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如何异步运行 NamedPipeServerStream？

我没有通过服务器在另一台计算机中使用管道。我只在我的电脑上使用它。这是代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.IO.Pipes;
using System.Runtime.InteropServices;

namespace ScreenVideoRecorder
{
    class Ffmpeg
    {
        NamedPipeServerStream p;
        String pipename = "mytestpipe";
        byte[] b;
        //int i, j;
        System.Diagnostics.Process process;

        public Ffmpeg()
        {

        }

        public void Start(string FileName, int BitmapRate )
        {
            p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
            b = new byte[1920 * 1080 * 3]; // Some buffer for the R, G and B of pixels of an image of size 720p.
            process = new System.Diagnostics.Process();
            process.StartInfo.FileName = @"D:\pipetest\pipetest\ffmpegx86\ffmpeg.exe";
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:\pipetest\pipetest\ffmpegx86";
            process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
            process.Start();

            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            p.WaitForConnection();
        }

一切正常。问题是当进程启动时，我看到命令提示符窗口并看到窗口中的所有工作。我无法访问表格。我可以在屏幕上拖动/移动命令提示符窗口，但我无法进入表单窗口以单击按钮或停止操作。我需要先等待它完成才能在命令提示符窗口或进程窗口中完成工作。

使用下面的代码行，我看到了变量 p 的一个属性来检查它是否是异步的，但是我如何将它设置为异步呢？

p.IsAsync

我试图找到示例，但它们都是根据我认为具有安全性的两台计算机之间的服务器。

后来，我改变了这一行：

p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte,PipeOptions.Asynchronous);

最后添加：PipeOptions.Asynchronous

现在，当我运行我的应用程序时，我遇到了异常：

p.Write(rgbValues, 0, length);

例外：

InvalidOperationException：管道尚未连接。

这是我所有更改的完整代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.IO.Pipes;
using System.Runtime.InteropServices;

namespace ScreenVideoRecorder
{
    class Ffmpeg
    {
        NamedPipeServerStream p;
        String pipename = "mytestpipe";
        byte[] b;
        //int i, j;
        System.Diagnostics.Process process;
        IAsyncResult ar;

        public Ffmpeg()
        {

        }

        public void Start(string FileName, int BitmapRate )
        {
            p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte,PipeOptions.Asynchronous);
            b = new byte[1920 * 1080 * 3]; // Some buffer for the R G and B of pixels of an image of size 720p.
            process = new System.Diagnostics.Process();
            process.StartInfo.FileName = @"D:\pipetest\pipetest\ffmpegx86\ffmpeg.exe";
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:\pipetest\pipetest\ffmpegx86";
            process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
            process.Start();

            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            ar = p.BeginWaitForConnection(EndWait,null);
        }

        void EndWait(IAsyncResult iar)
        {
            var state = ar.AsyncState; //fetch result, mandatory!
        }

        public void PushFrame(Bitmap bmp)
        {
            int length;
            // Lock the bitmap's bits.
            //bmp = new Bitmap(1920, 1080);
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            //Rectangle rect = new Rectangle(0, 0, 1280, 720);
            System.Drawing.Imaging.BitmapData bmpData =
                bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly,
                bmp.PixelFormat);

            int absStride = Math.Abs(bmpData.Stride);
            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;

            // Declare an array to hold the bytes of the bitmap.
            //length = 3 * bmp.Width * bmp.Height;
            length = absStride * bmpData.Height;
            byte[] rgbValues = new byte[length];

            //Marshal.Copy(ptr, rgbValues, 0, length);
            int j = bmp.Height - 1;
            for (int i = 0; i < bmp.Height; i++)
            {
                IntPtr pointer = new IntPtr(bmpData.Scan0.ToInt32() + (bmpData.Stride * j));
                System.Runtime.InteropServices.Marshal.Copy(pointer, rgbValues, absStride * (bmp.Height - i - 1), absStride);
                j--;
            }

            p.Write(rgbValues, 0, length);
            bmp.UnlockBits(bmpData);

异常消息：

System.InvalidOperationException was unhandled
  HResult=-2146233079
  Message=Pipe hasn't been connected yet.
  Source=System.Core
  StackTrace:
       at System.IO.Pipes.PipeStream.CheckWriteOperations()
       at System.IO.Pipes.PipeStream.Write(Byte[] buffer, Int32 offset, Int32 count)
       at ScreenVideoRecorder.Ffmpeg.PushFrame(Bitmap bmp) in d:\C-Sharp\ScreenVideoRecorder\ScreenVideoRecorderWorkingVersion\Ffmpeg.cs:line 77
       at ScreenVideoRecorder.Form1.StartRecording_Click(Object sender, EventArgs e) in d:\C-Sharp\ScreenVideoRecorder\ScreenVideoRecorderWorkingVersion\Form1.cs:line 53
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at ScreenVideoRecorder.Program.Main() in d:\C-Sharp\ScreenVideoRecorder\ScreenVideoRecorderWorkingVersion\Program.cs:line 18
       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()
  InnerException:
4

1 回答 1

2

当您使用当前线程时，NamedPipeServerStream.WaitForConnection您的当前线程将阻塞，直到操作完成。
您可以使用BeginWaitForConnection创建一个将在后台工作的线程。
使用返回的IAsyncResult，您可以获取异步操作的结果。

来自MSDN：

IAsyncResult 接口由包含可以异步操作的方法的类实现。它是启动异步操作的方法的返回类型，例如FileStream.BeginRead，并传递给结束异步操作的方法，例如FileStream.EndRead。当异步操作完成时，IAsyncResult对象也会传递给委托调用的方法。AsyncCallback支持IAsyncResult接口的对象存储异步操作的状态信息并提供同步对象以允许在操作完成时向线程发出信号。

class Ffmpeg
{
    NamedPipeServerStream p;
    String pipename = "mytestpipe";
    byte[] b;
    //int i, j;
    System.Diagnostics.Process process;
    IAsyncResult ar;

    public Ffmpeg()
    {

    }

    public void Start(string FileName, int BitmapRate )
    {
        p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
        b = new byte[1920 * 1080 * 3]; // some buffer for the r g and b of pixels of an image of size 720p 
        process = new System.Diagnostics.Process();
        process.StartInfo.FileName = @"D:\pipetest\pipetest\ffmpegx86\ffmpeg.exe";
        process.EnableRaisingEvents = false;
        process.StartInfo.WorkingDirectory = @"D:\pipetest\pipetest\ffmpegx86";
        process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
        process.Start();

        process.StartInfo.UseShellExecute = false;
        process.StartInfo.CreateNoWindow = false;
        ar = p.BeginWaitForConnection(EndWait, null);
    }

//callback when client connects
void EndWait(IAsyncResult iar){
    var state = iar.AsyncState; // fetch state -> cast to desired type
    //do something when client connected
}
于 2013-05-25T04:53:18.663 回答