[babeltrace.git] / src / lib / prio-heap / prio-heap.h

#ifndef _BABELTRACE_PRIO_HEAP_H
#define _BABELTRACE_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 "common/macros.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 G_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.
 */
BT_HIDDEN
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
 */
BT_HIDDEN
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.
 */
BT_HIDDEN
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.
 */
BT_HIDDEN
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.
 */
BT_HIDDEN
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.
 */
BT_HIDDEN
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.
 */
BT_HIDDEN
extern int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src);

#endif /* _BABELTRACE_PRIO_HEAP_H */
Commit	Line	Data
	1	#ifndef _BABELTRACE_PRIO_HEAP_H
	2	#define _BABELTRACE_PRIO_HEAP_H
	3
	4	/*
	5	* Static-sized priority heap containing pointers. Based on CLRS,
	6	* chapter 6.
	7	*
	8	* Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	9	*
	10	* Permission is hereby granted, free of charge, to any person obtaining a copy
	11	* of this software and associated documentation files (the "Software"), to deal
	12	* in the Software without restriction, including without limitation the rights
	13	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	14	* copies of the Software, and to permit persons to whom the Software is
	15	* furnished to do so, subject to the following conditions:
	16	*
	17	* The above copyright notice and this permission notice shall be included in
	18	* all copies or substantial portions of the Software.
	19	*
	20	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	21	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	23	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	24	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	25	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	26	* SOFTWARE.
	27	*/
	28
	29	#include <unistd.h>
	30	#include "common/macros.h"
	31
	32	struct ptr_heap {
	33	size_t len, alloc_len;
	34	void **ptrs;
	35	int (gt)(void a, void *b);
	36	};
	37
	38	#ifdef DEBUG_HEAP
	39	void check_heap(const struct ptr_heap *heap);
	40	#else
	41	static inline
	42	void check_heap(const struct ptr_heap *heap)
	43	{
	44	}
	45	#endif
	46
	47	/**
	48	* bt_heap_maximum - return the largest element in the heap
	49	* @heap: the heap to be operated on
	50	*
	51	* Returns the largest element in the heap, without performing any modification
	52	* to the heap structure. Returns NULL if the heap is empty.
	53	*/
	54	static inline void bt_heap_maximum(const struct ptr_heap heap)
	55	{
	56	check_heap(heap);
	57	return G_LIKELY(heap->len) ? heap->ptrs[0] : NULL;
	58	}
	59
	60	/**
	61	* bt_heap_init - initialize the heap
	62	* @heap: the heap to initialize
	63	* @alloc_len: number of elements initially allocated
	64	* @gt: function to compare the elements
	65	*
	66	* Returns -ENOMEM if out of memory.
	67	*/
	68	BT_HIDDEN
	69	extern int bt_heap_init(struct ptr_heap *heap,
	70	size_t alloc_len,
	71	int gt(void a, void b));
	72
	73	/**
	74	* bt_heap_free - free the heap
	75	* @heap: the heap to free
	76	*/
	77	BT_HIDDEN
	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	BT_HIDDEN
	90	extern int bt_heap_insert(struct ptr_heap heap, void p);
	91
	92	/**
	93	* bt_heap_remove - remove the largest element from the heap
	94	* @heap: the heap to be operated on
	95	*
	96	* Returns the largest element in the heap. It removes this element from the
	97	* heap. Returns NULL if the heap is empty.
	98	*/
	99	BT_HIDDEN
	100	extern void bt_heap_remove(struct ptr_heap heap);
	101
	102	/**
	103	* bt_heap_cherrypick - remove a given element from the heap
	104	* @heap: the heap to be operated on
	105	* @p: the element
	106	*
	107	* Remove the given element from the heap. Return the element if present, else
	108	* return NULL. This algorithm has a complexity of O(n), which is higher than
	109	* O(log(n)) provided by the rest of this API.
	110	*/
	111	BT_HIDDEN
	112	extern void bt_heap_cherrypick(struct ptr_heap heap, void *p);
	113
	114	/**
	115	* bt_heap_replace_max - replace the the largest element from the heap
	116	* @heap: the heap to be operated on
	117	* @p: the pointer to be inserted as topmost element replacement
	118	*
	119	* Returns the largest element in the heap. It removes this element from the
	120	* heap. The heap is rebalanced only once after the insertion. Returns NULL if
	121	* the heap is empty.
	122	*
	123	* This is the equivalent of calling bt_heap_remove() and then bt_heap_insert(), but
	124	* it only rebalances the heap once. It never allocates memory.
	125	*/
	126	BT_HIDDEN
	127	extern void bt_heap_replace_max(struct ptr_heap heap, void *p);
	128
	129	/**
	130	* bt_heap_copy - copy a heap
	131	* @dst: the destination heap (must be allocated)
	132	* @src: the source heap
	133	*
	134	* Returns -ENOMEM if out of memory.
	135	*/
	136	BT_HIDDEN
	137	extern int bt_heap_copy(struct ptr_heap dst, struct ptr_heap src);
	138
	139	#endif /* _BABELTRACE_PRIO_HEAP_H */