dendrite/syncapi/streams/stream_pdu.go

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package streams
import (
"context"
"sync"
"time"
"github.com/matrix-org/dendrite/syncapi/types"
userapi "github.com/matrix-org/dendrite/userapi/api"
"github.com/matrix-org/gomatrixserverlib"
"go.uber.org/atomic"
)
// The max number of per-room goroutines to have running.
// Too high and this will consume lots of CPU, too low and complete
// sync responses will take longer to process.
const PDU_STREAM_WORKERS = 256
// The maximum number of tasks that can be queued in total before
// backpressure will build up and the rests will start to block.
const PDU_STREAM_QUEUESIZE = PDU_STREAM_WORKERS * 8
type PDUStreamProvider struct {
StreamProvider
tasks chan func()
workers atomic.Int32
}
func (p *PDUStreamProvider) worker() {
defer p.workers.Dec()
for {
select {
case f := <-p.tasks:
f()
case <-time.After(time.Second * 10):
return
}
}
}
func (p *PDUStreamProvider) queue(f func()) {
if p.workers.Load() < PDU_STREAM_WORKERS {
p.workers.Inc()
go p.worker()
}
p.tasks <- f
}
func (p *PDUStreamProvider) Setup() {
p.StreamProvider.Setup()
p.tasks = make(chan func(), PDU_STREAM_QUEUESIZE)
p.latestMutex.Lock()
defer p.latestMutex.Unlock()
id, err := p.DB.MaxStreamPositionForPDUs(context.Background())
if err != nil {
panic(err)
}
p.latest = id
}
func (p *PDUStreamProvider) CompleteSync(
ctx context.Context,
req *types.SyncRequest,
) types.StreamPosition {
from := types.StreamPosition(0)
to := p.LatestPosition(ctx)
// Get the current sync position which we will base the sync response on.
// For complete syncs, we want to start at the most recent events and work
// backwards, so that we show the most recent events in the room.
r := types.Range{
From: to,
To: 0,
Backwards: true,
}
// Extract room state and recent events for all rooms the user is joined to.
joinedRoomIDs, err := p.DB.RoomIDsWithMembership(ctx, req.Device.UserID, gomatrixserverlib.Join)
if err != nil {
req.Log.WithError(err).Error("p.DB.RoomIDsWithMembership failed")
return from
}
stateFilter := req.Filter.Room.State
eventFilter := req.Filter.Room.Timeline
// Build up a /sync response. Add joined rooms.
var reqMutex sync.Mutex
var reqWaitGroup sync.WaitGroup
reqWaitGroup.Add(len(joinedRoomIDs))
for _, room := range joinedRoomIDs {
roomID := room
p.queue(func() {
defer reqWaitGroup.Done()
var jr *types.JoinResponse
jr, err = p.getJoinResponseForCompleteSync(
ctx, roomID, r, &stateFilter, &eventFilter, req.WantFullState, req.Device,
)
if err != nil {
req.Log.WithError(err).Error("p.getJoinResponseForCompleteSync failed")
return
}
reqMutex.Lock()
defer reqMutex.Unlock()
req.Response.Rooms.Join[roomID] = *jr
req.Rooms[roomID] = gomatrixserverlib.Join
})
}
reqWaitGroup.Wait()
// Add peeked rooms.
peeks, err := p.DB.PeeksInRange(ctx, req.Device.UserID, req.Device.ID, r)
if err != nil {
req.Log.WithError(err).Error("p.DB.PeeksInRange failed")
return from
}
for _, peek := range peeks {
if !peek.Deleted {
var jr *types.JoinResponse
jr, err = p.getJoinResponseForCompleteSync(
ctx, peek.RoomID, r, &stateFilter, &eventFilter, req.WantFullState, req.Device,
)
if err != nil {
req.Log.WithError(err).Error("p.getJoinResponseForCompleteSync failed")
return from
}
req.Response.Rooms.Peek[peek.RoomID] = *jr
}
}
return to
}
func (p *PDUStreamProvider) IncrementalSync(
ctx context.Context,
req *types.SyncRequest,
from, to types.StreamPosition,
) (newPos types.StreamPosition) {
r := types.Range{
From: from,
To: to,
Backwards: from > to,
}
var err error
var stateDeltas []types.StateDelta
var joinedRooms []string
stateFilter := req.Filter.Room.State
eventFilter := req.Filter.Room.Timeline
if req.WantFullState {
if stateDeltas, joinedRooms, err = p.DB.GetStateDeltasForFullStateSync(ctx, req.Device, r, req.Device.UserID, &stateFilter); err != nil {
req.Log.WithError(err).Error("p.DB.GetStateDeltasForFullStateSync failed")
return
}
} else {
if stateDeltas, joinedRooms, err = p.DB.GetStateDeltas(ctx, req.Device, r, req.Device.UserID, &stateFilter); err != nil {
req.Log.WithError(err).Error("p.DB.GetStateDeltas failed")
return
}
}
for _, roomID := range joinedRooms {
req.Rooms[roomID] = gomatrixserverlib.Join
}
if len(stateDeltas) == 0 {
return to
}
newPos = from
for _, delta := range stateDeltas {
var pos types.StreamPosition
if pos, err = p.addRoomDeltaToResponse(ctx, req.Device, r, delta, &eventFilter, req.Response); err != nil {
req.Log.WithError(err).Error("d.addRoomDeltaToResponse failed")
return to
}
switch {
case r.Backwards && pos < newPos:
fallthrough
case !r.Backwards && pos > newPos:
newPos = pos
}
}
return newPos
}
func (p *PDUStreamProvider) addRoomDeltaToResponse(
ctx context.Context,
device *userapi.Device,
r types.Range,
delta types.StateDelta,
eventFilter *gomatrixserverlib.RoomEventFilter,
res *types.Response,
) (types.StreamPosition, error) {
if delta.MembershipPos > 0 && delta.Membership == gomatrixserverlib.Leave {
// make sure we don't leak recent events after the leave event.
