1 files changed, 154 insertions, 0 deletions
diff --git a/core/state/database.go b/core/state/database.go
new file mode 100644
index 000000000..946625e76
--- /dev/null
+++ b/core/state/database.go
@@ -0,0 +1,154 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package state
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/trie"
+	lru "github.com/hashicorp/golang-lru"
+)
+
+// Trie cache generation limit after which to evic trie nodes from memory.
+var MaxTrieCacheGen = uint16(120)
+
+const (
+	// Number of past tries to keep. This value is chosen such that
+	// reasonable chain reorg depths will hit an existing trie.
+	maxPastTries = 12
+
+	// Number of codehash->size associations to keep.
+	codeSizeCacheSize = 100000
+)
+
+// Database wraps access to tries and contract code.
+type Database interface {
+	// Accessing tries:
+	// OpenTrie opens the main account trie.
+	// OpenStorageTrie opens the storage trie of an account.
+	OpenTrie(root common.Hash) (Trie, error)
+	OpenStorageTrie(addrHash, root common.Hash) (Trie, error)
+	// Accessing contract code:
+	ContractCode(addrHash, codeHash common.Hash) ([]byte, error)
+	ContractCodeSize(addrHash, codeHash common.Hash) (int, error)
+	// CopyTrie returns an independent copy of the given trie.
+	CopyTrie(Trie) Trie
+}
+
+// Trie is a Ethereum Merkle Trie.
+type Trie interface {
+	TryGet(key []byte) ([]byte, error)
+	TryUpdate(key, value []byte) error
+	TryDelete(key []byte) error
+	CommitTo(trie.DatabaseWriter) (common.Hash, error)
+	Hash() common.Hash
+	NodeIterator(startKey []byte) trie.NodeIterator
+	GetKey([]byte) []byte // TODO(fjl): remove this when SecureTrie is removed
+}
+
+// NewDatabase creates a backing store for state. The returned database is safe for
+// concurrent use and retains cached trie nodes in memory.
+func NewDatabase(db ethdb.Database) Database {
+	csc, _ := lru.New(codeSizeCacheSize)
+	return &cachingDB{db: db, codeSizeCache: csc}
+}
+
+type cachingDB struct {
+	db            ethdb.Database
+	mu            sync.Mutex
+	pastTries     []*trie.SecureTrie
+	codeSizeCache *lru.Cache
+}
+
+func (db *cachingDB) OpenTrie(root common.Hash) (Trie, error) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+
+	for i := len(db.pastTries) - 1; i >= 0; i-- {
+		if db.pastTries[i].Hash() == root {
+			return cachedTrie{db.pastTries[i].Copy(), db}, nil
+		}
+	}
+	tr, err := trie.NewSecure(root, db.db, MaxTrieCacheGen)
+	if err != nil {
+		return nil, err
+	}
+	return cachedTrie{tr, db}, nil
+}
+
+func (db *cachingDB) pushTrie(t *trie.SecureTrie) {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+
+	if len(db.pastTries) >= maxPastTries {
+		copy(db.pastTries, db.pastTries[1:])
+		db.pastTries[len(db.pastTries)-1] = t
+	} else {
+		db.pastTries = append(db.pastTries, t)
+	}
+}
+
+func (db *cachingDB) OpenStorageTrie(addrHash, root common.Hash) (Trie, error) {
+	return trie.NewSecure(root, db.db, 0)
+}
+
+func (db *cachingDB) CopyTrie(t Trie) Trie {
+	switch t := t.(type) {
+	case cachedTrie:
+		return cachedTrie{t.SecureTrie.Copy(), db}
+	case *trie.SecureTrie:
+		return t.Copy()
+	default:
+		panic(fmt.Errorf("unknown trie type %T", t))
+	}
+}
+
+func (db *cachingDB) ContractCode(addrHash, codeHash common.Hash) ([]byte, error) {
+	code, err := db.db.Get(codeHash[:])
+	if err == nil {
+		db.codeSizeCache.Add(codeHash, len(code))
+	}
+	return code, err
+}
+
+func (db *cachingDB) ContractCodeSize(addrHash, codeHash common.Hash) (int, error) {
+	if cached, ok := db.codeSizeCache.Get(codeHash); ok {
+		return cached.(int), nil
+	}
+	code, err := db.ContractCode(addrHash, codeHash)
+	if err == nil {
+		db.codeSizeCache.Add(codeHash, len(code))
+	}
+	return len(code), err
+}
+
+// cachedTrie inserts its trie into a cachingDB on commit.
+type cachedTrie struct {
+	*trie.SecureTrie
+	db *cachingDB
+}
+
+func (m cachedTrie) CommitTo(dbw trie.DatabaseWriter) (common.Hash, error) {
+	root, err := m.SecureTrie.CommitTo(dbw)
+	if err == nil {
+		m.db.pushTrie(m.SecureTrie)
+	}
+	return root, err
+}