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node.go
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node.go
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// Copyright 2020 The Swarm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mantaray
import (
"bytes"
"context"
"errors"
"fmt"
)
const (
PathSeparator = '/' // path separator
)
var (
ZeroObfuscationKey []byte
)
func init() {
ZeroObfuscationKey = make([]byte, 32)
}
// Error used when lookup path does not match
var (
ErrNotFound = errors.New("not found")
ErrEmptyPath = errors.New("empty path")
ErrMetadataTooLarge = errors.New("metadata too large")
)
// Node represents a mantaray Node
type Node struct {
nodeType uint8
refBytesSize int
obfuscationKey []byte
ref []byte // reference to uninstantiated Node persisted serialised
entry []byte
metadata map[string]string
forks map[byte]*fork
}
type fork struct {
prefix []byte // the non-branching part of the subpath
*Node // in memory structure that represents the Node
}
const (
nodeTypeValue = uint8(2)
nodeTypeEdge = uint8(4)
nodeTypeWithPathSeparator = uint8(8)
nodeTypeWithMetadata = uint8(16)
nodeTypeMask = uint8(255)
)
func nodeTypeIsWithMetadataType(nodeType uint8) bool {
return nodeType&nodeTypeWithMetadata == nodeTypeWithMetadata
}
// NewNodeRef is the exported Node constructor used to represent manifests by reference
func NewNodeRef(ref []byte) *Node {
return &Node{ref: ref}
}
// New is the constructor for in-memory Node structure
func New() *Node {
return &Node{forks: make(map[byte]*fork)}
}
func notFound(path []byte) error {
return fmt.Errorf("entry on '%s' ('%x'): %w", path, path, ErrNotFound)
}
// IsValueType returns true if the node contains entry.
func (n *Node) IsValueType() bool {
return n.nodeType&nodeTypeValue == nodeTypeValue
}
// IsEdgeType returns true if the node forks into other nodes.
func (n *Node) IsEdgeType() bool {
return n.nodeType&nodeTypeEdge == nodeTypeEdge
}
// IsWithPathSeparatorType returns true if the node path contains separator character.
func (n *Node) IsWithPathSeparatorType() bool {
return n.nodeType&nodeTypeWithPathSeparator == nodeTypeWithPathSeparator
}
// IsWithMetadataType returns true if the node contains metadata.
func (n *Node) IsWithMetadataType() bool {
return n.nodeType&nodeTypeWithMetadata == nodeTypeWithMetadata
}
func (n *Node) makeValue() {
n.nodeType = n.nodeType | nodeTypeValue
}
func (n *Node) makeEdge() {
n.nodeType = n.nodeType | nodeTypeEdge
}
func (n *Node) makeWithPathSeparator() {
n.nodeType = n.nodeType | nodeTypeWithPathSeparator
}
func (n *Node) makeWithMetadata() {
n.nodeType = n.nodeType | nodeTypeWithMetadata
}
//nolint,unused
func (n *Node) makeNotValue() {
n.nodeType = (nodeTypeMask ^ nodeTypeValue) & n.nodeType
}
//nolint,unused
func (n *Node) makeNotEdge() {
n.nodeType = (nodeTypeMask ^ nodeTypeEdge) & n.nodeType
}
func (n *Node) makeNotWithPathSeparator() {
n.nodeType = (nodeTypeMask ^ nodeTypeWithPathSeparator) & n.nodeType
}
//nolint,unused
func (n *Node) makeNotWithMetadata() {
n.nodeType = (nodeTypeMask ^ nodeTypeWithMetadata) & n.nodeType
}
func (n *Node) SetObfuscationKey(obfuscationKey []byte) {
bytes := make([]byte, 32)
copy(bytes, obfuscationKey)
n.obfuscationKey = bytes
}
// Reference returns the address of the mantaray node if saved.
func (n *Node) Reference() []byte {
return n.ref
}
// Entry returns the value stored on the specific path.
func (n *Node) Entry() []byte {
return n.entry
}
// Metadata returns the metadata stored on the specific path.
