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any-sync/data/treebuilder.go
2022-06-28 15:37:09 +02:00

437 lines
10 KiB
Go

package data
import (
"context"
"errors"
"fmt"
"github.com/anytypeio/go-anytype-infrastructure-experiments/data/threadmodels"
"github.com/anytypeio/go-anytype-infrastructure-experiments/pb"
"github.com/anytypeio/go-anytype-infrastructure-experiments/pkg/lib/logging"
"github.com/anytypeio/go-anytype-infrastructure-experiments/util/slice"
"github.com/gogo/protobuf/proto"
"github.com/textileio/go-threads/core/thread"
"sort"
"time"
)
var (
log = logging.Logger("anytype-data")
ErrEmpty = errors.New("logs empty")
)
type TreeBuilder struct {
cache map[string]*Change
logHeads map[string]*Change
identityKeys map[string]threadmodels.SigningPubKey
signingPubKeyDecoder threadmodels.SigningPubKeyDecoder
tree *Tree
thread threadmodels.Thread
}
func NewTreeBuilder(t threadmodels.Thread, decoder threadmodels.SigningPubKeyDecoder) *TreeBuilder {
return &TreeBuilder{
cache: make(map[string]*Change),
logHeads: make(map[string]*Change),
identityKeys: make(map[string]threadmodels.SigningPubKey),
signingPubKeyDecoder: decoder,
tree: &Tree{}, // TODO: add NewTree method
thread: t,
}
}
func (tb *TreeBuilder) loadChange(id string) (ch *Change, err error) {
if ch, ok := tb.cache[id]; ok {
return ch, nil
}
// TODO: Add virtual changes logic
ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
defer cancel()
record, err := tb.thread.GetRecord(ctx, id)
if err != nil {
return nil, err
}
aclChange := new(pb.ACLChange)
// TODO: think what should we do with such cases, because this can be used by attacker to break our tree
if err = proto.Unmarshal(record.Signed.Payload, aclChange); err != nil {
return
}
var verified bool
verified, err = tb.verify(aclChange.Identity, record.Signed.Payload, record.Signed.Signature)
if err != nil {
return
}
if !verified {
err = fmt.Errorf("the signature of the payload cannot be verified")
return
}
ch, err = NewChange(id, aclChange)
tb.cache[id] = ch
return ch, nil
}
func (tb *TreeBuilder) verify(identity string, payload, signature []byte) (isVerified bool, err error) {
identityKey, exists := tb.identityKeys[identity]
if !exists {
identityKey, err = tb.signingPubKeyDecoder.DecodeFromString(identity)
if err != nil {
return
}
tb.identityKeys[identity] = identityKey
}
return identityKey.Verify(payload, signature)
}
func (tb *TreeBuilder) getLogs() (logs []threadmodels.ThreadLog, err error) {
// TODO: Add beforeId building logic
logs, err = tb.thread.GetLogs()
if err != nil {
return nil, fmt.Errorf("GetLogs error: %w", err)
}
log.Debugf("build tree: logs: %v", logs)
if len(logs) == 0 || len(logs) == 1 && len(logs[0].Head) <= 1 {
return nil, ErrEmpty
}
var nonEmptyLogs = logs[:0]
for _, l := range logs {
if len(l.Head) == 0 {
continue
}
if ch, err := tb.loadChange(l.Head); err != nil {
log.Errorf("loading head %s of the log %s failed: %v", l.Head, l.ID, err)
} else {
tb.logHeads[l.ID] = ch
}
nonEmptyLogs = append(nonEmptyLogs, l)
}
return nonEmptyLogs, nil
}
func (tb *TreeBuilder) Build(fromStart bool) (*Tree, error) {
logs, err := tb.getLogs()
if err != nil {
return nil, err
}
// TODO: check if this should be changed if we are building from start
heads, err := tb.getActualHeads(logs)
if err != nil {
return nil, fmt.Errorf("get acl heads error: %v", err)
}
if fromStart {
if err = tb.buildTreeFromStart(heads); err != nil {
return nil, fmt.Errorf("buildTree error: %v", err)
}
} else {
breakpoint, err := tb.findBreakpoint(heads)
if err != nil {
return nil, fmt.Errorf("findBreakpoint error: %v", err)
}
if err = tb.buildTree(heads, breakpoint); err != nil {
return nil, fmt.Errorf("buildTree error: %v", err)
}
}
tb.cache = nil
return tb.tree, nil
}
func (tb *TreeBuilder) buildTreeFromStart(heads []string) (err error) {
changes, possibleRoots, err := tb.dfsFromStart(heads)
if len(possibleRoots) == 0 {
return fmt.Errorf("cannot have tree without root")
}
root, err := tb.getRoot(possibleRoots)
if err != nil {
return err
}
tb.tree.AddFast(root)
tb.tree.AddFast(changes...)
