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1eb0c69c MD |
1 | #ifndef _BABELTRACE_PRIO_HEAP_H |
2 | #define _BABELTRACE_PRIO_HEAP_H | |
3 | ||
4 | /* | |
5 | * prio_heap.h | |
6 | * | |
7 | * Static-sized priority heap containing pointers. Based on CLRS, | |
8 | * chapter 6. | |
9 | * | |
10 | * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
11 | * | |
12 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
13 | * of this software and associated documentation files (the "Software"), to deal | |
14 | * in the Software without restriction, including without limitation the rights | |
15 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
16 | * copies of the Software, and to permit persons to whom the Software is | |
17 | * furnished to do so, subject to the following conditions: | |
18 | * | |
19 | * The above copyright notice and this permission notice shall be included in | |
20 | * all copies or substantial portions of the Software. | |
21 | */ | |
22 | ||
23 | #include <unistd.h> | |
24 | ||
25 | struct ptr_heap { | |
26 | size_t len, alloc_len; | |
27 | void **ptrs; | |
28 | int (*gt)(void *a, void *b); | |
29 | }; | |
30 | ||
eacd552c MD |
31 | #ifdef DEBUG_HEAP |
32 | void check_heap(const struct ptr_heap *heap); | |
33 | #else | |
34 | static inline | |
35 | void check_heap(const struct ptr_heap *heap) | |
36 | { | |
37 | } | |
38 | #endif | |
39 | ||
1eb0c69c MD |
40 | /** |
41 | * heap_maximum - return the largest element in the heap | |
42 | * @heap: the heap to be operated on | |
43 | * | |
44 | * Returns the largest element in the heap, without performing any modification | |
45 | * to the heap structure. Returns NULL if the heap is empty. | |
46 | */ | |
47 | static inline void *heap_maximum(const struct ptr_heap *heap) | |
48 | { | |
eacd552c | 49 | check_heap(heap); |
1eb0c69c MD |
50 | return heap->len ? heap->ptrs[0] : NULL; |
51 | } | |
52 | ||
53 | /** | |
54 | * heap_init - initialize the heap | |
55 | * @heap: the heap to initialize | |
56 | * @alloc_len: number of elements initially allocated | |
57 | * @gt: function to compare the elements | |
58 | * | |
59 | * Returns -ENOMEM if out of memory. | |
60 | */ | |
61 | extern int heap_init(struct ptr_heap *heap, | |
62 | size_t alloc_len, | |
63 | int gt(void *a, void *b)); | |
64 | ||
65 | /** | |
66 | * heap_free - free the heap | |
67 | * @heap: the heap to free | |
68 | */ | |
69 | extern void heap_free(struct ptr_heap *heap); | |
70 | ||
71 | /** | |
72 | * heap_insert - insert an element into the heap | |
73 | * @heap: the heap to be operated on | |
74 | * @p: the element to add | |
75 | * | |
76 | * Insert an element into the heap. | |
77 | * | |
78 | * Returns -ENOMEM if out of memory. | |
79 | */ | |
80 | extern int heap_insert(struct ptr_heap *heap, void *p); | |
81 | ||
82 | /** | |
83 | * heap_remove - remove the largest element from the heap | |
84 | * @heap: the heap to be operated on | |
85 | * | |
86 | * Returns the largest element in the heap. It removes this element from the | |
87 | * heap. Returns NULL if the heap is empty. | |
88 | */ | |
89 | extern void *heap_remove(struct ptr_heap *heap); | |
90 | ||
91 | /** | |
92 | * heap_cherrypick - remove a given element from the heap | |
93 | * @heap: the heap to be operated on | |
94 | * @p: the element | |
95 | * | |
96 | * Remove the given element from the heap. Return the element if present, else | |
97 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |
98 | * O(log(n)) provided by the rest of this API. | |
99 | */ | |
100 | extern void *heap_cherrypick(struct ptr_heap *heap, void *p); | |
101 | ||
102 | /** | |
103 | * heap_replace_max - replace the the largest element from the heap | |
104 | * @heap: the heap to be operated on | |
105 | * @p: the pointer to be inserted as topmost element replacement | |
106 | * | |
107 | * Returns the largest element in the heap. It removes this element from the | |
108 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |
109 | * the heap is empty. | |
110 | * | |
111 | * This is the equivalent of calling heap_remove() and then heap_insert(), but | |
112 | * it only rebalances the heap once. It never allocates memory. | |
113 | */ | |
114 | extern void *heap_replace_max(struct ptr_heap *heap, void *p); | |
115 | ||
116 | #endif /* _BABELTRACE_PRIO_HEAP_H */ |