// TODO: History visibility makes this somewhat complex to handle correctly. For example:
// TODO: This doesn't work for join -> leave in a single /sync request (see events prior to join).
// TODO: This will fail on join -> leave -> sensitive msg -> join -> leave
// in a single /sync request
// This is all "okay" assuming history_visibility == "shared" which it is by default.
r.To = delta.MembershipPos
}
recentStreamEvents, limited, err := p.DB.RecentEvents(
ctx, delta.RoomID, r,
eventFilter, true, true,
)
if err != nil {
return r.From, err
}
recentEvents := p.DB.StreamEventsToEvents(device, recentStreamEvents)
delta.StateEvents = removeDuplicates(delta.StateEvents, recentEvents) // roll back
prevBatch, err := p.DB.GetBackwardTopologyPos(ctx, recentStreamEvents)
if err != nil {
return r.From, err
}
// If we didn't return any events at all then don't bother doing anything else.
if len(recentEvents) == 0 && len(delta.StateEvents) == 0 {
return r.To, nil
}
// Sort the events so that we can pick out the latest events from both sections.
recentEvents = gomatrixserverlib.HeaderedReverseTopologicalOrdering(recentEvents, gomatrixserverlib.TopologicalOrderByPrevEvents)
delta.StateEvents = gomatrixserverlib.HeaderedReverseTopologicalOrdering(delta.StateEvents, gomatrixserverlib.TopologicalOrderByAuthEvents)
// Work out what the highest stream position is for all of the events in this
// room that were returned.
latestPosition := r.To
updateLatestPosition := func(mostRecentEventID string) {
if _, pos, err := p.DB.PositionInTopology(ctx, mostRecentEventID); err == nil {
switch {
case r.Backwards && pos > latestPosition:
fallthrough
case !r.Backwards && pos < latestPosition:
latestPosition = pos
}
}
}
if len(recentEvents) > 0 {
updateLatestPosition(recentEvents[len(recentEvents)-1].EventID())
}
if len(delta.StateEvents) > 0 {
updateLatestPosition(delta.StateEvents[len(delta.StateEvents)-1].EventID())
}
switch delta.Membership {
case gomatrixserverlib.Join:
jr := types.NewJoinResponse()
jr.Timeline.PrevBatch = &prevBatch
jr.Timeline.Events = gomatrixserverlib.HeaderedToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
jr.Timeline.Limited = limited
jr.State.Events = gomatrixserverlib.HeaderedToClientEvents(delta.StateEvents, gomatrixserverlib.FormatSync)
res.Rooms.Join[delta.RoomID] = *jr
case gomatrixserverlib.Peek:
jr := types.NewJoinResponse()
jr.Timeline.PrevBatch = &prevBatch
jr.Timeline.Events = gomatrixserverlib.HeaderedToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
jr.Timeline.Limited = limited
jr.State.Events = gomatrixserverlib.HeaderedToClientEvents(delta.StateEvents, gomatrixserverlib.FormatSync)
res.Rooms.Peek[delta.RoomID] = *jr
case gomatrixserverlib.Leave:
fallthrough // transitions to leave are the same as ban
case gomatrixserverlib.Ban:
// TODO: recentEvents may contain events that this user is not allowed to see because they are
// no longer in the room.
lr := types.NewLeaveResponse()
lr.Timeline.PrevBatch = &prevBatch
lr.Timeline.Events = gomatrixserverlib.HeaderedToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
lr.Timeline.Limited = false // TODO: if len(events) >= numRecents + 1 and then set limited:true
lr.State.Events = gomatrixserverlib.HeaderedToClientEvents(delta.StateEvents, gomatrixserverlib.FormatSync)
res.Rooms.Leave[delta.RoomID] = *lr
}
return latestPosition, nil
}
func (p *PDUStreamProvider) getJoinResponseForCompleteSync(
ctx context.Context,
roomID string,
r types.Range,
stateFilter *gomatrixserverlib.StateFilter,
eventFilter *gomatrixserverlib.RoomEventFilter,
wantFullState bool,
device *userapi.Device,
) (jr *types.JoinResponse, err error) {
// TODO: When filters are added, we may need to call this multiple times to get enough events.
