stop/dispose/cancel 一个任务 C#

Question

我正在尝试通过从 google drive/ dropbox/ ftp 等各种存储库导入 DLL 来在 windows 服务中部署 DLL...

但是在实例化任何新的 DLL 之前，我希望关闭之前的运行ning 实例。

我正在使用任务和反思。

我不知道如何取消在运行时间实例化 DLL 的任务（因为实例化的 dll 很长运行 ning 应用程序示例文件观察器.. )

    CancellationTokenSource cts = new CancellationTokenSource();
    CancellationToken ct = cts.Token;

            // instantiate the dll though reflection
        t = Task.Factory.StartNew(() =>
        {
            try
            {
                Assembly assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName);
                Type type = assembly.GetType("myclass.Program");

                MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic |
                          BindingFlags.Static | BindingFlags.Instance);
                minfo.Invoke(Activator.CreateInstance(type), null);

            }
            catch (Exception ex)
            {

                log.Error(ex.ToString());
            }
        }, cts.Token);

问题：我想在我的应用程序检测到新的 dll 并尝试通过此任务代码执行它之前取消任务 t。

编辑我删除了取消令牌代码，因为它正在中断。这是带有取消标记的实际代码。

    CancellationTokenSource cts = new CancellationTokenSource();
    CancellationToken ct = cts.Token;

if (t != null)
        {
            cts.Cancel();
            try
            {
                ct.ThrowIfCancellationRequested();
            }
            catch (Exception ex)
            {

                cts.Dispose();
                t.Dispose();
            }

        }

                // instantiate the dll though reflection
        t = Task.Factory.StartNew(() =>
        {
            try
            {
                Assembly assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName);
                Type type = assembly.GetType("myclass.Program");

                MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic |
                          BindingFlags.Static | BindingFlags.Instance);
                minfo.Invoke(Activator.CreateInstance(type), null);

            }
            catch (Exception ex)
            {

                log.Error(ex.ToString());
            }
        }, cts.Token);

我的想法是，如果我能以某种方式取消并处置持有实例化上下文的任务，程序集将被释放，然后我将能够更新程序集并再次通过任务重新实例化它。

我知道我哪里出错了，请解释。

编辑

我对assemblyDomain.DoCallBack（代表）寄予厚望。但我收到一个错误。这是抛出错误的代码的简化版本。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;
using System.Reflection;


namespace AppDomain
{
    [Serializable]
    class Program
    {
        static System.AppDomain assemblyDomain = null;

        static void Main(string[] args)
        {

            var inp = "go";

            while (inp.ToString().ToLower().Trim() != "stop")
            {
                start();
                inp = Console.ReadLine();
            }

        }

        private static void start()
        {


            //Check if appdomain and assembly is already loaded
            if (assemblyDomain != null)
            {
                //unload appDomain and hence the assembly
                System.AppDomain.Unload(assemblyDomain);

                //Code to download new dll
            }

            string cwd = System.AppDomain.CurrentDomain.BaseDirectory;

            string sourceFileName = @"C:\Users\guest\Documents\visual studio 2010\Projects\DotNetTraining\Lecture 1 - dotNetProgramExecution\bin\Debug\Lecture 1 - dotNetProgramExecution.exe";

            string dllName = "Lecture 1 - dotNetProgramExecution.exe";

            // copy the file
            if (File.Exists(cwd + dllName))
            {
                File.Delete(cwd + dllName);
            }

            File.Copy(sourceFileName, cwd + dllName);

            assemblyDomain = System.AppDomain.CreateDomain("assembly1Domain", null);
            assemblyDomain.DoCallBack(() =>
               {
                   var t = Task.Factory.StartNew(() =>
                   {
                       try
                       {

                           string sss = "";
                           Assembly assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName);
                           Type type = assembly.GetType("Lecture_1___dotNetProgramExecution.Program");

                           MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic |
                                     BindingFlags.Static | BindingFlags.Instance);
                           minfo.Invoke(Activator.CreateInstance(type), null);



                           //        //var pathToDll = @"assembly path";
                           //        //var dllName = "assembly name";
                           //        var assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName);
                           //        var targetAssembly = assembly.CreateInstance("Lecture_1___dotNetProgramExecution.Program");
                           //        Type type = targetAssembly.GetType();
                           //        MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance);
                           //        minfo.Invoke(targetAssembly, null);

                       }
                       catch (Exception ex)
                       {

                           Console.WriteLine(ex.ToString());
                       }
                   });
               });
        }
    }
}

错误：
程序集 'AppDomain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' 中的类型 'AppDomain.Program+<>c__DisplayClass2' 未标记为可序列化。

堆栈跟踪：

at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at AppDomain.Program.start() in c:\users\guest\documents\visual studio 2010\Projects\DotNetTraining\AppDomain\Program.cs:line 58
   at AppDomain.Program.Main(String[] args) in c:\users\guest\documents\visual studio 2010\Projects\DotNetTraining\AppDomain\Program.cs:line 24
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

