1 #ifndef _LTTNG_PRIO_HEAP_H
2 #define _LTTNG_PRIO_HEAP_H
7 * Priority heap containing pointers. Based on CLRS, chapter 6.
9 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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:
18 * The above copyright notice and this permission notice shall be included in
19 * all copies or substantial portions of the Software.
21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
22 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
24 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
25 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
26 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 #include <linux/gfp.h>
32 struct lttng_ptr_heap
{
33 size_t len
, alloc_len
;
35 int (*gt
)(void *a
, void *b
);
40 void lttng_check_heap(const struct lttng_ptr_heap
*heap
);
43 void lttng_check_heap(const struct lttng_ptr_heap
*heap
)
49 * lttng_heap_maximum - return the largest element in the heap
50 * @heap: the heap to be operated on
52 * Returns the largest element in the heap, without performing any modification
53 * to the heap structure. Returns NULL if the heap is empty.
55 static inline void *lttng_heap_maximum(const struct lttng_ptr_heap
*heap
)
57 lttng_check_heap(heap
);
58 return heap
->len
? heap
->ptrs
[0] : NULL
;
62 * lttng_heap_init - initialize the heap
63 * @heap: the heap to initialize
64 * @alloc_len: number of elements initially allocated
65 * @gfp: allocation flags
66 * @gt: function to compare the elements
68 * Returns -ENOMEM if out of memory.
70 extern int lttng_heap_init(struct lttng_ptr_heap
*heap
,
71 size_t alloc_len
, gfp_t gfpmask
,
72 int gt(void *a
, void *b
));
75 * lttng_heap_free - free the heap
76 * @heap: the heap to free
78 extern void lttng_heap_free(struct lttng_ptr_heap
*heap
);
81 * lttng_heap_insert - insert an element into the heap
82 * @heap: the heap to be operated on
83 * @p: the element to add
85 * Insert an element into the heap.
87 * Returns -ENOMEM if out of memory.
89 extern int lttng_heap_insert(struct lttng_ptr_heap
*heap
, void *p
);
92 * lttng_heap_remove - remove the largest element from the heap
93 * @heap: the heap to be operated on
95 * Returns the largest element in the heap. It removes this element from the
96 * heap. Returns NULL if the heap is empty.
98 extern void *lttng_heap_remove(struct lttng_ptr_heap
*heap
);
101 * lttng_heap_cherrypick - remove a given element from the heap
102 * @heap: the heap to be operated on
105 * Remove the given element from the heap. Return the element if present, else
106 * return NULL. This algorithm has a complexity of O(n), which is higher than
107 * O(log(n)) provided by the rest of this API.
109 extern void *lttng_heap_cherrypick(struct lttng_ptr_heap
*heap
, void *p
);
112 * lttng_heap_replace_max - replace the the largest element from the heap
113 * @heap: the heap to be operated on
114 * @p: the pointer to be inserted as topmost element replacement
116 * Returns the largest element in the heap. It removes this element from the
117 * heap. The heap is rebalanced only once after the insertion. Returns NULL if
120 * This is the equivalent of calling heap_remove() and then heap_insert(), but
121 * it only rebalances the heap once. It never allocates memory.
123 extern void *lttng_heap_replace_max(struct lttng_ptr_heap
*heap
, void *p
);
125 #endif /* _LTTNG_PRIO_HEAP_H */
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