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dendrite/federationsender/consumers/roomserver.go

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// Copyright 2017 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package consumers
import (
"context"
"encoding/json"
"fmt"
"github.com/Shopify/sarama"
"github.com/matrix-org/dendrite/federationsender/queue"
"github.com/matrix-org/dendrite/federationsender/storage"
"github.com/matrix-org/dendrite/federationsender/types"
"github.com/matrix-org/dendrite/internal"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/setup/config"
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"github.com/matrix-org/dendrite/setup/jetstream"
"github.com/matrix-org/dendrite/setup/process"
"github.com/matrix-org/gomatrixserverlib"
log "github.com/sirupsen/logrus"
)
// OutputRoomEventConsumer consumes events that originated in the room server.
type OutputRoomEventConsumer struct {
cfg *config.FederationSender
rsAPI api.RoomserverInternalAPI
rsConsumer *internal.ContinualConsumer
db storage.Database
queues *queue.OutgoingQueues
}
// NewOutputRoomEventConsumer creates a new OutputRoomEventConsumer. Call Start() to begin consuming from room servers.
func NewOutputRoomEventConsumer(
process *process.ProcessContext,
cfg *config.FederationSender,
kafkaConsumer sarama.Consumer,
queues *queue.OutgoingQueues,
store storage.Database,
rsAPI api.RoomserverInternalAPI,
) *OutputRoomEventConsumer {
consumer := internal.ContinualConsumer{
Process: process,
ComponentName: "federationsender/roomserver",
Topic: string(cfg.Matrix.JetStream.TopicFor(jetstream.OutputRoomEvent)),
Consumer: kafkaConsumer,
PartitionStore: store,
}
s := &OutputRoomEventConsumer{
cfg: cfg,
rsConsumer: &consumer,
db: store,
queues: queues,
rsAPI: rsAPI,
}
consumer.ProcessMessage = s.onMessage
return s
}
// Start consuming from room servers
func (s *OutputRoomEventConsumer) Start() error {
return s.rsConsumer.Start()
}
// onMessage is called when the federation server receives a new event from the room server output log.
// It is unsafe to call this with messages for the same room in multiple gorountines
// because updates it will likely fail with a types.EventIDMismatchError when it
// realises that it cannot update the room state using the deltas.
func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
// Parse out the event JSON
var output api.OutputEvent
if err := json.Unmarshal(msg.Value, &output); err != nil {
// If the message was invalid, log it and move on to the next message in the stream
log.WithError(err).Errorf("roomserver output log: message parse failure")
return nil
}
switch output.Type {
case api.OutputTypeNewRoomEvent:
ev := output.NewRoomEvent.Event
if output.NewRoomEvent.RewritesState {
if err := s.db.PurgeRoomState(context.TODO(), ev.RoomID()); err != nil {
return fmt.Errorf("s.db.PurgeRoom: %w", err)
}
}
if err := s.processMessage(*output.NewRoomEvent); err != nil {
switch err.(type) {
case *queue.ErrorFederationDisabled:
log.WithField("error", output.Type).Info(
err.Error(),
)
default:
// panic rather than continue with an inconsistent database
log.WithFields(log.Fields{
"event_id": ev.EventID(),
"event": string(ev.JSON()),
"add": output.NewRoomEvent.AddsStateEventIDs,
"del": output.NewRoomEvent.RemovesStateEventIDs,
log.ErrorKey: err,
}).Panicf("roomserver output log: write room event failure")
}
return nil
}
Peeking over federation via MSC2444 (#1391) * a very very WIP first cut of peeking via MSC2753. doesn't yet compile or work. needs to actually add the peeking block into the sync response. checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it. * make PeekingDeviceSet private * add server_name param * blind stab at adding a `peek` section to /sync * make it build * make it launch * add peeking to getResponseWithPDUsForCompleteSync * cancel any peeks when we join a room * spell out how to runoutside of docker if you want speed * fix SQL * remove unnecessary txn for SelectPeeks * fix s/join/peek/ cargocult fail * HACK: Track goroutine IDs to determine when we write by the wrong thread To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe` * Track partition offsets and only log unsafe for non-selects * Put redactions in the writer goroutine * Update filters on writer goroutine * wrap peek storage in goid hack * use exclusive writer, and MarkPeeksAsOld more efficiently * don't log ascii in binary at sql trace... * strip out empty roomd deltas * re-add txn to SelectPeeks * re-add accidentally deleted field * reject peeks for non-worldreadable rooms * move perform_peek * fix package * correctly refactor perform_peek * WIP of implementing MSC2444 * typo * Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking" This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c. * (almost) make it build * clean up bad merge * support SendEventWithState with optional event * fix build & lint * fix build & lint * reinstate federated peeks in the roomserver (doh) * fix sql thinko * todo for authenticating state returned