Commit | Line | Data |
---|---|---|
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 | ||
28 | #include <babeltrace/prio_heap.h> | |
96e1cf26 | 29 | #include <babeltrace/babeltrace-internal.h> |
1eb0c69c MD |
30 | #include <errno.h> |
31 | #include <stdlib.h> | |
32 | #include <string.h> | |
eacd552c | 33 | #include <assert.h> |
1eb0c69c MD |
34 | |
35 | #ifndef max_t | |
36 | #define max_t(type, a, b) \ | |
37 | ((type) (a) > (type) (b) ? (type) (a) : (type) (b)) | |
38 | #endif | |
39 | ||
eacd552c MD |
40 | #ifdef DEBUG_HEAP |
41 | void check_heap(const struct ptr_heap *heap) | |
42 | { | |
43 | size_t i; | |
44 | ||
45 | if (!heap->len) | |
46 | return; | |
47 | ||
48 | for (i = 1; i < heap->len; i++) | |
49 | assert(!heap->gt(heap->ptrs[i], heap->ptrs[0])); | |
50 | } | |
51 | #endif | |
52 | ||
557255e5 | 53 | static |
1eb0c69c MD |
54 | size_t parent(size_t i) |
55 | { | |
eacd552c | 56 | return (i - 1) >> 1; |
1eb0c69c MD |
57 | } |
58 | ||
59 | static | |
60 | size_t left(size_t i) | |
61 | { | |
eacd552c | 62 | return (i << 1) + 1; |
1eb0c69c MD |
63 | } |
64 | ||
65 | static | |
66 | size_t right(size_t i) | |
67 | { | |
eacd552c | 68 | return (i << 1) + 2; |
1eb0c69c MD |
69 | } |
70 | ||
557255e5 MD |
71 | /* |
72 | * Copy of heap->ptrs pointer is invalid after heap_grow. | |
73 | */ | |
1eb0c69c MD |
74 | static |
75 | int heap_grow(struct ptr_heap *heap, size_t new_len) | |
76 | { | |
77 | void **new_ptrs; | |
78 | ||
96e1cf26 | 79 | if (likely(heap->alloc_len >= new_len)) |
1eb0c69c MD |
80 | return 0; |
81 | ||
82 | heap->alloc_len = max_t(size_t, new_len, heap->alloc_len << 1); | |
83 | new_ptrs = calloc(heap->alloc_len, sizeof(void *)); | |
96e1cf26 | 84 | if (unlikely(!new_ptrs)) |
1eb0c69c | 85 | return -ENOMEM; |
96e1cf26 | 86 | if (likely(heap->ptrs)) |
1eb0c69c MD |
87 | memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *)); |
88 | free(heap->ptrs); | |
89 | heap->ptrs = new_ptrs; | |
90 | return 0; | |
91 | } | |
92 | ||
93 | static | |
94 | int heap_set_len(struct ptr_heap *heap, size_t new_len) | |
95 | { | |
96 | int ret; | |
97 | ||
98 | ret = heap_grow(heap, new_len); | |
96e1cf26 | 99 | if (unlikely(ret)) |
1eb0c69c MD |
100 | return ret; |
101 | heap->len = new_len; | |
102 | return 0; | |
103 | } | |
104 | ||
dd06413f | 105 | int bt_heap_init(struct ptr_heap *heap, size_t alloc_len, |
1eb0c69c MD |
106 | int gt(void *a, void *b)) |
107 | { | |
108 | heap->ptrs = NULL; | |
109 | heap->len = 0; | |
110 | heap->alloc_len = 0; | |
111 | heap->gt = gt; | |
112 | /* | |
113 | * Minimum size allocated is 1 entry to ensure memory allocation | |
dd06413f | 114 | * never fails within bt_heap_replace_max. |
1eb0c69c MD |
115 | */ |
116 | return heap_grow(heap, max_t(size_t, 1, alloc_len)); | |
117 | } | |
118 | ||
dd06413f | 119 | void bt_heap_free(struct ptr_heap *heap) |
1eb0c69c MD |
120 | { |
121 | free(heap->ptrs); | |
122 | } | |
123 | ||
124 | static void heapify(struct ptr_heap *heap, size_t i) | |
125 | { | |
126 | void **ptrs = heap->ptrs; | |
127 | size_t l, r, largest; | |
128 | ||
129 | for (;;) { | |
eacd552c MD |
130 | void *tmp; |
131 | ||
1eb0c69c MD |
132 | l = left(i); |
133 | r = right(i); | |
eacd552c | 134 | if (l < heap->len && heap->gt(ptrs[l], ptrs[i])) |
1eb0c69c MD |
135 | largest = l; |
136 | else | |
137 | largest = i; | |
eacd552c | 138 | if (r < heap->len && heap->gt(ptrs[r], ptrs[largest])) |
1eb0c69c | 139 | largest = r; |
96e1cf26 | 140 | if (unlikely(largest == i)) |
