public long Update(long id, TableValueBuilder builder)
{
int size = builder.Size;
// first, try to fit in place, either in small or large sections
var prevIsSmall = id % _pageSize != 0;
if (size < ActiveDataSmallSection.MaxItemSize)
{
byte *pos;
if (prevIsSmall && ActiveDataSmallSection.TryWriteDirect(id, size, out pos))
{
int oldDataSize;
var oldData = ActiveDataSmallSection.DirectRead(id, out oldDataSize);
DeleteValueFromIndex(id, new TableValueReader(oldData, oldDataSize));
// MemoryCopy into final position.
builder.CopyTo(pos);
InsertIndexValuesFor(id, new TableValueReader(pos, size));
return(id);
}
}
else if (prevIsSmall == false)
{
var pageNumber = id / _pageSize;
var page = _tx.LowLevelTransaction.GetPage(pageNumber);
var existingNumberOfPages = _tx.LowLevelTransaction.DataPager.GetNumberOfOverflowPages(page.OverflowSize);
var newNumberOfPages = _tx.LowLevelTransaction.DataPager.GetNumberOfOverflowPages(size);
if (existingNumberOfPages == newNumberOfPages)
{
page.OverflowSize = size;
var pos = page.Pointer + sizeof(PageHeader);
DeleteValueFromIndex(id, new TableValueReader(pos, size));
// MemoryCopy into final position.
builder.CopyTo(pos);
InsertIndexValuesFor(id, new TableValueReader(pos, size));
return(id);
}
}
// can't fit in place, will just delete & insert instead
Delete(id);
return(Insert(builder));
}
private static void AssertValueMatches(ActiveRawDataSmallSection section, long id, string expected)
{
int size;
var p = section.DirectRead(id, out size);
var buffer = new byte[size];
fixed(byte *bp = buffer)
{
Memory.Copy(bp, p, size);
}
var actual = Encoding.UTF8.GetString(buffer, 0, size);
Assert.Equal(expected, actual);
}