private PriorityChain <T> GetChain(double priority)
{
PriorityChain <T> chain = null;
int count = this._priorityChains.Count;
if (count > 0)
{
if (priority == this._priorityChains.Keys[0])
{
chain = this._priorityChains.Values[0];
}
else if (priority == this._priorityChains.Keys[count - 1])
{
chain = this._priorityChains.Values[count - 1];
}
else if ((priority > this._priorityChains.Keys[0]) && (priority < this._priorityChains.Keys[count - 1]))
{
this._priorityChains.TryGetValue((int)priority, out chain);
}
}
if (chain == null)
{
if (this._cacheReusableChains.Count > 0)
{
chain = this._cacheReusableChains.Pop();
chain.Priority = priority;
}
else
{
chain = new PriorityChain <T>(priority);
}
this._priorityChains.Add((int)priority, chain);
}
return(chain);
}
public void ChangeItemPriority(PriorityItem <T> item, double priority)
{
this.RemoveItemFromPriorityChain(item);
PriorityChain <T> chain = this.GetChain(priority);
this.InsertItemInPriorityChain(item, chain);
}
public void RemoveItem(PriorityItem <T> item)
{
PriorityChain <T> chain = item.Chain;
this.RemoveItemFromPriorityChain(item);
this.RemoveItemFromSequentialChain(item);
}
internal void InsertItemInPriorityChain(PriorityItem <T> item, PriorityChain <T> chain, PriorityItem <T> after)
{
item.Chain = chain;
if (after == null)
{
if (chain.Head != null)
{
chain.Head.PriorityPrev = item;
item.PriorityNext = chain.Head;
chain.Head = item;
}
else
{
chain.Head = chain.Tail = item;
}
}
else
{
item.PriorityPrev = after;
if (after.PriorityNext != null)
{
item.PriorityNext = after.PriorityNext;
after.PriorityNext.PriorityPrev = item;
after.PriorityNext = item;
}
else
{
after.PriorityNext = item;
chain.Tail = item;
}
}
chain.Count++;
}
public PriorityItem <T> Enqueue(double priority, T data)
{
PriorityChain <T> chain = this.GetChain(priority);
PriorityItem <T> item = new PriorityItem <T>(data);
this.InsertItemInSequentialChain(item, this._tail);
this.InsertItemInPriorityChain(item, chain, chain.Tail);
return(item);
}
public T Peek()
{
T data = default(T);
int count = this._priorityChains.Count;
if (count > 0)
{
PriorityChain <T> chain = this._priorityChains.Values[count - 1];
data = chain.Head.Data;
}
return(data);
}
public T Dequeue()
{
int count = this._priorityChains.Count;
if (count <= 0)
{
throw new InvalidOperationException();
}
PriorityChain <T> chain = this._priorityChains.Values[count - 1];
PriorityItem <T> head = chain.Head;
this.RemoveItem(head);
return(head.Data);
}
private void InsertItemInPriorityChain(PriorityItem <T> item, PriorityChain <T> chain)
{
if (chain.Head == null)
{
this.InsertItemInPriorityChain(item, chain, null);
}
else
{
PriorityItem <T> after = null;
after = item.SequentialPrev;
while (after != null)
{
if (after.Chain == chain)
{
break;
}
after = after.SequentialPrev;
}
this.InsertItemInPriorityChain(item, chain, after);
}
}
private void RemoveItemFromPriorityChain(PriorityItem <T> item)
{
if (item.PriorityPrev != null)
{
item.PriorityPrev.PriorityNext = item.PriorityNext;
}
else
{
item.Chain.Head = item.PriorityNext;
}
if (item.PriorityNext != null)
{
item.PriorityNext.PriorityPrev = item.PriorityPrev;
}
else
{
item.Chain.Tail = item.PriorityPrev;
}
item.PriorityPrev = (PriorityItem <T>)(item.PriorityNext = null);
PriorityChain <T> chain = item.Chain;
chain.Count--;
if (item.Chain.Count == 0)
{
if (item.Chain.Priority == this._priorityChains.Keys[this._priorityChains.Count - 1])
{
this._priorityChains.RemoveAt(this._priorityChains.Count - 1);
}
else
{
this._priorityChains.Remove((int)item.Chain.Priority);
}
if (this._cacheReusableChains.Count < 10)
{
item.Chain.Priority = -1;//DispatcherPriority.Invalid;
this._cacheReusableChains.Push(item.Chain);
}
}
item.Chain = null;
}
