Merge branch 'master' into matthew/peeking-over-fed

CHANGES.md

@@ -1,5 +1,20 @@
 # Changelog
 
+## Dendrite 0.3.3 (2020-12-09)
+
+### Features
+
+* Federation sender should now use considerably less CPU cycles and RAM when sending events into large rooms
+* The roomserver now uses considerably less CPU cycles by not calculating event IDs so often
+* Experimental support for [MSC2836](https://github.com/matrix-org/matrix-doc/pull/2836) (threading) has been merged
+* Dendrite will no longer hold federation HTTP connections open unnecessarily, which should help to reduce ambient CPU/RAM usage and hold fewer long-term file descriptors
+
+### Fixes
+
+* A bug in the latest event updater has been fixed, which should prevent the roomserver from losing forward extremities in some rare cases
+* A panic has been fixed when federation is disabled (contributed by [kraem](https://github.com/kraem))
+* The response format of the `/joined_members` endpoint has been fixed (contributed by [alexkursell](https://github.com/alexkursell))
+
 ## Dendrite 0.3.2 (2020-12-02)
 
 ### Features

README.md

@@ -8,7 +8,6 @@ It intends to provide an **efficient**, **reliable** and **scalable** alternativ
    a [brand new Go test suite](https://github.com/matrix-org/complement).
  - Scalable: can run on multiple machines and eventually scale to massive homeserver deployments.
 
-
 As of October 2020, Dendrite has now entered **beta** which means:
 - Dendrite is ready for early adopters. We recommend running in Monolith mode with a PostgreSQL database.
 - Dendrite has periodic semver releases. We intend to release new versions as we land significant features.
@@ -24,7 +23,7 @@ This does not mean:
 Currently, we expect Dendrite to function well for small (10s/100s of users) homeserver deployments as well as P2P Matrix nodes in-browser or on mobile devices.
 In the future, we will be able to scale up to gigantic servers (equivalent to matrix.org) via polylith mode. 
 
-Join us in:
+If you have further questions, please take a look at [our FAQ](docs/FAQ.md) or join us in:
 
 - **[#dendrite:matrix.org](https://matrix.to/#/#dendrite:matrix.org)** - General chat about the Dendrite project, for users and server admins alike
 - **[#dendrite-dev:matrix.org](https://matrix.to/#/#dendrite-dev:matrix.org)** - The place for developers, where all Dendrite development discussion happens

build/scripts/find-lint.sh

@@ -8,7 +8,7 @@
 # - `DENDRITE_LINT_CONCURRENCY` - number of concurrent linters to run,
 #   golangci-lint defaults this to NumCPU
 # - `GOGC` - how often to perform garbage collection during golangci-lint runs.
-#   Essentially a ratio of memory/speed. See https://github.com/golangci/golangci-lint#memory-usage-of-golangci-lint
+#   Essentially a ratio of memory/speed. See https://golangci-lint.run/usage/performance/#memory-usage
 #   for more info.
 
 

cmd/dendrite-demo-libp2p/main.go

@@ -36,6 +36,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver"
 	"github.com/matrix-org/dendrite/setup"
 	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/setup/mscs"
 	"github.com/matrix-org/dendrite/signingkeyserver"
 	"github.com/matrix-org/dendrite/userapi"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -130,6 +131,8 @@ func main() {
 	cfg.AppServiceAPI.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-appservice.db", *instanceName))
 	cfg.Global.Kafka.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-naffka.db", *instanceName))
 	cfg.KeyServer.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-e2ekey.db", *instanceName))
+	cfg.MSCs.MSCs = []string{"msc2836"}
+	cfg.MSCs.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-mscs.db", *instanceName))
 	if err = cfg.Derive(); err != nil {
 		panic(err)
 	}
@@ -190,6 +193,9 @@ func main() {
 		base.Base.PublicKeyAPIMux,
 		base.Base.PublicMediaAPIMux,
 	)
+	if err := mscs.Enable(&base.Base, &monolith); err != nil {
+		logrus.WithError(err).Fatalf("Failed to enable MSCs")
+	}
 
 	httpRouter := mux.NewRouter().SkipClean(true).UseEncodedPath()
 	httpRouter.PathPrefix(httputil.InternalPathPrefix).Handler(base.Base.InternalAPIMux)

cmd/dendrite-demo-yggdrasil/main.go

@@ -39,6 +39,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver"
 	"github.com/matrix-org/dendrite/setup"
 	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/setup/mscs"
 	"github.com/matrix-org/dendrite/userapi"
 	"github.com/matrix-org/gomatrixserverlib"
 
@@ -83,6 +84,8 @@ func main() {
 	cfg.FederationSender.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-federationsender.db", *instanceName))
 	cfg.AppServiceAPI.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-appservice.db", *instanceName))
 	cfg.Global.Kafka.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-naffka.db", *instanceName))
+	cfg.MSCs.MSCs = []string{"msc2836"}
+	cfg.MSCs.Database.ConnectionString = config.DataSource(fmt.Sprintf("file:%s-mscs.db", *instanceName))
 	if err = cfg.Derive(); err != nil {
 		panic(err)
 	}
@@ -151,6 +154,9 @@ func main() {
 		base.PublicKeyAPIMux,
 		base.PublicMediaAPIMux,
 	)
+	if err := mscs.Enable(base, &monolith); err != nil {
+		logrus.WithError(err).Fatalf("Failed to enable MSCs")
+	}
 
 	httpRouter := mux.NewRouter().SkipClean(true).UseEncodedPath()
 	httpRouter.PathPrefix(httputil.InternalPathPrefix).Handler(base.InternalAPIMux)

cmd/generate-config/main.go

@@ -63,6 +63,8 @@ func main() {
 	if *defaultsForCI {
 		cfg.ClientAPI.RateLimiting.Enabled = false
 		cfg.FederationSender.DisableTLSValidation = true
+		cfg.MSCs.MSCs = []string{"msc2836"}
+		cfg.Logging[0].Level = "trace"
 	}
 
 	j, err := yaml.Marshal(cfg)

dendrite-config.yaml

@@ -89,7 +89,7 @@ global:
     # Naffka database options. Not required when using Kafka.
     naffka_database:
       connection_string: file:naffka.db
-      max_open_conns: 100
+      max_open_conns: 10
       max_idle_conns: 2
       conn_max_lifetime: -1
 
@@ -110,7 +110,7 @@ app_service_api:
     connect: http://localhost:7777
   database:
     connection_string: file:appservice.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -185,7 +185,7 @@ federation_sender:
     connect: http://localhost:7775
   database:
     connection_string: file:federationsender.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -211,7 +211,7 @@ key_server:
     connect: http://localhost:7779
   database:
     connection_string: file:keyserver.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -224,7 +224,7 @@ media_api:
     listen: http://[::]:8074
   database:
     connection_string: file:mediaapi.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -260,7 +260,7 @@ room_server:
     connect: http://localhost:7770
   database:
     connection_string: file:roomserver.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -271,7 +271,7 @@ signing_key_server:
     connect: http://localhost:7780
   database:
     connection_string: file:signingkeyserver.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -300,7 +300,7 @@ sync_api:
     listen: http://[::]:8073
   database:
     connection_string: file:syncapi.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 
@@ -316,12 +316,12 @@ user_api:
     connect: http://localhost:7781
   account_database:
     connection_string: file:userapi_accounts.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
   device_database:
     connection_string: file:userapi_devices.db
-    max_open_conns: 100
+    max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
 

docs/CODE_STYLE.md

@@ -2,13 +2,13 @@
 
 In addition to standard Go code style (`gofmt`, `goimports`), we use `golangci-lint`
 to run a number of linters, the exact list can be found under linters in [.golangci.yml](.golangci.yml).
-[Installation](https://github.com/golangci/golangci-lint#install) and [Editor
+[Installation](https://github.com/golangci/golangci-lint#install-golangci-lint) and [Editor
-Integration](https://github.com/golangci/golangci-lint#editor-integration) for
+Integration](https://golangci-lint.run/usage/integrations/#editor-integration) for
 it can be found in the readme of golangci-lint.
 
 For rare cases where a linter is giving a spurious warning, it can be disabled
 for that line or statement using a [comment
-directive](https://github.com/golangci/golangci-lint#nolint), e.g.  `var
+directive](https://golangci-lint.run/usage/false-positives/#nolint), e.g.  `var
 bad_name int //nolint:golint,unused`. This should be used sparingly and only
 when its clear that the lint warning is spurious.
 

docs/CONTRIBUTING.md

@@ -37,7 +37,7 @@ If a job fails, click the "details" button and you should be taken to the job's
 logs.
 
 ![Click the details button on the failing build
-step](docs/images/details-button-location.jpg)
+step](https://raw.githubusercontent.com/matrix-org/dendrite/master/docs/images/details-button-location.jpg)
 
 Scroll down to the failing step and you should see some log output. Scan the
 logs until you find what it's complaining about, fix it, submit a new commit,

docs/FAQ.md

@@ -12,6 +12,10 @@ No, although a good portion of the Matrix specification has been implemented. Mo
 
 No, not at present. There will be in the future when Dendrite reaches version 1.0.
 
+### Should I run a monolith or a polylith deployment?
+
+Monolith deployments are always preferred where possible, and at this time, are far better tested than polylith deployments are. The only reason to consider a polylith deployment is if you wish to run different Dendrite components on separate physical machines.
+
 ### I've installed Dendrite but federation isn't working
 
 Check the [Federation Tester](https://federationtester.matrix.org). You need at least:

federationapi/routing/send_test.go

@@ -9,7 +9,6 @@ import (
 	"time"
 
 	eduAPI "github.com/matrix-org/dendrite/eduserver/api"
-	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/test"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -85,6 +84,7 @@ func (o *testEDUProducer) InputReceiptEvent(
 }
 
 type testRoomserverAPI struct {
+	api.RoomserverInternalAPITrace
 	inputRoomEvents            []api.InputRoomEvent
 	queryMissingAuthPrevEvents func(*api.QueryMissingAuthPrevEventsRequest) api.QueryMissingAuthPrevEventsResponse
 	queryStateAfterEvents      func(*api.QueryStateAfterEventsRequest) api.QueryStateAfterEventsResponse
@@ -92,12 +92,6 @@ type testRoomserverAPI struct {
 	queryLatestEventsAndState  func(*api.QueryLatestEventsAndStateRequest) api.QueryLatestEventsAndStateResponse
 }
 
-func (t *testRoomserverAPI) PerformForget(ctx context.Context, req *api.PerformForgetRequest, resp *api.PerformForgetResponse) error {
-	return nil
-}
-
-func (t *testRoomserverAPI) SetFederationSenderAPI(fsAPI fsAPI.FederationSenderInternalAPI) {}
-
 func (t *testRoomserverAPI) InputRoomEvents(
 	ctx context.Context,
 	request *api.InputRoomEventsRequest,
@@ -109,58 +103,6 @@ func (t *testRoomserverAPI) InputRoomEvents(
 	}
 }
 
-func (t *testRoomserverAPI) PerformInvite(
-	ctx context.Context,
-	req *api.PerformInviteRequest,
-	res *api.PerformInviteResponse,
-) error {
-	return nil
-}
-
-func (t *testRoomserverAPI) PerformJoin(
-	ctx context.Context,
-	req *api.PerformJoinRequest,
-	res *api.PerformJoinResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformPeek(
-	ctx context.Context,
-	req *api.PerformPeekRequest,
-	res *api.PerformPeekResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformUnpeek(
-	ctx context.Context,
-	req *api.PerformUnpeekRequest,
-	res *api.PerformUnpeekResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformPublish(
-	ctx context.Context,
-	req *api.PerformPublishRequest,
-	res *api.PerformPublishResponse,
-) {
-}
-
-func (t *testRoomserverAPI) PerformLeave(
-	ctx context.Context,
-	req *api.PerformLeaveRequest,
-	res *api.PerformLeaveResponse,
-) error {
-	return nil
-}
-
-func (t *testRoomserverAPI) PerformInboundPeek(
-	ctx context.Context,
-	req *api.PerformInboundPeekRequest,
-	res *api.PerformInboundPeekResponse,
-) error {
-	return nil
-}
-
 // Query the latest events and state for a room from the room server.
 func (t *testRoomserverAPI) QueryLatestEventsAndState(
 	ctx context.Context,

federationsender/api/api.go

@@ -21,6 +21,7 @@ type FederationClient interface {
 	QueryKeys(ctx context.Context, s gomatrixserverlib.ServerName, keys map[string][]string) (res gomatrixserverlib.RespQueryKeys, err error)
 	GetEvent(ctx context.Context, s gomatrixserverlib.ServerName, eventID string) (res gomatrixserverlib.Transaction, err error)
 	GetServerKeys(ctx context.Context, matrixServer gomatrixserverlib.ServerName) (gomatrixserverlib.ServerKeys, error)
+	MSC2836EventRelationships(ctx context.Context, dst gomatrixserverlib.ServerName, r gomatrixserverlib.MSC2836EventRelationshipsRequest, roomVersion gomatrixserverlib.RoomVersion) (res gomatrixserverlib.MSC2836EventRelationshipsResponse, err error)
 	LookupServerKeys(ctx context.Context, s gomatrixserverlib.ServerName, keyRequests map[gomatrixserverlib.PublicKeyLookupRequest]gomatrixserverlib.Timestamp) ([]gomatrixserverlib.ServerKeys, error)
 }
 

federationsender/consumers/roomserver.go

@@ -94,13 +94,20 @@ func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
 		}
 
 		if err := s.processMessage(*output.NewRoomEvent); err != nil {
-			// panic rather than continue with an inconsistent database
+			switch err.(type) {
-			log.WithFields(log.Fields{
+			case *queue.ErrorFederationDisabled:
-				"event":      string(ev.JSON()),
+				log.WithField("error", output.Type).Info(
-				"add":        output.NewRoomEvent.AddsStateEventIDs,
+					err.Error(),
-				"del":        output.NewRoomEvent.RemovesStateEventIDs,
+				)
-				log.ErrorKey: err,
+			default:
-			}).Panicf("roomserver output log: write room event failure")
+				// panic rather than continue with an inconsistent database
+				log.WithFields(log.Fields{
+					"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
 		}
 	case api.OutputTypeNewInboundPeek:

federationsender/federationsender.go

@@ -46,7 +46,7 @@ func NewInternalAPI(
 ) api.FederationSenderInternalAPI {
 	cfg := &base.Cfg.FederationSender
 
-	federationSenderDB, err := storage.NewDatabase(&cfg.Database)
+	federationSenderDB, err := storage.NewDatabase(&cfg.Database, base.Caches)
 	if err != nil {
 		logrus.WithError(err).Panic("failed to connect to federation sender db")
 	}

federationsender/internal/api.go

@@ -229,3 +229,18 @@ func (a *FederationSenderInternalAPI) LookupServerKeys(
 	}
 	return ires.([]gomatrixserverlib.ServerKeys), nil
 }
+
+func (a *FederationSenderInternalAPI) MSC2836EventRelationships(
+	ctx context.Context, s gomatrixserverlib.ServerName, r gomatrixserverlib.MSC2836EventRelationshipsRequest,
+	roomVersion gomatrixserverlib.RoomVersion,
+) (res gomatrixserverlib.MSC2836EventRelationshipsResponse, err error) {
+	ctx, cancel := context.WithTimeout(ctx, time.Minute)
+	defer cancel()
+	ires, err := a.doRequest(s, func() (interface{}, error) {
+		return a.federation.MSC2836EventRelationships(ctx, s, r, roomVersion)
+	})
+	if err != nil {
+		return res, err
+	}
+	return ires.(gomatrixserverlib.MSC2836EventRelationshipsResponse), nil
+}

federationsender/inthttp/client.go

@@ -24,15 +24,16 @@ const (
 	FederationSenderPerformServersAlivePath           = "/federationsender/performServersAlive"
 	FederationSenderPerformBroadcastEDUPath           = "/federationsender/performBroadcastEDU"
 
-	FederationSenderGetUserDevicesPath   = "/federationsender/client/getUserDevices"
+	FederationSenderGetUserDevicesPath     = "/federationsender/client/getUserDevices"
-	FederationSenderClaimKeysPath        = "/federationsender/client/claimKeys"
+	FederationSenderClaimKeysPath          = "/federationsender/client/claimKeys"
-	FederationSenderQueryKeysPath        = "/federationsender/client/queryKeys"
+	FederationSenderQueryKeysPath          = "/federationsender/client/queryKeys"
-	FederationSenderBackfillPath         = "/federationsender/client/backfill"
+	FederationSenderBackfillPath           = "/federationsender/client/backfill"
-	FederationSenderLookupStatePath      = "/federationsender/client/lookupState"
+	FederationSenderLookupStatePath        = "/federationsender/client/lookupState"
-	FederationSenderLookupStateIDsPath   = "/federationsender/client/lookupStateIDs"
+	FederationSenderLookupStateIDsPath     = "/federationsender/client/lookupStateIDs"
-	FederationSenderGetEventPath         = "/federationsender/client/getEvent"
+	FederationSenderGetEventPath           = "/federationsender/client/getEvent"
-	FederationSenderGetServerKeysPath    = "/federationsender/client/getServerKeys"
+	FederationSenderGetServerKeysPath      = "/federationsender/client/getServerKeys"
-	FederationSenderLookupServerKeysPath = "/federationsender/client/lookupServerKeys"
+	FederationSenderLookupServerKeysPath   = "/federationsender/client/lookupServerKeys"
+	FederationSenderEventRelationshipsPath = "/federationsender/client/msc2836eventRelationships"
 )
 
 // NewFederationSenderClient creates a FederationSenderInternalAPI implemented by talking to a HTTP POST API.
@@ -430,3 +431,35 @@ func (h *httpFederationSenderInternalAPI) LookupServerKeys(
 	}
 	return response.ServerKeys, nil
 }
+
+type eventRelationships struct {
+	S       gomatrixserverlib.ServerName
+	Req     gomatrixserverlib.MSC2836EventRelationshipsRequest
+	RoomVer gomatrixserverlib.RoomVersion
+	Res     gomatrixserverlib.MSC2836EventRelationshipsResponse
+	Err     *api.FederationClientError
+}
+
+func (h *httpFederationSenderInternalAPI) MSC2836EventRelationships(
+	ctx context.Context, s gomatrixserverlib.ServerName, r gomatrixserverlib.MSC2836EventRelationshipsRequest,
+	roomVersion gomatrixserverlib.RoomVersion,
+) (res gomatrixserverlib.MSC2836EventRelationshipsResponse, err error) {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "MSC2836EventRelationships")
+	defer span.Finish()
+
+	request := eventRelationships{
+		S:       s,
+		Req:     r,
+		RoomVer: roomVersion,
+	}
+	var response eventRelationships
+	apiURL := h.federationSenderURL + FederationSenderEventRelationshipsPath
+	err = httputil.PostJSON(ctx, span, h.httpClient, apiURL, &request, &response)
+	if err != nil {
+		return res, err
+	}
+	if response.Err != nil {
+		return res, response.Err
+	}
+	return response.Res, nil
+}

federationsender/inthttp/server.go

@@ -307,4 +307,26 @@ func AddRoutes(intAPI api.FederationSenderInternalAPI, internalAPIMux *mux.Route
 			return util.JSONResponse{Code: http.StatusOK, JSON: request}
 		}),
 	)
+	internalAPIMux.Handle(
+		FederationSenderEventRelationshipsPath,
+		httputil.MakeInternalAPI("MSC2836EventRelationships", func(req *http.Request) util.JSONResponse {
+			var request eventRelationships
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			res, err := intAPI.MSC2836EventRelationships(req.Context(), request.S, request.Req, request.RoomVer)
+			if err != nil {
+				ferr, ok := err.(*api.FederationClientError)
+				if ok {
+					request.Err = ferr
+				} else {
+					request.Err = &api.FederationClientError{
+						Err: err.Error(),
+					}
+				}
+			}
+			request.Res = res
+			return util.JSONResponse{Code: http.StatusOK, JSON: request}
+		}),
+	)
 }

federationsender/queue/destinationqueue.go

@@ -35,6 +35,8 @@ import (
 const (
 	maxPDUsPerTransaction = 50
 	maxEDUsPerTransaction = 50
+	maxPDUsInMemory       = 128
+	maxEDUsInMemory       = 128
 	queueIdleTimeout      = time.Second * 30
 )
 
