core/state: simplify storage trie update and commit (#28030)

This change improves function description and simplifies logic in statedb update and commit operations.

Author: rjl493456442

core/state/state_object.go

@@ -264,12 +264,17 @@ func (s *stateObject) finalise(prefetch bool) {
 	}
 }
 
-// updateTrie writes cached storage modifications into the object's storage trie.
-// It will return nil if the trie has not been loaded and no changes have been
-// made. An error will be returned if the trie can't be loaded/updated correctly.
+// updateTrie is responsible for persisting cached storage changes into the
+// object's storage trie. In case the storage trie is not yet loaded, this
+// function will load the trie automatically. If any issues arise during the
+// loading or updating of the trie, an error will be returned. Furthermore,
+// this function will return the mutated storage trie, or nil if there is no
+// storage change at all.
 func (s *stateObject) updateTrie() (Trie, error) {
 	// Make sure all dirty slots are finalized into the pending storage area
-	s.finalise(false) // Don't prefetch anymore, pull directly if need be
+	s.finalise(false)
+
+	// Short circuit if nothing changed, don't bother with hashing anything
 	if len(s.pendingStorage) == 0 {
 		return s.trie, nil
 	}
@@ -281,14 +286,13 @@ func (s *stateObject) updateTrie() (Trie, error) {
 	var (
 		storage map[common.Hash][]byte
 		origin  map[common.Hash][]byte
-		hasher  = s.db.hasher
 	)
 	tr, err := s.getTrie()
 	if err != nil {
 		s.db.setError(err)
 		return nil, err
 	}
-	// Insert all the pending updates into the trie
+	// Insert all the pending storage updates into the trie
 	usedStorage := make([][]byte, 0, len(s.pendingStorage))
 	for key, value := range s.pendingStorage {
 		// Skip noop changes, persist actual changes
@@ -298,19 +302,18 @@ func (s *stateObject) updateTrie() (Trie, error) {
 		prev := s.originStorage[key]
 		s.originStorage[key] = value
 
-		// rlp-encoded value to be used by the snapshot
-		var snapshotVal []byte
+		var encoded []byte // rlp-encoded value to be used by the snapshot
 		if (value == common.Hash{}) {
 			if err := tr.DeleteStorage(s.address, key[:]); err != nil {
 				s.db.setError(err)
 				return nil, err
 			}
 			s.db.StorageDeleted += 1
 		} else {
-			trimmedVal := common.TrimLeftZeroes(value[:])
 			// Encoding []byte cannot fail, ok to ignore the error.
-			snapshotVal, _ = rlp.EncodeToBytes(trimmedVal)
-			if err := tr.UpdateStorage(s.address, key[:], trimmedVal); err != nil {
+			trimmed := common.TrimLeftZeroes(value[:])
+			encoded, _ = rlp.EncodeToBytes(trimmed)
+			if err := tr.UpdateStorage(s.address, key[:], trimmed); err != nil {
 				s.db.setError(err)
 				return nil, err
 			}
@@ -323,8 +326,8 @@ func (s *stateObject) updateTrie() (Trie, error) {
 				s.db.storages[s.addrHash] = storage
 			}
 		}
-		khash := crypto.HashData(hasher, key[:])
-		storage[khash] = snapshotVal // snapshotVal will be nil if it's deleted
+		khash := crypto.HashData(s.db.hasher, key[:])
+		storage[khash] = encoded // encoded will be nil if it's deleted
 
 		// Cache the original value of mutated storage slots
 		if origin == nil {
@@ -349,21 +352,17 @@ func (s *stateObject) updateTrie() (Trie, error) {
 	if s.db.prefetcher != nil {
 		s.db.prefetcher.used(s.addrHash, s.data.Root, usedStorage)
 	}
-	if len(s.pendingStorage) > 0 {
-		s.pendingStorage = make(Storage)
-	}
+	s.pendingStorage = make(Storage) // reset pending map
 	return tr, nil
 }
 
-// UpdateRoot sets the trie root to the current root hash of. An error
-// will be returned if trie root hash is not computed correctly.
+// updateRoot flushes all cached storage mutations to trie, recalculating the
+// new storage trie root.
 func (s *stateObject) updateRoot() {
+	// Flush cached storage mutations into trie, short circuit if any error
+	// is occurred or there is not change in the trie.
 	tr, err := s.updateTrie()
-	if err != nil {
-		return
-	}
-	// If nothing changed, don't bother with hashing anything
-	if tr == nil {
+	if err != nil || tr == nil {
 		return
 	}
 	// Track the amount of time wasted on hashing the storage trie
@@ -373,22 +372,23 @@ func (s *stateObject) updateRoot() {
 	s.data.Root = tr.Hash()
 }
 
