Cleaned and added a base class for view models with background processing tha uses the new ThreadedAction class to do its background processing; added a view binding interface for WinForms that emulates the WPF design

git-svn-id: file:///srv/devel/repo-conversion/nusu@334 d2e56fa2-650e-0410-a79f-9358c0239efd
This commit is contained in:
Markus Ewald 2019-02-06 07:00:27 +00:00
parent 97183d2335
commit 8cc16143de

View File

@ -28,433 +28,433 @@ using System.Threading.Tasks;
namespace Nuclex.Support.Threading {
/// <summary>Executes actions in a threads</summary>
public abstract class ThreadRunner : IDisposable {
/// <summary>Executes actions in a threads</summary>
public abstract class ThreadRunner : IDisposable {
#region interface IRunner
#region interface IRunner
/// <summary>Interface for a background task runner</summary>
private interface IRunner {
/// <summary>Interface for a background task runner</summary>
private interface IRunner {
/// <summary>Runs the background task</summary>
void Run();
/// <summary>Runs the background task</summary>
void Run();
/// <summary>The runner's cancellation token source</summary>
CancellationTokenSource CancellationTokenSource { get; }
/// <summary>The runner's cancellation token source</summary>
CancellationTokenSource CancellationTokenSource { get; }
}
}
#endregion // interface IRunner
#endregion // interface IRunner
#region struct Runner
#region struct Runner
/// <summary>Runs a background task with no parameters</summary>
private struct Runner : IRunner {
/// <summary>Runs a background task with no parameters</summary>
private struct Runner : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
public Runner(Action action) {
this.action = action;
}
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
public Runner(Action action) {
this.action = action;
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action();
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>Action the runner will execute</summary>
private Action action;
/// <summary>Action the runner will execute</summary>
private Action action;
}
}
#endregion // struct Runner
#endregion // struct Runner
#region struct CancellableRunner
#region struct CancellableRunner
/// <summary>Runs a background task with no parameters</summary>
private struct CancellableRunner : IRunner {
/// <summary>Runs a background task with no parameters</summary>
private struct CancellableRunner : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
public CancellableRunner(CancellableAction action) {
this.action = action;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
public CancellableRunner(CancellableAction action) {
this.action = action;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.cancellationTokenSource.Token);
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.cancellationTokenSource.Token);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction action;
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction action;
}
}
#endregion // struct CancellableRunner
#endregion // struct CancellableRunner
#region struct Runner<P1>
#region struct Runner<P1>
/// <summary>Runs a background task with one parameter</summary>
private struct Runner<P1> : IRunner {
/// <summary>Runs a background task with one parameter</summary>
private struct Runner<P1> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public Runner(Action<P1> action, P1 parameter1) {
this.action = action;
this.parameter1 = parameter1;
}
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public Runner(Action<P1> action, P1 parameter1) {
this.action = action;
this.parameter1 = parameter1;
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1);
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>Action the runner will execute</summary>
private Action<P1> action;
/// <summary>Parameter that will be passed to the action</summary>
private P1 parameter1;
/// <summary>Action the runner will execute</summary>
private Action<P1> action;
/// <summary>Parameter that will be passed to the action</summary>
private P1 parameter1;
}
}
#endregion // struct Runner<P1>
#region struct CancellableRunner<P1>
/// <summary>Runs a background task with one parameter</summary>
private struct CancellableRunner<P1> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public CancellableRunner(CancellableAction<P1> action, P1 parameter1) {
this.action = action;
this.parameter1 = parameter1;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.cancellationTokenSource.Token);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction<P1> action;
/// <summary>Parameter that will be passed to the action</summary>
private P1 parameter1;
}
#endregion // struct CancellableRunner<P1>
#region struct Runner<P1, P2>
/// <summary>Runs a background task with one parameter</summary>
private struct Runner<P1, P2> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public Runner(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.action = action;
this.parameter1 = parameter1;
this.parameter2 = parameter2;
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.parameter2);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>Action the runner will execute</summary>
private Action<P1, P2> action;
/// <summary>First parameter that will be passed to the action</summary>
private P1 parameter1;
/// <summary>Second parameter that will be passed to the action</summary>
private P2 parameter2;
}
#endregion // struct Runner<P1, P2>
#region struct CancellableRunner<P1, P2>
/// <summary>Runs a background task with one parameter</summary>
private struct CancellableRunner<P1, P2> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public CancellableRunner(CancellableAction<P1, P2> action, P1 parameter1, P2 parameter2) {
