Cross-AppDomain Singleton with Remoting - 启动性能差

Question

我有一个用于 MS Excel 的插件，它需要一个单例来在模块之间共享数据。 根据 Excel 的版本（2003、2007、2010）以及 Excel 的启动方式，它会从不同的、不可预测的 AppDomain 调用我的插件，这会阻止经典的单例方法。

创建自定义 AppDomainManager 不起作用，因为 Excel 在调用插件之前已经创建了 AppDomain。

链接到 mscoree 以枚举域会破坏插件注册过程（我真的不希望这样）；似乎没有任何其他枚举方式，所以这也不是一种选择。

我发现的唯一解决方案是使用远程处理。这是我的测试台：

Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
' Remeber to add reference to System.Runtime.Remoting DLL !

Public Class CrossAppDomainSingleton(Of T As {New})
    Inherits MarshalByRefObject

    Private Const _portnumber As Integer = 9999 ' adjust to suit taste
    Private Shared _instance As T = Nothing
    Private Shared _lock As Object = New Object
    Private Shared _id As Guid = Nothing
    Private Shared _myapp As String = System.Reflection.Assembly.GetExecutingAssembly().GetName.Name
    Private Shared _myname As String = GetType(T).ToString
    Private Shared _myfullname As String = _myapp & "/" & _myname

    Protected Sub New()
        _id = Guid.NewGuid
        Console.WriteLine("New " & ID & " in " & AppDomain.CurrentDomain.FriendlyName)
    End Sub
    Public Function GetInstance() As T
        If _instance Is Nothing Then
            Console.WriteLine("GetInstance in " & AppDomain.CurrentDomain.FriendlyName)
            _instance = New T
        End If
        Return _instance
    End Function
    Public ReadOnly Property ID As String
        Get
            Return _id.ToString
        End Get
    End Property
    Public Overrides Function InitializeLifetimeService() As Object
        Console.WriteLine("InitializeLifetimeService=infinite")
        Return Nothing
    End Function
    Public Shared Function Instance() As T

        Dim currentdomain As AppDomain
        Dim uri As String
        Dim registered As Boolean = False
        Dim remotet As Object
        Dim tcpchannel As Tcp.TcpChannel
        Dim tcpprops As System.Collections.IDictionary
        Dim sw As Stopwatch = New Stopwatch

        Try
            sw.Start()
            SyncLock _lock
                Console.WriteLine("Instance in " & AppDomain.CurrentDomain.FriendlyName)
                If _instance Is Nothing Then
                    currentdomain = AppDomain.CurrentDomain
                    _instance = currentdomain.GetData(_myfullname)

                    If _instance Is Nothing Then

                        ' Build connection string "tcp://localhost:[_portnumber]/[myapp]/[myname]".
                        uri = String.Format("tcp://localhost:{0}/{1}/{2}",
                                            _portnumber.ToString,
                                            _myapp,
                                            _myname)
                        registered = False
                        Try
                            remotet = RemotingServices.Connect(GetType(T), uri)
                            _instance = remotet.GetInstance()
                            currentdomain.SetData(_myfullname, _instance)
                            registered = True
                        Catch ex As Exception
                        End Try

                        If registered Then
                            Console.WriteLine("... instanced with remoting")
                        Else
                            Try
                                Dim ichannel As IChannel = ChannelServices.GetChannel(_myfullname)
                                ChannelServices.UnregisterChannel(ichannel)
                            Catch ex As Exception
                            End Try
                            tcpprops = New System.Collections.Hashtable
                            tcpprops("port") = _portnumber.ToString
                            tcpprops("name") = _myfullname
                            tcpchannel = New Tcp.TcpChannel(tcpprops, Nothing, Nothing)
                            ChannelServices.RegisterChannel(tcpchannel, False)
                            RemotingConfiguration.ApplicationName = _myapp
                            RemotingConfiguration.RegisterWellKnownServiceType(GetType(T),
                                                                               _myname,
                                                                               WellKnownObjectMode.Singleton)
                            remotet = RemotingServices.Connect(GetType(T), uri)
                            _instance = remotet.GetInstance()
                            Console.WriteLine("... singleton instance created")
                        End If
                    Else
                        Console.WriteLine("... instanced from AppDomain")
                    End If
                Else
                    Console.WriteLine("... instanced statically")
                End If
            End SyncLock
        Catch ex As Exception
            Console.WriteLine(String.Format("Error in {0}.Instance: {1}", _myname, ex.Message))
        End Try

        Console.WriteLine("instance time=" & CLng(1000000 * sw.ElapsedTicks / Stopwatch.Frequency) & " µS")
        sw.Stop()

        Return _instance

    End Function

End Class

（请忽略款式等，只是一个样机）。

我用它来锻炼它：

Module Main
    Public Class Common
        Inherits CrossAppDomainSingleton(Of Common)
        ' real application data goes here
    End Class
    Sub Main()
        Dim common As Common
        common = common.Instance
        Dim defaultdomain As AppDomain = AppDomain.CurrentDomain
        defaultdomain.DoCallBack(AddressOf ShowSingleton)

        Dim domain1 As AppDomain = AppDomain.CreateDomain("One")
        domain1.DoCallBack(AddressOf ShowSingleton)

        Dim domain2 As AppDomain = AppDomain.CreateDomain("Two")
        domain2.DoCallBack(AddressOf ShowSingleton)

        defaultdomain.DoCallBack(AddressOf ShowSingleton)
        domain1.DoCallBack(AddressOf ShowSingleton)
        domain2.DoCallBack(AddressOf ShowSingleton)

        Dim junk As Object = Console.ReadKey
    End Sub
    Private Sub ShowSingleton()
        Console.WriteLine("ShowSingleton in " & AppDomain.CurrentDomain.FriendlyName)
        Dim common As Common = common.Instance
        Console.WriteLine("guid is " & common.ID)
    End Sub
End Module

结果如下：

Instance in CrossAppDomainSingletonDemo.vshost.exe
New 497696b6-71c7-4001-b232-39b379034385 in CrossAppDomainSingletonDemo.vshost.exe
InitializeLifetimeService=infinite
GetInstance in CrossAppDomainSingletonDemo.vshost.exe
New 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4 in CrossAppDomainSingletonDemo.vshost.exe
InitializeLifetimeService=infinite
... singleton instance created
instance time=2593865 µS ' AAAARRRRGGGGHHHHH !!!!!!!!!!!!!!
ShowSingleton in CrossAppDomainSingletonDemo.vshost.exe
Instance in CrossAppDomainSingletonDemo.vshost.exe
... instanced statically
instance time=38 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4
ShowSingleton in One
Instance in One
... instanced with remoting
instance time=440087 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4
ShowSingleton in Two
Instance in Two
... instanced with remoting
instance time=438821 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4
ShowSingleton in CrossAppDomainSingletonDemo.vshost.exe
Instance in CrossAppDomainSingletonDemo.vshost.exe
... instanced statically
instance time=111 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4
ShowSingleton in One
Instance in One
... instanced statically
instance time=106 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4
ShowSingleton in Two
Instance in Two
... instanced statically
instance time=105 µS
guid is 3a3a7a9c-a4f7-46d4-9b16-35fdbfbdc6c4

一旦一切都运行起来，访问单例需要大约 100µS，这是完美的。第一次初始化每个 AppDomain 时，我可以忍受 ~400mS。问题出在启动时，远程调用大约需要 2.5 秒。

任何建议都将受到欢迎，我已经数周试图找到一个体面的解决方案 >;-)

Answer 1

用 IPC 代替 TCP 解决