core/state/statedb.go

@@ -970,8 +970,8 @@ func (s *StateDB) Commit(deleteEmptyObjects bool) (common.Hash, error) {
 		storageTrieNodesUpdated int
 		storageTrieNodesDeleted int
 		nodes                   = trie.NewMergedNodeSet()
+		codeWriter              = s.db.DiskDB().NewBatch()
 	)
-	codeWriter := s.db.DiskDB().NewBatch()
 	for addr := range s.stateObjectsDirty {
 		if obj := s.stateObjects[addr]; !obj.deleted {
 			// Write any contract code associated with the state object

trie/committer.go

@@ -33,29 +33,20 @@ type leaf struct {
 // insertion order.
 type committer struct {
 	nodes       *NodeSet
-	tracer      *tracer
 	collectLeaf bool
 }
 
 // newCommitter creates a new committer or picks one from the pool.
-func newCommitter(owner common.Hash, tracer *tracer, collectLeaf bool) *committer {
+func newCommitter(nodeset *NodeSet, collectLeaf bool) *committer {
 	return &committer{
-		nodes:       NewNodeSet(owner),
-		tracer:      tracer,
+		nodes:       nodeset,
 		collectLeaf: collectLeaf,
 	}
 }
 
-// Commit collapses a node down into a hash node and returns it along with
-// the modified nodeset.
-func (c *committer) Commit(n node) (hashNode, *NodeSet) {
-	h := c.commit(nil, n)
-	// Some nodes can be deleted from trie which can't be captured
-	// by committer itself. Iterate all deleted nodes tracked by
-	// tracer and marked them as deleted only if they are present
-	// in database previously.
-	c.tracer.markDeletions(c.nodes)
-	return h.(hashNode), c.nodes
+// Commit collapses a node down into a hash node.
+func (c *committer) Commit(n node) hashNode {
+	return c.commit(nil, n).(hashNode)
 }
 
 // commit collapses a node down into a hash node and returns it.
@@ -74,9 +65,7 @@ func (c *committer) commit(path []byte, n node) node {
 		// If the child is fullNode, recursively commit,
 		// otherwise it can only be hashNode or valueNode.
 		if _, ok := cn.Val.(*fullNode); ok {
-			childV := c.commit(append(path, cn.Key...), cn.Val)
-
-			collapsed.Val = childV
+			collapsed.Val = c.commit(append(path, cn.Key...), cn.Val)
 		}
 		// The key needs to be copied, since we're adding it to the
 		// modified nodeset.
@@ -85,12 +74,6 @@ func (c *committer) commit(path []byte, n node) node {
 		if hn, ok := hashedNode.(hashNode); ok {
 			return hn
 		}
-		// The short node now is embedded in its parent. Mark the node as
-		// deleted if it's present in database previously. It's equivalent
-		// as deletion from database's perspective.
-		if prev := c.tracer.getPrev(path); len(prev) != 0 {
-			c.nodes.markDeleted(path, prev)
-		}
 		return collapsed
 	case *fullNode:
 		hashedKids := c.commitChildren(path, cn)
@@ -101,12 +84,6 @@ func (c *committer) commit(path []byte, n node) node {
 		if hn, ok := hashedNode.(hashNode); ok {
 			return hn
 		}
-		// The full node now is embedded in its parent. Mark the node as
-		// deleted if it's present in database previously. It's equivalent
-		// as deletion from database's perspective.
-		if prev := c.tracer.getPrev(path); len(prev) != 0 {
-			c.nodes.markDeleted(path, prev)
-		}
 		return collapsed
 	case hashNode:
 		return cn
@@ -134,8 +111,7 @@ func (c *committer) commitChildren(path []byte, n *fullNode) [17]node {
 		// Commit the child recursively and store the "hashed" value.
 		// Note the returned node can be some embedded nodes, so it's
 		// possible the type is not hashNode.
-		hashed := c.commit(append(path, byte(i)), child)
-		children[i] = hashed
+		children[i] = c.commit(append(path, byte(i)), child)
 	}
 	// For the 17th child, it's possible the type is valuenode.
 	if n.Children[16] != nil {
@@ -155,6 +131,12 @@ func (c *committer) store(path []byte, n node) node {
 	// usually is leaf node). But small value (less than 32bytes) is not
 	// our target (leaves in account trie only).
 	if hash == nil {
+		// The node is embedded in its parent, in other words, this node
+		// will not be stored in the database independently, mark it as
+		// deleted only if the node was existent in database before.
+		if _, ok := c.nodes.accessList[string(path)]; ok {
+			c.nodes.markDeleted(path)
+		}
 		return n
 	}
 	// We have the hash already, estimate the RLP encoding-size of the node.
@@ -169,7 +151,7 @@ func (c *committer) store(path []byte, n node) node {
 		}
 	)
 	// Collect the dirty node to nodeset for return.
-	c.nodes.markUpdated(path, mnode, c.tracer.getPrev(path))
+	c.nodes.markUpdated(path, mnode)
 
 	// Collect the corresponding leaf node if it's required. We don't check
 	// full node since it's impossible to store value in fullNode. The key

trie/database.go

@@ -792,13 +792,12 @@ func (db *Database) Update(nodes *MergedNodeSet) error {
 	}
 	for _, owner := range order {
 		subset := nodes.sets[owner]
-		for _, path := range subset.updates.order {
-			n, ok := subset.updates.nodes[path]
-			if !ok {
-				return fmt.Errorf("missing node %x %v", owner, path)
+		subset.forEachWithOrder(func(path string, n *memoryNode) {
+			if n.isDeleted() {
+				return // ignore deletion
 			}
 			db.insert(n.hash, int(n.size), n.node)
-		}
+		})
 	}
 	// Link up the account trie and storage trie if the node points
 	// to an account trie leaf.

trie/nodeset.go

@@ -19,6 +19,7 @@ package trie
 import (
 	"fmt"
 	"reflect"
+	"sort"
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -40,8 +41,8 @@ var memoryNodeSize = int(reflect.TypeOf(memoryNode{}).Size())
 
 // memorySize returns the total memory size used by this node.
 // nolint:unused
-func (n *memoryNode) memorySize(key int) int {
-	return int(n.size) + memoryNodeSize + key
+func (n *memoryNode) memorySize(pathlen int) int {
+	return int(n.size) + memoryNodeSize + pathlen
 }
 
