/// <summary>
/// Pops the top access regulator from the stack associated with the specified resource, or from the
/// default stack if subject is set as null.
/// </summary>
/// <param name="subject">The resource to be regulated, or null if all are to be regulated.</param>
/// <returns>The AccessRegulator being popped, or null, if the stack was empty.</returns>
public IAccessRegulator PopAccessRegulator(IResource subject)
{
IAccessRegulator retval = null;
if (subject == null)
{
retval = (IAccessRegulator)m_defaultAccessRegulators.Pop();
if (m_defaultAccessRegulators.Count == 0 && m_autoDeleteEmptyStacks)
{
m_defaultAccessRegulators = null;
}
}
else
{
Stack stack = (Stack)m_monitoredObjects[subject];
if (stack != null)
{
retval = (IAccessRegulator)stack.Pop();
if (m_autoDeleteEmptyStacks && stack.Count == 0)
{
m_monitoredObjects.Remove(subject);
}
}
}
return(retval);
}
/// <summary>
/// Returns true if the given subject can be acquired using the presented key.
/// </summary>
/// <param name="subject">The resource whose acquisition is being queried.</param>
/// <param name="usingKey">The key that is to be presented by the prospective acquirer.</param>
/// <returns>True if the acquire will be allowed, false if not.</returns>
public bool CanAcquire(object subject, object usingKey)
{
Stack myStack = (Stack)m_monitoredObjects[subject];
if (myStack != null)
{
IAccessRegulator iar = (IAccessRegulator)myStack.Peek();
return(iar == null || iar.CanAcquire(subject, usingKey));
}
else
{
if (m_defaultAccessRegulators == null || m_defaultAccessRegulators.Count == 0)
{
return(true);
}
IAccessRegulator iar = (IAccessRegulator)m_defaultAccessRegulators.Peek();
return(iar.CanAcquire(subject, usingKey));
}
}
/// <summary>
/// Pushes an access regulator onto the stack that is associated with a particular resource, or
/// the default stack, if no resource is specified.
/// </summary>
/// <param name="accReg">Access Regulator to be pushed.</param>
/// <param name="subject">The resource to which this regulator is to apply, or null, if it applies to all of them.</param>
public void PushAccessRegulator(IAccessRegulator accReg, IResource subject)
{
if (subject == null)
{
if (m_defaultAccessRegulators == null)
{
m_defaultAccessRegulators = new Stack();
}
m_defaultAccessRegulators.Push(accReg);
}
else
{
Stack stack = (Stack)m_monitoredObjects[subject];
if (stack == null)
{
stack = new Stack();
m_monitoredObjects.Add(subject, stack);
}
stack.Push(accReg);
}
}
