Use `IsBlacklistedOrBackingOff` to determine if we should try to fetch devices (#3254)

Use `IsBlacklistedOrBackingOff` from the federation API to check if we
should fetch devices.

To reduce back pressure, we now only queue retrying servers if there's
space in the channel.

20 files changed, 212 insertions, 90 deletions

diff --git a/appservice/appservice_test.go b/appservice/appservice_test.go
index bbdeb47d..eca63371 100644
--- a/appservice/appservice_test.go
+++ b/appservice/appservice_test.go
@@ -14,6 +14,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/stretchr/testify/assert"
 
 	"github.com/matrix-org/dendrite/appservice"
@@ -32,6 +33,10 @@ import (
 	"github.com/matrix-org/dendrite/test/testrig"
 )
 
+var testIsBlacklistedOrBackingOff = func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+	return &statistics.ServerStatistics{}, nil
+}
+
 func TestAppserviceInternalAPI(t *testing.T) {
 
 	// Set expected results
@@ -144,7 +149,7 @@ func TestAppserviceInternalAPI(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(ctx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(ctx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		asAPI := appservice.NewInternalAPI(ctx, cfg, &natsInstance, usrAPI, rsAPI)
 
 		runCases(t, asAPI)
@@ -239,7 +244,7 @@ func TestAppserviceInternalAPI_UnixSocket_Simple(t *testing.T) {
 	cm := sqlutil.NewConnectionManager(ctx, cfg.Global.DatabaseOptions)
 	rsAPI := roomserver.NewInternalAPI(ctx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 	rsAPI.SetFederationAPI(nil, nil)
-	usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+	usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 	asAPI := appservice.NewInternalAPI(ctx, cfg, &natsInstance, usrAPI, rsAPI)
 
 	t.Run("UserIDExists", func(t *testing.T) {
@@ -378,7 +383,7 @@ func TestRoomserverConsumerOneInvite(t *testing.T) {
 		// Create required internal APIs
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
+		usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		// start the consumer
 		appservice.NewInternalAPI(processCtx, cfg, natsInstance, usrAPI, rsAPI)
 
diff --git a/build/dendritejs-pinecone/main.go b/build/dendritejs-pinecone/main.go
index d3d5f59f..6acc93c7 100644
--- a/build/dendritejs-pinecone/main.go
+++ b/build/dendritejs-pinecone/main.go
@@ -191,13 +191,13 @@ func startup() {
 	serverKeyAPI := &signing.YggdrasilKeys{}
 	keyRing := serverKeyAPI.KeyRing()
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
+	fedSenderAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, federation, rsAPI, caches, keyRing, true)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics, fedSenderAPI.IsBlacklistedOrBackingOff)
 
 	asQuery := appservice.NewInternalAPI(
 		processCtx, cfg, &natsInstance, userAPI, rsAPI,
 	)
 	rsAPI.SetAppserviceAPI(asQuery)
-	fedSenderAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, federation, rsAPI, caches, keyRing, true)
 	rsAPI.SetFederationAPI(fedSenderAPI, keyRing)
 
 	monolith := setup.Monolith{
diff --git a/build/gobind-yggdrasil/monolith.go b/build/gobind-yggdrasil/monolith.go
index 791ad261..2b227d37 100644
--- a/build/gobind-yggdrasil/monolith.go
+++ b/build/gobind-yggdrasil/monolith.go
@@ -216,7 +216,7 @@ func (m *DendriteMonolith) Start() {
 		processCtx, cfg, cm, &natsInstance, federation, rsAPI, caches, keyRing, true,
 	)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics, fsAPI.IsBlacklistedOrBackingOff)
 
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
diff --git a/clientapi/admin_test.go b/clientapi/admin_test.go
index b228dd93..f0e5f004 100644
--- a/clientapi/admin_test.go
+++ b/clientapi/admin_test.go
@@ -45,7 +45,7 @@ func TestAdminCreateToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -196,7 +196,7 @@ func TestAdminListRegistrationTokens(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -314,7 +314,7 @@ func TestAdminGetRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -415,7 +415,7 @@ func TestAdminDeleteRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -509,7 +509,7 @@ func TestAdminUpdateRegistrationToken(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 		accessTokens := map[*test.User]userDevice{
 			aliceAdmin: {},
@@ -693,7 +693,7 @@ func TestAdminResetPassword(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed for changing the password/login
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		// We mostly need the userAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -791,7 +791,7 @@ func TestPurgeRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		syncapi.AddPublicRoutes(processCtx, routers, cfg, cm, &natsInstance, userAPI, rsAPI, caches, caching.DisableMetrics)
 
