public UnamangedMemoryAccessor(int size)
{
size = Info.GetPowerOfTwo(size);// we ensure power of 2 to make sure that we don't fragment the _unmanaged_ heap
IntPtr allocHGlobal;
try
{
allocHGlobal = Marshal.AllocHGlobal(size);
}
catch (Exception)
{
GC.SuppressFinalize(this);
throw;
}
_memHandles[0] = new UnamagedMemory
{
Ptr = allocHGlobal,
Remaining = size,
Size = size
};
}
private int GetIndexOfHandleWithEnoughSpace(Stream stream)
{
int memIndex = 0;
var length = (int) stream.Length;
for (; memIndex < _memHandles.Length; memIndex++)
{
if (length < _memHandles[memIndex].Remaining)
return memIndex;
}
// couldn't find any space left, need to allocate more
// this should only happen _once_, since afterward, we would freeze
// the mem table. The code is ready to handle multiple uses, none the less
var newMemHandles = new UnamagedMemory[memIndex + 1];
Array.Copy(_memHandles, 0, newMemHandles, 0, _memHandles.Length);
var size = Info.GetPowerOfTwo(length);// we ensure power of 2 to make sure that we don't fragment the _unmanaged_ heap
var newMemHandle = new UnamagedMemory
{
Remaining = size,
Size = size
};
newMemHandles[memIndex] = newMemHandle;
try
{
newMemHandle.Ptr = Marshal.AllocHGlobal(size);
Volatile.Write(ref _memHandles, newMemHandles);
}
catch (Exception)
{
if (newMemHandle.Ptr != IntPtr.Zero)
Marshal.FreeHGlobal(newMemHandle.Ptr);
throw;
}
return memIndex;
}
