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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
using System;
using System.Collections.Generic;
namespace ICSharpCode.NRefactory.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>
public static class BusyManager
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1815:OverrideEqualsAndOperatorEqualsOnValueTypes")]
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1034:NestedTypesShouldNotBeVisible",
Justification = "Should always be used with 'var'")]
public struct BusyLock : IDisposable
{
public static readonly BusyLock Failed = new BusyLock(null);
readonly List<object> objectList;
internal 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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