 		// Create the room
@@ -863,7 +863,7 @@ func TestAdminEvacuateRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// Create the room
 		if err := api.SendEvents(ctx, rsAPI, api.KindNew, room.Events(), "test", "test", api.DoNotSendToOtherServers, nil, false); err != nil {
@@ -964,7 +964,7 @@ func TestAdminEvacuateUser(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, basepkg.CreateFederationClient(cfg, nil), rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// Create the room
 		if err := api.SendEvents(ctx, rsAPI, api.KindNew, room.Events(), "test", "test", api.DoNotSendToOtherServers, nil, false); err != nil {
@@ -1055,7 +1055,7 @@ func TestAdminMarkAsStale(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/clientapi_test.go b/clientapi/clientapi_test.go
index 2bb15fba..2ff4b650 100644
--- a/clientapi/clientapi_test.go
+++ b/clientapi/clientapi_test.go
@@ -17,6 +17,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/clientapi/routing"
 	"github.com/matrix-org/dendrite/clientapi/threepid"
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/internal/pushrules"
@@ -49,6 +50,10 @@ type userDevice struct {
 	password    string
 }
 
+var testIsBlacklistedOrBackingOff = func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+	return &statistics.ServerStatistics{}, nil
+}
+
 func TestGetPutDevices(t *testing.T) {
 	alice := test.NewUser(t)
 	bob := test.NewUser(t)
@@ -121,7 +126,7 @@ func TestGetPutDevices(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -170,7 +175,7 @@ func TestDeleteDevice(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI/ for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -275,7 +280,7 @@ func TestDeleteDevices(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI/ for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -442,7 +447,7 @@ func TestSetDisplayname(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		asPI := appservice.NewInternalAPI(processCtx, cfg, natsInstance, userAPI, rsAPI)
 
 		AddPublicRoutes(processCtx, routers, cfg, natsInstance, base.CreateFederationClient(cfg, nil), rsAPI, asPI, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -554,7 +559,7 @@ func TestSetAvatarURL(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		asPI := appservice.NewInternalAPI(processCtx, cfg, natsInstance, userAPI, rsAPI)
 
 		AddPublicRoutes(processCtx, routers, cfg, natsInstance, base.CreateFederationClient(cfg, nil), rsAPI, asPI, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -632,7 +637,7 @@ func TestTyping(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed to create accounts
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -716,7 +721,7 @@ func TestMembership(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed to create accounts
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		rsAPI.SetUserAPI(userAPI)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -955,7 +960,7 @@ func TestCapabilities(t *testing.T) {
 		// Needed to create accounts
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -1002,7 +1007,7 @@ func TestTurnserver(t *testing.T) {
 	// Needed to create accounts
 	rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 	rsAPI.SetFederationAPI(nil, nil)
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 	//rsAPI.SetUserAPI(userAPI)
 	// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 	AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -1100,7 +1105,7 @@ func Test3PID(t *testing.T) {
 		// Needed to create accounts
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		// We mostly need the rsAPI/userAPI for this test, so nil for other APIs etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
 
@@ -1276,7 +1281,7 @@ func TestPushRules(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -1663,7 +1668,7 @@ func TestKeys(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
@@ -2125,7 +2130,7 @@ func TestKeyBackup(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the rsAPI for this test, so nil for other APIs/caches etc.
 		AddPublicRoutes(processCtx, routers, cfg, &natsInstance, nil, rsAPI, nil, nil, nil, userAPI, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/routing/joinroom_test.go b/clientapi/routing/joinroom_test.go
index be3fb429..bd854efa 100644
--- a/clientapi/routing/joinroom_test.go
+++ b/clientapi/routing/joinroom_test.go
@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/jetstream"
@@ -21,6 +22,10 @@ import (
 	uapi "github.com/matrix-org/dendrite/userapi/api"
 )
 
