public IIterator MultiRead(Slice key)
{
Lazy <Cursor> lazy;
NodeHeader * node;
var page = FindPageFor(key, out node, out lazy);
if (page == null || page.LastMatch != 0)
{
return(new EmptyIterator());
}
Debug.Assert(node != null);
var fetchedNodeKey = page.GetNodeKey(node);
if (fetchedNodeKey.Compare(key) != 0)
{
throw new InvalidDataException("Was unable to retrieve the correct node. Data corruption possible");
}
if (node->Flags == NodeFlags.MultiValuePageRef)
{
var tree = OpenMultiValueTree(_tx, key, node);
return(tree.Iterate());
}
var nestedPage = new Page(NodeHeader.DirectAccess(_tx, node), "multi tree", (ushort)NodeHeader.GetDataSize(_tx, node));
return(new PageIterator(nestedPage));
}
private void EnsureNestedPagePointer(Page page, NodeHeader *currentItem, ref Page nestedPage, ref byte *nestedPagePtr)
{
var movedItem = page.GetNode(page.LastSearchPosition);
if (movedItem == currentItem)
{
return;
}
// HasSpaceFor could called Defrag internally and read item has moved
// need to ensure the nested page has a valid pointer
nestedPagePtr = NodeHeader.DirectAccess(_tx, movedItem);
nestedPage = new Page(nestedPagePtr, "multi tree", (ushort)NodeHeader.GetDataSize(_tx, movedItem));
}
public void MultiAdd(Slice key, Slice value, ushort?version = null)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
int maxNodeSize = AbstractPager.NodeMaxSize;
if (value.Size > maxNodeSize)
{
throw new ArgumentException(
"Cannot add a value to child tree that is over " + maxNodeSize + " bytes in size", "value");
}
if (value.Size == 0)
{
throw new ArgumentException("Cannot add empty value to child tree");
}
State.IsModified = true;
Lazy <Cursor> lazy;
NodeHeader * node;
var page = FindPageFor(key, out node, out lazy);
if ((page == null || page.LastMatch != 0))
{
MultiAddOnNewValue(_tx, key, value, version, maxNodeSize);
return;
}
page = _tx.ModifyPage(page.PageNumber, page);
var item = page.GetNode(page.LastSearchPosition);
// already was turned into a multi tree, not much to do here
if (item->Flags == NodeFlags.MultiValuePageRef)
{
var existingTree = OpenMultiValueTree(_tx, key, item);
existingTree.DirectAdd(value, 0, version: version);
return;
}
byte *nestedPagePtr;
if (item->Flags == NodeFlags.PageRef)
{
var overFlowPage = _tx.ModifyPage(item->PageNumber, null);
nestedPagePtr = overFlowPage.Base + Constants.PageHeaderSize;
}
else
{
nestedPagePtr = NodeHeader.DirectAccess(_tx, item);
}
var nestedPage = new Page(nestedPagePtr, "multi tree", (ushort)NodeHeader.GetDataSize(_tx, item));
var existingItem = nestedPage.Search(value);
if (nestedPage.LastMatch != 0)
{
existingItem = null; // not an actual match, just greater than
}
ushort previousNodeRevision = existingItem != null ? existingItem->Version : (ushort)0;
CheckConcurrency(key, value, version, previousNodeRevision, TreeActionType.Add);
if (existingItem != null)
{
// maybe same value added twice?
var tmpKey = page.GetNodeKey(item);
if (tmpKey.Compare(value) == 0)
{
return; // already there, turning into a no-op
}
nestedPage.RemoveNode(nestedPage.LastSearchPosition);
}
var valueToInsert = nestedPage.PrepareKeyToInsert(value, nestedPage.LastSearchPosition);
if (nestedPage.HasSpaceFor(_tx, valueToInsert, 0))
{
// we are now working on top of the modified root page, we can just modify the memory directly
nestedPage.AddDataNode(nestedPage.LastSearchPosition, valueToInsert, 0, previousNodeRevision);
return;
}
int pageSize = nestedPage.CalcSizeUsed() + Constants.PageHeaderSize;
var newRequiredSize = pageSize + nestedPage.GetRequiredSpace(valueToInsert, 0);
if (newRequiredSize <= maxNodeSize)
{
// we can just expand the current value... no need to create a nested tree yet
var actualPageSize = (ushort)Math.Min(Utils.NearestPowerOfTwo(newRequiredSize), maxNodeSize);
var currentDataSize = NodeHeader.GetDataSize(_tx, item);
ExpandMultiTreeNestedPageSize(_tx, key, value, nestedPagePtr, actualPageSize, currentDataSize);
return;
}
// we now have to convert this into a tree instance, instead of just a nested page
var tree = Create(_tx, KeysPrefixing, TreeFlags.MultiValue);
for (int i = 0; i < nestedPage.NumberOfEntries; i++)
{
var existingValue = nestedPage.GetNodeKey(i);
tree.DirectAdd(existingValue, 0);
}
tree.DirectAdd(value, 0, version: version);
_tx.AddMultiValueTree(this, key, tree);
// we need to record that we switched to tree mode here, so the next call wouldn't also try to create the tree again
DirectAdd(key, sizeof(TreeRootHeader), NodeFlags.MultiValuePageRef);
}
public void MultiDelete(Slice key, Slice value, ushort?version = null)
{
State.IsModified = true;
Lazy <Cursor> lazy;
NodeHeader * node;
var page = FindPageFor(key, out node, out lazy);
if (page == null || page.LastMatch != 0)
{
return; //nothing to delete - key not found
}
page = _tx.ModifyPage(page.PageNumber, page);
var item = page.GetNode(page.LastSearchPosition);
if (item->Flags == NodeFlags.MultiValuePageRef) //multi-value tree exists
{
var tree = OpenMultiValueTree(_tx, key, item);
tree.Delete(value, version);
// previously, we would convert back to a simple model if we dropped to a single entry
// however, it doesn't really make sense, once you got enough values to go to an actual nested
// tree, you are probably going to remain that way, or be removed completely.
if (tree.State.EntriesCount != 0)
{
return;
}
_tx.TryRemoveMultiValueTree(this, key);
_tx.FreePage(tree.State.RootPageNumber);
Delete(key);
}
else // we use a nested page here
{
var nestedPage = new Page(NodeHeader.DirectAccess(_tx, item), "multi tree", (ushort)NodeHeader.GetDataSize(_tx, item));
var nestedItem = nestedPage.Search(value);
if (nestedItem == null) // value not found
{
return;
}
byte *nestedPagePtr;
if (item->Flags == NodeFlags.PageRef)
{
var overFlowPage = _tx.ModifyPage(item->PageNumber, null);
nestedPagePtr = overFlowPage.Base + Constants.PageHeaderSize;
}
else
{
nestedPagePtr = NodeHeader.DirectAccess(_tx, item);
}
nestedPage = new Page(nestedPagePtr, "multi tree", (ushort)NodeHeader.GetDataSize(_tx, item))
{
LastSearchPosition = nestedPage.LastSearchPosition
};
CheckConcurrency(key, value, version, nestedItem->Version, TreeActionType.Delete);
nestedPage.RemoveNode(nestedPage.LastSearchPosition);
if (nestedPage.NumberOfEntries == 0)
{
Delete(key);
}
}
}
