Added Linq2DB benchmarks (#1125)

Added Linq2DB benchmarks

Dapper.Tests.Performance/Benchmarks.Linq2DB.cs

+using BenchmarkDotNet.Attributes;
+
+using System;
+using System.Linq;
+using Dapper.Tests.Performance.Linq2Db;
+using LinqToDB;
+using LinqToDB.Data;
+
+namespace Dapper.Tests.Performance
+{
+    public class Liq2DbBenchmarks : BenchmarkBase
+    {
+        private Linq2DBContext _dbContext;
+        
+        private static Func<Linq2DBContext, int, Post> compiledQuery = CompiledQuery.Compile((Linq2DBContext db, int id) =>
+            db.Posts.First(c => c.Id == id));
+        [GlobalSetup]
+        public void Setup()
+        {
+            BaseSetup();
+            DataConnection.DefaultSettings = new Linq2DBSettings(_connection.ConnectionString);
+            _dbContext = new Linq2DBContext();
+        }
+
+        [Benchmark(Description = "Normal")]
+        public Post Normal()
+        {
+            Step();
+            return _dbContext.Posts.First(p => p.Id == i);
+        }
+
+        [Benchmark(Description = "Compiled")]
+        public Post Compiled()
+        {
+            Step();
+            return compiledQuery(_dbContext, i);
+        }
+
+        [Benchmark(Description = "SqlQuery")]
+        public Post SqlQuery()
+        {
+            Step();
+            return _dbContext.Query<Post>("select * from Posts where Id = @id", new { id = i }).First();
+        }
+    }
+}

Dapper.Tests.Performance/Dapper.Tests.Performance.csproj

@@ -16,6 +16,7 @@
     <!--<PackageReference Include="BLToolkit" Version="4.3.6" />-->
     <PackageReference Include="EntityFramework" Version="6.2.0" />
     <PackageReference Include="FirebirdSql.Data.FirebirdClient" Version="6.3.0" />
+    <PackageReference Include="linq2db.SqlServer" Version="2.3.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.2" />
     <PackageReference Include="Microsoft.SqlServer.Types" Version="14.0.314.76" />
     <PackageReference Include="MySqlConnector" Version="0.44.1" />
@@ -40,7 +41,7 @@
   <ItemGroup>
     <None Update="NHibernate\*.xml" CopyToOutputDirectory="Always" />
     <Compile Update="Benchmarks.*.cs" DependentUpon="Benchmarks.cs" />
-  </ItemGroup>
+  </ItemGroup>  
   <ItemGroup>
     <PackageReference Update="SourceLink.Create.GitHub" Version="2.8.3" />
   </ItemGroup>

Dapper.Tests.Performance/Linq2DB/ConnectionStringSettings.cs

+using LinqToDB.Configuration;
+
+namespace Dapper.Tests.Performance.Linq2Db
+{
+    public class ConnectionStringSettings : IConnectionStringSettings
+    {
+        public string ConnectionString { get; set; }
+        public string Name { get; set; }
+        public string ProviderName { get; set; }
+        public bool IsGlobal => false;
+    }
+}
\ No newline at end of file

Dapper.Tests.Performance/Linq2DB/Linq2DBContext.cs

+using LinqToDB;
+using Microsoft.EntityFrameworkCore;
+
+namespace Dapper.Tests.Performance.Linq2Db
+{
+    public class Linq2DBContext : LinqToDB.Data.DataConnection
+    {
+        public ITable<Post> Posts => GetTable<Post>();
+    }
+}

Dapper.Tests.Performance/Linq2DB/Linq2DbSettings.cs

+using System.Collections.Generic;
+using System.Linq;
+using LinqToDB.Configuration;
+
+namespace Dapper.Tests.Performance.Linq2Db
+{
+    public class Linq2DBSettings : ILinqToDBSettings
+    {
+        private readonly string _connectionString;
+        public IEnumerable<IDataProviderSettings> DataProviders => Enumerable.Empty<IDataProviderSettings>();
+
+        public string DefaultConfiguration => "SqlServer";
+        public string DefaultDataProvider => "SqlServer";
+
+        public Linq2DBSettings(string connectionString)
+        {
+            _connectionString = connectionString;
+        }
+
+        public IEnumerable<IConnectionStringSettings> ConnectionStrings
+        {
+            get
+            {
+                yield return
+                    new ConnectionStringSettings
+                    {
+                        Name = "SqlServer",
+                        ProviderName = "SqlServer",
+                        ConnectionString = _connectionString
+                    };
+            }
+        }
+    }
+}

Dapper.Tests.Performance/Post.cs

@@ -5,9 +5,11 @@ namespace Dapper.Tests.Performance
 {
     [ServiceStack.DataAnnotations.Alias("Posts")]
     [Table(Name = "Posts")]
+    [LinqToDB.Mapping.Table(Name = "Posts")]
     public class Post
     {
         [Id(IdKind.Identity)]
+        [LinqToDB.Mapping.PrimaryKey, LinqToDB.Mapping.Identity]
         public int Id { get; set; }
         public string Text { get; set; }
         public DateTime CreationDate { get; set; }