[GH-13106] Migrate channelMemberCountsCache cache from store/sqlstore/channel_store.go to the new store/localcachelayer (#13128)

* Migrate channelMemberCountsCache cache from store/sqlstore/channel_store.go to the new store/localcachelayer

* Move cache functions to layer functions over the caches

* Directly remove and purge caches in handleClusterInvalidate to avoid loops and prepare details for layer with multiple caches

store/sqlstore/channel_store.go

@@ -29,9 +29,6 @@ const (
 	ALL_CHANNEL_MEMBERS_NOTIFY_PROPS_FOR_CHANNEL_CACHE_SIZE = model.SESSION_CACHE_SIZE
 	ALL_CHANNEL_MEMBERS_NOTIFY_PROPS_FOR_CHANNEL_CACHE_SEC  = 1800 // 30 mins
 
-	CHANNEL_MEMBERS_COUNTS_CACHE_SIZE = model.CHANNEL_CACHE_SIZE
-	CHANNEL_MEMBERS_COUNTS_CACHE_SEC  = 1800 // 30 mins
-
 	CHANNEL_GUESTS_COUNTS_CACHE_SIZE = model.CHANNEL_CACHE_SIZE
 	CHANNEL_GUESTS_COUNTS_CACHE_SEC  = 1800 // 30 mins
 
@@ -283,7 +280,6 @@ type publicChannel struct {
 	Purpose     string `json:"purpose"`
 }
 
-var channelMemberCountsCache = utils.NewLru(CHANNEL_MEMBERS_COUNTS_CACHE_SIZE)
 var channelPinnedPostCountsCache = utils.NewLru(CHANNEL_PINNEDPOSTS_COUNTS_CACHE_SIZE)
 var channelGuestCountsCache = utils.NewLru(CHANNEL_GUESTS_COUNTS_CACHE_SIZE)
 var allChannelMembersForUserCache = utils.NewLru(ALL_CHANNEL_MEMBERS_FOR_USER_CACHE_SIZE)
@@ -292,7 +288,6 @@ var channelCache = utils.NewLru(model.CHANNEL_CACHE_SIZE)
 var channelByNameCache = utils.NewLru(model.CHANNEL_CACHE_SIZE)
 
 func (s SqlChannelStore) ClearCaches() {
-	channelMemberCountsCache.Purge()
 	channelPinnedPostCountsCache.Purge()
 	channelGuestCountsCache.Purge()
 	allChannelMembersForUserCache.Purge()
@@ -301,7 +296,6 @@ func (s SqlChannelStore) ClearCaches() {
 	channelByNameCache.Purge()
 
 	if s.metrics != nil {
-		s.metrics.IncrementMemCacheInvalidationCounter("Channel Member Counts - Purge")
 		s.metrics.IncrementMemCacheInvalidationCounter("Channel Pinned Post Counts - Purge")
 		s.metrics.IncrementMemCacheInvalidationCounter("All Channel Members for User - Purge")
 		s.metrics.IncrementMemCacheInvalidationCounter("All Channel Members Notify Props for Channel - Purge")
@@ -1585,46 +1579,14 @@ func (s SqlChannelStore) GetAllChannelMembersNotifyPropsForChannel(channelId str
 }
 
 func (s SqlChannelStore) InvalidateMemberCount(channelId string) {
-	channelMemberCountsCache.Remove(channelId)
-	if s.metrics != nil {
-		s.metrics.IncrementMemCacheInvalidationCounter("Channel Member Counts - Remove by ChannelId")
-	}
 }
 
 func (s SqlChannelStore) GetMemberCountFromCache(channelId string) int64 {
-	if cacheItem, ok := channelMemberCountsCache.Get(channelId); ok {
-		if s.metrics != nil {
-			s.metrics.IncrementMemCacheHitCounter("Channel Member Counts")
-		}
-		return cacheItem.(int64)
-	}
-
-	if s.metrics != nil {
-		s.metrics.IncrementMemCacheMissCounter("Channel Member Counts")
-	}
-
-	count, err := s.GetMemberCount(channelId, true)
-	if err != nil {
-		return 0
-	}
-
+	count, _ := s.GetMemberCount(channelId, true)
 	return count
 }
 
 func (s SqlChannelStore) GetMemberCount(channelId string, allowFromCache bool) (int64, *model.AppError) {
-	if allowFromCache {
-		if cacheItem, ok := channelMemberCountsCache.Get(channelId); ok {
-			if s.metrics != nil {
-				s.metrics.IncrementMemCacheHitCounter("Channel Member Counts")
-			}
-			return cacheItem.(int64), nil
-		}
-	}
-
-	if s.metrics != nil {
-		s.metrics.IncrementMemCacheMissCounter("Channel Member Counts")
-	}
-
 	count, err := s.GetReplica().SelectInt(`
 		SELECT
 			count(*)
@@ -1639,10 +1601,6 @@ func (s SqlChannelStore) GetMemberCount(channelId string, allowFromCache bool) (
 		return 0, model.NewAppError("SqlChannelStore.GetMemberCount", "store.sql_channel.get_member_count.app_error", nil, "channel_id="+channelId+", "+err.Error(), http.StatusInternalServerError)
 	}
 
-	if allowFromCache {
-		channelMemberCountsCache.AddWithExpiresInSecs(channelId, count, CHANNEL_MEMBERS_COUNTS_CACHE_SEC)
-	}
-
 	return count, nil
 }