From 9033efc9718d7cee43a6ea012d672c55889a2ee6 Mon Sep 17 00:00:00 2001
From: Deluan <deluan@navidrome.org>
Date: Sun, 17 Oct 2021 22:58:12 -0400
Subject: [PATCH] Cache smart playlist refreshes for 5 seconds

---
 persistence/playlist_repository.go    | 20 ++++++++++++++++----
 persistence/sql_smartplaylist.go      |  6 +++---
 persistence/sql_smartplaylist_test.go |  6 +++---
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/persistence/playlist_repository.go b/persistence/playlist_repository.go
index 37ff8a2df..cb1afd9a7 100644
--- a/persistence/playlist_repository.go
+++ b/persistence/playlist_repository.go
@@ -173,9 +173,11 @@ func (r *playlistRepository) GetAll(options ...model.QueryOptions) (model.Playli
 }
 
 func (r *playlistRepository) refreshSmartPlaylist(pls *model.Playlist) bool {
-	if !pls.IsSmartPlaylist() { //|| pls.EvaluatedAt.After(time.Now().Add(-5*time.Second)) {
+	// Only refresh if it is a smart playlist and was not refreshed in the last 5 seconds
+	if !pls.IsSmartPlaylist() || time.Since(pls.EvaluatedAt) < 5*time.Second {
 		return false
 	}
+
 	log.Debug(r.ctx, "Refreshing smart playlist", "playlist", pls.Name, "id", pls.ID)
 	start := time.Now()
 
@@ -186,7 +188,8 @@ func (r *playlistRepository) refreshSmartPlaylist(pls *model.Playlist) bool {
 		return false
 	}
 
-	sp := SmartPlaylist(*pls.Rules)
+	// Re-populate playlist based on Smart Playlist criteria
+	sp := smartPlaylist(*pls.Rules)
 	sql := Select("row_number() over (order by "+sp.OrderBy()+") as id", "'"+pls.ID+"' as playlist_id", "media_file.id as media_file_id").
 		From("media_file").LeftJoin("annotation on (" +
 		"annotation.item_id = media_file.id" +
@@ -200,14 +203,23 @@ func (r *playlistRepository) refreshSmartPlaylist(pls *model.Playlist) bool {
 		return false
 	}
 
+	// Update playlist stats
 	err = r.updateStats(pls.ID)
 	if err != nil {
 		log.Error(r.ctx, "Error updating smart playlist stats", "playlist", pls.Name, "id", pls.ID, err)
 		return false
 	}
 
+	// Update when the playlist was last refreshed (for cache purposes)
+	updSql := Update(r.tableName).Set("evaluated_at", time.Now()).Where(Eq{"id": pls.ID})
+	_, err = r.executeSQL(updSql)
+	if err != nil {
+		log.Error(r.ctx, "Error updating smart playlist", "playlist", pls.Name, "id", pls.ID, err)
+		return false
+	}
+
 	log.Debug(r.ctx, "Refreshed playlist", "playlist", pls.Name, "id", pls.ID, "numTracks", c, "elapsed", time.Since(start))
-	pls.EvaluatedAt = time.Now()
+
 	return true
 }
 
@@ -251,8 +263,8 @@ func (r *playlistRepository) updatePlaylist(playlistId string, mediaFileIds []st
 	return r.updateStats(playlistId)
 }
 
+// updateStats updates total playlist duration, size and count
 func (r *playlistRepository) updateStats(playlistId string) error {
-	// Get total playlist duration, size and count
 	statsSql := Select("sum(duration) as duration", "sum(size) as size", "count(*) as count").
 		From("media_file").
 		Join("playlist_tracks f on f.media_file_id = media_file.id").
diff --git a/persistence/sql_smartplaylist.go b/persistence/sql_smartplaylist.go
index 0c2bda8db..a5bb4dad4 100644
--- a/persistence/sql_smartplaylist.go
+++ b/persistence/sql_smartplaylist.go
@@ -20,9 +20,9 @@ import (
 //"order": "lastPlayed desc",
 //"limit": 10
 //}
-type SmartPlaylist model.SmartPlaylist
+type smartPlaylist model.SmartPlaylist
 
-func (sp SmartPlaylist) AddCriteria(sql SelectBuilder) SelectBuilder {
+func (sp smartPlaylist) AddCriteria(sql SelectBuilder) SelectBuilder {
 	sql = sql.Where(RuleGroup(sp.RuleGroup)).Limit(uint64(sp.Limit))
 	if order := sp.OrderBy(); order != "" {
 		sql = sql.OrderBy(order)
@@ -30,7 +30,7 @@ func (sp SmartPlaylist) AddCriteria(sql SelectBuilder) SelectBuilder {
 	return sql
 }
 
-func (sp SmartPlaylist) OrderBy() string {
+func (sp smartPlaylist) OrderBy() string {
 	order := strings.ToLower(sp.Order)
 	for f, fieldDef := range fieldMap {
 		if strings.HasPrefix(order, f) {
diff --git a/persistence/sql_smartplaylist_test.go b/persistence/sql_smartplaylist_test.go
index 11d982603..ca0dbc922 100644
--- a/persistence/sql_smartplaylist_test.go
+++ b/persistence/sql_smartplaylist_test.go
@@ -10,8 +10,8 @@ import (
 	. "github.com/onsi/gomega"
 )
 
-var _ = Describe("SmartPlaylist", func() {
-	var pls SmartPlaylist
+var _ = Describe("smartPlaylist", func() {
+	var pls smartPlaylist
 	Describe("AddCriteria", func() {
 		BeforeEach(func() {
 			sp := model.SmartPlaylist{
@@ -32,7 +32,7 @@ var _ = Describe("SmartPlaylist", func() {
 				Order: "artist asc",
 				Limit: 100,
 			}
-			pls = SmartPlaylist(sp)
+			pls = smartPlaylist(sp)
 		})
 
 		It("returns a proper SQL query", func() {