探索一下 Enum 最佳化

victor.x.qu發表於2024-08-31

探索一下 Enum 最佳化

SV.Enums主要是探索如何讓 enum 更高效

其中涉及的最佳化手段並非完全自創

很多內容參考於以下專案

  • NetEscapades.EnumGenerators
  • FastEnum
  • runtime

主要最佳化手段

其實主要全是 空間換時間，大量快取

封裝入口方法以及 source-generators 生成

不過本專案嘗試了封裝入口方法、ModuleInitializer、source-generators 來避免對使用影響（其實更主要是嘗試如何避免使用interceptors）

    public static class Enums<T> where T : struct, Enum
    {
        public static bool IsFlags => CheckInfo().IsFlags;
        public static bool IsEmpty => CheckInfo().IsEmpty;

        internal static IEnumInfo<T> Info;

        [MethodImpl(Enums.Optimization)]
        internal static IEnumInfo<T> CheckInfo()
        {
            if (Info == null)
            {
                Info = new EnumInfo<T>();
            }
            return Info;
        }

        public static T Parse(string name, bool ignoreCase)
        {
            if (CheckInfo().TryParse(name, ignoreCase, out var result))
                return result;
            throw new ArgumentException($"Specified value '{name}' is not defined.", nameof(name));
        }

這樣做主要就可以利用 source-generators 生成enum 處理程式碼，

並透過 ModuleInitializer 在執行時啟用生成的enum程式碼

如下為生成enum 程式碼示例

internal class EnumInfoAD125120120540FC9AA056E2DD394A7C : EnumBase<global::Benchmark.Fruits2>
    {
        public override bool IsDefined(string name)
        {
            return name switch
            {
                nameof(global::Benchmark.Fruits2.Apple) => true,
nameof(global::Benchmark.Fruits2.Lemon) => true,
nameof(global::Benchmark.Fruits2.Melon) => true,
nameof(global::Benchmark.Fruits2.Banana) => true,
                _ => false,
            };
        }

        public override string? GetName(global::Benchmark.Fruits2 t)
        {
            switch (t)
            {
                case global::Benchmark.Fruits2.Apple: return nameof(global::Benchmark.Fruits2.Apple);
case global::Benchmark.Fruits2.Lemon: return nameof(global::Benchmark.Fruits2.Lemon);
case global::Benchmark.Fruits2.Melon: return nameof(global::Benchmark.Fruits2.Melon);
case global::Benchmark.Fruits2.Banana: return nameof(global::Benchmark.Fruits2.Banana);
                default:
                    return null;
            }
        }

        protected override bool TryParseCase(in ReadOnlySpan<char> name, out global::Benchmark.Fruits2 result)
        {
            switch (name)
            {
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Apple).AsSpan(), global::System.StringComparison.Ordinal):
                    result = global::Benchmark.Fruits2.Apple;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Lemon).AsSpan(), global::System.StringComparison.Ordinal):
                    result = global::Benchmark.Fruits2.Lemon;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Melon).AsSpan(), global::System.StringComparison.Ordinal):
                    result = global::Benchmark.Fruits2.Melon;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Banana).AsSpan(), global::System.StringComparison.Ordinal):
                    result = global::Benchmark.Fruits2.Banana;
                    return true;
                default:
                    result = default;
                    return false;
            }
        }

        protected override bool TryParseIgnoreCase(in ReadOnlySpan<char> name, out global::Benchmark.Fruits2 result)
        {
            switch (name)
            {
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Apple).AsSpan(), global::System.StringComparison.OrdinalIgnoreCase):
                    result = global::Benchmark.Fruits2.Apple;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Lemon).AsSpan(), global::System.StringComparison.OrdinalIgnoreCase):
                    result = global::Benchmark.Fruits2.Lemon;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Melon).AsSpan(), global::System.StringComparison.OrdinalIgnoreCase):
                    result = global::Benchmark.Fruits2.Melon;
                    return true;
                case ReadOnlySpan<char> current when current.Equals(nameof(global::Benchmark.Fruits2.Banana).AsSpan(), global::System.StringComparison.OrdinalIgnoreCase):
                    result = global::Benchmark.Fruits2.Banana;
                    return true;
                default:
                    result = default;
                    return false;
            }
        }
    }

