Fixed litedb-org#2471, litedb-org#2435, litedb-org#2483 : Releasing r…

…ead lock when done reading
JKamsker · Jun 1, 2024 · ece59bb · ece59bb
1 parent 5a46966
commit ece59bb
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Showing 3 changed files with 87 additions and 17 deletions.
diff --git a/LiteDB.Tests/Issues/Issue2471_Test.cs b/LiteDB.Tests/Issues/Issue2471_Test.cs
@@ -0,0 +1,49 @@
+using FluentAssertions;
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Xunit;
+
+namespace LiteDB.Tests.Issues;
+
+public class Issue2471_Test
+{
+    [Fact]
+    public void TestFragmentDB_FindByIDException()
+    {
+        using var db = new LiteDatabase(":memory:");
+        var collection = db.GetCollection<object>("fragtest");
+
+        var fragment = new object { };
+        var id = collection.Insert(fragment);
+
+        id.Should().BeGreaterThan(0);
+
+        var frag2 = collection.FindById(id);
+        frag2.Should().NotBeNull();
+
+        Action act = () => db.Checkpoint();
+
+        act.Should().NotThrow();
+    }
+
+    [Fact]
+    public void MultipleReadCleansUpTransaction()
+    {
+        using var database = new LiteDatabase(":memory:");
+
+        var collection = database.GetCollection("test");
+        collection.Insert(new BsonDocument { ["_id"] = 1 });
+
+        for (int i = 0; i < 500; i++)
+        {
+            collection.FindById(1);
+        }
+    }
+}
diff --git a/LiteDB/Engine/Query/QueryExecutor.cs b/LiteDB/Engine/Query/QueryExecutor.cs
@@ -1,6 +1,9 @@
-using System;
+using LiteDB.Utils.Extensions;
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
+
 using static LiteDB.Constants;
 
 namespace LiteDB.Engine
@@ -71,8 +74,14 @@ internal BsonDataReader ExecuteQuery(bool executionPlan)
 
             transaction.OpenCursors.Add(_cursor);
 
+            var enumerable = RunQuery();
+            if (isNew)
+            {
+                enumerable = enumerable.OnDispose(() => _monitor.ReleaseTransaction(transaction));
+            }
+
             // return new BsonDataReader with IEnumerable source
-            return new BsonDataReader(RunQuery(), _collection, _state);
+            return new BsonDataReader(enumerable, _collection, _state);
 
             IEnumerable<BsonDocument> RunQuery()
             {
@@ -89,11 +98,6 @@ IEnumerable<BsonDocument> RunQuery()
 
                     transaction.OpenCursors.Remove(_cursor);
 
-                    if (isNew)
-                    {
-                        _monitor.ReleaseTransaction(transaction);
-                    }
-
                     yield break;
                 }
 
@@ -111,11 +115,6 @@ IEnumerable<BsonDocument> RunQuery()
 
                     transaction.OpenCursors.Remove(_cursor);
 
-                    if (isNew)
-                    {
-                        _monitor.ReleaseTransaction(transaction);
-                    }
-
                     yield break;
                 }
 
@@ -169,11 +168,6 @@ IEnumerable<BsonDocument> RunQuery()
                 _cursor.Elapsed.Stop();
 
                 transaction.OpenCursors.Remove(_cursor);
-
-                if (isNew)
-                {
-                    _monitor.ReleaseTransaction(transaction);
-                }
             };
         }
 

diff --git a/LiteDB/Utils/Extensions/EnumerableExtensions.cs b/LiteDB/Utils/Extensions/EnumerableExtensions.cs
@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace LiteDB.Utils.Extensions
+{
+    internal static class EnumerableExtensions
+    {
+        // calls method on dispose
+        public static IEnumerable<T> OnDispose<T>(this IEnumerable<T> source, Action onDispose)
+        {
+            try
+            {
+                foreach (var item in source)
+                {
+                    yield return item;
+                }
+            }
+            finally
+            {
+                onDispose();
+            }
+        }
+    }
+}