+var testIsBlacklistedOrBackingOff = func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+	return &statistics.ServerStatistics{}, nil
+}
+
 func TestJoinRoomByIDOrAlias(t *testing.T) {
 	alice := test.NewUser(t)
 	bob := test.NewUser(t)
@@ -36,7 +41,7 @@ func TestJoinRoomByIDOrAlias(t *testing.T) {
 		natsInstance := jetstream.NATSInstance{}
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil) // creates the rs.Inputer etc
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
 		// Create the users in the userapi
diff --git a/clientapi/routing/login_test.go b/clientapi/routing/login_test.go
index 4c4fc353..1c628b19 100644
--- a/clientapi/routing/login_test.go
+++ b/clientapi/routing/login_test.go
@@ -49,7 +49,7 @@ func TestLogin(t *testing.T) {
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
 		// Needed for /login
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		// We mostly need the userAPI for this test, so nil for other APIs/caches etc.
 		Setup(routers, cfg, nil, nil, userAPI, nil, nil, nil, nil, nil, nil, nil, caching.DisableMetrics)
diff --git a/clientapi/routing/register_test.go b/clientapi/routing/register_test.go
index 69b29e9c..98455f80 100644
--- a/clientapi/routing/register_test.go
+++ b/clientapi/routing/register_test.go
@@ -416,7 +416,7 @@ func Test_register(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		for _, tc := range testCases {
 			t.Run(tc.name, func(t *testing.T) {
@@ -596,7 +596,7 @@ func TestRegisterUserWithDisplayName(t *testing.T) {
 		cm := sqlutil.NewConnectionManager(processCtx, cfg.Global.DatabaseOptions)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		deviceName, deviceID := "deviceName", "deviceID"
 		expectedDisplayName := "DisplayName"
 		response := completeRegistration(
@@ -637,7 +637,7 @@ func TestRegisterAdminUsingSharedSecret(t *testing.T) {
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 
 		expectedDisplayName := "rabbit"
 		jsonStr := []byte(`{"admin":true,"mac":"24dca3bba410e43fe64b9b5c28306693bf3baa9f","nonce":"759f047f312b99ff428b21d581256f8592b8976e58bc1b543972dc6147e529a79657605b52d7becd160ff5137f3de11975684319187e06901955f79e5a6c5a79","password":"wonderland","username":"alice","displayname":"rabbit"}`)
diff --git a/cmd/dendrite-demo-pinecone/monolith/monolith.go b/cmd/dendrite-demo-pinecone/monolith/monolith.go
index 5222d0b8..d9f44b5c 100644
--- a/cmd/dendrite-demo-pinecone/monolith/monolith.go
+++ b/cmd/dendrite-demo-pinecone/monolith/monolith.go
@@ -145,7 +145,7 @@ func (p *P2PMonolith) SetupDendrite(
 	)
 	rsAPI.SetFederationAPI(fsAPI, keyRing)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, enableMetrics)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, enableMetrics, fsAPI.IsBlacklistedOrBackingOff)
 
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
diff --git a/cmd/dendrite-demo-yggdrasil/main.go b/cmd/dendrite-demo-yggdrasil/main.go
index b0768753..1e518634 100644
--- a/cmd/dendrite-demo-yggdrasil/main.go
+++ b/cmd/dendrite-demo-yggdrasil/main.go
@@ -213,14 +213,15 @@ func main() {
 	natsInstance := jetstream.NATSInstance{}
 	rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.EnableMetrics)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics)
-
-	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
-	rsAPI.SetAppserviceAPI(asAPI)
 	fsAPI := federationapi.NewInternalAPI(
 		processCtx, cfg, cm, &natsInstance, federation, rsAPI, caches, keyRing, true,
 	)
 
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federation, caching.EnableMetrics, fsAPI.IsBlacklistedOrBackingOff)
+
+	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
+	rsAPI.SetAppserviceAPI(asAPI)
+
 	rsAPI.SetFederationAPI(fsAPI, keyRing)
 
 	monolith := setup.Monolith{
diff --git a/cmd/dendrite/main.go b/cmd/dendrite/main.go
index f38263c6..5234b750 100644
--- a/cmd/dendrite/main.go
+++ b/cmd/dendrite/main.go
@@ -162,7 +162,7 @@ func main() {
 	// dependency. Other components also need updating after their dependencies are up.
 	rsAPI.SetFederationAPI(fsAPI, keyRing)
 
-	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federationClient, caching.EnableMetrics)
+	userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, federationClient, caching.EnableMetrics, fsAPI.IsBlacklistedOrBackingOff)
 	asAPI := appservice.NewInternalAPI(processCtx, cfg, &natsInstance, userAPI, rsAPI)
 
 	rsAPI.SetAppserviceAPI(asAPI)
diff --git a/federationapi/federationapi.go b/federationapi/federationapi.go
index e148199f..e2524f66 100644
--- a/federationapi/federationapi.go
+++ b/federationapi/federationapi.go
@@ -24,7 +24,6 @@ import (
 	"github.com/matrix-org/gomatrixserverlib/fclient"
 	"github.com/sirupsen/logrus"
 