return
}
func (tb *TreeBuilder) dfsFromStart(stack []string) (buf []*Change, possibleRoots []*Change, err error) {
buf = make([]*Change, 0, len(stack)*2)
uniqMap := make(map[string]struct{})
for len(stack) > 0 {
id := stack[len(stack)-1]
stack = stack[:len(stack)-1]
if _, exists := uniqMap[id]; exists {
continue
}
ch, err := tb.loadChange(id)
if err != nil {
continue
}
uniqMap[id] = struct{}{}
buf = append(buf, ch)
for _, prev := range ch.PreviousIds {
stack = append(stack, prev)
}
if len(ch.PreviousIds) == 0 {
possibleRoots = append(possibleRoots, ch)
}
}
return buf, possibleRoots, nil
}
func (tb *TreeBuilder) buildTree(heads []string, breakpoint string) (err error) {
ch, err := tb.loadChange(breakpoint)
if err != nil {
return
}
tb.tree.AddFast(ch)
changes, err := tb.dfs(heads, breakpoint)
tb.tree.AddFast(changes...)
return
}
func (tb *TreeBuilder) dfs(stack []string, breakpoint string) (buf []*Change, err error) {
buf = make([]*Change, 0, len(stack)*2)
uniqMap := map[string]struct{}{breakpoint: {}}
for len(stack) > 0 {
id := stack[len(stack)-1]
stack = stack[:len(stack)-1]
if _, exists := uniqMap[id]; exists {
continue
}
ch, err := tb.loadChange(id)
if err != nil {
continue
}
uniqMap[id] = struct{}{}
buf = append(buf, ch)
for _, prev := range ch.PreviousIds {
stack = append(stack, prev)
}
}
return buf, nil
}
func (tb *TreeBuilder) getActualHeads(logs []threadmodels.ThreadLog) (heads []string, err error) {
sort.Slice(logs, func(i, j int) bool {
return logs[i].ID < logs[j].ID
})
var knownHeads []string
var validLogs = logs[:0]
for _, l := range logs {
if slice.FindPos(knownHeads, l.Head) != -1 { // do not scan known heads
continue
}
sh, err := tb.getNearSnapshot(l.Head)
if err != nil {
log.Warnf("can't get near snapshot: %v; ignore", err)
continue
}
if sh.LogHeads != nil {
for _, headId := range sh.LogHeads {
knownHeads = append(knownHeads, headId)
}
}
validLogs = append(validLogs, l)
}
for _, l := range validLogs {
if slice.FindPos(knownHeads, l.Head) != -1 { // do not scan known heads
continue
} else {
heads = append(heads, l.Head)
}
}
if len(heads) == 0 {
return nil, fmt.Errorf("no usable logs in head")
}
return
}
func (tb *TreeBuilder) getNearSnapshot(id string) (sh *Change, err error) {
ch, err := tb.loadChange(id)
if err != nil {
return
}
if ch.IsSnapshot {
sh = ch
} else {
sh, err = tb.loadChange(ch.SnapshotId)
if err != nil {
return nil, err
}
}
return sh, nil
}
func (tb *TreeBuilder) findBreakpoint(heads []string) (breakpoint string, err error) {
var (
ch *Change
snapshotIds []string
)
for _, head := range heads {
if ch, err = tb.loadChange(head); err != nil {
return
}
shId := ch.SnapshotId
if slice.FindPos(snapshotIds, shId) == -1 {
snapshotIds = append(snapshotIds, shId)
}
}
return tb.findCommonSnapshot(snapshotIds)
}
func (tb *TreeBuilder) findCommonSnapshot(snapshotIds []string) (snapshotId string, err error) {
if len(snapshotIds) == 1 {
return snapshotIds[0], nil
} else if len(snapshotIds) == 0 {
return "", fmt.Errorf("snapshots not found")
}
for len(snapshotIds) > 1 {
