1 /* $NetBSD: minheap-internal.h,v 1.2 2013/04/12 18:11:15 joerg Exp $ */ 2 /* 3 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 4 * 5 * Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 #ifndef _MIN_HEAP_H_ 30 #define _MIN_HEAP_H_ 31 32 #include "event2/event-config.h" 33 #include "event2/event.h" 34 #include "event2/event_struct.h" 35 #include "event2/util.h" 36 #include "util-internal.h" 37 #include "mm-internal.h" 38 39 typedef struct min_heap 40 { 41 struct event** p; 42 unsigned n, a; 43 } min_heap_t; 44 45 static inline void min_heap_ctor(min_heap_t* s); 46 static inline void min_heap_dtor(min_heap_t* s); 47 static inline void min_heap_elem_init(struct event* e); 48 static inline int min_heap_elt_is_top(const struct event *e); 49 static inline int min_heap_elem_greater(struct event *a, struct event *b); 50 static inline int min_heap_empty(min_heap_t* s); 51 static inline unsigned min_heap_size(min_heap_t* s); 52 static inline struct event* min_heap_top(min_heap_t* s); 53 static inline int min_heap_reserve(min_heap_t* s, unsigned n); 54 static inline int min_heap_push(min_heap_t* s, struct event* e); 55 static inline struct event* min_heap_pop(min_heap_t* s); 56 static inline int min_heap_erase(min_heap_t* s, struct event* e); 57 static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e); 58 static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e); 59 60 static inline int min_heap_elem_greater(struct event *a, struct event *b) 61 { 62 return evutil_timercmp(&a->ev_timeout, &b->ev_timeout, >); 63 } 64 65 static inline void min_heap_ctor(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; } 66 static inline void min_heap_dtor(min_heap_t* s) { if (s->p) mm_free(s->p); } 67 static inline void min_heap_elem_init(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; } 68 static inline int min_heap_empty(min_heap_t* s) { return 0u == s->n; } 69 static inline unsigned min_heap_size(min_heap_t* s) { return s->n; } 70 static inline struct event* min_heap_top(min_heap_t* s) { return s->n ? *s->p : 0; } 71 72 static inline int min_heap_push(min_heap_t* s, struct event* e) 73 { 74 if (min_heap_reserve(s, s->n + 1)) 75 return -1; 76 min_heap_shift_up_(s, s->n++, e); 77 return 0; 78 } 79 80 static inline struct event* min_heap_pop(min_heap_t* s) 81 { 82 if (s->n) 83 { 84 struct event* e = *s->p; 85 min_heap_shift_down_(s, 0u, s->p[--s->n]); 86 e->ev_timeout_pos.min_heap_idx = -1; 87 return e; 88 } 89 return 0; 90 } 91 92 static inline int min_heap_elt_is_top(const struct event *e) 93 { 94 return e->ev_timeout_pos.min_heap_idx == 0; 95 } 96 97 static inline int min_heap_erase(min_heap_t* s, struct event* e) 98 { 99 if (-1 != e->ev_timeout_pos.min_heap_idx) 100 { 101 struct event *last = s->p[--s->n]; 102 unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2; 103 /* we replace e with the last element in the heap. We might need to 104 shift it upward if it is less than its parent, or downward if it is 105 greater than one or both its children. Since the children are known 106 to be less than the parent, it can't need to shift both up and 107 down. */ 108 if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last)) 109 min_heap_shift_up_(s, e->ev_timeout_pos.min_heap_idx, last); 110 else 111 min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last); 112 e->ev_timeout_pos.min_heap_idx = -1; 113 return 0; 114 } 115 return -1; 116 } 117 118 static inline int min_heap_reserve(min_heap_t* s, unsigned n) 119 { 120 if (s->a < n) 121 { 122 struct event** p; 123 unsigned a = s->a ? s->a * 2 : 8; 124 if (a < n) 125 a = n; 126 if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p))) 127 return -1; 128 s->p = p; 129 s->a = a; 130 } 131 return 0; 132 } 133 134 static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e) 135 { 136 unsigned parent = (hole_index - 1) / 2; 137 while (hole_index && min_heap_elem_greater(s->p[parent], e)) 138 { 139 (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index; 140 hole_index = parent; 141 parent = (hole_index - 1) / 2; 142 } 143 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; 144 } 145 146 static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e) 147 { 148 unsigned min_child = 2 * (hole_index + 1); 149 while (min_child <= s->n) 150 { 151 min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]); 152 if (!(min_heap_elem_greater(e, s->p[min_child]))) 153 break; 154 (s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index; 155 hole_index = min_child; 156 min_child = 2 * (hole_index + 1); 157 } 158 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; 159 } 160 161 #endif /* _MIN_HEAP_H_ */ 162