[experiment] parallell trie hashing

trie/hasher.go

@@ -26,8 +26,8 @@ import (
 )
 
 type hasher struct {
-	tmp    sliceBuffer
-	sha    keccakState
+	tmp    []sliceBuffer
+	sha    []keccakState
 	onleaf LeafCallback
 }
 
@@ -54,8 +54,18 @@ func (b *sliceBuffer) Reset() {
 var hasherPool = sync.Pool{
 	New: func() interface{} {
 		return &hasher{
-			tmp: make(sliceBuffer, 0, 550), // cap is as large as a full fullNode.
-			sha: sha3.NewLegacyKeccak256().(keccakState),
+			tmp: []sliceBuffer{
+				make(sliceBuffer, 0, 550), // cap is as large as a full fullNode.
+				make(sliceBuffer, 0, 550), // cap is as large as a full fullNode.
+				make(sliceBuffer, 0, 550), // cap is as large as a full fullNode.
+				make(sliceBuffer, 0, 550), // cap is as large as a full fullNode.
+			},
+			sha: []keccakState{
+				sha3.NewLegacyKeccak256().(keccakState),
+				sha3.NewLegacyKeccak256().(keccakState),
+				sha3.NewLegacyKeccak256().(keccakState),
+				sha3.NewLegacyKeccak256().(keccakState),
+			},
 		}
 	},
 }
@@ -73,6 +83,9 @@ func returnHasherToPool(h *hasher) {
 // hash collapses a node down into a hash node, also returning a copy of the
 // original node initialized with the computed hash to replace the original one.
 func (h *hasher) hash(n node, db *Database, force bool) (node, node, error) {
+	return h.hashParalell(n, db, force, 0)
+}
+func (h *hasher) hashParalell(n node, db *Database, force bool, id int) (node, node, error) {
 	// If we're not storing the node, just hashing, use available cached data
 	if hash, dirty := n.cache(); hash != nil {
 		if db == nil {
@@ -88,11 +101,14 @@ func (h *hasher) hash(n node, db *Database, force bool) (node, node, error) {
 		}
 	}
 	// Trie not processed yet or needs storage, walk the children
-	collapsed, cached, err := h.hashChildren(n, db)
+	collapsed, cached, err := h.hashChildrenParalell(n, db, id)
 	if err != nil {
 		return hashNode{}, n, err
 	}
-	hashed, err := h.store(collapsed, db, force)
+	if id == -1 {
+		id = 0
+	}
+	hashed, err := h.store(collapsed, db, force, id)
 	if err != nil {
 		return hashNode{}, n, err
 	}
@@ -119,6 +135,10 @@ func (h *hasher) hash(n node, db *Database, force bool) (node, node, error) {
 // size of the child is larger than a hash, returning the collapsed node as well
 // as a replacement for the original node with the child hashes cached in.
 func (h *hasher) hashChildren(original node, db *Database) (node, node, error) {
+	return h.hashChildrenParalell(original, db, 0)
+}
+
+func (h *hasher) hashChildrenParalell(original node, db *Database, id int) (node, node, error) {
 	var err error
 
 	switch n := original.(type) {
@@ -129,7 +149,7 @@ func (h *hasher) hashChildren(original node, db *Database) (node, node, error) {
 		cached.Key = common.CopyBytes(n.Key)
 
 		if _, ok := n.Val.(valueNode); !ok {
-			collapsed.Val, cached.Val, err = h.hash(n.Val, db, false)
+			collapsed.Val, cached.Val, err = h.hashParalell(n.Val, db, false, id)
 			if err != nil {
 				return original, original, err
 			}
@@ -139,12 +159,74 @@ func (h *hasher) hashChildren(original node, db *Database) (node, node, error) {
 	case *fullNode:
 		// Hash the full node's children, caching the newly hashed subtrees
 		collapsed, cached := n.copy(), n.copy()
+		if id == -1 { // Top level, thread out
+			var wg sync.WaitGroup
+			wg.Add(3)
+			var e1, e2, e3, e4 error
+			go func() {
+				for i := 0; i < 4; i++ {
+					if n.Children[i] != nil {
+						collapsed.Children[i], cached.Children[i], e1 = h.hashParalell(n.Children[i], db, false, 0)
+						if err != nil {
+							return
+						}
+					}
+				}
+				wg.Done()
+			}()
+			go func() {
+				for i := 4; i < 8; i++ {
+					if n.Children[i] != nil {
+						collapsed.Children[i], cached.Children[i], e2 = h.hashParalell(n.Children[i], db, false, 1)
+						if err != nil {
+							return
+						}
+					}
+				}
+				wg.Done()
+			}()
+			go func() {
+				for i := 8; i < 12; i++ {
+					if n.Children[i] != nil {
+						collapsed.Children[i], cached.Children[i], e3 = h.hashParalell(n.Children[i], db, false, 2)
+						if err != nil {
+							return
+						}
+					}
+				}
+				wg.Done()
+			}()
+			for i := 12; i < 16; i++ {
+				if n.Children[i] != nil {
+					collapsed.Children[i], cached.Children[i], e4 = h.hashParalell(n.Children[i], db, false, 3)
+					if err != nil {
+						break
+					}
+				}
+			}
+			wg.Wait()
+			if e1 != nil {
+				return original, original, e1
+			}
+			if e2 != nil {
+				return original, original, e2
+			}
+
+			if e3 != nil {
+				return original, original, e3
+			}
+
+			if e4 != nil {
+				return original, original, e4
+			}
 
