Improve ArraySegment debugging #90488

pedrobsaila · 2023-08-13T16:56:58Z

ghost · 2023-08-13T16:57:10Z

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Issue Details

Author:	pedrobsaila
Assignees:	-
Labels:	`area-System.Runtime`
Milestone:	-

huoyaoyuan · 2023-08-14T01:34:52Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+        /// For <see cref="ArraySegment{Char}"/>, returns a new instance of string that represents the characters pointed to by the segment.
+        /// Otherwise, returns a <see cref="string"/> with the name of the type and the number of elements.
+        /// </summary>
+        public override string ToString()


Using ToString is an observable behavior change. The common approach is using a private property called DebuggerDisplay.

huoyaoyuan · 2023-08-14T01:38:38Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+            if (typeof(T) == typeof(char))
+            {
+                StringBuilder stringBuilder = new StringBuilder(_count);
+
+                for (int i = 0; i < _count; i++)
+                {
+                    T element = this[i];
+                    stringBuilder.Append(Unsafe.As<T, char>(ref element));
+                }
+
+                return stringBuilder.ToString();
+            }


Don't use a StringBuilder, just call string constructor like ReadOnlySpan<T>.ToString.

stephentoub · 2023-08-14T10:21:40Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+        {
+            if (typeof(T) == typeof(char))
+            {
+                return new string(new ReadOnlySpan<char>(ref Unsafe.As<T, char>(ref _array![_offset]), _count));


Suggested change

return new string(new ReadOnlySpan<char>(ref Unsafe.As<T, char>(ref _array![_offset]), _count));

return AsSpan().ToString();

stephentoub · 2023-08-14T10:24:00Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+        private sealed class ArraySegmentDebugView<U>
+        {
+            private readonly U[] _array;
+
+            public ArraySegmentDebugView(ArraySegment<U> arraySegments)
+            {
+                _array = arraySegments.ToArray();
+            }
+
+            [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
+            public U[] Items => _array;
+        }


Suggested change

private sealed class ArraySegmentDebugView<U>

{

private readonly U[] _array;

public ArraySegmentDebugView(ArraySegment<U> arraySegments)

{

_array = arraySegments.ToArray();

}

[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]

public U[] Items => _array;

}

private sealed class ArraySegmentDebugView(ArraySegment<T> array)

{

[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]

public T[] Items => array.AsSpan().ToArray();

}

Have we started to roll-in primary constructor in runtime?

Yes, for simple uses like debugger type proxies.

stephentoub · 2023-08-14T16:46:30Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+        private sealed class ArraySegmentDebugView<U>(ArraySegment<U> array)
+        {
+            [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
+            public U[] Items => array.AsSpan().ToArray();
+        }


As a nested type, this should not introduce another generic type parameter.

Suggested change

private sealed class ArraySegmentDebugView<U>(ArraySegment<U> array)

{

[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]

public U[] Items => array.AsSpan().ToArray();

}

private sealed class ArraySegmentDebugView(ArraySegment<T> array)

{

[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]

public T[] Items => array.AsSpan().ToArray();

}

It fails on compilation with CS0416 error : '.System.ArraySegment.ArraySegmentDebugView': an attribute argument cannot use type parameters

See https://github.com/dotnet/runtime/runs/15879904568

The attribute should be:

[DebuggerTypeProxy(typeof(ArraySegment<>.ArraySegmentDebugView))]

thanks for the help ^^

MichalPetryka · 2023-08-16T18:17:03Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+                return this.AsSpan().ToString();
+            }
+
+            return $"System.ArraySegment<{typeof(T).Name}>[{_count}]";


The original issue wanted the elements to be displayed in such case I think.

I'm not sure to understand. What is the issue exactly with this implementation ?

The original issue wanted the elements to be displayed in such case I think.

We don't do that for other collections. I'm not sure why we'd do it here.

Can someone explains to me what should be done here ? I used the same code as the one for Span

See Span debugging support for ideas of improvement.

runtime/src/libraries/System.Private.CoreLib/src/System/Span.cs

Lines 376 to 387 in ac02b66

/// <summary>

/// For <see cref="Span{Char}"/>, returns a new instance of string that represents the characters pointed to by the span.

/// Otherwise, returns a <see cref="string"/> with the name of the type and the number of elements.