 // rlp returns the raw rlp encoded blob of the cached trie node, either directly
@@ -64,7 +65,13 @@ func (n *memoryNode) obj() node {
 	return expandNode(n.hash[:], n.node)
 }
 
+// isDeleted returns the indicator if the node is marked as deleted.
+func (n *memoryNode) isDeleted() bool {
+	return n.hash == (common.Hash{})
+}
+
 // nodeWithPrev wraps the memoryNode with the previous node value.
+// nolint: unused
 type nodeWithPrev struct {
 	*memoryNode
 	prev []byte // RLP-encoded previous value, nil means it's non-existent
@@ -79,64 +86,60 @@ func (n *nodeWithPrev) unwrap() *memoryNode {
 // memorySize returns the total memory size used by this node. It overloads
 // the function in memoryNode by counting the size of previous value as well.
 // nolint: unused
-func (n *nodeWithPrev) memorySize(key int) int {
-	return n.memoryNode.memorySize(key) + len(n.prev)
-}
-
-// nodesWithOrder represents a collection of dirty nodes which includes
-// newly-inserted and updated nodes. The modification order of all nodes
-// is represented by order list.
-type nodesWithOrder struct {
-	order []string                 // the path list of dirty nodes, sort by insertion order
-	nodes map[string]*nodeWithPrev // the map of dirty nodes, keyed by node path
+func (n *nodeWithPrev) memorySize(pathlen int) int {
+	return n.memoryNode.memorySize(pathlen) + len(n.prev)
 }
 
 // NodeSet contains all dirty nodes collected during the commit operation.
 // Each node is keyed by path. It's not thread-safe to use.
 type NodeSet struct {
-	owner   common.Hash       // the identifier of the trie
-	updates *nodesWithOrder   // the set of updated nodes(newly inserted, updated)
-	deletes map[string][]byte // the map of deleted nodes, keyed by node
-	leaves  []*leaf           // the list of dirty leaves
+	owner   common.Hash            // the identifier of the trie
+	nodes   map[string]*memoryNode // the set of dirty nodes(inserted, updated, deleted)
+	leaves  []*leaf                // the list of dirty leaves
+	updates int                    // the count of updated and inserted nodes
+	deletes int                    // the count of deleted nodes
+
+	// The list of accessed nodes, which records the original node value.
+	// The origin value is expected to be nil for newly inserted node
+	// and is expected to be non-nil for other types(updated, deleted).
+	accessList map[string][]byte
 }
 
 // NewNodeSet initializes an empty node set to be used for tracking dirty nodes
 // from a specific account or storage trie. The owner is zero for the account
 // trie and the owning account address hash for storage tries.
-func NewNodeSet(owner common.Hash) *NodeSet {
+func NewNodeSet(owner common.Hash, accessList map[string][]byte) *NodeSet {
 	return &NodeSet{
-		owner: owner,
-		updates: &nodesWithOrder{
-			nodes: make(map[string]*nodeWithPrev),
-		},
-		deletes: make(map[string][]byte),
+		owner:      owner,
+		nodes:      make(map[string]*memoryNode),
+		accessList: accessList,
 	}
 }
 
-/*
-// NewNodeSetWithDeletion initializes the nodeset with provided deletion set.
-func NewNodeSetWithDeletion(owner common.Hash, paths [][]byte, prev [][]byte) *NodeSet {
-	set := NewNodeSet(owner)
-	for i, path := range paths {
-		set.markDeleted(path, prev[i])
+// forEachWithOrder iterates the dirty nodes with the order from bottom to top,
+// right to left, nodes with the longest path will be iterated first.
+func (set *NodeSet) forEachWithOrder(callback func(path string, n *memoryNode)) {
+	var paths sort.StringSlice
+	for path := range set.nodes {
+		paths = append(paths, path)
 	}
-	return set
-}
-*/
-
-// markUpdated marks the node as dirty(newly-inserted or updated) with provided
-// node path, node object along with its previous value.
-func (set *NodeSet) markUpdated(path []byte, node *memoryNode, prev []byte) {
-	set.updates.order = append(set.updates.order, string(path))
-	set.updates.nodes[string(path)] = &nodeWithPrev{
-		memoryNode: node,
-		prev:       prev,
+	// Bottom-up, longest path first
+	sort.Sort(sort.Reverse(paths))
+	for _, path := range paths {
+		callback(path, set.nodes[path])
 	}
 }
 
-// markDeleted marks the node as deleted with provided path and previous value.
-func (set *NodeSet) markDeleted(path []byte, prev []byte) {
-	set.deletes[string(path)] = prev
+// markUpdated marks the node as dirty(newly-inserted or updated).
+func (set *NodeSet) markUpdated(path []byte, node *memoryNode) {
+	set.nodes[string(path)] = node
+	set.updates += 1
+}
+
+// markDeleted marks the node as deleted.
+func (set *NodeSet) markDeleted(path []byte) {
+	set.nodes[string(path)] = &memoryNode{}
+	set.deletes += 1
 }
 
 // addLeaf collects the provided leaf node into set.
@@ -144,16 +147,16 @@ func (set *NodeSet) addLeaf(node *leaf) {
 	set.leaves = append(set.leaves, node)
 }
 
-// Size returns the number of updated and deleted nodes contained in the set.
+// Size returns the number of dirty nodes in set.
 func (set *NodeSet) Size() (int, int) {
-	return len(set.updates.order), len(set.deletes)
+	return set.updates, set.deletes
 }
 
 // Hashes returns the hashes of all updated nodes. TODO(rjl493456442) how can
 // we get rid of it?
 func (set *NodeSet) Hashes() []common.Hash {
 	var ret []common.Hash
-	for _, node := range set.updates.nodes {
+	for _, node := range set.nodes {
 		ret = append(ret, node.hash)
 	}
 	return ret
@@ -163,19 +166,23 @@ func (set *NodeSet) Hashes() []common.Hash {
 func (set *NodeSet) Summary() string {
 	var out = new(strings.Builder)
 	fmt.Fprintf(out, "nodeset owner: %v\n", set.owner)
-	if set.updates != nil {
-		for _, key := range set.updates.order {
-			updated := set.updates.nodes[key]
-			if updated.prev != nil {
-				fmt.Fprintf(out, "  [*]: %x -> %v prev: %x\n", key, updated.hash, updated.prev)
-			} else {
-				fmt.Fprintf(out, "  [+]: %x -> %v\n", key, updated.hash)
+	if set.nodes != nil {
+		for path, n := range set.nodes {
+			// Deletion
+			if n.isDeleted() {
+				fmt.Fprintf(out, "  [-]: %x prev: %x\n", path, set.accessList[path])
+				continue
 			}
+			// Insertion
+			origin, ok := set.accessList[path]
+			if !ok {
+				fmt.Fprintf(out, "  [+]: %x -> %v\n", path, n.hash)
+				continue
+			}
+			// Update
+			fmt.Fprintf(out, "  [*]: %x -> %v prev: %x\n", path, n.hash, origin)
 		}
 	}
-	for k, n := range set.deletes {
-		fmt.Fprintf(out, "  [-]: %x -> %x\n", k, n)
-	}
 	for _, n := range set.leaves {
 		fmt.Fprintf(out, "[leaf]: %v\n", n)
 	}

