Fixed CompareFunction being collected by GC

Author: ilyalukyanov

src/LightningDB/DatabaseOptions.cs

@@ -49,7 +49,7 @@ private static void SetNativeCompareFunction(
             var compareFunction = CreateNativeCompareFunction(db, comparer);
 
             NativeMethods.Execute(lib => setter.Invoke(lib, compareFunction));
-            tran.SubTransactionsManager.StoreComparer(comparer);
+            tran.SubTransactionsManager.StoreCompareFunction(compareFunction);
         }
 
         internal void SetComparer(LightningTransaction tran, LightningDatabase db)

src/LightningDB/Factories/TransactionManager.cs

@@ -16,7 +16,7 @@ class TransactionManager
         private readonly ConcurrentDictionary<LightningTransaction, bool> _transactions;
 
         //prevent delegated from being collected by GC by storing them in collection
-        private readonly ConcurrentDictionary<LightningCompareDelegate, bool> _comparatorsStore;
+        private readonly ConcurrentDictionary<CompareFunction, bool> _comparatorsStore;
 
         public TransactionManager(LightningEnvironment environment, LightningTransaction parentTransaction)
         {
@@ -31,7 +31,7 @@ public TransactionManager(LightningEnvironment environment, LightningTransaction
                 : IntPtr.Zero;
 
             _transactions = new ConcurrentDictionary<LightningTransaction, bool>();
-            _comparatorsStore = new ConcurrentDictionary<LightningCompareDelegate, bool>();
+            _comparatorsStore = new ConcurrentDictionary<CompareFunction, bool>();
         }
 
         private void EnsureEnvironmentOpened()
@@ -75,9 +75,9 @@ public void AbortAll()
             AbortAll(this);
         }
 
-        public void StoreComparer(LightningCompareDelegate comparer)
+        public void StoreCompareFunction(CompareFunction compareFunction)
         {
-            _comparatorsStore.TryAdd(comparer, true);
+            _comparatorsStore.TryAdd(compareFunction, true);
         }
     }
 }