@@ -51,54 +53,56 @@ type destinationQueue struct {
 	destination        gomatrixserverlib.ServerName        // destination of requests
 	running            atomic.Bool                         // is the queue worker running?
 	backingOff         atomic.Bool                         // true if we're backing off
+	overflowed         atomic.Bool                         // the queues exceed maxPDUsInMemory/maxEDUsInMemory, so we should consult the database for more
 	statistics         *statistics.ServerStatistics        // statistics about this remote server
 	transactionIDMutex sync.Mutex                          // protects transactionID
-	transactionID      gomatrixserverlib.TransactionID     // last transaction ID
+	transactionID      gomatrixserverlib.TransactionID     // last transaction ID if retrying, or "" if last txn was successful
-	transactionCount   atomic.Int32                        // how many events in this transaction so far
+	notify             chan struct{}                       // interrupts idle wait pending PDUs/EDUs
-	notifyPDUs         chan bool                           // interrupts idle wait for PDUs
+	pendingPDUs        []*queuedPDU                        // PDUs waiting to be sent
-	notifyEDUs         chan bool                           // interrupts idle wait for EDUs
+	pendingEDUs        []*queuedEDU                        // EDUs waiting to be sent
+	pendingMutex       sync.RWMutex                        // protects pendingPDUs and pendingEDUs
 	interruptBackoff   chan bool                           // interrupts backoff
 }
 
 // Send event adds the event to the pending queue for the destination.
 // If the queue is empty then it starts a background goroutine to
 // start sending events to that destination.
-func (oq *destinationQueue) sendEvent(receipt *shared.Receipt) {
+func (oq *destinationQueue) sendEvent(event *gomatrixserverlib.HeaderedEvent, receipt *shared.Receipt) {
-	// Create a transaction ID. We'll either do this if we don't have
+	if event == nil {
-	// one made up yet, or if we've exceeded the number of maximum
+		log.Errorf("attempt to send nil PDU with destination %q", oq.destination)
-	// events allowed in a single tranaction. We'll reset the counter
+		return
-	// when we do.
-	oq.transactionIDMutex.Lock()
-	if oq.transactionID == "" || oq.transactionCount.Load() >= maxPDUsPerTransaction {
-		now := gomatrixserverlib.AsTimestamp(time.Now())
-		oq.transactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
-		oq.transactionCount.Store(0)
 	}
-	oq.transactionIDMutex.Unlock()
 	// Create a database entry that associates the given PDU NID with
 	// this destination queue. We'll then be able to retrieve the PDU
 	// later.
 	if err := oq.db.AssociatePDUWithDestination(
 		context.TODO(),
-		oq.transactionID, // the current transaction ID
+		"",             // TODO: remove this, as we don't need to persist the transaction ID
-		oq.destination,   // the destination server name
+		oq.destination, // the destination server name
-		receipt,          // NIDs from federationsender_queue_json table
+		receipt,        // NIDs from federationsender_queue_json table
 	); err != nil {
-		log.WithError(err).Errorf("failed to associate PDU receipt %q with destination %q", receipt.String(), oq.destination)
+		log.WithError(err).Errorf("failed to associate PDU %q with destination %q", event.EventID(), oq.destination)
 		return
 	}
-	// We've successfully added a PDU to the transaction so increase
-	// the counter.
-	oq.transactionCount.Add(1)
 	// Check if the destination is blacklisted. If it isn't then wake
 	// up the queue.
 	if !oq.statistics.Blacklisted() {
+		// If there's room in memory to hold the event then add it to the
+		// list.
+		oq.pendingMutex.Lock()
+		if len(oq.pendingPDUs) < maxPDUsInMemory {
+			oq.pendingPDUs = append(oq.pendingPDUs, &queuedPDU{
+				pdu:     event,
+				receipt: receipt,
+			})
+		} else {
+			oq.overflowed.Store(true)
+		}
+		oq.pendingMutex.Unlock()
 		// Wake up the queue if it's asleep.
 		oq.wakeQueueIfNeeded()
-		// If we're blocking on waiting PDUs then tell the queue that we
-		// have work to do.
 		select {
-		case oq.notifyPDUs <- true:
+		case oq.notify <- struct{}{}:
 		default:
 		}
 	}
@@ -107,7 +111,11 @@ func (oq *destinationQueue) sendEvent(receipt *shared.Receipt) {
 // sendEDU adds the EDU event to the pending queue for the destination.
 // If the queue is empty then it starts a background goroutine to
 // start sending events to that destination.
-func (oq *destinationQueue) sendEDU(receipt *shared.Receipt) {
+func (oq *destinationQueue) sendEDU(event *gomatrixserverlib.EDU, receipt *shared.Receipt) {
+	if event == nil {
+		log.Errorf("attempt to send nil EDU with destination %q", oq.destination)
+		return
+	}
 	// Create a database entry that associates the given PDU NID with
 	// this destination queue. We'll then be able to retrieve the PDU
 	// later.
@@ -116,21 +124,28 @@ func (oq *destinationQueue) sendEDU(receipt *shared.Receipt) {
 		oq.destination, // the destination server name
 		receipt,        // NIDs from federationsender_queue_json table
 	); err != nil {
-		log.WithError(err).Errorf("failed to associate EDU receipt %q with destination %q", receipt.String(), oq.destination)
+		log.WithError(err).Errorf("failed to associate EDU with destination %q", oq.destination)
 		return
 	}
-	// We've successfully added an EDU to the transaction so increase
-	// the counter.
-	oq.transactionCount.Add(1)
 	// Check if the destination is blacklisted. If it isn't then wake
 	// up the queue.
 	if !oq.statistics.Blacklisted() {
+		// If there's room in memory to hold the event then add it to the
+		// list.
+		oq.pendingMutex.Lock()
+		if len(oq.pendingEDUs) < maxEDUsInMemory {
+			oq.pendingEDUs = append(oq.pendingEDUs, &queuedEDU{
+				edu:     event,
+				receipt: receipt,
+			})
+		} else {
+			oq.overflowed.Store(true)
+		}
+		oq.pendingMutex.Unlock()
 		// Wake up the queue if it's asleep.
 		oq.wakeQueueIfNeeded()
-		// If we're blocking on waiting EDUs then tell the queue that we
-		// have work to do.
 		select {
-		case oq.notifyEDUs <- true:
+		case oq.notify <- struct{}{}:
 		default:
 		}
 	}
@@ -152,48 +167,71 @@ func (oq *destinationQueue) wakeQueueIfNeeded() {
 	}
 }
 
-// waitForPDUs returns a channel for pending PDUs, which will be
+// getPendingFromDatabase will look at the database and see if
-// used in backgroundSend select. It returns a closed channel if
+// there are any persisted events that haven't been sent to this
-// there is something pending right now, or an open channel if
+// destination yet. If so, they will be queued up.
-// we're waiting for something.
+// nolint:gocyclo
-func (oq *destinationQueue) waitForPDUs() chan bool {
+func (oq *destinationQueue) getPendingFromDatabase() {
-	pendingPDUs, err := oq.db.GetPendingPDUCount(context.TODO(), oq.destination)
+	// Check to see if there's anything to do for this server
-	if err != nil {
+	// in the database.
-		log.WithError(err).Errorf("Failed to get pending PDU count on queue %q", oq.destination)
+	retrieved := false
-	}
+	ctx := context.Background()
-	// If there are PDUs pending right now then we'll return a closed
+	oq.pendingMutex.Lock()
-	// channel. This will mean that the backgroundSend will not block.
+	defer oq.pendingMutex.Unlock()
-	if pendingPDUs > 0 {
-		ch := make(chan bool, 1)
-		close(ch)
-		return ch
-	}
-	// If there are no PDUs pending right now then instead we'll return
-	// the notify channel, so that backgroundSend can pick up normal
-	// notifications from sendEvent.
-	return oq.notifyPDUs
-}
 
-// waitForEDUs returns a channel for pending EDUs, which will be
+	// Take a note of all of the PDUs and EDUs that we already
-// used in backgroundSend select. It returns a closed channel if
+	// have cached. We will index them based on the receipt,
-// there is something pending right now, or an open channel if
+	// which ultimately just contains the index of the PDU/EDU
-// we're waiting for something.
+	// in the database.
-func (oq *destinationQueue) waitForEDUs() chan bool {
+	gotPDUs := map[string]struct{}{}
-	pendingEDUs, err := oq.db.GetPendingEDUCount(context.TODO(), oq.destination)
+	gotEDUs := map[string]struct{}{}
-	if err != nil {
+	for _, pdu := range oq.pendingPDUs {
-		log.WithError(err).Errorf("Failed to get pending EDU count on queue %q", oq.destination)
+		gotPDUs[pdu.receipt.String()] = struct{}{}
 	}
-	// If there are EDUs pending right now then we'll return a closed
+	for _, edu := range oq.pendingEDUs {
-	// channel. This will mean that the backgroundSend will not block.
+		gotEDUs[edu.receipt.String()] = struct{}{}
-	if pendingEDUs > 0 {
+	}
-		ch := make(chan bool, 1)
+
-		close(ch)
+	if pduCapacity := maxPDUsInMemory - len(oq.pendingPDUs); pduCapacity > 0 {
-		return ch
+		// We have room in memory for some PDUs - let's request no more than that.
+		if pdus, err := oq.db.GetPendingPDUs(ctx, oq.destination, pduCapacity); err == nil {
+			for receipt, pdu := range pdus {
+				if _, ok := gotPDUs[receipt.String()]; ok {
+					continue
+				}
+				oq.pendingPDUs = append(oq.pendingPDUs, &queuedPDU{receipt, pdu})
+				retrieved = true
+			}
+		} else {
+			logrus.WithError(err).Errorf("Failed to get pending PDUs for %q", oq.destination)
+		}
+	}
+	if eduCapacity := maxEDUsInMemory - len(oq.pendingEDUs); eduCapacity > 0 {
+		// We have room in memory for some EDUs - let's request no more than that.
+		if edus, err := oq.db.GetPendingEDUs(ctx, oq.destination, eduCapacity); err == nil {
+			for receipt, edu := range edus {
+				if _, ok := gotEDUs[receipt.String()]; ok {
+					continue
+				}
+				oq.pendingEDUs = append(oq.pendingEDUs, &queuedEDU{receipt, edu})
+				retrieved = true
+			}
+		} else {
+			logrus.WithError(err).Errorf("Failed to get pending EDUs for %q", oq.destination)
+		}
+	}
+	// If we've retrieved all of the events from the database with room to spare
+	// in memory then we'll no longer consider this queue to be overflowed.
+	if len(oq.pendingPDUs) < maxPDUsInMemory && len(oq.pendingEDUs) < maxEDUsInMemory {
+		oq.overflowed.Store(false)
+	}
+	// If we've retrieved some events then notify the destination queue goroutine.
+	if retrieved {
+		select {
+		case oq.notify <- struct{}{}:
+		default:
+		}
 	}
-	// If there are no EDUs pending right now then instead we'll return
-	// the notify channel, so that backgroundSend can pick up normal
-	// notifications from sendEvent.
-	return oq.notifyEDUs
 }
 
 // backgroundSend is the worker goroutine for sending events.
@@ -206,25 +244,28 @@ func (oq *destinationQueue) backgroundSend() {
 	}
 	defer oq.running.Store(false)
 
+	// Mark the queue as overflowed, so we will consult the database
+	// to see if there's anything new to send.
+	oq.overflowed.Store(true)
+
 	for {
-		pendingPDUs, pendingEDUs := false, false
+		// If we are overflowing memory and have sent things out to the
+		// database then we can look up what those things are.
+		if oq.overflowed.Load() {
+			oq.getPendingFromDatabase()
+		}
 
 		// If we have nothing to do then wait either for incoming events, or
 		// until we hit an idle timeout.
 		select {
-		case <-oq.waitForPDUs():
+		case <-oq.notify:
-			// We were woken up because there are new PDUs waiting in the
+			// There's work to do, either because getPendingFromDatabase
-			// database.
+			// told us there is, or because a new event has come in via
-			pendingPDUs = true
+			// sendEvent/sendEDU.
-		case <-oq.waitForEDUs():
-			// We were woken up because there are new PDUs waiting in the
-			// database.
-			pendingEDUs = true
 		case <-time.After(queueIdleTimeout):
 			// The worker is idle so stop the goroutine. It'll get
 			// restarted automatically the next time we have an event to
 			// send.
-			log.Tracef("Queue %q has been idle for %s, going to sleep", oq.destination, queueIdleTimeout)
 			return
 		}
 
@@ -237,6 +278,16 @@ func (oq *destinationQueue) backgroundSend() {
 			// has exceeded a maximum allowable value. Clean up the in-memory
 			// buffers at this point. The PDU clean-up is already on a defer.
 			log.Warnf("Blacklisting %q due to exceeding backoff threshold", oq.destination)
+			oq.pendingMutex.Lock()
+			for i := range oq.pendingPDUs {
+				oq.pendingPDUs[i] = nil
+			}
+			for i := range oq.pendingEDUs {
+				oq.pendingEDUs[i] = nil
+			}
+			oq.pendingPDUs = nil
+			oq.pendingEDUs = nil
+			oq.pendingMutex.Unlock()
 			return
 		}
 		if until != nil && until.After(time.Now()) {
@@ -250,18 +301,41 @@ func (oq *destinationQueue) backgroundSend() {
 			}
 		}
 
+		// Work out which PDUs/EDUs to include in the next transaction.
+		oq.pendingMutex.RLock()
+		pduCount := len(oq.pendingPDUs)
+		eduCount := len(oq.pendingEDUs)
+		if pduCount > maxPDUsPerTransaction {
+			pduCount = maxPDUsPerTransaction
+		}
+		if eduCount > maxEDUsPerTransaction {
+			eduCount = maxEDUsPerTransaction
+		}
+		toSendPDUs := oq.pendingPDUs[:pduCount]
+		toSendEDUs := oq.pendingEDUs[:eduCount]
+		oq.pendingMutex.RUnlock()
+
 		// If we have pending PDUs or EDUs then construct a transaction.
-		if pendingPDUs || pendingEDUs {
+		// Try sending the next transaction and see what happens.
-			// Try sending the next transaction and see what happens.
+		transaction, pc, ec, terr := oq.nextTransaction(toSendPDUs, toSendEDUs)
-			transaction, terr := oq.nextTransaction()
+		if terr != nil {
-			if terr != nil {
+			// We failed to send the transaction. Mark it as a failure.
-				// We failed to send the transaction. Mark it as a failure.
+			oq.statistics.Failure()
-				oq.statistics.Failure()
+
-			} else if transaction {
+		} else if transaction {
-				// If we successfully sent the transaction then clear out
+			// If we successfully sent the transaction then clear out
-				// the pending events and EDUs, and wipe our transaction ID.
+			// the pending events and EDUs, and wipe our transaction ID.
-				oq.statistics.Success()
+			oq.statistics.Success()
+			oq.pendingMutex.Lock()
+			for i := range oq.pendingPDUs[:pc] {
+				oq.pendingPDUs[i] = nil
 			}
+			for i := range oq.pendingEDUs[:ec] {
+				oq.pendingEDUs[i] = nil
+			}
+			oq.pendingPDUs = oq.pendingPDUs[pc:]
+			oq.pendingEDUs = oq.pendingEDUs[ec:]
+			oq.pendingMutex.Unlock()
 		}
 	}
 }
@@ -270,16 +344,20 @@ func (oq *destinationQueue) backgroundSend() {
 // queue and sends it. Returns true if a transaction was sent or
 // false otherwise.
 // nolint:gocyclo
-func (oq *destinationQueue) nextTransaction() (bool, error) {
+func (oq *destinationQueue) nextTransaction(
-	// Before we do anything, we need to roll over the transaction
+	pdus []*queuedPDU,
-	// ID that is being used to coalesce events into the next TX.
+	edus []*queuedEDU,
-	// Otherwise it's possible that we'll pick up an incomplete
+) (bool, int, int, error) {
-	// transaction and end up nuking the rest of the events at the
+	// If there's no projected transaction ID then generate one. If
-	// cleanup stage.
+	// the transaction succeeds then we'll set it back to "" so that
+	// we generate a new one next time. If it fails, we'll preserve
+	// it so that we retry with the same transaction ID.
 	oq.transactionIDMutex.Lock()
-	oq.transactionID = ""
+	if oq.transactionID == "" {
+		now := gomatrixserverlib.AsTimestamp(time.Now())
+		oq.transactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
+	}
 	oq.transactionIDMutex.Unlock()
-	oq.transactionCount.Store(0)
 
 	// Create the transaction.
 	t := gomatrixserverlib.Transaction{
@@ -289,58 +367,36 @@ func (oq *destinationQueue) nextTransaction() (bool, error) {
 	t.Origin = oq.origin
 	t.Destination = oq.destination
 	t.OriginServerTS = gomatrixserverlib.AsTimestamp(time.Now())
-
+	t.TransactionID = oq.transactionID
-	// Ask the database for any pending PDUs from the next transaction.
-	// maxPDUsPerTransaction is an upper limit but we probably won't
-	// actually retrieve that many events.
-	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
-	defer cancel()
-	txid, pdus, pduReceipt, err := oq.db.GetNextTransactionPDUs(
-		ctx,                   // context
-		oq.destination,        // server name
-		maxPDUsPerTransaction, // max events to retrieve
-	)
-	if err != nil {
-		log.WithError(err).Errorf("failed to get next transaction PDUs for server %q", oq.destination)
-		return false, fmt.Errorf("oq.db.GetNextTransactionPDUs: %w", err)
-	}
-
-	edus, eduReceipt, err := oq.db.GetNextTransactionEDUs(
-		ctx,                   // context
-		oq.destination,        // server name
-		maxEDUsPerTransaction, // max events to retrieve
-	)
-	if err != nil {
-		log.WithError(err).Errorf("failed to get next transaction EDUs for server %q", oq.destination)
-		return false, fmt.Errorf("oq.db.GetNextTransactionEDUs: %w", err)
-	}
 
 	// If we didn't get anything from the database and there are no
 	// pending EDUs then there's nothing to do - stop here.
 	if len(pdus) == 0 && len(edus) == 0 {
-		return false, nil
+		return false, 0, 0, nil
 	}
 
-	// Pick out the transaction ID from the database. If we didn't
+	var pduReceipts []*shared.Receipt
-	// get a transaction ID (i.e. because there are no PDUs but only
+	var eduReceipts []*shared.Receipt
-	// EDUs) then generate a transaction ID.
-	t.TransactionID = txid
-	if t.TransactionID == "" {
-		now := gomatrixserverlib.AsTimestamp(time.Now())
-		t.TransactionID = gomatrixserverlib.TransactionID(fmt.Sprintf("%d-%d", now, oq.statistics.SuccessCount()))
-	}
 
 	// Go through PDUs that we retrieved from the database, if any,
 	// and add them into the transaction.
 	for _, pdu := range pdus {
+		if pdu == nil || pdu.pdu == nil {
+			continue
+		}
 		// Append the JSON of the event, since this is a json.RawMessage type in the
 		// gomatrixserverlib.Transaction struct
-		t.PDUs = append(t.PDUs, (*pdu).JSON())
+		t.PDUs = append(t.PDUs, pdu.pdu.JSON())
+		pduReceipts = append(pduReceipts, pdu.receipt)
 	}
 