trie/proof.go

@@ -563,7 +563,7 @@ func VerifyRangeProof(rootHash common.Hash, firstKey []byte, lastKey []byte, key
 	}
 	// Rebuild the trie with the leaf stream, the shape of trie
 	// should be same with the original one.
-	tr := &Trie{root: root, reader: newEmptyReader()}
+	tr := &Trie{root: root, reader: newEmptyReader(), tracer: newTracer()}
 	if empty {
 		tr.root = nil
 	}

trie/tracer.go

@@ -0,0 +1,125 @@
+// Copyright 2022 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 trie
+
+import "github.com/ethereum/go-ethereum/common"
+
+// tracer tracks the changes of trie nodes. During the trie operations,
+// some nodes can be deleted from the trie, while these deleted nodes
+// won't be captured by trie.Hasher or trie.Committer. Thus, these deleted
+// nodes won't be removed from the disk at all. Tracer is an auxiliary tool
+// used to track all insert and delete operations of trie and capture all
+// deleted nodes eventually.
+//
+// The changed nodes can be mainly divided into two categories: the leaf
+// node and intermediate node. The former is inserted/deleted by callers
+// while the latter is inserted/deleted in order to follow the rule of trie.
+// This tool can track all of them no matter the node is embedded in its
+// parent or not, but valueNode is never tracked.
+//
+// Besides, it's also used for recording the original value of the nodes
+// when they are resolved from the disk. The pre-value of the nodes will
+// be used to construct trie history in the future.
+//
+// Note tracer is not thread-safe, callers should be responsible for handling
+// the concurrency issues by themselves.
+type tracer struct {
+	inserts    map[string]struct{}
+	deletes    map[string]struct{}
+	accessList map[string][]byte
+}
+
+// newTracer initializes the tracer for capturing trie changes.
+func newTracer() *tracer {
+	return &tracer{
+		inserts:    make(map[string]struct{}),
+		deletes:    make(map[string]struct{}),
+		accessList: make(map[string][]byte),
+	}
+}
+
+// onRead tracks the newly loaded trie node and caches the rlp-encoded
+// blob internally. Don't change the value outside of function since
+// it's not deep-copied.
+func (t *tracer) onRead(path []byte, val []byte) {
+	t.accessList[string(path)] = val
+}
+
+// onInsert tracks the newly inserted trie node. If it's already
+// in the deletion set (resurrected node), then just wipe it from
+// the deletion set as it's "untouched".
+func (t *tracer) onInsert(path []byte) {
+	if _, present := t.deletes[string(path)]; present {
+		delete(t.deletes, string(path))
+		return
+	}
+	t.inserts[string(path)] = struct{}{}
+}
+
+// onDelete tracks the newly deleted trie node. If it's already
+// in the addition set, then just wipe it from the addition set
+// as it's untouched.
+func (t *tracer) onDelete(path []byte) {
+	if _, present := t.inserts[string(path)]; present {
+		delete(t.inserts, string(path))
+		return
+	}
+	t.deletes[string(path)] = struct{}{}
+}
+
+// reset clears the content tracked by tracer.
+func (t *tracer) reset() {
+	t.inserts = make(map[string]struct{})
+	t.deletes = make(map[string]struct{})
+	t.accessList = make(map[string][]byte)
+}
+
+// copy returns a deep copied tracer instance.
+func (t *tracer) copy() *tracer {
+	var (
+		inserts    = make(map[string]struct{})
+		deletes    = make(map[string]struct{})
+		accessList = make(map[string][]byte)
+	)
+	for path := range t.inserts {
+		inserts[path] = struct{}{}
+	}
+	for path := range t.deletes {
+		deletes[path] = struct{}{}
+	}
+	for path, blob := range t.accessList {
+		accessList[path] = common.CopyBytes(blob)
+	}
+	return &tracer{
+		inserts:    inserts,
+		deletes:    deletes,
+		accessList: accessList,
+	}
+}
+
+// markDeletions puts all tracked deletions into the provided nodeset.
+func (t *tracer) markDeletions(set *NodeSet) {
+	for path := range t.deletes {
+		// It's possible a few deleted nodes were embedded
+		// in their parent before, the deletions can be no
+		// effect by deleting nothing, filter them out.
+		if _, ok := set.accessList[path]; !ok {
+			continue
+		}
+		set.markDeleted([]byte(path))
+	}
+}

