Csharp/CSharp Tutorial/File Directory Stream/Asynchronous Input Output

Async File Stream

<source lang="csharp">using System; using System.Collections.Generic; using System.Text; using System.Threading; using System.IO; class Program {

   static void Main(string[] args) {
       Console.WriteLine("Main thread started. ThreadID = {0}", Thread.CurrentThread.GetHashCode());
       FileStream fs = new FileStream("logfile.txt", FileMode.Append, FileAccess.Write, FileShare.None, 4096, true);
       string msg = "this is a test";
       byte[] buffer = Encoding.ASCII.GetBytes(msg);
       fs.BeginWrite(buffer, 0, buffer.Length, new AsyncCallback(WriteDone), fs);
   }
   private static void WriteDone(IAsyncResult ar) {
       Console.WriteLine("AsyncCallback method on ThreadID = {0}", Thread.CurrentThread.GetHashCode());
       Stream s = (Stream)ar.AsyncState;
       s.EndWrite(ar);
       s.Close();
   }

}</source>

Async FileStream demo

<source lang="csharp">using System; using System.Collections.Generic; using System.Text; using System.IO; using System.Threading;

 class Program
 {
   static void Main(string[] args)
   {
     FileStream fs = new FileStream("logfile.txt", FileMode.Append,FileAccess.Write, FileShare.None, 4096, true);
     string msg = "this is a test";
     byte[] buffer = Encoding.ASCII.GetBytes(msg);
     fs.BeginWrite(buffer, 0, buffer.Length,new AsyncCallback(WriteDone), fs);
   }
   private static void WriteDone(IAsyncResult ar)
   {
     Stream s = (Stream)ar.AsyncState;
     s.EndWrite(ar);
     s.Close();
   }
 }</source>

Asynchronous I/O

<source lang="csharp">using System; using System.IO; using System.Windows.Forms; class MainClass {

 private static FileStream inStream;
 static void OnComplete(IAsyncResult asyncResult)
 {
   int bytesRead = inStream.EndRead(asyncResult);
   Console.Write(bytesRead);
 }
 public static void Main() 
 {
   inStream = new FileStream("C:\\text.txt", FileMode.Open, FileAccess.Read, FileShare.None, 2048, true);
   AsyncCallback  acb = new AsyncCallback(OnComplete);
   byte[] buf = new byte[50];
   
   inStream.BeginRead(buf, 0, 50, acb, null);
   for(int i=0; i<10; i++)
     Console.WriteLine(i);
   Console.WriteLine("Press Enter to exit");
   int resp = Console.Read();
 }

}</source>

Asynchronous I/O, some blocking on the main thread

<source lang="csharp">using System; using System.Collections.Generic; using System.Collections.Specialized; using System.IO; using System.IO.rupression; using System.Net; using System.Net.Mail; using System.Runtime.InteropServices; using System.Text; public class MainClass {

   public static void Main()
   {
       using (Stream s = new FileStream("c:\\test.txt", FileMode.Open))
       {
           byte[] buffer = new byte[4096];
           int bytesRead;
           do
           {
               IAsyncResult ar = s.BeginRead(buffer, 0, buffer.Length, null, null);
               bytesRead = s.EndRead(ar);
           }
           while (bytesRead == buffer.Length);
       }
   }

}</source>

Asynchronous IO with AsyncCallback

<source lang="csharp">using System; using System.Collections.Generic; using System.IO; using System.Text;

  public class MainClass
  {
     static Stream inputStream;
     static AsyncCallback myCallBack;
     static byte[] buffer;
     static int BufferSize = 256;
     public static void Main()
     {
        inputStream = File.OpenRead("AskTim.txt" );
        buffer = new byte[BufferSize];
        myCallBack = new AsyncCallback( OnCompletedRead );
        inputStream.BeginRead(
           buffer,             // holds the results
           0,                  // offset
           buffer.Length,      // (BufferSize)
           myCallBack,         // call back delegate
           null );             // local state object
     }
     static void OnCompletedRead( IAsyncResult asyncResult )
     {
        int bytesRead = inputStream.EndRead( asyncResult );
        if ( bytesRead > 0 ){
           String s = Encoding.ASCII.GetString( buffer, 0, bytesRead );
           Console.WriteLine( s );
           inputStream.BeginRead(buffer, 0, buffer.Length, myCallBack, null );
        }
     }
  }</source>