Convert compact.NodeID to Suffix directly

storage/cache/log_tile.go

@@ -15,6 +15,7 @@
 package cache
 
 import (
+	"encoding/binary"
 	"fmt"
 
 	"github.com/google/trillian/merkle/compact"
@@ -61,28 +62,21 @@ func PopulateLogTile(st *storagepb.SubtreeProto, hasher hashers.LogHasher) error
 		// Don't put leaves into the internal map and only update if we're rebuilding internal
 		// nodes. If the subtree was saved with internal nodes then we don't touch the map.
 		if id.Level > 0 && len(st.Leaves) == maxLeaves {
-			subDepth := logStrataDepth - int(id.Level)
-			// TODO(Martin2112): See if we can possibly avoid the expense hiding inside NewNodeIDFromPrefix.
-			nodeID := tree.NewNodeIDFromPrefix(st.Prefix, subDepth, int64(id.Index), logStrataDepth, maxLogDepth)
-			sfx := nodeID.Suffix(len(st.Prefix), int(st.Depth))
-			sfxKey := sfx.String()
-			st.InternalNodes[sfxKey] = hash
+			st.InternalNodes[toSuffix(id)] = hash
 		}
 	}
 
 	fact := compact.RangeFactory{Hash: hasher.HashChildren}
 	cr := fact.NewEmptyRange(0)
 
 	// We need to update the subtree root hash regardless of whether it's fully populated
-	for leafIndex := int64(0); leafIndex < int64(len(st.Leaves)); leafIndex++ {
-		nodeID := tree.NewNodeIDFromPrefix(st.Prefix, logStrataDepth, leafIndex, logStrataDepth, maxLogDepth)
-		sfx := nodeID.Suffix(len(st.Prefix), int(st.Depth))
-		sfxKey := sfx.String()
+	for leafIndex := uint64(0); leafIndex < uint64(len(st.Leaves)); leafIndex++ {
+		sfxKey := toSuffix(compact.NewNodeID(0, leafIndex))
 		h := st.Leaves[sfxKey]
 		if h == nil {
-			return fmt.Errorf("unexpectedly got nil for subtree leaf suffix %s", sfx)
+			return fmt.Errorf("unexpectedly got nil for subtree leaf suffix %s", sfxKey)
 		}
-		if size, expected := int64(cr.End()), leafIndex; size != expected {
+		if size, expected := cr.End(), leafIndex; size != expected {
 			return fmt.Errorf("got size of %d, but expected %d", size, expected)
 		}
 		if err := cr.Append(h, store); err != nil {
@@ -135,3 +129,10 @@ func prepareLogTile(st *storagepb.SubtreeProto) error {
 	}
 	return nil
 }
+
+func toSuffix(id compact.NodeID) string {
+	depth := logStrataDepth - int(id.Level)
+	var index [8]byte
+	binary.BigEndian.PutUint64(index[:], id.Index<<(maxLogDepth-depth))
+	return tree.NewSuffix(uint8(depth), index[:]).String()
+}

storage/cache/subtree_cache_test.go

@@ -241,9 +241,7 @@ func TestRepopulateLogSubtree(t *testing.T) {
 			t.Fatalf("merkle tree update failed: %v", err)
 		}
 
-		nodeID := tree.NewNodeIDFromPrefix(s.Prefix, logStrataDepth, numLeaves-1, logStrataDepth, maxLogDepth)
-		_, sfx := nodeID.Split(len(s.Prefix), int(s.Depth))
-		sfxKey := sfx.String()
+		sfxKey := toSuffix(compact.NewNodeID(0, uint64(numLeaves)-1))
 		s.Leaves[sfxKey] = leafHash
 		if numLeaves == 1<<uint(defaultLogStrata[0]) {
 			s.InternalNodeCount = uint32(len(cmtStorage.InternalNodes))
@@ -285,9 +283,7 @@ func BenchmarkRepopulateLogSubtree(b *testing.B) {
 	for i := 0; i < 256; i++ {
 		leaf := []byte(fmt.Sprintf("leaf %d", i))
 		hash := hasher.HashLeaf(leaf)
-		nodeID := tree.NewNodeIDFromPrefix(s.Prefix, logStrataDepth, int64(i), logStrataDepth, maxLogDepth)
-		_, sfx := nodeID.Split(len(s.Prefix), int(s.Depth))
-		s.Leaves[sfx.String()] = hash
+		s.Leaves[toSuffix(compact.NewNodeID(0, uint64(i)))] = hash
 	}
 
 	for n := 0; n < b.N; n++ {

storage/tree/suffix_test.go

@@ -74,19 +74,21 @@ func TestParseSuffix(t *testing.T) {
 
 func TestSplitParseSuffixRoundtrip(t *testing.T) {
 	for _, tc := range []struct {
-		prefix    []byte
-		leafIndex int64
-		wantPath  []byte
+		prefix   []byte
+		index    int64
+		level    int
+		wantPath []byte
 	}{
 		// Because we're using logStrataDepth below we'll always get a one byte
 		// suffix path.
-		{h2b(""), 1, h2b("01")},
-		{h2b("00"), 1, h2b("01")},
-		{h2b("abcd"), 99, h2b("63")},
-		{h2b("98765432"), 27, h2b("1b")},
-		{h2b("12345678"), 253, h2b("fd")},
+		{prefix: h2b(""), index: 1, wantPath: h2b("01")},
+		{prefix: h2b("00"), index: 1, wantPath: h2b("01")},
+		{prefix: h2b("00"), level: 4, index: 10, wantPath: h2b("a0")},
+		{prefix: h2b("abcd"), index: 99, wantPath: h2b("63")},
+		{prefix: h2b("98765432"), index: 27, wantPath: h2b("1b")},
+		{prefix: h2b("12345678"), index: 253, wantPath: h2b("fd")},
 	} {
-		nodeID := NewNodeIDFromPrefix(tc.prefix, logStrataDepth, tc.leafIndex, logStrataDepth, maxLogDepth)
+		nodeID := NewNodeIDFromPrefix(tc.prefix, logStrataDepth-tc.level, tc.index, logStrataDepth, maxLogDepth)
 		sfx := nodeID.Suffix(len(tc.prefix), logStrataDepth)
 		sfxKey := sfx.String()