From 17b9a974dee1e9c190e7863ad3661bed19ba6b59 Mon Sep 17 00:00:00 2001
From: Kavin <20838718+FireMasterK@users.noreply.github.com>
Date: Mon, 4 Jul 2022 06:42:01 +0100
Subject: [PATCH] Attempt to use stateless sessions in read-only operations.
 (#301)

---
 src/main/java/me/kavin/piped/Main.java        |  3 +-
 .../me/kavin/piped/utils/DatabaseHelper.java  | 35 ++++++------
 .../piped/utils/DatabaseSessionFactory.java   | 12 ++---
 .../me/kavin/piped/utils/ResponseHelper.java  | 54 ++++++++++---------
 4 files changed, 51 insertions(+), 53 deletions(-)

diff --git a/src/main/java/me/kavin/piped/Main.java b/src/main/java/me/kavin/piped/Main.java
index ea6cb02..28894b1 100644
--- a/src/main/java/me/kavin/piped/Main.java
+++ b/src/main/java/me/kavin/piped/Main.java
@@ -8,6 +8,7 @@ import me.kavin.piped.utils.*;
 import me.kavin.piped.utils.obj.db.PubSub;
 import me.kavin.piped.utils.obj.db.User;
 import org.hibernate.Session;
+import org.hibernate.StatelessSession;
 import org.hibernate.Transaction;
 import org.hibernate.query.Query;
 import org.schabi.newpipe.extractor.NewPipe;
@@ -54,7 +55,7 @@ public class Main {
         new Timer().scheduleAtFixedRate(new TimerTask() {
             @Override
             public void run() {
-                try (Session s = DatabaseSessionFactory.createSession()) {
+                try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
 
                     CriteriaBuilder cb = s.getCriteriaBuilder();
                     CriteriaQuery<PubSub> criteria = cb.createQuery(PubSub.class);
diff --git a/src/main/java/me/kavin/piped/utils/DatabaseHelper.java b/src/main/java/me/kavin/piped/utils/DatabaseHelper.java
index 097d8db..0f5ea30 100644
--- a/src/main/java/me/kavin/piped/utils/DatabaseHelper.java
+++ b/src/main/java/me/kavin/piped/utils/DatabaseHelper.java
@@ -5,8 +5,8 @@ import jakarta.persistence.criteria.CriteriaQuery;
 import jakarta.persistence.criteria.JoinType;
 import jakarta.persistence.criteria.Root;
 import me.kavin.piped.utils.obj.db.*;
-import org.hibernate.FlushMode;
-import org.hibernate.Session;
+import org.hibernate.SharedSessionContract;
+import org.hibernate.StatelessSession;
 
 import java.util.List;
 import java.util.UUID;
@@ -14,13 +14,12 @@ import java.util.UUID;
 public class DatabaseHelper {
 
     public static User getUserFromSession(String session) {
-        try (Session s = DatabaseSessionFactory.createSession()) {
-            s.setHibernateFlushMode(FlushMode.MANUAL);
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             return getUserFromSession(session, s);
         }
     }
 
-    public static User getUserFromSession(String session, Session s) {
+    public static User getUserFromSession(String session, SharedSessionContract s) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<User> cr = cb.createQuery(User.class);
         Root<User> root = cr.from(User.class);
@@ -30,8 +29,7 @@ public class DatabaseHelper {
     }
 
     public static User getUserFromSessionWithSubscribed(String session) {
-        try (Session s = DatabaseSessionFactory.createSession()) {
-            s.setHibernateFlushMode(FlushMode.MANUAL);
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             CriteriaBuilder cb = s.getCriteriaBuilder();
             CriteriaQuery<User> cr = cb.createQuery(User.class);
             Root<User> root = cr.from(User.class);
@@ -42,7 +40,7 @@ public class DatabaseHelper {
         }
     }
 
-    public static Channel getChannelFromId(Session s, String id) {
+    public static Channel getChannelFromId(SharedSessionContract s, String id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<Channel> cr = cb.createQuery(Channel.class);
         Root<Channel> root = cr.from(Channel.class);
@@ -52,13 +50,12 @@ public class DatabaseHelper {
     }
 
     public static Channel getChannelFromId(String id) {
-        try (Session s = DatabaseSessionFactory.createSession()) {
-            s.setHibernateFlushMode(FlushMode.MANUAL);
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             return getChannelFromId(s, id);
         }
     }
 
