// Copyright 2014 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 state provides a caching layer atop the Ethereum state trie.
package state
import (
"fmt"
"math/big"
"sort"
"sync"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/trie"
)
type revision struct {
id int
journalIndex int
}
var (
// emptyState is the known hash of an empty state trie entry.
emptyState = crypto.Keccak256Hash(nil)
// emptyCode is the known hash of the empty EVM bytecode.
emptyCode = crypto.Keccak256Hash(nil)
)
// StateDBs 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:
// * Contracts
// * Accounts
type StateDB struct {
db Database
trie Trie
// This map holds 'live' objects, which will get modified while processing a state transition.
stateObjects map[common.Address]*stateObject
stateObjectsDirty map[common.Address]struct{}
// DB error.
// State objects are used by the consensus core and VM which are
// unable to deal with database-level errors. Any error that occurs
// during a database read is memoized here and will eventually be returned
// by StateDB.Commit.
dbErr error
// The refund counter, also used by state transitioning.
refund uint64
thash, bhash common.Hash
txIndex int
logs map[common.Hash][]*types.Log
logSize uint
preimages map[common.Hash][]byte
// Journal of state modifications. This is the backbone of
// Snapshot and RevertToSnapshot.
journal *journal
validRevisions []revision
nextRevisionId int
lock sync.Mutex
}
// Create a new state from a given trie.
func New(root common.Hash, db Database) (*StateDB, error) {
tr, err := db.OpenTrie(root)
if err != nil {
return nil, err
}
return &StateDB{
db: db,
trie: tr,
stateObjects: make(map[common.Address]*stateObject),
stateObjectsDirty: make(map[common.Address]struct{}),
logs: make(map[common.Hash][]*types.Log),
preimages: make(map[common.Hash][]byte),
journal: newJournal(),
}, nil
}
// setError remembers the first non-nil error it is called with.
func (self *StateDB) setError(err error) {
if self.dbErr == nil {
self.dbErr = err
}
}
func (self *StateDB) Error() error {
return self.dbErr
}
// Reset clears out all ephemeral state objects from the state db, but keeps
// the underlying state trie to avoid reloading data for the next operations.
func (self *StateDB) Reset(root common.Hash) error {
tr, err := self.db.OpenTrie(root)
if err != nil {
return err
}
self.trie = tr
self.stateObjects = make(map[common.Address]*stateObject)
self.stateObjectsDirty = make(map[common.Address]struct{})
self.thash = common.Hash{}
self.bhash = common.Hash{}
self.txIndex = 0
self.logs = make(map[common.Hash][]*types.Log)
self.logSize = 0
self.preimages = make(map[common.Hash][]byte)
self.clearJournalAndRefund()
return nil
}
func (self *StateDB) AddLog(log *types.Log) {
self.journal.append(addLogChange{txhash: self.thash})
log.TxHash = self.thash
log.BlockHash = self.bhash
log.TxIndex = uint(self.txIndex)
log.Index = self.logSize
self.logs[self.thash] = append(self.logs[self.thash], log)
self.logSize++
}
func (self *StateDB) GetLogs(hash common.Hash) []*types.Log {
return self.logs[hash]
}
func (self *StateDB) Logs() []*types.Log {
var logs []*types.Log
for _, lgs := range self.logs {
logs = append(logs, lgs...)
}
return logs
}
// AddPreimage records a SHA3 preimage seen by the VM.
func (self *StateDB) AddPreimage(hash common.Hash, preimage []byte) {
if _, ok := self.preimages[hash]; !ok {
self.journal.append(addPreimageChange{hash: hash})
pi := make([]byte, len(preimage))
copy(pi, preimage)
self.preimages[hash] = pi
}
}
// Preimages returns a list of SHA3 preimages that have been submitted.
func (self *StateDB) Preimages() map[common.Hash][]byte {
return self.preimages
}
// AddRefund adds gas to the refund counter
func (self *StateDB) AddRefund(gas uint64) {
self.journal.append(refundChange{prev: self.refund})
self.refund += gas
}
// SubRefund removes gas from the refund counter.
// This method will panic if the refund counter goes below zero
func (self *StateDB) SubRefund(gas uint64) {
self.journal.append(refundChange{prev: self.refund})
if gas > self.refund {
panic("Refund counter below zero")
}
self.refund -= gas
}
// Exist reports whether the given account address exists in the state.
