private RedBlackNode <TKey, TValue> GetNodeForDelete(TKey key)
{
// begin at root
RedBlackNode <TKey, TValue> treeNode = _root;
// Hold a flag on root
if (!treeNode.OccupyNodeAtomically())
{
return(null);
}
// check if _root is locked
if (treeNode != _root)
{
treeNode.FreeNodeAtomically();
return(null);
}
var previousNode = treeNode;
// traverse tree until node is found
while (!treeNode.IsSentinel)
{
var result = key.CompareTo(treeNode.Key);
if (result == 0)
{
return(treeNode);
}
treeNode = result < 0 ? treeNode.Left : treeNode.Right;
// Hold a flag on new treenode
if (!treeNode.OccupyNodeAtomically())
{
previousNode.FreeNodeAtomically();
return(null);
}
// check if correct node is locked
if (treeNode != (result < 0 ? previousNode.Left : previousNode.Right))
{
previousNode.FreeNodeAtomically();
treeNode.FreeNodeAtomically();
return(null);
}
previousNode.FreeNodeAtomically();
previousNode = treeNode;
}
treeNode.FreeNodeAtomically();
return(null);
}
private bool GetFlagForMarker(
RedBlackNode <TKey, TValue> node,
RedBlackNode <TKey, TValue> prevNode,
List <RedBlackNode <TKey, TValue> > nodesToRelease,
Guid pid,
RedBlackNode <TKey, TValue> z = null)
{
if (z == null || z != node)
{
if (!IsIn(node, pid) && !node.OccupyNodeAtomically())
{
ReleaseFlags(pid, false, nodesToRelease);
return(false);
}
nodesToRelease.Add(node);
// verify parent is unchanged
if (node != prevNode.Parent)
{
ReleaseFlags(pid, false, nodesToRelease);
return(false);
}
}
return(true);
}
private void MoveLocalAreaUpwardForInsert(RedBlackNode <TKey, TValue> node, RedBlackNode <TKey, TValue>[] working, Guid pid)
{
while (true)
{
if (GetFlagsAndMarkersAbove(node, working, pid, 2))
{
break;
}
}
RedBlackNode <TKey, TValue> newParent = node.Parent, newGrandParent = node.Parent.Parent, newUncle = null;
while (true)
{
newUncle = newGrandParent.Left == node.Parent ? newGrandParent.Right : newGrandParent.Left;
if (!IsIn(newUncle, pid))
{
if (newUncle.OccupyNodeAtomically())
{
//check if uncle is not changed
var temp_uncle = newGrandParent.Left == node.Parent ? newGrandParent.Right : newGrandParent.Left;
if (newUncle != temp_uncle)
{
newUncle.FreeNodeAtomically();
}
else
{
break;
}
}
}
else
{
break;
}
}
// release flag on old local area
List <RedBlackNode <TKey, TValue> > nodesToRelease = new List <RedBlackNode <TKey, TValue> >();
nodesToRelease.Add(working[0]);
nodesToRelease.Add(working[1]);
nodesToRelease.Add(working[3]);
ReleaseFlags(pid, true, nodesToRelease);
working[0] = node;
working[1] = newParent;
working[2] = newGrandParent;
working[3] = newUncle;
}
private void FixUpCase1(
RedBlackNode <TKey, TValue>[] localArea,
Guid pid)
{
// correct relocated intention markers for other processes
if (localArea[2].Marker != Guid.Empty &&
localArea[3].Marker == localArea[2].Marker &&
localArea[1].Marker == Guid.Empty)
{
localArea[1].Marker = localArea[2].Marker;
localArea[2].Marker = Guid.Empty;
}
if (localArea[2].Marker != Guid.Empty &&
localArea[4].Marker == localArea[2].Marker &&
localArea[1].Marker == localArea[2].Marker)
{
Console.WriteLine("FixUpCase1: This should not happen!");
}
// Now correct local area and intention markers for the given process
// release highest held intention marker (fifth intention marker)
var intentionMarkers = new RedBlackNode <TKey, TValue> [4];
while (true)
{
if (GetFlagsForMarkers(localArea[2], pid, intentionMarkers, null))
{
break;
}
}
intentionMarkers[3].Marker = Guid.Empty;
ReleaseFlags(pid, false, intentionMarkers.ToList());
// release flag on node not "moved"
localArea[4].FreeNodeAtomically();
// acquire marker on old sibling of x and free the flag
localArea[2].Marker = pid;
localArea[2].FreeNodeAtomically();
RedBlackNode <TKey, TValue> neww = localArea[3];
RedBlackNode <TKey, TValue> newwl = neww.Left;
RedBlackNode <TKey, TValue> newwr = neww.Right;
if (!IsIn(newwl, pid))
{
while (true)
{
if (newwl.OccupyNodeAtomically())
{
break;
}
}
}
if (!IsIn(newwr, pid))
{
while (true)
{
if (newwr.OccupyNodeAtomically())
{
break;
}
}
}
localArea[2] = neww;
if (neww == localArea[1].Right)
{
localArea[3] = newwl;
localArea[4] = newwr;
}
else
{
localArea[3] = newwr;
localArea[4] = newwl;
}
}
private bool SpacingRuleIsSatisfied(
RedBlackNode <TKey, TValue> t,
Guid pid,
bool isParentOccupied,
RedBlackNode <TKey, TValue> z = null)
{
// we already hold flags on both t and z.