-	"github.com/matrix-org/dendrite/federationapi/api"
 	federationAPI "github.com/matrix-org/dendrite/federationapi/api"
 	"github.com/matrix-org/dendrite/federationapi/consumers"
 	"github.com/matrix-org/dendrite/federationapi/internal"
@@ -102,7 +101,7 @@ func NewInternalAPI(
 	caches *caching.Caches,
 	keyRing *gomatrixserverlib.KeyRing,
 	resetBlacklist bool,
-) api.FederationInternalAPI {
+) *internal.FederationInternalAPI {
 	cfg := &dendriteCfg.FederationAPI
 
 	federationDB, err := storage.NewDatabase(processContext.Context(), cm, &cfg.Database, caches, dendriteCfg.Global.IsLocalServerName)
diff --git a/federationapi/internal/api.go b/federationapi/internal/api.go
index 3e6f3956..67388a10 100644
--- a/federationapi/internal/api.go
+++ b/federationapi/internal/api.go
@@ -112,7 +112,7 @@ func NewFederationInternalAPI(
 	}
 }
 
-func (a *FederationInternalAPI) isBlacklistedOrBackingOff(s spec.ServerName) (*statistics.ServerStatistics, error) {
+func (a *FederationInternalAPI) IsBlacklistedOrBackingOff(s spec.ServerName) (*statistics.ServerStatistics, error) {
 	stats := a.statistics.ForServer(s)
 	if stats.Blacklisted() {
 		return stats, &api.FederationClientError{
@@ -151,7 +151,7 @@ func failBlacklistableError(err error, stats *statistics.ServerStatistics) (unti
 func (a *FederationInternalAPI) doRequestIfNotBackingOffOrBlacklisted(
 	s spec.ServerName, request func() (interface{}, error),
 ) (interface{}, error) {
-	stats, err := a.isBlacklistedOrBackingOff(s)
+	stats, err := a.IsBlacklistedOrBackingOff(s)
 	if err != nil {
 		return nil, err
 	}
diff --git a/federationapi/routing/profile_test.go b/federationapi/routing/profile_test.go
index a31b206c..ba13e07f 100644
--- a/federationapi/routing/profile_test.go
+++ b/federationapi/routing/profile_test.go
@@ -26,7 +26,6 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/cmd/dendrite-demo-yggdrasil/signing"
 	fedAPI "github.com/matrix-org/dendrite/federationapi"
-	fedInternal "github.com/matrix-org/dendrite/federationapi/internal"
 	"github.com/matrix-org/dendrite/federationapi/routing"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
@@ -67,11 +66,8 @@ func TestHandleQueryProfile(t *testing.T) {
 		keyRing := serverKeyAPI.KeyRing()
 		fedapi := fedAPI.NewInternalAPI(processCtx, cfg, cm, &natsInstance, &fedClient, nil, nil, keyRing, true)
 		userapi := fakeUserAPI{}
-		r, ok := fedapi.(*fedInternal.FederationInternalAPI)
-		if !ok {
-			panic("This is a programming error.")
-		}
-		routing.Setup(routers, cfg, nil, r, keyRing, &fedClient, &userapi, &cfg.MSCs, nil, caching.DisableMetrics)
+
+		routing.Setup(routers, cfg, nil, fedapi, keyRing, &fedClient, &userapi, &cfg.MSCs, nil, caching.DisableMetrics)
 
 		handler := fedMux.Get(routing.QueryProfileRouteName).GetHandler().ServeHTTP
 		_, sk, _ := ed25519.GenerateKey(nil)
diff --git a/federationapi/routing/query_test.go b/federationapi/routing/query_test.go
index bb14ab03..fd0894d1 100644
--- a/federationapi/routing/query_test.go
+++ b/federationapi/routing/query_test.go
@@ -25,7 +25,6 @@ import (
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/cmd/dendrite-demo-yggdrasil/signing"
 	fedAPI "github.com/matrix-org/dendrite/federationapi"
-	fedInternal "github.com/matrix-org/dendrite/federationapi/internal"
 	"github.com/matrix-org/dendrite/federationapi/routing"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
@@ -65,11 +64,8 @@ func TestHandleQueryDirectory(t *testing.T) {
 		keyRing := serverKeyAPI.KeyRing()
 		fedapi := fedAPI.NewInternalAPI(processCtx, cfg, cm, &natsInstance, &fedClient, nil, nil, keyRing, true)
 		userapi := fakeUserAPI{}
-		r, ok := fedapi.(*fedInternal.FederationInternalAPI)
-		if !ok {
-			panic("This is a programming error.")
-		}
-		routing.Setup(routers, cfg, nil, r, keyRing, &fedClient, &userapi, &cfg.MSCs, nil, caching.DisableMetrics)
+
+		routing.Setup(routers, cfg, nil, fedapi, keyRing, &fedClient, &userapi, &cfg.MSCs, nil, caching.DisableMetrics)
 
