// 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/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/trie"
lru "github.com/hashicorp/golang-lru"
)
// Trie cache generation limit after which to evic trie nodes from memory.
var MaxTrieCacheGen = uint16(120)
const (
// Number of past tries to keep. This value is chosen such that
// reasonable chain reorg depths will hit an existing trie.
maxPastTries = 12
// Number of codehash->size associations to keep.
codeSizeCacheSize = 100000
)
type revision struct {
id int
journalIndex int
}
// 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 ethdb.Database
trie *trie.SecureTrie
pastTries []*trie.SecureTrie
codeSizeCache *lru.Cache
// This map holds 'live' objects, which will get modified while processing a state transition.
stateObjects map[common.Address]*stateObject
stateObjectsDirty map[common.Address]struct{}
stateObjectsDestructed map[common.Address]struct{}
// The refund counter, also used by state transitioning.
refund *big.Int
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 ethdb.Database) (*StateDB, error) {
tr, err := trie.NewSecure(root, db, MaxTrieCacheGen)
if err != nil {
return nil, err
}
csc, _ := lru.New(codeSizeCacheSize)
return &StateDB{
db: db,
trie: tr,
codeSizeCache: csc,
stateObjects: make(map[common.Address]*stateObject),
stateObjectsDirty: make(map[common.Address]struct{}),
stateObjectsDestructed: make(map[common.Address]struct{}),
refund: new(big.Int),
logs: make(map[common.Hash][]*types.Log),
preimages: make(map[common.Hash][]byte),
}, nil
}
// New creates a new statedb by reusing any journalled tries to avoid costly
// disk io.
func (self *StateDB) New(root common.Hash) (*StateDB, error) {
self.lock.Lock()
defer self.lock.Unlock()
tr, err := self.openTrie(root)
if err != nil {
return nil, err
}
return &StateDB{
db: self.db,
trie: tr,
codeSizeCache: self.codeSizeCache,
stateObjects: make(map[common.Address]*stateObject),
stateObjectsDirty: make(map[common.Address]struct{}),
stateObjectsDestructed: make(map[common.Address]struct{}),
refund: new(big.Int),
logs: make(map[common.Hash][]*types.Log),
preimages: make(map[common.Hash][]byte),
}, nil
}
// Reset clears out all emphemeral 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 {
self.lock.Lock()
defer self.lock.Unlock()
tr, err := self.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.stateObjectsDestructed = 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
}
// openTrie creates a trie. It uses an existing trie if one is available
// from the journal if available.
func (self *StateDB) openTrie(root common.Hash) (*trie.SecureTrie, error) {
for i := len(self.pastTries) - 1; i >= 0; i-- {
if self.pastTries[i].Hash() == root {
tr := *self.pastTries[i]
return &tr, nil
}
}
return trie.NewSecure(root, self.db, MaxTrieCacheGen)
}
func (self *StateDB) pushTrie(t *trie.SecureTrie) {
self.lock.Lock()
defer self.lock.Unlock()
if len(self.pastTries) >= maxPastTries {
copy(self.pastTries, self.pastTries[1:])
self.pastTries[len(self.pastTries)-1] = t
} else {
self.pastTries = append(self.pastTries, t)
}
}
func (self *StateDB) AddLog(log *types.Log) {
self.journal = append(self.journal, 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(self.journal, 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
}
func (self *StateDB) AddRefund(gas *big.Int) {
self.journal = append(self.journal, refundChange{prev: new(big.Int).Set(self.refund)})
self.refund.Add(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 {
code := stateObject.Code(self.db)
key := common.BytesToHash(stateObject.CodeHash())
self.codeSizeCache.Add(key, len(code))
return code
}
return nil
}
func (self *StateDB) GetCodeSize(addr common.Address) int {
stateObject := self.getStateObject(addr)
if stateObject == nil {
return 0
}
key := common.BytesToHash(stateObject.CodeHash())
if cached, ok := self.codeSizeCache.Get(key); ok {
return cached.(int)
}
size := len(stateObject.Code(self.db))
if stateObject.dbErr == nil {
self.codeSizeCache.Add(key, size)
}
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())
}
func (self *StateDB) GetState(a common.Address, b common.Hash) common.Hash {
stateObject := self.getStateObject(a)
if stateObject != nil {
return stateObject.GetState(self.db, b)
}
return common.Hash{}
}
// 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(a common.Address) *trie.SecureTrie {
stateObject := self.getStateObject(a)
if stateObject == nil {
return nil
}
cpy := stateObject.deepCopy(self, nil)
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 common.Hash, 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(self.journal, suicideChange{
account: &addr,
prev: stateObject.suicided,
prevbalance: new(big.Int).Set(stateObject.Balance()),
})
stateObject.markSuicided()
stateObject.data.Balance = new(big.Int)
self.stateObjectsDestructed[addr] = struct{}{}
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.trie.Update(addr[:], data)
}
// deleteStateObject removes the given object from the state trie.
func (self *StateDB) deleteStateObject(stateObject *stateObject) {
stateObject.deleted = true
addr := stateObject.Address()
self.trie.Delete(addr[:])
}
// Retrieve a state object given my 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 := self.trie.Get(addr[:])
if len(enc) == 0 {
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.MarkStateObjectDirty)
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
}
// MarkStateObjectDirty adds the specified object to the dirty map to avoid costly
// state object cache iteration to find a handful of modified ones.