by /peek * support returning current state from QueryStateAndAuthChain * handle SS /peek * reimplement SS /peek to prod the RS to tell the FS about the peek * rename RemotePeeks as OutboundPeeks * rename remote_peeks_table as outbound_peeks_table * add perform_handle_remote_peek.go * flesh out federation doc * add inbound peeks table and hook it up * rename ambiguous RemotePeek as InboundPeek * rename FSAPI's PerformPeek as PerformOutboundPeek * setup inbound peeks db correctly * fix api.SendEventWithState with no event * track latestevent on /peek * go fmt * document the peek send stream race better * fix SendEventWithRewrite not to bail if handed a non-state event * add fixme * switch SS /peek to use SendEventWithRewrite * fix comment * use reverse topo ordering to find latest extrem * support postgres for federated peeking * go fmt * back out bogus go.mod change * Fix performOutboundPeekUsingServer * Fix getAuthChain -> GetAuthChain * Fix build issues * Fix build again * Fix getAuthChain -> GetAuthChain * Don't repeat outbound peeks for the same room ID to the same servers * Fix lint * Don't omitempty to appease sytest Co-authored-by: Kegan Dougal <kegan@matrix.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-01-22 15:55:08 +01:00
case api.OutputTypeNewInboundPeek:
if err := s.processInboundPeek(*output.NewInboundPeek); err != nil {
log.WithFields(log.Fields{
"event": output.NewInboundPeek,
log.ErrorKey: err,
}).Panicf("roomserver output log: remote peek event failure")
return nil
}
default:
log.WithField("type", output.Type).Debug(
"roomserver output log: ignoring unknown output type",
)
return nil
}
return nil
}
Peeking over federation via MSC2444 (#1391) * a very very WIP first cut of peeking via MSC2753. doesn't yet compile or work. needs to actually add the peeking block into the sync response. checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it. * make PeekingDeviceSet private * add server_name param * blind stab at adding a `peek` section to /sync * make it build * make it launch * add peeking to getResponseWithPDUsForCompleteSync * cancel any peeks when we join a room * spell out how to runoutside of docker if you want speed * fix SQL * remove unnecessary txn for SelectPeeks * fix s/join/peek/ cargocult fail * HACK: Track goroutine IDs to determine when we write by the wrong thread To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe` * Track partition offsets and only log unsafe for non-selects * Put redactions in the writer goroutine * Update filters on writer goroutine * wrap peek storage in goid hack * use exclusive writer, and MarkPeeksAsOld more efficiently * don't log ascii in binary at sql trace... * strip out empty roomd deltas * re-add txn to SelectPeeks * re-add accidentally deleted field * reject peeks for non-worldreadable rooms * move perform_peek * fix package * correctly refactor perform_peek * WIP of implementing MSC2444 * typo * Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking" This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c. * (almost) make it build * clean up bad merge * support SendEventWithState with optional event * fix build & lint * fix build & lint * reinstate federated peeks in the roomserver (doh) * fix sql thinko * todo for authenticating state returned by /peek * support returning current state from QueryStateAndAuthChain * handle SS /peek * reimplement SS /peek to prod the RS to tell the FS about the peek * rename RemotePeeks as OutboundPeeks * rename remote_peeks_table as outbound_peeks_table * add perform_handle_remote_peek.go * flesh out federation doc * add inbound peeks table and hook it up * rename ambiguous RemotePeek as InboundPeek * rename FSAPI's PerformPeek as PerformOutboundPeek * setup inbound peeks db correctly * fix api.SendEventWithState with no event * track latestevent on /peek * go fmt * document the peek send stream race better * fix SendEventWithRewrite not to bail if handed a non-state event * add fixme * switch SS /peek to use SendEventWithRewrite * fix comment * use reverse topo ordering to find latest extrem * support postgres for federated peeking * go fmt * back out bogus go.mod change * Fix performOutboundPeekUsingServer * Fix getAuthChain -> GetAuthChain * Fix build issues * Fix build again * Fix getAuthChain -> GetAuthChain * Don't repeat outbound peeks for the same room ID to the same servers * Fix lint * Don't omitempty to appease sytest Co-authored-by: Kegan Dougal <kegan@matrix.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-01-22 15:55:08 +01:00
// processInboundPeek starts tracking a new federated inbound peek (replacing the existing one if any)
// causing the federationsender to start sending messages to the peeking server
func (s *OutputRoomEventConsumer) processInboundPeek(orp api.OutputNewInboundPeek) error {
// FIXME: there's a race here - we should start /sending new peeked events
// atomically after the orp.LatestEventID to ensure there are no gaps between
// the peek beginning and the send stream beginning.
