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//------------------------------------------------------------------------------
// <copyright file="WorkItem.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Util {
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Threading;
//
// Support for positing of work items to a different thread
//
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
public delegate void WorkItemCallback();
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
public class WorkItem {
private static bool _useQueueUserWorkItem = true;
private static WaitCallback _onQueueUserWorkItemCompletion = new WaitCallback(OnQueueUserWorkItemCompletion);
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
[SecurityPermission(SecurityAction.Demand, Unrestricted=true)]
public static void Post(WorkItemCallback callback) {
#if !FEATURE_PAL // ROTORTODO
if (Environment.OSVersion.Platform != PlatformID.Win32NT)
throw new PlatformNotSupportedException(SR.GetString(SR.RequiresNT));
#else // !FEATURE_PAL
throw new NotImplementedException("ROTORTODO");
#endif // !FEATURE_PAL
PostInternal(callback);
}
// assert to disregard the user code up the compressed stack
[PermissionSet(SecurityAction.Assert, Unrestricted=true)]
private static void CallCallbackWithAssert(WorkItemCallback callback) {
callback();
}
private static void OnQueueUserWorkItemCompletion(Object state) {
WorkItemCallback callback = state as WorkItemCallback;
if (callback != null) {
CallCallbackWithAssert(callback);
}
}
internal static void PostInternal(WorkItemCallback callback) {
if (_useQueueUserWorkItem) {
ThreadPool.QueueUserWorkItem(_onQueueUserWorkItemCompletion, callback);
}
else {
WrappedWorkItemCallback w = new WrappedWorkItemCallback(callback);
w.Post();
}
}
}
internal class WrappedWorkItemCallback {
private GCHandle _rootedThis;
private WorkItemCallback _originalCallback;
private WorkItemCallback _wrapperCallback;
internal WrappedWorkItemCallback(WorkItemCallback callback) {
_originalCallback = callback;
_wrapperCallback = new WorkItemCallback(this.OnCallback);
}
internal void Post() {
_rootedThis = GCHandle.Alloc(this);
if (UnsafeNativeMethods.PostThreadPoolWorkItem(_wrapperCallback) != 1) {
_rootedThis.Free();
throw new HttpException(SR.GetString(SR.Cannot_post_workitem));
}
}
private void OnCallback() {
_rootedThis.Free();
_originalCallback();
}
}
}
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