public bool Seek(Slice key)
{
if (_disposed)
{
throw new ObjectDisposedException("TreeIterator " + _tree.Name);
}
TreeNodeHeader * node;
Func <Slice, TreeCursor> constructor;
_currentPage = _tree.FindPageFor(key, node: out node, cursor: out constructor, allowCompressed: false);
_cursor = constructor(key);
_cursor.Pop();
if (node != null)
{
_prevKeyScope.Dispose();
_prevKeyScope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, node, out _currentInternalKey);
_currentKey = _currentInternalKey;
if (DoRequireValidation)
{
return(this.ValidateCurrentKey(_tx, Current));
}
return(true);
}
// The key is not found in the db, but we are Seek()ing for equals or starts with.
// We know that the exact value isn't there, but it is possible that the next page has values
// that is actually greater than the key, so we need to check it as well.
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries; // force next MoveNext to move to the next _page_.
return(MoveNext());
}
public bool MovePrev()
{
if (_disposed)
{
throw new ObjectDisposedException("TreeIterator " + _tree.Name);
}
while (true)
{
_currentPage.LastSearchPosition--;
if (_currentPage.LastSearchPosition >= 0)
{
// run out of entries, need to select the next page...
while (_currentPage.IsBranch)
{
// In here we will also have the 'current' page (even if we are traversing a compressed node).
if (_prefetch)
{
MaybePrefetchPagesReferencedBy(_currentPage);
}
_cursor.Push(_currentPage);
var node = _currentPage.GetNode(_currentPage.LastSearchPosition);
_currentPage = _tree.GetReadOnlyTreePage(node->PageNumber);
if (_currentPage.IsCompressed)
{
DecompressedCurrentPage();
}
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries - 1;
}
// We should be prefetching data pages down here.
if (_prefetch)
{
MaybePrefetchPagesReferencedBy(_currentPage);
}
var current = _currentPage.GetNode(_currentPage.LastSearchPosition);
if (DoRequireValidation && this.ValidateCurrentKey(_tx, current) == false)
{
return(false);
}
_prevKeyScope.Dispose();
_prevKeyScope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, current, out _currentInternalKey);
_currentKey = _currentInternalKey;
return(true);// there is another entry in this page
}
if (_cursor.PageCount == 0)
{
break;
}
_currentPage = _cursor.Pop();
}
_currentPage = null;
return(false);
}
public bool MovePrev()
{
if (_disposed)
{
throw new ObjectDisposedException("TreeIterator " + _tree.Name);
}
while (true)
{
_currentPage.LastSearchPosition--;
if (_currentPage.LastSearchPosition >= 0)
{
// run out of entries, need to select the next page...
while (_currentPage.IsBranch)
{
_cursor.Push(_currentPage);
var node = _currentPage.GetNode(_currentPage.LastSearchPosition);
_currentPage = _tree.GetReadOnlyTreePage(node->PageNumber);
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries - 1;
if (_prefetch && _currentPage.IsLeaf)
{
MaybePrefetchOverflowPages(_currentPage);
}
}
var current = _currentPage.GetNode(_currentPage.LastSearchPosition);
if (DoRequireValidation && this.ValidateCurrentKey(_tx, current) == false)
{
return(false);
}
_prevKeyScope.Dispose();
_prevKeyScope = TreeNodeHeader.ToSlicePtr(_tx.Allocator, current, out _currentInternalKey);
_currentKey = _currentInternalKey;
return(true);// there is another entry in this page
}
if (_cursor.PageCount == 0)
{
break;
}
_currentPage = _cursor.Pop();
}
_currentPage = null;
return(false);
}
public bool Seek(Slice key)
{
if (_disposed)
{
throw new ObjectDisposedException("PageIterator");
}
var current = _page.Search(_tx, key);
if (current == null)
{
return(false);
}
_prevScopeDispose.Dispose();
_prevScopeDispose = TreeNodeHeader.ToSlicePtr(_tx.Allocator, current, out _currentInternalKey);
_currentKey = _currentInternalKey;
if (DoRequireValidation)
{
return(this.ValidateCurrentKey(_tx, current));
}
return(true);
}
private bool TrySetPosition()
{
if (_disposed)
{
throw new ObjectDisposedException("PageIterator");
}
if (_page.LastSearchPosition < 0 || _page.LastSearchPosition >= _page.NumberOfEntries)
{
return(false);
}
var current = _page.GetNode(_page.LastSearchPosition);
if (DoRequireValidation && this.ValidateCurrentKey(_tx, current) == false)
{
return(false);
}
_prevScopeDispose.Dispose();
_prevScopeDispose = TreeNodeHeader.ToSlicePtr(_tx.Allocator, current, out _currentInternalKey);
_currentKey = _currentInternalKey;
return(true);
}
