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ledger/complete/mtrie/forest.go

@@ -190,10 +190,11 @@ func (f *Forest) Read(r *ledger.TrieRead) ([]ledger.Value, error) {
 	return orderedValues, nil
 }
 
-// Update updates the Values for the registers, adds updated tries to forest,
-// and returns rootHash and error (if any).
+// Update creates a new trie by updating Values for registers in the parent trie,
+// adds new trie to forest, and returns rootHash and error (if any).
 // In case there are multiple updates to the same register, Update will persist
 // the latest written value.
+// Note: Update adds new trie to forest, unlike NewTrie().
 func (f *Forest) Update(u *ledger.TrieUpdate) (ledger.RootHash, error) {
 	t, err := f.NewTrie(u)
 	if err != nil {
@@ -208,9 +209,11 @@ func (f *Forest) Update(u *ledger.TrieUpdate) (ledger.RootHash, error) {
 	return t.RootHash(), nil
 }
 
-// NewTrie updates the Values for the registers and returns updated trie and error (if any).
-// In case there are multiple updates to the same register, Update will persist the latest
-// written value.
+// NewTrie creates a new trie by updating Values for registers in the parent trie,
+// and returns new trie and error (if any).
+// In case there are multiple updates to the same register, NewTrie will persist
+// the latest written value.
+// Note: NewTrie doesn't add new trie to forest, unlike Update().
 func (f *Forest) NewTrie(u *ledger.TrieUpdate) (*trie.MTrie, error) {
 
 	parentTrie, err := f.GetTrie(u.RootHash)

ledger/complete/mtrie/forest_test.go

@@ -1041,3 +1041,34 @@ func TestValueSizesWithDuplicatedKeys(t *testing.T) {
 		require.Equal(t, expectedValueSizes[i], retValueSizes[i])
 	}
 }
+
+func TestNow(t *testing.T) {
+
+	metricsCollector := &metrics.NoopCollector{}
+	forest, err := NewForest(5, metricsCollector, nil)
+	require.NoError(t, err)
+	rootHash := forest.GetEmptyRootHash()
+
+	p1 := pathByUint8s([]uint8{uint8(53), uint8(74)})
+	v1 := payloadBySlices([]byte{'A'}, []byte{'A'})
+
+	paths := []ledger.Path{p1}
+	payloads := []*ledger.Payload{v1}
+	update := &ledger.TrieUpdate{RootHash: rootHash, Paths: paths, Payloads: payloads}
+	updatedRoot, err := forest.Update(update)
+	size := forest.Size()
+	require.NoError(t, err)
+	require.Equal(t, 2, size)
+
+	read := &ledger.TrieRead{RootHash: updatedRoot, Paths: paths}
+	retValues, err := forest.Read(read)
+	require.NoError(t, err)
+	require.Equal(t, retValues[0], payloads[0].Value)
+
+	update = &ledger.TrieUpdate{RootHash: updatedRoot, Paths: nil, Payloads: nil}
+	updatedRoot2, err := forest.Update(update)
+	size = forest.Size()
+	require.NoError(t, err)
+	require.Equal(t, updatedRoot, updatedRoot2)
+	require.Equal(t, 2, size)
+}