bool isMarkerAllowed = true;
// check that t has no marker set
if (z == null || z != t)
{
if (t.Marker != Guid.Empty)
{
return(false);
}
}
// check that t's parent has no flag or marker
RedBlackNode <TKey, TValue> tp = t.Parent;
if (z == null || z != tp)
{
if (!isParentOccupied)
{
if (!IsIn(tp, pid) && !tp.OccupyNodeAtomically())
{
return(false);
}
// verify parent is unchanged
if (tp != t.Parent)
{
tp.FreeNodeAtomically();
return(false);
}
}
if (tp.Marker != Guid.Empty)
{
if (!isParentOccupied)
{
tp.FreeNodeAtomically();
}
return(false);
}
}
//check that t's sibling has no flag or marker or PIDtoIgnore
var nodesToRelease = new List <RedBlackNode <TKey, TValue> >();
var ts = (t == tp.Left ? tp.Right : tp.Left);
if (!IsIn(ts, pid) && !ts.OccupyNodeAtomically())
{
if (z == null || z != tp)
{
if (!isParentOccupied)
{
nodesToRelease.Add(tp);
ReleaseFlags(pid, false, nodesToRelease);
}
}
return(false);
}
Guid PIDtoIgnore;
bool IsTooCloseProcess = getPIDtoIgnore(pid, out PIDtoIgnore);
if (ts.Marker != Guid.Empty && (!IsTooCloseProcess || ts.Marker != PIDtoIgnore))
{
isMarkerAllowed = false;
}
// release flags on ts and tp
nodesToRelease.Add(ts);
if (z == null || z != tp)
{
if (!isParentOccupied)
{
nodesToRelease.Add(tp);
}
}
ReleaseFlags(pid, false, nodesToRelease);
return(isMarkerAllowed);
}
private bool GetFlagsAndMarkersAbove(
RedBlackNode <TKey, TValue> start,
RedBlackNode <TKey, TValue>[] localArea,
Guid pid,
int numAdditional,
RedBlackNode <TKey, TValue> z = null)
{
var markerPositions = new RedBlackNode <TKey, TValue> [4];
if (!GetFlagsForMarkers(start, pid, markerPositions, z))
{
return(false);
}
if (numAdditional == 0)
{
bool IsSetMarkerSuccess = setMarker(markerPositions.ToList(), pid, z);
// release flags on four nodes after putting markers
ReleaseFlags(pid, false, markerPositions.ToList());
return(IsSetMarkerSuccess);
}
var nodesToRelease = new List <RedBlackNode <TKey, TValue> >();
// get additional marker(s) above
RedBlackNode <TKey, TValue> firstnew = markerPositions[3].Parent;
if (!IsIn(firstnew, pid) && !firstnew.OccupyNodeAtomically())
{
nodesToRelease.Add(markerPositions[0]);
nodesToRelease.Add(markerPositions[1]);
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
ReleaseFlags(pid, false, nodesToRelease.ToList());
return(false);
}
if (firstnew != markerPositions[3].Parent && !SpacingRuleIsSatisfied(firstnew, pid, false, null))
{
nodesToRelease.Add(markerPositions[0]);
nodesToRelease.Add(markerPositions[1]);
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
nodesToRelease.Add(firstnew);
ReleaseFlags(pid, false, nodesToRelease.ToList());
return(false);
}
if (numAdditional == 1)
{
firstnew.Marker = pid;
nodesToRelease.Add(markerPositions[1]);
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
nodesToRelease.Add(firstnew);
localArea[1] = markerPositions[0];
markerPositions[0].Marker = Guid.Empty;
ReleaseFlags(pid, true, nodesToRelease);
return(true);;
}
if (numAdditional == 2)
{
// get additional marker above
RedBlackNode <TKey, TValue> secondnew = firstnew.Parent;
if (!IsIn(secondnew, pid) && !secondnew.OccupyNodeAtomically())
{
nodesToRelease.Add(markerPositions[0]);
nodesToRelease.Add(markerPositions[1]);
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
nodesToRelease.Add(firstnew);
ReleaseFlags(pid, false, nodesToRelease.ToList());
return(false);
}
if (secondnew != firstnew.Parent && !SpacingRuleIsSatisfied(secondnew, pid, false, null))
{
nodesToRelease.Add(markerPositions[0]);
nodesToRelease.Add(markerPositions[1]);
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
nodesToRelease.Add(firstnew);
nodesToRelease.Add(secondnew);
ReleaseFlags(pid, false, nodesToRelease.ToList());
return(false);
}
firstnew.Marker = pid;
secondnew.Marker = pid;
nodesToRelease.Add(markerPositions[2]);
nodesToRelease.Add(markerPositions[3]);
