Adding caching layer to some posts calls (#4779)

3 files changed, 68 insertions, 6 deletions

diff --git a/store/sql_post_store.go b/store/sql_post_store.go
index 900aeeeb6..44ae58b32 100644
--- a/store/sql_post_store.go
+++ b/store/sql_post_store.go
@@ -17,6 +17,17 @@ type SqlPostStore struct {
 	*SqlStore
 }
 
+const (
+	POSTS_ETAG_CACHE_SIZE = 25000
+	POSTS_ETAG_CACHE_SEC  = 900 // 15 minutes
+)
+
+var postEtagCache = utils.NewLru(CHANNEL_MEMBERS_COUNTS_CACHE_SIZE)
+
+func ClearPostCaches() {
+	postEtagCache.Purge()
+}
+
 func NewSqlPostStore(sqlStore *SqlStore) PostStore {
 	s := &SqlPostStore{sqlStore}
 
@@ -210,12 +221,25 @@ type etagPosts struct {
 	UpdateAt int64
 }
 
-func (s SqlPostStore) GetEtag(channelId string) StoreChannel {
+func (s SqlPostStore) InvalidatePostEtagCache(channelId string) {
+	postEtagCache.Remove(channelId)
+}
+
+func (s SqlPostStore) GetEtag(channelId string, allowFromCache bool) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 
 	go func() {
 		result := StoreResult{}
 
+		if allowFromCache {
+			if cacheItem, ok := postEtagCache.Get(channelId); ok {
+				result.Data = cacheItem.(string)
+				storeChannel <- result
+				close(storeChannel)
+				return
+			}
+		}
+
 		var et etagPosts
 		err := s.GetReplica().SelectOne(&et, "SELECT Id, UpdateAt FROM Posts WHERE ChannelId = :ChannelId ORDER BY UpdateAt DESC LIMIT 1", map[string]interface{}{"ChannelId": channelId})
 		if err != nil {
@@ -224,6 +248,8 @@ func (s SqlPostStore) GetEtag(channelId string) StoreChannel {
 			result.Data = fmt.Sprintf("%v.%v.%v", model.CurrentVersion, et.Id, et.UpdateAt)
 		}
 
+		postEtagCache.AddWithExpiresInSecs(channelId, result.Data.(string), POSTS_ETAG_CACHE_SEC)
+
 		storeChannel <- result
 		close(storeChannel)
 	}()
diff --git a/store/sql_post_store_test.go b/store/sql_post_store_test.go
index d685ea41e..30376fae5 100644
--- a/store/sql_post_store_test.go
+++ b/store/sql_post_store_test.go
@@ -37,14 +37,14 @@ func TestPostStoreGet(t *testing.T) {
 	o1.UserId = model.NewId()
 	o1.Message = "a" + model.NewId() + "b"
 
-	etag1 := (<-store.Post().GetEtag(o1.ChannelId)).Data.(string)
+	etag1 := (<-store.Post().GetEtag(o1.ChannelId, false)).Data.(string)
 	if strings.Index(etag1, model.CurrentVersion+".0.") != 0 {
 		t.Fatal("Invalid Etag")
 	}
 
 	o1 = (<-store.Post().Save(o1)).Data.(*model.Post)
 
-	etag2 := (<-store.Post().GetEtag(o1.ChannelId)).Data.(string)
+	etag2 := (<-store.Post().GetEtag(o1.ChannelId, false)).Data.(string)
 	if strings.Index(etag2, model.CurrentVersion+"."+o1.Id) != 0 {
 		t.Fatal("Invalid Etag")
 	}
@@ -62,6 +62,41 @@ func TestPostStoreGet(t *testing.T) {
 	}
 }
 
+func TestGetEtagCache(t *testing.T) {
+	Setup()
+	o1 := &model.Post{}
+	o1.ChannelId = model.NewId()
+	o1.UserId = model.NewId()
+	o1.Message = "a" + model.NewId() + "b"
+
+	etag1 := (<-store.Post().GetEtag(o1.ChannelId, true)).Data.(string)
+	if strings.Index(etag1, model.CurrentVersion+".0.") != 0 {
+		t.Fatal("Invalid Etag")
+	}
+
+	// This one should come from the cache
+	etag2 := (<-store.Post().GetEtag(o1.ChannelId, true)).Data.(string)
+	if strings.Index(etag2, model.CurrentVersion+".0.") != 0 {
+		t.Fatal("Invalid Etag")
+	}
+
+	o1 = (<-store.Post().Save(o1)).Data.(*model.Post)
+
+	// We have not invalidated the cache so this should be the same as above
+	etag3 := (<-store.Post().GetEtag(o1.ChannelId, true)).Data.(string)
+	if strings.Index(etag3, model.CurrentVersion+".0.") != 0 {
+		t.Fatal("Invalid Etag")
+	}
+
+	store.Post().InvalidatePostEtagCache(o1.ChannelId)
+
+	// Invalidated cache so we should get a good result
+	etag4 := (<-store.Post().GetEtag(o1.ChannelId, true)).Data.(string)
+	if strings.Index(etag4, model.CurrentVersion+"."+o1.Id) != 0 {
+		t.Fatal("Invalid Etag")
+	}
+}
+
 func TestPostStoreUpdate(t *testing.T) {
 	Setup()
 
@@ -164,7 +199,7 @@ func TestPostStoreDelete(t *testing.T) {
 	o1.UserId = model.NewId()
 	o1.Message = "a" + model.NewId() + "b"
 
-	etag1 := (<-store.Post().GetEtag(o1.ChannelId)).Data.(string)
+	etag1 := (<-store.Post().GetEtag(o1.ChannelId, false)).Data.(string)
 	if strings.Index(etag1, model.CurrentVersion+".0.") != 0 {
 		t.Fatal("Invalid Etag")
 	}
@@ -188,7 +223,7 @@ func TestPostStoreDelete(t *testing.T) {
 		t.Fatal("Missing id should have failed")
 	}
 
-	etag2 := (<-store.Post().GetEtag(o1.ChannelId)).Data.(string)
+	etag2 := (<-store.Post().GetEtag(o1.ChannelId, false)).Data.(string)
 	if strings.Index(etag2, model.CurrentVersion+"."+o1.Id) != 0 {
 		t.Fatal("Invalid Etag")
 	}
diff --git a/store/store.go b/store/store.go
index 236fbbc13..b0cc09983 100644
--- a/store/store.go
+++ b/store/store.go
@@ -130,11 +130,12 @@ type PostStore interface {
 	GetPostsBefore(channelId string, postId string, numPosts int, offset int) StoreChannel
 	GetPostsAfter(channelId string, postId string, numPosts int, offset int) StoreChannel
 	GetPostsSince(channelId string, time int64) StoreChannel
-	GetEtag(channelId string) StoreChannel
+	GetEtag(channelId string, allowFromCache bool) StoreChannel
 	Search(teamId string, userId string, params *model.SearchParams) StoreChannel
 	AnalyticsUserCountsWithPostsByDay(teamId string) StoreChannel
 	AnalyticsPostCountsByDay(teamId string) StoreChannel
 	AnalyticsPostCount(teamId string, mustHaveFile bool, mustHaveHashtag bool) StoreChannel
+	InvalidatePostEtagCache(channelId string)
 }
 
 type UserStore interface {