Adding caching of last 60 posts. (#4880)

api/post.go

@@ -1295,7 +1295,7 @@ func getPosts(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	pchan := Srv.Store.Post().GetPosts(id, offset, limit)
+	pchan := Srv.Store.Post().GetPosts(id, offset, limit, true)
 
 	if result := <-pchan; result.Err != nil {
 		c.Err = result.Err

store/sql_post_store.go

@@ -21,12 +21,17 @@ type SqlPostStore struct {
 const (
 	LAST_POST_TIME_CACHE_SIZE = 25000
 	LAST_POST_TIME_CACHE_SEC  = 900 // 15 minutes
+
+	LAST_POSTS_CACHE_SIZE = 1000
+	LAST_POSTS_CACHE_SEC  = 900 // 15 minutes
 )
 
 var lastPostTimeCache = utils.NewLru(LAST_POST_TIME_CACHE_SIZE)
+var lastPostsCache = utils.NewLru(LAST_POSTS_CACHE_SIZE)
 
 func ClearPostCaches() {
 	lastPostTimeCache.Purge()
+	lastPostsCache.Purge()
 }
 
 func NewSqlPostStore(sqlStore *SqlStore) PostStore {
@@ -224,6 +229,7 @@ type etagPosts struct {
 
 func (s SqlPostStore) InvalidateLastPostTimeCache(channelId string) {
 	lastPostTimeCache.Remove(channelId)
+	lastPostsCache.Remove(channelId)
 }
 
 func (s SqlPostStore) GetEtag(channelId string, allowFromCache bool) StoreChannel {
@@ -381,11 +387,12 @@ func (s SqlPostStore) PermanentDeleteByUser(userId string) StoreChannel {
 	return storeChannel
 }
 
-func (s SqlPostStore) GetPosts(channelId string, offset int, limit int) StoreChannel {
+func (s SqlPostStore) GetPosts(channelId string, offset int, limit int, allowFromCache bool) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 
 	go func() {
 		result := StoreResult{}
+		metrics := einterfaces.GetMetricsInterface()
 
 		if limit > 1000 {
 			result.Err = model.NewLocAppError("SqlPostStore.GetLinearPosts", "store.sql_post.get_posts.app_error", nil, "channelId="+channelId)
@@ -394,6 +401,27 @@ func (s SqlPostStore) GetPosts(channelId string, offset int, limit int) StoreCha
 			return
 		}
 
+		if allowFromCache && offset == 0 && limit == 60 {
+			if cacheItem, ok := lastPostsCache.Get(channelId); ok {
+				if metrics != nil {
+					metrics.IncrementMemCacheHitCounter("Last Posts Cache")
+				}
+
+				result.Data = cacheItem.(*model.PostList)
+				storeChannel <- result
+				close(storeChannel)
+				return
+			} else {
+				if metrics != nil {
+					metrics.IncrementMemCacheMissCounter("Last Posts Cache")
+				}
+			}
+		} else {
+			if metrics != nil {
+				metrics.IncrementMemCacheMissCounter("Last Posts Cache")
+			}
+		}
+
 		rpc := s.getRootPosts(channelId, offset, limit)
 		cpc := s.getParentsPosts(channelId, offset, limit)
 
@@ -418,6 +446,10 @@ func (s SqlPostStore) GetPosts(channelId string, offset int, limit int) StoreCha
 
 			list.MakeNonNil()
 
+			if offset == 0 && limit == 60 {
+				lastPostsCache.AddWithExpiresInSecs(channelId, list, LAST_POSTS_CACHE_SEC)
+			}
+
 			result.Data = list
 		}
 

store/sql_post_store_test.go

@@ -491,7 +491,7 @@ func TestPostStoreGetPostsWtihDetails(t *testing.T) {
 	o5.RootId = o4.Id
 	o5 = (<-store.Post().Save(o5)).Data.(*model.Post)
 
-	r1 := (<-store.Post().GetPosts(o1.ChannelId, 0, 4)).Data.(*model.PostList)
+	r1 := (<-store.Post().GetPosts(o1.ChannelId, 0, 4, false)).Data.(*model.PostList)
 
 	if r1.Order[0] != o5.Id {
 		t.Fatal("invalid order")
@@ -516,6 +516,32 @@ func TestPostStoreGetPostsWtihDetails(t *testing.T) {
 	if r1.Posts[o1.Id].Message != o1.Message {
 		t.Fatal("Missing parent")
 	}
+
+	r2 := (<-store.Post().GetPosts(o1.ChannelId, 0, 4, true)).Data.(*model.PostList)
+
+	if r2.Order[0] != o5.Id {
+		t.Fatal("invalid order")
+	}
+
+	if r2.Order[1] != o4.Id {
+		t.Fatal("invalid order")
+	}
+
+	if r2.Order[2] != o3.Id {
+		t.Fatal("invalid order")
+	}
+
+	if r2.Order[3] != o2a.Id {
+		t.Fatal("invalid order")
+	}
+
+	if len(r2.Posts) != 6 { //the last 4, + o1 (o2a and o3's parent) + o2 (in same thread as o2a and o3)
+		t.Fatal("wrong size")
+	}
+
+	if r2.Posts[o1.Id].Message != o1.Message {
+		t.Fatal("Missing parent")
+	}
 }
 
 func TestPostStoreGetPostsBeforeAfter(t *testing.T) {

store/store.go

@@ -127,7 +127,7 @@ type PostStore interface {
 	Get(id string) StoreChannel
 	Delete(postId string, time int64) StoreChannel
 	PermanentDeleteByUser(userId string) StoreChannel
-	GetPosts(channelId string, offset int, limit int) StoreChannel
+	GetPosts(channelId string, offset int, limit int, allowFromCache bool) StoreChannel
 	GetFlaggedPosts(userId string, offset int, limit int) StoreChannel
 	GetPostsBefore(channelId string, postId string, numPosts int, offset int) StoreChannel
 	GetPostsAfter(channelId string, postId string, numPosts int, offset int) StoreChannel