/// <summary>
/// Constructs an allocator.
/// </summary>
/// <param name="budgetInBytes">Budget of the allocator in bytes.</param>
/// <param name="bufferSizeInBytes">Size of each buffer to be allocated in bytes.</param>
/// <param name="handle">An AllocatorHandle to use for internal bookkeeping structures.</param>
/// <exception cref="InvalidOperationException">Thrown if the allocator cannot reserve the address range required for the given budget.</exception>
public BufferAllocator(int budgetInBytes, int bufferSizeInBytes, AllocatorManager.AllocatorHandle handle)
{
BufferSizeInBytes = bufferSizeInBytes;
// Reserve the entire budget's worth of address space. The reserved space may be larger than the budget
// due to page sizes.
var pageCount = VirtualMemoryUtility.BytesToPageCount((uint)budgetInBytes, VirtualMemoryUtility.DefaultPageSizeInBytes);
BaselibErrorState errorState;
ReservedRange = VirtualMemoryUtility.ReserveAddressSpace(pageCount, VirtualMemoryUtility.DefaultPageSizeInBytes, out errorState);
#if ENABLE_UNITY_COLLECTIONS_CHECKS
if (!errorState.Success)
{
throw new InvalidOperationException($"Failed to reserve address range for {budgetInBytes} bytes");
}
#endif
// Init a free list of blocks.
MaxBufferCount = (int)VirtualMemoryUtility.BytesToPageCount((uint)budgetInBytes, (uint)bufferSizeInBytes);
FreeList = new UnsafeIntList(MaxBufferCount, handle);
for (int i = MaxBufferCount - 1; i >= 0; --i)
{
FreeList.Add(i);
}
}
