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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
using System;
using System.Collections.Generic;
namespace Tango.Scripting.Editors.Utils
{
/// <summary>
/// This class is used to prevent stack overflows by representing a 'busy' flag
/// that prevents reentrance when another call is running.
/// However, using a simple 'bool busy' is not thread-safe, so we use a
/// thread-static BusyManager.
/// </summary>
static class BusyManager
{
public struct BusyLock : IDisposable
{
public static readonly BusyLock Failed = new BusyLock(null);
readonly List<object> objectList;
public BusyLock(List<object> objectList)
{
this.objectList = objectList;
}
public bool Success {
get { return objectList != null; }
}
public void Dispose()
{
if (objectList != null) {
objectList.RemoveAt(objectList.Count - 1);
}
}
}
[ThreadStatic] static List<object> _activeObjects;
public static BusyLock Enter(object obj)
{
List<object> activeObjects = _activeObjects;
if (activeObjects == null)
activeObjects = _activeObjects = new List<object>();
for (int i = 0; i < activeObjects.Count; i++) {
if (activeObjects[i] == obj)
return BusyLock.Failed;
}
activeObjects.Add(obj);
return new BusyLock(activeObjects);
}
}
}
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