trie/tracer_test.go

@@ -0,0 +1,368 @@
+// Copyright 2022 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 trie
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+)
+
+var (
+	tiny = []struct{ k, v string }{
+		{"k1", "v1"},
+		{"k2", "v2"},
+		{"k3", "v3"},
+	}
+	nonAligned = []struct{ k, v string }{
+		{"do", "verb"},
+		{"ether", "wookiedoo"},
+		{"horse", "stallion"},
+		{"shaman", "horse"},
+		{"doge", "coin"},
+		{"dog", "puppy"},
+		{"somethingveryoddindeedthis is", "myothernodedata"},
+	}
+	standard = []struct{ k, v string }{
+		{string(randBytes(32)), "verb"},
+		{string(randBytes(32)), "wookiedoo"},
+		{string(randBytes(32)), "stallion"},
+		{string(randBytes(32)), "horse"},
+		{string(randBytes(32)), "coin"},
+		{string(randBytes(32)), "puppy"},
+		{string(randBytes(32)), "myothernodedata"},
+	}
+)
+
+func TestTrieTracer(t *testing.T) {
+	testTrieTracer(t, tiny)
+	testTrieTracer(t, nonAligned)
+	testTrieTracer(t, standard)
+}
+
+// Tests if the trie diffs are tracked correctly. Tracer should capture
+// all non-leaf dirty nodes, no matter the node is embedded or not.
+func testTrieTracer(t *testing.T, vals []struct{ k, v string }) {
+	db := NewDatabase(rawdb.NewMemoryDatabase())
+	trie := NewEmpty(db)
+
+	// Determine all new nodes are tracked
+	for _, val := range vals {
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	insertSet := copySet(trie.tracer.inserts) // copy before commit
+	deleteSet := copySet(trie.tracer.deletes) // copy before commit
+	root, nodes := trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	seen := setKeys(iterNodes(db, root))
+	if !compareSet(insertSet, seen) {
+		t.Fatal("Unexpected insertion set")
+	}
+	if !compareSet(deleteSet, nil) {
+		t.Fatal("Unexpected deletion set")
+	}
+
+	// Determine all deletions are tracked
+	trie, _ = New(TrieID(root), db)
+	for _, val := range vals {
+		trie.Delete([]byte(val.k))
+	}
+	insertSet, deleteSet = copySet(trie.tracer.inserts), copySet(trie.tracer.deletes)
+	if !compareSet(insertSet, nil) {
+		t.Fatal("Unexpected insertion set")
+	}
+	if !compareSet(deleteSet, seen) {
+		t.Fatal("Unexpected deletion set")
+	}
+}
+
+// Test that after inserting a new batch of nodes and deleting them immediately,
+// the trie tracer should be cleared normally as no operation happened.
+func TestTrieTracerNoop(t *testing.T) {
+	testTrieTracerNoop(t, tiny)
+	testTrieTracerNoop(t, nonAligned)
+	testTrieTracerNoop(t, standard)
+}
+
+func testTrieTracerNoop(t *testing.T, vals []struct{ k, v string }) {
+	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
+	for _, val := range vals {
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	for _, val := range vals {
+		trie.Delete([]byte(val.k))
+	}
+	if len(trie.tracer.inserts) != 0 {
+		t.Fatal("Unexpected insertion set")
+	}
+	if len(trie.tracer.deletes) != 0 {
+		t.Fatal("Unexpected deletion set")
+	}
+}
+
+// Tests if the accessList is correctly tracked.
+func TestAccessList(t *testing.T) {
+	testAccessList(t, tiny)
+	testAccessList(t, nonAligned)
+	testAccessList(t, standard)
+}
+
+func testAccessList(t *testing.T, vals []struct{ k, v string }) {
+	var (
+		db   = NewDatabase(rawdb.NewMemoryDatabase())
+		trie = NewEmpty(db)
+		orig = trie.Copy()
+	)
+	// Create trie from scratch
+	for _, val := range vals {
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	root, nodes := trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, nodes); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+
+	// Update trie
+	trie, _ = New(TrieID(root), db)
+	orig = trie.Copy()
+	for _, val := range vals {
+		trie.Update([]byte(val.k), randBytes(32))
+	}
+	root, nodes = trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, nodes); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+
+	// Add more new nodes
+	trie, _ = New(TrieID(root), db)
+	orig = trie.Copy()
+	var keys []string
+	for i := 0; i < 30; i++ {
+		key := randBytes(32)
+		keys = append(keys, string(key))
+		trie.Update(key, randBytes(32))
+	}
+	root, nodes = trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, nodes); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+
+	// Partial deletions
+	trie, _ = New(TrieID(root), db)
+	orig = trie.Copy()
+	for _, key := range keys {
+		trie.Update([]byte(key), nil)
+	}
+	root, nodes = trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, nodes); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+
+	// Delete all
+	trie, _ = New(TrieID(root), db)
+	orig = trie.Copy()
+	for _, val := range vals {
+		trie.Update([]byte(val.k), nil)
+	}
+	root, nodes = trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, nodes); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+}
+
+// Tests origin values won't be tracked in Iterator or Prover
+func TestAccessListLeak(t *testing.T) {
+	var (
+		db   = NewDatabase(rawdb.NewMemoryDatabase())
+		trie = NewEmpty(db)
+	)
+	// Create trie from scratch
+	for _, val := range standard {
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	root, nodes := trie.Commit(false)
+	db.Update(NewWithNodeSet(nodes))
+
+	var cases = []struct {
+		op func(tr *Trie)
+	}{
+		{
+			func(tr *Trie) {
+				it := tr.NodeIterator(nil)
+				for it.Next(true) {
+				}
+			},
+		},
+		{
+			func(tr *Trie) {
+				it := NewIterator(tr.NodeIterator(nil))
+				for it.Next() {
+				}
+			},
+		},
+		{
+			func(tr *Trie) {
+				for _, val := range standard {
+					tr.Prove([]byte(val.k), 0, rawdb.NewMemoryDatabase())
+				}
+			},
+		},
+	}
+	for _, c := range cases {
+		trie, _ = New(TrieID(root), db)
+		n1 := len(trie.tracer.accessList)
+		c.op(trie)
+		n2 := len(trie.tracer.accessList)
+
+		if n1 != n2 {
+			t.Fatalf("AccessList is leaked, prev %d after %d", n1, n2)
+		}
+	}
+}
+
+// Tests whether the original tree node is correctly deleted after being embedded
+// in its parent due to the smaller size of the original tree node.
+func TestTinyTree(t *testing.T) {
+	var (
+		db   = NewDatabase(rawdb.NewMemoryDatabase())
+		trie = NewEmpty(db)
+	)
+	for _, val := range tiny {
+		trie.Update([]byte(val.k), randBytes(32))
+	}
+	root, set := trie.Commit(false)
+	db.Update(NewWithNodeSet(set))
+
+	trie, _ = New(TrieID(root), db)
+	orig := trie.Copy()
+	for _, val := range tiny {
+		trie.Update([]byte(val.k), []byte(val.v))
+	}
+	root, set = trie.Commit(false)
+	db.Update(NewWithNodeSet(set))
+
+	trie, _ = New(TrieID(root), db)
+	if err := verifyAccessList(orig, trie, set); err != nil {
+		t.Fatalf("Invalid accessList %v", err)
+	}
+}
+
+func compareSet(setA, setB map[string]struct{}) bool {
+	if len(setA) != len(setB) {
+		return false
+	}
+	for key := range setA {
+		if _, ok := setB[key]; !ok {
+			return false
+		}
+	}
+	return true
+}
+
+func forNodes(tr *Trie) map[string][]byte {
+	var (
+		it    = tr.NodeIterator(nil)
+		nodes = make(map[string][]byte)
+	)
+	for it.Next(true) {
+		if it.Leaf() {
+			continue
+		}
+		nodes[string(it.Path())] = common.CopyBytes(it.NodeBlob())
+	}
+	return nodes
+}
+
+func iterNodes(db *Database, root common.Hash) map[string][]byte {
+	tr, _ := New(TrieID(root), db)
+	return forNodes(tr)
+}
+
+func forHashedNodes(tr *Trie) map[string][]byte {
+	var (
+		it    = tr.NodeIterator(nil)
+		nodes = make(map[string][]byte)
+	)
+	for it.Next(true) {
+		if it.Hash() == (common.Hash{}) {
+			continue
+		}
+		nodes[string(it.Path())] = common.CopyBytes(it.NodeBlob())
+	}
+	return nodes
+}
+
+func diffTries(trieA, trieB *Trie) (map[string][]byte, map[string][]byte, map[string][]byte) {
+	var (
+		nodesA = forHashedNodes(trieA)
+		nodesB = forHashedNodes(trieB)
+		inA    = make(map[string][]byte) // hashed nodes in trie a but not b
+		inB    = make(map[string][]byte) // hashed nodes in trie b but not a
+		both   = make(map[string][]byte) // hashed nodes in both tries but different value
+	)
+	for path, blobA := range nodesA {
+		if blobB, ok := nodesB[path]; ok {
+			if bytes.Equal(blobA, blobB) {
+				continue
+			}
+			both[path] = blobA
+			continue
+		}
+		inA[path] = blobA
+	}
+	for path, blobB := range nodesB {
+		if _, ok := nodesA[path]; ok {
+			continue
+		}
+		inB[path] = blobB
+	}
+	return inA, inB, both
+}
+
+func setKeys(set map[string][]byte) map[string]struct{} {
+	keys := make(map[string]struct{})
+	for k := range set {
+		keys[k] = struct{}{}
+	}
+	return keys
+}
+
+func copySet(set map[string]struct{}) map[string]struct{} {
+	copied := make(map[string]struct{})
+	for k := range set {
+		copied[k] = struct{}{}
+	}
+	return copied
+}