//
// We probably need to track orp.LatestEventID on the inbound peek, but it's
// unclear how we then use that to prevent the race when we start the send
// stream.
//
// This is making the tests flakey.
return s.db.AddInboundPeek(context.TODO(), orp.ServerName, orp.RoomID, orp.PeekID, orp.RenewalInterval)
}
// processMessage updates the list of currently joined hosts in the room
// and then sends the event to the hosts that were joined before the event.
func (s *OutputRoomEventConsumer) processMessage(ore api.OutputNewRoomEvent) error {
addsJoinedHosts, err := joinedHostsFromEvents(gomatrixserverlib.UnwrapEventHeaders(ore.AddsState()))
if err != nil {
return err
}
// Update our copy of the current state.
// We keep a copy of the current state because the state at each event is
// expressed as a delta against the current state.
2017-10-06 15:13:53 +02:00
// TODO(#290): handle EventIDMismatchError and recover the current state by
// talking to the roomserver
oldJoinedHosts, err := s.db.UpdateRoom(
context.TODO(),
ore.Event.RoomID(),
ore.LastSentEventID,
ore.Event.EventID(),
addsJoinedHosts,
ore.RemovesStateEventIDs,
)
if err != nil {
return err
}
if oldJoinedHosts == nil {
// This means that there is nothing to update as this is a duplicate
// message.
// This can happen if dendrite crashed between reading the message and
// persisting the stream position.
return nil
}
if ore.SendAsServer == api.DoNotSendToOtherServers {
// Ignore event that we don't need to send anywhere.
return nil
}
// Work out which hosts were joined at the event itself.
joinedHostsAtEvent, err := s.joinedHostsAtEvent(ore, oldJoinedHosts)
if err != nil {
return err
}
Peeking over federation via MSC2444 (#1391) * a very very WIP first cut of peeking via MSC2753. doesn't yet compile or work. needs to actually add the peeking block into the sync response. checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it. * make PeekingDeviceSet private * add server_name param * blind stab at adding a `peek` section to /sync * make it build * make it launch * add peeking to getResponseWithPDUsForCompleteSync * cancel any peeks when we join a room * spell out how to runoutside of docker if you want speed * fix SQL * remove unnecessary txn for SelectPeeks * fix s/join/peek/ cargocult fail * HACK: Track goroutine IDs to determine when we write by the wrong thread To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe` * Track partition offsets and only log unsafe for non-selects * Put redactions in the writer goroutine * Update filters on writer goroutine * wrap peek storage in goid hack * use exclusive writer, and MarkPeeksAsOld more efficiently * don't log ascii in binary at sql trace... * strip out empty roomd deltas * re-add txn to SelectPeeks * re-add accidentally deleted field * reject peeks for non-worldreadable rooms * move perform_peek * fix package * correctly refactor perform_peek * WIP of implementing MSC2444 * typo * Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking" This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c. * (almost) make it build * clean up bad merge * support SendEventWithState with optional event * fix build & lint * fix build & lint * reinstate federated peeks in the roomserver (doh) * fix sql thinko * todo for authenticating state returned by /peek * support returning current state from QueryStateAndAuthChain * handle SS /peek * reimplement SS /peek to prod the RS to tell the FS about the peek * rename RemotePeeks as OutboundPeeks * rename remote_peeks_table as outbound_peeks_table * add perform_handle_remote_peek.go * flesh out federation doc * add inbound peeks table and hook it up * rename ambiguous RemotePeek as InboundPeek * rename FSAPI's PerformPeek as PerformOutboundPeek * setup inbound peeks db correctly * fix api.SendEventWithState with no event * track latestevent on /peek * go fmt * document the peek send stream race better * fix SendEventWithRewrite not to bail if handed a non-state event * add fixme * switch SS /peek to use SendEventWithRewrite * fix comment * use reverse topo ordering to find latest extrem * support postgres for federated peeking * go fmt * back out bogus go.mod change * Fix performOutboundPeekUsingServer * Fix getAuthChain -> GetAuthChain * Fix build issues * Fix build again * Fix getAuthChain -> GetAuthChain * Don't repeat outbound peeks for the same room ID to the same servers * Fix lint * Don't omitempty to appease sytest Co-authored-by: Kegan Dougal <kegan@matrix.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-01-22 15:55:08 +01:00
// TODO: do housekeeping to evict unrenewed peeking hosts
// TODO: implement query to let the fedapi check whether a given peek is live or not
// Send the event.
