[MM 19840] Create a Cache Interface abstraction to support multiple cache backends (#13384)

* Refactor to use structured logging

* Properly formatted with gofmt

* created interface Cache, but construction of cache is still coupled.

* Implementing cache factories to build caches

* Simple redis implementation without error handling. Keys and values by default are string

* refactor NewLocalCacheLayer to inject cache factory

* Removed redis impl to focus on cache abstraction

* CacheFactory injected on sqlsupplier and saved in Store struct

* remove useless private method

* replace concrete declaration of lru cache to cache abstraction

* discard spaces

* Renamed factory to provider because concrete implementations of factories may hold an state (such as a redis client for example)

* refactor to include all caches in the same package cache and subpackages

* method close cache. This method will be used for concrete implementations that need to release resources (close a connection, etc)

* closing cacheprovider and releasing resources while closing sql store

* fixed merge conflict fail

* gofmt files

* remove unused property from post_store

* naming refactor to avoid stutter. Added godocs on interface

* Store doesnt know anything about the cache and provider. Cache provider will be built after loading config and injected in localCacheLayer

* fixed broken test

* cache provider initialized before RunOldAppInitialization which initializes the localcachelayer

* move statusCache to server to initialize it with the new cache provider

* update terms_service and channel_layer to have new cacheProvider

* gofmt

* Add Connect method to the cache provider

* mock cacheprovider in user_layer_test

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/status.go

@@ -6,17 +6,10 @@ package app
 import (
 	"github.com/mattermost/mattermost-server/v5/mlog"
 	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/utils"
 )
 
-var statusCache *utils.Cache = utils.NewLru(model.STATUS_CACHE_SIZE)
-
-func ClearStatusCache() {
-	statusCache.Purge()
-}
-
 func (a *App) AddStatusCacheSkipClusterSend(status *model.Status) {
-	statusCache.Add(status.UserId, status)
+	a.Srv.statusCache.Add(status.UserId, status)
 }
 
 func (a *App) AddStatusCache(status *model.Status) {
@@ -37,12 +30,12 @@ func (a *App) GetAllStatuses() map[string]*model.Status {
 		return map[string]*model.Status{}
 	}
 
-	userIds := statusCache.Keys()
+	userIds := a.Srv.statusCache.Keys()
 	statusMap := map[string]*model.Status{}
 
 	for _, userId := range userIds {
 		if id, ok := userId.(string); ok {
-			status := GetStatusFromCache(id)
+			status := a.GetStatusFromCache(id)
 			if status != nil {
 				statusMap[id] = status
 			}
@@ -62,7 +55,7 @@ func (a *App) GetStatusesByIds(userIds []string) (map[string]interface{}, *model
 
 	missingUserIds := []string{}
 	for _, userId := range userIds {
-		if result, ok := statusCache.Get(userId); ok {
+		if result, ok := a.Srv.statusCache.Get(userId); ok {
 			statusMap[userId] = result.(*model.Status).Status
 			if metrics != nil {
 				metrics.IncrementMemCacheHitCounter("Status")
@@ -109,7 +102,7 @@ func (a *App) GetUserStatusesByIds(userIds []string) ([]*model.Status, *model.Ap
 
 	missingUserIds := []string{}
 	for _, userId := range userIds {
-		if result, ok := statusCache.Get(userId); ok {
+		if result, ok := a.Srv.statusCache.Get(userId); ok {
 			statusMap = append(statusMap, result.(*model.Status))
 			if metrics != nil {
 				metrics.IncrementMemCacheHitCounter("Status")
@@ -329,8 +322,8 @@ func (a *App) SetStatusOutOfOffice(userId string) {
 	a.SaveAndBroadcastStatus(status)
 }
 
-func GetStatusFromCache(userId string) *model.Status {
-	if result, ok := statusCache.Get(userId); ok {
+func (a *App) GetStatusFromCache(userId string) *model.Status {
+	if result, ok := a.Srv.statusCache.Get(userId); ok {
 		status := result.(*model.Status)
 		statusCopy := &model.Status{}
 		*statusCopy = *status
@@ -345,7 +338,7 @@ func (a *App) GetStatus(userId string) (*model.Status, *model.AppError) {
 		return &model.Status{}, nil
 	}
 
-	status := GetStatusFromCache(userId)
+	status := a.GetStatusFromCache(userId)
 	if status != nil {
 		return status, nil
 	}