1 /* 2 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 3 * 4 * Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #ifndef MINHEAP_INTERNAL_H_INCLUDED_ 29 #define MINHEAP_INTERNAL_H_INCLUDED_ 30 31 #include "event2/event-config.h" 32 #include "evconfig-private.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_empty_(min_heap_t* s); 50 static inline unsigned min_heap_size_(min_heap_t* s); 51 static inline struct event* min_heap_top_(min_heap_t* s); 52 static inline int min_heap_reserve_(min_heap_t* s, unsigned n); 53 static inline int min_heap_push_(min_heap_t* s, struct event* e); 54 static inline struct event* min_heap_pop_(min_heap_t* s); 55 static inline int min_heap_adjust_(min_heap_t *s, struct event* e); 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_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e); 59 static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e); 60 61 #define min_heap_elem_greater(a, b) \ 62 (evutil_timercmp(&(a)->ev_timeout, &(b)->ev_timeout, >)) 63 64 void min_heap_ctor_(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; } 65 void min_heap_dtor_(min_heap_t* s) { if (s->p) mm_free(s->p); } 66 void min_heap_elem_init_(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; } 67 int min_heap_empty_(min_heap_t* s) { return 0u == s->n; } 68 unsigned min_heap_size_(min_heap_t* s) { return s->n; } 69 struct event* min_heap_top_(min_heap_t* s) { return s->n ? *s->p : 0; } 70 71 int min_heap_push_(min_heap_t* s, struct event* e) 72 { 73 if (min_heap_reserve_(s, s->n + 1)) 74 return -1; 75 min_heap_shift_up_(s, s->n++, e); 76 return 0; 77 } 78 79 struct event* min_heap_pop_(min_heap_t* s) 80 { 81 if (s->n) 82 { 83 struct event* e = *s->p; 84 min_heap_shift_down_(s, 0u, s->p[--s->n]); 85 e->ev_timeout_pos.min_heap_idx = -1; 86 return e; 87 } 88 return 0; 89 } 90 91 int min_heap_elt_is_top_(const struct event *e) 92 { 93 return e->ev_timeout_pos.min_heap_idx == 0; 94 } 95 96 int min_heap_erase_(min_heap_t* s, struct event* e) 97 { 98 if (-1 != e->ev_timeout_pos.min_heap_idx) 99 { 100 struct event *last = s->p[--s->n]; 101 unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2; 102 /* we replace e with the last element in the heap. We might need to 103 shift it upward if it is less than its parent, or downward if it is 104 greater than one or both its children. Since the children are known 105 to be less than the parent, it can't need to shift both up and 106 down. */ 107 if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last)) 108 min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, last); 109 else 110 min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last); 111 e->ev_timeout_pos.min_heap_idx = -1; 112 return 0; 113 } 114 return -1; 115 } 116 117 int min_heap_adjust_(min_heap_t *s, struct event *e) 118 { 119 if (-1 == e->ev_timeout_pos.min_heap_idx) { 120 return min_heap_push_(s, e); 121 } else { 122 unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2; 123 /* The position of e has changed; we shift it up or down 124 * as needed. We can't need to do both. */ 125 if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], e)) 126 min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, e); 127 else 128 min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, e); 129 return 0; 130 } 131 } 132 133 int min_heap_reserve_(min_heap_t* s, unsigned n) 134 { 135 if (s->a < n) 136 { 137 struct event** p; 138 unsigned a = s->a ? s->a * 2 : 8; 139 if (a < n) 140 a = n; 141 if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p))) 142 return -1; 143 s->p = p; 144 s->a = a; 145 } 146 return 0; 147 } 148 149 void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e) 150 { 151 unsigned parent = (hole_index - 1) / 2; 152 do 153 { 154 (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index; 155 hole_index = parent; 156 parent = (hole_index - 1) / 2; 157 } while (hole_index && min_heap_elem_greater(s->p[parent], e)); 158 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; 159 } 160 161 void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e) 162 { 163 unsigned parent = (hole_index - 1) / 2; 164 while (hole_index && min_heap_elem_greater(s->p[parent], e)) 165 { 166 (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index; 167 hole_index = parent; 168 parent = (hole_index - 1) / 2; 169 } 170 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; 171 } 172 173 void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e) 174 { 175 unsigned min_child = 2 * (hole_index + 1); 176 while (min_child <= s->n) 177 { 178 min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]); 179 if (!(min_heap_elem_greater(e, s->p[min_child]))) 180 break; 181 (s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index; 182 hole_index = min_child; 183 min_child = 2 * (hole_index + 1); 184 } 185 (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; 186 } 187 188 #endif /* MINHEAP_INTERNAL_H_INCLUDED_ */ 189