public void FixedSizeItemsPage()
{
int pageSize = 32768;
var dummyPageManager = new FileSystemPageManager(pageSize);
var p = new Page(dummyPageManager, 0, new byte[pageSize]);
var header = new FixedSizeItemsPageHeader();
var r = new Random();
foreach (var sizeRange in EnumHelper.FixedSizeItemsSizeRanges())
{
header.SizeRange = sizeRange;
PageFormatter.InitPage(p, header);
var item = new DbItem(new byte[DbItem.GetMaxSize(header.SizeRange)]);
r.NextBytes(item.RawData);
// fill the page with the items
short count = 0;
bool spaceRemains = true;
while (PageFormatter.HasFreeSpaceForFixedSizeItem(p))
{
Assert.IsTrue(spaceRemains);
PageFormatter.AddFixedSizeItem(p, item, out spaceRemains);
count++;
Assert.AreEqual(count, PageFormatter.ReadFixedSizeItemsCount(p));
}
Assert.IsFalse(spaceRemains);
// check if fetched objects are equal to originals
for (short j = 0; j < PageFormatter.ReadFixedSizeItemsCount(p); j++)
{
DbItem readItem = PageFormatter.ReadFixedSizeItem(p, j);
Assert.IsTrue(AreEqualByteArrays(item.RawData, readItem.RawData));
}
// delete all added items
short itemindex = 0;
while (PageFormatter.ReadFixedSizeItemsCount(p) > 0)
{
PageFormatter.DeleteFixedSizeItem(p, itemindex);
count--;
itemindex++;
Assert.AreEqual(count, PageFormatter.ReadFixedSizeItemsCount(p));
}
}
}
/// <summary>
/// Gets DbItem instance by reference.
/// </summary>
/// <param name="reference">Reference to the requested db item</param>
/// <returns></returns>
public DbItem Get(DbItemReference reference)
{
if (!_pageManager.PageExists(reference.PageIndex))
{
return(null);
}
IPage page = _pageManager.FetchPage(reference.PageIndex);
var header = PageFormatter.GetPageHeader(page);
if (header.SizeRange == SizeRange.MultiPage)
{
var length = PageFormatter.ReadMultipageItemLength(page);
var content = new byte[length];
long offset = 0;
while (page != null)
{
var readBytes = PageFormatter.ReadMultipageItemBlock(page, Math.Min(_pageManager.PageSize, (int)(length - offset)));
readBytes.CopyTo(content, offset);
offset += readBytes.Length;
var nextPageIndex = ((MultipageItemPageHeader)header).NextPageIndex;
if (nextPageIndex != -1)
{
page = _pageManager.FetchPage(nextPageIndex);
header = PageFormatter.GetPageHeader(page);
}
else
{
page = null;
}
}
return(new DbItem(content));
}
return(PageFormatter.IsFixedSizeItemAllocated(page, reference.ItemIndex)
? PageFormatter.ReadFixedSizeItem(page, reference.ItemIndex)
: null);
}
private byte[] GetFixedSizeItemSegment(IPage page, DbItemReference reference, long startIndex, long endIndex)
{
if (!PageFormatter.IsFixedSizeItemAllocated(page, reference.ItemIndex))
{
return new byte[] { }
}
;
var item = PageFormatter.ReadFixedSizeItem(page, reference.ItemIndex);
if (item.RawData.Length >= endIndex)
{
throw new ArgumentOutOfRangeException(nameof(endIndex));
}
var length = endIndex - startIndex + 1;
var result = new byte[length];
Array.Copy(item.RawData, startIndex, result, 0, length);
return(result);
}
