plugeth/swarm/api/manifest.go
Lewis Marshall 60c858a529 swarm/api: make api.NewManifest synchronous (#14880)
Previously, NewManifest was asynchronous so subsequent code which tried
to use the returned manifest could error as the manifest was not yet
persisted.
2017-07-31 15:58:19 +02:00

471 lines
12 KiB
Go

// Copyright 2016 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 api
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/swarm/storage"
)
const (
ManifestType = "application/bzz-manifest+json"
)
// Manifest represents a swarm manifest
type Manifest struct {
Entries []ManifestEntry `json:"entries,omitempty"`
}
// ManifestEntry represents an entry in a swarm manifest
type ManifestEntry struct {
Hash string `json:"hash,omitempty"`
Path string `json:"path,omitempty"`
ContentType string `json:"contentType,omitempty"`
Mode int64 `json:"mode,omitempty"`
Size int64 `json:"size,omitempty"`
ModTime time.Time `json:"mod_time,omitempty"`
Status int `json:"status,omitempty"`
}
// ManifestList represents the result of listing files in a manifest
type ManifestList struct {
CommonPrefixes []string `json:"common_prefixes,omitempty"`
Entries []*ManifestEntry `json:"entries,omitempty"`
}
// NewManifest creates and stores a new, empty manifest
func (a *Api) NewManifest() (storage.Key, error) {
var manifest Manifest
data, err := json.Marshal(&manifest)
if err != nil {
return nil, err
}
return a.Store(bytes.NewReader(data), int64(len(data)), &sync.WaitGroup{})
}
// ManifestWriter is used to add and remove entries from an underlying manifest
type ManifestWriter struct {
api *Api
trie *manifestTrie
quitC chan bool
}
func (a *Api) NewManifestWriter(key storage.Key, quitC chan bool) (*ManifestWriter, error) {
trie, err := loadManifest(a.dpa, key, quitC)
if err != nil {
return nil, fmt.Errorf("error loading manifest %s: %s", key, err)
}
return &ManifestWriter{a, trie, quitC}, nil
}
// AddEntry stores the given data and adds the resulting key to the manifest
func (m *ManifestWriter) AddEntry(data io.Reader, e *ManifestEntry) (storage.Key, error) {
key, err := m.api.Store(data, e.Size, nil)
if err != nil {
return nil, err
}
entry := newManifestTrieEntry(e, nil)
entry.Hash = key.String()
m.trie.addEntry(entry, m.quitC)
return key, nil
}
// RemoveEntry removes the given path from the manifest
func (m *ManifestWriter) RemoveEntry(path string) error {
m.trie.deleteEntry(path, m.quitC)
return nil
}
// Store stores the manifest, returning the resulting storage key
func (m *ManifestWriter) Store() (storage.Key, error) {
return m.trie.hash, m.trie.recalcAndStore()
}
// ManifestWalker is used to recursively walk the entries in the manifest and
// all of its submanifests
type ManifestWalker struct {
api *Api
trie *manifestTrie
quitC chan bool
}
func (a *Api) NewManifestWalker(key storage.Key, quitC chan bool) (*ManifestWalker, error) {
trie, err := loadManifest(a.dpa, key, quitC)
if err != nil {
return nil, fmt.Errorf("error loading manifest %s: %s", key, err)
}
return &ManifestWalker{a, trie, quitC}, nil
}
// SkipManifest is used as a return value from WalkFn to indicate that the
// manifest should be skipped
var SkipManifest = errors.New("skip this manifest")
// WalkFn is the type of function called for each entry visited by a recursive
// manifest walk
type WalkFn func(entry *ManifestEntry) error
// Walk recursively walks the manifest calling walkFn for each entry in the
// manifest, including submanifests
func (m *ManifestWalker) Walk(walkFn WalkFn) error {
return m.walk(m.trie, "", walkFn)
}
func (m *ManifestWalker) walk(trie *manifestTrie, prefix string, walkFn WalkFn) error {
for _, entry := range trie.entries {
if entry == nil {
continue
}
entry.Path = prefix + entry.Path
err := walkFn(&entry.ManifestEntry)
if err != nil {