return s.queues.SendEvent(
ore.Event, gomatrixserverlib.ServerName(ore.SendAsServer), joinedHostsAtEvent,
)
}
// joinedHostsAtEvent works out a list of matrix servers that were joined to
Peeking over federation via MSC2444 (#1391) * a very very WIP first cut of peeking via MSC2753. doesn't yet compile or work. needs to actually add the peeking block into the sync response. checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it. * make PeekingDeviceSet private * add server_name param * blind stab at adding a `peek` section to /sync * make it build * make it launch * add peeking to getResponseWithPDUsForCompleteSync * cancel any peeks when we join a room * spell out how to runoutside of docker if you want speed * fix SQL * remove unnecessary txn for SelectPeeks * fix s/join/peek/ cargocult fail * HACK: Track goroutine IDs to determine when we write by the wrong thread To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe` * Track partition offsets and only log unsafe for non-selects * Put redactions in the writer goroutine * Update filters on writer goroutine * wrap peek storage in goid hack * use exclusive writer, and MarkPeeksAsOld more efficiently * don't log ascii in binary at sql trace... * strip out empty roomd deltas * re-add txn to SelectPeeks * re-add accidentally deleted field * reject peeks for non-worldreadable rooms * move perform_peek * fix package * correctly refactor perform_peek * WIP of implementing MSC2444 * typo * Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking" This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c. * (almost) make it build * clean up bad merge * support SendEventWithState with optional event * fix build & lint * fix build & lint * reinstate federated peeks in the roomserver (doh) * fix sql thinko * todo for authenticating state returned by /peek * support returning current state from QueryStateAndAuthChain * handle SS /peek * reimplement SS /peek to prod the RS to tell the FS about the peek * rename RemotePeeks as OutboundPeeks * rename remote_peeks_table as outbound_peeks_table * add perform_handle_remote_peek.go * flesh out federation doc * add inbound peeks table and hook it up * rename ambiguous RemotePeek as InboundPeek * rename FSAPI's PerformPeek as PerformOutboundPeek * setup inbound peeks db correctly * fix api.SendEventWithState with no event * track latestevent on /peek * go fmt * document the peek send stream race better * fix SendEventWithRewrite not to bail if handed a non-state event * add fixme * switch SS /peek to use SendEventWithRewrite * fix comment * use reverse topo ordering to find latest extrem * support postgres for federated peeking * go fmt * back out bogus go.mod change * Fix performOutboundPeekUsingServer * Fix getAuthChain -> GetAuthChain * Fix build issues * Fix build again * Fix getAuthChain -> GetAuthChain * Don't repeat outbound peeks for the same room ID to the same servers * Fix lint * Don't omitempty to appease sytest Co-authored-by: Kegan Dougal <kegan@matrix.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-01-22 15:55:08 +01:00
// the room at the event (including peeking ones)
// It is important to use the state at the event for sending messages because:
// 1) We shouldn't send messages to servers that weren't in the room.
// 2) If a server is kicked from the rooms it should still be told about the
// kick event,
// Usually the list can be calculated locally, but sometimes it will need fetch
// events from the room server.
