private static bool TryBlockingAwait(Type awaitableType, object invocationResult, out object result)
{
// https://github.com/dotnet/csharplang/blob/master/spec/expressions.md#runtime-evaluation-of-await-expressions
var accessors = AwaitableApiAccessors.TryCreate(awaitableType);
if (accessors == null)
{
result = null;
return(false);
}
var awaiter = accessors.GetAwaiter(invocationResult);
if (!accessors.IsCompleted(awaiter))
{
using (var mres = new ManualResetEventSlim())
{
accessors.OnCompleted(awaiter, mres.Set);
mres.Wait();
}
}
result = accessors.GetResult(awaiter);
return(true);
}
/// <summary>
/// If a delegate is created by the end user, <see cref="IsAwaitable(Delegate)"/> must be used instead.
/// </summary>
public static bool IsAwaitable(MethodInfo methodWithoutEndUserDelegate)
{
if (methodWithoutEndUserDelegate == null)
{
throw new ArgumentNullException(nameof(methodWithoutEndUserDelegate));
}
// May be different from both @endUserDelegate.Method.ReturnType and invocationResult.GetType().
// Delegate return type is what we need to care about.
var awaitableType = methodWithoutEndUserDelegate.ReturnType;
return(AwaitableApiAccessors.TryCreate(awaitableType) != null);
}
/// <summary>
/// If a delegate is created by the end user, <see cref="IsAwaitable(Delegate)"/> must be used instead.
/// </summary>
public static Type GetAwaitableResultType(MethodInfo methodWithoutEndUserDelegate)
{
if (methodWithoutEndUserDelegate == null)
{
throw new ArgumentNullException(nameof(methodWithoutEndUserDelegate));
}
// May be different from both @endUserDelegate.Method.ReturnType and invocationResult.GetType().
// Delegate return type is what we need to care about.
var awaitableType = methodWithoutEndUserDelegate.ReturnType;
var accessors = AwaitableApiAccessors.TryCreate(awaitableType);
if (accessors == null)
{
throw new InvalidOperationException($"{awaitableType} is not awaitable.");
}
return(accessors.ResultType);
}
