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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 | ||
0235b0db MJ |
10 | #ifndef _BABELTRACE_PRIO_HEAP_H |
11 | #define _BABELTRACE_PRIO_HEAP_H | |
12 | ||
1eb0c69c | 13 | #include <unistd.h> |
91d81473 | 14 | #include "common/macros.h" |
1eb0c69c MD |
15 | |
16 | struct ptr_heap { | |
17 | size_t len, alloc_len; | |
18 | void **ptrs; | |
19 | int (*gt)(void *a, void *b); | |
20 | }; | |
21 | ||
eacd552c MD |
22 | #ifdef DEBUG_HEAP |
23 | void check_heap(const struct ptr_heap *heap); | |
24 | #else | |
25 | static inline | |
ecd7492f | 26 | void check_heap(const struct ptr_heap *heap __attribute__((unused))) |
eacd552c MD |
27 | { |
28 | } | |
29 | #endif | |
30 | ||
1eb0c69c | 31 | /** |
dd06413f | 32 | * bt_heap_maximum - return the largest element in the heap |
1eb0c69c MD |
33 | * @heap: the heap to be operated on |
34 | * | |
35 | * Returns the largest element in the heap, without performing any modification | |
36 | * to the heap structure. Returns NULL if the heap is empty. | |
37 | */ | |
dd06413f | 38 | static inline void *bt_heap_maximum(const struct ptr_heap *heap) |
1eb0c69c | 39 | { |
eacd552c | 40 | check_heap(heap); |
91d81473 | 41 | return G_LIKELY(heap->len) ? heap->ptrs[0] : NULL; |
1eb0c69c MD |
42 | } |
43 | ||
44 | /** | |
dd06413f | 45 | * bt_heap_init - initialize the heap |
1eb0c69c MD |
46 | * @heap: the heap to initialize |
47 | * @alloc_len: number of elements initially allocated | |
48 | * @gt: function to compare the elements | |
49 | * | |
50 | * Returns -ENOMEM if out of memory. | |
51 | */ | |
dd06413f | 52 | extern int bt_heap_init(struct ptr_heap *heap, |
1eb0c69c MD |
53 | size_t alloc_len, |
54 | int gt(void *a, void *b)); | |
55 | ||
56 | /** | |
dd06413f | 57 | * bt_heap_free - free the heap |
1eb0c69c MD |
58 | * @heap: the heap to free |
59 | */ | |
dd06413f | 60 | extern void bt_heap_free(struct ptr_heap *heap); |
1eb0c69c MD |
61 | |
62 | /** | |
dd06413f | 63 | * bt_heap_insert - insert an element into the heap |
1eb0c69c MD |
64 | * @heap: the heap to be operated on |
65 | * @p: the element to add | |
66 | * | |
67 | * Insert an element into the heap. | |
68 | * | |
69 | * Returns -ENOMEM if out of memory. | |
70 | */ | |
dd06413f | 71 | extern int bt_heap_insert(struct ptr_heap *heap, void *p); |
1eb0c69c MD |
72 | |
73 | /** | |
dd06413f | 74 | * bt_heap_remove - remove the largest element from the heap |
1eb0c69c MD |
75 | * @heap: the heap to be operated on |
76 | * | |
77 | * Returns the largest element in the heap. It removes this element from the | |
78 | * heap. Returns NULL if the heap is empty. | |
79 | */ | |
dd06413f | 80 | extern void *bt_heap_remove(struct ptr_heap *heap); |
1eb0c69c MD |
81 | |
82 | /** | |
dd06413f | 83 | * bt_heap_cherrypick - remove a given element from the heap |
1eb0c69c MD |
84 | * @heap: the heap to be operated on |
85 | * @p: the element | |
86 | * | |
87 | * Remove the given element from the heap. Return the element if present, else | |
88 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |
89 | * O(log(n)) provided by the rest of this API. | |
90 | */ | |
dd06413f | 91 | extern void *bt_heap_cherrypick(struct ptr_heap *heap, void *p); |
1eb0c69c MD |
92 | |
93 | /** | |
dd06413f | 94 | * bt_heap_replace_max - replace the the largest element from the heap |
1eb0c69c MD |
95 | * @heap: the heap to be operated on |
96 | * @p: the pointer to be inserted as topmost element replacement | |
97 | * | |
98 | * Returns the largest element in the heap. It removes this element from the | |
99 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |
100 | * the heap is empty. | |
101 | * | |
dd06413f | 102 | * This is the equivalent of calling bt_heap_remove() and then bt_heap_insert(), but |
1eb0c69c MD |
103 | * it only rebalances the heap once. It never allocates memory. |
104 | */ | |
dd06413f | 105 | extern void *bt_heap_replace_max(struct ptr_heap *heap, void *p); |
1eb0c69c | 106 | |
23a151f0 | 107 | /** |
dd06413f | 108 | * bt_heap_copy - copy a heap |
23a151f0 JD |
109 | * @dst: the destination heap (must be allocated) |
110 | * @src: the source heap | |
111 | * | |
112 | * Returns -ENOMEM if out of memory. | |
113 | */ | |
dd06413f | 114 | extern int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src); |
23a151f0 | 115 | |
1eb0c69c | 116 | #endif /* _BABELTRACE_PRIO_HEAP_H */ |