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1eb0c69c MD |
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 | ||

23 | #include <unistd.h> | |

24 | ||

25 | struct ptr_heap { | |

26 | size_t len, alloc_len; | |

27 | void **ptrs; | |

28 | int (*gt)(void *a, void *b); | |

29 | }; | |

30 | ||

eacd552c MD |
31 | #ifdef DEBUG_HEAP |

32 | void check_heap(const struct ptr_heap *heap); | |

33 | #else | |

34 | static inline | |

35 | void check_heap(const struct ptr_heap *heap) | |

36 | { | |

37 | } | |

38 | #endif | |

39 | ||

1eb0c69c MD |
40 | /** |

41 | * heap_maximum - return the largest element in the heap | |

42 | * @heap: the heap to be operated on | |

43 | * | |

44 | * Returns the largest element in the heap, without performing any modification | |

45 | * to the heap structure. Returns NULL if the heap is empty. | |

46 | */ | |

47 | static inline void *heap_maximum(const struct ptr_heap *heap) | |

48 | { | |

eacd552c | 49 | check_heap(heap); |

1eb0c69c MD |
50 | return heap->len ? heap->ptrs[0] : NULL; |

51 | } | |

52 | ||

53 | /** | |

54 | * heap_init - initialize the heap | |

55 | * @heap: the heap to initialize | |

56 | * @alloc_len: number of elements initially allocated | |

57 | * @gt: function to compare the elements | |

58 | * | |

59 | * Returns -ENOMEM if out of memory. | |

60 | */ | |

61 | extern int heap_init(struct ptr_heap *heap, | |

62 | size_t alloc_len, | |

63 | int gt(void *a, void *b)); | |

64 | ||

65 | /** | |

66 | * heap_free - free the heap | |

67 | * @heap: the heap to free | |

68 | */ | |

69 | extern void heap_free(struct ptr_heap *heap); | |

70 | ||

71 | /** | |

72 | * heap_insert - insert an element into the heap | |

73 | * @heap: the heap to be operated on | |

74 | * @p: the element to add | |

75 | * | |

76 | * Insert an element into the heap. | |

77 | * | |

78 | * Returns -ENOMEM if out of memory. | |

79 | */ | |

80 | extern int heap_insert(struct ptr_heap *heap, void *p); | |

81 | ||

82 | /** | |

83 | * heap_remove - remove the largest element from the heap | |

84 | * @heap: the heap to be operated on | |

85 | * | |

86 | * Returns the largest element in the heap. It removes this element from the | |

87 | * heap. Returns NULL if the heap is empty. | |

88 | */ | |

89 | extern void *heap_remove(struct ptr_heap *heap); | |

90 | ||

91 | /** | |

92 | * heap_cherrypick - remove a given element from the heap | |

93 | * @heap: the heap to be operated on | |

94 | * @p: the element | |

95 | * | |

96 | * Remove the given element from the heap. Return the element if present, else | |

97 | * return NULL. This algorithm has a complexity of O(n), which is higher than | |

98 | * O(log(n)) provided by the rest of this API. | |

99 | */ | |

100 | extern void *heap_cherrypick(struct ptr_heap *heap, void *p); | |

101 | ||

102 | /** | |

103 | * heap_replace_max - replace the the largest element from the heap | |

104 | * @heap: the heap to be operated on | |

105 | * @p: the pointer to be inserted as topmost element replacement | |

106 | * | |

107 | * Returns the largest element in the heap. It removes this element from the | |

108 | * heap. The heap is rebalanced only once after the insertion. Returns NULL if | |

109 | * the heap is empty. | |

110 | * | |

111 | * This is the equivalent of calling heap_remove() and then heap_insert(), but | |

112 | * it only rebalances the heap once. It never allocates memory. | |

113 | */ | |

114 | extern void *heap_replace_max(struct ptr_heap *heap, void *p); | |

115 | ||

116 | #endif /* _BABELTRACE_PRIO_HEAP_H */ |

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