/// <summary>
/// Deletes the given element from priority queue.
/// </summary>
/// <param name="queueElement">Element to be deleted. </param>
public void DeleteElement(QueueElement queueElement)
{
Trace.Indent();
// Increase the timestamp to max possible value.
IncreaseTimestamp(queueElement, DateTime.MaxValue);
Trace.WriteLine("Whiteboard.BoardPriorityQueue.DeleteElement: Timestamp for element increased to MAX");
// extract out max value (highest timestamp)
Extract();
Trace.WriteLine("Whiteboard.BoardPriorityQueue.DeleteElement: Element extracted out.");
Trace.Unindent();
}
/// <summary>
/// Inserts the element in the priority queue.
/// </summary>
/// <param name="queueElement">Element to be inserted.</param>
public void Insert(QueueElement queueElement)
{
Trace.Indent();
// update the index of the queue element
var lastIndex = GetSize();
queueElement.Index = lastIndex;
// adding the element in queue and placing it at right position.
_queue.Add(queueElement);
while (lastIndex != 0 && _queue[Parent(lastIndex)].Timestamp < _queue[lastIndex].Timestamp)
{
SwapElements(lastIndex, Parent(lastIndex));
lastIndex = Parent(lastIndex);
}
Trace.WriteLine("Whiteboard.BoardPriorityQueue.Insert: Inserted the element successfully.");
Trace.Unindent();
}
/// <summary>
/// Increases the timestamp of given queue element and place it at appropriate position in priority queue.
/// </summary>
/// <param name="queueElement">Element to be updated. </param>
/// <param name="dateTime">The new date-time value. </param>
public void IncreaseTimestamp(QueueElement queueElement, DateTime dateTime)
{
Trace.Indent();
var index = queueElement.Index;
// if index is out of range
if (index < 0 || index >= GetSize())
{
Trace.WriteLine("Whiteboard.BoardPriorityQueue.IncreaseTimestamp: Index out of range.");
throw new IndexOutOfRangeException("Element index in the queue. IncreaseTimestamp failed.");
}
// update timestamp and place the element at correct position.
queueElement.Timestamp = dateTime;
while (index != 0 && _queue[Parent(index)].Timestamp < _queue[index].Timestamp)
{
SwapElements(index, Parent(index));
index = Parent(index);
}
Trace.WriteLine(
"Whiteboard.BoardPriorityQueue.IncreaseTimestamp: Increased timestamp and moved to new suitable position.");
Trace.Unindent();
}
/// <summary>
/// Updates local state on Fetch State from server.
/// </summary>
/// <param name="boardServerShape">BoardServerShape object having the whole update.</param>
/// <returns>List of UXShape to notify client.</returns>
private List <UXShape> UpdateStateOnFetch(BoardServerShape boardServerShape)
{
try
{
var boardShapes = boardServerShape.ShapeUpdates;
List <UXShape> uXShapes = new();
// Sorting boardShapes
boardShapes.Sort(delegate(BoardShape boardShape1, BoardShape boardShape2)
{
return(boardShape1.LastModifiedTime.CompareTo(boardShape2.LastModifiedTime));
});
// updating checkpoint number
_checkpointsNumber = boardServerShape.CheckpointNumber;
_clientCheckPointHandler.CheckpointNumber = _checkpointsNumber;
// updating state
for (var i = 0; i < boardShapes.Count; i++)
{
var boardShapeId = boardShapes[i].Uid;
// insert in id to BoardShape map
if (_mapIdToBoardShape.ContainsKey(boardShapeId))
{
// if already there is some reference present, removing it
_mapIdToBoardShape.Remove(boardShapeId);
GC.Collect();
}
_mapIdToBoardShape.Add(boardShapeId, boardShapes[i]);
// insert in priority queue and id to QueueElement map
var queueElement = new QueueElement(boardShapeId, boardShapes[i].LastModifiedTime);
if (_mapIdToQueueElement.ContainsKey(boardShapeId))
{
// if already there is some reference present, removing it
var tempQueueElement = _mapIdToQueueElement[boardShapeId];
_priorityQueue.DeleteElement(tempQueueElement);
_mapIdToQueueElement.Remove(boardShapeId);
GC.Collect();
}
_mapIdToQueueElement.Add(boardShapeId, queueElement);
_priorityQueue.Insert(queueElement);
// converting BoardShape to UXShape and adding it in the list
uXShapes.Add(new UXShape(UXOperation.CREATE, boardShapes[i].MainShapeDefiner, boardShapeId,
_checkpointsNumber, boardServerShape.OperationFlag));
}
return(uXShapes);
}
catch (Exception e)
{
Trace.WriteLine("ClientBoardStateManager.UpdateStateOnFetch: Exception occurred.");
Trace.WriteLine(e.Message);
}
return(null);
}