Fix: add mmap_base_offset to ctf_stream_pos
[babeltrace.git] / lib / prio_heap / prio_heap.c
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>
21 #include <babeltrace/babeltrace-internal.h>
22 #include <errno.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <assert.h>
26
27 #ifndef max_t
28 #define max_t(type, a, b) \
29 ((type) (a) > (type) (b) ? (type) (a) : (type) (b))
30 #endif
31
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
45 static
46 size_t parent(size_t i)
47 {
48 return (i - 1) >> 1;
49 }
50
51 static
52 size_t left(size_t i)
53 {
54 return (i << 1) + 1;
55 }
56
57 static
58 size_t right(size_t i)
59 {
60 return (i << 1) + 2;
61 }
62
63 /*
64 * Copy of heap->ptrs pointer is invalid after heap_grow.
65 */
66 static
67 int heap_grow(struct ptr_heap *heap, size_t new_len)
68 {
69 void **new_ptrs;
70
71 if (likely(heap->alloc_len >= new_len))
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 *));
76 if (unlikely(!new_ptrs))
77 return -ENOMEM;
78 if (likely(heap->ptrs))
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);
91 if (unlikely(ret))
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 (;;) {
122 void *tmp;
123
124 l = left(i);
125 r = right(i);
126 if (l < heap->len && heap->gt(ptrs[l], ptrs[i]))
127 largest = l;
128 else
129 largest = i;
130 if (r < heap->len && heap->gt(ptrs[r], ptrs[largest]))
131 largest = r;
132 if (unlikely(largest == i))
133 break;
134 tmp = ptrs[i];
135 ptrs[i] = ptrs[largest];
136 ptrs[largest] = tmp;
137 i = largest;
138 }
139 check_heap(heap);
140 }
141
142 void *heap_replace_max(struct ptr_heap *heap, void *p)
143 {
144 void *res;
145
146 if (unlikely(!heap->len)) {
147 (void) heap_set_len(heap, 1);
148 heap->ptrs[0] = p;
149 check_heap(heap);
150 return NULL;
151 }
152
153 /* Replace the current max and heapify */
154 res = heap->ptrs[0];
155 heap->ptrs[0] = p;
156 heapify(heap, 0);
157 return res;
158 }
159
160 int heap_insert(struct ptr_heap *heap, void *p)
161 {
162 void **ptrs;
163 size_t pos;
164 int ret;
165
166 ret = heap_set_len(heap, heap->len + 1);
167 if (unlikely(ret))
168 return ret;
169 ptrs = heap->ptrs;
170 pos = heap->len - 1;
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);
175 }
176 ptrs[pos] = p;
177 check_heap(heap);
178 return 0;
179 }
180
181 void *heap_remove(struct ptr_heap *heap)
182 {
183 switch (heap->len) {
184 case 0:
185 return NULL;
186 case 1:
187 (void) heap_set_len(heap, 0);
188 return heap->ptrs[0];
189 }
190 /* Shrink, replace the current max by previous last entry and heapify */
191 heap_set_len(heap, heap->len - 1);
192 /* len changed. previous last entry is at heap->len */
193 return heap_replace_max(heap, heap->ptrs[heap->len]);
194 }
195
196 void *heap_cherrypick(struct ptr_heap *heap, void *p)
197 {
198 size_t pos, len = heap->len;
199
200 for (pos = 0; pos < len; pos++)
201 if (unlikely(heap->ptrs[pos] == p))
202 goto found;
203 return NULL;
204 found:
205 if (unlikely(heap->len == 1)) {
206 (void) heap_set_len(heap, 0);
207 check_heap(heap);
208 return heap->ptrs[0];
209 }
210 /* Replace p with previous last entry and heapify. */
211 heap_set_len(heap, heap->len - 1);
212 /* len changed. previous last entry is at heap->len */
213 heap->ptrs[pos] = heap->ptrs[heap->len];
214 heapify(heap, pos);
215 return p;
216 }
217
218 int heap_copy(struct ptr_heap *dst, struct ptr_heap *src)
219 {
220 int ret;
221
222 ret = heap_init(dst, src->alloc_len, src->gt);
223 if (ret < 0)
224 goto end;
225
226 ret = heap_set_len(dst, src->len);
227 if (ret < 0)
228 goto end;
229
230 memcpy(dst->ptrs, src->ptrs, src->len * sizeof(void *));
231
232 end:
233 return ret;
234 }
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