[release/1.4.16] core/state: implement reverts by journaling all changes

This commit replaces the deep-copy based state revert mechanism with a
linear complexity journal. This commit also hides several internal
StateDB methods to limit the number of ways in which calling code can
use the journal incorrectly.

As usual consultation and bug fixes to the initial implementation were
provided by @karalabe, @obscuren and @Arachnid. Thank you!

(cherry picked from commit 1f1ea18)

Author: fjl

accounts/abi/bind/backends/simulated.go

@@ -97,7 +97,8 @@ func (b *SimulatedBackend) ContractCall(contract common.Address, data []byte, pe
 		statedb *state.StateDB
 	)
 	if pending {
-		block, statedb = b.pendingBlock, b.pendingState.Copy()
+		block, statedb = b.pendingBlock, b.pendingState
+		defer statedb.RevertToSnapshot(statedb.Snapshot())
 	} else {
 		block = b.blockchain.CurrentBlock()
 		statedb, _ = b.blockchain.State()
@@ -119,6 +120,7 @@ func (b *SimulatedBackend) ContractCall(contract common.Address, data []byte, pe
 		value:    new(big.Int),
 		data:     data,
 	}
+
 	// Execute the call and return
 	vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), vm.Config{})
 	gaspool := new(core.GasPool).AddGas(common.MaxBig)
@@ -146,8 +148,10 @@ func (b *SimulatedBackend) EstimateGasLimit(sender common.Address, contract *com
 	// Create a copy of the currently pending state db to screw around with
 	var (
 		block   = b.pendingBlock
-		statedb = b.pendingState.Copy()
+		statedb = b.pendingState
 	)
+	defer statedb.RevertToSnapshot(statedb.Snapshot())
+
 	// If there's no code to interact with, respond with an appropriate error
 	if contract != nil {
 		if code := statedb.GetCode(*contract); len(code) == 0 {

cmd/evm/main.go

@@ -223,22 +223,22 @@ type ruleSet struct{}
 
 func (ruleSet) IsHomestead(*big.Int) bool { return true }
 
-func (self *VMEnv) RuleSet() vm.RuleSet        { return ruleSet{} }
-func (self *VMEnv) Vm() vm.Vm                  { return self.evm }
-func (self *VMEnv) Db() vm.Database            { return self.state }
-func (self *VMEnv) MakeSnapshot() vm.Database  { return self.state.Copy() }
-func (self *VMEnv) SetSnapshot(db vm.Database) { self.state.Set(db.(*state.StateDB)) }
-func (self *VMEnv) Origin() common.Address     { return *self.transactor }
-func (self *VMEnv) BlockNumber() *big.Int      { return common.Big0 }
-func (self *VMEnv) Coinbase() common.Address   { return *self.transactor }
-func (self *VMEnv) Time() *big.Int             { return self.time }
-func (self *VMEnv) Difficulty() *big.Int       { return common.Big1 }
-func (self *VMEnv) BlockHash() []byte          { return make([]byte, 32) }
-func (self *VMEnv) Value() *big.Int            { return self.value }
-func (self *VMEnv) GasLimit() *big.Int         { return big.NewInt(1000000000) }
-func (self *VMEnv) VmType() vm.Type            { return vm.StdVmTy }
-func (self *VMEnv) Depth() int                 { return 0 }
-func (self *VMEnv) SetDepth(i int)             { self.depth = i }
+func (self *VMEnv) RuleSet() vm.RuleSet       { return ruleSet{} }
+func (self *VMEnv) Vm() vm.Vm                 { return self.evm }
+func (self *VMEnv) Db() vm.Database           { return self.state }
+func (self *VMEnv) SnapshotDatabase() int     { return self.state.Snapshot() }
+func (self *VMEnv) RevertToSnapshot(snap int) { self.state.RevertToSnapshot(snap) }
+func (self *VMEnv) Origin() common.Address    { return *self.transactor }
+func (self *VMEnv) BlockNumber() *big.Int     { return common.Big0 }
+func (self *VMEnv) Coinbase() common.Address  { return *self.transactor }
+func (self *VMEnv) Time() *big.Int            { return self.time }
+func (self *VMEnv) Difficulty() *big.Int      { return common.Big1 }
+func (self *VMEnv) BlockHash() []byte         { return make([]byte, 32) }
+func (self *VMEnv) Value() *big.Int           { return self.value }
+func (self *VMEnv) GasLimit() *big.Int        { return big.NewInt(1000000000) }
+func (self *VMEnv) VmType() vm.Type           { return vm.StdVmTy }
+func (self *VMEnv) Depth() int                { return 0 }
+func (self *VMEnv) SetDepth(i int)            { self.depth = i }
 func (self *VMEnv) GetHash(n uint64) common.Hash {
 	if self.block.Number().Cmp(big.NewInt(int64(n))) == 0 {
 		return self.block.Hash()

