Add FederationClient interface to federationsender (#1284)

* Add FederationClient interface to federationsender

- Use a shim struct in HTTP mode to keep the same API as `FederationClient`.
- Use `federationsender` instead of `FederationClient` in `keyserver`.

* Pointers not values

* Review comments

* Fix unit tests

* Rejig backoff

* Unbreak test

* Remove debug logs

* Review comments and linting

3 files changed, 9 insertions, 7 deletions

diff --git a/keyserver/internal/device_list_update.go b/keyserver/internal/device_list_update.go
index dd8fb700..36918256 100644
--- a/keyserver/internal/device_list_update.go
+++ b/keyserver/internal/device_list_update.go
@@ -22,6 +22,7 @@ import (
 	"sync"
 	"time"
 
+	fedsenderapi "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/keyserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
@@ -65,7 +66,7 @@ type DeviceListUpdater struct {
 
 	db          DeviceListUpdaterDatabase
 	producer    KeyChangeProducer
-	fedClient   *gomatrixserverlib.FederationClient
+	fedClient   fedsenderapi.FederationClient
 	workerChans []chan gomatrixserverlib.ServerName
 
 	// When device lists are stale for a user, they get inserted into this map with a channel which `Update` will
@@ -103,7 +104,7 @@ type KeyChangeProducer interface {
 
 // NewDeviceListUpdater creates a new updater which fetches fresh device lists when they go stale.
 func NewDeviceListUpdater(
-	db DeviceListUpdaterDatabase, producer KeyChangeProducer, fedClient *gomatrixserverlib.FederationClient,
+	db DeviceListUpdaterDatabase, producer KeyChangeProducer, fedClient fedsenderapi.FederationClient,
 	numWorkers int,
 ) *DeviceListUpdater {
 	return &DeviceListUpdater{
@@ -304,7 +305,7 @@ func (u *DeviceListUpdater) worker(ch chan gomatrixserverlib.ServerName) {
 				continue
 			} else {
 				scheduledRetries[serverName] = time.Now().Add(cooloffPeriod)
-				go inject(serverName, cooloffPeriod) // TODO: Backoff?
+				go inject(serverName, cooloffPeriod)
 				continue
 			}
 		}
@@ -312,7 +313,7 @@ func (u *DeviceListUpdater) worker(ch chan gomatrixserverlib.ServerName) {
 		shouldRetry := u.processServer(serverName)
 		if shouldRetry {
 			scheduledRetries[serverName] = time.Now().Add(cooloffPeriod)
-			go inject(serverName, cooloffPeriod) // TODO: Backoff?
+			go inject(serverName, cooloffPeriod)
 		}
 	}
 }
diff --git a/keyserver/internal/internal.go b/keyserver/internal/internal.go
index 31fb1236..53afe0a6 100644
--- a/keyserver/internal/internal.go
+++ b/keyserver/internal/internal.go
@@ -22,6 +22,7 @@ import (
 	"sync"
 	"time"
 
+	fedsenderapi "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/keyserver/api"
 	"github.com/matrix-org/dendrite/keyserver/producers"
 	"github.com/matrix-org/dendrite/keyserver/storage"
@@ -36,7 +37,7 @@ import (
 type KeyInternalAPI struct {
 	DB         storage.Database
 	ThisServer gomatrixserverlib.ServerName
-	FedClient  *gomatrixserverlib.FederationClient
+	FedClient  fedsenderapi.FederationClient
 	UserAPI    userapi.UserInternalAPI
 	Producer   *producers.KeyChange
 	Updater    *DeviceListUpdater
diff --git a/keyserver/keyserver.go b/keyserver/keyserver.go
index 04136938..2e561363 100644
--- a/keyserver/keyserver.go
+++ b/keyserver/keyserver.go
@@ -17,13 +17,13 @@ package keyserver
 import (
 	"github.com/Shopify/sarama"
 	"github.com/gorilla/mux"
+	fedsenderapi "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/config"
 	"github.com/matrix-org/dendrite/keyserver/api"
 	"github.com/matrix-org/dendrite/keyserver/internal"
 	"github.com/matrix-org/dendrite/keyserver/inthttp"
 	"github.com/matrix-org/dendrite/keyserver/producers"
 	"github.com/matrix-org/dendrite/keyserver/storage"
-	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/sirupsen/logrus"
 )
 
@@ -36,7 +36,7 @@ func AddInternalRoutes(router *mux.Router, intAPI api.KeyInternalAPI) {
 // NewInternalAPI returns a concerete implementation of the internal API. Callers
 // can call functions directly on the returned API or via an HTTP interface using AddInternalRoutes.
 func NewInternalAPI(
-	cfg *config.KeyServer, fedClient *gomatrixserverlib.FederationClient, producer sarama.SyncProducer,
+	cfg *config.KeyServer, fedClient fedsenderapi.FederationClient, producer sarama.SyncProducer,
 ) api.KeyInternalAPI {
 	db, err := storage.NewDatabase(&cfg.Database)
 	if err != nil {