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2010-05-26T15:31:19Z

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2010-05-26T11:45:37Z

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==Asynchronous Writing, Asynchronous Reading==

<source lang="csharp">
//Code revised from Chapter 25 - Accessing Data Streams
//C# Bible
//by Jeff Ferguson et al.

using System;
using System.IO;
using System.Threading;

class FileTestClass
{
private static FileStream BinaryFile = new FileStream("test.dat", FileMode.Create, FileAccess.ReadWrite);
private static byte [] ByteArray = new byte [256];
private static IAsyncResult AsyncReadResultImplementation = null;
private static IAsyncResult AsyncWriteResultImplementation;
private static AsyncCallback ReadBytesCompleteCallback = new AsyncCallback(OnReadBytesComplete);
private static AsyncCallback WriteBytesCompleteCallback = new AsyncCallback(OnWriteBytesComplete);

public static void OnReadBytesComplete(IAsyncResult AsyncResult)
{
int BytesRead;
int Failures;

BytesRead = BinaryFile.EndRead(AsyncResult);
Console.WriteLine("Bytes read........: {0}", BytesRead);
Failures = 0;
for(int i = 0; i < 256; i++)
{
if(ByteArray[i] != (byte)i)
{
Console.WriteLine("Read test failed for byte at offset {0}.", i);
Failures++;
}
}
Console.WriteLine("Read test failures: {0}", Failures);
}
public static void OnWriteBytesComplete(IAsyncResult AsyncResult)
{
BinaryFile.EndWrite(AsyncResult);
}
static public void Main()
{
for(int i = 0; i < 256; i++)
ByteArray[i] = (byte)i;
AsyncWriteResultImplementation = BinaryFile.BeginWrite(ByteArray, 0, 256, WriteBytesCompleteCallback, null);

WaitHandle WaitOnWriteIO = AsyncWriteResultImplementation.AsyncWaitHandle;
WaitOnWriteIO.WaitOne();

BinaryFile.Seek(0, SeekOrigin.Begin);
AsyncReadResultImplementation = BinaryFile.BeginRead(ByteArray, 0, 256, ReadBytesCompleteCallback, null);
WaitHandle WaitOnReadIO = AsyncReadResultImplementation.AsyncWaitHandle;
WaitOnReadIO.WaitOne();
}
}

</source>

==illustrates asynchronous I/O==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example15_18.cs illustrates asynchronous I/O
*/
using System;
using System.IO;
using System.Windows.Forms;
public class Example15_18
{
// stream to handle reading
private static FileStream inStream;
// delegated method to handle callback
private static AsyncCallback acb;
// allocate a big buffer for reading
static byte[] buf = new byte[500000];
// callback to use when read is complete
static void OnComplete(IAsyncResult asyncResult)
{
int bytesRead = inStream.EndRead(asyncResult);
Console.Write(bytesRead);
Console.WriteLine(" bytes read!");
}

[STAThread]
public static void Main()
{
// use an open file dialog to get a filename
OpenFileDialog dlgOpen = new OpenFileDialog();
dlgOpen.Title="Select file to read";
if (dlgOpen.ShowDialog() == DialogResult.OK)
{
// open the file
inStream = new FileStream(dlgOpen.FileName, FileMode.Open,
FileAccess.Read, FileShare.None, 2048, true);
// assign the callback delegate
acb = new AsyncCallback(OnComplete);
// read asynchronously
inStream.BeginRead(buf, 0, 500000, acb, null);
// do some work in the meantime
for(int i=0; i<10; i++)
Console.WriteLine(i);
// And wait for the user to quit
Console.WriteLine("Press Enter to exit");
int resp = Console.Read();
}
}
}

</source>

==Synchronous Writing, Asynchronous Reading==

<source lang="csharp">
//Code revised from Chapter 25 - Accessing Data Streams
//C# Bible
//by Jeff Ferguson et al.
using System;
using System.IO;
using System.Threading;

class FileTestClass
{
private static FileStream BinaryFile = new FileStream("test.dat", FileMode.Create, FileAccess.ReadWrite);
private static byte [] ByteArray = new byte [256];
private static IAsyncResult AsyncResultImplementation;
private static AsyncCallback ReadBytesCompleteCallback= new AsyncCallback(OnReadBytesComplete);
public static void OnReadBytesComplete(IAsyncResult AsyncResult)
{
int BytesRead;
int Failures;

BytesRead = BinaryFile.EndRead(AsyncResult);
Failures = 0;
for(int i = 0; i < 256; i++)
{
if(ByteArray[i] != (byte)i)
{
Console.WriteLine("Read test failed for byte at offset {0}.", i);
Failures++;
}
}
}
static public void Main()
{
for(int i = 0; i < 256; i++)
ByteArray[i] = (byte)i;
BinaryFile.Write(ByteArray, 0, 256);
BinaryFile.Seek(0, SeekOrigin.Begin);
AsyncResultImplementation = BinaryFile.BeginRead(ByteArray, 0, 256, ReadBytesCompleteCallback, null);
WaitHandle WaitOnReadIO = AsyncResultImplementation.AsyncWaitHandle;
WaitOnReadIO.WaitOne();
}
}

</source>

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