mirror of
https://github.com/1f349/dendrite.git
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244 lines
8.4 KiB
Go
244 lines
8.4 KiB
Go
// Copyright 2017 Vector Creations Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sync
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import (
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"context"
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"sync"
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"time"
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"github.com/matrix-org/dendrite/syncapi/storage"
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"github.com/matrix-org/dendrite/syncapi/types"
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"github.com/matrix-org/gomatrixserverlib"
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log "github.com/sirupsen/logrus"
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)
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// Notifier will wake up sleeping requests when there is some new data.
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// It does not tell requests what that data is, only the stream position which
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// they can use to get at it. This is done to prevent races whereby we tell the caller
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// the event, but the token has already advanced by the time they fetch it, resulting
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// in missed events.
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type Notifier struct {
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// A map of RoomID => Set<UserID> : Must only be accessed by the OnNewEvent goroutine
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roomIDToJoinedUsers map[string]userIDSet
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// Protects currPos and userStreams.
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streamLock *sync.Mutex
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// The latest sync stream position
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currPos types.StreamPosition
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// A map of user_id => UserStream which can be used to wake a given user's /sync request.
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userStreams map[string]*UserStream
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// The last time we cleaned out stale entries from the userStreams map
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lastCleanUpTime time.Time
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}
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// NewNotifier creates a new notifier set to the given stream position.
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// In order for this to be of any use, the Notifier needs to be told all rooms and
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// the joined users within each of them by calling Notifier.Load(*storage.SyncServerDatabase).
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func NewNotifier(pos types.StreamPosition) *Notifier {
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return &Notifier{
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currPos: pos,
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roomIDToJoinedUsers: make(map[string]userIDSet),
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userStreams: make(map[string]*UserStream),
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streamLock: &sync.Mutex{},
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lastCleanUpTime: time.Now(),
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}
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}
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// OnNewEvent is called when a new event is received from the room server. Must only be
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// called from a single goroutine, to avoid races between updates which could set the
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// current position in the stream incorrectly.
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// Can be called either with a *gomatrixserverlib.Event, or with an user ID
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func (n *Notifier) OnNewEvent(ev *gomatrixserverlib.Event, userID string, pos types.StreamPosition) {
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// update the current position then notify relevant /sync streams.
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// This needs to be done PRIOR to waking up users as they will read this value.
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n.streamLock.Lock()
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defer n.streamLock.Unlock()
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n.currPos = pos
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n.removeEmptyUserStreams()
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if ev != nil {
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// Map this event's room_id to a list of joined users, and wake them up.
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userIDs := n.joinedUsers(ev.RoomID())
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// If this is an invite, also add in the invitee to this list.
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if ev.Type() == "m.room.member" && ev.StateKey() != nil {
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targetUserID := *ev.StateKey()
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membership, err := ev.Membership()
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if err != nil {
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log.WithError(err).WithField("event_id", ev.EventID()).Errorf(
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"Notifier.OnNewEvent: Failed to unmarshal member event",
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)
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} else {
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// Keep the joined user map up-to-date
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switch membership {
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case "invite":
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userIDs = append(userIDs, targetUserID)
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case "join":
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// Manually append the new user's ID so they get notified
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// along all members in the room
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userIDs = append(userIDs, targetUserID)
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n.addJoinedUser(ev.RoomID(), targetUserID)
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case "leave":
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fallthrough
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case "ban":
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n.removeJoinedUser(ev.RoomID(), targetUserID)
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}
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}
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}
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for _, toNotifyUserID := range userIDs {
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n.wakeupUser(toNotifyUserID, pos)
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}
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} else if len(userID) > 0 {
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n.wakeupUser(userID, pos)
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}
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}
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// GetListener returns a UserStreamListener that can be used to wait for
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// updates for a user. Must be closed.
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// notify for anything before sincePos
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func (n *Notifier) GetListener(req syncRequest) UserStreamListener {
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// Do what synapse does: https://github.com/matrix-org/synapse/blob/v0.20.0/synapse/notifier.py#L298
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// - Bucket request into a lookup map keyed off a list of joined room IDs and separately a user ID
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// - Incoming events wake requests for a matching room ID
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// - Incoming events wake requests for a matching user ID (needed for invites)
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// TODO: v1 /events 'peeking' has an 'explicit room ID' which is also tracked,
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// but given we don't do /events, let's pretend it doesn't exist.
