Commit | Line | Data |
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1eb0c69c | 1 | /* |
0235b0db | 2 | * SPDX-License-Identifier: MIT |
1eb0c69c | 3 | * |
0235b0db | 4 | * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
1eb0c69c | 5 | * |
0235b0db MJ |
6 | * Static-sized priority heap containing pointers. Based on CLRS, |
7 | * chapter 6. | |
1eb0c69c MD |
8 | */ |
9 | ||
91d81473 | 10 | #include "common/macros.h" |
578e048b | 11 | #include "common/assert.h" |
1eb0c69c MD |
12 | #include <errno.h> |
13 | #include <stdlib.h> | |
14 | #include <string.h> | |
15 | ||
ef5ebbac | 16 | #include "common/prio-heap.h" |
578e048b | 17 | |
eacd552c MD |
18 | #ifdef DEBUG_HEAP |
19 | void check_heap(const struct ptr_heap *heap) | |
20 | { | |
21 | size_t i; | |
22 | ||
23 | if (!heap->len) | |
24 | return; | |
25 | ||
26 | for (i = 1; i < heap->len; i++) | |
98b15851 | 27 | BT_ASSERT_DBG(!heap->gt(heap->ptrs[i], heap->ptrs[0])); |
eacd552c MD |
28 | } |
29 | #endif | |
30 | ||
557255e5 | 31 | static |
1eb0c69c MD |
32 | size_t parent(size_t i) |
33 | { | |
eacd552c | 34 | return (i - 1) >> 1; |
1eb0c69c MD |
35 | } |
36 | ||
37 | static | |
38 | size_t left(size_t i) | |
39 | { | |
eacd552c | 40 | return (i << 1) + 1; |
1eb0c69c MD |
41 | } |
42 | ||
43 | static | |
44 | size_t right(size_t i) | |
45 | { | |
eacd552c | 46 | return (i << 1) + 2; |
1eb0c69c MD |
47 | } |
48 | ||
557255e5 MD |
49 | /* |
50 | * Copy of heap->ptrs pointer is invalid after heap_grow. | |
51 | */ | |
1eb0c69c MD |
52 | static |
53 | int heap_grow(struct ptr_heap *heap, size_t new_len) | |
54 | { | |
55 | void **new_ptrs; | |
56 | ||
91d81473 | 57 | if (G_LIKELY(heap->alloc_len >= new_len)) |
1eb0c69c MD |
58 | return 0; |
59 | ||
91d81473 | 60 | heap->alloc_len = bt_max_t(size_t, new_len, heap->alloc_len << 1); |
1eb0c69c | 61 | new_ptrs = calloc(heap->alloc_len, sizeof(void *)); |
91d81473 | 62 | if (G_UNLIKELY(!new_ptrs)) |
1eb0c69c | 63 | return -ENOMEM; |
91d81473 | 64 | if (G_LIKELY(heap->ptrs)) |
1eb0c69c MD |
65 | memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *)); |
66 | free(heap->ptrs); | |
67 | heap->ptrs = new_ptrs; | |
68 | return 0; | |
69 | } | |
70 | ||
71 | static | |
72 | int heap_set_len(struct ptr_heap *heap, size_t new_len) | |
73 | { | |
74 | int ret; | |
75 | ||
76 | ret = heap_grow(heap, new_len); | |
91d81473 | 77 | if (G_UNLIKELY(ret)) |
1eb0c69c MD |
78 | return ret; |
79 | heap->len = new_len; | |
80 | return 0; | |
81 | } | |
82 | ||
dd06413f | 83 | int bt_heap_init(struct ptr_heap *heap, size_t alloc_len, |
1eb0c69c MD |
84 | int gt(void *a, void *b)) |
85 | { | |
86 | heap->ptrs = NULL; | |
87 | heap->len = 0; | |
88 | heap->alloc_len = 0; | |
89 | heap->gt = gt; | |
90 | /* | |
91 | * Minimum size allocated is 1 entry to ensure memory allocation | |
dd06413f | 92 | * never fails within bt_heap_replace_max. |
1eb0c69c | 93 | */ |
91d81473 | 94 | return heap_grow(heap, bt_max_t(size_t, 1, alloc_len)); |
1eb0c69c MD |
95 | } |
96 | ||
dd06413f | 97 | void bt_heap_free(struct ptr_heap *heap) |
1eb0c69c MD |
98 | { |
99 | free(heap->ptrs); | |
100 | } | |
101 | ||
102 | static void heapify(struct ptr_heap *heap, size_t i) | |
103 | { | |
104 | void **ptrs = heap->ptrs; | |
105 | size_t l, r, largest; | |
106 | ||
107 | for (;;) { | |
eacd552c MD |
108 | void *tmp; |
109 | ||
1eb0c69c MD |
110 | l = left(i); |
111 | r = right(i); | |
eacd552c | 112 | if (l < heap->len && heap->gt(ptrs[l], ptrs[i])) |
1eb0c69c MD |
113 | largest = l; |
114 | else | |
115 | largest = i; | |
eacd552c | 116 | if (r < heap->len && heap->gt(ptrs[r], ptrs[largest])) |
