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//------------------------------------------------------------------------------
// <copyright file="WithinCancellableCallbackTaskAwaitable.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Util {
using System;
using System.Runtime.CompilerServices;
using System.Security.Permissions;
using System.Threading;
using System.Threading.Tasks;
// An awaitable type that invokes a continuation callback under a call to HttpContext.InvokeCancellableCallback.
// This type is for compiler use; the ASP.NET runtime is not expected to call into these APIs directly.
internal struct WithinCancellableCallbackTaskAwaitable {
internal static readonly WithinCancellableCallbackTaskAwaitable Completed = new WithinCancellableCallbackTaskAwaitable(null, ((Task)Task.FromResult((object)null)).GetAwaiter());
private readonly WithinCancellableCallbackTaskAwaiter _awaiter;
public WithinCancellableCallbackTaskAwaitable(HttpContext context, TaskAwaiter innerAwaiter) {
_awaiter = new WithinCancellableCallbackTaskAwaiter(context, innerAwaiter);
}
public WithinCancellableCallbackTaskAwaiter GetAwaiter() {
return _awaiter;
}
// The awaiter type that backs WithinCancellableCallbackTaskAwaitable.
internal struct WithinCancellableCallbackTaskAwaiter : ICriticalNotifyCompletion {
private static readonly WaitCallback _shunt = state => ((Action)state)();
private readonly HttpContext _context;
private readonly TaskAwaiter _innerAwaiter;
internal WithinCancellableCallbackTaskAwaiter(HttpContext context, TaskAwaiter innerAwaiter) {
_context = context;
_innerAwaiter = innerAwaiter;
}
public bool IsCompleted {
get { return _innerAwaiter.IsCompleted; }
}
public void GetResult() {
_innerAwaiter.GetResult();
// If Response.End was called, need to observe it here.
HttpContext context = _context;
if (context != null) {
context.Response.ObserveResponseEndCalled();
}
}
public void OnCompleted(Action continuation) {
Action wrappedContinuation = WrapContinuation(continuation);
_innerAwaiter.OnCompleted(wrappedContinuation);
}
[SecurityPermission(SecurityAction.LinkDemand, Unrestricted = true)] // equivalent of [SecurityCritical]
public void UnsafeOnCompleted(Action continuation) {
Action wrappedContinuation = WrapContinuation(continuation);
_innerAwaiter.UnsafeOnCompleted(wrappedContinuation);
}
private Action WrapContinuation(Action continuation) {
HttpContext context = _context;
return (context != null)
? () => context.InvokeCancellableCallback(_shunt, continuation)
: continuation;
}
}
}
}
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