 		handler := fedMux.Get(routing.QueryDirectoryRouteName).GetHandler().ServeHTTP
 		_, sk, _ := ed25519.GenerateKey(nil)
diff --git a/federationapi/routing/send_test.go b/federationapi/routing/send_test.go
index f629479d..ff4f7bd0 100644
--- a/federationapi/routing/send_test.go
+++ b/federationapi/routing/send_test.go
@@ -23,7 +23,6 @@ import (
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/cmd/dendrite-demo-yggdrasil/signing"
 	fedAPI "github.com/matrix-org/dendrite/federationapi"
-	fedInternal "github.com/matrix-org/dendrite/federationapi/internal"
 	"github.com/matrix-org/dendrite/federationapi/routing"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
@@ -62,11 +61,8 @@ func TestHandleSend(t *testing.T) {
 		fedapi := fedAPI.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, nil, nil, nil, true)
 		serverKeyAPI := &signing.YggdrasilKeys{}
 		keyRing := serverKeyAPI.KeyRing()
-		r, ok := fedapi.(*fedInternal.FederationInternalAPI)
-		if !ok {
-			panic("This is a programming error.")
-		}
-		routing.Setup(routers, cfg, nil, r, keyRing, nil, nil, &cfg.MSCs, nil, caching.DisableMetrics)
+
+		routing.Setup(routers, cfg, nil, fedapi, keyRing, nil, nil, &cfg.MSCs, nil, caching.DisableMetrics)
 
 		handler := fedMux.Get(routing.SendRouteName).GetHandler().ServeHTTP
 		_, sk, _ := ed25519.GenerateKey(nil)
diff --git a/roomserver/roomserver_test.go b/roomserver/roomserver_test.go
index 22d27ba0..218a0d8a 100644
--- a/roomserver/roomserver_test.go
+++ b/roomserver/roomserver_test.go
@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/internal/httputil"
@@ -34,6 +35,10 @@ import (
 	"github.com/matrix-org/dendrite/test/testrig"
 )
 
+var testIsBlacklistedOrBackingOff = func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+	return &statistics.ServerStatistics{}, nil
+}
+
 type FakeQuerier struct {
 	api.QuerySenderIDAPI
 }
@@ -58,7 +63,7 @@ func TestUsers(t *testing.T) {
 		})
 
 		t.Run("kick users", func(t *testing.T) {
-			usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+			usrAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 			rsAPI.SetUserAPI(usrAPI)
 			testKickUsers(t, rsAPI, usrAPI)
 		})
@@ -258,7 +263,7 @@ func TestPurgeRoom(t *testing.T) {
 		fsAPI := federationapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, nil, rsAPI, caches, nil, true)
 		rsAPI.SetFederationAPI(fsAPI, nil)
 
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, fsAPI.IsBlacklistedOrBackingOff)
 		syncapi.AddPublicRoutes(processCtx, routers, cfg, cm, &natsInstance, userAPI, rsAPI, caches, caching.DisableMetrics)
 
 		// Create the room
@@ -1050,7 +1055,7 @@ func TestUpgrade(t *testing.T) {
 
 		rsAPI := roomserver.NewInternalAPI(processCtx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
 		rsAPI.SetFederationAPI(nil, nil)
-		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics)
+		userAPI := userapi.NewInternalAPI(processCtx, cfg, cm, &natsInstance, rsAPI, nil, caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		rsAPI.SetUserAPI(userAPI)
 
 		for _, tc := range testCases {
diff --git a/userapi/internal/device_list_update.go b/userapi/internal/device_list_update.go
index a4d28188..b4063516 100644
--- a/userapi/internal/device_list_update.go
+++ b/userapi/internal/device_list_update.go
@@ -25,6 +25,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	rsapi "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib/fclient"
 	"github.com/matrix-org/gomatrixserverlib/spec"
@@ -108,6 +109,8 @@ type DeviceListUpdater struct {
 	userIDToChan   map[string]chan bool
 	userIDToChanMu *sync.Mutex
 	rsAPI          rsapi.KeyserverRoomserverAPI
+
+	isBlacklistedOrBackingOffFn func(s spec.ServerName) (*statistics.ServerStatistics, error)
 }
 