-// commit returns the changes made in storage trie and updates the account data.
+// commit obtains a set of dirty storage trie nodes and updates the account data.
+// The returned set can be nil if nothing to commit. This function assumes all
+// storage mutations have already been flushed into trie by updateRoot.
 func (s *stateObject) commit() (*trienode.NodeSet, error) {
-	tr, err := s.updateTrie()
-	if err != nil {
-		return nil, err
-	}
-	// If nothing changed, don't bother with committing anything
-	if tr == nil {
+	// Short circuit if trie is not even loaded, don't bother with committing anything
+	if s.trie == nil {
 		s.origin = s.data.Copy()
 		return nil, nil
 	}
 	// Track the amount of time wasted on committing the storage trie
 	if metrics.EnabledExpensive {
 		defer func(start time.Time) { s.db.StorageCommits += time.Since(start) }(time.Now())
 	}
-	root, nodes, err := tr.Commit(false)
+	// The trie is currently in an open state and could potentially contain
+	// cached mutations. Call commit to acquire a set of nodes that have been
+	// modified, the set can be nil if nothing to commit.
+	root, nodes, err := s.trie.Commit(false)
 	if err != nil {
 		return nil, err
 	}
@@ -536,3 +536,7 @@ func (s *stateObject) Balance() *big.Int {
 func (s *stateObject) Nonce() uint64 {
 	return s.data.Nonce
 }
+
+func (s *stateObject) Root() common.Hash {
+	return s.data.Root
+}

core/state/statedb.go

@@ -18,7 +18,6 @@
 package state
 
 import (
-	"errors"
 	"fmt"
 	"math/big"
 	"sort"
@@ -48,17 +47,6 @@ type revision struct {
 	journalIndex int
 }
 
-type proofList [][]byte
-
-func (n *proofList) Put(key []byte, value []byte) error {
-	*n = append(*n, value)
-	return nil
-}
-
-func (n *proofList) Delete(key []byte) error {
-	panic("not supported")
-}
-
 // StateDB structs within the ethereum protocol are used to store anything
 // within the merkle trie. StateDBs take care of caching and storing
 // nested states. It's the general query interface to retrieve:
@@ -297,6 +285,7 @@ func (s *StateDB) GetBalance(addr common.Address) *big.Int {
 	return common.Big0
 }
 
+// GetNonce retrieves the nonce from the given address or 0 if object not found
 func (s *StateDB) GetNonce(addr common.Address) uint64 {
 	stateObject := s.getStateObject(addr)
 	if stateObject != nil {
@@ -306,6 +295,16 @@ func (s *StateDB) GetNonce(addr common.Address) uint64 {
 	return 0
 }
 
+// GetStorageRoot retrieves the storage root from the given address or empty
+// if object not found.
+func (s *StateDB) GetStorageRoot(addr common.Address) common.Hash {
+	stateObject := s.getStateObject(addr)
+	if stateObject != nil {
+		return stateObject.Root()
+	}
+	return common.Hash{}
+}
+
 // TxIndex returns the current transaction index set by Prepare.
 func (s *StateDB) TxIndex() int {
 	return s.txIndex
@@ -344,35 +343,6 @@ func (s *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash {
 	return common.Hash{}
 }
 
-// GetProof returns the Merkle proof for a given account.
-func (s *StateDB) GetProof(addr common.Address) ([][]byte, error) {
-	return s.GetProofByHash(crypto.Keccak256Hash(addr.Bytes()))
-}
-
-// GetProofByHash returns the Merkle proof for a given account.
-func (s *StateDB) GetProofByHash(addrHash common.Hash) ([][]byte, error) {
-	var proof proofList
-	err := s.trie.Prove(addrHash[:], &proof)
-	return proof, err
-}
-
-// GetStorageProof returns the Merkle proof for given storage slot.
-func (s *StateDB) GetStorageProof(a common.Address, key common.Hash) ([][]byte, error) {
-	trie, err := s.StorageTrie(a)
-	if err != nil {
-		return nil, err
-	}
-	if trie == nil {
-		return nil, errors.New("storage trie for requested address does not exist")
-	}
-	var proof proofList
-	err = trie.Prove(crypto.Keccak256(key.Bytes()), &proof)
-	if err != nil {
-		return nil, err
-	}
-	return proof, nil
-}
-
 // GetCommittedState retrieves a value from the given account's committed storage trie.
 func (s *StateDB) GetCommittedState(addr common.Address, hash common.Hash) common.Hash {
 	stateObject := s.getStateObject(addr)
@@ -387,21 +357,6 @@ func (s *StateDB) Database() Database {
 	return s.db
 }
 
