Refactor `StoreEvent` and create a new `RoomDatabase` interface (#2985)

This PR changes a few things:
- It pulls out the creation of several NIDs from the `StoreEvent`
function to make the functions more reusable
- Uses more caching when using those NIDs to avoid DB round trips

4 files changed, 60 insertions, 10 deletions

diff --git a/internal/caching/cache_eventstatekeys.go b/internal/caching/cache_eventstatekeys.go
index 05580ab0..51e2499d 100644
--- a/internal/caching/cache_eventstatekeys.go
+++ b/internal/caching/cache_eventstatekeys.go
@@ -7,6 +7,7 @@ import "github.com/matrix-org/dendrite/roomserver/types"
 type EventStateKeyCache interface {
 	GetEventStateKey(eventStateKeyNID types.EventStateKeyNID) (string, bool)
 	StoreEventStateKey(eventStateKeyNID types.EventStateKeyNID, eventStateKey string)
+	GetEventStateKeyNID(eventStateKey string) (types.EventStateKeyNID, bool)
 }
 
 func (c Caches) GetEventStateKey(eventStateKeyNID types.EventStateKeyNID) (string, bool) {
@@ -15,4 +16,23 @@ func (c Caches) GetEventStateKey(eventStateKeyNID types.EventStateKeyNID) (strin
 
 func (c Caches) StoreEventStateKey(eventStateKeyNID types.EventStateKeyNID, eventStateKey string) {
 	c.RoomServerStateKeys.Set(eventStateKeyNID, eventStateKey)
+	c.RoomServerStateKeyNIDs.Set(eventStateKey, eventStateKeyNID)
+}
+
+func (c Caches) GetEventStateKeyNID(eventStateKey string) (types.EventStateKeyNID, bool) {
+	return c.RoomServerStateKeyNIDs.Get(eventStateKey)
+}
+
+type EventTypeCache interface {
+	GetEventTypeKey(eventType string) (types.EventTypeNID, bool)
+	StoreEventTypeKey(eventTypeNID types.EventTypeNID, eventType string)
+}
+
+func (c Caches) StoreEventTypeKey(eventTypeNID types.EventTypeNID, eventType string) {
+	c.RoomServerEventTypeNIDs.Set(eventType, eventTypeNID)
+	c.RoomServerEventTypes.Set(eventTypeNID, eventType)
+}
+
+func (c Caches) GetEventTypeKey(eventType string) (types.EventTypeNID, bool) {
+	return c.RoomServerEventTypeNIDs.Get(eventType)
 }
diff --git a/internal/caching/cache_roomservernids.go b/internal/caching/cache_roomservernids.go
index 88a5b28b..734a3a04 100644
--- a/internal/caching/cache_roomservernids.go
+++ b/internal/caching/cache_roomservernids.go
@@ -9,19 +9,28 @@ type RoomServerCaches interface {
 	RoomVersionCache
 	RoomServerEventsCache
 	EventStateKeyCache
+	EventTypeCache
 }
 
 // RoomServerNIDsCache contains the subset of functions needed for
 // a roomserver NID cache.
 type RoomServerNIDsCache interface {
 	GetRoomServerRoomID(roomNID types.RoomNID) (string, bool)
+	// StoreRoomServerRoomID stores roomNID -> roomID and roomID -> roomNID
 	StoreRoomServerRoomID(roomNID types.RoomNID, roomID string)
+	GetRoomServerRoomNID(roomID string) (types.RoomNID, bool)
 }
 
 func (c Caches) GetRoomServerRoomID(roomNID types.RoomNID) (string, bool) {
 	return c.RoomServerRoomIDs.Get(roomNID)
 }
 
