public unsafe Report GetNumberOfPreAllocatedFreePages()
{
var fst = _parentTree.FixedTreeFor(AllocationStorage, valSize: BitmapSize);
if (fst.NumberOfEntries == 0)
{
return(new Report());
}
var free = 0;
using (var it = fst.Iterate())
{
if (it.Seek(long.MinValue) == false)
{
throw new InvalidOperationException($"Could not seek to the first element of {fst.Name} tree");
}
Slice slice;
using (it.Value(out slice))
{
byte *ptr = slice.Content.Ptr;
for (int i = 0; i < NumberOfPagesInSection; i++)
{
if (PtrBitVector.GetBitInPointer(ptr, i) == false)
{
free++;
}
}
}
}
int amountOfPagesActuallyAllocated = GetNumberOfPagesToAllocate();
return(new Report
{
NumberOfOriginallyAllocatedPages = fst.NumberOfEntries * amountOfPagesActuallyAllocated,
NumberOfFreePages = free
});
}
public unsafe Page AllocateSinglePage(long nearbyPage)
{
var fst = _parentTree.FixedTreeFor(AllocationStorage, valSize: BitmapSize);
using (var it = fst.Iterate())
{
Page page;
if (it.Seek(nearbyPage)) // found a value >= from the nearby page
{
if (it.CurrentKey > nearbyPage)
{
// go back one step if we can
if (it.MovePrev() == false)
{
it.Seek(nearbyPage); // if we can't, go back to the original find
}
}
}
else // probably it is on the last entry, after the first page, so we'll use the last entry
{
if (it.SeekToLast() == false)
{
// shouldn't actuallly happen, but same behavior as running out of space
page = AllocateMoreSpace(fst);
SetValue(fst, page.PageNumber, 0);
return(page);
}
}
var startPage = it.CurrentKey;
while (true)
{
Slice slice;
using (it.Value(out slice))
{
var hasSpace = false;
var buffer = (ulong *)(slice.Content.Ptr);
for (int i = 0; i < BitmapSize / sizeof(ulong); i++)
{
if (buffer[i] != ulong.MaxValue)
{
hasSpace = true;
break;
}
}
if (hasSpace == false)
{
if (TryMoveNextCyclic(it, startPage) == false)
{
break;
}
}
for (int i = 0; i < BitmapSize * 8; i++)
{
if (PtrBitVector.GetBitInPointer(buffer, i) == false)
{
var currentSectionStart = it.CurrentKey;
SetValue(fst, currentSectionStart, i);
return(_llt.ModifyPage(currentSectionStart + i));
}
}
if (TryMoveNextCyclic(it, startPage) == false)
{
break;
}
}
}
page = AllocateMoreSpace(fst);
SetValue(fst, page.PageNumber, 0);
return(page);
}
}