gaspersic/go-ethereum
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

trie: added error handling

Browse Source 
Created alternate versions of Trie and SecureTrie functions that can return a MissingNodeError (used by ODR services)
This commit is contained in:
zsfelfoldi
2015-11-25 18:28:21 +01:00
parent 66d47ced48
commit 52904ae32f
7 changed files with 346 additions and 71 deletions
Download Patch File Download Diff File Expand all files Collapse all files

210
trie/trie.go
View File

@ -19,7 +19,6 @@ package trie
import (
"bytes"
"errors"
"fmt"
"hash"
@ -44,7 +43,10 @@ var (
emptyState = crypto.Sha3Hash(nil)
)
var ErrMissingRoot = errors.New("missing root node")
// ClearGlobalCache clears the global trie cache
func ClearGlobalCache() {
globalCache.Clear()
}
// Database must be implemented by backing stores for the trie.
type Database interface {
@ -67,8 +69,9 @@ type DatabaseWriter interface {
//
// Trie is not safe for concurrent use.
type Trie struct {
root node
db Database
root node
db Database
originalRoot common.Hash
*hasher
}
@ -76,16 +79,19 @@ type Trie struct {
//
// If root is the zero hash or the sha3 hash of an empty string, the
// trie is initially empty and does not require a database. Otherwise,
// New will panics if db is nil or root does not exist in the
// database. Accessing the trie loads nodes from db on demand.
// New will panic if db is nil and returns a MissingNodeError if root does
// not exist in the database. Accessing the trie loads nodes from db on demand.
func New(root common.Hash, db Database) (*Trie, error) {
trie := &Trie{db: db}
trie := &Trie{db: db, originalRoot: root}
if (root != common.Hash{}) && root != emptyRoot {
if db == nil {
panic("trie.New: cannot use existing root without a database")
}
if v, _ := trie.db.Get(root[:]); len(v) == 0 {
return nil, ErrMissingRoot
return nil, &MissingNodeError{
RootHash: root,
NodeHash: root,
}
}
trie.root = hashNode(root.Bytes())
}
@ -100,28 +106,44 @@ func (t *Trie) Iterator() *Iterator {
// Get returns the value for key stored in the trie.
// The value bytes must not be modified by the caller.
func (t *Trie) Get(key []byte) []byte {
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 *Trie) TryGet(key []byte) ([]byte, error) {
key = compactHexDecode(key)
pos := 0
tn := t.root
for len(key) > 0 {
for pos < len(key) {
switch n := tn.(type) {
case shortNode:
if len(key) < len(n.Key) || !bytes.Equal(n.Key, key[:len(n.Key)]) {
return nil
if len(key)-pos < len(n.Key) || !bytes.Equal(n.Key, key[pos:pos+len(n.Key)]) {
return nil, nil
}
tn = n.Val
key = key[len(n.Key):]
pos += len(n.Key)
case fullNode:
tn = n[key[0]]
key = key[1:]
tn = n[key[pos]]
pos++
case nil:
return nil
return nil, nil
case hashNode:
tn = t.resolveHash(n)
var err error
tn, err = t.resolveHash(n, key[:pos], key[pos:])
if err != nil {
return nil, err
}
default:
panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
}
}
return tn.(valueNode)
return tn.(valueNode), nil
}
// Update associates key with value in the trie. Subsequent calls to
@ -131,17 +153,40 @@ func (t *Trie) Get(key []byte) []byte {
// The value bytes must not be modified by the caller while they are
// stored in the trie.