if entry.ContentType == ManifestType && err == SkipManifest {
continue
}
return err
}
if entry.ContentType != ManifestType {
continue
}
if err := trie.loadSubTrie(entry, nil); err != nil {
return err
}
if err := m.walk(entry.subtrie, entry.Path, walkFn); err != nil {
return err
}
}
return nil
}
type manifestTrie struct {
dpa *storage.DPA
entries [257]*manifestTrieEntry // indexed by first character of basePath, entries[256] is the empty basePath entry
hash storage.Key // if hash != nil, it is stored
}
func newManifestTrieEntry(entry *ManifestEntry, subtrie *manifestTrie) *manifestTrieEntry {
return &manifestTrieEntry{
ManifestEntry: *entry,
subtrie: subtrie,
}
}
type manifestTrieEntry struct {
ManifestEntry
subtrie *manifestTrie
}
func loadManifest(dpa *storage.DPA, hash storage.Key, quitC chan bool) (trie *manifestTrie, err error) { // non-recursive, subtrees are downloaded on-demand
log.Trace(fmt.Sprintf("manifest lookup key: '%v'.", hash.Log()))
// retrieve manifest via DPA
manifestReader := dpa.Retrieve(hash)
return readManifest(manifestReader, hash, dpa, quitC)
}
func readManifest(manifestReader storage.LazySectionReader, hash storage.Key, dpa *storage.DPA, quitC chan bool) (trie *manifestTrie, err error) { // non-recursive, subtrees are downloaded on-demand
// TODO check size for oversized manifests
size, err := manifestReader.Size(quitC)
if err != nil { // size == 0
// can't determine size means we don't have the root chunk
err = fmt.Errorf("Manifest not Found")
return
}
manifestData := make([]byte, size)
read, err := manifestReader.Read(manifestData)
if int64(read) < size {
log.Trace(fmt.Sprintf("Manifest %v not found.", hash.Log()))
if err == nil {
err = fmt.Errorf("Manifest retrieval cut short: read %v, expect %v", read, size)
}
return
}
log.Trace(fmt.Sprintf("Manifest %v retrieved", hash.Log()))
var man struct {
Entries []*manifestTrieEntry `json:"entries"`
}
err = json.Unmarshal(manifestData, &man)
if err != nil {
err = fmt.Errorf("Manifest %v is malformed: %v", hash.Log(), err)
log.Trace(fmt.Sprintf("%v", err))
return
}
log.Trace(fmt.Sprintf("Manifest %v has %d entries.", hash.Log(), len(man.Entries)))
trie = &manifestTrie{
dpa: dpa,
}
for _, entry := range man.Entries {
trie.addEntry(entry, quitC)
}
return
}
func (self *manifestTrie) addEntry(entry *manifestTrieEntry, quitC chan bool) {
self.hash = nil // trie modified, hash needs to be re-calculated on demand
if len(entry.Path) == 0 {
self.entries[256] = entry
return
}
b := byte(entry.Path[0])
oldentry := self.entries[b]
if (oldentry == nil) || (oldentry.Path == entry.Path && oldentry.ContentType != ManifestType) {
self.entries[b] = entry
return
}
cpl := 0
for (len(entry.Path) > cpl) && (len(oldentry.Path) > cpl) && (entry.Path[cpl] == oldentry.Path[cpl]) {
cpl++
}
if (oldentry.ContentType == ManifestType) && (cpl == len(oldentry.Path)) {
if self.loadSubTrie(oldentry, quitC) != nil {
return
}
entry.Path = entry.Path[cpl:]
oldentry.subtrie.addEntry(entry, quitC)
oldentry.Hash = ""
return
}
commonPrefix := entry.Path[:cpl]
subtrie := &manifestTrie{
dpa: self.dpa,
}
entry.Path = entry.Path[cpl:]
oldentry.Path = oldentry.Path[cpl:]
subtrie.addEntry(entry, quitC)
subtrie.addEntry(oldentry, quitC)
self.entries[b] = newManifestTrieEntry(&ManifestEntry{
Path: commonPrefix,
ContentType: ManifestType,
}, subtrie)
}
func (self *manifestTrie) getCountLast() (cnt int, entry *manifestTrieEntry) {
for _, e := range self.entries {
if e != nil {
cnt++
entry = e
}
}
return
}
func (self *manifestTrie) deleteEntry(path string, quitC chan bool) {
self.hash = nil // trie modified, hash needs to be re-calculated on demand
if len(path) == 0 {
self.entries[256] = nil
return
}
b := byte(path[0])
entry := self.entries[b]
if entry == nil {
return
}
if entry.Path == path {
