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. | |
18 | */ | |
19 | ||
20 | #include <babeltrace/prio_heap.h> | |
96e1cf26 | 21 | #include <babeltrace/babeltrace-internal.h> |
1eb0c69c MD |
22 | #include <errno.h> |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
eacd552c | 25 | #include <assert.h> |
1eb0c69c MD |
26 | |
27 | #ifndef max_t | |
28 | #define max_t(type, a, b) \ | |
29 | ((type) (a) > (type) (b) ? (type) (a) : (type) (b)) | |
30 | #endif | |
31 | ||
eacd552c MD |
32 | #ifdef DEBUG_HEAP |
33 | void check_heap(const struct ptr_heap *heap) | |
34 | { | |
35 | size_t i; | |
36 | ||
37 | if (!heap->len) | |
38 | return; | |
39 | ||
40 | for (i = 1; i < heap->len; i++) | |
41 | assert(!heap->gt(heap->ptrs[i], heap->ptrs[0])); | |
42 | } | |
43 | #endif | |
44 | ||
557255e5 | 45 | static |
1eb0c69c MD |
46 | size_t parent(size_t i) |
47 | { | |
eacd552c | 48 | return (i - 1) >> 1; |
1eb0c69c MD |
49 | } |
50 | ||
51 | static | |
52 | size_t left(size_t i) | |
53 | { | |
eacd552c | 54 | return (i << 1) + 1; |
1eb0c69c MD |
55 | } |
56 | ||
57 | static | |
58 | size_t right(size_t i) | |
59 | { | |
eacd552c | 60 | return (i << 1) + 2; |
1eb0c69c MD |
61 | } |
62 | ||
557255e5 MD |
63 | /* |
64 | * Copy of heap->ptrs pointer is invalid after heap_grow. | |
65 | */ | |
1eb0c69c MD |
66 | static |
67 | int heap_grow(struct ptr_heap *heap, size_t new_len) | |
68 | { | |
69 | void **new_ptrs; | |
70 | ||
96e1cf26 | 71 | if (likely(heap->alloc_len >= new_len)) |
1eb0c69c MD |
72 | return 0; |
73 | ||
74 | heap->alloc_len = max_t(size_t, new_len, heap->alloc_len << 1); | |
75 | new_ptrs = calloc(heap->alloc_len, sizeof(void *)); | |
96e1cf26 | 76 | if (unlikely(!new_ptrs)) |
1eb0c69c | 77 | return -ENOMEM; |
96e1cf26 | 78 | if (likely(heap->ptrs)) |
1eb0c69c MD |
79 | memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *)); |
80 | free(heap->ptrs); | |
81 | heap->ptrs = new_ptrs; | |
82 | return 0; | |
83 | } | |
84 | ||
85 | static | |
86 | int heap_set_len(struct ptr_heap *heap, size_t new_len) | |
87 | { | |
88 | int ret; | |
89 | ||
90 | ret = heap_grow(heap, new_len); | |
96e1cf26 | 91 | if (unlikely(ret)) |
1eb0c69c MD |
92 | return ret; |
93 | heap->len = new_len; | |
94 | return 0; | |
95 | } | |
96 | ||
97 | int heap_init(struct ptr_heap *heap, size_t alloc_len, | |
98 | int gt(void *a, void *b)) | |
99 | { | |
100 | heap->ptrs = NULL; | |
101 | heap->len = 0; | |
102 | heap->alloc_len = 0; | |
103 | heap->gt = gt; | |
104 | /* | |
105 | * Minimum size allocated is 1 entry to ensure memory allocation | |
106 | * never fails within heap_replace_max. | |
107 | */ | |
108 | return heap_grow(heap, max_t(size_t, 1, alloc_len)); | |
109 | } | |
110 | ||
111 | void heap_free(struct ptr_heap *heap) | |
112 | { | |
113 | free(heap->ptrs); | |
114 | } | |
115 | ||
116 | static void heapify(struct ptr_heap *heap, size_t i) | |
117 | { | |
118 | void **ptrs = heap->ptrs; | |
119 | size_t l, r, largest; | |
120 | ||
121 | for (;;) { | |
eacd552c MD |
122 | void *tmp; |
123 | ||
1eb0c69c MD |
124 | l = left(i); |
125 | r = right(i); | |
eacd552c | 126 | if (l < heap->len && heap->gt(ptrs[l], ptrs[i])) |
