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9f36eaed MJ |
1 | /* SPDX-License-Identifier: MIT |
2 | * | |
a071f25d | 3 | * lttng/prio_heap.h |
162769ef | 4 | * |
7369e702 | 5 | * Priority heap containing pointers. Based on CLRS, chapter 6. |
162769ef MD |
6 | * |
7 | * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
f3bc08c5 MD |
8 | */ |
9 | ||
9f36eaed MJ |
10 | #ifndef _LTTNG_PRIO_HEAP_H |
11 | #define _LTTNG_PRIO_HEAP_H | |
12 | ||
c9891db2 MD |
13 | #include <linux/gfp.h> |
14 | ||
a88db018 | 15 | struct lttng_ptr_heap { |
7369e702 | 16 | size_t len, alloc_len; |
c9891db2 MD |
17 | void **ptrs; |
18 | int (*gt)(void *a, void *b); | |
7369e702 | 19 | gfp_t gfpmask; |
c9891db2 | 20 | }; |
f3bc08c5 | 21 | |
0b6d2ab3 | 22 | #ifdef DEBUG_HEAP |
a88db018 | 23 | void lttng_check_heap(const struct lttng_ptr_heap *heap); |
0b6d2ab3 MD |
24 | #else |
25 | static inline | |
a88db018 | 26 | void lttng_check_heap(const struct lttng_ptr_heap *heap) |
0b6d2ab3 MD |
27 | { |
28 | } | |
29 | #endif | |
30 | ||
f3bc08c5 | 31 | /** |
a88db018 | 32 | * lttng_heap_maximum - return the largest element in the heap |
f3bc08c5 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 | */ | |
a88db018 | 38 | static inline void *lttng_heap_maximum(const struct lttng_ptr_heap *heap) |
f3bc08c5 | 39 | { |
a88db018 | 40 | lttng_check_heap(heap); |
7369e702 | 41 | return heap->len ? heap->ptrs[0] : NULL; |
f3bc08c5 MD |
42 | } |
43 | ||
c9891db2 | 44 | /** |
a88db018 | 45 | * lttng_heap_init - initialize the heap |
c9891db2 | 46 | * @heap: the heap to initialize |
7369e702 | 47 | * @alloc_len: number of elements initially allocated |
c9891db2 MD |
48 | * @gfp: allocation flags |
49 | * @gt: function to compare the elements | |
50 | * | |
51 | * Returns -ENOMEM if out of memory. | |
52 | */ | |
a88db018 | 53 | extern int lttng_heap_init(struct lttng_ptr_heap *heap, |
7369e702 MD |
54 | size_t alloc_len, gfp_t gfpmask, |
55 | int gt(void *a, void *b)); | |
c9891db2 MD |
56 | |
57 | /** | |
a88db018 | 58 | * lttng_heap_free - free the heap |
c9891db2 MD |
59 | * @heap: the heap to free |
60 | */ | |
a88db018 | 61 | extern void lttng_heap_free(struct lttng_ptr_heap *heap); |
c9891db2 MD |
62 | |
63 | /** | |
a88db018 | 64 | * lttng_heap_insert - insert an element into the heap |
c9891db2 | 65 | * @heap: the heap to be operated on |
7369e702 | 66 | * @p: the element to add |
c9891db2 | 67 | * |
7369e702 MD |
68 | * Insert an element into the heap. |
69 | * | |
70 | * Returns -ENOMEM if out of memory. | |
c9891db2 | 71 | */ |
a88db018 | 72 | extern int lttng_heap_insert(struct lttng_ptr_heap *heap, void *p); |
f3bc08c5 MD |
73 | |
74 | /** | |
a88db018 | 75 | * lttng_heap_remove - remove the largest element from the heap |
f3bc08c5 MD |
76 | * @heap: the heap to be operated on |
77 | * | |
78 | * Returns the largest element in the heap. It removes this element from the | |
79 | * heap. Returns NULL if the heap is empty. | |
80 | */ | |
a88db018 | 81 | extern void *lttng_heap_remove(struct lttng_ptr_heap *heap); |
f3bc08c5 MD |
82 | |
83 | /** | |
a88db018 | 84 | * lttng_heap_cherrypick - remove a given element from the heap |
f3bc08c5 MD |
85 | * @heap: the heap to be operated on |
86 | * @p: the element | |
87 | * | |
88 | * Remove the given element from the heap. Return the element if present, else | |
89 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |
90 | * O(log(n)) provided by the rest of this API. | |
91 | */ | |
a88db018 | 92 | extern void *lttng_heap_cherrypick(struct lttng_ptr_heap *heap, void *p); |
f3bc08c5 MD |
93 | |
94 | /** | |
a88db018 | 95 | * lttng_heap_replace_max - replace the the largest element from the heap |
f3bc08c5 MD |
96 | * @heap: the heap to be operated on |
97 | * @p: the pointer to be inserted as topmost element replacement | |
98 | * | |
99 | * Returns the largest element in the heap. It removes this element from the | |
100 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |
101 | * the heap is empty. | |
102 | * | |
103 | * This is the equivalent of calling heap_remove() and then heap_insert(), but | |
7369e702 | 104 | * it only rebalances the heap once. It never allocates memory. |
f3bc08c5 | 105 | */ |
a88db018 | 106 | extern void *lttng_heap_replace_max(struct lttng_ptr_heap *heap, void *p); |
f3bc08c5 | 107 | |
162769ef | 108 | #endif /* _LTTNG_PRIO_HEAP_H */ |