Re: [PATCH v2 04/15] lib min_heap: Add type safe interface

Kent Overstreet
2024-03-21T21:22:21Z

On Thu, Mar 21, 2024 at 07:57:47PM +0800, Kuan-Wei Chiu wrote:
> On Wed, Mar 20, 2024 at 04:56:57PM -0400, Kent Overstreet wrote:
> > On Wed, Mar 20, 2024 at 10:54:06PM +0800, Kuan-Wei Chiu wrote:
> > > Introduce a type-safe interface for min_heap by adding small macro
> > > wrappers around functions and using a 0-size array to store type
> > > information. This enables the use of __minheap_cast and
> > > __minheap_obj_size macros for type casting and obtaining element size.
> > > The implementation draws inspiration from generic-radix-tree.h,
> > > eliminating the need to pass element size in min_heap_callbacks.
> >
> > let's avoid the heap->heap.nr - darray (fs/bcachefs/darray.h) has a
> > trick for that. All heaps have the same memory layout, so we can just
> > cast to a void pointer heap to get something the C code can use.
> >
> If I understand correctly, you're suggesting adding APIs similar to
> darray_top(), darray_first(), and darray_last() within min_heap and
> having them return a pointer. However, some users are using heap.nr in
> conditional statements instead of utilizing heap.nr for memory
> operations, so returning pointers may not be as convenient. What about
> adding get and set functions for nr instead?

No, I mean not having separate inner and outer types. Want me to sketch
something out?