public bool MovePrev()
{
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 = _tx.GetReadOnlyPage(node->PageNumber);
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries - 1;
}
var current = _currentPage.GetNode(_currentPage.LastSearchPosition);
if (this.ValidateCurrentKey(current, _currentPage) == false)
{
return(false);
}
_currentPage.SetNodeKey(current, ref _currentInternalKey);
_currentKey = _currentInternalKey.ToSlice();
return(true); // there is another entry in this page
}
if (_cursor.PageCount == 0)
{
break;
}
_currentPage = _cursor.Pop();
}
_currentPage = null;
return(false);
}
private void RemoveBranchWithOneEntry(Page page, Page parentPage)
{
Debug.Assert(page.NumberOfEntries == 1);
var pageRefNumber = page.GetNode(0)->PageNumber;
NodeHeader *nodeHeader = null;
for (int i = 0; i < parentPage.NumberOfEntries; i++)
{
nodeHeader = parentPage.GetNode(i);
if (nodeHeader->PageNumber == page.PageNumber)
{
break;
}
}
Debug.Assert(nodeHeader->PageNumber == page.PageNumber, string.Format("Node page number: {0}, page number: {1}", nodeHeader->PageNumber, page.PageNumber));
nodeHeader->PageNumber = pageRefNumber;
if (_cursor.CurrentPage.PageNumber == page.PageNumber)
{
_cursor.Pop();
_cursor.Push(_tx.GetReadOnlyPage(pageRefNumber));
}
_tree.FreePage(page);
}
public bool Seek(Slice key)
{
_currentPage = _tree.FindPageFor(_tx, key, _cursor);
_cursor.Pop();
var node = _currentPage.Search(key, _cmp);
if (node == null)
{
return(false);
}
_currentKey.Set(node);
return(this.ValidateCurrentKey(Current, _cmp));
}
public PageSplitter(Transaction tx,
Tree tree,
SliceComparer cmp,
Slice newKey,
int len,
long pageNumber,
NodeFlags nodeType,
ushort nodeVersion,
Cursor cursor,
TreeMutableState treeState)
{
_tx = tx;
_tree = tree;
_cmp = cmp;
_newKey = newKey;
_len = len;
_pageNumber = pageNumber;
_nodeType = nodeType;
_nodeVersion = nodeVersion;
_cursor = cursor;
_treeState = treeState;
Page page = _cursor.Pages.First.Value;
_page = tx.ModifyPage(page.PageNumber, page);
_cursor.Pop();
}
public PageSplitter(Transaction tx,
Tree tree,
SliceComparer cmp,
Slice newKey,
int len,
long pageNumber,
NodeFlags nodeType,
ushort nodeVersion,
Cursor cursor,
TreeMutableState treeState)
{
_tx = tx;
_tree = tree;
_cmp = cmp;
_newKey = newKey;
_len = len;
_pageNumber = pageNumber;
_nodeType = nodeType;
_nodeVersion = nodeVersion;
_cursor = cursor;
_treeState = treeState;
Page page = _cursor.Pages.First.Value;
_page = tx.ModifyPage(page.PageNumber, page);
_cursor.Pop();
}
private void RebalanceRoot(Cursor cursor, Page page)
{
if (page.NumberOfEntries == 0)
{
return; // nothing to do
}
if (!page.IsBranch || page.NumberOfEntries > 1)
{
return; // cannot do anything here
}
// in this case, we have a root pointer with just one pointer, we can just swap it out
var node = page.GetNode(0);
Debug.Assert(node->Flags == (NodeFlags.PageRef));
_tree.State.LeafPages = 1;
_tree.State.BranchPages = 0;
_tree.State.Depth = 1;
_tree.State.PageCount = 1;
var rootPage = _tx.ModifyPage(node->PageNumber, null);
_tree.State.RootPageNumber = rootPage.PageNumber;
Debug.Assert(rootPage.Dirty);
cursor.Pop();
cursor.Push(rootPage);
_tx.FreePage(page.PageNumber);
}
public bool Seek(Slice key)
{
if (_disposed)
{
throw new ObjectDisposedException("TreeIterator " + _tree.Name);
}
Lazy <Cursor> lazy;
NodeHeader * node;
_currentPage = _tree.FindPageFor(key, out node, out lazy);
_cursor = lazy.Value;
_cursor.Pop();
if (node != null)
{
_currentPage.SetNodeKey(node, ref _currentInternalKey);
_currentKey = _currentInternalKey.ToSlice();
return(this.ValidateCurrentKey(Current, _currentPage));
}
// 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)
{
_cursor.Push(_currentPage);
var node = _currentPage.GetNode(_currentPage.LastSearchPosition);
_currentPage = _tx.GetReadOnlyPage(node->PageNumber);
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries - 1;
if (_prefetch && _currentPage.IsLeaf)
{
MaybePrefetchOverflowPages(_currentPage);
}
}
