46c0ac68af
git-svn-id: file:///srv/devel/repo-conversion/nusu@33 d2e56fa2-650e-0410-a79f-9358c0239efd
85 lines
2.6 KiB
C#
85 lines
2.6 KiB
C#
#region CPL License
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/*
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Nuclex Framework
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Copyright (C) 2002-2007 Nuclex Development Labs
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This library is free software; you can redistribute it and/or
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modify it under the terms of the IBM Common Public License as
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published by the IBM Corporation; either version 1.0 of the
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License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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IBM Common Public License for more details.
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You should have received a copy of the IBM Common Public
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License along with this library
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*/
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#endregion
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using System;
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using System.Collections.Generic;
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using Nuclex.Support.Tracking;
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namespace Nuclex.Support.Scheduling {
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/// <summary>Base class for observable operations running in the background</summary>
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public abstract class Operation : Progression {
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/// <summary>Executes the operation synchronously</summary>
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public virtual void Execute() {
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Begin();
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End();
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}
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/// <summary>Launches the background operation</summary>
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public abstract void Begin();
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/// <summary>Waits for the background operation to end</summary>
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/// <remarks>
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/// Any exceptions raised in the background operation will be thrown
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/// in this method.
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/// </remarks>
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public virtual void End() {
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// Use some ingenious double-checked locking to set the endCalled flag.
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// Quite a lot of effort for a mere safety feature that prevents the programmer
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// from calling End() twice.
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bool error;
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if(!this.endCalled) {
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lock(this) {
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if(!this.endCalled) {
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this.endCalled = true;
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error = false;
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} else {
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error = true;
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}
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}
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} else {
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error = true;
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}
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// If the progression itself hasn't ended yet, block the caller until it has.
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if(!Ended)
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WaitHandle.WaitOne();
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// If an exception occured during the background execution
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if(this.occuredException != null)
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throw this.occuredException;
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}
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/// <summary>Exception that occured while the operation was executing</summary>
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/// <remarks>
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/// If this field is null, it is assumed that no exception has occured
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/// in the background process. When it is set, the End() method will
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/// </remarks>
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protected Exception occuredException;
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/// <summary>Whether the End() method has been called already</summary>
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private volatile bool endCalled;
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}
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} // namespace Nuclex.Support.Scheduling
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