Revert prev workaround for LiteDB and make it flush instead

It turns out that LiteDB's data corruption
(mbdavid/LiteDB#1268) seems to happen
due to sudden termination of program.  So the workaround made in the
previous patch (planetarium#386)
was reverted for the most part, and a new option named `flush` was
added to `LiteDBStore()` constructor.

CHANGES.md

@@ -12,6 +12,8 @@ To be released.
  -  `StoreExtension.LookupStateReference<T>()` method became to return
     `Tuple<HashDigest<SHA256>, long>` which is a nullable tuple of `Block<T>.Hash`
     and `Block<T>.Index`.  [[#350]]
+ -  `LiteDBStore()` constructor became to have a new option named `flush` and turned on by default.
+    [[#387], [LiteDB #1268]]
 
 ### Added interfaces
 
@@ -45,7 +47,7 @@ To be released.
  -  Fixed a bug where the `LiteDBStore.IterateStagedTransactionIds()` returns
     duplicated transaction ids.  [[#366]]
  -  Fixed a `LiteDBStore` bug that blocks or transactions had got corrupted
-    sometimes.  [[#386], [LiteDB #1268]]
+    sometimes.  [[#386], [#387], [LiteDB #1268]]
 
 [#343]: https://github.com/planetarium/libplanet/pull/343
 [#350]: https://github.com/planetarium/libplanet/pull/350
@@ -54,7 +56,8 @@ To be released.
 [#366]: https://github.com/planetarium/libplanet/pull/366
 [#384]: https://github.com/planetarium/libplanet/issues/384
 [#385]: https://github.com/planetarium/libplanet/pull/385
-[#386]: https://github.com/planetarium/libplanet/pull/366
+[#386]: https://github.com/planetarium/libplanet/pull/386
+[#387]: https://github.com/planetarium/libplanet/pull/387
 [LiteDB #1268]: https://github.com/mbdavid/LiteDB/issues/1268
 
 

Libplanet/Store/LiteDBStore.cs

@@ -40,7 +40,14 @@ public class LiteDBStore : BaseStore, IDisposable
         /// Enables or disables double write check to ensure durability.
         /// </param>
         /// <param name="cacheSize">Max number of pages in the cache.</param>
-        public LiteDBStore(string path, bool journal = true, int cacheSize = 50000)
+        /// <param name="flush">Writes data direct to disk avoiding OS cache.  Turned on by default.
+        /// </param>
+        public LiteDBStore(
+            string path,
+            bool journal = true,
+            int cacheSize = 50000,
+            bool flush = true
+        )
         {
             if (path is null)
             {
@@ -52,6 +59,7 @@ public LiteDBStore(string path, bool journal = true, int cacheSize = 50000)
                 Filename = path,
                 Journal = journal,
                 CacheSize = cacheSize,
+                Flush = flush,
             };
 
             if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) &&
@@ -298,7 +306,8 @@ public override void SetBlockStates(
             {
                 var formatter = new BinaryFormatter();
                 formatter.Serialize(stream, states);
-                UploadFile(
+                stream.Seek(0, SeekOrigin.Begin);
+                _db.FileStorage.Upload(
                     BlockStateFileId(blockHash),
                     ByteUtil.Hex(blockHash.ToByteArray()),
                     stream
@@ -558,38 +567,12 @@ IEnumerable transactions
                 .Where(tx => tx != null);
         }
 
-        // As LiteDB's file storage seems unstable, we need to repeat trying to save a file
-        // until we ensure it's actually saved.
-        // https://github.com/mbdavid/LiteDB/issues/1268
-        private void UploadFile(string fileId, string filename, Stream stream)
-        {
-            bool IsFiledUploaded()
-            {
-                if (_db.FileStorage.FindById(fileId) is LiteFileInfo file && file.Length > 0)
-                {
-                    using (LiteFileStream f = file.OpenRead())
-                    {
-                        var buffer = new byte[1];
-                        return f.Read(buffer, 0, 1) > 0;
-                    }
-                }
-
-                return false;
-            }
-
-            do
-            {
-                stream.Seek(0, SeekOrigin.Begin);
-                _db.FileStorage.Upload(fileId, filename, stream);
-            }
-            while (!IsFiledUploaded());
-        }
-
         private void UploadFile(string fileId, string filename, byte[] bytes)
         {
             using (var stream = new MemoryStream(bytes))
             {
-                UploadFile(fileId, filename, stream);
+                stream.Seek(0, SeekOrigin.Begin);
+                _db.FileStorage.Upload(fileId, filename, stream);
             }
         }