core/chain_makers.go

@@ -131,7 +131,7 @@ func (b *BlockGen) AddUncheckedReceipt(receipt *types.Receipt) {
 // TxNonce returns the next valid transaction nonce for the
 // account at addr. It panics if the account does not exist.
 func (b *BlockGen) TxNonce(addr common.Address) uint64 {
-	if !b.statedb.HasAccount(addr) {
+	if !b.statedb.Exist(addr) {
 		panic("account does not exist")
 	}
 	return b.statedb.GetNonce(addr)

core/execution.go

@@ -85,7 +85,7 @@ func exec(env vm.Environment, caller vm.ContractRef, address, codeAddr *common.A
 		createAccount = true
 	}
 
-	snapshotPreTransfer := env.MakeSnapshot()
+	snapshotPreTransfer := env.SnapshotDatabase()
 	var (
 		from = env.Db().GetAccount(caller.Address())
 		to   vm.Account
@@ -129,7 +129,7 @@ func exec(env vm.Environment, caller vm.ContractRef, address, codeAddr *common.A
 	if err != nil && (env.RuleSet().IsHomestead(env.BlockNumber()) || err != vm.CodeStoreOutOfGasError) {
 		contract.UseGas(contract.Gas)
 
-		env.SetSnapshot(snapshotPreTransfer)
+		env.RevertToSnapshot(snapshotPreTransfer)
 	}
 
 	return ret, addr, err
@@ -144,7 +144,7 @@ func execDelegateCall(env vm.Environment, caller vm.ContractRef, originAddr, toA
 		return nil, common.Address{}, vm.DepthError
 	}
 
-	snapshot := env.MakeSnapshot()
+	snapshot := env.SnapshotDatabase()
 
 	var to vm.Account
 	if !env.Db().Exist(*toAddr) {
@@ -162,7 +162,7 @@ func execDelegateCall(env vm.Environment, caller vm.ContractRef, originAddr, toA
 	if err != nil {
 		contract.UseGas(contract.Gas)
 
-		env.SetSnapshot(snapshot)
+		env.RevertToSnapshot(snapshot)
 	}
 
 	return ret, addr, err

core/state/dump.go

@@ -52,7 +52,7 @@ func (self *StateDB) RawDump() Dump {
 			panic(err)
 		}
 
-		obj := NewObject(common.BytesToAddress(addr), data, nil)
+		obj := newObject(nil, common.BytesToAddress(addr), data, nil)
 		account := DumpAccount{
 			Balance:  data.Balance.String(),
 			Nonce:    data.Nonce,

