public bool TryGet(long pageNumber, DecompressionUsage usage, out DecompressedLeafPage decompressed)
{
int position = _current;
int itemsLeft = Size;
while (itemsLeft > 0)
{
var page = _cache[position % Size];
if (page == null)
{
itemsLeft--;
position++;
continue;
}
if (page.PageNumber == pageNumber && page.Usage == usage)
{
Debug.Assert(page.Cached);
decompressed = page;
return(true);
}
itemsLeft--;
position++;
}
decompressed = null;
return(false);
}
public void Add(DecompressedLeafPage decompressed)
{
decompressed.Cached = true;
var itemsLeft = Size;
var position = _current + Size;
DecompressedLeafPage old;
while (itemsLeft > 0)
{
var itemIndex = position % Size;
old = _cache[itemIndex];
if (old == null)
{
_cache[itemIndex] = decompressed;
return;
}
if (old.PageNumber == decompressed.PageNumber && old.Usage == decompressed.Usage)
{
Debug.Assert(old != decompressed);
old.Cached = false;
old.Dispose();
_cache[itemIndex] = decompressed;
return;
}
itemsLeft--;
position--;
}
_current = ++_current % Size;
old = _cache[_current];
if (old != null)
{
Debug.Assert(old != decompressed);
old.Cached = false;
old.Dispose();
}
_cache[_current] = decompressed;
}
public bool TryFindPageForReading(Slice key, LowLevelTransaction tx, out DecompressedLeafPage result)
{
Debug.Assert(key.Options == SliceOptions.Key);
var position = _current;
var itemsLeft = Size;
while (itemsLeft > 0)
{
var page = _cache[position % Size];
if (page == null || page.Usage != DecompressionUsage.Read || page.NumberOfEntries == 0) // decompressed page can has 0 entries if each compressed entry had a tombstone marker
{
itemsLeft--;
position++;
continue;
}
Slice first;
Slice last;
using (page.GetNodeKey(tx, 0, out first))
using (page.GetNodeKey(tx, page.NumberOfEntries - 1, out last))
{
if (SliceComparer.Compare(key, first) >= 0 && SliceComparer.Compare(key, last) <= 0)
{
result = page;
return(true);
}
}
itemsLeft--;
position++;
}
result = null;
return(false);
}
public DecompressedReadResult(ValueReader reader, DecompressedLeafPage page) : base(reader)
{
_page = page;
}