More flexible caching (#1101)

internal/caching/cache_roomversions.go

@@ -0,0 +1,30 @@
+package caching
+
+import "github.com/matrix-org/gomatrixserverlib"
+
+const (
+	RoomVersionCacheName       = "room_versions"
+	RoomVersionCacheMaxEntries = 1024
+	RoomVersionCacheMutable    = false
+)
+
+// RoomVersionsCache contains the subset of functions needed for
+// a room version cache.
+type RoomVersionCache interface {
+	GetRoomVersion(roomID string) (roomVersion gomatrixserverlib.RoomVersion, ok bool)
+	StoreRoomVersion(roomID string, roomVersion gomatrixserverlib.RoomVersion)
+}
+
+func (c Caches) GetRoomVersion(roomID string) (gomatrixserverlib.RoomVersion, bool) {
+	val, found := c.RoomVersions.Get(roomID)
+	if found && val != nil {
+		if roomVersion, ok := val.(gomatrixserverlib.RoomVersion); ok {
+			return roomVersion, true
+		}
+	}
+	return "", false
+}
+
+func (c Caches) StoreRoomVersion(roomID string, roomVersion gomatrixserverlib.RoomVersion) {
+	c.RoomVersions.Set(roomID, roomVersion)
+}