 	// Do the same for pending EDUS in the queue.
 	for _, edu := range edus {
-		t.EDUs = append(t.EDUs, *edu)
+		if edu == nil || edu.edu == nil {
+			continue
+		}
+		t.EDUs = append(t.EDUs, *edu.edu)
+		eduReceipts = append(eduReceipts, edu.receipt)
 	}
 
 	logrus.WithField("server_name", oq.destination).Debugf("Sending transaction %q containing %d PDUs, %d EDUs", t.TransactionID, len(t.PDUs), len(t.EDUs))
@@ -349,34 +405,38 @@ func (oq *destinationQueue) nextTransaction() (bool, error) {
 	// TODO: we should check for 500-ish fails vs 400-ish here,
 	// since we shouldn't queue things indefinitely in response
 	// to a 400-ish error
-	ctx, cancel = context.WithTimeout(context.Background(), time.Minute*5)
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute*5)
 	defer cancel()
-	_, err = oq.client.SendTransaction(ctx, t)
+	_, err := oq.client.SendTransaction(ctx, t)
 	switch err.(type) {
 	case nil:
 		// Clean up the transaction in the database.
-		if pduReceipt != nil {
+		if pduReceipts != nil {
 			//logrus.Infof("Cleaning PDUs %q", pduReceipt.String())
-			if err = oq.db.CleanPDUs(context.Background(), oq.destination, pduReceipt); err != nil {
+			if err = oq.db.CleanPDUs(context.Background(), oq.destination, pduReceipts); err != nil {
-				log.WithError(err).Errorf("failed to clean PDUs %q for server %q", pduReceipt.String(), t.Destination)
+				log.WithError(err).Errorf("Failed to clean PDUs for server %q", t.Destination)
 			}
 		}
-		if eduReceipt != nil {
+		if eduReceipts != nil {
 			//logrus.Infof("Cleaning EDUs %q", eduReceipt.String())
-			if err = oq.db.CleanEDUs(context.Background(), oq.destination, eduReceipt); err != nil {
+			if err = oq.db.CleanEDUs(context.Background(), oq.destination, eduReceipts); err != nil {
-				log.WithError(err).Errorf("failed to clean EDUs %q for server %q", eduReceipt.String(), t.Destination)
+				log.WithError(err).Errorf("Failed to clean EDUs for server %q", t.Destination)
 			}
 		}
-		return true, nil
+		// Reset the transaction ID.
+		oq.transactionIDMutex.Lock()
+		oq.transactionID = ""
+		oq.transactionIDMutex.Unlock()
+		return true, len(t.PDUs), len(t.EDUs), nil
 	case gomatrix.HTTPError:
 		// Report that we failed to send the transaction and we
 		// will retry again, subject to backoff.
-		return false, err
+		return false, 0, 0, err
 	default:
 		log.WithFields(log.Fields{
 			"destination": oq.destination,
 			log.ErrorKey:  err,
-		}).Info("problem sending transaction")
+		}).Infof("Failed to send transaction %q", t.TransactionID)
-		return false, err
+		return false, 0, 0, err
 	}
 }

federationsender/queue/queue.go

@@ -24,6 +24,7 @@ import (
 
 	"github.com/matrix-org/dendrite/federationsender/statistics"
 	"github.com/matrix-org/dendrite/federationsender/storage"
+	"github.com/matrix-org/dendrite/federationsender/storage/shared"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	log "github.com/sirupsen/logrus"
@@ -83,8 +84,8 @@ func NewOutgoingQueues(
 				log.WithError(err).Error("Failed to get EDU server names for destination queue hydration")
 			}
 			for serverName := range serverNames {
-				if !queues.getQueue(serverName).statistics.Blacklisted() {
+				if queue := queues.getQueue(serverName); !queue.statistics.Blacklisted() {
-					queues.getQueue(serverName).wakeQueueIfNeeded()
+					queue.wakeQueueIfNeeded()
 				}
 			}
 		})
@@ -100,6 +101,16 @@ type SigningInfo struct {
 	PrivateKey ed25519.PrivateKey
 }
 
+type queuedPDU struct {
+	receipt *shared.Receipt
+	pdu     *gomatrixserverlib.HeaderedEvent
+}
+
+type queuedEDU struct {
+	receipt *shared.Receipt
+	edu     *gomatrixserverlib.EDU
+}
+
 func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *destinationQueue {
 	oqs.queuesMutex.Lock()
 	defer oqs.queuesMutex.Unlock()
@@ -112,8 +123,7 @@ func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *d
 			destination:      destination,
 			client:           oqs.client,
 			statistics:       oqs.statistics.ForServer(destination),
-			notifyPDUs:       make(chan bool, 1),
+			notify:           make(chan struct{}, 1),
-			notifyEDUs:       make(chan bool, 1),
 			interruptBackoff: make(chan bool),
 			signing:          oqs.signing,
 		}
@@ -122,13 +132,23 @@ func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *d
 	return oq
 }
 
+type ErrorFederationDisabled struct {
+	Message string
+}
+
+func (e *ErrorFederationDisabled) Error() string {
+	return e.Message
+}
+
 // SendEvent sends an event to the destinations
 func (oqs *OutgoingQueues) SendEvent(
 	ev *gomatrixserverlib.HeaderedEvent, origin gomatrixserverlib.ServerName,
 	destinations []gomatrixserverlib.ServerName,
 ) error {
 	if oqs.disabled {
-		return fmt.Errorf("federation is disabled")
+		return &ErrorFederationDisabled{
+			Message: "Federation disabled",
+		}
 	}
 	if origin != oqs.origin {
 		// TODO: Support virtual hosting; gh issue #577.
@@ -178,7 +198,7 @@ func (oqs *OutgoingQueues) SendEvent(
 	}
 
 	for destination := range destmap {
-		oqs.getQueue(destination).sendEvent(nid)
+		oqs.getQueue(destination).sendEvent(ev, nid)
 	}
 
 	return nil
@@ -190,7 +210,9 @@ func (oqs *OutgoingQueues) SendEDU(
 	destinations []gomatrixserverlib.ServerName,
 ) error {
 	if oqs.disabled {
-		return fmt.Errorf("federation is disabled")
+		return &ErrorFederationDisabled{
+			Message: "Federation disabled",
+		}
 	}
 	if origin != oqs.origin {
 		// TODO: Support virtual hosting; gh issue #577.
@@ -246,7 +268,7 @@ func (oqs *OutgoingQueues) SendEDU(
 	}
 
 	for destination := range destmap {
-		oqs.getQueue(destination).sendEDU(nid)
+		oqs.getQueue(destination).sendEDU(e, nid)
 	}
 
 	return nil

federationsender/storage/interface.go

@@ -36,14 +36,14 @@ type Database interface {
 
 	StoreJSON(ctx context.Context, js string) (*shared.Receipt, error)
 
+	GetPendingPDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, limit int) (pdus map[*shared.Receipt]*gomatrixserverlib.HeaderedEvent, err error)
+	GetPendingEDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, limit int) (edus map[*shared.Receipt]*gomatrixserverlib.EDU, err error)
+
 	AssociatePDUWithDestination(ctx context.Context, transactionID gomatrixserverlib.TransactionID, serverName gomatrixserverlib.ServerName, receipt *shared.Receipt) error
 	AssociateEDUWithDestination(ctx context.Context, serverName gomatrixserverlib.ServerName, receipt *shared.Receipt) error
 
-	GetNextTransactionPDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, limit int) (gomatrixserverlib.TransactionID, []*gomatrixserverlib.HeaderedEvent, *shared.Receipt, error)
+	CleanPDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, receipts []*shared.Receipt) error
-	GetNextTransactionEDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, limit int) ([]*gomatrixserverlib.EDU, *shared.Receipt, error)
+	CleanEDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, receipts []*shared.Receipt) error
-
-	CleanPDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, receipt *shared.Receipt) error
-	CleanEDUs(ctx context.Context, serverName gomatrixserverlib.ServerName, receipt *shared.Receipt) error
 
 	GetPendingPDUCount(ctx context.Context, serverName gomatrixserverlib.ServerName) (int64, error)
 	GetPendingEDUCount(ctx context.Context, serverName gomatrixserverlib.ServerName) (int64, error)

federationsender/storage/postgres/queue_pdus_table.go

@@ -45,16 +45,10 @@ const insertQueuePDUSQL = "" +
 const deleteQueuePDUSQL = "" +
 	"DELETE FROM federationsender_queue_pdus WHERE server_name = $1 AND json_nid = ANY($2)"
 
-const selectQueuePDUNextTransactionIDSQL = "" +
+const selectQueuePDUsSQL = "" +
-	"SELECT transaction_id FROM federationsender_queue_pdus" +
-	" WHERE server_name = $1" +
-	" ORDER BY transaction_id ASC" +
-	" LIMIT 1"
-
-const selectQueuePDUsByTransactionSQL = "" +
 	"SELECT json_nid FROM federationsender_queue_pdus" +
-	" WHERE server_name = $1 AND transaction_id = $2" +
+	" WHERE server_name = $1" +
-	" LIMIT $3"
+	" LIMIT $2"
 
 const selectQueuePDUReferenceJSONCountSQL = "" +
 	"SELECT COUNT(*) FROM federationsender_queue_pdus" +
@@ -71,8 +65,7 @@ type queuePDUsStatements struct {
 	db                                   *sql.DB
 	insertQueuePDUStmt                   *sql.Stmt
 	deleteQueuePDUsStmt                  *sql.Stmt
-	selectQueuePDUNextTransactionIDStmt  *sql.Stmt
+	selectQueuePDUsStmt                  *sql.Stmt
-	selectQueuePDUsByTransactionStmt     *sql.Stmt
 	selectQueuePDUReferenceJSONCountStmt *sql.Stmt
 	selectQueuePDUsCountStmt             *sql.Stmt
 	selectQueuePDUServerNamesStmt        *sql.Stmt
@@ -92,10 +85,7 @@ func NewPostgresQueuePDUsTable(db *sql.DB) (s *queuePDUsStatements, err error) {
 	if s.deleteQueuePDUsStmt, err = s.db.Prepare(deleteQueuePDUSQL); err != nil {
 		return
 	}
-	if s.selectQueuePDUNextTransactionIDStmt, err = s.db.Prepare(selectQueuePDUNextTransactionIDSQL); err != nil {
+	if s.selectQueuePDUsStmt, err = s.db.Prepare(selectQueuePDUsSQL); err != nil {
-		return
-	}
-	if s.selectQueuePDUsByTransactionStmt, err = s.db.Prepare(selectQueuePDUsByTransactionSQL); err != nil {
 		return
 	}
 	if s.selectQueuePDUReferenceJSONCountStmt, err = s.db.Prepare(selectQueuePDUReferenceJSONCountSQL); err != nil {
@@ -137,18 +127,6 @@ func (s *queuePDUsStatements) DeleteQueuePDUs(
 	return err
 }
 
-func (s *queuePDUsStatements) SelectQueuePDUNextTransactionID(
-	ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName,
-) (gomatrixserverlib.TransactionID, error) {
-	var transactionID gomatrixserverlib.TransactionID
-	stmt := sqlutil.TxStmt(txn, s.selectQueuePDUNextTransactionIDStmt)
-	err := stmt.QueryRowContext(ctx, serverName).Scan(&transactionID)
-	if err == sql.ErrNoRows {
-		return "", nil
-	}
-	return transactionID, err
-}
-
 func (s *queuePDUsStatements) SelectQueuePDUReferenceJSONCount(
 	ctx context.Context, txn *sql.Tx, jsonNID int64,
 ) (int64, error) {
@@ -182,11 +160,10 @@ func (s *queuePDUsStatements) SelectQueuePDUCount(
 func (s *queuePDUsStatements) SelectQueuePDUs(
 	ctx context.Context, txn *sql.Tx,
 	serverName gomatrixserverlib.ServerName,
-	transactionID gomatrixserverlib.TransactionID,
 	limit int,
 ) ([]int64, error) {
-	stmt := sqlutil.TxStmt(txn, s.selectQueuePDUsByTransactionStmt)
+	stmt := sqlutil.TxStmt(txn, s.selectQueuePDUsStmt)
-	rows, err := stmt.QueryContext(ctx, serverName, transactionID, limit)
+	rows, err := stmt.QueryContext(ctx, serverName, limit)
 	if err != nil {
 		return nil, err
 	}

federationsender/storage/postgres/storage.go

@@ -19,6 +19,7 @@ import (
 	"database/sql"
 
 	"github.com/matrix-org/dendrite/federationsender/storage/shared"
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
 )
@@ -32,7 +33,7 @@ type Database struct {
 }
 
 // NewDatabase opens a new database
-func NewDatabase(dbProperties *config.DatabaseOptions) (*Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, cache caching.FederationSenderCache) (*Database, error) {
 	var d Database
 	var err error
 	if d.db, err = sqlutil.Open(dbProperties); err != nil {
@@ -73,6 +74,7 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*Database, error) {
 	}
 	d.Database = shared.Database{
 		DB:                            d.db,
+    Cache:                         cache,
 		Writer:                        d.writer,
 		FederationSenderJoinedHosts:   joinedHosts,
 		FederationSenderQueuePDUs:     queuePDUs,

federationsender/storage/shared/storage.go

@@ -17,17 +17,18 @@ package shared
 import (
 	"context"
 	"database/sql"
-	"encoding/json"
 	"fmt"
 
 	"github.com/matrix-org/dendrite/federationsender/storage/tables"
 	"github.com/matrix-org/dendrite/federationsender/types"
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/gomatrixserverlib"
 )
 
 type Database struct {
 	DB                            *sql.DB
+ 	Cache                         caching.FederationSenderCache
 	Writer                        sqlutil.Writer
 	FederationSenderQueuePDUs     tables.FederationSenderQueuePDUs
 	FederationSenderQueueEDUs     tables.FederationSenderQueueEDUs
@@ -44,16 +45,11 @@ type Database struct {
 // to pass them back so that we can clean up if the transaction sends
 // successfully.
 type Receipt struct {
-	nids []int64
+	nid int64
 }
 
-func (e *Receipt) Empty() bool {
+func (r *Receipt) String() string {
-	return len(e.nids) == 0
+	return fmt.Sprintf("%d", r.nid)
-}
-
-func (e *Receipt) String() string {
-	j, _ := json.Marshal(e.nids)
-	return string(j)
 }
 
 // UpdateRoom updates the joined hosts for a room and returns what the joined
@@ -146,7 +142,7 @@ func (d *Database) StoreJSON(
 		return nil, fmt.Errorf("d.insertQueueJSON: %w", err)
 	}
 	return &Receipt{
-		nids: []int64{nid},
+		nid: nid,
 	}, nil
 }
 

federationsender/storage/shared/storage_edus.go

@@ -33,16 +33,14 @@ func (d *Database) AssociateEDUWithDestination(
 	receipt *Receipt,
 ) error {
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		for _, nid := range receipt.nids {
+		if err := d.FederationSenderQueueEDUs.InsertQueueEDU(
-			if err := d.FederationSenderQueueEDUs.InsertQueueEDU(
+			ctx,         // context
-				ctx,        // context
+			txn,         // SQL transaction
-				txn,        // SQL transaction
+			"",          // TODO: EDU type for coalescing
-				"",         // TODO: EDU type for coalescing
+			serverName,  // destination server name
-				serverName, // destination server name
+			receipt.nid, // NID from the federationsender_queue_json table
-				nid,        // NID from the federationsender_queue_json table
+		); err != nil {
-			); err != nil {
+			return fmt.Errorf("InsertQueueEDU: %w", err)
-				return fmt.Errorf("InsertQueueEDU: %w", err)
-			}
 		}
 		return nil
 	})
@@ -50,36 +48,41 @@ func (d *Database) AssociateEDUWithDestination(
 
 // GetNextTransactionEDUs retrieves events from the database for
 // the next pending transaction, up to the limit specified.
-func (d *Database) GetNextTransactionEDUs(
+func (d *Database) GetPendingEDUs(
 	ctx context.Context,
 	serverName gomatrixserverlib.ServerName,
 	limit int,
 ) (
-	edus []*gomatrixserverlib.EDU,
+	edus map[*Receipt]*gomatrixserverlib.EDU,
-	receipt *Receipt,
 	err error,
 ) {
+	edus = make(map[*Receipt]*gomatrixserverlib.EDU)
 	err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
 		nids, err := d.FederationSenderQueueEDUs.SelectQueueEDUs(ctx, txn, serverName, limit)
 		if err != nil {
 			return fmt.Errorf("SelectQueueEDUs: %w", err)
 		}
 
-		receipt = &Receipt{
+		retrieve := make([]int64, 0, len(nids))
-			nids: nids,
+		for _, nid := range nids {
+			if edu, ok := d.Cache.GetFederationSenderQueuedEDU(nid); ok {
+				edus[&Receipt{nid}] = edu
+			} else {
+				retrieve = append(retrieve, nid)
+			}
 		}
 
-		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, nids)
+		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, retrieve)
 		if err != nil {
 			return fmt.Errorf("SelectQueueJSON: %w", err)
 		}
 
-		for _, blob := range blobs {
+		for nid, blob := range blobs {
 			var event gomatrixserverlib.EDU
 			if err := json.Unmarshal(blob, &event); err != nil {
 				return fmt.Errorf("json.Unmarshal: %w", err)
 			}
-			edus = append(edus, &event)
+			edus[&Receipt{nid}] = &event
 		}
 
 		return nil
@@ -92,25 +95,31 @@ func (d *Database) GetNextTransactionEDUs(
 func (d *Database) CleanEDUs(
 	ctx context.Context,
 	serverName gomatrixserverlib.ServerName,
-	receipt *Receipt,
+	receipts []*Receipt,
 ) error {
-	if receipt == nil {
+	if len(receipts) == 0 {
 		return errors.New("expected receipt")
 	}
 
+	nids := make([]int64, len(receipts))
+	for i := range receipts {
+		nids[i] = receipts[i].nid
+	}
+
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		if err := d.FederationSenderQueueEDUs.DeleteQueueEDUs(ctx, txn, serverName, receipt.nids); err != nil {
+		if err := d.FederationSenderQueueEDUs.DeleteQueueEDUs(ctx, txn, serverName, nids); err != nil {
 			return err
 		}
 
 		var deleteNIDs []int64
-		for _, nid := range receipt.nids {
+		for _, nid := range nids {
 			count, err := d.FederationSenderQueueEDUs.SelectQueueEDUReferenceJSONCount(ctx, txn, nid)
 			if err != nil {
 				return fmt.Errorf("SelectQueueEDUReferenceJSONCount: %w", err)
 			}
 			if count == 0 {
 				deleteNIDs = append(deleteNIDs, nid)
+				d.Cache.EvictFederationSenderQueuedEDU(nid)
 			}
 		}
 

federationsender/storage/shared/storage_pdus.go

@@ -34,16 +34,14 @@ func (d *Database) AssociatePDUWithDestination(
 	receipt *Receipt,
 ) error {
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		for _, nid := range receipt.nids {
+		if err := d.FederationSenderQueuePDUs.InsertQueuePDU(
-			if err := d.FederationSenderQueuePDUs.InsertQueuePDU(
+			ctx,           // context
-				ctx,           // context
+			txn,           // SQL transaction
-				txn,           // SQL transaction
+			transactionID, // transaction ID
-				transactionID, // transaction ID
+			serverName,    // destination server name
-				serverName,    // destination server name
+			receipt.nid,   // NID from the federationsender_queue_json table
-				nid,           // NID from the federationsender_queue_json table
+		); err != nil {
-			); err != nil {
+			return fmt.Errorf("InsertQueuePDU: %w", err)
-				return fmt.Errorf("InsertQueuePDU: %w", err)
-			}
 		}
 		return nil
 	})
@@ -51,14 +49,12 @@ func (d *Database) AssociatePDUWithDestination(
 