// Notably this also returns true for suicided accounts.
func (self *StateDB) Exist(addr common.Address) bool {
return self.getStateObject(addr) != nil
}
// Empty returns whether the state object is either non-existent
// or empty according to the EIP161 specification (balance = nonce = code = 0)
func (self *StateDB) Empty(addr common.Address) bool {
so := self.getStateObject(addr)
return so == nil || so.empty()
}
// Retrieve the balance from the given address or 0 if object not found
func (self *StateDB) GetBalance(addr common.Address) *big.Int {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.Balance()
}
return common.Big0
}
func (self *StateDB) GetNonce(addr common.Address) uint64 {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.Nonce()
}
return 0
}
func (self *StateDB) GetCode(addr common.Address) []byte {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.Code(self.db)
}
return nil
}
func (self *StateDB) GetCodeSize(addr common.Address) int {
stateObject := self.getStateObject(addr)
if stateObject == nil {
return 0
}
if stateObject.code != nil {
return len(stateObject.code)
}
size, err := self.db.ContractCodeSize(stateObject.addrHash, common.BytesToHash(stateObject.CodeHash()))
if err != nil {
self.setError(err)
}
return size
}
func (self *StateDB) GetCodeHash(addr common.Address) common.Hash {
stateObject := self.getStateObject(addr)
if stateObject == nil {
return common.Hash{}
}
return common.BytesToHash(stateObject.CodeHash())
}
// GetState retrieves a value from the given account's storage trie.
func (self *StateDB) GetState(addr common.Address, hash common.Hash) common.Hash {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.GetState(self.db, hash)
}
return common.Hash{}
}
// GetCommittedState retrieves a value from the given account's committed storage trie.
func (self *StateDB) GetCommittedState(addr common.Address, hash common.Hash) common.Hash {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.GetCommittedState(self.db, hash)
}
return common.Hash{}
}
// Database retrieves the low level database supporting the lower level trie ops.
func (self *StateDB) Database() Database {
return self.db
}
// StorageTrie returns the storage trie of an account.
// The return value is a copy and is nil for non-existent accounts.
func (self *StateDB) StorageTrie(addr common.Address) Trie {
stateObject := self.getStateObject(addr)
if stateObject == nil {
return nil
}
cpy := stateObject.deepCopy(self)
return cpy.updateTrie(self.db)
}
func (self *StateDB) HasSuicided(addr common.Address) bool {
stateObject := self.getStateObject(addr)
if stateObject != nil {
return stateObject.suicided
}
return false
}
/*
* SETTERS
*/
// AddBalance adds amount to the account associated with addr.
func (self *StateDB) AddBalance(addr common.Address, amount *big.Int) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.AddBalance(amount)
}
}
// SubBalance subtracts amount from the account associated with addr.
func (self *StateDB) SubBalance(addr common.Address, amount *big.Int) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.SubBalance(amount)
}
}
func (self *StateDB) SetBalance(addr common.Address, amount *big.Int) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.SetBalance(amount)
}
}
func (self *StateDB) SetNonce(addr common.Address, nonce uint64) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.SetNonce(nonce)
}
}
func (self *StateDB) SetCode(addr common.Address, code []byte) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.SetCode(crypto.Keccak256Hash(code), code)
}
}
func (self *StateDB) SetState(addr common.Address, key, value common.Hash) {
stateObject := self.GetOrNewStateObject(addr)
if stateObject != nil {
stateObject.SetState(self.db, key, value)
}
}
// Suicide marks the given account as suicided.
// This clears the account balance.
//
// The account's state object is still available until the state is committed,
// getStateObject will return a non-nil account after Suicide.
func (self *StateDB) Suicide(addr common.Address) bool {
stateObject := self.getStateObject(addr)
if stateObject == nil {
return false
}
self.journal.append(suicideChange{
account: &addr,
prev: stateObject.suicided,
prevbalance: new(big.Int).Set(stateObject.Balance()),
})
stateObject.markSuicided()
stateObject.data.Balance = new(big.Int)
return true
}
//
// Setting, updating & deleting state object methods.
//
// updateStateObject writes the given object to the trie.
func (self *StateDB) updateStateObject(stateObject *stateObject) {
addr := stateObject.Address()
data, err := rlp.EncodeToBytes(stateObject)
if err != nil {
panic(fmt.Errorf("can't encode object at %x: %v", addr[:], err))
}
self.setError(self.trie.TryUpdate(addr[:], data))
}
// deleteStateObject removes the given object from the state trie.
func (self *StateDB) deleteStateObject(stateObject *stateObject) {
stateObject.deleted = true
addr := stateObject.Address()
self.setError(self.trie.TryDelete(addr[:]))
}
// Retrieve a state object given by the address. Returns nil if not found.
func (self *StateDB) getStateObject(addr common.Address) (stateObject *stateObject) {
// Prefer 'live' objects.