 // DeviceListUpdaterDatabase is the subset of functionality from storage.Database required for the updater.
@@ -167,25 +170,28 @@ func NewDeviceListUpdater(
 	process *process.ProcessContext, db DeviceListUpdaterDatabase,
 	api DeviceListUpdaterAPI, producer KeyChangeProducer,
 	fedClient fedsenderapi.KeyserverFederationAPI, numWorkers int,
-	rsAPI rsapi.KeyserverRoomserverAPI, thisServer spec.ServerName,
+	rsAPI rsapi.KeyserverRoomserverAPI,
+	thisServer spec.ServerName,
 	enableMetrics bool,
+	isBlacklistedOrBackingOffFn func(s spec.ServerName) (*statistics.ServerStatistics, error),
 ) *DeviceListUpdater {
 	if enableMetrics {
 		prometheus.MustRegister(deviceListUpdaterBackpressure, deviceListUpdaterServersRetrying)
 	}
 	return &DeviceListUpdater{
-		process:        process,
-		userIDToMutex:  make(map[string]*sync.Mutex),
-		mu:             &sync.Mutex{},
-		db:             db,
-		api:            api,
-		producer:       producer,
-		fedClient:      fedClient,
-		thisServer:     thisServer,
-		workerChans:    make([]chan spec.ServerName, numWorkers),
-		userIDToChan:   make(map[string]chan bool),
-		userIDToChanMu: &sync.Mutex{},
-		rsAPI:          rsAPI,
+		process:                     process,
+		userIDToMutex:               make(map[string]*sync.Mutex),
+		mu:                          &sync.Mutex{},
+		db:                          db,
+		api:                         api,
+		producer:                    producer,
+		fedClient:                   fedClient,
+		thisServer:                  thisServer,
+		workerChans:                 make([]chan spec.ServerName, numWorkers),
+		userIDToChan:                make(map[string]chan bool),
+		userIDToChanMu:              &sync.Mutex{},
+		rsAPI:                       rsAPI,
+		isBlacklistedOrBackingOffFn: isBlacklistedOrBackingOffFn,
 	}
 }
 
@@ -362,13 +368,22 @@ func (u *DeviceListUpdater) notifyWorkers(userID string) {
 	if err != nil {
 		return
 	}
+	_, err = u.isBlacklistedOrBackingOffFn(remoteServer)
+	var federationClientError *fedsenderapi.FederationClientError
+	if errors.As(err, &federationClientError) {
+		if federationClientError.Blacklisted {
+			return
+		}
+	}
+
 	hash := fnv.New32a()
 	_, _ = hash.Write([]byte(remoteServer))
 	index := int(int64(hash.Sum32()) % int64(len(u.workerChans)))
 
