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charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Mar 22, 2024 at 10:08:59PM -0400, Kent Overstreet wrote: > On Sat, Mar 23, 2024 at 09:53:08AM +0800, Kuan-Wei Chiu wrote: > > On Fri, Mar 22, 2024 at 02:23:26PM -0400, Kent Overstreet wrote: > > > On Sat, Mar 23, 2024 at 01:02:29AM +0800, Kuan-Wei Chiu wrote: > > > > On Thu, Mar 21, 2024 at 05:22:14PM -0400, Kent Overstreet wrote: > > > > > 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? > > > > > > > > Based on your suggestion, I've come up with the following code snippet: > > > > > > > > #define MIN_HEAP_PREALLOCATED(_type, _name, _nr) \ > > > > struct _name { \ > > > > int nr; \ > > > > int size; \ > > > > _type *data; \ > > > > _type preallocated[_nr]; \ > > > > }; > > > > > > > > #define MIN_HEAP(_type, _name) MIN_HEAP_PREALLOCATED(_type, _name, 0) > > > > > > > > typdef MIN_HEAP(char, _) min_heap_char; > > > > > > > > static __always_inline > > > > void min_heap_init(min_heap_char *heap, void *data, int size) > > > > { > > > > heap->nr = 0; > > > > heap->size = size; > > > > heap->data = size <= ARRAY_SIZE(heap->preallocated) ? heap->preallocated : data; > > > > } > > > > > > > > But I'm not sure how to implement other inline functions like > > > > min_heap_push or min_heap_pop if I do that, unless they are rewritten > > > > using macros. Also, I'm not sure how to make the less and swp functions > > > > in the min_heap_callbacks not use void * type parameters. Or perhaps I > > > > misunderstood your meaning again. If you could sketch out your idea or > > > > have a better approach, it would be a great help to me. Any guidance > > > > would be greatly appreciated. > > > > > > No, you're on the right track. To call C functions on different types of > > > heaps you have to cast them all to a common type, say HEAP(char), also > > > pass the element size as a paremeter (which you had to do previously > > > anyways). > > > > The other question I want to ask is, I'm not sure how this relates to > > avoiding the heap->heap.nr. In cases where we need to know the current > > number of elements in the heap, don't we still need to use the same > > method to determine the number of elements? > > Yes, but this eliminates the nested types; so it's just heap->nr. > > It's a pretty minor detail, cosmetic really, but I managed it in darray > so it'd be nice to have here as well :) Ah, got it. I'll make that change in v3. Regards, Kuan-Wei