var current = _currentPage.GetNode(_currentPage.LastSearchPosition);
if (this.ValidateCurrentKey(current, _currentPage) == false)
{
return(false);
}
_currentPage.SetNodeKey(current, ref _currentInternalKey);
_currentKey = _currentInternalKey.ToSlice();
return(true);// there is another entry in this page
}
if (_cursor.PageCount == 0)
{
break;
}
_currentPage = _cursor.Pop();
}
_currentPage = null;
return(false);
}
public PageSplitter(Transaction tx, SliceComparer cmp, Slice newKey, int len, long pageNumber, Cursor cursor, TreeDataInTransaction txInfo)
{
_tx = tx;
_cmp = cmp;
_newKey = newKey;
_len = len;
_pageNumber = pageNumber;
_cursor = cursor;
_txInfo = txInfo;
_page = _cursor.Pop();
}
public bool Seek(Slice key)
{
Lazy<Cursor> lazy;
_currentPage = _tree.FindPageFor(_tx, key, out lazy);
_cursor = lazy.Value;
_cursor.Pop();
var node = _currentPage.Search(key, _cmp);
if (node == null)
{
return false;
}
_currentKey.Set(node);
return this.ValidateCurrentKey(Current, _cmp);
}
public bool Seek(Slice key)
{
Lazy<Cursor> lazy;
_currentPage = _tree.FindPageFor(key, out lazy);
_cursor = lazy.Value;
_cursor.Pop();
var node = _currentPage.Search(key);
if (node != null)
{
_currentKey.Set(node);
return this.ValidateCurrentKey(Current);
}
// 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 PageSplitter(Transaction tx,
Tree tree,
MemorySlice newKey,
int len,
long pageNumber,
NodeFlags nodeType,
ushort nodeVersion,
Cursor cursor)
{
_tx = tx;
_tree = tree;
_newKey = newKey;
_len = len;
_pageNumber = pageNumber;
_nodeType = nodeType;
_nodeVersion = nodeVersion;
_cursor = cursor;
Page page = _cursor.Pages.First.Value;
_page = tx.ModifyPage(page.PageNumber, _tree, page);
_cursor.Pop();
}
public bool Seek(Slice key)
{
Lazy <Cursor> lazy;
_currentPage = _tree.FindPageFor(key, out lazy);
_cursor = lazy.Value;
_cursor.Pop();
var node = _currentPage.Search(key);
if (node != null)
{
_currentKey.Set(node);
return(this.ValidateCurrentKey(Current));
}
// 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 Page Execute(Cursor cursor, Page page)
{
_tx.ClearRecentFoundPages(_tree);
if (cursor.PageCount <= 1) // the root page
{
RebalanceRoot(cursor, page);
return null;
}
var parentPage = _tx.ModifyPage(cursor.ParentPage.PageNumber, cursor.ParentPage);
cursor.Update(cursor.Pages.First.Next, parentPage);
if (page.NumberOfEntries == 0) // empty page, just delete it and fixup parent
{
// need to delete the implicit left page, shift right
if (parentPage.LastSearchPosition == 0 && parentPage.NumberOfEntries > 2)
{
var newImplicit = parentPage.GetNode(1)->PageNumber;
parentPage.RemoveNode(0);
parentPage.RemoveNode(0);
parentPage.AddPageRefNode(0, Slice.Empty, newImplicit);
}
else // will be set to rights by the next rebalance call
{
parentPage.RemoveNode(parentPage.LastSearchPositionOrLastEntry);
}
_tx.FreePage(page.PageNumber);
cursor.Pop();
return parentPage;
}
var minKeys = page.IsBranch ? 2 : 1;
if ((page.UseMoreSizeThan(_tx.DataPager.PageMinSpace)) &&
page.NumberOfEntries >= minKeys)
return null; // above space/keys thresholds
Debug.Assert(parentPage.NumberOfEntries >= 2); // if we have less than 2 entries in the parent, the tree is invalid
var sibling = SetupMoveOrMerge(cursor, page, parentPage);
Debug.Assert(sibling.PageNumber != page.PageNumber);
minKeys = sibling.IsBranch ? 2 : 1; // branch must have at least 2 keys
if (sibling.UseMoreSizeThan(_tx.DataPager.PageMinSpace) &&
sibling.NumberOfEntries > minKeys)
{
// neighbor is over the min size and has enough key, can move just one key to the current page
if (page.IsBranch)
{
MoveBranchNode(parentPage, sibling, page);
}
else
MoveLeafNode(parentPage, sibling, page);
cursor.Pop();
return parentPage;
}
if (page.LastSearchPosition == 0) // this is the right page, merge left
{
if (!HasEnoughSpaceToCopyNodes(sibling, page))
return null;
MergePages(parentPage, sibling, page);
}
else // this is the left page, merge right
{
if (!HasEnoughSpaceToCopyNodes(page, sibling))
return null;
