private bool FindCycle(IDependencyVertex root, IDependencyVertex next, ref ArrayList members, ref Stack stack)
{
if (s_diagnostics_StackCheck)
{
if (stack.Contains(next))
{
string msg = "GraphSequencer has detected a dependency cycle in the initialization sequence of this model.\r\n";
IDependencyVertex thisDv = next;
int depct = 1;
foreach (IDependencyVertex idv in (object[])stack.ToArray())
{
msg += string.Format("{0}.) {1} depends on {2}.\r\n", (depct++), thisDv, idv);
thisDv = idv;
}
throw new ApplicationException(msg);
}
else
{
stack.Push(next);
}
}
foreach (IDependencyVertex parent in next.PredecessorList)
{
if (parent.Equals(root) || FindCycle(root, parent, ref members, ref stack))
{
members.Add(next);
return(true);
}
}
return(false);
}
/// <summary>
/// Call this with an IDependencyVertex object to add it to the sequencer
/// for consideration next time there is a request for a service sequence list.
/// </summary>
/// <param name="vertex">An IDependencyVertex object</param>
public void AddVertex(IDependencyVertex vertex)
{
m_serviceSequenceList = null;
if (m_vertices.Contains(vertex))
{
string msg = string.Format("Dependency sequencer error: Attempt to register a dependency vertex, {0}, that already exists in the list.",
vertex);
throw new ApplicationException(msg);
}
m_vertices.Add((IDependencyVertex)vertex);
}
/// <summary>
/// Recalculates the service sequence.
/// </summary>
protected void RecalculateServiceSequence()
{
m_serviceSequenceList = new ArrayList();
// First we create the list of vertex data and a hashtable to find
// the vertex from the underlying.
ArrayList lstVerts = new ArrayList();
Hashtable htVerts = new Hashtable();
//_Debug.WriteLine("Calculating Service Sequence.");
foreach (IDependencyVertex idv in m_vertices)
{
VertexRecord v = new VertexRecord(idv);
if (s_diagnostics)
{
_Debug.WriteLine("Parents of " + v.Underlying);
foreach (IDependencyVertex idv2 in v.Underlying.PredecessorList)
{
_Debug.WriteLine("\t" + idv2);
}
}
lstVerts.Add(v);
htVerts.Add(idv, v);
if (s_diagnostics)
{
_Debug.WriteLine(String.Format("New vertex, {0} with {1} dependents.", idv, idv.PredecessorList.Count));
}
}
// Each underlying knows who it depends on - we need each vertex to
// know, rather, who depends on IT.
foreach (VertexRecord v in lstVerts)
{
v.EstablishChildRelationships(htVerts);
}
try {
bool bResortNeeded = true;
int numAffectedLastAdjustment = lstVerts.Count;
// We will repeat the following until all nodes have been evaluated.
while (lstVerts.Count > 0)
{
//if ( lstVerts.Count%100 == 0 ) Console.WriteLine("%%%" + lstVerts.Count);
// Sort remaining vertices by the provided Comparer. (defaults to
// sorting first by nOrder, then by the vertices' provided comparator.
// See below for an explanation of the 'bResortNeeded' boolean.
if (bResortNeeded)
{
if (numAffectedLastAdjustment > lstVerts.Count * 0.02)
{
lstVerts.Sort(GetVertexComparer());
}
else
{
lstVerts = BubbleSort(lstVerts);
}
}
// Dumps the sort order as it progresses...
//foreach ( Vertex v in lstVerts ) _Debug.WriteLine(v.Underlying + " : " + v.Order);
// Move the least vertex to the ServiceOrder list.
VertexRecord next = (VertexRecord)lstVerts[0];
lstVerts.RemoveAt(0);
m_serviceSequenceList.Add(next.Underlying);
// If the vertex we just removed had no parents, then the sort order
// that was valid in the preceding step is still valid. Nobody had
// their child-count reduced, so no one's position in the sort will
// have had a reason to change. We just move on to the next one...
numAffectedLastAdjustment = next.Underlying.PredecessorList.Count;
bResortNeeded = (numAffectedLastAdjustment > 0);
if (next.Order != 0)
{
IDependencyVertex root = next.Underlying;
ArrayList members = new ArrayList();
members.Add(root);
Stack stack = new Stack();
foreach (IDependencyVertex parent in root.PredecessorList)
{
if (!FindCycle(root, parent, ref members, ref stack))
{
break;
}
}
throw new GraphCycleException(members);
}
// Decrement the Order of all vertices that this one depended on.
next.DecrementParentsChildCount(htVerts);
}
} catch (StackOverflowException soe) {
throw new ApplicationException("The GraphSequencer has detected a probable dependency cycle in the initialization sequence of this model. For details, set the GraphSequencer.StackCheck key to true in the modeler's app.config file.", soe);
}
#region Diagnostics
if (s_diagnostics)
{
_Debug.WriteLine("Dependency Solver determines sequence to be:");
foreach (IDependencyVertex idv in m_serviceSequenceList)
{
_Debug.WriteLine("\t" + idv);
}
}
#endregion Diagnostics
}
public VertexRecord(IDependencyVertex underlying)
{
m_underlying = underlying;
m_order = 0;
}