// Returns an error if there was a problem talking to the room server.
func (s *OutputRoomEventConsumer) joinedHostsAtEvent(
ore api.OutputNewRoomEvent, oldJoinedHosts []types.JoinedHost,
) ([]gomatrixserverlib.ServerName, error) {
// Combine the delta into a single delta so that the adds and removes can
// cancel each other out. This should reduce the number of times we need
// to fetch a state event from the room server.
combinedAdds, combinedRemoves := combineDeltas(
ore.AddsStateEventIDs, ore.RemovesStateEventIDs,
ore.StateBeforeAddsEventIDs, ore.StateBeforeRemovesEventIDs,
)
combinedAddsEvents, err := s.lookupStateEvents(combinedAdds, ore.Event.Event)
if err != nil {
return nil, err
}
combinedAddsJoinedHosts, err := joinedHostsFromEvents(combinedAddsEvents)
if err != nil {
return nil, err
}
removed := map[string]bool{}
for _, eventID := range combinedRemoves {
removed[eventID] = true
}
joined := map[gomatrixserverlib.ServerName]bool{}
for _, joinedHost := range oldJoinedHosts {
if removed[joinedHost.MemberEventID] {
// This m.room.member event is part of the current state of the
// room, but not part of the state at the event we are processing
// Therefore we can't use it to tell whether the server was in
// the room at the event.
continue
}
joined[joinedHost.ServerName] = true
}
for _, joinedHost := range combinedAddsJoinedHosts {
// This m.room.member event was part of the state of the room at the
// event, but isn't part of the current state of the room now.
joined[joinedHost.ServerName] = true
}
Peeking over federation via MSC2444 (#1391) * a very very WIP first cut of peeking via MSC2753. doesn't yet compile or work. needs to actually add the peeking block into the sync response. checking in now before it gets any bigger, and to gather any initial feedback on the vague shape of it. * make PeekingDeviceSet private * add server_name param * blind stab at adding a `peek` section to /sync * make it build * make it launch * add peeking to getResponseWithPDUsForCompleteSync * cancel any peeks when we join a room * spell out how to runoutside of docker if you want speed * fix SQL * remove unnecessary txn for SelectPeeks * fix s/join/peek/ cargocult fail * HACK: Track goroutine IDs to determine when we write by the wrong thread To use: set `DENDRITE_TRACE_SQL=1` then grep for `unsafe` * Track partition offsets and only log unsafe for non-selects * Put redactions in the writer goroutine * Update filters on writer goroutine * wrap peek storage in goid hack * use exclusive writer, and MarkPeeksAsOld more efficiently * don't log ascii in binary at sql trace... * strip out empty roomd deltas * re-add txn to SelectPeeks * re-add accidentally deleted field * reject peeks for non-worldreadable rooms * move perform_peek * fix package * correctly refactor perform_peek * WIP of implementing MSC2444 * typo * Revert "Merge branch 'kegan/HACK-goid-sqlite-db-is-locked' into matthew/peeking" This reverts commit 3cebd8dbfbccdf82b7930b7b6eda92095ca6ef41, reversing changes made to ed4b3a58a7855acc43530693cc855b439edf9c7c. * (almost) make it build * clean up bad merge * support SendEventWithState with optional event * fix build & lint * fix build & lint * reinstate federated peeks in the roomserver (doh) * fix sql thinko * todo for authenticating state returned by /peek * support returning current state from QueryStateAndAuthChain * handle SS /peek * reimplement SS /peek to prod the RS to tell the FS about the peek * rename RemotePeeks as OutboundPeeks * rename remote_peeks_table as outbound_peeks_table * add perform_handle_remote_peek.go * flesh out federation doc * add inbound peeks table and hook it up * rename ambiguous RemotePeek as InboundPeek * rename FSAPI's PerformPeek as PerformOutboundPeek * setup inbound peeks db correctly * fix api.SendEventWithState with no event * track latestevent on /peek * go fmt * document the peek send stream race better * fix SendEventWithRewrite not to bail if handed a non-state event * add fixme * switch SS /peek to use SendEventWithRewrite * fix comment * use reverse topo ordering to find latest extrem * support postgres for federated peeking * go fmt * back out bogus go.mod change * Fix performOutboundPeekUsingServer * Fix getAuthChain -> GetAuthChain * Fix build issues * Fix build again * Fix getAuthChain -> GetAuthChain * Don't repeat outbound peeks for the same room ID to the same servers * Fix lint * Don't omitempty to appease sytest Co-authored-by: Kegan Dougal <kegan@matrix.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-01-22 15:55:08 +01:00
// handle peeking hosts
inboundPeeks, err := s.db.GetInboundPeeks(context.TODO(), ore.Event.Event.RoomID())
if err != nil {
return nil, err
}
for _, inboundPeek := range inboundPeeks {
joined[inboundPeek.ServerName] = true
}
var result []gomatrixserverlib.ServerName
for serverName, include := range joined {
if include {
result = append(result, serverName)
}
}
return result, nil
}
// joinedHostsFromEvents turns a list of state events into a list of joined hosts.
