public PageLocatorCurrent(LowLevelTransactionStub tx, int cacheSize = 8)
{
//Debug.Assert(tx != null);
//Debug.Assert(cacheSize > 0);
_tx = tx;
if (tx != null)
{
Debug.Fail("");
}
cacheSize = Bits.NextPowerOf2(cacheSize);
if (cacheSize > 1024)
{
cacheSize = 1024;
}
int shiftRight = Bits.CeilLog2(cacheSize);
_andMask = (int)(0xFFFFFFFF >> (sizeof(uint) * 8 - shiftRight));
_tx = tx;
_allocator.Allocate(cacheSize * sizeof(PageData), out _cacheMemory);
_cache = (PageData *)_cacheMemory.Ptr;
for (var i = 0; i < cacheSize; i++)
{
_cache[i].PageNumber = Invalid;
}
}
public void Renew(LowLevelTransaction tx, int cacheSize)
{
Debug.Assert(tx != null);
Debug.Assert(cacheSize > 0);
Debug.Assert(cacheSize <= 1024);
if (!Bits.IsPowerOfTwo(cacheSize))
{
cacheSize = Bits.NextPowerOf2(cacheSize);
}
int shiftRight = Bits.CeilLog2(cacheSize);
_andMask = (int)(0xFFFFFFFF >> (sizeof(uint) * 8 - shiftRight));
_tx = tx;
tx.Allocator.Allocate(cacheSize * sizeof(PageData), out _cacheMemory);
_cache = (PageData *)_cacheMemory.Ptr;
for (var i = 0; i < cacheSize; i++)
{
_cache[i].PageNumber = Invalid;
}
}
public void Release()
{
if (_tx == null)
{
return;
}
_tx.Allocator.Release(ref _cacheMemory);
_tx = null;
_cache = null;
}
public void SetWritable(long pageNumber, Page page)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->PageNumber != pageNumber || node->IsWritable == false)
{
node->PageNumber = pageNumber;
node->Page = page;
node->IsWritable = true;
}
}
public bool TryGetWritablePage(long pageNumber, out Page page)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->IsWritable && node->PageNumber == pageNumber && node->PageNumber != Invalid)
{
page = node->Page;
return(true);
}
page = default(Page);
return(false);
}
public bool TryGetReadOnlyPage(long pageNumber, out Page page)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->PageNumber == pageNumber)
{
page = node->Page;
return(true);
}
page = default(Page);
return(false);
}
public MyPageStruct GetWritablePage(long pageNumber)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->IsWritable && node->PageNumber == pageNumber)
{
return(node->Page);
}
var page = LowLevelTransactionStub.ModifyPageStruct(pageNumber);
node->PageNumber = pageNumber;
node->Page = page;
node->IsWritable = true;
return(page);
}
public Page GetReadOnlyPage(long pageNumber)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->PageNumber == pageNumber)
{
return(node->Page);
}
var page = _tx.GetPage(pageNumber);
node->PageNumber = pageNumber;
node->Page = page;
node->IsWritable = false;
return(page);
}
public Page GetWritablePage(long pageNumber)
{
var position = pageNumber & _andMask;
PageData *node = &_cache[position];
if (node->IsWritable && node->PageNumber == pageNumber)
{
return(node->Page);
}
var page = _tx.ModifyPage(pageNumber);
node->PageNumber = pageNumber;
node->Page = page;
node->IsWritable = true;
return(page);
}
