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.
22 #include <linux/gfp.h>
25 size_t len
, alloc_len
;
27 int (*gt
)(void *a
, void *b
);
32 * heap_maximum - return the largest element in the heap
33 * @heap: the heap to be operated on
35 * Returns the largest element in the heap, without performing any modification
36 * to the heap structure. Returns NULL if the heap is empty.
38 static inline void *heap_maximum(const struct ptr_heap
*heap
)
40 return heap
->len
? heap
->ptrs
[0] : NULL
;
44 * heap_init - initialize the heap
45 * @heap: the heap to initialize
46 * @alloc_len: number of elements initially allocated
47 * @gfp: allocation flags
48 * @gt: function to compare the elements
50 * Returns -ENOMEM if out of memory.
52 extern int heap_init(struct ptr_heap
*heap
,
53 size_t alloc_len
, gfp_t gfpmask
,
54 int gt(void *a
, void *b
));
57 * heap_free - free the heap
58 * @heap: the heap to free
60 extern void heap_free(struct ptr_heap
*heap
);
63 * heap_insert - insert an element into the heap
64 * @heap: the heap to be operated on
65 * @p: the element to add
67 * Insert an element into the heap.
69 * Returns -ENOMEM if out of memory.
71 extern int heap_insert(struct ptr_heap
*heap
, void *p
);
74 * heap_remove - remove the largest element from the heap
75 * @heap: the heap to be operated on
77 * Returns the largest element in the heap. It removes this element from the
78 * heap. Returns NULL if the heap is empty.
80 extern void *heap_remove(struct ptr_heap
*heap
);
83 * heap_cherrypick - remove a given element from the heap
84 * @heap: the heap to be operated on
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.
91 extern void *heap_cherrypick(struct ptr_heap
*heap
, void *p
);
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
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
102 * This is the equivalent of calling heap_remove() and then heap_insert(), but
103 * it only rebalances the heap once. It never allocates memory.
105 extern void *heap_replace_max(struct ptr_heap
*heap
, void *p
);
107 #endif /* _LTTNG_PRIO_HEAP_H */
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