/// </summary>

public override string ToString()

{

if (typeof(T) == typeof(char))

{

return new string(new ReadOnlySpan<char>(ref Unsafe.As<T, char>(ref _reference), _length));

}

return $"System.Span<{typeof(T).Name}>[{_length}]";

}

For types with a Count such as this, the debugger display usually displays Count = XXX.

e.g.

runtime/src/libraries/System.ObjectModel/src/System/Collections/ObjectModel/KeyedCollection.cs

Line 12 in f9b07d4

[DebuggerDisplay("Count = {Count}")]

I would lean towards doing that. However, I don't own this code. @stephentoub or someone else on the dotnet/runtime team, could you clarify what the debugger display should be?

adamsitnik

@pedrobsaila thank you for your contribution!

I think that we can simplify the solution, PTAL at my suggestion. Thank you!

adamsitnik · 2023-10-27T11:51:54Z

src/libraries/System.Private.CoreLib/src/System/ArraySegment.cs

+    [DebuggerDisplay("{DebuggerToString(),nq}")]
+    [DebuggerTypeProxy(typeof(ArraySegment<>.ArraySegmentDebugView))]


I believe that we should simply mimic what List<T> does:

https://github.com/dotnet/runtime/blob/568ed4125d0ae62c0d82d8f3703854fcc04bf32d/src/libraries/System.Private.CoreLib/src/System/Collections/Generic/List.cs#L17C1-L18

ArraySegment<T> implements IList<T> which extends ICollection<T> so it should work OOTB without any other code changes being required

Suggested change

[DebuggerDisplay("{DebuggerToString(),nq}")]

[DebuggerTypeProxy(typeof(ArraySegment<>.ArraySegmentDebugView))]

[DebuggerTypeProxy(typeof(ICollectionDebugView<>))]

[DebuggerDisplay("Count = {Count}")]

adamsitnik

LGTM, thank you @pedrobsaila !

Improve ArraySegment debugging

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dotnet-issue-labeler bot added the area-System.Runtime label Aug 13, 2023

ghost added the community-contribution Indicates that the PR has been added by a community member label Aug 13, 2023

fix build

451deac

huoyaoyuan reviewed Aug 14, 2023

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fix remarks

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stephentoub reviewed Aug 14, 2023

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pedrobsaila added 3 commits August 14, 2023 13:41

fix remark 2

18511fc

fix build

9c7de7c

fix build 2

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build-analysis bot mentioned this pull request Aug 14, 2023

Microsoft.Extensions.SourceGeneration.Configuration.Binder.Tests.ConfigurationBinderTests.GetCanReadStaticProperty failed #88843

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stephentoub reviewed Aug 14, 2023

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drop generics

84f43fa

build-analysis bot mentioned this pull request Aug 14, 2023

Test failure readytorun/GenericCycleDetection/Depth3Test/Depth3Test.sh #88586

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MichalPetryka reviewed Aug 16, 2023

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adamsitnik requested changes Oct 27, 2023

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ghost added the needs-author-action An issue or pull request that requires more info or actions from the author. label Oct 27, 2023

adamsitnik self-assigned this Oct 27, 2023

pedrobsaila added 2 commits October 28, 2023 11:44

Merge remote-tracking branch 'upstream/main' into 88961

c06836c

use simpler solution

f220fdb

ghost removed the needs-author-action An issue or pull request that requires more info or actions from the author. label Oct 28, 2023

clean DebuggerToString

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This was referenced Oct 28, 2023

Timeout in System.Net.Quic.Functional.Tests #86019

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CI error: System.Net.Quic.QuicException: The connection timed out from inactivity #91757

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adamsitnik approved these changes Oct 30, 2023

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adamsitnik merged commit e5c631d into dotnet:main Oct 30, 2023
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adamsitnik added this to the 9.0.0 milestone Oct 30, 2023

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Improve ArraySegment debugging #90488

Improve ArraySegment debugging #90488

pedrobsaila commented Aug 13, 2023

ghost commented Aug 13, 2023

huoyaoyuan Aug 14, 2023

huoyaoyuan Aug 14, 2023

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	return new string(new ReadOnlySpan<char>(ref Unsafe.As<T, char>(ref _array![_offset]), _count));
	return AsSpan().ToString();

	/// <summary>
	/// For <see cref="Span{Char}"/>, returns a new instance of string that represents the characters pointed to by the span.
	/// Otherwise, returns a <see cref="string"/> with the name of the type and the number of elements.
	/// </summary>
	public override string ToString()
	{
	if (typeof(T) == typeof(char))
	{
	return new string(new ReadOnlySpan<char>(ref Unsafe.As<T, char>(ref _reference), _length));
	}
	return $"System.Span<{typeof(T).Name}>[{_length}]";
	}

		[DebuggerDisplay("{DebuggerToString(),nq}")]
		[DebuggerTypeProxy(typeof(ArraySegment<>.ArraySegmentDebugView))]

Improve ArraySegment debugging #90488

Improve ArraySegment debugging #90488

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