// See: https://github.com/matrix-org/synapse/blob/v0.19.3/synapse/handlers/sync.py#L316
recentStreamEvents, limited, err := p.DB.RecentEvents(
ctx, roomID, r, eventFilter, true, true,
)
if err != nil {
return
}
// TODO FIXME: We don't fully implement history visibility yet. To avoid leaking events which the
// user shouldn't see, we check the recent events and remove any prior to the join event of the user
// which is equiv to history_visibility: joined
joinEventIndex := -1
for i := len(recentStreamEvents) - 1; i >= 0; i-- {
ev := recentStreamEvents[i]
if ev.Type() == gomatrixserverlib.MRoomMember && ev.StateKeyEquals(device.UserID) {
membership, _ := ev.Membership()
if membership == "join" {
joinEventIndex = i
if i > 0 {
// the create event happens before the first join, so we should cut it at that point instead
if recentStreamEvents[i-1].Type() == gomatrixserverlib.MRoomCreate && recentStreamEvents[i-1].StateKeyEquals("") {
joinEventIndex = i - 1
break
}
}
break
}
}
}
if joinEventIndex != -1 {
// cut all events earlier than the join (but not the join itself)
recentStreamEvents = recentStreamEvents[joinEventIndex:]
limited = false // so clients know not to try to backpaginate
}
// Work our way through the timeline events and pick out the event IDs
// of any state events that appear in the timeline. We'll specifically
// exclude them at the next step, so that we don't get duplicate state
// events in both `recentStreamEvents` and `stateEvents`.
var excludingEventIDs []string
if !wantFullState {
excludingEventIDs = make([]string, 0, len(recentStreamEvents))
for _, event := range recentStreamEvents {
if event.StateKey() != nil {
excludingEventIDs = append(excludingEventIDs, event.EventID())
}
}
}
stateEvents, err := p.DB.CurrentState(ctx, roomID, stateFilter, excludingEventIDs)
if err != nil {
return
}
// Retrieve the backward topology position, i.e. the position of the
// oldest event in the room's topology.
var prevBatch *types.TopologyToken
if len(recentStreamEvents) > 0 {
var backwardTopologyPos, backwardStreamPos types.StreamPosition
backwardTopologyPos, backwardStreamPos, err = p.DB.PositionInTopology(ctx, recentStreamEvents[0].EventID())
if err != nil {
return
}
prevBatch = &types.TopologyToken{
Depth: backwardTopologyPos,
PDUPosition: backwardStreamPos,
}
prevBatch.Decrement()
}
// We don't include a device here as we don't need to send down
// transaction IDs for complete syncs, but we do it anyway because Sytest demands it for:
// "Can sync a room with a message with a transaction id" - which does a complete sync to check.
recentEvents := p.DB.StreamEventsToEvents(device, recentStreamEvents)
stateEvents = removeDuplicates(stateEvents, recentEvents)
jr = types.NewJoinResponse()
jr.Timeline.PrevBatch = prevBatch
jr.Timeline.Events = gomatrixserverlib.HeaderedToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
jr.Timeline.Limited = limited
jr.State.Events = gomatrixserverlib.HeaderedToClientEvents(stateEvents, gomatrixserverlib.FormatSync)
return jr, nil
}
func removeDuplicates(stateEvents, recentEvents []*gomatrixserverlib.HeaderedEvent) []*gomatrixserverlib.HeaderedEvent {
for _, recentEv := range recentEvents {
if recentEv.StateKey() == nil {
continue // not a state event
}
// TODO: This is a linear scan over all the current state events in this room. This will
// be slow for big rooms. We should instead sort the state events by event ID (ORDER BY)
// then do a binary search to find matching events, similar to what roomserver does.
for j := 0; j < len(stateEvents); j++ {
if stateEvents[j].EventID() == recentEv.EventID() {
// overwrite the element to remove with the last element then pop the last element.
// This is orders of magnitude faster than re-slicing, but doesn't preserve ordering
// (we don't care about the order of stateEvents)
stateEvents[j] = stateEvents[len(stateEvents)-1]
stateEvents = stateEvents[:len(stateEvents)-1]
break // there shouldn't be multiple events with the same event ID
}
}
}
return stateEvents
}