private bool TryMergePages(Page parentPage, Page left, Page right)
{
TemporaryPage tmp;
using (_tx.Environment.GetTemporaryPage(_tx, out tmp))
{
var mergedPage = tmp.GetTempPage(left.KeysPrefixed);
Memory.Copy(mergedPage.Base, left.Base, left.PageSize);
var previousSearchPosition = right.LastSearchPosition;
for (int i = 0; i < right.NumberOfEntries; i++)
{
right.LastSearchPosition = i;
var key = GetActualKey(right, right.LastSearchPositionOrLastEntry);
var node = right.GetNode(i);
var prefixedKey = mergedPage.PrepareKeyToInsert(key, mergedPage.NumberOfEntries);
if (mergedPage.HasSpaceFor(_tx, SizeOf.NodeEntryWithAnotherKey(node, prefixedKey) + Constants.NodeOffsetSize + SizeOf.NewPrefix(prefixedKey)) == false)
{
right.LastSearchPosition = previousSearchPosition; //previous position --> prevent mutation of parameter
return(false);
}
mergedPage.CopyNodeDataToEndOfPage(node, prefixedKey);
}
Memory.Copy(left.Base, mergedPage.Base, left.PageSize);
}
parentPage.RemoveNode(parentPage.LastSearchPositionOrLastEntry); // unlink the right sibling
_tree.FreePage(right);
return(true);
}
private void AddSeparatorToParentPage(Page parentPage, long pageNumber, MemorySlice seperatorKey, int separatorKeyPosition)
{
var separatorKeyToInsert = parentPage.PrepareKeyToInsert(seperatorKey, separatorKeyPosition);
if (parentPage.HasSpaceFor(_tx, SizeOf.BranchEntry(separatorKeyToInsert) + Constants.NodeOffsetSize + SizeOf.NewPrefix(separatorKeyToInsert)) == false)
{
var pageSplitter = new PageSplitter(_tx, _tree, seperatorKey, -1, pageNumber, NodeFlags.PageRef,
0, _cursor, _tree.State);
pageSplitter.Execute();
}
else
{
parentPage.AddPageRefNode(separatorKeyPosition, separatorKeyToInsert, pageNumber);
}
}
public int GetRequiredSpace(MemorySlice key, int len)
{
return(SizeOf.NodeEntry(PageMaxSpace, key, len) + Constants.NodeOffsetSize + SizeOf.NewPrefix(key));
}
/// <summary>
/// Internal method that is used when splitting pages
/// No need to do any work here, we are always adding at the end
/// </summary>
internal void CopyNodeDataToEndOfPage(NodeHeader *other, MemorySlice key)
{
var index = NumberOfEntries;
Debug.Assert(HasSpaceFor(SizeOf.NodeEntryWithAnotherKey(other, key) + Constants.NodeOffsetSize + SizeOf.NewPrefix(key)));
var nodeSize = SizeOf.NodeEntryWithAnotherKey(other, key);
Debug.Assert(IsBranch == false || index != 0 || key.KeyLength == 0); // branch page's first item must be the implicit ref
var nodeVersion = other->Version; // every time new node is allocated the version is increased, but in this case we do not want to increase it
if (nodeVersion > 0)
{
nodeVersion -= 1;
}
var prefixedKey = key as PrefixedSlice;
if (prefixedKey != null && prefixedKey.NewPrefix != null)
{
WritePrefix(prefixedKey.NewPrefix, prefixedKey.Header.PrefixId);
}
var newNode = AllocateNewNode(index, nodeSize, nodeVersion);
newNode->KeySize = key.Size;
newNode->Flags = other->Flags;
if (key.Options == SliceOptions.Key && key.Size > 0)
{
key.CopyTo((byte *)newNode + Constants.NodeHeaderSize);
}
if (IsBranch || other->Flags == (NodeFlags.PageRef))
{
newNode->PageNumber = other->PageNumber;
newNode->Flags = NodeFlags.PageRef;
return;
}
newNode->DataSize = other->DataSize;
MemoryUtils.Copy((byte *)newNode + Constants.NodeHeaderSize + key.Size,
(byte *)other + Constants.NodeHeaderSize + other->KeySize,
other->DataSize);
}
private void AddSeparatorToParentPage(long pageNumber, MemorySlice seperatorKey)
{
var separatorKeyToInsert = _parentPage.PrepareKeyToInsert(seperatorKey, _parentPage.LastSearchPosition);
if (_parentPage.HasSpaceFor(_tx, SizeOf.BranchEntry(separatorKeyToInsert) + Constants.NodeOffsetSize + SizeOf.NewPrefix(separatorKeyToInsert)) == false)
