Avoid boxing when structs are used as collection keys. #69443
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Change several structs to record structs such that they no longer are boxed when used as keys in MultiDictionary's internal ImmutableHashSet. When MultiDictionary's value is a struct and is created without specifying the value's IEqualityComparer, the default struct comparer is used. This equality comparer is notoriously slow due to boxing. By switching these structs to record structs, an implementation of IEquatable is generated and the default struct equality comparer isn't used. Addresses dotnet#69165 Sam mentioned that there is an issue already logged in the roslyn-analyzers repo around adding an analyzer to detect this. dotnet/roslyn-analyzers#1640
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sharwell
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Aug 9, 2023
| @@ -20,7 +20,7 @@ internal enum HighlightSpanKind | |||
| } | |||
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| [DataContract] | |||
| internal readonly struct HighlightSpan | |||
| internal readonly record struct HighlightSpan | |||
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➡️ This type isn't used as a dictionary key, but rather as a dictionary value in a type that happens to create a set from the values.
CyrusNajmabadi
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Aug 9, 2023
sharwell
reviewed
Aug 9, 2023
| @@ -63,11 +62,11 @@ private string GetDebuggerDisplay() | |||
| => Name + ", " + ParentIndex; | |||
| } | |||
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| private readonly struct ParameterTypeInfo(string name, bool isComplex, bool isArray) | |||
| private readonly record struct ParameterTypeInfo(string name, bool isComplex, bool isArray) | |||
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➡️ This type isn't used as a dictionary key, but rather as a dictionary value in a type that happens to create a set from the values.
genlu
approved these changes
Aug 10, 2023
ghost
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Change several structs to record structs such that they no longer are boxed when used as keys in MultiDictionary's internal ImmutableHashSet. When MultiDictionary's value is a struct and is created without specifying the value's IEqualityComparer, the default struct comparer is used. This equality comparer is notoriously slow due to boxing. By switching these structs to record structs, an implementation of IEquatable is generated and the default struct equality comparer isn't used.
Addresses #69165
Sam mentioned that there is an issue already logged in the roslyn-analyzers repo around adding an analyzer to detect this.
dotnet/roslyn-analyzers#1640