-		for i := 0; i < 16; i++ {
-			if n.Children[i] != nil {
-				collapsed.Children[i], cached.Children[i], err = h.hash(n.Children[i], db, false)
-				if err != nil {
-					return original, original, err
+		} else {
+			for i := 0; i < 16; i++ {
+				if n.Children[i] != nil {
+					collapsed.Children[i], cached.Children[i], err = h.hashParalell(n.Children[i], db, false, id)
+					if err != nil {
+						return original, original, err
+					}
 				}
 			}
 		}
@@ -160,31 +242,31 @@ func (h *hasher) hashChildren(original node, db *Database) (node, node, error) {
 // store hashes the node n and if we have a storage layer specified, it writes
 // the key/value pair to it and tracks any node->child references as well as any
 // node->external trie references.
-func (h *hasher) store(n node, db *Database, force bool) (node, error) {
+func (h *hasher) store(n node, db *Database, force bool, id int) (node, error) {
 	// Don't store hashes or empty nodes.
 	if _, isHash := n.(hashNode); n == nil || isHash {
 		return n, nil
 	}
-	// Generate the RLP encoding of the node
-	h.tmp.Reset()
-	if err := rlp.Encode(&h.tmp, n); err != nil {
-		panic("encode error: " + err.Error())
-	}
-	if len(h.tmp) < 32 && !force {
-		return n, nil // Nodes smaller than 32 bytes are stored inside their parent
-	}
-	// Larger nodes are replaced by their hash and stored in the database.
+	// We might already have the hash
 	hash, _ := n.cache()
 	if hash == nil {
-		hash = h.makeHashNode(h.tmp)
+		// Generate the RLP encoding of the node
+		h.tmp[id].Reset()
+		if err := rlp.Encode(&h.tmp[id], n); err != nil {
+			panic("encode error: " + err.Error())
+		}
+		if len(h.tmp[id]) < 32 && !force {
+			return n, nil // Nodes smaller than 32 bytes are stored inside their parent
+		}
+		// Larger nodes are replaced by their hash and stored in the database.
+		hash = h.makeHashNode(id)
 	}
-
 	if db != nil {
 		// We are pooling the trie nodes into an intermediate memory cache
 		hash := common.BytesToHash(hash)
 
 		db.lock.Lock()
-		db.insert(hash, h.tmp, n)
+		db.insert(hash, h.tmp[id], n)
 		db.lock.Unlock()
 
 		// Track external references from account->storage trie
@@ -206,10 +288,10 @@ func (h *hasher) store(n node, db *Database, force bool) (node, error) {
 	return hash, nil
 }
 
-func (h *hasher) makeHashNode(data []byte) hashNode {
-	n := make(hashNode, h.sha.Size())
-	h.sha.Reset()
-	h.sha.Write(data)
-	h.sha.Read(n)
+func (h *hasher) makeHashNode(id int) hashNode {
+	n := make(hashNode, h.sha[id].Size())
+	h.sha[id].Reset()
+	h.sha[id].Write(h.tmp[id])
+	h.sha[id].Read(n)
 	return n
 }

trie/iterator.go

@@ -190,7 +190,7 @@ func (it *nodeIterator) LeafProof() [][]byte {
 			for i, item := range it.stack[:len(it.stack)-1] {
 				// Gather nodes that end up as hash nodes (or the root)
 				node, _, _ := hasher.hashChildren(item.node, nil)
-				hashed, _ := hasher.store(node, nil, false)
+				hashed, _ := hasher.store(node, nil, false,0)
 				if _, ok := hashed.(hashNode); ok || i == 0 {
 					enc, _ := rlp.EncodeToBytes(node)
 					proofs = append(proofs, enc)

