TaskToAsyncResult
using System.Runtime.CompilerServices;
namespace System.Threading.Tasks
{
[System.Runtime.CompilerServices.NullableContext(1)]
[System.Runtime.CompilerServices.Nullable(0)]
internal static class TaskToAsyncResult
{
private sealed class TaskAsyncResult : IAsyncResult
{
internal readonly Task _task;
private readonly AsyncCallback _callback;
public object AsyncState { get; }
public bool CompletedSynchronously { get; }
public bool IsCompleted => _task.IsCompleted;
public WaitHandle AsyncWaitHandle => ((IAsyncResult)_task).AsyncWaitHandle;
internal TaskAsyncResult(Task task, object state, AsyncCallback callback)
{
_task = task;
AsyncState = state;
if (task.IsCompleted) {
CompletedSynchronously = true;
callback?.Invoke(this);
} else if (callback != null) {
_callback = callback;
_task.ConfigureAwait(false).GetAwaiter().OnCompleted(delegate {
_callback(this);
});
}
}
}
public static IAsyncResult Begin(Task task, [System.Runtime.CompilerServices.Nullable(2)] AsyncCallback callback, [System.Runtime.CompilerServices.Nullable(2)] object state)
{
ExceptionPolyfills.ThrowIfNull(task, "task");
return new TaskAsyncResult(task, state, callback);
}
public static void End(IAsyncResult asyncResult)
{
Unwrap(asyncResult).GetAwaiter().GetResult();
}
public static TResult End<[System.Runtime.CompilerServices.Nullable(2)] TResult>(IAsyncResult asyncResult)
{
return Unwrap<TResult>(asyncResult).GetAwaiter().GetResult();
}
public static Task Unwrap(IAsyncResult asyncResult)
{
ExceptionPolyfills.ThrowIfNull(asyncResult, "asyncResult");
Task obj = (asyncResult as TaskAsyncResult)?._task;
if (obj == null)
throw new ArgumentException(null, "asyncResult");
return obj;
}
public static Task<TResult> Unwrap<[System.Runtime.CompilerServices.Nullable(2)] TResult>(IAsyncResult asyncResult)
{
ExceptionPolyfills.ThrowIfNull(asyncResult, "asyncResult");
Task<TResult> obj = (asyncResult as TaskAsyncResult)?._task as Task<TResult>;
if (obj == null)
throw new ArgumentException(null, "asyncResult");
return obj;
}
}
}