linux-kernel - Re: [PATCH 11/13] lib min_heap: Add min_heap

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Date: Tue, 19 Mar 2024 12:59:32 -0700
From: Ian Rogers <irogers@...gle.com>
To: Kuan-Wei Chiu <visitorckw@...il.com>
Cc: colyli@...e.de, kent.overstreet@...ux.dev, msakai@...hat.com, 
	peterz@...radead.org, mingo@...hat.com, acme@...nel.org, namhyung@...nel.org, 
	akpm@...ux-foundation.org, bfoster@...hat.com, mark.rutland@....com, 
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org, adrian.hunter@...el.com, 
	jserv@...s.ncku.edu.tw, linux-bcache@...r.kernel.org, 
	dm-devel@...ts.linux.dev, linux-bcachefs@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/13] lib min_heap: Add min_heap_del()

On Tue, Mar 19, 2024 at 11:01 AM Kuan-Wei Chiu <visitorckw@...il.com> wrote:
>
> Add min_heap_del() to delete the element at index 'idx' in the heap.
>
> Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>

Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  include/linux/min_heap.h | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
> index 154ac2102114..ce085137fce7 100644
> --- a/include/linux/min_heap.h
> +++ b/include/linux/min_heap.h
> @@ -199,4 +199,28 @@ bool __min_heap_push(struct __min_heap *heap, const void *element, size_t elem_s
>  #define min_heap_push(_heap, _element, _func, _args)   \
>         __min_heap_push(&(_heap)->heap, _element, __minheap_obj_size(_heap), _func, _args)
>
> +/* Remove ith element from the heap, O(log2(nr)). */
> +static __always_inline
> +bool __min_heap_del(struct __min_heap *heap, size_t elem_size, size_t idx,
> +               const struct min_heap_callbacks *func, void *args)
> +{
> +       void *data = heap->data;
> +
> +       if (WARN_ONCE(heap->nr <= 0, "Popping an empty heap"))
> +               return false;
> +
> +       /* Place last element at the root (position 0) and then sift down */
> +       heap->nr--;
> +       if (idx == heap->nr)
> +               return true;
> +       memcpy(data, data + (heap->nr * elem_size), elem_size);
> +       __min_heap_sift_up(heap, elem_size, idx, func, args);
> +       __min_heapify(heap, idx, elem_size, func, args);
> +
> +       return true;
> +}
> +
> +#define min_heap_del(_heap, _idx, _func, _args)        \
> +       __min_heap_del(&(_heap)->heap, __minheap_obj_size(_heap), _idx, _func, _args)
> +
>  #endif /* _LINUX_MIN_HEAP_H */
> --
> 2.34.1
>