Lazy

LazyInterface/LazyInterface.Tests/.editorconfig

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+[*.cs]
+
+# SA1600: Elements should be documented
+dotnet_diagnostic.SA1600.severity = none
+csharp_indent_labels = one_less_than_current
+csharp_style_throw_expression = true:suggestion
+csharp_style_prefer_null_check_over_type_check = true:suggestion
+
+[*.{cs,vb}]
+dotnet_style_operator_placement_when_wrapping = beginning_of_line
+tab_width = 4
+indent_size = 4
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggestion
+dotnet_style_prefer_auto_properties = true:silent
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_prefer_simplified_boolean_expressions = true:suggestion
+dotnet_style_prefer_conditional_expression_over_assignment = true:silent
+dotnet_style_prefer_conditional_expression_over_return = true:silent
+dotnet_style_explicit_tuple_names = true:suggestion
+dotnet_style_prefer_inferred_tuple_names = true:suggestion
+dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
+dotnet_style_prefer_compound_assignment = true:suggestion
+dotnet_style_prefer_simplified_interpolation = true:suggestion
+dotnet_style_prefer_collection_expression = when_types_loosely_match:suggestion
+dotnet_style_namespace_match_folder = true:suggestion
+[*.cs]
+#### Стили именования ####
+
+# Правила именования
+
+dotnet_naming_rule.interface_should_be_begins_with_i.severity = suggestion
+dotnet_naming_rule.interface_should_be_begins_with_i.symbols = interface
+dotnet_naming_rule.interface_should_be_begins_with_i.style = begins_with_i
+
+dotnet_naming_rule.types_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.types_should_be_pascal_case.symbols = types
+dotnet_naming_rule.types_should_be_pascal_case.style = pascal_case
+
+dotnet_naming_rule.non_field_members_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.non_field_members_should_be_pascal_case.symbols = non_field_members
+dotnet_naming_rule.non_field_members_should_be_pascal_case.style = pascal_case
+
+# Спецификации символов
+
+dotnet_naming_symbols.interface.applicable_kinds = interface
+dotnet_naming_symbols.interface.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.interface.required_modifiers = 
+
+dotnet_naming_symbols.types.applicable_kinds = class, struct, interface, enum
+dotnet_naming_symbols.types.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.types.required_modifiers = 
+
+dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
+dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.non_field_members.required_modifiers = 
+
+# Стили именования
+
+dotnet_naming_style.begins_with_i.required_prefix = I
+dotnet_naming_style.begins_with_i.required_suffix = 
+dotnet_naming_style.begins_with_i.word_separator = 
+dotnet_naming_style.begins_with_i.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+csharp_prefer_simple_default_expression = true:suggestion
+
+[*.vb]
+#### Стили именования ####
+
+# Правила именования
+
+dotnet_naming_rule.interface_should_be_начинается_с_i.severity = suggestion
+dotnet_naming_rule.interface_should_be_начинается_с_i.symbols = interface
+dotnet_naming_rule.interface_should_be_начинается_с_i.style = начинается_с_i
+
+dotnet_naming_rule.типы_should_be_всечастиспрописнойбуквы.severity = suggestion
+dotnet_naming_rule.типы_should_be_всечастиспрописнойбуквы.symbols = типы
+dotnet_naming_rule.типы_should_be_всечастиспрописнойбуквы.style = всечастиспрописнойбуквы
+
+dotnet_naming_rule.не_являющиеся_полем_члены_should_be_всечастиспрописнойбуквы.severity = suggestion
+dotnet_naming_rule.не_являющиеся_полем_члены_should_be_всечастиспрописнойбуквы.symbols = не_являющиеся_полем_члены
+dotnet_naming_rule.не_являющиеся_полем_члены_should_be_всечастиспрописнойбуквы.style = всечастиспрописнойбуквы
+
+# Спецификации символов
+
+dotnet_naming_symbols.interface.applicable_kinds = interface
+dotnet_naming_symbols.interface.applicable_accessibilities = public, friend, private, protected, protected_friend, private_protected
+dotnet_naming_symbols.interface.required_modifiers = 
+
+dotnet_naming_symbols.типы.applicable_kinds = class, struct, interface, enum
+dotnet_naming_symbols.типы.applicable_accessibilities = public, friend, private, protected, protected_friend, private_protected
+dotnet_naming_symbols.типы.required_modifiers = 
+
+dotnet_naming_symbols.не_являющиеся_полем_члены.applicable_kinds = property, event, method
+dotnet_naming_symbols.не_являющиеся_полем_члены.applicable_accessibilities = public, friend, private, protected, protected_friend, private_protected
+dotnet_naming_symbols.не_являющиеся_полем_члены.required_modifiers = 
+
+# Стили именования
+
+dotnet_naming_style.начинается_с_i.required_prefix = I
+dotnet_naming_style.начинается_с_i.required_suffix = 
+dotnet_naming_style.начинается_с_i.word_separator = 
+dotnet_naming_style.начинается_с_i.capitalization = pascal_case
+
+dotnet_naming_style.всечастиспрописнойбуквы.required_prefix = 
+dotnet_naming_style.всечастиспрописнойбуквы.required_suffix = 
+dotnet_naming_style.всечастиспрописнойбуквы.word_separator = 
+dotnet_naming_style.всечастиспрописнойбуквы.capitalization = pascal_case
+
+dotnet_naming_style.всечастиспрописнойбуквы.required_prefix = 
+dotnet_naming_style.всечастиспрописнойбуквы.required_suffix = 
+dotnet_naming_style.всечастиспрописнойбуквы.word_separator = 
+dotnet_naming_style.всечастиспрописнойбуквы.capitalization = pascal_case