MergePages(parentPage, page, sibling);
}
cursor.Pop();
return parentPage;
}
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);
}
public Page Execute(Cursor cursor, Page page)
{
if (cursor.PageCount <= 1) // the root page
{
RebalanceRoot(cursor, _txInfo, page);
return(null);
}
var parentPage = cursor.ParentPage;
if (page.NumberOfEntries == 0) // empty page, just delete it and fixup parent
{
// need to delete the implicit left page, shift right
if (parentPage.LastSearchPosition == 0 && parentPage.NumberOfEntries > 2)
{
var newImplicit = parentPage.GetNode(1)->PageNumber;
parentPage.AddNode(0, Slice.Empty, -1, newImplicit);
parentPage.RemoveNode(1);
parentPage.RemoveNode(1);
}
else // will be set to rights by the next rebalance call
{
parentPage.RemoveNode(parentPage.LastSearchPosition);
}
cursor.Pop();
return(parentPage);
}
var minKeys = page.IsBranch ? 2 : 1;
if (page.SizeUsed >= _tx.Pager.PageMinSpace &&
page.NumberOfEntries >= minKeys)
{
return(null); // above space/keys thresholds
}
Debug.Assert(parentPage.NumberOfEntries >= 2); // if we have less than 2 entries in the parent, the tree is invalid
var sibling = SetupMoveOrMerge(cursor, page, parentPage);
Debug.Assert(sibling.PageNumber != page.PageNumber);
minKeys = sibling.IsBranch ? 2 : 1; // branch must have at least 2 keys
if (sibling.SizeUsed > _tx.Pager.PageMinSpace &&
sibling.NumberOfEntries > minKeys)
{
// neighbor is over the min size and has enough key, can move just one key to the current page
if (page.IsBranch)
{
MoveBranchNode(parentPage, sibling, page);
}
else
{
MoveLeafNode(parentPage, sibling, page);
}
cursor.Pop();
return(parentPage);
}
if (page.LastSearchPosition == 0) // this is the right page, merge left
{
MergePages(parentPage, sibling, page);
}
else // this is the left page, merge right
{
MergePages(parentPage, page, sibling);
}
cursor.Pop();
return(parentPage);
}
private byte *SplitPageInHalf(Page rightPage)
{
bool toRight;
var currentIndex = _page.LastSearchPosition;
var splitIndex = _page.NumberOfEntries / 2;
if (currentIndex <= splitIndex)
{
toRight = false;
}
else
{
toRight = true;
var leftPageEntryCount = splitIndex;
var rightPageEntryCount = _page.NumberOfEntries - leftPageEntryCount + 1;
if (rightPageEntryCount > leftPageEntryCount)
{
splitIndex++;
Debug.Assert(splitIndex < _page.NumberOfEntries);
}
}
PrefixNode[] prefixes = null;
if (_tree.KeysPrefixing && _page.HasPrefixes)
{
prefixes = _page.GetPrefixes();
}
if (_page.IsLeaf || prefixes != null)
{
splitIndex = AdjustSplitPosition(currentIndex, splitIndex, prefixes, ref toRight);
}
var currentKey = _page.GetNodeKey(splitIndex);
MemorySlice seperatorKey;
if (toRight && splitIndex == currentIndex)
{
seperatorKey = currentKey.Compare(_newKey) < 0 ? currentKey : _newKey;
}
else
{
seperatorKey = currentKey;
}
Page parentOfRight;
AddSeparatorToParentPage(rightPage.PageNumber, seperatorKey, out parentOfRight);
var parentOfPage = _cursor.CurrentPage;
MemorySlice instance = _page.CreateNewEmptyKey();
if (prefixes != null)
{
for (int i = 0; i < prefixes.Length; i++)
{
var prefix = prefixes[i];
rightPage.WritePrefix(new Slice(prefix.ValuePtr, prefix.PrefixLength), i);
}
}
bool addedAsImplicitRef = false;
if (_page.IsBranch && toRight && seperatorKey == _newKey)
{
// _newKey needs to be inserted as first key (BeforeAllKeys) to the right page, so we need to add it before we move entries from the current page
AddNodeToPage(rightPage, 0, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys);
addedAsImplicitRef = true;
}
// move the actual entries from page to right page
ushort nKeys = _page.NumberOfEntries;
for (int i = splitIndex; i < nKeys; i++)
{
NodeHeader *node = _page.GetNode(i);
if (_page.IsBranch && rightPage.NumberOfEntries == 0)
{
rightPage.CopyNodeDataToEndOfPage(node, _tree.KeysPrefixing ? (MemorySlice)PrefixedSlice.BeforeAllKeys : Slice.BeforeAllKeys);
}
else
{
_page.SetNodeKey(node, ref instance);
var key = rightPage.PrepareKeyToInsert(instance, rightPage.NumberOfEntries);
