path: root/core/state/statedb.go

// 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
}

func (self *StateDB) AddRefund(gas uint64) {
    self.journal.append(refundChange{prev: self.refund})
    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())
}

func (self *StateDB) GetState(addr common.Address, bhash common.Hash) common.Hash {
    stateObject := self.getStateObject(addr)
    if stateObject != nil {
        return stateObject.GetState(self.db, bhash)
    }
    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
    }

    // 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.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
}