+// StoreRoomServerRoomID stores roomNID -> roomID and roomID -> roomNID
 func (c Caches) StoreRoomServerRoomID(roomNID types.RoomNID, roomID string) {
+	c.RoomServerRoomNIDs.Set(roomID, roomNID)
 	c.RoomServerRoomIDs.Set(roomNID, roomID)
 }
+
+func (c Caches) GetRoomServerRoomNID(roomID string) (types.RoomNID, bool) {
+	return c.RoomServerRoomNIDs.Get(roomID)
+}
diff --git a/internal/caching/caches.go b/internal/caching/caches.go
index 78c9ab7e..47992046 100644
--- a/internal/caching/caches.go
+++ b/internal/caching/caches.go
@@ -23,16 +23,19 @@ import (
 // different implementations as long as they satisfy the Cache
 // interface.
 type Caches struct {
-	RoomVersions        Cache[string, gomatrixserverlib.RoomVersion]           // room ID -> room version
-	ServerKeys          Cache[string, gomatrixserverlib.PublicKeyLookupResult] // server name -> server keys
-	RoomServerRoomNIDs  Cache[string, types.RoomNID]                           // room ID -> room NID
-	RoomServerRoomIDs   Cache[types.RoomNID, string]                           // room NID -> room ID
-	RoomServerEvents    Cache[int64, *gomatrixserverlib.Event]                 // event NID -> event
-	RoomServerStateKeys Cache[types.EventStateKeyNID, string]                  // event NID -> event state key
-	FederationPDUs      Cache[int64, *gomatrixserverlib.HeaderedEvent]         // queue NID -> PDU
-	FederationEDUs      Cache[int64, *gomatrixserverlib.EDU]                   // queue NID -> EDU
-	SpaceSummaryRooms   Cache[string, gomatrixserverlib.MSC2946SpacesResponse] // room ID -> space response
-	LazyLoading         Cache[lazyLoadingCacheKey, string]                     // composite key -> event ID
+	RoomVersions            Cache[string, gomatrixserverlib.RoomVersion]           // room ID -> room version
+	ServerKeys              Cache[string, gomatrixserverlib.PublicKeyLookupResult] // server name -> server keys
+	RoomServerRoomNIDs      Cache[string, types.RoomNID]                           // room ID -> room NID
+	RoomServerRoomIDs       Cache[types.RoomNID, string]                           // room NID -> room ID
+	RoomServerEvents        Cache[int64, *gomatrixserverlib.Event]                 // event NID -> event
+	RoomServerStateKeys     Cache[types.EventStateKeyNID, string]                  // eventStateKey NID -> event state key
+	RoomServerStateKeyNIDs  Cache[string, types.EventStateKeyNID]                  // event state key -> eventStateKey NID
+	RoomServerEventTypeNIDs Cache[string, types.EventTypeNID]                      // eventType -> eventType NID
+	RoomServerEventTypes    Cache[types.EventTypeNID, string]                      // eventType NID -> eventType
+	FederationPDUs          Cache[int64, *gomatrixserverlib.HeaderedEvent]         // queue NID -> PDU
+	FederationEDUs          Cache[int64, *gomatrixserverlib.EDU]                   // queue NID -> EDU
+	SpaceSummaryRooms       Cache[string, gomatrixserverlib.MSC2946SpacesResponse] // room ID -> space response
+	LazyLoading             Cache[lazyLoadingCacheKey, string]                     // composite key -> event ID
 }
 
 // Cache is the interface that an implementation must satisfy.
diff --git a/internal/caching/impl_ristretto.go b/internal/caching/impl_ristretto.go
index 49292d0d..fca93afd 100644
--- a/internal/caching/impl_ristretto.go
+++ b/internal/caching/impl_ristretto.go
@@ -40,6 +40,9 @@ const (
 	spaceSummaryRoomsCache
 	lazyLoadingCache
 	eventStateKeyCache
+	eventTypeCache
+	eventTypeNIDCache
+	eventStateKeyNIDCache
 )
 
 func NewRistrettoCache(maxCost config.DataUnit, maxAge time.Duration, enablePrometheus bool) *Caches {
@@ -105,6 +108,21 @@ func NewRistrettoCache(maxCost config.DataUnit, maxAge time.Duration, enableProm
 			Prefix: eventStateKeyCache,
 			MaxAge: maxAge,
 		},
+		RoomServerStateKeyNIDs: &RistrettoCachePartition[string, types.EventStateKeyNID]{ // eventStateKey -> eventStateKey NID
+			cache:  cache,
+			Prefix: eventStateKeyNIDCache,
+			MaxAge: maxAge,
+		},
+		RoomServerEventTypeNIDs: &RistrettoCachePartition[string, types.EventTypeNID]{ // eventType -> eventType NID
+			cache:  cache,
+			Prefix: eventTypeCache,
+			MaxAge: maxAge,
+		},
+		RoomServerEventTypes: &RistrettoCachePartition[types.EventTypeNID, string]{ // eventType NID -> eventType
+			cache:  cache,
+			Prefix: eventTypeNIDCache,
+			MaxAge: maxAge,
+		},
 		FederationPDUs: &RistrettoCostedCachePartition[int64, *gomatrixserverlib.HeaderedEvent]{ // queue NID -> PDU
 			&RistrettoCachePartition[int64, *gomatrixserverlib.HeaderedEvent]{
 				cache:   cache,