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