", err)
+	}
+}
diff --git a/core/rawdb/accessors_state.go b/core/rawdb/accessors_state.go
new file mode 100644
index 0000000..6112de0
--- /dev/null
+++ b/core/rawdb/accessors_state.go
@@ -0,0 +1,96 @@
+// 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 rawdb
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+// ReadPreimage retrieves a single preimage of the provided hash.
+func ReadPreimage(db ethdb.KeyValueReader, hash common.Hash) []byte {
+	data, _ := db.Get(preimageKey(hash))
+	return data
+}
+
+// WritePreimages writes the provided set of preimages to the database.
+func WritePreimages(db ethdb.KeyValueWriter, preimages map[common.Hash][]byte) {
+	for hash, preimage := range preimages {
+		if err := db.Put(preimageKey(hash), preimage); err != nil {
+			log.Crit("Failed to store trie preimage", "err", err)
+		}
+	}
+	preimageCounter.Inc(int64(len(preimages)))
+	preimageHitCounter.Inc(int64(len(preimages)))
+}
+
+// ReadCode retrieves the contract code of the provided code hash.
+func ReadCode(db ethdb.KeyValueReader, hash common.Hash) []byte {
+	// Try with the legacy code scheme first, if not then try with current
+	// scheme. Since most of the code will be found with legacy scheme.
+	//
+	// todo(rjl493456442) change the order when we forcibly upgrade the code
+	// scheme with snapshot.
+	data, _ := db.Get(hash[:])
+	if len(data) != 0 {
+		return data
+	}
+	return ReadCodeWithPrefix(db, hash)
+}
+
+// ReadCodeWithPrefix retrieves the contract code of the provided code hash.
+// The main difference between this function and ReadCode is this function
+// will only check the existence with latest scheme(with prefix).
+func ReadCodeWithPrefix(db ethdb.KeyValueReader, hash common.Hash) []byte {
+	data, _ := db.Get(codeKey(hash))
+	return data
+}
+
+// WriteCode writes the provided contract code database.
+func WriteCode(db ethdb.KeyValueWriter, hash common.Hash, code []byte) {
+	if err := db.Put(codeKey(hash), code); err != nil {
+		log.Crit("Failed to store contract code", "err", err)
+	}
+}
+
+// DeleteCode deletes the specified contract code from the database.
+func DeleteCode(db ethdb.KeyValueWriter, hash common.Hash) {
+	if err := db.Delete(codeKey(hash)); err != nil {
+		log.Crit("Failed to delete contract code", "err", err)
+	}
+}
+
+// ReadTrieNode retrieves the trie node of the provided hash.
+func ReadTrieNode(db ethdb.KeyValueReader, hash common.Hash) []byte {
+	data, _ := db.Get(hash.Bytes())
+	return data
+}
+
+// WriteTrieNode writes the provided trie node database.
+func WriteTrieNode(db ethdb.KeyValueWriter, hash common.Hash, node []byte) {
+	if err := db.Put(hash.Bytes(), node); err != nil {
+		log.Crit("Failed to store trie node", "err", err)
+	}
+}
+
+// DeleteTrieNode deletes the specified trie node from the database.
+func DeleteTrieNode(db ethdb.KeyValueWriter, hash common.Hash) {
+	if err := db.Delete(hash.Bytes()); err != nil {
+		log.Crit("Failed to delete trie node", "err", err)
+	}
+}
diff --git a/core/rawdb/chain_iterator.go b/core/rawdb/chain_iterator.go
new file mode 100644
index 0000000..3130e92
--- /dev/null
+++ b/core/rawdb/chain_iterator.go
@@ -0,0 +1,304 @@
+// 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 rawdb
+
+import (
+	"runtime"
+	"sync/atomic"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/prque"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
+	"golang.org/x/crypto/sha3"
+)
+
+// InitDatabaseFromFreezer reinitializes an empty database from a previous batch
+// of frozen ancient blocks. The method iterates over all the frozen blocks and
+// injects into the database the block hash->number mappings.