请注意：我已将导入的程序集中的 class 程序标记为可序列化

namespace Lecture_1___dotNetProgramExecution
{
    [Serializable]
    class Program
    {
        static void Main()
        {

更新：

动态拉取程序集代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Threading;

namespace Lecture_1___dotNetProgramExecution
{
    [Serializable]
    class Program
    {
        static void Main()
        {
            try
            {

                Task.Factory.StartNew(() =>
                {

                    while (true)
                    {
                        StringBuilder sb = new StringBuilder();
                        sb.Append("log something new yippe ");
                        // flush every 20 seconds as you do it
                        File.AppendAllText(@"C:\logs.txt", sb.ToString());
                        sb.Clear();
                        Thread.Sleep(3000);
                    }

                });



                FileSystemWatcher fsw = new FileSystemWatcher();

                fsw.Path = @"c:\watched";
                //fsw.filter = ".dll";
                fsw.Created += new FileSystemEventHandler(fsw_Created);
                fsw.BeginInit();
                //throw new FileNotFoundException();
                Console.ReadLine();

            }
            catch (Exception ex)
            {

                Task.Factory.StartNew(() =>
                {

                    while (true)
                    {
                        StringBuilder sb = new StringBuilder();
                        sb.Append("loggind froom exception log something");
                        // flush every 20 seconds as you do it
                        File.AppendAllText(@"C:\logs.txt", sb.ToString());
                        sb.Clear();
                        Thread.Sleep(1000);
                    }

                });
                Console.ReadLine();
            }
        }

        static void fsw_Created(object sender, FileSystemEventArgs e)
        {
            throw new NotImplementedException();
        }


    }
}

Answer 1

从你的问题来看，如果有可用的升级，你似乎想卸载动态加载的程序集，然后重新加载最新的程序集。在这种情况下取消将无济于事。事实上，我没有看到您在任何地方使用取消令牌。

卸载动态加载程序集的唯一方法是先在单独的应用程序域中加载程序集，然后在不再需要程序集时卸载应用程序域本身。所以你应该这样做：

创建一个新的应用域。保留应用程序域的引用，稍后您将需要它来卸载域和程序集。
在新创建的应用程序域中加载程序集。
根据需要从新加载的程序集中创建类型实例并执行其方法。
当有新版本的dll 可用时，卸载之前创建的应用程序域。这也会自动卸载程序集。
下载新程序集并重新从第 1 步开始。

请参阅此内容了解如何 load/unload 应用域和程序集：Using AppDomain in C# to dynamically load and unload dll

编辑：下面是带有AppDomain.DoCallback

的代码片段

using System;
using System.IO;
using System.Reflection;
using System.Threading.Tasks;


namespace AppDomain
{
[Serializable]
class Program
{
    static System.AppDomain assemblyDomain = null;

    static void Main(string[] args)
    {

        var inp = "go";

        while (inp.ToString().ToLower().Trim() != "stop")
        {
            start();
            inp = Console.ReadLine();
        }

    }

    private static void start()
    {


        //Check if appdomain and assembly is already loaded
        if (assemblyDomain != null)
        {
            //unload appDomain and hence the assembly
            System.AppDomain.Unload(assemblyDomain);

            //Code to download new dll
        }

        string cwd = System.AppDomain.CurrentDomain.BaseDirectory;

        string sourceFileName = @"C:\Users\deepak\Documents\visual studio 2010\Projects\ConsoleApplication1\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe";


        string dllName = "ConsoleApplication2.exe";

        // copy the file
        if (File.Exists(cwd + dllName))
        {
            File.Delete(cwd + dllName);
        }

        File.Copy(sourceFileName, cwd + dllName);

        assemblyDomain = System.AppDomain.CreateDomain("assembly1Domain", null);
        assemblyDomain.DoCallBack(() =>
        {
            var t = Task.Factory.StartNew(() =>
            {
                try
                {

                    string sss = "";
                    string dllName1 = "ConsoleApplication2.exe";
                    Assembly assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName1);
                    Type type = assembly.GetType("Lecture_1___dotNetProgramExecution.Program");

                    MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic |
                              BindingFlags.Static | BindingFlags.Instance);
                    minfo.Invoke(Activator.CreateInstance(type), null);
                }
                catch (Exception ex)
                {

                    Console.WriteLine(ex.ToString());
                }
            });
        });
    }
}
}


using System;
using System.Text;
using System.Threading;

namespace Lecture_1___dotNetProgramExecution
{
[Serializable]
class Program
{
    static void Main()
    {
        while (true)
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("log something new yippe ");
            // flush every 20 seconds as you do it
            //File.AppendAllText(@"C:\logs.txt", sb.ToString());
            Console.WriteLine(sb.ToString());
            sb.Clear();
            Thread.Sleep(3000);
        }
    }
}
}

stop/dispose/cancel 一个任务 C#

stop/dispose/cancel a Task C#

.net

c#

task

task-parallel-library

cancellationtokensource