C# 進程的掛起與恢復

1. 源起：

仍然是模塊化編程所引起的需求。產品經理難伺候，女產品經理更甚之~:p

純屬戲謔，技術方案與產品經理無關，芋頭莫怪！

VCU10項目重構，要求各功能模塊以獨立進程方式實現，好比：音視頻轉換模塊，若以獨立進程方式實現，如何控制其暫停、繼續等功能呢？

線程能夠Suspend、Resume，c#內置的Process沒有此類方法，咋整？

山窮水盡疑無路，柳暗花明又一村。情到濃時清轉薄，此情可待成追憶！

前篇描述了進程間數據傳遞方法，此篇亦以示例演示其間控制與數據交互方法。

 

 

 二、未公開的API函數：NtSuspendProcess、NtResumeProcess

此類函數在MSDN中找不到。

思其緣由，概因它們介於Windows API和 內核API之間，威力不容小覷。怕二八耙子程序員濫用而引起事端，所以密藏。

其實還有個NtTerminateProcess，因Process有Kill方法，所以可不用。

但再隱祕的東西，只要有價值，都會被人給翻出來，好酒不怕巷子深麼！

好，基於其，設計一個進程管理類，實現模塊化編程之進程間控制這個需求。

 

 

三、ProcessMgr

直上代碼吧，封裝一個進程管理單元：

public static class ProcessMgr
    {
        /// <summary>
        /// The process-specific access rights.
        /// </summary>
        [Flags]
        public enum ProcessAccess : uint
        {
            /// <summary>
            /// Required to terminate a process using TerminateProcess.
            /// </summary>
            Terminate = 0x1,

            /// <summary>
            /// Required to create a thread.
            /// </summary>
            CreateThread = 0x2,

            /// <summary>
            /// Undocumented.
            /// </summary>
            SetSessionId = 0x4,

            /// <summary>
            /// Required to perform an operation on the address space of a process (see VirtualProtectEx and WriteProcessMemory).
            /// </summary>
            VmOperation = 0x8,

            /// <summary>
            /// Required to read memory in a process using ReadProcessMemory.
            /// </summary>
            VmRead = 0x10,

            /// <summary>
            /// Required to write to memory in a process using WriteProcessMemory.
            /// </summary>
            VmWrite = 0x20,

            /// <summary>
            /// Required to duplicate a handle using DuplicateHandle.
            /// </summary>
            DupHandle = 0x40,

            /// <summary>
            /// Required to create a process.
            /// </summary>
            CreateProcess = 0x80,

            /// <summary>
            /// Required to set memory limits using SetProcessWorkingSetSize.
            /// </summary>
            SetQuota = 0x100,

            /// <summary>
            /// Required to set certain information about a process, such as its priority class (see SetPriorityClass).
            /// </summary>
            SetInformation = 0x200,

            /// <summary>
            /// Required to retrieve certain information about a process, such as its token, exit code, and priority class (see OpenProcessToken, GetExitCodeProcess, GetPriorityClass, and IsProcessInJob).
            /// </summary>
            QueryInformation = 0x400,

            /// <summary>
            /// Undocumented.
            /// </summary>
            SetPort = 0x800,

            /// <summary>
            /// Required to suspend or resume a process.
            /// </summary>
            SuspendResume = 0x800,

            /// <summary>
            /// Required to retrieve certain information about a process (see QueryFullProcessImageName). A handle that has the PROCESS_QUERY_INFORMATION access right is automatically granted PROCESS_QUERY_LIMITED_INFORMATION.
            /// </summary>
            QueryLimitedInformation = 0x1000,

            /// <summary>
            /// Required to wait for the process to terminate using the wait functions.
            /// </summary>
            Synchronize = 0x100000
        }

        [DllImport("ntdll.dll")]
        private static extern uint NtResumeProcess([In] IntPtr processHandle);

        [DllImport("ntdll.dll")]
        private static extern uint NtSuspendProcess([In] IntPtr processHandle);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr OpenProcess(
            ProcessAccess desiredAccess,
            bool inheritHandle,
            int processId);

        [DllImport("kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool CloseHandle([In] IntPtr handle);

        public static void SuspendProcess(int processId)
        {
            IntPtr hProc = IntPtr.Zero;
            try
            {
                // Gets the handle to the Process
                hProc = OpenProcess(ProcessAccess.SuspendResume, false, processId);
                if (hProc != IntPtr.Zero)
                    NtSuspendProcess(hProc);
            }
            finally
            {
                // Don't forget to close handle you created.
                if (hProc != IntPtr.Zero)
                    CloseHandle(hProc);
            }
        }

        public static void ResumeProcess(int processId)
        {
            IntPtr hProc = IntPtr.Zero;
            try
            {
                // Gets the handle to the Process
                hProc = OpenProcess(ProcessAccess.SuspendResume, false, processId);
                if (hProc != IntPtr.Zero)
                    NtResumeProcess(hProc);
            }
            finally
            {
                // Don't forget to close handle you created.
                if (hProc != IntPtr.Zero)
                    CloseHandle(hProc);
            }
        }
    }

四、進程控制

我權且主進程爲宿主，它經過Process類調用子進程，得其ID，以此爲用。其調用代碼爲：

private void RunTestProcess(bool hidden = false)
        {
            string appPath = Path.GetDirectoryName(Application.ExecutablePath);
            string testAppPath = Path.Combine(appPath, "TestApp.exe");
            var pi = new ProcessStartInfo();
            pi.FileName = testAppPath;
            pi.Arguments = this.Handle.ToString();
            pi.WindowStyle = hidden ? ProcessWindowStyle.Hidden : ProcessWindowStyle.Normal;
            this.childProcess = Process.Start(pi);
            txtInfo.Text = string.Format("子進程ID：{0}\r\n子進程名：{1}", childProcess.Id, childProcess.ProcessName);

            ...
        }

控制代碼爲：

private void btnWork_Click(object sender, EventArgs e)
        {
            if (this.childProcess == null || this.childProcess.HasExited)
                return;

            if ((int)btnWork.Tag == 0)
            {
                btnWork.Tag = 1;
                btnWork.Text = "恢復";
                ProcessMgr.SuspendProcess(this.childProcess.Id);
            }
            else
            {
                btnWork.Tag = 0;
                btnWork.Text = "掛起";
                ProcessMgr.ResumeProcess(this.childProcess.Id);
            }
        }

子進程以必定時器模擬其工做，向主進程拋進度消息：

private void timer_Tick(object sender, EventArgs e)
        {
            if (progressBar.Value < progressBar.Maximum)
                progressBar.Value += 1;
            else
                progressBar.Value = 0;
            if (this.hostHandle != IntPtr.Zero)
                SendMessage(this.hostHandle, WM_PROGRESS, 0, progressBar.Value);
        }

五、效果圖：

爲示例，作了兩個圖，其一爲顯示子進程，其二爲隱藏子進程。

實際項目調用獨立進程模塊，是以隱藏方式調用的，以宿主展現其處理進度，如此圖：

 

 

後記：

擴展思路，一些優秀的開源工具，如youtube_dl、ffmpeg等，都以獨立進程方式存在，且可經過CMD管理通訊。

以此進程控制原理，能夠基於這些開源工具，作出至關不錯的GUI工具出來。畢竟相對於強大的命令行，人們仍是以簡單操做爲方便。