主机托管代码和垃圾回收 [英] Hosting managed code and garbage collection
问题描述
我有一个C ++托管了大量的C＃代码来支持由C ++ COM对象公开的API外的进程COM服务器。
I have a C++ out-of-process COM server that hosts a lot of C# code to support the API exposed by the C++ COM objects.
由于各种原因，我正在考虑消除我的解决方案的C ++部分。但是，因为我的控制范围之外的限制我的有无的保留进程外的COM服务器。微软确实有这里此的一个典型的例子。
For a variety of reasons, I am considering eliminating the C++ portion of my solution. However, because of constraints outside of my control I have to retain the out-of-process COM server. Microsoft does have a canonical example of this here.
在这个例子中寻找有件事我不明白。消息循环开始之前，创建一个定时器来调用GC.Collect每5秒。这是我能找到的唯一一提表示它保证了COM对象在合理的时间内释放。我有点困惑这个...没有我的C ++托管当前自动调用GC.Collect？我当然不这样做。其实我作为C ++代码COM对象的创建管理对象（有标记有ComVisible特性（真）。这是否意味着我应该叫GC.Collect的每5秒了吗？如果没有，为什么我需要调用它在这个新的C＃进程外的服务器。那是弥补了自动的过程，清理在一个正常的C ++应用程序？未引用的COM对象（我假设消息循环过程中的某个时候发生的事情。）
Looking at this example there is something I don't understand. Before the message loop starts, a timer is created to call GC.Collect every 5 seconds. The only mention of this that I can find indicates it's to ensure the COM objects are released in a reasonable timeframe. I'm a little confused about this...does my C++ host currently call GC.Collect automatically? I'm certainly not doing it. And yet I am creating managed objects (with COMVisible(true) as COM objects in the C++ code. Does that mean I should be calling GC.Collect every 5 seconds now? If not, why do I need to call it in this new C# out of process server. Is that to make up for the automatic process that cleans up unreferenced COM objects in a normal C++ application? (Which I assume is happening sometime during the message loop.)
所以GC.Collect调用每5秒钟好像它可能是一个坏主意。我错了而烦恼？是否存在被，我可以达到同样的效果其他方法？
Calling GC.Collect every 5 seconds seems like it could be a bad idea. Am I wrong to worry? Is there some other method by which I could achieve the same results?
我使用.NET 4.5和Visual Studio 2012。
I am using .NET 4.5 and Visual Studio 2012.
推荐答案
IMO，最简单的方法来创建一个COM外的进程内在C＃服务器是使用 DLL替代进程。
IMO, the easiest way to create a COM out-of-proc server in C# is to use a DLL surrogate process.
您还在局限于双接口（ ComInterfaceType.InterfaceIsDual ），然后你需要注册生成的类型库（并做到这一点作为部署的一部分，太）：
You're still limited to dual interfaces (ComInterfaceType.InterfaceIsDual), and you'd need to register the generated type library (and do it as part of deployment, too):
ç ：\Windows\Microsoft.NET\Framework\v4.0.30319\RegAsm.exe ManagedServer.dll /代码库/ TLB
这将允许您利用COM类型库编组，因为你没有为你的C＃的COM对象专用的COM代理/ STUF DLL。
This will allow you to utilize the COM type library marshaller, because you don't have a dedicated COM proxy/stuf DLL for your C# COM objects.
请务必使用正确的 RegAsm.exe 二进制文件，这取决于你的 ManagedServer.dll 装配的目标位岬。以上假设x86代码。
Make sure to use the correct RegAsm.exe binary, depending on the target bit-ness of your ManagedServer.dll assembly. The above assumes x86 code.