// This errors if one of the events was invalid.
// It should be impossible for an invalid event to get this far in the pipeline.
func joinedHostsFromEvents(evs []*gomatrixserverlib.Event) ([]types.JoinedHost, error) {
var joinedHosts []types.JoinedHost
for _, ev := range evs {
if ev.Type() != "m.room.member" || ev.StateKey() == nil {
continue
}
membership, err := ev.Membership()
if err != nil {
return nil, err
}
if membership != gomatrixserverlib.Join {
continue
}
_, serverName, err := gomatrixserverlib.SplitID('@', *ev.StateKey())
if err != nil {
return nil, err
}
joinedHosts = append(joinedHosts, types.JoinedHost{
MemberEventID: ev.EventID(), ServerName: serverName,
})
}
return joinedHosts, nil
}
// combineDeltas combines two deltas into a single delta.
// Assumes that the order of operations is add(1), remove(1), add(2), remove(2).
// Removes duplicate entries and redundant operations from each delta.
func combineDeltas(adds1, removes1, adds2, removes2 []string) (adds, removes []string) {
addSet := map[string]bool{}
removeSet := map[string]bool{}
// combine processes each unique value in a list.
// If the value is in the removeFrom set then it is removed from that set.
// Otherwise it is added to the addTo set.
combine := func(values []string, removeFrom, addTo map[string]bool) {
processed := map[string]bool{}
for _, value := range values {
if processed[value] {
continue
}
processed[value] = true
if removeFrom[value] {
delete(removeFrom, value)
} else {
addTo[value] = true
}
}
}
combine(adds1, nil, addSet)
combine(removes1, addSet, removeSet)
combine(adds2, removeSet, addSet)
combine(removes2, addSet, removeSet)
for value := range addSet {
adds = append(adds, value)
}
for value := range removeSet {
removes = append(removes, value)
}
return
}
// lookupStateEvents looks up the state events that are added by a new event.
func (s *OutputRoomEventConsumer) lookupStateEvents(
addsStateEventIDs []string, event *gomatrixserverlib.Event,
) ([]*gomatrixserverlib.Event, error) {
// Fast path if there aren't any new state events.
if len(addsStateEventIDs) == 0 {
return nil, nil
}
// Fast path if the only state event added is the event itself.
if len(addsStateEventIDs) == 1 && addsStateEventIDs[0] == event.EventID() {
return []*gomatrixserverlib.Event{event}, nil
}
missing := addsStateEventIDs
var result []*gomatrixserverlib.Event
// Check if event itself is being added.
for _, eventID := range missing {
if eventID == event.EventID() {
result = append(result, event)
break
}
}
missing = missingEventsFrom(result, addsStateEventIDs)
if len(missing) == 0 {
return result, nil
}
// At this point the missing events are neither the event itself nor are
// they present in our local database. Our only option is to fetch them
// from the roomserver using the query API.
eventReq := api.QueryEventsByIDRequest{EventIDs: missing}
var eventResp api.QueryEventsByIDResponse
if err := s.rsAPI.QueryEventsByID(context.TODO(), &eventReq, &eventResp); err != nil {
return nil, err
}
for _, headeredEvent := range eventResp.Events {
result = append(result, headeredEvent.Event)
}
missing = missingEventsFrom(result, addsStateEventIDs)
if len(missing) != 0 {
return nil, fmt.Errorf(
"missing %d state events IDs at event %q", len(missing), event.EventID(),
)
}
return result, nil
}
func missingEventsFrom(events []*gomatrixserverlib.Event, required []string) []string {
have := map[string]bool{}
for _, event := range events {
have[event.EventID()] = true
}
var missing []string
for _, eventID := range required {
if !have[eventID] {
missing = append(missing, eventID)
}
}
return missing
}