{
var pageSplitter = new PageSplitter(_tx, _tree, seperatorKey, -1, pageNumber, NodeFlags.PageRef,
0, _cursor, _treeState);
pageSplitter.Execute();
}
else
{
_parentPage.NodePositionFor(seperatorKey); // select the appropriate place for this
_parentPage.AddPageRefNode(_parentPage.LastSearchPosition, separatorKeyToInsert, pageNumber);
}
}
private byte *AddSeparatorToParentPage(long pageNumber, MemorySlice seperatorKey, bool toRight, out Page parent)
{
var pos = _parentPage.NodePositionFor(seperatorKey); // select the appropriate place for this
var separatorKeyToInsert = _parentPage.PrepareKeyToInsert(seperatorKey, pos);
if (_parentPage.HasSpaceFor(_tx, SizeOf.BranchEntry(separatorKeyToInsert) + Constants.NodeOffsetSize + SizeOf.NewPrefix(separatorKeyToInsert)) == false)
{
var pageSplitter = new PageSplitter(_tx, _tree, seperatorKey, -1, pageNumber, NodeFlags.PageRef,
0, _cursor, _treeState);
var posToInsert = pageSplitter.Execute();
if (toRight == false && _cursor.CurrentPage.PageNumber != _parentPage.PageNumber)
{
// _newKey being added to _page wasn't meant to be inserted to a newly created right page
// however the above page split has modified the cursor that its first page is a parent page for the right page containing separator key
// we need to ensure that the current _parentPage is first at the cursor
parent = _cursor.Pop();
_cursor.Push(_parentPage);
}
else
{
parent = _parentPage;
}
return(posToInsert);
}
parent = _parentPage;
return(_parentPage.AddPageRefNode(pos, separatorKeyToInsert, pageNumber));
}
public byte *AddSeparator(MemorySlice separator, long pageRefNumber, int?nodePos = null)
{
var originalLastSearchPositionOfParent = _parentPage.LastSearchPosition;
if (nodePos == null)
{
nodePos = _parentPage.NodePositionFor(separator); // select the appropriate place for this
}
var separatorKeyToInsert = _parentPage.PrepareKeyToInsert(separator, nodePos.Value);
if (_parentPage.HasSpaceFor(_tx, SizeOf.BranchEntry(separatorKeyToInsert) + Constants.NodeOffsetSize + SizeOf.NewPrefix(separatorKeyToInsert)) == false)
{
var pageSplitter = new PageSplitter(_tx, _tree, separator, -1, pageRefNumber, NodeFlags.PageRef, 0, _cursor, _tree.State);
var posToInsert = pageSplitter.Execute();
ParentOfAddedPageRef = _cursor.CurrentPage;
var adjustParentPageOnCursor = true;
for (int i = 0; i < _cursor.CurrentPage.NumberOfEntries; i++)
{
if (_cursor.CurrentPage.GetNode(i)->PageNumber == _currentPage.PageNumber)
{
adjustParentPageOnCursor = false;
_cursor.CurrentPage.LastSearchPosition = i;
break;
}
}
if (adjustParentPageOnCursor)
{
// the above page split has modified the cursor that its first page points to the parent of the leaf where 'separatorKey' was inserted
// and it doesn't have the reference to _page, we need to ensure that the actual parent is first at the cursor
_cursor.Pop();
_cursor.Push(_parentPage);
EnsureValidLastSearchPosition(_parentPage, _currentPage.PageNumber, originalLastSearchPositionOfParent);
}
#if VALIDATE
Debug.Assert(_cursor.CurrentPage.GetNode(_cursor.CurrentPage.LastSearchPosition)->PageNumber == _currentPage.PageNumber,
"The parent page is not referencing a page which is being split");
var parentToValidate = ParentOfAddedPageRef;
Debug.Assert(Enumerable.Range(0, parentToValidate.NumberOfEntries).Any(i => parentToValidate.GetNode(i)->PageNumber == pageRefNumber),
"The parent page of a page reference isn't referencing it");
#endif
return(posToInsert);
}
ParentOfAddedPageRef = _parentPage;
var pos = _parentPage.AddPageRefNode(nodePos.Value, separatorKeyToInsert, pageRefNumber);
EnsureValidLastSearchPosition(_parentPage, _currentPage.PageNumber, originalLastSearchPositionOfParent);
return(pos);
}