        internal static partial class EnumsF1029F0E5915401BBDD8559E2B5289B1
    {
        [ModuleInitializer]
        internal static void Init4771B8A4BD2E4761973279D81E61089C()
        {
            global::SV.Enums.SetEnumInfo<global::Benchmark.Fruits2>(new EnumInfoAD125120120540FC9AA056E2DD394A7C());
        }
    }

不過這樣封裝入口，存在一定效能損失

空間換時間

當然如果不使用 source-generators， 對應功能也有預設實現

部分程式碼如下， 大部分東西都記憶體快取了

    public class EnumInfo<T> : IEnumInfo<T> where T : struct, Enum
    {
        private readonly string[] names;
        private readonly T[] values;
        private readonly (string Name, T Value)[] members;
        private readonly FastReadOnlyDictionary<string, T> membersByName;
        private readonly FastReadOnlyDictionary<T, (string Name, EnumMemberAttribute Member, FastReadOnlyDictionary<int, string> Labels)> namesByMember;
        private readonly Type underlyingType;
        private readonly TypeCode underlyingTypeCode;

        public bool IsFlags { get; private set; }
        public bool IsEmpty => values.Length == 0;

        public EnumInfo() : base()
        {
            var t = typeof(T);
            names = Enum.GetNames(t);
            members = names.Select(i => (i, (T)Enum.Parse(t, i))).ToArray();
            values = members.Select(i => i.Value).ToArray();
            membersByName = members.ToFastReadOnlyDictionary(i => i.Name, i => i.Value);
            namesByMember = membersByName.AsEnumerable().DistinctBy(i => i.Value).ToFastReadOnlyDictionary(i => i.Value, i =>
            {
                var fieldInfo = t.GetField(i.Key)!;
                return (i.Key, fieldInfo.GetCustomAttribute<EnumMemberAttribute>(), fieldInfo.GetCustomAttributes<LabelAttribute>().DistinctBy(i => i.Index).ToFastReadOnlyDictionary(x => x.Index, x => x.Value));
            });
            underlyingType = Enum.GetUnderlyingType(t);
            underlyingTypeCode = Type.GetTypeCode(underlyingType);
            IsFlags = t.IsDefined(typeof(FlagsAttribute), true);
        }

        [MethodImpl(Enums.Optimization)]
        public bool TryParseIgnoreCase(in ReadOnlySpan<char> name, out T result)
        {
            foreach (var member in members.AsSpan())
            {
                if (name.Equals(member.Name.AsSpan(), StringComparison.OrdinalIgnoreCase))
                {
                    result = member.Value;
                    return true;
                }
            }
            result = default;
            return false;
        }

enum 轉換方法

同時提供一些 不用拆箱裝箱的 enum 轉換方法，裡面移除了型別檢查的邏輯，所以理論只能保證正常使用不會有問題

public static T ToEnum(int value)

public static T ToEnum(byte value)

public static T ToEnum(Int16 value)

public static T ToEnum(Int64 value)

...

效能測試

簡單做下效能測試， 部分程式碼如下

public enum Fruits
    {
        Apple,
        Lemon,
        Melon,
        Banana,
        Lemon1,
        Melon2,
        Banana3,
        Lemon11,
        Melon21,
        Banana31,
        Lemon12,
        Melon22,
        Banana32,
        Lemon13,
        Melon23,
        Banana33,
        Lemon131,
        Melon231,
        Banana331,
        Lemon14,
        Melon24,
        Banana34,
    }

    [MemoryDiagnoser, Orderer(summaryOrderPolicy: SummaryOrderPolicy.FastestToSlowest), GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByCategory), CategoriesColumn]
    public class EnumBenchmarks
    {
        private readonly EnumInfo<Fruits> test;

        public EnumBenchmarks()
        {
            test = new EnumInfo<Fruits>();
        }