 	ch := u.assignChannel(userID)
+	// Since workerChans are buffered, we only increment here and let the worker
+	// decrement it once it is done processing.
 	deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(index)}).Inc()
-	defer deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(index)}).Dec()
 	u.workerChans[index] <- remoteServer
 	select {
 	case <-ch:
@@ -405,24 +420,38 @@ func (u *DeviceListUpdater) worker(ch chan spec.ServerName, workerID int) {
 	go func() {
 		var serversToRetry []spec.ServerName
 		for {
-			serversToRetry = serversToRetry[:0] // reuse memory
-			time.Sleep(time.Second)
+			// nuke serversToRetry by re-slicing it to be "empty".
+			// The capacity of the slice is unchanged, which ensures we can reuse the memory.
+			serversToRetry = serversToRetry[:0]
+
+			deviceListUpdaterServersRetrying.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Set(float64(len(retries)))
+			time.Sleep(time.Second * 2)
+
+			// -2, so we have space for incoming device list updates over federation
+			maxServers := (cap(ch) - len(ch)) - 2
+			if maxServers <= 0 {
+				continue
+			}
+
 			retriesMu.Lock()
 			now := time.Now()
 			for srv, retryAt := range retries {
 				if now.After(retryAt) {
 					serversToRetry = append(serversToRetry, srv)
+					if maxServers == len(serversToRetry) {
+						break
+					}
 				}
 			}
+
 			for _, srv := range serversToRetry {
 				delete(retries, srv)
 			}
-			deviceListUpdaterServersRetrying.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Set(float64(len(retries)))
 			retriesMu.Unlock()
+
 			for _, srv := range serversToRetry {
 				deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Inc()
 				ch <- srv
-				deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Dec()
 			}
 		}
 	}()
@@ -430,8 +459,18 @@ func (u *DeviceListUpdater) worker(ch chan spec.ServerName, workerID int) {
 		retriesMu.Lock()
 		_, exists := retries[serverName]
 		retriesMu.Unlock()
-		if exists {
-			// Don't retry a server that we're already waiting for.
+
+		// If the serverName is coming from retries, maybe it was
+		// blacklisted in the meantime.
+		_, err := u.isBlacklistedOrBackingOffFn(serverName)
+		var federationClientError *fedsenderapi.FederationClientError
+		// unwrap errors and check for FederationClientError, if found, federationClientError will be not nil
+		errors.As(err, &federationClientError)
+		isBlacklisted := federationClientError != nil && federationClientError.Blacklisted
+
+		// Don't retry a server that we're already waiting for or is blacklisted by now.
+		if exists || isBlacklisted {
+			deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Dec()
 			continue
 		}
 		waitTime, shouldRetry := u.processServer(serverName)
@@ -442,6 +481,7 @@ func (u *DeviceListUpdater) worker(ch chan spec.ServerName, workerID int) {
 			}
 			retriesMu.Unlock()
 		}
+		deviceListUpdaterBackpressure.With(prometheus.Labels{"worker_id": strconv.Itoa(workerID)}).Dec()
 	}
 }
 
diff --git a/userapi/internal/device_list_update_test.go b/userapi/internal/device_list_update_test.go
index 14a49bc5..a2f1869d 100644
--- a/userapi/internal/device_list_update_test.go
+++ b/userapi/internal/device_list_update_test.go
@@ -27,6 +27,8 @@ import (
 	"testing"
 	"time"
 
+	api2 "github.com/matrix-org/dendrite/federationapi/api"
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -129,6 +131,10 @@ type mockDeviceListUpdaterAPI struct {
 func (d *mockDeviceListUpdaterAPI) PerformUploadDeviceKeys(ctx context.Context, req *api.PerformUploadDeviceKeysRequest, res *api.PerformUploadDeviceKeysResponse) {
 }
 
+var testIsBlacklistedOrBackingOff = func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+	return &statistics.ServerStatistics{}, nil
+}
+
 type roundTripper struct {
 	fn func(*http.Request) (*http.Response, error)
 }
@@ -162,7 +168,7 @@ func TestUpdateHavePrevID(t *testing.T) {
 	}
 	ap := &mockDeviceListUpdaterAPI{}
 	producer := &mockKeyChangeProducer{}
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, nil, 1, nil, "localhost", caching.DisableMetrics)
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, nil, 1, nil, "localhost", caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 	event := gomatrixserverlib.DeviceListUpdateEvent{
 		DeviceDisplayName: "Foo Bar",
 		Deleted:           false,
@@ -234,7 +240,7 @@ func TestUpdateNoPrevID(t *testing.T) {
 			`)),
 		}, nil
 	})
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 2, nil, "example.test", caching.DisableMetrics)
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 2, nil, "example.test", caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 	if err := updater.Start(); err != nil {
 		t.Fatalf("failed to start updater: %s", err)
 	}
@@ -304,7 +310,7 @@ func TestDebounce(t *testing.T) {
 		close(incomingFedReq)
 		return <-fedCh, nil
 	})
-	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 1, nil, "localhost", caching.DisableMetrics)
+	updater := NewDeviceListUpdater(process.NewProcessContext(), db, ap, producer, fedClient, 1, nil, "localhost", caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 	if err := updater.Start(); err != nil {
 		t.Fatalf("failed to start updater: %s", err)
 	}
@@ -407,7 +413,7 @@ func TestDeviceListUpdater_CleanUp(t *testing.T) {
 