 // GetNextTransactionPDUs retrieves events from the database for
 // the next pending transaction, up to the limit specified.
-func (d *Database) GetNextTransactionPDUs(
+func (d *Database) GetPendingPDUs(
 	ctx context.Context,
 	serverName gomatrixserverlib.ServerName,
 	limit int,
 ) (
-	transactionID gomatrixserverlib.TransactionID,
+	events map[*Receipt]*gomatrixserverlib.HeaderedEvent,
-	events []*gomatrixserverlib.HeaderedEvent,
-	receipt *Receipt,
 	err error,
 ) {
 	// Strictly speaking this doesn't need to be using the writer
@@ -66,36 +62,34 @@ func (d *Database) GetNextTransactionPDUs(
 	// a guarantee of transactional isolation, it's actually useful
 	// to know in SQLite mode that nothing else is trying to modify
 	// the database.
+	events = make(map[*Receipt]*gomatrixserverlib.HeaderedEvent)
 	err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		transactionID, err = d.FederationSenderQueuePDUs.SelectQueuePDUNextTransactionID(ctx, txn, serverName)
+		nids, err := d.FederationSenderQueuePDUs.SelectQueuePDUs(ctx, txn, serverName, limit)
-		if err != nil {
-			return fmt.Errorf("SelectQueuePDUNextTransactionID: %w", err)
-		}
-
-		if transactionID == "" {
-			return nil
-		}
-
-		nids, err := d.FederationSenderQueuePDUs.SelectQueuePDUs(ctx, txn, serverName, transactionID, limit)
 		if err != nil {
 			return fmt.Errorf("SelectQueuePDUs: %w", err)
 		}
 
-		receipt = &Receipt{
+		retrieve := make([]int64, 0, len(nids))
-			nids: nids,
+		for _, nid := range nids {
+			if event, ok := d.Cache.GetFederationSenderQueuedPDU(nid); ok {
+				events[&Receipt{nid}] = event
+			} else {
+				retrieve = append(retrieve, nid)
+			}
 		}
 
-		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, nids)
+		blobs, err := d.FederationSenderQueueJSON.SelectQueueJSON(ctx, txn, retrieve)
 		if err != nil {
 			return fmt.Errorf("SelectQueueJSON: %w", err)
 		}
 
-		for _, blob := range blobs {
+		for nid, blob := range blobs {
 			var event gomatrixserverlib.HeaderedEvent
 			if err := json.Unmarshal(blob, &event); err != nil {
 				return fmt.Errorf("json.Unmarshal: %w", err)
 			}
-			events = append(events, &event)
+			events[&Receipt{nid}] = &event
+			d.Cache.StoreFederationSenderQueuedPDU(nid, &event)
 		}
 
 		return nil
@@ -109,25 +103,31 @@ func (d *Database) GetNextTransactionPDUs(
 func (d *Database) CleanPDUs(
 	ctx context.Context,
 	serverName gomatrixserverlib.ServerName,
-	receipt *Receipt,
+	receipts []*Receipt,
 ) error {
-	if receipt == nil {
+	if len(receipts) == 0 {
 		return errors.New("expected receipt")
 	}
 
+	nids := make([]int64, len(receipts))
+	for i := range receipts {
+		nids[i] = receipts[i].nid
+	}
+
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		if err := d.FederationSenderQueuePDUs.DeleteQueuePDUs(ctx, txn, serverName, receipt.nids); err != nil {
+		if err := d.FederationSenderQueuePDUs.DeleteQueuePDUs(ctx, txn, serverName, nids); err != nil {
 			return err
 		}
 
 		var deleteNIDs []int64
-		for _, nid := range receipt.nids {
+		for _, nid := range nids {
 			count, err := d.FederationSenderQueuePDUs.SelectQueuePDUReferenceJSONCount(ctx, txn, nid)
 			if err != nil {
 				return fmt.Errorf("SelectQueuePDUReferenceJSONCount: %w", err)
 			}
 			if count == 0 {
 				deleteNIDs = append(deleteNIDs, nid)
+				d.Cache.EvictFederationSenderQueuedPDU(nid)
 			}
 		}
 

federationsender/storage/sqlite3/queue_pdus_table.go

@@ -53,10 +53,10 @@ const selectQueueNextTransactionIDSQL = "" +
 	" ORDER BY transaction_id ASC" +
 	" LIMIT 1"
 
-const selectQueuePDUsByTransactionSQL = "" +
+const selectQueuePDUsSQL = "" +
 	"SELECT json_nid FROM federationsender_queue_pdus" +
-	" WHERE server_name = $1 AND transaction_id = $2" +
+	" WHERE server_name = $1" +
-	" LIMIT $3"
+	" LIMIT $2"
 
 const selectQueuePDUsReferenceJSONCountSQL = "" +
 	"SELECT COUNT(*) FROM federationsender_queue_pdus" +
@@ -73,7 +73,7 @@ type queuePDUsStatements struct {
 	db                                *sql.DB
 	insertQueuePDUStmt                *sql.Stmt
 	selectQueueNextTransactionIDStmt  *sql.Stmt
-	selectQueuePDUsByTransactionStmt  *sql.Stmt
+	selectQueuePDUsStmt               *sql.Stmt
 	selectQueueReferenceJSONCountStmt *sql.Stmt
 	selectQueuePDUsCountStmt          *sql.Stmt
 	selectQueueServerNamesStmt        *sql.Stmt
@@ -97,7 +97,7 @@ func NewSQLiteQueuePDUsTable(db *sql.DB) (s *queuePDUsStatements, err error) {
 	if s.selectQueueNextTransactionIDStmt, err = db.Prepare(selectQueueNextTransactionIDSQL); err != nil {
 		return
 	}
-	if s.selectQueuePDUsByTransactionStmt, err = db.Prepare(selectQueuePDUsByTransactionSQL); err != nil {
+	if s.selectQueuePDUsStmt, err = db.Prepare(selectQueuePDUsSQL); err != nil {
 		return
 	}
 	if s.selectQueueReferenceJSONCountStmt, err = db.Prepare(selectQueuePDUsReferenceJSONCountSQL); err != nil {
@@ -193,11 +193,10 @@ func (s *queuePDUsStatements) SelectQueuePDUCount(
 func (s *queuePDUsStatements) SelectQueuePDUs(
 	ctx context.Context, txn *sql.Tx,
 	serverName gomatrixserverlib.ServerName,
-	transactionID gomatrixserverlib.TransactionID,
 	limit int,
 ) ([]int64, error) {
-	stmt := sqlutil.TxStmt(txn, s.selectQueuePDUsByTransactionStmt)
+	stmt := sqlutil.TxStmt(txn, s.selectQueuePDUsStmt)
-	rows, err := stmt.QueryContext(ctx, serverName, transactionID, limit)
+	rows, err := stmt.QueryContext(ctx, serverName, limit)
 	if err != nil {
 		return nil, err
 	}

federationsender/storage/sqlite3/storage.go

@@ -21,6 +21,7 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 
 	"github.com/matrix-org/dendrite/federationsender/storage/shared"
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
 )
@@ -34,7 +35,7 @@ type Database struct {
 }
 
 // NewDatabase opens a new database
-func NewDatabase(dbProperties *config.DatabaseOptions) (*Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, cache caching.FederationSenderCache) (*Database, error) {
 	var d Database
 	var err error
 	if d.db, err = sqlutil.Open(dbProperties); err != nil {
@@ -75,6 +76,7 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*Database, error) {
 	}
 	d.Database = shared.Database{
 		DB:                            d.db,
+		Cache:                         cache,
 		Writer:                        d.writer,
 		FederationSenderJoinedHosts:   joinedHosts,
 		FederationSenderQueuePDUs:     queuePDUs,

federationsender/storage/storage.go

@@ -21,16 +21,17 @@ import (
 
 	"github.com/matrix-org/dendrite/federationsender/storage/postgres"
 	"github.com/matrix-org/dendrite/federationsender/storage/sqlite3"
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/setup/config"
 )
 
 // NewDatabase opens a new database
-func NewDatabase(dbProperties *config.DatabaseOptions) (Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, cache caching.FederationSenderCache) (Database, error) {
 	switch {
 	case dbProperties.ConnectionString.IsSQLite():
-		return sqlite3.NewDatabase(dbProperties)
+		return sqlite3.NewDatabase(dbProperties, cache)
 	case dbProperties.ConnectionString.IsPostgres():
-		return postgres.NewDatabase(dbProperties)
+		return postgres.NewDatabase(dbProperties, cache)
 	default:
 		return nil, fmt.Errorf("unexpected database type")
 	}

federationsender/storage/storage_wasm.go

@@ -18,14 +18,15 @@ import (
 	"fmt"
 
 	"github.com/matrix-org/dendrite/federationsender/storage/sqlite3"
+	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/setup/config"
 )
 
 // NewDatabase opens a new database
-func NewDatabase(dbProperties *config.DatabaseOptions) (Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, cache caching.FederationSenderCache) (Database, error) {
 	switch {
 	case dbProperties.ConnectionString.IsSQLite():
-		return sqlite3.NewDatabase(dbProperties)
+		return sqlite3.NewDatabase(dbProperties, cache)
 	case dbProperties.ConnectionString.IsPostgres():
 		return nil, fmt.Errorf("can't use Postgres implementation")
 	default:

federationsender/storage/tables/interface.go

@@ -25,10 +25,9 @@ import (
 type FederationSenderQueuePDUs interface {
 	InsertQueuePDU(ctx context.Context, txn *sql.Tx, transactionID gomatrixserverlib.TransactionID, serverName gomatrixserverlib.ServerName, nid int64) error
 	DeleteQueuePDUs(ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName, jsonNIDs []int64) error
-	SelectQueuePDUNextTransactionID(ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName) (gomatrixserverlib.TransactionID, error)
 	SelectQueuePDUReferenceJSONCount(ctx context.Context, txn *sql.Tx, jsonNID int64) (int64, error)
 	SelectQueuePDUCount(ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName) (int64, error)
-	SelectQueuePDUs(ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName, transactionID gomatrixserverlib.TransactionID, limit int) ([]int64, error)
+	SelectQueuePDUs(ctx context.Context, txn *sql.Tx, serverName gomatrixserverlib.ServerName, limit int) ([]int64, error)
 	SelectQueuePDUServerNames(ctx context.Context, txn *sql.Tx) ([]gomatrixserverlib.ServerName, error)
 }
 

go.mod

@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200518170932-783164aeeda4
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3
 	github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20201202134418-2ba106a5bca3
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20201209172200-eb6a8903f9fb
 	github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
 	github.com/mattn/go-sqlite3 v1.14.2
@@ -32,15 +32,17 @@ require (
 	github.com/pkg/errors v0.9.1
 	github.com/pressly/goose v2.7.0-rc5+incompatible
 	github.com/prometheus/client_golang v1.7.1
-	github.com/sirupsen/logrus v1.6.0
+	github.com/sirupsen/logrus v1.7.0
 	github.com/tidwall/gjson v1.6.3
-	github.com/tidwall/sjson v1.1.1
+	github.com/tidwall/match v1.0.2 // indirect
+	github.com/tidwall/sjson v1.1.2
 	github.com/uber/jaeger-client-go v2.25.0+incompatible
 	github.com/uber/jaeger-lib v2.2.0+incompatible
 	github.com/yggdrasil-network/yggdrasil-go v0.3.15-0.20201006093556-760d9a7fd5ee
 	go.uber.org/atomic v1.6.0
-	golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a
+	golang.org/x/crypto v0.0.0-20201117144127-c1f2f97bffc9
 	golang.org/x/net v0.0.0-20200528225125-3c3fba18258b
+	golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 // indirect
 	gopkg.in/h2non/bimg.v1 v1.1.4
 	gopkg.in/yaml.v2 v2.3.0
 )

go.sum

@@ -301,8 +301,6 @@ github.com/konsorten/go-windows-terminal-sequences v1.0.2 h1:DB17ag19krx9CFsz4o3
 github.com/konsorten/go-windows-terminal-sequences v1.0.2 h1:DB17ag19krx9CFsz4o3enTrPXyIXCl+2iCXH/aMAp9s=
 github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
-github.com/konsorten/go-windows-terminal-sequences v1.0.3 h1:CE8S1cTafDpPvMhIxNJKvHsGVBgn1xWYf1NbHQhywc8=
-github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/koron/go-ssdp v0.0.0-20191105050749-2e1c40ed0b5d h1:68u9r4wEvL3gYg2jvAOgROwZ3H+Y3hIDk4tbbmIjcYQ=
 github.com/koron/go-ssdp v0.0.0-20191105050749-2e1c40ed0b5d/go.mod h1:5Ky9EC2xfoUKUor0Hjgi2BJhCSXJfMOFlmyYrVKGQMk=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
@@ -569,8 +567,8 @@ github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26 h1:Hr3zjRsq2bh
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
 github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd h1:xVrqJK3xHREMNjwjljkAUaadalWc0rRbmVuQatzmgwg=
 github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20201202134418-2ba106a5bca3 h1:+45Q/5FybBhHPMr10YdzJNFYO/6RRgkBcZbMzIRq5Ck=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20201209172200-eb6a8903f9fb h1:UlhiSebJupQ+qAM93cdVGg4nAJ6bnxwAA5/EBygtYoo=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20201202134418-2ba106a5bca3/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20201209172200-eb6a8903f9fb/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91 h1:HJ6U3S3ljJqNffYMcIeAncp5qT/i+ZMiJ2JC2F0aXP4=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91/go.mod h1:sjyPyRxKM5uw1nD2cJ6O2OxI6GOqyVBfNXqKjBZTBZE=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7 h1:ntrLa/8xVzeSs8vHFHK25k0C+NV74sYMJnNSg5NoSRo=
@@ -779,8 +777,8 @@ github.com/shurcooL/webdavfs v0.0.0-20170829043945-18c3829fa133/go.mod h1:hKmq5k
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
-github.com/sirupsen/logrus v1.6.0 h1:UBcNElsrwanuuMsnGSlYmtmgbb23qDR5dG+6X6Oo89I=
+github.com/sirupsen/logrus v1.7.0 h1:ShrD1U9pZB12TX0cVy0DtePoCH97K8EtX+mg7ZARUtM=
-github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
+github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
 github.com/smola/gocompat v0.2.0/go.mod h1:1B0MlxbmoZNo3h8guHp8HztB3BSYR5itql9qtVc0ypY=
 github.com/sourcegraph/annotate v0.0.0-20160123013949-f4cad6c6324d/go.mod h1:UdhH50NIW0fCiwBSr0co2m7BnFLdv4fQTgdqdJTHFeE=
 github.com/sourcegraph/syntaxhighlight v0.0.0-20170531221838-bd320f5d308e/go.mod h1:HuIsMU8RRBOtsCgI77wP899iHVBQpCmg4ErYMZB+2IA=
@@ -812,10 +810,13 @@ github.com/syndtr/goleveldb v1.0.0/go.mod h1:ZVVdQEZoIme9iO1Ch2Jdy24qqXrMMOU6lpP
 github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07/go.mod h1:kDXzergiv9cbyO7IOYJZWg1U88JhDg3PB6klq9Hg2pA=
 github.com/tidwall/gjson v1.6.0 h1:9VEQWz6LLMUsUl6PueE49ir4Ka6CzLymOAZDxpFsTDc=
 github.com/tidwall/gjson v1.6.0/go.mod h1:P256ACg0Mn+j1RXIDXoss50DeIABTYK1PULOJHhxOls=
+github.com/tidwall/gjson v1.6.1/go.mod h1:BaHyNc5bjzYkPqgLq7mdVzeiRtULKULXLgZFKsxEHI0=
 github.com/tidwall/gjson v1.6.3 h1:aHoiiem0dr7GHkW001T1SMTJ7X5PvyekH5WX0whWGnI=
 github.com/tidwall/gjson v1.6.3/go.mod h1:BaHyNc5bjzYkPqgLq7mdVzeiRtULKULXLgZFKsxEHI0=
 github.com/tidwall/match v1.0.1 h1:PnKP62LPNxHKTwvHHZZzdOAOCtsJTjo6dZLCwpKm5xc=
 github.com/tidwall/match v1.0.1/go.mod h1:LujAq0jyVjBy028G1WhWfIzbpQfMO8bBZ6Tyb0+pL9E=
+github.com/tidwall/match v1.0.2 h1:uuqvHuBGSedK7awZ2YoAtpnimfwBGFjHuWLuLqQj+bU=
+github.com/tidwall/match v1.0.2/go.mod h1:LujAq0jyVjBy028G1WhWfIzbpQfMO8bBZ6Tyb0+pL9E=
 github.com/tidwall/pretty v1.0.0/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
 github.com/tidwall/pretty v1.0.1 h1:WE4RBSZ1x6McVVC8S/Md+Qse8YUv6HRObAx6ke00NY8=
 github.com/tidwall/pretty v1.0.1/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
@@ -823,8 +824,8 @@ github.com/tidwall/pretty v1.0.2 h1:Z7S3cePv9Jwm1KwS0513MRaoUe3S01WPbLNV40pwWZU=
 github.com/tidwall/pretty v1.0.2/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
 github.com/tidwall/sjson v1.0.3 h1:DeF+0LZqvIt4fKYw41aPB29ZGlvwVkHKktoXJ1YW9Y8=
 github.com/tidwall/sjson v1.0.3/go.mod h1:bURseu1nuBkFpIES5cz6zBtjmYeOQmEESshn7VpF15Y=
-github.com/tidwall/sjson v1.1.1 h1:7h1vk049Jnd5EH9NyzNiEuwYW4b5qgreBbqRC19AS3U=
+github.com/tidwall/sjson v1.1.2 h1:NC5okI+tQ8OG/oyzchvwXXxRxCV/FVdhODbPKkQ25jQ=
-github.com/tidwall/sjson v1.1.1/go.mod h1:yvVuSnpEQv5cYIrO+AT6kw4QVfd5SDZoGIS7/5+fZFs=
+github.com/tidwall/sjson v1.1.2/go.mod h1:SEzaDwxiPzKzNfUEO4HbYF/m4UCSJDsGgNqsS1LvdoY=
 github.com/uber/jaeger-client-go v2.25.0+incompatible h1:IxcNZ7WRY1Y3G4poYlx24szfsn/3LvK9QHCq9oQw8+U=
 github.com/uber/jaeger-client-go v2.25.0+incompatible/go.mod h1:WVhlPFC8FDjOFMMWRy2pZqQJSXxYSwNYOkTr/Z6d3Kk=
 github.com/uber/jaeger-lib v2.2.0+incompatible h1:MxZXOiR2JuoANZ3J6DE/U0kSFv/eJ/GfSYVCjK7dyaw=
@@ -905,8 +906,8 @@ golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5 h1:Q7tZBpemrlsc2I7IyODzht
 golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37 h1:cg5LA/zNPRzIXIWSCxQW10Rvpy94aQh3LT/ShoCpkHw=
 golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a h1:vclmkQCjlDX5OydZ9wv8rBCcS0QyQY66Mpf/7BZbInM=
+golang.org/x/crypto v0.0.0-20201117144127-c1f2f97bffc9 h1:phUcVbl53swtrUN8kQEXFhUxPlIlWyBfKmidCu7P95o=
-golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201117144127-c1f2f97bffc9/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/lint v0.0.0-20180702182130-06c8688daad7/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
@@ -982,6 +983,7 @@ golang.org/x/sys v0.0.0-20190904154756-749cb33beabd/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191003212358-c178f38b412c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191128015809-6d18c012aee9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200106162015-b016eb3dc98e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -994,6 +996,9 @@ golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1 h1:ogLJMz+qpzav7lGMh10LMvAkM/fAoGlaiiHYiFYdm80=
 golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 h1:nxC68pudNYkKU6jWhgrqdreuFiOQWj1Fs7T3VrH4Pjw=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

internal/caching/cache_federationevents.go

@@ -0,0 +1,67 @@
+package caching
+
+import (
+	"fmt"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const (
+	FederationEventCacheName       = "federation_event"
+	FederationEventCacheMaxEntries = 256
+	FederationEventCacheMutable    = true // to allow use of Unset only
+)
+
+// FederationSenderCache contains the subset of functions needed for
+// a federation event cache.
+type FederationSenderCache interface {
+	GetFederationSenderQueuedPDU(eventNID int64) (event *gomatrixserverlib.HeaderedEvent, ok bool)
+	StoreFederationSenderQueuedPDU(eventNID int64, event *gomatrixserverlib.HeaderedEvent)
+	EvictFederationSenderQueuedPDU(eventNID int64)
+
+	GetFederationSenderQueuedEDU(eventNID int64) (event *gomatrixserverlib.EDU, ok bool)
+	StoreFederationSenderQueuedEDU(eventNID int64, event *gomatrixserverlib.EDU)
+	EvictFederationSenderQueuedEDU(eventNID int64)
+}
+
+func (c Caches) GetFederationSenderQueuedPDU(eventNID int64) (*gomatrixserverlib.HeaderedEvent, bool) {
+	key := fmt.Sprintf("%d", eventNID)
+	val, found := c.FederationEvents.Get(key)
+	if found && val != nil {
+		if event, ok := val.(*gomatrixserverlib.HeaderedEvent); ok {
+			return event, true
+		}
+	}
+	return nil, false
+}
+
+func (c Caches) StoreFederationSenderQueuedPDU(eventNID int64, event *gomatrixserverlib.HeaderedEvent) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Set(key, event)
+}
+
+func (c Caches) EvictFederationSenderQueuedPDU(eventNID int64) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Unset(key)
+}
+
+func (c Caches) GetFederationSenderQueuedEDU(eventNID int64) (*gomatrixserverlib.EDU, bool) {
+	key := fmt.Sprintf("%d", eventNID)
+	val, found := c.FederationEvents.Get(key)
+	if found && val != nil {
+		if event, ok := val.(*gomatrixserverlib.EDU); ok {
+			return event, true
+		}
+	}
+	return nil, false
+}
+
+func (c Caches) StoreFederationSenderQueuedEDU(eventNID int64, event *gomatrixserverlib.EDU) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Set(key, event)
+}
+
+func (c Caches) EvictFederationSenderQueuedEDU(eventNID int64) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Unset(key)
+}

internal/caching/caches.go

@@ -10,6 +10,7 @@ type Caches struct {
 	RoomServerEventTypeNIDs Cache // RoomServerNIDsCache
 	RoomServerRoomNIDs      Cache // RoomServerNIDsCache
 	RoomServerRoomIDs       Cache // RoomServerNIDsCache
+	FederationEvents        Cache // FederationEventsCache
 }
 
