public ClassEntry Search(uint cid)
{
//time consuming operations, that's the reason for cache
if (m_cid_cache.ContainsKey(cid))
{
ClassEntry t = (ClassEntry)m_cid_cache[cid];
t.BreakLinks();
t.BuildLinks(m_LRU, m_LRU.Next);
return(t);
}
else
{
//do the sequential search, :(
OOD.Imp.Storage.BTree.BTEnumerator bt = m_tree.GetEnumerator();
while (bt.MoveNext())
{
KCatalog key = (KCatalog)bt.Current;
Debug.Assert(key != null);
if (key.ClassInfo != null && key.ClassInfo.CId == cid)
{
//found
_put_in_cache(cid, key.ClassName, key.ClassInfo.FieldNames, key.ClassInfo.TopNodeSId);
return((ClassEntry)m_cid_cache[cid]);
}
}
return(null);
}
}
/// <summary>
/// Request a segment with size of length.
/// </summary>
/// <param name="length"></param>
/// <returns>True if succeed, otherwise false.</returns>
/// <preCondition></preCondition>
/// <PostCondition>A free segment will offset as the starting place and length as size
/// is cleared from this free space tree.</PostCondition>
public bool RequireSegment(int length, ref uint offset)
{
//do the sequential search
OOD.Imp.Storage.BTree.BTEnumerator enumerator = m_tree.GetEnumerator();
KOffset finding = null;
// while (enumerator.MoveNext())
// {
// KOffset temp = (KOffset)enumerator.Current;
// if (temp != null && temp.Length.Num >= length)
// {
// finding = temp;
// break;
// }
// }
if (finding == null)
{
//no free space find in the b-tree, create a new segment after the file end
offset = (uint)m_dbFile.Length;
m_dbFile.SetLength(offset + length);
}
else
{
//find new space in the tree
offset = finding.Offset;
int len = finding.Length.Num;
if (m_tree.Delete(finding) == false)
{
throw new OOD.Exception.ProgramLogicError(
this,
"Delete free space failed.");
}
if (finding.Length.Num > length)
{
//put the left back
finding.Offset = (uint)(offset + length);
finding.Length.Num = len - length;
if (m_tree.Insert(finding) == false)
{
throw new OOD.Exception.ProgramLogicError(
this,
"Insert free space failed.");
}
}
}
return(true);
}