LazyInterface/LazyInterface.Tests/CommonTests.cs

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+// <copyright file="CommonTests.cs" company="Kalinin Andrew">
+// Copyright (c) Kalinin Andrew. All rights reserved.
+// </copyright>
+
+namespace LazyInterface.Tests;
+
+public class CommonTests
+{
+    public static IEnumerable<ILazy<object>> LazyImplementations()
+    {
+        yield return new SimpleVersion<object>(() => new object());
+        yield return new MultithreadedVersion<object>(() => new object());
+    }
+
+    [TestCaseSource(nameof(LazyImplementations))]
+    public void Get_MultipleCalls_ShoulCallSupplierOnlyOnce(ILazy<object> lazy)
+    {
+        int callCount = 0;
+        Func<object> supplier = () =>
+        {
+            callCount++;
+            return new object();
+        };
+        lazy = lazy is SimpleVersion<object> ? new SimpleVersion<object>(supplier) : new MultithreadedVersion<object>(supplier);
+
+        lazy.Get();
+        lazy.Get();
+        lazy.Get();
+
+        var result = lazy.Get();
+
+        Assert.That(callCount, Is.EqualTo(1));
+    }
+
+    [TestCaseSource(nameof(LazyImplementations))]
+    public void Get_MultipleCalls_ShoulReturnTheSameObjectReference(ILazy<object> lazy)
+    {
+        lazy = lazy is SimpleVersion<object> ? new SimpleVersion<object>(() => new object()) : new MultithreadedVersion<object>(() => new object());
+
+        var result1 = lazy.Get();
+        var result2 = lazy.Get();
+        Assert.That(result1, Is.SameAs(result2));
+    }
+
+    [TestCaseSource(nameof(LazyImplementations))]
+    public void Get_SupplierReturnsNull_ShouldReturnNull(ILazy<object> lazy)
+    {
+        int callCount = 0;
+        lazy = lazy is SimpleVersion<object> ? new SimpleVersion<object>(() =>
+        {
+            callCount++;
+            return null!;
+        }) : new MultithreadedVersion<object>(() =>
+        {
+            callCount++;
+            return null!;
+        });
+
+        var result1 = lazy.Get();
+        var result2 = lazy.Get();
+
+        Assert.That(callCount, Is.EqualTo(1));
+        Assert.That(result1, Is.Null);
+        Assert.That(result2, Is.Null);
+    }
+
+    [TestCaseSource(nameof(LazyImplementations))]
+    public void Constructor_SupplierIsNull_ShouldThrowArgumentNullException(ILazy<object> lazy)
+    {
+        Assert.Throws<ArgumentNullException>(() => new SimpleVersion<object>(null!));
+        Assert.Throws<ArgumentNullException>(() => new MultithreadedVersion<object>(null!));
+    }
+}