 // Cache is the interface that an implementation must satisfy.

internal/caching/impl_inmemorylru.go

@@ -63,6 +63,15 @@ func NewInMemoryLRUCache(enablePrometheus bool) (*Caches, error) {
 	if err != nil {
 		return nil, err
 	}
+	federationEvents, err := NewInMemoryLRUCachePartition(
+		FederationEventCacheName,
+		FederationEventCacheMutable,
+		FederationEventCacheMaxEntries,
+		enablePrometheus,
+	)
+	if err != nil {
+		return nil, err
+	}
 	return &Caches{
 		RoomVersions:            roomVersions,
 		ServerKeys:              serverKeys,
@@ -70,6 +79,7 @@ func NewInMemoryLRUCache(enablePrometheus bool) (*Caches, error) {
 		RoomServerEventTypeNIDs: roomServerEventTypeNIDs,
 		RoomServerRoomNIDs:      roomServerRoomNIDs,
 		RoomServerRoomIDs:       roomServerRoomIDs,
+		FederationEvents:        federationEvents,
 	}, nil
 }
 

internal/version.go

@@ -17,7 +17,7 @@ var build string
 const (
 	VersionMajor = 0
 	VersionMinor = 3
-	VersionPatch = 2
+	VersionPatch = 3
 	VersionTag   = "" // example: "rc1"
 )
 

roomserver/api/api.go

@@ -138,6 +138,15 @@ type RoomserverInternalAPI interface {
 		response *QueryStateAndAuthChainResponse,
 	) error
 
+	// QueryAuthChain returns the entire auth chain for the event IDs given.
+	// The response includes the events in the request.
+	// Omits without error for any missing auth events. There will be no duplicates.
+	QueryAuthChain(
+		ctx context.Context,
+		request *QueryAuthChainRequest,
+		response *QueryAuthChainResponse,
+	) error
+
 	// QueryCurrentState retrieves the requested state events. If state events are not found, they will be missing from
 	// the response.
 	QueryCurrentState(ctx context.Context, req *QueryCurrentStateRequest, res *QueryCurrentStateResponse) error

roomserver/api/api_trace.go

@@ -334,6 +334,16 @@ func (t *RoomserverInternalAPITrace) QueryServerBannedFromRoom(ctx context.Conte
 	return err
 }
 
+func (t *RoomserverInternalAPITrace) QueryAuthChain(
+	ctx context.Context,
+	request *QueryAuthChainRequest,
+	response *QueryAuthChainResponse,
+) error {
+	err := t.Impl.QueryAuthChain(ctx, request, response)
+	util.GetLogger(ctx).WithError(err).Infof("QueryAuthChain req=%+v res=%+v", js(request), js(response))
+	return err
+}
+
 func js(thing interface{}) string {
 	b, err := json.Marshal(thing)
 	if err != nil {

roomserver/api/query.go

@@ -275,6 +275,14 @@ type QueryPublishedRoomsResponse struct {
 	RoomIDs []string
 }
 
+type QueryAuthChainRequest struct {
+	EventIDs []string
+}
+
+type QueryAuthChainResponse struct {
+	AuthChain []*gomatrixserverlib.HeaderedEvent
+}
+
 type QuerySharedUsersRequest struct {
 	UserID         string
 	ExcludeRoomIDs []string

roomserver/internal/input/input.go

@@ -62,10 +62,10 @@ func (w *inputWorker) start() {
 	for {
 		select {
 		case task := <-w.input:
-			hooks.Run(hooks.KindNewEventReceived, &task.event.Event)
+			hooks.Run(hooks.KindNewEventReceived, task.event.Event)
 			_, task.err = w.r.processRoomEvent(task.ctx, task.event)
 			if task.err == nil {
-				hooks.Run(hooks.KindNewEventPersisted, &task.event.Event)
+				hooks.Run(hooks.KindNewEventPersisted, task.event.Event)
 			}
 			task.wg.Done()
 		case <-time.After(time.Second * 5):

roomserver/internal/input/input_latest_events.go

@@ -285,15 +285,15 @@ func (u *latestEventsUpdater) calculateLatest(
 	// then do nothing - it's not a candidate to be a new extremity if
 	// it has been referenced.
 	if _, ok := existingPrevs[newEvent.EventID()]; ok {
+		u.latest = oldLatest
 		return false, nil
 	}
 
 	// If the "new" event is already a forward extremity then stop, as
 	// nothing changes.
-	for _, event := range events {
+	if _, ok := existingRefs[newEvent.EventID()]; ok {
-		if event.EventID() == newEvent.EventID() {
+		u.latest = oldLatest
-			return false, nil
+		return false, nil
-		}
 	}
 
 	// Include our new event in the extremities.

roomserver/internal/query/query.go

@@ -718,3 +718,16 @@ func (r *Queryer) QueryServerBannedFromRoom(ctx context.Context, req *api.QueryS
 	res.Banned = r.ServerACLs.IsServerBannedFromRoom(req.ServerName, req.RoomID)
 	return nil
 }
+
+func (r *Queryer) QueryAuthChain(ctx context.Context, req *api.QueryAuthChainRequest, res *api.QueryAuthChainResponse) error {
+	chain, err := getAuthChain(ctx, r.DB.EventsFromIDs, req.EventIDs)
+	if err != nil {
+		return err
+	}
+	hchain := make([]*gomatrixserverlib.HeaderedEvent, len(chain))
+	for i := range chain {
+		hchain[i] = chain[i].Headered(chain[i].Version())
+	}
+	res.AuthChain = hchain
+	return nil
+}

roomserver/inthttp/client.go

@@ -55,6 +55,7 @@ const (
 	RoomserverQuerySharedUsersPath             = "/roomserver/querySharedUsers"
 	RoomserverQueryKnownUsersPath              = "/roomserver/queryKnownUsers"
 	RoomserverQueryServerBannedFromRoomPath    = "/roomserver/queryServerBannedFromRoom"
+	RoomserverQueryAuthChainPath               = "/roomserver/queryAuthChain"
 )
 
 type httpRoomserverInternalAPI struct {
@@ -515,6 +516,16 @@ func (h *httpRoomserverInternalAPI) QueryKnownUsers(
 	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, req, res)
 }
 
+func (h *httpRoomserverInternalAPI) QueryAuthChain(
+	ctx context.Context, req *api.QueryAuthChainRequest, res *api.QueryAuthChainResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "QueryAuthChain")
+	defer span.Finish()
+
+	apiURL := h.roomserverURL + RoomserverQueryAuthChainPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, req, res)
+}
+
 func (h *httpRoomserverInternalAPI) QueryServerBannedFromRoom(
 	ctx context.Context, req *api.QueryServerBannedFromRoomRequest, res *api.QueryServerBannedFromRoomResponse,
 ) error {

roomserver/inthttp/server.go

@@ -465,4 +465,17 @@ func AddRoutes(r api.RoomserverInternalAPI, internalAPIMux *mux.Router) {
 			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
 		}),
 	)
+	internalAPIMux.Handle(RoomserverQueryAuthChainPath,
+		httputil.MakeInternalAPI("queryAuthChain", func(req *http.Request) util.JSONResponse {
+			request := api.QueryAuthChainRequest{}
+			response := api.QueryAuthChainResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := r.QueryAuthChain(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
 }

roomserver/storage/shared/storage.go

@@ -309,6 +309,10 @@ func (d *Database) Events(
 	if err != nil {
 		return nil, err
 	}
+	eventIDs, _ := d.EventsTable.BulkSelectEventID(ctx, eventNIDs)
+	if err != nil {
+		eventIDs = map[types.EventNID]string{}
+	}
 	results := make([]types.Event, len(eventJSONs))
 	for i, eventJSON := range eventJSONs {
 		var roomNID types.RoomNID
@@ -328,8 +332,8 @@ func (d *Database) Events(
 				return nil, err
 			}
 		}
-		result.Event, err = gomatrixserverlib.NewEventFromTrustedJSON(
+		result.Event, err = gomatrixserverlib.NewEventFromTrustedJSONWithEventID(
-			eventJSON.EventJSON, false, roomVersion,
+			eventIDs[eventJSON.EventNID], eventJSON.EventJSON, false, roomVersion,
 		)
 		if err != nil {
 			return nil, err
@@ -779,6 +783,7 @@ func (d *Database) loadEvent(ctx context.Context, eventID string) *types.Event {
 // GetStateEvent returns the current state event of a given type for a given room with a given state key
 // If no event could be found, returns nil
 // If there was an issue during the retrieval, returns an error
+// nolint:gocyclo
 func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey string) (*gomatrixserverlib.HeaderedEvent, error) {
 	roomInfo, err := d.RoomInfo(ctx, roomID)
 	if err != nil {
@@ -800,6 +805,16 @@ func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey s
 	if err != nil {
 		return nil, err
 	}
+	var eventNIDs []types.EventNID
+	for _, e := range entries {
+		if e.EventTypeNID == eventTypeNID && e.EventStateKeyNID == stateKeyNID {
+			eventNIDs = append(eventNIDs, e.EventNID)
+		}
+	}
+	eventIDs, _ := d.EventsTable.BulkSelectEventID(ctx, eventNIDs)
+	if err != nil {
+		eventIDs = map[types.EventNID]string{}
+	}
 	// return the event requested
 	for _, e := range entries {
 		if e.EventTypeNID == eventTypeNID && e.EventStateKeyNID == stateKeyNID {
@@ -810,7 +825,7 @@ func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey s
 			if len(data) == 0 {
 				return nil, fmt.Errorf("GetStateEvent: no json for event nid %d", e.EventNID)
 			}
-			ev, err := gomatrixserverlib.NewEventFromTrustedJSON(data[0].EventJSON, false, roomInfo.RoomVersion)
+			ev, err := gomatrixserverlib.NewEventFromTrustedJSONWithEventID(eventIDs[e.EventNID], data[0].EventJSON, false, roomInfo.RoomVersion)
 			if err != nil {
 				return nil, err
 			}
@@ -921,7 +936,10 @@ func (d *Database) GetBulkStateContent(ctx context.Context, roomIDs []string, tu
 			}
 		}
 	}
-
+	eventIDs, _ := d.EventsTable.BulkSelectEventID(ctx, eventNIDs)
+	if err != nil {
+		eventIDs = map[types.EventNID]string{}
+	}
 	events, err := d.EventJSONTable.BulkSelectEventJSON(ctx, eventNIDs)
 	if err != nil {
 		return nil, fmt.Errorf("GetBulkStateContent: failed to load event JSON for event nids: %w", err)
@@ -929,7 +947,7 @@ func (d *Database) GetBulkStateContent(ctx context.Context, roomIDs []string, tu
 	result := make([]tables.StrippedEvent, len(events))
 	for i := range events {
 		roomVer := eventNIDToVer[events[i].EventNID]
-		ev, err := gomatrixserverlib.NewEventFromTrustedJSON(events[i].EventJSON, false, roomVer)
+		ev, err := gomatrixserverlib.NewEventFromTrustedJSONWithEventID(eventIDs[events[i].EventNID], events[i].EventJSON, false, roomVer)
 		if err != nil {
 			return nil, fmt.Errorf("GetBulkStateContent: failed to load event JSON for event NID %v : %w", events[i].EventNID, err)
 		}

setup/mscs/msc2836/msc2836.go

@@ -18,10 +18,13 @@ package msc2836
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
+	"sort"
+	"strings"
 	"time"
 
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
@@ -36,13 +39,12 @@ import (
 )
 
 const (
-	constRelType     = "m.reference"
+	constRelType = "m.reference"
-	constRoomIDKey   = "relationship_room_id"
-	constRoomServers = "relationship_servers"
 )
 
 type EventRelationshipRequest struct {
 	EventID         string `json:"event_id"`
+	RoomID          string `json:"room_id"`
 	MaxDepth        int    `json:"max_depth"`
 	MaxBreadth      int    `json:"max_breadth"`
 	Limit           int    `json:"limit"`
@@ -52,7 +54,6 @@ type EventRelationshipRequest struct {
 	IncludeChildren bool   `json:"include_children"`
 	Direction       string `json:"direction"`
 	Batch           string `json:"batch"`
-	AutoJoin        bool   `json:"auto_join"`
 }
 
 func NewEventRelationshipRequest(body io.Reader) (*EventRelationshipRequest, error) {
@@ -81,8 +82,16 @@ type EventRelationshipResponse struct {
 	Limited   bool                            `json:"limited"`
 }
 
+func toClientResponse(res *gomatrixserverlib.MSC2836EventRelationshipsResponse) *EventRelationshipResponse {
+	out := &EventRelationshipResponse{
+		Events:    gomatrixserverlib.ToClientEvents(res.Events, gomatrixserverlib.FormatAll),
+		Limited:   res.Limited,
+		NextBatch: res.NextBatch,
+	}
+	return out
+}
+
 // Enable this MSC
-// nolint:gocyclo
 func Enable(
 	base *setup.BaseDendrite, rsAPI roomserver.RoomserverInternalAPI, fsAPI fs.FederationSenderInternalAPI,
 	userAPI userapi.UserInternalAPI, keyRing gomatrixserverlib.JSONVerifier,
@@ -96,63 +105,22 @@ func Enable(
 		he := headeredEvent.(*gomatrixserverlib.HeaderedEvent)
 		hookErr := db.StoreRelation(context.Background(), he)
 		if hookErr != nil {
-			util.GetLogger(context.Background()).WithError(hookErr).Error(
+			util.GetLogger(context.Background()).WithError(hookErr).WithField("event_id", he.EventID()).Error(
 				"failed to StoreRelation",
 			)
 		}
-	})
+		// we need to update child metadata here as well as after doing remote /event_relationships requests
-	hooks.Attach(hooks.KindNewEventReceived, func(headeredEvent interface{}) {
+		// so we catch child metadata originating from /send transactions
-		he := headeredEvent.(*gomatrixserverlib.HeaderedEvent)
+		hookErr = db.UpdateChildMetadata(context.Background(), he)
-		ctx := context.Background()
+		if hookErr != nil {
-		// we only inject metadata for events our server sends
+			util.GetLogger(context.Background()).WithError(err).WithField("event_id", he.EventID()).Warn(
-		userID := he.Sender()
+				"failed to update child metadata for event",
-		_, domain, err := gomatrixserverlib.SplitID('@', userID)
+			)
-		if err != nil {
-			return
-		}
-		if domain != base.Cfg.Global.ServerName {
-			return
-		}
-		// if this event has an m.relationship, add on the room_id and servers to unsigned
-		parent, child, relType := parentChildEventIDs(he)
-		if parent == "" || child == "" || relType == "" {
-			return
-		}
-		event, joinedToRoom := getEventIfVisible(ctx, rsAPI, parent, userID)
-		if !joinedToRoom {
-			return
-		}
-		err = he.SetUnsignedField(constRoomIDKey, event.RoomID())
-		if err != nil {
-			util.GetLogger(context.Background()).WithError(err).Warn("Failed to SetUnsignedField")
-			return
-		}
-
-		var servers []gomatrixserverlib.ServerName
-		if fsAPI != nil {
-			var res fs.QueryJoinedHostServerNamesInRoomResponse
-			err = fsAPI.QueryJoinedHostServerNamesInRoom(ctx, &fs.QueryJoinedHostServerNamesInRoomRequest{
-				RoomID: event.RoomID(),
-			}, &res)
-			if err != nil {
-				util.GetLogger(context.Background()).WithError(err).Warn("Failed to QueryJoinedHostServerNamesInRoom")
-				return
-			}
-			servers = res.ServerNames
-		} else {
-			servers = []gomatrixserverlib.ServerName{
-				base.Cfg.Global.ServerName,
-			}
-		}
-		err = he.SetUnsignedField(constRoomServers, servers)
-		if err != nil {
-			util.GetLogger(context.Background()).WithError(err).Warn("Failed to SetUnsignedField")
-			return
 		}
 	})
 
 	base.PublicClientAPIMux.Handle("/unstable/event_relationships",
-		httputil.MakeAuthAPI("eventRelationships", userAPI, eventRelationshipHandler(db, rsAPI)),
+		httputil.MakeAuthAPI("eventRelationships", userAPI, eventRelationshipHandler(db, rsAPI, fsAPI)),
 	).Methods(http.MethodPost, http.MethodOptions)
 
 	base.PublicFederationAPIMux.Handle("/unstable/event_relationships", httputil.MakeExternalAPI(
@@ -163,22 +131,27 @@ func Enable(
 			if fedReq == nil {
 				return errResp
 			}
-			return federatedEventRelationship(req.Context(), fedReq, db, rsAPI)
+			return federatedEventRelationship(req.Context(), fedReq, db, rsAPI, fsAPI)
 		},
 	)).Methods(http.MethodPost, http.MethodOptions)
 	return nil
 }
 
 type reqCtx struct {
-	ctx                context.Context
+	ctx         context.Context
-	rsAPI              roomserver.RoomserverInternalAPI
+	rsAPI       roomserver.RoomserverInternalAPI
-	db                 Database
+	db          Database
-	req                *EventRelationshipRequest
+	req         *EventRelationshipRequest
-	userID             string
+	userID      string
+	roomVersion gomatrixserverlib.RoomVersion
+
+	// federated request args
 	isFederatedRequest bool
+	serverName         gomatrixserverlib.ServerName
+	fsAPI              fs.FederationSenderInternalAPI
 }
 
-func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAPI) func(*http.Request, *userapi.Device) util.JSONResponse {
+func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAPI, fsAPI fs.FederationSenderInternalAPI) func(*http.Request, *userapi.Device) util.JSONResponse {
 	return func(req *http.Request, device *userapi.Device) util.JSONResponse {
 		relation, err := NewEventRelationshipRequest(req.Body)
 		if err != nil {
@@ -193,6 +166,7 @@ func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAP
 			req:                relation,
 			userID:             device.UserID,
 			rsAPI:              rsAPI,
+			fsAPI:              fsAPI,
 			isFederatedRequest: false,
 			db:                 db,
 		}
@@ -203,12 +177,14 @@ func eventRelationshipHandler(db Database, rsAPI roomserver.RoomserverInternalAP
 
 		return util.JSONResponse{
 			Code: 200,
-			JSON: res,
+			JSON: toClientResponse(res),
 		}
 	}
 }
 
