trie: added error handling

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

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