core/state/journal.go

@@ -0,0 +1,117 @@
+// Copyright 2016 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
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+type journalEntry interface {
+	undo(*StateDB)
+}
+
+type journal []journalEntry
+
+type (
+	// Changes to the account trie.
+	createObjectChange struct {
+		account *common.Address
+	}
+	resetObjectChange struct {
+		prev *StateObject
+	}
+	deleteAccountChange struct {
+		account     *common.Address
+		prev        bool // whether account had already suicided
+		prevbalance *big.Int
+	}
+
+	// Changes to individual accounts.
+	balanceChange struct {
+		account *common.Address
+		prev    *big.Int
+	}
+	nonceChange struct {
+		account *common.Address
+		prev    uint64
+	}
+	storageChange struct {
+		account       *common.Address
+		key, prevalue common.Hash
+	}
+	codeChange struct {
+		account            *common.Address
+		prevcode, prevhash []byte
+	}
+
+	// Changes to other state values.
+	refundChange struct {
+		prev *big.Int
+	}
+	addLogChange struct {
+		txhash common.Hash
+	}
+)
+
+func (ch createObjectChange) undo(s *StateDB) {
+	s.GetStateObject(*ch.account).deleted = true
+	delete(s.stateObjects, *ch.account)
+	delete(s.stateObjectsDirty, *ch.account)
+}
+
+func (ch resetObjectChange) undo(s *StateDB) {
+	s.setStateObject(ch.prev)
+}
+
+func (ch deleteAccountChange) undo(s *StateDB) {
+	obj := s.GetStateObject(*ch.account)
+	if obj != nil {
+		obj.remove = ch.prev
+		obj.setBalance(ch.prevbalance)
+	}
+}
+
+func (ch balanceChange) undo(s *StateDB) {
+	s.GetStateObject(*ch.account).setBalance(ch.prev)
+}
+
+func (ch nonceChange) undo(s *StateDB) {
+	s.GetStateObject(*ch.account).setNonce(ch.prev)
+}
+
+func (ch codeChange) undo(s *StateDB) {
+	s.GetStateObject(*ch.account).setCode(common.BytesToHash(ch.prevhash), ch.prevcode)
+}
+
+func (ch storageChange) undo(s *StateDB) {
+	s.GetStateObject(*ch.account).setState(ch.key, ch.prevalue)
+}
+
+func (ch refundChange) undo(s *StateDB) {
+	s.refund = ch.prev
+}
+
+func (ch addLogChange) undo(s *StateDB) {
+	logs := s.logs[ch.txhash]
+	if len(logs) == 1 {
+		delete(s.logs, ch.txhash)
+	} else {
+		s.logs[ch.txhash] = logs[:len(logs)-1]
+	}
+}

core/state/managed_state_test.go

@@ -29,11 +29,8 @@ func create() (*ManagedState, *account) {
 	db, _ := ethdb.NewMemDatabase()
 	statedb, _ := New(common.Hash{}, db)
 	ms := ManageState(statedb)
-	so := &StateObject{address: addr}
-	so.SetNonce(100)
-	ms.StateDB.stateObjects[addr] = so
-	ms.accounts[addr] = newAccount(so)
-
+	ms.StateDB.SetNonce(addr, 100)
+	ms.accounts[addr] = newAccount(ms.StateDB.GetStateObject(addr))
 	return ms, ms.accounts[addr]
 }
 

core/state/state_object.go

@@ -66,6 +66,7 @@ func (self Storage) Copy() Storage {
 type StateObject struct {
 	address common.Address // Ethereum address of this account
 	data    Account
+	db      *StateDB
 
 	// DB error.
 	// State objects are used by the consensus core and VM which are
@@ -99,15 +100,15 @@ type Account struct {
 	CodeHash []byte
 }
 
-// NewObject creates a state object.
-func NewObject(address common.Address, data Account, onDirty func(addr common.Address)) *StateObject {
+// newObject creates a state object.
+func newObject(db *StateDB, address common.Address, data Account, onDirty func(addr common.Address)) *StateObject {
 	if data.Balance == nil {
 		data.Balance = new(big.Int)
 	}
 	if data.CodeHash == nil {
 		data.CodeHash = emptyCodeHash
 	}
-	return &StateObject{address: address, data: data, cachedStorage: make(Storage), dirtyStorage: make(Storage), onDirty: onDirty}
+	return &StateObject{db: db, address: address, data: data, cachedStorage: make(Storage), dirtyStorage: make(Storage), onDirty: onDirty}
 }
 
 // EncodeRLP implements rlp.Encoder.
@@ -122,7 +123,7 @@ func (self *StateObject) setError(err error) {
 	}
 }
 
