syncthing/lib/model/indexhandler.go

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// Copyright (C) 2020 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package model
import (
"context"
"fmt"
"sync"
"time"
"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/db"
"github.com/syncthing/syncthing/lib/events"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/syncthing/syncthing/lib/svcutil"
)
type indexHandler struct {
conn protocol.Connection
downloads *deviceDownloadState
folder string
folderIsReceiveEncrypted bool
prevSequence int64
evLogger events.Logger
cond *sync.Cond
paused bool
fset *db.FileSet
runner service
}
func newIndexHandler(conn protocol.Connection, downloads *deviceDownloadState, folder config.FolderConfiguration, fset *db.FileSet, runner service, startInfo *clusterConfigDeviceInfo, evLogger events.Logger) *indexHandler {
myIndexID := fset.IndexID(protocol.LocalDeviceID)
mySequence := fset.Sequence(protocol.LocalDeviceID)
var startSequence int64
// This is the other side's description of what it knows
// about us. Lets check to see if we can start sending index
// updates directly or need to send the index from start...
if startInfo.local.IndexID == myIndexID {
// They say they've seen our index ID before, so we can
// send a delta update only.
if startInfo.local.MaxSequence > mySequence {
// Safety check. They claim to have more or newer
// index data than we have - either we have lost
// index data, or reset the index without resetting
// the IndexID, or something else weird has
// happened. We send a full index to reset the
// situation.
l.Infof("Device %v folder %s is delta index compatible, but seems out of sync with reality", conn.DeviceID().Short(), folder.Description())
startSequence = 0
} else {
l.Debugf("Device %v folder %s is delta index compatible (mlv=%d)", conn.DeviceID().Short(), folder.Description(), startInfo.local.MaxSequence)
startSequence = startInfo.local.MaxSequence
}
} else if startInfo.local.IndexID != 0 {
// They say they've seen an index ID from us, but it's
// not the right one. Either they are confused or we
// must have reset our database since last talking to
// them. We'll start with a full index transfer.
l.Infof("Device %v folder %s has mismatching index ID for us (%v != %v)", conn.DeviceID().Short(), folder.Description(), startInfo.local.IndexID, myIndexID)
startSequence = 0
} else {
l.Debugf("Device %v folder %s has no index ID for us", conn.DeviceID().Short(), folder.Description())
}
// This is the other side's description of themselves. We
// check to see that it matches the IndexID we have on file,
// otherwise we drop our old index data and expect to get a
// completely new set.
theirIndexID := fset.IndexID(conn.DeviceID())
if startInfo.remote.IndexID == 0 {
// They're not announcing an index ID. This means they
// do not support delta indexes and we should clear any
// information we have from them before accepting their
// index, which will presumably be a full index.
l.Debugf("Device %v folder %s does not announce an index ID", conn.DeviceID().Short(), folder.Description())
fset.Drop(conn.DeviceID())
} else if startInfo.remote.IndexID != theirIndexID {
// The index ID we have on file is not what they're
// announcing. They must have reset their database and
// will probably send us a full index. We drop any
// information we have and remember this new index ID
// instead.
l.Infof("Device %v folder %s has a new index ID (%v)", conn.DeviceID().Short(), folder.Description(), startInfo.remote.IndexID)
fset.Drop(conn.DeviceID())
fset.SetIndexID(conn.DeviceID(), startInfo.remote.IndexID)
}
return &indexHandler{
conn: conn,
downloads: downloads,
folder: folder.ID,
folderIsReceiveEncrypted: folder.Type == config.FolderTypeReceiveEncrypted,
prevSequence: startSequence,
evLogger: evLogger,
fset: fset,
runner: runner,
cond: sync.NewCond(new(sync.Mutex)),
}
}
// waitForFileset waits for the handler to resume and fetches the current fileset.
func (s *indexHandler) waitForFileset(ctx context.Context) (*db.FileSet, error) {
s.cond.L.Lock()
defer s.cond.L.Unlock()
for s.paused {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
s.cond.Wait()
}
}
return s.fset, nil
}
func (s *indexHandler) Serve(ctx context.Context) (err error) {
l.Debugf("Starting index handler for %s to %s at %s (slv=%d)", s.folder, s.conn.DeviceID().Short(), s.conn, s.prevSequence)
stop := make(chan struct{})
defer func() {
err = svcutil.NoRestartErr(err)
l.Debugf("Exiting index handler for %s to %s at %s: %v", s.folder, s.conn.DeviceID().Short(), s.conn, err)
close(stop)
}()
// Broadcast the pause cond when the context quits
go func() {
select {
case <-ctx.Done():
s.cond.Broadcast()
case <-stop:
}
}()
// We need to send one index, regardless of whether there is something to send or not
fset, err := s.waitForFileset(ctx)
if err != nil {
return err
}
err = s.sendIndexTo(ctx, fset)
// Subscribe to LocalIndexUpdated (we have new information to send) and
// DeviceDisconnected (it might be us who disconnected, so we should
// exit).