trie/trie.go

@@ -81,7 +81,7 @@ func New(id *ID, db NodeReader) (*Trie, error) {
 	trie := &Trie{
 		owner:  id.Owner,
 		reader: reader,
-		//tracer: newTracer(),
+		tracer: newTracer(),
 	}
 	if id.Root != (common.Hash{}) && id.Root != types.EmptyRootHash {
 		rootnode, err := trie.resolveAndTrack(id.Root[:], nil)
@@ -547,7 +547,7 @@ func (t *Trie) resolveAndTrack(n hashNode, prefix []byte) (node, error) {
 // Hash returns the root hash of the trie. It does not write to the
 // database and can be used even if the trie doesn't have one.
 func (t *Trie) Hash() common.Hash {
-	hash, cached, _ := t.hashRoot()
+	hash, cached := t.hashRoot()
 	t.root = cached
 	return common.BytesToHash(hash.(hashNode))
 }
@@ -561,14 +561,14 @@ func (t *Trie) Hash() common.Hash {
 func (t *Trie) Commit(collectLeaf bool) (common.Hash, *NodeSet) {
 	defer t.tracer.reset()
 
+	nodes := NewNodeSet(t.owner, t.tracer.accessList)
+	t.tracer.markDeletions(nodes)
+
 	// Trie is empty and can be classified into two types of situations:
 	// - The trie was empty and no update happens
 	// - The trie was non-empty and all nodes are dropped
 	if t.root == nil {
-		// Wrap tracked deletions as the return
-		set := NewNodeSet(t.owner)
-		t.tracer.markDeletions(set)
-		return types.EmptyRootHash, set
+		return types.EmptyRootHash, nodes
 	}
 	// Derive the hash for all dirty nodes first. We hold the assumption
 	// in the following procedure that all nodes are hashed.
@@ -582,23 +582,23 @@ func (t *Trie) Commit(collectLeaf bool) (common.Hash, *NodeSet) {
 		t.root = hashedNode
 		return rootHash, nil
 	}
-	h := newCommitter(t.owner, t.tracer, collectLeaf)
-	newRoot, nodes := h.Commit(t.root)
-	t.root = newRoot
+	t.root = newCommitter(nodes, collectLeaf).Commit(t.root)
 	return rootHash, nodes
 }
 
 // hashRoot calculates the root hash of the given trie
-func (t *Trie) hashRoot() (node, node, error) {
+func (t *Trie) hashRoot() (node, node) {
 	if t.root == nil {
-		return hashNode(types.EmptyRootHash.Bytes()), nil, nil
+		return hashNode(types.EmptyRootHash.Bytes()), nil
 	}
 	// If the number of changes is below 100, we let one thread handle it
 	h := newHasher(t.unhashed >= 100)
-	defer returnHasherToPool(h)
+	defer func() {
+		returnHasherToPool(h)
+		t.unhashed = 0
+	}()
 	hashed, cached := h.hash(t.root, true)
-	t.unhashed = 0
-	return hashed, cached, nil
+	return hashed, cached
 }
 
 // Reset drops the referenced root node and cleans all internal state.

trie/trie_test.go

@@ -403,6 +403,51 @@ func (randTest) Generate(r *rand.Rand, size int) reflect.Value {
 	return reflect.ValueOf(steps)
 }
 