self.entries[b] = nil
return
}
epl := len(entry.Path)
if (entry.ContentType == ManifestType) && (len(path) >= epl) && (path[:epl] == entry.Path) {
if self.loadSubTrie(entry, quitC) != nil {
return
}
entry.subtrie.deleteEntry(path[epl:], quitC)
entry.Hash = ""
// remove subtree if it has less than 2 elements
cnt, lastentry := entry.subtrie.getCountLast()
if cnt < 2 {
if lastentry != nil {
lastentry.Path = entry.Path + lastentry.Path
}
self.entries[b] = lastentry
}
}
}
func (self *manifestTrie) recalcAndStore() error {
if self.hash != nil {
return nil
}
var buffer bytes.Buffer
buffer.WriteString(`{"entries":[`)
list := &Manifest{}
for _, entry := range self.entries {
if entry != nil {
if entry.Hash == "" { // TODO: paralellize
err := entry.subtrie.recalcAndStore()
if err != nil {
return err
}
entry.Hash = entry.subtrie.hash.String()
}
list.Entries = append(list.Entries, entry.ManifestEntry)
}
}
manifest, err := json.Marshal(list)
if err != nil {
return err
}
sr := bytes.NewReader(manifest)
wg := &sync.WaitGroup{}
key, err2 := self.dpa.Store(sr, int64(len(manifest)), wg, nil)
wg.Wait()
self.hash = key
return err2
}
func (self *manifestTrie) loadSubTrie(entry *manifestTrieEntry, quitC chan bool) (err error) {
if entry.subtrie == nil {
hash := common.Hex2Bytes(entry.Hash)
entry.subtrie, err = loadManifest(self.dpa, hash, quitC)
entry.Hash = "" // might not match, should be recalculated
}
return
}
func (self *manifestTrie) listWithPrefixInt(prefix, rp string, quitC chan bool, cb func(entry *manifestTrieEntry, suffix string)) error {
plen := len(prefix)
var start, stop int
if plen == 0 {
start = 0
stop = 256
} else {
start = int(prefix[0])
stop = start
}
for i := start; i <= stop; i++ {
select {
case <-quitC:
return fmt.Errorf("aborted")
default:
}
entry := self.entries[i]
if entry != nil {
epl := len(entry.Path)
if entry.ContentType == ManifestType {
l := plen
if epl < l {
l = epl
}
if prefix[:l] == entry.Path[:l] {
err := self.loadSubTrie(entry, quitC)
if err != nil {
return err
}
err = entry.subtrie.listWithPrefixInt(prefix[l:], rp+entry.Path[l:], quitC, cb)
if err != nil {
return err
}
}
} else {
if (epl >= plen) && (prefix == entry.Path[:plen]) {
cb(entry, rp+entry.Path[plen:])
}
}
}
}
return nil
}
func (self *manifestTrie) listWithPrefix(prefix string, quitC chan bool, cb func(entry *manifestTrieEntry, suffix string)) (err error) {
return self.listWithPrefixInt(prefix, "", quitC, cb)
}
func (self *manifestTrie) findPrefixOf(path string, quitC chan bool) (entry *manifestTrieEntry, pos int) {
log.Trace(fmt.Sprintf("findPrefixOf(%s)", path))
if len(path) == 0 {
return self.entries[256], 0
}
b := byte(path[0])
entry = self.entries[b]
if entry == nil {
return self.entries[256], 0
}
epl := len(entry.Path)
log.Trace(fmt.Sprintf("path = %v entry.Path = %v epl = %v", path, entry.Path, epl))
if (len(path) >= epl) && (path[:epl] == entry.Path) {
log.Trace(fmt.Sprintf("entry.ContentType = %v", entry.ContentType))
if entry.ContentType == ManifestType {
err := self.loadSubTrie(entry, quitC)
if err != nil {
return nil, 0
}
entry, pos = entry.subtrie.findPrefixOf(path[epl:], quitC)
if entry != nil {
pos += epl
}
} else {
pos = epl
}
}
return
}
// file system manifest always contains regularized paths
// no leading or trailing slashes, only single slashes inside
func RegularSlashes(path string) (res string) {
for i := 0; i < len(path); i++ {
if (path[i] != '/') || ((i > 0) && (path[i-1] != '/')) {
res = res + path[i:i+1]
}
}
if (len(res) > 0) && (res[len(res)-1] == '/') {
res = res[:len(res)-1]
}
return
}
func (self *manifestTrie) getEntry(spath string) (entry *manifestTrieEntry, fullpath string) {
path := RegularSlashes(spath)
var pos int
quitC := make(chan bool)
entry, pos = self.findPrefixOf(path, quitC)
return entry, path[:pos]
}