sub := s.evLogger.Subscribe(events.LocalIndexUpdated | events.DeviceDisconnected)
defer sub.Unsubscribe()
evChan := sub.C()
ticker := time.NewTicker(time.Minute)
defer ticker.Stop()
for err == nil {
fset, err = s.waitForFileset(ctx)
if err != nil {
return err
}
// While we have sent a sequence at least equal to the one
// currently in the database, wait for the local index to update. The
// local index may update for other folders than the one we are
// sending for.
if fset.Sequence(protocol.LocalDeviceID) <= s.prevSequence {
select {
case <-ctx.Done():
return ctx.Err()
case <-evChan:
case <-ticker.C:
}
continue
}
err = s.sendIndexTo(ctx, fset)
// Wait a short amount of time before entering the next loop. If there
// are continuous changes happening to the local index, this gives us
// time to batch them up a little.
select {
case <-ctx.Done():
return ctx.Err()
case <-time.After(250 * time.Millisecond):
}
}
return err
}
// resume might be called because the folder was actually resumed, or just
// because the folder config changed (and thus the runner and potentially fset).
func (s *indexHandler) resume(fset *db.FileSet, runner service) {
s.cond.L.Lock()
s.paused = false
s.fset = fset
s.runner = runner
s.cond.Broadcast()
s.cond.L.Unlock()
}
func (s *indexHandler) pause() {
s.cond.L.Lock()
if s.paused {
s.evLogger.Log(events.Failure, "index handler got paused while already paused")
}
s.paused = true
s.fset = nil
s.runner = nil
s.cond.Broadcast()
s.cond.L.Unlock()
}
// sendIndexTo sends file infos with a sequence number higher than prevSequence and
// returns the highest sent sequence number.
func (s *indexHandler) sendIndexTo(ctx context.Context, fset *db.FileSet) error {
initial := s.prevSequence == 0
batch := db.NewFileInfoBatch(nil)
batch.SetFlushFunc(func(fs []protocol.FileInfo) error {
l.Debugf("%v: Sending %d files (<%d bytes)", s, len(fs), batch.Size())
if initial {
initial = false
return s.conn.Index(ctx, s.folder, fs)
}
return s.conn.IndexUpdate(ctx, s.folder, fs)
})
var err error
var f protocol.FileInfo
snap, err := fset.Snapshot()
if err != nil {
return svcutil.AsFatalErr(err, svcutil.ExitError)
}
defer snap.Release()
previousWasDelete := false
snap.WithHaveSequence(s.prevSequence+1, func(fi protocol.FileIntf) bool {
// This is to make sure that renames (which is an add followed by a delete) land in the same batch.
// Even if the batch is full, we allow a last delete to slip in, we do this by making sure that
// the batch ends with a non-delete, or that the last item in the batch is already a delete
if batch.Full() && (!fi.IsDeleted() || previousWasDelete) {
if err = batch.Flush(); err != nil {
return false
}
}
if shouldDebug() {
if fi.SequenceNo() < s.prevSequence+1 {
panic(fmt.Sprintln("sequence lower than requested, got:", fi.SequenceNo(), ", asked to start at:", s.prevSequence+1))
}
}
if f.Sequence > 0 && fi.SequenceNo() <= f.Sequence {
l.Warnln("Non-increasing sequence detected: Checking and repairing the db...")
// Abort this round of index sending - the next one will pick
// up from the last successful one with the repeaired db.
defer func() {
if fixed, dbErr := fset.RepairSequence(); dbErr != nil {
l.Warnln("Failed repairing sequence entries:", dbErr)
panic("Failed repairing sequence entries")
} else {
s.evLogger.Log(events.Failure, "detected and repaired non-increasing sequence")
l.Infof("Repaired %v sequence entries in database", fixed)
}
}()
return false
}
f = fi.(protocol.FileInfo)
// If this is a folder receiving encrypted files only, we
// mustn't ever send locally changed file infos. Those aren't
// encrypted and thus would be a protocol error at the remote.
if s.folderIsReceiveEncrypted && fi.IsReceiveOnlyChanged() {
return true
}
f = prepareFileInfoForIndex(f)
previousWasDelete = f.IsDeleted()
batch.Append(f)
return true
})
if err != nil {
return err
}
err = batch.Flush()
// Use the sequence of the snapshot we iterated as a starting point for the
// next run. Previously we used the sequence of the last file we sent,
// however it's possible that a higher sequence exists, just doesn't need to
// be sent (e.g. in a receive-only folder, when a local change was
// reverted). No point trying to send nothing again.