func (self *StateDB) MarkStateObjectDirty(addr common.Address) {
self.stateObjectsDirty[addr] = struct{}{}
}
// 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{}, self.MarkStateObjectDirty)
newobj.setNonce(0) // sets the object to dirty
if prev == nil {
self.journal = append(self.journal, createObjectChange{account: &addr})
} else {
self.journal = append(self.journal, 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
}
// When iterating over the storage check the cache first
for h, value := range so.cachedStorage {
cb(h, value)
}
it := trie.NewIterator(so.getTrie(db.db).NodeIterator(nil))
for it.Next() {
// ignore cached values
key := common.BytesToHash(db.trie.GetKey(it.Key))
if _, ok := so.cachedStorage[key]; !ok {
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.trie,
pastTries: self.pastTries,
codeSizeCache: self.codeSizeCache,
stateObjects: make(map[common.Address]*stateObject, len(self.stateObjectsDirty)),
stateObjectsDirty: make(map[common.Address]struct{}, len(self.stateObjectsDirty)),
stateObjectsDestructed: make(map[common.Address]struct{}, len(self.stateObjectsDestructed)),
refund: new(big.Int).Set(self.refund),
logs: make(map[common.Hash][]*types.Log, len(self.logs)),
logSize: self.logSize,
preimages: make(map[common.Hash][]byte),
}
// Copy the dirty states, logs, and preimages
for addr := range self.stateObjectsDirty {
state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state, state.MarkStateObjectDirty)
state.stateObjectsDirty[addr] = struct{}{}
if self.stateObjects[addr].suicided {
state.stateObjectsDestructed[addr] = struct{}{}
}
}
for hash, logs := range self.logs {
state.logs[hash] = make([]*types.Log, len(logs))
copy(state.logs[hash], logs)
}
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, len(self.journal)})
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.
for i := len(self.journal) - 1; i >= snapshot; i-- {
self.journal[i].undo(self)
}
self.journal = self.journal[:snapshot]
// Remove invalidated snapshots from the stack.
self.validRevisions = self.validRevisions[:idx]
}
// GetRefund returns the current value of the refund counter.
// The return value must not be modified by the caller and will become
// invalid at the next call to AddRefund.
func (self *StateDB) GetRefund() *big.Int {
return self.refund
}
// 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 {
for addr := range s.stateObjectsDirty {
stateObject := s.stateObjects[addr]
if stateObject.suicided || (deleteEmptyObjects && stateObject.empty()) {
s.deleteStateObject(stateObject)
} else {
stateObject.updateRoot(s.db)
s.updateStateObject(stateObject)
}
}
// Invalidate journal because reverting across transactions is not allowed.
s.clearJournalAndRefund()
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
}
// Finalise finalises the state by removing the self destructed objects
// in the current stateObjectsDestructed buffer and clears the journal
// as well as the refunds.
//
// Please note that Finalise is used by EIP#98 and is used instead of
// IntermediateRoot.
func (s *StateDB) Finalise() {
for addr := range s.stateObjectsDestructed {
s.deleteStateObject(s.stateObjects[addr])
}
s.clearJournalAndRefund()
}
// DeleteSuicides flags the suicided objects for deletion so that it
// won't be referenced again when called / queried up on.
//
// DeleteSuicides should not be used for consensus related updates
// under any circumstances.
func (s *StateDB) DeleteSuicides() {
// Reset refund so that any used-gas calculations can use this method.
s.clearJournalAndRefund()
for addr := range s.stateObjectsDirty {
stateObject := s.stateObjects[addr]
// If the object has been removed by a suicide
// flag the object as deleted.
if stateObject.suicided {
stateObject.deleted = true
}
delete(s.stateObjectsDirty, addr)
}
}
// Commit commits all state changes to the database.
func (s *StateDB) Commit(deleteEmptyObjects bool) (root common.Hash, err error) {
root, batch := s.CommitBatch(deleteEmptyObjects)
return root, batch.Write()
}
// CommitBatch commits all state changes to a write batch but does not
// execute the batch. It is used to validate state changes against
// the root hash stored in a block.
func (s *StateDB) CommitBatch(deleteEmptyObjects bool) (root common.Hash, batch ethdb.Batch) {
batch = s.db.NewBatch()
root, _ = s.CommitTo(batch, deleteEmptyObjects)
log.Debug("Trie cache stats after commit", "misses", trie.CacheMisses(), "unloads", trie.CacheUnloads())
return root, batch
}
func (s *StateDB) clearJournalAndRefund() {
s.journal = nil
s.validRevisions = s.validRevisions[:0]
s.refund = new(big.Int)
}
// CommitTo writes the state to the given database.
func (s *StateDB) CommitTo(dbw trie.DatabaseWriter, deleteEmptyObjects bool) (root common.Hash, err error) {
defer s.clearJournalAndRefund()
// 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 {
if err := dbw.Put(stateObject.CodeHash(), stateObject.code); err != nil {
return common.Hash{}, err
}
stateObject.dirtyCode = false
}
// Write any storage changes in the state object to its storage trie.
if err := stateObject.CommitTrie(s.db, dbw); 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.CommitTo(dbw)
if err == nil {
s.pushTrie(s.trie)
}
return root, err
}
