Nuclex.Support/Source/Scheduling/Operation.cs
Markus Ewald acbb07d6b5 Some more unit tests; improved documentation; improve useless speed optimization of an exceptional case
git-svn-id: file:///srv/devel/repo-conversion/nusu@39 d2e56fa2-650e-0410-a79f-9358c0239efd
2007-07-12 22:16:11 +00:00

90 lines
3.3 KiB
C#

#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2007 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.Collections.Generic;
using Nuclex.Support.Tracking;
namespace Nuclex.Support.Scheduling {
/// <summary>Base class for observable operations running in the background</summary>
public abstract class Operation : Progression {
/// <summary>Launches the background operation</summary>
public abstract void Begin();
/// <summary>Waits for the background operation to end</summary>
/// <remarks>
/// Any exceptions raised in the background operation will be thrown
/// in this method. If you decide to override this method, you should
/// call End() first (and let any possible exception through to your
/// caller).
/// </remarks>
public virtual void End() {
// By design, end can only be called once!
lock(this) {
if(this.endCalled)
throw new InvalidOperationException("End() has already been called");
this.endCalled = true;
}
// If the progression itself hasn't ended yet, block the caller until it has.
if(!Ended)
WaitHandle.WaitOne();
// If an exception occured during the background execution
if(this.occuredException != null)
throw this.occuredException;
}
/// <summary>Exception that occured while the operation was executing</summary>
/// <remarks>
/// If this field is null, it is assumed that no exception has occured
/// in the background process. If it is set, however, the End() method will
/// re-raise the exception to the calling thread when it is called.
/// </remarks>
public Exception OccuredException {
get { return this.occuredException; }
}
/// <summary>Sets the exception to raise to the caller of the End() method</summary>
/// <param name="exception">Exception to raise to the caller of the End() method</param>
protected void SetException(Exception exception) {
// We allow the caller to set the exception multiple times. While I certainly
// can't think of a scenario where this would happen, throwing an exception
// in that case seems worse. The caller might just be executing an exception
// handling block and locking + throwing here could cause all kinds of problems.
this.occuredException = exception;
}
/// <summary>Exception that occured while the operation was executing</summary>
private volatile Exception occuredException;
/// <summary>Whether the End() method has been called already</summary>
private volatile bool endCalled;
}
} // namespace Nuclex.Support.Scheduling