Commit | Line | Data |
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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 | |
26 | void check_heap(const struct ptr_heap *heap) | |
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 | */ | |
ec21af4a | 52 | BT_HIDDEN |
dd06413f | 53 | extern int bt_heap_init(struct ptr_heap *heap, |
1eb0c69c MD |
54 | size_t alloc_len, |
55 | int gt(void *a, void *b)); | |
56 | ||
57 | /** | |
dd06413f | 58 | * bt_heap_free - free the heap |
1eb0c69c MD |
59 | * @heap: the heap to free |
60 | */ | |
ec21af4a | 61 | BT_HIDDEN |
dd06413f | 62 | extern void bt_heap_free(struct ptr_heap *heap); |
1eb0c69c MD |
63 | |
64 | /** | |
dd06413f | 65 | * bt_heap_insert - insert an element into the heap |
1eb0c69c MD |
66 | * @heap: the heap to be operated on |
67 | * @p: the element to add | |
68 | * | |
69 | * Insert an element into the heap. | |
70 | * | |
71 | * Returns -ENOMEM if out of memory. | |
72 | */ | |
ec21af4a | 73 | BT_HIDDEN |
dd06413f | 74 | extern int bt_heap_insert(struct ptr_heap *heap, void *p); |
1eb0c69c MD |
75 | |
76 | /** | |
dd06413f | 77 | * bt_heap_remove - remove the largest element from the heap |
1eb0c69c MD |
78 | * @heap: the heap to be operated on |
79 | * | |
80 | * Returns the largest element in the heap. It removes this element from the | |
81 | * heap. Returns NULL if the heap is empty. | |
82 | */ | |
ec21af4a | 83 | BT_HIDDEN |
dd06413f | 84 | extern void *bt_heap_remove(struct ptr_heap *heap); |
1eb0c69c MD |
85 | |
86 | /** | |
dd06413f | 87 | * bt_heap_cherrypick - remove a given element from the heap |
1eb0c69c MD |
88 | * @heap: the heap to be operated on |
89 | * @p: the element | |
90 | * | |
91 | * Remove the given element from the heap. Return the element if present, else | |
92 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |
93 | * O(log(n)) provided by the rest of this API. | |
94 | */ | |
ec21af4a | 95 | BT_HIDDEN |
dd06413f | 96 | extern void *bt_heap_cherrypick(struct ptr_heap *heap, void *p); |
1eb0c69c MD |
97 | |
98 | /** | |
dd06413f | 99 | * bt_heap_replace_max - replace the the largest element from the heap |
1eb0c69c MD |
100 | * @heap: the heap to be operated on |
101 | * @p: the pointer to be inserted as topmost element replacement | |
102 | * | |
103 | * Returns the largest element in the heap. It removes this element from the | |
104 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |
105 | * the heap is empty. | |
106 | * | |
dd06413f | 107 | * This is the equivalent of calling bt_heap_remove() and then bt_heap_insert(), but |
1eb0c69c MD |
108 | * it only rebalances the heap once. It never allocates memory. |
109 | */ | |
ec21af4a | 110 | BT_HIDDEN |
dd06413f | 111 | extern void *bt_heap_replace_max(struct ptr_heap *heap, void *p); |
1eb0c69c | 112 | |
23a151f0 | 113 | /** |
dd06413f | 114 | * bt_heap_copy - copy a heap |
23a151f0 JD |
115 | * @dst: the destination heap (must be allocated) |
116 | * @src: the source heap | |
117 | * | |
118 | * Returns -ENOMEM if out of memory. | |
119 | */ | |
ec21af4a | 120 | BT_HIDDEN |
dd06413f | 121 | extern int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src); |
23a151f0 | 122 | |
1eb0c69c | 123 | #endif /* _BABELTRACE_PRIO_HEAP_H */ |