[lttngtop.git] / lib / babeltrace / prio_heap.h

#ifndef _BABELTRACE_PRIO_HEAP_H
#define _BABELTRACE_PRIO_HEAP_H

/*
 * prio_heap.h
 *
 * Static-sized priority heap containing pointers. Based on CLRS,
 * chapter 6.
 *
 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <unistd.h>
#include <babeltrace/babeltrace-internal.h>

struct ptr_heap {
	size_t len, alloc_len;
	void **ptrs;
	int (*gt)(void *a, void *b);
};

#ifdef DEBUG_HEAP
void check_heap(const struct ptr_heap *heap);
#else
static inline
void check_heap(const struct ptr_heap *heap)
{
}
#endif

/**
 * bt_heap_maximum - return the largest element in the heap
 * @heap: the heap to be operated on
 *
 * Returns the largest element in the heap, without performing any modification
 * to the heap structure. Returns NULL if the heap is empty.
 */
static inline void *bt_heap_maximum(const struct ptr_heap *heap)
{
	check_heap(heap);
	return likely(heap->len) ? heap->ptrs[0] : NULL;
}

/**
 * bt_heap_init - initialize the heap
 * @heap: the heap to initialize
 * @alloc_len: number of elements initially allocated
 * @gt: function to compare the elements
 *
 * Returns -ENOMEM if out of memory.
 */
extern int bt_heap_init(struct ptr_heap *heap,
		     size_t alloc_len,
		     int gt(void *a, void *b));

/**
 * bt_heap_free - free the heap
 * @heap: the heap to free
 */
extern void bt_heap_free(struct ptr_heap *heap);

/**
 * bt_heap_insert - insert an element into the heap
 * @heap: the heap to be operated on
 * @p: the element to add
 *
 * Insert an element into the heap.
 *
 * Returns -ENOMEM if out of memory.
 */
extern int bt_heap_insert(struct ptr_heap *heap, void *p);

/**
 * bt_heap_remove - remove the largest element from the heap
 * @heap: the heap to be operated on
 *
 * Returns the largest element in the heap. It removes this element from the
 * heap. Returns NULL if the heap is empty.
 */
extern void *bt_heap_remove(struct ptr_heap *heap);

/**
 * bt_heap_cherrypick - remove a given element from the heap
 * @heap: the heap to be operated on
 * @p: the element
 *
 * Remove the given element from the heap. Return the element if present, else
 * return NULL. This algorithm has a complexity of O(n), which is higher than
 * O(log(n)) provided by the rest of this API.
 */
extern void *bt_heap_cherrypick(struct ptr_heap *heap, void *p);

/**
 * bt_heap_replace_max - replace the the largest element from the heap
 * @heap: the heap to be operated on
 * @p: the pointer to be inserted as topmost element replacement
 *
 * Returns the largest element in the heap. It removes this element from the
 * heap. The heap is rebalanced only once after the insertion. Returns NULL if
 * the heap is empty.
 *
 * This is the equivalent of calling bt_heap_remove() and then bt_heap_insert(), but
 * it only rebalances the heap once. It never allocates memory.
 */
extern void *bt_heap_replace_max(struct ptr_heap *heap, void *p);

/**
 * bt_heap_copy - copy a heap
 * @dst: the destination heap (must be allocated)
 * @src: the source heap
 *
 * Returns -ENOMEM if out of memory.
 */
extern int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src);

#endif /* _BABELTRACE_PRIO_HEAP_H */
Commit	Line	Data
b1acd2b3 JD	1	#ifndef _BABELTRACE_PRIO_HEAP_H
	2	#define _BABELTRACE_PRIO_HEAP_H
	3
	4	/*
	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.
	21	*
	22	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	23	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	24	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	25	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	26	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	27	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	28	* SOFTWARE.
	29	*/
	30
	31	#include <unistd.h>
	32	#include <babeltrace/babeltrace-internal.h>
	33
	34	struct ptr_heap {
	35	size_t len, alloc_len;
	36	void **ptrs;
	37	int (gt)(void a, void *b);
	38	};
	39
	40	#ifdef DEBUG_HEAP
	41	void check_heap(const struct ptr_heap *heap);
	42	#else
	43	static inline
	44	void check_heap(const struct ptr_heap *heap)
	45	{
	46	}
	47	#endif
	48
	49	/**
	50	* bt_heap_maximum - return the largest element in the heap
	51	* @heap: the heap to be operated on
	52	*
	53	* Returns the largest element in the heap, without performing any modification
	54	* to the heap structure. Returns NULL if the heap is empty.
	55	*/
	56	static inline void bt_heap_maximum(const struct ptr_heap heap)
	57	{
	58	check_heap(heap);
	59	return likely(heap->len) ? heap->ptrs[0] : NULL;
	60	}
	61
	62	/**
	63	* bt_heap_init - initialize the heap
	64	* @heap: the heap to initialize
65	* @alloc_len: number of elements initially allocated
66	* @gt: function to compare the elements
67	*
68	* Returns -ENOMEM if out of memory.
69	*/
70	extern int bt_heap_init(struct ptr_heap *heap,
71	size_t alloc_len,
72	int gt(void a, void b));
73
74	/**
75	* bt_heap_free - free the heap
76	* @heap: the heap to free
77	*/
78	extern void bt_heap_free(struct ptr_heap *heap);
79
80	/**
81	* bt_heap_insert - insert an element into the heap
82	* @heap: the heap to be operated on
83	* @p: the element to add
84	*
85	* Insert an element into the heap.
86	*
87	* Returns -ENOMEM if out of memory.
88	*/
89	extern int bt_heap_insert(struct ptr_heap heap, void p);
90
91	/**
92	* bt_heap_remove - remove the largest element from the heap
93	* @heap: the heap to be operated on
94	*
95	* Returns the largest element in the heap. It removes this element from the
96	* heap. Returns NULL if the heap is empty.
97	*/
98	extern void bt_heap_remove(struct ptr_heap heap);
99
100	/**
101	* bt_heap_cherrypick - remove a given element from the heap
102	* @heap: the heap to be operated on
103	* @p: the element
104	*
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.
108	*/
109	extern void bt_heap_cherrypick(struct ptr_heap heap, void *p);
110
111	/**
112	* bt_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
115	*
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
118	* the heap is empty.
119	*
120	* This is the equivalent of calling bt_heap_remove() and then bt_heap_insert(), but
121	* it only rebalances the heap once. It never allocates memory.
122	*/
123	extern void bt_heap_replace_max(struct ptr_heap heap, void *p);
124
125	/**
126	* bt_heap_copy - copy a heap
127	* @dst: the destination heap (must be allocated)
128	* @src: the source heap
129	*
130	* Returns -ENOMEM if out of memory.
131	*/
132	extern int bt_heap_copy(struct ptr_heap dst, struct ptr_heap src);
133
134	#endif /* _BABELTRACE_PRIO_HEAP_H */