if obj := self.stateObjects[addr]; obj != nil {
if obj.deleted {
return nil
}
return obj
}
// Load the object from the database.
enc, err := self.trie.TryGet(addr[:])
if len(enc) == 0 {
self.setError(err)
return nil
}
var data Account
if err := rlp.DecodeBytes(enc, &data); err != nil {
log.Error("Failed to decode state object", "addr", addr, "err", err)
return nil
}
// Insert into the live set.
obj := newObject(self, addr, data)
self.setStateObject(obj)
return obj
}
func (self *StateDB) setStateObject(object *stateObject) {
self.stateObjects[object.Address()] = object
}
// Retrieve a state object or create a new state object if nil.
func (self *StateDB) GetOrNewStateObject(addr common.Address) *stateObject {
stateObject := self.getStateObject(addr)
if stateObject == nil || stateObject.deleted {
stateObject, _ = self.createObject(addr)
}
return stateObject
}
// createObject creates a new state object. If there is an existing account with
// the given address, it is overwritten and returned as the second return value.
func (self *StateDB) createObject(addr common.Address) (newobj, prev *stateObject) {
prev = self.getStateObject(addr)
newobj = newObject(self, addr, Account{})
newobj.setNonce(0) // sets the object to dirty
if prev == nil {
self.journal.append(createObjectChange{account: &addr})
} else {
self.journal.append(resetObjectChange{prev: prev})
}
self.setStateObject(newobj)
return newobj, prev
}
// CreateAccount explicitly creates a state object. If a state object with the address
// already exists the balance is carried over to the new account.
//
// CreateAccount is called during the EVM CREATE operation. The situation might arise that
// a contract does the following:
//
// 1. sends funds to sha(account ++ (nonce + 1))
// 2. tx_create(sha(account ++ nonce)) (note that this gets the address of 1)
//
// Carrying over the balance ensures that Ether doesn't disappear.
func (self *StateDB) CreateAccount(addr common.Address) {
new, prev := self.createObject(addr)
if prev != nil {
new.setBalance(prev.data.Balance)
}
}
func (db *StateDB) ForEachStorage(addr common.Address, cb func(key, value common.Hash) bool) {
so := db.getStateObject(addr)
if so == nil {
return
}
it := trie.NewIterator(so.getTrie(db.db).NodeIterator(nil))
for it.Next() {
key := common.BytesToHash(db.trie.GetKey(it.Key))
if value, dirty := so.dirtyStorage[key]; dirty {
cb(key, value)
continue
}
cb(key, common.BytesToHash(it.Value))
}
}
// Copy creates a deep, independent copy of the state.
// Snapshots of the copied state cannot be applied to the copy.
func (self *StateDB) Copy() *StateDB {
self.lock.Lock()
defer self.lock.Unlock()
// Copy all the basic fields, initialize the memory ones
state := &StateDB{
db: self.db,
trie: self.db.CopyTrie(self.trie),
stateObjects: make(map[common.Address]*stateObject, len(self.journal.dirties)),
stateObjectsDirty: make(map[common.Address]struct{}, len(self.journal.dirties)),
refund: self.refund,
logs: make(map[common.Hash][]*types.Log, len(self.logs)),
logSize: self.logSize,
preimages: make(map[common.Hash][]byte),
journal: newJournal(),
}
// Copy the dirty states, logs, and preimages
for addr := range self.journal.dirties {
// As documented [here](https://github.com/ethereum/go-ethereum/pull/16485#issuecomment-380438527),
// and in the Finalise-method, there is a case where an object is in the journal but not
// in the stateObjects: OOG after touch on ripeMD prior to Byzantium. Thus, we need to check for
// nil
if object, exist := self.stateObjects[addr]; exist {
state.stateObjects[addr] = object.deepCopy(state)
state.stateObjectsDirty[addr] = struct{}{}
}
}
// Above, we don't copy the actual journal. This means that if the copy is copied, the
// loop above will be a no-op, since the copy's journal is empty.
