/* Needed operations:
* 1. Given an offset and length, set that range to be free space.
* 2. Given an length, return the pair (offset, length) can be used.
* that range will be removed from free space tree before this
* operation returns.
*/
/// <summary>
/// Set the segment in the databse file to be free.
/// </summary>
/// <param name="offset"></param>
/// <param name="length"></param>
public void SetSegmentFree(uint offset, int length)
{
if (offset + length != m_dbFile.Length)
{
uint nextSeg = (uint)(offset + length);
KOffset target = new KOffset(nextSeg);
KOffset finding = (KOffset)m_tree.Search(target);
if (finding == null)
{
//combine to next segment is not possible, just go ahead to insert this one
target.Offset = offset;
target.Length = new DLength(length);
if (m_tree.Insert(target) == false)
{
throw new OOD.Exception.ProgramLogicError(
this,
"Insert into free space b-tree failed.");
}
}
else
{
//combine these two free segment into a big one
length += finding.Length.Num;
target.Length = new DLength(length);
target.Offset = offset;
if (m_tree.Delete(finding) == false || m_tree.Insert(target) == false)
{
throw new OOD.Exception.ProgramLogicError(
this,
"Delete free space failed.");
}
}
}
else
{
//this is the last segment in the database file, just remove it from the file
m_dbFile.SetLength(offset);
}
}
