syncthing/lib/model/indexsender.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"
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"github.com/thejerf/suture/v4"
"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 indexSender struct {
conn protocol.Connection
folder string
folderIsReceiveEncrypted bool
dev string
fset *db.FileSet
prevSequence int64
evLogger events.Logger
connClosed chan struct{}
done chan struct{}
token suture.ServiceToken
pauseChan chan struct{}
resumeChan chan *db.FileSet
}
func (s *indexSender) Serve(ctx context.Context) (err error) {
l.Debugf("Starting indexSender for %s to %s at %s (slv=%d)", s.folder, s.conn.ID(), s.conn, s.prevSequence)
defer func() {
close(s.done)
err = svcutil.NoRestartErr(err)
l.Debugf("Exiting indexSender for %s to %s at %s: %v", s.folder, s.conn.ID(), s.conn, err)
}()
// We need to send one index, regardless of whether there is something to send or not
err = s.sendIndexTo(ctx)
// 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()
paused := false
evChan := sub.C()
ticker := time.NewTicker(time.Minute)
defer ticker.Stop()
for err == nil {
select {
case <-ctx.Done():
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return ctx.Err()
case <-s.connClosed:
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return nil
default:
}
// 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 s.fset.Sequence(protocol.LocalDeviceID) <= s.prevSequence {
select {
case <-ctx.Done():
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return ctx.Err()
case <-s.connClosed:
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return nil
case <-evChan:
case <-ticker.C:
case <-s.pauseChan:
paused = true
case s.fset = <-s.resumeChan:
paused = false
}
continue
}
if !paused {
err = s.sendIndexTo(ctx)
}
// 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.
time.Sleep(250 * time.Millisecond)
}
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return err
}
func (s *indexSender) resume(fset *db.FileSet) {
select {
case <-s.done:
case s.resumeChan <- fset:
}
}
func (s *indexSender) pause() {
select {
case <-s.done:
case s.pauseChan <- struct{}{}:
}
}
// sendIndexTo sends file infos with a sequence number higher than prevSequence and
// returns the highest sent sequence number.
func (s *indexSender) sendIndexTo(ctx context.Context) error {
initial := s.prevSequence == 0
batch := newFileInfoBatch(nil)
batch.flushFn = func(fs []protocol.FileInfo) error {
l.Debugf("%v: Sending %d files (<%d bytes)", s, len(batch.infos), 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 := s.fset.Snapshot()
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 := s.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
}
// 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{}
}
// never sent externally
f.LocalFlags = 0
f.VersionHash = nil
previousWasDelete = f.IsDeleted()
batch.append(f)
return true
})
if err != nil {
return err
}
err = batch.flush()
// True if there was nothing to be sent
if f.Sequence == 0 {
return err
}
s.prevSequence = f.Sequence
return err
}
func (s *indexSender) String() string {
return fmt.Sprintf("indexSender@%p for %s to %s at %s", s, s.folder, s.conn.ID(), s.conn)
}
type indexSenderRegistry struct {
deviceID protocol.DeviceID
sup *suture.Supervisor
evLogger events.Logger
conn protocol.Connection
closed chan struct{}
indexSenders map[string]*indexSender
startInfos map[string]*indexSenderStartInfo
mut sync.Mutex
}
func newIndexSenderRegistry(conn protocol.Connection, closed chan struct{}, sup *suture.Supervisor, evLogger events.Logger) *indexSenderRegistry {
return &indexSenderRegistry{
deviceID: conn.ID(),
conn: conn,
closed: closed,
sup: sup,
evLogger: evLogger,
indexSenders: make(map[string]*indexSender),
startInfos: make(map[string]*indexSenderStartInfo),
mut: sync.Mutex{},
}
}
// add starts an index sender for given folder.
