Hook up device list updates to the sync notifier (#1231)

* WIP hooking up key changes

* Fix import cycle, get tests passing and binary compiling

* Linting and update whitelist

keyserver/api/api.go

@@ -143,6 +143,8 @@ type QueryKeyChangesRequest struct {
 type QueryKeyChangesResponse struct {
 	// The set of users who have had their keys change.
 	UserIDs []string
+	// The partition being served - useful if the partition is unknown at request time
+	Partition int32
 	// The latest offset represented in this response.
 	Offset int64
 	// Set if there was a problem handling the request.

keyserver/internal/internal.go

@@ -41,6 +41,9 @@ type KeyInternalAPI struct {
 }
 
 func (a *KeyInternalAPI) QueryKeyChanges(ctx context.Context, req *api.QueryKeyChangesRequest, res *api.QueryKeyChangesResponse) {
+	if req.Partition < 0 {
+		req.Partition = a.Producer.DefaultPartition()
+	}
 	userIDs, latest, err := a.DB.KeyChanges(ctx, req.Partition, req.Offset)
 	if err != nil {
 		res.Error = &api.KeyError{
@@ -48,6 +51,7 @@ func (a *KeyInternalAPI) QueryKeyChanges(ctx context.Context, req *api.QueryKeyC
 		}
 	}
 	res.Offset = latest
+	res.Partition = req.Partition
 	res.UserIDs = userIDs
 }
 

keyserver/producers/keychange.go

@@ -31,6 +31,15 @@ type KeyChange struct {
 	DB       storage.Database
 }
 
+// DefaultPartition returns the default partition this process is sending key changes to.
+// NB: A keyserver MUST send key changes to only 1 partition or else query operations will
+// become inconsistent. Partitions can be sharded (e.g by hash of user ID of key change) but
+// then all keyservers must be queried to calculate the entire set of key changes between
+// two sync tokens.
+func (p *KeyChange) DefaultPartition() int32 {
+	return 0
+}
+
 // ProduceKeyChanges creates new change events for each key
 func (p *KeyChange) ProduceKeyChanges(keys []api.DeviceKeys) error {
 	for _, key := range keys {