1eb0c69c MD |
127 | largest = l; |
128 | else | |
129 | largest = i; | |
eacd552c | 130 | if (r < heap->len && heap->gt(ptrs[r], ptrs[largest])) |
1eb0c69c | 131 | largest = r; |
96e1cf26 | 132 | if (unlikely(largest == i)) |
1eb0c69c | 133 | break; |
eacd552c MD |
134 | tmp = ptrs[i]; |
135 | ptrs[i] = ptrs[largest]; | |
136 | ptrs[largest] = tmp; | |
137 | i = largest; | |
1eb0c69c | 138 | } |
eacd552c | 139 | check_heap(heap); |
1eb0c69c MD |
140 | } |
141 | ||
142 | void *heap_replace_max(struct ptr_heap *heap, void *p) | |
143 | { | |
144 | void *res; | |
1eb0c69c | 145 | |
96e1cf26 | 146 | if (unlikely(!heap->len)) { |
1eb0c69c | 147 | (void) heap_set_len(heap, 1); |
557255e5 | 148 | heap->ptrs[0] = p; |
eacd552c | 149 | check_heap(heap); |
1eb0c69c MD |
150 | return NULL; |
151 | } | |
152 | ||
153 | /* Replace the current max and heapify */ | |
557255e5 MD |
154 | res = heap->ptrs[0]; |
155 | heap->ptrs[0] = p; | |
1eb0c69c MD |
156 | heapify(heap, 0); |
157 | return res; | |
158 | } | |
159 | ||
160 | int heap_insert(struct ptr_heap *heap, void *p) | |
161 | { | |
557255e5 MD |
162 | void **ptrs; |
163 | size_t pos; | |
1eb0c69c MD |
164 | int ret; |
165 | ||
166 | ret = heap_set_len(heap, heap->len + 1); | |
96e1cf26 | 167 | if (unlikely(ret)) |
1eb0c69c | 168 | return ret; |
557255e5 | 169 | ptrs = heap->ptrs; |
557255e5 | 170 | pos = heap->len - 1; |
eacd552c MD |
171 | while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) { |
172 | /* Move parent down until we find the right spot */ | |
173 | ptrs[pos] = ptrs[parent(pos)]; | |
174 | pos = parent(pos); | |
557255e5 | 175 | } |
eacd552c MD |
176 | ptrs[pos] = p; |
177 | check_heap(heap); | |
1eb0c69c MD |
178 | return 0; |
179 | } | |
180 | ||
181 | void *heap_remove(struct ptr_heap *heap) | |
182 | { | |
1eb0c69c MD |
183 | switch (heap->len) { |
184 | case 0: | |
185 | return NULL; | |
186 | case 1: | |
187 | (void) heap_set_len(heap, 0); | |
557255e5 | 188 | return heap->ptrs[0]; |
1eb0c69c MD |
189 | } |
190 | /* Shrink, replace the current max by previous last entry and heapify */ | |
191 | heap_set_len(heap, heap->len - 1); | |
eacd552c MD |
192 | /* len changed. previous last entry is at heap->len */ |
193 | return heap_replace_max(heap, heap->ptrs[heap->len]); | |
1eb0c69c MD |
194 | } |
195 | ||
196 | void *heap_cherrypick(struct ptr_heap *heap, void *p) | |
197 | { | |
1eb0c69c MD |
198 | size_t pos, len = heap->len; |
199 | ||
200 | for (pos = 0; pos < len; pos++) | |
96e1cf26 | 201 | if (unlikely(heap->ptrs[pos] == p)) |
1eb0c69c MD |
202 | goto found; |
203 | return NULL; | |
204 | found: | |
96e1cf26 | 205 | if (unlikely(heap->len == 1)) { |
1eb0c69c | 206 | (void) heap_set_len(heap, 0); |
eacd552c | 207 | check_heap(heap); |
557255e5 | 208 | return heap->ptrs[0]; |
1eb0c69c MD |
209 | } |
210 | /* Replace p with previous last entry and heapify. */ | |
211 | heap_set_len(heap, heap->len - 1); | |
eacd552c MD |
212 | /* len changed. previous last entry is at heap->len */ |
213 | heap->ptrs[pos] = heap->ptrs[heap->len]; | |
1eb0c69c MD |
214 | heapify(heap, pos); |
215 | return p; | |
216 | } |