ensure.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Runtime.CompilerServices;
using System.Text;

namespace benchmark
{
    class Program
    {
        static void Main(string[] args)
        {
            var summary = BenchmarkRunner.Run(typeof(Program).Assembly);
        }
    }

    public class ToStringFix
    {
        [Benchmark]
        public new void ToString()
        {
            R1 r1 = new R1()
            {
                Name = "blah"
            };
            r1.R2 = new R2();
            r1.R2.R1 = r1;
            r1.ToString();
        }

        [Benchmark]
        public void ToStringWithEnsure()
        {
            R1E r1 = new R1E()
            {
                Name = "blah"
            };
            r1.R2 = new R2E();
            r1.R2.R1 = r1;
            r1.ToString();
        }
    }

    public class R1
    {
        public int Limit;
        public string Name { get; set; }
        public R2 R2 { get; set; }

        public override string ToString()
        {
            if (Limit++ == 500)
            {
                return "";
            }

            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.Append("R1");
            stringBuilder.Append(" { ");
            if (PrintMembers(stringBuilder))
            {
                stringBuilder.Append(" ");
            }
            stringBuilder.Append("}");
            return stringBuilder.ToString();
        }

        protected virtual bool PrintMembers(StringBuilder builder)
        {
            builder.Append("name");
            builder.Append(" = ");
            builder.Append((object)Name);
            builder.Append(", ");
            builder.Append("R2");
            builder.Append(" = ");
            builder.Append(R2);
            return true;
        }
    }

    public class R2
    {
        public R1 R1 { get; set; }

        public override string ToString()
        {
            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.Append("R2");
            stringBuilder.Append(" { ");
            if (PrintMembers(stringBuilder))
            {
                stringBuilder.Append(" ");
            }
            stringBuilder.Append("}");
            return stringBuilder.ToString();
        }

        protected virtual bool PrintMembers(StringBuilder builder)
        {
            builder.Append("r1");
            builder.Append(" = ");
            builder.Append(R1);
            return true;
        }
    }

    public class R1E
    {
        public int Limit;
        public string Name { get; set; }
        public R2E R2 { get; set; }

        public override string ToString()
        {
            if (Limit++ == 500)
            {
                return "";
            }

            try
            {
                RuntimeHelpers.EnsureSufficientExecutionStack();

                StringBuilder stringBuilder = new StringBuilder();
                stringBuilder.Append("R1");
                stringBuilder.Append(" { ");
                if (PrintMembers(stringBuilder))
                {
                    stringBuilder.Append(" ");
                }
                stringBuilder.Append("}");
                return stringBuilder.ToString();
            }
            catch
            {
                return "";
            }
        }

        protected virtual bool PrintMembers(StringBuilder builder)
        {
            builder.Append("name");
            builder.Append(" = ");
            builder.Append((object)Name);
            builder.Append(", ");
            builder.Append("R2");
            builder.Append(" = ");
            builder.Append(R2);
            return true;
        }
    }

    public class R2E
    {
        public R1E R1 { get; set; }

        public override string ToString()
        {
            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.Append("R2");
            stringBuilder.Append(" { ");
            if (PrintMembers(stringBuilder))
            {
                stringBuilder.Append(" ");
            }
            stringBuilder.Append("}");
            return stringBuilder.ToString();
        }

        protected virtual bool PrintMembers(StringBuilder builder)
        {
            builder.Append("r1");
            builder.Append(" = ");
            builder.Append(R1);
            return true;
        }
    }
}