下面是一个完整的工作模板的例子。它采用代理注册护理：
Here is a complete working template example. It takes care of the surrogate registration:
using Microsoft.Win32;
using System;
using System.Runtime.InteropServices;
namespace ManagedServer
{
[ComVisible(true), Guid("1891CF89-1282-4CA8-B7C5-F2608AF1E2F1")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface IManagedComObject
{
string ComMethod(string data);
}
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
[ComDefaultInterface(typeof(IManagedComObject))]
[Guid("989162CD-A6A6-4A7D-A7FB-C94086A4E90A")]
[ProgId("Noseratio.ManagedComObject")]
public class ManagedComObject : IManagedComObject
{
// public constructor
public ManagedComObject()
{
}
// IManagedComObject
public string ComMethod(string data)
{
return data;
}
// registration
[ComRegisterFunction()]
public static void Register(Type type)
{
var guid = type.GUID.ToString("B");
using (var appIdKey = Registry.ClassesRoot.CreateSubKey(@"AppID\" + guid))
{
appIdKey.SetValue("DllSurrogate", String.Empty);
}
using (var appIdKey = Registry.ClassesRoot.CreateSubKey(@"CLSID\" + guid))
{
appIdKey.SetValue("AppId", guid);
}
}
[ComUnregisterFunction()]
public static void Unregister(Type type)
{
var guid = type.GUID.ToString("B");
using (var appIdKey = Registry.ClassesRoot.OpenSubKey(@"AppID\" + guid, writable: true))
{
if (appIdKey != null)
appIdKey.DeleteValue("DllSurrogate", throwOnMissingValue: false);
}
Registry.ClassesRoot.DeleteSubKeyTree(@"CLSID\" + guid, throwOnMissingSubKey: false);
}
}
}
默认情况下，对象将在MTA的公寓中创建的，所以接口方法有可能在任何线程调用，你需要实现线程安全。
By default, the objects will be created in MTA apartment, so the interface methods may possibly be called on any thread, you'd need to implement thread safety.
如果你需要为你的对象的替代进程内消息泵STA线程，你可以做到这一点明确实施工厂单，并使用 CoMarshalInterThreadInterfaceInStream对该 / CoGetInterfaceAndReleaseStream对导出STA线程之外的对象（的这个可能是相关的）。
If you need an STA thread with message pump inside the surrogate process for your objects, you could do that explicitly by implementing a factory singleton and using CoMarshalInterThreadInterfaceInStream/CoGetInterfaceAndReleaseStream to export objects outside the STA thread (this might be related).
还有一点，你的COM客户端代码应该使用 CLSCTX_LOCAL_SERVER 时创建 ManagedComObject 这样的一个实例。这是不是与 Activator.CreateInstance的情况下（Type.GetTypeFromProgID（Noseratio.ManagedComObject）），这显然使用了 CLSCTX_ALL 。这可以很容易地照顾：
Another point, your COM client code should use CLSCTX_LOCAL_SERVER when creating this an instance of ManagedComObject. This is not the case with Activator.CreateInstance(Type.GetTypeFromProgID("Noseratio.ManagedComObject")), which apparently uses CLSCTX_ALL. This can be easily taken care of:
using System;
using System.Runtime.InteropServices;
namespace Client
{
class Program
{
static void Main(string[] args)
{
// dynamic obj = Activator.CreateInstance(Type.GetTypeFromProgID("Noseratio.ManagedComObject"));
dynamic obj = ComExt.CreateInstance(
Type.GetTypeFromProgID("Noseratio.ManagedComObject").GUID,
localServer: true);
Console.WriteLine(obj.ComMethod("hello"));
}
}
// COM interop
public static class ComExt
{
const uint CLSCTX_LOCAL_SERVER = 0x4;
const uint CLSCTX_INPROC_SERVER = 0x1;
static readonly Guid IID_IUnknown = new Guid("00000000-0000-0000-C000-000000000046");
[DllImport("ole32.dll", ExactSpelling = true, PreserveSig = false)]
static extern void CoCreateInstance(
[MarshalAs(UnmanagedType.LPStruct)] Guid rclsid,
[MarshalAs(UnmanagedType.IUnknown)] object pUnkOuter,
uint dwClsContext,
[MarshalAs(UnmanagedType.LPStruct)] Guid riid,
[MarshalAs(UnmanagedType.Interface)] out object rReturnedComObject);
public static object CreateInstance(Guid clsid, bool localServer)
{
object unk;
CoCreateInstance(clsid, null, localServer ? CLSCTX_LOCAL_SERVER : CLSCTX_INPROC_SERVER, IID_IUnknown, out unk);
return unk;
}
}
}
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