/// <summary>Begins to continue the workflow.</summary>
/// <param name="callback">The method to be called when the asynchronous continue operation is completed.</param>
/// <param name="state">A user-provided object that distinguishes this particular asynchronous continue request from other requests.</param>
/// <returns>An <see cref="IAsyncResult"/> that references the asynchronous continue.</returns>
public IAsyncResult BeginContinue(AsyncCallback callback, object state)
{
AsyncResultVoid result = new AsyncResultVoid(callback, state);
ThreadPool.QueueUserWorkItem(this.ContinueWorkflowHelper, result);
return(result);
}
/// <summary>Waits for the pending asynchronous continue to complete.</summary>
/// <param name="asyncResult">The reference to the pending asynchronous request to wait for.</param>
/// <exception cref="NotSupportedException">The workflow does not support pausing and continuing.</exception>
/// <exception cref="InvalidOperationException">The workflow is not in a state in which it can be continued. Only when the workflow is in the
/// state <see cref="WorkflowState.Paused"/>, it can be continued.</exception>
/// <seealso cref="CanPauseAndContinue"/>
public void EndContinue(IAsyncResult asyncResult)
{
Guard.ArgumentIsNotNull(asyncResult, nameof(asyncResult));
AsyncResultVoid result = asyncResult as AsyncResultVoid;
if (result == null)
{
throw new ArgumentException("The specified IAsyncResult was not of the expected type AsyncResultVoid", "asyncResult");
}
result.EndInvoke();
return;
}
/// <summary>Executes the <see cref="Continue()"/> method in a separate thread. This is used to support asynchronous operations.</summary>
/// <param name="asyncResult">The object that holds the status of the asynchronous operation.</param>
private void ContinueWorkflowHelper(object asyncResult)
{
AsyncResultVoid result = asyncResult as AsyncResultVoid;
if (result == null)
{
throw new ArgumentException("The specified object was not of the expected type AsyncResultVoid", "asyncResult");
}
try {
this.Continue();
result.SetAsCompleted(null, false);
}
catch (Exception ex) {
/* We deliberately catch every exception. It is up to the caller of EndContinue() to do a more fine-grained exception handling */
result.SetAsCompleted(ex, false);
}
}