4 * Priority heap containing pointers. Based on CLRS, chapter 6.
6 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
27 #include <linux/slab.h>
28 #include "lttng_prio_heap.h"
31 void lttng_check_heap(const struct lttng_ptr_heap *heap)
38 for (i = 1; i < heap->len; i++)
39 WARN_ON_ONCE(!heap->gt(heap->ptrs[i], heap->ptrs[0]));
44 size_t parent(size_t i)
56 size_t right(size_t i)
62 * Copy of heap->ptrs pointer is invalid after heap_grow.
65 int heap_grow(struct lttng_ptr_heap *heap, size_t new_len)
69 if (heap->alloc_len >= new_len)
72 heap->alloc_len = max_t(size_t, new_len, heap->alloc_len << 1);
73 new_ptrs = kmalloc(heap->alloc_len * sizeof(void *), heap->gfpmask);
77 memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *));
79 heap->ptrs = new_ptrs;
84 int heap_set_len(struct lttng_ptr_heap *heap, size_t new_len)
88 ret = heap_grow(heap, new_len);
95 int lttng_heap_init(struct lttng_ptr_heap *heap, size_t alloc_len,
96 gfp_t gfpmask, int gt(void *a, void *b))
102 heap->gfpmask = gfpmask;
104 * Minimum size allocated is 1 entry to ensure memory allocation
105 * never fails within heap_replace_max.
107 return heap_grow(heap, max_t(size_t, 1, alloc_len));
110 void lttng_heap_free(struct lttng_ptr_heap *heap)
115 static void heapify(struct lttng_ptr_heap *heap, size_t i)
117 void **ptrs = heap->ptrs;
118 size_t l, r, largest;
125 if (l < heap->len && heap->gt(ptrs[l], ptrs[i]))
129 if (r < heap->len && heap->gt(ptrs[r], ptrs[largest]))
134 ptrs[i] = ptrs[largest];
138 lttng_check_heap(heap);
141 void *lttng_heap_replace_max(struct lttng_ptr_heap *heap, void *p)
146 (void) heap_set_len(heap, 1);
148 lttng_check_heap(heap);
152 /* Replace the current max and heapify */
159 int lttng_heap_insert(struct lttng_ptr_heap *heap, void *p)
165 ret = heap_set_len(heap, heap->len + 1);
170 while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) {
171 /* Move parent down until we find the right spot */
172 ptrs[pos] = ptrs[parent(pos)];
176 lttng_check_heap(heap);
180 void *lttng_heap_remove(struct lttng_ptr_heap *heap)
186 (void) heap_set_len(heap, 0);
187 return heap->ptrs[0];
189 /* Shrink, replace the current max by previous last entry and heapify */
190 heap_set_len(heap, heap->len - 1);
191 /* len changed. previous last entry is at heap->len */
192 return lttng_heap_replace_max(heap, heap->ptrs[heap->len]);
195 void *lttng_heap_cherrypick(struct lttng_ptr_heap *heap, void *p)
197 size_t pos, len = heap->len;
199 for (pos = 0; pos < len; pos++)
200 if (heap->ptrs[pos] == p)
204 if (heap->len == 1) {
205 (void) heap_set_len(heap, 0);
206 lttng_check_heap(heap);
207 return heap->ptrs[0];
209 /* Replace p with previous last entry and heapify. */
210 heap_set_len(heap, heap->len - 1);
211 /* len changed. previous last entry is at heap->len */
212 heap->ptrs[pos] = heap->ptrs[heap->len];