trie, triedb: remove unnecessary child resolver interface (ethereum#3…

…0167)

trie/committer.go

@@ -154,12 +154,8 @@ func (c *committer) store(path []byte, n node) node {
 	return hash
 }
 
-// MerkleResolver the children resolver in merkle-patricia-tree.
-type MerkleResolver struct{}
-
-// ForEach implements childResolver, decodes the provided node and
-// traverses the children inside.
-func (resolver MerkleResolver) ForEach(node []byte, onChild func(common.Hash)) {
+// ForGatherChildren decodes the provided node and traverses the children inside.
+func ForGatherChildren(node []byte, onChild func(common.Hash)) {
 	forGatherChildren(mustDecodeNodeUnsafe(nil, node), onChild)
 }
 

triedb/database.go

@@ -23,7 +23,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
-	"github.com/ethereum/go-ethereum/trie"
 	"github.com/ethereum/go-ethereum/trie/trienode"
 	"github.com/ethereum/go-ethereum/trie/triestate"
 	"github.com/ethereum/go-ethereum/triedb/database"
@@ -112,14 +111,7 @@ func NewDatabase(diskdb ethdb.Database, config *Config) *Database {
 	if config.PathDB != nil {
 		db.backend = pathdb.New(diskdb, config.PathDB, config.IsVerkle)
 	} else {
-		var resolver hashdb.ChildResolver
-		if config.IsVerkle {
-			// TODO define verkle resolver
-			log.Crit("verkle does not use a hash db")
-		} else {
-			resolver = trie.MerkleResolver{}
-		}
-		db.backend = hashdb.New(diskdb, config.HashDB, resolver)
+		db.backend = hashdb.New(diskdb, config.HashDB)
 	}
 	return db
 }

triedb/hashdb/database.go

@@ -31,6 +31,7 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
 	"github.com/ethereum/go-ethereum/trie/trienode"
 	"github.com/ethereum/go-ethereum/trie/triestate"
 	"github.com/ethereum/go-ethereum/triedb/database"
@@ -60,12 +61,6 @@ var (
 	memcacheCommitBytesMeter = metrics.NewRegisteredMeter("hashdb/memcache/commit/bytes", nil)
 )
 
-// ChildResolver defines the required method to decode the provided
-// trie node and iterate the children on top.
-type ChildResolver interface {
-	ForEach(node []byte, onChild func(common.Hash))
-}
-
 // Config contains the settings for database.
 type Config struct {
 	CleanCacheSize int // Maximum memory allowance (in bytes) for caching clean nodes
@@ -84,9 +79,7 @@ var Defaults = &Config{
 // the disk database. The aim is to accumulate trie writes in-memory and only
 // periodically flush a couple tries to disk, garbage collecting the remainder.
 type Database struct {
-	diskdb   ethdb.Database // Persistent storage for matured trie nodes
-	resolver ChildResolver  // The handler to resolve children of nodes
-
+	diskdb  ethdb.Database              // Persistent storage for matured trie nodes
 	cleans  *fastcache.Cache            // GC friendly memory cache of clean node RLPs
 	dirties map[common.Hash]*cachedNode // Data and references relationships of dirty trie nodes
 	oldest  common.Hash                 // Oldest tracked node, flush-list head
@@ -124,15 +117,15 @@ var cachedNodeSize = int(reflect.TypeOf(cachedNode{}).Size())
 // forChildren invokes the callback for all the tracked children of this node,
 // both the implicit ones from inside the node as well as the explicit ones
 // from outside the node.
-func (n *cachedNode) forChildren(resolver ChildResolver, onChild func(hash common.Hash)) {
+func (n *cachedNode) forChildren(onChild func(hash common.Hash)) {
 	for child := range n.external {
 		onChild(child)
 	}
-	resolver.ForEach(n.node, onChild)
+	trie.ForGatherChildren(n.node, onChild)
 }
 
 // New initializes the hash-based node database.
-func New(diskdb ethdb.Database, config *Config, resolver ChildResolver) *Database {
+func New(diskdb ethdb.Database, config *Config) *Database {
 	if config == nil {
 		config = Defaults
 	}
@@ -141,10 +134,9 @@ func New(diskdb ethdb.Database, config *Config, resolver ChildResolver) *Databas
 		cleans = fastcache.New(config.CleanCacheSize)
 	}
 	return &Database{
-		diskdb:   diskdb,
-		resolver: resolver,
-		cleans:   cleans,
-		dirties:  make(map[common.Hash]*cachedNode),
+		diskdb:  diskdb,
+		cleans:  cleans,
+		dirties: make(map[common.Hash]*cachedNode),
 	}
 }
 
@@ -163,7 +155,7 @@ func (db *Database) insert(hash common.Hash, node []byte) {
 		node:      node,
 		flushPrev: db.newest,
 	}
-	entry.forChildren(db.resolver, func(child common.Hash) {
+	entry.forChildren(func(child common.Hash) {
 		if c := db.dirties[child]; c != nil {
 			c.parents++
 		}
@@ -316,7 +308,7 @@ func (db *Database) dereference(hash common.Hash) {
 			db.dirties[node.flushNext].flushPrev = node.flushPrev
 		}
 		// Dereference all children and delete the node
-		node.forChildren(db.resolver, func(child common.Hash) {
+		node.forChildren(func(child common.Hash) {
 			db.dereference(child)
 		})
 		delete(db.dirties, hash)
@@ -465,7 +457,7 @@ func (db *Database) commit(hash common.Hash, batch ethdb.Batch, uncacher *cleane
 	var err error
 
 	// Dereference all children and delete the node
-	node.forChildren(db.resolver, func(child common.Hash) {
+	node.forChildren(func(child common.Hash) {
 		if err == nil {
 			err = db.commit(child, batch, uncacher)
 		}