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1 | #ifndef _LTTNG_PRIO_HEAP_H |
2 | #define _LTTNG_PRIO_HEAP_H | |
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3 | |
4 | /* | |
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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. | |
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21 | */ |
22 | ||
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23 | /* |
24 | * TODO: | |
25 | * implement struct ptr_head, heap_init, heap_free, heap_insert. | |
f3bc08c5 | 26 | */ |
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27 | |
28 | /** | |
29 | * heap_maximum - return the largest element in the heap | |
30 | * @heap: the heap to be operated on | |
31 | * | |
32 | * Returns the largest element in the heap, without performing any modification | |
33 | * to the heap structure. Returns NULL if the heap is empty. | |
34 | */ | |
35 | static inline void *heap_maximum(const struct ptr_heap *heap) | |
36 | { | |
37 | return heap->size ? heap->ptrs[0] : NULL; | |
38 | } | |
39 | ||
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40 | |
41 | /** | |
42 | * heap_remove - remove the largest element from the heap | |
43 | * @heap: the heap to be operated on | |
44 | * | |
45 | * Returns the largest element in the heap. It removes this element from the | |
46 | * heap. Returns NULL if the heap is empty. | |
47 | */ | |
48 | extern void *heap_remove(struct ptr_heap *heap); | |
49 | ||
50 | /** | |
51 | * heap_cherrypick - remove a given element from the heap | |
52 | * @heap: the heap to be operated on | |
53 | * @p: the element | |
54 | * | |
55 | * Remove the given element from the heap. Return the element if present, else | |
56 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |
57 | * O(log(n)) provided by the rest of this API. | |
58 | */ | |
59 | extern void *heap_cherrypick(struct ptr_heap *heap, void *p); | |
60 | ||
61 | /** | |
62 | * heap_replace_max - replace the the largest element from the heap | |
63 | * @heap: the heap to be operated on | |
64 | * @p: the pointer to be inserted as topmost element replacement | |
65 | * | |
66 | * Returns the largest element in the heap. It removes this element from the | |
67 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |
68 | * the heap is empty. | |
69 | * | |
70 | * This is the equivalent of calling heap_remove() and then heap_insert(), but | |
71 | * it only rebalances the heap once. | |
72 | */ | |
73 | extern void *heap_replace_max(struct ptr_heap *heap, void *p); | |
74 | ||
162769ef | 75 | #endif /* _LTTNG_PRIO_HEAP_H */ |