 		updater := NewDeviceListUpdater(processCtx, db, nil,
 			nil, nil,
-			0, rsAPI, "test", caching.DisableMetrics)
+			0, rsAPI, "test", caching.DisableMetrics, testIsBlacklistedOrBackingOff)
 		if err := updater.CleanUp(); err != nil {
 			t.Error(err)
 		}
@@ -475,3 +481,68 @@ func Test_dedupeStateList(t *testing.T) {
 		})
 	}
 }
+
+func TestDeviceListUpdaterIgnoreBlacklisted(t *testing.T) {
+	unreachableServer := spec.ServerName("notlocalhost")
+
+	updater := DeviceListUpdater{
+		workerChans: make([]chan spec.ServerName, 1),
+		isBlacklistedOrBackingOffFn: func(s spec.ServerName) (*statistics.ServerStatistics, error) {
+			switch s {
+			case unreachableServer:
+				return nil, &api2.FederationClientError{Blacklisted: true}
+			}
+			return nil, nil
+		},
+		mu:             &sync.Mutex{},
+		userIDToChanMu: &sync.Mutex{},
+		userIDToChan:   make(map[string]chan bool),
+		userIDToMutex:  make(map[string]*sync.Mutex),
+	}
+	workerCh := make(chan spec.ServerName)
+	defer close(workerCh)
+	updater.workerChans[0] = workerCh
+
+	// happy case
+	alice := "@alice:localhost"
+	aliceCh := updater.assignChannel(alice)
+	defer updater.clearChannel(alice)
+
+	// failing case
+	bob := "@bob:" + unreachableServer
+	bobCh := updater.assignChannel(string(bob))
+	defer updater.clearChannel(string(bob))
+
+	expectedServers := map[spec.ServerName]struct{}{
+		"localhost": {},
+	}
+	unexpectedServers := make(map[spec.ServerName]struct{})
+
+	go func() {
+		for serverName := range workerCh {
+			switch serverName {
+			case "localhost":
+				delete(expectedServers, serverName)
+				aliceCh <- true // unblock notifyWorkers
+			case unreachableServer: // this should not happen as it is "filtered" away by the blacklist
+				unexpectedServers[serverName] = struct{}{}
+				bobCh <- true
+			default:
+				unexpectedServers[serverName] = struct{}{}
+			}
+		}
+	}()
+
+	// alice is not blacklisted
+	updater.notifyWorkers(alice)
+	// bob is blacklisted
+	updater.notifyWorkers(string(bob))
+
+	for server := range expectedServers {
+		t.Errorf("Server still in expectedServers map: %s", server)
+	}
+
+	for server := range unexpectedServers {
+		t.Errorf("unexpected server in result: %s", server)
+	}
+}
diff --git a/userapi/userapi.go b/userapi/userapi.go
index 34bf119a..a1c9b94a 100644
--- a/userapi/userapi.go
+++ b/userapi/userapi.go
@@ -18,10 +18,12 @@ import (
 	"time"
 
 	fedsenderapi "github.com/matrix-org/dendrite/federationapi/api"
+	"github.com/matrix-org/dendrite/federationapi/statistics"
 	"github.com/matrix-org/dendrite/internal/pushgateway"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/setup/process"
+	"github.com/matrix-org/gomatrixserverlib/spec"
 	"github.com/sirupsen/logrus"
 
 	rsapi "github.com/matrix-org/dendrite/roomserver/api"
@@ -47,6 +49,7 @@ func NewInternalAPI(
 	rsAPI rsapi.UserRoomserverAPI,
 	fedClient fedsenderapi.KeyserverFederationAPI,
 	enableMetrics bool,
+	blacklistedOrBackingOffFn func(s spec.ServerName) (*statistics.ServerStatistics, error),
 ) *internal.UserInternalAPI {
 	js, _ := natsInstance.Prepare(processContext, &dendriteCfg.Global.JetStream)
 	appServices := dendriteCfg.Derived.ApplicationServices
@@ -100,7 +103,7 @@ func NewInternalAPI(
 		FedClient:            fedClient,
 	}
 
-	updater := internal.NewDeviceListUpdater(processContext, keyDB, userAPI, keyChangeProducer, fedClient, dendriteCfg.UserAPI.WorkerCount, rsAPI, dendriteCfg.Global.ServerName, enableMetrics)
+	updater := internal.NewDeviceListUpdater(processContext, keyDB, userAPI, keyChangeProducer, fedClient, dendriteCfg.UserAPI.WorkerCount, rsAPI, dendriteCfg.Global.ServerName, enableMetrics, blacklistedOrBackingOffFn)
 	userAPI.Updater = updater
 	// Remove users which we don't share a room with anymore
 	if err := updater.CleanUp(); err != nil {