+func InitDatabaseFromFreezer(db ethdb.Database) {
+	// If we can't access the freezer or it's empty, abort
+	frozen, err := db.Ancients()
+	if err != nil || frozen == 0 {
+		return
+	}
+	var (
+		batch  = db.NewBatch()
+		start  = time.Now()
+		logged = start.Add(-7 * time.Second) // Unindex during import is fast, don't double log
+		hash   common.Hash
+	)
+	for i := uint64(0); i < frozen; i++ {
+		// Since the freezer has all data in sequential order on a file,
+		// it would be 'neat' to read more data in one go, and let the
+		// freezerdb return N items (e.g up to 1000 items per go)
+		// That would require an API change in Ancients though
+		if h, err := db.Ancient(freezerHashTable, i); err != nil {
+			log.Crit("Failed to init database from freezer", "err", err)
+		} else {
+			hash = common.BytesToHash(h)
+		}
+		WriteHeaderNumber(batch, hash, i)
+		// If enough data was accumulated in memory or we're at the last block, dump to disk
+		if batch.ValueSize() > ethdb.IdealBatchSize {
+			if err := batch.Write(); err != nil {
+				log.Crit("Failed to write data to db", "err", err)
+			}
+			batch.Reset()
+		}
+		// If we've spent too much time already, notify the user of what we're doing
+		if time.Since(logged) > 8*time.Second {
+			log.Info("Initializing database from freezer", "total", frozen, "number", i, "hash", hash, "elapsed", common.PrettyDuration(time.Since(start)))
+			logged = time.Now()
+		}
+	}
+	if err := batch.Write(); err != nil {
+		log.Crit("Failed to write data to db", "err", err)
+	}
+	batch.Reset()
+
+	WriteHeadHeaderHash(db, hash)
+	WriteHeadFastBlockHash(db, hash)
+	log.Info("Initialized database from freezer", "blocks", frozen, "elapsed", common.PrettyDuration(time.Since(start)))
+}
+
+type blockTxHashes struct {
+	number uint64
+	hashes []common.Hash
+}
+
+// iterateTransactions iterates over all transactions in the (canon) block
+// number(s) given, and yields the hashes on a channel
+func iterateTransactions(db ethdb.Database, from uint64, to uint64, reverse bool) (chan *blockTxHashes, chan struct{}) {
+	// One thread sequentially reads data from db
+	type numberRlp struct {
+		number uint64
+		rlp    rlp.RawValue
+	}
+	if to == from {
+		return nil, nil
+	}
+	threads := to - from
+	if cpus := runtime.NumCPU(); threads > uint64(cpus) {
+		threads = uint64(cpus)
+	}
+	var (
+		rlpCh    = make(chan *numberRlp, threads*2)     // we send raw rlp over this channel
+		hashesCh = make(chan *blockTxHashes, threads*2) // send hashes over hashesCh
+		abortCh  = make(chan struct{})
+	)
+	// lookup runs in one instance
+	lookup := func() {
+		n, end := from, to
+		if reverse {
+			n, end = to-1, from-1
+		}
+		defer close(rlpCh)
+		for n != end {
+			data := ReadCanonicalBodyRLP(db, n)
+			// Feed the block to the aggregator, or abort on interrupt
+			select {
+			case rlpCh <- &numberRlp{n, data}:
+			case <-abortCh:
+				return
+			}
+			if reverse {
+				n--
+			} else {
+				n++
+			}
+		}
+	}
+	// process runs in parallel
+	nThreadsAlive := int32(threads)
+	process := func() {
+		defer func() {
+			// Last processor closes the result channel
+			if atomic.AddInt32(&nThreadsAlive, -1) == 0 {
+				close(hashesCh)
+			}
+		}()
+
+		var hasher = sha3.NewLegacyKeccak256()
+		for data := range rlpCh {
+			it, err := rlp.NewListIterator(data.rlp)
+			if err != nil {
+				log.Warn("tx iteration error", "error", err)
+				return
+			}
+			it.Next()
+			txs := it.Value()
+			txIt, err := rlp.NewListIterator(txs)
+			if err != nil {
+				log.Warn("tx iteration error", "error", err)
+				return
+			}
+			var hashes []common.Hash
+			for txIt.Next() {
+				if err := txIt.Err(); err != nil {
+					log.Warn("tx iteration error", "error", err)
+					return
+				}
+				var txHash common.Hash
+				hasher.Reset()
+				hasher.Write(txIt.Value())
+				hasher.Sum(txHash[:0])
+				hashes = append(hashes, txHash)
+			}
+			result := &blockTxHashes{
+				hashes: hashes,
+				number: data.number,
+			}
+			// Feed the block to the aggregator, or abort on interrupt
+			select {
+			case hashesCh <- result:
+			case <-abortCh:
+				return
+			}
+		}
+	}
+	go lookup() // start the sequential db accessor
+	for i := 0; i < int(threads); i++ {
+		go process()
+	}
+	return hashesCh, abortCh
+}
+
+// IndexTransactions creates txlookup indices of the specified block range.
+//
+// This function iterates canonical chain in reverse order, it has one main advantage:
+// We can write tx index tail flag periodically even without the whole indexing
+// procedure is finished. So that we can resume indexing procedure next time quickly.
+func IndexTransactions(db ethdb.Database, from uint64, to uint64) {
+	// short circuit for invalid range
+	if from >= to {
+		return
+	}
+	var (
+		hashesCh, abortCh = iterateTransactions(db, from, to, true)
+		batch             = db.NewBatch()
+		start             = time.Now()
+		logged            = start.Add(-7 * time.Second)
+		//  Since we iterate in reverse, we expect the first number to come
+		// in to be [to-1]. Therefore, setting lastNum to means that the
+		// prqueue gap-evaluation will work correctly
+		lastNum = to
+		queue   = prque.New(nil)
+		// for stats reporting
+		blocks, txs = 0, 0
+	)
+	defer close(abortCh)