Jeg har selv brugt denne implementering af backgroundworker for at få en ordentlig cancellering:
ow///Created by Roy Osherove, Team Agile
/// Blog:
www.ISerializable.com/// Roy@TeamAgile.com
namespace WindowsApplication2
{
using System;
using System.Runtime.CompilerServices;
using System.Security.Permissions;
using System.Threading;
using System.ComponentModel;
/// <summary>
/// Replaces the standard BackgroundWorker Component in .NET 2.0 Winforms
/// To support the ability of aborting the thread the worker is using,
///and supporting the fast proporgation of ProgressChanged events without locking up
/// </summary>
/// <remarks></remarks>
public class BackgroundWorkerEx : Component
{
// Events
public event DoWorkEventHandler DoWork
{
add
{
base.Events.AddHandler(BackgroundWorkerEx.doWorkKey, value);
}
remove
{
base.Events.RemoveHandler(BackgroundWorkerEx.doWorkKey, value);
}
}
public event ProgressChangedEventHandler ProgressChanged
{
add
{
base.Events.AddHandler(BackgroundWorkerEx.progressChangedKey, value);
}
remove
{
base.Events.RemoveHandler(BackgroundWorkerEx.progressChangedKey, value);
}
}
public event RunWorkerCompletedEventHandler RunWorkerCompleted
{
add
{
base.Events.AddHandler(BackgroundWorkerEx.runWorkerCompletedKey, value);
}
remove
{
base.Events.RemoveHandler(BackgroundWorkerEx.runWorkerCompletedKey, value);
}
}
// Methods
static BackgroundWorkerEx()
{
BackgroundWorkerEx.doWorkKey = new object();
BackgroundWorkerEx.runWorkerCompletedKey = new object();
BackgroundWorkerEx.progressChangedKey = new object();
}
public BackgroundWorkerEx()
{
this.threadStart = new WorkerThreadStartDelegate(this.WorkerThreadStart);
this.operationCompleted = new SendOrPostCallback(this.AsyncOperationCompleted);
this.progressReporter = new SendOrPostCallback(this.ProgressReporter);
}
private void AsyncOperationCompleted(object arg)
{
this.isRunning = false;
this.cancellationPending = false;
this.OnRunWorkerCompleted((RunWorkerCompletedEventArgs)arg);
}
public void CancelAsync()
{
if (!this.WorkerSupportsCancellation)
{
throw new InvalidOperationException("BackgroundWorker_WorkerDoesntSupportCancellation");
}
this.cancellationPending = true;
}
protected virtual void OnDoWork(DoWorkEventArgs e)
{
mThread = Thread.CurrentThread;
DoWorkEventHandler workStartDelegate = (DoWorkEventHandler)base.Events[BackgroundWorkerEx.doWorkKey];
if (workStartDelegate != null)
{
try
{
workStartDelegate(this, e);
}
catch (ThreadAbortException)
{
Thread.ResetAbort();
}
}
}
private object tempLock = new object();
protected virtual void OnProgressChanged(ProgressChangedEventArgs e)
{
ProgressChangedEventHandler progressChangedDelegate = (ProgressChangedEventHandler)base.Events[BackgroundWorkerEx.progressChangedKey];
if (progressChangedDelegate != null)
{
progressChangedDelegate(this, e);
}
}
protected virtual void OnRunWorkerCompleted(RunWorkerCompletedEventArgs e)
{
RunWorkerCompletedEventHandler workderCompletedDelegate = (RunWorkerCompletedEventHandler)base.Events[BackgroundWorkerEx.runWorkerCompletedKey];
if (workderCompletedDelegate != null)
{
workderCompletedDelegate(this, e);
}
}
private void ProgressReporter(object arg)
{
this.OnProgressChanged((ProgressChangedEventArgs)arg);
}
public void ReportProgress(int percentProgress)
{
this.ReportProgress(percentProgress, null);
}
public void ReportProgress(int percentProgress, object userState)
{
if (!this.WorkerReportsProgress)
{
throw new InvalidOperationException("BackgroundWorker_WorkerDoesntReportProgress");
}
ProgressChangedEventArgs progressArgs = new ProgressChangedEventArgs(percentProgress, userState);
object lockTarget = new object();
if (this.asyncOperation != null)
{
this.asyncOperation.Post(this.progressReporter, progressArgs);
// Thread.Sleep(10);
}
else
{
this.progressReporter(progressArgs);
}
}
public void RunWorkerAsync()
{
this.RunWorkerAsync(null);
}
private Thread mThread;
public void StopImmediately()
{
if (!IsBusy || mThread == null)
{
return;
}
else
{
mThread.Abort();
//there is no need to catch a threadAbortException
//since we are catching it and resetting it inside the OnDoWork method
}
RunWorkerCompletedEventArgs completedArgs =
new RunWorkerCompletedEventArgs(null, null, true);
if (asyncOperation != null)
{
//invoke operation on the correct thread
asyncOperation.PostOperationCompleted(operationCompleted, completedArgs);
}
else
{
//invoke operation directly
operationCompleted(completedArgs);
}
}
public void RunWorkerAsync(object argument)
{
if (this.isRunning)
{
throw new InvalidOperationException("BackgroundWorker_WorkerAlreadyRunning");
}
this.isRunning = true;
this.cancellationPending = false;
this.asyncOperation = AsyncOperationManager.CreateOperation(null);
this.threadStart.BeginInvoke(argument, null, null);
}
private void WorkerThreadStart(object userState)
{
object result = null;
Exception workerException = null;
bool cancel = false;
try
{
DoWorkEventArgs workArgs = new DoWorkEventArgs(userState);
this.OnDoWork(workArgs);
if (workArgs.Cancel)
{
cancel = true;
}
else
{
result = workArgs.Result;
}
}
catch (Exception ex)
{
workerException = ex;
}
RunWorkerCompletedEventArgs completedArgs = new RunWorkerCompletedEventArgs(result, workerException, cancel);
if (isRunning)
{
this.asyncOperation.PostOperationCompleted(this.operationCompleted, completedArgs);
}
}
// Properties
public bool CancellationPending
{
get
{
return this.cancellationPending;
}
}
public bool IsBusy
{
get
{
return this.isRunning;
}
}
public bool WorkerReportsProgress
{
get
{
return this.workerReportsProgress;
}
set
{
this.workerReportsProgress = value;
}
}
public bool WorkerSupportsCancellation
{
get
{
return this.canCancelWorker;
}
set
{
this.canCancelWorker = value;
}
}
// Fields
private AsyncOperation asyncOperation;
private bool canCancelWorker;
private bool cancellationPending;
private static readonly object doWorkKey;
private bool isRunning;
private readonly SendOrPostCallback operationCompleted;
private static readonly object progressChangedKey;
private readonly SendOrPostCallback progressReporter;
private static readonly object runWorkerCompletedKey;
private readonly WorkerThreadStartDelegate threadStart;
private bool workerReportsProgress;
// Nested Types
private delegate void WorkerThreadStartDelegate(object argument);
}
}