func (n *Node) Metadata() map[string]string {
return n.metadata
}
// LookupNode finds the node for a path or returns error if not found
func (n *Node) LookupNode(ctx context.Context, path []byte, l Loader) (*Node, error) {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
if n.forks == nil {
if err := n.load(ctx, l); err != nil {
return nil, err
}
}
if len(path) == 0 {
return n, nil
}
f := n.forks[path[0]]
if f == nil {
return nil, notFound(path)
}
c := common(f.prefix, path)
if len(c) == len(f.prefix) {
return f.Node.LookupNode(ctx, path[len(c):], l)
}
return nil, notFound(path)
}
// Lookup finds the entry for a path or returns error if not found
func (n *Node) Lookup(ctx context.Context, path []byte, l Loader) ([]byte, error) {
node, err := n.LookupNode(ctx, path, l)
if err != nil {
return nil, err
}
if !node.IsValueType() && len(path) > 0 {
return nil, notFound(path)
}
return node.entry, nil
}
// Add adds an entry to the path
func (n *Node) Add(ctx context.Context, path, entry []byte, metadata map[string]string, ls LoadSaver) error {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
if n.refBytesSize == 0 {
if len(entry) > 256 {
return fmt.Errorf("node entry size > 256: %d", len(entry))
}
// empty entry for directories
if len(entry) > 0 {
n.refBytesSize = len(entry)
}
} else if len(entry) > 0 && n.refBytesSize != len(entry) {
return fmt.Errorf("invalid entry size: %d, expected: %d", len(entry), n.refBytesSize)
}
if len(path) == 0 {
n.entry = entry
n.makeValue()
if len(metadata) > 0 {
n.metadata = metadata
n.makeWithMetadata()
}
n.ref = nil
return nil
}
if n.forks == nil {
if err := n.load(ctx, ls); err != nil {
return err
}
n.ref = nil
}
f := n.forks[path[0]]
if f == nil {
nn := New()
if len(n.obfuscationKey) > 0 {
nn.SetObfuscationKey(n.obfuscationKey)
}
nn.refBytesSize = n.refBytesSize
// check for prefix size limit
if len(path) > nodePrefixMaxSize {
prefix := path[:nodePrefixMaxSize]
rest := path[nodePrefixMaxSize:]
err := nn.Add(ctx, rest, entry, metadata, ls)
if err != nil {
return err
}
nn.updateIsWithPathSeparator(prefix)
n.forks[path[0]] = &fork{prefix, nn}
n.makeEdge()
return nil
}
nn.entry = entry
if len(metadata) > 0 {
nn.metadata = metadata
nn.makeWithMetadata()
}
nn.makeValue()
nn.updateIsWithPathSeparator(path)
n.forks[path[0]] = &fork{path, nn}
n.makeEdge()
return nil
}
c := common(f.prefix, path)
rest := f.prefix[len(c):]
nn := f.Node
if len(rest) > 0 {
// move current common prefix node
nn = New()
if len(n.obfuscationKey) > 0 {
nn.SetObfuscationKey(n.obfuscationKey)
}
nn.refBytesSize = n.refBytesSize
f.Node.updateIsWithPathSeparator(rest)
nn.forks[rest[0]] = &fork{rest, f.Node}
nn.makeEdge()
// if common path is full path new node is value type
if len(path) == len(c) {
nn.makeValue()
}
}
// NOTE: special case on edge split
nn.updateIsWithPathSeparator(path)
// add new for shared prefix
err := nn.Add(ctx, path[len(c):], entry, metadata, ls)
if err != nil {
return err
}
n.forks[path[0]] = &fork{c, nn}
n.makeEdge()
return nil
}
func (n *Node) updateIsWithPathSeparator(path []byte) {
if bytes.IndexRune(path, PathSeparator) > 0 {
n.makeWithPathSeparator()
} else {
n.makeNotWithPathSeparator()
}
}
// Remove removes a path from the node
func (n *Node) Remove(ctx context.Context, path []byte, ls LoadSaver) error {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
if len(path) == 0 {
return ErrEmptyPath
}
if n.forks == nil {
if err := n.load(ctx, ls); err != nil {
return err
}
}
f := n.forks[path[0]]
if f == nil {
return ErrNotFound
}
prefixIndex := bytes.Index(path, f.prefix)
if prefixIndex != 0 {
return ErrNotFound
}
rest := path[len(f.prefix):]
if len(rest) == 0 {
// full path matched
delete(n.forks, path[0])
return nil
}
return f.Node.Remove(ctx, rest, ls)
}
func common(a, b []byte) (c []byte) {
for i := 0; i < len(a) && i < len(b) && a[i] == b[i]; i++ {
c = append(c, a[i])
}
return c
}
// HasPrefix tests whether the node contains prefix path.
func (n *Node) HasPrefix(ctx context.Context, path []byte, l Loader) (bool, error) {
select {
case <-ctx.Done():
return false, ctx.Err()
default:
}
if n.forks == nil {
if err := n.load(ctx, l); err != nil {
return false, err
}
}
if len(path) == 0 {
return true, nil
}
f := n.forks[path[0]]
if f == nil {
return false, nil
}
c := common(f.prefix, path)
if len(c) == len(f.prefix) {
return f.Node.HasPrefix(ctx, path[len(c):], l)
}
if bytes.HasPrefix(f.prefix, path) {
return true, nil
}
return false, nil
}