protected override void ReadContent(ByteReader reader)
{
_nodes = new Dictionary <ushort, IndexNode>(ItemCount);
for (var i = 0; i < ItemCount; i++)
{
var index = reader.ReadUInt16();
var levels = reader.ReadByte();
var node = new IndexNode(levels);
node.Page = this;
node.Position = new PageAddress(PageID, index);
node.Slot = reader.ReadByte();
node.PrevNode = reader.ReadPageAddress();
node.NextNode = reader.ReadPageAddress();
node.KeyLength = reader.ReadUInt16();
node.Key = reader.ReadBsonValue(node.KeyLength);
node.DataBlock = reader.ReadPageAddress();
for (var j = 0; j < node.Prev.Length; j++)
{
node.Prev[j] = reader.ReadPageAddress();
node.Next[j] = reader.ReadPageAddress();
}
_nodes.Add(node.Position.Index, node);
}
}
/// <summary>
/// Gets all node list from any index node (go forward and backward)
/// </summary>
public IEnumerable <IndexNode> GetNodeList(IndexNode node, bool includeInitial)
{
var next = node.NextNode;
var prev = node.PrevNode;
// returns some initial node
if (includeInitial)
{
yield return(node);
}
// go forward
while (next.IsEmpty == false)
{
var n = GetNode(next);
next = n.NextNode;
yield return(n);
}
// go backward
while (prev.IsEmpty == false)
{
var p = GetNode(prev);
prev = p.PrevNode;
yield return(p);
}
}
/// <summary>
/// Delete node from this page and update counter and free space
/// </summary>
public void DeleteNode(IndexNode node)
{
ItemCount--;
FreeBytes += node.Length;
_nodes.Remove(node.Position.Index);
}
/// <summary>
/// Add new index node into this page. Update counters and free space
/// </summary>
public void AddNode(IndexNode node)
{
var index = _nodes.NextIndex();
node.Position = new PageAddress(PageID, index);
ItemCount++;
FreeBytes -= node.Length;
_nodes.Add(index, node);
}
/// <summary>
/// Insert a new node index inside an collection index. Flip coin to know level
/// </summary>
public IndexNode AddNode(CollectionIndex index, BsonValue key, IndexNode last)
{
var level = FlipCoin();
// set index collection with max-index level
if (level > index.MaxLevel)
{
index.MaxLevel = level;
_pager.SetDirty(index.Page);
}
// call AddNode with key value
return(AddNode(index, key, level, last));
}
/// <summary>
/// Goto the first/last occurrence of this index value
/// </summary>
private IndexNode FindBoundary(CollectionIndex index, IndexNode cur, BsonValue value, int order, int level)
{
var last = cur;
while (cur.Key.CompareTo(value) == 0)
{
last = cur;
cur = GetNode(cur.NextPrev(0, order));
if (cur.IsHeadTail(index))
{
break;
}
}
return(last);
}
/// <summary>
/// Create a new index and returns head page address (skip list)
/// </summary>
public CollectionIndex CreateIndex(CollectionPage col)
{
// get index slot
var index = col.GetFreeIndex();
// get a new index page for first index page
var page = _pager.NewPage <IndexPage>();
// create a empty node with full max level
var head = new IndexNode(IndexNode.MAX_LEVEL_LENGTH)
{
Key = BsonValue.MinValue,
KeyLength = (ushort)BsonValue.MinValue.GetBytesCount(false),
Slot = (byte)index.Slot,
Page = page
};
// add as first node
page.AddNode(head);
// set index page as dirty
_pager.SetDirty(index.Page);
// add indexPage on freelist if has space
_pager.AddOrRemoveToFreeList(true, page, index.Page, ref index.FreeIndexPageID);
// point the head/tail node to this new node position
index.HeadNode = head.Position;
// insert tail node
var tail = AddNode(index, BsonValue.MaxValue, IndexNode.MAX_LEVEL_LENGTH, null);
index.TailNode = tail.Position;
return(index);
}
/// <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 = 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 : 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 : 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 = 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 = 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);
}