s.prevSequence = snap.Sequence(protocol.LocalDeviceID)
return err
}
func (s *indexHandler) receive(fs []protocol.FileInfo, update bool, op string) error {
deviceID := s.conn.DeviceID()
s.cond.L.Lock()
paused := s.paused
fset := s.fset
runner := s.runner
s.cond.L.Unlock()
if paused {
l.Infof("%v for paused folder %q", op, s.folder)
return fmt.Errorf("%v: %w", s.folder, ErrFolderPaused)
}
defer runner.SchedulePull()
s.downloads.Update(s.folder, makeForgetUpdate(fs))
if !update {
fset.Drop(deviceID)
}
for i := range fs {
// The local attributes should never be transmitted over the wire.
// Make sure they look like they weren't.
fs[i].LocalFlags = 0
fs[i].VersionHash = nil
}
fset.Update(deviceID, fs)
seq := fset.Sequence(deviceID)
s.evLogger.Log(events.RemoteIndexUpdated, map[string]interface{}{
"device": deviceID.String(),
"folder": s.folder,
"items": len(fs),
"sequence": seq,
"version": seq, // legacy for sequence
})
return nil
}
func prepareFileInfoForIndex(f protocol.FileInfo) protocol.FileInfo {
// Mark the file as invalid if any of the local bad stuff flags are set.
f.RawInvalid = f.IsInvalid()
// If the file is marked LocalReceive (i.e., changed locally on a
// receive only folder) we do not want it to ever become the
// globally best version, invalid or not.
if f.IsReceiveOnlyChanged() {
f.Version = protocol.Vector{}
}
// The trailer with the encrypted fileinfo is device local, don't send info
// about that to remotes
f.Size -= int64(f.EncryptionTrailerSize)
f.EncryptionTrailerSize = 0
// never sent externally
f.LocalFlags = 0
f.VersionHash = nil
f.InodeChangeNs = 0
return f
}
func (s *indexHandler) String() string {
return fmt.Sprintf("indexHandler@%p for %s to %s at %s", s, s.folder, s.conn.DeviceID().Short(), s.conn)
}
type indexHandlerRegistry struct {
evLogger events.Logger
conn protocol.Connection
downloads *deviceDownloadState
indexHandlers *serviceMap[string, *indexHandler]
startInfos map[string]*clusterConfigDeviceInfo
folderStates map[string]*indexHandlerFolderState
mut sync.Mutex
}
type indexHandlerFolderState struct {
cfg config.FolderConfiguration
fset *db.FileSet
runner service
}
func newIndexHandlerRegistry(conn protocol.Connection, downloads *deviceDownloadState, evLogger events.Logger) *indexHandlerRegistry {
r := &indexHandlerRegistry{
evLogger: evLogger,
conn: conn,
downloads: downloads,
indexHandlers: newServiceMap[string, *indexHandler](evLogger),
startInfos: make(map[string]*clusterConfigDeviceInfo),
folderStates: make(map[string]*indexHandlerFolderState),
mut: sync.Mutex{},
}
return r
}
func (r *indexHandlerRegistry) String() string {
return fmt.Sprintf("indexHandlerRegistry/%v", r.conn.DeviceID().Short())
}
func (r *indexHandlerRegistry) Serve(ctx context.Context) error {
// Running the index handler registry means running the individual index
// handler children.
return r.indexHandlers.Serve(ctx)
}
func (r *indexHandlerRegistry) startLocked(folder config.FolderConfiguration, fset *db.FileSet, runner service, startInfo *clusterConfigDeviceInfo) {
r.indexHandlers.RemoveAndWait(folder.ID, 0)
delete(r.startInfos, folder.ID)
is := newIndexHandler(r.conn, r.downloads, folder, fset, runner, startInfo, r.evLogger)
r.indexHandlers.Add(folder.ID, is)
// This new connection might help us get in sync.
runner.SchedulePull()
}
// AddIndexInfo starts an index handler for given folder, unless it is paused.
// If it is paused, the given startInfo is stored to start the sender once the
// folder is resumed.
// If an index handler is already running, it will be stopped first.
func (r *indexHandlerRegistry) AddIndexInfo(folder string, startInfo *clusterConfigDeviceInfo) {
r.mut.Lock()
defer r.mut.Unlock()
if r.indexHandlers.RemoveAndWait(folder, 0) == nil {
l.Debugf("Removed index sender for device %v and folder %v due to added pending", r.conn.DeviceID().Short(), folder)
}
folderState, ok := r.folderStates[folder]
if !ok {
l.Debugf("Pending index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
r.startInfos[folder] = startInfo
return
}
r.startLocked(folderState.cfg, folderState.fset, folderState.runner, startInfo)
}
// Remove stops a running index handler or removes one pending to be started.