+func verifyAccessList(old *Trie, new *Trie, set *NodeSet) error {
+	deletes, inserts, updates := diffTries(old, new)
+
+	// Check insertion set
+	for path := range inserts {
+		n, ok := set.nodes[path]
+		if !ok || n.isDeleted() {
+			return errors.New("expect new node")
+		}
+		_, ok = set.accessList[path]
+		if ok {
+			return errors.New("unexpected origin value")
+		}
+	}
+	// Check deletion set
+	for path, blob := range deletes {
+		n, ok := set.nodes[path]
+		if !ok || !n.isDeleted() {
+			return errors.New("expect deleted node")
+		}
+		v, ok := set.accessList[path]
+		if !ok {
+			return errors.New("expect origin value")
+		}
+		if !bytes.Equal(v, blob) {
+			return errors.New("invalid origin value")
+		}
+	}
+	// Check update set
+	for path, blob := range updates {
+		n, ok := set.nodes[path]
+		if !ok || n.isDeleted() {
+			return errors.New("expect updated node")
+		}
+		v, ok := set.accessList[path]
+		if !ok {
+			return errors.New("expect origin value")
+		}
+		if !bytes.Equal(v, blob) {
+			return errors.New("invalid origin value")
+		}
+	}
+	return nil
+}
+
 func runRandTest(rt randTest) bool {
 	var (
 		triedb   = NewDatabase(rawdb.NewMemoryDatabase())
@@ -410,8 +455,6 @@ func runRandTest(rt randTest) bool {
 		values   = make(map[string]string) // tracks content of the trie
 		origTrie = NewEmpty(triedb)
 	)
-	tr.tracer = newTracer()
-
 	for i, step := range rt {
 		// fmt.Printf("{op: %d, key: common.Hex2Bytes(\"%x\"), value: common.Hex2Bytes(\"%x\")}, // step %d\n",
 		// 	step.op, step.key, step.value, i)
@@ -447,24 +490,6 @@ func runRandTest(rt randTest) bool {
 			tr.Hash()
 		case opCommit:
 			root, nodes := tr.Commit(true)
-			// Validity the returned nodeset
-			if nodes != nil {
-				for path, node := range nodes.updates.nodes {
-					blob, _, _ := origTrie.TryGetNode(hexToCompact([]byte(path)))
-					got := node.prev
-					if !bytes.Equal(blob, got) {
-						rt[i].err = fmt.Errorf("prevalue mismatch for 0x%x, got 0x%x want 0x%x", path, got, blob)
-						panic(rt[i].err)
-					}
-				}
-				for path, prev := range nodes.deletes {
-					blob, _, _ := origTrie.TryGetNode(hexToCompact([]byte(path)))
-					if !bytes.Equal(blob, prev) {
-						rt[i].err = fmt.Errorf("prevalue mismatch for 0x%x, got 0x%x want 0x%x", path, prev, blob)
-						return false
-					}
-				}
-			}
 			if nodes != nil {
 				triedb.Update(NewWithNodeSet(nodes))
 			}
@@ -473,13 +498,13 @@ func runRandTest(rt randTest) bool {
 				rt[i].err = err
 				return false
 			}
+			if nodes != nil {
+				if err := verifyAccessList(origTrie, newtr, nodes); err != nil {
+					rt[i].err = err
+					return false
+				}
+			}
 			tr = newtr
-
-			// Enable node tracing. Resolve the root node again explicitly
-			// since it's not captured at the beginning.
-			tr.tracer = newTracer()
-			tr.resolveAndTrack(root.Bytes(), nil)
-
 			origTrie = tr.Copy()
 		case opItercheckhash:
 			checktr := NewEmpty(triedb)
@@ -492,8 +517,6 @@ func runRandTest(rt randTest) bool {
 			}
 		case opNodeDiff:
 			var (
-				inserted = tr.tracer.insertList()
-				deleted  = tr.tracer.deleteList()
 				origIter = origTrie.NodeIterator(nil)
 				curIter  = tr.NodeIterator(nil)
 				origSeen = make(map[string]struct{})
@@ -527,19 +550,19 @@ func runRandTest(rt randTest) bool {
 					deleteExp[path] = struct{}{}
 				}
 			}
-			if len(insertExp) != len(inserted) {
+			if len(insertExp) != len(tr.tracer.inserts) {
 				rt[i].err = fmt.Errorf("insert set mismatch")
 			}
-			if len(deleteExp) != len(deleted) {
+			if len(deleteExp) != len(tr.tracer.deletes) {
 				rt[i].err = fmt.Errorf("delete set mismatch")
 			}
-			for _, insert := range inserted {
-				if _, present := insertExp[string(insert)]; !present {
+			for insert := range tr.tracer.inserts {
+				if _, present := insertExp[insert]; !present {
 					rt[i].err = fmt.Errorf("missing inserted node")
 				}
 			}
-			for _, del := range deleted {
-				if _, present := deleteExp[string(del)]; !present {
+			for del := range tr.tracer.deletes {
+				if _, present := deleteExp[del]; !present {
 					rt[i].err = fmt.Errorf("missing deleted node")
 				}
 			}