-func federatedEventRelationship(ctx context.Context, fedReq *gomatrixserverlib.FederationRequest, db Database, rsAPI roomserver.RoomserverInternalAPI) util.JSONResponse {
+func federatedEventRelationship(
+	ctx context.Context, fedReq *gomatrixserverlib.FederationRequest, db Database, rsAPI roomserver.RoomserverInternalAPI, fsAPI fs.FederationSenderInternalAPI,
+) util.JSONResponse {
 	relation, err := NewEventRelationshipRequest(bytes.NewBuffer(fedReq.Content()))
 	if err != nil {
 		util.GetLogger(ctx).WithError(err).Error("failed to decode HTTP request as JSON")
@@ -218,17 +194,43 @@ func federatedEventRelationship(ctx context.Context, fedReq *gomatrixserverlib.F
 		}
 	}
 	rc := reqCtx{
-		ctx:                ctx,
+		ctx:   ctx,
-		req:                relation,
+		req:   relation,
-		userID:             "",
+		rsAPI: rsAPI,
-		rsAPI:              rsAPI,
+		db:    db,
+		// federation args
 		isFederatedRequest: true,
-		db:                 db,
+		fsAPI:              fsAPI,
+		serverName:         fedReq.Origin(),
 	}
 	res, resErr := rc.process()
 	if resErr != nil {
 		return *resErr
 	}
+	// add auth chain information
+	requiredAuthEventsSet := make(map[string]bool)
+	var requiredAuthEvents []string
+	for _, ev := range res.Events {
+		for _, a := range ev.AuthEventIDs() {
+			if requiredAuthEventsSet[a] {
+				continue
+			}
+			requiredAuthEvents = append(requiredAuthEvents, a)
+			requiredAuthEventsSet[a] = true
+		}
+	}
+	var queryRes roomserver.QueryAuthChainResponse
+	err = rsAPI.QueryAuthChain(ctx, &roomserver.QueryAuthChainRequest{
+		EventIDs: requiredAuthEvents,
+	}, &queryRes)
+	if err != nil {
+		// they may already have the auth events so don't fail this request
+		util.GetLogger(ctx).WithError(err).Error("Failed to QueryAuthChain")
+	}
+	res.AuthChain = make([]*gomatrixserverlib.Event, len(queryRes.AuthChain))
+	for i := range queryRes.AuthChain {
+		res.AuthChain[i] = queryRes.AuthChain[i].Unwrap()
+	}
 
 	return util.JSONResponse{
 		Code: 200,
@@ -236,18 +238,25 @@ func federatedEventRelationship(ctx context.Context, fedReq *gomatrixserverlib.F
 	}
 }
 
-func (rc *reqCtx) process() (*EventRelationshipResponse, *util.JSONResponse) {
+// nolint:gocyclo
-	var res EventRelationshipResponse
+func (rc *reqCtx) process() (*gomatrixserverlib.MSC2836EventRelationshipsResponse, *util.JSONResponse) {
+	var res gomatrixserverlib.MSC2836EventRelationshipsResponse
 	var returnEvents []*gomatrixserverlib.HeaderedEvent
 	// Can the user see (according to history visibility) event_id? If no, reject the request, else continue.
-	// We should have the event being referenced so don't give any claimed room ID / servers
+	event := rc.getLocalEvent(rc.req.EventID)
-	event := rc.getEventIfVisible(rc.req.EventID, "", nil)
 	if event == nil {
+		event = rc.fetchUnknownEvent(rc.req.EventID, rc.req.RoomID)
+	}
+	if rc.req.RoomID == "" && event != nil {
+		rc.req.RoomID = event.RoomID()
+	}
+	if event == nil || !rc.authorisedToSeeEvent(event) {
 		return nil, &util.JSONResponse{
 			Code: 403,
 			JSON: jsonerror.Forbidden("Event does not exist or you are not authorised to see it"),
 		}
 	}
+	rc.roomVersion = event.Version()
 
 	// Retrieve the event. Add it to response array.
 	returnEvents = append(returnEvents, event)
@@ -282,29 +291,122 @@ func (rc *reqCtx) process() (*EventRelationshipResponse, *util.JSONResponse) {
 		)
 		returnEvents = append(returnEvents, events...)
 	}
-	res.Events = make([]gomatrixserverlib.ClientEvent, len(returnEvents))
+	res.Events = make([]*gomatrixserverlib.Event, len(returnEvents))
 	for i, ev := range returnEvents {
-		res.Events[i] = gomatrixserverlib.HeaderedToClientEvent(ev, gomatrixserverlib.FormatAll)
+		// for each event, extract the children_count | hash and add it as unsigned data.
+		rc.addChildMetadata(ev)
+		res.Events[i] = ev.Unwrap()
 	}
 	res.Limited = remaining == 0 || walkLimited
 	return &res, nil
 }
 
+// fetchUnknownEvent retrieves an unknown event from the room specified. This server must
+// be joined to the room in question. This has the side effect of injecting surround threaded
+// events into the roomserver.
+func (rc *reqCtx) fetchUnknownEvent(eventID, roomID string) *gomatrixserverlib.HeaderedEvent {
+	if rc.isFederatedRequest || roomID == "" {
+		// we don't do fed hits for fed requests, and we can't ask servers without a room ID!
+		return nil
+	}
+	logger := util.GetLogger(rc.ctx).WithField("room_id", roomID)
+	// if they supplied a room_id, check the room exists.
+	var queryVerRes roomserver.QueryRoomVersionForRoomResponse
+	err := rc.rsAPI.QueryRoomVersionForRoom(rc.ctx, &roomserver.QueryRoomVersionForRoomRequest{
+		RoomID: roomID,
+	}, &queryVerRes)
+	if err != nil {
+		logger.WithError(err).Warn("failed to query room version for room, does this room exist?")
+		return nil
+	}
+
+	// check the user is joined to that room
+	var queryMemRes roomserver.QueryMembershipForUserResponse
+	err = rc.rsAPI.QueryMembershipForUser(rc.ctx, &roomserver.QueryMembershipForUserRequest{
+		RoomID: roomID,
+		UserID: rc.userID,
+	}, &queryMemRes)
+	if err != nil {
+		logger.WithError(err).Warn("failed to query membership for user in room")
+		return nil
+	}
+	if !queryMemRes.IsInRoom {
+		return nil
+	}
+
+	// ask one of the servers in the room for the event
+	var queryRes fs.QueryJoinedHostServerNamesInRoomResponse
+	err = rc.fsAPI.QueryJoinedHostServerNamesInRoom(rc.ctx, &fs.QueryJoinedHostServerNamesInRoomRequest{
+		RoomID: roomID,
+	}, &queryRes)
+	if err != nil {
+		logger.WithError(err).Error("failed to QueryJoinedHostServerNamesInRoom")
+		return nil
+	}
+	// query up to 5 servers
+	serversToQuery := queryRes.ServerNames
+	if len(serversToQuery) > 5 {
+		serversToQuery = serversToQuery[:5]
+	}
+
+	// fetch the event, along with some of the surrounding thread (if it's threaded) and the auth chain.
+	// Inject the response into the roomserver to remember the event across multiple calls and to set
+	// unexplored flags correctly.
+	for _, srv := range serversToQuery {
+		res, err := rc.MSC2836EventRelationships(eventID, srv, queryVerRes.RoomVersion)
+		if err != nil {
+			continue
+		}
+		rc.injectResponseToRoomserver(res)
+		for _, ev := range res.Events {
+			if ev.EventID() == eventID {
+				return ev.Headered(ev.Version())
+			}
+		}
+	}
+	logger.WithField("servers", serversToQuery).Warn("failed to query event relationships")
+	return nil
+}
+
 // If include_parent: true and there is a valid m.relationship field in the event,
 // retrieve the referenced event. Apply history visibility check to that event and if it passes, add it to the response array.
-func (rc *reqCtx) includeParent(event *gomatrixserverlib.HeaderedEvent) (parent *gomatrixserverlib.HeaderedEvent) {
+func (rc *reqCtx) includeParent(childEvent *gomatrixserverlib.HeaderedEvent) (parent *gomatrixserverlib.HeaderedEvent) {
-	parentID, _, _ := parentChildEventIDs(event)
+	parentID, _, _ := parentChildEventIDs(childEvent)
 	if parentID == "" {
 		return nil
 	}
-	claimedRoomID, claimedServers := roomIDAndServers(event)
+	return rc.lookForEvent(parentID)
-	return rc.getEventIfVisible(parentID, claimedRoomID, claimedServers)
 }
 
 // If include_children: true, lookup all events which have event_id as an m.relationship
 // Apply history visibility checks to all these events and add the ones which pass into the response array,
 // honouring the recent_first flag and the limit.
 func (rc *reqCtx) includeChildren(db Database, parentID string, limit int, recentFirst bool) ([]*gomatrixserverlib.HeaderedEvent, *util.JSONResponse) {
+	if rc.hasUnexploredChildren(parentID) {
+		// we need to do a remote request to pull in the children as we are missing them locally.
+		serversToQuery := rc.getServersForEventID(parentID)
+		var result *gomatrixserverlib.MSC2836EventRelationshipsResponse
+		for _, srv := range serversToQuery {
+			res, err := rc.fsAPI.MSC2836EventRelationships(rc.ctx, srv, gomatrixserverlib.MSC2836EventRelationshipsRequest{
+				EventID:     parentID,
+				Direction:   "down",
+				Limit:       100,
+				MaxBreadth:  -1,
+				MaxDepth:    1, // we just want the children from this parent
+				RecentFirst: true,
+			}, rc.roomVersion)
+			if err != nil {
+				util.GetLogger(rc.ctx).WithError(err).WithField("server", srv).Error("includeChildren: failed to call MSC2836EventRelationships")
+			} else {
+				result = &res
+				break
+			}
+		}
+		if result != nil {
+			rc.injectResponseToRoomserver(result)
+		}
+		// fallthrough to pull these new events from the DB
+	}
 	children, err := db.ChildrenForParent(rc.ctx, parentID, constRelType, recentFirst)
 	if err != nil {
 		util.GetLogger(rc.ctx).WithError(err).Error("failed to get ChildrenForParent")
@@ -313,8 +415,7 @@ func (rc *reqCtx) includeChildren(db Database, parentID string, limit int, recen
 	}
 	var childEvents []*gomatrixserverlib.HeaderedEvent
 	for _, child := range children {
-		// in order for us to even know about the children the server must be joined to those rooms, hence pass no claimed room ID or servers.
+		childEvent := rc.lookForEvent(child.EventID)
-		childEvent := rc.getEventIfVisible(child.EventID, "", nil)
 		if childEvent != nil {
 			childEvents = append(childEvents, childEvent)
 		}
@@ -327,14 +428,9 @@ func (rc *reqCtx) includeChildren(db Database, parentID string, limit int, recen
 
 // Begin to walk the thread DAG in the direction specified, either depth or breadth first according to the depth_first flag,
 // honouring the limit, max_depth and max_breadth values according to the following rules
-// nolint: unparam
 func walkThread(
 	ctx context.Context, db Database, rc *reqCtx, included map[string]bool, limit int,
 ) ([]*gomatrixserverlib.HeaderedEvent, bool) {
-	if rc.req.Direction != "down" {
-		util.GetLogger(ctx).Error("not implemented: direction=up")
-		return nil, false
-	}
 	var result []*gomatrixserverlib.HeaderedEvent
 	eventWalker := walker{
 		ctx: ctx,
@@ -352,8 +448,11 @@ func walkThread(
 			}
 
 			// Process the event.
-			// TODO: Include edge information: room ID and servers
+			// if event is not found, use remoteEventRelationships to explore that part of the thread remotely.
-			event := rc.getEventIfVisible(wi.EventID, "", nil)
+			// This will probably be easiest if the event relationships response is directly pumped into the database
+			// so the next walk will do the right thing. This requires those events to be authed and likely injected as
+			// outliers into the roomserver DB, which will de-dupe appropriately.
+			event := rc.lookForEvent(wi.EventID)
 			if event != nil {
 				result = append(result, event)
 			}
@@ -368,74 +467,280 @@ func walkThread(
 	return result, limited
 }
 
-func (rc *reqCtx) getEventIfVisible(eventID string, claimedRoomID string, claimedServers []string) *gomatrixserverlib.HeaderedEvent {
+// MSC2836EventRelationships performs an /event_relationships request to a remote server
-	event, joinedToRoom := getEventIfVisible(rc.ctx, rc.rsAPI, eventID, rc.userID)
+func (rc *reqCtx) MSC2836EventRelationships(eventID string, srv gomatrixserverlib.ServerName, ver gomatrixserverlib.RoomVersion) (*gomatrixserverlib.MSC2836EventRelationshipsResponse, error) {
-	if event != nil && joinedToRoom {
+	res, err := rc.fsAPI.MSC2836EventRelationships(rc.ctx, srv, gomatrixserverlib.MSC2836EventRelationshipsRequest{
-		return event
+		EventID:     eventID,
+		DepthFirst:  rc.req.DepthFirst,
+		Direction:   rc.req.Direction,
+		Limit:       rc.req.Limit,
+		MaxBreadth:  rc.req.MaxBreadth,
+		MaxDepth:    rc.req.MaxDepth,
+		RecentFirst: rc.req.RecentFirst,
+	}, ver)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Error("Failed to call MSC2836EventRelationships")
+		return nil, err
 	}
-	// either we don't have the event or we aren't joined to the room, regardless we should try joining if auto join is enabled
+	return &res, nil
-	if !rc.req.AutoJoin {
+
-		return nil
-	}
-	// if we're doing this on behalf of a random server don't auto-join rooms regardless of what the request says
-	if rc.isFederatedRequest {
-		return nil
-	}
-	roomID := claimedRoomID
-	var servers []gomatrixserverlib.ServerName
-	if event != nil {
-		roomID = event.RoomID()
-	}
-	for _, s := range claimedServers {
-		servers = append(servers, gomatrixserverlib.ServerName(s))
-	}
-	var joinRes roomserver.PerformJoinResponse
-	rc.rsAPI.PerformJoin(rc.ctx, &roomserver.PerformJoinRequest{
-		UserID:        rc.userID,
-		Content:       map[string]interface{}{},
-		RoomIDOrAlias: roomID,
-		ServerNames:   servers,
-	}, &joinRes)
-	if joinRes.Error != nil {
-		util.GetLogger(rc.ctx).WithError(joinRes.Error).WithField("room_id", roomID).Error("Failed to auto-join room")
-		return nil
-	}
-	if event != nil {
-		return event
-	}
-	// TODO: hit /event_relationships on the server we joined via
-	util.GetLogger(rc.ctx).Infof("joined room but need to fetch event TODO")
-	return nil
 }
 