-func (self *StateObject) MarkForDeletion() {
+func (self *StateObject) markForDeletion() {
 	self.remove = true
 	if self.onDirty != nil {
 		self.onDirty(self.Address())
@@ -163,7 +164,16 @@ func (self *StateObject) GetState(db trie.Database, key common.Hash) common.Hash
 }
 
 // SetState updates a value in account storage.
-func (self *StateObject) SetState(key, value common.Hash) {
+func (self *StateObject) SetState(db trie.Database, key, value common.Hash) {
+	self.db.journal = append(self.db.journal, storageChange{
+		account:  &self.address,
+		key:      key,
+		prevalue: self.GetState(db, key),
+	})
+	self.setState(key, value)
+}
+
+func (self *StateObject) setState(key, value common.Hash) {
 	self.cachedStorage[key] = value
 	self.dirtyStorage[key] = value
 
@@ -189,7 +199,7 @@ func (self *StateObject) updateTrie(db trie.Database) {
 }
 
 // UpdateRoot sets the trie root to the current root hash of
-func (self *StateObject) UpdateRoot(db trie.Database) {
+func (self *StateObject) updateRoot(db trie.Database) {
 	self.updateTrie(db)
 	self.data.Root = self.trie.Hash()
 }
@@ -232,6 +242,14 @@ func (c *StateObject) SubBalance(amount *big.Int) {
 }
 
 func (self *StateObject) SetBalance(amount *big.Int) {
+	self.db.journal = append(self.db.journal, balanceChange{
+		account: &self.address,
+		prev:    new(big.Int).Set(self.data.Balance),
+	})
+	self.setBalance(amount)
+}
+
+func (self *StateObject) setBalance(amount *big.Int) {
 	self.data.Balance = amount
 	if self.onDirty != nil {
 		self.onDirty(self.Address())
@@ -242,8 +260,8 @@ func (self *StateObject) SetBalance(amount *big.Int) {
 // Return the gas back to the origin. Used by the Virtual machine or Closures
 func (c *StateObject) ReturnGas(gas, price *big.Int) {}
 
-func (self *StateObject) Copy(db trie.Database, onDirty func(addr common.Address)) *StateObject {
-	stateObject := NewObject(self.address, self.data, onDirty)
+func (self *StateObject) deepCopy(db *StateDB, onDirty func(addr common.Address)) *StateObject {
+	stateObject := newObject(db, self.address, self.data, onDirty)
 	stateObject.trie = self.trie
 	stateObject.code = self.code
 	stateObject.dirtyStorage = self.dirtyStorage.Copy()
@@ -280,6 +298,16 @@ func (self *StateObject) Code(db trie.Database) []byte {
 }
 
 func (self *StateObject) SetCode(codeHash common.Hash, code []byte) {
+	prevcode := self.Code(self.db.db)
+	self.db.journal = append(self.db.journal, codeChange{
+		account:  &self.address,
+		prevhash: self.CodeHash(),
+		prevcode: prevcode,
+	})
+	self.setCode(codeHash, code)
+}
+
+func (self *StateObject) setCode(codeHash common.Hash, code []byte) {
 	self.code = code
 	self.data.CodeHash = codeHash[:]
 	self.dirtyCode = true
@@ -290,6 +318,14 @@ func (self *StateObject) SetCode(codeHash common.Hash, code []byte) {
 }
 
 func (self *StateObject) SetNonce(nonce uint64) {
+	self.db.journal = append(self.db.journal, nonceChange{
+		account: &self.address,
+		prev:    self.data.Nonce,
+	})
+	self.setNonce(nonce)
+}
+
+func (self *StateObject) setNonce(nonce uint64) {
 	self.data.Nonce = nonce
 	if self.onDirty != nil {
 		self.onDirty(self.Address())
@@ -322,7 +358,7 @@ func (self *StateObject) ForEachStorage(cb func(key, value common.Hash) bool) {
 		cb(h, value)
 	}
 
-	it := self.trie.Iterator()
+	it := self.getTrie(self.db.db).Iterator()
 	for it.Next() {
 		// ignore cached values
 		key := common.BytesToHash(self.trie.GetKey(it.Key))