/// <summary>
/// Create new Page based on pre-defined PageID and PageType
/// </summary>
public BasePage(PageBuffer buffer, uint pageID, PageType pageType)
{
_buffer = buffer;
ENSURE(buffer.Slice(PAGE_HEADER_SIZE, PAGE_SIZE - PAGE_HEADER_SIZE - 1).All(0), "new page buffer must be empty before use in a new page");
// page information
this.PageID = pageID;
this.PageType = pageType;
this.PrevPageID = uint.MaxValue;
this.NextPageID = uint.MaxValue;
// transaction information
this.ColID = uint.MaxValue;
this.TransactionID = uint.MaxValue;
this.IsConfirmed = false;
// block information
this.ItemsCount = 0;
this.UsedBytes = 0;
this.FragmentedBytes = 0;
this.NextFreePosition = PAGE_HEADER_SIZE; // 32
this.HighestIndex = byte.MaxValue; // empty - not used yet
// default values
this.IsDirty = false;
// writing direct into buffer in Ctor() because there is no change later (write once)
_buffer.Write(this.PageID, P_PAGE_ID);
_buffer.Write((byte)this.PageType, P_PAGE_TYPE);
}
/// <summary>
/// Write header data from variable into byte[] buffer. When override, call base.UpdateBuffer() after write your code
/// </summary>
public virtual PageBuffer UpdateBuffer()
{
// using fixed position to be faster than BufferWriter
ENSURE(this.PageID == _buffer.ReadUInt32(P_PAGE_ID), "pageID can't be changed");
// page information
// PageID - never change!
_buffer.Write(this.PrevPageID, P_PREV_PAGE_ID);
_buffer.Write(this.NextPageID, P_NEXT_PAGE_ID);
// transaction information
_buffer.Write(this.TransactionID, P_TRANSACTION_ID);
_buffer.Write(this.IsConfirmed, P_IS_CONFIRMED);
_buffer.Write(this.ColID, P_COL_ID);
// segments information
_buffer.Write(this.ItemsCount, P_ITEMS_COUNT);
_buffer.Write(this.UsedBytes, P_USED_BYTES);
_buffer.Write(this.FragmentedBytes, P_FRAGMENTED_BYTES);
_buffer.Write(this.NextFreePosition, P_NEXT_FREE_POSITION);
_buffer.Write(this.HighestIndex, P_HIGHEST_INDEX);
return(_buffer);
}