-    public static List<Channel> getChannelsFromIds(Session s, List<String> id) {
+    public static List<Channel> getChannelsFromIds(SharedSessionContract s, List<String> id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<Channel> cr = cb.createQuery(Channel.class);
         Root<Channel> root = cr.from(Channel.class);
@@ -67,7 +64,7 @@ public class DatabaseHelper {
         return s.createQuery(cr).list();
     }
 
-    public static Video getVideoFromId(Session s, String id) {
+    public static Video getVideoFromId(SharedSessionContract s, String id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<Video> cr = cb.createQuery(Video.class);
         Root<Video> root = cr.from(Video.class);
@@ -77,13 +74,12 @@ public class DatabaseHelper {
     }
 
     public static Video getVideoFromId(String id) {
-        try (Session s = DatabaseSessionFactory.createSession()) {
-            s.setHibernateFlushMode(FlushMode.MANUAL);
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             return getVideoFromId(s, id);
         }
     }
 
-    public static PlaylistVideo getPlaylistVideoFromId(Session s, String id) {
+    public static PlaylistVideo getPlaylistVideoFromId(SharedSessionContract s, String id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<PlaylistVideo> cr = cb.createQuery(PlaylistVideo.class);
         Root<PlaylistVideo> root = cr.from(PlaylistVideo.class);
@@ -92,7 +88,7 @@ public class DatabaseHelper {
         return s.createQuery(cr).uniqueResult();
     }
 
-    public static Playlist getPlaylistFromId(Session s, String id) {
+    public static Playlist getPlaylistFromId(SharedSessionContract s, String id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<Playlist> cr = cb.createQuery(Playlist.class);
         Root<Playlist> root = cr.from(Playlist.class);
@@ -101,7 +97,7 @@ public class DatabaseHelper {
         return s.createQuery(cr).uniqueResult();
     }
 
-    public static List<PlaylistVideo> getPlaylistVideosFromIds(Session s, List<String> id) {
+    public static List<PlaylistVideo> getPlaylistVideosFromIds(SharedSessionContract s, List<String> id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<PlaylistVideo> cr = cb.createQuery(PlaylistVideo.class);
         Root<PlaylistVideo> root = cr.from(PlaylistVideo.class);
@@ -110,7 +106,7 @@ public class DatabaseHelper {
         return s.createQuery(cr).list();
     }
 
-    public static PubSub getPubSubFromId(Session s, String id) {
+    public static PubSub getPubSubFromId(SharedSessionContract s, String id) {
         CriteriaBuilder cb = s.getCriteriaBuilder();
         CriteriaQuery<PubSub> cr = cb.createQuery(PubSub.class);
         Root<PubSub> root = cr.from(PubSub.class);
@@ -120,8 +116,7 @@ public class DatabaseHelper {
     }
 
     public static PubSub getPubSubFromId(String id) {
-        try (Session s = DatabaseSessionFactory.createSession()) {
-            s.setHibernateFlushMode(FlushMode.MANUAL);
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             return getPubSubFromId(s, id);
         }
     }
diff --git a/src/main/java/me/kavin/piped/utils/DatabaseSessionFactory.java b/src/main/java/me/kavin/piped/utils/DatabaseSessionFactory.java
index 63fefd4..a9ab7f0 100644
--- a/src/main/java/me/kavin/piped/utils/DatabaseSessionFactory.java
+++ b/src/main/java/me/kavin/piped/utils/DatabaseSessionFactory.java
@@ -1,14 +1,10 @@
 package me.kavin.piped.utils;
 
 import me.kavin.piped.consts.Constants;
-import me.kavin.piped.utils.obj.db.Channel;
-import me.kavin.piped.utils.obj.db.Playlist;
-import me.kavin.piped.utils.obj.db.PlaylistVideo;
-import me.kavin.piped.utils.obj.db.PubSub;
-import me.kavin.piped.utils.obj.db.User;
-import me.kavin.piped.utils.obj.db.Video;
+import me.kavin.piped.utils.obj.db.*;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
+import org.hibernate.StatelessSession;
 import org.hibernate.cfg.Configuration;
 
