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Don't hold onto references in Consumer #2191

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Merged
merged 3 commits into from
Feb 13, 2023
Merged

Don't hold onto references in Consumer #2191

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60b21b0
Don't store references in Consumer.
timcassell Oct 27, 2022
df10294
Removed reference check as it's no longer necessary.
timcassell Oct 27, 2022
bdb4037
Overwrite field to null instead of calling DeadCodeEliminationHelper.…
timcassell Oct 30, 2022
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38 changes: 21 additions & 17 deletions src/BenchmarkDotNet/Engines/Consumer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ private static readonly HashSet<Type> SupportedTypes
.Where(field => !field.IsStatic) // exclude this HashSet itself
.Select(field => field.FieldType));

#pragma warning disable IDE0052 // Remove unread private members
private volatile byte byteHolder;
private volatile sbyte sbyteHolder;
private volatile short shortHolder;
Expand All @@ -30,10 +31,10 @@ private static readonly HashSet<Type> SupportedTypes
private double doubleHolder;
private long longHolder;
private ulong ulongHolder;
private string stringHolder;
private object objectHolder;
private IntPtr ptrHolder;
private UIntPtr uptrHolder;
private volatile object objectHolder;
private volatile IntPtr ptrHolder;
private volatile UIntPtr uptrHolder;
#pragma warning restore IDE0052 // Remove unread private members

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
Expand Down Expand Up @@ -84,11 +85,11 @@ private static readonly HashSet<Type> SupportedTypes

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
public void Consume(IntPtr intPtrValue) => Volatile.Write(ref ptrHolder, intPtrValue);
public void Consume(IntPtr intPtrValue) => ptrHolder = intPtrValue;

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
public void Consume(UIntPtr uintPtrValue) => Volatile.Write(ref uptrHolder, uintPtrValue);
public void Consume(UIntPtr uintPtrValue) => uptrHolder = uintPtrValue;

[CLSCompliant(false)]
[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand All @@ -97,22 +98,28 @@ private static readonly HashSet<Type> SupportedTypes

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
public void Consume(string stringValue) => Volatile.Write(ref stringHolder, stringValue);
public void Consume(string stringValue) => Consume((object) stringValue);

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
public void Consume(object objectValue) => Volatile.Write(ref objectHolder, objectValue);
public void Consume(object objectValue)
{
// Write to volatile field to prevent dead code elimination and out-of-order execution.
objectHolder = objectValue;
// Overwrite field to null so we aren't holding onto references to affect GC behavior. (#1942)
objectHolder = null;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[PublicAPI]
public void Consume<T>(T objectValue) where T : class // class constraint prevents from boxing structs
=> Volatile.Write(ref objectHolder, objectValue);
=> Consume((object) objectValue);

[MethodImpl(MethodImplOptions.AggressiveInlining)]
public unsafe void Consume<T>(T* ptrValue) where T: unmanaged => Volatile.Write(ref ptrHolder, (IntPtr)ptrValue);
public unsafe void Consume<T>(T* ptrValue) where T : unmanaged => ptrHolder = (IntPtr) ptrValue;

[MethodImpl(MethodImplOptions.AggressiveInlining)]
public unsafe void Consume(void* ptrValue) => Volatile.Write(ref ptrHolder, (IntPtr)ptrValue);
public unsafe void Consume(void* ptrValue) => ptrHolder = (IntPtr) ptrValue;

[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Consume<T>(in T value)
Expand Down Expand Up @@ -141,15 +148,12 @@ public void Consume<T>(in T value)
Volatile.Write(ref longHolder, (long)(object)value);
else if (typeof(T) == typeof(ulong))
Volatile.Write(ref ulongHolder, (ulong)(object)value);
else if (default(T) == null)
objectHolder = (object) value;
else if (default(T) == null && !typeof(T).IsValueType)
Consume((object) value);
else
ValueTypesConsumer(value); // non-primitive value types
DeadCodeEliminationHelper.KeepAliveWithoutBoxingReadonly(value); // non-primitive and nullable value types
}

[MethodImpl(MethodImplOptions.NoInlining)]
private void ValueTypesConsumer<T>(in T _) { }

internal static bool IsConsumable(Type type)
=> SupportedTypes.Contains(type) || type.GetTypeInfo().IsClass || type.GetTypeInfo().IsInterface;

Expand Down