func (t *Trie) Update(key, value []byte) {
k := compactHexDecode(key)
if len(value) != 0 {
t.root = t.insert(t.root, k, valueNode(value))
} else {
t.root = t.delete(t.root, k)
if err := t.TryUpdate(key, value); err != nil && glog.V(logger.Error) {
glog.Errorf("Unhandled trie error: %v", err)
}
}
func (t *Trie) insert(n node, key []byte, value node) node {
// 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 *Trie) TryUpdate(key, value []byte) error {
k := compactHexDecode(key)
if len(value) != 0 {
n, err := t.insert(t.root, nil, k, valueNode(value))
if err != nil {
return err
}
t.root = n
} else {
n, err := t.delete(t.root, nil, k)
if err != nil {
return err
}
t.root = n
}
return nil
}
func (t *Trie) insert(n node, prefix, key []byte, value node) (node, error) {
if len(key) == 0 {
return value
return value, nil
}
switch n := n.(type) {
case shortNode:
@ -149,25 +194,40 @@ func (t *Trie) insert(n node, key []byte, value node) node {
// If the whole key matches, keep this short node as is
// and only update the value.
if matchlen == len(n.Key) {
return shortNode{n.Key, t.insert(n.Val, key[matchlen:], value)}
nn, err := t.insert(n.Val, append(prefix, key[:matchlen]...), key[matchlen:], value)
if err != nil {
return nil, err
}
return shortNode{n.Key, nn}, nil
}
// Otherwise branch out at the index where they differ.
var branch fullNode
branch[n.Key[matchlen]] = t.insert(nil, n.Key[matchlen+1:], n.Val)
branch[key[matchlen]] = t.insert(nil, key[matchlen+1:], value)
var err error
branch[n.Key[matchlen]], err = t.insert(nil, append(prefix, n.Key[:matchlen+1]...), n.Key[matchlen+1:], n.Val)
if err != nil {
return nil, err
}
branch[key[matchlen]], err = t.insert(nil, append(prefix, key[:matchlen+1]...), key[matchlen+1:], value)
if err != nil {
return nil, err
}
// Replace this shortNode with the branch if it occurs at index 0.
if matchlen == 0 {
return branch
return branch, nil
}
// Otherwise, replace it with a short node leading up to the branch.
return shortNode{key[:matchlen], branch}
return shortNode{key[:matchlen], branch}, nil
case fullNode:
n[key[0]] = t.insert(n[key[0]], key[1:], value)
return n
nn, err := t.insert(n[key[0]], append(prefix, key[0]), key[1:], value)
if err != nil {
return nil, err
}
n[key[0]] = nn
return n, nil
case nil:
return shortNode{key, value}
return shortNode{key, value}, nil
case hashNode:
// We've hit a part of the trie that isn't loaded yet. Load
@ -176,7 +236,11 @@ func (t *Trie) insert(n node, key []byte, value node) node {
//
// TODO: track whether insertion changed the value and keep
// n as a hash node if it didn't.
return t.insert(t.resolveHash(n), key, value)
rn, err := t.resolveHash(n, prefix, key)
if err != nil {
return nil, err
}
return t.insert(rn, prefix, key, value)
default:
panic(fmt.Sprintf("%T: invalid node: %v", n, n))
@ -185,28 +249,44 @@ func (t *Trie) insert(n node, key []byte, value node) node {
// Delete removes any existing value for key from the trie.
func (t *Trie) Delete(key []byte) {
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 *Trie) TryDelete(key []byte) error {
k := compactHexDecode(key)
t.root = t.delete(t.root, k)
n, err := t.delete(t.root, nil, k)
if err != nil {
return err
}
t.root = n
return nil
}
// delete returns the new root of the trie with key deleted.
// It reduces the trie to minimal form by simplifying
// nodes on the way up after deleting recursively.
func (t *Trie) delete(n node, key []byte) node {
func (t *Trie) delete(n node, prefix, key []byte) (node, error) {
switch n := n.(type) {
case shortNode:
matchlen := prefixLen(key, n.Key)
if matchlen < len(n.Key) {
return n // don't replace n on mismatch
return n, nil // don't replace n on mismatch
}
if matchlen == len(key) {
return nil // remove n entirely for whole matches
return nil, nil // remove n entirely for whole matches
}
// The key is longer than n.Key. Remove the remaining suffix
// from the subtrie. Child can never be nil here since the
// subtrie must contain at least two other values with keys
// longer than n.Key.
