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//
// TaskAwaiter.cs
//
// Authors:
// Marek Safar <marek.safar@gmail.com>
//
// Copyright (C) 2011 Novell, Inc (http://www.novell.com)
// Copyright (C) 2011 Xamarin, Inc (http://www.xamarin.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
#if NET_4_5
using System.Threading;
using System.Threading.Tasks;
using System.Runtime.ExceptionServices;
namespace System.Runtime.CompilerServices
{
public struct TaskAwaiter : ICriticalNotifyCompletion
{
readonly Task task;
internal TaskAwaiter (Task task)
{
this.task = task;
}
public bool IsCompleted {
get {
return task.IsCompleted;
}
}
public void GetResult ()
{
if (!task.IsCompleted)
task.WaitCore (Timeout.Infinite, CancellationToken.None, true);
if (task.Status != TaskStatus.RanToCompletion)
// Merge current and dispatched stack traces if there is any
ExceptionDispatchInfo.Capture (HandleUnexpectedTaskResult (task)).Throw ();
}
internal static Exception HandleUnexpectedTaskResult (Task task)
{
var slot = task.ExceptionSlot;
switch (task.Status) {
case TaskStatus.Canceled:
// Use original exception when we have one
if (slot.Exception != null)
goto case TaskStatus.Faulted;
return new TaskCanceledException (task);
case TaskStatus.Faulted:
// Mark the exception as observed when GetResult throws
slot.Observed = true;
return slot.Exception.InnerException;
default:
throw new ArgumentException (string.Format ("Unexpected task `{0}' status `{1}'", task.Id, task.Status));
}
}
internal static void HandleOnCompleted (Task task, Action continuation, bool continueOnSourceContext, bool manageContext)
{
if (continueOnSourceContext && SynchronizationContext.Current != null && SynchronizationContext.Current.GetType () != typeof (SynchronizationContext)) {
task.ContinueWith (new SynchronizationContextContinuation (continuation, SynchronizationContext.Current));
} else {
IContinuation cont;
Task cont_task;
if (continueOnSourceContext && !TaskScheduler.IsDefault) {
cont_task = new Task (TaskActionInvoker.Create (continuation), null, CancellationToken.None, TaskCreationOptions.None, null);
cont_task.SetupScheduler (TaskScheduler.Current);
cont = new SchedulerAwaitContinuation (cont_task);
} else {
cont_task = null;
cont = new AwaiterActionContinuation (continuation);
}
//
// This is awaiter continuation. For finished tasks we get false result and need to
// queue the continuation otherwise the task would block
//
if (task.ContinueWith (cont, false))
return;
if (cont_task == null) {
cont_task = new Task (TaskActionInvoker.Create (continuation), null, CancellationToken.None, TaskCreationOptions.None, null);
cont_task.SetupScheduler (TaskScheduler.Current);
}
cont_task.Schedule (true);
}
}
public void OnCompleted (Action continuation)
{
if (continuation == null)
throw new ArgumentNullException ("continuation");
HandleOnCompleted (task, continuation, true, true);
}
public void UnsafeOnCompleted (Action continuation)
{
if (continuation == null)
throw new ArgumentNullException ("continuation");
HandleOnCompleted (task, continuation, true, false);
}
}
}
#endif
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