/// <summary>
/// Creates a union stream reader from the supplied data.
/// </summary>
/// <param name="streams">all of the tables to combine in the union</param>
/// <param name="ownsStream">if this class owns the streams, it will call dispose when <see cref="Dispose"/> is called.
/// Otherwise, the streams will not be disposed.</param>
public UnionTreeStream(IEnumerable <TreeStream <TKey, TValue> > streams, bool ownsStream)
{
m_firstStream = null;
m_ownsStreams = ownsStream;
m_tablesOrigList = streams.Select(x => new BufferedTreeStream(x)).ToArray();
m_sortedArchiveStreams = new UnionTreeStreamSortHelper(m_tablesOrigList);
m_readWhileUpperBounds.SetMin();
foreach (var table1 in m_sortedArchiveStreams.Items)
{
table1.EnsureCache();
}
m_sortedArchiveStreams.Sort();
//Remove any duplicates
RemoveDuplicatesIfExists();
if (m_sortedArchiveStreams.Items.Length > 0)
{
m_firstTable = m_sortedArchiveStreams[0];
}
else
{
m_firstTable = null;
}
SetReadWhileUpperBoundsValue();
}
/// <summary>
/// Resorts the entire list. Uses an insertion sort routine
/// </summary>
public void Sort()
{
//A insertion sort routine.
//Skip first item in list since it will always be sorted correctly
for (int itemToInsertIndex = 1; itemToInsertIndex < m_validRecords; itemToInsertIndex++)
{
BufferedTreeStream itemToInsert = Items[itemToInsertIndex];
int currentIndex = itemToInsertIndex - 1;
//While the current item is greater than itemToInsert, shift the value
while ((currentIndex >= 0) && (IsLessThan(itemToInsert, Items[currentIndex])))
{
Items[currentIndex + 1] = Items[currentIndex];
currentIndex--;
}
Items[currentIndex + 1] = itemToInsert;
}
for (int x = m_validRecords - 1; x >= 0; x--)
{
if (Items[x].IsValid)
{
m_validRecords = x + 1;
break;
}
if (x == 0)
{
m_validRecords = 0;
}
}
}
/// <summary>
/// Resorts only the item at the specified index assuming:
/// 1) all other items are properly sorted
/// 2) this items's value increased.
/// </summary>
/// <param name="index">the index of the item to resort.</param>
public void SortAssumingIncreased(int index)
{
BufferedTreeStream itemToMove = Items[index];
if (!itemToMove.IsValid)
{
m_validRecords--;
for (int x = index; x < m_validRecords; x++)
{
Items[x] = Items[x + 1];
}
Items[m_validRecords] = itemToMove;
return;
}
//ToDo: Consider an exponential search algorithm.
int currentIndex = index + 1;
while (currentIndex < m_validRecords && Items[currentIndex].CacheKey.IsLessThan(itemToMove.CacheKey))
{
Items[currentIndex - 1] = Items[currentIndex];
currentIndex++;
}
Items[currentIndex - 1] = itemToMove;
}
//-------------------------------------------------------------
/// <summary>
/// Compares two Archive Streams together for proper sorting.
/// </summary>
/// <param name="item1"></param>
/// <param name="item2"></param>
/// <returns></returns>
private int CompareStreams(BufferedTreeStream item1, BufferedTreeStream item2)
{
if (!item1.IsValid && !item2.IsValid)
{
return(0);
}
if (!item1.IsValid)
{
return(1);
}
if (!item2.IsValid)
{
return(-1);
}
return(item1.CacheKey.CompareTo(item2.CacheKey));// item1.CurrentKey.CompareTo(item2.CurrentKey);
}
private bool IsLessThan(BufferedTreeStream item1, BufferedTreeStream item2)
{
if (!item1.IsValid && !item2.IsValid)
{
return(false);
}
if (!item1.IsValid)
{
return(false);
}
if (!item2.IsValid)
{
return(true);
}
return(item1.CacheKey.IsLessThan(item2.CacheKey));// item1.CurrentKey.CompareTo(item2.CurrentKey);
}
private bool Read2(TKey key, TValue value)
{
TryAgain:
if (m_firstStream == null)
{
//If m_firstStream == null, this means either:
// the value is cached.
// or
// the end of the stream has occured.
if (m_firstTable != null && m_firstTable.IsValid)
{
//The value is cached.
m_firstTable.Read(key, value);
m_firstStream = m_firstTable.Stream;
return(true);
}
//The end of the steam has been reached.
return(false);
}
//Condition 1:
// The archive stream may no longer be in order and needs to be checked
//Response:
// Resort the archive stream
//
//Condition 2:
// The end of the frame has been reached
//Response:
// Advance to the next frame
// Also test the edge case where the current point might be equal to the end of the frame
// since this is an inclusive filter and ReadWhile is exclusive.
// If it's part of the frame, return true after Advancing the frame and the point.
//
//Since condition 1 and 2 can occur at the same time, verifying the sort of the Archive Stream is a good thing to do.
// Will verify that the stream is in the proper order and remove any duplicates that were found.
// May be called after every single read, but better to be called
// when a ReadWhile function returns false.
if (m_sortedArchiveStreams.Items.Length > 1)
{
//If list is no longer in order
int compare = CompareStreams(m_sortedArchiveStreams[0], m_sortedArchiveStreams[1]);
if (compare == 0) //A duplicate value was found.
{
//If a duplicate entry is found, advance the position of the duplicate entry
RemoveDuplicatesFromList();
SetReadWhileUpperBoundsValue();
m_firstTable = m_sortedArchiveStreams[0];
}
else if (compare > 0) //List is out of order
{
m_sortedArchiveStreams.SortAssumingIncreased(0);
m_firstTable = m_sortedArchiveStreams[0];
SetReadWhileUpperBoundsValue();
}
}
else
{
//If only 1 stream, we can't resort, so we are done.
if (!m_sortedArchiveStreams[0].IsValid)
{
return(false);
}
}
m_firstStream = null; //Ensure that the if block is executed when repeating this function call.
goto TryAgain;
}
