From 48d89fd515f3ee348b13c5248d636bedd3a71611 Mon Sep 17 00:00:00 2001
From: neumannf <frank.neumann@htw-berlin.de>
Date: Sat, 26 Dec 2020 10:55:27 +0100
Subject: [PATCH] Fixed issue #1772: Unfortunately, the TransactionService for
 a closed thread was not be removed from the _transactions dictionary within
 the TransactionMonitor. Therefore a finalizer for the TransactionService was
 added, which takes care of removing the transaction from the _transactions
 dictionary.

---
 LiteDB/Engine/Services/TransactionService.cs | 28 +++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/LiteDB/Engine/Services/TransactionService.cs b/LiteDB/Engine/Services/TransactionService.cs
index 5f03d71df..0a03e5837 100644
--- a/LiteDB/Engine/Services/TransactionService.cs
+++ b/LiteDB/Engine/Services/TransactionService.cs
@@ -74,6 +74,14 @@ public TransactionService(HeaderPage header, LockService locker, DiskService dis
             _reader = _disk.GetReader();
         }
 
+        /// <summary>
+        /// Finalizer: Will be called once a thread is closed. The TransactionMonitor._slot releases the used TransactionService.
+        /// </summary>
+        ~TransactionService()
+        {
+            Dispose(false);
+        }
+
         /// <summary>
         /// Create (or get from transaction-cache) snapshot and return
         /// </summary>
@@ -375,10 +383,22 @@ IEnumerable<PageBuffer> source()
         }
 
         /// <summary>
-        /// Dispose
+        /// Public implementation of Dispose pattern.
         /// </summary>
         public void Dispose()
         {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        // Protected implementation of Dispose pattern.
+        protected virtual void Dispose(bool dispose)
+        {
+            if (_state == TransactionState.Disposed)
+            {
+                return;
+            }
+
             ENSURE(_state != TransactionState.Disposed, "transaction must be active before call Done");
 
             // clean snapshots if there is no commit/rollback
@@ -409,6 +429,12 @@ public void Dispose()
             _reader.Dispose();
 
             _state = TransactionState.Disposed;
+
+            if (!dispose)
+            {
+                // Remove transaction monitor's dictionary
+                _monitor.ReleaseTransaction(this);
+            }
         }
     }
 }
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