this.action = action;
this.parameter1 = parameter1;
this.parameter2 = parameter2;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.parameter2, this.cancellationTokenSource.Token);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction<P1, P2> action;
/// <summary>First parameter that will be passed to the action</summary>
private P1 parameter1;
/// <summary>Second parameter that will be passed to the action</summary>
private P2 parameter2;
}
#endregion // struct CancellableRunner<P1, P2>
/// <summary>Initializes a new background processing handler</summary>
public ThreadRunner() {
this.executeQueuedRunnersInThreadDelegate = new Action(executeQueuedRunnersInThread);
this.queuedRunners = new ConcurrentQueue<IRunner>();
}
/// <summary>
/// Immediately cancels all operations and releases the resources used by the instance
/// </summary>
public void Dispose() {
Dispose(timeoutMilliseconds: 2500);
}
/// <summary>
/// Immediately cancels all operations and releases the resources used by the instance
/// </summary>
/// <param name="timeoutMilliseconds">
/// Time to wait for the background tasks before dropping the tasks unfinished
/// </param>
public void Dispose(int timeoutMilliseconds) {
CancelAllBackgroundOperations();
Task currentTask;
lock(this) {
currentTask = this.currentTask;
}
if(currentTask != null) {
if(!currentTask.Wait(timeoutMilliseconds)) {
Debug.Assert(false, "Task does not support cancellation or did not cancel in time");
}
lock(this) {
this.currentTask = null;
IsBusy = false;
}
}
}
/// <summary>Whether the view model is currently busy executing a task</summary>
public bool IsBusy {
get { return this.isBusy; }
private set {
if(value != this.isBusy) {
this.isBusy = value;
BusyChanged();
}
}
}
/// <summary>Reports an error</summary>
/// <param name="exception">Error that will be reported</param>
protected abstract void ReportError(Exception exception);
/// <summary>Called when the status of the busy flag changes</summary>
protected abstract void BusyChanged();
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
public void RunInBackground(Action action) {
this.queuedRunners.Enqueue(new Runner(action));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
public void RunInBackground(CancellableAction action) {
this.queuedRunners.Enqueue(new CancellableRunner(action));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public void RunInBackground<P1>(Action<P1> action, P1 parameter1) {
this.queuedRunners.Enqueue(new Runner<P1>(action, parameter1));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public void RunInBackground<P1>(CancellableAction<P1> action, P1 parameter1) {
this.queuedRunners.Enqueue(new CancellableRunner<P1>(action, parameter1));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public void RunInBackground<P1, P2>(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.queuedRunners.Enqueue(new Runner<P1, P2>(action, parameter1, parameter2));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public void RunInBackground<P1, P2>(
CancellableAction<P1, P2> action, P1 parameter1, P2 parameter2
) {
this.queuedRunners.Enqueue(new CancellableRunner<P1, P2>(action, parameter1, parameter2));
startBackgroundProcessingIfNecessary();
}
/// <summary>Cancels the currently running background operation</summary>
public void CancelBackgroundOperation() {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
CancellationTokenSource cancellationTokenSource = currentRunner.CancellationTokenSource;
if(cancellationTokenSource != null) {
cancellationTokenSource.Cancel();
}
}
}
/// <summary>Cancels all queued and the currently running background operation</summary>
public void CancelAllBackgroundOperations() {
IRunner runner;
while(this.queuedRunners.TryDequeue(out runner)) {
CancellationTokenSource cancellationTokenSource = runner.CancellationTokenSource;
if(cancellationTokenSource != null) {
cancellationTokenSource.Cancel();
}
}
CancelBackgroundOperation();
}
/// <summary>Whether the background operation has been cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
public bool IsBackgroundOperationCancelled {
get {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
return currentRunner.CancellationTokenSource.IsCancellationRequested;
} else {
return false;
}
}
}
/// <summary>Throws an exception if the background operation was cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
public void ThrowIfBackgroundOperationCancelled() {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
currentRunner.CancellationTokenSource.Token.ThrowIfCancellationRequested();
}
}
/// <summary>Executes the queued runners in the background</summary>
private void executeQueuedRunnersInThread() {
IsBusy = true;
IRunner runner;
while(this.queuedRunners.TryDequeue(out runner)) {
try {
this.currentRunner = runner;
runner.Run();
}
catch(OperationCanceledException) {
// Ignore
}
catch(Exception exception) {
this.currentRunner = null; // When the error is reported this should already be null
ReportError(exception);
}
this.currentRunner = null;
}
lock(this) {
this.currentTask = null;
IsBusy = false;
}
}
/// <summary>Starts the background processing thread, if needed</summary>
private void startBackgroundProcessingIfNecessary() {
Task currentTask;
lock(this) {
if(this.currentTask == null) {
currentTask = new Task(this.executeQueuedRunnersInThreadDelegate);
this.currentTask = currentTask;
} else {
return; // Task is already running
}
}
// Start the task outside of the lock statement so that when the thread starts to run,
// it is guaranteed to read the currentTask variable as the task we just created.
