协议缓冲区是否支持使用共享引用对象图的序列化？

Question

请观察以下简单程序(基于protobuf-net项目v1 wiki的示例):

using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using ProtoBuf;

namespace HelloProtoBuf
{
  [ProtoContract]
  class Person
  {
    [ProtoMember(1)]
    public int Id { get; set; }
    [ProtoMember(2)]
    public string Name { get; set; }
    [ProtoMember(3)]
    public Address Address { get; set; }
  }
  [ProtoContract]
  class Address
  {
    [ProtoMember(1)]
    public string Line1 { get; set; }
    [ProtoMember(2)]
    public string Line2 { get; set; }
  }


  class Program
  {
    static void Main(string[] args)
    {
      var person = new Person
      {
        Id = 12345,
        Name = "Fred",
        Address = new Address
        {
          Line1 = "Flat 1",
          Line2 = "The Meadows"
        }
      };
      var person2 = new Person
      {
        Id = 4553,
        Name = "Nadya",
        Address = person.Address
      };
      var persons = new List<Person> { person, person2 };
      Debug.Assert(ReferenceEquals(persons[0].Address, persons[1].Address));

      using (var file = File.Create("persons.bin"))
      {
        Serializer.Serialize(file, persons);
      }
      List<Person> persons2;
      using (var file = File.OpenRead("persons.bin"))
      {
        persons2 = Serializer.Deserialize<List<Person>>(file);
      }
      Debug.Assert(ReferenceEquals(persons2[0].Address, persons2[1].Address));
    }
  }
}

第二个断言失败了.这是protobuf-net实现中的错误还是协议缓冲区根本不支持具有共享引用的对象图？

谢谢.

Answer 1

协议缓冲区本身不支持这个 - 所以不,它不是一个bug.实际上,*XmlSerializer和DataContractSerializer*会做同样的事情(可能会JavaScriptSerializer和JSON.NET一样).

但是,这是一个常见的请求,所以这在protobuf-net v2中得到支持(基本上:我作弊).只需将其更改为:

    [ProtoMember(3, AsReference=true)]
    public Address Address { get; set; }

(并使用我在大约5分钟内上传的v2 dll,或者从代码构建)

*=警告:DataContractSerializer 不支持引用,但只有当你使用特定的构造函数; 它默认是禁用的