MM-60413: Fix issues due to incorrect cache provider (#28181)

We were using a mock cache provider which mixed up LRU caches
with each other. This led to incorrect unmarshalling method calls.

We fix this by using the real cache provider.

https://mattermost.atlassian.net/browse/MM-60413

```release-note
NONE
```

server/channels/store/localcachelayer/layer_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/mattermost/mattermost/server/v8/channels/store"
 	"github.com/mattermost/mattermost/server/v8/channels/store/sqlstore"
 	"github.com/mattermost/mattermost/server/v8/channels/store/storetest"
+	"github.com/mattermost/mattermost/server/v8/platform/services/cache"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -108,7 +109,7 @@ func initStores(logger mlog.LoggerIFace) {
 			if err != nil {
 				return err
 			}
-			st.Store, err = NewLocalCacheLayer(st.SqlStore, nil, nil, getMockCacheProvider(), logger)
+			st.Store, err = NewLocalCacheLayer(st.SqlStore, nil, nil, cache.NewProvider(), logger)
 			if err != nil {
 				return err
 			}

server/channels/store/localcachelayer/user_layer.go

@@ -84,8 +84,7 @@ func (s *LocalCacheUserStore) InvalidateProfilesInChannelCacheByUser(userId stri
 
 		toPass := make([]any, 0, len(keys))
 		for i := 0; i < len(keys); i++ {
-			// Note: keep https://github.com/mattermost/mattermost/pull/27830 in mind.
-			var userMap map[string]*model.User
+			var userMap model.UserMap
 			toPass = append(toPass, &userMap)
 		}
 		errs := s.rootStore.doMultiReadCache(s.rootStore.profilesInChannelCache, keys, toPass)
@@ -96,7 +95,7 @@ func (s *LocalCacheUserStore) InvalidateProfilesInChannelCacheByUser(userId stri
 				}
 				continue
 			}
-			gotMap := *(toPass[i].(*map[string]*model.User))
+			gotMap := *(toPass[i].(*model.UserMap))
 			if gotMap == nil {
 				s.rootStore.logger.Warn("Found nil userMap in InvalidateProfilesInChannelCacheByUser. This is not expected")
 				continue
@@ -147,7 +146,7 @@ func (s *LocalCacheUserStore) GetAllProfiles(options *model.UserGetOptions) ([]*
 
 func (s *LocalCacheUserStore) GetAllProfilesInChannel(ctx context.Context, channelId string, allowFromCache bool) (map[string]*model.User, error) {
 	if allowFromCache {
-		var cachedMap map[string]*model.User
+		var cachedMap model.UserMap
 		if err := s.rootStore.doStandardReadCache(s.rootStore.profilesInChannelCache, channelId, &cachedMap); err == nil {
 			return cachedMap, nil
 		}

server/platform/services/cache/lru.go

@@ -220,11 +220,6 @@ func (l *LRU) get(key string, value any) error {
 		_, err := u.UnmarshalMsg(val)
 		*v = &u
 		return err
-	case *map[string]*model.User:
-		var u model.UserMap
-		_, err := u.UnmarshalMsg(val)
-		*v = u
-		return err
 	}
 
 	// Slow path for other structs.

server/platform/services/cache/lru_test.go

@@ -294,12 +294,12 @@ func TestLRUMarshalUnMarshal(t *testing.T) {
 	u.Timezone = nil
 	require.Equal(t, user, u)
 
-	tt := make(map[string]*model.User)
+	tt := make(model.UserMap)
 	tt["1"] = u
-	err = l.SetWithDefaultExpiry("mm", model.UserMap(tt))
+	err = l.SetWithDefaultExpiry("mm", tt)
 	require.NoError(t, err)
 
-	var out map[string]*model.User
+	var out model.UserMap
 	err = l.Get("mm", &out)
 	require.NoError(t, err)
 	out["1"].Timezone = nil

server/platform/services/cache/redis.go

@@ -123,11 +123,6 @@ func (r *Redis) Get(key string, value any) error {
 		_, err := u.UnmarshalMsg(val)
 		*v = &u
 		return err
-	case *map[string]*model.User:
-		var u model.UserMap
-		_, err := u.UnmarshalMsg(val)
-		*v = u
-		return err
 	}
 
 	// Slow path for other structs.
@@ -193,12 +188,6 @@ func (r *Redis) GetMulti(keys []string, values []any) []error {
 			*v = &u
 			errs[i] = err
 			continue
-		case *map[string]*model.User:
-			var u model.UserMap
-			_, err := u.UnmarshalMsg(buf)
-			*v = u
-			errs[i] = err
-			continue
 		}
 
 		// Slow path for other structs.