Improve error messages when database access is disposed (#174)

csharp/Platform.Data.Doublets.Tests/DisposalErrorMessagesTests.cs

@@ -0,0 +1,72 @@
+using System;
+using System.IO;
+using Xunit;
+using Platform.Data.Doublets.Memory.United.Generic;
+using Platform.Memory;
+
+namespace Platform.Data.Doublets.Tests
+{
+    /// <summary>
+    /// Tests to verify that better error messages are shown when database access is disposed
+    /// right after the access is created (GitHub issue #174)
+    /// </summary>
+    public static class DisposalErrorMessagesTests
+    {
+        [Fact]
+        public static void DisposedLinksThrowObjectDisposedExceptionWithMeaningfulMessage()
+        {
+            var links = new UnitedMemoryLinks<uint>(new HeapResizableDirectMemory());
+
+            // Create a link and then dispose
+            var link = links.Create();
+            links.Dispose();
+
+            // Test Count method
+            var ex = Assert.Throws<ObjectDisposedException>(() => links.Count());
+            Assert.Contains("Cannot access a disposed Links instance", ex.Message);
+            Assert.Contains("database connection has been closed", ex.Message);
+
+            // Test Create method
+            ex = Assert.Throws<ObjectDisposedException>(() => links.Create());
+            Assert.Contains("Cannot access a disposed Links instance", ex.Message);
+
+            // Test Delete method
+            ex = Assert.Throws<ObjectDisposedException>(() => links.Delete(link));
+            Assert.Contains("Cannot access a disposed Links instance", ex.Message);
+
+            // Test Each method  
+            ex = Assert.Throws<ObjectDisposedException>(() => links.Each(handler: l => links.Constants.Continue));
+            Assert.Contains("Cannot access a disposed Links instance", ex.Message);
+
+            // Test Update method
+            ex = Assert.Throws<ObjectDisposedException>(() => links.Update(new[] { link }, new[] { link }));
+            Assert.Contains("Cannot access a disposed Links instance", ex.Message);
+        }
+
+        [Fact]
+        public static void DisposedLinksObjectNameIsCorrectInException()
+        {
+            var links = new UnitedMemoryLinks<uint>(new HeapResizableDirectMemory());
+            links.Dispose();
+
+            var ex = Assert.Throws<ObjectDisposedException>(() => links.Count());
+            Assert.Contains("UnitedMemoryLinks", ex.ObjectName);
+        }
+
+        [Fact] 
+        public static void NonDisposedLinksWorkNormally()
+        {
+            using var links = new UnitedMemoryLinks<uint>(new HeapResizableDirectMemory());
+
+            // These should all work normally without throwing ObjectDisposedException
+            var count = links.Count();
+            var link = links.Create();
+            links.Each(handler: l => links.Constants.Continue);
+            // Test update - create another link to update the first one
+            var link2 = links.Create();
+            links.Update(new[] { link }, new[] { link, link2, link2 });
+            links.Delete(link);
+            links.Delete(link2);
+        }
+    }
+}

csharp/Platform.Data.Doublets/Ffi/Links.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Platform.Converters;
 using Platform.Delegates;
@@ -181,6 +182,25 @@ public class Links<TLinkAddress> : DisposableBase, ILinks<TLinkAddress>  where T
 
         private readonly unsafe void* _ptr;
 
+        /// <summary>
+        ///     <para>
+        ///         Ensures that this instance has not been disposed.
+        ///     </para>
+        ///     <para></para>
+        /// </summary>
+        /// <exception cref="ObjectDisposedException">
+        ///     <para>Thrown when this instance has been disposed.</para>
+        ///     <para></para>
+        /// </exception>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        protected virtual void EnsureNotDisposed()
+        {
+            if (IsDisposed)
+            {
+                throw new ObjectDisposedException(GetType().Name, "Cannot access a disposed Links instance. The database connection has been closed and is no longer available for operations.");
+            }
+        }
+
         public Links(string path)
         {
             TLinkAddress t = default;
@@ -202,6 +222,7 @@ public Links(string path)
 
