Commit | Line | Data |
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1eb0c69c MD |
1 | /* |
2 | * prio_heap.c | |
3 | * | |
4 | * Static-sized priority heap containing pointers. Based on CLRS, | |
5 | * chapter 6. | |
6 | * | |
7 | * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
8 | * | |
9 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
10 | * of this software and associated documentation files (the "Software"), to deal | |
11 | * in the Software without restriction, including without limitation the rights | |
12 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
13 | * copies of the Software, and to permit persons to whom the Software is | |
14 | * furnished to do so, subject to the following conditions: | |
15 | * | |
16 | * The above copyright notice and this permission notice shall be included in | |
17 | * all copies or substantial portions of the Software. | |
c462e188 MD |
18 | * |
19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
20 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
21 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
22 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
23 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
24 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
25 | * SOFTWARE. | |
1eb0c69c MD |
26 | */ |
27 | ||
3d9990ac | 28 | #include <babeltrace/prio-heap-internal.h> |
96e1cf26 | 29 | #include <babeltrace/babeltrace-internal.h> |
f6ccaed9 | 30 | #include <babeltrace/assert-internal.h> |
1eb0c69c MD |
31 | #include <errno.h> |
32 | #include <stdlib.h> | |
33 | #include <string.h> | |
34 | ||
eacd552c MD |
35 | #ifdef DEBUG_HEAP |
36 | void check_heap(const struct ptr_heap *heap) | |
37 | { | |
38 | size_t i; | |
39 | ||
40 | if (!heap->len) | |
41 | return; | |
42 | ||
43 | for (i = 1; i < heap->len; i++) | |
f6ccaed9 | 44 | BT_ASSERT(!heap->gt(heap->ptrs[i], heap->ptrs[0])); |
eacd552c MD |
45 | } |
46 | #endif | |
47 | ||
557255e5 | 48 | static |
1eb0c69c MD |
49 | size_t parent(size_t i) |
50 | { | |
eacd552c | 51 | return (i - 1) >> 1; |
1eb0c69c MD |
52 | } |
53 | ||
54 | static | |
55 | size_t left(size_t i) | |
56 | { | |
eacd552c | 57 | return (i << 1) + 1; |
1eb0c69c MD |
58 | } |
59 | ||
60 | static | |
61 | size_t right(size_t i) | |
62 | { | |
eacd552c | 63 | return (i << 1) + 2; |
1eb0c69c MD |
64 | } |
65 | ||
557255e5 MD |
66 | /* |
67 | * Copy of heap->ptrs pointer is invalid after heap_grow. | |
68 | */ | |
1eb0c69c MD |
69 | static |
70 | int heap_grow(struct ptr_heap *heap, size_t new_len) | |
71 | { | |
72 | void **new_ptrs; | |
73 | ||
96e1cf26 | 74 | if (likely(heap->alloc_len >= new_len)) |
1eb0c69c MD |
75 | return 0; |
76 | ||
77 | heap->alloc_len = max_t(size_t, new_len, heap->alloc_len << 1); | |
78 | new_ptrs = calloc(heap->alloc_len, sizeof(void *)); | |
96e1cf26 | 79 | if (unlikely(!new_ptrs)) |
1eb0c69c | 80 | return -ENOMEM; |
96e1cf26 | 81 | if (likely(heap->ptrs)) |
1eb0c69c MD |
82 | memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *)); |
83 | free(heap->ptrs); | |
84 | heap->ptrs = new_ptrs; | |
85 | return 0; | |
86 | } | |
87 | ||
88 | static | |
89 | int heap_set_len(struct ptr_heap *heap, size_t new_len) | |
90 | { | |
91 | int ret; | |
92 | ||
93 | ret = heap_grow(heap, new_len); | |
96e1cf26 | 94 | if (unlikely(ret)) |
1eb0c69c MD |
95 | return ret; |
96 | heap->len = new_len; | |
97 | return 0; | |
98 | } | |
99 | ||
dd06413f | 100 | int bt_heap_init(struct ptr_heap *heap, size_t alloc_len, |
1eb0c69c MD |
101 | int gt(void *a, void *b)) |
102 | { | |
103 | heap->ptrs = NULL; | |
104 | heap->len = 0; | |
105 | heap->alloc_len = 0; | |
106 | heap->gt = gt; | |
107 | /* | |
108 | * Minimum size allocated is 1 entry to ensure memory allocation | |
dd06413f | 109 | * never fails within bt_heap_replace_max. |
1eb0c69c MD |
110 | */ |
111 | return heap_grow(heap, max_t(size_t, 1, alloc_len)); | |
112 | } | |
113 | ||
dd06413f | 114 | void bt_heap_free(struct ptr_heap *heap) |
1eb0c69c MD |
115 | { |
116 | free(heap->ptrs); | |
117 | } | |
118 | ||