LazyInterface/LazyInterface.Tests/LazyInterface.Tests.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="NUnit" Version="4.2.2" />
+    <PackageReference Include="NUnit.Analyzers" Version="4.4.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+	<ItemGroup>
+		<None Remove="stylecop.json" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<AdditionalFiles Include="stylecop.json" />
+	</ItemGroup>
+
+	<ItemGroup>
+    <ProjectReference Include="..\LazyInterface\LazyInterface.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="NUnit.Framework" />
+  </ItemGroup>
+
+</Project>

LazyInterface/LazyInterface.Tests/MultithreadedTests.cs

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+// <copyright file="MultithreadedTests.cs" company="Kalinin Andrew">
+// Copyright (c) Kalinin Andrew. All rights reserved.
+// </copyright>
+
+namespace LazyInterface.Tests;
+
+public class MultithreadedTests
+{
+    [Test]
+    public void Get_AvailabilityOfRaces_SupplierShouldInitializeOnlyOnce()
+    {
+        int callCount = 0;
+        var lazy = new MultithreadedVersion<object>(() =>
+        {
+            Interlocked.Increment(ref callCount);
+            Thread.Sleep(150);
+            return new object();
+        });
+
+        int numOfThreads = 10;
+        var threads = new Thread[numOfThreads];
+        var results = new object?[numOfThreads];
+        var barrier = new Barrier(numOfThreads);
+
+        for (int i = 0; i < numOfThreads; ++i)
+        {
+            int index = i;
+            threads[i] = new Thread(() =>
+            {
+                barrier.SignalAndWait();
+                results[index] = lazy.Get();
+            });
+            threads[i].Start();
+        }
+
+        foreach (var thread in threads)
+        {
+            thread.Join();
+        }
+
+        Assert.That(callCount, Is.EqualTo(1));
+        var firstResult = results[0];
+        Assert.That(results.All(res => ReferenceEquals(res, firstResult)), Is.True);
+    }
+}

LazyInterface/LazyInterface.Tests/stylecop.json

@@ -0,0 +1,9 @@
+{
+  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
+  "settings": {
+    "documentationRules": {
+      "companyName": "Kalinin Andrew",
+      "copyrightText": "Copyright (c) {companyName}. All rights reserved."
+    }
+  }
+}

LazyInterface/LazyInterface.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.13.35806.99
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LazyInterface", "LazyInterface\LazyInterface.csproj", "{492B0043-2F2B-4D4B-9032-8C3EC5A941C5}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LazyInterface.Tests", "LazyInterface.Tests\LazyInterface.Tests.csproj", "{38FDFD18-1B23-483D-A68C-9938CF478AD4}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{492B0043-2F2B-4D4B-9032-8C3EC5A941C5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{492B0043-2F2B-4D4B-9032-8C3EC5A941C5}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{492B0043-2F2B-4D4B-9032-8C3EC5A941C5}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{492B0043-2F2B-4D4B-9032-8C3EC5A941C5}.Release|Any CPU.Build.0 = Release|Any CPU
+		{38FDFD18-1B23-483D-A68C-9938CF478AD4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{38FDFD18-1B23-483D-A68C-9938CF478AD4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{38FDFD18-1B23-483D-A68C-9938CF478AD4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{38FDFD18-1B23-483D-A68C-9938CF478AD4}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {ADEC834D-6E46-477C-871F-21879B4BA23D}
+	EndGlobalSection
+EndGlobal

LazyInterface/LazyInterface/ILazy.cs

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+// <copyright file="ILazy.cs" company="Kalinin Andrew">
+// Copyright (c) Kalinin Andrew. All rights reserved.
+// </copyright>
+
+namespace LazyInterface;
+
+/// <summary>
+/// Interface for lazy value calculation.
+/// </summary>
+/// <typeparam name="T">Type of calculated value.</typeparam>
+public interface ILazy<T>
+{
+    /// <summary>
+    /// Gets the calculated value. Performs the calculation on the first call,
+    /// returns the previously calculated value on subsequent attempts.
+    /// </summary>
+    /// <returns>Calculated value of type T.</returns>
+    T? Get();
+}

LazyInterface/LazyInterface/LazyInterface.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+	<ItemGroup>
+		<None Remove="stylecop.json" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<AdditionalFiles Include="stylecop.json" />
+	</ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+</Project>