        [Benchmark(Baseline = true), BenchmarkCategory("IgnoreCase")]
        public Fruits ParseIgnoreCase()
        {
            return Enum.Parse<Fruits>("melon", true);
        }

        [Benchmark, BenchmarkCategory("IgnoreCase")]
        public Fruits FastEnumParseIgnoreCase()
        {
            return FastEnum.Parse<Fruits>("melon", true);
        }

        [Benchmark, BenchmarkCategory("IgnoreCase")]
        public Fruits SVEnumsParseIgnoreCase()
        {
            Enums<Fruits>.TryParse("melon", true, out var v);
            return v;
        }

        [Benchmark, BenchmarkCategory("IgnoreCase")]
        public Fruits EnumInfoParseIgnoreCase()
        {
            test.TryParse("melon", true, out var v);
            return v;
        }

        [Benchmark(Baseline = true)]
        public Fruits Parse()
        {
            return Enum.Parse<Fruits>("Melon", false);
        }

        [Benchmark]
        public Fruits FastEnumParse()
        {
            return FastEnum.Parse<Fruits>("Melon", false);
        }

        [Benchmark]
        public Fruits SVEnumsParse()
        {
            Enums<Fruits>.TryParse("Melon", out var v);
            return v;
        }

        [Benchmark]
        public Fruits EnumInfoParse()
        {
            test.TryParse("Melon", false, out var v);
            return v;
        }

        ...

    [MemoryDiagnoser, Orderer(summaryOrderPolicy: SummaryOrderPolicy.FastestToSlowest), GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByCategory), CategoriesColumn]
    public class ToEnumBenchmarks
    {
        private readonly EnumInfo<Fruits> test;

        public ToEnumBenchmarks()
        {
            test = new EnumInfo<Fruits>();
            //Enums.SetEnumInfo<Fruits>(new TestIEnumInfo());
        }

        [Benchmark(Baseline = true), BenchmarkCategory("ToEnumInt")]
        public Fruits ToEnumInt()
        {
            return (Fruits)Enum.ToObject(typeof(Fruits), 11);
        }

        [Benchmark, BenchmarkCategory("ToEnumInt")]
        public Fruits SVEnumsToEnumInt()
        {
            return Enums<Fruits>.ToEnum(11);
        }

        [Benchmark, BenchmarkCategory("ToEnumInt")]
        public Fruits ToEnumIntByte()
        {
            return (Fruits)Enum.ToObject(typeof(Fruits), (byte)11);
        }

        [Benchmark, BenchmarkCategory("ToEnumInt")]
        public Fruits SVEnumsToEnumIntByte()
        {
            return Enums<Fruits>.ToEnum((byte)11);
        }

        [Benchmark, BenchmarkCategory("ToEnumInt")]
        public Fruits ToEnumIntObject()
        {
            return (Fruits)Enum.ToObject(typeof(Fruits), (object)11);
        }

        [Benchmark, BenchmarkCategory("ToEnumInt")]
        public Fruits SVEnumsToEnumIntObject()
        {
            return Enums<Fruits>.ToEnum((object)11);
        }
    }