// Thus, here we iterate over stateObjects, to enable copies of copies
for addr := range self.stateObjectsDirty {
if _, exist := state.stateObjects[addr]; !exist {
state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state)
state.stateObjectsDirty[addr] = struct{}{}
}
}
for hash, logs := range self.logs {
cpy := make([]*types.Log, len(logs))
for i, l := range logs {
cpy[i] = new(types.Log)
*cpy[i] = *l
}
state.logs[hash] = cpy
}
for hash, preimage := range self.preimages {
state.preimages[hash] = preimage
}
return state
}
// Snapshot returns an identifier for the current revision of the state.
func (self *StateDB) Snapshot() int {
id := self.nextRevisionId
self.nextRevisionId++
self.validRevisions = append(self.validRevisions, revision{id, self.journal.length()})
return id
}
// RevertToSnapshot reverts all state changes made since the given revision.
func (self *StateDB) RevertToSnapshot(revid int) {
// Find the snapshot in the stack of valid snapshots.
idx := sort.Search(len(self.validRevisions), func(i int) bool {
return self.validRevisions[i].id >= revid
})
if idx == len(self.validRevisions) || self.validRevisions[idx].id != revid {
panic(fmt.Errorf("revision id %v cannot be reverted", revid))
}
snapshot := self.validRevisions[idx].journalIndex
// Replay the journal to undo changes and remove invalidated snapshots
self.journal.revert(self, snapshot)
self.validRevisions = self.validRevisions[:idx]
}
// GetRefund returns the current value of the refund counter.
func (self *StateDB) GetRefund() uint64 {
return self.refund
}
// Finalise finalises the state by removing the self destructed objects
// and clears the journal as well as the refunds.
func (s *StateDB) Finalise(deleteEmptyObjects bool) {
for addr := range s.journal.dirties {
stateObject, exist := s.stateObjects[addr]
if !exist {
// ripeMD is 'touched' at block 1714175, in tx 0x1237f737031e40bcde4a8b7e717b2d15e3ecadfe49bb1bbc71ee9deb09c6fcf2
// That tx goes out of gas, and although the notion of 'touched' does not exist there, the
// touch-event will still be recorded in the journal. Since ripeMD is a special snowflake,
// it will persist in the journal even though the journal is reverted. In this special circumstance,
// it may exist in `s.journal.dirties` but not in `s.stateObjects`.
// Thus, we can safely ignore it here
continue
}
if stateObject.suicided || (deleteEmptyObjects && stateObject.empty()) {
s.deleteStateObject(stateObject)
} else {
stateObject.updateRoot(s.db)
s.updateStateObject(stateObject)
}
s.stateObjectsDirty[addr] = struct{}{}
}
// Invalidate journal because reverting across transactions is not allowed.
s.clearJournalAndRefund()
}
// IntermediateRoot computes the current root hash of the state trie.
// It is called in between transactions to get the root hash that
// goes into transaction receipts.
func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
s.Finalise(deleteEmptyObjects)
return s.trie.Hash()
}
// Prepare sets the current transaction hash and index and block hash which is
// used when the EVM emits new state logs.
func (self *StateDB) Prepare(thash, bhash common.Hash, ti int) {
self.thash = thash
self.bhash = bhash
self.txIndex = ti
}
func (s *StateDB) clearJournalAndRefund() {
s.journal = newJournal()
s.validRevisions = s.validRevisions[:0]
s.refund = 0
}
// Commit writes the state to the underlying in-memory trie database.
func (s *StateDB) Commit(deleteEmptyObjects bool) (root common.Hash, err error) {
defer s.clearJournalAndRefund()
for addr := range s.journal.dirties {
s.stateObjectsDirty[addr] = struct{}{}
}
// Commit objects to the trie.
for addr, stateObject := range s.stateObjects {
_, isDirty := s.stateObjectsDirty[addr]
switch {
case stateObject.suicided || (isDirty && deleteEmptyObjects && stateObject.empty()):
// If the object has been removed, don't bother syncing it
// and just mark it for deletion in the trie.
s.deleteStateObject(stateObject)
case isDirty:
// Write any contract code associated with the state object
if stateObject.code != nil && stateObject.dirtyCode {
s.db.TrieDB().InsertBlob(common.BytesToHash(stateObject.CodeHash()), stateObject.code)
stateObject.dirtyCode = false
}
// Write any storage changes in the state object to its storage trie.
if err := stateObject.CommitTrie(s.db); err != nil {
return common.Hash{}, err
}
// Update the object in the main account trie.
s.updateStateObject(stateObject)
}
delete(s.stateObjectsDirty, addr)
}
// Write trie changes.
root, err = s.trie.Commit(func(leaf []byte, parent common.Hash) error {
var account Account
if err := rlp.DecodeBytes(leaf, &account); err != nil {
return nil
}
if account.Root != emptyState {
s.db.TrieDB().Reference(account.Root, parent)
}
code := common.BytesToHash(account.CodeHash)
if code != emptyCode {
s.db.TrieDB().Reference(code, parent)
}
return nil
})
log.Debug("Trie cache stats after commit", "misses", trie.CacheMisses(), "unloads", trie.CacheUnloads())
return root, err
}