-func getEventIfVisible(ctx context.Context, rsAPI roomserver.RoomserverInternalAPI, eventID, userID string) (*gomatrixserverlib.HeaderedEvent, bool) {
+// authorisedToSeeEvent checks that the user or server is allowed to see this event. Returns true if allowed to
-	var queryEventsRes roomserver.QueryEventsByIDResponse
+// see this request. This only needs to be done once per room at present as we just check for joined status.
-	err := rsAPI.QueryEventsByID(ctx, &roomserver.QueryEventsByIDRequest{
+func (rc *reqCtx) authorisedToSeeEvent(event *gomatrixserverlib.HeaderedEvent) bool {
-		EventIDs: []string{eventID},
+	if rc.isFederatedRequest {
-	}, &queryEventsRes)
+		// make sure the server is in this room
-	if err != nil {
+		var res fs.QueryJoinedHostServerNamesInRoomResponse
-		util.GetLogger(ctx).WithError(err).Error("getEventIfVisible: failed to QueryEventsByID")
+		err := rc.fsAPI.QueryJoinedHostServerNamesInRoom(rc.ctx, &fs.QueryJoinedHostServerNamesInRoomRequest{
-		return nil, false
+			RoomID: event.RoomID(),
+		}, &res)
+		if err != nil {
+			util.GetLogger(rc.ctx).WithError(err).Error("authorisedToSeeEvent: failed to QueryJoinedHostServerNamesInRoom")
+			return false
+		}
+		for _, srv := range res.ServerNames {
+			if srv == rc.serverName {
+				return true
+			}
+		}
+		return false
 	}
-	if len(queryEventsRes.Events) == 0 {
+	// make sure the user is in this room
-		util.GetLogger(ctx).Infof("event does not exist")
-		return nil, false // event does not exist
-	}
-	event := queryEventsRes.Events[0]
-
 	// Allow events if the member is in the room
 	// TODO: This does not honour history_visibility
 	// TODO: This does not honour m.room.create content
 	var queryMembershipRes roomserver.QueryMembershipForUserResponse
-	err = rsAPI.QueryMembershipForUser(ctx, &roomserver.QueryMembershipForUserRequest{
+	err := rc.rsAPI.QueryMembershipForUser(rc.ctx, &roomserver.QueryMembershipForUserRequest{
 		RoomID: event.RoomID(),
-		UserID: userID,
+		UserID: rc.userID,
 	}, &queryMembershipRes)
 	if err != nil {
-		util.GetLogger(ctx).WithError(err).Error("getEventIfVisible: failed to QueryMembershipForUser")
+		util.GetLogger(rc.ctx).WithError(err).Error("authorisedToSeeEvent: failed to QueryMembershipForUser")
-		return nil, false
+		return false
 	}
-	return event, queryMembershipRes.IsInRoom
+	return queryMembershipRes.IsInRoom
+}
+
+func (rc *reqCtx) getServersForEventID(eventID string) []gomatrixserverlib.ServerName {
+	if rc.req.RoomID == "" {
+		util.GetLogger(rc.ctx).WithField("event_id", eventID).Error(
+			"getServersForEventID: event exists in unknown room",
+		)
+		return nil
+	}
+	if rc.roomVersion == "" {
+		util.GetLogger(rc.ctx).WithField("event_id", eventID).Errorf(
+			"getServersForEventID: event exists in %s with unknown room version", rc.req.RoomID,
+		)
+		return nil
+	}
+	var queryRes fs.QueryJoinedHostServerNamesInRoomResponse
+	err := rc.fsAPI.QueryJoinedHostServerNamesInRoom(rc.ctx, &fs.QueryJoinedHostServerNamesInRoomRequest{
+		RoomID: rc.req.RoomID,
+	}, &queryRes)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Error("getServersForEventID: failed to QueryJoinedHostServerNamesInRoom")
+		return nil
+	}
+	// query up to 5 servers
+	serversToQuery := queryRes.ServerNames
+	if len(serversToQuery) > 5 {
+		serversToQuery = serversToQuery[:5]
+	}
+	return serversToQuery
+}
+
+func (rc *reqCtx) remoteEventRelationships(eventID string) *gomatrixserverlib.MSC2836EventRelationshipsResponse {
+	if rc.isFederatedRequest {
+		return nil // we don't query remote servers for remote requests
+	}
+	serversToQuery := rc.getServersForEventID(eventID)
+	var res *gomatrixserverlib.MSC2836EventRelationshipsResponse
+	var err error
+	for _, srv := range serversToQuery {
+		res, err = rc.MSC2836EventRelationships(eventID, srv, rc.roomVersion)
+		if err != nil {
+			util.GetLogger(rc.ctx).WithError(err).WithField("server", srv).Error("remoteEventRelationships: failed to call MSC2836EventRelationships")
+		} else {
+			break
+		}
+	}
+	return res
+}
+
+// lookForEvent returns the event for the event ID given, by trying to query remote servers
+// if the event ID is unknown via /event_relationships.
+func (rc *reqCtx) lookForEvent(eventID string) *gomatrixserverlib.HeaderedEvent {
+	event := rc.getLocalEvent(eventID)
+	if event == nil {
+		queryRes := rc.remoteEventRelationships(eventID)
+		if queryRes != nil {
+			// inject all the events into the roomserver then return the event in question
+			rc.injectResponseToRoomserver(queryRes)
+			for _, ev := range queryRes.Events {
+				if ev.EventID() == eventID && rc.req.RoomID == ev.RoomID() {
+					return ev.Headered(ev.Version())
+				}
+			}
+		}
+	} else if rc.hasUnexploredChildren(eventID) {
+		// we have the local event but we may need to do a remote hit anyway if we are exploring the thread and have unknown children.
+		// If we don't do this then we risk never fetching the children.
+		queryRes := rc.remoteEventRelationships(eventID)
+		if queryRes != nil {
+			rc.injectResponseToRoomserver(queryRes)
+			err := rc.db.MarkChildrenExplored(context.Background(), eventID)
+			if err != nil {
+				util.GetLogger(rc.ctx).WithError(err).Warnf("failed to mark children of %s as explored", eventID)
+			}
+		}
+	}
+	if rc.req.RoomID == event.RoomID() {
+		return event
+	}
+	return nil
+}
+
+func (rc *reqCtx) getLocalEvent(eventID string) *gomatrixserverlib.HeaderedEvent {
+	var queryEventsRes roomserver.QueryEventsByIDResponse
+	err := rc.rsAPI.QueryEventsByID(rc.ctx, &roomserver.QueryEventsByIDRequest{
+		EventIDs: []string{eventID},
+	}, &queryEventsRes)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Error("getLocalEvent: failed to QueryEventsByID")
+		return nil
+	}
+	if len(queryEventsRes.Events) == 0 {
+		util.GetLogger(rc.ctx).WithField("event_id", eventID).Infof("getLocalEvent: event does not exist")
+		return nil // event does not exist
+	}
+	return queryEventsRes.Events[0]
+}
+
+// injectResponseToRoomserver injects the events
+// into the roomserver as KindOutlier, with auth chains.
+func (rc *reqCtx) injectResponseToRoomserver(res *gomatrixserverlib.MSC2836EventRelationshipsResponse) {
+	var stateEvents []*gomatrixserverlib.Event
+	var messageEvents []*gomatrixserverlib.Event
+	for _, ev := range res.Events {
+		if ev.StateKey() != nil {
+			stateEvents = append(stateEvents, ev)
+		} else {
+			messageEvents = append(messageEvents, ev)
+		}
+	}
+	respState := gomatrixserverlib.RespState{
+		AuthEvents:  res.AuthChain,
+		StateEvents: stateEvents,
+	}
+	eventsInOrder, err := respState.Events()
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Error("failed to calculate order to send events in MSC2836EventRelationshipsResponse")
+		return
+	}
+	// everything gets sent as an outlier because auth chain events may be disjoint from the DAG
+	// as may the threaded events.
+	var ires []roomserver.InputRoomEvent
+	for _, outlier := range append(eventsInOrder, messageEvents...) {
+		ires = append(ires, roomserver.InputRoomEvent{
+			Kind:         roomserver.KindOutlier,
+			Event:        outlier.Headered(outlier.Version()),
+			AuthEventIDs: outlier.AuthEventIDs(),
+		})
+	}
+	// we've got the data by this point so use a background context
+	err = roomserver.SendInputRoomEvents(context.Background(), rc.rsAPI, ires)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Error("failed to inject MSC2836EventRelationshipsResponse into the roomserver")
+	}
+	// update the child count / hash columns for these nodes. We need to do this here because not all events will make it
+	// through to the KindNewEventPersisted hook because the roomserver will ignore duplicates. Duplicates have meaning though
+	// as the `unsigned` field may differ (if the number of children changes).
+	for _, ev := range ires {
+		err = rc.db.UpdateChildMetadata(context.Background(), ev.Event)
+		if err != nil {
+			util.GetLogger(rc.ctx).WithError(err).WithField("event_id", ev.Event.EventID()).Warn("failed to update child metadata for event")
+		}
+	}
+}
+
+func (rc *reqCtx) addChildMetadata(ev *gomatrixserverlib.HeaderedEvent) {
+	count, hash := rc.getChildMetadata(ev.EventID())
+	if count == 0 {
+		return
+	}
+	err := ev.SetUnsignedField("children_hash", gomatrixserverlib.Base64Bytes(hash))
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Warn("Failed to set children_hash")
+	}
+	err = ev.SetUnsignedField("children", map[string]int{
+		constRelType: count,
+	})
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Warn("Failed to set children count")
+	}
+}
+
+func (rc *reqCtx) getChildMetadata(eventID string) (count int, hash []byte) {
+	children, err := rc.db.ChildrenForParent(rc.ctx, eventID, constRelType, false)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).Warn("Failed to get ChildrenForParent for getting child metadata")
+		return
+	}
+	if len(children) == 0 {
+		return
+	}
+	// sort it lexiographically
+	sort.Slice(children, func(i, j int) bool {
+		return children[i].EventID < children[j].EventID
+	})
+	// hash it
+	var eventIDs strings.Builder
+	for _, c := range children {
+		_, _ = eventIDs.WriteString(c.EventID)
+	}
+	hashValBytes := sha256.Sum256([]byte(eventIDs.String()))
+
+	count = len(children)
+	hash = hashValBytes[:]
+	return
+}
+
+// hasUnexploredChildren returns true if this event has unexplored children.
+// "An event has unexplored children if the `unsigned` child count on the parent does not match
+// how many children the server believes the parent to have. In addition, if the counts match but
+// the hashes do not match, then the event is unexplored."
+func (rc *reqCtx) hasUnexploredChildren(eventID string) bool {
+	if rc.isFederatedRequest {
+		return false // we only explore children for clients, not servers.
+	}
+	// extract largest child count from event
+	eventCount, eventHash, explored, err := rc.db.ChildMetadata(rc.ctx, eventID)
+	if err != nil {
+		util.GetLogger(rc.ctx).WithError(err).WithField("event_id", eventID).Warn(
+			"failed to get ChildMetadata from db",
+		)
+		return false
+	}
+	// if there are no recorded children then we know we have >= children.
+	// if the event has already been explored (read: we hit /event_relationships successfully)
+	// then don't do it again. We'll only re-do this if we get an even bigger children count,
+	// see Database.UpdateChildMetadata
+	if eventCount == 0 || explored {
+		return false // short-circuit
+	}
+
+	// calculate child count for event
+	calcCount, calcHash := rc.getChildMetadata(eventID)
+
+	if eventCount < calcCount {
+		return false // we have more children
+	} else if eventCount > calcCount {
+		return true // the event has more children than we know about
+	}
+	// we have the same count, so a mismatched hash means some children are different
+	return !bytes.Equal(eventHash, calcHash)
 }
 
 type walkInfo struct {
@@ -453,9 +758,9 @@ type walker struct {
 
 // WalkFrom the event ID given
 func (w *walker) WalkFrom(eventID string) (limited bool, err error) {
-	children, err := w.db.ChildrenForParent(w.ctx, eventID, constRelType, w.req.RecentFirst)
+	children, err := w.childrenForParent(eventID)
 	if err != nil {
-		util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() ChildrenForParent failed, cannot walk")
+		util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() childrenForParent failed, cannot walk")
 		return false, err
 	}
 	var next *walkInfo
@@ -467,9 +772,9 @@ func (w *walker) WalkFrom(eventID string) (limited bool, err error) {
 			return true, nil
 		}
 		// find the children's children
-		children, err = w.db.ChildrenForParent(w.ctx, next.EventID, constRelType, w.req.RecentFirst)
+		children, err = w.childrenForParent(next.EventID)
 		if err != nil {
-			util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() ChildrenForParent failed, cannot walk")
+			util.GetLogger(w.ctx).WithError(err).Error("WalkFrom() childrenForParent failed, cannot walk")
 			return false, err
 		}
 		toWalk = w.addChildren(toWalk, children, next.Depth+1)
@@ -528,3 +833,20 @@ func (w *walker) nextChild(toWalk []walkInfo) (*walkInfo, []walkInfo) {
 	child, toWalk = toWalk[0], toWalk[1:]
 	return &child, toWalk
 }
+
+// childrenForParent returns the children events for this event ID, honouring the direction: up|down flags
+// meaning this can actually be returning the parent for the event instead of the children.
+func (w *walker) childrenForParent(eventID string) ([]eventInfo, error) {
+	if w.req.Direction == "down" {
+		return w.db.ChildrenForParent(w.ctx, eventID, constRelType, w.req.RecentFirst)
+	}
+	// find the event to pull out the parent
+	ei, err := w.db.ParentForChild(w.ctx, eventID, constRelType)
+	if err != nil {
+		return nil, err
+	}
+	if ei != nil {
+		return []eventInfo{*ei}, nil
+	}
+	return nil, nil
+}

setup/mscs/msc2836/msc2836_test.go

@@ -4,10 +4,14 @@ import (
 	"bytes"
 	"context"
 	"crypto/ed25519"
+	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"sort"
+	"strings"
 	"testing"
 	"time"
 
@@ -43,9 +47,7 @@ func TestMSC2836(t *testing.T) {
 	alice := "@alice:localhost"
 	bob := "@bob:localhost"
 	charlie := "@charlie:localhost"
-	roomIDA := "!alice:localhost"
+	roomID := "!alice:localhost"
-	roomIDB := "!bob:localhost"
-	roomIDC := "!charlie:localhost"
 	// give access tokens to all three users
 	nopUserAPI := &testUserAPI{
 		accessTokens: make(map[string]userapi.Device),
@@ -66,7 +68,7 @@ func TestMSC2836(t *testing.T) {
 		UserID:      charlie,
 	}
 	eventA := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDA,
+		RoomID: roomID,
 		Sender: alice,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -74,7 +76,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventB := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDB,
+		RoomID: roomID,
 		Sender: bob,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -86,7 +88,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventC := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDB,
+		RoomID: roomID,
 		Sender: bob,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -98,7 +100,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventD := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDA,
+		RoomID: roomID,
 		Sender: alice,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -110,7 +112,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventE := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDB,
+		RoomID: roomID,
 		Sender: bob,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -122,7 +124,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventF := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDC,
+		RoomID: roomID,
 		Sender: charlie,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -134,7 +136,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventG := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDA,
+		RoomID: roomID,
 		Sender: alice,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -146,7 +148,7 @@ func TestMSC2836(t *testing.T) {
 		},
 	})
 	eventH := mustCreateEvent(t, fledglingEvent{
-		RoomID: roomIDB,
+		RoomID: roomID,
 		Sender: bob,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -160,9 +162,9 @@ func TestMSC2836(t *testing.T) {
 	// make everyone joined to each other's rooms
 	nopRsAPI := &testRoomserverAPI{
 		userToJoinedRooms: map[string][]string{
-			alice:   []string{roomIDA, roomIDB, roomIDC},
+			alice:   []string{roomID},
-			bob:     []string{roomIDA, roomIDB, roomIDC},
+			bob:     []string{roomID},
-			charlie: []string{roomIDA, roomIDB, roomIDC},
+			charlie: []string{roomID},
 		},
 		events: map[string]*gomatrixserverlib.HeaderedEvent{
 			eventA.EventID(): eventA,
@@ -198,21 +200,6 @@ func TestMSC2836(t *testing.T) {
 			"include_parent": true,
 		}))
 	})
-	t.Run("omits parent if not joined to the room of parent of event", func(t *testing.T) {
-		nopUserAPI.accessTokens["frank2"] = userapi.Device{
-			AccessToken: "frank2",
-			DisplayName: "Frank2 Not In Room",
-			UserID:      "@frank2:localhost",
-		}
-		// Event B is in roomB, Event A is in roomA, so make frank2 joined to roomB
-		nopRsAPI.userToJoinedRooms["@frank2:localhost"] = []string{roomIDB}
-		body := postRelationships(t, 200, "frank2", newReq(t, map[string]interface{}{
-			"event_id":       eventB.EventID(),
-			"limit":          1,
-			"include_parent": true,
-		}))
-		assertContains(t, body, []string{eventB.EventID()})
-	})
 	t.Run("returns the parent if include_parent is true", func(t *testing.T) {
 		body := postRelationships(t, 200, "alice", newReq(t, map[string]interface{}{
 			"event_id":       eventB.EventID(),
@@ -349,6 +336,39 @@ func TestMSC2836(t *testing.T) {
 		}))
 		assertContains(t, body, []string{eventB.EventID(), eventC.EventID(), eventD.EventID(), eventE.EventID(), eventF.EventID(), eventG.EventID(), eventH.EventID()})
 	})
+	t.Run("can navigate up the graph with direction: up", func(t *testing.T) {
+		//   A4
+		//   |
+		//   B3
+		//  / \
+		// C   D2
+		//    /| \
+		//   E F1 G
+		//   |
+		//   H
+		body := postRelationships(t, 200, "alice", newReq(t, map[string]interface{}{
+			"event_id":     eventF.EventID(),
+			"recent_first": false,
+			"depth_first":  true,
+			"direction":    "up",
+		}))
+		assertContains(t, body, []string{eventF.EventID(), eventD.EventID(), eventB.EventID(), eventA.EventID()})
+	})
+	t.Run("includes children and children_hash in unsigned", func(t *testing.T) {
+		body := postRelationships(t, 200, "alice", newReq(t, map[string]interface{}{
+			"event_id":     eventB.EventID(),
+			"recent_first": false,
+			"depth_first":  false,
+			"limit":        3,
+		}))
+		// event B has C,D as children
+		// event C has no children
+		// event D has 3 children (not included in response)
+		assertContains(t, body, []string{eventB.EventID(), eventC.EventID(), eventD.EventID()})
+		assertUnsignedChildren(t, body.Events[0], "m.reference", 2, []string{eventC.EventID(), eventD.EventID()})
+		assertUnsignedChildren(t, body.Events[1], "", 0, nil)
+		assertUnsignedChildren(t, body.Events[2], "m.reference", 3, []string{eventE.EventID(), eventF.EventID(), eventG.EventID()})
+	})
 }
 
 // TODO: TestMSC2836TerminatesLoops (short and long)
@@ -411,8 +431,12 @@ func postRelationships(t *testing.T, expectCode int, accessToken string, req *ms
 	}
 	if res.StatusCode == 200 {
 		var result msc2836.EventRelationshipResponse
-		if err := json.NewDecoder(res.Body).Decode(&result); err != nil {
+		body, err := ioutil.ReadAll(res.Body)
-			t.Fatalf("response 200 OK but failed to deserialise JSON : %s", err)
+		if err != nil {
+			t.Fatalf("response 200 OK but failed to read response body: %s", err)
+		}
+		if err := json.Unmarshal(body, &result); err != nil {
+			t.Fatalf("response 200 OK but failed to deserialise JSON : %s\nbody: %s", err, string(body))
 		}
 		return &result
 	}
@@ -435,6 +459,43 @@ func assertContains(t *testing.T, result *msc2836.EventRelationshipResponse, wan
 	}
 }
 
+func assertUnsignedChildren(t *testing.T, ev gomatrixserverlib.ClientEvent, relType string, wantCount int, childrenEventIDs []string) {
+	t.Helper()
+	unsigned := struct {
+		Children map[string]int `json:"children"`
+		Hash     string         `json:"children_hash"`
+	}{}
+	if err := json.Unmarshal(ev.Unsigned, &unsigned); err != nil {
+		if wantCount == 0 {
+			return // no children so possible there is no unsigned field at all
+		}
+		t.Fatalf("Failed to unmarshal unsigned field: %s", err)
+	}
+	// zero checks
+	if wantCount == 0 {
+		if len(unsigned.Children) != 0 || unsigned.Hash != "" {
+			t.Fatalf("want 0 children but got unsigned fields %+v", unsigned)
+		}
+		return
+	}
+	gotCount := unsigned.Children[relType]
+	if gotCount != wantCount {
+		t.Errorf("Got %d count, want %d count for rel_type %s", gotCount, wantCount, relType)
+	}
+	// work out the hash
+	sort.Strings(childrenEventIDs)
+	var b strings.Builder
+	for _, s := range childrenEventIDs {
+		b.WriteString(s)
+	}
+	t.Logf("hashing %s", b.String())
+	hashValBytes := sha256.Sum256([]byte(b.String()))
+	wantHash := base64.RawStdEncoding.EncodeToString(hashValBytes[:])
+	if wantHash != unsigned.Hash {
+		t.Errorf("Got unsigned hash %s want hash %s", unsigned.Hash, wantHash)
+	}
+}
+
 type testUserAPI struct {
 	accessTokens map[string]userapi.Device
 }

setup/mscs/msc2836/storage.go

@@ -1,20 +1,22 @@
 package msc2836
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
+	"encoding/base64"
 	"encoding/json"
 
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 )
 
 type eventInfo struct {
 	EventID        string
 	OriginServerTS gomatrixserverlib.Timestamp
 	RoomID         string
-	Servers        []string
 }
 
 type Database interface {
@@ -25,6 +27,21 @@ type Database interface {
 	// provided `relType`. The returned slice is sorted by origin_server_ts according to whether
 	// `recentFirst` is true or false.
 	ChildrenForParent(ctx context.Context, eventID, relType string, recentFirst bool) ([]eventInfo, error)
+	// ParentForChild returns the parent event for the given child `eventID`. The eventInfo should be nil if
+	// there is no parent for this child event, with no error. The parent eventInfo can be missing the
+	// timestamp if the event is not known to the server.
+	ParentForChild(ctx context.Context, eventID, relType string) (*eventInfo, error)
+	// UpdateChildMetadata persists the children_count and children_hash from this event if and only if
+	// the count is greater than what was previously there. If the count is updated, the event will be
+	// updated to be unexplored.
+	UpdateChildMetadata(ctx context.Context, ev *gomatrixserverlib.HeaderedEvent) error
+	// ChildMetadata returns the children_count and children_hash for the event ID in question.
+	// Also returns the `explored` flag, which is set to true when MarkChildrenExplored is called and is set
+	// back to `false` when a larger count is inserted via UpdateChildMetadata.
+	// Returns nil error if the event ID does not exist.
+	ChildMetadata(ctx context.Context, eventID string) (count int, hash []byte, explored bool, err error)
+	// MarkChildrenExplored sets the 'explored' flag on this event to `true`.
+	MarkChildrenExplored(ctx context.Context, eventID string) error
 }
 
 type DB struct {
@@ -34,6 +51,10 @@ type DB struct {
 	insertNodeStmt                         *sql.Stmt
 	selectChildrenForParentOldestFirstStmt *sql.Stmt
 	selectChildrenForParentRecentFirstStmt *sql.Stmt
+	selectParentForChildStmt               *sql.Stmt
+	updateChildMetadataStmt                *sql.Stmt
+	selectChildMetadataStmt                *sql.Stmt
+	updateChildMetadataExploredStmt        *sql.Stmt
 }
 
 // NewDatabase loads the database for msc2836
@@ -65,19 +86,26 @@ func newPostgresDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	CREATE TABLE IF NOT EXISTS msc2836_nodes (
 		event_id TEXT PRIMARY KEY NOT NULL,
 		origin_server_ts BIGINT NOT NULL,
-		room_id TEXT NOT NULL
+		room_id TEXT NOT NULL,
+		unsigned_children_count BIGINT NOT NULL,
+		unsigned_children_hash TEXT NOT NULL,
+		explored SMALLINT NOT NULL
 	);
 	`)
 	if err != nil {
 		return nil, err
 	}
 	if d.insertEdgeStmt, err = d.db.Prepare(`
-		INSERT INTO msc2836_edges(parent_event_id, child_event_id, rel_type, parent_room_id, parent_servers) VALUES($1, $2, $3, $4, $5) ON CONFLICT DO NOTHING
+		INSERT INTO msc2836_edges(parent_event_id, child_event_id, rel_type, parent_room_id, parent_servers)
+		VALUES($1, $2, $3, $4, $5)
+		ON CONFLICT DO NOTHING
 	`); err != nil {
 		return nil, err
 	}
 	if d.insertNodeStmt, err = d.db.Prepare(`
-		INSERT INTO msc2836_nodes(event_id, origin_server_ts, room_id) VALUES($1, $2, $3) ON CONFLICT DO NOTHING
+		INSERT INTO msc2836_nodes(event_id, origin_server_ts, room_id, unsigned_children_count, unsigned_children_hash, explored)
+		VALUES($1, $2, $3, $4, $5, $6)
+		ON CONFLICT DO NOTHING
 	`); err != nil {
 		return nil, err
 	}
@@ -93,6 +121,27 @@ func newPostgresDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	if d.selectChildrenForParentRecentFirstStmt, err = d.db.Prepare(selectChildrenQuery + "DESC"); err != nil {
 		return nil, err
 	}
+	if d.selectParentForChildStmt, err = d.db.Prepare(`
+		SELECT parent_event_id, parent_room_id FROM msc2836_edges
+		WHERE child_event_id = $1 AND rel_type = $2
+	`); err != nil {
+		return nil, err
+	}
+	if d.updateChildMetadataStmt, err = d.db.Prepare(`
+		UPDATE msc2836_nodes SET unsigned_children_count=$1, unsigned_children_hash=$2, explored=$3 WHERE event_id=$4
+	`); err != nil {
+		return nil, err
+	}
+	if d.selectChildMetadataStmt, err = d.db.Prepare(`
+		SELECT unsigned_children_count, unsigned_children_hash, explored FROM msc2836_nodes WHERE event_id=$1
+	`); err != nil {
+		return nil, err
+	}
+	if d.updateChildMetadataExploredStmt, err = d.db.Prepare(`
+		UPDATE msc2836_nodes SET explored=$1 WHERE event_id=$2
+	`); err != nil {
+		return nil, err
+	}
 	return &d, err
 }
 