trie/proof.go

@@ -71,7 +71,7 @@ func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.KeyValueWriter) e
 		// Don't bother checking for errors here since hasher panics
 		// if encoding doesn't work and we're not writing to any database.
 		n, _, _ = hasher.hashChildren(n, nil)
-		hn, _ := hasher.store(n, nil, false)
+		hn, _ := hasher.store(n, nil, false, 0)
 		if hash, ok := hn.(hashNode); ok || i == 0 {
 			// If the node's database encoding is a hash (or is the
 			// root node), it becomes a proof element.
@@ -80,7 +80,7 @@ func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.KeyValueWriter) e
 			} else {
 				enc, _ := rlp.EncodeToBytes(n)
 				if !ok {
-					hash = hasher.makeHashNode(enc)
+					hash = hasher.makeHashNode(0)
 				}
 				proofDb.Put(hash, enc)
 			}

trie/secure_trie.go

@@ -177,9 +177,9 @@ func (t *SecureTrie) NodeIterator(start []byte) NodeIterator {
 // invalid on the next call to hashKey or secKey.
 func (t *SecureTrie) hashKey(key []byte) []byte {
 	h := newHasher(nil)
-	h.sha.Reset()
-	h.sha.Write(key)
-	buf := h.sha.Sum(t.hashKeyBuf[:0])
+	h.sha[0].Reset()
+	h.sha[0].Write(key)
+	buf := h.sha[0].Sum(t.hashKeyBuf[:0])
 	returnHasherToPool(h)
 	return buf
 }

trie/trie.go

@@ -429,5 +429,5 @@ func (t *Trie) hashRoot(db *Database, onleaf LeafCallback) (node, node, error) {
 	}
 	h := newHasher(onleaf)
 	defer returnHasherToPool(h)
-	return h.hash(t.root, db, true)
+	return h.hashParalell(t.root, db, true, -1)
 }

trie/trie_test.go

@@ -512,6 +512,72 @@ func BenchmarkHash(b *testing.B) {
 	trie.Hash()
 }
 
+// Benchmarks the trie Commit following a Hash. Since the trie caches the result of any operation,
+// we cannot use b.N as the number of hashing rouns, since all rounds apart from
+// the first one will be NOOP. As such, we'll use b.N as the number of account to
+// insert into the trie before measuring the hashing.
+func BenchmarkCommitAfterHash(b *testing.B) {
+	// Make the random benchmark deterministic
+	random := rand.New(rand.NewSource(0))
+
+	// Create a realistic account trie to hash
+	addresses := make([][20]byte, b.N)
+	for i := 0; i < len(addresses); i++ {
+		for j := 0; j < len(addresses[i]); j++ {
+			addresses[i][j] = byte(random.Intn(256))
+		}
+	}
+	accounts := make([][]byte, len(addresses))
+	for i := 0; i < len(accounts); i++ {
+		var (
+			nonce   = uint64(random.Int63())
+			balance = new(big.Int).Rand(random, new(big.Int).Exp(common.Big2, common.Big256, nil))
+			root    = emptyRoot
+			code    = crypto.Keccak256(nil)
+		)
+		accounts[i], _ = rlp.EncodeToBytes([]interface{}{nonce, balance, root, code})
+	}
+	// Insert the accounts into the trie and hash it
+	trie := newEmpty()
+	for i := 0; i < len(addresses); i++ {
+		trie.Update(crypto.Keccak256(addresses[i][:]), accounts[i])
+	}
+	trie.Hash()
+	b.ResetTimer()
+	b.ReportAllocs()
+	trie.Commit(nil)
+}
+
+func TestCommitAfterHash(t *testing.T) {
+	// Make the random benchmark deterministic
+	random := rand.New(rand.NewSource(0))
+
+	// Create a realistic account trie to hash
+	addresses := make([][20]byte, 10000)
+	for i := 0; i < len(addresses); i++ {
+		for j := 0; j < len(addresses[i]); j++ {
+			addresses[i][j] = byte(random.Intn(256))
+		}
+	}
+	accounts := make([][]byte, len(addresses))
+	for i := 0; i < len(accounts); i++ {
+		var (
+			nonce   = uint64(random.Int63())
+			balance = new(big.Int).Rand(random, new(big.Int).Exp(common.Big2, common.Big256, nil))
+			root    = emptyRoot
+			code    = crypto.Keccak256(nil)
+		)
+		accounts[i], _ = rlp.EncodeToBytes([]interface{}{nonce, balance, root, code})
+	}
+	// Insert the accounts into the trie and hash it
+	trie := newEmpty()
+	for i := 0; i < len(addresses); i++ {
+		trie.Update(crypto.Keccak256(addresses[i][:]), accounts[i])
+	}
+	trie.Hash()
+	trie.Commit(nil)
+}
+
 func tempDB() (string, *Database) {
 	dir, err := ioutil.TempDir("", "trie-bench")
 	if err != nil {