/// <summary>
/// Allocates a handle for data, you MUST call Write to commit the handle, otherwise the handle
/// may be reallocated after closing and re-opening this file. If you do not intend to commit
/// the handle by writing to it, you should still call Delete() so that it may be reused.
/// </summary>
public uint Create()
{
uint handle = 0;
lock (_sync)
{
while (handle == 0)
{
foreach (int i in _freeHandles.EnumerateFrom(_prevFreeHandle))
{
_freeHandles.Remove(i);
_prevFreeHandle = i + 1;
handle = (uint)i;
break;
}
if (handle == 0)
{
AddSection();
}
}
}
HandleRef href = new HandleRef(handle, BlockSize);
uint blockId = _sections[href.Section][href.Offset];
if (blockId != 0)
{
throw new InvalidDataException();
}
return(handle);
}
private uint TakeBlocks(int blocksNeeded)
{
lock (_sync)
{
bool resized = false;
while (true)
{
int found = 0;
int last = int.MinValue;
int first = int.MaxValue;
foreach (int free in _freeBlocks.EnumerateFrom(_prevFreeBlock))
{
if (_reservedBlocks.Contains(free))
{
continue;
}
first = Math.Min(first, free);
found = (last + 1 != free) ? 1 : found + 1;
last = free;
if (found == blocksNeeded)
{
_prevFreeBlock = first;
int start = free - (blocksNeeded - 1);
for (int i = start; i <= free; i++)
{
_freeBlocks.Remove(i);
}
uint blockId = (uint)start;
blockId |= ((uint)Math.Min(16, blocksNeeded) - 1 << 28) & 0xF0000000u;
return(blockId);
}
}
if (resized)
{
throw new ArgumentOutOfRangeException("length");
}
resized = true;
AddSection();
}
}
}
