public void BackgroundProcessing()
{
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
var worker = new BackgroundWorker
{
WorkerReportsProgress = true,
WorkerSupportsCancellation = true
};
worker.DoWork += (sender, e) =>
{
var threadInfo = ThreadInfo.GetCurrentThreadInfo();
for (int i = 1; i <= 100; i++)
{
Thread.Sleep(50);
worker.ReportProgress(i);
}
};
worker.ProgressChanged += (sender, e) =>
{
Debug.WriteLine(e.ProgressPercentage);
};
worker.RunWorkerCompleted += (sender, e) =>
{
var threadInfo = ThreadInfo.GetCurrentThreadInfo();
};
worker.RunWorkerAsync();
}
static void Main(string[] args)
{
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
// shows how to block the execution when it's not possible to mark containing method as async
string result = dotNet45Task.ASyncCallWithContinuation().GetAwaiter().GetResult();
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
}
private void button2_Click(object sender, EventArgs e)
{
// shows how asynchronous I/O executes using I/O completion ports (watch debug output), but still blocks executing thread
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
string result = preTask.AsyncCallWithWait();
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
}
private async void button6_Click(object sender, EventArgs e)
{
// shows how using async/await can simplify asynchronous calls (and context synchronization)
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
string result = await dotNet45Task.ASyncCallWithContinuation();
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
}
private void button4_Click(object sender, EventArgs e)
{
// shows blocking TPM approach to asynchronous calls (no gain over APM)
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
string result = dotNet4Task.AsyncCallWithWait();
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
}
private void button5_Click(object sender, EventArgs e)
{
// shows non blocking TPM approach to asynchronous calls (but still with callbacks and synchronization problems)
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
dotNet4Task.ASyncCallWithContinuation().ContinueWith(task =>
{
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(task.Result);
}); // fix: }, TaskScheduler.FromCurrentSynchronizationContext());
}
private void button3_Click(object sender, EventArgs e)
{
// shows how asynchronous programming was in APM (callback hell and synchronization problems)
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
preTask.ASyncCallWithCallback(result =>
{
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
});
}
public Task <string> BackgroundProcessing()
{
return(Task.Factory.StartNew(() =>
{
var threadInfo = ThreadInfo.GetCurrentThreadInfo();
for (int i = 1; i <= 100; i++)
{
Thread.Sleep(50);
}
return "ok";
})); // fix: }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default
}
private void button7_Click(object sender, EventArgs e)
{
// shows how default context synchronization used in conjunction with blocking can cause a deadlock
// let's assume that we can't change method signature to async so we need to use blocking
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
string result = dotNet45Task.ASyncCallWithContinuation().Result; // fix: see DotNet45TaskExamples.ASyncCallWithContinuation() source
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
}
private void button11_Click(object sender, EventArgs e)
{
// shows why Task.Factory.StartNew default settings are dangerous
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
dotNet4Task.BackgroundProcessing().ContinueWith(task =>
{
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
// second call - watch thread info
dotNet4Task.BackgroundProcessing(); // fix: see DotNet4TaskExamples.BackgroundProcessing() source
MessageBox.Show(task.Result);
}, TaskScheduler.FromCurrentSynchronizationContext());
}
public Task <string> BackgroundProcessingAlternative()
{
var backgroundTask = new Task <string>(() =>
{
var threadInfo = ThreadInfo.GetCurrentThreadInfo();
for (int i = 1; i <= 100; i++)
{
Thread.Sleep(50);
}
return("ok");
});
backgroundTask.Start(TaskScheduler.Default);
return(backgroundTask);
}
private async void button12_Click(object sender, EventArgs e)
{
// shows how to perform ThreadPool calculations in .NET 4.5
var entryThreadInfo = ThreadInfo.GetCurrentThreadInfo();
var processingCancellation = new CancellationTokenSource();
//processingCancellation.Cancel(); // causes TaskCancelledException
Task <string> processingTask = dotNet45Task.BackgroundProcessing(processingCancellation.Token);
//Thread.Sleep(2000);
//processingCancellation.Cancel(); // causes OperationCancelledException
string result = await processingTask;
var returningThreadInfo = ThreadInfo.GetCurrentThreadInfo();
MessageBox.Show(result);
}
public Task <string> BackgroundProcessing(CancellationToken cancellationToken)
{
var progressHandler = new Progress <int>(value =>
{
Debug.WriteLine(value);
});
var progress = (IProgress <int>)progressHandler;
return(Task.Run(() =>
{
var threadInfo = ThreadInfo.GetCurrentThreadInfo();
for (int i = 1; i <= 100; i++)
{
cancellationToken.ThrowIfCancellationRequested();
Thread.Sleep(50);
progress.Report(i);
}
return "ok";
}, cancellationToken));
}