@@ -117,19 +166,26 @@ func newSQLiteDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	CREATE TABLE IF NOT EXISTS msc2836_nodes (
 		event_id TEXT PRIMARY KEY NOT NULL,
 		origin_server_ts BIGINT NOT NULL,
-		room_id TEXT NOT NULL
+		room_id TEXT NOT NULL,
+		unsigned_children_count BIGINT NOT NULL,
+		unsigned_children_hash TEXT NOT NULL,
+		explored SMALLINT NOT NULL
 	);
 	`)
 	if err != nil {
 		return nil, err
 	}
 	if d.insertEdgeStmt, err = d.db.Prepare(`
-		INSERT INTO msc2836_edges(parent_event_id, child_event_id, rel_type, parent_room_id, parent_servers) VALUES($1, $2, $3, $4, $5) ON CONFLICT (parent_event_id, child_event_id, rel_type) DO NOTHING
+		INSERT INTO msc2836_edges(parent_event_id, child_event_id, rel_type, parent_room_id, parent_servers)
+		VALUES($1, $2, $3, $4, $5)
+		ON CONFLICT (parent_event_id, child_event_id, rel_type) DO NOTHING
 	`); err != nil {
 		return nil, err
 	}
 	if d.insertNodeStmt, err = d.db.Prepare(`
-		INSERT INTO msc2836_nodes(event_id, origin_server_ts, room_id) VALUES($1, $2, $3) ON CONFLICT DO NOTHING
+		INSERT INTO msc2836_nodes(event_id, origin_server_ts, room_id, unsigned_children_count, unsigned_children_hash, explored)
+		VALUES($1, $2, $3, $4, $5, $6)
+		ON CONFLICT DO NOTHING
 	`); err != nil {
 		return nil, err
 	}
@@ -145,6 +201,27 @@ func newSQLiteDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	if d.selectChildrenForParentRecentFirstStmt, err = d.db.Prepare(selectChildrenQuery + "DESC"); err != nil {
 		return nil, err
 	}
+	if d.selectParentForChildStmt, err = d.db.Prepare(`
+		SELECT parent_event_id, parent_room_id FROM msc2836_edges
+		WHERE child_event_id = $1 AND rel_type = $2
+	`); err != nil {
+		return nil, err
+	}
+	if d.updateChildMetadataStmt, err = d.db.Prepare(`
+		UPDATE msc2836_nodes SET unsigned_children_count=$1, unsigned_children_hash=$2, explored=$3 WHERE event_id=$4
+	`); err != nil {
+		return nil, err
+	}
+	if d.selectChildMetadataStmt, err = d.db.Prepare(`
+		SELECT unsigned_children_count, unsigned_children_hash, explored FROM msc2836_nodes WHERE event_id=$1
+	`); err != nil {
+		return nil, err
+	}
+	if d.updateChildMetadataExploredStmt, err = d.db.Prepare(`
+		UPDATE msc2836_nodes SET explored=$1 WHERE event_id=$2
+	`); err != nil {
+		return nil, err
+	}
 	return &d, nil
 }
 
@@ -158,16 +235,55 @@ func (p *DB) StoreRelation(ctx context.Context, ev *gomatrixserverlib.HeaderedEv
 	if err != nil {
 		return err
 	}
+	count, hash := extractChildMetadata(ev)
 	return p.writer.Do(p.db, nil, func(txn *sql.Tx) error {
 		_, err := txn.Stmt(p.insertEdgeStmt).ExecContext(ctx, parent, child, relType, relationRoomID, string(relationServersJSON))
 		if err != nil {
 			return err
 		}
-		_, err = txn.Stmt(p.insertNodeStmt).ExecContext(ctx, ev.EventID(), ev.OriginServerTS(), ev.RoomID())
+		util.GetLogger(ctx).Infof("StoreRelation child=%s parent=%s rel_type=%s", child, parent, relType)
+		_, err = txn.Stmt(p.insertNodeStmt).ExecContext(ctx, ev.EventID(), ev.OriginServerTS(), ev.RoomID(), count, base64.RawStdEncoding.EncodeToString(hash), 0)
 		return err
 	})
 }
 
+func (p *DB) UpdateChildMetadata(ctx context.Context, ev *gomatrixserverlib.HeaderedEvent) error {
+	eventCount, eventHash := extractChildMetadata(ev)
+	if eventCount == 0 {
+		return nil // nothing to update with
+	}
+
+	// extract current children count/hash, if they are less than the current event then update the columns and set to unexplored
+	count, hash, _, err := p.ChildMetadata(ctx, ev.EventID())
+	if err != nil {
+		return err
+	}
+	if eventCount > count || (eventCount == count && !bytes.Equal(hash, eventHash)) {
+		_, err = p.updateChildMetadataStmt.ExecContext(ctx, eventCount, base64.RawStdEncoding.EncodeToString(eventHash), 0, ev.EventID())
+		return err
+	}
+	return nil
+}
+
+func (p *DB) ChildMetadata(ctx context.Context, eventID string) (count int, hash []byte, explored bool, err error) {
+	var b64hash string
+	var exploredInt int
+	if err = p.selectChildMetadataStmt.QueryRowContext(ctx, eventID).Scan(&count, &b64hash, &exploredInt); err != nil {
+		if err == sql.ErrNoRows {
+			err = nil
+		}
+		return
+	}
+	hash, err = base64.RawStdEncoding.DecodeString(b64hash)
+	explored = exploredInt > 0
+	return
+}
+
+func (p *DB) MarkChildrenExplored(ctx context.Context, eventID string) error {
+	_, err := p.updateChildMetadataExploredStmt.ExecContext(ctx, 1, eventID)
+	return err
+}
+
 func (p *DB) ChildrenForParent(ctx context.Context, eventID, relType string, recentFirst bool) ([]eventInfo, error) {
 	var rows *sql.Rows
 	var err error
@@ -191,6 +307,17 @@ func (p *DB) ChildrenForParent(ctx context.Context, eventID, relType string, rec
 	return children, nil
 }
 
+func (p *DB) ParentForChild(ctx context.Context, eventID, relType string) (*eventInfo, error) {
+	var ei eventInfo
+	err := p.selectParentForChildStmt.QueryRowContext(ctx, eventID, relType).Scan(&ei.EventID, &ei.RoomID)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+	return &ei, nil
+}
+
 func parentChildEventIDs(ev *gomatrixserverlib.HeaderedEvent) (parent, child, relType string) {
 	if ev == nil {
 		return
@@ -224,3 +351,19 @@ func roomIDAndServers(ev *gomatrixserverlib.HeaderedEvent) (roomID string, serve
 	}
 	return body.RoomID, body.Servers
 }
+
+func extractChildMetadata(ev *gomatrixserverlib.HeaderedEvent) (count int, hash []byte) {
+	unsigned := struct {
+		Counts map[string]int                `json:"children"`
+		Hash   gomatrixserverlib.Base64Bytes `json:"children_hash"`
+	}{}
+	if err := json.Unmarshal(ev.Unsigned(), &unsigned); err != nil {
+		// expected if there is no unsigned field at all
+		return
+	}
+	for _, c := range unsigned.Counts {
+		count += c
+	}
+	hash = unsigned.Hash
+	return
+}

setup/mscs/mscs.go

@@ -16,15 +16,18 @@
 package mscs
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/matrix-org/dendrite/setup"
 	"github.com/matrix-org/dendrite/setup/mscs/msc2836"
+	"github.com/matrix-org/util"
 )
 
 // Enable MSCs - returns an error on unknown MSCs
 func Enable(base *setup.BaseDendrite, monolith *setup.Monolith) error {
 	for _, msc := range base.Cfg.MSCs.MSCs {
+		util.GetLogger(context.Background()).WithField("msc", msc).Info("Enabling MSC")
 		if err := EnableMSC(base, monolith, msc); err != nil {
 			return err
 		}

syncapi/storage/postgres/current_room_state_table.go

@@ -76,7 +76,7 @@ const selectRoomIDsWithMembershipSQL = "" +
 	"SELECT DISTINCT room_id FROM syncapi_current_room_state WHERE type = 'm.room.member' AND state_key = $1 AND membership = $2"
 
 const selectCurrentStateSQL = "" +
-	"SELECT headered_event_json FROM syncapi_current_room_state WHERE room_id = $1" +
+	"SELECT event_id, headered_event_json FROM syncapi_current_room_state WHERE room_id = $1" +
 	" AND ( $2::text[] IS NULL OR     sender  = ANY($2)  )" +
 	" AND ( $3::text[] IS NULL OR NOT(sender  = ANY($3)) )" +
 	" AND ( $4::text[] IS NULL OR     type LIKE ANY($4)  )" +
@@ -92,10 +92,10 @@ const selectStateEventSQL = "" +
 
 const selectEventsWithEventIDsSQL = "" +
 	// TODO: The session_id and transaction_id blanks are here because otherwise
-	// the rowsToStreamEvents expects there to be exactly five columns. We need to
+	// the rowsToStreamEvents expects there to be exactly six columns. We need to
 	// figure out if these really need to be in the DB, and if so, we need a
 	// better permanent fix for this. - neilalexander, 2 Jan 2020
-	"SELECT added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
+	"SELECT event_id, added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
 	" FROM syncapi_current_room_state WHERE event_id = ANY($1)"
 
 type currentRoomStateStatements struct {
@@ -278,13 +278,14 @@ func (s *currentRoomStateStatements) SelectEventsWithEventIDs(
 func rowsToEvents(rows *sql.Rows) ([]*gomatrixserverlib.HeaderedEvent, error) {
 	result := []*gomatrixserverlib.HeaderedEvent{}
 	for rows.Next() {
+		var eventID string
 		var eventBytes []byte
-		if err := rows.Scan(&eventBytes); err != nil {
+		if err := rows.Scan(&eventID, &eventBytes); err != nil {
 			return nil, err
 		}
 		// TODO: Handle redacted events
 		var ev gomatrixserverlib.HeaderedEvent
-		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+		if err := ev.UnmarshalJSONWithEventID(eventBytes, eventID); err != nil {
 			return nil, err
 		}
 		result = append(result, &ev)

syncapi/storage/postgres/output_room_events_table.go

@@ -79,20 +79,20 @@ const insertEventSQL = "" +
 	"RETURNING id"
 
 const selectEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events WHERE event_id = ANY($1)"
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events WHERE event_id = ANY($1)"
 
 const selectRecentEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id DESC LIMIT $4"
 
 const selectRecentEventsForSyncSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3 AND exclude_from_sync = FALSE" +
 	" ORDER BY id DESC LIMIT $4"
 
 const selectEarlyEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id ASC LIMIT $4"
 
@@ -413,6 +413,7 @@ func rowsToStreamEvents(rows *sql.Rows) ([]types.StreamEvent, error) {
 	var result []types.StreamEvent
 	for rows.Next() {
 		var (
+			eventID         string
 			streamPos       types.StreamPosition
 			eventBytes      []byte
 			excludeFromSync bool
@@ -420,12 +421,12 @@ func rowsToStreamEvents(rows *sql.Rows) ([]types.StreamEvent, error) {
 			txnID           *string
 			transactionID   *api.TransactionID
 		)
-		if err := rows.Scan(&streamPos, &eventBytes, &sessionID, &excludeFromSync, &txnID); err != nil {
+		if err := rows.Scan(&eventID, &streamPos, &eventBytes, &sessionID, &excludeFromSync, &txnID); err != nil {
 			return nil, err
 		}
 		// TODO: Handle redacted events
 		var ev gomatrixserverlib.HeaderedEvent
-		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+		if err := ev.UnmarshalJSONWithEventID(eventBytes, eventID); err != nil {
 			return nil, err
 		}
 

syncapi/storage/shared/syncserver.go

@@ -31,6 +31,7 @@ import (
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/dendrite/syncapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/sirupsen/logrus"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -514,25 +515,28 @@ func (d *Database) addPDUDeltaToResponse(
 		deltas, joinedRoomIDs, err = d.getStateDeltas(
 			ctx, &device, txn, r, device.UserID, &stateFilter,
 		)
+		if err != nil {
+			return nil, fmt.Errorf("d.getStateDeltas: %w", err)
+		}
 	} else {
 		deltas, joinedRoomIDs, err = d.getStateDeltasForFullStateSync(
 			ctx, &device, txn, r, device.UserID, &stateFilter,
 		)
-	}
+		if err != nil {
-	if err != nil {
+			return nil, fmt.Errorf("d.getStateDeltasForFullStateSync: %w", err)
-		return nil, err
+		}
 	}
 
 	for _, delta := range deltas {
 		err = d.addRoomDeltaToResponse(ctx, &device, txn, r, delta, numRecentEventsPerRoom, res)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("d.addRoomDeltaToResponse: %w", err)
 		}
 	}
 
 	// TODO: This should be done in getStateDeltas
 	if err = d.addInvitesToResponse(ctx, txn, device.UserID, r, res); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("d.addInvitesToResponse: %w", err)
 	}
 
 	succeeded = true
@@ -1126,7 +1130,13 @@ func (d *Database) fetchMissingStateEvents(
 		return nil, err
 	}
 	if len(stateEvents) != len(missing) {
-		return nil, fmt.Errorf("failed to map all event IDs to events: (got %d, wanted %d)", len(stateEvents), len(missing))
+		logrus.WithContext(ctx).Warnf("Failed to map all event IDs to events (got %d, wanted %d)", len(stateEvents), len(missing))
+
+		// TODO: Why is this happening? It's probably the roomserver. Uncomment
+		// this error again when we work out what it is and fix it, otherwise we
+		// just end up returning lots of 500s to the client and that breaks
+		// pretty much everything, rather than just sending what we have.
+		//return nil, fmt.Errorf("failed to map all event IDs to events: (got %d, wanted %d)", len(stateEvents), len(missing))
 	}
 	events = append(events, stateEvents...)
 	return events, nil

syncapi/storage/sqlite3/current_room_state_table.go

@@ -64,7 +64,7 @@ const selectRoomIDsWithMembershipSQL = "" +
 	"SELECT DISTINCT room_id FROM syncapi_current_room_state WHERE type = 'm.room.member' AND state_key = $1 AND membership = $2"
 
 const selectCurrentStateSQL = "" +
-	"SELECT headered_event_json FROM syncapi_current_room_state WHERE room_id = $1" +
+	"SELECT event_id, headered_event_json FROM syncapi_current_room_state WHERE room_id = $1" +
 	" AND ( $2 IS NULL OR     sender IN ($2)  )" +
 	" AND ( $3 IS NULL OR NOT(sender IN ($3)) )" +
 	" AND ( $4 IS NULL OR     type   IN ($4)  )" +
@@ -80,10 +80,10 @@ const selectStateEventSQL = "" +
 
 const selectEventsWithEventIDsSQL = "" +
 	// TODO: The session_id and transaction_id blanks are here because otherwise
-	// the rowsToStreamEvents expects there to be exactly five columns. We need to
+	// the rowsToStreamEvents expects there to be exactly six columns. We need to
 	// figure out if these really need to be in the DB, and if so, we need a
 	// better permanent fix for this. - neilalexander, 2 Jan 2020
-	"SELECT added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
+	"SELECT event_id, added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
 	" FROM syncapi_current_room_state WHERE event_id IN ($1)"
 
 type currentRoomStateStatements struct {
@@ -289,13 +289,14 @@ func (s *currentRoomStateStatements) SelectEventsWithEventIDs(
 func rowsToEvents(rows *sql.Rows) ([]*gomatrixserverlib.HeaderedEvent, error) {
 	result := []*gomatrixserverlib.HeaderedEvent{}
 	for rows.Next() {
+		var eventID string
 		var eventBytes []byte
-		if err := rows.Scan(&eventBytes); err != nil {
+		if err := rows.Scan(&eventID, &eventBytes); err != nil {
 			return nil, err
 		}
 		// TODO: Handle redacted events
 		var ev gomatrixserverlib.HeaderedEvent
-		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+		if err := ev.UnmarshalJSONWithEventID(eventBytes, eventID); err != nil {
 			return nil, err
 		}
 		result = append(result, &ev)

syncapi/storage/sqlite3/output_room_events_table.go

@@ -56,20 +56,20 @@ const insertEventSQL = "" +
 	"ON CONFLICT (event_id) DO UPDATE SET exclude_from_sync = $13"
 
 const selectEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events WHERE event_id = $1"
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events WHERE event_id = $1"
 
 const selectRecentEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id DESC LIMIT $4"
 
 const selectRecentEventsForSyncSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3 AND exclude_from_sync = FALSE" +
 	" ORDER BY id DESC LIMIT $4"
 
 const selectEarlyEventsSQL = "" +
-	"SELECT id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
+	"SELECT event_id, id, headered_event_json, session_id, exclude_from_sync, transaction_id FROM syncapi_output_room_events" +
 	" WHERE room_id = $1 AND id > $2 AND id <= $3" +
 	" ORDER BY id ASC LIMIT $4"
 
@@ -428,6 +428,7 @@ func rowsToStreamEvents(rows *sql.Rows) ([]types.StreamEvent, error) {
 	var result []types.StreamEvent
 	for rows.Next() {
 		var (
+			eventID         string
 			streamPos       types.StreamPosition
 			eventBytes      []byte
 			excludeFromSync bool
@@ -435,12 +436,12 @@ func rowsToStreamEvents(rows *sql.Rows) ([]types.StreamEvent, error) {
 			txnID           *string
 			transactionID   *api.TransactionID
 		)
-		if err := rows.Scan(&streamPos, &eventBytes, &sessionID, &excludeFromSync, &txnID); err != nil {
+		if err := rows.Scan(&eventID, &streamPos, &eventBytes, &sessionID, &excludeFromSync, &txnID); err != nil {
 			return nil, err
 		}
 		// TODO: Handle redacted events
 		var ev gomatrixserverlib.HeaderedEvent
-		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+		if err := ev.UnmarshalJSONWithEventID(eventBytes, eventID); err != nil {
 			return nil, err
 		}
 

sytest-blacklist

@@ -63,4 +63,7 @@ If user leaves room, remote user changes device and rejoins we see update in /sy
 A prev_batch token from incremental sync can be used in the v1 messages API
 
 # Blacklisted due to flakiness
-Forgotten room messages cannot be paginated
+Forgotten room messages cannot be paginated
+
+# Blacklisted due to flakiness
+Can re-join room if re-invited

sytest-whitelist

@@ -501,6 +501,5 @@ Can get rooms/{roomId}/state for a departed room (SPEC-216)
 Users cannot set notifications powerlevel higher than their own
 Forgetting room does not show up in v2 /sync
 Can forget room you've been kicked from
-Can re-join room if re-invited
 /whois
 /joined_members return joined members