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AsyncHelpers to simplify calling of Async/Task methods from synchronous context.
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namespace My.Common | |
{ | |
using System; | |
using System.Collections.Generic; | |
using System.Threading; | |
using System.Threading.Tasks; | |
public static class AsyncHelpers | |
{ | |
/// <summary> | |
/// Execute's an async Task<T> method which has a void return value synchronously | |
/// </summary> | |
/// <param name="task"> | |
/// Task<T> method to execute | |
/// </param> | |
public static void RunSync(Func<Task> task) | |
{ | |
var oldContext = SynchronizationContext.Current; | |
var synch = new ExclusiveSynchronizationContext(); | |
SynchronizationContext.SetSynchronizationContext(synch); | |
synch.Post(async _ => | |
{ | |
try | |
{ | |
await task(); | |
} | |
catch (Exception e) | |
{ | |
synch.InnerException = e; | |
throw; | |
} | |
finally | |
{ | |
synch.EndMessageLoop(); | |
} | |
}, null); | |
synch.BeginMessageLoop(); | |
SynchronizationContext.SetSynchronizationContext(oldContext); | |
} | |
/// <summary> | |
/// Execute's an async Task<T> method which has a T return type synchronously | |
/// </summary> | |
/// <typeparam name="T">Return Type</typeparam> | |
/// <param name="task"> | |
/// Task<T> method to execute | |
/// </param> | |
/// <returns></returns> | |
public static T RunSync<T>(Func<Task<T>> task) | |
{ | |
var oldContext = SynchronizationContext.Current; | |
var synch = new ExclusiveSynchronizationContext(); | |
SynchronizationContext.SetSynchronizationContext(synch); | |
T ret = default(T); | |
synch.Post(async _ => | |
{ | |
try | |
{ | |
ret = await task(); | |
} | |
catch (Exception e) | |
{ | |
synch.InnerException = e; | |
throw; | |
} | |
finally | |
{ | |
synch.EndMessageLoop(); | |
} | |
}, null); | |
synch.BeginMessageLoop(); | |
SynchronizationContext.SetSynchronizationContext(oldContext); | |
return ret; | |
} | |
private class ExclusiveSynchronizationContext : SynchronizationContext | |
{ | |
private readonly Queue<Tuple<SendOrPostCallback, object>> _items = | |
new Queue<Tuple<SendOrPostCallback, object>>(); | |
private readonly AutoResetEvent _workItemsWaiting = new AutoResetEvent(false); | |
private bool done; | |
public Exception InnerException { get; set; } | |
public override void Send(SendOrPostCallback d, object state) | |
{ | |
throw new NotSupportedException("We cannot send to our same thread"); | |
} | |
public override void Post(SendOrPostCallback d, object state) | |
{ | |
lock (_items) | |
{ | |
_items.Enqueue(Tuple.Create(d, state)); | |
} | |
_workItemsWaiting.Set(); | |
} | |
public void EndMessageLoop() | |
{ | |
Post(_ => done = true, null); | |
} | |
public void BeginMessageLoop() | |
{ | |
while (!done) | |
{ | |
Tuple<SendOrPostCallback, object> task = null; | |
lock (_items) | |
{ | |
if (_items.Count > 0) | |
{ | |
task = _items.Dequeue(); | |
} | |
} | |
if (task != null) | |
{ | |
task.Item1(task.Item2); | |
if (InnerException != null) // the method threw an exeption | |
{ | |
throw new AggregateException("AsyncHelpers.Run method threw an exception.", InnerException); | |
} | |
} | |
else | |
{ | |
_workItemsWaiting.WaitOne(); | |
} | |
} | |
} | |
public override SynchronizationContext CreateCopy() | |
{ | |
return this; | |
} | |
} | |
} | |
} |
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