l := len(snapshotIds)
shId, e := tb.findCommonForTwoSnapshots(snapshotIds[l-2], snapshotIds[l-1])
if e != nil {
return "", e
}
snapshotIds[l-2] = shId
snapshotIds = snapshotIds[:l-1]
}
return snapshotIds[0], nil
}
func (tb *TreeBuilder) findCommonForTwoSnapshots(s1, s2 string) (s string, err error) {
// fast cases
if s1 == s2 {
return s1, nil
}
ch1, err := tb.loadChange(s1)
if err != nil {
return "", err
}
if ch1.SnapshotId == s2 {
return s2, nil
}
ch2, err := tb.loadChange(s2)
if err != nil {
return "", err
}
if ch2.SnapshotId == s1 {
return s1, nil
}
if ch1.SnapshotId == ch2.SnapshotId && ch1.SnapshotId != "" {
return ch1.SnapshotId, nil
}
// traverse
var t1 = make([]string, 0, 5)
var t2 = make([]string, 0, 5)
t1 = append(t1, ch1.Id, ch1.SnapshotId)
t2 = append(t2, ch2.Id, ch2.SnapshotId)
for {
lid1 := t1[len(t1)-1]
if lid1 != "" {
l1, e := tb.loadChange(lid1)
if e != nil {
return "", e
}
if l1.SnapshotId != "" {
if slice.FindPos(t2, l1.SnapshotId) != -1 {
return l1.SnapshotId, nil
}
}
t1 = append(t1, l1.SnapshotId)
}
lid2 := t2[len(t2)-1]
if lid2 != "" {
l2, e := tb.loadChange(t2[len(t2)-1])
if e != nil {
return "", e
}
if l2.SnapshotId != "" {
if slice.FindPos(t1, l2.SnapshotId) != -1 {
return l2.SnapshotId, nil
}
}
t2 = append(t2, l2.SnapshotId)
}
if lid1 == "" && lid2 == "" {
break
}
}
log.Warnf("changes build tree: possible versions split")
// prefer not first snapshot
if len(ch1.PreviousIds) == 0 && len(ch2.PreviousIds) > 0 {
log.Warnf("changes build tree: prefer %s(%d prevIds) over %s(%d prevIds)", s2, len(ch2.PreviousIds), s1, len(ch1.PreviousIds))
return s2, nil
} else if len(ch1.PreviousIds) > 0 && len(ch2.PreviousIds) == 0 {
log.Warnf("changes build tree: prefer %s(%d prevIds) over %s(%d prevIds)", s1, len(ch1.PreviousIds), s2, len(ch2.PreviousIds))
return s1, nil
}
isEmptySnapshot := func(ch *Change) bool {
// TODO: add more sophisticated checks in Change for snapshots
return !ch.IsSnapshot
}
// TODO: can we even have empty snapshots?
// prefer not empty snapshot
if isEmptySnapshot(ch1) && !isEmptySnapshot(ch2) {
log.Warnf("changes build tree: prefer %s(not empty) over %s(empty)", s2, s1)
return s2, nil
} else if isEmptySnapshot(ch2) && !isEmptySnapshot(ch1) {
log.Warnf("changes build tree: prefer %s(not empty) over %s(empty)", s1, s2)
return s1, nil
}
// TODO: add virtual change mechanics
// unexpected behavior - just return lesser id
if s1 < s2 {
log.Warnf("changes build tree: prefer %s (%s<%s)", s1, s1, s2)
return s1, nil
}
log.Warnf("changes build tree: prefer %s (%s<%s)", s2, s2, s1)
return s2, nil
}
func (tb *TreeBuilder) getRoot(possibleRoots []*Change) (*Change, error) {
threadId, err := thread.Decode(tb.thread.ID())
if err != nil {
return nil, err
}
for _, r := range possibleRoots {
id := r.Content.Identity
sk, err := tb.signingPubKeyDecoder.DecodeFromString(id)
if err != nil {
continue
}
res, err := threadmodels.VerifyACLThreadID(sk, threadId)
if err != nil {
continue
}
if res {
return r, nil
}
}
return nil, fmt.Errorf("could not find any root")
}