PLT-5308 Caching layer part 2 (#6973)

* Adding Reaction store cache layer example

* Implementing reaction store in new caching system.

* Redis for reaction store

* Adding redis library

* Adding invalidation for DeleteAllWithEmojiName and other minor enhancements

store/local_cache_supplier.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package store
+
+import (
+	"context"
+
+	"github.com/mattermost/platform/einterfaces"
+	"github.com/mattermost/platform/model"
+	"github.com/mattermost/platform/utils"
+)
+
+const (
+	REACTION_CACHE_SIZE = 20000
+	REACTION_CACHE_SEC  = 1800 // 30 minutes
+
+	CLEAR_CACHE_MESSAGE_DATA = ""
+)
+
+type LocalCacheSupplier struct {
+	next          LayeredStoreSupplier
+	reactionCache *utils.Cache
+}
+
+func NewLocalCacheSupplier() *LocalCacheSupplier {
+	supplier := &LocalCacheSupplier{
+		reactionCache: utils.NewLruWithParams(REACTION_CACHE_SIZE, "Reaction", REACTION_CACHE_SEC, model.CLUSTER_EVENT_INVALIDATE_CACHE_FOR_REACTIONS),
+	}
+
+	registerClusterHandlers(supplier)
+
+	return supplier
+}
+
+func registerClusterHandlers(supplier *LocalCacheSupplier) {
+	if cluster := einterfaces.GetClusterInterface(); cluster != nil {
+		cluster.RegisterClusterMessageHandler(model.CLUSTER_EVENT_INVALIDATE_CACHE_FOR_REACTIONS, supplier.handleClusterInvalidateReaction)
+	}
+}
+
+func (s *LocalCacheSupplier) SetChainNext(next LayeredStoreSupplier) {
+	s.next = next
+}
+
+func (s *LocalCacheSupplier) Next() LayeredStoreSupplier {
+	return s.next
+}
+
+func doStandardReadCache(ctx context.Context, cache utils.ObjectCache, key string, hints ...LayeredStoreHint) *LayeredStoreSupplierResult {
+	metrics := einterfaces.GetMetricsInterface()
+
+	if hintsContains(hints, LSH_NO_CACHE) {
+		if metrics != nil {
+			metrics.IncrementMemCacheMissCounter(cache.Name())
+		}
+		return nil
+	}
+
+	if cacheItem, ok := cache.Get(key); ok {
+		if metrics != nil {
+			metrics.IncrementMemCacheHitCounter(cache.Name())
+		}
+		result := NewSupplierResult()
+		result.Data = cacheItem
+		return result
+	}
+
+	if metrics != nil {
+		metrics.IncrementMemCacheMissCounter(cache.Name())
+	}
+
+	return nil
+}
+
+func doStandardAddToCache(ctx context.Context, cache utils.ObjectCache, key string, result *LayeredStoreSupplierResult, hints ...LayeredStoreHint) {
+	if result.Err == nil && result.Data != nil {
+		cache.AddWithDefaultExpires(key, result.Data)
+	}
+}
+
+func doInvalidateCacheCluster(cache utils.ObjectCache, key string) {
+	cache.Remove(key)
+	if einterfaces.GetClusterInterface() != nil {
+		msg := &model.ClusterMessage{
+			Event:    cache.GetInvalidateClusterEvent(),
+			SendType: model.CLUSTER_SEND_BEST_EFFORT,
+			Data:     key,
+		}
+		einterfaces.GetClusterInterface().SendClusterMessage(msg)
+	}
+}
+
+func doClearCacheCluster(cache utils.ObjectCache) {
+	cache.Purge()
+	if einterfaces.GetClusterInterface() != nil {
+		msg := &model.ClusterMessage{
+			Event:    cache.GetInvalidateClusterEvent(),
+			SendType: model.CLUSTER_SEND_BEST_EFFORT,
+			Data:     CLEAR_CACHE_MESSAGE_DATA,
+		}
+		einterfaces.GetClusterInterface().SendClusterMessage(msg)
+	}
+}