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1 | #ifndef _LTTNG_PRIO_HEAP_H |
2 | #define _LTTNG_PRIO_HEAP_H | |
f3bc08c5 MD |
3 | |
4 | /* | |
162769ef MD |
5 | * prio_heap.h |
6 | * | |
7369e702 | 7 | * Priority heap containing pointers. Based on CLRS, chapter 6. |
162769ef MD |
8 | * |
9 | * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
12 | * of this software and associated documentation files (the "Software"), to deal | |
13 | * in the Software without restriction, including without limitation the rights | |
14 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
15 | * copies of the Software, and to permit persons to whom the Software is | |
16 | * furnished to do so, subject to the following conditions: | |
17 | * | |
18 | * The above copyright notice and this permission notice shall be included in | |
19 | * all copies or substantial portions of the Software. | |
f3bc08c5 MD |
20 | */ |
21 | ||
c9891db2 MD |
22 | #include <linux/gfp.h> |
23 | ||
24 | struct ptr_heap { | |
7369e702 | 25 | size_t len, alloc_len; |
c9891db2 MD |
26 | void **ptrs; |
27 | int (*gt)(void *a, void *b); | |
7369e702 | 28 | gfp_t gfpmask; |
c9891db2 | 29 | }; |
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30 | |
31 | /** | |
32 | * heap_maximum - return the largest element in the heap | |
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 | */ | |
38 | static inline void *heap_maximum(const struct ptr_heap *heap) | |
39 | { | |
7369e702 | 40 | return heap->len ? heap->ptrs[0] : NULL; |
f3bc08c5 MD |
41 | } |
42 | ||
c9891db2 MD |
43 | /** |
44 | * heap_init - initialize the heap | |
45 | * @heap: the heap to initialize | |
7369e702 | 46 | * @alloc_len: number of elements initially allocated |
c9891db2 MD |
47 | * @gfp: allocation flags |
48 | * @gt: function to compare the elements | |
49 | * | |
50 | * Returns -ENOMEM if out of memory. | |
51 | */ | |
7369e702 MD |
52 | extern int heap_init(struct ptr_heap *heap, |
53 | size_t alloc_len, gfp_t gfpmask, | |
54 | int gt(void *a, void *b)); | |
c9891db2 MD |
55 | |
56 | /** | |
57 | * heap_free - free the heap | |
58 | * @heap: the heap to free | |
59 | */ | |
60 | extern void heap_free(struct ptr_heap *heap); | |
61 | ||
62 | /** | |
63 | * heap_insert - insert an element into the heap | |
64 | * @heap: the heap to be operated on | |
7369e702 | 65 | * @p: the element to add |
c9891db2 | 66 | * |
7369e702 MD |
67 | * Insert an element into the heap. |
68 | * | |
69 | * Returns -ENOMEM if out of memory. | |
c9891db2 | 70 | */ |
7369e702 | 71 | extern int heap_insert(struct ptr_heap *heap, void *p); |
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72 | |
73 | /** | |
74 | * heap_remove - remove the largest element from the heap | |
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 | */ | |
80 | extern void *heap_remove(struct ptr_heap *heap); | |
81 | ||
82 | /** | |
83 | * heap_cherrypick - remove a given element from the heap | |
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 | */ | |
91 | extern void *heap_cherrypick(struct ptr_heap *heap, void *p); | |
92 | ||
93 | /** | |
94 | * heap_replace_max - replace the the largest element from the heap | |
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 | * | |
102 | * This is the equivalent of calling heap_remove() and then heap_insert(), but | |
7369e702 | 103 | * it only rebalances the heap once. It never allocates memory. |
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104 | */ |
105 | extern void *heap_replace_max(struct ptr_heap *heap, void *p); | |
106 | ||
162769ef | 107 | #endif /* _LTTNG_PRIO_HEAP_H */ |