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n.streamLock.Lock()
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defer n.streamLock.Unlock()
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n.removeEmptyUserStreams()
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return n.fetchUserStream(req.device.UserID, true).GetListener(req.ctx)
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}
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// Load the membership states required to notify users correctly.
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func (n *Notifier) Load(ctx context.Context, db *storage.SyncServerDatabase) error {
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roomToUsers, err := db.AllJoinedUsersInRooms(ctx)
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if err != nil {
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return err
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}
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n.setUsersJoinedToRooms(roomToUsers)
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return nil
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}
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// CurrentPosition returns the current stream position
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func (n *Notifier) CurrentPosition() types.StreamPosition {
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return n.currPos
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}
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// setUsersJoinedToRooms marks the given users as 'joined' to the given rooms, such that new events from
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// these rooms will wake the given users /sync requests. This should be called prior to ANY calls to
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// OnNewEvent (eg on startup) to prevent racing.
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func (n *Notifier) setUsersJoinedToRooms(roomIDToUserIDs map[string][]string) {
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// This is just the bulk form of addJoinedUser
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for roomID, userIDs := range roomIDToUserIDs {
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if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
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n.roomIDToJoinedUsers[roomID] = make(userIDSet)
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}
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for _, userID := range userIDs {
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n.roomIDToJoinedUsers[roomID].add(userID)
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}
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}
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}
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func (n *Notifier) wakeupUser(userID string, newPos types.StreamPosition) {
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stream := n.fetchUserStream(userID, false)
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if stream == nil {
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return
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}
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stream.Broadcast(newPos) // wakeup all goroutines Wait()ing on this stream
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}
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// fetchUserStream retrieves a stream unique to the given user. If makeIfNotExists is true,
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// a stream will be made for this user if one doesn't exist and it will be returned. This
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// function does not wait for data to be available on the stream.
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func (n *Notifier) fetchUserStream(userID string, makeIfNotExists bool) *UserStream {
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stream, ok := n.userStreams[userID]
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if !ok && makeIfNotExists {
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// TODO: Unbounded growth of streams (1 per user)
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stream = NewUserStream(userID, n.currPos)
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n.userStreams[userID] = stream
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}
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return stream
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}
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// Not thread-safe: must be called on the OnNewEvent goroutine only
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func (n *Notifier) addJoinedUser(roomID, userID string) {
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if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
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n.roomIDToJoinedUsers[roomID] = make(userIDSet)
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}
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n.roomIDToJoinedUsers[roomID].add(userID)
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}
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// Not thread-safe: must be called on the OnNewEvent goroutine only
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func (n *Notifier) removeJoinedUser(roomID, userID string) {
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if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
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n.roomIDToJoinedUsers[roomID] = make(userIDSet)
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}
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n.roomIDToJoinedUsers[roomID].remove(userID)
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}
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// Not thread-safe: must be called on the OnNewEvent goroutine only
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func (n *Notifier) joinedUsers(roomID string) (userIDs []string) {
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if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
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return
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}
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return n.roomIDToJoinedUsers[roomID].values()
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}
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// removeEmptyUserStreams iterates through the user stream map and removes any
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// that have been empty for a certain amount of time. This is a crude way of
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// ensuring that the userStreams map doesn't grow forver.
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// This should be called when the notifier gets called for whatever reason,
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// the function itself is responsible for ensuring it doesn't iterate too
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// often.
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// NB: Callers should have locked the mutex before calling this function.
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func (n *Notifier) removeEmptyUserStreams() {
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// Only clean up now and again
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now := time.Now()
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if n.lastCleanUpTime.Add(time.Minute).After(now) {
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return
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}
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n.lastCleanUpTime = now
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deleteBefore := now.Add(-5 * time.Minute)
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for key, value := range n.userStreams {
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if value.TimeOfLastNonEmpty().Before(deleteBefore) {
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delete(n.userStreams, key)
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}
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}
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}
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// A string set, mainly existing for improving clarity of structs in this file.
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type userIDSet map[string]bool
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func (s userIDSet) add(str string) {
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s[str] = true
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}
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func (s userIDSet) remove(str string) {
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delete(s, str)
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}
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func (s userIDSet) values() (vals []string) {
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for str := range s {
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vals = append(vals, str)
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}
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return
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}
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