currentTask.Start();
}
/// <summary>Whether the view model is currently busy executing a task</summary>
private volatile bool isBusy;
/// <summary>Delegate for the executedQueuedRunnersInThread() method</summary>
private Action executeQueuedRunnersInThreadDelegate;
/// <summary>Queued background operations</summary>
private ConcurrentQueue<IRunner> queuedRunners;
/// <summary>Runner currently executing in the background</summary>
private volatile IRunner currentRunner;
/// <summary>Task that is currently executing the runners</summary>
private Task currentTask;
}
#endregion // struct Runner<P1>
#region struct CancellableRunner<P1>
/// <summary>Runs a background task with one parameter</summary>
private struct CancellableRunner<P1> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public CancellableRunner(CancellableAction<P1> action, P1 parameter1) {
this.action = action;
this.parameter1 = parameter1;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.cancellationTokenSource.Token);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction<P1> action;
/// <summary>Parameter that will be passed to the action</summary>
private P1 parameter1;
}
#endregion // struct CancellableRunner<P1>
#region struct Runner<P1, P2>
/// <summary>Runs a background task with one parameter</summary>
private struct Runner<P1, P2> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public Runner(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.action = action;
this.parameter1 = parameter1;
this.parameter2 = parameter2;
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.parameter2);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return null; }
}
/// <summary>Action the runner will execute</summary>
private Action<P1, P2> action;
/// <summary>First parameter that will be passed to the action</summary>
private P1 parameter1;
/// <summary>Second parameter that will be passed to the action</summary>
private P2 parameter2;
}
#endregion // struct Runner<P1, P2>
#region struct CancellableRunner<P1, P2>
/// <summary>Runs a background task with one parameter</summary>
private struct CancellableRunner<P1, P2> : IRunner {
/// <summary>Initializes a new runner</summary>
/// <param name="action">Action the runner will execute</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public CancellableRunner(CancellableAction<P1, P2> action, P1 parameter1, P2 parameter2) {
this.action = action;
this.parameter1 = parameter1;
this.parameter2 = parameter2;
this.cancellationTokenSource = new CancellationTokenSource();
}
/// <summary>Executes the runner's action</summary>
public void Run() {
this.action(this.parameter1, this.parameter2, this.cancellationTokenSource.Token);
}
/// <summary>The runner's cancellation token source</summary>
public CancellationTokenSource CancellationTokenSource {
get { return this.cancellationTokenSource; }
}
/// <summary>The runner's cancellation token source</summary>
private CancellationTokenSource cancellationTokenSource;
/// <summary>Action the runner will execute</summary>
private CancellableAction<P1, P2> action;
/// <summary>First parameter that will be passed to the action</summary>
private P1 parameter1;
/// <summary>Second parameter that will be passed to the action</summary>
private P2 parameter2;
}
#endregion // struct CancellableRunner<P1, P2>
/// <summary>Initializes a new background processing handler</summary>
public ThreadRunner() {
this.executeQueuedRunnersInThreadDelegate = new Action(executeQueuedRunnersInThread);
this.queuedRunners = new ConcurrentQueue<IRunner>();
}
/// <summary>
/// Immediately cancels all operations and releases the resources used by the instance
/// </summary>
public void Dispose() {
Dispose(timeoutMilliseconds: 2500);
}
/// <summary>
/// Immediately cancels all operations and releases the resources used by the instance
/// </summary>
/// <param name="timeoutMilliseconds">
/// Time to wait for the background tasks before dropping the tasks unfinished
/// </param>
public void Dispose(int timeoutMilliseconds) {
CancelAllBackgroundOperations();
Task currentTask;
lock(this) {
currentTask = this.currentTask;
}
if(currentTask != null) {
if(!currentTask.Wait(timeoutMilliseconds)) {
Debug.Assert(false, "Task does not support cancellation or did not cancel in time");
}
lock(this) {
this.currentTask = null;
IsBusy = false;
}
}
}
/// <summary>Whether the view model is currently busy executing a task</summary>
public bool IsBusy {
get { return this.isBusy; }
private set {
if(value != this.isBusy) {
this.isBusy = value;
BusyChanged();
}
}
}
/// <summary>Reports an error</summary>
/// <param name="exception">Error that will be reported</param>
protected abstract void ReportError(Exception exception);