         public TLinkAddress Count(IList<TLinkAddress>? restriction)
         {
+            EnsureNotDisposed();
             var restrictionLength = restriction?.Count ?? 0;
             unsafe
             {
@@ -260,6 +281,7 @@ public TLinkAddress Count(IList<TLinkAddress>? restriction)
 
         public TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var restrictionLength = restriction?.Count ?? 0;
             unsafe
             {
@@ -322,6 +344,7 @@ public TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddr
 
         public TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var substitutionLength = substitution?.Count ?? 0;
             unsafe
             {
@@ -384,6 +407,7 @@ public TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLink
 
         public TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var restrictionLength = restriction?.Count ?? 0;
             var substitutionLength = substitution?.Count ?? 0;
             unsafe
@@ -469,6 +493,7 @@ public TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>
 
         public TLinkAddress Delete(IList<TLinkAddress>? restriction, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var restrictionLength = restriction?.Count ?? 0;
             unsafe
             {

csharp/Platform.Data.Doublets/Ffi/UInt32Links.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Platform.Converters;
 using Platform.Delegates;
@@ -17,6 +18,25 @@ public class UInt32Links : DisposableBase, ILinks<TLinkAddress>
 
         private readonly unsafe void* _ptr;
 
+        /// <summary>
+        ///     <para>
+        ///         Ensures that this instance has not been disposed.
+        ///     </para>
+        ///     <para></para>
+        /// </summary>
+        /// <exception cref="ObjectDisposedException">
+        ///     <para>Thrown when this instance has been disposed.</para>
+        ///     <para></para>
+        /// </exception>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        protected virtual void EnsureNotDisposed()
+        {
+            if (IsDisposed)
+            {
+                throw new ObjectDisposedException(GetType().Name, "Cannot access a disposed Links instance. The database connection has been closed and is no longer available for operations.");
+            }
+        }
+
         public UInt32Links(string path)
         {
             unsafe
@@ -30,6 +50,7 @@ public UInt32Links(string path)
 
         public TLinkAddress Count(IList<TLinkAddress>? restriction)
         {
+            EnsureNotDisposed();
             unsafe
             {
                 var array = stackalloc uint[restriction.Count];
@@ -43,6 +64,7 @@ public TLinkAddress Count(IList<TLinkAddress>? restriction)
 
         public TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             unsafe
             {
                 Methods.EachCallback_UInt32 callback = (link) => handler != null ? handler(new Link<TLinkAddress>(link.Index, link.Source, link.Target)) : Constants.Continue;
@@ -57,6 +79,7 @@ public TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddr
 
         public TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             unsafe
             {
                 Methods.CreateCallback_UInt32 callback = (before, after) => handler != null ? handler(new Link<TLinkAddress>(before.Index, before.Source, before.Target), new Link<TLinkAddress>(after.Index, after.Source, after.Target)) : Constants.Continue;
@@ -69,6 +92,7 @@ public TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLink
 
         public TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             unsafe
             {
                 var restrictionArray = stackalloc uint[restriction.Count];
@@ -88,6 +112,7 @@ public TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>
 
         public TLinkAddress Delete(IList<TLinkAddress>? restriction, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             unsafe
             {
                 var restrictionArray = stackalloc uint[restriction.Count];

csharp/Platform.Data.Doublets/Memory/Split/Generic/SplitMemoryLinksBase.cs

@@ -221,6 +221,25 @@ public virtual LinksConstants<TLinkAddress> Constants
         get;
     }
 