trie/util_test.go

@@ -1,305 +0,0 @@
-// Copyright 2022 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 trie
-
-import (
-	"bytes"
-	"testing"
-
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/rawdb"
-	"github.com/ethereum/go-ethereum/core/types"
-)
-
-// Tests if the trie diffs are tracked correctly.
-func TestTrieTracer(t *testing.T) {
-	db := NewDatabase(rawdb.NewMemoryDatabase())
-	trie := NewEmpty(db)
-	trie.tracer = newTracer()
-
-	// Insert a batch of entries, all the nodes should be marked as inserted
-	vals := []struct{ k, v string }{
-		{"do", "verb"},
-		{"ether", "wookiedoo"},
-		{"horse", "stallion"},
-		{"shaman", "horse"},
-		{"doge", "coin"},
-		{"dog", "puppy"},
-		{"somethingveryoddindeedthis is", "myothernodedata"},
-	}
-	for _, val := range vals {
-		trie.Update([]byte(val.k), []byte(val.v))
-	}
-	trie.Hash()
-
-	seen := make(map[string]struct{})
-	it := trie.NodeIterator(nil)
-	for it.Next(true) {
-		if it.Leaf() {
-			continue
-		}
-		seen[string(it.Path())] = struct{}{}
-	}
-	inserted := trie.tracer.insertList()
-	if len(inserted) != len(seen) {
-		t.Fatalf("Unexpected inserted node tracked want %d got %d", len(seen), len(inserted))
-	}
-	for _, k := range inserted {
-		_, ok := seen[string(k)]
-		if !ok {
-			t.Fatalf("Unexpected inserted node")
-		}
-	}
-	deleted := trie.tracer.deleteList()
-	if len(deleted) != 0 {
-		t.Fatalf("Unexpected deleted node tracked %d", len(deleted))
-	}
-
-	// Commit the changes and re-create with new root
-	root, nodes := trie.Commit(false)
-	if err := db.Update(NewWithNodeSet(nodes)); err != nil {
-		t.Fatal(err)
-	}
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-
-	// Delete all the elements, check deletion set
-	for _, val := range vals {
-		trie.Delete([]byte(val.k))
-	}
-	trie.Hash()
-
-	inserted = trie.tracer.insertList()
-	if len(inserted) != 0 {
-		t.Fatalf("Unexpected inserted node tracked %d", len(inserted))
-	}
-	deleted = trie.tracer.deleteList()
-	if len(deleted) != len(seen) {
-		t.Fatalf("Unexpected deleted node tracked want %d got %d", len(seen), len(deleted))
-	}
-	for _, k := range deleted {
-		_, ok := seen[string(k)]
-		if !ok {
-			t.Fatalf("Unexpected inserted node")
-		}
-	}
-}
-
-func TestTrieTracerNoop(t *testing.T) {
-	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
-	trie.tracer = newTracer()
-
-	// Insert a batch of entries, all the nodes should be marked as inserted
-	vals := []struct{ k, v string }{
-		{"do", "verb"},
-		{"ether", "wookiedoo"},
-		{"horse", "stallion"},
-		{"shaman", "horse"},
-		{"doge", "coin"},
-		{"dog", "puppy"},
-		{"somethingveryoddindeedthis is", "myothernodedata"},
-	}
-	for _, val := range vals {
-		trie.Update([]byte(val.k), []byte(val.v))
-	}
-	for _, val := range vals {
-		trie.Delete([]byte(val.k))
-	}
-	if len(trie.tracer.insertList()) != 0 {
-		t.Fatalf("Unexpected inserted node tracked %d", len(trie.tracer.insertList()))
-	}
-	if len(trie.tracer.deleteList()) != 0 {
-		t.Fatalf("Unexpected deleted node tracked %d", len(trie.tracer.deleteList()))
-	}
-}
-
-func TestTrieTracePrevValue(t *testing.T) {
-	db := NewDatabase(rawdb.NewMemoryDatabase())
-	trie := NewEmpty(db)
-	trie.tracer = newTracer()
-
-	paths, blobs := trie.tracer.prevList()
-	if len(paths) != 0 || len(blobs) != 0 {
-		t.Fatalf("Nothing should be tracked")
-	}
-	// Insert a batch of entries, all the nodes should be marked as inserted
-	vals := []struct{ k, v string }{
-		{"do", "verb"},
-		{"ether", "wookiedoo"},
-		{"horse", "stallion"},
-		{"shaman", "horse"},
-		{"doge", "coin"},
-		{"dog", "puppy"},
-		{"somethingveryoddindeedthis is", "myothernodedata"},
-	}
-	for _, val := range vals {
-		trie.Update([]byte(val.k), []byte(val.v))
-	}
-	paths, blobs = trie.tracer.prevList()
-	if len(paths) != 0 || len(blobs) != 0 {
-		t.Fatalf("Nothing should be tracked")
-	}
-
-	// Commit the changes and re-create with new root
-	root, nodes := trie.Commit(false)
-	if err := db.Update(NewWithNodeSet(nodes)); err != nil {
-		t.Fatal(err)
-	}
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-	trie.resolveAndTrack(root.Bytes(), nil)
-
-	// Load all nodes in trie
-	for _, val := range vals {
-		trie.TryGet([]byte(val.k))
-	}
-
-	// Ensure all nodes are tracked by tracer with correct prev-values
-	iter := trie.NodeIterator(nil)
-	seen := make(map[string][]byte)
-	for iter.Next(true) {
-		// Embedded nodes are ignored since they are not present in
-		// database.
-		if iter.Hash() == (common.Hash{}) {
-			continue
-		}
-		seen[string(iter.Path())] = common.CopyBytes(iter.NodeBlob())
-	}
-
-	paths, blobs = trie.tracer.prevList()
-	if len(paths) != len(seen) || len(blobs) != len(seen) {
-		t.Fatalf("Unexpected tracked values")
-	}
-	for i, path := range paths {
-		blob := blobs[i]
-		prev, ok := seen[string(path)]
-		if !ok {
-			t.Fatalf("Missing node %v", path)
-		}
-		if !bytes.Equal(blob, prev) {
-			t.Fatalf("Unexpected value path: %v, want: %v, got: %v", path, prev, blob)
-		}
-	}
-
-	// Re-open the trie and iterate the trie, ensure nothing will be tracked.
-	// Iterator will not link any loaded nodes to trie.
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-
-	iter = trie.NodeIterator(nil)
-	for iter.Next(true) {
-	}
-	paths, blobs = trie.tracer.prevList()
-	if len(paths) != 0 || len(blobs) != 0 {
-		t.Fatalf("Nothing should be tracked")
-	}
-
-	// Re-open the trie and generate proof for entries, ensure nothing will
-	// be tracked. Prover will not link any loaded nodes to trie.
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-	for _, val := range vals {
-		trie.Prove([]byte(val.k), 0, rawdb.NewMemoryDatabase())
-	}
-	paths, blobs = trie.tracer.prevList()
-	if len(paths) != 0 || len(blobs) != 0 {
-		t.Fatalf("Nothing should be tracked")
-	}
-
-	// Delete entries from trie, ensure all previous values are correct.
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-	trie.resolveAndTrack(root.Bytes(), nil)
-
-	for _, val := range vals {
-		trie.TryDelete([]byte(val.k))
-	}
-	paths, blobs = trie.tracer.prevList()
-	if len(paths) != len(seen) || len(blobs) != len(seen) {
-		t.Fatalf("Unexpected tracked values")
-	}
-	for i, path := range paths {
-		blob := blobs[i]
-		prev, ok := seen[string(path)]
-		if !ok {
-			t.Fatalf("Missing node %v", path)
-		}
-		if !bytes.Equal(blob, prev) {
-			t.Fatalf("Unexpected value path: %v, want: %v, got: %v", path, prev, blob)
-		}
-	}
-}
-
-func TestDeleteAll(t *testing.T) {
-	db := NewDatabase(rawdb.NewMemoryDatabase())
-	trie := NewEmpty(db)
-	trie.tracer = newTracer()
-
-	// Insert a batch of entries, all the nodes should be marked as inserted
-	vals := []struct{ k, v string }{
-		{"do", "verb"},
-		{"ether", "wookiedoo"},
-		{"horse", "stallion"},
-		{"shaman", "horse"},
-		{"doge", "coin"},
-		{"dog", "puppy"},
-		{"somethingveryoddindeedthis is", "myothernodedata"},
-	}
-	for _, val := range vals {
-		trie.Update([]byte(val.k), []byte(val.v))
-	}
-	root, set := trie.Commit(false)
-	if err := db.Update(NewWithNodeSet(set)); err != nil {
-		t.Fatal(err)
-	}
-	// Delete entries from trie, ensure all values are detected
-	trie, _ = New(TrieID(root), db)
-	trie.tracer = newTracer()
-	trie.resolveAndTrack(root.Bytes(), nil)
-
-	// Iterate all existent nodes
-	var (
-		it    = trie.NodeIterator(nil)
-		nodes = make(map[string][]byte)
-	)
-	for it.Next(true) {
-		if it.Hash() != (common.Hash{}) {
-			nodes[string(it.Path())] = common.CopyBytes(it.NodeBlob())
-		}
-	}
-
-	// Perform deletion to purge the entire trie
-	for _, val := range vals {
-		trie.Delete([]byte(val.k))
-	}
-	root, set = trie.Commit(false)
-	if root != types.EmptyRootHash {
-		t.Fatalf("Invalid trie root %v", root)
-	}
-	for path, blob := range set.deletes {
-		prev, ok := nodes[path]
-		if !ok {
-			t.Fatalf("Extra node deleted %v", []byte(path))
-		}
-		if !bytes.Equal(prev, blob) {
-			t.Fatalf("Unexpected previous value %v", []byte(path))
-		}
-	}
-	if len(set.deletes) != len(nodes) {
-		t.Fatalf("Unexpected deletion set")
-	}
-}

