/// <summary>
/// Insert a new node index inside an collection index.
/// </summary>
private IndexNode AddNode(CollectionIndex index, BsonValue key, byte level, IndexNode last)
{
// calc key size
var keyLength = key.GetBytesCount(false);
// test for index key maxlength
if (keyLength > MAX_INDEX_LENGTH)
{
throw LiteException.IndexKeyTooLong();
}
// creating a new index node
var node = new IndexNode(level)
{
Key = key,
KeyLength = (ushort)keyLength,
Slot = (byte)index.Slot
};
// get a free page to insert my index node
var page = _pager.GetFreePage <IndexPage>(index.FreeIndexPageID, node.Length);
node.Page = page;
// add index node to page
page.AddNode(node);
// now, let's link my index node on right place
var cur = this.GetNode(index.HeadNode);
// using as cache last
IndexNode cache = null;
// scan from top left
for (var i = index.MaxLevel - 1; i >= 0; i--)
{
// get cache for last node
cache = cache != null && cache.Position.Equals(cur.Next[i]) ? cache : this.GetNode(cur.Next[i]);
// for(; <while_not_this>; <do_this>) { ... }
for (; cur.Next[i].IsEmpty == false; cur = cache)
{
// get cache for last node
cache = cache != null && cache.Position.Equals(cur.Next[i]) ? cache : this.GetNode(cur.Next[i]);
// read next node to compare
var diff = cache.Key.CompareTo(key);
// if unique and diff = 0, throw index exception (must rollback transaction - others nodes can be dirty)
if (diff == 0 && index.Unique)
{
throw LiteException.IndexDuplicateKey(index.Field, key);
}
if (diff == 1)
{
break;
}
}
if (i <= (level - 1)) // level == length
{
// cur = current (immediately before - prev)
// node = new inserted node
// next = next node (where cur is pointing)
_pager.SetDirty(cur.Page);
node.Next[i] = cur.Next[i];
node.Prev[i] = cur.Position;
cur.Next[i] = node.Position;
var next = this.GetNode(node.Next[i]);
if (next != null)
{
next.Prev[i] = node.Position;
_pager.SetDirty(next.Page);
}
}
}
// add/remove indexPage on freelist if has space
_pager.AddOrRemoveToFreeList(page.FreeBytes > IndexPage.INDEX_RESERVED_BYTES, page, index.Page, ref index.FreeIndexPageID);
// if last node exists, create a double link list
if (last != null)
{
// link new node with last node
if (last.NextNode.IsEmpty == false)
{
// fix link pointer with has more nodes in list
var next = this.GetNode(last.NextNode);
next.PrevNode = node.Position;
last.NextNode = node.Position;
node.PrevNode = last.Position;
node.NextNode = next.Position;
_pager.SetDirty(next.Page);
}
else
{
last.NextNode = node.Position;
node.PrevNode = last.Position;
}
// set last node page as dirty
_pager.SetDirty(last.Page);
}
return(node);
}