public static short[] ReadFixedSizeItemLengths(IPage page)
{
SizeRange range = PageHeaderBase.GetSizeRange(page);
if (range == SizeRange.MultiPage || range == SizeRange.NotApplicable)
{
throw new PageFormatException("Page is not dedicated to fixed size items.");
}
short headerLength = PageHeaderBase.GetHeaderLength(page);
short itemSizesLength = BitConverter.ToInt16(page.Content, headerLength);
var result = new short[itemSizesLength];
int offset = headerLength + OnPagePointerSize;
var content = page.Content;
for (int i = 0; i < itemSizesLength; i++)
{
result[i] = BitConverter.ToInt16(content, offset);
offset += OnPagePointerSize;
}
return(result);
}
public static List <DbItem> ReadFixedSizeItems(IPage page)
{
short[] itemLengths = ReadFixedSizeItemLengths(page);
var result = new List <DbItem>(itemLengths.Length);
short maxSize = DbItem.GetMaxSize(PageHeaderBase.GetSizeRange(page));
int offset = page.Content.Length - maxSize;
var content = page.Content;
int cnt = itemLengths.Length;
for (int i = 0; i < cnt; i++)
{
var il = itemLengths[i];
if (il != -1) // item is actualy present on page, read it
{
var itemBytes = new byte[Math.Max(il, (short)0)];
Buffer.BlockCopy(content, offset, itemBytes, 0, itemBytes.Length);
result.Add(new DbItem(itemBytes));
}
offset -= maxSize;
}
return(result);
}
public static short ReadFixedSizeItemMarkersLength(IPage page)
{
SizeRange sc = PageHeaderBase.GetSizeRange(page);
if (sc == SizeRange.MultiPage || sc == SizeRange.NotApplicable)
{
throw new PageFormatException("Page is not dedicated to fixed size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
return(BitConverter.ToInt16(page.Content, headerLength));
}
public static DbItem ReadFixedSizeItem(IPage page, short itemIndex)
{
short itemLength = ReadFixedSizeItemLength(page, itemIndex);
if (itemLength == -1)
{
throw new PageFormatException("Item has been deleted.");
}
var itemBytes = new byte[itemLength];
short slotSize = DbItem.GetMaxSize(PageHeaderBase.GetSizeRange(page));
int offset = page.Content.Length - slotSize * (itemIndex + 1);
for (int j = 0; j < itemBytes.Length; j++)
{
itemBytes[j] = page.Content[j + offset];
}
return(new DbItem(itemBytes));
}
public static short ReadFixedSizeItemLength(IPage page, short itemIndex)
{
SizeRange range = PageHeaderBase.GetSizeRange(page);
if (range == SizeRange.MultiPage || range == SizeRange.NotApplicable)
{
throw new PageFormatException("Page is not dedicated to fixed size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
short itemSizesLength = BitConverter.ToInt16(page.Content, headerLength);
if (itemIndex >= itemSizesLength)
{
throw new ArgumentOutOfRangeException(nameof(itemIndex));
}
int offset = headerLength + OnPagePointerSize + itemIndex * OnPagePointerSize;
return(BitConverter.ToInt16(page.Content, offset));
}
public static bool IsFixedSizeItemAllocated(IPage page, short itemIndex)
{
SizeRange sc = PageHeaderBase.GetSizeRange(page);
if (sc == SizeRange.MultiPage || sc == SizeRange.NotApplicable)
{
throw new PageFormatException("Page is not dedicated to fixed size items.");
}
short headerLength = BitConverter.ToInt16(page.Content, OnPageOffsets.HeaderLength);
short itemSizesLength = BitConverter.ToInt16(page.Content, headerLength);
if (itemIndex >= itemSizesLength)
{
return(false);
}
int offset = headerLength + OnPagePointerSize + itemIndex * OnPagePointerSize;
return(BitConverter.ToInt16(page.Content, offset) != -1);
}