trie: added error handling

Created alternate versions of Trie and SecureTrie functions that can return a MissingNodeError (used by ODR services)

trie/arc.go

@@ -62,6 +62,18 @@ func newARC(c int) *arc {
 	}
 }
 
+// Clear clears the cache
+func (a *arc) Clear() {
+	a.mutex.Lock()
+	defer a.mutex.Unlock()
+	a.p = 0
+	a.t1 = list.New()
+	a.b1 = list.New()
+	a.t2 = list.New()
+	a.b2 = list.New()
+	a.cache = make(map[string]*entry, a.c)
+}
+
 // Put inserts a new key-value pair into the cache.
 // This optimizes future access to this entry (side effect).
 func (a *arc) Put(key hashNode, value node) bool {

trie/errors.go

@@ -0,0 +1,41 @@
+// Copyright 2014 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 trie
+
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// MissingNodeError is returned by the trie functions (TryGet, TryUpdate, TryDelete)
+// in the case where a trie node is not present in the local database. Contains
+// information necessary for retrieving the missing node through an ODR service.
+//
+// NodeHash is the hash of the missing node
+// RootHash is the original root of the trie that contains the node
+// KeyPrefix is the prefix that leads from the root to the missing node (hex encoded)
+// KeySuffix (optional) contains the rest of the key we were looking for, gives a
+//  hint on which further nodes should also be retrieved (hex encoded)
+type MissingNodeError struct {
+	RootHash, NodeHash   common.Hash
+	KeyPrefix, KeySuffix []byte
+}
+
+func (err *MissingNodeError) Error() string {
+	return fmt.Sprintf("Missing trie node %064x", err.NodeHash)
+}

trie/iterator.go

@@ -16,7 +16,12 @@
 
 package trie
 
-import "bytes"
+import (
+	"bytes"
+
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
 
 type Iterator struct {
 	trie *Trie
@@ -100,7 +105,11 @@ func (self *Iterator) next(node interface{}, key []byte, isIterStart bool) []byt
 		}
 
 	case hashNode:
-		return self.next(self.trie.resolveHash(node), key, isIterStart)
+		rn, err := self.trie.resolveHash(node, nil, nil)
+		if err != nil && glog.V(logger.Error) {
+			glog.Errorf("Unhandled trie error: %v", err)
+		}
+		return self.next(rn, key, isIterStart)
 	}
 	return nil
 }
@@ -127,7 +136,11 @@ func (self *Iterator) key(node interface{}) []byte {
 			}
 		}
 	case hashNode:
-		return self.key(self.trie.resolveHash(node))
+		rn, err := self.trie.resolveHash(node, nil, nil)
+		if err != nil && glog.V(logger.Error) {
+			glog.Errorf("Unhandled trie error: %v", err)
+		}
+		return self.key(rn)
 	}
 
 	return nil

trie/proof.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
@@ -39,7 +41,14 @@ func (t *Trie) Prove(key []byte) []rlp.RawValue {
 		case nil:
 			return nil
 		case hashNode:
-			tn = t.resolveHash(n)
+			var err error
+			tn, err = t.resolveHash(n, nil, nil)
+			if err != nil {
+				if glog.V(logger.Error) {
+					glog.Errorf("Unhandled trie error: %v", err)
+				}
+				return nil
+			}
 		default:
 			panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
 		}

trie/secure_trie.go

@@ -21,6 +21,8 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
 )
 
 var secureKeyPrefix = []byte("secure-key-")
@@ -46,8 +48,8 @@ type SecureTrie struct {
 // NewSecure creates a trie with an existing root node from db.
 //
 // If root is the zero hash or the sha3 hash of an empty string, the
-// trie is initially empty. Otherwise, New will panics if db is nil
-// and returns ErrMissingRoot if the root node cannpt be found.
+// trie is initially empty. Otherwise, New will panic if db is nil
+// and returns MissingNodeError if the root node cannot be found.
 // Accessing the trie loads nodes from db on demand.
 func NewSecure(root common.Hash, db Database) (*SecureTrie, error) {
 	if db == nil {
@@ -63,7 +65,18 @@ func NewSecure(root common.Hash, db Database) (*SecureTrie, error) {
 // Get returns the value for key stored in the trie.
 // The value bytes must not be modified by the caller.
 func (t *SecureTrie) Get(key []byte) []byte {
-	return t.Trie.Get(t.hashKey(key))
+	res, err := t.TryGet(key)
+	if err != nil && glog.V(logger.Error) {
+		glog.Errorf("Unhandled trie error: %v", err)
+	}
+	return res
+}
+
+// TryGet returns the value for key stored in the trie.
+// The value bytes must not be modified by the caller.
+// If a node was not found in the database, a MissingNodeError is returned.
+func (t *SecureTrie) TryGet(key []byte) ([]byte, error) {
+	return t.Trie.TryGet(t.hashKey(key))
 }
 
 // Update associates key with value in the trie. Subsequent calls to
@@ -73,14 +86,40 @@ func (t *SecureTrie) Get(key []byte) []byte {
 // The value bytes must not be modified by the caller while they are
 // stored in the trie.
 func (t *SecureTrie) Update(key, value []byte) {
+	if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
+		glog.Errorf("Unhandled trie error: %v", err)
+	}
+}
+
+// TryUpdate associates key with value in the trie. Subsequent calls to
+// Get will return value. If value has length zero, any existing value
+// is deleted from the trie and calls to Get will return nil.
+//
+// The value bytes must not be modified by the caller while they are
+// stored in the trie.
+//
+// If a node was not found in the database, a MissingNodeError is returned.
+func (t *SecureTrie) TryUpdate(key, value []byte) error {
 	hk := t.hashKey(key)
-	t.Trie.Update(hk, value)
+	err := t.Trie.TryUpdate(hk, value)
+	if err != nil {
+		return err
+	}
 	t.Trie.db.Put(t.secKey(hk), key)
+	return nil
 }
 
 // Delete removes any existing value for key from the trie.
 func (t *SecureTrie) Delete(key []byte) {
-	t.Trie.Delete(t.hashKey(key))
+	if err := t.TryDelete(key); err != nil && glog.V(logger.Error) {
+		glog.Errorf("Unhandled trie error: %v", err)
+	}
+}
+
+// TryDelete removes any existing value for key from the trie.
+// If a node was not found in the database, a MissingNodeError is returned.
+func (t *SecureTrie) TryDelete(key []byte) error {
+	return t.Trie.TryDelete(t.hashKey(key))
 }
 
 // GetKey returns the sha3 preimage of a hashed key that was