119 | static void heapify(struct ptr_heap *heap, size_t i) | |
120 | { | |
121 | void **ptrs = heap->ptrs; | |
122 | size_t l, r, largest; | |
123 | ||
124 | for (;;) { | |
eacd552c MD |
125 | void *tmp; |
126 | ||
1eb0c69c MD |
127 | l = left(i); |
128 | r = right(i); | |
eacd552c | 129 | if (l < heap->len && heap->gt(ptrs[l], ptrs[i])) |
1eb0c69c MD |
130 | largest = l; |
131 | else | |
132 | largest = i; | |
eacd552c | 133 | if (r < heap->len && heap->gt(ptrs[r], ptrs[largest])) |
1eb0c69c | 134 | largest = r; |
96e1cf26 | 135 | if (unlikely(largest == i)) |
1eb0c69c | 136 | break; |
eacd552c MD |
137 | tmp = ptrs[i]; |
138 | ptrs[i] = ptrs[largest]; | |
139 | ptrs[largest] = tmp; | |
140 | i = largest; | |
1eb0c69c | 141 | } |
eacd552c | 142 | check_heap(heap); |
1eb0c69c MD |
143 | } |
144 | ||
dd06413f | 145 | void *bt_heap_replace_max(struct ptr_heap *heap, void *p) |
1eb0c69c MD |
146 | { |
147 | void *res; | |
1eb0c69c | 148 | |
96e1cf26 | 149 | if (unlikely(!heap->len)) { |
1eb0c69c | 150 | (void) heap_set_len(heap, 1); |
557255e5 | 151 | heap->ptrs[0] = p; |
eacd552c | 152 | check_heap(heap); |
1eb0c69c MD |
153 | return NULL; |
154 | } | |
155 | ||
156 | /* Replace the current max and heapify */ | |
557255e5 MD |
157 | res = heap->ptrs[0]; |
158 | heap->ptrs[0] = p; | |
1eb0c69c MD |
159 | heapify(heap, 0); |
160 | return res; | |
161 | } | |
162 | ||
dd06413f | 163 | int bt_heap_insert(struct ptr_heap *heap, void *p) |
1eb0c69c | 164 | { |
557255e5 MD |
165 | void **ptrs; |
166 | size_t pos; | |
1eb0c69c MD |
167 | int ret; |
168 | ||
169 | ret = heap_set_len(heap, heap->len + 1); | |
96e1cf26 | 170 | if (unlikely(ret)) |
1eb0c69c | 171 | return ret; |
557255e5 | 172 | ptrs = heap->ptrs; |
557255e5 | 173 | pos = heap->len - 1; |
eacd552c MD |
174 | while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) { |
175 | /* Move parent down until we find the right spot */ | |
176 | ptrs[pos] = ptrs[parent(pos)]; | |
177 | pos = parent(pos); | |
557255e5 | 178 | } |
eacd552c MD |
179 | ptrs[pos] = p; |
180 | check_heap(heap); | |
1eb0c69c MD |
181 | return 0; |
182 | } | |
183 | ||
dd06413f | 184 | void *bt_heap_remove(struct ptr_heap *heap) |
1eb0c69c | 185 | { |
1eb0c69c MD |
186 | switch (heap->len) { |
187 | case 0: | |
188 | return NULL; | |
189 | case 1: | |
190 | (void) heap_set_len(heap, 0); | |
557255e5 | 191 | return heap->ptrs[0]; |
1eb0c69c MD |
192 | } |
193 | /* Shrink, replace the current max by previous last entry and heapify */ | |
194 | heap_set_len(heap, heap->len - 1); | |
eacd552c | 195 | /* len changed. previous last entry is at heap->len */ |
dd06413f | 196 | return bt_heap_replace_max(heap, heap->ptrs[heap->len]); |
1eb0c69c MD |
197 | } |
198 | ||
dd06413f | 199 | void *bt_heap_cherrypick(struct ptr_heap *heap, void *p) |
1eb0c69c | 200 | { |
1eb0c69c MD |
201 | size_t pos, len = heap->len; |
202 | ||
203 | for (pos = 0; pos < len; pos++) | |
96e1cf26 | 204 | if (unlikely(heap->ptrs[pos] == p)) |
1eb0c69c MD |
205 | goto found; |
206 | return NULL; | |
207 | found: | |
96e1cf26 | 208 | if (unlikely(heap->len == 1)) { |
1eb0c69c | 209 | (void) heap_set_len(heap, 0); |
eacd552c | 210 | check_heap(heap); |
557255e5 | 211 | return heap->ptrs[0]; |
1eb0c69c MD |
212 | } |
213 | /* Replace p with previous last entry and heapify. */ | |
214 | heap_set_len(heap, heap->len - 1); | |
eacd552c MD |
215 | /* len changed. previous last entry is at heap->len */ |
216 | heap->ptrs[pos] = heap->ptrs[heap->len]; | |
1eb0c69c MD |
217 | heapify(heap, pos); |
218 | return p; | |
219 | } | |
23a151f0 | 220 | |
dd06413f | 221 | int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src) |
23a151f0 JD |
222 | { |
223 | int ret; | |
224 | ||
dd06413f | 225 | ret = bt_heap_init(dst, src->alloc_len, src->gt); |
23a151f0 JD |
226 | if (ret < 0) |
227 | goto end; | |
228 | ||
229 | ret = heap_set_len(dst, src->len); | |
230 | if (ret < 0) | |
231 | goto end; | |
232 | ||
233 | memcpy(dst->ptrs, src->ptrs, src->len * sizeof(void *)); | |
234 | ||
235 | end: | |
236 | return ret; | |
237 | } |