/// <summary>Called when the status of the busy flag changes</summary>
protected abstract void BusyChanged();
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
public void RunInBackground(Action action) {
this.queuedRunners.Enqueue(new Runner(action));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
public void RunInBackground(CancellableAction action) {
this.queuedRunners.Enqueue(new CancellableRunner(action));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public void RunInBackground<P1>(Action<P1> action, P1 parameter1) {
this.queuedRunners.Enqueue(new Runner<P1>(action, parameter1));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">Parameter that will be passed to the action</param>
public void RunInBackground<P1>(CancellableAction<P1> action, P1 parameter1) {
this.queuedRunners.Enqueue(new CancellableRunner<P1>(action, parameter1));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public void RunInBackground<P1, P2>(Action<P1, P2> action, P1 parameter1, P2 parameter2) {
this.queuedRunners.Enqueue(new Runner<P1, P2>(action, parameter1, parameter2));
startBackgroundProcessingIfNecessary();
}
/// <summary>Executes the specified operation in the background</summary>
/// <param name="action">Action that will be executed in the background</param>
/// <param name="parameter1">First parameter that will be passed to the action</param>
/// <param name="parameter2">Second parameter that will be passed to the action</param>
public void RunInBackground<P1, P2>(
CancellableAction<P1, P2> action, P1 parameter1, P2 parameter2
) {
this.queuedRunners.Enqueue(new CancellableRunner<P1, P2>(action, parameter1, parameter2));
startBackgroundProcessingIfNecessary();
}
/// <summary>Cancels the currently running background operation</summary>
public void CancelBackgroundOperation() {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
CancellationTokenSource cancellationTokenSource = currentRunner.CancellationTokenSource;
if(cancellationTokenSource != null) {
cancellationTokenSource.Cancel();
}
}
}
/// <summary>Cancels all queued and the currently running background operation</summary>
public void CancelAllBackgroundOperations() {
IRunner runner;
while(this.queuedRunners.TryDequeue(out runner)) {
CancellationTokenSource cancellationTokenSource = runner.CancellationTokenSource;
if(cancellationTokenSource != null) {
cancellationTokenSource.Cancel();
}
}
CancelBackgroundOperation();
}
/// <summary>Whether the background operation has been cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
public bool IsBackgroundOperationCancelled {
get {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
return currentRunner.CancellationTokenSource.IsCancellationRequested;
} else {
return false;
}
}
}
/// <summary>Throws an exception if the background operation was cancelled</summary>
//[Obsolete("Please use a method accepting a cancellation token instead of using this")]
public void ThrowIfBackgroundOperationCancelled() {
IRunner currentRunner = this.currentRunner;
if(currentRunner != null) {
currentRunner.CancellationTokenSource.Token.ThrowIfCancellationRequested();
}
}
/// <summary>Executes the queued runners in the background</summary>
private void executeQueuedRunnersInThread() {
IsBusy = true;
IRunner runner;
while(this.queuedRunners.TryDequeue(out runner)) {
try {
this.currentRunner = runner;
runner.Run();
}
catch(OperationCanceledException) {
// Ignore
}
catch(Exception exception) {
this.currentRunner = null; // When the error is reported this should already be null
ReportError(exception);
}
this.currentRunner = null;
}
lock(this) {
this.currentTask = null;
IsBusy = false;
}
}
/// <summary>Starts the background processing thread, if needed</summary>
private void startBackgroundProcessingIfNecessary() {
Task currentTask;
lock(this) {
if(this.currentTask == null) {
currentTask = new Task(this.executeQueuedRunnersInThreadDelegate);
this.currentTask = currentTask;
} else {
return; // Task is already running
}
}
// Start the task outside of the lock statement so that when the thread starts to run,
// it is guaranteed to read the currentTask variable as the task we just created.
currentTask.Start();
}
/// <summary>Whether the view model is currently busy executing a task</summary>
private volatile bool isBusy;
/// <summary>Delegate for the executedQueuedRunnersInThread() method</summary>
private Action executeQueuedRunnersInThreadDelegate;
/// <summary>Queued background operations</summary>
private ConcurrentQueue<IRunner> queuedRunners;
/// <summary>Runner currently executing in the background</summary>
private volatile IRunner currentRunner;
/// <summary>Task that is currently executing the runners</summary>
private Task currentTask;
}
} // namespace Nuclex.Support.Threading