115 lines
3.4 KiB
C#
115 lines
3.4 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="AsyncOperation.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.ComponentModel
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{
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using System.Security.Permissions;
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using System.Threading;
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[HostProtection(SharedState = true)]
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public sealed class AsyncOperation
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{
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private SynchronizationContext syncContext;
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private object userSuppliedState;
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private bool alreadyCompleted;
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/// <summary>
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/// Constructor. Protected to avoid unwitting usage - AsyncOperation objects
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/// are typically created by AsyncOperationManager calling CreateOperation.
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/// </summary>
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private AsyncOperation(object userSuppliedState, SynchronizationContext syncContext)
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{
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this.userSuppliedState = userSuppliedState;
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this.syncContext = syncContext;
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this.alreadyCompleted = false;
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this.syncContext.OperationStarted();
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}
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/// <summary>
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/// Destructor. Guarantees that [....] context will always get notified of completion.
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/// </summary>
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~AsyncOperation()
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{
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if (!alreadyCompleted && syncContext != null)
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{
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syncContext.OperationCompleted();
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}
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}
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public object UserSuppliedState
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{
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get { return userSuppliedState; }
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}
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/// <include file='doc\AsyncOperation.uex' path='docs/doc[@for="AsyncOperation.SynchronizationContext"]/*' />
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public SynchronizationContext SynchronizationContext
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{
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get
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{
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return syncContext;
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}
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}
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public void Post(SendOrPostCallback d, object arg)
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{
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VerifyNotCompleted();
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VerifyDelegateNotNull(d);
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syncContext.Post(d, arg);
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}
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public void PostOperationCompleted(SendOrPostCallback d, object arg)
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{
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Post(d, arg);
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OperationCompletedCore();
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}
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public void OperationCompleted()
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{
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VerifyNotCompleted();
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OperationCompletedCore();
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}
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private void OperationCompletedCore()
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{
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try
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{
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syncContext.OperationCompleted();
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}
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finally
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{
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alreadyCompleted = true;
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GC.SuppressFinalize(this);
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}
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}
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private void VerifyNotCompleted()
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{
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if (alreadyCompleted)
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{
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throw new InvalidOperationException(SR.GetString(SR.Async_OperationAlreadyCompleted));
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}
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}
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private void VerifyDelegateNotNull(SendOrPostCallback d)
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{
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if (d == null)
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{
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throw new ArgumentNullException(SR.GetString(SR.Async_NullDelegate), "d");
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}
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}
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/// <summary>
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/// Only for use by AsyncOperationManager to create new AsyncOperation objects
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/// </summary>
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internal static AsyncOperation CreateOperation(object userSuppliedState, SynchronizationContext syncContext)
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{
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AsyncOperation newOp = new AsyncOperation(userSuppliedState, syncContext);
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return newOp;
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}
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}
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}
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