trie: make commit use channel for insert + leaf callbacks

tests/testdata

@@ -1 +1 @@
-Subproject commit b5eb9900ee2147b40d3e681fe86efa4fd693959a
+Subproject commit 25f480521dae1937841bbcb034e862c4dfd53256

trie/hasher.go

@@ -25,10 +25,17 @@ import (
 	"golang.org/x/crypto/sha3"
 )
 
+type Leaf struct {
+	size int
+	hash common.Hash
+	node node
+}
+
 type hasher struct {
 	tmp    sliceBuffer
 	sha    keccakState
 	onleaf LeafCallback
+	leafCh chan *Leaf
 }
 
 // keccakState wraps sha3.state. In addition to the usual hash methods, it also supports
@@ -178,16 +185,37 @@ func (h *hasher) store(n node, db *Database, force bool) (node, error) {
 	if hash == nil {
 		hash = h.makeHashNode(h.tmp)
 	}
-
 	if db != nil {
+		h.leafCh <- &Leaf{
+			size: len(h.tmp),
+			hash: common.BytesToHash(hash),
+			node: n,
+		}
+	}
+	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)
+	return n
+}
+
+// commitLoop does the actual insert + leaf callback for nodes
+func (h *hasher) commitLoop(db *Database, wg *sync.WaitGroup) {
+	defer wg.Done()
+	for item := range h.leafCh {
+		var (
+			hash = item.hash
+			size = item.size
+			n    = item.node
+		)
 		// We are pooling the trie nodes into an intermediate memory cache
-		hash := common.BytesToHash(hash)
-
 		db.lock.Lock()
-		db.insert(hash, len(h.tmp), n)
+		db.insert(hash, size, n)
 		db.lock.Unlock()
-
-		// Track external references from account->storage trie
 		if h.onleaf != nil {
 			switch n := n.(type) {
 			case *shortNode:
@@ -203,13 +231,4 @@ 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)
-	return n
 }

trie/trie.go

@@ -20,6 +20,7 @@ package trie
 import (
 	"bytes"
 	"fmt"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -415,7 +416,18 @@ func (t *Trie) Commit(onleaf LeafCallback) (root common.Hash, err error) {
 	if t.db == nil {
 		panic("commit called on trie with nil database")
 	}
-	hash, cached, err := t.hashRoot(t.db, onleaf)
+	if t.root == nil {
+		return emptyRoot, nil
+	}
+	h := newHasher(onleaf)
+	h.leafCh = make(chan *Leaf, 200) // arbitrary number
+	defer returnHasherToPool(h)
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go h.commitLoop(t.db, &wg)
+	hash, cached, err :=  h.hash(t.root, t.db, true)
+	close(h.leafCh)
+	wg.Wait()
 	if err != nil {
 		return common.Hash{}, err
 	}
@@ -431,3 +443,4 @@ func (t *Trie) hashRoot(db *Database, onleaf LeafCallback) (node, node, error) {
 	defer returnHasherToPool(h)
 	return h.hash(t.root, db, true)
 }
+