// It is a noop if the folder isn't known.
func (r *indexHandlerRegistry) Remove(folder string) {
r.mut.Lock()
defer r.mut.Unlock()
l.Debugf("Removing index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
r.indexHandlers.RemoveAndWait(folder, 0)
delete(r.startInfos, folder)
l.Debugf("Removed index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
}
// RemoveAllExcept stops all running index handlers and removes those pending to be started,
// except mentioned ones.
// It is a noop if the folder isn't known.
func (r *indexHandlerRegistry) RemoveAllExcept(except map[string]remoteFolderState) {
r.mut.Lock()
defer r.mut.Unlock()
r.indexHandlers.Each(func(folder string, is *indexHandler) error {
if _, ok := except[folder]; !ok {
r.indexHandlers.RemoveAndWait(folder, 0)
l.Debugf("Removed index handler for device %v and folder %v (removeAllExcept)", r.conn.DeviceID().Short(), folder)
}
return nil
})
for folder := range r.startInfos {
if _, ok := except[folder]; !ok {
delete(r.startInfos, folder)
l.Debugf("Removed pending index handler for device %v and folder %v (removeAllExcept)", r.conn.DeviceID().Short(), folder)
}
}
}
// RegisterFolderState must be called whenever something about the folder
// changes. The exception being if the folder is removed entirely, then call
// Remove. The fset and runner arguments may be nil, if given folder is paused.
func (r *indexHandlerRegistry) RegisterFolderState(folder config.FolderConfiguration, fset *db.FileSet, runner service) {
if !folder.SharedWith(r.conn.DeviceID()) {
r.Remove(folder.ID)
return
}
r.mut.Lock()
if folder.Paused {
r.folderPausedLocked(folder.ID)
} else {
r.folderRunningLocked(folder, fset, runner)
}
r.mut.Unlock()
}
// folderPausedLocked stops a running index handler.
// It is a noop if the folder isn't known or has not been started yet.
func (r *indexHandlerRegistry) folderPausedLocked(folder string) {
l.Debugf("Pausing index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
delete(r.folderStates, folder)
if is, ok := r.indexHandlers.Get(folder); ok {
is.pause()
l.Debugf("Paused index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
} else {
l.Debugf("No index handler for device %v and folder %v to pause", r.conn.DeviceID().Short(), folder)
}
}
// folderRunningLocked resumes an already running index handler or starts it, if it
// was added while paused.
// It is a noop if the folder isn't known.
func (r *indexHandlerRegistry) folderRunningLocked(folder config.FolderConfiguration, fset *db.FileSet, runner service) {
r.folderStates[folder.ID] = &indexHandlerFolderState{
cfg: folder,
fset: fset,
runner: runner,
}
is, isOk := r.indexHandlers.Get(folder.ID)
if info, ok := r.startInfos[folder.ID]; ok {
if isOk {
r.indexHandlers.RemoveAndWait(folder.ID, 0)
l.Debugf("Removed index handler for device %v and folder %v in resume", r.conn.DeviceID().Short(), folder.ID)
}
r.startLocked(folder, fset, runner, info)
delete(r.startInfos, folder.ID)
l.Debugf("Started index handler for device %v and folder %v in resume", r.conn.DeviceID().Short(), folder.ID)
} else if isOk {
l.Debugf("Resuming index handler for device %v and folder %v", r.conn.DeviceID().Short(), folder)
is.resume(fset, runner)
} else {
l.Debugf("Not resuming index handler for device %v and folder %v as none is paused and there is no start info", r.conn.DeviceID().Short(), folder.ID)
}
}
func (r *indexHandlerRegistry) ReceiveIndex(folder string, fs []protocol.FileInfo, update bool, op string) error {
r.mut.Lock()
defer r.mut.Unlock()
is, isOk := r.indexHandlers.Get(folder)
if !isOk {
l.Infof("%v for nonexistent or paused folder %q", op, folder)
return fmt.Errorf("%s: %w", folder, ErrFolderMissing)
}
return is.receive(fs, update, op)
}
// makeForgetUpdate takes an index update and constructs a download progress update
// causing to forget any progress for files which we've just been sent.
func makeForgetUpdate(files []protocol.FileInfo) []protocol.FileDownloadProgressUpdate {
updates := make([]protocol.FileDownloadProgressUpdate, 0, len(files))
for _, file := range files {
if file.IsSymlink() || file.IsDirectory() || file.IsDeleted() {
continue
}
updates = append(updates, protocol.FileDownloadProgressUpdate{
Name: file.Name,
Version: file.Version,
UpdateType: protocol.FileDownloadProgressUpdateTypeForget,
})
}
return updates
}