-// StorageTrie returns the storage trie of an account. The return value is a copy
-// and is nil for non-existent accounts. An error will be returned if storage trie
-// is existent but can't be loaded correctly.
-func (s *StateDB) StorageTrie(addr common.Address) (Trie, error) {
-	stateObject := s.getStateObject(addr)
-	if stateObject == nil {
-		return nil, nil
-	}
-	cpy := stateObject.deepCopy(s)
-	if _, err := cpy.updateTrie(); err != nil {
-		return nil, err
-	}
-	return cpy.getTrie()
-}
-
 func (s *StateDB) HasSelfDestructed(addr common.Address) bool {
 	stateObject := s.getStateObject(addr)
 	if stateObject != nil {

eth/api_debug.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/rlp"
@@ -216,7 +217,6 @@ func (api *DebugAPI) StorageRangeAt(ctx context.Context, blockNrOrHash rpc.Block
 	if err != nil {
 		return StorageRangeResult{}, err
 	}
-
 	if block == nil {
 		return StorageRangeResult{}, fmt.Errorf("block %v not found", blockNrOrHash)
 	}
@@ -226,18 +226,20 @@ func (api *DebugAPI) StorageRangeAt(ctx context.Context, blockNrOrHash rpc.Block
 	}
 	defer release()
 
-	st, err := statedb.StorageTrie(contractAddress)
+	return storageRangeAt(statedb, block.Root(), contractAddress, keyStart, maxResult)
+}
+
+func storageRangeAt(statedb *state.StateDB, root common.Hash, address common.Address, start []byte, maxResult int) (StorageRangeResult, error) {
+	storageRoot := statedb.GetStorageRoot(address)
+	if storageRoot == types.EmptyRootHash || storageRoot == (common.Hash{}) {
+		return StorageRangeResult{}, nil // empty storage
+	}
+	id := trie.StorageTrieID(root, crypto.Keccak256Hash(address.Bytes()), storageRoot)
+	tr, err := trie.NewStateTrie(id, statedb.Database().TrieDB())
 	if err != nil {
 		return StorageRangeResult{}, err
 	}
-	if st == nil {
-		return StorageRangeResult{}, fmt.Errorf("account %x doesn't exist", contractAddress)
-	}
-	return storageRangeAt(st, keyStart, maxResult)
-}
-
-func storageRangeAt(st state.Trie, start []byte, maxResult int) (StorageRangeResult, error) {
-	trieIt, err := st.NodeIterator(start)
+	trieIt, err := tr.NodeIterator(start)
 	if err != nil {
 		return StorageRangeResult{}, err
 	}
@@ -249,7 +251,7 @@ func storageRangeAt(st state.Trie, start []byte, maxResult int) (StorageRangeRes
 			return StorageRangeResult{}, err
 		}
 		e := storageEntry{Value: common.BytesToHash(content)}
-		if preimage := st.GetKey(it.Key); preimage != nil {
+		if preimage := tr.GetKey(it.Key); preimage != nil {
 			preimage := common.BytesToHash(preimage)
 			e.Key = &preimage
 		}

eth/api_debug_test.go

@@ -159,9 +159,10 @@ func TestStorageRangeAt(t *testing.T) {
 
 	// Create a state where account 0x010000... has a few storage entries.
 	var (
-		state, _ = state.New(types.EmptyRootHash, state.NewDatabase(rawdb.NewMemoryDatabase()), nil)
-		addr     = common.Address{0x01}
-		keys     = []common.Hash{ // hashes of Keys of storage
+		db     = state.NewDatabaseWithConfig(rawdb.NewMemoryDatabase(), &trie.Config{Preimages: true})
+		sdb, _ = state.New(types.EmptyRootHash, db, nil)
+		addr   = common.Address{0x01}
+		keys   = []common.Hash{ // hashes of Keys of storage
 			common.HexToHash("340dd630ad21bf010b4e676dbfa9ba9a02175262d1fa356232cfde6cb5b47ef2"),
 			common.HexToHash("426fcb404ab2d5d8e61a3d918108006bbb0a9be65e92235bb10eefbdb6dcd053"),
 			common.HexToHash("48078cfed56339ea54962e72c37c7f588fc4f8e5bc173827ba75cb10a63a96a5"),
@@ -175,8 +176,10 @@ func TestStorageRangeAt(t *testing.T) {
 		}
 	)
 	for _, entry := range storage {
-		state.SetState(addr, *entry.Key, entry.Value)
+		sdb.SetState(addr, *entry.Key, entry.Value)
 	}
+	root, _ := sdb.Commit(0, false)
+	sdb, _ = state.New(root, db, nil)
 
 	// Check a few combinations of limit and start/end.
 	tests := []struct {
@@ -206,11 +209,7 @@ func TestStorageRangeAt(t *testing.T) {
 		},
 	}
 	for _, test := range tests {
-		tr, err := state.StorageTrie(addr)
-		if err != nil {
-			t.Error(err)
-		}
-		result, err := storageRangeAt(tr, test.start, test.limit)
+		result, err := storageRangeAt(sdb, root, addr, test.start, test.limit)
 		if err != nil {
 			t.Error(err)
 		}