Federation sender event cache (#1614)

* Cache federation sender events

* Store in the correct cache

* Update federation event cache

* Fix Unset

* Give EDUs same caching treatment as PDUs

* Make federationsender_cache_size configurable

* Default caches configuration

* Fix unit tests

* Revert "Fix unit tests"

This reverts commit 24eb5d22524f20e1024b1475debe61ae20538a5a.

* Revert "Default caches configuration"

This reverts commit 464ecd1e64b9d2983f6fd5430e9607519d543cb3.

* Revert "Make federationsender_cache_size configurable"

This reverts commit 4631f5324151e006a15d6f19008f06361b994607.

internal/caching/cache_federationevents.go

@@ -0,0 +1,67 @@
+package caching
+
+import (
+	"fmt"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const (
+	FederationEventCacheName       = "federation_event"
+	FederationEventCacheMaxEntries = 256
+	FederationEventCacheMutable    = true // to allow use of Unset only
+)
+
+// FederationSenderCache contains the subset of functions needed for
+// a federation event cache.
+type FederationSenderCache interface {
+	GetFederationSenderQueuedPDU(eventNID int64) (event *gomatrixserverlib.HeaderedEvent, ok bool)
+	StoreFederationSenderQueuedPDU(eventNID int64, event *gomatrixserverlib.HeaderedEvent)
+	EvictFederationSenderQueuedPDU(eventNID int64)
+
+	GetFederationSenderQueuedEDU(eventNID int64) (event *gomatrixserverlib.EDU, ok bool)
+	StoreFederationSenderQueuedEDU(eventNID int64, event *gomatrixserverlib.EDU)
+	EvictFederationSenderQueuedEDU(eventNID int64)
+}
+
+func (c Caches) GetFederationSenderQueuedPDU(eventNID int64) (*gomatrixserverlib.HeaderedEvent, bool) {
+	key := fmt.Sprintf("%d", eventNID)
+	val, found := c.FederationEvents.Get(key)
+	if found && val != nil {
+		if event, ok := val.(*gomatrixserverlib.HeaderedEvent); ok {
+			return event, true
+		}
+	}
+	return nil, false
+}
+
+func (c Caches) StoreFederationSenderQueuedPDU(eventNID int64, event *gomatrixserverlib.HeaderedEvent) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Set(key, event)
+}
+
+func (c Caches) EvictFederationSenderQueuedPDU(eventNID int64) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Unset(key)
+}
+
+func (c Caches) GetFederationSenderQueuedEDU(eventNID int64) (*gomatrixserverlib.EDU, bool) {
+	key := fmt.Sprintf("%d", eventNID)
+	val, found := c.FederationEvents.Get(key)
+	if found && val != nil {
+		if event, ok := val.(*gomatrixserverlib.EDU); ok {
+			return event, true
+		}
+	}
+	return nil, false
+}
+
+func (c Caches) StoreFederationSenderQueuedEDU(eventNID int64, event *gomatrixserverlib.EDU) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Set(key, event)
+}
+
+func (c Caches) EvictFederationSenderQueuedEDU(eventNID int64) {
+	key := fmt.Sprintf("%d", eventNID)
+	c.FederationEvents.Unset(key)
+}

internal/caching/caches.go

@@ -10,6 +10,7 @@ type Caches struct {
 	RoomServerEventTypeNIDs Cache // RoomServerNIDsCache
 	RoomServerRoomNIDs      Cache // RoomServerNIDsCache
 	RoomServerRoomIDs       Cache // RoomServerNIDsCache
+	FederationEvents        Cache // FederationEventsCache
 }
 
 // Cache is the interface that an implementation must satisfy.

internal/caching/impl_inmemorylru.go

@@ -63,6 +63,15 @@ func NewInMemoryLRUCache(enablePrometheus bool) (*Caches, error) {
 	if err != nil {
 		return nil, err
 	}
+	federationEvents, err := NewInMemoryLRUCachePartition(
+		FederationEventCacheName,
+		FederationEventCacheMutable,
+		FederationEventCacheMaxEntries,
+		enablePrometheus,
+	)
+	if err != nil {
+		return nil, err
+	}
 	return &Caches{
 		RoomVersions:            roomVersions,
 		ServerKeys:              serverKeys,
@@ -70,6 +79,7 @@ func NewInMemoryLRUCache(enablePrometheus bool) (*Caches, error) {
 		RoomServerEventTypeNIDs: roomServerEventTypeNIDs,
 		RoomServerRoomNIDs:      roomServerRoomNIDs,
 		RoomServerRoomIDs:       roomServerRoomIDs,
+		FederationEvents:        federationEvents,
 	}, nil
 }