Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WCF / Log / System / IO / Log / OverlappedAsyncResult.cs / 1305376 / OverlappedAsyncResult.cs
//------------------------------------------------------------------------------ // Copyright (c) Microsoft Corporation. All rights reserved. //----------------------------------------------------------------------------- namespace System.IO.Log { using System; using System.Diagnostics; using System.Runtime; using System.Runtime.InteropServices; using System.Security.Permissions; using System.Threading; using System.ServiceModel.Diagnostics; using Microsoft.Win32.SafeHandles; // How to use: // 1. Subclass, implement IOCompleted. // 2. Call Pack() each time before invoking native method. // 3. Use NativeOverlapped pointer in native method // 4. If call completes synchronously, Free() immediately // 5. If call completes asynchronously, Free() is called for you // unsafe abstract class OverlappedAsyncResult : IAsyncResult { // Boring stuff needed to implement IAsyncResult // correctly. // object userState; AsyncCallback callback; ManualResetEvent waitHandle; object syncRoot; bool isCompleted; bool completedSynchronously; bool endCalled; Exception storedException; // More exciting stuff... // NativeOverlapped* nativeOverlapped; protected OverlappedAsyncResult(AsyncCallback callback, object state) { this.callback = callback; this.userState = state; this.syncRoot = new Object(); GC.SuppressFinalize(this); } ~OverlappedAsyncResult() { // Avoid leaking the NativeOverlapped in case things go wrong if (!Environment.HasShutdownStarted && !AppDomain.CurrentDomain.IsFinalizingForUnload()) { Free(); } } public Object AsyncState { get { return this.userState; } } public WaitHandle AsyncWaitHandle { get { lock (this.syncRoot) { if (this.waitHandle == null) { this.waitHandle = new ManualResetEvent(this.isCompleted); } } return this.waitHandle; } } public bool CompletedSynchronously { get { return this.completedSynchronously; } } public bool IsCompleted { get { return this.isCompleted; } } internal NativeOverlapped *NativeOverlapped { get { return this.nativeOverlapped; } } internal void Complete(bool completedSynchronously, Exception exception) { lock (this.syncRoot) { this.storedException = exception; this.completedSynchronously = completedSynchronously; this.isCompleted = true; if (this.waitHandle != null) this.waitHandle.Set(); Monitor.PulseAll(this.syncRoot); } if (this.callback != null) { if (!completedSynchronously || !ThreadPool.QueueUserWorkItem(InvokeUserCallback, this)) { InvokeUserCallbackFunction(this); } } } public void End() { lock (this.syncRoot) { while (!this.IsCompleted) { Monitor.Wait(this.syncRoot); } if (this.endCalled) throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(Error.DuplicateEnd()); this.endCalled = true; if (this.storedException != null) { throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(this.storedException); } } } internal void Free() { if (this.nativeOverlapped != null) { GC.SuppressFinalize(this); Overlapped.Free(this.nativeOverlapped); this.nativeOverlapped = null; } } internal void Pack(object pinnedObjects) { if (this.nativeOverlapped != null) { // If we reach this condition, we have a bug in a derived AsyncResult class. // It attempted to initiate a new async I/O operation before the previous // one completed. This is a fatal condition, so we cannot continue execution. DiagnosticUtility.FailFast("Must allow previous I/O to complete before packing"); } GC.ReRegisterForFinalize(this); Overlapped overlapped = new Overlapped(0, 0, IntPtr.Zero, this); if (this.callback == null) { this.nativeOverlapped = overlapped.UnsafePack( IOCompletionCallback, pinnedObjects); } else { this.nativeOverlapped = overlapped.Pack( IOCompletionCallback, pinnedObjects); } } internal abstract void IOCompleted(uint errorCode); static IOCompletionCallback IOCompletionCallback = Fx.ThunkCallback(new IOCompletionCallback(CompletionCallback)); static void CompletionCallback(uint errorCode, uint numBytes, NativeOverlapped* nativeOverlapped) { try { Overlapped overlapped = Overlapped.Unpack(nativeOverlapped); OverlappedAsyncResult result; result = (OverlappedAsyncResult)overlapped.AsyncResult; result.Free(); result.IOCompleted(errorCode); } #pragma warning suppress 56500 // We will be terminating the process with any exception in this call catch(Exception e) { // The code in the try block should not throw any exceptions. // If an exception is caught here, IO.Log may be in an unknown state. // We prefer to failfast instead of risking the possibility of log corruption. // Any client code using IO.Log must have a recovery model that can deal // with appdomain and process failures. DiagnosticUtility.InvokeFinalHandler(e); } } static WaitCallback InvokeUserCallback = Fx.ThunkCallback(new WaitCallback(InvokeUserCallbackFunction)); static void InvokeUserCallbackFunction( object data) { try { OverlappedAsyncResult result = (OverlappedAsyncResult)data; result.callback(result); } #pragma warning suppress 56500 // We will be terminating the process with any exception in this call catch(Exception e) { if (Fx.IsFatal(e)) throw; throw DiagnosticUtility.ExceptionUtility.ThrowHelperCallback(e); } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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