rightPage.CopyNodeDataToEndOfPage(node, key);
}
}
_page.Truncate(_tx, splitIndex);
byte *pos;
if (addedAsImplicitRef == false)
{
try
{
if (toRight && _cursor.CurrentPage.PageNumber != parentOfRight.PageNumber)
{
// modify the cursor if we are going to insert to the right page
_cursor.Pop();
_cursor.Push(parentOfRight);
}
// actually insert the new key
pos = toRight ? InsertNewKey(rightPage) : InsertNewKey(_page);
}
catch (InvalidOperationException e)
{
if (e.Message.StartsWith("The page is full and cannot add an entry") == false)
{
throw;
}
throw new InvalidOperationException(GatherDetailedDebugInfo(rightPage, currentKey, seperatorKey, currentIndex, splitIndex, toRight), e);
}
}
else
{
pos = null;
_cursor.Push(rightPage);
}
if (_page.IsBranch) // remove a branch that has only one entry, the page ref needs to be added to the parent of the current page
{
Debug.Assert(_page.NumberOfEntries > 0);
Debug.Assert(rightPage.NumberOfEntries > 0);
if (_page.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(_page, parentOfPage);
}
if (rightPage.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(rightPage, parentOfRight);
}
}
return(pos);
}
public Page Execute(Page page)
{
_tree.ClearRecentFoundPages();
if (_cursor.PageCount <= 1) // the root page
{
RebalanceRoot(page);
return(null);
}
var parentPage = _tx.ModifyPage(_cursor.ParentPage.PageNumber, _tree, _cursor.ParentPage);
_cursor.Update(_cursor.Pages.First.Next, parentPage);
if (page.NumberOfEntries == 0) // empty page, just delete it and fixup parent
{
// need to change the implicit left page
if (parentPage.LastSearchPosition == 0 && parentPage.NumberOfEntries > 2)
{
var newImplicit = parentPage.GetNode(1)->PageNumber;
parentPage.RemoveNode(0);
parentPage.ChangeImplicitRefPageNode(newImplicit);
}
else // will be set to rights by the next rebalance call
{
parentPage.RemoveNode(parentPage.LastSearchPositionOrLastEntry);
}
_tree.FreePage(page);
_cursor.Pop();
return(parentPage);
}
if (page.IsBranch && page.NumberOfEntries == 1)
{
RemoveBranchWithOneEntry(page, parentPage);
_cursor.Pop();
return(parentPage);
}
var minKeys = page.IsBranch ? 2 : 1;
if ((page.UseMoreSizeThan(_tx.DataPager.PageMinSpace)) &&
page.NumberOfEntries >= minKeys)
{
return(null); // above space/keys thresholds
}
Debug.Assert(parentPage.NumberOfEntries >= 2); // if we have less than 2 entries in the parent, the tree is invalid
var sibling = SetupMoveOrMerge(page, parentPage);
Debug.Assert(sibling.PageNumber != page.PageNumber);
if (page.Flags != sibling.Flags)
{
return(null);
}
minKeys = sibling.IsBranch ? 2 : 1; // branch must have at least 2 keys
if (sibling.UseMoreSizeThan(_tx.DataPager.PageMinSpace) &&
sibling.NumberOfEntries > minKeys)
{
_cursor.Pop();
// neighbor is over the min size and has enough key, can move just one key to the current page
if (page.IsBranch)
{
MoveBranchNode(parentPage, sibling, page);
}
else
{
MoveLeafNode(parentPage, sibling, page);
}
return(parentPage);
}
if (page.LastSearchPosition == 0) // this is the right page, merge left
{
if (TryMergePages(parentPage, sibling, page) == false)
{
return(null);
}
}
else // this is the left page, merge right
{
if (TryMergePages(parentPage, page, sibling) == false)
{
return(null);
}
}
_cursor.Pop();
return(parentPage);
}
private void RebalanceRoot(Cursor cursor, Page page)
{
if (page.NumberOfEntries == 0)
return; // nothing to do
if (!page.IsBranch || page.NumberOfEntries > 1)
{
return; // cannot do anything here
}
// in this case, we have a root pointer with just one pointer, we can just swap it out
var node = page.GetNode(0);
Debug.Assert(node->Flags == (NodeFlags.PageRef));
_tree.State.LeafPages = 1;
_tree.State.BranchPages = 0;
_tree.State.Depth = 1;
_tree.State.PageCount = 1;
var rootPage = _tx.ModifyPage(node->PageNumber, null);
_tree.State.RootPageNumber = rootPage.PageNumber;
Debug.Assert(rootPage.Dirty);
cursor.Pop();
cursor.Push(rootPage);
_tx.FreePage(page.PageNumber);
}