// If an index sender is already running, it will be stopped first.
func (r *indexSenderRegistry) add(folder config.FolderConfiguration, fset *db.FileSet, startInfo *indexSenderStartInfo) {
r.mut.Lock()
r.addLocked(folder, fset, startInfo)
r.mut.Unlock()
}
func (r *indexSenderRegistry) addLocked(folder config.FolderConfiguration, fset *db.FileSet, startInfo *indexSenderStartInfo) {
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", r.deviceID, folder.Description())
startSequence = 0
} else {
l.Debugf("Device %v folder %s is delta index compatible (mlv=%d)", r.deviceID, 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)", r.deviceID, folder.Description(), startInfo.local.IndexID, myIndexID)
startSequence = 0
} else {
l.Debugf("Device %v folder %s has no index ID for us", r.deviceID, 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(r.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", r.deviceID, folder.Description())
fset.Drop(r.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)", r.deviceID, folder.Description(), startInfo.remote.IndexID)
fset.Drop(r.deviceID)
fset.SetIndexID(r.deviceID, startInfo.remote.IndexID)
}
if is, ok := r.indexSenders[folder.ID]; ok {
r.sup.RemoveAndWait(is.token, 0)
delete(r.indexSenders, folder.ID)
}
if _, ok := r.startInfos[folder.ID]; ok {
delete(r.startInfos, folder.ID)
}
is := &indexSender{
conn: r.conn,
connClosed: r.closed,
done: make(chan struct{}),
folder: folder.ID,
folderIsReceiveEncrypted: folder.Type == config.FolderTypeReceiveEncrypted,
fset: fset,
prevSequence: startSequence,
evLogger: r.evLogger,
pauseChan: make(chan struct{}),
resumeChan: make(chan *db.FileSet),
}
is.token = r.sup.Add(is)
r.indexSenders[folder.ID] = is
}
// addPending stores the given info to start an index sender once resume is called
// for this folder.
// If an index sender is already running, it will be stopped.
func (r *indexSenderRegistry) addPending(folder config.FolderConfiguration, startInfo *indexSenderStartInfo) {
r.mut.Lock()
defer r.mut.Unlock()
if is, ok := r.indexSenders[folder.ID]; ok {
r.sup.RemoveAndWait(is.token, 0)
delete(r.indexSenders, folder.ID)
}
r.startInfos[folder.ID] = startInfo
}
// remove stops a running index sender or removes one pending to be started.
// It is a noop if the folder isn't known.
func (r *indexSenderRegistry) remove(folder string) {
r.mut.Lock()
defer r.mut.Unlock()
if is, ok := r.indexSenders[folder]; ok {
r.sup.RemoveAndWait(is.token, 0)
delete(r.indexSenders, folder)
}
delete(r.startInfos, folder)
}
// removeAllExcept stops all running index senders and removes those pending to be started,
// except mentioned ones.
// It is a noop if the folder isn't known.
func (r *indexSenderRegistry) removeAllExcept(except map[string]struct{}) {
r.mut.Lock()
defer r.mut.Unlock()
for folder, is := range r.indexSenders {
if _, ok := except[folder]; !ok {
r.sup.RemoveAndWait(is.token, 0)
delete(r.indexSenders, folder)
}
}
for folder := range r.startInfos {
if _, ok := except[folder]; !ok {
delete(r.startInfos, folder)
}
}
}
// pause stops a running index sender.
// It is a noop if the folder isn't known or has not been started yet.
func (r *indexSenderRegistry) pause(folder string) {
r.mut.Lock()
defer r.mut.Unlock()
if is, ok := r.indexSenders[folder]; ok {
is.pause()
}
}
// resume unpauses an already running index sender or starts it, if it was added
// while paused.
// It is a noop if the folder isn't known.
func (r *indexSenderRegistry) resume(folder config.FolderConfiguration, fset *db.FileSet) {
r.mut.Lock()
defer r.mut.Unlock()
is, isOk := r.indexSenders[folder.ID]
if info, ok := r.startInfos[folder.ID]; ok {
if isOk {
r.sup.RemoveAndWait(is.token, 0)
delete(r.indexSenders, folder.ID)
}
r.addLocked(folder, fset, info)
delete(r.startInfos, folder.ID)
} else if isOk {
is.resume(fset)
}
}
type indexSenderStartInfo struct {
local, remote protocol.Device
}