private void MoveBranchNode(TreePage parentPage, TreePage from, TreePage to)
{
Debug.Assert(from.IsBranch);
Slice originalFromKey;
using (GetActualKey(from, from.LastSearchPositionOrLastEntry, out originalFromKey))
{
to.EnsureHasSpaceFor(_tx, originalFromKey, -1);
var fromNode = from.GetNode(from.LastSearchPosition);
long pageNum = fromNode->PageNumber;
if (to.LastSearchPosition == 0)
{
// cannot add to left implicit side, adjust by moving the left node
// to the right by one, then adding the new one as the left
TreeNodeHeader *actualKeyNode;
Slice implicitLeftKey;
using (GetActualKey(to, 0, out actualKeyNode, out implicitLeftKey))
{
var implicitLeftNode = to.GetNode(0);
var leftPageNumber = implicitLeftNode->PageNumber;
Slice implicitLeftKeyToInsert;
ByteStringContext.ExternalScope?externalScope;
if (implicitLeftNode == actualKeyNode)
{
externalScope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, actualKeyNode, out implicitLeftKeyToInsert);
}
else
{
implicitLeftKeyToInsert = implicitLeftKey;
externalScope = null;
}
to.EnsureHasSpaceFor(_tx, implicitLeftKeyToInsert, -1);
to.AddPageRefNode(1, implicitLeftKeyToInsert, leftPageNumber);
externalScope?.Dispose();
to.ChangeImplicitRefPageNode(pageNum); // setup the new implicit node
}
}
else
{
to.AddPageRefNode(to.LastSearchPosition, originalFromKey, pageNum);
}
}
if (from.LastSearchPositionOrLastEntry == 0)
{
var rightPageNumber = from.GetNode(1)->PageNumber;
from.RemoveNode(0); // remove the original implicit node
from.ChangeImplicitRefPageNode(rightPageNumber); // setup the new implicit node
Debug.Assert(from.NumberOfEntries >= 2);
}
else
{
from.RemoveNode(from.LastSearchPositionOrLastEntry);
}
var pos = parentPage.LastSearchPositionOrLastEntry;
parentPage.RemoveNode(pos);
Slice newSeparatorKey;
var scope = GetActualKey(to, 0, out newSeparatorKey); // get the next smallest key it has now
try
{
var pageNumber = to.PageNumber;
if (parentPage.GetNode(0)->PageNumber == to.PageNumber)
{
pageNumber = from.PageNumber;
scope.Dispose();
scope = GetActualKey(from, 0, out newSeparatorKey);
}
AddSeparatorToParentPage(to, parentPage, pageNumber, newSeparatorKey, pos);
}
finally
{
scope.Dispose();
}
}