 public class DatabaseSessionFactory {
@@ -31,4 +27,8 @@ public class DatabaseSessionFactory {
     public static final Session createSession() {
         return sessionFactory.openSession();
     }
+
+    public static StatelessSession createStatelessSession() {
+        return sessionFactory.openStatelessSession();
+    }
 }
diff --git a/src/main/java/me/kavin/piped/utils/ResponseHelper.java b/src/main/java/me/kavin/piped/utils/ResponseHelper.java
index 1ebfb86..5dcc562 100644
--- a/src/main/java/me/kavin/piped/utils/ResponseHelper.java
+++ b/src/main/java/me/kavin/piped/utils/ResponseHelper.java
@@ -29,6 +29,7 @@ import org.apache.commons.codec.digest.DigestUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.exception.ExceptionUtils;
 import org.hibernate.Session;
+import org.hibernate.StatelessSession;
 import org.schabi.newpipe.extractor.InfoItem;
 import org.schabi.newpipe.extractor.ListExtractor.InfoItemsPage;
 import org.schabi.newpipe.extractor.Page;
@@ -224,9 +225,10 @@ public class ResponseHelper {
         info.getRelatedItems().forEach(o -> relatedStreams.add(collectRelatedStream(o)));
 
         Multithreading.runAsync(() -> {
-            try (Session s = DatabaseSessionFactory.createSession()) {
 
-                me.kavin.piped.utils.obj.db.Channel channel = DatabaseHelper.getChannelFromId(s, info.getId());
+            me.kavin.piped.utils.obj.db.Channel channel = DatabaseHelper.getChannelFromId(info.getId());
+
+            try (Session s = DatabaseSessionFactory.createSession()) {
 
                 if (channel != null) {
                     if (channel.isVerified() != info.isVerified()
@@ -324,7 +326,7 @@ public class ResponseHelper {
     }
 
     private static byte[] playlistPipedResponse(String playlistId) throws IOException {
-        try (Session s = DatabaseSessionFactory.createSession()) {
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             var cb = s.getCriteriaBuilder();
             var cq = cb.createQuery(me.kavin.piped.utils.obj.db.Playlist.class);
             var root = cq.from(me.kavin.piped.utils.obj.db.Playlist.class);
@@ -421,7 +423,7 @@ public class ResponseHelper {
     private static byte[] playlistPipedRSSResponse(String playlistId)
             throws FeedException {
 
-        try (Session s = DatabaseSessionFactory.createSession()) {
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             var cb = s.getCriteriaBuilder();
             var cq = cb.createQuery(me.kavin.piped.utils.obj.db.Playlist.class);
             var root = cq.from(me.kavin.piped.utils.obj.db.Playlist.class);
@@ -720,7 +722,7 @@ public class ResponseHelper {
 
         user = user.toLowerCase();
 
-        try (Session s = DatabaseSessionFactory.createSession()) {
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             CriteriaBuilder cb = s.getCriteriaBuilder();
             CriteriaQuery<User> cr = cb.createQuery(User.class);
             Root<User> root = cr.from(User.class);
@@ -786,11 +788,9 @@ public class ResponseHelper {
                     tr.commit();
 
                     Multithreading.runAsync(() -> {
-                        try (Session s2 = DatabaseSessionFactory.createSession()) {
-                            var channel = DatabaseHelper.getChannelFromId(s2, channelId);
-                            if (channel == null) {
-                                Multithreading.runAsync(() -> saveChannel(channelId));
-                            }
+                        var channel = DatabaseHelper.getChannelFromId(channelId);
+                        if (channel == null) {
+                            Multithreading.runAsync(() -> saveChannel(channelId));
                         }
                     });
                 }
@@ -825,7 +825,7 @@ public class ResponseHelper {
     }
 
     public static byte[] isSubscribedResponse(String session, String channelId) throws IOException {
-        try (Session s = DatabaseSessionFactory.createSession()) {
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             var cb = s.getCriteriaBuilder();
             var query = cb.createQuery(Long.class);
             var root = query.from(User.class);
@@ -848,7 +848,7 @@ public class ResponseHelper {
         User user = DatabaseHelper.getUserFromSession(session);
 
         if (user != null) {
-            try (Session s = DatabaseSessionFactory.createSession()) {
+            try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
 
