IEnumerable <BTreePageItems <T> > GetNodeItemPages <T>(BTreePageBase <T> rootPage)
where T : IComparable <T>
{
var stack = new Stack <BTreePageBase <T> >();
stack.Push(rootPage);
while (stack.Count > 0)
{
var item = stack.Pop();
if (item.Type == BTreePageType.Collection)
{
yield return(item as BTreePageItems <T>);
}
else
{
var node = item as BTreePageNode <T>;
if (node.Right != null)
{
stack.Push(node.Right);
}
if (node.Left != null)
{
stack.Push(node.Left);
}
}
}
}
void StoreTreePage <T>(BTreePageBase <T> rootPage, io.BinaryWriter writer)
where T : IComparable <T>
{
if (rootPage.IsLeaf)
{
//store id of left
Int32 valueInt32 = Consts.BTreePageNodeItemsFlag;
writer.Write(valueInt32);
//offset
///////////////// TO BE USED AS AN ID //////////////////////////
var leaf = rootPage as BTreePageItems <T>;
writer.Write(leaf.Offset);
}
else
{
//store page node
var buffer = rootPage.ToBuffer();
writer.Write(buffer, 0, buffer.Length);
//try to navigate left or right
var node = rootPage as BTreePageNode <T>;
int empty = 0;
if (node.Left == null)
{
//signal, no left node
writer.Write(empty);
throw new ArgumentException($"Tree Node key:[{node.Root.Key}] has no left child");
}
else
{
StoreTreePage <T>(node.Left, writer);
}
if (node.Right == null)
{
//signal, no right node
writer.Write(empty);
throw new ArgumentException($"Tree Node key:[{node.Root.Key}] has no right child");
}
else
{
StoreTreePage <T>(node.Right, writer);
}
}
}
void SaveBinaryIndex <T>(BTreePageBase <T> rootPage, DbColumn index)
where T : IComparable <T>
{
if (rootPage == null)
{
return;
}
var pageCount = rootPage.ChildrenCount;
Console.WriteLine($" saving ({pageCount}) page(s)");
//update column tree page count
index.NodePages = pageCount;
index.Table.Database.Modified = true;
string indexfilepath = io.Path.Combine(Database.BinaryPath, $"{index.Indexer}");
//page with items .bin
//this where the main info is
var indexBinFilePath = indexfilepath + ".bin";
using (var writer = new io.BinaryWriter(io.File.Create(indexBinFilePath)))
{
var collectionPage = GetNodeItemPages <T>(rootPage).ToList();
//update column item page count
index.ItemPages = collectionPage.Count;
//MAIN HEADER
Int32 pageCollectionCount = collectionPage.Count;
//write amount of pages
writer.Write(pageCollectionCount);
//write index key type
Int32 keyType = (int)index.TypeEnum;
writer.Write(keyType);
//pages
//sizeof: pageCollectionCount, keyType
var offset = DbGenerator.ItemsPageStart; // 8;
foreach (var page in collectionPage)
{
page.Offset = offset;
//save page
var buffer = page.ToBuffer();
//
offset += buffer.Length;
//
writer.Write(buffer, 0, buffer.Length);
}
}
//tree page indexer .index
//this is a light in-memory tree structure for fast search
using (var writer = new io.BinaryWriter(io.File.Create(indexfilepath)))
{
Int32 valueInt32 = 0;
//write Index main Header
PageIndexTreeHeader header = new PageIndexTreeHeader();
//
header.Value0 = 0;
//page count
header.PageCount = pageCount;
//index.Index
header.ColumnIndex = index.Index;
//index.Unique
//index.Key
valueInt32 =
(index.Unique ? Consts.IndexHeaderIsUnique : 0) |
(index.Key ? Consts.IndexHeaderIsKey : 0) |
(rootPage.IsLeaf ? Consts.IndexHeaderIsLeaf : 0);
//index.Type
//valueInt32 = valueInt32 << 8;
valueInt32 |= (byte)index.TypeEnum;
header.Flags = valueInt32;
//write Header
byte[] buffer = header.ToByteArray();
writer.Write(buffer, 0, buffer.Length);
//test
var bin = Convert.ToString(header.Flags, 2);
//write page tree
if (!rootPage.IsLeaf)
{
StoreTreePage <T>(rootPage, writer);
}
}
}
