Transactional synchronize message

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -1153,15 +1153,20 @@ public class ServiceSynchronize extends LifecycleService {
             boolean seen = helper.getSeen();
 
             DB db = DB.getInstance(this);
+            try {
+                db.beginTransaction();
+
+                // Find message by uid (fast, no headers required)
                 EntityMessage message = db.message().getMessageByUid(folder.id, uid);
 
-            // Find by Message-ID
+                // Find message by Message-ID (slow, headers required)
                 // - messages in inbox have same id as message sent to self
                 // - messages in archive have same id as original
                 if (message == null &&
                         !EntityFolder.SENT.equals(folder.type) &&
                         !EntityFolder.ARCHIVE.equals(folder.type)) {
-                String msgid = imessage.getMessageID(); // Will fetch headers
+                    // Will fetch headers within database transaction
+                    String msgid = imessage.getMessageID();
                     message = db.message().getMessageByMsgId(msgid);
                     if (message != null) {
                         Log.i(Helper.TAG, folder.name + " found as id=" + message.id + " uid=" + message.uid + " msgid=" + msgid);
@@ -1171,7 +1176,25 @@ public class ServiceSynchronize extends LifecycleService {
                     }
                 }
 
-            if (message == null) {
+                if (message != null) {
+                    if (message.seen != seen) {
+                        message.seen = seen;
+                        message.ui_seen = seen;
+                        db.message().updateMessage(message);
+                        Log.v(Helper.TAG, folder.name + " updated id=" + message.id + " uid=" + message.uid);
+                        return -1;
+                    } else {
+                        Log.v(Helper.TAG, folder.name + " unchanged id=" + message.id + " uid=" + message.uid);
+                        return 0;
+                    }
+                }
+
+                db.setTransactionSuccessful();
+
+            } finally {
+                db.endTransaction();
+            }
+
             FetchProfile fp1 = new FetchProfile();
             fp1.add(FetchProfile.Item.ENVELOPE);
             fp1.add(FetchProfile.Item.CONTENT_INFO);
@@ -1179,7 +1202,7 @@ public class ServiceSynchronize extends LifecycleService {
             fp1.add(IMAPFolder.FetchProfileItem.MESSAGE);
             ifolder.fetch(new Message[]{imessage}, fp1);
 
-                message = new EntityMessage();
+            EntityMessage message = new EntityMessage();
             message.account = folder.account;
             message.folder = folder.id;
             message.uid = uid;
@@ -1221,16 +1244,6 @@ public class ServiceSynchronize extends LifecycleService {
             }
 
             return 1;
-            } else if (message.seen != seen) {
-                message.seen = seen;
-                message.ui_seen = seen;
-                db.message().updateMessage(message);
-                Log.v(Helper.TAG, folder.name + " updated id=" + message.id + " uid=" + message.uid);
-                return -1;
-            } else {
-                Log.v(Helper.TAG, folder.name + " unchanged id=" + message.id + " uid=" + message.uid);
-                return 0;
-            }
 
         } finally {
             Log.v(Helper.TAG, folder.name + " end sync uid=" + uid);