nodesToRelease.Add(firstnew);
nodesToRelease.Add(secondnew);
markerPositions[0].Marker = Guid.Empty;
markerPositions[1].Marker = Guid.Empty;
ReleaseFlags(pid, true, nodesToRelease);
return(true);;
}
return(true);
}
private bool OccupyLocalAreaForInsert(RedBlackNode <TKey, TValue> node, RedBlackNode <TKey, TValue>[] localArea, Guid pid)
{
// occupy the node to be inserted
if (!node.OccupyNodeAtomically())
{
node.Parent.FreeNodeAtomically();
return(false);
}
var grandParent = node.Parent.Parent;
// occupy grandparent
if (!grandParent.OccupyNodeAtomically())
{
node.Parent.FreeNodeAtomically();
node.FreeNodeAtomically();
return(false);
}
// if grand parent changed before occupying, return false
if (grandParent != node.Parent.Parent)
{
// free grand parent
grandParent.FreeNodeAtomically();
node.Parent.FreeNodeAtomically();
node.FreeNodeAtomically();
return(false);
}
var uncle = grandParent.Left == node.Parent ? grandParent.Right : grandParent.Left;
if (!uncle.OccupyNodeAtomically())
{
grandParent.FreeNodeAtomically();
node.Parent.FreeNodeAtomically();
node.FreeNodeAtomically();
return(false);
}
//check if uncle is not changed
var temp_uncle = (grandParent.Left == node.Parent ? grandParent.Right : grandParent.Left);
if (uncle != temp_uncle)
{
uncle.FreeNodeAtomically();
grandParent.FreeNodeAtomically();
node.Parent.FreeNodeAtomically();
node.FreeNodeAtomically();
return(false);
}
localArea[0] = node;
localArea[1] = node.Parent;
localArea[2] = grandParent;
localArea[3] = uncle;
if (!GetFlagsAndMarkersAbove(grandParent, localArea, pid, 0))
{
uncle.FreeNodeAtomically();
grandParent.FreeNodeAtomically();
node.Parent.FreeNodeAtomically();
node.FreeNodeAtomically();
return(false);
}
return(true);
}
public RedBlackNode <TKey, TValue> Search(TKey key)
{
while (true)
{
if (_root == null)
{
break;
}
// begin at root
RedBlackNode <TKey, TValue> workNode = _root, nextNode = _root;
while (true)
{
if (!workNode.OccupyNodeAtomically())
{
continue;
}
int result = key.CompareTo(workNode.Key);
if (result == 0)
{
return(workNode);
}
if (result > 0)
{
nextNode = workNode.Right;
}
else
{
nextNode = workNode.Left;
}
if (nextNode.IsSentinel)
{
break;
}
if (!nextNode.OccupyNodeAtomically())
{
workNode.FreeNodeAtomically();
break;
}
if (nextNode.Parent != workNode)
{
workNode.FreeNodeAtomically();
nextNode.FreeNodeAtomically();
continue;
}
workNode.FreeNodeAtomically();
workNode = nextNode;
}
if (nextNode.IsSentinel)
{
break;
}
}
return(null);
}
private void Insert(RedBlackNode <TKey, TValue> newNode, RedBlackNode <TKey, TValue>[] localArea, Guid pid)
{
while (true)
{
if (_root == null)
{
if (!_dummy.OccupyNodeAtomically())
{
continue;
}
if (!_dummy.Left.IsSentinel)
{
_dummy.FreeNodeAtomically();
continue;
}
newNode.OccupyNodeAtomically();
// first node added
newNode.Parent = _dummy;
_dummy.Left = newNode;
_root = newNode;
break;
}
RedBlackNode <TKey, TValue> workNode = _root, nextNode = _root;
if (!workNode.OccupyNodeAtomically())
{
continue;
}
var isLocalAreaOccupied = false;
while (true)
{
newNode.Parent = workNode;
int result = newNode.Key.CompareTo(workNode.Key);
if (result == 0)
{
throw new Exception("duplicate key");
}
if (result > 0)
{
nextNode = workNode.Right;
}
else
{
nextNode = workNode.Left;
}
if (nextNode.IsSentinel)
{
isLocalAreaOccupied = OccupyLocalAreaForInsert(newNode, localArea, pid);
break;
}
if (!nextNode.OccupyNodeAtomically())
{
workNode.FreeNodeAtomically();
break;
}
if (nextNode.Parent != workNode)
{
workNode.FreeNodeAtomically();
nextNode.FreeNodeAtomically();
break;
}
workNode.FreeNodeAtomically();
workNode = nextNode;
}
if (isLocalAreaOccupied)
{
break;
}
}
// insert node into tree starting at parent's location
if (newNode != _root)
{
if (newNode.Key.CompareTo(newNode.Parent.Key) > 0)
{
newNode.Parent.Right = newNode;
}
else
{
newNode.Parent.Left = newNode;
}
}
}