public static int WriteMultipageItemBlock(IPage page, DbItem item, long offset)
{
if (offset < 0 || offset >= item.RawData.LongLength)
{
throw new ArgumentOutOfRangeException(nameof(offset));
}
MultipageItemPageHeader header = GetMultipageItemPageHeader(page);
if (item.GetAllocationType(page.Length) == AllocationType.SinglePage)
{
throw new PageFormatException("Unable to add item block on page. Item allocation type is single page.");
}
int last = Math.Min(page.Length - header.Length, (int)(item.RawData.LongLength - offset)) - 1;
int contentOffset = header.Length;
if (offset == 0)
{
// we should write the length of the object
var lengthBytes = BitConverter.GetBytes(item.RawData.LongLength);
lengthBytes.CopyTo(page.Content, header.Length);
last -= 8;
contentOffset += 8;
}
for (long i = 0; i <= last; i++)
{
page.Content[i + contentOffset] = item.RawData[i + offset];
}
return(last + 1);
}
public static long ReadMultipageItemLength(IPage page)
{
MultipageItemPageHeader header = GetMultipageItemPageHeader(page);
if (header.PreviousPageIndex != -1)
{
throw new PageFormatException("This page is not the start page of multipage item.");
}
return(BitConverter.ToInt64(page.Content, header.Length));
}
public static byte[] ReadMultipageItemBlock(IPage page, int length)
{
MultipageItemPageHeader header = GetMultipageItemPageHeader(page);
var offset = header.Length;
// skip object length marker if we are on the start page
if (header.PreviousPageIndex == -1)
{
offset += 8;
}
return(ReadBlock(page, Math.Min(length, page.Length - offset), offset));
}
public static PageHeaderBase GetPageHeader(IPage page)
{
PageHeaderBase ph;
PageType pt = PageHeaderBase.GetPageType(page);
switch (pt)
{
case PageType.FreeSpaceMap:
ph = new FreeSpaceMapPageHeader();
ph.Read(page);
return(ph);
case PageType.Heading:
ph = new HeadingPageHeader();
ph.Read(page);
return(ph);
case PageType.MultipageItem:
ph = new MultipageItemPageHeader();
ph.Read(page);
return(ph);
case PageType.FixedSizeItem:
ph = new FixedSizeItemsPageHeader();
ph.Read(page);
return(ph);
case PageType.BPlusTree:
ph = new BPlusTreeNodePageHeader();
ph.Read(page);
return(ph);
case PageType.RadixTree:
ph = new RadixTreeNodesPageHeader();
ph.Read(page);
return(ph);
}
return(null);
}
