void PerformMerge(GLPoolResourceNode left, GLPoolResourceTicket ticket, GLPoolResourceNode right)
{
bool leftMerge = left != null && (ticket.First == (left.Last + 1));
bool rightMerge = right != null && ((ticket.Last + 1) == right.First);
ValidateTicket(ticket);
ValidateLocation(left, ticket, right);
if (leftMerge && rightMerge)
{
Debug.Assert(ReferenceEquals(left.Next, right));
var finalCount = left.Count + ticket.Count + right.Count;
Debug.Assert(finalCount == (right.Last - left.First + 1));
left.Count = finalCount;
left.Last = right.Last;
left.Next = right.Next;
}
else if (leftMerge)
{
var finalCount = left.Count + ticket.Count;
Debug.Assert(finalCount == (ticket.Last - left.First + 1));
left.Count = finalCount;
left.Last = ticket.Last;
}
else if (rightMerge)
{
var finalCount = right.Count + ticket.Count;
Debug.Assert(finalCount == (right.Last - ticket.First + 1));
right.Count = finalCount;
right.First = ticket.First;
}
else
{
var inBetween = new GLPoolResourceNode
{
First = ticket.First,
Last = ticket.Last,
Count = ticket.Count,
};
// REPLACE HEAD
if (left == null)
{
Debug.Assert(ReferenceEquals(right, Head));
inBetween.Next = Head;
Head = inBetween;
}
else
{
left.Next = inBetween;
inBetween.Next = right;
}
}
}
public bool Free(GLPoolResourceTicket ticket)
{
// only tickets from same pool resource
// CAN MOVE THIS OUT
//if (!ReferenceEquals(this, parent))
// return false;
// TODO? : spamming same ticket should have no effect (maybe)
if (Head == null)
{
Head = new GLPoolResourceNode
{
First = ticket.First,
Last = ticket.Last,
Count = ticket.Count,
};
return(true);
}
else
{
GLPoolResourceNode previous = null;
GLPoolResourceNode current = Head;
while (current != null)
{
// SAME TICKET RANGE RECOVERY
if (ticket.First == current.First)
{
// DO NOTHING IF INSIDE RANGE
if (ticket.Last <= current.Last && ticket.Count <= current.Count)
{
return(true);
}
else
{
AdjustTicketsSpan(ticket, current);
return(true);
}
}
// GAP-BASED SLOT RECOVERY
else if (ticket.First < current.First)
{
PerformMerge(previous, ticket, current);
return(true);
}
previous = current;
current = current.Next;
}
// At end of linked list
PerformMerge(previous, ticket, null);
return(true);
}
}
void ValidateLocation(GLPoolResourceNode previous, GLPoolResourceTicket ticket, GLPoolResourceNode current)
{
if (previous != null && previous.Last >= ticket.First)
{
throw new InvalidOperationException();
}
if (current != null && current.First <= ticket.Last)
{
throw new InvalidOperationException();
}
}
void ValidateTicket(GLPoolResourceTicket ticket)
{
if ((ticket.First + ticket.Count) > Count)
{
throw new InvalidOperationException();
}
if (ticket.Count == 0)
{
throw new InvalidOperationException();
}
if ((ticket.First + ticket.Count - 1) != ticket.Last)
{
throw new InvalidOperationException();
}
if (ticket.Last > Count)
{
throw new InvalidOperationException();
}
}
void AdjustTicketsSpan(GLPoolResourceTicket ticket, GLPoolResourceNode parent)
{
GLPoolResourceNode lastNode = null;
bool intercepts = false;
GLPoolResourceNode current = parent.Next;
while (current != null)
{
lastNode = current;
if (current.Last > ticket.Last)
{
intercepts = (current.First <= ticket.Last);
break;
}
// remove from the list
parent.Next = current.Next;
current = current.Next;
}
parent.Last = (lastNode != null && intercepts) ? lastNode.Last : ticket.Last;
parent.Count = parent.Last - parent.First + 1;
if (current == null)
{
// ITERATED THRU THEN POINT TO END
parent.Next = null;
}
else if (lastNode != null && intercepts)
{
// INCLUDE LAST NODE
parent.Next = lastNode.Next;
}
else
{
// OUTSIDE OF LAST NODE
parent.Next = lastNode;
}
}
public bool Allocate(uint request, out GLPoolResourceTicket range)
{
if (request == 0)
{
throw new ArgumentOutOfRangeException(nameof(request) + " must be greater than 0");
}
{
// FIRST LOOP : SCAN FOR EXACT MATCHES
GLPoolResourceNode current = Head;
GLPoolResourceNode previous = null;
while (current != null)
{
if (current.Count == request)
{
range = new GLPoolResourceTicket
{
First = current.First,
Last = current.Last,
Count = current.Count,
};
// remove current from linked list
if (previous != null)
{
previous.Next = current.Next;
}
// remove from head
if (ReferenceEquals(Head, current))
{
Head = current.Next;
}
return(true);
}
previous = current;
current = current.Next;
}
}
{
// SECOND LOOP : FIND FIRST BLOCK LARGE ENOUGH AND SPLIT
GLPoolResourceNode current = Head;
while (current != null)
{
if (current.Count > request)
{
range = new GLPoolResourceTicket
{
First = current.First,
Last = request + current.First - 1,
Count = request,
};
// adjust current
current.First += request;
current.Count -= request;
return(true);
}
current = current.Next;
}
}
// NOT FOUND
range = null;
return(false);
}