trie/utils.go

@@ -1,199 +0,0 @@
-// Copyright 2022 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 trie
-
-// tracer tracks the changes of trie nodes. During the trie operations,
-// some nodes can be deleted from the trie, while these deleted nodes
-// won't be captured by trie.Hasher or trie.Committer. Thus, these deleted
-// nodes won't be removed from the disk at all. Tracer is an auxiliary tool
-// used to track all insert and delete operations of trie and capture all
-// deleted nodes eventually.
-//
-// The changed nodes can be mainly divided into two categories: the leaf
-// node and intermediate node. The former is inserted/deleted by callers
-// while the latter is inserted/deleted in order to follow the rule of trie.
-// This tool can track all of them no matter the node is embedded in its
-// parent or not, but valueNode is never tracked.
-//
-// Besides, it's also used for recording the original value of the nodes
-// when they are resolved from the disk. The pre-value of the nodes will
-// be used to construct reverse-diffs in the future.
-//
-// Note tracer is not thread-safe, callers should be responsible for handling
-// the concurrency issues by themselves.
-type tracer struct {
-	insert map[string]struct{}
-	delete map[string]struct{}
-	origin map[string][]byte
-}
-
-// newTracer initializes the tracer for capturing trie changes.
-func newTracer() *tracer {
-	return &tracer{
-		insert: make(map[string]struct{}),
-		delete: make(map[string]struct{}),
-		origin: make(map[string][]byte),
-	}
-}
-
-// onRead tracks the newly loaded trie node and caches the rlp-encoded blob internally.
-// Don't change the value outside of function since it's not deep-copied.
-func (t *tracer) onRead(path []byte, val []byte) {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return
-	}
-	t.origin[string(path)] = val
-}
-
-// onInsert tracks the newly inserted trie node. If it's already in the deletion set
-// (resurrected node), then just wipe it from the deletion set as the "untouched".
-func (t *tracer) onInsert(path []byte) {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return
-	}
-	if _, present := t.delete[string(path)]; present {
-		delete(t.delete, string(path))
-		return
-	}
-	t.insert[string(path)] = struct{}{}
-}
-
-// onDelete tracks the newly deleted trie node. If it's already
-// in the addition set, then just wipe it from the addition set
-// as it's untouched.
-func (t *tracer) onDelete(path []byte) {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return
-	}
-	if _, present := t.insert[string(path)]; present {
-		delete(t.insert, string(path))
-		return
-	}
-	t.delete[string(path)] = struct{}{}
-}
-
-// insertList returns the tracked inserted trie nodes in list format.
-func (t *tracer) insertList() [][]byte {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return nil
-	}
-	var ret [][]byte
-	for path := range t.insert {
-		ret = append(ret, []byte(path))
-	}
-	return ret
-}
-
-// deleteList returns the tracked deleted trie nodes in list format.
-func (t *tracer) deleteList() [][]byte {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return nil
-	}
-	var ret [][]byte
-	for path := range t.delete {
-		ret = append(ret, []byte(path))
-	}
-	return ret
-}
-
-// prevList returns the tracked node blobs in list format.
-func (t *tracer) prevList() ([][]byte, [][]byte) {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return nil, nil
-	}
-	var (
-		paths [][]byte
-		blobs [][]byte
-	)
-	for path, blob := range t.origin {
-		paths = append(paths, []byte(path))
-		blobs = append(blobs, blob)
-	}
-	return paths, blobs
-}
-
-// getPrev returns the cached original value of the specified node.
-func (t *tracer) getPrev(path []byte) []byte {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return nil
-	}
-	return t.origin[string(path)]
-}
-
-// reset clears the content tracked by tracer.
-func (t *tracer) reset() {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return
-	}
-	t.insert = make(map[string]struct{})
-	t.delete = make(map[string]struct{})
-	t.origin = make(map[string][]byte)
-}
-
-// copy returns a deep copied tracer instance.
-func (t *tracer) copy() *tracer {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return nil
-	}
-	var (
-		insert = make(map[string]struct{})
-		delete = make(map[string]struct{})
-		origin = make(map[string][]byte)
-	)
-	for key := range t.insert {
-		insert[key] = struct{}{}
-	}
-	for key := range t.delete {
-		delete[key] = struct{}{}
-	}
-	for key, val := range t.origin {
-		origin[key] = val
-	}
-	return &tracer{
-		insert: insert,
-		delete: delete,
-		origin: origin,
-	}
-}
-
-// markDeletions puts all tracked deletions into the provided nodeset.
-func (t *tracer) markDeletions(set *NodeSet) {
-	// Tracer isn't used right now, remove this check later.
-	if t == nil {
-		return
-	}
-	for _, path := range t.deleteList() {
-		// There are a few possibilities for this scenario(the node is deleted
-		// but not present in database previously), for example the node was
-		// embedded in the parent and now deleted from the trie. In this case
-		// it's noop from database's perspective.
-		val := t.getPrev(path)
-		if len(val) == 0 {
-			continue
-		}
-		set.markDeleted(path, val)
-	}
-}