child := t.delete(n.Val, key[len(n.Key):])
child, err := t.delete(n.Val, append(prefix, key[:len(n.Key)]...), key[len(n.Key):])
if err != nil {
return nil, err
}
switch child := child.(type) {
case shortNode:
// Deleting from the subtrie reduced it to another
@ -215,13 +295,17 @@ func (t *Trie) delete(n node, key []byte) node {
// always creates a new slice) instead of append to
// avoid modifying n.Key since it might be shared with
// other nodes.
return shortNode{concat(n.Key, child.Key...), child.Val}
return shortNode{concat(n.Key, child.Key...), child.Val}, nil
default:
return shortNode{n.Key, child}
return shortNode{n.Key, child}, nil
}
case fullNode:
n[key[0]] = t.delete(n[key[0]], key[1:])
nn, err := t.delete(n[key[0]], append(prefix, key[0]), key[1:])
if err != nil {
return nil, err
}
n[key[0]] = nn
// Check how many non-nil entries are left after deleting and
// reduce the full node to a short node if only one entry is
// left. Since n must've contained at least two children
@ -250,21 +334,24 @@ func (t *Trie) delete(n node, key []byte) node {
// shortNode{..., shortNode{...}}. Since the entry
// might not be loaded yet, resolve it just for this
// check.
cnode := t.resolve(n[pos])
cnode, err := t.resolve(n[pos], prefix, []byte{byte(pos)})
if err != nil {
return nil, err
}
if cnode, ok := cnode.(shortNode); ok {
k := append([]byte{byte(pos)}, cnode.Key...)
return shortNode{k, cnode.Val}
return shortNode{k, cnode.Val}, nil
}
}
// Otherwise, n is replaced by a one-nibble short node
// containing the child.
return shortNode{[]byte{byte(pos)}, n[pos]}
return shortNode{[]byte{byte(pos)}, n[pos]}, nil
}
// n still contains at least two values and cannot be reduced.
return n
return n, nil
case nil:
return nil
return nil, nil
case hashNode:
// We've hit a part of the trie that isn't loaded yet. Load
@ -273,7 +360,11 @@ func (t *Trie) delete(n node, key []byte) node {
//
// TODO: track whether deletion actually hit a key and keep
// n as a hash node if it didn't.
return t.delete(t.resolveHash(n), key)
rn, err := t.resolveHash(n, prefix, key)
if err != nil {
return nil, err
}
return t.delete(rn, prefix, key)
default:
panic(fmt.Sprintf("%T: invalid node: %v (%v)", n, n, key))
@ -287,34 +378,31 @@ func concat(s1 []byte, s2 ...byte) []byte {
return r
}
func (t *Trie) resolve(n node) node {
func (t *Trie) resolve(n node, prefix, suffix []byte) (node, error) {
if n, ok := n.(hashNode); ok {
return t.resolveHash(n)
return t.resolveHash(n, prefix, suffix)
}
return n
return n, nil
}
func (t *Trie) resolveHash(n hashNode) node {
func (t *Trie) resolveHash(n hashNode, prefix, suffix []byte) (node, error) {
if v, ok := globalCache.Get(n); ok {
return v
return v, nil
}
enc, err := t.db.Get(n)
if err != nil || enc == nil {
// TODO: This needs to be improved to properly distinguish errors.
// Disk I/O errors shouldn't produce nil (and cause a
// consensus failure or weird crash), but it is unclear how
// they could be handled because the entire stack above the trie isn't
// prepared to cope with missing state nodes.
if glog.V(logger.Error) {
glog.Errorf("Dangling hash node ref %x: %v", n, err)
return nil, &MissingNodeError{
RootHash: t.originalRoot,
NodeHash: common.BytesToHash(n),
KeyPrefix: prefix,
KeySuffix: suffix,
}
return nil
}
dec := mustDecodeNode(n, enc)
if dec != nil {
globalCache.Put(n, dec)
}
return dec
return dec, nil
}
// Root returns the root hash of the trie.