/// <summary>
/// Adds an error indicating that this element represents the start of a cycle. Cycles will be detected
/// by the first recurring element in a path.
/// </summary>
/// <param name="element">The element that has just been added to the current depth path.</param>
private void LogError(object element)
{
#region Create & add an error.
if (s_diagnostics)
{
for (int i = 0; i < m_level; i++)
{
Console.Write(" ");
}
Console.WriteLine(">>>>>>>>>>>> Element " + element + " represents the start of a cycle.");
}
ArrayList elements = new ArrayList();
ArrayList pathObjArray = new ArrayList(m_currentPath.ToArray());
string narrative = "Cycle detected - elements are : ";
int startOfLoop = pathObjArray.IndexOf(element);
for (int i = startOfLoop; i >= 0; i--)
{
object elementInPath = pathObjArray[i];
elements.Add(elementInPath);
narrative += elementInPath.ToString();
if (i > 1)
{
narrative += ", ";
}
else if (i == 1)
{
narrative += " and ";
}
}
DagStructureError se = new DagStructureError(m_rootEdge, elements, narrative);
m_errors.Add(se);
#endregion
}
/// <summary>
/// Forces this DAGDeadlockChecker to validate the entire DAG by checking for deadlocks.
/// </summary>
/// <returns>True if the DAGDeadlockChecker found no errors.</returns>
public virtual bool Check()
{
m_errors = new ArrayList();
m_nodes = new Hashtable();
m_frontier = new ArrayList();
Build(m_rootEdge.PreVertex);
m_frontier.Add(m_nodes[m_rootEdge.PreVertex]);
while (Advance())
{
if (s_diagnostics)
{
Console.WriteLine("There are " + m_frontier.Count + " nodes on the frontier.");
}
}
if (m_frontier.Count > 0)
{
ArrayList removees = new ArrayList();
foreach (Node n in m_frontier)
{
foreach (Node pred in AnyPredecessorsOf(n))
{
if (m_frontier.Contains(pred))
{
if (!removees.Contains(n))
{
//Console.WriteLine("Removing " + n.Name + " because " + pred.Name + " is also on the frontier.");
removees.Add(n);
break;
}
}
}
}
foreach (Node r in removees)
{
m_frontier.Remove(r);
}
ArrayList targets = new ArrayList();
foreach (Node n in m_frontier)
{
targets.Add(n.Element);
}
DagStructureError dse = new DagStructureError(m_rootEdge, targets, "A deadlock was detected in the graph.");
m_errors.Add(dse);
}
return(m_errors.Count == 0);
}