public static void FormatVariableSizeItemsPage(IPage page, PageHeaderBase header, List <byte[]> items)
{
header.WriteToPage(page);
short itemsLength = items.Aggregate <byte[], short>(0, (current, item) => (short)(current + (short)(item.Length)));
int remainingSpace =
page.Length - // full page length
header.Length - // subtract header length
itemsLength - // subtract items length
items.Count * OnPagePointerSize + OnPagePointerSize; // subtract markers array and its length
if (remainingSpace < 0)
{
throw new ArgumentException("Page have no space to add specified items", nameof(items));
}
var content = page.Content;
int contentLength = page.Length;
int cnt = items.Count;
int headerLength = header.Length;
short offset = 0;
for (int index = 0; index < cnt; index++)
{
var item = items[index];
byte[] bytes;
if (item != null)
{
bytes = BitConverter.GetBytes((short)item.Length);
offset += (short)item.Length;
// write the body of item
Buffer.BlockCopy(item, 0, content, contentLength - offset, item.Length);
}
else
{
bytes = zeroBytesShort;
}
// write the length marker
Buffer.BlockCopy(bytes, 0, content, headerLength + OnPagePointerSize * (index + 1), sizeof(short));
}
// write the length of length marker array
byte[] lengthLengthMarkers = BitConverter.GetBytes((short)cnt);
lengthLengthMarkers.CopyTo(content, headerLength);
WriteFreeSpace(page, (ushort)remainingSpace);
}
public static void InitPage(IPage page, PageHeaderBase header)
{
if (header.Length > page.Length)
{
throw new PageFormatException("Unable to format page. Too large header.");
}
// fill whole page with zero
Array.Clear(page.Content, 0, page.Length);
header.WriteToPage(page);
}
public static void FormatFixedSizeItemsPage(IPage page, PageHeaderBase header, DbItem[] items)
{
var sizeRange = header.SizeRange;
if (items.Any())
{
if (items.Any(item => item.SizeRange != sizeRange))
{
throw new ArgumentException("Size ranges should be equal", nameof(items));
}
}
header.WriteToPage(page);
int remainingSpace =
page.Length - // full page length
header.Length - // subtract header length
items.Length * OnPagePointerSize - OnPagePointerSize; // subtract item length markers array and its length
if (remainingSpace < 0)
{
throw new ArgumentException("Page have no space to add specified items", nameof(items));
}
var maxSize = DbItem.GetMaxSize(sizeRange);
var content = page.Content;
int contentLength = page.Length;
int cnt = items.Length;
int headerLength = header.Length;
for (int index = 0; index < cnt; index++)
{
var rawData = items[index].RawData;
// write the length marker
Buffer.BlockCopy(BitConverter.GetBytes((short)rawData.Length), 0, content, headerLength + OnPagePointerSize * (index + 1), sizeof(short));
// write the body of item
Buffer.BlockCopy(rawData, 0, content, contentLength - maxSize * (index + 1), rawData.Length);
}
// write the length of length marker array
byte[] lengthLengthMarkers = BitConverter.GetBytes((short)cnt);
lengthLengthMarkers.CopyTo(content, headerLength);
}
