trie: polish

trie/hasher.go

@@ -65,9 +65,11 @@ func (h *hasher) hash(n node, force bool) []byte {
 	case *shortNode:
 		enc := h.encodeShortNode(n)
 		if len(enc) < 32 && !force {
+			// Nodes smaller than 32 bytes are embedded directly in their parent.
+			// In such cases, return the raw encoded blob instead of the node hash.
 			buf := make([]byte, len(enc))
 			copy(buf, enc)
-			return buf // Nodes smaller than 32 bytes are stored inside their parent
+			return buf
 		}
 		hash := h.hashData(enc)
 		n.flags.hash = hash
@@ -76,9 +78,11 @@ func (h *hasher) hash(n node, force bool) []byte {
 	case *fullNode:
 		enc := h.encodeFullNode(n)
 		if len(enc) < 32 && !force {
+			// Nodes smaller than 32 bytes are embedded directly in their parent.
+			// In such cases, return the raw encoded blob instead of the node hash.
 			buf := make([]byte, len(enc))
 			copy(buf, enc)
-			return buf // Nodes smaller than 32 bytes are stored inside their parent
+			return buf
 		}
 		hash := h.hashData(enc)
 		n.flags.hash = hash
@@ -110,6 +114,8 @@ func (h *hasher) encodeShortNode(n *shortNode) []byte {
 	return h.encodedBytes()
 }
 
+// fnEncoderPool is the pool for storing shared fullNode encoder to mitigate
+// the significant memory allocation overhead.
 var fnEncoderPool = sync.Pool{
 	New: func() interface{} {
 		var enc fullnodeEncoder
@@ -189,10 +195,7 @@ func (h *hasher) hashDataTo(dst, data []byte) {
 	h.sha.Read(dst)
 }
 
-// proofHash is used to construct trie proofs, and returns the 'collapsed'
+// proofHash is used to construct trie proofs, returning the rlp-encoded node blobs.
-// node (for later RLP encoding) as well as the hashed node -- unless the
-// node is smaller than 32 bytes, in which case it will be returned as is.
-// This method does not do anything on value- or hash-nodes.
 func (h *hasher) proofHash(original node) []byte {
 	switch n := original.(type) {
 	case *shortNode:

trie/iterator.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"container/heap"
 	"errors"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 )

trie/node_enc.go

@@ -46,14 +46,11 @@ func (n *fullnodeEncoder) encode(w rlp.EncoderBuffer) {
 		if len(c) == 0 {
 			w.Write(rlp.EmptyString)
 		} else {
-			if i == 16 {
+			// valueNode or hashNode
-				w.WriteBytes(c) // valueNode
+			if i == 16 || len(c) >= 32 {
+				w.WriteBytes(c)
 			} else {
-				if len(c) < 32 {
 				w.Write(c) // rawNode
-				} else {
-					w.WriteBytes(c) // hashNode
-				}
 			}
 		}
 	}
@@ -84,7 +81,7 @@ func (n *extNodeEncoder) encode(w rlp.EncoderBuffer) {
 	w.WriteBytes(n.Key)
 
 	if n.Val == nil {
-		w.Write(rlp.EmptyString)
+		w.Write(rlp.EmptyString) // theoretically impossible to happen
 	} else if len(n.Val) < 32 {
 		w.Write(n.Val) // rawNode
 	} else {

trie/proof.go

@@ -87,9 +87,6 @@ func (t *Trie) Prove(key []byte, proofDb ethdb.KeyValueWriter) error {
 
 	for i, n := range nodes {
 		enc := hasher.proofHash(n)
-		if len(enc) == 32 {
-			fmt.Println("DEBUG")
-		}
 		if len(enc) >= 32 || i == 0 {
 			proofDb.Put(crypto.Keccak256(enc), enc)
 		}