                 CriteriaBuilder cb = s.getCriteriaBuilder();
 
@@ -892,7 +892,7 @@ public class ResponseHelper {
 
         if (user != null) {
 
-            try (Session s = DatabaseSessionFactory.createSession()) {
+            try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
 
                 SyndFeed feed = new SyndFeedImpl();
                 feed.setFeedType("atom_1.0");
@@ -954,7 +954,7 @@ public class ResponseHelper {
         if (user != null) {
 
             Multithreading.runAsync(() -> {
-                try (Session sess = DatabaseSessionFactory.createSession()) {
+                try (Session s = DatabaseSessionFactory.createSession()) {
                     if (override) {
                         user.setSubscribed(Set.of(channelIds));
                     } else {
@@ -963,15 +963,15 @@ public class ResponseHelper {
                     }
 
                     if (channelIds.length > 0) {
-                        var tr = sess.beginTransaction();
-                        sess.merge(user);
+                        var tr = s.beginTransaction();
+                        s.merge(user);
                         tr.commit();
                     }
                 }
             });
 
             Multithreading.runAsync(() -> {
-                try (Session s = DatabaseSessionFactory.createSession()) {
+                try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
                     var channels = DatabaseHelper.getChannelsFromIds(s, Arrays.asList(channelIds));
 
                     Arrays.stream(channelIds).parallel()
@@ -996,7 +996,7 @@ public class ResponseHelper {
         User user = DatabaseHelper.getUserFromSession(session);
 
         if (user != null) {
-            try (Session s = DatabaseSessionFactory.createSession()) {
+            try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
 
                 CriteriaBuilder cb = s.getCriteriaBuilder();
                 var query = cb.createQuery(me.kavin.piped.utils.obj.db.Channel.class);
@@ -1275,14 +1275,14 @@ public class ResponseHelper {
             s.merge(playlist);
             tr.commit();
 
-            Multithreading.runAsync(() -> pruneUnusedPlaylistVideos());
+            Multithreading.runAsync(ResponseHelper::pruneUnusedPlaylistVideos);
 
             return mapper.writeValueAsBytes(new AcceptedResponse());
         }
     }
 
     public static String registeredBadgeRedirect() {
-        try (Session s = DatabaseSessionFactory.createSession()) {
+        try (StatelessSession s = DatabaseSessionFactory.createStatelessSession()) {
             long registered = (Long) s.createQuery("select count(*) from User").uniqueResult();
 
             return String.format("https://img.shields.io/badge/Registered%%20Users-%s-blue", registered);
@@ -1349,11 +1349,12 @@ public class ResponseHelper {
     private static void updateVideo(String id, StreamInfoItem item, long time, boolean addIfNotExistent) {
         Multithreading.runAsync(() -> {
             try {
-                Session s = DatabaseSessionFactory.createSession();
-                Video video = DatabaseHelper.getVideoFromId(s, id);
+                Video video = DatabaseHelper.getVideoFromId(id);
 
                 if (video != null) {
-                    updateVideo(s, video, item.getViewCount(), item.getDuration(), item.getName());
+                    try (Session s = DatabaseSessionFactory.createSession()) {
+                        updateVideo(s, video, item.getViewCount(), item.getDuration(), item.getName());
+                    }
                 } else if (addIfNotExistent) {
                     handleNewVideo("https://www.youtube.com/watch?v=" + id, time, null);
                 }
@@ -1367,11 +1368,12 @@ public class ResponseHelper {
     private static void updateVideo(String id, StreamInfo info, long time) {
         Multithreading.runAsync(() -> {
             try {
-                Session s = DatabaseSessionFactory.createSession();
-                Video video = DatabaseHelper.getVideoFromId(s, id);
+                Video video = DatabaseHelper.getVideoFromId(id);
 
                 if (video != null) {
-                    updateVideo(s, video, info.getViewCount(), info.getDuration(), info.getName());
+                    try (Session s = DatabaseSessionFactory.createSession()) {
+                        updateVideo(s, video, info.getViewCount(), info.getDuration(), info.getName());
+                    }
                 } else {
                     handleNewVideo(info, time, null);
                 }