+    /// <summary>
+    ///     <para>
+    ///         Ensures that this instance has not been disposed.
+    ///     </para>
+    ///     <para></para>
+    /// </summary>
+    /// <exception cref="ObjectDisposedException">
+    ///     <para>Thrown when this instance has been disposed.</para>
+    ///     <para></para>
+    /// </exception>
+    [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
+    protected virtual void EnsureNotDisposed()
+    {
+        if (IsDisposed)
+        {
+            throw new ObjectDisposedException(GetType().Name, "Cannot access a disposed Links instance. The database connection has been closed and is no longer available for operations.");
+        }
+    }
+
     /// <summary>
     ///     <para>
     ///         Counts the substitution.
@@ -242,6 +261,7 @@ public virtual LinksConstants<TLinkAddress> Constants
     [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
     public virtual TLinkAddress Count(IList<TLinkAddress>? restriction)
     {
+        EnsureNotDisposed();
         // Если нет ограничений, тогда возвращаем общее число связей находящихся в хранилище.
         if (restriction.Count == 0)
         {
@@ -433,6 +453,7 @@ public virtual TLinkAddress Count(IList<TLinkAddress>? restriction)
     [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
     public virtual TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddress>? handler)
     {
+        EnsureNotDisposed();
         var constants = Constants;
         var @break = constants.Break;
         if (restriction.Count == 0)
@@ -612,6 +633,7 @@ public virtual TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<T
     [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
     public virtual TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
     {
+        EnsureNotDisposed();
         var constants = Constants;
         var @null = constants.Null;
         var externalReferencesRange = constants.ExternalReferencesRange;
@@ -693,6 +715,7 @@ public virtual TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLink
     [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
     public virtual TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
     {
+        EnsureNotDisposed();
         ref var header = ref GetHeaderReference();
         var freeLink = header.FirstFreeLink;
         if ((freeLink != Constants.Null))
@@ -734,6 +757,7 @@ public virtual TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandl
     [MethodImpl(methodImplOptions: MethodImplOptions.AggressiveInlining)]
     public virtual TLinkAddress Delete(IList<TLinkAddress>? restriction, WriteHandler<TLinkAddress>? handler)
     {
+        EnsureNotDisposed();
         ref var header = ref GetHeaderReference();
         var link = restriction[index: Constants.IndexPart];
         var before = GetLinkStruct(linkIndex: link);

csharp/Platform.Data.Doublets/Memory/United/Generic/UnitedMemoryLinksBase.cs

@@ -114,6 +114,25 @@ public virtual LinksConstants<TLinkAddress> Constants
             get;
         }
 
+        /// <summary>
+        ///     <para>
+        ///         Ensures that this instance has not been disposed.
+        ///     </para>
+        ///     <para></para>
+        /// </summary>
+        /// <exception cref="ObjectDisposedException">
+        ///     <para>Thrown when this instance has been disposed.</para>
+        ///     <para></para>
+        /// </exception>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        protected virtual void EnsureNotDisposed()
+        {
+            if (IsDisposed)
+            {
+                throw new ObjectDisposedException(GetType().Name, "Cannot access a disposed Links instance. The database connection has been closed and is no longer available for operations.");
+            }
+        }
+
         /// <summary>
         /// <para>
         /// Initializes a new <see cref="UnitedMemoryLinksBase"/> instance.
@@ -207,6 +226,7 @@ protected virtual void Init(IResizableDirectMemory memory, long memoryReservatio
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public virtual TLinkAddress Count(IList<TLinkAddress>? restriction)
         {
+            EnsureNotDisposed();
             // Если нет ограничений, тогда возвращаем общее число связей находящихся в хранилище.
             if (restriction.Count == 0)
             {
@@ -340,6 +360,7 @@ public virtual TLinkAddress Count(IList<TLinkAddress>? restriction)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public virtual TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var constants = Constants;
             var @break = constants.Break;
             if (restriction.Count == 0)
@@ -472,6 +493,7 @@ public virtual TLinkAddress Each(IList<TLinkAddress>? restriction, ReadHandler<T
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public virtual TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             var constants = Constants;
             var @null = constants.Null;
             var linkIndex = this.GetIndex(restriction);
@@ -508,6 +530,7 @@ public virtual TLinkAddress Update(IList<TLinkAddress>? restriction, IList<TLink
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public virtual TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             ref var header = ref GetHeaderReference();
             var freeLink = header.FirstFreeLink;
             if (!AreEqual(freeLink, Constants.Null))
@@ -547,6 +570,7 @@ public virtual TLinkAddress Create(IList<TLinkAddress>? substitution, WriteHandl
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public virtual TLinkAddress Delete(IList<TLinkAddress>? restriction, WriteHandler<TLinkAddress>? handler)
         {
+            EnsureNotDisposed();
             ref var header = ref GetHeaderReference();
             var link = restriction[Constants.IndexPart];
             var before = GetLinkStruct(link);