結果如下


BenchmarkDotNet v0.14.0, Windows 10 (10.0.19045.4651/22H2/2022Update)
Intel Core i7-10700 CPU 2.90GHz, 1 CPU, 16 logical and 8 physical cores
.NET SDK 9.0.100-preview.5.24307.3
  [Host]     : .NET 8.0.6 (8.0.624.26715), X64 RyuJIT AVX2
  DefaultJob : .NET 8.0.6 (8.0.624.26715), X64 RyuJIT AVX2
Method Mean Error StdDev Median Ratio RatioSD Gen0 Allocated Alloc Ratio
SVEnumsToEnumInt 0.9796 ns 0.0062 ns 0.0055 ns 0.9781 ns 0.02 0.00 - - 0.00
SVEnumsToEnumIntByte 1.0990 ns 0.0089 ns 0.0074 ns 1.0966 ns 0.03 0.00 - - 0.00
SVEnumsToEnumIntObject 5.1211 ns 0.0842 ns 0.0746 ns 5.1295 ns 0.12 0.00 0.0029 24 B 1.00
ToEnumIntByte 40.9720 ns 0.2100 ns 0.1861 ns 40.9065 ns 1.00 0.03 0.0029 24 B 1.00
ToEnumInt 41.1962 ns 0.8452 ns 1.4122 ns 40.4985 ns 1.00 0.05 0.0029 24 B 1.00
ToEnumIntObject 48.2590 ns 0.4380 ns 0.3882 ns 48.0802 ns 1.17 0.04 0.0057 48 B 2.00
Method Categories Mean Error StdDev Ratio RatioSD Gen0 Gen1 Allocated Alloc Ratio
SVEnumsParse 2.8382 ns 0.0508 ns 0.0450 ns 0.12 0.00 - - - NA
FastEnumParse 6.9671 ns 0.0437 ns 0.0388 ns 0.28 0.00 - - - NA
EnumInfoParse 7.1513 ns 0.1049 ns 0.0930 ns 0.29 0.00 - - - NA
Parse 24.5338 ns 0.0548 ns 0.0485 ns 1.00 0.00 - - - NA
FastEnumGetName GetName 0.8608 ns 0.0175 ns 0.0155 ns 0.32 0.01 - - - NA
EnumInfoGetName GetName 1.4291 ns 0.0147 ns 0.0130 ns 0.54 0.01 - - - NA
SVEnumsGetName GetName 1.6210 ns 0.0148 ns 0.0131 ns 0.61 0.01 - - - NA
GetName GetName 2.6512 ns 0.0150 ns 0.0125 ns 1.00 0.01 - - - NA
SVEnumsGetNames GetNames 0.2539 ns 0.0061 ns 0.0051 ns 0.01 0.00 - - - 0.00
FastEnumGetNames GetNames 0.6874 ns 0.0195 ns 0.0163 ns 0.03 0.00 - - - 0.00
GetNames GetNames 21.0463 ns 0.4645 ns 0.5162 ns 1.00 0.03 0.0239 0.0001 200 B 1.00
SVEnumsGetValues GetValues 0.3022 ns 0.0296 ns 0.0277 ns 0.009 0.00 - - - 0.00
FastEnumGetValues GetValues 0.6683 ns 0.0098 ns 0.0082 ns 0.021 0.00 - - - 0.00
GetValues GetValues 32.5145 ns 0.6732 ns 0.5968 ns 1.000 0.03 0.0134 - 112 B 1.00
SVEnumsParseIgnoreCase IgnoreCase 3.0465 ns 0.0680 ns 0.0727 ns 0.12 0.00 - - - NA
EnumInfoParseIgnoreCase IgnoreCase 10.1299 ns 0.1660 ns 0.1472 ns 0.42 0.01 - - - NA
FastEnumParseIgnoreCase IgnoreCase 10.3531 ns 0.0807 ns 0.0674 ns 0.42 0.00 - - - NA
ParseIgnoreCase IgnoreCase 24.3767 ns 0.1270 ns 0.1060 ns 1.00 0.01 - - - NA
SVEnumsIsDefinedName IsDefinedName 2.7188 ns 0.0111 ns 0.0098 ns 0.11 0.00 - - - NA
EnumInfoIsDefinedName IsDefinedName 6.6075 ns 0.0190 ns 0.0148 ns 0.26 0.00 - - - NA
FastEnumIsDefinedName IsDefinedName 6.7011 ns 0.0388 ns 0.0303 ns 0.26 0.00 - - - NA
IsDefinedName IsDefinedName 25.3131 ns 0.2064 ns 0.1829 ns 1.00 0.01 - - - NA

完整程式碼參見 https://github.com/fs7744/Enums

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