1eb0c69c | 117 | largest = r; |
91d81473 | 118 | if (G_UNLIKELY(largest == i)) |
1eb0c69c | 119 | break; |
eacd552c MD |
120 | tmp = ptrs[i]; |
121 | ptrs[i] = ptrs[largest]; | |
122 | ptrs[largest] = tmp; | |
123 | i = largest; | |
1eb0c69c | 124 | } |
eacd552c | 125 | check_heap(heap); |
1eb0c69c MD |
126 | } |
127 | ||
dd06413f | 128 | void *bt_heap_replace_max(struct ptr_heap *heap, void *p) |
1eb0c69c MD |
129 | { |
130 | void *res; | |
1eb0c69c | 131 | |
91d81473 | 132 | if (G_UNLIKELY(!heap->len)) { |
1eb0c69c | 133 | (void) heap_set_len(heap, 1); |
557255e5 | 134 | heap->ptrs[0] = p; |
eacd552c | 135 | check_heap(heap); |
1eb0c69c MD |
136 | return NULL; |
137 | } | |
138 | ||
139 | /* Replace the current max and heapify */ | |
557255e5 MD |
140 | res = heap->ptrs[0]; |
141 | heap->ptrs[0] = p; | |
1eb0c69c MD |
142 | heapify(heap, 0); |
143 | return res; | |
144 | } | |
145 | ||
dd06413f | 146 | int bt_heap_insert(struct ptr_heap *heap, void *p) |
1eb0c69c | 147 | { |
557255e5 MD |
148 | void **ptrs; |
149 | size_t pos; | |
1eb0c69c MD |
150 | int ret; |
151 | ||
152 | ret = heap_set_len(heap, heap->len + 1); | |
91d81473 | 153 | if (G_UNLIKELY(ret)) |
1eb0c69c | 154 | return ret; |
557255e5 | 155 | ptrs = heap->ptrs; |
557255e5 | 156 | pos = heap->len - 1; |
eacd552c MD |
157 | while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) { |
158 | /* Move parent down until we find the right spot */ | |
159 | ptrs[pos] = ptrs[parent(pos)]; | |
160 | pos = parent(pos); | |
557255e5 | 161 | } |
eacd552c MD |
162 | ptrs[pos] = p; |
163 | check_heap(heap); | |
1eb0c69c MD |
164 | return 0; |
165 | } | |
166 | ||
dd06413f | 167 | void *bt_heap_remove(struct ptr_heap *heap) |
1eb0c69c | 168 | { |
1eb0c69c MD |
169 | switch (heap->len) { |
170 | case 0: | |
171 | return NULL; | |
172 | case 1: | |
173 | (void) heap_set_len(heap, 0); | |
557255e5 | 174 | return heap->ptrs[0]; |
1eb0c69c MD |
175 | } |
176 | /* Shrink, replace the current max by previous last entry and heapify */ | |
177 | heap_set_len(heap, heap->len - 1); | |
eacd552c | 178 | /* len changed. previous last entry is at heap->len */ |
dd06413f | 179 | return bt_heap_replace_max(heap, heap->ptrs[heap->len]); |
1eb0c69c MD |
180 | } |
181 | ||
dd06413f | 182 | void *bt_heap_cherrypick(struct ptr_heap *heap, void *p) |
1eb0c69c | 183 | { |
1eb0c69c MD |
184 | size_t pos, len = heap->len; |
185 | ||
186 | for (pos = 0; pos < len; pos++) | |
91d81473 | 187 | if (G_UNLIKELY(heap->ptrs[pos] == p)) |
1eb0c69c MD |
188 | goto found; |
189 | return NULL; | |
190 | found: | |
91d81473 | 191 | if (G_UNLIKELY(heap->len == 1)) { |
1eb0c69c | 192 | (void) heap_set_len(heap, 0); |
eacd552c | 193 | check_heap(heap); |
557255e5 | 194 | return heap->ptrs[0]; |
1eb0c69c MD |
195 | } |
196 | /* Replace p with previous last entry and heapify. */ | |
197 | heap_set_len(heap, heap->len - 1); | |
eacd552c MD |
198 | /* len changed. previous last entry is at heap->len */ |
199 | heap->ptrs[pos] = heap->ptrs[heap->len]; | |
1eb0c69c MD |
200 | heapify(heap, pos); |
201 | return p; | |
202 | } | |
23a151f0 | 203 | |
dd06413f | 204 | int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src) |
23a151f0 JD |
205 | { |
206 | int ret; | |
207 | ||
dd06413f | 208 | ret = bt_heap_init(dst, src->alloc_len, src->gt); |
23a151f0 JD |
209 | if (ret < 0) |
210 | goto end; | |
211 | ||
212 | ret = heap_set_len(dst, src->len); | |
213 | if (ret < 0) | |
214 | goto end; | |
215 | ||
216 | memcpy(dst->ptrs, src->ptrs, src->len * sizeof(void *)); | |
217 | ||
218 | end: | |
219 | return ret; | |
220 | } |