core/state: move revision-handling into journal

core/state/journal.go

@@ -17,13 +17,20 @@
 package state
 
 import (
+	"fmt"
 	"maps"
+	"sort"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/holiman/uint256"
 )
 
+type revision struct {
+	id           int
+	journalIndex int
+}
+
 // journalEntry is a modification entry in the state change journal that can be
 // reverted on demand.
 type journalEntry interface {
@@ -43,6 +50,9 @@ type journalEntry interface {
 type journal struct {
 	entries []journalEntry         // Current changes tracked by the journal
 	dirties map[common.Address]int // Dirty accounts and the number of changes
+
+	validRevisions []revision
+	nextRevisionId int
 }
 
 // newJournal creates a new initialized journal.
@@ -52,6 +62,40 @@ func newJournal() *journal {
 	}
 }
 
+// Reset clears the journal, after this operation the journal can be used
+// anew. It is semantically similar to calling 'newJournal', but the underlying
+// slices can be reused
+func (j *journal) Reset() {
+	j.entries = j.entries[:0]
+	j.validRevisions = j.validRevisions[:0]
+	j.dirties = make(map[common.Address]int)
+	j.nextRevisionId = 0
+}
+
+// Snapshot returns an identifier for the current revision of the state.
+func (j *journal) Snapshot() int {
+	id := j.nextRevisionId
+	j.nextRevisionId++
+	j.validRevisions = append(j.validRevisions, revision{id, j.length()})
+	return id
+}
+
+// RevertToSnapshot reverts all state changes made since the given revision.
+func (j *journal) RevertToSnapshot(revid int, s *StateDB) {
+	// Find the snapshot in the stack of valid snapshots.
+	idx := sort.Search(len(j.validRevisions), func(i int) bool {
+		return j.validRevisions[i].id >= revid
+	})
+	if idx == len(j.validRevisions) || j.validRevisions[idx].id != revid {
+		panic(fmt.Errorf("revision id %v cannot be reverted", revid))
+	}
+	snapshot := j.validRevisions[idx].journalIndex
+
+	// Replay the journal to undo changes and remove invalidated snapshots
+	j.revert(s, snapshot)
+	j.validRevisions = j.validRevisions[:idx]
+}
+
 // append inserts a new modification entry to the end of the change journal.
 func (j *journal) append(entry journalEntry) {
 	j.entries = append(j.entries, entry)

core/state/statedb.go

@@ -23,7 +23,6 @@ import (
 	"maps"
 	"math/big"
 	"slices"
-	"sort"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -48,11 +47,6 @@ import (
 // TriesInMemory represents the number of layers that are kept in RAM.
 const TriesInMemory = 128
 
-type revision struct {
-	id           int
-	journalIndex int
-}
-
 type mutationType int
 
 const (
@@ -144,8 +138,6 @@ type StateDB struct {
 	// Journal of state modifications. This is the backbone of
 	// Snapshot and RevertToSnapshot.
 	journal *journal
-	validRevisions []revision
-	nextRevisionId int
 
 	// State witness if cross validation is needed
 	witness *stateless.Witness
@@ -703,8 +695,6 @@ func (s *StateDB) Copy() *StateDB {
 		logSize:              s.logSize,
 		preimages:            maps.Clone(s.preimages),
 		journal:              s.journal.copy(),
-		validRevisions:       slices.Clone(s.validRevisions),
-		nextRevisionId:       s.nextRevisionId,
 
 		// In order for the block producer to be able to use and make additions
 		// to the snapshot tree, we need to copy that as well. Otherwise, any
@@ -750,26 +740,12 @@ func (s *StateDB) Copy() *StateDB {
 
 // Snapshot returns an identifier for the current revision of the state.
 func (s *StateDB) Snapshot() int {
-	id := s.nextRevisionId
-	s.nextRevisionId++
-	s.validRevisions = append(s.validRevisions, revision{id, s.journal.length()})
-	return id
+	return s.journal.Snapshot()
 }
 
 // RevertToSnapshot reverts all state changes made since the given revision.
 func (s *StateDB) RevertToSnapshot(revid int) {
-	// Find the snapshot in the stack of valid snapshots.
-	idx := sort.Search(len(s.validRevisions), func(i int) bool {
-		return s.validRevisions[i].id >= revid
-	})
-	if idx == len(s.validRevisions) || s.validRevisions[idx].id != revid {
-		panic(fmt.Errorf("revision id %v cannot be reverted", revid))
-	}
-	snapshot := s.validRevisions[idx].journalIndex
-
-	// Replay the journal to undo changes and remove invalidated snapshots
-	s.journal.revert(s, snapshot)
-	s.validRevisions = s.validRevisions[:idx]
+	s.journal.RevertToSnapshot(revid, s)
 }
 
 // GetRefund returns the current value of the refund counter.
@@ -983,11 +959,8 @@ func (s *StateDB) SetTxContext(thash common.Hash, ti int) {
 }
 
 func (s *StateDB) clearJournalAndRefund() {
-	if len(s.journal.entries) > 0 {
-		s.journal = newJournal()
+	s.journal.Reset()
 	s.refund = 0
-	}
-	s.validRevisions = s.validRevisions[:0] // Snapshots can be created without journal entries
 }
 
 // fastDeleteStorage is the function that efficiently deletes the storage trie