1eb0c69c | 141 | break; |
eacd552c MD |
142 | tmp = ptrs[i]; |
143 | ptrs[i] = ptrs[largest]; | |
144 | ptrs[largest] = tmp; | |
145 | i = largest; | |
1eb0c69c | 146 | } |
eacd552c | 147 | check_heap(heap); |
1eb0c69c MD |
148 | } |
149 | ||
dd06413f | 150 | void *bt_heap_replace_max(struct ptr_heap *heap, void *p) |
1eb0c69c MD |
151 | { |
152 | void *res; | |
1eb0c69c | 153 | |
96e1cf26 | 154 | if (unlikely(!heap->len)) { |
1eb0c69c | 155 | (void) heap_set_len(heap, 1); |
557255e5 | 156 | heap->ptrs[0] = p; |
eacd552c | 157 | check_heap(heap); |
1eb0c69c MD |
158 | return NULL; |
159 | } | |
160 | ||
161 | /* Replace the current max and heapify */ | |
557255e5 MD |
162 | res = heap->ptrs[0]; |
163 | heap->ptrs[0] = p; | |
1eb0c69c MD |
164 | heapify(heap, 0); |
165 | return res; | |
166 | } | |
167 | ||
dd06413f | 168 | int bt_heap_insert(struct ptr_heap *heap, void *p) |
1eb0c69c | 169 | { |
557255e5 MD |
170 | void **ptrs; |
171 | size_t pos; | |
1eb0c69c MD |
172 | int ret; |
173 | ||
174 | ret = heap_set_len(heap, heap->len + 1); | |
96e1cf26 | 175 | if (unlikely(ret)) |
1eb0c69c | 176 | return ret; |
557255e5 | 177 | ptrs = heap->ptrs; |
557255e5 | 178 | pos = heap->len - 1; |
eacd552c MD |
179 | while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) { |
180 | /* Move parent down until we find the right spot */ | |
181 | ptrs[pos] = ptrs[parent(pos)]; | |
182 | pos = parent(pos); | |
557255e5 | 183 | } |
eacd552c MD |
184 | ptrs[pos] = p; |
185 | check_heap(heap); | |
1eb0c69c MD |
186 | return 0; |
187 | } | |
188 | ||
dd06413f | 189 | void *bt_heap_remove(struct ptr_heap *heap) |
1eb0c69c | 190 | { |
1eb0c69c MD |
191 | switch (heap->len) { |
192 | case 0: | |
193 | return NULL; | |
194 | case 1: | |
195 | (void) heap_set_len(heap, 0); | |
557255e5 | 196 | return heap->ptrs[0]; |
1eb0c69c MD |
197 | } |
198 | /* Shrink, replace the current max by previous last entry and heapify */ | |
199 | heap_set_len(heap, heap->len - 1); | |
eacd552c | 200 | /* len changed. previous last entry is at heap->len */ |
dd06413f | 201 | return bt_heap_replace_max(heap, heap->ptrs[heap->len]); |
1eb0c69c MD |
202 | } |
203 | ||
dd06413f | 204 | void *bt_heap_cherrypick(struct ptr_heap *heap, void *p) |
1eb0c69c | 205 | { |
1eb0c69c MD |
206 | size_t pos, len = heap->len; |
207 | ||
208 | for (pos = 0; pos < len; pos++) | |
96e1cf26 | 209 | if (unlikely(heap->ptrs[pos] == p)) |
1eb0c69c MD |
210 | goto found; |
211 | return NULL; | |
212 | found: | |
96e1cf26 | 213 | if (unlikely(heap->len == 1)) { |
1eb0c69c | 214 | (void) heap_set_len(heap, 0); |
eacd552c | 215 | check_heap(heap); |
557255e5 | 216 | return heap->ptrs[0]; |
1eb0c69c MD |
217 | } |
218 | /* Replace p with previous last entry and heapify. */ | |
219 | heap_set_len(heap, heap->len - 1); | |
eacd552c MD |
220 | /* len changed. previous last entry is at heap->len */ |
221 | heap->ptrs[pos] = heap->ptrs[heap->len]; | |
1eb0c69c MD |
222 | heapify(heap, pos); |
223 | return p; | |
224 | } | |
23a151f0 | 225 | |
dd06413f | 226 | int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src) |
23a151f0 JD |
227 | { |
228 | int ret; | |
229 | ||
dd06413f | 230 | ret = bt_heap_init(dst, src->alloc_len, src->gt); |
23a151f0 JD |
231 | if (ret < 0) |
232 | goto end; | |
233 | ||
234 | ret = heap_set_len(dst, src->len); | |
235 | if (ret < 0) | |
236 | goto end; | |
237 | ||
238 | memcpy(dst->ptrs, src->ptrs, src->len * sizeof(void *)); | |
239 | ||
240 | end: | |
241 | return ret; | |
242 | } |